• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.41-45
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• 2004

In the normal growth and development of the mandible, the molar tooth buds distal to the first permanent molar have a mesial inclination. This inclination is usually self-correcting, but, unfortunately, this self-correction does not always occur. The first case is about, 14-year-old female patient with familial history of lower second molar impaction. Her lower second molars were both impacted, and she was treated with sectional wires and open-coil springs. The second case, 14-year-old male, we treated his impacted #47 with Halterman appliance. The third case, 11-year-old male, his both mandibular second molars were impacted during full-fixed orthodontic treatment. They were treated with brass wire, sectional wire and open-coil spring.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.4
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• pp.314-320
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• 2013

With a prevalence rate of 0.01%, the presence of eruption disturbances of mandibular first molar has rarely been in populations. Eruption disturbances of permanent molars have been usually manifested as impaction, primary retention, and secondary retention. The treatments of eruption disturbances are carried out by: periodic observation; surgical exposure; forced eruption after surgical exposure; forced eruption with luxation; surgical repositioning; and extraction. This case report show successfully erupted mandibular first molars by various treatment methods on five patients diagnosed with impaction, primary retention, and secondary retention, respectively. Eruption disturbances of the mandibular first molar can be properly diagnosed with impaction, primary retention, and secondary retention by clinical and radiographic examination at normal eruption time of the mandibular first molar. The treatment should be done synthetically, considering eruption state of affected tooth, the relationship between the affected tooth and the adjacent or opposite tooth, the patient's age, treatment compliance, and economic state.

• The korean journal of orthodontics
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• v.47 no.4
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• pp.268-274
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• 2017

The purpose of this article is to introduce a simple appliance that uses a setup model and a nickel-titanium (Ni-Ti) wire for correcting the mesial rotation and drift of the permanent maxillary first molar. The technique involves bonding a Ni-Ti wire to the proper position of the target tooth on a setup model, followed by the fabrication of the transfer cap for indirect bonding and its transfer to the patient's teeth. This appliance causes less discomfort and provides better oral hygiene for the patients than do conventional appliances such as the bracket, pendulum, and distal jet. The treatment time is also shorter with the new appliance than with full-fixed appliances. Moreover, the applicability of the new appliance can be expanded to many cases by using screws or splinting with adjacent teeth to improve anchorage.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.633-644
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• 1993

There has been so much controversies about the position of upper and lower jaws, and their first permanent molars in normal occlusion and Angle's class $I{\cdot}II{\cdot}III$ malocclusions. So, the purpose of this study is to compare the position of upper and lower jaws, and their first molars in normal occlusion and Angle's class $I{\cdot}II{\cdot}III$ malocclusions by lateral cephalometric analysis. The sample consisted of one hundred and twenty girls(thirty in each group) who had completed growth. The findings of this study were as follows : 1. In class I malocclusion, both maxilla and mandible were slightly posterior position than normal occlusion, but they showed harmonious relationship. 2. In class II malocclusion, the mandible was greatly retruded, and the maxilla was also slightly retruded to the cranial base as compared with normal occlusion. 3. In class III malocclusion, the maxilla was significantly retruded to the cranial base, but no significant difference was found in mandibular position as compared with normal occlusion. 4. The maxillary first molar was located at posterior position in class II malocclusion, and anterior position in class III malocclusion to the cranium, so that the rotation of mandible was influenced by that. 5. The mandibular first molar showed constant relationship to the mandible in all four groups, but different position to the cranial base in direct proportion to the mandibular position. 6. On the treatment planning of class III malocclusion, it seems to be better to promote the mandibular horizontal growth by inhibiting the vertical growth of maxillary molar area, and on the treatment planning of class III malocclusion, it seems to be better to promote the antero-inferior growth of maxilla mi to promote the mandibular vertical growth by inducing the vertical growth of maxillary molar area.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.3
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• pp.121-140
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• 1991

