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Associated Topics

Insufficient evidence for the turning of the screw

Cynthia Trajtenberg DDS; Leonard Shapiro DMD, MS .


Systematic Review Conclusion

In well-maintained patients, teeth had a higher survival rate than implants. Longevity comparisons were difficult to make because of heterogeneity factors between studies.

Critical Summary Assessment

Despite the heterogeneity between teeth and implant studies, the survival rate of natural teeth appears to be greater than dental implants in well maintained patients.

Evidence Quality Rating

Limited Evidence

Structured Abstract

Clinical Questions:

a. what is the incidence of tooth and implant loss? b. what are the osseous crest level changes around teeth and endosseous implants?

Review Methods:

A comprehensive search yielded 70 potentially relevant publications on natural teeth and 52 on implants. Of these publications, 11 of them met the inclusion criteria for natural teeth and 9 of them for implants. These studies reported totals of 3015 and 476 subjects respectively, with a follow-up of at least 10 years and less than a 30% dropout rate.

Main Results:

The incidence of tooth loss among subjects with a follow-up period of 10 to 30 years varied from 1.3% to 5% in a majority of the studies. The incidence of tooth loss in 2 studies on rural Chinese populations was 14% and 20%. The incidence of implant loss varied between 1% and 18%. 10-year osseous crest rate loss ranged between 0.2 mm and 0.8 mm for natural teeth and 0.7 mm to 1.3 mm for implants.


In clinically well-maintained patients, teeth had a lower loss rate than implants. Osseous crest loss was minimal in both populations in the well-maintained patient. Valid comparisons for longevity were not possible due to the heterogeneity between the studies.

Source of Funding:

No source of funding was disclosed.


Importance and Context:

In order to support restorative treatment of natural teeth there must at least be a perceived difference between the longevity of the natural tooth when compared with the implant.

Strengths and Weaknesses of the Systematic Review:

A comprehensive review was conducted for a specific question with specific inclusion and exclusion criteria. However, a valid comparison was not possible due to the heterogeneity of the studies. Valid comparisons were difficult to make because study populations were diverse, ranging from a well-maintained population to rural and institutionalized groups not receiving maintenance care. The combined sample size of the implant group was smaller. Of the implant systems reported--- Endopore, Branemark, ITI, IMZ, and Astra ( n=486 ) the majority ( n=369 ) were of the Branemark and ITI systems with most of the implant failures reported occurring in with these two systems. Currently neither of these specific systems is in general clinical use.

Strengths and Weaknesses of the Evidence:

A comprehensive literature search that was limited to English language literature included only 1 electronic database (Pubmed). Key words and MESH terms were stated. However, the search strategy was not provided. Reports from the grey literature were not included. Inclusion criteria for the 11 natural teeth and 9 implant studies were stated clearly. The authors cited a list of exclusion criteria that included studies with less than a 70% follow-up period, and studies that had retrospective design and regenerative therapy before implant placement. Reported causes of tooth loss included caries, periodontal involvement, endodontic involvement and tooth fracture. The scientific quality of included studies was assessed a priori. In addition, the authors considered only prospective cohort studies with follow-up periods of at least 10 years. Also, they only considered studies with a dropout rate less than 30%.

Implications for Dental Practice:

In the studies reported, the survival rate of natural teeth was greater than that of implants. However, the results are questionable because of the heterogeneity among the cited studies. Also, 2 of the implant systems that the search referenced are no longer in general clinical use. With this as a caveat, given the favorable prognosis for both the natural tooth and the implant in the well maintained dentition the clinician has valid options for restoring form and function.

Critical Summary Publication Date:


These summaries are not intended to, and do not, express, imply, or summarize standards of care, but rather provide a concise reference for dentists to aid in understanding and applying evidence from the referenced systematic review in making clinically sound decisions as guided by their clinical judgment and by patient needs. American Dental Association © 2019