Mandibular third molar teeth have the highest impaction frequency for several reasons such as lack of space which may be related to the direction of facial growth. Gonial angle is used for the definition of facial growth pattern with some other measures such as mandibular plane angle. Winter and Pell–Gregory classifications are used for defining the level and pattern of mandibular third molar impaction. The aim of this study is to define the relationship between mandibular third molar impaction pattern and gonial angle; also to evaluate relationship between mandibular third molar roots and inferior alveolar canal. Study included 90 patients who had undergone cone beam computed tomography assessment for mandibular third molar impaction. Impacted teeth were grouped according to Pell–Gregory depth (A, B, C) and ramus (1, 2, 3) classification and sub-groups were composed. Winter classification was used for angulation of third molars and their relationship between with inferior alveolar canal was recorded. Gonial angle was measured on panoramic radiographs. Of the evaluated 90 impacted third molars, mesioangular position was the most frequent (34.4%), followed by vertical, horizontal and distoangular positions. Nearly 77% of the impacted third molar roots were related to inferior alveolar canal. While no correlation was determined between gender, age, third molar angulation and gonial angle, C2 sub-group of Pell–Gregory classification showed statistically significant higher gonial angle values. Although no significance was found, gonial angle was higher in level C group. In conclusion, gonial angle is higher in patients with C2 impaction level. Also, although statistically insignificant, Pell–Gregory C group had higher gonial angle averages.
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Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
For this study, ethical approval was taken from İstanbul Medipol University Ethics Committee (No.: 329/2019).
Statement of clinical relevance
Gonial angle, which is one of the measures of facial growth pattern, can be evaluated on panoramic radiographs. Gonial angle may be related to third molar impaction estimation and impaction of third molars may affect orthodontic treatment modalities.
Akarslan ZZ, Kocabay C (2009) Assessment of the associated symptoms, pathologies, positions and angulations of bilateral occurring mandibular third molars: is there any similarity? Oral Surg Oral Med Oral Pathol Oral Radiol 108:26–32CrossRefGoogle Scholar
Araki M, Kiyosaki T, Sato M, Kohinata K, Matsumoto K, Honda K (2015) Comparative analysis of the gonial angle on lateral cephalometric radiographs and panoramic radiographs. J Oral Sci 57:373–378CrossRefGoogle Scholar
Behbehani F, Artun J, Thalib L (2006) Prediction of mandibular third-molar impaction in adolescent orthodontic patients. Am J Orthod Dentofac Orthop 130:47–55CrossRefGoogle Scholar
Eshghpour M, Nezadi A, Moradi A, Shamsabadi RM, Rezaei NM, Nejat A (2014) Pattern of mandibular third molar impaction: a cross-sectional study in northeast of Iran. Niger J Clin Pract 17:673–677CrossRefGoogle Scholar
Girish Katti G, Chandrika Katti C, Karuna Shahbaz S, Khan M, Ghali SR (2016) Reliability of panoramic radiography in assessing gonial angle compared to lateral cephalogram in adult patients with Class I malocclusion. J Indian Acad Oral Med Radiol 28:252–255CrossRefGoogle Scholar
Gu L, Zhu C, Chen K, Liu X, Tang Z (2018) Anatomic study of the position of the mandibular canal and corresponding mandibular third molar on cone-beam computed tomography images. Surg Radiol Anat 40:609–614CrossRefGoogle Scholar
Gupta R, Sharma M, Singh S (2017) Mandibular third molar impactions in relation to different skeletal facial axis groups: a radiographic evaluation. J Appl Dent Med Sci 3:49–55Google Scholar
Hashemipour M, Tahmasbi-Arashlow M, Farnaz Fahimi-Hanzaei F (2013) Incidence of impacted mandibular and maxillary third molars: a radiographic study in a Southeast Iran population. Med Oral Patol Oral Cir Bucal 18:140–145CrossRefGoogle Scholar
Hassan AH (2010) Pattern of third molar impaction in a Saudi population. Clin Cosmet Investig Dent 2:109–113CrossRefGoogle Scholar
Ishii S, Abe S, Moro A, Yokomizo N, Kobayashi Y (2017) The horizontal inclination angle is associated with the risk of inferior alveolar nerve injury during the extraction of mandibular third molars. Int J Oral Maxillofac Surg 46:1626–1634CrossRefGoogle Scholar
Juodzbalys G, Daugela P (2013) Mandibular third molar impaction: review of literature and a proposal of a classification. J Oral Maxillofac Res 4:1–12CrossRefGoogle Scholar
Kaur R, Kumar AC, Garg R, Sharma S, Rastogi T, Gupta VV (2016) Early prediction of mandibular third molar eruption/impaction using linear and angular measurements on digital panoramic radiography: a radiographic study. Indian J Dent 7:66–69CrossRefGoogle Scholar
Kositbowornchai S, Densiri-aksorn W, Piumthanaroj P (2010) Ability of two radiographic methods to identify the closeness between the mandibular third molar root and the inferior alveolar canal: a pilot study. Dentomaxillofac Radiol 39:79–84CrossRefGoogle Scholar
Kumar SS, Thailavathy V, Srinivasan D, Loganathan D, Yamini J (2017) Comparison of orthopantomogram and lateral cephalogram for mandibular measurements. J Pharm Bioallied Sci 9:92–95CrossRefGoogle Scholar
Kundi IU, Baig MN (2018) Reliability of panoramic radiography in assessing gonial angle compared to lateral cephalogram. Pakistan Oral Dent J 33:320–323Google Scholar
Legović M, Legović I, Brumini G, Vandura I, Cabov T, Ovesnik M, Mestrović S et al (2008) Correlation between the pattern of facial growth and the position of the mandibular third molar. J Oral Maxillofac Surg 66:1218–1224CrossRefGoogle Scholar
Mollaoglu N, Çetiner S, Güngör K (2002) Patterns of third molar impaction in a group of volunteers in Turkey. Clin Oral Invest 6:109–113CrossRefGoogle Scholar
Muñoz G, Dias FJ, Weber B, Betancourt P, Borie E (2017) Anatomic relationships of mandibular canal. A cone beam CT study. Int J Morphol 35:1243–1248CrossRefGoogle Scholar
Richardson ME (1977) The etiology and prediction of mandibular third molar impaction. Angle Orthod 47:165–172PubMedGoogle Scholar
Tassoker M, Kok H, Sener S (2019) Is there a possible association between skeletal face types and third molar impaction? A retrospective radiographic study. Med Princ Pract 28:70–74CrossRefGoogle Scholar
Uthman AT (2007) Retromolar space analysis in relation to selected linear and angular measurements for an iraqi sample. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 104:76–82CrossRefGoogle Scholar
Yilmaz S, Adisen MZ, Misirlioglu M, Yorubulut S (2016) Assessment of third molar impaction pattern and associated clinical symptoms in a central anatolian Turkish population. Med Princ Pract 25:169–175CrossRefGoogle Scholar