Marginal bone loss in the second molar related to impacted mandibular third molars: comparison between panoramic images and cone beam computed tomography.

Mj Dias,A Franco,Jl Junqueira,Ft Fayad,Ac Oenning,Ph Pereira

doi:10.4317/medoral.23443

Abstract

Background Deciding whether or not to extract third molars remains a controversial situation in dental practice. Image exams support this decision by enabling a close view of the third molar, its adjacent bone and its relationship with the second molar. This study aimed to assess and compare second molar bone loss adjacent to impacted mandibular third molar in panoramic radiographs (PAN) and cone beam computed tomography (CBCT) scans. Material and Methods A sample of 70 patients was selected (n=124 teeth). Each patient had a set of a panoramic radiograph and CBCT scans consecutively taken for dental treatment purposes. In PAN and CBCT, mandibular third molars were classified based on their position and bone loss of the adjacent second molar. Agreement between PAN and CBCT scans was assessed and quantified. Results Outcomes of bone loss assessment were different between PAN and CBCT scans (p<0.05). Bone loss was found in 62.9% of the PAN, while in CBCT scans it was found in 80%. In particular, nearly 29% (n=27) of the teeth that were classified without bone loss in PAN were classified with bone loss in CBCT scans. Mesioangular and horizontal third molars had a statistically significant association with bone loss of the adjacent second molars (p<0.05). In general, PAN underestimated the severity of bone loss compared to CBCT scans (p<0.05). Conclusions Diagnosing second molar bone loss due to impaction of adjacent third molar in PAN may be challenging because of false negatives. Impacted third molars justify preoperative CBCT scans if second molar bone loss needs to be precisely assessed for a more detailed and reliable treatment plan. Key words:Bone, CBCT, panoramic radiograph, third molar.

Highlights

Periodontal health and prognosis of teeth directly depend on the available bone support [1]
cone beam computed tomography (CBCT) scanning after panoramic radiograph was justified for therapeutic purposes – all the patients were scheduled for third molar removal and had the position of their third molars and the inherent anatomic relation with adjacent teeth and mandibular canal three-dimensionally analyzed via CBCT scans
This outcome was expected because CBCT scans enable a three-dimensional and slice-by-slice view of the second and third molars and their relationship with adjacent bone structures, which allow the determination of the bone level in different directions, without the typical superimposition observed in two-dimensional exams of infrabony or combined defects

Summary

Introduction

Periodontal health and prognosis of teeth directly depend on the available bone support [1]. Bone loss may be induced by several factors, such as smoking habit [2], level of education [2] and the presence of adjacent impacted tooth [3] The latter plays an important part in the contemporary dental practice because tooth impaction is often found, especially involving mandibular third molars [4]. Based on the exposed justification, this study aimed at assessing and comparing the detection and severity of second molar bone loss adjacent to impacted third molars between panoramic radiographs and CBCT scans. Deciding whether or not to extract third molars remains a controversial situation in dental practice Image exams support this decision by enabling a close view of the third molar, its adjacent bone and its relationship with the second molar. This study aimed to assess and compare second molar bone loss adjacent to impacted mandibular third molar in panoramic radiographs (PAN) and cone beam computed tomography (CBCT) scans. Impacted third molars justify preoperative CBCT scans if second molar bone loss needs to be precisely assessed for a more detailed and reliable treatment plan

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Conclusion