Objective
To assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological, technical, and aesthetic complications. The focused question was: What is the survival rate of implants supporting single crowns and implant-supported crowns with a mean follow-up of 5 years and to which extent do biological, technical, and aesthetic complications occur?

Methods
A Medline search (2006–2011) was performed for clinical studies focusing on implant-supported SCs with a mean follow-up of at least 5 years. The search was complemented by an additional hand search and the inclusion of 24 studies from a previous systematic review (Jung et al. 2008a). Survival and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5- and 10-year proportions.

Results
Forty-six studies derived from an initial search count of 1083 titles and the complementary publications from the previous systematic review (Jung et al. 2008a) were selected and the data were extracted. Based on the meta-analysis, survival of implants supporting SCs at 5 years amounted to 97.2% (95% CI: 96.3–97.9%), and at 10 years amounted to 95.2% (95% CI: 91.8–97.2%). The survival of implant-supported SCs was 96.3% (95% CI: 94.2–97.6%) after 5 years and 89.4% (95% CI: 82.8–93.6%) after 10 years. For biological complications, a 5-year cumulative soft tissue complication rate of 7.1% (95% CI: 4.4–11.3%) and a cumulative complication rate for implants with bone loss >2 mm of 5.2% (95% CI: 3.1–8.6%) were calculated. Technical complications reached a cumulative incidence of 8.8% (95% CI: 5.1–15.0%) for screw-loosening, 4.1% (95% CI: 2.2–7.5%) for loss of retention, and 3.5% (95% CI: 2.4–5.2%) for fracture of the veneering material after 5 years. The cumulative 5-year aesthetic complication rate amounted to 7.1% (95% CI: 3.6–13.6%).

Conclusions
The outcomes of the meta-analysis demonstrated high implant survival rates for both the single tooth implants and the respective single crowns after 5 and 10 years. However, technical, biological, and aesthetic complications were frequent.

Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years

Objectives
The objective of this systematic review was to assess the 5- and 10-year survival of implant-supported fixed dental prostheses (FDPs) 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 and case series on FDPs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Failure and complication rates were analyzed using standard and random-effects Poisson regression models to obtain summary estimates of 5-year and 10-year survival and complication rates.

Results
The updated search provided 979 titles and 257 abstracts. Full-text analysis was performed for 90 articles resulting in a total 32 studies that met the inclusion criteria. Meta-analysis of these studies indicated an estimated survival of implants supporting FDPs of 95.6% after 5 years and 93.1% after 10 years. When machined surface implants were excluded from the analysis and only rough surface implants included, the survival rate increased to 97.2% after 5 years. The survival rate of implant-supported FDPs was 95.4% after 5 years and 80.1% after 10 years of function. When the analysis was done exclusively for metal–ceramic FDPs, hence the old gold–acrylic FDPs were excluded, the survival rate increased significantly. The survival rate of metal–ceramic implant-supported FDPs was 96.4% after 5 years and 93.9% after 10 years. Only 66.4% of the patients were free of any complications after 5 years. The most frequent complications over the 5-year observation period were fractures of the veneering material (13.5%), peri-implantitis and soft tissue complications (8.5%), loss of access hole restoration (5.4%), abutment or screw loosening (5.3%), and loss of retention of cemented FDPs (4.7%).

Conclusion
It may be concluded that implant-supported fixed dental prostheses (FDPs) are a safe and predictable treatment method with high survival rates. However, biological and technical complications were frequent (33.6%). To minimize the incidence of complications, dental professionals should make great effort in choosing reliable components and materials for implant-supported FDPs and the patients should be placed in well-structured maintenance system after treatment.

A systematic review of the survival and complication rates of implant-supported fixed dental prostheses (FDPs) after a mean observation period of at least 5 years.