Fifteen dental college students of Chosun University without the abnormal occlusion, the history and symptom of temporomandibular dysfunction(TMD), and who had all permanent teeth except third molar and the fifteen moderate group and the fifteen severe group classified according to Helkimo's dysfunction index among patients on the basis of the symptom of TMD were selected. The occlusal contact, occlusal force and occlusal interference in eccentric movement was studied and analyzed using T-Scan system. The result were as follows : 1. The TLR centering around midsagittal axis was located at $1.42{\pm}0.82mm$ in control group, $3.36{\pm}1.45mm$ in severe group, and as TMD was heavier, occlusal contact was located at the farther point from midsagittal axis. 2. The PLR from the first contact to the fifth contact centering around midsagittal axis was located at $1.73{\pm}1.78mm$ in control group, $3.36{\pm}1.41mm$ in moderate group, and $5.39{\pm}4.32mm$ in severe group, and as TMD was heavier, occlusal contact was located at the farther point from midsgittal axis. 3. The TFB, PFB, RFB and LFB of occlusal contact centering around incisal axis had no significant difference statistically among control group, moderate group, and severe group, and it was located at first molar. 4.The LF and RF was smaller in TMD group than in control group. 5. The LR moment of occlusal force centering around midsagittal axis was located at $178.51{\pm}139.81N.mm$ in control group, $466.25{\pm}296.47N.mm$ in moderate group, and $749.18{\pm}588.18N.mm$ in severe group. And as TMD was heavier, it was located at the farther point from midsagittal axis. 6. The RL and LL of occlusal force centering around incisal axis had not-significance statistically among control group, moderate group, and severe group, and it was at the first molar. 7. The number of occlusal interference of the eccentric movement was increased in the patients of TMD.

• The korean journal of orthodontics
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• v.25 no.4
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• pp.447-451
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• 1995

The purpose of this study was to investigate the effects of cleft on mesiodistal dimensions of permanent teeth in unilateral cleft lip and palate patients. Mesiodistal dimensions of permanent teeth were measured to the nearest 0.01mm on plaster models of 50 subjects with unilateral complete cleft lip and palate, 10 siblings and 50 Controls. The results were as follows : 1. Tooth size discrepancy in the cleft group was significant in all regions except maxillary cuspid, mandibular cuspid and mandibular first premolar. 2. Some of the mesiodistal dimensions of the teeth on the cleft side were significantly smaller than those of their antimeres on the non-cleft side in the cleft group. 3. A comparison of mesiodistal dimensions of the teeth for the right and left sides of the control group showed no statisically significant differences excepts maxillary lateral incisor. 4. Asymmetries of mesiodistal dimensions of the teeth in the sibling group was not found except maxillary first molar.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.2
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• pp.192-198
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• 2012

Revascularization of the pulp in a necrotic, infected immature tooth with apical periodontitis was attempting several years. Revascularization of partially necrotic pulp in an immature tooth is based on the concept that vital dental stem cells can survive pulpal necrosis. Revascularization procedure obtains longer and thicker roots in teeth with necrotic pulp diagnosis. Pulp revascularization for immature permanent molars can be possibly applied on cases having difficulty to use conventional root canal treatment due to abnormally thin root canal wall or severe root curvature. Also, when an uncooperative patient does not agree with sedative treatment the revascularization can be useful. And a patient with disability who is barely cooperative can be another indication of this treatment. In this case report, pulp revascularization using triple-antibiotics, metronidazole, ciprofloxacine and minocycline, was applied on the immature first permanent molar infected by caries.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.607-617
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• 2002

