• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.212-218
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• 2004

The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when three types of nickel-titanium rotary instruments (Profile. ProTaper and $K^3$) and a hand instrument(Hedstrom file) used to remove these materials. The results of this study were as follows: 1. In the total time for gutta-percha removal. Profile group was the fastest and followed by $K^3$, Protaper, Hedstrom file group. 2. In case of the evaluation of the volume of remained gutta-percha from radiograph. $K^3$ group got the highest score and followed by Protaper. Hedstrom file. Profile group in the apical 1/3. 3. In case of the evaluation of the volume of gutta-percha remained from stereomicroscope, $K^3$ group got the highest score and followed by Protaper. Hedstrom file. Profile group in the apical 1/3. These results showed that instrumentation using nickel-titanium rotary instrument groups was faster than that using hand instrument group. The effect of gutta-percha removal using Profile group was better than that using Protaper and $K^3$ group in the nickel-titanium rotary instrument groups.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.552-552
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• 2003

The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when three types of nickel-titanium rotary instruments and a hand instrument were used to remove these materials. Forty extracted mandibular premolars were prepared by step-back method and obturated with gutta-percha and sealer. Gutta-percha removal for group 1 was done using hand file with chloroform, group 2 using Profile and group 4 using K3. The following factors were evaluated : Time taken to reach working length, total time for gutta-percha removal and number of fractured instruments.(중략)

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.611-620
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• 1994

The purpose of this study was to evaluate the effect of post space preparation on apical sealing according to the methods and time of gutta percha removal. Forty six extracted single rooted teeth were selected for this study. Forty teeth were used as experimental groups and six teeth as control groups. Forty teeth were routinely prepared by step-back method and obturated with gutta percha cones and zinc oxide-eugenol cement using lateral condensation. All obturated teeth were divided into 4 groups of 10 teeth each. In each group of 1, 2, 3, heated plugger, gate glidden drill and chloroform and K-file were used respectively for post space preparation by removing the gutta percha immediately after obturation. In group 4, post space were prepared with gate glidden drill one week after obturation. In all experimental groups, the post space were prepared so that 4mm of apical gutta percha remained. After post space preparation, apical leakage were measured with electrochemical method for 28 days and analyzed statistically. The following results were obtained ; 1. No statistically significant differences in apical leakage were occured among the experimental groups using heated plugger, gate glidden drill and chloroform and K-file to remove the gutta percha immediately after obturation. 2. No significant difference in apical leakage was found between the teeth prepared post space immediately after obturation and those prepared 1 week after obturation. 3. In all experimental groups, the apical leakage was increased with time passage regardless of the post space preparation time and the gutta percha removal techniques.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.1
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• pp.99-107
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• 2011

The main objective of nonsurgical retreatment is to disinfect the root canal space for periradicular healing. Thus, efficient removal of the filling material from the root canal system is essential to ensure a favorable outcome. Traditionally, the removal of root canal filling material was performed by stainless steel hand instrument and this procedure is time and effort-consuming. Recently, rotary NiTi retreatment instruments are developed to effective removal of root canal filling material. The aim of this study was to evaluate the effectiveness of stainless-steel hand instrument and rotary NiTi retreatment instrument when removing gutta-percha in curved root canals. For the remaining materials, there were no significant differences between groups. But the rotary NiTi system proved to be faster than hand instruments in removing root filling materials.

• Restorative Dentistry and Endodontics
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• v.25 no.1
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• pp.144-152
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• 2000

Intracoronal bleaching is currently disregarded by many clinicians because of the potential consequence of cervical resorption. To prevent this complication it is recommended that intra coronal barrier materials be placed over the root canal obturation and sodium perborate be used with water rather than with hydrogen peroxide. The purpose of this study was to evaluate the amount of the hydrogen peroxide penetration according to the difference in intracanal base materials and sodium perborate preparation. Fifty extracted intact premolars were instrumented, and filled with gutta-percha. And then the outer surface of the teeth was sealed with wax exposing the CEJ. The prepared teeth were placed in plastic tubes containing 1.5ml distilled water with their entire root submerged into the solution, The teeth were divided into the following five groups. In the first two groups gutta-percha was removed without placement of barrier, and then water or superoxole(30% $H_2O_2$) with sodium perborate were used respectively for bleaching. In the other three groups, after removal of gutta-percha, an intracanal isolating barrier(ZPC, IRM, Fuji II LC) was placed and then bleached with sodium perborate and superoxole. The bleaching procedure was performed 4 times with 1 week interval. The results were as follows : 1. All the groups showed a tendency of increasing penetration amount with increasing treatment times(P<0.05). 2. After the 1st and 2nd treatments, there was no significant difference in microleakage among the groups. 3. After the 3rd bleaching with superoxole and sodium perborate, there was no significant difference in microleakage between gutta-percha alone group and gutta-percha with ZPC, Fuji II LC barrier group. But significant difference was found between IRM barrier group and other groups(P<0.01). 4. After the 4th bleaching with superoxole and sodium perborate, there was no significant difference between gutta-percha alone group and gutta-percha with barrier groups. 5. After the 4th treatment, the group bleached with sodium perborate and water without barrier showed lower hydrogen peroxide penetration than that of other groups(P<0.01).

