Objectives: The aim of the present study was to evaluate the effects of remineralizing agent (MI Paste Plus) on the surface topography and chemical analysis of sound human enamel following acid-etching and laser etching, using Environmental scanning electron microscopic (ESEM) techniques. Materials and Methods: Fifty human upper premolars extracted for orthodontic reason were used. The teeth were mounted vertically in a self-cure acrylic cylinder. One clinician prepared all the teeth, in each tooth; a 4x4 mm area was treated in middle third of the buccal surface. The teeth were divided into three groups, Group I : Control group no treatment ; Group II: enamel etched with 37% phosphoric acid; Group III: enamel was irradiated with Er,Cr:YSGG laser. Group II and III were subdivided into subgroup according to remineralizing agent (GC MI Paste Plus), (n=10). Remineralizing paste was used as manufacturer's instructions, a single application of approximately 0.5 mm layer for 3 minutes; twice daily. Synthetic saliva was rinsing between remineralizing paste application, followed by synthetic saliva rinsing for 15 days with fresh replenished on a daily basis. Teeth were examined for morphological and chemical characterization using an Environmental Scanning Electron Microscope. All of the data were analyzed by two-way analysis of variance (ANOVA) and Tukey's post hoc test. Results: Morphological changes of enamel surfaces of acid-etching group showed type 1 etching pattern and laser etching group showed the normal appearance of the enamel prisms (honeycomb-like structure). Comparison of all groups and control group P & Ca weight%, the greatest mean value was recorded in acid etch group before and after remineralization with GC MI Paste Plus. Conclusion: Within the limits of this in vitro study, Since Ca and P constitute the major part of tooth structure, while other element represent trace element; results emphasize the effect of GC MI Paste Plus on tooth remineralization. Comparison of all groups and control group, acid etch group before and after remineralization recorded the greatest mean value for P & Ca weight%. Laser etching didn't have a significant effect on tooth composition and mineral content.

Objectives: The aim of the present study was to evaluate the etching pattern of Er,Cr:YSGG and conventional etching on prepared samples of human enamel by environmental scanning electron microscope (ESEM). Materials and Methods: Forty five freshly extracted human upper premolars were used; the teeth had been extracted for orthodontic reasons and were collected and stored in a solution of 0.1% (wt/vol) thymol. The teeth were mounted vertically in a self-cure acrylic cylinder. One clinician prepared all the teeth, in each tooth, a 4x4 mm area was treated in middle third of the buccal surface. The teeth were divided into three groups according to type of etching techniques (n=15).Group(A): enamel etched with 37% phosphoric acid for 30 s, thoroughly rinsed with distilled water for 60 s and gently air dried.; Group (B): enamel was irradiated with Er,Cr:YSGG laser ablated with an energy output of 4.5 watt/30hz and Group (C):enamel was irradiated with Er,Cr:YSGG laser ablated with an energy output of 4.5 watt/20hz. In group b & c Er,Cr:YSGG laser (2.78 μm wavelength) used for 15 sec at 45degree angulations working distance 5mm on a square size 4x4mm on buccal surface. Micro-morphological changes of enamel surface were evaluated using an environmental scanning electron microscope at X250 & X1500 magnification. Results: In this study, laser with 30 Hz reveals a definite change in the surface of the enamel, most of the enamel prisms are interrupted showing an irregular outline. However laser with 20 Hz showed the ultra-structural appearance of enamel nearly similar to that of conventionally etched enamel with 37 percent phosphoric acid. Conclusion: Within the limits of this in vitro study, both conventional acid etching & laser 20 Hz etching showed nearly similar effect on enamel surface, so the laser-etching can be successfully used as an alternative to the conventional acid-etch. On the other hand laser 30 Hz etching failed to induce an effect on enamel surface comparable to that of acid etching and therefore can't be used as substitute for the conventional acid-etch.

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Statement of problem: failure of resin composite restoration is most frequently caused by improper polymerization; it would be advantageous if the restoration possessed optimal depth of cure. Objective: The purpose of this study was to the depth of cure of resin composite restoration by using Trans-tooth curing technique with different light curing intensities Material and methods: A total of 20 sound, non-carious human maxillary anterior teeth, were used in this study. The teeth were divided into 2 main groups of 10 teeth each according to the thickness of the labial tooth structure plate (T); either 1.5 mm plate thickness (T1) or 1 mm plate thickness (T2). Each main group was subdivided into 2 subgroups of 5 teeth each according to the intensity of the light curing (I); either conventional intensity light curing (I 1 ), or high intensity light curing (I 2 ). Two Standardized class III cavity preparations were prepared in the proximals and lingual surfaces. Resin composite restorations were applied then all the teeth prepared for micro-hardness assessment. Data were explored for normality using Kolmogorov-Smirnov test of normality. The results of Kolmogorov-Smirnov test indicated that most of data were normally distributed (parametric data), therefore, one-way analysis of variance (ANOVA) test was used to compare between groups. This was followed by Tukey's post hoc test and independent t test for pairwise comparisons. The significance level was set at p < 0.05. Results:Comparing all groups revealed that the highest mean value was recorded in High intensity curing (1.5 mm), whereas the lowest mean value was recorded in conventional intensity curing at 1.5 mm. ANOVA test revealed that the difference between all groups was statistically significant (P=0.001). Conclusions:Under the limitation of this in-vitro study it can be concluded that the thickness of the tooth structure as trans-tooth curing technique was applied is greatly affect the amount of light energy reached to the resin composite restoration. So therefore subsequently affect the degree of conversion of the composite restoration rather than the degree of light intensity. (804)Rasha Raafat E.D.

BACKGROUND: The main objective of conservative dentistry is maintaining the health of the dentition and restored teeth free from dental caries. The prevention of dental caries can be achieved by personal prevention programs at home, dental health care professional, and public health application programs. Based on knowledge related to the etiology and pathogenesis of dental caries, this provides a chance for application of effective prevention program for the prevention of dental caries. AIM: This study aimed to evaluate the effect of different preventive regimens using different toothpastes on caries risk using cariogram and decayed, missing, and filled (DMF) scores of high caries risk patients. MATERIALS AND METHODS: The study was conducted on 66 participants with high caries risk. Participants were divided into three groups, 22 participant each. According to the test regimen, where (A1) participants were exposed to a regimen including dual zinc plus arginine-based toothpaste (Colgate total), (A2) participants were exposed to a regimen including zinc-based toothpaste (Crest complete), and (A3) control group was participants that were exposed to a regimen including fluoride-based toothpaste (Signal). The study was carried for 1 year, assessment of cariogram and DMF scores was done in four intervals: T0: baseline, T3: after 3 months, T6: after 6 months, and T12: after 12 months. RESULTS: According to cariogram, there was a statistically significant difference between Groups A1, A2, and A3, where p < 0.001. However, DMF scores of all groups showed no statistically significant difference between the three groups. CONCLUSIONS: Dual zinc plus arginine-based toothpaste is a superior caries preventive regimen in high caries risk patients. CLINICAL SIGNIFICANCE: The benefits of preventive regimen to the practitioner will be providing a non-invasive, and cost-efficient method to prevent dental caries. Benefits to the patient will be an improvement of oral hygiene, prevention of dental caries, and maintain healthy dental supporting structures.