Does Maxillomandibular Fixation Technique Affect Occlusion Quality in Segmental LeFort I Osteotomy?

Abstract

BackgroundSegmental maxillary osteotomies require precise occlusal control due to variability in individual segment positioning. The role of maxillomandibular fixation (MMF) technique on occlusal control has not been validated. PurposeThe purpose is to measure and compare the accuracy of occlusal positioning among MMF techniques. Study design, setting, sampleThis was a double-blinded in vitro study on experiment models to simulate a 3-piece LeFort I osteotomy. The models were constricted posteriorly and expanded using 3 different MMF techniques and compared to the unaltered baseline occlusion. Based on sample size calculation, 32 separate attempts were made for each MMF technique. Predictor variableThe predictor variable was MMF technique (brackets, MMF screws, embrasure wires). Main outcome variablesThe primary outcome variable was the visual occlusal analysis score (VOAS), a 1.00 to 4.00 continuous scale measuring the similarity of the achieved occlusion to the planned (control) occlusion assessed by an oral and maxillofacial surgeon and an orthodontist. High VOAS indicated greater occlusal accuracy, with 3.50 defined as the threshold for accuracy. The secondary outcome variable was the linear error of the achieved occlusion at the canine and first molar teeth, with lower error indicating greater accuracy. An a priori accuracy threshold of 0.5mm was set for this variable. CovariatesNone. AnalysesKruskal-Wallis test with post hoc testing was used to analyze the difference in the outcome variables of interest. P-value < 0.05 was considered statistically significant. ResultsThirty-two attempts for each technique showed that brackets had higher VAOS than MMF screws and embrasure wires (median differences 1.49 and 0.48, P<0.001), and had lower linear occlusal error (median differences 0.35 to 0.99mm, P<0.001). Conclusions and RelevanceMMF technique influences the quality of occlusal control, with greater visual rating scores and lower linear errors seen with brackets than with embrasure wires or MMF screws.