Types of interventions

GBR to reconstruct vertical and/or horizontal defects, was considered. According to the principle of GBR, a protected space is created with a resorbable or non-resorbable barrier membrane over the area to be augmented, to stabilize the blood clot and to exclude soft tissue penetration. Bone regeneration may be obtained by means of membranes alone, or with the aid of various grafting materials, such as autogenous bone; demineralized or mineralized freeze-dried bone allografts, hydroxyapatite, bovine bone mineral, tri-calcium phosphate or mixtures of different materials.

Outcome measures

Implant success, as a combination of the success criteria previously defined by Albrektsson et al., and adapted by Buser et al., as well as Karoussis et al., was considered. It included: absence of mobility ; absence of persistent subjective complaints (pain, foreign body sensation and/or dysaesthesia) ; absence of recurrent peri-implant infection with suppuration ; absence of a continuous radiolucency around the implant ; no pocket probing depth (PPD) >5 mm ; and no PPD ≥ 5 mm and bleeding on probing (BOP). During the first year, 1.5 mm of vertical bone resorption was accepted. After the first year of insertion, the annual vertical bone loss should not exceed 0.2 mm (mesially or distally).

Even though not all the studies adopted the same success criteria, they were always well specified in the publications included.

Search strategy

The search strategy involved searching electronic databases (MEDLINE, EMBASE, and COCHRANE LIBRARY) and was supplemented by cross-checking the bibliographies of relevant review articles, up to January 2010.

The following combination of words was used: (success[All Fields] AND rate[All Fields]) OR (“dental implants”[MeSH Terms] OR #“dental”[All Fields] AND “implants”[All Fields]# OR “dental implants”[All Fields]) OR #osseointegrated[All Fields] AND implants[All Fields]# OR ##“mouth”[MeSH Terms] OR “mouth”[All Fields] OR “oral”[All Fields]# AND implants[All Fields]# OR #implant[All Fields] AND supported[All Fields] AND #“prosthesis implantation”[MeSH Terms] OR #“prosthesis”[All Fields] AND “implantation”[All Fields]# OR “prosthesis implantation”[All Fields] OR “prosthesis”[All Fields] OR “prostheses and implants”[MeSH Terms] OR #“prostheses”[All Fields] AND “implants”[All Fields]# OR “prostheses and implants”[All Fields]## OR #transmucosal[All Fields] AND implants[All Fields]# OR one-stage[All Fields] OR two-stages[All Fields] OR #immediate[All Fields] AND placement[All Fields]# OR #delayed[All Fields] AND placement[All Fields]#) AND #“alveolar ridge augmentation”[MeSH Terms] OR (“alveolar”[All Fields] AND “ridge”[All Fields] AND “augmentation”[All Fields]) OR “alveolar ridge augmentation”[All Fields]) OR (vertical[All Fields] AND ridge[All Fields] AND augmentation[All Fields]) OR (augmented[All Fields] AND ridges[All Fields]) OR (“bone regeneration”[MeSH Terms] OR (“bone”[All Fields] AND “regeneration”[All Fields]) OR “bone regeneration”[All Fields]) OR (“bone substitutes”[MeSH Terms] OR (“bone”[All Fields] AND “substitutes”[All Fields]) OR “bone substitutes”[All Fields]) OR (autogenous[All Fields] AND (“bone and bones”[MeSH Terms] OR (“bone”[All Fields] AND “bones”[All Fields]) OR “bone and bones”[All Fields] OR “bone”[All Fields]) AND (“transplantation”[Subheading] OR “transplantation”[All Fields] OR “grafts”[All Fields] OR “transplants”[MeSH Terms] OR “transplants”[All Fields])) OR (“inlays”[MeSH Terms] OR “inlays”[All Fields] OR “onlay”[All Fields]) OR ((“inlays”[MeSH Terms] OR “inlays”[All Fields] OR “onlay”[All Fields]) AND (“bone and bones”[MeSH Terms] OR (“bone”[All Fields] AND “bones”[All Fields]) OR “bone and bones”[All Fields] OR “bone”[All Fields]) AND (“transplantation”[Subheading] OR “transplantation”[All Fields] OR “grafts”[All Fields] OR “transplants”[MeSH Terms] OR “transplants”[All Fields])) OR (“bone transplantation”[MeSH Terms] OR (“bone”[All Fields] AND “transplantation”[All Fields]) OR “bone transplantation”[All Fields]) OR (“transplantation, homologous”[MeSH Terms] OR (“transplantation”[All Fields] AND “homologous”[All Fields]) OR “homologous transplantation”[All Fields] OR (“homologous”[All Fields] AND “transplantation”[All Fields])) OR “transplantation, homologous”[MeSH Terms] OR (“transplantation”[All Fields] AND “homologous”[All Fields]) OR “homologous transplantation”[All Fields] AND %5[All Fields].

Studies published in the English language were included.

Selection criteria and data extraction

The search resulted in a great number of published studies about the topic, so a three stage screening process was performed by two independent reviewers (A.M. and M.C.) and disagreement between the two reviewers was resolved after additional discussion.

All the titles were screened to eliminate irrelevant publications, review articles and animal studies. All abstracts of publications selected during the first screening were analysed, excluding studies based on the number of patients, the intervention and the outcome characteristics. Through analysis of the whole selected full texts, the study eligibility was based on the predetermined inclusion and exclusion criteria. A table with data from all the included studies was created and the results were discussed.

Quality assessment

Assessment of methodological study quality was performed combining the proposed criteria by MOOSE statement, STROBE statement, PRISMA.

When random selection in the population, defined inclusion/exclusion criteria, report of losses to follow-up, validated measurements and statistical analysis were reported the study was classed as at a low risk of bias. When missing one of these five criteria, the study was classed as having a moderate potential risk of bias. There was a high potential risk of bias if the study was missing two or more of these criteria.