The effect of connective tissue graft or a collagen matrix on epithelial differentiation around teeth and dental implants: A preclinical study in minipigs

Objectives: To histologically evaluate the healing of coronally advanced flap (CAF) with either a superficial (SCTG) or deep palatal connective tissue graft (DCTG), or a collagen matrix (CM) to cover recession defects at teeth and implants.Material and Methods: One mandibular side of 6 miniature pigs received each 3 titanium implants 12 weeks after extraction. Eight weeks later, recession defects were created around implants and contralateral premolars and 4 weeks later randomly subjected to CAF+SCTG, CAF+DCTG, or CAF+CM. After 8 weeks block biopsies were histologically analyzed. Results: Pocket formation was seen at all teeth, around most implants with SCTG and DCTG, however not in the CM implant group. The connective tissue grafts showed hardly signs of degradation, whereas the CM was partly degraded and integrated in connective tissue. All teeth and implants exhibited a keratinized epithelium with no differences among the groups. The mean gain in gingival height was similar in all experimental groups (SCTG 3.89 ± 0.80 mm, DCTG 4.01 ± 1.40 mm, CM 4.21 ± 0.64 mm). Statistically significant differences were found in the height of the junctional epithelium between the control teeth and the connective tissue groups (p=0.009 and 0.044). Conclusions: In terms of keratinization no difference was observed between superficial and deep connective tissue grafts. Using a SCTG or DCTG (not CM) at teeth and implants showed pocket formation with subgingival calculus and inflammatory processes. Generally, CAF+SCTG/DCTG/CM resulted in a long JE that was even longer at implants.Clinical relevance: Deep/superficial palatal connective tissue graft yielded similar keratinization around teeth/implants.