In vivo preclinical study comparing the peri implant tissue of a minimally invasive implant using a flapless technique and a bone level implant using an open flap technique

Purpose The purpose of the to test the hypothesis that the placement of a minimally invasive implant (MII) using a flapless technique provides a better quality of peri implant tissues compared to a reference implant (RI) placed with access flap in a canine model. Methods In this in vivo preclinical study 2 types of implants (MII without flap and RI with flap) were placed in both quadrants of the mandibula. Clinical, radiological, and histomorphometry measurements were performed at implant placement (T0), at healing abutment placement (T + 8W), and at the end of the study (T + 16W). Results A significant increase in keratinized tissue thickness was observed around MII (3.00mm ± 1.04 vs 3.68mm ± 0.63; p < 0.001) and a significant decrease for RI (3.47mm ± 0.74 vs 2.07mm ± 0.40; p < 0.05) between T0 and T + 16W. The biological width, in mesio-distal sections, was significantly greater around MII (mean ± SD PM-fBIC distances: 3680.5µm ± 629.2) than RI (2065.5µm ± 395.1, p < 0.001). Bone remodeling, in mesio-distal sections, around MII (mean ± SD IS-BC 890.4µm ± 759.2) was higher than the implant shoulder (IS) and was significantly greater than around RI (mean ± SD IS-BC -283.4µm ± 285.3, p < 0.001) for which significant bone resorption was observed around RI. Conclusion The present in vivo preclinical study found a greater thickness of the epithelial-connective tissue for MII compared to RI, which contributed to the formation of a biological space that promoted physiological tissue remodeling and supported favorable tissue stability; the hypothesis was therefore accepted. It would now be interesting to confirm these results in humans, particularly in the elderly and medically compromised patients for whom the atraumatic flapless surgical protocol seems particularly suitable.