University of Groningen Performance of the Straumann Bone Level Implant system for anterior single-tooth replacements in augmented and nonaugmented sites

Aim: The purpose of this prospective study was to evaluate radiographic, clinical and aesthetic outcomes and patient satisfaction of cases treated with platform-switched single implant restorations in the aesthetic region of the maxilla. Furthermore, the influence of an augmentation procedure 3 months before implant placement and the type of restoration (screw-retained vs. cement-retained) was evaluated. Material and methods: Sixty patients with a missing anterior tooth in the maxilla were treated with a Straumann Bone Level Implant. Bone augmentation was performed in 29 patients at 3 months before implant placement. Implants were loaded after 3 months of submerged healing. Follow-up was conducted at 7 and 18 months after implant placement. Peri-implant mucosa and implant crown aesthetic outcomes were determined using the Implant Crown Aesthetic Index (ICAI) and the Pink Esthetic Score-White Esthetic Score (PES-WES). Results: No implants were lost. At 18 months after implant placement, mean bone level change was 0.10 ± 0.27 mm and mean probing pocket depth was 2.57 mm. No differences were found between augmented and nonaugmented sites (P = 0.28). The ICAI indicated satisfactory mucosa and crown aesthetics in 67% and 75% of the cases, respectively, while the PES score was 14.4. ICAI mucosa (P = 0.004) and PES (P = 0.02) scores were significantly less favourable for augmented sites compared with nonaugmented sites. Patient satisfaction was high (8.9 ± 1.1 on VAS-score). Conclusions: From the present prospective, clinical study, it can be concluded that the Straumann Bone Level Implant shows an excellent survival rate, marginal bone stability and good clinical and aesthetic results. Bone augmentation before implant placement does not lead to more marginal bone loss. However, less favourable pink aesthetic outcomes were found in augmented sites compared with nonaugmented sites, while no differences were found between cement-retained and screw-retained restorations. The use of dental implants in oral rehabilitation has become a standard of care in daily practice. High survival rates are generally reported (den Hartog et al. 2008). However, to further improve the survival rates and to raise the quality of survival, new implant systems, implant surfaces and implant designs are continuously developed. In 2007, the Straumann Bone Level Implant system (Institut Straumann AG, Basel, Switzerland) was introduced to the market. This implant system offers various features that claim to improve implant survival, decrease bone loss and improve aesthetic outcomes. The Straumann Bone Level Implant is equipped with the SLActive implant surface (Ferguson et al. 2006; Rupp et al. 2006). This implant surface has shown to accelerate osseointegration compared to the SLA surface (Oates et al. 2007; Schatzle et al. 2009) and provides high survival rates even in sites with compromised bone (GaneDate: Accepted 21 March 2012 To cite this article: Santing HJ, Raghoebar GM, Vissink A, den Hartog L, Meijer HJA. Performance of the Straumann Bone Level Implant system for anterior single-tooth replacements in augmented and nonaugmented sites: A prospective cohort study with 60 consecutive patients. Clin. Oral Impl. Res. 24, 2013, 941–948 doi: 10.1111/j.1600-0501.2012.02486.x © 2012 John Wiley & Sons A/S 941 les et al. 2008; Roccuzzo & Wilson 2009). The implant-prosthetic connection of the Straumann Bone Level Implant shows a platform switch. The rationale behind this feature is displacing the implant-abutment interface, and thereby the microgap, away from the edge of the implant platform. According to a recent review, various studies have shown that platform-switched implants show less marginal bone loss compared to platform-matched implants (Atieh et al. 2010). It is hypothesized that marginal bone is crucial not only for maintaining soft tissue levels, and thereby obtaining aesthetically satisfying results, but also for limiting formation of pockets around the implant. Another important condition for establishing aesthetic results is control of the emergence profile. Increasing the distance between the top of the implant and the soft tissue margin by placing the top of the implant at bone level provides more prosthetic freedom than positioning the top of the implant beyond bone level (e.g. transmucosal implants). Bone augmentation is often needed before implant placement due to insufficient bone volume. A recent review showed that bone augmentation procedures are effective in promoting bone fill and defect resolution at implants in postextraction sites. However, these procedures are more successful with immediate (type 1) and early placement (type 2 and type 3) than with late placement (type 4, completely healed sites) (Chen & Buser 2009). Type 2 is defined as early placement with soft tissue healing (typically 4–8 weeks) without significant bone healing, whereas type 3 is defined as early placement with partial bone healing (typically 12–16 weeks). The purpose of this prospective study was to evaluate radiographic, clinical and aesthetic outcomes and patient satisfaction of cases treated with platform-switched single implant restorations in the aesthetic region of the maxilla. Furthermore, the influence of an augmentation procedure 3 months before implant placement and the type of restoration (screwretained vs. cement-retained) was evaluated. Materials and methods Study design This clinical study was designed as a singlecohort, prospective case series (n = 60) with an 18-month follow-up (Fig. 1). The study was conducted at the Department of Oral and Maxillofacial Surgery of the University Medical Center Groningen, Groningen, the Netherlands. The study protocol has been independently reviewed and approved by the Medical Ethical Committee of the University Medical Center Groningen. Written informed consent was obtained from all eligible patients before enrolment. Patients were included between October 2007 and June 2009. The study was performed in compliance with Good Clinical Practice, the Declaration of Helsinki and local legal and regulatory requirements. Participants Patients referred for single-implant treatment in the maxillary aesthetic zone were considered for inclusion if they fulfilled the following criteria: • At least 18 years of age. • One missing tooth being an incisor, canine or first premolar in the maxilla with adjacent natural teeth. • Space width with mesial–distal width of at least 6 mm. Patients were excluded from participation in this study if they met one of the following criteria: • American Society of Anesthesiologists (ASA) physical status classification system score III (Smeets et al. 1998). • Presence of clinically active periodontal disease as expressed by probing pocket depths 4 mm in combination with bleeding on probing. • Presence of peri-apical lesions or any other abnormalities in the anterior region of the maxilla as detected on a radiograph. • Smoking <3 months before bone augmentation (if applicable) or implant placement. • Tooth extraction <3 months before implant placement.