Scolaris Content Display Scolaris Content Display

Cochrane Database of Systematic Reviews Protocol - Intervention

Interventions for replacing missing teeth: alveolar ridge preservation techniques for oral implant site development

Authors' declarations of interest

Version published: 14 November 2012 Version history

https://doi.org/10.1002/14651858.CD010176

This is not the most recent version

view the current version 26 April 2021
Collapse all Expand all

Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the clinical effects of various materials and techniques for alveolar ridge preservation (ARP) after tooth extraction compared with extraction alone and/or other methods of ARP for patients requiring oral implant placement following healing of extraction socket.

Background

Description of the condition

Tooth extraction is performed because of different pathological, endodontic, periodontal or traumatic reasons, and often without any consideration for the preservation of the alveolar ridge. Following extraction of permanent teeth, bone remodelling occurs and continues for several months, with most changes occurring in the first three months (Schropp 2003). Post‐extraction alveolar bone changes have been estimated to cause 50% reduction in the bucco‐lingual width of alveolar bone (Lekovic 1997; Lekovic 1998; Camargo 2000; Iasella 2003; Schropp 2003), and a further loss in height has also been reported (Lam 1960; Iasella 2003). A systematic review evaluated the dimensional changes of the alveolar ridge following tooth extraction and showed mean reduction of 3.8 and 1.24 mm in width and height respectively in the first 6 months (Tan 2012). The predictable order of bone resorption is known with the buccal aspect resorbing first (Soehren 1979; Cawood 1988), greater resorption in width than height (Johnson 1967), and with the mandibular bone resorbing faster than the maxillary bone (Atwood 1971; Tallgren 1972). Furthermore, a lingual shift of the crest of the bone, in relation to the original position of the tooth, has also been identified (Pietrokovski 1975). Disuse atrophy, inadequate vascularisation and inflammatory response have been implicated as causative factors for alveolar ridge resorption (Ashman 2000). 

The overall alveolar changes, following tooth extraction, may compromise the prosthodontic rehabilitation using fixed, removable, or more importantly, implant‐supported prostheses. The alveolar bone resorption may not allow an optimal positioning of oral implants (Mecall 1991; John 2007). Therefore, the planning for a prosthodontically‐driven implant placement may invariably require the preservation of the original alveolar ridge dimensions following tooth extraction. Postoperative care of extraction sockets to reduce postoperative pain and minimise complications following extractions, and to improve soft and hard tissue healing, have been previously investigated (Khosla 1971). The practice of bone preservation following tooth extraction in an attempt to maintain ridge height and width was first described as 'bone maintenance' (Ashman 1982; Greenstein 1985; Kentros 1985). Different terms were then used to describe the same procedure such as 'socket preservation', 'socket augmentation', 'socket grafting', 'ridge preservation', and 'alveolar bone grafting'. To avoid ambiguity, the term 'alveolar ridge preservation' (ARP) will be used throughout this review. ARP is defined as the procedure of arresting or minimising the alveolar ridge resorption following tooth extraction for future prosthodontic treatment including placement of oral implants.

The purpose of ARP is to maintain a favourable alveolar ridge architecture for future implant placement. The timing of implant placement varies and may influence the final functional and aesthetic outcomes. Following ARP, delayed implant placement is considered to allow time for bone formation within the extraction socket. A recent consensus statement has limited the potential benefits of immediate implant placement particularly in the aesthetic zone where a high rate of mucosal recession is expected (Hammerle 2012). Nevertheless, there remains a lack of evidence regarding the optimal timing for implant placement after ARP.

ARP techniques may include the placement of different grafting materials with or without the use of membranes to preserve and minimise ridge resorption for optimising future implant placement. Two systematic reviews (Hammerle 2012; Vignoletti 2012) were recently published and demonstrated a significantly less reduction in the vertical and horizontal dimensions in alveolar ridge following ARP. However, clinicians' choice of ARP technique often relies on personal preference rather than evidence of efficacy. The clinical efficacy of grafting materials and procedures for ARP remains controversial with each claiming superiority in limiting the horizontal and vertical alveolar ridge resorption.

Description of the intervention

ARP techniques include the use of grafting materials of human or synthetic origin with or without the use of barrier membranes to further optimise the functional and aesthetic restoration of oral implants. The grafting materials include: particulate autogenous chips (Becker 1994; Araujo 2011), allografts (Iasella 2003), xenografts (Carmagnola 2003; Araujo 2010), and alloplasts (Norton 2002).

