Experimental dental cement: Mechanical properties and fluoride released

Objective: The purpose of this study was to develop polycarboxylate cement through the neutralization reaction of poli(acrylic acid) with cobalt fluorides in presence of metallic oxides.

Methods: Acrylic acid (J.T. Baker), ammonium persulfate (J.T. Baker), isopropílic alcohol (J.T. Baker) and deionized water were used to obtain poly (acrylic acid) (PAA). The reactives were placed in a glass reactor (70°C+5°C) with constant stirring in nitrogen atmosphere; molecular weights were calculated through relative viscosity determinations. The PAA, cobalt fluoride III (CoF3) (J.T. Baker), cobalt fluoride II (CoF2) (Aldrich) and filling material sinterized in Dental Materials Laboratory (DEPeI, F.O. UNAM) were used to prepare the cobalt polycarboxilate. Working and setting time, compressive strength and acid erosion were measured according to 96 ADA. For determination of fluoride released, the specimens were stored in deionized water and 24h later the measure of fluoride released were carried out using a fluoride selective electrode (Orion) and ion-analyzer (Oakton), this measurements were repeated for 10 days.

Results: PAA viscosity molecular weights were 40,000 and 8,000 g/mol. The results of working and setting time, compressive strength and acid erosion were analyzed with One way ANOVA and showed significant differences (p<0.001). For the fluoride released test the highest release results were obtained with CoF3 mixed with PAA 8000g/mol and filling material.

Conclusions: The closest values to the established on the specification were obtained by PAA 40,000 g/mol, CoF2 and filling material sinterized and the highest release results were obtained with the CoF3 and PAA 8000g/mol mix.