No abstract

The introduction of many new packable composites suggests that these products are rapidly gaining popularity. The purpose of this study was to evaluate the in vitro properties of a variety of packable composites and to determine if significant enhancements in physical and mechanical properties have been achieved for these materials compared with two popular nonpackable posterior composites. For the five packable and two regular composites tested (ALERT, Pyramid‐Dentin, Pyramid‐Enamel, Solitaire, SureFil, Heliomolar, and Z100), the values for fracture toughness, flexure strength, flexure modulus, hardness, and volumetric polymerization shrinkage were determined. In general, although the packable composites were of heavier consistency, they had mechanical properties that were intermediate to (ALERT, Pyramid, and SureFil) or lower than (Solitaire) those of the nonpackable materials. These results could have been predicted based on the similar meth‐acrylate resin chemistry and filler volumes of the various composites. No composite had adequate depth‐of‐cure when tested in increments greater than 2 mm thick. Polymerization contraction of the packable composites was similar to or higher than that of the nonpackable composites. In addition, the radiopacity of at least one material, Solitaire, was not considered to be adequate (less than 2 mm of aluminum). The results of this study suggest that these packable composites are unlikely to offer improved clinical performance over well‐placed nonpackable composites. CLINICAL SIGNIFICANCE Packable composites have physical and mechanical properties that are similar to those of nonpackable posterior composites and are, therefore, expected to provide equivalent clinical performance.

No abstract

No abstract

During mineralization, unbound water within the collagen matrix is replaced by apatite. This study tested the null hypothesis that there is no difference in the status of in vitro biomimetic remineralization of hybrid layers irrespective of their moisture contents. Acid-etched dentin was bonded with One-Step using ethanol-wet bonding, water-wet bonding and water-overwet bonding protocols. Composite-dentin slabs were subjected to remineralization for 1–4 months in a medium containing dual biomimetic analogs with set Portland cement as the calcium source and characterized by transmission electron microscopy. Remineralization was either non-existent or restricted to the intrafibrillar mode in ethanol-wet bonded specimens. Extensive intrafibrillar and interfibrillar remineralization were observed in water-wet bonded specimens. Water-overwet specimens demonstrated partial remineralization of hybrid layers and precipitation of mineralized plates within water channels. The use of ethanol-wet bonding substantiates that biomimetic remineralization is a progressive dehydration process that replaces remnant water in hybrid layers with apatite crystallites.