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Purpose: This in vitro study evaluated the effectiveness of using a 37% phosphoric acid liquid etchant along with MI Paste Plus™ powered technology compared to using MI Paste Plus™ alone or to an artificially created saliva solution in decreasing the demineralization and enhancing the remineralization of artificial carious lesions created on extracted human teeth. The teeth were analyzed and compared using polarized light microscopy, quantitative light-induced fluorescence, and digital photography. Materials and Methods: One hundred three recently extracted non-carious human third molar teeth without observable white-spot lesions, decalcification, or dental fluorosis were selected for this twelve day study and randomly divided into four treatment groups as follows: Group 1 (Control) - Artificial saliva solution (27 teeth) Group 2 (MIP) - MI Paste Plus™ application for 30 minutes daily for 12 days (26 teeth) Group 3 (15MIP) - 15 second etch every third day and MI Paste Plus™ application for 30 minutes daily for 12 days (25 teeth) Group 4 (1MIP) - 1 minute etch on day one ONLY and application of MI Paste Plus™ for 30 minutes daily for 12 days (25 teeth). Results: Results of one<–>way ANOVA revealed there was a significant effect for the type of treatment on the lesion depth (p = 0.0027). The post-hoc Tukey-Kramer's test indicated there was a statistically significant difference between the two groups (15MIP and 1MIP) that incorporated an acid etch in combination with MI Paste Plus™ and the group with exposure to MI Paste Plus™ alone (MIP). In addition, results of one<–>way ANOVA showed that there was no statistically significant effect for type of treatment on the change in fluorescence (p = 0.1417) or the change in density (p = 0.1934). Conclusions: The results of the present study revealed there was a significant effect for the type of treatment on the lesion depth (p = 0.0027). However, the only significant difference found was between the two groups (15MIP and 1MIP) that incorporated an acid etch in combination with MI Paste Plus™ and the group with exposure to MI Paste Plus™ alone (MIP). Thus, daily applications of MI Paste Plus™, with or without an acid etch, did not produce a statistically significant difference in mean lesion depth when compared to the control (artificial saliva group). In addition, the results of the present study showed that there was no statistically significant effect for type of treatment on the change in fluorescence (p = 0.1417) or the change in density (p = 0.1934). Further research is needed to evaluate MI Paste Plus™ capability in prevention of demineralization and/or enhancement of remineralization by conducting randomized clinical trials.

Magister Chirurgiae Dentium (MChD) / A total of 25 third molar teeth (erupted [9], as well as unerupted [16]), from subjects who had lived continuously since birth in an area where the water fluoride concentration was more than 1,8 ppm, were studied. (The range was 1,8 ppm - 2,64 ppm of F-). The subjects had no systemic fluoride supplementation. Tooth brushing with a fluoride containing dentifrice and, perhaps, occasional fluoride mouth rinsing was the only additional exposure to fluoride. The acid-etch biopsy technique was used to determine the fluoride and calcium concentrations at various depths on the enamel surface. The fluoride concentration of the buffered etch solution was determined with an adapted fluoride ion-selective electrode technique, and the amount of calcium by flame atomic absorption spectrophotometry. Six consecutive etchings were done on the mesio-buccal and mesio-lingual cusps of each tooth; the teeth were then washed in an alkali and the same procedure repeated on the disto-buccal and disto-lingual cusps. The depth of etch of each biopsy was calculated assuming that human enamel contains 37% Ca and has a density of 2,95g/ml. It was previously reported, (Grobler & Joubert, 1988), that the enamel fluoride levels of the mesio-buccal and mesio-Iingual sides did not differ from that of the disto-buccal and disto-Iingual sides. The average etch depth and fluoride concentration value as calculated from the values for the two cusps per tooth were used for statistical analysis. The mean etch depths (pm) and mean enamel fluoride concentrations of alkali-washed and unwashed enamel of both erupted and unerupted teeth were tabled, together with the standard deviations and range for each etch. Contrary to the results obtained from a low F- area, no significant difference (p>O.05) could be found in the etch depth between erupted and unerupted enamel in this study. Graphs were plotted by a line fitted to the mean enamel fluoride concentration and mean etch depths values of unwashed erupted, unwashed unerupted, alkali-washed erupted and alkali-washed unerupted third molar teeth. These graphs were compared to the graphs obtained in a comparable study done by Grobler and Kotze (1990), on erupted and unerupted third molar teeth from a low fluoride area (F- < 0,10 ppm). Results indicate that the enamel fluoride concentration in the bulk of the enamel of teeth from a high fluoride area (> 1,8 ppm), is higher than that of teeth from a low fluoride area « 0,10 ppm ). In contrast to the teeth from a low fluoride area, where there was a significant increase (p<0.05) in the fluoride concentration of the outer layer (± 4 J,lm) of erupted enamel when compared to that of the unerupted enamel, no notable increase in the F- content of the enamel was observed in the present study of teeth from a high fluoride area (p>0,05). There was, in addition, no significant (p>0.05) difference between the enamel fluoride content of alkali-washed and unwashed, erupted and unerupted teeth, which showed that very little CaF 2-like material was gained by the enamel after eruption. In both studies the subjects had brushed with a fluoride dentifrice for a period of 1 - 16 years. It was expected that this topical exposure would increase the surface enamel concentration in the high fluoride area similar to the increase found in the low fluoride area. However, this was not the case, and as all the teeth from the high fluoride area exhibited some degree of fluorosis, it was concluded that posteruptive fluoride uptake by fluorotic human enamel without severe enamel loss is limited. This is in agreement with work done by Richards, Fejerskov, Baelum and Likimani (1989).

December 2011. A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Introduction: The purpose of this study is to compare the shear bond strengths (SBSs) of two new commercial adhesive systems to a conventional multistep bonding system incorporating a 35% phosphoric acid gel. In addition, the amount of adhesive remaining on each tooth following debonding will be analyzed and compared using the adhesive remnant index (ARI). Methods: 88 human premolar teeth chosen from the Nova Southeastern tooth databank were randomly divided into four groups. Group I (control group): Transbond XT primer and adhesive (35% phosphoric acid), Group II: iBond Total Etch system with iBond 35 gel (35% phosphoric acid), Group III: iBond Total Etch system with iBond 20 gel (20% phosphoric acid). Group IV: iBond Self Etch. A scanning electron microscope (SEM) was utilized to qualitatively examine the enamel surface of one randomly selected tooth per group immediately after etching, leaving 21 teeth per group available for the debonding procedure (n=21). Following bonding of the stainless steel brackets (3M Unitek, Monrovia, CA), the teeth were stored in water at 37°C ± 2°C for forty-eight hours. A universal testing machine (Instron, Canton, MA) was then used to determine the shear bond strength of each bracket. Additionally, the amount of adhesive remaining on each tooth following debonding was recorded using 10x light microscopy. Results: A 1-way ANOVA revealed that no statistical differences in bond strength were found between the four groups. SBS values of groups I (11.7 ± 3.9), II (11.6 ± 4.6), III (10.3 ± 4.1), and IV (10.8 ± 3.9) demonstrated mean SBSs considered adequate. The iBond Total Etch (20%) and iBond Total Etch (35%) groups were more likely to have an ARI score of 2-3 than the control group (Transbond XT). No significant differences were found between iBond Self Etch and the control group. Conclusion: The SBS's of all three groups, as compared to the control group, were adequate. The iBond Total Etch system, whether used with iBond 20 gel or iBond 35 gel, had more adhesive remaining on the tooth surface after debonding. Standardization amongst shear bond strength studies is significantly needed in the near future in order to accurately compare findings.