The Guided Bone Regeneration (GBR) treatment concept advocates that regeneration of osseous defects is predictably attainable via the application of occlusive membranes, which mechanically exclude non-osteogenic cell populations from the surrounding soft tissues, thereby allowing osteogenic cell populations originating from the parent bone to inhabit the osseous wound. The present review discusses the evolution of the GBR biological rationale and therapeutic concept over the last two decades. Further, an overview of the GBR research history is provided with specific focus on the evidence available on its effectiveness and predictability in promoting the regeneration of critical size cranio-maxillo-facial defects, the neo-osteogenesis potential and the reconstruction of atrophic alveolar ridges before, or in conjunction with, the placement of dental implants. The authors conclude that future research should focus on (a) the investigation of the molecular mechanisms underlying the wound healing process following GBR application; (b) the identification of site and patient related factors which impact on the effectiveness and predictability of GBR therapy and (c) the evaluation of the pathophysiology of the GBR healing process in the presence of systemic conditions potentially affecting the skeletal system.To cite this article:Retzepi M, Donos N. Guided Bone Regeneration: biological principle and therapeutic applications.Clin. Oral Impl. Res. 21, 2010; 567-576.doi: 10.1111/j.1600-0501.2010.01922.x.

Guided Bone Regeneration: biological principle and therapeutic applications

PURPOSE

The objectives of this systematic review are (1) to quantitatively estimate the esthetic outcomes of implants placed in postextraction sites, and (2) to evaluate the influence of simultaneous bone augmentation procedures on these outcomes.

MATERIALS AND METHODS

Electronic and manual searches of the dental literature were performed to collect information on esthetic outcomes based on objective criteria with implants placed after extraction of maxillary anterior and premolar teeth. All levels of evidence were accepted (case series studies required a minimum of 5 cases).

RESULTS

From 1,686 titles, 114 full-text articles were evaluated and 50 records included for data extraction. The included studies reported on single-tooth implants adjacent to natural teeth, with no studies on multiple missing teeth identified (6 randomized controlled trials, 6 cohort studies, 5 cross-sectional studies, and 33 case series studies). Considerable heterogeneity in study design was found. A meta-analysis of controlled studies was not possible. The available evidence suggests that esthetic outcomes, determined by esthetic indices (predominantly the pink esthetic score) and positional changes of the peri-implant mucosa, may be achieved for single-tooth implants placed after tooth extraction. Immediate (type 1) implant placement, however, is associated with a greater variability in outcomes and a higher frequency of recession of > 1 mm of the midfacial mucosa (eight studies; range 9% to 41% and median 26% of sites, 1 to 3 years after placement) compared to early (type 2 and type 3) implant placement (2 studies; no sites with recession > 1 mm). In two retrospective studies of immediate (type 1) implant placement with bone graft, the facial bone wall was not detectable on cone beam CT in 36% and 57% of sites. These sites had more recession of the midfacial mucosa compared to sites with detectable facial bone. Two studies of early implant placement (types 2 and 3) combined with simultaneous bone augmentation with GBR (contour augmentation) demonstrated a high frequency (above 90%) of facial bone wall visible on CBCT. Recent studies of immediate (type 1) placement imposed specific selection criteria, including thick tissue biotype and an intact facial socket wall, to reduce esthetic risk. There were no specific selection criteria for early (type 2 and type 3) implant placement.

CONCLUSIONS

Acceptable esthetic outcomes may be achieved with implants placed after extraction of teeth in the maxillary anterior and premolar areas of the dentition. Recession of the midfacial mucosa is a risk with immediate (type 1) placement. Further research is needed to investigate the most suitable biomaterials to reconstruct the facial bone and the relationship between long-term mucosal stability and presence/absence of the facial bone, the thickness of the facial bone, and the position of the facial bone crest.

Esthetic outcomes following immediate and early implant placement in the anterior maxilla--a systematic review.

