Replacing missing teeth with dental implants is a routine treatment in many dental practices. In order to achieve adequate functional and aesthetic results, an optimal three-dimensional implant position has to be assured. Various materials are available to build up missing bone. While autogenous bone is usually regarded to be the gold standard, harvesting may be associated with morbidity and considerable post-operative resorption of the augmented volume. Therefore, bone substitutes are often used either alone or in combination with autogenous bone. Among bone substitutes, deproteinized bovine bone mineral has proven effectiveness in various indications as shown in clinical studies. The long-term stability of the augmented volume found with this material is probably due to its slow resorption rate.

In guided bone regeneration procedures, membranes are often used to cover the graft and prevent ingrowth of soft tissue. Native collagen membranes have been shown to allow bone formation with a low complication rate.

Questions have been raised whether implant survival may be compromised in augmented sites since graft materials might impede and delay bone remodelling. While some studies reported reduced survival for implants in grafted areas, other authors did not report any significant differences of implant survival or implant success between augmented and pristine bone. For sinus floor augmentation, Aghaloo et al. even found favourable implant survival rates in augmented bone.

Therefore, the objective of this study was to retrospectively analyse all consecutively placed implants in patients fulfilling the inclusion criteria and complete patient data files within 20 years in three private practices in terms of implant survival in augmented and non-augmented sites. Secondary objectives were to evaluate whether certain augmentation procedures or materials may be advantageous in terms of implant survival.