IMPORTANCE OF SOFT AND HARD TISSUE MANAGEMENT ON THE AESTHETICS AND LONG TERM STABILITY AT IMPLANT SITE

Missing teeth in anterior maxilla represents one of the most challenging therapy in implant dentistry, as providing a “perfect” aesthetic results of the final restoration may include several biological variables. The aesthetic outcome of implant supported restoration is markedly influenced by the natural appearance of the dental restoration with the surrounding teeth and soft tissues; that implies that the peri implant soft tissue should be in harmony with the mucosa around the adjacent teeth and that the implant crown should be in balance with the neighbouring dentition in a natural way ( Meijer et al, 2005; Meijndert et a, 2007). The restoration of a single edentulous tooth in anterior maxilla by implant placement, was introduced as a predictable procedure in the early nineties (Jemt et al, 1991); it rapidly became a viable and effective prosthodontic alternative to conventional fixed bridgework, resin bonded restoration or partial removable dentures ( Belser et al, 1998; Belser et al, 2004). Long term studies have reported high implant survival rate for single tooth implants placement, demonstrating excellent functional success rate (Scheller et al, 1998; Romeo et al 2002; Naert et al, 2002; Kois 2004); however an implant that is osteointegrated does not alway corresponds with an aesthetic success and unlike the past, today the patients expectations degree is greater. It has been suggested that today patients use to evaluate their final restoration comparing it with the contra- lateral natural tooth as the gold standard ( Chang et al, 1999). Therefore, in order to satisfy patients’ increasing expectations, clinicians who approach aesthetic demanding clinical cases, should strive to focus not only on the prosthetic parameters but also to gingival parameters, such as soft tissue blending and ideal papilla form. Thus, in the aesthetic area, the evaluation of the success rate of single implant therapy is not only based on survival rate criteria ( Albrektsson et al, 1986), but even more by the long term quality and stability of soft and hard tissue. One of the most important key factor is a proper treatment planning prior to implant placement, requiring both objective and subjective criteria related to hard and soft tissue management (Belser et al, 1998). As a consequence of this shift in aesthetic consciousness both by patients and clinicians, the well known and traditional success criteria, ( Albrecktsson et al, 1986) have been gradually replaced by new ones: firstly, Smith and Zarb included the necessity of aesthetic variables for both patients and clinicians in order to evaluate successful results ( Smith & Zarb, 1989 ). Further, many Authors proposed different tools and indices in order to objectively assess and quantify prosthetic results and peri implant soft tissue outcomes ( Belser et al, 1998; Furhauser et al, 2005; Mejiert et al, 2005; Benic 2012). Various implant treatment procedure have been proposed in order to achieve optimal aesthetic prior or at implant placement ( Esposito et al, 2012): these surgical strategies include both soft tissue and hard tissue augmentation techniques. In some clinical situations, it might be possible to obtain good aesthetic results only by manipulating or augmenting soft tissues; particularly, many surgical approaches have been proposed to modify flap designs or to rebuild and correct the height of the papilla between a single implant and the adjacent tooth or the peri implant connective tissue fill between two adjacent implants. Recently, many Authors focused on this topic, suggesting that to better predict the aesthetic outcome of the implant supported restoration, it would be beneficial to identify the ideal vertical distances between the bone crest and the interproximal contact point to create an adequate papilla volume (Jung et al, 2018). It was concluded that the papilla height between an implant and a tooth is mainly affected by the clinical attachment level of the tooth; furthermore, other factors may influence the papilla volume and filling of the interproximal embrasure, such as tooth- and implant- related factors and at the same time surgical-related factors , such as stage vs simultaneous procedure or submerged vs transmucosal healing. The Authors concluded that, to reduce the risk of aesthetic complication, an appropriate periodontal examination should be performed during the clinical surgical planning, to correctly assess the clinical attachment level at the adjacent teeth. Nevertheless, based on the available weak evidence, it is not possible to identify a threshold distance able to predict a complete papilla fill. Another controversial issue, when evaluating the soft tissue management, is the need of an adequate band of keratinised mucosa around dental implants to improve their long term prognosis. Many Authors strongly recommend the use of soft tissue augmentation techniques to increase the width of keratinised mucosa , in order to promote peri implant health, without firm evidence supporting these statements ( Wennstrom 1994; Chung 2006; Roos- Jansaker 2006). Further studies reported, however, that a wider keratinised mucosa may be crucial to preserve soft and hard tissue stability at implant site ( Bouri et al, 2008), being a key factor in long term maintenance of dental implants ( Kim et al, 2009), resulting in a better oral hygiene and less recession over time ( Schrott et al, 2009). A recent systematic review ( Thoma et al, 2018) assessed the importance of soft tissue grafting procedure in order to improve peri implant heath, enhancing both mucosal thickness and keratinised mucosa width. On the other hand, even when approaching severe ridge deficiences of the anterior or posterior maxilla, the success largely relies on primary wound closure during and after the surgical procedure ( Wang et al, 2006). These challenging clinical scenarios requires an adequate soft tissue management in order to prevent early membrane or graft exposure that may lead to clinical failures ( Tonetti et al, 2006