The Influence of the Gonial Angle on the Initial Biomechanical Stability of the Plate Osteosynthesis in Polyurethane Mandibles With Angle Fractures

Abstract

The aim of the present study was to examine the biomechanical stability of the mandibular angle fractures (MAF) fixated with standard titanium miniplates in polyurethane models with different gonial angles (GA). Three custom molds were prepared for 3-dimensional printed mandibles with low, normal and high GA. Twenty polyurethane replicas were cast per group and standard MAFs were created on each sample. Fractures were stabilized with 1 4-hole standard titanium miniplate inserted over the superior alveolar border. Half of the samples were subjected to molar loading and the other half to the incisal loading up until 150 N force magnitude. The load-displacement curves and the horizontal moment arms were recorded and analyzed. The samples with high GA demonstrated greater displacement than those with normal and low GA during molar loading (P < 0.05 for both). After correcting for the effects of the moment arm, the incisal loading also resulted in higher mean displacement in the high GA group than the others (P < 0.05 for both) and the normal GA samples showed higher displacement after 100 N level compared to those in low GA (P < 0.05). Within the limits of this in vitro study, it can be concluded that the MAFs of the polyurethane mandibles with high GA fixated with 1 standard monocortical plate are more likely to demonstrate higher displacement values under the effects of the molar and incisal loadings than do the mandibles with normal and low GA.

Correlation of radiomorphometric indices of the mandible and mandibular angle fractures

“…LGA, NGA, and HGA correspond to horizontal, normal, and vertical growth patterns, respectively. According to CT and ultrasound, the cross-section of the masticatory muscles in HGA individuals (vertical growth pattern) was smaller than that in NGA and LGA individuals [ 17 , 37 , 38 , 39 ]. Moreover, the muscle morphology in HGA individuals results in relatively lower masticatory force or function, which leads to a reduction in cortical bone thickness at the angle of mandible.…”

“…The gonial angle (GA) is an anthropometric parameter used for assessment of the mandibular growth pattern [ 8 ]. Low gonial angle (LGA), normal gonial angle (NGA), and high gonial angle (HGA) correspond to horizontal, normal, and vertical growth, respectively [ 17 ]. Also, evidence shows that a vertical growth pattern is correlated with a shorter ramus height [ 7 ].…”

“…The cross-sectional thickness of the muscles of mastication in HGA individuals is lower than that in LGA, and NGA individuals. Also, mandibular height, masticatory force, and alveolar cortical thickness are inversely correlated with the size of GA [ 17 ].…”

Magnitude of gonial angle influence on the commonness of mandibular angle fractures

“…Sirin et al . [ 21 ] studied the biomechanical stability of mandibular angle fractures with different gonial angles. Their study on polyurethane mandibles revealed higher displacement in the high gonial angle group as compared to both normal and low-angle groups, both at molar and incisal loading.…”

The biomechanical stability of miniplate osteosynthesis configurations in bilateral mandibular angle fractures

“…Two acrylic templates for the bilateral fracture lines and four for plate insertion were prepared. A box cutter was positioned over the fracture line and a rubber headed mallet was used to drive the box cutter into the fracture line until complete separation occurred [14]. The fracture segments were checked and then repositioned using the plate template.…”