In addition, the literature describes a variety of membranes for covering extraction sockets and preserving alveolar ridges. Barrier membranes can be classified into two main categories: the non‐resorbable and resorbable membranes. The former is characterised by its larger bone fill and favourable marginal tissue response provided that the membrane is not exposed (e.g. expanded polytetrafluoroethylene (ePTFE)) (Bartee 1998). On the other hand, resorbable membranes do not require a second surgery and are characterised by significant improvement in soft tissue healing with minimal tissue reaction to membrane exposure (e.g. bovine and porcine collagen matrices) (Iasella 2003).

How the intervention might work

Three main mechanisms are proposed.

  • Osteogenesis, is the principle of bone healing process in which bone is formed by the host's osteoblasts and osteocytes. This is mostly observed with autogenous grafts (Araujo 2011) and tissue engineering (Nevins 2011).

  • Osseoinduction, is the stimulation of bone growth by the use of grafting materials that activate the mesenchymal cells to differentiate into bone forming cells (osteoblasts). This is often linked to the use of demineralised freeze‐dried bone allografts (DFDBA) (Iasella 2003) and the recombinant human bone‐morphogenetic proteins (rhBMPs) (Boyne 2004).

  • Osseoconduction, is the process of encouraging the formation of capillaries and progenitor cells from the recipient site by using osseoconductive materials (i.e. xenograft, mineralised allografts and alloplasts) that act as a scaffold which allows the establishment of new bone (Barone 2008).

Resorbable and non‐resorbable membranes are thought to keep the grafting material in place and maintain the space to allow bone regeneration and predictably preserve the shape of the alveolar ridge.

Why it is important to do this review

Although several techniques and materials have been introduced to preserve the alveolar ridge, little evidence exists with regard to the efficacy of these techniques in reducing alveolar ridge resorption and the superiority of one technique over the other. The existing data show conflicting results with some considering the use of grafting material for ARP an effective technique in limiting alveolar ridge resorption (Iasella 2003; Barone 2008), while others argue that intra‐socket grafts may compromise the normal healing process of the extraction socket, or be of no benefits in preserving the alveolar ridge (Becker 1998; Buser 1998). A further controversy is related to the rate at which grafting material may resorb with several studies showing that particles of different grafting material may remain within the socket for more than 6 months following placement (Becker 1994; Artizi 2000; Carmagnola 2003). Therefore, the aim of this systematic review will be to evaluate the clinical efficacy of the different materials and techniques used for ARP and to provide evidence, for clinicians and consumers, on their effects in preventing or minimising alveolar ridge resorption.

Objectives

To assess the clinical effects of various materials and techniques for alveolar ridge preservation (ARP) after tooth extraction compared with extraction alone and/or other methods of ARP for patients requiring oral implant placement following healing of extraction socket.

Methods

Criteria for considering studies for this review

Types of studies

All randomised controlled trials (RCTs), cross‐over trials and split‐mouth studies on the use of alveolar ridge preservation (ARP) techniques, including the use of barrier membrane (alone or with bone graft), in mandibular or maxillary, molar or non‐molar sites with at least 6 months of follow‐up, will be included in this review. The follow‐up is regarded as the period from tooth extraction until the final measurements of the alveolar ridge prior to or at the time of implant placement.

The studies that evaluated the use of ARP procedures in patients requiring non‐implant related prosthodontic treatment will be excluded.

No language restrictions will be applied.

Types of participants

Adult participants that are 18 years or older, in good general health, and require extraction of one or more permanent tooth with consideration of future prosthodontic treatment including delayed placement of an oral implant.

Types of interventions

Any method of ARP with or without the use of any type of barrier membranes after tooth extraction. ARP will be compared to either extraction alone (no ARP is performed), or another type of ARP.

Types of outcome measures

Primary outcomes

  • Changes in the bucco‐lingual/palatal width of alveolar ridge.

  • Changes in the vertical height of the alveolar ridge.

  • Post‐surgical complications (i.e. discomfort, pain and swelling).

  • Need for additional augmentation prior to implant placement.

  • Aesthetic outcomes of future prosthodontic rehabilitation.

  • Implant failure rate.

Secondary outcomes

  • Peri‐implant marginal bone level changes.

  • Changes in probing depth (PD) at teeth adjacent to the extraction site.

  • Changes in clinical attachment level (CAL) at teeth adjacent to the extraction site.

  • Prosthodontic outcomes of future prosthodontic rehabilitation.

Search methods for identification of studies

For the identification of studies included or considered for this review, detailed search strategies will be developed for each database searched. These will be based on the search strategy developed for MEDLINE (Appendix 1) but revised appropriately for each database to take account of differences in controlled vocabulary and syntax rules. The reference lists of all eligible trials will be checked for additional studies.

