Conclusion The current evidence suggests lack of support for the hypothesis that high-viscosity glass-ionomer cements are inferior to silver amalgam as restorative material s for permanent posterior teeth .
Background To develop a synthesis within a Bayesian probability framework of previously established evidence , in order to derive an overall conclusion about the hypothesis ( H1 ) : ‘ High-viscosity glass-ionomer cements ( HVGIC ) are inferior to silver amalgam as ( load bearing ) restorative material s for permanent posterior teeth ’ .
Direct Contra Naïve-Indirect Comparison of Clinical Failure Rates between High-Viscosity GIC and Conventional Amalgam Restorations: An Empirical Study
Background Naïve-indirect comparisons are comparisons between competing clinical interventions ’ evidence from separate ( uncontrolled ) trials . Direct comparisons are comparisons within r and omised 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 . Methods A 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 . Results Trends 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 ) . Conclusion The 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
Conclusion The current evidence suggests lack of support for the hypothesis that high-viscosity glass-ionomer cements are inferior to silver amalgam as restorative material s for permanent posterior teeth .
Background To develop a synthesis within a Bayesian probability framework of previously established evidence , in order to derive an overall conclusion about the hypothesis ( H1 ) : ‘ High-viscosity glass-ionomer cements ( HVGIC ) are inferior to silver amalgam as ( load bearing ) restorative material s for permanent posterior teeth ’ .