Abstract
BackgroundNaïve-indirect comparisons are comparisons between competing clinical interventions’ evidence from separate (uncontrolled) trials. Direct comparisons are comparisons within randomised control trials (RCTs). The objective of this empirical study is to test the null-hypothesis that trends and performance differences inferred from naïve-indirect comparisons and from direct comparisons/RCTs regarding the failure rates of amalgam and direct high-viscosity glass-ionomer cement (HVGIC) restorations in permanent posterior teeth have similar direction and magnitude.MethodsA total of 896 citations were identified through systematic literature search. From these, ten and two uncontrolled clinical longitudinal studies for HVGIC and amalgam, respectively, were included for naïve-indirect comparison and could be matched with three out twenty RCTs. Summary effects sizes were computed as Odds ratios (OR; 95% Confidence intervals) and compared with those from RCTs. Trend directions were inferred from 95% Confidence interval overlaps and direction of point estimates; magnitudes of performance differences were inferred from the median point estimates (OR) with 25% and 75% percentile range, for both types of comparison. Mann-Whitney U test was applied to test for statistically significant differences between point estimates of both comparison types.ResultsTrends and performance differences inferred from naïve-indirect comparison based on evidence from uncontrolled clinical longitudinal studies and from direct comparisons based on RCT evidence are not the same. The distributions of the point estimates differed significantly for both comparison types (Mann–Whitney U = 25, nindirect = 26; ndirect = 8; p = 0.0013, two-tailed).ConclusionThe null-hypothesis was rejected. Trends and performance differences inferred from either comparison between HVGIC and amalgam restorations failure rates in permanent posterior teeth are not the same. It is recommended that clinical practice guidance regarding HVGICs should rest on direct comparisons via RCTs and not on naïve-indirect comparisons based on uncontrolled longitudinal studies in order to avoid inflation of effect estimates.
Highlights
The term ‘high-viscosity’ or ‘high-viscous glass-ionomer cement’ (HVGIC) has emerged within the scientific dental literature: A simple search conducted in PubMed/Medline (25.09.2012) with the string of search terms: "high-viscosity glass ionomer cement" Odds ratios (OR) "high-viscous glass ionomer cement" revealed 16 citations of articles, published between 2003 – 2011, of which five articles referred to the term in their titles and all articles in their listed abstracts and related it to the products Fuji IX (GC Corporation, Japan) or Ketac Molar (3M ESPE, Germany).high-viscosity glassionomer cement (HVGIC) appear distinct from other viscosity glass-ionomer cements (GICs) in their comparative survival rate to that of conventional amalgam restorations
The distributions of the point estimates differed significantly for both comparison types (Mann–Whitney U = 25, nindirect = 26; ndirect = 8; p = 0.0013, two-tailed).These results indicate that trends and performance differences inferred from naıve-indirect comparison based on evidence from uncontrolled clinical longitudinal studies and from direct comparisons based on randomised control trials (RCTs) evidence do not have the same direction and magnitude
The objective was to test the null-hypothesis that trends and performance differences inferred from naıve-indirect comparison based on evidence from uncontrolled clinical longitudinal studies and from direct comparisons based on RCT evidence have similar directions and magnitude
Summary
The term ‘high-viscosity’ or ‘high-viscous glass-ionomer cement’ (HVGIC) has emerged within the scientific dental literature: A simple search conducted in PubMed/Medline (25.09.2012) with the string of search terms: "high-viscosity glass ionomer cement" OR "high-viscous glass ionomer cement" revealed 16 citations of articles, published between 2003 – 2011, of which five articles referred to the term in their titles and all articles in their listed abstracts and related it to the products Fuji IX (GC Corporation, Japan) or Ketac Molar (3M ESPE, Germany).HVGICs appear distinct from other (low) viscosity GICs (including Cermets) in their comparative survival rate to that of conventional amalgam restorations. The results of a meta-analysis found a survival rate for HVGIC (Fuji IX; Ketac Molar) similar to that of amalgam but showed significantly lower survival rates for ‘‘low-viscosity’’ GICs (Chelon Silver ( = Cermet); Chem Fil; Fuji II) than for amalgam [1]. Glass ionomer cements, such as HVGICs, adhere primarily via calcium bonds to the mineral content of the tooth structure [2]. Direct comparisons are comparisons within randomised control trials (RCTs) The objective of this empirical study is to test the null-hypothesis that trends and performance differences inferred from naıve-indirect comparisons and from direct comparisons/RCTs regarding the failure rates of amalgam and direct high-viscosity glassionomer cement (HVGIC) restorations in permanent posterior teeth have similar direction and magnitude
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