Third Molar Coronectomy vs Total Removal in Second Molar Periodontal Healing.

OBJECTIVES: The objective of this randomised controlled trial was to compare the periodontal healing at the distal of the adjacent second molar after coronectomy or surgical removal and the surgical morbidities of the 2 techniques. METHODS: This is a pilot study of a split-mouth randomised clinical trial comparing the periodontal healing of the adjacent second molar after coronectomy or total removal of lower third molars, which was registered with the University of Hong Kong Clinical Trial Centre as HKUCTR-2948 on 21 February 2020. Cone beam computed tomography (CBCT) scans were taken preoperatively and at 6 months postoperatively. Changes in the bone level from the cemento-enamel junction, periodontal probing depth (PPD), and clinical attachment level (CAL) at the distal of the adjacent second molar were compared. Surgical morbidities in terms of pain, infection, neurologic deficit, root exposure, and need for second surgery for removal were assessed. RESULTS: Forty patients (22 male, 18 female) with mean age of 26.7 years were evaluated at 6 months postoperatively. Both coronectomy and total removal groups demonstrated statistically significant reduction in PPD and CAL. There was an alveolar bone gain of 1.28 ± 0.88 mm in the coronectomy group and 1.13 ± 0.73mm in the control group, which was statistically significant (P < .001 for both groups). CONCLUSIONS: Early findings show the periodontal healing at the adjacent second molar of coronectomy was as good as that of total removal of lower third molar. There were no differences in terms of surgical morbidities between both groups.

Recording Natural Head Position Using Cone Beam Computerized Tomography.

The purpose of this study was to develop a technique to record the natural head position (NHP) of a subject using the scout images of cone beam computerized tomography (CBCT) scans. The first step was to align a hanging mirror with the vertical (XY) plane of the CBCT field-of-view (FOV) volume. Then, two scout CBCT images, at frontal and at sagittal planes, were taken when the subject exhibited a NHP. A normal CBCT scan on the subject was then taken separately. These scout images were used to correct the orientation of the normal CBCT scan. A phantom head was used for validation and performance analysis of the proposed method. It was found that the orientation detection error was within 0.88°. This enables easy and economic NHP recording for CBCT without additional hardware.

A Comparative Study on a Novel Fibula Malleolus Cap to Increase the Accuracy of Oncologic Jaw Reconstruction.

OBJECTIVES: Although computer-assisted surgery using fibula flap has been widely applied for oncologic jaw reconstruction in recent years, the inaccurate positioning of the fibula harvest guide brings sliding and rotational errors, which leads to compromised accuracy in simultaneous implant placement and dental rehabilitation. This study aimed to develop a novel three-dimensional (3D)-printed patient-specific fibula malleolus cap to increase oncologic reconstruction accuracy. METHODS: In this prospective comparative study with a recent historical control cohort, patients in need of oncologic jaw reconstruction with fibula free flaps were recruited. In the study group, the fibula was harvested with the guide of the malleolus cap, whereas in the control group, without the malleolus cap. Deviations of location and angulation of distal fibula osteotomies, jaw reconstruction segments, and simultaneous dental implants were compared. RESULTS: Twenty patients were recruited, with 10 in each arm. The application of the malleolus cap significantly reduced the deviations in locations and angles of distal fibula osteotomies, from 9.5 to 4.1 mm and 25.3° to 8.7°. For the simultaneous dental implants placed in the fibula flaps, there was a significant increase in the accuracy of implant platform locations (the average deviation from 3.2 to 1.3 mm), apex locations (from 3.8 to 1.5 mm), and angles (from 11.3° to 4.6°). No significant difference was detected in the accuracy of fibula reconstruction segments. CONCLUSIONS: We developed a novel fibula malleolus cap to overcome the sliding and rotational errors during fibula flap harvesting for oncologic jaw reconstruction, with increased accuracy in simultaneous dental implants. This is a step forward to achieve a satisfactory functional outcome of jaw reconstruction with dental rehabilitation.