What works best to preserve the jaw bone after tooth extraction?

Why is this question important?

Tooth extraction is a common procedure that can be used for example to:

- remove damaged or diseased teeth;
- remove teeth that are in the wrong place; or
- make room for other teeth.

After a tooth extraction, the part of the jaw bone that used to hold the tooth shrinks because it is no longer needed to support the tooth. If the bone shrinks too much, this can:

- make it difficult or impossible to replace the missing tooth with an artificial one (an implant); and
- weaken the support and health of neighbouring teeth.

To limit bone loss after tooth extraction, dentists or surgeons can carry out a procedure called alveolar ridge preservation (ARP). ARP involves filling the hole left by the missing tooth (using a range of different materials and techniques), and leaving it to heal for several months. The hole can be filled with human, animal, or artificial bone. It can be covered over (to stop gums from growing into the hole) using:

- materials that, after some time, are naturally absorbed by the body; or
- materials that need to be removed with surgery once no longer needed.

To find out if ARP works to preserve jaw bone after tooth extraction, we reviewed the evidence from research studies. We also wanted to know if any materials and ARP techniques are better than others.

How did we identify and evaluate the evidence?

First, we searched the medical literature for studies that compared:

- ARP against no ARP; or
- different ARP materials or techniques.

We then compared the results, and summarised the evidence from all the studies. Finally, we rated our confidence in the evidence, based on factors such as study methods and sizes, and the consistency of findings across studies.

What did we find?

We found 16 studies that followed a total of 426 adults for at least six months. The studies took place in North America, South America, Europe, and Asia. Four studies were supported by pharmaceutical and medical device companies. The other studies either received public funding, no specific funding, or did not report funding source.

ARP compared to no ARP

Eight studies compared ARP against no ARP. In seven studies, animal bone was used to fill the hole left by the missing tooth. In one study, the hole was filled with an artificial bone.

Bone loss: evidence from studies suggests that ARP may prevent bone loss after tooth extraction. However, we are not confident about this finding. This is because studies reported conflicting findings and did not report their methods clearly.

Complications: the evidence about complications (such as discomfort or pain) was mixed. One study reported delayed healing in one person following ARP. In another, some people experienced pain and swelling after ARP. Others reported no complications.

Implications for tooth implants: evidence from studies where ARP used animal bones suggests that ARP may make little or no difference to the need to add more bone to the jaw before implants can be inserted. However, we are not confident about this finding. This is because studies reported conflicting findings and did not report their methods clearly.

It is unclear if ARP affects the success of implants, or the appearance of teeth after implantation. This is because too few robust studies have investigated this.

Comparisons between different materials

Eight studies compared the use of different ARP materials (animal bone against artificial bone). In general, these studies did not provide sufficiently robust evidence to determine which materials work best.

Bone loss: there was some evidence to suggest that there may be little or no difference in bone loss between animal bone and artificial bone. However, we are not confident about this finding. This is because studies reported conflicting findings and did not report their methods clearly.

Complications: the evidence about complications was mixed. Some studies reported redness, pain or swelling, but others did not report that any complications had occurred.

Implications for tooth implants: evidence suggests that the material used may make little or no difference to the need to add more bone to the jaw before implants can be inserted. However, we are not confident about this finding. This is because studies reported conflicting findings and did not report their methods clearly.

It is unclear if different ARP materials and methods have different effects on the success of implants, or the appearance of teeth after implantation. This is because too few robust studies have investigated this.

What does this mean?

We do not know what works best to preserve jaw bone after tooth extraction. It is not clear :

- if ARP is better than no ARP; or
- if some ARP materials and techniques are better than others.

This is because the evidence currently available is not sufficiently robust.

Future studies that report their methods clearly and follow people over long periods will help to strengthen the evidence and draw conclusions.

How-up-to date is this review?

The evidence is current to March 2021.

Authors' conclusions: 

ARP techniques may minimise the overall changes in residual ridge height and width six months after extraction but the evidence is very uncertain. There is lack of evidence of any differences in the need for additional augmentation at the time of implant placement, implant failure, aesthetic outcomes, or any other clinical parameters due to lack of information or long-term data. There is no evidence of any clinically significant difference between different grafting materials and barriers used for ARP. Further long-term RCTs that follow CONSORT guidelines (www.consort-statement.org) are necessary.