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.67-76
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• 1993

After periodontal surgery, the potential healing responses were occurred by interaction among junctional epithelium, gingival connective tissue, alveolar bone and periodontal ligament. The only cell that created periodontal regeneration was derived from periodontal ligament. The aim of the study was to evaluate the regenerative effects of the collagen membrane($collacote^{\circ}C$) and autogenous connective tissure graft with periosteum. Experimental periodontitis were created in furcation area of 4 adult dogs with bone removal and gutta percha packing. After 6 weeks later, the gutta percha was removed and experiment was performed divided by 3 groups. 1) Flap operation(control group). 2) Flap operation with collage membrane(Experimental group I). 3) Flap operation with autogenous connective tissue graft with periosteum (Experimental group II). After dogs were sacrificed after two and three weeks, specimens were prepared and stained with hematoxylin-eosin and masson-trichrome stain for light microscopic study. The results were as follows : 1. In all gruoups, connective tissue compartments were increased from two to three weeks especially in experimental group I. 2. Collagen membrane and connective tissue were increased collagen deposits of periodontal ligament. Therefore collagen fiber attached to tooth surface was seen. 3. In al experimental groups, newly forming alveolar bone was seen. 4. Collagen membrane and connective tissue were which prevented proliferation of epithelium, aided connective tissue new attachment and influenced periodontal regeneration.

• Imaging Science in Dentistry
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• v.47 no.4
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• pp.233-239
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• 2017

Purpose: This study was performed to quantify the repeat rate of imaging acquisitions based on different clinical examinations, and to assess the prevalence of error types in intraoral bitewing and periapical imaging using a digital complementary metal-oxide-semiconductor(CMOS) intraoral sensor. Materials and Methods: A total of 8,030 intraoral images were retrospectively collected from 3 groups of undergraduate clinical dental students. The type of examination, stage of the procedure, and reasons for repetition were analysed and recorded. The repeat rate was calculated as the total number of repeated images divided by the total number of examinations. The weighted Cohen's kappa for inter- and intra-observer agreement was used after calibration and prior to image analysis. Results: The overall repeat rate on intraoral periapical images was 34.4%. A total of 1,978 repeated periapical images were from endodontic assessment, which included working length estimation (WLE), trial gutta-percha (tGP), obturation, and removal of gutta-percha (rGP). In the endodontic imaging, the highest repeat rate was from WLE (51.9%) followed by tGP (48.5%), obturation (42.2%), and rGP (35.6%). In bitewing images, the repeat rate was 15.1% and poor angulation was identified as the most common cause of error. A substantial level of intra- and inter-observer agreement was achieved. Conclusion: The repeat rates in this study were relatively high, especially for certain clinical procedures, warranting training in optimization techniques and radiation protection. Repeat analysis should be performed from time to time to enhance quality assurance and hence deliver high-quality health services to patients

• The Journal of the Korean dental association
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• v.54 no.11
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• pp.874-879
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• 2016

Damage to the inferior alveolar nerve(IAN) is a relatively infrequent complication in endodontic treatment. However, endodontic overfilling involving the mandibular canal may cause an injury of the inferior alveolar nerve resulting in sensory disturbances such as pain, dysesthesia, paresthesia or anesthesia. Two mechanism(chemical neurotoxicity and mechanical compression) are responsible for the IAN injury. When absorbent materials overfilled, it can be treated as a non-surgical procedure. But early surgical intervention required when mechanical, chemical nerve damage expected. We report surgical removal of overfilled gutta-percha and IAN decompression through sagittal split osteotomy in case of dysesthesia after overfilling of endodontic material into the mandibular canal. Dysesthesia recovered 3 months after surgical treatment.

• Restorative Dentistry and Endodontics
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• v.11 no.1
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• pp.27-32
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• 1985

The purpose of this study was to examine the influence of canal irrigants and smear layer on the property of apical seal. Fourty-five canals from human teeth were randomly selected and divided into 5 groups according to the irrigants used in conjunction with instrumentation. The irrigants were RC-prep in combination with Naocl, Citric acid, Naocl, Naocl in combination with $H_2O_2$, and normal saline solution. After instrumention and dry the canal with paper point, the canals were obturated by lateral condensation of Zinc-oxide eugenol sealer and gutta percha cone. All the specimens were immersed in 2% methylene blue dye solution for 7 days and the depth of dye penetration into the canals was evaluated by macros cope. The following results were obtained. 1. All the canals experimented showed varying degree of dye penetration. 2. There was no significant difference in depth of dye penetration between the groups known to be effective and ineffective in the removal of the smear layer. 3. The canals irrigated with NaOCl alone showed the highest dye penetration and mean leakage was 7.7 mm. 4. In the canals irrigated with RC-prep in combination with Naocl and citric acid, the mean dye penetration was 5.5 mm and 4.8 mm respectively, and the canals irrigated with NaOCl in combination with $H_2O_2$ and normal saline solution revealed mean dye penetration of 3.9 mm.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.727-733
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• 1997

Autotransplantation is a procedure which transplants teeth from the original position to other positions in the same individual. It is classified surgical reposition by intraalveolar autotransplantation and transalveolar autotransplantation. The prognosis for successful autotransplantation is dependent on a number of factors such as root development, surgical technique, patient's age, endodontic treatment, time and type of splinting, preservation of periodontal ligament and storage medium. The most important factor is preservation of periodontal ligament. The cause of the failure of transplantation include damage of the transplant during removal from deep palatal malposition, poor regeneration of the bone around the transplant and chronic periodontal infection. In case I, Impacted maxillary canine for which surgical exposure and orthodontic treatment was impossisle was transplanted. After 2 weeks, It showed periapical radiolucency and external root resorption. So, endodontic treatment was done. One year later, permanent filling was done with gutta percha. In case II, Transpositioned maxillary central incisor was transplanted after extraction of impacted mesiodens. Pulp vitality was maintained during 5 months without other clinical symptons.