Missing teeth can sometimes be replaced with crowns, bridges or dentures, which may be attached to dental implants. Many different types of implant exist; more than 1,300 are available in different materials, shapes, sizes and with different surface characteristics or coatings. This newly updated review on the Cochrane Library compares the different types of implant, in terms of how often they fail and have to be removed. Failure could be biological and caused by bone loss or infection; or mechanical, where the implant itself fractures.
What was the research?
A systematic review of the evidence to compare the clinical effects of implant types for replacing missing teeth.
Who conducted the research?
The research was conducted by a team led by Marco Esposito, on behalf of the Cochrane Oral Health Group. Yasmin Ardebili and Helen V. Worthington were also on the team.
What evidence was included in the review?
Data was extracted from 27 randomised controlled trials. The trials were based in a wide range of countries, six in Italy, five in New Zealand, five in Sweden, three in the Netherlands, two in Korea, one in Turkey, one in Germany, one in Switzerland and three multicentre European trials. There were comparisons made of 38 implant types, with different surface characteristics, shapes, and materials. The main outcome considered by the trials was the failure of the implant to work.
What did the evidence say?
The review found that there was not enough evidence from trials to demonstrate the superiority of any particular type of implant characteristic or implant system over another. There was no evidence showing that any particular type of dental implant had greater long-term success. There was limited evidence showing that implants with relatively smooth surfaces were less prone to lose bone due to chronic infections (peri-implantitis) than implants with much rougher surfaces. However, the evidence also suggests they may fail earlier than implants with roughened surfaces.
How good was the evidence?
Two trials were at low risk of bias, and 15 were at high risk. For 10 of the trials, there wasn’t enough information available to decide on the quality of the evidence. Most of the trials were underpowered, which means that there were not enough participants in the studies to be able to draw firm conclusions.
What are the implications for dentists and the general public?
There was limited evidence showing that implants with relatively smooth (turned) surfaces are less prone to fail due to chronic infection than implants with much rougher surfaces (titanium plasma sprayed). These findings were based on several RCTs, often at high risk of bias, with few participants and relatively short follow up periods.
What should researchers look at in the future?
More well-designed, long term trials are required to understand if there is any design, surface modification or material able to improve the effectiveness of oral implants significantly. It is recommended that any randomized controlled trials in future include:
- test and control implants, placed in the same way if possible.
- a sufficient number of participants to disclose a true difference, if any
- a sufficient duration (they should last for 5 years or more).
Esposito M, Ardebili Y, Worthington HV. Interventions for replacing missing teeth: different types of dental implants. Cochrane Database of Systematic Reviews 2014, Issue 7. Art. No.: CD003815. DOI: 10.1002/14651858.CD003815.pub4.