OBJECTIVES: To assess the 5-year survival rates and incidences of complications of cemented and screw-retained implant reconstructions. METHODS: An electronic Medline search complemented by manual searching was conducted to identify randomized controlled clinical trials (RCTs), and prospective and retrospective studies giving information on cemented and screw-retained single-unit and multiple-unit implant reconstructions with a mean follow-up time of at least 1 year. Assessment of the identified studies and data abstraction were performed independently by three reviewers. Failure rates were analyzed using Poisson regression models to obtain summary estimates and 95% confidence intervals of failure rates and 5-year survival proportions. RESULTS: Fifty-nine clinical studies were selected from an initial yield of 4511 titles and the data were extracted. For cemented single crowns the estimated 5-year reconstruction survival was 96.5% (95% confidence interval (CI): 94.8-97.7%), for screw-retained single crowns it was 89.3% (95% CI: 64.9-97.1%) (P = 0.091 for difference). The 5-year survival for cemented partial fixed dental prostheses (FDPs) was 96.9% (95% CI: 90.8-99%), similar to the one for screw-retained partial FDPs with 98% (95% CI: 96.2-99%) (P = 0.47). For cemented full-arch FDPs the 5-year survival was 100% (95% CI: 88.9-100%), which was somewhat higher than that for screw-retained FDPs with 95.8% (95% CI: 91.9-97.9%) (P = 0.54). The estimated 5-year cumulative incidence of technical complications at cemented single crowns was 11.9% and 24.4% at screw-retained crowns. At the partial and full-arch FDPs, in contrast, a trend to less complication at the screw-retained was found than at the cemented ones (partial FDPs cemented 24.5%, screw-retained 22.1%; full-arch FDPs cemented 62.9%, screw-retained 54.1%). Biological complications like marginal bone loss >2 mm occurred more frequently at cemented crowns (5-year incidence: 2.8%) than at screw-retained ones (5-year incidence: 0%). CONCLUSION: Both types of reconstructions influenced the clinical outcomes in different ways, none of the fixation methods was clearly advantageous over the other. Cemented reconstructions exhibited more serious biological complications (implant loss, bone loss >2 mm), screw-retained reconstructions exhibited more technical problems. Screw-retained reconstructions are more easily retrievable than cemented reconstructions and, therefore, technical and eventually biological complications can be treated more easily. For this reason and for their apparently higher biological compatibility, these reconstructions seem to be preferable.

Cemented and screw‐retained implant reconstructions: a systematic review of the survival and complication rates

Aim: To compare the immediate restoration of single implants in the esthetic zones performed on implants placed immediately after tooth extraction or 8 weeks later (immediate replacement vs. immediate restoration). Methods: Sixteen patients (10 women and 6 men) with a mean age of 35 years (ranging from 21 to 49 years old) were treated from 2004 to 2005 for single-tooth replacement in the upper arch. The patients were randomly divided into two groups: in the test group patients received implants placed and restored (non-occlusal loading) at the time of tooth extraction; in the control group implants were placed 8 weeks after tooth extraction and immediately restored. All the patients received tapered effect (TE) implants from the Straumann Dental Implant System. The following parameters were evaluated at the moment of provisional restoration (within 48h after implant placement) and at the 2 years follow-up visit: marginal bone resorption, papilla index, position of the mucosal margin. The implant stability quotient was measured at the moment of implant placement and at the moment of the delivery of the definitive restoration. Results: No statistically significant differences were found in any of the studied parameters between the test and the control groups (P40.05). The implant stability quotient values between the test and control groups were significant (Po0.05) at the moment of implant placement but were no more significant at the loading of the definitive restoration (P40.05). Conclusion: The results of the present study suggest that immediate replacement without functional loading may be considered a valuable therapeutic option for selected cases of single-tooth replacement in the esthetic area when TE implants are used. Implant stability at the moment of implant placement is slightly inferior in the immediate replacement group, but it does not affect the treatment result.

Two‐year prospective clinical comparison of immediate replacement vs. immediate restoration of single tooth in the esthetic zone

Aim: To evaluate the long-term morbidity of intraoral bone harvesting from two different donor sites (mandibular symphysis or ramus) for bone augmentation procedures before or at the time of implant placement and to evaluate the success and the survival rates of implants placed in sites augmented with mandibular bone.

