• Imaging Science in Dentistry
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• v.41 no.1
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• pp.17-21
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• 2011

Purpose : The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption. Materials and Methods : This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment. Results : Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption. Conclusion : These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.649-658
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• 1994

The purpose of this study was to evaluate the association between incisor root resolution and sex, age, extraction, the magnitude and direction of tooth movement. The sample consisted of 189 randomly selected orthodontic patients, receiving standard edgewise orthodontic treatment in three private orthodontic onces at San Francisco. Pre-treatment and post-treatment periapicals and cephalometric radiographs were digitized. Measurements and superimpositions were made utilizing a computerized cephalometric analysis program. The variables were statistically analyzed. The results were as follows: 1. Mean apical root resorption values were $0.77{\pm}2.08mm$ for upper right central incisor, $0.88{\pm}2.11mm$ for upper left central incisor, $-0.05{\pm}2.09mm$ for lower right central incisor and $0.11{\pm}1.85mm$ for lower left central incisor. Apical root resorption of upper incisor was greater than lowers. 2. No correlation was found between sex and apical root resorption. 3. Apical root resorptions in adolescents were smaller than those in adults. 4. Apical root resorption was not affected by extraction. 5. Apical root resorption values of upper incisor were correlated to the horizontal and vertical movement of apex; Apical root resorption values of lower incisor were correlated to the vertical movement of apex.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.631-648
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• 1994

The purpose of this study was to investigate the effects of different types of orthodontic force on the root resorption and repair in rat molar. 77 rats were divided into three groups; The control group was not equiped with orthodontic appliance between incisor and first molar. The experimental group was subdivided into closed coil spring subgroup and elastic chain subgroup by the application methods of orthodontic force. Initial orthodontic force between incisor and first molar was 100g. Experimental period was 8 weeks; for 4 weeks the appliance was acting and for another 4 weeks, removed. Root resorption and repair in the root of first molar was examined by light microscope for histologic changes and by inductively coupled plasma spectroscopy(ICP) for quantitative changes. The results were as follows: 1. In the closed coil spring subgroup odontoclasts and root resolution were appeared one week earlier. 2. One week after orthodontic force was eliminated the repair response in the resorptive lacuna was seen in both subgroups. Delayed resorption was seen on the periphery of resorptive lacunae whereas reparative response was seen in the center of lacunae. A new resorption was seen one week after orthodontic force was eliminated. Root contour was partially restored by repairing of resorbed root. 3. The weight ratios of calcium and phosphorous to the sample were decreased during resorptive process but increased during repair process in both the orthodontic groups, but not more than the control group. 4. By different types of orthodontic force (closed coil spring or elastic chain) resorption process was affected but repair process was not.

• The korean journal of orthodontics
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• v.50 no.3
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• pp.216-226
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• 2020

Root resorption can be caused by several factors, including contact with the cortical bone. Here we report a case involving a 21-year-old female with Angle Class II, division 1 malocclusion who exhibited significant root resorption in the maxillary right central incisor after orthodontic treatment. The patient presented with significant left-sided deviation of the maxillary incisors due to lingual dislocation of the left lateral incisor and a Class II molar relationship. Cephalometric analysis demonstrated a Class I skeletal relationship (A point-nasion-B point, 2.5°) and proclined maxillary anterior teeth (upper incisor to sella-nasion plane angle, 113.4°). The primary treatment objectives were the achievement of stable occlusion with midline agreement between the maxillary and mandibular dentitions and appropriate maxillary anterior tooth axes and molar relationship. A panoramic radiograph obtained after active treatment showed significant root resorption in the maxillary right central incisor; therefore, we performed cone-beam computed tomography, which confirmed root resorption along the cortical bone around the incisive canal. The findings from this case, where different degrees of root resorption were observed despite comparable degrees of orthodontic movement in the bilateral maxillary central incisors, suggest that the incisive canal could be an inducing factor for root resorption. However, further investigation is necessary to confirm this assumption.

• Journal of dental hygiene science
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• v.11 no.3
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• pp.251-255
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• 2011

Objectives One aspect of undesirable outcomes in orthodontic treatment includes excessive resorption of dental roots with mechanotherapy. The purpose of this study was to examine the relationship between treatment duration, adult and adolescent, gender, extraction and non-extraction root resorption after orthodontic treatment. Methods The subjects consisted of 140 orthodontic patients(adult : 70, adolescent : 70) who treated by standard edgewise technique at the three orthodontic hospital and clinic in seoul. Pre-treatment and post-treatment periapical radiographs were examined. The amount of root resorption was assessed for six anterior teeth according to criteria modified from Lupi et al root resorption score. Results Treatment duration was 24.7 months in the adult group and 33.5 months in the adolescents group. Between adult and adolescents group were significantly difference of mean of root resorption score(p<0.05). Female group and extraction group usually had higher prevalence of root resorption, but were not significant differences between the each groups(p>0.05). Conclusions When viewing these results, a lot of root resorption in adult patients appears, especially the maxillary central incisor, lateral incisor root resorption during orthodontic treatment occurs, so be careful and do more research to be done is suggested.

