Effect of bone thickness on alveolar bone-height measurements from cone-beam computed tomography images.

INTRODUCTION: Cone-beam computed tomography (CBCT) has been used to assess alveolar bone changes after rapid palatal expansion. The purpose of this study was to investigate the accuracy of alveolar bone-height measurements from CBCT images with varied bone thicknesses and imaging resolutions. METHODS: Eleven maxillary specimens from 6-month-old pigs were measured for alveolar bone height (distance between drilled reference holes and alveolar crests) at 6 locations with a digital caliper, followed by CBCT scanning at 0.4-mm and 0.25-mm voxel sizes. Buccal alveolar bone of these locations was then reduced approximately by 0.5 to 1.5 mm, followed by CBCT rescanning with the same voxel sizes. The CBCT images were measured by using 3-dimensional software to determine alveolar bone height and thickness in buccolingual slices by independent, blinded raters. The specimens were subsequently cut into buccolingual sections at reference-hole levels, and direct bone height and thickness were measured from these sections. Intrarater and interrater repeatability and the differences between CBCT and direct measurements were assessed. RESULTS: Excellent intrarater (intraclass correlations, r = 0.89-0.98) and good interrater (r = 0.64-0.90) repeatability values were found for alveolar bone-height measurements from the CBCT images. Before alveolar bone reduction, the thickness was much greater than the CBCT voxel size (0.4 mm), and bone-height measurements from the CBCT images were 0.5 to 1 mm more than the direct measurements (paired t tests, P <0.017 at most locations). After bone reduction, the thickness at the subcrest 1-mm level was near or below the CBCT voxel size (0.4 mm), and bone-height measurements from the CBCT images were 0.9 to 1.2 mm less than the direct measurements (paired t tests, P <0.017 at most locations). These measurement inaccuracies were substantially improved by decreasing the CBCT voxel size to 0.25 mm. CONCLUSIONS: Alveolar bone-height measurements from conventional clinical 0.4-mm voxel size CBCT images might overestimate alveolar bone-height loss associated with rapid palatal expansion.

Local anesthesia affects physiologic parameters and reduces anesthesiologist intervention in children undergoing general anesthesia for dental rehabilitation.

PURPOSE: The purpose of this study was to evaluate the use of intraoperative local anesthetics in pediatric outpatient dental surgery. This study assessed physiologic stability, as defined by fluctuations in end-tidol carbon dioxide, heart rate, and respiratory rate, as well as subsequent anesthesiologist intervention. METHODS: Forty-eight children (mean age = 3.87 years [+/- l.06 SD]) were included in this randomized, parallel-design study. Intervention variables and the research design were validated in a pilot study. Following collection of baseline vital signs, patients were either given local anesthesia before comprehensive dental treatment or not. Vital sign change was recorded 30 seconds after each procedure. RESULTS: In the no local anesthetic group, 2 areas were found to be statistically significant: (1) postextraction end-tidal carbon dioxide; and (2) heart rate. There was a statistically significant relationship between local anesthetic use and anesthesiologist intervention when assessing the pooled data (P = .001). CONCLUSION: Patients who were not given intraoperative local anesthesia were more likely to experience vital sign fluctuation requiring anesthesiologist intervention.