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. 2021 Mar 24:2021:8841297.
doi: 10.1155/2021/8841297. eCollection 2021.

Radiographic Position of Impacted Mandibular Third Molars and Their Association with Pathological Conditions

Zahra Haddad  1 , Mansour Khorasani  2 , Mahin Bakhshi  3 , Maryam Tofangchiha  4 , Zeynab Shalli  5
Affiliations

Radiographic Position of Impacted Mandibular Third Molars and Their Association with Pathological Conditions

Zahra Haddad et al. Int J Dent. .

Abstract

Objectives: This study aimed to assess the radiographic position of impacted mandibular third molars (IMTMs) and their association with pathological conditions.

Materials and methods: The impaction depth, relationship with ramus, and angulation of 1600 IMTMs and their association with 2nd molar distal caries and root resorption, pathological conditions, and proximity to the mandibular canal were evaluated on panoramic radiographs. The IMTM position was determined based on the depth of impaction according to the Pell and Gregory classification, relationship with ramus according to the Pell and Gregory classification, and angulation according to the Winter's classification. The classical and Bayesian logistic regressions were applied to analyze the effect of IMTM position on the associated complications using the odds ratio (OR) and 95% confidence interval (credible interval for Bayesian models). Two-tailed P value < 0.05 was considered statistically significant.

Results: Of 1600 IMTMs evaluated in this study, 195 (12.2%), 252 (15.8%), and 119 (7.4%) had caused second molar distal caries, second molar root resorption, and pathological lesions, respectively, and 872 (54.5%) had contact with the mandibular canal. Impaction angulation was a risk factor for second molar distal caries (maximum OR = 5.01, 95% CI: 3.12-8.18). Changed angulation and greater impaction depth were the risk factors for second molar root resorption (minimum OR = 1.64, 95% CI: 0.58-4.02). Decreased distance between the ramus and distal side of the second molar was a risk factor for associated pathological lesions (minimum OR = 2.73, 95% CI: 1.79-4.25). Mesioangular and horizontal angulations and greater impaction depth were the risk factors for contact with the mandibular canal (maximum OR = 3.44, 95% CI: 2.6-4.57 and minimum OR = 1.3, 95% CI: 094-1.8).

Conclusions: The frequency of complications associated with IMTMs was low, but considerable. The occurrence of these conditions might be affected by the impaction position. Thus, regular follow-ups are recommended in order to be able to surgically intervene when the first signs of pathologies arise.

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Conflict of interest statement

The authors declare that there are no conflicts of interest regarding the publication of this paper.

Figures

Figure 1
Figure 1
The questionnaire used in the study.
Figure 2
Figure 2
The impaction depth classified according to the Pell and Gregory classification with respect to the occlusal plane. Class A: the highest part of the mandibular third molar is located on the same level or above the occlusal plane of the adjacent second molar. Class B: the highest part of the mandibular third molar is located between the occlusal plane and the cervical line of the second molar. Class C: the highest part of the mandibular third molar is located below the cervical line of the second molar.
Figure 3
Figure 3
Pell and Gregory classification of ramus relation. (a) Class I: sufficient space available between the anterior border of the ascending ramus and distal side of the second molar for third molar eruption. (b) Class II: the space available between the anterior border of the ascending ramus and distal side of the second molar is less than the mesiodistal width of third molar's crown. It indicates that ascending ramus bone is covering the distal portion of the third molar crown. (c) Class III: absolute lack of space is observed; the third molar is totally embedded in the ascending ramus bone.
Figure 4
Figure 4
Angulation of impaction according to the Winter's classification. (a) Vertical impaction: 10° to −10°. (b) Mesioangular impaction: 11° to 79°. (c) Horizontal impaction: 80° to 100°. (d) Distoangular impaction: −11° to −79°. (e) Buccolingual impaction: when the crown and roots are superimposed. (f) Others: 111° to −80°.
Figure 5
Figure 5
Method of angulation measurement. The angle formed at the intersection of the two lines was measured by an orthodontic protractor.
Figure 6
Figure 6
Radiographic signs showing close relation between the mandibular third molar and the mandibular canal. (a) Darkening of root. (b) Dark and bifid apex of root. (c) Narrowing of the canal. (d) Deflection of root. (e) Interruption of white line of the canal. (f) Narrowing of root. (g) Diversion of canal.
Figure 7
Figure 7
Any radiolucency around the impacted tooth that was larger than 3 mm was considered as a pathological lesion.
See this image and copyright information in PMC

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