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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Restorative Dentistry and Endodontics
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Journal DOI :
The Korean Academy of Conservative Dentistry
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Volume & Issues
Volume 23, Issue 2 - Dec 1998
Volume 23, Issue 1 - Apr 1998
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A STUDY OF PHYSICAL PROPERTIES OF COMPOSITE RESIN POLYMERIZATION WITH ARGON LASER
Kim, Deok ; Min, Byung-Soon ; Choi, Ho-Young ; Park, Sang-Jin ; Choi, Gi-Woon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 1~19
After polymerizing composite resin with argon laser and visible light, four test, to be concretely, measurement of compressive strength using Instron testing machine, surface microhardness using Rockwell hardness tester, quantitative analysis of residual monomer using HPLC and analysis of degree of conversion using FTIR, were accomplished. Test groups were a sort of specimen with 3mm diameter, 4mm thickness for measuring compressive strength, two sort of specimen with 7mm diameter, 2mm and 3mm thickness for measuring surface microhardness, quantitative analysing of residual monomer after curing and measuring the degree of conversion, each were divided by six groups according to the condition of light exposure. In case of argon laser, in 1.0W and 0.5W output, the exposure time for specimen were 5 sec, 10 sec respectiyely. In case of visible light, the exposure time for specimen were 20 sec, 40 sec respectively. The test were accomplished and following results were obtained. 1. Compressive strength of composite resin was the highest in the group of 1 W output, exposing for 10 sec with argon laser, followed by the group of 0.5W, exposing for 10 sec with argon laser, the group of exposing for 40 sec with visible light. But there were statistically no significant difference between these three groups(p>0.05). 2. Surface microhardness of composite resin wasn't significantly affected by light curing conditions. 3. BIS-GMA within residual monomer was least detected in the group of exposing for 40 sec. TEGDMA was least detected in the group of 1 W output, exposing for 10 sec with argon laseboth 2mm and 3mm thickness specimen. 4. The degree of conversion of all groups in the 2mm thickness specimen were more than 50%, similar to each other but in the group of 1W, exposing 10 sec with argon laser the degree of conversion was highest in the 3mm thickness specimen. 5. Argon laser could make composite resin to has similar properties with 25% lesser exposure time than visible light.
HEALING PROCESS OF DENTAL HARD TISSUES AND PULP TISSUE AFTER LASER IRRADIATION
Kim, Chul-Soon ; Min, Byung-Soon ; Choi, Ho-Young ; Park, Sang-Jin ; Choi, Gi-Woon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 20~42
The present study was designed to understand the basic principles of the laser system and to assess the optimal coditions of the Nd:YAG laser irradiation system in order to expand the use of the laser system in the dental field. The laser system used in this study was a pulsed-wave output type and the power level is 9 watts. The incisors of developing rats were irradiated with the laser system explained above for 0.5, 1, and 2 seconds giving energy density 71, 167, and 215 J/
respectively. The rats were sacrificed just after irradiation or 10 minutes and 10 days after irradiation. The specimens were examined with the stereoscope, light microscope and transmission electron microscope. The results are as follows: 1. The tissue removal efficiency (depth of the cavity formed) is increased with the energy density after Nd:YAG laser irradiation. 2. The carbonized area is increased with the energy density. Cracks and melted appearance are seen in all kinds of the energy densities. 3. The lacunae in the damaged alveolar bone by the laser irradiation were empty, while those in the newly formed bone were occupied with the osteocytes. The damaged alveolar bone was repaired by the osteoblasts and macrophages on the periphery of the bone matrix. 4. The damaged enamel was replaced by the loose connective tissues showing many kinds of cells. The ameloblasts were differntiated on the replaced loose connective tissue. 5. The damaged dentin was repaired by the irregular dentin formed by the odontoblasts differentiated from the mesenchymal cells migrated from the pulp core.
UREASE ACTIVITY OF STREPTOCOCCUS SALIVARIUS
Chung, Sang-Baek ; Choi, Ho-Young ; Min, Byung-Soon ; Park, Sang-Jin ; Lee, Jin-Yong ; Choi, Ki-Woon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 43~53
Dental caries is induced by organic acids produced by oral bacteria. In order to prevent dental caries, therefore, it is essential to maintain neutral pH in the oral cavity. Urea plays a major role in oral pH homeostasis. Urea is hydrolyzed by bacterial ureases to ammonia, causing a pH elevation. Streptococcus salivarius has been shown to be a major contribution to oral ureolysis. Synthesis of urease by S. salivarius appears to be constituitive, but can be greatly enhanced by low pH. It is, therefore, conceivable that ureolytic activity of S. salivarius from a carious lesion is greater than that of the bacterium from a healthy tooth. In the present study, urease activity of S. salivarius isolates from dental plaque of carious lesions was compared with that of the isolates from plaques of the teeth and the dorsum of the tongue; 45 S. salivarius strains were isofated from carious lesions(>C2) of 21 individuals with dental caries and 30 strains from 10 individuals without dental caries. The results were as follows: 1. All the 21 individuals with dental caries harbored ureolytic S. salivarius whereas 3 of 13 individuals without dental caries harbored non-ureolytic strains of S. salivarius. 2. All the 45 S. saliuarius isolates from carious lesions showed urease activity. In contrast, of 30 isolates from individuals without dental caries, 17 isolates(56.7%) did not demonstrate urease activity, or if any, very little(<5
/min/mg). 3. Urease activity of the isolates from carious lesions was greater than that of the isolates from individuals without dental caries : the urease activity ranged from 42 to
/min/mg and from 0 to
/min/mg, respectively. 4. At acid pH(5.5), the isolates which showed intermediate urease activity at pH 7.0 demonstrated even higher activity whereas the isolate with no or lower urease activity did not show any significant difference in their activity. However, the isolates with the greatest urease activity from both individuals with and without dental caries, exhibited a rather much lower urease activity at pH 5.5. The overall results suggest that isolates may have their own urease activity but the isolates exposed to chronic acidic environment of the carious lesion might elevate urease activity of S. salivarius, which in turn, might influence on survival of S. salivarius itself and other bacteria, establishing a new oral bacterial ecosystem.
EFFICIENCY OF DENTIN CUTTING AND ROOT -END RETROCAVITY PREPARATION USING ULTRASONIC DIAMOND INSTRUMENTS AND THEIR INFLUENCE ON TOOTH STRUCTURE
Lim, Choon-Hee ; Kim, Sung-Kyo ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 54~67
The purposes of this study were to evaluate the efficiency of dentin cutting and root-end cavity preparation, and to determine the incidence of tooth crack when root-end retrograde cavity preparation was done with. ultrasonic diamond instruments. To evaluate the efficiency of dentin cutting, ultrasonic diamond and stainless steel instruments were applied to 20 exposed bovine dentin surfaces perpendicularly or parallely at the low, and medium power settings for 1 minute (
, EIE, CA, U.S.A.). The resultant cavity depth was measured. To evaluate the efficiency of cavity preparation and to investigate the incidence of tooth crack, 165 mesiobuccal, distobuccal and palatal root-ends of extracted human maxillary first molars were resected by 3 mm perpendicularly to the long axis of tooth using a slow speed diamond saw after root canal preparation and filling. Retrocavities were prepared using a ultrasonic diamond instrument or a stainless steel one of the low- or medium power settings of 2 or 6. Time consumed and the number of strokes used for the cavity preparation were measured and the incidence of tooth cracks was evaluated under a stereomicroscope. The results were as follows: Both at the low and medium power settings, and both with perpendicularly- and parallely applied tips to dentin, diamond instruments showed higher dentin cutting efficiency than stainless steel ones did (p<0.01). When tips were applied to dentin perpendicularly, both diamond instrument and stainless steel one showed higher cutting efficiency with medium power setting than with low power one (p<0.01). Both at the low- and medium power settings, both diamond instrument and stainless steel one showed higher cutting efficiency when tips were applied perpendicularly to dentin surface than applied parallely (p<0.01). At the medium power setting, the number of stroke and time consumed were less with diamond instrument than with stainless steel one (p<0.05) for the retrograde cavity preparation. At the low power setting, diamond instrument induced less tooth cracks than stainless steel one did (p<0.01).
