Connective tissue graft versus xenogeneic collagen matrix for soft tissue augmentation at implant sites: a randomized-controlled clinical trial

The purpose of this randomized clinical trial (RCT) is to compare xenogeneic collagen matrix (XCM) versus subepithelial connective tissue graft (SCTG) to increase soft tissue thickness at implant site. The study was a randomized, parallel-group controlled investigation. Thirty patients underwent buccal soft tissue thickness augmentation at the stage of implant placement by two different methods: SCTG (control group) and XCM (test group). Primary outcome was the amount of buccal soft tissue thickness gain, 3 months after the intervention. Secondary outcomes were the operation time, the amount of keratinized mucosa (KM), pain syndrome (PS), and patients’ quality of life (QL). Histologic evaluation was also performed. The amount of soft tissue thickness gain was 1.55±0.11 mm in SCTG group, and 1.18±0.11mm in XCM group. The difference between the SCTG and XCM was −0.366 (−0.66 to −0.07; p=0.016). Operation time with XCM was 8.4 (3.737 to 13.06) min shorter than that with the SCTG (p=0.001). KT, PS, and QL for both groups were not statistically significantly different at any time point (p>0.05). At histological examination, the general picture in both groups was similar. No significant differences between the studied groups in most indices, except for the average and maximum formation thickness, cellularity of the basal, mitotic activity and also maximum length of rete ridges. Within limitations, this study demonstrates that the use of SCTG provides a statistically significant superior soft tissue thickness gain than XCM for soft tissue augmentation procedures around implants. XCM can be used as the method of choice for increasing the thickness of soft tissues.