Biomechanical evaluation of hybrid fixation method of sagittal split ramus osteotomy in mandibular advancement

Biomechanical comparison of the efficacy of Cfr-PEEK and titanium systems in the fixation following sagittal split advancement osteotomy: a biomechanical study

BACKGROUND

This study evaluates the efficacy of carbon fiber reinforced Polyetheretherketone (Cfr-PEEK) in fixation after sagittal split ramus osteotomy (SSRO) by comparing it with titanium in vitro.

METHODS

Twenty-eight sheep hemimandibles were randomly assigned to four groups for SSRO surgery. Fixation was performed with a 4-hole titanium mini plate for 5 mm advancement in Group 1, with a 4-hole Cfr-PEEK mini plate for 5 mm advancement for Group 2, with a 4-hole titanium mini plate for 10 mm advancement for Group 3, and with a 4-hole Cfr-PEEK mini plate for 10 mm advancement for Group 4. A linear vertical load of 50 N was applied to all models from the molar region. Displacement values were recorded digitally.

RESULTS

There was a significant difference among the displacement values of four groups (p < 0.05). The highest displacement values were observed in group 2 and the lowest in group 3. The Cfr-PEEK plates' fixed groups showed lower displacement values than their titanium counterparts.

CONCLUSIONS

According to this study, Cfr-PEEK provides better stability than titanium by considering the displacement values. However, future experimental and clinical studies that include larger samples and different designs need to be done.

Does the type of sagittal split ramus osteotomy influence fixation strength? Evaluation of the mechanical behavior of two types of fixation used in three types of sagittal split ramus osteotomy

PURPOSE

This study compared the mechanical behavior of two fixation techniques used in three sections representing the sagittal split ramus osteotomy (SSRO) in polyurethane replicas that were divided into groups, according to type of section, and sub-groups according to type of fixation, simulating 11-mm advancement and 6º clockwise mandibular rotation.

METHODS

Loads were applied in two regions, aiming at progressive application and consequent strength value, measured in kilogram-force in displacements of 1, 3, 5, and 7 mm, from the load application tip. Shapiro-Wilk test was performed, followed by two-way analysis of variance (ANOVA-2 way), and Bonferroni's multiple comparison.

RESULTS

The results showed no statistically significant difference in the type of section and type of fixation used when load was applied to the inter-incisor region. However, when load was applied to the first molar region, statistically significant difference was observed in 1-mm displacement, in which section described by Epker with two modifications showed greater strength, regardless of type of fixation used (p = 0.007).

CONCLUSION

In the application of load in the inter-incisor region, there was no statistical difference between the type of osteotomy and the type of fixation used. When applying loads to molars, there was a difference for the type of osteotomy, where the Epker osteotomy with 2 modifications presented greater resistance, regardless of the type of fixation used.

Semi-Rigid Fixation Using a Sliding Plate for Treating Fractures of the Mandibular Condylar Process

Occlusal displacement often occurs after surgery for condylar process fractures because it is difficult to reduce these fractures precisely. However, performing semi-rigid fixation using a sliding plate may overcome this limitation. A retrospective clinical comparison between semi-rigid and rigid fixations was performed. Among 34 patients who had unilateral condylar process fractures, 17 were treated with rigid fixation and the remaining with semi-rigid fixation using a sliding plate. For all patients, panoramic radiographs were collected 1 day and 6 months after surgery. In these radiographs, ramus height and condylar process inclination were measured, and the differences between the fractured and normal sides were assessed. Additionally, the radiographic density of the fracture area was measured. Differences in surgical outcomes and operative times between the two groups and changes in postoperative deviations within each group were analyzed. There was no statistically significant difference in ramus height and condylar process inclination between the two groups at postoperative day 1 and 6 months. Radio-density was observed to be higher in the rigid fixation group, and it increased with time in both groups. The semi-rigid fixation group had a significantly shorter operative time than the other group did. Semi-rigid and rigid fixations showed no differences in terms of effectiveness and outcomes of surgery. In terms of operative time, semi-rigid fixation was superior to rigid fixation.