A STUDY ON BONE STRENGTH AND THE DEGREE OF CONVERSION OF DENTIN BONDING AGENTS
Kim, Byung-Hyun ; Kwon, Hyuk-Choon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 68~93
The physical properties of polymer are greatly influenced by the extent to which a resin cures. The presence of un reacted monomer can, have a plasticizing effect on the polymer, thereby altering the physical and mechanical properties of dentin bonding agent (DBA). If the DBA does not polymerize sufficiently, it will leave a weak bonding layer and lead to lower bond strength. The purpose of this study was to evaluate the shear bond strengths(SBS) and the degree of conversion (DC) of 4 commercialy avilable dentin bonding systems which are composed of 2 multi-bottle systems [Scotchbond Multi-Purpose (SMP), AeliteBond(AB)] and 2 onebottle systems [SingleBond(SB), One-Step(OS)]. For shear bond strength measurement, labial surfaces of freshly extracted bovine incisors were ground with # 600 grit SiC paper to expose dentin. Four different groups of samples were formed, with 10 samples. being made for each of the 4 commercial DBA in each group according to the curing sequences of DBA and overlayer thickness of composites: Group I (standard cure and 1mm thick composites) : The DBA was light cured and the composites of 1mm thickness was applied ; Group II (standard cure and 2mm thick composites) : The DBA was light cured and the composites of 2mm thickness was applied; Group III (simultaneous cure and 1mm thick composites) : The DBA was not light-cured and simultaneously cured with composites of 1mm thickness; Group N (simultaneous cure and 2mm thick composites) : The DBA was. not light-cured and simultaneously cured with composites of 2mm thickness. The SBS was measured immediately after the composites was bonded to the bovine dentin using an Instron machine. The DC of the DBA was examined in a thin film under simulated conditions of the experimental groups according to the curing sequences and overlayer thickness of composites in the SBS test. using a Fourier transform Infrared(FTIR) spectrometer. The following results were obtained from SBS tests and DC measurements 1. In SBS tests, the multi-bottle DBA(SMP, AB) had a generally higher bond strength values than the one bottle DBA(SB, OS). In DC measurements, the one bottle DBA(SB, OS) had a significantly higher DC than the multi-bottle DBA(SMP, AB). 2. In all DBAs except OS, there was no significant difference between the bond strength of group I (standard cure and 1mm thick composites) and that of group III (simultaneous cure and 1mm thick composites). SMP, SB in Group I had a significantly higher DC than those in group III, but AB, OS in group I had a significantly lower DC than those in group III 3. All DBAs in Goup II (standard cure and 2mm thick composites) had significantly higher bond strength and DC than those in Group N (simultaneous cure and 2mm thick composites). 4. In all DBAs, there was no significantly different SBS and DC between Group I and Group II, but all DBAs in Group III had significantly higher SBS and DC than those in Group IV.
A STUDY ON THE STRESS OF FILES AND CANAL TRANSPORTATION IN A CURVED CANAL
Park, Han-Soo ; Yoon, Soo-Han ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 94~109
The purpose of this study was to evaluate the effect of materials and sizes of files on canal transportation in a curved canal. The stress and the strain energy of files of two kinds of materials (stainless steel and NiTi) and five sizes (No. 20, 25, 30, 35 and 40) in a curved canal were analyzed by a finite element program, NASTRAN. Curved canals in transparent resin blocks were instrumented with the 10 kinds of files, and the degree of canal transportation obtained by double exposure technique of photography was compared with the analysis by the finite element method. The results were as follows : 1. The stress of a file in a curved canal increased from the file body to the file tip. 2. The stress of a stainless steel file was about 2.5 times greater than that of a same-sized NiTi file. 3. The stress distributions of files of an identical material were the same, and the strain energies of files of an identical material increased as the size of files increased. 4. The strain energy of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file. 5. The degree of canal transportation by a stainless steel file was greater than that by a same-sized NiTi file. The degree of canal transportation generally increased as the size of a file increased. 6. The degree of canal transportation of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file.
DEVELOPMENT OF A STORAGE SYSTEM FOR THE TREATMENT DATA AND IMAGE DATA IN DENTISTRY USING THE OPTICAL LASER CARD
Shin, Yong-Pil ; Lee, Chan-Young ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 110~140
One of the problems facing in all modern dental hospitals is the much efforts, manpower and space are needed to effectively sort and stack patients' charts of the various dental departments. In addition, the storage and prompt arrangement of x-ray films is also a problem. Therefore, if dental charts as well as films could be computerized, it would be easier to store and keep them; by data basing, many space, manpower and cost would be saved: data could also be effectively managed for the purpose of academic researches. This would be an epoch -making event in the development of dental hospital management. The purpose of this study is to develop a dental information processing program, that will be used to store dental treatment records and digital image data using a new record media, the optical card. The patients' charts from the dental hospital were selected. The treatment records of the chart were put into the treatment data -recording area of the program, and the digital images of various dental x-ray films were made with a scanner. These data were stored in the optical card and analyzed to get the following results: 1. In this program it is possible to put treatment records and image data into and out from the optical card, and it is impossible to correct and delete all data recorded on the optical card. 2. All data in the optical card system can be searched and analyzed on database. 3. The resolution of image data stored in optical card is above 5.9 lp/mm. 4, All data of dental charts used as samples, stored to optical cards, occupies average 14%, In conclusion, with the development of the storage system using the optical card, a dental patient's life-time treatment record can be stored in one optical card and used as a substitute for the dental chart.
MORPHOLOGIC CHANGE OF DENTIN SURFACE ACCORDING TO THE DIFFERENCE IN CONCENTRATION AND APPLICATION TIME OF PHOSPHORIC ACID
Kim, Myeong-Su ; Ohn, Young-Seok ; Lee, Kwang-Won ; Son, Ho-Hyun ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 141~161
The depth and patterns of demineralization according to the difference in concentration and application time of phosphoric acid were observed through the transmission electron microscope, and shear bond strengths to the acid -conditioned dentin were then measured and compared with the TEM results. To investigate the influence of polymer addition into the phosphoric acid and the effect of difference in concentration and application time of the acid, the specimens were randomly divided into 9 groups. Among the specimens, the exposed dentin surfaces were acid-conditioned with 10% polymer-thickened phosphoric acid(All Bond 2, Bisco, U.S.A.) and aqueous 10%, 20%, 30%, 40% phosphoric acid for 20 seconds, The rest of the specimens were acid-conditioned with 10% phosphoric acid for 15s, 30s, 60s, 120s respectively. The specimens were immersed in 4% glutaraldehyde in 0.1M sodium cacodylate buffer and postfixed with 1 % osmium tetroxide without decalcification and then observed under a JEOL Transmission Electron Microscope(JEM 1200 EX II, Japan). After the specimens were acid-conditioned as the above, primer and adhesive resin were applied to blot-dried dentin and shear bond strengths were then measured and analysed. The results were as follows : 1. The intertubular demineralization depth of 4.0-
in 10% polymer-thickened phosphoric acid gels was similar or slightly deeper than that of 4.0-
in aqueous 10% phosphoric acid solution. 2. The intertubular demineralization depth of aqueous 20%, 30% and 40% phosphoric acid solution was 6.5-
respectively. It showed that the depth of dentin demineralization is partly related to the concentration of phosphoric acid solution. 3. The intertubular demineralization depth of aqueous 10% phosphoric acid solution in application time for 15s, 30s, 60s and 120s was 2.5-
respectively. It showed that the depth of dentin demineralization is directly related to the application time of phosphoric acid solution. 4. The partially demineralized dentin layer between demineralized collagen layer and unaffected dentin was showed to a width of 0.5-
in lower concentration groups treated with aqueous 10% phosphoric acid for 20s, 60s, 120s and 20% phosphoric acid for 20s. 5. The demineralization effect at the border of intertubular-peritubular junction was less evident than that in the peritubular and intertubular dentin. The collagen fibers in the intertubular dentin had a random orientation, whereas those that lined the tubules were circumferentially aligned. The cross-linkage of dentinal collagen in demineralized collagen layer was clearly seen. 6. A statistically significant difference of bond strengths according to the difference in phosphoric acid concentration did not exist among the groups treated with 10%, 20%, 30% and 40% acid solution (P>0.05). However, bond strengths to the treated dentin with 10% phosphoric acid solution for 30s were significantly higher than that for 120s (P<0.05).
FINITE ELEMENT ANALYSIS OF STRESS DISTRIBUTION IN ROOT-END RESECTED TEETH
Lee, Se-Joon ; Choi, Ho-Young ; Min, Byung-Soon ; Park, Sang-Jin ; Choi, Gi-Woon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 163~174
The purpose of this study is to evaluate the distribution of stress in the root end resected teeth. The finite element method was used to compare stresses along the root and retrograde filling material in seven two-dimensional models of mandibular 2nd premolar. Each model was endodontic treatment and gold crown' restoration. Each model divided with amagam core restoration or gold casting post restoration. Thus each model divided with shape of root end resection, depth of retropreparation and exposure length of root in the bony cavity. The seven models were classified as in the table 1 below. A load of 500N was applied
diagonally on the lingual slope of the buccal cusp. These mode were analyzed with two dimensional finite element methods. The results of this study were as follows : 1. The maximum tensile stress along the inner canal wall was shown on the model 7. 2. When the model 1 was compared with the model 5, the maximum tensile stress along the inner canal wall showed the model 1. 3. Less equivalent stress was shown on the model 6 and more equivalent stress was shown on the model 4. 4. More shear stress was shown on the retrograde filling material of the model 7. 5. The models with increased length of exposed root in the bony cavity demonstrated a gradual increase to the tensile stress in X direction which occurred approximately a boundary between the bone and exposed root in' the bony cavity. 6. The model which had a case of matching the apex of post and a boundary between the bone and exposed root in the bony cavity demonstrated more increase tensile stress in X direction than other models.
