To evaluate the clinical effect of a digital whole-process surgical guide for immediate implantation in the molar area.

Twenty-six patients with molar extraction plans were accepted for preoperative CBCT and model construction. Computer software was used to design the ideal three-dimensional position of the implant. The control group of 13 patients underwent immediate implantation with a free hand operation, whereas the experimental group of 13 patients underwent preparation and implant insertion under the guidance of a surgical guide. Bone grafting was performed, and a good initial stability was achieved. After 5 to 6 months, osseointegration was achieved, and the final restoration was delivered. After surgery, the accuracy of the three-dimensional position of the implants was measured, and at the 6 month return visit, the modified Plaque Index (mPLI), modified Sulcular Bleeding Index (mSBI) and probing depth (PD) were measured.

In the control group and experimental group, the vertical errors at the top of the implants were 1.246 ± 0.072 mm and 0.628 ± 0.046 mm (t = 26.078, P < 0.001), respectively, and the horizontal errors were 1.563 ± 0.086 mm and 0.546 ± 0.056 mm (t = 35.813, P < 0.001), respectively; and the vertical errors at the root of the implants were 1.352 ± 0.042 mm and 0.532 ± 0.030 mm (t = 57.021, P < 0.001), respectively, and the horizontal errors were 1.645 ± 0.076 mm and 0.625 ± 0.072 mm (t = 35.086, P < 0.001), respectively. For the experimental group, the mPLI value was 0.923 ± 0.760, the mSBI value was 0.846 ± 0.689, and the PD value was 3.460 ± 0.713 mm, which were significantly lower than those of the control group. For the control group, the mPLI value was 1.769 ± 0.927 (t = 2.546, P = 0.018), the mSBI value was 1.692 ± 0.947 (t = 22.605, P = 0.016) and the PD value was (4.579 ± 0.475) mm (t = 4.709, P < 0.001).

A digital surgical guide plate can increase the precision of immediate implantation and the peri-implant health in the molar area.

To compare the accuracy of the original-mirror alignment algorithm and a landmark-independent method in constructing the midsagittal plane (MSP) of the cone beam computed tomography in patients with facial deformities, so as to provide a theoretical basis for symmetric analysis.

The study was approved by the hospital ethics committee. Cone beam computed tomography data of 30 patients with facial deformities were obtained, and the output was saved in DICOM format. The scan data were imported into Mimics 21.0; after segmentation, three-dimensional (3D) skull models were reconstructed. Furthermore, the 3D scan data of skulls were transformed into mirror skull models using Geomagic Studio 2014 reverse engineering software. The MSP of each skull was generated using both the original-mirror alignment algorithm and the landmark-independent method. Original-mirror alignment algorithm: the original skull model and its mirror model were combined, and the new data to calculate the MSP (S1) of the original data in Geomagic Studio 2014 were obtained. Landmark-independent method: the following anatomical landmarks were determined using Mimics 21.0: nasion (N), crista galli (CG), sella (S), basion (Ba), vomer (V), posterior nasal spine (PNS), incisive foramen (IF), and anterior nasal spine (ANS). The MSP (S2) of best fit was then found by minimizing the mean square distance of these eight anatomical landmarks to a plane in Geomagic Studio 2014. The results of the S1 and S2 models constructed using the originalmirror alignment algorithm and the landmark-independent method, respectively, were scored subjectively by five senior maxillofacial surgeons, and a paired t-test was performed for the two groups. The internal consistency analysis was performed based on secondary experiments to verify the repeatability of the expert evaluation method.

The average scores of the S1 and S2 models were 65.73 and 75.90, respectively. The average score of the model constructed using the landmark-independent method was significantly higher than that of the model constructed using the original-mirror alignment algorithm (P＜0.01). Furthermore, the results of the internal consistency analysis showed that the expert evaluation method had good reliability and validity.

In patients with facial deformities, the MSP constructed using the landmark-independent method is superior to that constructed using the original-mirror alignment algorithm. This study provides a theoretical basis for maxillofacial symmetry analysis in clinical settings and is clinically feasible.