A Clinical Study Of Xenogenic Collagen Matrix And CGF Promoting Oral Mucosal Regeneration At Inter-implant Regions

Objective: The aim of this study was to evaluate the accuracy and repeatability of digital oral scan models superimposed method in measuring gingival contour changes;then apply it,combined with wound healing rate analysis and other methods,to compare the clinical effects between xenogeneic collagen matrix(XCM)and CGF on promoting the regeneration of oral mucosal at inter-implant regions.Therefore,to provide the clinical evidences for the selection of ideal biomaterials to promote oral mucosal regeneration.Methods: Part Ⅰ: 60 sites were marked on the buccal and lingual side of gingiva from fresh Sanyuan pig mandible specimen,then the gingival contour was increased with a silicone strip in these parts.At the above sites,the transgingival probing measurement method was used to measure the gingival thickness before and after amplification,and the difference was calculated as the gingival contour changes(gingival thickness after amplification-gingival thickness before amplification),and the digital oral scan models superimposed method was used to measure the gingival contour changes.The transgingival probing measurement method was used as the gold standard to evaluate the accuracy and repeatability of digital oral scan models superimposed method.Bland and Altman plots and intraclass correlation efficient were used for statistical analysis.Part Ⅱ: Patients with two or three consecutive missing teeth were included during January 2022 to December 2022 in Affiliated Stomatology Hospital of Kunming Medical University.All patients used two implants for fixed prosthesis.During stage-two surgery,the patients were treated with XCM or CGF to fill the mucosal defect area at inter-implant regions for XCM group and CGF group,respectively;or by scratching the bone surface to form blood clots to fill the mucosal defect area for the natural healing group,then the operation was completed after recording the clinical information.Pain scores,mucosal healing status at the edge of the operative area,wound healing rate,clinical appearance scores,contour changes of mucosa,depth and area of mucosal defect were recorded,which were conducted at 24 hours,3,7,14,28,and 60 days after surgery.Results: Part Ⅰ: The average gingival contour changes measured by the transgingival probing measurement method and digital oral scan models superimposed method were1.92±0.39 mm and 1.94±0.41 mm respectively.The results of Bland and Altman plots and intraclass correlation efficient concluded excellent agreement for the transgingival probing measurement method and digital oral scan models superimposed method(ICC value=0.981),and excellent agreement(repeatability)for digital oral scan models superimposed method between repeated measurement results(ICC value = 0.993).Part Ⅱ: A total of 30 patients were recruited and treated with XCM(n=8),CGF(n=11)and natural healing(n=11).For pain scores,CGF group showed lower value than the other two groups in 24 hours and 3 days after surgery,but no statistically significant differences were detected(P > 0.05).For mucosal healing status at the edge of the operative area,CGF group showed superior value than the other two groups in 3 and 7 days after surgery,but no significant differences(P > 0.05).After 7 days,the wound healing rate was 32.76%,36.12%and 21.54% for XCM group,CGF group and natural healing group respectively,XCM and CGF group showed significantly higher healing rate than natural healing group(P < 0.05),but no statistically significant differences were detected between XCM group and CGF group(P > 0.05);no statistically significant differences among the three groups at 3 and 14 days after surgery(P > 0.05);from 3 days to 14 days after surgery,the wound healing rate was significantly increased in all groups(P < 0.05).For clinical appearance scores,contour changes of mucosa,depth and area of mucosal defect,XCM and CGF group showed superior results,but no significant differences(P > 0.05).Conclusions: The digital oral scan models superimposed method has excellent accuracy and repeatability in assessing gingival contour changes,recommended as a non-invasive and accurate measurement method in clinical application.Compared with natural healing,XCM and CGF can promote inter-implant mucosal regeneration and wound healing at the early stage of healing,but CGF seems to be more advantageous in reducing postoperative inflammatory response and pain.Both XCM and CGF can be used to promote the defect repair of inter-implant mucosal.