The search strategy will combine the subject search with the Cochrane Highly Sensitive Search Strategy for identifying RCTs, as detailed in box 6.4c of the Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011] (Higgins 2011).

Electronic searches

Databases to be searched

We will search the following electronic databases.

  • The Cochrane Oral Health Group's Trials Register (whole database)

  • The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, current issue)

  • MEDLINE via OVID (1948 to present)

  • EMBASE via OVID (1980 to present)

  • LILACS via BIREME (1982 to present)

  • The metaRegister of current Controlled Trials (http://www.controlled‐trials.com/) (whole database)

  • Clinical Trials.gov (www.clinicaltrials.gov) (whole database)

  • The World Health Organization International Clinical Trials Registry platform (http://apps.who.int/trialsearch/) (whole database)

  • Web of Science Conference Proceedings (1990 to present)

  • Scopus (1966 to present)

  • ProQuest Dissertations and Abstracts service (1861 to present)

  • OpenGrey (http://www.opengrey.eu/) (whole database).

Searching other resources

A number of journals have been handsearched as part of the Cochrane worldwide handsearching programme (see the Masterlist of journals being handsearched for more information). In addition, the following journals will be handsearched for the period 2003 to 2012.

  • Clinical Oral Implants Research

  • Journal of Clinical Periodontology

  • Journal of Periodontology

  • International Journal of Oral and Maxillofacial Implants

The Editors‐in‐Chief of the selected dental journals will also be approached via e‐mail in an attempt to identify the relevant papers that were submitted or accepted at the time of the search. The corresponding authors will be contacted if further information is required. The manufacturers of different grafting materials will also be approached in an attempt to identify any unpublished or ongoing studies.

Data collection and analysis

Selection of studies

The retrieved citations will be screened independently for relevance by at least two review authors in duplicate. The search results will be printed off and checked on the basis of title first, then by abstract, keywords or both. Irrelevant references will be discarded, and those that are screened as relevant will be obtained in full and assessed for inclusion in the review by using an eligibility form that will be prepared and pilot tested in advance. If disagreement arises, it will be resolved by discussion. Where resolution cannot be reached, a third review author will be consulted. In the presence of more than one publication of a trial, all the publications will be reviewed and the corresponding author will be contacted to check if all papers are related to the same study. In case of duplicate publication, all the references will be included and then a primary reference will be selected for data extraction. The rejected studies will be recorded in the table of excluded studies and reasons for exclusion will be documented. Foreign language studies will be translated prior to data extraction and risk of bias assessment.

Data extraction and management

A piloted data extraction form will be used by at two review authors to independently extract the data, in duplicate, from all the included studies and any arising discrepancy will be discussed with a third review author. Corresponding authors of studies will be contacted for obtaining missing data or clarification, and studies with lack of sufficient data will be excluded. Data from foreign language papers will be extracted with the help of appropriate translators. The review authors will not be blinded to the study authors' names, institutional affiliations, journal of publication, and the results of the study. The following data will be recorded for each included trial according to the Cochrane review guidelines.

  1. Study characteristics: title, authors' names, contact address, study location, language of publication, year of publication, published or unpublished data, source of study funding, study design (parallel group or split mouth), method of randomisation, duration of study, allocation concealment, and blinding (participants, investigators, outcome examiners).

  2. Participants: demographic characteristics, inclusion/exclusion criteria, number of participants in test and control groups, number of withdrawals and the reasons for dropouts.

  3. Interventions: types of ARP techniques and grafting materials.

  4. Comparison: extraction alone (no ARP is performed) or another method of ARP.

  5. Outcomes: the previously described outcomes in addition to any other outcomes evaluated in the study. The method of assessment, length of the observation period and any adverse events will also be recorded.

Any discrepancy in data extraction will be resolved by discussion and contacting the corresponding author of the original study if necessary.

Assessment of risk of bias in included studies

At least two review authors will independently assess the risk of bias, in duplicate, for the included studies by using a two‐part tool that addresses the seven domains set out in Section 8 of the Cochrane Handbook for Systematic Reviews for Interventions (Higgins 2011). The seven specific domains include sequence generation, allocation concealment, blinding of participants and investigators, blinding of outcome assessment, incomplete outcome data, selective outcome reporting, and potential sources of bias. In the 'Risk of bias' table, the first part of the tool involves a description for each entry while the second part determines the risk of bias by assigning a judgment for each entry as 'Low risk' of bias, 'High risk' of bias, and 'Unclear risk' of bias indicating uncertainty or lack of information.

