Materials and methods: Sixty (60) extracted sound Maxilla (Mx) and Mandibular (Mn) premolars were randomly divided into 2 groups (test and control). Artificial WSLs were produced on buccal surface of teeth and were immersed in artificial saliva for 8 weeks. Colour components (L∗, a∗, b∗) and surface roughness (Sa∗) were assessed on 40 teeth using colour difference meter RD-100 and Alicona® Infinite Focus profilometer respectively. The measurements were done at baseline (T1), directly after artificial WSLs (T2), after 24 hours immersed in saliva and application of resin (T3) and immersion in artificial saliva for 1 (T4), 2 (T5), 4 (T6), 6 (T7) and 8 (T8) weeks. SEM images analysis were carried out on 20 teeth in four time points.
Results: The values of L∗ (lightness), b∗ (yellow/blue) and Sa∗ (surface roughness) are gradually reduced to the baseline value. Whereas, the value of a∗ gradually increased with distinct treatment time to achieve the baseline value. The higher value of L∗ and Sa∗, the whiter the lesion suggesting higher degree of enamel demineralization and surface roughness. Lower L∗ values suggest a masking colour effect.
Conclusion: The material produced favorable esthetics on colour and the surface roughness of teeth at distinct treatment times. It is recommended to be used to improve WSL post orthodontic treatment.
MATERIAL AND METHOD: Forty sound permanent mandibular premolars were collected from a dental clinical setting and disinfected. All forty samples were mounted vertically in a rubber mold exposing only the clinical crown. All samples were bleached using Opalescence Boost Professional Teeth Whitening. After the bleaching procedure, each sample was randomly allocated into four groups according to surface treatment. Samples in group 1 were treated with methylene blue photosensitizer (MBP). Samples in group 2 were exposed to 10% sodium ascorbate. Samples in group 3 were treated with Er, Cr: YSGG laser (ECL). Samples in group 4 were not treated (control). All Samples were treated with 37% phosphoric acid and a bonding agent was applied. A bulk-fill composite was cured to all specimens and all samples were treated in a thermocycler. Specimens were placed in a universal testing machine for shear bond strength (SBS) testing. Descriptive statistics were associated by analysis of variance (ANOVA) and Tukey's post hoc test maintaining level of significance (p<0.05) RESULTS: The lowest SBS scores were achieved in the bleached enamel (BE) group (15.25±1.745 MPa). Whereas, the highest bond integrity was attained by AA group (32.23±1.854 MPa). Samples treated with ECL (31.87±1.659 MPa) and AA (32.23±1.854) were comparable (p>0.05). Samples treated with PDT exhibited significantly different SBS (22.41±1.258) compared to other experimental groups CONCLUSION: ECL showed a reversal effect of BE compared to AA and has the potential to be used in clinical settings. BE reversal using MBP needs further investigation.
AIM: To determine the incremental and total enamel loss when enamel surfaces are exposed to multiple etching cycles and to assess the relative attenuation coefficient after multiple etching cycles and resin infiltration treatment.
METHODS: Ninety extracted sound human premolars teeth were divided into 9 groups (n = 10); with each consecutive group having one additional etching cycle up to 9 cycles. The teeth were scanned with optical coherence tomography and enamel loss and attenuation coefficient were measured with MATLAB software. Enamel loss (one-way ANOVA, p ≤ 0.05) and attenuation coefficient (two-way ANOVA, p ≤ 0.05) were statistically analyzed.
RESULTS: There was a significant total enamel loss of more than 33% found at the 7th etching cycle and more. There was no statistically significant difference in the incremental mean depth of penetration of resin between various etching cycles (F(8, 134) = [2.016], one-way ANOVA, p = 0.185).
CONCLUSION: This study recommends that etching should not be repeated more than seven cycles to prevent excessive enamel loss. Following eight etching cycles, resin infiltration penetration appears approximately equal to that of healthy enamel.
