Bruxism: Is the implant failure risk real?

A recent systematic review states that bruxism may contribute to implant and implant-supported prosthetic failures.

Bruxism is the grinding or clenching of teeth. It can damage teeth structures, leading to the failure/fracture of dental restorations and tooth wear.

Bruxism has two distinct circadian phenomena: sleep bruxism and awake bruxism. These two are not considered a disorder for healthy patients but risk factors for negative outcomes.

Osseointegrated dental implants are rigidly attached to the bone, unlike the tooth-periodontium interface, they cannot adapt reversibly to different loading conditions. Implants are therefore negatively impacted by bruxism.

A systematic search in PubMed was performed with the time range from 2010-2021. Out of 343 articles, only 16 studies were included and were divided into three groups. Group one assessed implant complications, group two determined prosthetic complications, and group three reported both.

The findings from earlier studies on this topic were controversial.  Moreover, only two systematic reviews were conducted on this topic (2014 and 2015), and both of them were inconclusive. This review, however, is based on observational studies, as there have been no randomized or non-randomized clinical trials.  The authors were compelled to choose retrospective protocols based on the systematic review guidelines.

Using the criterion studies for grouping the participants (implant, prosthesis, or both) helped close the gap between the studies, reducing protocol differences and resulting in a large homogenized group.

It was only the bruxism diagnosis that broke the homogeneity.  The literature describes a variety of approaches to bruxism diagnosis.  Bruxism is typically diagnosed by one of three approaches: self-report, clinical examination, and questionnaire to establish the probable cause of bruxism, and finally polysomnography (the most effective method to confirm bruxism).

Studies with unclear or negative results mostly assess either self-reported bruxism or unclear bruxism diagnosis.  This can explain negative results by including non-bruxors in the bruxism group.

Recent studies have found that dental attrition alone cannot diagnose bruxism, as it has multiple causes. In addition, some studies revealed that in bruxors, implants have increased marginal bone loss, mobility, and failure rates. In all the studies, however, bruxism was related and found to be a risk factor for mechanical complications of implant-supported rehabilitation, with a greater incidence of chipping, fractures, and wear among patients with bruxism than patients without.

Summary and conclusion

Almost all of the studies showed a positive correlation between bruxism and implant failure, with bruxors having a 2.45 to 3.6 times greater risk of implant failure.

All the studies showed a positive correlation between bruxism, implant failure, and prosthetic complications with an odds ratio of 2.71.

Three studies showed a positive relationship between bruxism and mechanical complications with 3.6 times more complications in bruxors.

In light of the above, bruxism can be regarded as a risk factor for implant survival, and as a mechanical risk for implant-supported rehabilitations. These findings are in agreement with the results of an earlier meta-analysis (2016).

A clear and evident diagnosis of bruxism, standardized measurement units, and an appropriate protocol would be of value to future research.