Methods: Seventy-eight patients who received mandibular bone grafts were recalled after 18–42 months follow-up (mean 29 months). The group consisted of 36 men and 42 women aged between 18 and 68 years old at the moment of augmentation surgery. Vitality of teeth adjacent to the harvesting sites was investigated. Soft tissue superficial sensory function was assessed by the Pointed-Blunt Test and the Two-Point-Discrimination Test. Implant health status was assessed measuring peri-implant probing depth and bleeding on probing. Implant survival and success rates were also calculated. In order to evaluate patients' perception of the morbidity of the procedures, the patients were asked to answer several questions by means of visual analogue scales (VAS).

Results: Only two teeth (out of 282) in the chin harvesting group needed root canal treatment after surgery. A higher frequency of minor temporary and permanent sensorial disturbances was found in the group of patients who received chin harvesting procedures (2.3% vs. 13%P=0.03), while pain during chewing and bleeding were more frequently recorded after ramus harvesting (9.8% vs. 0%P=0.03). No permanent anesthesia of any region of the skin was reported. Implants' survival and success rate were comparable to implants placed in bone reconstructed with other techniques and were not influenced by the choice of the donor site. Patient's perception regarding the morbidity of the procedures was very low and did not differ between ramus and chin harvesting groups (mean VAS scores <4).

Conclusion: The present cross-sectional retrospective study demonstrated the safety of mandibular grafts that reported excellent results in terms of implant success and survival rates with minor complications regarding the donor site area. When the chin was chosen as donor site, minor sensorial disturbances of mucosa and teeth were recorded. The majority of these disturbances were temporary; only few of them were permanent but still had no impact on patient's life.

To cite this article:
Cordaro L, Torsello F, Miuccio MT, Mirisola di Torresanto V, Eliopoulos D. Mandibular bone harvesting for alveolar reconstruction and implant placement: subjective and objective cross-sectional evaluation of donor and recipient site up to 4 years.
Clin. Oral Impl. Res. 22, 2011; 1320–1326.
doi: 10.1111/j.1600-0501.2010.02115.x

Mandibular bone harvesting for alveolar reconstruction and implant placement: subjective and objective cross‐sectional evaluation of donor and recipient site up to 4 years

Aim: The aim of the present study was to evaluate if the use of deprotenized bovine bone mineral (DBBM) and collagen barrier membranes (CM) in combination with mandibular bone block grafts could reduce bone block graft resorption during healing.

Methods: A prospective randomized controlled study has been designed. Twenty-two ridges presenting horizontal alveolar deficiency (crest width <4 mm) and at least two adjacent missing teeth were included in the study. In the control group, one or multiple mandibular blocks were used to gain horizontal augmentation of the ridge. In the test group, DBBM granules were added at the periphery and over the graft. The reconstructions were covered by two layers of CM. Implants were placed 4 months after grafting. Direct measurements of crest width were performed before and immediately after bone augmentation, and immediately before implant placement.

Results: Statistical analysis showed no significant differences in crest width between test and control groups at baseline and immediately after grafting. Mean augmentation at first surgery in the test group was 4.18 vs. 4.57 mm in the control group. Final gain obtained at the time of implant placement was 3.93 mm in the test and 3.67 mm in the control groups. The difference in mean graft resorption between test and control sites was statistically significant (0.25 mm in the test group vs. 0.89 mm in the control group, P=0.03).

Complications seem to occur more often in the test group (complications recorded in three cases in the test group vs. one complication recorded in the control group). In all cases, implants could be placed in the planned sites and a total of 55 implants were placed (28 in the test group and 27 in the control group). All implants could be considered successfully integrated at the 24-month follow-up visit.

Conclusion: The results from this study showed that the addition of bovine bone mineral and a CM around and over a mandibular bone block graft could minimize graft resorption during healing. On the other hand, the use of bone substitutes and barrier membranes in combination with block grafts increased the frequency of complications and the difficulty of their management.

To cite this article:
Cordaro L, Torsello F, Morcavallo S, Mirisola di Torresanto V. Effect of bovine bone and collagen membranes on healing of mandibular bone blocks: a prospective randomized controlled study.
Clin. Oral Impl. Res. 22, 2011; 1145–1150.
doi: 10.1111/j.1600-0501.2010.02093.x

Effect of bovine bone and collagen membranes on healing of mandibular bone blocks: a prospective randomized controlled study

Aim: The aim of this study was to compare the clinical outcome of submerged vs. non-submerged tapered implants placed into fresh extraction sockets.