MATERIALS AND METHODS: Sound extracted human molars were randomly divided into: manufacturer's instructions (MI), manual blend 2 mm (MB2), and manual blend 4 mm (MB4). Occlusal enamel was removed and flattened, dentin surfaces were bonded by Prime & Bond universal (Dentsply and Optibond FL, Kerr). For the MI group, adhesives were applied following the manufacturer's instructions then light-cured. For MB groups, SDR flow+ bulk-fill flowable composite resin was applied in 2- or 4-mm increment then manually rubbed by a micro brush for 15 s with uncured dentine bonding agents and the mixture was light-cured. Composite buildup was fabricated incrementally using Ceram.X One, Dentsply nanohybrid composite resin restorative material. After 24-h water storage, the teeth were sectioned to obtain beams of about 0.8 mm2 for 24-h and thermocycled micro-tensile bond strength at 0.5 mm/min crosshead speed. Degree of conversion was evaluated with micro-Raman spectroscopy. Contraction gaps at 24 h after polymerization were evaluated and atomic force microscopy (AFM) nano-indentation processes were undertaken for measuring the hardness across the interface. Depth of resin penetration was studied using a scanning electron microscope (SEM). Bond strength data was expressed using two-way ANOVA followed by Tukey's test. Nanoindentation hardness was separately analyzed using one-way ANOVA.
RESULTS: Factors "storage F = 6.3" and "application F = 30.11" significantly affected the bond strength to dentine. For Optibond FL, no significant difference in nanoleakage was found in MI/MB4 groups between baseline and aged specimens; significant difference in nanoleakage score was observed in MB2 groups. Confocal microscopy analysis showed MB2 Optibond FL and Prime & Bond universal specimens diffusing within the dentine. Contraction gap was significantly reduced in MB2 specimens in both adhesive systems. Degree of conversion (DC) of the MB2 specimens were numerically more compared to MS1 in both adhesive systems.
CONCLUSION: Present study suggests that the new co-blend technique might have a positive effect on bond strengths of etch-and-rinse adhesives to dentine.
MATERIALS AND METHODS: Test medias used in this study included carbonated beverage, noncarbonated beverage, high-energy sports drink medicated cough syrup, distilled water as the control. A total of 110 previously extracted human premolar teeth were selected for the study. Teeth were randomly divided into two groups. Test specimens were randomly distributed to five beverages groups and comprised 12 specimens per group. Surface roughness (profilometer) readings were performed at baseline and again, following immersion for 14 days (24 h/day). Microleakage was evaluated. The results obtained were analyzed for statistical significance using SPSS-PC package using the multiple factor ANOVA at a significance level of P < 0.05. Paired t-test, Friedman test ranks, and Wilcoxon signed ranks test.
RESULTS: For surface roughness high-energy sports drink and noncarbonated beverage showed the highly significant difference with P values of 0.000 and 0.000, respectively compared to other test media. For microleakage high-energy sports drink had significant difference in comparison to noncarbonated beverage (P = 0.002), medicated syrup (P = 0.000), and distilled water (P = 0.000).
CONCLUSION: High-energy sports drink showed highest surface roughness value and microleakage score among all test media and thus greater erosive potential to enamel while medicated syrup showed least surface roughness value and microleakage among all test media.
Objectives: The main aim of the study was to determine and compare the erosive potential of different fruit juices in frozen/unfrozen forms on primary teeth by studying the calcium dissolution.
Materials and methods: pH of four different juices (pure) - apple, orange, citrus limetta (musumbi) and grapes were determined using a digital pH meter. The titratable acidity of these in frozen and unfrozen forms were determined by adding 0.2 ml of 1M NaOH to these to raise to pH=5.5(critical pH) and pH =7(neutral pH). Forty eight caries free deciduous anterior teeth specimens were prepared to study the calcium dissolution by atomic absorption spectrophotometer. The results were analysed for statistical significance using One-way Repeated Measures ANOVA and pair wise multiple comparison with Bonferroni correction.
Results: Total titratable acidity and calcium dissolution were found to be significantly more in the initial thawed fruit juices.
Conclusion: Frozen fruit juices had more buffering capacity and erosive potential than unfrozen forms. The study concluded that sucking on frozen fruit juices is more damaging to teeth than unfrozen forms because more of erosion is expected to occur in a frozen state.