This study assessed the success rate of implants placed in horizontal and vertical guided bone regenerated areas. A systematic review was carried out of all prospective and retrospective studies, involving at least five consecutively treated patients, that analysed the success rate of implants placed simultaneously or as second surgery following ridge augmentation by means of a guided bone regeneration (GBR) technique. Studies reporting only the survival rate of implants and studies with a post-loading follow up less than 6 months were excluded. From 323 potentially relevant studies, 32 full text publications were screened and 8 were identified as fulfilling the inclusion criteria. The success rate of implants placed in GBR augmented ridges ranged from 61.5% to 100%; all studies, apart from three, reported a success rate higher than 90% (range 90–100%). The data obtained demonstrated that GBR is a predictable technique that allows the placement of implants in atrophic areas. Despite that, studies with well-defined implant success criteria after a longer follow-up are required.
Dental rehabilitation of partially or totally edentulous patients with oral implants is a valid method for restoring oral aesthetics and function with predictable results. A minimum amount of bone width and height is essential for the successful placement of implants. Unfavourable local conditions, due to atrophy, trauma and periodontal disease, may provide insufficient bone volume or an unfavourable interarch relationship, which does not allow correct and a prosthodontically guided positioning of dental implants.
Many techniques have been developed to reconstruct deficient alveolar jaws for the placement of dental implants performed either in combination or in second stage surgery after a period of healing. The development of the guided bone regeneration (GBR) technique started in the late 1980s with a series of experimental studies. Then clinicians started to use barrier membranes in implant patients for various clinical indications.
GBR is based on the concept of using a resorbable or a non-resorbable barrier membrane to stabilize the blood clot and to create a space into which cells originating from bone tissue can grow without the interference of the faster proliferating soft tissue cells. GBR allows the positioning of dental implants in atrophic ridges, which otherwise would not be possible; survival rates range from 91.7 to 100%.
The survival rates of implants placed in augmented sites with GBR are reported in many publications, but there are few data about the success rate of dental implants placed in those areas, according to universally established criteria. This may represent a limit in evaluating the reliability of the GBR technique, because a high implant survival rate may not correspond to a high GBR success rate bearing in mind that an implant can remain stable and osseointegrated even if the total amount of regenerated tissue has been resorbed after the GBR procedure.
The present systematic review was carried out to analyse all publications reporting the success rate of implants placed in vertically and horizontally augmented areas using the GBR technique. The specific question addressed was ‘In patients treated with horizontal and/or vertical GBR, what are the clinical outcomes, in terms of implant success rate after a minimum 6 month follow-up period?’
Material and methods
Inclusion and exclusion criteria were defined by the authors, before the start of the study.
The inclusion criteria were as follows. All studies published in English language, based on human subjects, involving more than five consecutively treated patients were considered. All studies analysing the success rate of endosseus implants placed in jaws augmented by means of horizontal and vertical GBR were included. Studies had to report on implants with at least 6 months of loading, because this allows the observation of biological complications during function rather than early implant failures. Studies had to show data allowing the computation of the success rate by means of survival analysis. Studies on smokers were included. Studies on healthy patients were included.
The exclusion criteria were as follows. Publications that reported the same data as later publications by the same authors and systematic reviews were not considered. Studies reporting the results of GBR not followed by implant placement and/or with a post-loading follow-up period less than 6 months, were excluded. Studies reporting only the survival rate of implants or with not enough specified success criteria were not included. Studies on medically compromised patients were excluded. Studies about major maxillofacial reconstructions following big tissue resections in case of tumours as well as bone defects related to congenital malformations (such as cleft lip and palate or major craniofacial malformations), were excluded. Studies describing socket preservation techniques or the treatment of periimplantitis were excluded.
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.
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.
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.
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.
The search resulted in 4299 titles. Following the first stage of screening, 323 potentially relevant studies were identified. After the second stage screening, 32 full text publications were obtained and analysed, resulting in 8 articles fulfilling the inclusion criteria ( Table 1 ).
The review included prospective and retrospective cohort studies reporting data about the success rate of implants placed in areas augmented by vertical and/or horizontal GBR procedures. Owing to the significant heterogeneity of the outcome measures, meta-analysis was not performed and the synthesis of the data was determined from the evidence table alone ( Table 2 ).
|Author||Type of study||Year||City||Type of augm.||N. patients||Mean age||Implants||Area of implants||Post-loading follow-up||Cumulative success rate of implants||Cumulative survival rate of implants|
|1. F. Llambés||c.s.||2007||Valencia (Spain)||Vertical gbr||11||48||32 imm.||Mandible||1 year||75%||93.75%|
|2. G. Juodzbalys||c.s.||2007||Kaunas (Lithuania)||Vertical gbr||17||39.6||20 imm.||–||1 year||90%||100%|
|3. P.A. Fugazzotto||r.s.||2005||Milton (Massachussets)||Vertical and||319||49||423 imm/del||215 maxilla||7 years||98.30%||–|
|Horizontal gbr||208 mand.||11 years||97.40%|
|4. M. Chiapasco||rct||2004||Milan (Italy)||Vertical gbr||11||–||25 (13 imm; 12 del)||10 maxilla
|1 year||84.6% (imm)||100% (imm)|
|83.3% (del)||100% (del)|
|2 year||76.9% (imm)||100% (imm)|
|83.3% (del)||100% (del)|
|3 year||61.5% (imm)||100% (imm)|
|75% (del)||100% (del)|
|5. D. Buser||c.s||2002||Berne (Switzerland)||Horizontal gbr||40||–||61 del.||–||1 year||100%||100%|
|6. G. Brunel||c.s.||2001||Toulouse (France)||Gbr||14||48||14 del.||13 maxilla
|7. M. Simion||ccs||2001||Parma (Italy)||Vertical gbr||49||50.4||123 (120 imm; 3 del)||–||1 year||97.50%||99.20%|
|8. M. Lorenzoni||c.s.||1999||Graz (Austria)||Gbr||82||21–61||85||39 maxilla