THE EFFECT OF POLYPHOSPHATE ON THE GROWTH OF PORPHYROMONAS ENDODONTALIS
Choi, Sung-Baik ; Choi, Ho-Young ; Min, Byung-Soon ; Park, Sang-Jin ; Lee, Jin-Yong ; Choi, Ki-Woon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 175~182
Polyphosphate has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of polyphosphate on the growth of Porphyromonas endodontalis, a gram negative endodontopathic bacterium. Porphyromonas endodontalis ATCC 35406 was grown in the presence of polyphosphates with different chain lengths. Inhibitory effect of each polyphosphate which was added at the beginning or during the culture, was determined by measuring the optical density of the bacterial cell at 540nm and by viable cell count. The results from this study were as follows : 1. Polyphosphates were shown the growth inhibition of the Porphyromonas endodontalis. 2. The minimal inhibitory concentration(MIC) of polyphosphate was observed to be 0.04%. 3. Polyphosphates with chain lengths of 25 and 75 demonstrated the greatest inhibitory effect on the growth of Porphyromonas endodontalis. 4. Polyphosphates are bactericidal to Porphyromonas endodontalis, demonstrating the growth inhibition of the bacterium. The overall results suggest that use of polyphosphate may affect the growth of Porphyromonas endodontalis. Further studies will be needed to confirm the effect of, polyphosphate.
A STUDY ON THE BONDING OF ESTHETIC RESTORATIVE MATERIALS TO BLEACHED BOVINE ENAMEL
Rew, Kyung-Hee ; Park, Sang-Jin ; Min, Byung-Soon ; Choi, Ho-Young ; Choi, Gi-Woon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 183~196
The purpose of this study was to determine the effect of bleaching technique on the shear bond strength of esthetic restorative materials to bovine enamel. The bleaching agent was used 35%
(Hi-Lite, Shofu, U.S.A.). Experimental groups were divided into two divisions as group A and B. Experimental A groups for the effect of number of bleaching were as follows ; Group Al : no bleaching Group A2 : bleaching 1 time ( for 5 minutes ) Group A3 : bleaching 3 times ( each for 5 minutes ) Group A4 : bleaching 6 times ( each for 5 minutes ) Group A5 : bleaching 9 times ( each for 5 minutes ) Experimental B groups for the effect of storage period in artificial saliva were as follows ; Group B1 : not stored in artificial saliva after bleaching Group B2 : stored in artificial saliva for 1 day after bleaching Group B3 : stored in artificial saliva for 1 week after bleaching Group B4 : stored in artificial saliva for 2 weeks after bleaching Group B5 : stored in artificial saliva for 4 weeks after bleaching Composite resin and glass ionomer cement were bonded to all specimens, and the shear bond strength between enamel and r~storative material were measured in Instron Universal Testing Machine(Instron, 4467, U.S.A,), Additionally, the bleached enamel specimens were examed after etching with 37.4%
for 1 min under SEM(S-2300, Hitachi Co., Japan) to observe the effect of bleaching procedure on enamel surface morphology. The result were as follows ; 1. In SEM findings, bleached bovine enamel was found to be superficially rough. 2. In bleached bovine enamel, the effect of acid etching was reduced with the increase of number of bleaching. 3. The mean shear bond strength of composite resin and glass ionomer cement to bleached enamel surface tended to be lower than those to non-bleached enamel surface. 4. With the increase of number of bleaching, the shear bond strength of composite resin and glass ionomer cement to bleached enamel were progressively decreased. 5. Increasing the, storage period in artificial saliva after bleaching, the shear bond strength of composite resin and glass ionomer cement to bleached enamel were progressively increased. 6. The mean shear bond strength of glass ionomer cement to bleached bovine enamel tended to be clearly lower than that of composite resin.
A STUDY ON THE BOND OF AESTHETIC RESTORATIVE MATERIALS TO FLUORIDE TREATED ROOT DENTIN
Tak, Heung-Soo ; Park, Sang-Jin ; Min, Byung-Soon ; Choi, Ho-Young ; Choi, Ki-Woon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 197~212
The purpose of this study was to evaluate the effects of fluoride application on the aspect of shear bond strength of three aesthetic restorative materials to dentin. One light-cured composite resin(Palfique Esterite) and two light-cured glass ionomer cements(Fuji II LC and Compoglass)were used in this study. 120 permanent molars were used for this study. The teeth were extracted due to the origin of periodontal disease. The crowns of all teeth were removed, and the remaining roots were embedded in epoxy resin. The mesial or distal surfaces of roots were ground flat to expose dentin and polished on wet 320-, 400-, and 600 grit SIC papers for a total of 120 prepared flat root dentin surfaces. The prepared samples were divided into six groups. Group 1, 3, and 5 were control groups and group 2, 4, and 6 were experimental groups. Sixty samples for experimental groups were treated with 2% NaF solution for 5 minutes. Group 1 and 2 were bonded with Plafique Esterite, group 3 and 4 were bonded with Fuji II LC, and group 5 and 6 were bonded with Compoglass. After 24 hours water storage at
, all samples were subjected to a shear to fracture with Instron universal testing machine(No.4467) at 1.0 mm/min displacement rate. Dentin surfaces treated with each conditioners before bonding and interfacial layers between dentin and aesthetic restorative materials were observed under Scanning Electron Microscope(Hitachi S-2300) at 20Kvp. The data were evaluated statistically at the 95% confidence level with ANOVA test. The result were as follows; 1. Among the control groups, group 1 showed strongest bond strength and group 3 showed weakest. 2. Among the experimental groups, group 2 showed strongest bond strength and group 6 showed weakest. 3. Statistical analysis of the data showed that pretreatment of dentin with 2% NaF solution significantly decreased the bond strength of three aesthetic restorative materials to dentin(P<0.05). 4. SEM findings of fluoride treated dentin surfaces (2, 4, 6 group) demonstrated dentin surfaces covered with fluoridated reaction products. 5. Except group 4 and 6, resin tags were formed in all groups.
THE EFFECT OF OBTURATION TECHNIQUES ON THE APICAL MICROLEAKAGE OF ROOT CANALS
Yoo, Hyung-Jun ; Hong, Chan-Ui ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 213~222
Advisor: Prof. The quality of apical seal obtained with 3 different gutta-percha obturation techniques was compared in 49 recently extracted single rooted teeth. The root canals were instrumented using step-back technique and obturated with laterally condensed gutta-percha, Continuous Wave gutta-percha, and hybrid technique. Teeth were suspended in black India ink for 7 days, cleared, and then examined under a stereomicroscope at
magnification. The results were as follows; 1. All experimental groups produced favorable apical seal. 2. The mean leakage was
for group 1,
for group 2, and
for froup 3, but there was no statistical difference amoung them. Within the limits of the results of this experiment, the Continuous Wave gutta-percha obturation technique demonstrated relatively favorable apical sealing effect and shorter obturation time. Thus, it is thought that this obturation technique is a acceptable method for clinical use but further studies on this metter should be conducted.
COLOR ANALYSIS OF THE NATURAL TEETH WITH A MODIFIED INTRAORAL SPECTROPHOTOMETER
Cho, Kyung-Mo ; Shin, Dong-Hoon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 223~235
The recognition of the esthetics as well as their function of the teeth in the dental field is growing. Evaluating the esthetics of a tooth concerns shape, texture, and color. And among these, color has been the most difficult element to make natural expression. Color is a very subjective element affected by many different factor like light source, object, observer. Numerous efforts to quantifying color has been made. Currently the use of colorimeter and spectrophotometercolor that the color measuring device has been suggested. In this study, the normal range of the tooth color in canines, lateral incisors and central incisors for Koreans was evaluated with a modified spectrophotometer for intraoral use. The color differences in terms of teeth positions, age and area within the tooth was evaluated and comparatively analyzed. Results were as follow ; 1. In all age groups, the central incisors are most bright and least yellowish opposit to the canines are most dark and yellowish. The central incisors and lateral incisors showed the similar color patterns. 2. In the comparison between gender, it showed that in the 10' s group male have more yellowish, the 20's female have lighter and more redness, the 30's indicated more redness in female and in the 40's the lightness is more in female. 3. With aging, there was no significant change in
coordinates but a shift was in
to yellowish in the 30' sand 40's in central incisors. Lateral incisors and canines showed a lighter and more yellowish tooth color with an irregular change of color coordinate in
. 4. In all teeth the middle and cervical portion showed close correlation with over 0.7(0.05>p) but color (
) showed higher correlation than lightness(
). 5. It has been shown that through the regression test the cervical color could be calculated by the middle color value.
