July/August 2009, Volume 5, Issue 7
Published by AEGIS Communications
Clinical Evaluation of N’Durance Nano-dimer Conversion Technology Dental Composite
Howard E. Strassler, DMD
Ritter H, Lee SS. J Dent Res. 2009;89(Special Issue IADR abstracts): Abstract 1006.
Objective: To evaluate the clinical performance of this material as an anterior restorative.
Materials and Methods: Opti-Bond Solo total-etch (Kerr, Orange, CA) was used as the dental adhesive. Class III, IV, V, incisal edge repairs, diastema closures and direct veneer restorations were placed in anterior teeth. With the IRB approval, a total of 40 restorations were placed in 23 patients. Restorations were evaluated at two-week baseline period, 6 months and 1 year, and are planned to be recalled at 18 month and 2 years, with an optional evaluation at 3 and 4 years. Restorations were evaluated for the following variables: Anatomic Form (AF), Color Match (CM), Marginal Adaptation (MA), Marginal Discoloration (MD), Surface Staining (SS), Retention (RT), Secondary Caries (SC), Fracture (FX) and Polishability (PL) using a modified USPHS evaluation system.
Results: Results at one year indicated that all restorations had excellent anatomic form, marginal adaptation, marginal discoloration, surface staining, retention, and secondary caries. None of the patients exhibited postoperative sensitivity or exaggerated gingival response. In general, all the restorations were initially judged to be clinically satisfactory.
Conclusions: The N’durance composite produces good clinical results for anterior restorations at the one year evaluation with no postoperative sensitivity or gingival irritation.
In 1962, Dr. Raphael Bowen at the American Dental Association’s research laboratory at the National Bureau of Standards (now the American Dental Association Health Foundation at the National Institute of Standards) patented the polymer chemistry Bis-GMA (bisphenol A glycidal methacrylate) using a silane coupling agent to chemically bond silicate-based glass fillers to the resin matrix. This chemistry is used in almost all current composite resins that we place in our clinical practices. In another 3 years it will be that patent’s 50th anniversary. The composite resins have improved over the years with the changes in filler particles from macroparticles (25 µm to 50 µm in diameter) to our current nanofillers approximately 0.4 µm in diameter. Today’s composites are more wear resistant and have better physical properties. But it is still the same chemistry with the same problems with poor conversion of the dimethacrylate monomers into polymers, polymerization shrinkage, shrinkage stresses, water solubility, and alcohol solubility. While there has been significant research investigating the substitution with different polymer chemistries for Bis-GMA, many have produced an acceptablecomposite to restore teeth.
This well-designed clinical research study investigated the clinical performance of a significantly different chemistry for composite resins using dimer-acid chemistry developed and patented at the University of Colorado. This high double-bond conversion (75% conversion compared to 60% of traditional composites), low shrinkage, low water absorption, light-activated composite provides for low wear with increased radiopacity using optimized nanofillers. The reduction in polymerization shrinkage is derived from a phase separation that compensates for resin shrinkage during polymerization. Physical property testing can be a predictor for how a composite resin will perform. When reviewing the 1-year clinical data for this new chemistry, the results are very promising.
About the Author
Howard E. Strassler, DMD
Professor and Director of Operative Dentistry
Department of Endodontics
Prosthodontics and Operative Dentistry
University of Maryland Dental School