Ultrasonic determination of thickness of masticatory mucosa

Objective. The aim of the present study was to assess the reliability and v alidity of ultrasonic measurements of thickness of the masticatory mucosa. Study design. Eleven periodontally healthy subjects took part. Thickness of the buccal gingiva was assessed midbuccally and interdentally. In the maxi lla, the palatal mucosa was measured at every tooth midpalatally, between t he first and second molars, and between the second and third molars at each of 3 defined locations 4 mm apart. In the mandible, thickness of the lingu al gingiva was measured midlingually as well as interdentally between the f irst and second molars and between the second and third molars. Thickness o f the retromolar mucosa was also assessed. All 1,293 measurements were repe ated after 24 hours. Validity of measurements was tested in a porcine model . Results, Mean (+/- standard deviation) thickness of the midbuccal and midli ngual gingiva was 0.99 +/- 0.52 mm; the measurement error was 0.26 mm. Meas urements were well correlated (Pearson's r=.74, P <.001). Mean thickness of the papillary gingiva was 1.19 +/- 0.53 mm; the measurement error was 0.37 mm (r =.58, P <.001). A lower reliability was observed for palatal measure ments of mucosal thickness; mean thickness was 2.36 +/- 0.87 mm, and measur ement error was 0.54 mm (r = .64, P <.001). The validity of measurements wa s excellent in the 0.5-4.5 mm range. Conclusions. Differences in reliability of ultrasonic assessments of mucosa l thickness in different parts of the oral cavity may depend on the difficu lties of repeatedly measuring at the same location, on varying thickness of the tissues, and on expression of palatal rugae. These problems might be r esolved by averaging multiple measurements.