Fixed prosthodontic treatment is a routine dental procedure in which one or more missing or severely damaged teeth are replaced by artificial substitutes. The material used to make the prosthesis may be made of a metal framework with a veneering of an aesthetic material (ceramic) or entirely in metal or it can be made with different non-metal structures (metal-free materials). There is still uncertainty regarding metal-free long-term performance compared to metal-based crowns and bridges.
What was the research?
A systematic review to compare the effects of metal-free materials to metal-ceramic or other conventional all-metal materials for prosthodontic treatments aimed to restore severely damaged teeth or to replace missing teeth.
Who conducted the research?
The research was conducted by a team led by Carlo E Poggio of University of Rochester Eastman Institute for Oral Health, USA, on behalf of Cochrane Oral Health. Carlo Ercoli, Lorena Rispoli, Carlo Maiorana and Marco Esposito were also on the team.
What evidence was included in the review?
We included 9 randomised controlled trials, including 448 participants in which a total of 224 crowns and 132 bridges on natural teeth, and a total of 74 crowns and 25 bridges on implants, were used. Of the nine included trials, three were conducted in Germany, one in Sweden, one in Spain, one in Switzerland and the USA, one in Denmark, one in Italy, and one in Switzerland. All the included trials were single-centre conducted at university dental clinics and had a parallel-group study design. All the included trials received support from industry.
What did the evidence say?
Each trial was addressing a different type of intervention. The studies had durations up to 10 years but included very small numbers of participants and were assessed as at unclear or high risk of bias. Based on these studies, there is currently insufficient reliable evidence to support which of these materials are more effective.
How good was the evidence?
Two trials were at unclear risk of bias and seven were at high risk of bias. The overall quality of evidence was very low, therefore caution should be exercised when generalising the results of the included trials. Future research should aim to provide more reliable information which can help clinicians to decide on appropriate materials for fixed prosthodontic treatment whilst taking into consideration the individual circumstances and preferences of their patients.
What are the implications for dentists and the general public?
Based on the results of the included randomised controlled trials (RCTs), there is insufficient evidence to support or refute the effectiveness of metal-free materials for fixed prosthodontic treatment over metal-ceramic or other type of standard restorations.
What should researchers look at in the future?
Future research should aim to provide more reliable information which can help clinicians to decide on appropriate material for fixed prosthodontic treatment whilst taking into consideration the individual circumstances and preferences of their patients. More well-designed, long-term RCTs are required to understand if metal-free materials have the same in-service clinical performance of conventional metal-based fixed prosthodontic treatments.
Poggio CE, Ercoli C, Rispoli L, Maiorana C, Esposito M. Metal-free materials for fixed prosthodontic restorations. Cochrane Database of Systematic Reviews 2017 , Issue 12 . Art. No.: CD009606. DOI: 10.1002/14651858.CD009606.pub2 .
This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Editorial Base.