Evaluation of matrix metalloproteinase and cysteine cathepsin activity in dentin hybrid layer by gelatin zymography

Aim: The aim of this study was to comparatively assess the gelatinolytic activity of matrix metalloproteinases(MMPs) and Cysteine Cathepsins (CCs) in the adhesive interface using etch and rinse adhesive at different time intervals using zymographic technique. Methodology: Twenty freshly extracted non-carious human third molars were used in this study. Occlusal surfaces were ground flat and 1mm thick horizontal dentin slabs were obtained from each tooth using a diamond disc. The dentin surface was polished with 600-grit silicon-carbide paper. Five out of 20 samples were directly pulverized. In the remaining fifteen samples, the dentin was etched and adhesive was applied and light cured according to the manufacturer's instructions. A 1mm thick flowable composite was build up and light cured. Bonded specimens were cut vertically into 3 to 4 dentin slabs by means of diamond disc to expose the adhesive/dentin interfaces. These were then ground down to 500 µm thick resin-dentin interface using a hard tissue microtome. These sections were then pulverised into powder. Following this, every five samples were subjected to zymographic analysis after 1 day, 7 days and 21 days. Results: Zymograms showed clear, thicker bands on all three isoforms in the etched samples compared to control samples at 1st and 7th day intervals and became inactive at 21st day for all three isoforms. MMP 9 activity was relatively higher when compared to CCs and MMP 2. Conclusion: Etch and rinse adhesive activated MMPs and CCs within the hybrid layer that remained active till 7th day and no gelatinolytic activity was found on 21st day and MMPs are more active compared to CCs and MMP-2

Effect of white tea extract incorporated calcium silicate cements on flexural strength and collagen degradation of dentin

Aim: The aim of the study was to comparatively evaluate the effect of white tea extract-incorporated mineral trioxide aggregate (MTA) and Biodentine (BD) on collagen degradation and flexural strength of coronal dentin. Methods: Two hundred and fifty dentin beams (10 mm × 2 mm × 2 mm) were obtained from the mid-coronal portion of caries-free human 3rd molars. They were randomly assigned to five experimental groups (n = 50). Group 1-control group (No experimental materials placed); Group 2-MTA; Group 3-MTA with 10% white tea extract (WMTA); Group 4-BD; and Group 5-BD with 10% white tea extract (WBD). All experimental materials were mixed and then spread onto the prepared dentin beams. Each group was further divided into five subgroups with each 10 samples according to aging periods of 24 h, 1, 3, 6 months, and 1 year as A, B, C, D, and E, respectively. The dentin beams were placed in contact with a set calcium silicate cement block in silicone molds, with only one side of each beam exposed to the cement at 37°C in a 100% relative humidity chamber. At each designated time period, the beams were copiously rinsed with deionized water and tested for flexural strength and collagen degradation using a universal testing machine and Fourier Transform-Raman spectrometer, respectively. Flexural strength results were statistically analyzed using one-way ANOVA, followed by post hoc adjustment with Tukey's test for pair-wise comparisons with P < 0.05. Results: Collagen degradation was more in Group 2, followed by 4, 3, and 5. All the groups showed a gradual reduction in flexural strength over 1 year. Group 2 showed the highest reduction in flexural strength over 1 year. Group 5 showed the least reduction in flexural strength. Conclusion: BD and white tea-incorporated BD showed less collagen degradation and better flexural strength than MTA and white tea-incorporated MTA, respectively