Aim: To evaluate the remineralization potential presented by surface metrology, of two remineralizing agents: CPP-ACPF (MI paste plus) and fluoride containing mouthwash (Aquafresh extra care mouthwash) on the induced acid erosion bovine enamel. Materials and Methods: Ten freshly extracted bovine permanent incisors were selected. The incisal one third of their crowns were sectioned by a slow speed diamond disc. The labial surface of each sample was examined under atomic force microscope (AFM) to record its surface roughness (Ra values). All samples were then demineralized by citric acid solution and reexamined under AFM .The demineralized samples were randomly divided into two equal groups I and II (5 samples each), according to the remineralization regimen used; samples in group I were treated with MI Paste plus while those in group II were treated with Aquafresh extra care mouthwash. All samples were reexamined under AFM to evaluate Ra values. Results: Acid erosion showed an increase of surface roughness value (72.85 nm) compared to that recorded for the original surface (38.45 nm). After remineralization, there was a decrease of the mean Ra value in group I (52.78nm) and group II (59.54 nm). ANOVA test revealed a statistical significant difference among base line data (original enamel surface), demineralized and remineralized samples in both groups. Scheffe`s test revealed a statistical significant difference between mean Ra value of demineralized samples versus that of base line data as well as that of remineralized samples in both groups. Conclusion: The tested CPP-ACP based compound offered a significant remineralization potential of initially eroded bovine enamel compared to the tested fluoride containing mouthwash as detected by reduced surface roughness.

Aim: To evaluate the effect of hydro abrasion versus the conventional drill method of cavity preparation on the clinical performance of composite restoration over one year follow up period. Materials and methods:Twenty patients with occlusal carious lesions were selected and examined with DIAGNO cam and ICDAS visual criteria to select teeth having ICDAS Code 3 or 4. Forty lesions were randomly divided into two groups (n=20) according to the method of caries removal. Cavities were prepared by the conventional drill method in group I and by hydro-abrasion in group II. Cavities of both groups were restored by self-etch adhesive (Adper Easy Bond) and nano-filled composite (Filtek Z350XT). All restorations were evaluated after 24 hours, after 9 and 12 months according to (USPHS) criteria for retention, marginal adaptation, postoperative sensitivity, marginal discoloration, and secondary caries.Results: Mild, moderate -severe and very severe pain was recorded in group I While in group II, only mild pain was recorded in (40%) of cases. The statistical analysis of the collected data related to the tested USPHS criteria revealed 100% Alpha scoring regarding retention, marginal adaptation and secondary caries in both groups throughout the study period. The gap width measured under SEM was found increased sig. by time in both groups. Marginal discoloration was observed in the two groups after nine and 12 months. Post-operative hypersensitivity was found only in group I in 100% of cases at the base line and was disappeared during the next follow up period. Conclusion:Hydro-abrasion could be recommended as a preferred method of cavity preparation in shallow to mild carious lesions compared to the conventional cavity preparation method.