A STUDY ON THE APICAL MICROLEAKAGE OF GLASS IONOMER ROOT CANAL SEALER
Lee, So-Young ; Hong, Chan-Ui ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 236~246
The purpose of this study was to compare the degree of micro- leakage of new glass ionomer root canal sealer, Ketac-Endo(ESPE Co., Seefeld, Germany) with that of AH-26(De Trey Co., Ltd., U.S.A.). Root canal treatment using K -file, H -file, Gate Glidden drill was conducted on 49 extracted single-rooted teeth. 45 teeth were randomly divided into 3 experimental groups(15 teeth per group) and 4 teeth were used as the control group. Group 1 was used AH -26 sealer with the lateral condensation method for canal filling, group 2 was used Ketac-Endo with the single cone method and group 3 was used Ketac-Endo with the lateral condensation method. The control group was obturated with the single cone method without sealer. The teeth were covered with two coats of nail varnish after 48 hours of obturation. The teeth were immersed in India ink for 1 week and cleaned with methyl salicylate and then the degree of dye penetration were measured with stereomicroscope. The data were analyzed statistically by one-way ANOVA. The results were as follows: 1. 7 teeth in group 1, 5 in group 2, and 3 in group 3, were showed evidence of microleakage implying appropriate canal filling. 2, The mean average of microleakage was
in group 1,
in group 2.
in group 3, showing that canal filling using the lateral condensation canal filling method with Ketac-Endo showed the least microleakage and using the single cone method with Ketac-Endo showed the largest amount of microleakage, 3. There were no statistically significant difference in the variation of microleakage among groups. From the results above, Ketac-Endo which has the advantage of glass ionomer, whether using the single cone method or the lateral condensation method, showed similar results as AH-26, but for clinical application it is thought that were studies on the properties of Ketac-Endo should be followed.
A STUDY ON THE SHEAR BOND STRENGTH OF COMPOMER ACCORDING TO SURFACE TREATMENT
Kim, Jin-Yong ; Hong, Chan-Ui ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 247~256
To evalutate the change in shear bond strength according to dentin surface treatment, 4 materials were divided into control group(A) and experimental group(B). Group A was treated according to the instruction of manufacture. Group B was treated with 32% phosphoric acid. After dentin surface treatment, each material was bonded and stored in 100% humidity during 7 days, and then, the shear bond strength was evaluated. The results were as follows: 1. In the case of treatment according to the instruction of manufacture, the shear bond strength according to material showed Z-100 to be highest with 12.42 MPa, Compoglass had the lowest shear bond strength with 4.23 MPa and there was significant difference between Compoglass and Z-100, Dyract (p<0.01). 2. The group treated with 32% phosphoric acid showed lower shear bond strength than that of the group treated according to the instruction of manufacture but there was no statistical significance. 3. As a result of observation under SEM, the fracture pattern was a mixture of cohesive and adhesive failure in group 1, and there was more adhesive failure in group 2, and in group 3 and 4 there was cohesive failure of material or tooth structure. From the results above Dyract showed shear bond strength levels between resin and resin -modified glass ionomer but Compoglass showed much lower shear bond strength than that of resin-modified glass ionomer thus indicating that even though they are the same type of material they show evident differences in physical properties. And it is thought that the treatment of dentin surface with phosphoric acid did not increase the shear bond strength, unlike enamel.
THE EFFECT OF NiTi ROTARY INSTRUMENTATION ON THE CHANGE OF APICAL ROOT CANAL CURVATURE
Lim, Hyoung-Tae ; Hong, Chan-Ui ; Cho, Yong-Bum ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 257~268
During cleaning and shaping of narrow and curved canals, it is very difficult or nearly impossible to maintain the original canal shape. Procedural accidents such as, ledge, zipping, perforation, and instrument breakage are frequently occurred and even may lead to failure of endodontic therapy. To prevent these kinds of accidents, various instrumentation techniques and materials have been introduced. Recently some nickel titanium (NiTi) files are introduced and it is reported that These NiTi files created rounder preparations with less transportation than conventional instruments in curved canals. This study compared the change of the canal curvature and procedural accidents after instrumentation produced by stainless steel K-flexo file, and NiTi rotary files (Profile 29 and Quantec 2000). Thirty narrow and curved canals (25-45 degree) of extracted human molars were randomly divided into three groups. In group 1, canals were instrumented using a step-back and watch-winding/pull motion with K-flexo files. In group 2, canals were prepared with Profile 29. Group 3, canals were prepared with Quantec 2000 files. Before and after preparation of canals, periapical radiographs were taken and scanned. The change of canal curvature were measured using Photoshop 4.0 program and the incidence of procedural accidents were also evaluated. The results were as follows: 1. All group showed some loss of canal curvature after instrumentation. 2. Average loss of canal curvature was
degree for group 1,
degree for group 2, and
degree for group 3. All group There was significant change in curvature between before and after instrumentation (p<0.05). But there was no statistical difference amoung 3 groups. 3. In group I, there were no procedural accidents, such as ledging, perforation, or instrument fracture. In group 2, two cases of ledge and one case of instrument fracture were produced Goup 3, each one case of ledge, perforation and instrument fracture were occurred. Whthin the limits of above results, It seems that NiTi rotary instrumentation is not All Mighty and if we use uncarefully, it is more dangerous to produce some procedural accidents than conventional hand files. But more studies should be taken to evaluate the exact effects of NiTi rotary instrumentations.
COMPARISON OF MICROLEAKAGE OF GALLIUM ALLOY AND AMALGAM RESTORATION
Lee, Min-Ho ; Lee, Hee-Joo ; Hur, Bock ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 269~277
This in vitro study compared the microleakage of 4 lining conditions when used with Gallium alloy GF II and Valiant PhD. Class V cavity was prepared on both buccal and lingual surface of 80 extracted human premolar & molar teeth with one margin in enamel and another in dentin. Before restoration, prepared cavities were applied to no-liner, cavity varnish, Scotchbond multipurpose, and Superbond D-liner II plus according to manufacture's instructions. The restored teeth were stored in saline for 1 week, then thermocycled for 100 times, stained with 0.5% basic fuchsin dye for 1 day, sectioned, and observed using a light microscope. Following results were obtained. 1. The leakage value of Superbond-lined group showed significantly lower than that of nolined group on both margins of Valiant PhD(p<0.05). 2; There was no significant difference between the 4 lining conditions in Gallium alloy GF II (p>0.05). 3. When We make a comparison between Gallium alloy GF II and Valiant PhD under same lining conditions, the microleakage value of Gallium alloy GF II showed lower than that of Valiant PhD on occlusal & gingival margin(p<0.05) except for Superbond-lined group(p>0.05).
COMPARISON OF THE PHYSICAL PROPERTIES BETWEEN GALLIUM ALLOY AND HIGH COPPER AMALGAM ALLOYS
Kim, Hyeon-Cheol ; Lee, Hee-Joo ; Hur, Bock ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 278~287
The purpose of this study was to compare the physical properties between high copper amalgam and gallium restorative material. In this study, the specimens for the 4 experimatal groups (Valiant, Valiant PhD, Gallium Alloy GF II. Gallium Alloy GF II triturated with some addition of alcohol) were prepared in the manner of which stated in ADA specification No.1 for amalgam alloy. And then, measured and compared the value of compressive strength. creep, and dimensional change during hardening of each sample. The results were as follows: 1. In the compressive strength, the Valiant-lathe cut type high copper amalgam-had the highest value of strength(p<0.05), and the Valiant PhD-admixed type high copper amalgam-showed the higher value of strength than the Gallium Alloy GF II(p<0.05) but had no significant difference with Gallium Alloy GF II triturated with some addition of alcohol(p>0.05). 2. In the creep. the Valiant PhD showed the highest value of creep (p<0.05), but there was no significant difference between Gallium Alloy GF II and Valiant(p>0.05). 3. In the dimensional change during hardening, no two groups were significantly different at the 0.050 level. 4. There was no significant difference between Gallium Alloy GF II and the same material which was triturated with some addition of alcohol(p>0.05).
MARGINAL LEAKAGE OF CLASS 2 GLASS-IONOMER CEMENT RESTORATIONS NOT INVOLVING OCCLUSAL SURFACE
Lee, Young-Ran ; Hur, Bock ; Lee, Hee-Joo ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 288~295
The microleakage of direct-access Class 2 restorations was evaluated. Cavities were prepared at mesial and distal proximal enamel surfaces of 20 extracted human molars through buccal window. Prepared cavities were filled with Ketac-Fil, Ketac-Silver, and Fuji II LC, following manufacturer's instructions. 4 specimens of each restorations were made through sectioning 1/4 of bucco-lingual length mesio-distally after thermocycling between
and imerging 0.5% basic-fuchsin dye solution. Leakage at both occlusal and gingival margin of each specimen was scored 0 to 3 with stereomicroscope. The results were as follows: 1. At occlusal margin, leakage in Ketac-Fil group was more than Ketac-Silver and Fuji II LC group (ANOVA p<0.05) and there was no significant difference between Ketac-Silver and Fuji II LC group(p>0.05), and at gingival margin, there was no significant difference amang materials (p>0.05). 2. Occlusal margin leaked more than gingival margin in Ketac-Silver and Fuji II LC group (t-test p<0.05). 3. Leakage was different according to bucco-lingual location in Ketac-Fil and Fuji II LC group, and lingaul specimen exhibited more leakage(ANOVA p<0.05).
