• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.47-55
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• 1993

This study was designed to recognize the factors which can affect the normal eruption of the lower third molar and the eruption rate of the lower third molar in the cases of non-extraction and the extraction of first premolar. The sample consisted of 214 cases of extraction of first premolar and 119 cases of non-extraction, and all of these cases were divided into erupted and impacted lower third molar groups and were analized according to the pantomogram. The results of the study were as follows : 1. The eruption rate of the touter third molar was $54.67\%$ in the group of extraction of the first premolar and $35.29\%$ in the non-extraction group. 2. The early inclination of the erupting lower third molar has significant effect in the eruption of it. 3. In the orthodontic treatment, the extraction of first premolar is one of the factors infuencing the nomal eruption of lower third molar. 4. The available space for the normal enruption of lower third molar was greater in first premolar extraction case than in non-extraction case.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.6
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• pp.530-535
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• 2004

Objectives. The purpose of this study was to evaluate mandibular third molars as risk factors for angle fracture in a patient sample with fractured mandible. Materials and methods. The medical records and panoramic radiographs of 107 patients with mandibular fractures were examined. The presence and absence and degree of impaction of the lower third molar were assessed for each patient and related to the occurrence of fracture of the mandibular angle. Data were also collected for age, sex and mechanism of injury. Data were analyzed by a chisquare statistics and Student t test. Result. The incidence of mandibular angle fracture was found to be significantly greater when a lower third molar was present(p <0.05) especially at class III state.(p < 0.05)(by Pell & Gregory system) Of the 78 patients with a lower third molar, 46(58.97%) had angle fractures. Of the 29 without a lower third molar, 24(82.76%) had not angle fractures. Conclusion. The result of this study showed that the mandibular angle that have a lower third molar is more susceptible to fracture when exposed to an impact than an angle without an lower third molar.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.79-88
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• 1988

The purpose of this study was to investigate the factors which might be related to mandibular third molar eruption and to predict the possibility of whether or not it will be erupted. The material of this study was lateral cephalometric radiograms, pantomograms and dental casts obtained from 70 patients (19 males, 51 females) ranging in age from 18.0 to 32.1 years. They were devided into erupted group and impacted group of mandibular third molars. For the comparison of each group, a total of 20 measurement items were employed and the data were analyzed by means of computer statistical method. As a result of this study, the following conclusion can be made; 1. The longer mandibular body length and narrower mandibular ramus width, the higher eruption tendency of the lower third molar, but the degree of genial angle was not related to mandibular third molar eruption. 2. The lower percentage of posterior mandibular body height to anterior mandibular body height, the higher eruption tendency of the lower third molar. 3. The total tooth size, including the lower second molar, appeared to be larger in the impacted group than in the erupted group of the lower third molar. 4. The arch length discrepancy of the impacted group was more severe in contrast with the erupted group of the lower third molar.

• The korean journal of orthodontics
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• v.9 no.1
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• pp.117-123
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• 1979

The aspects examined in the present study concerning the location and position of the lower third molar and the interrelationships of this molar, the gonial angle, and the second lower molar in subjects aged 8-24 are based on measurements made from 472 orthopantomograms. The following conclusion were drawn on the basis of the present study. 1. The gonial angle decreased with age, but slight enlarging occurred in the age group 20-21. 2. The angulation of the third molar in relation to the second molar did not correlate with the size of the gonial angle but decreased with developmental stage. 3. The mesial angle between the longitudinal axis of the second molar and the mandibular base line correlated significantly with the gonial angle. The above angle were smaller in Class II, Divison 2 and larger in Class III than in Class I and Class II, Division 1. 4. The rate of presence of lower third molar was 74.4%.

• Journal of Oral Medicine and Pain
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• v.16 no.1
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• pp.121-136
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• 1991

This study was undertaken to obtain the data for age determination following the calcification degree of the second molar, third molar in the point of forensic odontology. The intraoral panoramic radiograph of 1600 male and 1600 female (100 persons each age) ranging from 7 to 2 years of age were studied. The developmental state of the second molar and third molar were divided into 12 stages following the calcification degree and correlations of second molar developmental stage and statistically analyzed. The results were as follows : 1. There was remarkable correlation between the development of the second molar, the third molar and age. 2. There was no significant developmental differences between the right and left second molar, third molar.(p>0.05) 3. The developmental stages of the lower second molar was more advanced than those of upper second molar. (p<0.05) 4. The developmental stages of upper third molar was more advanced than those of lower third molar. (p<0.05) 5. Both the developmental stages of second, third molars were earlier in the female than in the male. (p<0.001) 6. For the purpose of age estimation according to developmental stages of the second, third molar, linear equations are as follows. (p<0.001) second molar : male upper : Y=1.3927X + 0.2213 (r=0.72) lower : Y=1.4132X + 0.0012 (r=0.78) female upper : Y=1.4914X + 0.2151 (r=0.73) lower : Y=1.5429X - 0.0911 (r=0.78)