Allocation is adequately concealed if it follows one of the following methods: central randomisation, on‐site computer software with allocation stored in locked computer file, pharmacy‐controlled randomisation, coded numbered containers, opaque, sealed and sequentially numbered envelopes. On the other hand, alternation, use of date of birth, and file number are considered as inadequate methods of allocation concealment. The overall risk of bias will be assessed by completing a 'Risk of bias' table for each included study and then studies will be grouped in the following categories.

  • Low risk of bias when all key domains are assessed as being at low risk of bias (a possible bias that is unlikely to alter the results).

  • High risk of bias when one or more domain are assessed as being at high risk of bias (a likely bias that seriously indicates less confidence about the results).

  • Unclear risk of bias when one or more key domains are assessed as unclear (a likely bias that raises doubts about the results).

Measures of treatment effect

Continuous data

The mean difference (MD) and 95% confidence interval (CI) will be calculated for continuous outcomes such as changes in width and height of alveolar ridge. The reported mean changes from baseline as well as the final mean scores can be combined as MD. In the event of combining studies using different scales of measurements, the standardised mean difference (SMD) will be used.

Binary data

Risk ratios (RR) and 95% CIs will be calculated for dichotomous outcomes such as implant failure rate. It is expected that the statistical unit will be the patient and not the treated site.

Studies with several treatment groups

The raw data (mean values and standard deviations) will be obtained for all treatment and control groups in the presence of more than one relevant treatment group and control group. The control group numbers will then be divided into approximately equally sized smaller groups in order to provide a pair wise comparison for each treatment modality. Thus, all the relevant data will be included in the primary meta‐analyses (Higgins 2011).

Unit of analysis issues

The statistical unit will be the patient in parallel group trials, while in split‐mouth studies, the site will be the unit of analysis. The following issues will be taken into account in data analysis.

  • The errors related to the unit of analysis particularly in the presence of multiple treatment sites in split‐mouth studies.

  • The level of randomisation (i.e. cluster‐randomised trials).

  • Multiple observations (i.e. repetition of measurements of the same outcome).

Dealing with missing data

In the event of incompletely reported data regarding the study characteristics, methods and results, the corresponding authors will be contacted for clarification. The missing standard deviations of continuous variables will be estimated using the methods detailed in section 7.3.3 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).

Assessment of heterogeneity

Heterogeneity among the included studies will be expected due to the presence of different materials and membranes used for ARP. Cochran's test for heterogeneity and the I 2 statistic will be used to statistically determine the percentage variation across the studies. The tests for heterogeneity will be interpreted according to the guidelines detailed in section 9.5 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). A graphical inspection of the estimated treatment effects from the trials will also be used to assess the heterogeneity of the studies.

Assessment of reporting biases

A comprehensive search will be adopted in an attempt to avoid reporting bias. The search will include grey literature, non‐English language publications, and contacting different manufacturers to identify ongoing and unpublished clinical trials. The funnel plot technique will be used to assess publication and reporting bias in the presence of a sufficient number of RCTs (Egger 1997). Other corrective analytical methods will be implemented depending on the number of included studies.

Data synthesis

Meta‐analyses will only be conducted for trials of similar comparisons reporting the same outcome measures. The meta‐analysis will be used to quantitatively summarise the results using RevMan 5. In the presence of four or more trials, risk ratios will be combined for dichotomous data, and mean differences for continuous data using a random‐effects model. Otherwise, a fixed‐effect model will be used for combining three or less trials. The effect of ARP techniques for bone maintenance will be assessed according to different outcomes (alveolar bone width and height, post‐surgical complications, need for additional augmentation, and implant failure).

Subgroup analysis and investigation of heterogeneity

Subgroup analysis will be performed to investigate the heterogeneity of the results and explore the effects of different methods of ARP. The subgroups will include the following.

  • Type of grafting material (autogenous versus xenograft and allograft versus xenograft).

  • Effect of barrier membrane (use of any type of membrane versus no use of barrier membrane).

  • Site of ARP (molar versus non‐molar).

If an adequate number of studies are available, meta‐regression will be carried out to examine the effects of different variables on the outcome.

Sensitivity analysis

The sensitivity analysis will be conducted to test the influence of the risk of bias of included studies and inclusion of unpublished data on the overall estimates of effect. The robustness of the results will also be evaluated by only including the studies that were considered to have a low risk of bias.

Presentation of main results

A 'Summary of findings' table will be developed for the primary outcomes of this review using GRADEPro software. The quality of the body of evidence will be assessed with reference to the overall risk of bias of the included studies, the directness of the evidence, the inconsistency of the results, the precision of the estimates, the risk of publication bias, the magnitude of the effect and whether or not there is evidence of a dose response. The quality of the body of evidence for each of the primary outcomes will be categorised as high, moderate, low or very low.