COMPARISON OF MARGINAL LEAKAGE OF CLASS 5 GIC RESTORATIONS ACCORDING TO CAVITY DESIGNS
Lee, Seon-Hwa ; Hur, Bock ; Lee, Hee-Joo ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 296~303
The purpose of this study was to assess the effects of cavity designs on the marginal leakage of class 5 glass ionomer restorations. The five cavity designs were as follows ; notch shape(A group), notch shape with groove(B group), combined lesion(C group), combined lesion with groove and deep chamfer margin(D group) and combined lesion with groove and shoulder(E group), and each design had 10 cavities. After the cavities were restored with GIC, they were immersed in 0.5% basic fuchsin solution for 6 hours. The specimens were washed thoroughly and sectioned longitudinally in a buccolingual direction through the center of the restorations. The degree of marginal leakage was measured as the extent of dye penetration under the stereoscope. The results of this study were as follows 1. The enamel margins of all groups showed lesser leakage than dentin/cementum margins(p<0.05). 2. The combined lesion(C group) showed more leakage than notch shape(A group), but there was no siginificant difference(p>0.05). 3. In the notch shape, there was no influence on the marginal leakage by the groove preparation. 4. In the combined lesion, marginal leakage was decreased by the groove preparation and marginal modification.
THE MICROLEAKAGE OF LIGHT-CURED GLASS LONOMER RESTORATIVE MATERIALS IN CLASS V CAVITIES
Cho, In-Sik ; Park, Joon-Il ; Kwon, Hyuk-Choon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 304~315
The purpose of this study was to evaluate the microleakage of light cured glass ionomer restorative materials in class 5 cavities. In this in vitro study, class 5 cavities were prepared on buccal and lingual surfaces of forty extracted human premolars and molars on cementum margin. These specimen were randomly divided into four groups of 10 each : Group 1 was Fugi II (control), Group 2 was Fugi II LC, Group 3 was Vitremer, and Group 4 was Dyract. Group 2 was also divided once more into 2 groups of 5 each : Group 2-1 was pretreated with dentin conditioner and Group 2-2 was not. All teeth were restored according to the manufacturer's instructions. After 500 thermocycling between
, the 40 teeth were placed in 2 % Methylene blue dye for 24hr, then rinsed with tab water. The specimen were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen were then observed with a stereomicroscope at 20. The results of the study were statistically analyzed using the Student-Newman-Keuls Methods and the Mann-Whitney Rank Sum Test. Tooth restorative interfaces were evaluated using SEM analysis. Results were as follows, 1. Compared to conventional glass ionomer restoratioqs, all light cured glass ionomer restorations were fairly resistant to microleakage (P<0.05). 2. Groups 3 (Vitremer) and Group 4 (Dyract) were found to be the most resistant, Group 2 (Fugi II LC) fairly resistant, and Group 1 (Fugi II) least resistant to microleakage(P<0.05). 3. No significant differences were found between Group 2-1 and Group 2-2 (P>0.08). 4. With the backscattered SEM analysis, the degrees to which tight bonding occurred were also observed in all the groups except for Group 1. Group 4 showed the highest degree of tight bonding than any other materials used in this study.
TISSUE LEVELS OF INTERLEUKIN-1α, INTERLEUKIN-1β AND TUMOR NECROSIS FACTOR-α IN PULPAL AND PERIAPICAL PATHOSIS
Ko, Hyun-Jung ; Chung, Kwan-Hee ; Lim, Sung-Sam ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 316~327
This study was designed to examine the tissue levels of interleukin-
) and tumor necrosis factor-
) in inflamed human dental pulps and periapical lesions, and to determine the relationship between each cytokine and pulpal and periapical pathosis. The pulps used in this experiment, were obtained in routine endodontic treatment and the periapical lesions in periapical surgery after clinical diagnoses were performed. These specimens were divided into four groups as normal pulp group(control group, n=9), acute pulpitis group(n=g), chronic pulpitis group(n= 10) and periapical lesion group(n= 18) and stored in liquid N2. For extract preparation, tissues were finely minced with a scalpel, and the fragments were incubated in
homogenizing buffer (0.1 mol/L potassium chloride, 0.02 mol/L TRIS; pH=7.6) for two hours and grinded with glass homogenizer. Debris was removed by centrifugation and supernatants were immediately tested with enzymelinked immunosorbent assay (ELISA, R&D Co., Minneapolis, USA). Following results were obtained; 1. The concentrations of IL-
in all experimental groups were significantly higher than in control group(p<0.05). And the concentrations of IL-
in periapical lesion group were somewhat higher than in two pulpitis groups, but the differences among those groups were not stastically significant (p>0.05). 2. The concentrations of IL-
in all experimental groups were significantly higher than in control group (p<0.05), and all the experimental groups expressed similar concentrations. 3. The concentrations of TNF-
in all experimental groups were higher than in control group but only the differences between chronic pulpitis group and control group were statistically significant(p<0.05). And the concentrations of TNF-
in acute and chronic pulpit is groups were higher than in periapical lesion group but only the differences between chronic pulpitis group and periapical lesion group were statistically significant (p<0.05). 4. There was significant correlation only between IL-
in periapical lesion group (p<0.05).
IDENTIFICATION OF PORPHYROMONAS ENDODONTALIS USING POLYMERASE CHAIN REACTION(RCR)
Lee, Sang-Yup ; Yoon, Soo-Han ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 328~338
Porphyromonas endodontalis, an anaerobic Gram negative cocobacillus which was known to be associated with the infected root canals and periapical lesions, is very difficult to culture and to detect by the traditional method in that it requires much time to induce the specific black pigmentation, and it is very sensitive to oxygen and the antibiotics added in the culture medium. In this study, the nucleotide sequences of the 'probe h' (0.73kb), one of the specific DNA probes top. endodontalis (ATCC 35406) which had been developed by our department, was determined and then a pair of primers for PCR amplification was fabricated to identify P. endodontalis. The plasmids containing 'probe h' were purified by
Midipreps DNA Purification System (Promega Corp.), and the nucleotide sequences of the 'probe h' were determined by the dideoxy chain termination method using TaqTrack Sequencing System (Promega Corp.) and detected by fluorescent labelling method. The sense/antisense PCR primers were designed with computer software (Lasergene, DNASTAR Ind. PCR was done with a programmable GeneAmp PCR System 2400 (Perkin Elmer-Cetus Co.). Each sample containing the whole genomic DNA of P. endodontalis and other black-pigmented Bacteroides was itailly denatured at
for 5 min and then subjected to 30 cycles, each of them consisting of 60s at
, 60s at
, and 90s. at
. The amplified DNA was resolved electrophoretically in a 1.0 % agarose gel in 1X TAE buffer, stained with EtBr, and photographed on a UV transilluminator. The results were as follows : 1. The nucleotide sequences of 'probe h' (743 base pairs) were obtained by dideoxy chain termination method, and from that results the specific primers to P. endodontalis (ATCC 35406), 'Primer H1/ Primer H2', were designed. 2. It has been found that 'Primer H1/H2' could detect P. endodontalis (ATCC 35406) using PCR. 3. The PCR system with this primers may be a powerful technique to amplify the specific sequences of 'probe h' of P. endodontalis (ATCC 35406) that produce distinct identification of it from other black-pigmented Bacteroides, and this could help us to determine the nature of periapical disease.
AN IN VITRO EVALUATION OF THE ACCURACY OF ROOT ZX ELECTRONIC APEX LOCATOR
Kang, Dae-Hoon ; Chung, Kwang-Hee ; Yoon, Soo-Han ; Bae, Kwang-Shik ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 339~345
The purpose of this study was to evaluate the in vitro accuracy of Root ZX(Morita Co., Japan) which is the ratio type electronic apex locator. The 86 extracted human palatal roots of maxillary molar with fully formed apices were used. File lengths with the file tip just visible at the foramen were compared to those measured with Root ZX. For length measuring with Root ZX, saline test model with which the apical 1/3 of each root was submerged into normal saline were designed. The root canal lengths were determined with Root ZX and the radiographs were taken with a file in the canal. The distances from file tips of Root ZX lengths to apecies in radiographs also were measured with Profile projector PJ311(Mitutoyo Co., Japan). The results were as follows : 1. The root canal length determined with electronic apex locator was
shorter than the length with visual measurement. 2. The file tip of Root ZX lengths was located at
away from the apex in radiograph. 3. The accuracy of the Root ZX was 79.1% within 0.5mm of visual working length and 96.5% within 1.0mm.
