OBJECTIVES: The objective of this systematic review was to assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological and technical complications. METHODS: An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on SCs with a mean follow-up time of at least 5 years. Failure and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5-year proportions. RESULTS: Twenty-six studies from an initial yield of 3601 titles were finally selected and data were extracted. In a meta-analysis of these studies, survival of implants supporting SCs was 96.8% [95% confidence interval (CI): 95.9-97.6%] after 5 years. The survival rate of SCs supported by implants was 94.5% (95% CI: 92.5-95.9%) after 5 years of function. The survival rate of metal-ceramic crowns, 95.4% (95% CI: 93.6-96.7%), was significantly (P=0.005) higher than the survival rate, 91.2% (95% CI: 86.8-94.2%), of all-ceramic crowns. Peri-implantitis and soft tissue complications occurred adjacent to 9.7% of the SCs and 6.3% of the implants had bone loss exceeding 2 mm over the 5-year observation period. The cumulative incidence of implant fractures after 5 years was 0.14%. After 5 years, the cumulative incidence of screw or abutment loosening was 12.7% and 0.35% for screw or abutment fracture. For supra-structure-related complications, the cumulative incidence of ceramic or veneer fractures was 4.5%. CONCLUSION: It can be concluded that after an observation period of 5 years, high survival rates for implants and implant-supported SCs can be expected. However, biological and particularly technical complications are frequent. AbstractObjectives:The objective of this systematic review was to assess the 5 year survival of implant supported single crowns (SCs) and to describe the incidence of biological and technical complications. Methods:An electronic Medline search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on SCs with a mean follow-up time of at least 5 years. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5-year proportions. Results:Twenty-six studies from an initial yield of 3601 titles were finally selected and data were extracted. In a meta-analysis of these studies survival of implants Periimplantitis and soft tissue complications occurred in 9.7% of the SCs and 6.3% of the implants had bone loss exceeding 2 mm over the 5 years observation period. Technical complications included implant fractures, connection-related and supra-structure related complications. The cumulative incidence of implant fractures after 5 years was 0.14%. After 5 years the cumulative incidence of connection-related complications was 12.7% for screw or abutment loosening and 0.35% for screw or abutment fracture. For supra-structure related complications the cum...

Within the limitations of this study, it is concluded that failing implants show a continuous decrease of stability until failure. Low RFA levels after 1 and 2 months seem to indicate an increased risk for future failure. This information may be used to avoid implant failure in the future by unloading implants with decreasing degree of stability with time as diagnosed with the RFA technique.

The immediate loading concept is a realistic treatment alternative in various jawbone regions except for the posterior part of the maxilla. High occlusal loads should be considered a risk factor. On the other hand, implants in combination with bone defects frequently are penetrating cortical layers to a higher extent, thereby contributing to implant stability during the healing phase and consequently do not inevitably jeopardize the treatment result. However, further controlled clinical studies with larger sample sizes need to be performed to evaluate the influence of different parameters on treatment outcome.

The present prospective multicenter study indicates that the prefabrication, on the basis of models derived from three-dimensional oral implant planning software, of both surgical templates for flapless surgery and dental prostheses for immediate loading is a very reliable treatment option. It is evident that the same approach could be used for staged surgery and in partial edentulism.

The applied immediate loading protocol in combination with a slightly tapered implant and a modified implant surface texture was shown to be a successful treatment alternative even in regions exhibiting soft bone.

The aim of the present clinical study was to test whether or not the addition of recombinant human bone morphogenetic protein-2 (rhBMP-2) to a xenogenic bone substitute mineral (Bio-Oss) will improve guided bone regeneration therapy regarding bone volume, density and maturation. In 11 partially edentulous patients, 34 Brånemark implants were placed at two different sites in the same jaw (five maxillae, six mandibles) requiring lateral ridge augmentation. The bone defects were randomly assigned to test and control treatments: the test and the control defects were both augmented with the xenogenic bone substitute and a resorbable collagen membrane (Bio-Gide). At the test sites, the xenogenic bone substitute mineral was coated with rhBMP-2 in a lyophilization process. Following implant insertion (baseline), the peri-implant bone defect height was measured from the implant shoulder to the first implant-bone contact. After an average healing period of 6 months (SD 0.17, range 5.7-6.2), the residual defects were again measured and trephine burs were used to take 22 bone biopsies from the augmented regions. The healing period was uneventful except for one implant site that showed a wound dehiscence, which spontaneously closed after 4 weeks. Later at reentry, all implants were stable. At baseline, the mean defect height was 7.0 mm (SD 2.67, range 3-12 mm) at test and 5.8 mm (SD 1.81, range 3-8 mm) at control sites. At reentry, the mean defect height decreased to 0.2 mm (SD 0.35, range 0-1 mm) at test sites (corresponding to 96% vertical defect fill) and to 0.4 mm (SD 0.66, range 0-2 mm) at the control site (vertical defect fill of 91%). Reduction in defect height from baseline to reentry for both test and control sites was statistically significant (Wilcoxon P<0.01). Histomorphometric analysis showed an average area density of 37% (SD 11.2, range 23-51%) newly formed bone at test sites and 30% (SD 8.9, range 18-43%) at control sites. The fraction of mineralized bone identified as mature lamellar bone amounted to 76% (SD 14.4, range 47.8-94%) at test compared to 56% (SD 18.3, range 31.6-91.4%) at control sites (paired t-test P<0.05). At BMP-treated sites 57% (SD 16.2, range 29-81%) and at control sites 30% (SD 22.6, range 0-66%) of the surface of the bone substitute particles were in direct contact with newly formed bone (paired t-test P<0.05). It is concluded that the combination of the xenogenic bone substitute mineral with rhBMP-2 can enhance the maturation process of bone regeneration and can increase the graft to bone contact in humans. rhBMP-2 has the potential to predictably improve and accelerate guided bone regeneration therapy.

The periimplant soft tissue formed at the experimental one-piece mini-implants in humans was of a character similar to that described in animal studies. The oxidized and acid-etched implants revealed less epithelial downgrowth and longer connective tissue seal than machined implants.

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