Objectives: The aim of this study is to evaluate the efficacy of dentin bonding agent (DBA) in preventing coronal discoloration caused by four different root canal sealers- MTA Fillapex, Sealapex, Zical and Z. O. B seal at different time intervals by measuring chromatic alterations using digital images analysis method.
Methodology: Ninety mandibular premolars were collected and sectioned at 1 mm below the cementoenamel junction. Standard access cavity preparations of dimensions (depth-3 mm, width-0.8 mm, and length-3 mm) were prepared with a No. 245 bur through the cervical access. Following the standard irrigation protocol, specimens were then randomly divided into nine groups (four groups without DBA [1-4] +4 groups with DBA [5-8] +1 negative control [9]). In Groups 1-4, four different root canal sealers (MTA Fillapex, Sealapex, Zical, and Z.O.B seal) were applied to the walls of the pulp chamber. For Groups 5-8, the samples were etched with 37% phosphoric acid and DBA application was done before the respective root canal sealer application. The cervical access in all specimens was sealed using glass ionomer cement. Digital photographs were taken under standard lighting and environmental conditions at different time intervals: preprocedural, postprocedural, and after 1, 2, 3, and 4 months. These images were analyzed using Adobe Photoshop CS6 from which laboratory values and subsequently Delta E values were obtained.
Results: Statistical analysis performed using repeated measures ANOVA and post hoc Tukey's tests show that the groups with DBA application had significantly lower mean Delta E values (P < 0.05) compared to the groups without DBA application.
Conclusion: DBAs applied to the dentinal walls of the pulp chamber before obturation can effectively reduce the sealer-induced coronal discoloration.
Materials and Methods: CBCT images which show MFPMs recorded in HUSM Dental Clinic between January 2015 and June 2016 was obtained and analyzed for their number of roots and canals. A total of 208 CBCT images of MFPMs were collected; 118 patients had unilateral molars and 90 patients had bilateral molars. The following observations were made: (1) root number; (2) number of canals per root; and (3) comparisons of number of roots and canals according to gender, ethnicity, and position.
Results: The majority of cases of bilateral MFPM had the same number of roots (95.6%, 95% confidence interval [CI]: 89.01%, 98.78%) on both the right and left side and only 4 cases (4.4%, 95% CI: 1.22%, 10.99%) had 3 roots on the right and 2 roots on the left sides. The majority of cases had the same number of canals on both sides (66.7%, 95% CI: 55.95, 76.26%) and 33.3% (95% CI: 23.74%, 44.05%) with unequal number of canals. The occurrence of the number of canals was not independent of the sides of the arch (P < 0.001) and there was statistically significantly greater proportion of cases who had greater number of canals on the right side than the left (P = 0.03). The prevalence of right single-rooted MFPM was very small at 0.3% (n = 1) in a Malay male (95% CI: 0.00, 1.83) and the most prevalent was two roots first molar (88.4%). The number of roots was not associated with sex or ethnic group (P > 0.05). The MFPM with a single root was found to have only one mesial canal. For two rooted MFPM, the most prevalent occurrence was two canals at the mesial and one canal at the distal roots (59%); followed by single canals in each mesial and distal (21%) and double canals per root (18%). Three roots MFPM have either single or double canals in the mesial root and double canals in the distal root.
Conclusions: The majority of population in the East Coast region of Malaysia has two roots and three root canals in their MFPMs. There was no difference in the number of roots between gender and ethnic and canals between ethnic.
METHODS: Dentine surfaces were etched with 37% phosphoric acid, bonded with respective in vitro ethanol and acetone adhesives modified with (m/m, 0, 1%, 2% and 3% ribose), restored with restorative composite-resin, and sectioned into resin-dentine slabs and beams to be stored for 24h or 12 months in artificial saliva. Bond-strength testing was performed with bond failure analysis. Pentosidine assay was performed on demineralized ribose modified dentine specimens with HPLC sensitive fluorescent detection. The structural variations of ribose-modified dentine were analysed using TEM and human dental pulpal cells were used for cell viability. Three-point bending test of ribose-modified dentine beams were performed and depth of penetration of adhesives evaluated with micro-Raman spectroscopy. The MMP-2 and cathepsin K activities in ribose-treated dentine powder were also quantified using ELISA. Bond strength data was expressed using two-way ANOVA followed by Tukey's test. Paired T tests were used to analyse the specimens for pentosidine crosslinks. The modulus of elasticity and dentinal MMP-2 and cathepsin K concentrations was separately analyzed using one-way ANOVA.
RESULTS: The incorporation of RB in the experimental two-step etch-and-rinse adhesive at 1% improved the adhesive bond strength without adversely affecting the degree of polymerisation. The newly developed adhesive increases the resistance of dentine collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The application of RB to acid-etched dentine helps maintain the mechanical properties.
SIGNIFICANCE: The incorporation of 1%RB can be considered as a potential candidate stabilizing resin dentine bond.
DESIGN: Dental pulp from extracted human permanent teeth was processed for fluorescence immunohistochemistry. Ten asymptomatic (normal) and 10 symptomatic (symptoms associated with pulpitis) teeth were used in this study. Nerve fibers were identified by immunostaining for a marker, protein gene product 9.5, and the cells were counterstained with 4',6-diamidino-2-phenylindole. An anti-TRPV4 antibody was used to trace TRPV4 expression.
RESULTS: TRPV4 expression was co-localized with the nerve fiber marker. Immunoreactivity for TRPV4 was more intense (p dental pulp of symptomatic teeth compared with that of asymptomatic (normal) teeth.
CONCLUSIONS: There is expression of TRPV4 channels on the nerve fibers of human dental pulp. Our findings suggest upregulation of TRPV4 expression under inflammatory conditions in the pulp. The upregulation of TRPV4 channels may be associated with the exaggerated response of dental pulp to innocuous mechanical, thermal and osmotic stimuli under inflammatory conditions.
METHODS: Here, we show a robust episomal and xeno-free reprogramming strategy for human iPS generation from dental pulp stem cells (DPSCs) which renders good efficiency (0.19%) over a short time frame (13-18 days).
RESULTS: The robustness of DPSCs as starting cells for iPS induction is found due to their exceptional inherent stemness properties, developmental origin from neural crest cells, specification for tissue commitment, and differentiation capability. To investigate the epigenetic basis for the high reprogramming efficiency of DPSCs, we performed genome-wide DNA methylation analysis and found that the epigenetic signature of DPSCs associated with pluripotent, developmental, and ecto-mesenchymal genes is relatively close to that of iPS and embryonic stem (ES) cells. Among these genes, it is found that overexpression of PAX9 and knockdown of HERV-FRD improved the efficiencies of iPS generation.
CONCLUSION: In conclusion, our study provides underlying epigenetic mechanisms that establish a robust platform for efficient generation of iPS cells from DPSCs, facilitating industrial and clinical use of iPS technology for therapeutic needs.