The objective of this systematic review was to test the hypothesis of no difference in implant treatment outcomes when using Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone grafts for lateral ridge augmentation. A search of the MEDLINE, Cochrane Library, and Embase databases in combination with a hand-search of relevant journals was conducted. Human studies published in English from 1 January 1990 to 1 May 2016 were included. The search provided 337 titles and six studies fulfilled the inclusion criteria. Considerable variation prevented a meta-analysis from being performed. The two treatment modalities have never been compared within the same study. Non-comparative studies demonstrated a 3-year implant survival of 96% with 50% Bio-Oss mixed with 50% autogenous bone graft. Moreover, Bio-Oss alone or Bio-Oss mixed with autogenous bone graft seems to increase the amount of newly formed bone as well as the width of the alveolar process. Within the limitations of this systematic review, lateral ridge augmentation with Bio-Oss alone or in combination with autogenous bone graft seems to induce newly formed bone and increase the width of the alveolar process, with high short-term implant survival. However, long-term studies comparing the two treatment modalities are needed before final conclusions can be drawn.
Lateral ridge augmentation (LRA) involving an autogenous bone block is the most commonly used surgical procedure to augment the severely atrophic alveolar process . However, harvesting autogenous bone from the mandible or the iliac crest is associated with donor site morbidity and increased costs . Moreover, the use of autogenous bone grafts is associated with resorption of the graft material . Therefore, bone substitutes alone or in combination with a particulate autogenous bone graft (PABG) are used increasingly to simplify the surgical procedure and minimize donor site morbidity.
Previous short-term human studies assessing LRA with deproteinized bovine bone mineral (Bio-Oss, Geistlich Pharma AG, Wolhusen, Switzerland) alone or in combination with PABG have shown the formation of new bone, an increase in the width of the alveolar process, and a high implant survival rate . A previous published systematic review concluded that horizontal defects can be augmented predictably up to a width of approximately 3.7 mm using particulate grafting material, without any preference for its origin . However, the outcome of implant treatment following LRA with Bio-Oss alone or Bio-Oss mixed with PABG has not been assessed specifically in a systematic review.
Materials and methods
This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-Equity 2012 checklist .
The objective of this systematic review was to test the hypothesis of no difference in implant treatment outcomes when using Bio-Oss alone or Bio-Oss mixed with PABG as graft material for LRA.
Consideration of eligibility criteria for this review
The inclusion criteria were developed using the PICO guidelines and included human studies evaluating LRA with Bio-Oss alone or Bio-Oss mixed with PABG ( Table 1 ). Moreover, non-comparative human studies assessing LRA with Bio-Oss alone or Bio-Oss mixed with PABG were also included.
|Patient and population (P)||All patients were adult patients with partial or total edentulism|
|Intervention (I)||Lateral ridge augmentation with Bio-Oss alone or in combination with particulate autogenous bone graft|
|Comparator or control group (C)||Lateral ridge augmentation with a mixture of Bio-Oss and particulate autogenous bone graft|
|Outcomes (O)||Survival of suprastructures and implants, bone regeneration, width gained at the alveolar process, width reduction of the graft material, volumetric stability of the graft material, patient-reported outcome measures, complications related to the surgical procedure|
|Focused question||Are there any differences in implant treatment outcomes after lateral ridge augmentation with Bio-Oss alone or in combination with particulate autogenous bone|
The primary outcome measures are the most important measures for evaluating the final treatment outcome. Secondary outcome measures were also included in this systematic review as surrogate measures, due to the lack of studies focusing on the primary outcome measure.
The primary outcome measures were (1) the survival of suprastructures: loss of the suprastructure was defined as total loss due to a mechanical and/or biological complication; (2) the survival of implants: loss of implants was defined as non-integrated implants, mobility of previously clinically osseointegrated implants, and removal of non-mobile implants due to progressive peri-implant marginal bone loss or infection.
Moreover, the following secondary outcome measures were assessed: (1) bone regeneration, assessed by histological measurements; (2) width gained at the alveolar process, assessed by clinical or radiographic measurements; (3) width reduction of the graft material, assessed by two-dimensional measurements; (4) volumetric stability of the graft material, assessed by three-dimensional measurements; (5) patient-reported outcome measures; (6) complications related to the surgical procedure.
A search of the MEDLINE (PubMed), Cochrane Library, and Embase databases was conducted. Human studies published in English from 1 January 1990 to 1 May 2016 were included. The search strategy utilized a combination of controlled vocabulary terms (medical subject headings, MeSH) and free text terms. The headings were (alveolar ridge augmentation OR alveolar AND ridge augmentation) AND (lateral OR horizontal) AND (Bio-Oss OR bone substitute OR bovine bone OR xenograft).
The search was supplemented by a thorough hand-search, page by page, of relevant journals. The manual search also included the bibliographies of all articles selected for full-text screening, as well as previously published reviews relevant to the present systematic review. The search was performed by two reviewers (HCA and TJ). Any disagreement between the two observers was resolved by consensus.
The titles of the identified reports were initially screened. The abstract was assessed when the title indicated that the study fulfilled the inclusion criteria. Full-text analysis was performed when the abstract was unavailable or when the abstract indicated that the inclusion criteria were fulfilled. The study selection process was performed by two reviewers (HCA and TJ). Any disagreement between the two observers was resolved by consensus.
