The efficacy of subcrestal implant placement versus flattening of the alveolar ridge in preserving stable peri-implant bone: a comparative clinical study

30D43 ePOSTER CLINICAL RESEARCH – PERI-IMPLANT BIOLOGY

Background: The stable peri-implant crestal bone is highly dependent on the vertical soft tissue thickness. The subcrestal implant placement and the flattening of the alveolar ridge with simultaneous epicrestal implant placement are two of the few methods to increase vertical soft tissue thickness and avoid or minimize crestal bone loss.

Aim/Hypothesis: The aim of this study was to register and compare the crestal bone loss that occurs in subcrestally placed bone-level implants with the crestal bone loss in epicrestally placed bone-level implants in flattened alveolar ridges, both in patients with vertically thin soft tissues.

Materials and Methods: 20 two-piece, bone-level implants with platform – switching conical implant-abutment connection were placed in 8 patients with vertically thin tissues of 2 mm or less. They were divided into control group (subcrestal group – 10 implants) and test group (epicrestal group in flattened ridges – 10 implants). All implants were placed in a one-stage manner in the posterior mandible. Subcrestal implants were places 1.5-2 mm below bone level, while epicrestal implants were placed after reducing the ridge height by 2 mm. The primary stability was determined through implant stability quotient using RFA instrument. All implants were restored with screw retained single crowns or fixed partial dentures. The crestal bone level changes were measured on intraoral radiographs at mesial and distal reference points at the time of implant placement and one year post final restoration delivery. The statistical significance was set to P < .05.

Results: One year after final restoration delivery, the mean bone loss values, calculated from the implant platform to the first implant-bone contact at subcrestal implants were 0.65 ± 0.35 mm while at epicrestal group 0.58 ± 0.45 mm, showing no statistically significant difference.

Conclusions and Clinical Implications: Within the limitations of this study it can be concluded that subcrestally placed platform-switched implants did not preserve crestal bone better in comparison with epicrestally placed platform switched implants in flattened ridges. Both methods are equally effective in maintaining stable bone levels around implants.

Keywords: vertical soft tissue thickness, subcrestal implant placement, alveolar ridge flattening, crestal bone stability, bone loss