Xenogeneic collagen matrix loaded with recombinant human platelet-derived growth factor vs autogenous connective tissue graft for the treatment of peri-implant soft tissue dehiscences: A randomized, controlled, clinical, trial

Abstract

Background and Object: Patient’s demands have progressively increased over the last decade that esthetic concerns related to anterior dental implants are not uncommon. Several techniques have been attempted for the treatment of peri-implant soft tissue dehiscences/deficiencies (PSTDs), mostly employing the use of autogenous connective tissue graft (CTG). The objective of this study was to assess the effectiveness of combining recombinant human platelet-derived growth factor (rhPDGF)-BB with a xenogeneic “volume-stable” collagen matrix collagen matrix (VCMX) compared to the gold standard CTG for the treatment of peri-implant soft tissue dehiscences PSTDs at anterior implant sites. Methods: Twenty-eight subjects with isolated PSTDs were enrolled and randomized to receive a prosthetic-surgical approach involving either VCMX + rhPDGF-BB or CTG. The treatment protocol involved a presurgical prosthetic phase, with the removal of the pre-existing crown and the fabrication of a temporary crown. After 1 month, the surgical procedure for the correction of the PSTD was performed via soft tissue augmentation (VCMX + rhPDGF-BB or CTG, based on the randomization). After a provisional phase with the creation of an adequate emergence profile, a new definitive crown was made. The primary outcomes of interest in this study were the mean PSTDs coverage between the two treatment groups at 1 year. Additional outcomes of interest included: i) volumetric changes; ii) assessment of modifications in the peri-implant soft tissue phenotype; iii) ultrasonographic tissue perfusion-related outcomes; iv) ultrasonographic tissue elasticity-related outcomes: v) assessment of patient-reported outcomes during the first post-operative month; vi) evaluation of patient-reported outcomes at the last study visit and their changes compared to baseline. Optical scanning and the superimposition of the digital models were employed to evaluate volumetric changes at the treated areas. High-frequency ultrasonography was executed at different time points over 12 months to assessed changes in the peri-implant soft tissue phenotype, as well as tissue perfusion, and strain elastography. Multilevel linear mixed models were used to assess the study outcomes, accounting for repeated measures with random effects for time and subject, and fixed effects for potential confounders. Results: The preliminary findings from the randomized clinical trial depicted a mean follow-up period of 7.6 months. No statistically significant differences were observed for the primary outcome (mean PSTD of 94% for CTG, and 87% for VCMX + rhPDGF-BB, p>0.005). CTG-treated sites showed significantly higher KMW changes (2.9 mm vs 0.6 mm, p.01), MT gain (1.6 mm vs 0.9 mm, p=0.02) and Vol gain (114 mm3 vs 81 mm3, p=0.04) compared to VCMX + rhPDGF. On the other hand, the patients allocated to CTG reported significantly greater post-operative morbidity (20.9 VAS vs 5.5 VAS, p.01) and time for recovery (8.3 days vs 4.1 days, p.01) than the subjects that received VCMX + rhPDGF-BB. No significant differences were found between the groups for patient-reported treatment satisfactions and esthetic assessment (p.05). Conclusion: Treatment of PSTD with CTG or VCMX + rhPDGF-BB resulted in similar mean PSTD coverage. CTG resulted in a significantly greater KMW, MT, and Vol gains, while it also caused significantly higher post-operative pain and time to recover than VCMX + rhPDGF