Influence of implant placement depth and soft tissue thickness on crestal bone stability around implants with and without platform switching. A comparative clinical trial

15868 ORAL COMMUNICATION CLINICAL RESEARCH - PERI-IMPLANT BIOLOGY

Background

Recent studies by Linkevicius et al. have found that platform switching does not prevent crestal bone resorption if surrounding soft tissues are thin vertically. One of suggested ways how to avoid crestal bone loss in those cases is to place implant subcrestally, hoping that controlled bone remodelling will occur which will increase soft tissue thickness. However, this treatment mode is still not well researched, especially with properly designed control group.

Aim/Hypothesis

Aim of the study is to measure early crestal bone changes around subcrestally placed dental implants, surrounded by thin soft tissue and to compare with regular platform implants, placed in supracrestal position and surrounded by thick soft tissue.

Material and Methods

Sixty-seven patients (27 males and 40 females, 23 to 55 years of age) received 67 internal hex implants of 4.6 mm diameter. Depending on vertical soft tissue thickness, patients were divided into test group (<2 mm) and control group 3 mm or more). Control group patients received dental implants with matching platform (BioHorizons Tapered), which were placed approx. 0.5 mm supracrestally, to avoid the effect of microgap. Test group patients received dental implants with platforms switching (BioHorizons Tapered Plus), which were placed 1.5 mm subcrestally, to increase volume of soft tissue vertically. Radiographic examination was performed after implant placement, 2 months after healing, after restoration. Crestal bone loss was measured and statistical analysis performed (RStudio, Inc. Boston, USA). Shapiro -Wilk normality test was performed and independent samples t-test was used (Confidence Level 0.95).

Results

All implants integrated successfully, control group implants mean bone loss around implants after restoration was 0.198 ± 0.2 mm, (range, 0.1 to 1.2 mm), median - 0.1 mm. Test group mean bone loss around implants after restoration was 0.665 ± 0.66 mm, (range, 0 to 2.76 mm), median - 0.45 mm. Difference between test group and control group was found statistically significant (P < 0.05).

Conclusion and clinical implications

Implants with matching connection in naturally thick soft tissues experienced minor bone remodelling, implants with platform switching surrounded by thin soft tissues had moderate crestal bone resorption, inspite of subcrestal implant placement.