Validation of measurements of mandibular protrusion in the treatment of obstructive sleep apnoea and snoring with a mandibular protruding device.

The aims of this study were to compare the maximum range of protrusion determined with a ruler with measurements made using a George Gauge (GG) and to validate the methods of measurement (ruler and GG) of the advancement established by mandibular protruding devices (MPDs), using cephalograms as the gold standard. The study comprised 77 patients (63 males, 14 females, mean age 54 years, range 31-73 years) with obstructive sleep apnoea (OSA) (n = 50) or complaints of snoring (n = 27). After a medical examination that included an overnight somnographic registration and a dental and stomatognathic examination, each patient was given a MPD. Measurements of the maximum range of protrusion with the GG and a ruler were compared. Pairs of upright cephalograms were taken with and without the MPD. The position of the mandible on the cephalograms was compared with ruler measurements of the device-induced protrusion in the incisor and premolar regions, the vertical opening in the anterior region, and GG construction bite registration. The maximum range of protrusion was significantly greater with GG than ruler measurements, on average +1.2 mm (P < 0.001). The mandibular position as measured in the incisor or premolar region with a ruler or on the cephalogram was not significantly different. GG values, however, were higher and differed significantly from ruler and cephalometric measurements (P < 0.001). The degree of anterior mandibular advancement with a MPD measured with a ruler in the incisor or premolar regions compared well with corresponding cephalometric measurements. The ruler and cephalometric measurements of the vertical opening with the MPD coincided well in the incisor region. The GG overestimated the maximum range of protrusion compared with ruler measurements.