Objective: The aim of the present study was to assess the reliability and validity 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 maxilla, the palatal mucosa was measured at every tooth midpalatally, between the 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 lingual gingiva was measured midlingually as well as interdentally between the first and second molars and between the second and third molars. Thickness of the retromolar mucosa was also assessed. All 1,293 measurements were repeated after 24 hours. Validity of measurements was tested in a porcine model.
Results: Mean (+/- standard deviation) thickness of the midbuccal and midlingual gingiva was 0.99+/-0.52 mm; the measurement error was 0.26 mm. Measurements 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 measurements of mucosal thickness; mean thickness was 2.36+/-0.87 mm, and measurement error was 0.54 mm (r = .64, P<.001). The validity of measurements was excellent in the 0.5-4.5 mm range.
Conclusions: Differences in reliability of ultrasonic assessments of mucosal thickness in different parts of the oral cavity may depend on the difficulties of repeatedly measuring at the same location, on varying thickness of the tissues, and on expression of palatal rugae. These problems might be resolved by averaging multiple measurements.