COMPARISON OF THE SEALING ABILITY OF VARIOUS ROOT CANAL FILLING TECHNIQUES
Lee, Dong-Kyoung ; Yoon, Soo-Han ; Bae, Kwang-Shik ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 346~356
The purpose of this study was to evaluate the sealing ability of various canal filling methods. Palatal roots of ninety extracted human maxillary molar teeth were resected at cementoenamel junction. Eighty of them were randomly assigned to four experimental groups, ten were served as positive and negative controls. All canals were prepared to # 40 using Profile. Experimental groups were obturated by lateral condensation technique, Thermafil technique, Continuous Wave of Condensation Technique, and down-pack & back-fill technique of Obtura-II, each with root canal sealer. Control groups were not obturated. Teeth were immersed in resorcinol-formaldehyde resin for 5 days at
, and the resin was allowed to polymerize completely for 4 days at room temperature. Teeth were then ground horizontally at 1.5mm(level 1), 2.5mm(level 2), 3.5 mm(level 3) from the anatomical apex and examined with a stereomicroscope at
magnification. The gap between the canal wall and the filling material, which was filled with the resin, was measured at each of the three levels. Each ratio of leakage was obtained by calculating the ratio of the area of the resin to the total area of the canal and was analyzed statistically (Rank-sum test). The results were as follows : 1. At the level 1, there was the greatest leakage in the Thermafil group and Obtura-II group, and the difference between the Obtura-II group and Continuous Wave of Condensation Technique group was statistically significant(p<0.05). 2. At the level 2, there was the least leakage in the Continuous Wave of Condensation Technique group, but there was no statistically significant difference between each group (p>0.05). 3. At the level 3, there was no statistically significant difference between each group(p>0.05).
RADIOPACITY OF CAD/CAM CERAMICS
Lee, Jong-Hyeok ; Choi, Han-Seuk ; Um, Chung-Moon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 357~365
THE EFFECTS OF THERMOCONDENSATION TECHNIQUE USING SYSTEM B
ON THE PERIODONTIUM
Kim, Jae-Wook ; Lee, Seung-Jong ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 366~378
Thermocondensation root canal filling technique have been used to fill accessary canals or to obtain homogeneous root caral fillings. But these thermocondensation technique inevitably produce heat in the canal which can be transmitted through the dentin and cementum and consequently damage periodontal ligamental cells and osteoblasts. In this study, System
(Analytic technology, WA.D.S.A.) was used to evaluate the reaction of periodontal ligament tissue to "Continous Wave condensation technique" introduced by Buchanan, and the transmitted root surface temperature was measured according to measured root thicknesses. 12 Mandibular incisors of two adult dogs were used for the experiment. 6 controls were filled by lateral condensation technique with sealer.3 specimens were apically filled by Continuous Wave technique at
for 5 seconds and remaining 3 specimens were additionally backfilled using System
(Analytic technology, WA.D.S.A.) was used to evaluate the reaction of periodontal ligament tissue to "Continous Wave condensation technique" introduced by Buchanan, and the transmitted root surface temperature was measured according to measured root thicknesses. 12 Mandibular incisors of two adult dogs were used for the experiment. 6 controls were filled by lateral condensation technique with sealer.3 specimens were apically filled by Continuous Wave technique at
for 5 seconds and remaining 3 specimens were additionally backfilled using System
for 20 seconds. Six weeks later, the dogs were sacrificed and the teeth stained with Hematoxylin and Eosin for histologic examination. 6 extracted human teeth were used to measure the transmitted temperature. After cutting off the crown, the canals were prepared and divided into 3 groups with root thickness of 1.5mm, 1.0mm, 0.5mm, 2 teeth in each group. Inside each root canal, System
was heated as with the temperature for the apically condensed and the back filled group, and the transmitted heat was measured on the external surface of the root. The temperature of System
heat spreader at
was also measured at root temperature. It can be concluded as follows: 1. In the thin area (200-
) of the root, root resorption could be seen even with heating at
for 5 seconds. 2. When the spreader was heated at
for 5 seconds and additionally at
for 20 seconds for backfill, all teeth showed root resorption regardless of their root thickness. 3. The transmitted external root surface temperature was higher as the root thickness decreased and as the heating time increased. In the thermocompaction technique using System
, the spreader should be heated for the minimal time and used only in the apical area. The heated spreader shouldn't inserted to the binding point of the canal and backfilling should be done with other means of minimally heated gutta percha technique.
Elution of calcium ion from calcium hydroxide products using various root canal irrigants
Seo, Jung-Hwa ; Park, Dong-Soo ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 379~390
In endodontic treatment, calcium hydroxide has been used as intracanal medicament. Although calcium hydroxide should be removed thoroughly before permanent root canal filling, no effective method for its removal has been reported. Because of irregularity of root canal walls, root curvatures and anatomic variations, it is insufficient to remove calcium hydroxide from the canal wall only by mechanical instrumentation Considering the chemical effects of irrigants on calcium hydroxide,
dissolving effect from two calcium hydroxide products is investigated, using dis- tilled water, NaOCl, citric acid and EDTA. Vitapex
0.1g and calcium hydroxide 0.03g were dissolved in distilled water, 5% NaOCl, 50% citric acid and 17% EDTA respectively, at 1, 3, 5, 10min. time interval. The solution was filtered using filter paper(pore size
concentration was determined by ion chromatography. The result were as follows : 1. Distilled water, NaOCl, citric acid and EDTA abstracted more
from calcium hydroxide than Vitapex
except NaOCl 1, 5, 10 time interval. 2. EDTA and citric acid abstracted more
and calcium hydroxide than distilled water or NaOCl. The overall result support the view that water-based calcium hydroxide product is easily removed than oil-based calcium hydroxide product and EDTA, citric acid are more effective in
elution than NaOCl or distilled water.
A STUDY ON COMPARISON OF STAINLESS STEEL, NICKEL-TITANIUM HAND, NICKEL-TITANIUM ENGINE-DRIVEN FILE INSTRUMENTATION USING COMPUTED TOMOGRAPHY
Lee, Hwang ; Im, Mi-Kyung ; Lee, Keon-Il ; Lee, Yong-Keun ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 391~400
The aim of this study was to determine the shaping ability of stainless-steel K file (S-S K file), nickel-titanium K file (Ni-Ti K file) and engine driven nickel-titanium file (Quantec file) in resin simulated root canal. Computed tomography was used to evaluate the change of the root canal morphology. Thirty nine resin simulated root canal were divided into four groups (A:12, B:12, C:12, D:3). Resin simulated canals were scanned by computed tomography before instrumentation (1st C-T scan). Canals were instrumented using step back preparation technique with S-S K file in group A and Ni-Ti K file in group B. Group C was prepared with engine driven Ni-Ti file. Group D was uninstrumented to compare the 1st C-T scan images with 2nd C-T scan images of root canal. Instrumented canals were again scanned using computed tomography (2nd C-T scan), and reformated images of the uninstrumented canals were compared with images of the instrumented canals. In the sections of 2mm and 6mm from the apex, Quantec file caused significantly less canal transportation than S-S K file and Ni-Ti K file (p<0.05). Quantec file produced more centered than S-S K file and Ni-Ti K file in the sections of 2mm and 4mm from the apex (p<0.05). There was no significant difference in the removed volume of canals among the each groups (p>0.05). However the removed canal volume from the apex to 5mm were significantly higher than them from 5mm to 1mm (p<0.05) in each groups. Under the conditions of this study, preparation with Quantec file was more effective and produce more appropriate canal shapes than S-S K file and Ni-Ti K file.
REGIONAL MICRO-SHEAR BOND STRENGTH TO DENTIN:EFFECTS OF DENTINAL HARDNESS, POSITION, AND REMAINING DENTIN THICKNESS
Hwang, Seon-Seong ; Im, Mi-Kyung ; Lee, Yong-Keun ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 401~412
The aim of this study was to measure the regional micro-shear bond strength of dentin bonding agents to dentin, and to investigate the relationship between the micro-shear bond strength and two dentinal characteristics ; Vickers hardness and remaining dentin thickness. Twenty-four freshly extracted, noncarious human molars were selected for this study. The materials tested in this study consisted of two commercially available dentin bonding agents (MAC-BOND, ONE-STEP) and two restorative light-cured composite resins (AELITEFIL, Z100). The occlusal or side surface of tooth crown was sectioned to expose dentin, and the exposed surface was finally polished with # 600 sandpaper. Four groups of application methods were used combining the filling materials and the dentin bonding agents. The composite resin-attached tooth specimens were embeded in a cold cure acrylic resin, and were cut with a low speed diamond saw to the dimension of 1mm
1mm. Nine specimens were obtained from each tooth. The cut specimens were divided into three groups depending on the position of the dentin bonding surface. The micro-shear bond strength, remaining dentin thickness, and dentinal hardness were measured. Experimental results were then statistically analyzed with ANOVA. t-test, Scheffe test, and regression analysis. From this experiment, the following results were obtained : 1. In the case of occlusal surface bonding, the pooled micro-shear bond strength of ONST-AELIT group (16.62 MPa) was significantly higher than that of MACB-AELIT group (9.91 MPa) (p<0.05). However, there was no significant difference in the micro-shear bond strength depending on the dentin position (p>0.05). 2. In the case of side surface bonding of crown, the pooled micro-shear bond strength of four different bonding groups was not significantly different among each other (p>0.05). However, in three of the test groups (ONST-AELIT, MACB-Z100, ONST-Z100), the micro-shear bond strength to the lower 1/3(III) position was significantly lower than that to middle 1/3(II) position of surface (p<0.05). 3. In the ONST-AELIT bonding group, the pooled micro-shear bond strength to the occlusal surface was significantly lower than that to the side surface of crown (p<0.05). 4. There was no significant correlation between the micro-shear bond strength and dentin hardness / remaining dentin thickness (p>0.05).
