Systematic review on highly viscous glass-ionomer cement/resin coating restorations (Part I): 
Do they merge Minamata Convention and minimum intervention dentistry?

BACKGROUND: With the Minamata Convention the use of mercury will be phased down, and this undoubtedly will have an effect on dental treatment regimens and economic resources. Composite resin restorations are considered viable alternatives to amalgam fillings; however, these will not be covered completely by health insurance systems in many countries. Recently, a high-viscosity glass-ionomer cement (hvGIC) processed with a resinous coating (RC) has been introduced, and has been marketed as a restorative material in load-bearing Class I cavities (and in Class II cavities with limited size), thus serving as a possible alternative to amalgam fillings.

OBJECTIVE: To evaluate the literature on this treatment approach, and to focus particularly on the clinical performance of the hvGIC/RC combination.

SEARCH STRATEGY: The Cochrane Library as well as Ebsco, Embase, PubMed, and Scopus databases were screened. Moreover, relevant abstracts published with dental meetings were reviewed.

SELECTION CRITERIA: All available randomized clinical trials focusing on the hvGIC/RC approach (published either as full-texts or abstracts until June 2016) were selected. Moreover, single-group studies using hvGIC/RC were included.

DATA COLLECTION AND ANALYSIS: Screening of titles and abstracts, data extraction, and quality assessments of full-texts according to Oxford scoring were performed.

RESULTS: Regarding failure rates, minor differences between hvGIC/RC and GIC or composite resins as comparators could be observed in seven clinical studies. The hvGIC/RC combination showed high survival rates (with only few catastrophic failures) of up to 6 years.

CONCLUSION: Class I retention rates of hvGIC/RC seem promising, but further high-quality clinical studies are clearly warranted.