Materials and methods: A prospective, controlled, multicenter, randomized, clinical trial has been performed in two centers in Rome and Torino (Italy). Thirty healthy patients were recruited according to the following inclusion criteria: need for an immediate post extraction implant, ages between 18 and 70, horizontal defect depth <2 mm, smokers <10 cigarettes/day and absence of any circumstance or condition that could represent contraindications to implant surgery. The patients were randomly allocated to submerged or non-submerged treatment groups immediately after flap elevation and tooth extraction. Submerged implants were exposed 8 weeks after the first surgery; all implants were loaded with provisional restorations 12 weeks after the first surgery and with definitive restoration 12 weeks thereafter. Clinical and radiographic parameters were evaluated at baseline, at implant loading and at the 1-year follow-up visit.

Results: The results showed statistically significant differences between the two groups in the mean value of keratinized tissue (KT) height after surgery that was significantly reduced for submerged implants when compared with transmucosal implants (mean reduction of KT at year follow-up: T group 0.2 mm, S group 1.3 mm; P=0.007).

Conclusion: Similar outcomes were found for submerged and non-submerged implants placed in fresh extraction sockets with a horizontal peri-implant defect smaller than 2 mm, except for a reduction of KT in the submerged group. Either with a submerged or a non-submerged procedure, 1 mm of mean soft tissue recession is seen after 1 year when compared with the pre-extraction situation.

Clinical outcome of submerged vs. non-submerged implants placed in fresh extraction sockets.

Objective The aim of the present work was to compare the marginal precision of titanium frameworks for a complete arch-fixed prosthesis fabricated using five different methods. Methods A prospective study was designed. Fifteen titanium frameworks for totally edentulous upper or lower jaws, each supported by five to nine implants, were assigned to five study groups, so as to have three frameworks in each group for each technique: (1) lost wax technique frameworks, (2) cast titanium sovrastructures laser welded to prefabricated titanium copings, (3) Procera Implant Bridge, (4) Cresco Ti System and (5) CAM StructSURE Precision Milled Bar. The microgap between the framework and the shoulders of implant analogues was measured on the master cast with a stereomicroscope at a magnification of 100 x at four different locations, yielding a total of 364 data points on 91 implants. Data were analyzed using an ANOVA and a Tukey post hoc test (P= Results The mean values for the microgap were 78 microm (SD+/-48) for lost wax technique frameworks, 33 microm (SD+/-19) for cast titanium sovrastructures laser welded to titanium copyings, 21 microm (SD+/-10) for the Procera implant bridge, 18 microm (SD+/-8) for the Cresco Ti System and 27 microm (SD+/-15) for the CAM StructSURE. The differences among the mean values were statistically significant (P 0.05). Conclusion The computer-aided procedures analyzed in the present study were able to produce a precision-fitting framework, with no significant differences among them and, at the same time, showed a greater precision compared with the traditional casting methods or with the use of prefabricated titanium copings. However, it should be noted that, even if group 2 frameworks were not as accurate as groups 3 and 4, cast titanium sovrastructures laser welded to prefabricated titanium copings showed significantly better marginal precision than the frameworks produced with the lost wax technique.

Evaluation of the marginal precision of one-piece complete arch titanium frameworks fabricated using five different methods for implant-supported restorations.

Ferruccio Torsello

Papers

Two‐year prospective clinical comparison of immediate replacement vs. immediate restoration of single tooth in the esthetic zone

Mandibular bone harvesting for alveolar reconstruction and implant placement: subjective and objective cross‐sectional evaluation of donor and recipient site up to 4 years

Effect of bovine bone and collagen membranes on healing of mandibular bone blocks: a prospective randomized controlled study

Clinical outcome of submerged vs. non-submerged implants placed in fresh extraction sockets.

Evaluation of the marginal precision of one-piece complete arch titanium frameworks fabricated using five different methods for implant-supported restorations.