Cytotoxicity evaluation of Bio-C, CeraSeal, MTA - Fillapex, and AH Plus root canal sealers by microscopic and 3-(4, 5 dimethythiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay.

Aim: The aim of this study was to compare the cytotoxic effect of calcium silicate-based Bio-C, CeraSeal, and mineral trioxide aggregate (MTA)-based (MTA-Fillapex) sealers to a widely used resin-based sealer (AH Plus) using 3-(4, 5 dimethythiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and microscopic examination. Materials and Methods: A total of (n = 36) samples divided into four groups with three sealer samples per time period of 0 h, 24 h, and 7 days after mixing were extracted in cell culture medium using Dulbecco's Modified Eagle's Medium. The cytotoxicity of these sealers was evaluated using an MTT assay on L929 mouse fibroblasts, and changes in the cell morphology were observed under an inverted phase-contrast microscope (×20). The values obtained were analyzed statistically using one-way ANOVA, Tukey's post hoc, and Bonferroni's test. Results: Bio-C and CeraSeal showed a reduction in cytotoxicity from severe at 0 h to no cytotoxicity at 24 h and 7 day time period. AH Plus showed severe cytotoxicity at all time periods. MTA-Fillapex showed severe cytotoxicity at 0 h which decreased to moderate at 24 h and 7 days. The differences between groups were statistically significant (P < 0.05). Conclusions: The sealers with resin constituents (AH Plus and MTA-Fillapex) showed severe-to-moderate cytotoxicity at different time periods, whereas calcium silicate-based sealers (Bio-C and CeraSeal) were relatively biocompatible as their cytotoxicity decreased significantly from severe initially to noncytotoxic with time.

Comparison between Mineral Trioxide Aggregate Mixed with Water and Water-based Gel Regarding Shear Bond Strength with Resin-modified Glass Ionomer Cement and Composite.

AIM AND OBJECTIVE: To compare between mineral trioxide aggregate (MTA) mixed with water and water-based gel regarding shear bond strength with resin-modified glass ionomer cement (RMGIC) and composite. METHODS AND MATERIALS: In this study, 40 blocks of cylindrical shape were prepared with acrylic. These blocks were divided into four groups with each group consisting of 10 blocks: group-1A: MTA + distilled water + composite, group-1B: MTA + distilled water + RMGIC, group-2A: MTA + polymer + composite, and group-2B: RMGIC + MTA + polymer. After that, a universal testing machine was used for the measurement of shear bond strength. The acrylic blocks were placed under this machine. A blade with a knife-edge was used to provide a crosshead speed of 1 mm/minute. This was continued till bond of MTA in both forms (distilled water/gel) and restorative material failed. RESULTS: It was observed that a statistically significant difference was found between MTAw + composite and MTAg + composite resin but no statistically significant difference between MTAw + RMGIC and MTAg + RMGIC with p ≥ 0.05. It was found that a statistically significant difference was present between the RMGIC and composite groups within the same MTA type with p ≤ 0.05. CONCLUSION: It was concluded from the present study that MTA with a water-based gel has a better shear bond strength than composite resin and RMGIC materials. CLINICAL SIGNIFICANCE: It has been found that MTA has different properties when it is mixed with polymer and water. Very few studies have been conducted in the past to compare MTA mixed with water and water-based gel regarding the shear bond strength with RMGIC and composite.

Comparative Evaluation of Physical Surface Changes and Incidence of Separation in Rotary Nickel-Titanium Instruments: An in Vitro SEM Study.

