Mechanobehavior and mandibular ramus length in different facial phenotypes

Abstract

Objectives To test the hypotheses that mechanobehavior scores (MBS) were correlated with mandibular ramus lengths (Co-Go) and differed between facial phenotypes. Materials and Methods Subjects gave informed consent to participate. Co-Go (mm), mandibular plane angles (SN-GoGn, °), and three-dimensional anatomy were derived from cephalometric radiography or cone beam computed tomography. Temporomandibular joint (TMJ) energy densities (ED) (mJ/mm3) were measured using dynamic stereometry and duty factors (DF) (%) were measured from electromyography, to calculate MBS (= ED2 × DF,) for each TMJ. Polynomial regressions, K-means cluster analysis, and analysis of variance (ANOVA) with Tukey post-hoc tests were employed. Results Fifty females and 23 males produced replete data. Polynomial regressions showed MBS were correlated with Co-Go (females, R2 = 0.57; males, R2 = 0.81). Cluster analysis identified three groups (P < .001). Dolichofacial subjects, with shorter normalized Co-Go, clustered into two subgroups with low and high MBS compared to brachyfacial subjects with longer Co-Go. SN-GoGn was significantly larger (P < .03) in the dolichofacial subgroups combined (33.0 ± 5.9°) compared to the brachyfacial group (29.8 ± 5.5°). Conclusions MBS correlated with Co-Go within sexes and differed significantly between brachyfacial and dolichofacial subjects.

Evaluation of associations between condylar morphology, ramus height, and mandibular plane angle in various vertical skeletal patterns: a digital radiographic study

“…Distinctive facial characteristics of individuals with different vertical skeletal growth patterns include differences in mandibular ramus heights and mandibular plane angles, and mandibular condyle morphology and position can be significantly affected by the posterior rotation of the mandible [6,7]. The idea that there may be a relationship between mandibular condylar sizes, condylar position, condylar morphology, ramus height, and vertical skeletal pattern has been discussed in the literature [1,6,[8][9][10][11]. Individuals with a high-angle pattern may have lower mandibular ramus heights than individuals with normal angle and low-angle patterns [1,9].…”

Behavior of the mandibular length in class II non-growing patients treated with jaw functional orthopedics

“…According to Riddle et al [24] Much has to be studied about the behavior of the mandible when subjected to biomechanical alterations. Gender and facial biotype influence the mechanical behavior of the mandibular ramus length.…”

A theoretical analysis of longitudinal temporomandibular joint compressive stresses and mandibular growth

“…These shortcomings can be addressed through a prospective study to characterize the variables relevant to growth of the mandibular condyles that are individual-specific by employing longitudinal imaging of the TMJ and craniofacial anatomy, in combination with data about jaw-loading behaviors from jaw muscle electromyography, TMJ forces from numerical modeling, and three-dimensional joint contact mechanics from dynamic stereometry. 27 These approaches have been combined to give TMJ ''mechanobehavior scores'' in living humans 14,17,22 and have potential to improve understanding of factors that influence the clinical outcomes of functional appliances in children.…”

“…Variations in functional temporomandibular joint (TMJ) loading patterns in different dentofacial phenotypes have been described. [12][13][14] In part, these variations can result from age-related changes in craniomandibular mechanics and occlusal forces. In addition, in vitro experiments suggested, depending on loading force magnitudes and frequencies, it was possible to inhibit or stimulate mandibular condylar cartilage growth.…”