Revisiting implant controversies
What are the indications and limitations of GBR
3D implant position in not negotiable
First, the speaker focused on hard and soft tissue deficiencies which are not associated with peri-implantitis. He stated that most of these problems arise from incorrect implant placement. For this reason, 3D implant positioning is crucial – he stated that if an implant cannot be placed in the exact 3D position, today is not the day to place it.
There is evidence in the literature supporting the fact that excessive buccal angulation is a strong predictor for mid-facial recession (Cosyn et al., 2012a). Placing implants in an alveolar process with missing buccal bone wall usually leads to apical displacement of the mucosal margin (Cosyn et al., 2012b) (fig 1).
GBR cannot correct peri-implant problems outside the bony envelope
The key factor for successful GBR is that it is applied within the contour of the bone. Outside the bony envelope, GBR is unpredictable; this is the limit for when GBR is indicated. When the implant platform is too close to the buccal bone wall, our therapeutic tools are not predictable enough. Finally, when implants are not placed deep enough in the bony envelope, regeneration is not predictable above the level of the implant-abutment connection (fig 2).
GBR can be used to augment deficiencies caused by peri-implantitis after tissues have healed. However, it is not indicated for correcting the effects of implants which have been placed too buccally.
In some cases, a connective tissue graft can improve both tissue sealing and aesthetic appearance by covering the greyish area. But the more buccally tilted the implant is, the less predictable the graft will be. Angulations over 25º are pointing outwards and should be explanted rather than treated.
Lack of keratinised tissue and recessions are limitations for GBR
There are thousands of implants which have been placed without buccal cortical bone. In these borderline situations, GBR results are unpredictable because of the lack of bone and keratinised tissue. If the implants don’t show signs of disease and can be well maintained by the patient, we should leave them as they are.
Prevention means placing the implant in the correct position
A systematic review has investigated the effect of various surgical and restorative interventions at immediate implant placement on the buccal mucosal level. Lingual-palatal implant positioning was found to be the intervention that most consistently prevented mid-buccal mucosal recession. Other interventions which had conflicting results were: platform-switching abutments, flapless approaches, gap grafting, connective tissue grafts and immediate provisionalisation (Lin et al., 2014).