Accuracy of a digital workflow for bimaxillary orthognathic surgery: comparison of planned and actual outcomes.

AIM: The aim of the present prospective proof-of-concept study was to evaluate the accuracy of 3D orthognathic surgical planning and CAD/CAM splints by comparing planned with actual postoperative outcomes. MATERIALS AND METHODS: Ten patients scheduled for bimaxillary orthognathic surgery to correct a skeletal Class III dentofacial deformity were recruited. All subjects had CBCT scans taken not more than 2 months preoperatively and within the 1-week postoperative period. The distance between six dental landmarks (midpoint of the maxillary and mandibular incisors, mesiobuccal cusps of the maxillary and mandibular first molars) and three intersecting symmetry planes (Frankfort horizontal plane [FHP], midsagittal plane [MSP], and coronal plane [CP]) were measured, and the differences between the virtually simulated and actual postoperative models were computed. The threshold for accuracy was set at 2 mm. RESULTS: Differences between the planned and actual outcomes were analyzed via chi-square tests and two-tailed paired student t tests. The overall mean linear difference for all six landmarks was 0.98 mm. The overall mean linear differences for both maxillary and mandibular landmarks relative to the FHP, MSP, and CP were 1.3, 0.7, and 0.9 mm, respectively. Four cases showed all linear differences of the six landmarks to be < 2.0 mm, while the other six cases had at least one linear difference of > 2.0 mm, the majority of which were in the superior-inferior direction. There were statistically significantly greater inaccuracies in the FHP compared with the MSP and CP (P < 0.05). CONCLUSION: Most of the linear differences between the simulated and actual outcomes were clinically acceptable. However, greater linear differences were seen in the superior-inferior direction, indicating a greater surgical error in achieving the desired vertical position of the maxillomandibular complex. (Int J Comput Dent 2022;25(4):397-0; doi: 10.3290/j.ijcd.b2599749).

Canine and Premolar Root Dimensions in Chinese. A Reference for Osteoodontokeratoprosthesis Surgery.

PURPOSE: Osteoodontokeratoprosthesis (OOKP) surgery is used to restore vision in end-stage corneal disorders, where an autogenous tooth supporting an optical cylinder is implanted through the cornea under a buccal mucosal graft. The ideal tooth for OOKP is a healthy single-rooted permanent tooth with sufficient buccolingual/palatal root diameter to accommodate an optical cylinder. The aim of this study was to determine the buccolingual/palatal diameters of canine and premolar roots in Chinese, for selection of teeth for OOKP surgery. DESIGN: This was an anatomical study on root dimensions of extracted intact teeth. METHODS: Extracted canine and premolar teeth (excluding maxillary first premolars) were collected and the buccolingual/palatal and mesiodistal diameters of the root at the cervical line and at 2-mm intervals below the cervical line were measured with Vernier calipers. Other measurements included total tooth length, crown buccolingual/palatal diameter, and root length. Mean and minimum buccolingual/palatal root diameters were compiled for each 2-mm interval. RESULTS: A total of 415 extracted teeth (198 male, 217 female) were collected and measured. Recorded dimensions of keratoprostheses in 55 previous OOKP surgeries were used to establish acceptable lamina dimensions to ascertain root size adequacy. Premolars in Chinese female patients were undersized in a small minority. Minimal dimensions of teeth were insufficient if at 6 mm root level, the buccolingual/palatal width was less than 5 mm, or the mesiodistal width was less than 3 mm. This was noted in female mandibular first premolars (5.6%), maxillary second premolars (4.5%), and mandibular second premolars (1.5%). CONCLUSIONS: Canines have adequate dimensions for OOKP surgery. However, premolars in Chinese females may be undersized in a small minority.

Novel 3D polycaprolactone scaffold for ridge preservation--a pilot randomised controlled clinical trial.

OBJECTIVES: This pilot randomised controlled clinical trial aimed to evaluate the feasibility and effectiveness of using a polycaprolactone (PCL) scaffold in fresh extraction sockets for ridge preservation. The hypothesis was that the insertion of a 3D bioresorbable PCL scaffold in fresh extraction sockets allowed for normal bone healing and better maintenance of ridge dimensions after 6 months as compared to extraction sockets without the scaffold. MATERIAL AND METHODS: Thirteen patients were randomised to either the test group (N = 6) where a PCL scaffold was inserted in the tooth socket after extraction or the control group (N = 7) where no space filler was used. Alveolar ridge height and width measurements were made at baseline and 6 months post-extraction, for the evaluation of bone resorption. At 6 months, a core of bone was trephined out from the healed ridge for microcomputed tomographic (micro CT) and histological analyses, immediately before Stage I dental implant surgery. Stage II dental implant surgery was performed 4-6 months later. RESULTS: There was less vertical ridge resorption in the test group compared to the control group, and the difference was statistically significant in the mesio-buccal aspect (P = 0.008). Micro CT and histological observations showed mainly mineralised bone formation in both groups, except for one specimen in the test group. CONCLUSIONS: The insertion of a 3D bioresorbable PCL scaffold in fresh extraction sockets allowed for normal bone healing, and there was better maintenance of ridge height after 6 months as compared to extraction sockets without the scaffold.