Human studies assessing the outcome of LRA with Bio-Oss alone or mixed with PABG were included; these studies addressed the previously described outcome measures. The review exclusively focused on studies applying LRA in non-prepared sites with delayed implant installation. In addition, at least five patients had to have been included in the study. Studies including both lateral and vertical ridge augmentation were included if the outcome measures for LRA alone could be clearly identified. Studies comparing Bio-Oss with autogenous bone graft alone were included if the outcome measures could be identified for Bio-Oss alone or in combination with PABG.
Studies using Bio-Oss blocks alone or Bio-Oss blocks in combination with granules were excluded if the outcome measures could not be identified for granules alone . In addition, studies using an unknown ratio of Bio-Oss to PABG were excluded, as well as studies applying immediate implant placement .
A quality assessment of the included studies was undertaken by one review author (HCA) as part of the data extraction process. The quality assessment was performed according to the following parameters: (1) adequate randomization (yes/no); (2) blinding of outcome measurement (yes/no); (3) completeness of follow-up; a clear explanation for withdrawals and drop-outs (yes/no); (4) histological evaluation involving unbiased stereological methods (yes/no).
The studies were defined as having a low risk of bias (plausible bias unlikely to seriously alter the results) if all of the quality criteria described above were met, or as having a high risk of bias (plausible bias that seriously weakens confidence in the results) if any of the quality criteria described above were not met.
Data were extracted by one reviewer (HCA) according to the data collection form, ensuring systematic recording of the outcome measures. In addition, relevant characteristics of the studies were recorded. In the case of any uncertainty, another reviewer was consulted (TJ).
The studies included in the review revealed considerable variations in design, i.e. width of the alveolar process, ratio of Bio-Oss and PABG, presence or absence of a barrier membrane, length of the observation period, and types of outcome measure. Therefore, a meta-analysis was not possible for the present review.
Description of studies
A flow diagram of the search process is given in Fig. 1 . A total of 337 titles were identified and 179 abstracts were reviewed. The full-text analysis resulted in six articles for inclusion; these articles reported six non-comparative studies . No studies were included as a result of the hand-search.
LRA was performed with Bio-Oss alone in two studies . The other four studies used different mixtures of Bio-Oss and PABG , involving 50% Bio-Oss and 50% PABG , 60% Bio-Oss and 40% PABG , and 90% Bio-Oss and 10% PABG . In all studies, the autogenous bone graft was harvested from the mandible. In one study, three different regions were used for the harvesting procedure: the retromolar region, the ascending mandibular ramus, and the symphysis region . The retromolar region alone was used in two studies and the ascending mandibular ramus in one study . The use of a covering membrane varied between the studies, including the use of a non-resorbable membrane , a resorbable membrane , no membrane and fibrin glue15, or a resorbable membrane in combination with fibrin glue18. The main results are described and summarized in Tables 2 and 3 .
|Ref.||Patients||Materials and methods||Follow-up||Implants, n||Results||Conclusion|
|New bone formation||Complications|
|Zitzmann et al. 2001||6||6 sites: Bio-Oss and Bio-Gide membrane||6–7 months||NR||NFB, 22.6%||NR||Bio-Oss may be a very suitable material for LRA in humans|
|Friedmann et al. 2002||28||14 sites: Bio-Oss and collagen membrane||7 months||50||NFB, 42%||Postoperative dehiscence: 16 after 1–3 weeks; 12 after more than 3 weeks||Bio-Oss is suitable as a bone substitute without addition of PABG|
|Bio-Oss, 14%||Re-augmentation needed: 1|
|14 sites: Bio-Oss and e-PTFE membrane||NFB, 39%|
|Ref.||Patients||Materials and methods||Follow-up||Implants, n||Results||Conclusion|
|Primary outcome||Secondary outcomes|
|Implant survival||New bone formation||Gain in ridge width||WRG||VS||Complications|
|Hellem et al. 2003||24||24 sites: 50% Bio-Oss and 50% PABG||6 months,||74||95.9%||NR||NR||NR||NR||Abutment fracture: 1||Mixture of 50% Bio-Oss and 50% PABG useful for LRA|
|Facing fractures of SS: 2|
|Urban et al. 2011||16||18 sites: 50% Bio-Oss, 50% PABG and resorbable synthetic membrane||38.8 months||42||100%||No difference in amount of NFB in apical and coronal parts||5.56 mm||NR||NR||NR||PAGB in combination with Bio-Oss covered by resorbable membrane is effective for LRA|
|Mordenfeld et al. 2013||13||14 sites: 60% Bio-Oss and 40% PABG||7.5 and 8 months||71||NR||NFB, 20%||At 3 mm from top of crest: 3.5 mm||37%||53.8%||Postoperative dehiscence: 7||Significantly less graft width reduction with mixture 60:40 compared with mixture 90:10|
|Bio-Oss, 28.3%||At 6 mm from top of crest: 4.5 mm||No histomorphometric differences between groups|
|14 sites: 90% Bio-Oss and 10% PABG||NR||NFB, 22.7%||At 3 mm from top of crest: 2.9 mm||46.9%||55.3%|
|Bio-Oss, 30.1%||At 6 mm from top of crest: 4.0 mm|
|Urban et al. 2013||25||31 sites: 50% Bio-Oss, 50% PABG and resorbable collagen membrane||8.9 and 20.9 months||76||100%||NFB, 31.0%||5.68 mm||NR||NR||Abscess at graft site:1||This treatment can be regarded as successful|
|Bio-Oss, 25.8%||Patient was retreated with a successful result|