No abstract

This second part (Part II) of a two-part comprehensive review of bioactive and biomimetic restorative materials reviews the calcium aluminate-based restorative dental materials. Part II explores the development, composition, properties, and application of the bioactive calcium aluminate-based materials that have been developed for several indications in restorative dentistry. CLINICAL SIGNIFICANCEBioactive materials have evolved over the past three decades from relatively specialized, highly biocompatible, but low-strength dental materials to now emerge in product compositions for expanded clinical uses in restorative dentistry. Further developments to meet additional restorative clinical needs are anticipated in the newly emerging category of dental materials. (J Esthet Restor Dent 26:27-39, 2014) CALCIUM ALUMINATE CEMENTS Similar to the calcium silicate cements (CSCs), the calcium aluminate cements (CAC) are also derived from the class of cements called "hydraulic" or natural cements. Their hydrating solution is water with 30 to 90 ppm lithium to accelerate the hardening process. A typical CAC contains prereacted constituents as follows: Al2O3 = 43%; CaO = 19%; H2O = 15%; ZrO2 = 19% (silicon, iron, magnesium, titanium, and alkali oxides less than 10%). The calcium aluminate undergoes very rapid hydration with a setting reaction at a pH of 11.4 to 12.5 and the formation of the reaction products Katoite and Gibbsite. Mechanistically, water dissolves the calcium aluminate powder with the subsequent formation of calcium ions calcium ions (Ca 2+ ), aluminum hydroxyl ions (Al(OH)4 -, and hydroxyl ions (OH -). This activity is then followed almost immediately by precipitation of new solid phases (Katoite and Gibbsite) as the solution reaches saturation. These precipitates grow until they meet, and a connected cluster of hydroxide particles is formed continually. Crystallization of the phases proceeds and the hydrates grow in size from nanometers (nm) to microns (μm). This segment is the second part (Part II) of a two-part comprehensive review of bioactive and biomimetic restorative materials. Part I considered the calciumsilicate-based dental materials. Part II will now review the calcium aluminate-based restorative dental materials.

Selection of appropriate finishing and polishing devices is critical to the optimal appearance and longevity of composite resin restoratives. This report compares the effectiveness of three specific finishing and polishing systems when used to prepare the surfaces of composite restorative materials provided by the respective manufacturers. Profilometer surface roughness analyses were conducted at two separate laboratories to cross‐correlate numerical smoothness data in this study. Statistically significant differences in mean surface roughness were found between various finishing system/composite resin pairings. Surprisingly, a hybrid composite resin finished and polished with its respective finishing/polishing system gave a significantly smoother surface than a microfill composite surface prepared with its corresponding sequentially coated abrasive disc system. This finding was corroborated at a second site using a separate methodology for profilometer analysis.

Two-year recall data yielded no loss of retention, no secondary caries, no marginal discolorations, and no subjective sensitivity. All restorations rated "alpha" for marginal integrity at the 2-year recall. After periodic recalls up to 2 years, the new bioactive cement tested thus far has performed favorably as a luting agent for permanent cementation.

No abstract