Caroliene Meijndert

43 Performance of bone level implants with conical connections in the anterior maxilla Introduction The maxillary anterior region is an aesthetically high demanding region. For implant restorations, optimal pre-treatment conditions, careful surgical procedures and reliable implant materials are required (Roccuzzo et al., 2018). Failing or missing teeth often coincide with deficiencies of the hard and soft tissues. Depending on the severity of these deficiencies, the end result of the treatment can be compromised (Sanz-Sánchez, et al., 2018). To prevent such a compromised outcome, a bone augmentation procedure prior to implant placement is often needed to reconstruct the defect. Over time there has been a shift in the use of tissue-level implants to bone-level implants. Bone-level implants can enable the practitioner to create a natural emergence profile with individually designed abutments, which is particularly useful in the aesthetic zone (Chappuis et al., 2016; Siebert et al., 2018). A satisfying treatment outcome should be durable and stay stable for many years. Stability of the peri-implant soft and hard tissues are essential for long lasting implant success (Schwartz-Arad et al., 2005). There is evidence that an internal conical implant-abutment connection with platform- switching is efficient in maintaining stable biological aspects. The tighter conical seal between the implant and the abutment reduces bacterial leakage and thus reduces bone loss around implants compared to a non-conical connections (Schmitt et al., 2014). The reviews of Gracis et al.(2012), Goiato et al.(2015) and Palacios-Garzón et al.(2018) indicated that short-term results of this connection are favorable, but longer follow-up periods are needed to confirm the results over the long term. Five-year and ten-year results of single-tooth replacements have been published, but specific data on single bone level implants in healed sites in the anterior maxilla with an internal conical abutment connection are limited to the studies of Palmer, Gotfredsen, Pieri, Berberi, and Cooper (Palmer et al., 2000; Gotfredsen, 2004; Pieri et al., 2013; Berberi et al., 2014; Cooper et al., 2014) . All authors reported high implant survival rate between 98% and 100% and marginal bone loss <0.5mm after 5 years. All the cited studies reported on the 5-year outcome of the same bone level implant system (Astra Tech Implant System, Dentsply Implants, Mölndal, Sweden). However, Gao (Gao et al., 2017) published a 3-year study with another type of bone level implants (Straumann Bone Level Implant System, Institute Straumann AG, Basel, Switzerland). Although this study had a shorter follow-up period, the results were comparable (100% implant survival and 0.07±0.48mm bone loss). No studies with 5-year results of the latter bone level implant system (Straumann Bone Level Implant System) have been published, and none of the published studies 3