Prevalence of mandibular, condylar and ramus asymmetry in panoramic radiographs of adult individuals. A cross-sectional study

Abstract

Background: Mandibular asymmetry is more common than previously thought. The purpose of this study was to determine the prevalence of mandibular, condylar and ramus asymmetry by means of the Habets index using panoramic radiographs obtained from adult individuals.

Material and methods: This cross-sectional study evaluated 210 panoramic radiographs performed in adults attending a private referral radiology center in Lima, Peru. Radiographs of both genders were considered, including permanent dentition and of good quality. A trained and calibrated evaluator assessed mandibular, condyle and ramus height using the Habets method, considering asymmetry when the difference between the two sides was greater than 3%. Fisher's exact test, the paired Student's t-test and finally binary logistic regression were used to determine the characteristics of the asymmetries.

Results: Mandibular asymmetry was present in 39.5%, condylar asymmetry in 81.4% and mandibular ramus asymmetry in 48.6%, with no differences between genders (P>0.05). Only women showed a difference between the two sides in mandibular (P=0.008), and condylar height (P=0.013), although multivariate analysis showed neither gender nor age to have any significant influence on the occurrence of mandibular, condylar or ramus asymmetries.

Conclusions: The prevalence of mandibular, condylar and ramus asymmetries in the sample evaluated was significant, although most of these asymmetries can be considered mild, given that the highly sensitive Habets index classifies any difference greater than 3% as asymmetry. These asymmetries, although most of them could be clinically not very noticeable, should be considered when planning treatments. In addition, neither gender nor age was found to significantly influence the occurrence of these asymmetries. Key words:Asymmetry, condyle, mandible, orthodontics.

Figure 1

The most lateral point of the mandibular condyle (O1), the most lateral point of the mandibular ramus (O2), and the most superior point of the condyle.

Figure 2

Line A, which represents a tangent line on the mandibular ramus, drawn from O1 to O2, and Line B, which is perpendicular from line A to the most superior area of the condyle. Condylar height (CH), defined as the distance from the point of intersection of line B with line A to point O1; ramus height (RH), determined as the distance between points O1 and O2 measured on line A; and CH and CH, which consisted of the sum of the two previous measurements.