It was proved that vertically thin soft thickness might be an important factor in development of early crestal bone loss, therefore several methods were advanced how to increase soft tissue thickness. Some authors claim, that subcrestal placement of implant and subsequent controlled bone remodelling can accommodate the problem. Another method suggests to increase soft tissue thickness by placing implant at the bone level with 2 mm height healing abutment and suture soft tissues over. The aim of the study was fourfold - to register crestal bone stability around (1) 1.5 mm subcrestally placed implants; and (2) epicrestally placed implants with 2 mm healing abutments; to (3) register bone remodelling in subcrestal group; (4) determine how vertical soft tissue has increased in epicrestal group, compared to initial situation. 24 patients with vertically thin tissues of 2 mm or less received 24 submerged bone level platform-switched implants (Conelog, Camlog, Basel, Switzerland). Implants were divided into 2 equal groups – (1) 1.5 mm subcrestally placed implants and (2) epicrestal implants with 2 mm healing abutments. At II stage surgery, all implants received 4 mm healing screws and later restored with Zr screw-retained single crowns, radiological images taken at II stage surgery and after 1 y follow-up. Bone loss was calculated as a distance between implant neck and first radiographically visible bone-to-implant contact and measured in both groups. Additionally, in subcrestal group bone remodelling was calculated as a distance between bone crest and implant neck. Mann-Whitney U-test was used for statistical analysis, significance set to 0.05. After 1 y follow-up, 1 (subcrestal) group had 0.06 (0.07 SD) mm of bone loss, while 2 group (epicrestal with 2 mm healing abutment) had 0.11 (0.14 SD) mm of bone loss, with statistically significant difference (P=0.005). Bone remodelling in group 2 (subcrestal) was 0.55 (0.3 SD) and was significantly larger compared to bone loss of subcrestal (P=0.001) and epicrestal groups (P=0.003). Vertical tissue thickness in epicrestal group before intervention was 2.30 (0.26 SD) and 3.65 (0.41 SD) after use of 2 mm healing abutment, with statistical difference (P=0.005). The novelty of the study is that crestal bone loss and bone remodelling as discussed as separate outcomes. Bone loss was calculated as a distance between implant neck and first radiographically visible bone-to-implant contact, while bone remodelling was calculated as a distance between bone crest and implant neck. Both groups had only minor crestal bone loss and could be used as a method to reduce bone loss in vertically thin tissues. However, it is interesting to note that bone remodelling in subcrestal group was larger than bone loss in both groups. In addition, the use of 2 mm healing abutment, as a method to increase soft tissue thickness and reduce bone loss was established.
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