Caroliene Meijndert

8 Chapter 1 Single tooth replacement in the aesthetic region has been part of implant dentistry for a number of decades. Since its introduction, a variety of implant systems, surgical and prosthetic techniques, and loading protocols have been used (Den Hartog et al., 2008; Esposito et al., 2010; Jung et al., 2012; Lang et al., 2012; Benic et al., 2014; Slagter et al., 2014; Van Nimwegen et al., 2019.) Most studies have only reported on the 1-year survival rate for single tooth implants and crowns. The few studies with a longer follow- up demonstrated that the 5- and 10-year survival rate of implants are 97.2% and 95.2%, respectively. The 5- and 10-year survival rate of single crowns are 96.3% and 89.4% respectively (Jung et al., 2012). Implant design, however, is subject to continuous development to achieve better or faster osseointegration of the implant, to improve the connection between the implant and abutment, and to optimise the aesthetics by facilitating the prosthetics. A specific implant design and prosthetic construction might not be used today anymore and therefore might cause restrictions when comparing the results of the former implant designs and prosthetic rehabilitation with the more recent designs and prosthetic constructions. Healed sites with extended resorption Implant treatment was, at least in former days, not always part of the initial restorative treatment plan after tooth extraction. After tooth extraction, the alveolus undergoes a series of physiologic events that can, without extra precautions, lead to progressive resorption of the alveolar ridge. Predominantly of the buccal bony wall, this could lead to severe recession of the mucosa (Araújo et al., 2019). This so-called ‘physiologic collapse’ can make the site unfit for implant placement (Buser et al., 2004; Chen & Buser, 2009; Jung et al., 2018). These unfavourable circumstances often require extensive pre- implant local ridge augmentation surgery to obtain enough bone for implant placement and a satisfying soft tissue display. This often means that placement and restoration of the implant needs to be postponed (Kuchler & Von Arx, 2014). Healed sites with limited resorption Luckilly, the extended resorption of the alveolar ridge does not always occur after a tooth extraction. Thus, leaving enough bone for implant placement after healing. When needed, e.g. in cases where the implant can be placed with sufficient initial stability, but parts of the implant shoulder remain uncovered, or where the buccal bone wall is thin (less than 2mm in thickness), a simultaneous local augmentation procedure can be performed with autologous bone and/or a bone substitute (xenograft, allograft,