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Dental Medicine and Oral Health Sciences

Socket preservation may be an effective method of preserving alveolar ridge anatomy after tooth extraction

Clinical Question: In adults who undergo tooth extraction and subsequent implant placement, to what extent does socket preservation affect ridge anatomy preservation (in terms of ridge width and height) compared to graft-free healing within three months post extraction and beyond?

Clinical Bottom Line: Socket preservation appears to be an effective method of preserving alveolar ridge height when planning subsequent implant placement. Both xenograft and allograft result in an increase in width and height of the alveolar ridge when compared to no intervention at follow ups of more than 4 months post-extraction. The evidence shows that the results of xenograft intervention were clinically meaningful (average alveolar ridge measurement >1 mm clinical threshold) and decisive (95% CI  >1 mm clinical threshold) in preserving ridge height and width, while the results of allograft intervention were clinically meaningful but not clinically decisive for height or width. Comprehensive search strategies, rigorous methodology, appropriate assessment of risk of bias and meta-analysis were employed by the systematic review. Evidence graded as “moderate quality” (GRADE score) includes alveolar ridge height and width changes for xenograft intervention. The quality of evidence was compromised by selection and reporting bias, low sample size of individual studies, low number of included studies and clinical heterogeneity. The interventions and follow up time may be applied worldwide due to similarities in international standards. However, the study population is not universally representative since the inclusion criteria only contemplated posterior teeth and specific edentulous patterns. Clinicians may prefer to use xenograft material in situations that favor significant bone preservation, given the lower financial cost/mm and great amount of bone preserved overall. Clinicians may also favor the lower cost allograft in situations that have minor bone defects. The clinical application is not completely clear due to lack of evidence of subsequent implant success and patient satisfaction measures.

Evidence search: 

("Dental Implants"[Mesh] OR implant[tiab]) AND ("Alveolar Bone Loss/prevention and control"[Mesh] OR socket preservation[tiab] or alveolar ridge preservation[tiab]).  Limits applied: Systematic Review, Randomized Controlled Trial

Search date: July 22, 2014-Nov 1, 2019;  65 articles found; Additional search: 3 CATs

Author, year Source of evidence Population Characteristics Methods

Atieh et al., 2015

PMID: 26020735

Cochrane systematic review
(3 RCTs)

Population: adults aged 26-69 years needed teeth extractions and subsequent implant-supported restoration. SES varied.

Sample size: Participants, N=79, M=32, F=47;  Surgical sites, N=94

Location/Setting: Italy, US; Hospital and University

Search: 9 databases, including Embase, MEDLINE, CENTRAL, OpenGrey

Intervention/Control: Parallel group and split-mouth RCT designs comparing corticocancellous porcine bone xenograft and collagen membrane to extraction alone, and tetracycline hydrated freeze-dried bone allograft to extraction alone.

Primary Outcomes: Assess the effect of ARP BL width of ridge changes*, height changes of ridge*, complications, need for additional augmentation, aesthetics of prosthodontic procedures, and implant failure.Secondary

Outcomes: Changes in peri-implant marginal bone levels, probing depths, clinical attachment levels, and prosthodontic outcomes.
*Applicable to this C.A.T.

Follow up:  ≥4 months

Measurements: digital intraoral periapical radiographs, intrasurgical protocol, occlusal stents

Key Results

Total 50 evidence sources, 8 RCTs selected, 3 RCTs related to the clinical question. Publications from 2003 to 2013.

  • Xenograft vs extraction: MD (loss of height) = -2.60 mm; 95% CI -3.43 to -1.76); MD (loss of width) = -1.97 mm; 95% CI -2.48 to -1.46.
  • Allograft vs extraction: MD (loss of height) = -2.20 mm; 95% CI -0.75 to -3.65; MD (loss of width) = -1.40 mm; 95% CI 0.00 to -2.80.
Evidence Quality

The results found that patients receiving a xenograft ARP procedure lose 1.97 mm less width than extraction alone and lose 2.60 mm less height compared to extraction alone. Xenograft height and width changes were both statistically significant, clinically meaningful (results >1 mm clinical threshold),  and clinically precise (95%CI >1 mm clinical threshold). Patients receiving an alloplast ARP procedure lose 1.40 mm less width than extraction alone and lose 2.20 mm less height compared to extraction alone. Allograft height changes were statistically significant but width was not, height and widths changes were clinically meaningful (results >1 mm clinical threshold), but  not  clinically precise.

Strengths: Rigorous search strategy of multiple databases, three clinical trial registries, hand search of five journals; independent blinded reviewers, PRISMA methodology, meta-analysis, Cochrane tool for risk of bias assessment, GRADE approach for quality of evidence assessment, evidence quality (GRADE) was “moderate quality” for xenograft alveolar ridge height and width changes.

Limitations: Small number of articles (n=3 studies) within each comparison group, small sample sizes (n=94 extraction sites) of individual RCTs, high risk of reporting bias (due to one study’s neglection of non-molar extraction sites in the results despite being listed in the inclusion criteria), high risk of selection bias (due to participant randomization via coin flip being conducted mid-procedure rather than a priori), evidence quality (GRADE) was “low quality” for allograft alveolar ridge height and width changes, xenograft high heterogeneity for population/outcome/time,  low precision of the results (allograft confidence intervals are wide, low number of included studies, low participant numbers).

Perspectives: The recommendation for using ridge preservation techniques would be stronger if there was a stronger source of evidence with increased sample size.


The purpose of alveolar ridge preservation techniques are to prevent loss of ridge anatomy following extraction. The evidence suggests that ARP techniques can improve ridge anatomy post-extraction in the long term, however, “there was no convincing evidence that ARP would improve implant or prosthodontic success”; more studies following up these implants and prosthodontic restorations would be required to confirm that ARP has a positive effect on the restoration survival. The documented adverse effects listed for the ARP procedure were pain and swelling for xenograft placement; allograft placement was described as uneventful. Other potential complications such as partial loss of grafting material, membrane exposure, and fibrous adhesion were not analyzed throughout the 3 selected studies, limiting its applicability.

In Quebec, bone grafts when performed in a hospital setting are covered by RAMQ, therefore free of cost for the patient. Otherwise, the ACDQ fee guide for preservation suggests $185 + material costs, resulting in: xenograft at $489.99 and allograft at $445.99 which is $188.46 per mm of vertical height and $248.73 per mm of horizontal height for xenograft and $202.72 per mm of vertical height and $318.56 per mm of horizontal for allograft.
The evidence from this review can be applicable to Canadian dental private practice setting. However, the population studied is limited to specific teeth and edentulous patterns, those without systemic health problems, non-smokers, those who did not experience alveolar bone fractures, which doesn’t not represent the general population, even though the age criteria of 18 years and older is similar to our population. The intervention (materials, setting, and procedure), and outcomes (changes in ridge height, implant failure, esthetics, need for additional augmentation) are clinically relevant. The time to follow-up of 6 months is sufficient as most of the vertical and horizontal resorption of the alveolar ridge occurs within that time, however it would have been improved if the authors had included follow-up time at 3 months or longer, as at 3 months we can begin to notice changes and in practice some implants may be surgically implanted before 6 months.

Authors: Ricardo Alchini, Khalid Hossain, Bonny Hou, Lorenzo Marcil (DMD3 students)

Faculty mentors: Raphael de Souza, Farzeen Tanwir, Svetlana Tikhonova

Acknowledgments: Martin Morris (McGill librarian)

Date: April 1, 2020


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