• The korean journal of orthodontics
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• v.26 no.1 s.54
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• pp.105-111
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• 1996

Most of orthodontic cases are treated with extraction of certain teeth, which influence the pre-eruptive movement of the lower third molar The purpose of this study was to evaluate the positional change of lower third molar following orthodontic treatment. Pre- and post-treatment pantomograms of 163 orthodontic patients (77 nonextraction group, 78 first premolar- extraction group, 8 second molar- extraction group) were analyzed in terms of the mesiodistal and buccolingual angles of lower third molar. The results were as follows. 1. The change of the mesiodistal angle of lower third molar by orthodontic treatment was significant in second molar-extraction group. 2. The mesiodistal angle of lower third molar in pre-treatment was significantly correlated to the mesiodistal angle in post-treatment and/or the change of the mesiodistal angle by treatment. 3. The change of the buccolingual angle of lower third molar by orthodontic treatment was significant in non -extraction group or first premolar-extrction group. 4. The change of the buccolingual angle of lower third molar by treatment was significantly correlated to the mesiodistal angle in post-treatment, the change of the mesiodistal angle by treatment, the buccolingual angle in pre-treatment or the buccolingual angle in post-treatment.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.6
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• pp.505-511
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• 2011

Purpose: This study evaluated correlation and risk factors between position of the mandibular third molars and mandibular angle fractures using clinical and radiographic findings. Methods: Medical records and panoramic radiographs of 188 patients with mandibular fractures were retrospectively reviewed. The presence and position of the third molars were assessed for each patient and were related to the occurrence of mandibular angle fractures. Results: The incidence of mandibular angle fracture was found to be greater when a lower third molar was present, particularly at the occlusal plane positioned on the $2^{nd}$ molar occlusal surface (by Archer system) and the third molar is impacted in mandibular ramus (by Pell & Gregory system). Of the 192 sites with a lower third molar, 32 (16%) had an angle fracture. Of the 184 site without lower third molars, 16 (8%) had an angle fracture. Conclusion: This study confirmed an increased risk of angle fractures in the presence of a lower third molar as well as variable risk for angle fracture, depending on positioning of the third molar.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.3
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• pp.207-213
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• 1998

Purpose : This study attempted to relate the incidence of fractures at the mandibular angle with the presence and state of eruption of lower third molars, and to find out the real risk factors for angle fractures in the states of lower third molars. Materials and Methods : Medical records and radiographs of 395 patients with mandibular fractures were retrospectively reviewed. The presence and states of third molars were assessed for each patients and related to the occurrence of angle and other mandibular fractures. Results : Of 395 patients with mandibular fractures, 142 had angle fractures. The incidence of angle fractures was found to be significantly greater when partial erupted lower third molars were present and it had a definite role for risk factors for angle fractures. But there were no clear relationship between the incidence of angle fracrtures and states of without, fully erupted lower third molars. Furthermore, the states of patial and unerupted lower third molar had an effect on bony segment displacement. Conclusions : This study provides clinical evidence to suggest that patial erupted third molar teeth weaken the mandibular angle both quantitatively and qualitatively.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.6
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• pp.551-553
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• 2004

The displacement of an entire tooth into the adjacent anatomical area is an uncommon complication of a tooth extraction. We encountered a 23-year-old woman who had previously undergone surgery under local anesthesia to remove the lower third molar about 12 weeks prior and the upper third molar was extracted 2 days prior to visiting this hospital. Upon admission, she complained of a swallowing discomfort and a mouth opening limitation. Panoramic radiograph and a CT scan revealed a displacement of the entire tooth into the lateral pharyngeal space. The tooth was retrieved via the transoral approach under general anesthesia. The removed tooth had an indentation formed by a dental bur. Therefore, it was concluded that the tooth displaced into the lateral pharyngeal space was the lower third molar. This report describes an unusual case of a third molar that was displaced into the lateral pharyngeal space with a review of the relevant literature.

• Korean Journal of Cleft Lip And Palate
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• v.16 no.1
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• pp.25-35
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• 2013

We report the treatment of an adult Class II malocclusion with severe crowding and a hopeless lower second molar. According to the treatment plan, 4 premolars and 4 third molars were to be extracted for 2-jaw surgery. To replace the hopeless lower second molar, one upper third molar was successfully autotransplanted during the pre-surgical orthodontic treatment. Multiple teeth are frequently extracted for treatment purposes in adult surgical cases. Under precise diagnosis, the reuse of extracted teeth to replace missing teeth can be a successful alternative even in adult surgical patients.