Identification of Specific Panoramic High-Risk Signs in Impacted Third Molar Cases in Which Cone Beam Computed Tomography Changes the Treatment Decision.

PURPOSE: The aim of this study was to investigate the treatment decisions of oral-maxillofacial surgeons in the management of impacted lower third molars (M3s) according to panoramic radiography (PR) and cone beam computed tomography (CBCT) risk analysis. PATIENTS AND METHODS: Ten surgeons analyzed 40 deliberately selected M3 cases showing 1 or more panoramic high-risk signs: 1) darkening of the root, 2) interruption of the white line, 3) diversion of the inferior alveolar canal (IAC), 4) narrowing of the IAC, and 5) 2 or more signs occurring simultaneously (including darkening and/or interruption of the IAC). After evaluating the PR images, the observers analyzed the patients' CBCT images. The treatment decision (extraction vs coronectomy) and surgical technique (number of planned tooth sections) were recorded. RESULTS: On the CBCT coronal slices, direct contact between the M3 and IAC, together with narrowing and/or fenestration of the IAC, was observed most frequently when 2 or more panoramic signs were seen simultaneously on the PR images (odds ratio [OR], 7.2; P = .021). CBCT findings led to a significant decrease in the number of coronectomy decisions (23% vs 14.5%, P = .002), which was most prominent in the groups showing panoramic signs of darkening (approximately 50%, P = .007) and narrowing (approximately 66%, P = .044). A significant number of extraction decisions were modified to coronectomy when 2 or more panoramic signs occurred together (OR, 7.9; P < .001). However, there were no significant differences regarding the number of planned hypothetical tooth sections. CONCLUSIONS: The results showed that the surgeons' confidence in the treatment decision increased after CBCT imaging, resulting in fewer coronectomy decisions. CBCT information that changed a previous coronectomy decision to extraction was most frequently observed in cases showing darkening and narrowing PR signs. The chance of changing an extraction decision to a coronectomy decision after evaluating the patient's CBCT images was the highest when 2 or more PR signs were observed simultaneously.

Intraosseous Heat Production and Preparation Efficiency of Surgical Tungsten Carbide Round Drills: The Effect of Coronectomy on Drill Wear.

PURPOSE: The aim of this in vitro study was to examine the effects of surgical drill wear after coronectomy on bone temperature changes and preparation times for bone cavity drilling. MATERIALS AND METHODS: Tungsten carbide round drills were used to perform 10 (D_10), 20 (D_20), or 30 (D_30) coronectomies on extracted lower third molars to elicit drill wear, and then 5-mm-deep cavities were drilled in pig ribs with a testing apparatus-controlled surgical unit. Temperature changes and preparation times were measured. Differences in mean values were examined with analyses of variance and the Tukey honest significant difference post hoc test. RESULTS: The unused drills prepared the holes significantly faster (2.52 ± 1.6 seconds) than the D_20 (13.29 ± 5.76 seconds) and D_30 (31.48 ± 12.93 seconds) drills (P = .01 and P < .001, respectively). The D_10 (change, 2.33 ± 0.77°C), D_20 (change, 2.57 ± 0.57°C), and D_30 (change, 3.94 ± 0.62°C) drills produced significantly more heat than the D_0 drills (change, 1.18 ± 0.28°C; P < .001). At higher axial pressures of 25 N (to provoke ≤ 3-second preparation times in line with new drills), the D_30 drills produced a temperature change of 6.31 ± 1.23°C with 60 mL/minute and significantly more heat (change, 20.48 ± 8.84°C; P < .001) with 20 mL/minute of irrigation. CONCLUSIONS: Intraosseous heat produced by surgical tungsten carbide round drills remains under the threshold temperature of bone necrosis for up to 30 coronectomies; however, the use of increased axial pressure (∼ 25 N), especially with the combination of decreased irrigation (∼ 33%), can cause unacceptable temperatures during bone removal. Professionals should select drills and drilling parameters that generate an acceptable amount of heat during surgical tooth removal.