• The korean journal of orthodontics
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• v.48 no.5
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• pp.339-345
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• 2018

Objective: The purpose of this study was to clarify the effects of continuous force application for extrusive tipping movement and occlusal interference on periapical root resorption in the rat mandibular first molar. Methods: We constructed an appliance comprising a titanium screw implant with a cobalt-chromium post as the anchorage unit and a nickel-titanium closed coil spring (50 cN) as the active unit. Force was applied on the mandibular left first molar of rats for 8 (n = 10) and 15 days (n = 10; experimental groups), with the tooth in occlusion. Five rats were included as a non-treated control group to examine the body effect of the appliance. Active root resorption lacunae, identified using tartrate-resistant acid phosphatase, were evaluated in terms of the length, depth, and area. Results: The rat mandibular first molars were mesially tipped and extruded in the occlusal direction. This mesio-occlusal tipping movement and occlusion resulted in the formation of a compression zone and active root resorption lacunae in the distoapical third of the distal roots. However, there was no significant difference in the amount of root resorption between the two experimental groups. The control group did not exhibit any active root resorption lacunae. Conclusions: Periapical root resorption was induced by continuous extrusive tipping force and occlusal interference in rat mandibular molars. These data suggest that we orthodontists had better take care not to induce occlusal interference during our orthodontic treatment.

• Imaging Science in Dentistry
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• v.46 no.1
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• pp.17-24
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• 2016

Purposes: This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. Materials and Methods: A sample of 79 patients (mean age, $13.5{\pm}2.2years$) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the post-treatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. Results: The mean EARR observed was $15.44{\pm}12.1pixels$ (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. Conclusion: A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment.

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.147-154
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• 2012

Purpose: This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. Materials and Methods: The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. Results: The periapical radiographs of 564 teeth showed that the average root resorption was $1.39{\pm}1.27$ ($8.24{\pm}7.22$%) and $1.69{\pm}1.14$ mm ($10.16{\pm}6.78%$) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. Conclusion: These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.4
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• pp.319-326
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• 2015

Short root anomaly (SRA) is very rare, but can be problematic for physicians because patients with SRA are more vulnerable to root resorption with orthodontic forces. During the mixed dentition period, it may be difficult to diagnose generalized SRA. This article reports the treatment of an orthodontic patient with SRA at the early mixed dentition stage. Despite local tooth loss, a relatively favorable outcome was obtained without excessive root resorption. Ultimately, orthodontic therapy is possible for patients with generalized SRA, but precautions should be taken to avoid complications, such as tooth loss or root resorption.

• The korean journal of orthodontics
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• v.47 no.6
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• pp.365-374
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• 2017

Objective: The objective of this study is to investigate the eruption pattern and root resorption of the bovine anterior dentition in relation to growth-related parameters based on dental maturity. Methods: A cross-sectional study was conducted on 110 bovine anterior mandibles by using standard radiography, cone-beam computed tomography (CBCT), and actual measurements. We determined the relationships between the stages of dental maturity by using a modification of Demirjian's method and various growth-related parameters, such as the activity of the root-resorbing tissue and mobility of the deciduous teeth. The correlation of growth-related parameters with interdental spacing and distal unusual root resorption (DRR) of the deciduous fourth incisor was assessed. The cause of mesial unusual root resorption (MRR) of the deciduous fourth incisor was determined on the basis of the arrangement of the permanent third incisor. Results: An independent t-test and chi-square test indicated significant differences in growth-related parameters associated with dental arch length discrepancy and factors related to the shedding of deciduous teeth between the low and high dental maturity groups. The samples with interdental spacing and DRR showed a larger sum of mesiodistal permanent crown widths and higher dental maturity than did the respective controls. Samples with MRR tended to show a lingually rotated distal tip of the adjacent tooth crown. Conclusions: Dental maturity has relevance to the interdental spaces and unusual root resorption of mixed dentition. The position of the adjacent tooth crown on CBCT may be correlated with the occurrence of unusual root resorption of the incisor.