Predictor Mandibular Dentoalveolar Features on the Occurrence of 1-Rooted/C-Shaped Mandibular Second Molar Teeth

OBJECTIVE

This study aimed to examine the mandible form features of the mandible, such as inter-second molar width, anteroposterior length, arch perimeter length, arch breadth, corpus height/width in the mandibular second molars (MnSM) region, and arch form, and the relation for the occasion of the 1-rooted/C-shaped.

METHODS

The study analyzed cone-beam computed tomography images of 215 male and 215 female Turkish patients to determine the prevalence of 1-rooted and C-shaped MnSM. Mandibular dentoalveolar characteristics of individuals with bilateral (1R-1R group) and unilateral (1R-2R group) 1-rooted MnSM were examined and compared with those with bilateral 2-roots (2R-2R group) MnSM. Statistical tests were performed using Chi-square, one-way ANOVA, Tukey, and binary logistic regression analysis at the 5% significance level.

RESULTS

The prevalence of 1-rooted and 1-rooted/C-shaped MnSM was 12.79% and 9.65%, respectively. Root fusion was more commonly present in females (p<0.05). In the 1R-1R group, the anteroposterior length was shorter than in the 2R-2R group (p<0.05). There was no difference between the groups for other features (p>0.05).

CONCLUSION

Although the study found a shorter anteroposterior length in the 1R-1R group, no feature was a predictive variable for 1-rooted/C-shaped MnSM.

Examining Interobserver Reliability of Metric and Morphoscopic Characteristics of the Mandible

Mandibular metric and morphological characteristics have long been used for sex and ancestry estimation. Currently, there are no large-scale studies examining interobserver agreement, particularly examining the role of observer experience. This study examines the interobserver agreement of six morphoscopic and eleven metric mandibular variables. Four observers with varied levels of experience scored 183 mandibles from the William M. Bass Donated Skeletal Collection. Absolute agreement and consistency were evaluated with the intraclass correlation coefficient (ICC). Additionally, technical error of measurement (TEM) and relative TEM (%TEM) were calculated for each metric variable. All analyses were conducted twice-once with all observers and again with only experienced observers. Results show mean morphoscopic agreement of 0.543 among all observers and 0.615 for experienced observers, and mean metric agreement of 0.886 among all observers and 0.911 for experienced observers. Further, no TEM exceeded 2 mm. All results were significant (p < 0.001).

Evaluation of mandibular morphology in different facial types

The purpose of this study was to evaluate mandibular morphology in different facial types using various parameters. This study was conducted on lateral cephalograms of a total of 110 subjects, which included 55 males and 55 females between the age of 18-25 years having a mean of 22.3 years for males and 21.5 years for females. The sample was divided into normodivergent, hypodivergent, and hyperdivergent subgroups based on Jarabak's ratio. Symphysis height, depth, ratio (height/depth) and angle, antegonial notch depth, ramal height and width, mandibular depth, upper, lower, and total gonial angle, and mandibular arc angle were analyzed statistically and graphically. It was found that the mandible with the vertical growth pattern was associated with a symphysis with large height, small depth, large ratio, small angle, decreased ramus height and width, smaller mandibular depth, increased gonial angle, and decreased mandibular arc angle in contrast to mandible with a horizontal growth pattern. Sexual dichotomy was found with mean symphysis height and depth in the female sample being smaller than in the male sample, but symphysis ratio was larger in the female sample; males having greater ramus height and width, mandibular depth than females. The mandible seemed to have retained its infantile characteristics with all its processes underdeveloped in hyperdivergent group.