Revisiting implant controversies
Placing implants in the aesthetic zone
Risk assessment: the key to success
Placing implants in the aesthetic area is a great challenge for clinicians, due to numerous pitfalls found in daily practice. The speaker stated that a correct risk assessment is key, so we can understand which factors contribute to the success or failure of our cases.
Post-extraction remodelling is the issue
The first factor to consider when placing implants in the aesthetic area is the alveolar atrophy that occurs after tooth extraction. It is well known that the mean facial reduction of the ridge is about 2.5mm (Araujo et al., 2005). An even greater rate of resorption was observed in a primate model, reaching 70% reduction in the coronal third and over 40% in the middle zone (Min et al., 2016; Omran et al., 2016; Su et al., 2017).
How much volume reduction can be expected?
The width of the buccal bony wall represents the bone phenotype, and should be considered a risk factor due to the different response to tooth extraction. Thin phenotypes (buccal width < 1mm) tend to show a reduction of about 50% of the volume, whereas thick phenotypes (buccal wall > 1 mm) have volume reduction of less than 20%. It has also been reported that bone resorption is greater in central incisors and canines than in laterals and premolars (Cosyn et al., 2016). As well as thin phenotypes, a short gap (distance between implant platform and buccal bone wall) is an important risk factor (Ferrus et al., 2010).
How to avoid un-aesthetic margin recession
In general, the more buccal the position of the implant shoulder, the more frequent and the greater the mid-facial soft tissue recession (odds ratio of 17.4) (Cosyn et al., 2012) (fig 1–2). The ideal 3D implant position is 2mm from the vestibular wall and 1mm below the bone level.
Secondly, bone remodelling tends to correlate with gingival biotype. A thin peri-implant mucosa can increase bone loss in supracrestal implants. It has been shown that when soft tissue thickness is low, a more subcrestal positioning of the implant can help avoid implant exposure (Vervaeke et al., 2018).
In cases involving bone dehiscence, higher levels of volume reduction can be expected, reaching 90% in the most coronal third. This could lead to early implant failure, lower levels of bone formation, greater horizontal resorption and higher incidence of marginal recession. In these cases, it is preferable to use a delayed implant placement approach. Different devices have appeared on the market (fig 3), such as SocketKAP™ or SocketKAGE™, to improve ridge preservation and repair sockets with dehiscence defects (Zadeh et al., 2015).
On the other hand, grafting is associated with lower levels of bone loss. A recently published RCT concluded that bone loss is greater without grafts (2.5mm) than when grafts are used simultaneously (0.35mm) with implant placement (Sanz et al., 2017).
Another option for avoiding margin recession could be to perform a connective tissue graft at the moment of implant placement (Yoshino et al., 2014; Migliorati et al., 2015; Zuiderveld et al., 2018). The mean recession observed went from 0.5mm (without graft) to 0.1mm (with graft).
When recession has occurred, what can be done?
The speaker presented several clinical cases which were resolved with the VISTA technique (vestibular subperiosteal incision tunnel approach). This technique allows bone and soft tissue grafting to be performed at the time of implant placement. The speaker stated that his preference for connective tissue was to use tuberosity as the donor area, as he has found it to be more stable.
Other factors such as platform switching and microtextured implant surfaces can also help prevent buccal dehiscence and improve the preservation of hard and soft peri-implant tissues. Finally, figure 4 summarises the different approaches recommended by the speaker.