INTRODUCTION: The aim of the present study was to comparatively evaluate the physical surface changes and incidence of separation in rotary nickel-titanium (NiTi) instruments using scanning electron microscope (SEM). METHODS AND MATERIALS: A total number of 210 freshly extracted human maxillary and mandibular first molars were selected and distributed between three groups. Three different systems of rotary NiTi instruments, namely ProFile (PF), RaCe (RC) and Twisted File (TF), were used to prepare the canals using crown-down technique. All instruments were evaluated by means of SEM with 500× and 1500× magnifications, at four different stages; before use, after preparation of 7 and 14 canals and after instrument separation. Photomicrographs were also taken. The data was analyzed using the Kruskal-Wallis test and the level of significance was set at 0.001. It was found that H (HAT matrix) was 15.316 with 2 degrees of freedom. Moreover the various groups were compared using the Student-Newman-Keuls test with P<0.05 and it was found that all groups were significantly different. RESULTS: RC showed the maximum wear of the surface followed by TF (P<0.05). PF showed the minimum wear except for its tip. There was no correlation between electropolishing and file fracture. Insignificant difference was observed in the mean number of canals shaped by PF and TF before their separation. CONCLUSION: Clinically, TF performance was superior, followed by PF then RC. RC fracture rate was the greatest after preparing the least number of canals.

Cut off values of laser fluorescence for different storage methods at different time intervals in comparison to frozen condition: A 1 year in vitro study.

AIMS: The aim of the following study is to evaluate the change in laser fluorescence (LF) values for extracted teeth stored in different solutions over 1 year period, to give cut-off values for different storage media at different time intervals to get them at par with the in vivo conditions and to see which medium gives best results with the least change in LF values and while enhancing the validity of DIAGNOdent in research. MATERIALS AND METHODS: Ninety extracted teeth selected, from a pool of frozen teeth, were divided into nine groups of 10 each. Specimens in Groups 1-8 were stored in 1% chloramine, 10% formalin, 10% buffered formalin, 0.02% thymol, 0.12% chlorhexidine, 3% sodium hypochlorite, a commercially available saliva substitute-Wet Mouth (ICPA Pharmaceuticals) and normal saline respectively at 4°C. The last group was stored under frozen condition at -20°C without contact with any storage solution. DIAGNOdent was used to measure the change the LF values at day 30, 45, 60, 160 and 365. STATISTICAL ANALYSIS USED: The mean change in LF values in different storage mediums at different time intervals were compared using two-way ANOVA. RESULTS: At the end of 1 year, significant decrease in fluorescence (P < 0.05) was observed in Groups 1-8. Maximum drop in LF values occurred between day 1 and 30. Group 9 (frozen specimens) did not significantly change their fluorescence response. CONCLUSIONS: An inevitable change in LF takes place due to various storage media commonly used in dental research at different time intervals. The values obtained from our study can remove the bias caused by the storage media and the values of LF thus obtained can hence be conveniently extrapolated to the in vivo condition.

Evaluation of biological, physical and chemical properties of mineral trioxide aggregate mixed with 4-META/MMA-TBB.

AIM: To evaluate the change in physical, chemical and biological properties when mineral trioxide aggregate (MTA) is mixed with a resin 4-methacryloxyethyl trimellitate anhydride (4-META)/methyl methacrylate-tri-n-butyl-borane (MMA)-TBB. MATERIALS AND METHODS: For biological evaluation MTA was inoculated in Wistar rat's subcutaneous tissue and peripheral tissue response was checked after 72 h, 7 days, 15 days and 30 days. Setting time was evaluated using Gillmore needle. The Ca++ release at the end of 24 h was checked using ethylenediaminetetraacetic acid titration method. For all the trials MTA mixed with water was kept as a control and the ratio of MTA with resin was 1:1 by weight. RESULTS: The biological reaction was verified by two observers and their readings were matched using kappa test and there was an excellent relevance. There was no significant difference in the tissue reaction at the end of 30 days where both the groups seemed to show healing. Setting time of MTA with 4-META/MMA-TBB was coming to a mean of 26 min (approx.), which is almost 6 times lesser than that of MTA with water. After applying t test, the difference in Ca++ release was found significant (P = 0.00), with mean of 0.044 and 0.031 mol/L of MTA with water and MTA with 4-META/MMA-TBB respectively. CONCLUSION: Under the parameters of this study, this new experimental cement has better handling, physical and chemical properties. Even its subcutaneous tissue reaction is comparable to MTA mixed with water.