Abstract
Objectives: Repeated abutment disconnection/reconnection may compromise the mucosal barrier and result in crestal bone level changes. The clinical significance of this phenomenon is not yet clear, as most studies on this topic are short-term. Therefore, the aim of the present study was to evaluate the influence of abutment disconnections and reconnections on peri-implant marginal bone loss over a medium-term follow-up period. Material and methods: Twenty-one patients (6 men and 15 women) with a mean age 66.23 ± 9.35 year at the time of implant placement were included. All patients who received two adjacent nonsubmerged implants were randomly assigned into one of the two groups: definitive multiunit abutments (DEFs) connected to the implant that were not removed (test group) or healing abutments (HEAs) placed at surgery, which were disconnected and reconnected 3–5 times during the prosthetic phase (control group). Peri-implant marginal bone levels (MBL) were measured through periapical X-rays images acquired immediately after the surgery (baseline), at 4–7 months immediately after prosthetic delivery, and at 1-year and 3-year follow-up visits. Results: No implant was lost or presented bone loss of more than 1.9 mm during the 3-year follow-up; thus, the survival and success rate was 100%. Peri-implant mucositis was noticed in 38.1% DEFs and 41.9% of HEAs at the 3-year follow-up assessment. At the end of 3 years, the MBL was −0.35 ± 0.69 mm for participants in the DEFs group and −0.57 ± 0.80 mm for the HEAs group, with significant statistical difference between groups. Conclusions: Immediate connection of the multiunit abutments reduced bone loss in comparison with 3–5 disconnections noted in the healing abutments 3 years after prosthetic delivery. However, the difference between the groups was minimal; thus, the clinical relevance of those results is doubtful.
Highlights
The peri-implant mucosa around titanium implants has been studied in a series of preclinical and clinical studies [1,2,3,4,5,6,7,8,9,10,11,12]
It was suggested [2] that this attachment serves the purpose of protecting the zone of osseointegration from factors released from the plaque and the oral cavity
Since the junctional epithelium consistently terminated at a certain level during healing, it was suggested that there was an interaction between the junctional epithelium and the titanium dioxide of the abutment surface and that this zone of “interaction” was not recognized as a wound
Summary
The peri-implant mucosa around titanium implants has been studied in a series of preclinical and clinical studies [1,2,3,4,5,6,7,8,9,10,11,12]. It was observed that the implant–mucosal barrier comprises two components: junctional epithelium (JE) of 2 mm long and connective tissue compartment of 1–1.5 mm height [2]. It was suggested [2] that this attachment serves the purpose of protecting the zone of osseointegration from factors released from the plaque and the oral cavity. The main advantage of transmucosal portion with a smooth machined surface is its capacity to reduce the risk of bacterial colonization and inflammation, reducing the incidence of peri-implantitis [4]. Connective tissue fibers were found to be denser and perpendicularly oriented to the surface around microgrooved abutments, whereas in the machined titanium abutments, the fibers were oriented parallel to the abutment surface [4]
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