Read the full abstract...
Background: 

Alveolar bone changes following tooth extraction can compromise prosthodontic rehabilitation. Alveolar ridge preservation (ARP) has been proposed to limit these changes and improve prosthodontic and aesthetic outcomes when implants are used. This is an update of the Cochrane Review first published in 2015.

Objectives: 

To assess the clinical effects of various materials and techniques for ARP after tooth extraction compared with extraction alone or other methods of ARP, or both, in patients requiring dental implant placement following healing of extraction sockets.

Search strategy: 

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 19 March 2021), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2021, Issue 2), MEDLINE Ovid (1946 to 19 March 2021), Embase Ovid (1980 to 19 March 2021), Latin American and Caribbean Health Science Information database (1982 to 19 March 2021), Web of Science Conference Proceedings (1990 to 19 March 2021), Scopus (1966 to 19 March 2021), ProQuest Dissertations and Theses (1861 to 19 March 2021), and OpenGrey (to 19 March 2021). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. A number of journals were also handsearched.

Selection criteria: 

We included all randomised controlled trials (RCTs) on the use of ARP techniques with at least six months of follow-up. Outcome measures were: changes in the bucco-lingual/palatal width of alveolar ridge, changes in the vertical height of the alveolar ridge, complications, the need for additional augmentation prior to implant placement, aesthetic outcomes, implant failure rates, peri-implant marginal bone level changes, changes in probing depths and clinical attachment levels at teeth adjacent to the extraction site, and complications of future prosthodontic rehabilitation.

Data collection and analysis: 

We selected trials, extracted data, and assessed risk of bias in duplicate. Corresponding authors were contacted to obtain missing information. We estimated mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes, with 95% confidence intervals (95% CI). We constructed 'Summary of findings' tables to present the main findings and assessed the certainty of the evidence using GRADE.

Main results: 

We included 16 RCTs conducted worldwide involving a total of 524 extraction sites in 426 adult participants. We assessed four trials as at overall high risk of bias and the remaining trials at unclear risk of bias. Nine new trials were included in this update with six new trials in the category of comparing ARP to extraction alone and three new trials in the category of comparing different grafting materials.

ARP versus extraction: from the seven trials comparing xenografts with extraction alone, there is very low-certainty evidence of a reduction in loss of alveolar ridge width (MD -1.18 mm, 95% CI -1.82 to -0.54; P = 0.0003; 6 studies, 184 participants, 201 extraction sites), and height (MD -1.35 mm, 95% CI -2.00 to -0.70; P < 0.0001; 6 studies, 184 participants, 201 extraction sites) in favour of xenografts, but we found no evidence of a significant difference for the need for additional augmentation (RR 0.68, 95% CI 0.29 to 1.62; P = 0.39; 4 studies, 154 participants, 156 extraction sites; very low-certainty evidence) or in implant failure rate (RR 1.00, 95% CI 0.07 to 14.90; 2 studies, 70 participants/extraction sites; very low-certainty evidence). From the one trial comparing alloplasts versus extraction, there is very low-certainty evidence of a reduction in loss of alveolar ridge height (MD -3.73 mm; 95% CI -4.05 to -3.41; 1 study, 15 participants, 60 extraction sites) in favour of alloplasts. This single trial did not report any other outcomes.

Different grafting materials for ARP: three trials (87 participants/extraction sites) compared allograft versus xenograft, two trials (37 participants, 55 extraction sites) compared alloplast versus xenograft, one trial (20 participants/extraction sites) compared alloplast with and without membrane, one trial (18 participants, 36 extraction sites) compared allograft with and without synthetic cell-binding peptide P-15, and one trial (30 participants/extraction sites) compared alloplast with different particle sizes. The evidence was of very low certainty for most comparisons and insufficient to determine whether there are clinically significant differences between different ARP techniques based on changes in alveolar ridge width and height, the need for additional augmentation prior to implant placement, or implant failure.

We found no trials which evaluated parameters relating to clinical attachment levels, specific aesthetic or prosthodontic outcomes for any of the comparisons.
No serious adverse events were reported with most trials indicating that the procedure was uneventful. Among the complications reported were delayed healing with partial exposure of the buccal plate at suture removal, postoperative pain and swelling, moderate glazing, redness and oedema, membrane exposure and partial loss of grafting material, and fibrous adhesions at the cervical part of previously preserved sockets, for the comparisons xenografts versus extraction, allografts versus xenografts, alloplasts versus xenografts, and alloplasts with and without membrane.

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