• 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.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.2
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• pp.66-73
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• 2015

Objectives: To assess the validity of the vertical tube-shift method using intraoral periapical radiography (IOPAR) for determining the relationship between the mandibular third molar roots and the inferior alveolar nerve (IAN) canal in comparison with cone-beam computed tomography (CBCT). Materials and Methods: Fifty impacted mandibular third molars were analyzed using the IOPAR vertical tube-shift method and CBCT. The relationship of the IAN canal to the impacted mandibular third molar was recorded as buccal, lingual or in line with the apex and was compared with CBCT findings. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the vertical tube-shift method in depicting the relationship (buccal/lingual/in line with the apex) of the IAN canal to the third molar root apex was calculated. Results: The sensitivity and specificity PPV and NPV of the IOPAR vertical tube-shift technique was found to be highest for a lingual relationship (100%) followed by buccal (94.4%, 92.3%, 97.1%, and 85.7%) and in line with the apex relationship (88.9%, 95.0%, 80.0%, and 97.4%) of the IAN canal with the third molar root apex, respectively. A statistically significant association was observed between the IOPAR vertical tube-shift method and the CBCT with a P-value <0.01. Conclusion: The vertical tube-shift method can be used as an effective diagnostic tool in assessing the relationship of the IAN canal to the third molar root apex with high sensitivity, specificity, PPV, and NPV.

• Imaging Science in Dentistry
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• v.44 no.3
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• pp.185-191
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• 2014

Purpose: This study investigated the developmental stages of third molars in relation to chronological age and compared third molar development according to location and gender. Materials and Methods: A retrospective analysis of panoramic radiographs of 2490 patients aged between 6 and 24 years was conducted, and the developmental stages of the third molars were evaluated using the modified Demirjian's classification. The mean age, standard deviation, minimal and maximal age, and percentile distributions were recorded for each stage of development. A Mann-Whitney U test was performed to test the developmental differences in the third molars between the maxillary and mandibular arches and between genders. A linear regression analysis was used for assessing the correlation between the third molar development and chronological age. Results: The developmental stages of the third molars were more advanced in the maxillary arch than the mandibular arch. Males reached the developmental stages earlier than females. The average age of the initial mineralization of the third molars was 8.57 years, and the average age at apex closure was 21.96 years. The mean age of crown completion was 14.52 and 15.04 years for the maxillary and the mandibular third molars, respectively. Conclusion: The developmental stages of the third molars clearly showed a strong correlation with age. The third molars developed earlier in the upper arch than the lower arch; further, they developed earlier in males than in females.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.19-24
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• 1986

The author performed radiographical analysis of the third molar dentition and characteristic relation to anatomical oral structure. For this purpose 506 orthopantomagraph film, male 283cases and female 223 cases, aged from 15 to 30 years were evaluated by means of Winter's classification in conjunction with some other methods. Through the study following results were obtained; 1. The eruption of(equation omitted) were found in 229 cases followed by 61 cases of(equation omitted) and 45 cases showed no evidence of eruption. 2. The classification based on the relation of ramus to distal portion of the 2nd molar revealed class Ⅱ, 460 cases (61.8%) and 182 cases (24.5%) were class Ⅲ. 3. Parallelism between long axis of mandibular third molar and the second molar were found in 302 cases (40.8%) and mesial inclination of the third molar were 280 cases (37.6%). 4. Average inclination degree among these cases showed 138.62±12.56°.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.1
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• pp.29-39
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• 2021