The purposes of this study were to evaluate the timing of tooth calcification and the change of tooth position with tooth developmental stage on the mandibular teeth. Seven hundred seventy two children(male:446, female:326), 3 to 12 years of age were examined radiographically with panoramic film. Dental development was determined by inspecting radiographs and assigning a rating according to consecutive stages defined by Moorrees, and tooth cusp position and root terminus position were measured from the lower border of mandibular body and calculated the position index to evaluate the movement of tooth with developmental stage. The results were as follows. 1. There were no significant differences between boys and girls in the timing of calcification until crown completion, but timing of calcification tend to be faster in girls than in boys after root initiation stage. 2. In terms of mean age, crown completion of central incisor in boys and girls occurred at the age of 3.71, 4.05 years, at 4.44, 4.60 years for the lateral incisor, at 5.35, 5.11 years for the canine, at 6.62, 6.36 years for the first premolar, at 7.36, 7.17 years of second premolar, at 3.51, 3.69 years of first molar, and at 7.90, 7.64 years for the second molar respectively. Apex 1/2 closed stage of central incisor occurred at the age of 8.70 in boys, 8.18 in girls, at 9.55, 8.99 years for the lateral incisor, at 12.48, 11.60 years for the canine, at 12.30, 12.01 years for the first premolar, at 12.19, 12.26 years of second premolar, at 9.12, 8.87 years of first molar, and at 12.59, 12.45 years for the second molar respectively. 3. There was no noticeable movement of cusp tip until crown completion (Crc), but showed rapid movement toward occlusion plane after root initiation(Ri) and again maintain stable position after root completion stage(Rc). 4. Root terminus position was stable until root 1/4 formation stage(R1/4), followed by rapid movement toward occlusal plane and was stable again after root 3/4 formation stage(R3/4). 5. Developmental stage at the time of alveolar bone penetration by cusp tip varied with each of the permanent teeth. 6. Canine tooth follicle was at the lowest position in the mandibular body during the early stage of calcification, followed by second premolar, first premolar, lateral incisor, second molar, first molar and central incisor in order.

• The korean journal of orthodontics
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• v.38 no.6
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• pp.397-406
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• 2008

Objective: The purpose of this study was to provide clinical guidelines to indicate the best location for mini-implants as it relates to the cortical bone thickness and root proximity. Methods: CT images from 14 men and 14 women were used to evaluate the buccal interradicular cortical bone thickness and root proximity from mesial to the central incisor to the 2nd molar. Cortical bone thickness was measured at 4 different angles including $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, and $45^{\circ}$. Results: There was a statistically significant difference in cortical bone thickness between the second premolar/first permanent molar site, central incisor/central incisor site, between the first/second permanent molar site and in the anterior region. A statistically significant difference in cortical bone thickness was also found when the angulation of placement was increased except for the 2 mm level from the alveolar crest. Interradicular spaces at the 1st/2nd premolar, 2nd premolar/1st permanent molar and 1st/2nd permanent molar sites are considered to be wide enough for mini-implant placement without root damage. Conclusions: Given the limits of this study, mini-implants for orthodontic anchorage may be well placed at the 4 and 6 mm level from the alveolar crest in the posterior region with a $30^{\circ}$ and $45^{\circ}$ angulation upon placement.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.4
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• pp.337-347
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• 2011

The basic structure of the primary crowns usually resemble their succeeding permanent teeth. However, maxillary second primary molars resemble ipsilateral first permanent molars. Accordingly in this study, odontometric data of the two teeth was obtained, then analyzed to verify the morphological relationship and sex difference between the two teeth. Dental study casts were examined for their mesiodistal and buccolingual width of the crowns, diameter of each cusps, and intercuspal distances. Photographs of the crowns were taken to measure the angles between each cusp tip. The results are as follows : 1. In boys, PrI, PaI, DBC angle, and MBC angle did not show any statistically significant difference between the two teeth(p>0.05), and moderate level of correlations were observed. 2. In girls, crown index, DBC angle, and MBC angle of the two teeth did not show any statistically significant difference(p>0.05), and moderate level of correlations were recognized. 3. Measurements that did not show statistically significant difference between the two teeth in both boys and girls were DBC angle and MBC angle(p>0.05). In DLC angle, however, statistically significant difference was observed(p<0.01). 4. Most of the measurements showed sex differences, except DBC angle, which did not show any sex difference in both teeth(p>0.05).