Objective: To evaluate the stability and aesthetic effect of a xenogeneic collagen matrix (mucograft) on achieving an adequate keratinized mucosa width (KMW) around implants and to provide a reference basis for the clinical application of xenogeneic collagen matrix materials. Methods: The hospital ethics committee approved the study protocol, and the patients provided informed consent. Twenty patients with a KMW<2 mm at the buccal implant site who were treated in Binzhou Medical University Affiliated Yantai Stomatological Hospital from July 2020 to September 2022 were included, and a total of 36 implants were included. The mean age of the patients was (52.0±10.4) years, of which 18 were females and 2 were males. They were divided into a free gingival graft group (FGG, control group) and a xenogeneic collagen matrix group (test group) according to different graft materials. The incremental effect of the KMW on the buccal side of the implant and the mucosal shrinkage rate was measured at 1 month and 3 months after the operation. The mucosal scar index (MSI) was evaluated after the operation. Results: At 3 months postoperatively, the KMW was (3.67 ± 1.06) mm in the control group and (2.96 ± 0.98) mm in the test group, and the difference was statistically significant (t = 2.076, P<0.05). The KMW shrinkage rate was (33.34 ± 16.30) % in the test group and (22.05 ± 15.47) % in the control group at 1 month postoperatively and (51.95 ± 12.60) % in the test group and (37.44 ± 16.30) % in the control group at 3 months postoperatively, with statistically significant differences between the two groups at the same time points (P<0.05). Three months after surgery, the test group showed significantly better outcomes than the control group in terms of the five scar indicators (scar width, scar convexity, scar color, scar trace, and overall appearance), and the difference was statistically significant (P<0.05). Conclusion Xenogeneic collagen matrix can increase the peri-implant KMW and achieve a more natural and coordinated soft tissue aesthetic effect but with a higher shrinkage rate.

Objective:To compare the difference between virtual surgical planning(VSP)position and postoperative real position of maxilla and condyle,and to explore the degree of intraoperative realization of VSP after orthognathic surgery.Methods:In this study,36 patients with mandibular protrusion de-formity from January 2022 to December 2022 were included.All the patients had been done bilateral sagittal split ramus osteotomy(SSRO)combined with Le Fort Ⅰ osteotomy under guidance of VSP.The VSP data(T0)and 1-week postoperative CT(T1)were collected,the 3D model of postoperative CT was established and segmented into upper and lower jaws in CCMF Plan software.At the same time,accor-ding to the morphology of palatal folds,the virtual design was registered with the postoperative model,and the unclear maxillary dentition in the postoperative model was replaced.Then the postoperative model was matched with VSP model by registration of upper skull anatomy that was not affected by the opera-tion.The three-dimensional reference plane and coordinate system were established.Selecting anatomical landmarks and their connections of condyle and maxilla for the measurement,we compared the coordinate changes of marker points in three directions,and the angle changes between the line connecting the marker points and the reference plane to analyze the positional deviation and the angle deviation of the postoperative condyle and maxilla compared to VSP.Results:The postoperative real position of the maxilla deviates from the VSP by nearly 1 mm in the horizontal and vertical directions,and the anteropos-terior deviation was about 1.5 mm.In addition,most patients had a certain degree of counterclockwise rotation of the maxilla after surgery.Most of the bilateral condyle moved forward,outward and downward(the average distance deviation was 0.15 mm,1.54 mm,2.19 mm,respectively),and rotated forward,outward and upward(the average degree deviation was 4.32°,1.02°,0.86°,respectively)compared with the VSP.Conclusion:VSP can be mostly achieved by assistance of 3D printed occlusal plates,but there are certain deviations in the postoperative real position of maxilla and condyle compared with VSP,which may be related to the rotation axis of the mandible in the VSP.It is necessary to use patient personalized condylar rotation axis for VSP,and apply condylar positioning device to further improve surgical accuracy.