With the vast possibilities of restorative dentistry nowadays and the constant development and release of restorative materials with improved mechanical and esthetical properties, there is a growing body of research on adhesive systems and cementation materials, as well as the adequate choices thereof in everyday clinical practice. There are high demands from the dental cements with regard to their adhesion to various substrates and restorative materials, their mechanical properties, resistance to dissolution in the oral environment, esthetic considerations, etc. A material that meets all these requirements is not yet available, and each available material presents certain shortcomings. However, thanks to the advancements in dental material research, polymers-based cements have gained admirable mechanical and esthetic properties, as well as versatility. With the plethora of products available on the market, clinicians are often faced with difficulties in the choice of a material adequate for certain clinical situations. Indeed, important factors to consider are the substrate for cementation and the restoration material. The aim of this review was to provide clear and literature-based clinical recommendations for the adequate cementation of prosthodontic restorations with regard to the cementation substrate. Considering that there is no gold standard protocol applicable in all clinical cases, since the properties of the cementation abutment could substantially differ, important individual considerations must be made for each situation.

This study aimed to investigate matrix metalloproteinase (MMP) activity in human dentin using in-situ and gelatin zymography, after at-home and in-office bleaching, related to their clinical exposure times. Dentin specimens (n = 5) were treated with 35% hydrogen peroxide (50 min per session/4 sessions), 10% carbamide peroxide (180 min/21 sessions), or no treatment. All were subjected to in-situ zymography. Dentin slices were, subsequently, obtained, covered with fluorescein-conjugated gelatin, and examined with confocal laser-scanning microscopy. The fluorescence intensity was quantified and statistically analyzed using one-way ANOVA and Bonferroni tests (α = 0.05). Furthermore, gelatin zymography was performed on protein extracts obtained from dentin powder (N = 8 teeth), treated with hydrogen peroxide or carbamide peroxide, with different exposure times (10/50 min for hydrogen peroxide; 252/1260 min for carbamide peroxide). The results of the in-situ zymography showed no statistical differences between the bleached specimens and the control group, with a medium level of gelatinolytic activity expressed in the dentin tubules. The results of gelatin zymography showed an increased expression of pro-MMP-9 in carbamide peroxide groups. The expression of pro-MMP-2 decreased in all the experimental groups. The bleaching treatments performed on the enamel of sound teeth do not influence dentinal enzymatic activity. However, when unprotected dentin tissue is bleached, matrix metalloproteinases are more expressed, particularly when carbamide peroxide is used, proportional to the exposure time.