Background: Impacted mandibular third molar removal is one of the most commonly performed oral surgical procedures. This procedure can lead to several postoperative complications, such as trismus, facial swelling, and pain, which occur as a result of the inflammatory responses to surgery. This study compared the efficiency of preoperative injections of 4 mg versus 8 mg dexamethasone into the pterygomandibular space to reduce postoperative sequelae. Methods: This was a randomized, prospective, split-mouth, controlled study, including 52 mandibular third molar surgeries in 26 patients. Each patient was randomized to either the 4 mg or 8 mg dexamethasone injection group. Dexamethasone was injected into the pterygomandibular space after numbness from local anesthesia. Data were collected for trismus, facial swelling, visual analog scale (VAS) pain score, and the number of analgesics taken during the evaluation period. The level of significance was set at P < 0.05. Results: Statistically significant differences in postoperative facial swelling (P = 0.031, diff = 1.4 mm) and pain (P = 0.012, diff = 0.020) were found between the 8 mg and 4 mg dexamethasone groups. However, there were no significant differences between the groups for trismus and the total number of analgesics consumed (P > 0.05). Conclusion: Compared to the 4 mg preoperative dexamethasone injection, the 8 mg preoperative dexamethasone injection into the pterygomandibular space was more effective in reducing postoperative swelling and pain following the surgical removal of the impacted mandibular third molar. However, the difference in trismus could not be evaluated clinically. Therefore, the recommendation of administering the 4 mg dexamethasone preoperative injection is optimal in the third molar surgical procedure.

• Imaging Science in Dentistry
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• v.38 no.3
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• pp.163-167
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• 2008

Purpose : The purpose of this study is to evaluate the position of the mandibular canal in relation to the mandibular third molar by cone beam CT in cases showing a close relationship between the third molar and the mandibular canal on the panoramic radiograph. Materials and Methods : The panoramic images and cone beam CT scans of 87 impacted mandibular third molars in 60 patients were evaluated to assess the tooth relationship to the mandibular canal. The clearness of the canal wall and the vertical depth of the lower third molar were evaluated on panoramic radiographs. The lower third molars were assessed using cone beam CT to determine the proximity and position of the canal relative to the roots. Results : In the 66 cases where the canal wall was unclear on the panoramic radiographs, 58 (87.9%) of the third molars had contact between the canal and root; 34 (51.5%) canals were showed an inferior position and 22 (33.3%) showed a linguoinferior position on cone beam CT. Conclusion : Interruption of the canal wall on panoramic radiographs was highly predictive of contact between the mandibular canal and the third molar. Cross sectional CT may be indicated for localization of the mandibular canal in such cases.

• The korean journal of orthodontics
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• v.10 no.1
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• pp.55-64
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• 1980

The purpose of this study was to investigate the interrelationship of the experimental group and control group by analyzing case histories, intraoral radiographs, orthopantomographs, intraoral slide films and dental casts. The data for this study were complied from 654 outpatients of the Department of Orthodontics, Seoul National University Hospital. The following conclusions were obtained. 1. When one or more thins molar teeth were congenitally missing, the incidence of the other congenitally missing teeth was high. 2. The frequency of congenitally missing teeth was comparatively higher in male, maxilla, class II and class III. 3. The congenitally missing srea of the third molar by Angle's classification was not significant. 4. The order of frequency of congenitally missing teeth was the third molar, the second premolar, the lateral incisor, the first premolar, the central incisor, the canine, the first molar, the second molar.

• 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.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.5
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• pp.242-245
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• 2013

Impacted mandibular third molars are located between the second mandibular molar and mandibular ramus. However, ectopic mandibular third molars with heterotopic positions are reported in the subcondylar or pterygomandibular space. The usual cause of malposition is a cyst or tumor, and malposition without a pathology is rare. This case report described an impacted mandibular third molar in the pterygomandibular space without any associated pathology.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.5
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• pp.326-328
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• 2022

Impacted mandibular third molar removal is the most common procedure performed by oral and maxillofacial surgeons. An array of alternative procedures have been suggested, like operculectomy in cases of pericoronitis and coronectomy in certain cases. However, these procedures pose several disadvantages, and we propose a relatively non-invasive 'straight lift technique'. This technique is specifically useful in straightening abnormally positioned mesioangular third molars as a substitute of complete removal. This can improve tooth function, eliminate the need for surgical intervention, and reduce the risk of complications associated with third molar removal.