A 31P-magnet resonance spectroscopy study on the metabolism of human masseter in individuals with different vertical facial pattern

Objective. The objective of this study was to investigate differences in masseter metabolism by P-31-Chemical Shift Imaging (CSI) in adult individuals with different vertical facial patterns. The clinical study should be supported by functional findings at the mRNA level after orthognathic surgery. Study Design. Twenty-two male volunteers (mean age 24.6) were divided into a deep-bite (NL/ML 11.8 +/- 2.3 degrees) and open-bite group (NL/ML 34.1 +/- 2.6 degrees). Vertical jaw relationship, gonial angle, and masseter volume were defined and compared with the phosphate values obtained from the P-31 spectra. Student t test and regression analysis were used. Results. Phosphocreatine related strongly to muscle volume (P < .001), gonial angle (P < .001), and ML/NL angle (P < .01). Pi was found to be related to gonial angle (P < .05). Muscle volume was found to be inversely related to ML/NL (P < .01) and to the gonial angle (P < .01). Conclusions. A difference in masseter muscle metabolism between long- and short-faced subjects was confirmed at rest position. (Oral Surg Oral Med Oral Pathol Oral Radiol 2013;115:406-414)