Background Knowledge: Calcium hydroxide with a pH of almost 12.5 is a strong alkaline substance. In an aqueous solution, dissolution of calcium hydroxide occurs into calcium and hydroxyl ions. Its biological properties include antimicrobial activity, inhibiting resorption of tooth and inducing of repair by formation of hard tissue. Hence it is widely used in several clinical situations. The capacity of calcium hydroxide to produce an alkaline shift in pH is responsible for its antimicrobial effect. This property will be affected when it is combined with other substances/ vehicles like 2% chlorhexidine, sodium hypochlorite etc, which makes the action last longer. Therefore this study was conducted to determine the changes in pH of five different types of calcium hydroxide based intracanal medicaments. Materials and methods: This study assesses the changes in pH when calcium hydroxide is mixed with different vehicles like 2% chlorhexidine, sodium hypochlorite, povidone iodine and also commercially available RC Cal (premixed) and Metapex. It is an in vitro study with time intervals of 24 hours, 48 hours and 1 week. Results and conclusion: Within the limitations of the study, it is found that calcium hydroxide when mixed with distilled water has given the best results.

Aim: To evaluate and compare the compressive strength of a new ceramic-reinforced glass ionomer (Amalgomer CR) and resin coated high strength glass ionomer. cement (GIC) (Equia forte) with a nanohybrid composite (tetric N ceram). Methodology: Twenty four maxillary premolar teeth were selected. Selected teeth after cleaning were mounted in acrylic resin blocks exposing the crown. Class II cavities were prepared. Samples were divided into three groups of 8 teeth; • Group 1: Class II cavity restored with Tetric N Ceram composite (control group) • Group 2: Class II cavity restored with amalgomer CR • Group 3: Class II cavity restored with equia Forte Restored samples stored in artificial saliva for 2 weeks and subjected to compressive strength test using the universal testing machine at a cross head speed of 0.5 mm/min. The failure load was recorded. SPSS software was employed for statistical analysis. Mean compressive strength and mean compressive load was calculated. One way analysis of variance (ANOVA) followed by post hoc tests served for comparison of compressive strength among the study groups. The significance level was set at 0.001. Conclusion: Tetric N ceram has a high compressive strength compared to amalgomer CR and equia forte. It can be concluded that tetric N ceram may be a better posterior restorative in comparison with Amalgomer CR and Equia Forte.

Aim: The current study aimed to compare the efficacy of working length measurement in different simulated clinical scenariosapical root resorption and horizontal root fracture using a new integrated apex locator SCM 008 (Fanta dental materials) and ROOT ZX (J Morita). Materials and methods: Forty recently extracted single-rooted mandibular premolar teeth were taken. Allotted into two major groups under two apex locators. Each group was subdivided into two, based on the different simulated conditions. In horizontal root fracture group, an oblique notch was made on the external root surface 8 mm from the anatomic apex. To simulate apical root resorption, an irregular defect was drilled at the apex with a round bur. Teeth were embedded in a customized holder containing alginate simulating the periodontal ligament. Electronic measurements were taken and compared. Statistical analysis: One sample t-test. Results: Though values were more accurate in the case of Root ZX, the result obtained was not significant statistically. Conclusion: In the case of both horizontal fracture and apical resorption, Root ZX and the new integrated apex locator could perform with superior efficacy in the given experimental conditions.

Aim: To evaluate and compare the microhardness of artificially demineralized human enamel treated with three different remineralizing agents. Materials and methods: Twenty-five intact caries free maxillary premolar were taken for the study. The tooth was decoronated 2 mm below cementoenamel junction (CEJ). Enamel samples of 2 mm width were prepared, the enamel slices were taken from the buccal and lingual surfaces of the teeth using a diamond disc. Following sample preparation, windows were created with a dimension of 5 mm × 5 mm. Adhesive tape was placed over it to resist acid attack. The specimens were demineralized using a demineralizing solution for ten days and then subjected to microhardness testing. Teeth were divided into five groups. • Group 1: Negative control in which no therapy was done • Group 2: Demineralized enamel specimen • Group 3: Remineralization with potassium nitrate containing toothpaste • Group 4: Remineralization with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) containing toothpaste, • Group 5: Remineralization with hydroxyapatite containing toothpaste. The remineralizing agents were applied using cotton applicator tips for 3 minutes twice daily and they were washed under distilled water. The samples were then stored in artificial saliva for 10 days and subjected to microhardness testing. Statistical analysis: One-way analysis of variance (ANOVA) test. A post hoc comparison showed that done using a paired t-test. Results: The result showed that there has been statistically significant difference in the microhardness for control samples and experimental samples. Within the experimental samples, group which used hydroxyapatite paste as remineralizing paste showed better results when compared to paste which contain calcium and potassium ions and sodium nitrate.

Aim: The aim of this study was to evaluate the effect of different concentrations of sodium hypochlorite (NaOCl), solutions on the surfaces of nickel-titanium (Ni-Ti) rotary files using atomic force microscopy (AFM). Materials and methods: Sixteen unused ProTaper Ni-TI files of size F1, were selected for AFM evaluation at apical, middle and coronal segments. The selected files were then assigned into 4 groups • Group 1: Unused files (n = 4) • Group 2: 2.5% sodium hypochlorite irrigation (n = 4) • Group 3: 5.25% sodium hypochlorite irrigation (n = 4) • Group 4: 8.25% sodium hypochlorite irrigation (n = 4) The files were used as per the manufacturer's instruction, and the number of uses was restricted to five. Normal irrigation protocol was followed and the only variable being a concentration of sodium hypochlorite (2.5%, 5.25%, 8.25%). The post-treatment roughness average (RA) and root mean square (RMS) of apical, middle and coronal segments of the scanned profiles were then recorded using AFM and compared with the initial readings. The data was tabulated and analyzed using one-way analysis of variance (ANOVA). Conclusion: Within the limitations of the present study, it was concluded that different concentrations of sodium hypochlorite showed effect on the surface characteristics of Ni-Ti instruments.

Aim: This study aims to evaluate the color change in enamel bleached with herbal bleaching agents using a spectrophotometer. Materials and methods: Baseline color values of 40 randomly selected artificially stained premolars were obtained. The specimens were randomly divided into four groups of 10 teeth each. Group 1 (n-10)-Musa sapientum, group 2–citrus sinensis, group 3–citrus limon, control group 4 to 35% hydrogen peroxide. The color difference was examined using spectrophotometer Results: All the agents that have been tested showed a significant color change since ÄE is more than 3.3, of which Musa sapientum gives the best result as compared to citrous groups. Statistical analysis: The results were statistically analyzed using the Mann–Whitney test. Conclusion: Within the limitations of this study, Musa sapientum whitens the teeth better than citrus sinensis and citrus limon but lesser than hydrogen peroxide.