EFFECTS OF SURFACE TREATMENT AND BONDING AGENTS ON SHEAR BOND STRENGTH OF THE COMPOSITE RESION TO IPS-EMPRESS CERAMIC
Yoon, Byeung-Sik ; Im, Mi-Kyung ; Lee, Yong-Keun ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 413~423
Dental ceramics exhibit excellent esthetic property, compressive strength, chemical durability, biocompatibility and translucency. This study evaluated the shear bond strength of composite resin to the new heat-pressed ceramic material (IPS-Empress System) depending on the surface treatments and bonding agents. The surface treatments were etching with 4.0% hydrofluoric acid, application of silane, and the combination of the two methods. Composite resin was bonded to ceramic with four kinds of dentin bonding agents(All-Bond 2, Heliobond, Scotch bond Multi-purpose and Tenure bonding agents). The ceramic specimen bonded with composite resin was mounted in the testing jig, and the universal testing machine(Zwick 020, Germany) was used to measure the shear bond strength with the cross head speed of 0.5 mm/min. The results obtained were as follows 1. The mean shear bond strength of the specimens of which the ceramic surface was treated with the combination of hydrofluoric acid and silane before bonding composite resin was significantly higher than those of the other surface treatment groups(p<0.05). 2. In the case of All-Bond 2 and Scotchbond Multi-purpose bonding agent group, the surface treatment methods did not influenced significantly on the shear bond(p>0.05). 3. Of the four bonding agents tested, the shear bond strength of Heliobond was significantly lower than those of other bonding agents regardless of the surface treatment methods(p<0.05). 4. The highest shear bond strength(
MPa) was obtained with Scotchbond Multipurpose preceded by the ceramic surface treatment with the combination of 4% hydrofluoric acid and silane.
COMPARATIVE EVALUATION OF LIGHT-CURED COMPOSITE RESINS BASED ON VITA SHADE BY SPECTROCOLORIMETER
Cho, Kyoung-Yee ; Hwang, In-Nam ; Choi, Hong-Ran ; Oh, Won-Mann ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 424~432
To get a satisfactory result in the composite resin restorations, it is necessary to choose correct shade. At present, most of the commercial composite resins are based on the Vita Lumin shade guide or Bioform shade guide, but color differences might be expected even using the same shade in various materials. In this study, five kinds of light-cured composite resins with A2 and B3 shade were used to measure and compare the color each other while one porcelain served as a control. All composite resins (Spectrum TPH (SP), VeridonFil- Photo (VE), Z100 (Z100), Charisma (CH), Prodigy (PRO)) were filled in to the metal mold (12 mm diameter, 2 mm depth), followed by compression, polymerization and polishing with wet sandpaper. The specimens of porcelain were fabricated by using the refractory mold for porcelain. After 24 hours, the specimens were placed on the spectrocolorimeter and spectral reflectance were measured under CIE illuminant D65. After measuring the values of
, following results were obtained; 1. The
values of both shade of porcelain specimens showed significantly higher than those of resin specimens(p<0.05). 2. In comparing the resin specimens of the A2 shade, differences were significant except
values of SP-CH and PRO-VE,
values of the VE-SP and
values of the VE-Z100 and SP-PRO(p<0.05), 3. In comparing the resin specimens of the B3 shade, differences were significant except
values of PRO-SP,
values of the SP-PRO and Z100-VE and b* values of the PRO-SP(p<0.05). 4. In comparing the resin specimens of the A2 shade, color differences between materials (
) showed the lowest value of 1.66, and the highest was 5.16.
values of the materials of VE-PRO, CH-PRO, SP-PRO, SP-Z100 and SP-CH were lower than 3.3. 5. In comparing the resin specimens of the B3 shade, the lowest value of the
was 0.57 and the highest was 5.92.
values of Z100-CH and SP-PRO were lower than 3.3. The present study revealed there was perceptible color difference between materials even if they have the same designated shade based on Vita shade guide. The results of the present study suggested that it would be necessary to establish the reproducible and constant color specification system for an esthetic restoration.
IN VIVO CHANGES OF THE ACIDITY OF VARIOUS DENTAL LINERS
Lee, Mi-Jeong ; Ahn, Yun-Sil ; Lee, Yong-Woo ; Son, Ho-Hyun ; Lee, Kwang-Won ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 433~442
The purpose of this study was to observe the changes of acidity of resin cement(Time Line), glass ionomer cement(GC Fugi Lining LC), zinc phosphate cement(Fleck's zinc cement). zinc oxide eugenol cement(Sultan,Chemists.) in vivo and in vitro. Class I cavities with 3mm depth were prepared on the occlusal surfaces of 20 recently extracted human Mn. molar teeth and 20 human Mn. 3rd molar teeth in oral cavity. The prepared cavities were divided into 4 groups of each 5 teeth using the above 4 cavity liners. Each cement was mixed in accordance with manufacturer's direction at the room temperature of
and filled into the cavity in a width of 1 mm. The microelectrode of pH meter was inserted into the prepared cavity which was filled with mixed cement, and the acidity of cement was measured for 3 days from the beginning of cement mix in vitro and in vivo. The measured acidity was then statistically analyzed by ANOVA. The results were as follows. 1. In vitro, the pH of zinc oxide eugenol cement was statistically lower than that of the three other groups at 2min, 4min, 6min, 8min, 10min, 12min, 18min, 20min. (p<0.05). 2. The pH of zinc oxide eugenol cement in vivo was statistically higher than that in vitro at 16min,16min, 20min(p<0.05). 3. The pH of zinc phosphate cement in vivo was statistically higher than that in vitro at 4min, 20min(p<0.05). 4. In vitro and in vivo, there was no significant difference in the pH between the resin cement and the glass ionomer cement(p>0.05). 5. The initial acidity was not high, but almost neutral in all kinds of the cements.
CHANGES OF TENSILE BOND STRENGTH ACCORDING TO THE DIFFERENCE IN LINING MATERIALS AND LINING AREA
Park, Jong-Duk ; Lee, Yong-Woo ; Ohn, Yeong-Suck ; Lee, Kwang-Won ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 443~460
The purpose of this study was to estimate the changes of tensile bond strength according to the difference in lining materials and lining area. Seventy non-carious extracted human molars were used in the present study, and they were randomly assigned into 2 experimental groups according to the difference in lining materials. Each experimental group was subdivided into 3 groups according to the difference in lining area. Circular cavities were prepared on the dentin surface to a diameter of 1.5mm, 2.0mm, 2.5mm and the prepared cavities were filled with Fuji II LC( Glass Ionomer Cement : GIC) or Dycal. Dentin specimens without circular cavity were used as control group. The primer and bonding agent of All-Bond 2 and composite resin (Z-100, 3M Dental Products, U. S. A.) were applied to the exposed dentin surface with or without lining. Tensile bond strengths for the experimental specimens were then measured. To examine the interface between dentin and liner & between liner and composite resin, two specimens from each group were fabricated and observed under the SEM. The results were as follows. 1. Tensile bond strength for the specimens lined with GIC was higher than that for specimens lined with Dycal. However, there was no significant difference between two groups(p>0.05). 2. Tensile bond strength for the specimens lined with GIC in a diameter of 1.5mm(GIC-1.5mm lining group) was statistically higher than that for the GIC-2.0mm lining group and GIC-2.5mm lining group(p<0.05). 3. Tensile bond strength for the specimens lined with Dycal in a diameter of 2.5mm (Dycal-2.5mm lining group)was statistically lower than that for Dycal-1.5mm lining group and Dycal-2.0mm lining group(p<0.05). 4. It was possible to observe the good adhesion of the resin composite to the GIC and the presence of a fissure between GIC and dentin all along the interface. Interfacial gaps of 7.2-
between GIC and dentin were observed. The interfacial gap between GIC and dentin at the cavity base was greater. However, the gap was gradually decreased toward the occlusal portion. 5. It was possible to observe the poor adhesion of the resin composite to the Dycal. The detachment of Dycal was occurred all along the composite resin-Dycal interface, and the gaps of 2.0-
were formed. In all the specimens, polymerization shrinkage of resin composite caused the detachment of Dycal from the body of Dycal. At a Dycal-dentin interface. it was possible to observe the good adhesion. but poor adhesion with interfacial gap of 2.9-
was observed partially.
