Page 117 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

IMPROVEMENT OF QUALITY OF LIFE WITH IMPLANT-SUPPORTED MANDIBULAR OVERDENTURES AND THE EFFECT OF IMPLANT TYPE AND SURGICAL PROCEDURE ON BONE AND SOFT TISSUE STABILITY
is expressed in a Sa value. This three-dimensional value expresses an absolute difference in the height of each point compared to the arithmetical mean of the surface.22 In the early years of implant dentistry two types of implant surfaces were used, the machined/turned surface (Sa = 0.5–1 μm) and the microporous titanium plasma-sprayed surface (Sa > 2 μm). The first one is smooth and the latter could be described as a rough implant surface.
Surface modification was done to enlarge the surface, resulting in a greater bone- to-implant contact area. Implant surface modifications were done by sandblasting, acid-etching, anodic oxidation or hydroxyapatite coating. These techniques resulted in a moderately rough implant surface (Sa = 1–2 μm), which is nowadays the most used surface roughness. Beside the higher bone-to-implant contact,23 a lower clinical failure rate24 and a higher removal torque was observed compared to the smooth implant surfaces.25 Hence, the surface modification made it possible to load the implant earlier or even immediately after the surgery. The resulting surface enlargement allowed shorter implants to be used, without jeopardizing the prognosis and with a reduced necessity for bone grafting procedures.2 Beside the aforementioned benefits, related to faster integration, rough implant systems have been linked to increased bacterial adhesion.26 The applied model in the latter study does not always mimic the clinical reality. However, A Cochrane systematic review suggested limited evidence that smooth surfaces had a 20% reduced risk of being affected by peri-implantitis over a three-year period.27,28 This finding led to the commercial production of hybrid dental implants, combining the best of both systems. Hybrid dental implants have a minimally rough coronal part to decrease biofilm formation in the soft tissue crevice and a moderately rough implant body to enhance bone healing and speed up the osseointegration. These hybrid surfaces combine the effect of both surface roughnesses in the same implant. A short-term study indicated that the moderately rough and smooth coronal part showed the same crestal bone remodeling in the initial healing phase.29 However, long-term studies to describe clinical parameters and peri-implant health are not yet available.
Some patient-related factors, such as certain metabolic syndrome components, medical conditions and/or the use of medication are known to have an effect on implant treatment outcome. Systematic reviews reveal that hyperglycemia has an increased risk for peri-implantitis,30,31 although the risk for more implant failures
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