Recaldent is a product of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). The remineralizing potential of CPP-ACP per se, or when combined with 0.22% Fl gel on artificially demineralized enamel using laser florescence, is investigated. Mesial surfaces of 15 sound human molars are tested using a He-Cd laser beam at 441.5 nm with 18-mW power as an excitation source on a suitable setup based on a Spex 750-M monochromator provided with a photomultiplier tube (PMT) for detection of collected autofluorescence from sound enamel. Mesial surfaces are subjected to demineralization for ten days. The spectra from demineralized enamel are measured. Teeth are divided into three groups according to the remineralizing regimen: group 1 Recaldent per se, group 2 Recaldent combined with fluoride gel and ACP, and group 3 artificial saliva as a positive control. After following these protocols for three weeks, the spectra from the remineralized enamel are measured. The spectra of enamel autofluorescence are recorded and normalized to peak intensity at about 540 nm to compare spectra from sound, demineralized, and remineralized enamel surfaces. A slight red shift occurred in spectra from demineralized enamel, while a blue shift may occur in remineralized enamel. Group 2 shows the highest remineralizing potential. Combining fluoride and ACP with CPP-ACP can give a synergistic effect on enamel remineralization.

Objectives:The objective of the study was to evaluate fluoride release and water sorption of three flowable esthetic restorative materials: a giomer, a fluoride-releasing resin composite, and a nonfluoridated resin composite.Materials and Methods:Ten samples from a giomer, a fluoride releasing nano-hybrid, and a nonfluoridated nano-hybrid composite were prepared and immersed in deionized water. Fluoride measurements were done using an ion-specific electrode attached to a microprocessor-based fluoride meter after 1 day, 1 week, and 4 weeks. Another thirty samples were made and placed in desiccators. Water sorption was calculated by weighing the specimens before and after water immersion for 1 day, 1 week, and 4 weeks. Data analysis was done using two-way ANOVA, paired t-test (P < 0.05), and Pearson's correlation coefficient to calculate correlations between fluoride release and water sorption.Results:The highest fluoride release was from giomer after 1 day, it was statistically significant from all other groups. Both nano-hybrid composites after 1 day showed significantly lower water sorption which was different than all the other groups. Pearson's correlation showed no significant correlations between fluoride release and water sorption.Conclusions:Fluoride release is material and time dependent, while water sorption is material dependent.

A high-intensity LED LCU used for 10 seconds resulted in RH values greater than 80%, with all four restoratives tested indicating a sufficient degree of monomer conversion with such a short curing cycle.

To evaluate the effect of staining and bleaching on color and translucency of finished and unfinished nano-filled resin composite and giomer. Twenty specimens (ten finished + ten unfinished) were fabricated from each material, then an initial color and translucency measurement was taken. Specimens were stained in coffee for 48 h at 37 °C, rinsed and dried. After which the second color and translucency measurement was taken. After in-office bleaching with 40% HO Opalescence boost, a third color and translucency measurement was taken. CIE system was used for measuring color change and translucency. Two-way ANOVA and paired-test were used for statistical analysis at P ≤ 0.05. After staining, all specimens showed clinically acceptable color change ( ≤ 3.3) with no significant differences between groups. After bleaching, all specimens showed clinically unacceptable color change ( > 3.3) and significant differences between finished & polished and unfinished groups (P = 0.024). Nano-composites recorded significantly higher translucency than giomer (P = 0.000) except after bleaching. In addition, the translucency of unfinished groups were significantly higher than finished & polished groups (P = 0.001). The tested materials responded similarly to staining and bleaching. High concentration bleaching increased color change and reduced translucency. Finishing& polishing restorative materials improves their resistance to color change after bleaching, but it adversely affects translucency.

SUMMARYObjective: The current study aimed to determine the effect of preheating resin composite to three different temperatures on the cuspal movement and gap formation at the tooth/restoration interface. Methods: Fifty extracted, sound human upper premolars were subjected to standardized MOD cavity preparations. Five groups of 10 premolars each were restored with either 1) Tetric Ceram HB, 2) a layer of Tetric Flow followed by Tetric Ceram HB, 3-5) preheated composite to 37°C, 54°C and 68°C, respectively, using a chairside preheating device (Calset thermal assist unit). Cuspal movement was calculated by measuring the intercuspal distance between the indexed cusp tips before restoration 5 minutes and 24 hours after composite curing using a stereomicroscope. The teeth were sectioned longitudinally and examined under a stereomicroscope connected to a digital camera and image analysis software to detect gap formation. Results: Group 2 showed the least cuspal movement at 5 minutes and 24 hours and the highest gap area, while Groups 4 and 5 showed the highest cuspal movement at 5 minutes and 24 hours. Group 3 had the least gap area. Conclusions: Preheating resin composite to temperatures higher than 37°C increases cuspal movement. The adaptation and gap area of preheated resin composite to 37°C and 54°C improved, but it did not change with resin composite preheated to 68°C. INTRODUCTIONViscoelastic materials, such as resin composites, exhibit decreased viscosity and greater flowability with temperature increase. 1-2 This makes them easily applied and adapted to cavity walls. [3][4] Recently, preheating resin composites with suitable devices has been advocated as a method to reduce paste viscosity, improve marginal adaptation and monomer conversion and shorten curing times. 5 The temperature at which the polymerization occurs affects the conversion process and polymer properties. 6-9 Increased temperature enhances both radical and monomer mobility, resulting in higher overall conversion and reaction rate. Cuspal Movement and Gap Formation in Premolars Restored with Preheated Resin Composite I Elsayad Clinical RelevanceThe use of preheated resin composite to 37°C may improve adaptation and decrease interfacial gaps, but when the composite is preheated to higher temperatures, including 54°C and 68°C, this can cause tooth deformation and subsequently other clinical manifestations.