SURVEY OF COMPOSITE RESTORATIONS IN KOREA
Um, Chung-Moon ; Lee, Jong-Hyeok ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 461~467
A survey has been made of the reasons for the replacement of 318 resin restorations in selected dental practices in Korea. Secondary caries and discoloarations were the main reason for replacement of composite restorations, followed by discoloration, fracture of restoration, loss of anatomic form and pain sensitivity. The estimated 50% survival time for the surveyed restorations was 3.3 years.
A STUDY ON THE DENTIN BONDING OF ONE-STEP BONDING AGENT
Cho, Young-Gon ; Park, Sung-Taek ; Park, Kwang-Soo ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 468~476
The purpose of this study was to observe the morphologic change of dentinal surface, adhesion in interface between dentin and bonding agents, and penetration pattern of resin tags into dentinal tubles according to bonding procedure of ONE-STEP universal adhesive system. Ten extracted human molars were mounted in dental stone and sectioned to expose mid-coronal occlusal dentin and again sectioned tooth crown apically. Specimens were randomly assigned to three groups for dentin conditioning with 32% phoshoric acid, two coats of bonding agents after dentin conditioning, and bond of composite resin. The surfaces of dentin were treated with etch ant and applied bonding agent, and bonded composite resin according to the directions of manufacturer. Specimens which were boned composite were sectioned longitudinally for observing interfaces between resin and dentin. Two of specimens which were sectioned longitudinally were immersed in 6 N HCL for 30 seconds and 1% NaOCL for 12 hours to partially demineralize and deproteinize the dentin substrate. Each specimen was mounted on a brass stub, sputter-coated with gold and observed under SEM. The result were as follows : 1. On the dentinal surface which was conditioned with 32% phosphoric acid. the smear layer was completely removed. orifices of dentinal tubules were opened 3-
wide. and dentinal surface was irregular. 2. On the dentinal surface which was applied ONE-STEP. bonding agent. resin particles were observed on the orifices of dentinal tubules and intertubular dentin. 3. There were close adaptation between dentin and resin and were the pattern which composite invaded into dentin. 4. 1-
-wide hybrid layer was visible in the interface between dentin and resin. 5. Long and funnel shaped resin tags were observed in demineralized specimens. and the surfaces of tags were rough.
SEM EVALUATION OF THE PREPARED ROOT CANALS BY HAND AND Ni-Ti ROTARY ROOT CANAL INSTRUMENTS
Oh, Tae-Seok ; Park, Jeong-Won ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 477~486
Recently the development of rotary instrument makes it possible that in root canal treatment operator saves much more time, maintans original curved canal shape and easily prepares continuous tapered root canal. The purpose of this experiment was to examine the smoothness of the internal surface of prepared root canal and the effectiveness of debridement in prepared root canal by SEM for the comparison of hand and Ni-Ti rotary instrument. 25 extracted human teeth were access opened and # 10 K-type file was introduced into canal until it was appeared at the apical foramen. The working length was established by subtracting 0.5mm from this measurement. Group 1. The root canal preparation was done to # 30 with working length and then step-back until # 45 with K-Flexofile (Maillefer, Swiss). Group 2. Root canal preparation was done by Naviflex Ni-Ti file (Brasseler, USA) as the same technique with group 1. Group 3. Canal was prepared by Profile .04 (Maillefer, Swiss) taper until #30. Group 4. With use of Quantec (Tycom, USA) root canal was prepared from file number 1 to 8. In group 1 and 2, the root canal irrigant was NaOCl and the other groups, NaOCl and RC-prep (Premine Dental Products, USA) was used. The prepared teeth were notched with high-speed bur as bucco-lingual direction and fractured with chisel and mallet, then examined with SEM. Group 1 showed smooth internal surface. There were scratches mainly to the axial direction. Group 2 showed similar characteristics to those in group 1. Group 3 showed more smoother and linear cutting surface with bised scratches. Group 4 has the almost same characteristics group 3 and there was no difference in the file design. Ni-Ti rotary root canal instrument prepare the dentinal wall more smoother than hand instrument. The effectiveness of debridement was not fully affected by file design. The isthmus area and accessory canals of the root canal system were not prepared in any group. According to the result, hand and rotary type instrumentation techniques were effective in removal of major amount of tissue from root canal but it was not complete. In the direction of cutting movement there was difference between them.
TENSILE STREGNTH BETWEEN MACHINABLE CERAMIC AND DENTIN CEMENTED WITH LUTING COMPOSITE RESIN CEMENTS
Cho, Byeong-Hoon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 487~501
In the case of CAD/CAM ceramic inlay restorations, if isthmus width is widened too much, it may cause fracture of remaining tooth structure or loss of bonding at the luting interface because of excessive displacement of buccal or lingual cusps under occlusal loads. So to clarify the criterior of widening isthmus width, this study was designed to test the tensile bond strength and bond failure mode between dentin and ceramic cemented with luting composite resin cements. Cylindrical ceramic blocks(Vita Cerec Mark II, d=4mm) were bonded to buccal dentin of 40 freshly extracted third molars with 4 luting composite resin cements(group1 : Scotchbond Resin Cement/Scotchbond Multi-Purpose, group2 : Duolink Resin Cement/ All-Bond 2, group3: Bistite Resin Cement/Ceramics Primer, and group4:Superbond C&B). Tensile bond test was done under universal testing machine using bonding and measuring alignment blocks(
& Urn, 1992). After immersion of fractured samples into 1 % methylene blue for 24 hours, failure mode was analysed under stereomicroscope and SEM. Results: The tensile bond strength of goup 1, 2 & 4 was
MPa, respectively. There was no statistical differences(p>0.05). But, group 3 showed significantly lower bond stregnth(
MPa, p<0.05). In almost all samples, adhesive fractures between dentin and resin cements were observed. But, in group 1, 2 & 4, as bond strength increased, cohesive fracture within resin cement was observed simultaneously. And, in group 3, as bond strength decreased, cohesive fracture between hybrid layer and composite resin cement was also observed. Cohesive fracture within dentin and porcelain adhesive fracture were not observed. In conclusion, although adhesive cements were used in CAD/CAM -fabricated ceramic inlay restorations, the conservative priciples of cavity preparation must be obligated.
A STUDY ON THE CORROSION OF AMALGAMS IN CHLORIDE SOLUTION
Um, Chung-Moon ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 502~514
The purpose of this study is to observe the corrosion characteristcs of four dental amalgams(CAULK FINE CUT, CAULK SPHERICAL, DISPERSALLOY, TYTIN) and to determine a function of chloride concentration through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylinderical metal mold, and condensed by hydrolic pressure. Each specimen was removed from the metal mold. 24 hours after condensation, specimens were polished with the emery paper and stored at room temperature for 6 months. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgam m KCl and KCl-NaCl solution, which had chlonde concentration of 0.4 g/l, 0.8 g/l, 1.2 gil, and 1.6 gil at
with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 1 hour, the potential scan was begun. The potential scan range was - 1500mV ~+800mV(vs. S.C.E.) in the working electrode and the scan rate was 50mV/sec. The results were as follows, 1. The corrosion potential. the potential of anodic current peak, and transpassive potential in the solution of high chloride concentration shifted to more cathodic direction than those in the solution of low concentration, and the current density in the solution of high chloride concentration was higher than that in the solution of low concentration. 2. The corrosion potential, the potential of anodic current peak, and transpassive potential for CAULK FINE CUT amalgam were the most cathodic among the others, and the current density were the highest among the others. 3. In the solution of low chloride concentration, the corrosion potential, the potential of anodic current peak, and transpassive potential for DISPERSALLOY were the most anodic among the others, however in the solution of high chloride concentration, those for TYTIN were the most anodic among the others. 4. The anodic polarization curve for CAULK SPHERICAL was similar to that for high copper amalgams.
CLEANLINESS AND WALL MORPHOLOGY OF ROOT-END RETROGRADE CAVITY MADE BY ULTRASONIC DIAMOND INSTRUMENTS
Kim, Sung-Kyo ; Lim, Choon-Hee ; Kwon, Tae-Kyung ;
Restorative Dentistry and Endodontics, volume 23, issue 1, 1998, Pages 515~524
The purposes of this study were to observe the cavity wall morphology and to evaluate the degree of cavity cleanliness when root-end retrograde cavity preparation was done with ultrasonic diamond instruments. To observe the morphology of retrocavity and to evaluate the degree of cavity cleanliness. root-end resections were done on 20 palatal roots of extracted maxillary first molars after canal filling with gutta-percha. Retrocavities were prepared using either ultrasonic diamond instruments or stainless steel ones of medium power setting of level 6 (
, EIE, CA, U.S.A.). Morphology of the cavity. degrees of the remaining canal debris and smear layer were evaluated under the scanning electron microscope. The results were as follows: Cavities prepared with ultrasonic diamond instruments showed scratched appearance of wall, while ultrasonic stainless steel preparation showed hatcheted appearance. Ultrasonic diamond instruments induced more smear layer than stainless steel ones did (p<0.01) in the cavity. However, there was no significant difference in canal debris (p>0.05).