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Atraumatic/Alternative restorative treatment (ART) and interim therapeutic restoration (ITR) have been developed as a part of minimally invasive dentistry (MID) where demineralized tooth tissues are removed using hand instruments and the cavity is restored with glass ionomer cements (GICs). However, dental hand instruments alone do not remove carious dentin as effectively as rotary burs, and cariogenic bacteria can survive under GIC restorations causing their failure. Several attempts in developing antibacterial GICs have been reported in the literature. The most appropriate choice of antibacterial agents to combine with GIC would be those providing the maximum antibacterial effect without disturbing its main physical and mechanical properties.
Accordingly; this study was conducted to assess three physical and mechanical properties (primary and permanent enamel shear bond strength (SBS), water sorption and solubility) of two high viscous glass ionomer formulations containing cetrimide (CT) versus lyophilized Salvadora persica extract (SPE), 1% w/w each, as antibacterial additives.
SBS test involved 21 primary and 21 permanent prepared enamel specimens. Primary molar specimens were randomly and equally divided into 3 groups according to the materials used (n = 7 each). Permanent specimens were also divided into 3 similar groups in the same manner. Primary and permanent SBS was then evaluated using a Universal Testing Machine at a crosshead speed of 0.5mm/min. The debonded primary and permanent enamel surfaces of each group were evaluated to assess the failure mode using a stereomicroscope.
Three groups, according to material type, were used for water sorption and solubility testing. Based on the norms of the international organization for standardization (ISO), preparation of 5 disk specimens in each group was required for testing. Specimens were first desiccated until a constant mass was obtained. Specimens were immersed for 7 days in distilled water and immediately weighted after this period. Then the disks were post-desiccated and re-weighted daily till reaching a constant mass. Water sorption and solubility of each specimen were then calculated according to the change in its weight as observed before and after immersion and desiccation periods.
Numerical and qualitative data for SBS, water sorption and solubility tests in different groups were tabulated and statistically analyzed. Statistical analysis was carried out using SPSS program (Statistical Package for the Social Sciences, 2008).
Results revealed significant high SBS values of miswak (MW) containing HVGIC to primary enamel. However; CT containing HVGIC showed a statistically significant increase in permanent enamel SBS values. On comparing SBS to primary versus permanent enamel within each of the three materials; only MW containing HVGIC revealed a statistically significant increase in primary enamel SBS in relation to permanent enamel.
Fractology analysis revealed no statistically significant difference in mode of failure in primary teeth between different groups, where the failure mode was predominantly “mixed”. Regarding permanent teeth; 100% of the control group failure mode was mixed however; a high percentage of cohesive failure was recorded in the test groups that was significantly different from the control indicating stronger bonds. On comparing primary versus permanent modes of failure within each material; there was no statistically significant difference except for the CT experimental formulation where the predominant primary fracture mode was mixed in comparison with the predominant cohesive mode of failure in permanent teeth.
Regarding water sorption and solubility levels; no statistically significant difference was recorded in both water based properties in different groups indicating that the addition of either CT powder or lyophilized SPE to HVGIC didn’t affect water sorption and solubility of the set cement. Sperman correlation coefficient revealed no statistical correlation between water sorption and solubility in the three groups.