Full versus split thickness flap to increase soft tissue thickness and keratinization of NO-keratinized mucosa. A 3-year split mouth randomized clinical trial

35SVT ORAL COMMUNICATION CLINICAL RESEARCH – PERI-IMPLANT BIOLOGY

Background: Tuberosity is a common donor site for the soft tissue augmentation. It was shown, that this CTG tends to determine hyperplastic responses due to the differences of collagen cross-linking and fibroblasts maturation. This may induce over-keratinization and influence changes of soft tissue color and texture in the aesthetic area. In contrast, it may be used as advantages to increase keratinized tissues around implants in the lower jaw.

Aim/Hypothesis: Clinically evaluate and compare CTG from tuberosity ability to increase soft tissue thickness and the keratinization potential after recipient area is either prepared using split or full thickness flap in edentulous mandible.

Materials and Methods: 40 implants were placed in 10 edentulous patients with atrophied mandible (Class IV) presenting less than 1 mm of keratinized tissue using flapless approach and immediately restored with acrylic temporary bridge on multiunit abutments. After randomization implants were divided in to split thickness (N20) and full thickness (N20) groups. CTG from tuber was placed into the socket buccally using split thickness or full thickness flap. Width of keratinized tissue (KT), horizontal soft tissue thickness (STT), marginal hard and soft tissue level as well as the implant success parameters were collected and one-way repeated measures ANOVA were used to evaluate the mean differences in full and split thickness groups at four time-points (at a baseline (surgery), after 2 months, 1 year and 3 years after). A two-tailed p-value less than 0.05 considered to be significant. Statistical analysis was performed using R statistical software.

Results: After 3 years follow-up period the increase of KT was significantly more evident in a split thickness group from 0.6(0.6) to 5.1(0.72)mm, while full thickness group showed very little improvement from 0.5(0.51) to 1(0.57)mm with statistically significant difference between the groups (P < 0.001). STT was significantly increased in both groups over time: from 2.4(0.88) to 5.4(0.68)mm in full thickness group and from 2.5(0.51) to 5.8(0.41)mm in split thickness group without any significant difference between the groups. Vertical recession was 2.6(0.7)mm in a full thickness group and 1.4(0.6)mm in a split thickness group. Crestal bone loss of more than 1 mm was observed in 8 of 40 implants. At final examination all implants were still in function.

Conclusions and Clinical Implications: The increase of soft tissue thickness by using CTG from tuberosity was found in both groups, wile keratinisation of NO-keratinized mucosa was more evident in split thickness group. Clinical Implications: Full thickness flap should be used in aesthetic area to increase soft tissue thickness and avoid differentiations of the graft. Split thickness flap should be used in clinical situations when there is a need of KT.