15-Year Pattern of Clinical Research Trials for Packable-Condensable Posterior Composites

Introduction:  Packable-condensable composites (PCC's) were the first generation of materials intended as true amalgam-replacement materials for posterior teeth.  Posterior composite failure/success is best tested with high-risk trial designs (first molars, Class II, large restorations, long trials, high caries-risk patients). 

Objective: Examine the 15-year life-cycle of PCC's and characterize the pattern of research designs (design type, trial length) for high-risk testing.

Methods:  All references to PCC's were identified within the IADR meeting abstract database (2001-2013, www.dentalresearch.org, n=30) and in Medline (1999-2013, www.ncbi.nlm.nih.gov/pubmed, n=24).  Trials were excluded for packable glass ionomers and/or <1Y recalls.  Related recall reports from the original pool of 54 items were collected into 32 individual trials distributed within 11 countries.  Results were qualitatively analyzed for dominant risk features.

Results:  Baseline designs included from 20 to >500 restorations.  Despite the interest in high-risk trials, designs did not assess caries risk, did include Class-I types, and involved substantially more than first molar posterior restorations.  Trial designs involved no randomized-controlled (RCT=0%, e.g., amalgam controls), 13 standard-controlled (SCT=41%, no controls), and 19 controlled-clinical trials (CCT=59%, other product controls).  Trial lengths were short (1-to-2.5y, n=18; 3-to-5y, n=11; 6-to-10y, n=3).  Results were positive for almost all materials except Solitaire-1.  SureFil testing dominated, involved the most citations, and included the longest trial. 

Conclusion:   Despite strong interest in challenges for true amalgam-replacement materials, clinical research trials have been short (2.8y) and not truly focused on high-risk designs.