Magnetic resonance spectroscopy of the masseter muscle in different facial morphological patterns

American Journal of Orthodontics and Dentofacial Orthopedics : Official Publication of the American Association of Orthodontists, Its Constituent Societies, and the American Board of Orthodontics
E T Al-FarraJ Ghafari

Abstract

The aims of this study were (1) to develop a reliable noninvasive method to evaluate the masseter muscle metabolism, by using (31)P-magnetic resonance spectroscopy, and (2) to evaluate the metabolic profile of the masseter muscle in subjects with various facial patterns. The maxillary-mandibular relationship, which varied from hypodivergent to hyperdivergent, was measured on lateral cephalograms of 20 adults, 22 to 35 years of age. (31)P-spectra were acquired from the masseter muscle at rest with a custom-made, single-turn, double-tuned, 3 x 5-cm oblong surface coil. The inorganic phosphate to phosphocreatine (Pi/PCr) ratios were measured and compared in relation to vertical and sagittal cephalometric measurements. A statistically significant (R(2) = 0.65, r = 0.81, P = .001) relationship was found between Pi/PCr ratio and the palatal-to-mandibular plane angle. As the maxillary-to-mandibular divergence increased, the Pi/PCr ratio decreased. This correlation suggests that muscles with a higher Pi/PCr ratio have a higher resting metabolic activity than those with a lower Pi/PCr ratio. Consequently, these muscles may keep bone under more tension and influence its growth in a more horizontal direction. Another possible explanation ...Continue Reading

Citations

May 6, 2009·The Angle Orthodontist·Michelle Santos Vianna-LaraMaise Mendonça Amorim

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