Effect of different endodontic regeneration protocols on wettability, roughness and chemical composition of surface dentin

Introduction We investigated the changes in physiochemical properties of dentin surfaces after performing different endodontic regeneration protocols. Methods Human dentin slices were randomized into 4 treatment groups and 1 untreated control group (n = 10). One treatment group was irrigated with sodium hypochlorite (NaOCl) for 5 minutes followed by EDTA for 10 minutes. The other 3 treatment groups were irrigated with NaOCl; treated for 4 weeks with triple antibiotic paste (TAP), diluted triple antibiotic paste (DTAP), or calcium hydroxide (Ca[OH]2); and then irrigated with EDTA. After treatment, contact angles between a blood analog and dentin surfaces were evaluated. Surface roughness and chemical composition were characterized using optical profilometry and energy-dispersive X-ray spectroscopy, respectively. One-way analysis of variance followed by Fisher least significant difference tests were used for statistical analyses. Results All treatment groups showed a significant reduction in wettability and a significant increase in surface roughness when compared with untreated dentin. Dentin treated with Ca(OH)2 had significantly lower wettability compared with all other groups. No significant difference in wettability was found between dentin treated with DTAP and TAP protocols. Dentin treated with TAP had significantly higher surface roughness compared with all other groups. Untreated dentin and NaOCl + EDTA–treated dentin had significantly higher calcium and phosphorus as well as significantly lower carbon compared with dentin treated with Ca(OH)2, DTAP, and TAP. Conclusions Endodontic regeneration protocols had a significant effect on wettability, surface roughness, and chemical composition of surface dentin. The Ca(OH)2 protocol caused a significant reduction in dentin wettability compared with TAP or DTAP protocols

The Effect of Diluted Triple and Double Antibiotic Pastes on Dental Pulp Stem Cells and Established Enterococcus faecalis Biofilm

Objectives To investigate the effect of various dilutions of antibiotic medicaments used in endodontic regeneration on the survival of human dental pulp stem cells (DPSCs) and to determine their antibacterial effect against established Enterococcus faecalis biofilm. Materials and methods The cytotoxic and antibacterial effects of different triple (TAP) and double antibiotic paste (DAP) dilutions (0.125, 0.25, 0.5, 1, and 10 mg/ml) were tested against Enterococcus faecalis established biofilm and DPSC. Established bacterial biofilm were exposed to antibiotic dilutions for 3 days. Then, biofilms were collected, spiral plated, and the numbers of bacterial colony forming units (CFU/ml) were determined. For the cytotoxic effect, lactate dehydrogenase activity assays (LDH) and cell viability assays (WST-1) were used to measure the percentage of DPSC cytotoxicity after 3-day treatment with the same antibiotic dilutions. A general linear mixed model was used for statistical analyses (α = 0.05). Results All antibiotic dilutions significantly decreased the bacterial CFU/ml. For WST-1 assays, all antibiotic dilutions except 0.125 mg/ml significantly reduced the viability of DPSC. For LDH assays, the three lowest tested concentrations of DAP (0.5, 0.25, 0.125 mg/ml) and the two lowest concentrations of TAP (0.25 and 0.125 mg/ml) were non-toxic to DPSC. Conclusions All tested dilutions had an antibacterial effect against E. faecalis. However, 0.125 mg/ml of DAP and TAP showed a significant antibacterial effect with no cytotoxic effects on DPSCs. Clinical relevance Using appropriate antibiotic concentrations of intracanal medicament during endodontic regeneration procedures is critical to disinfect root canal and decrease the adverse effects on stem cells

Effects of air-abrasion pressure on the resin bond strength to zirconia: a combined cyclic loading and thermocycling aging study

Objectives To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide (Al2O3) particles at different pressures. Materials and Methods Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and χ2 tests (α = 0.05). Results The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. Conclusions CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used

The predictive value of high school grade point average to academic achievement and career satisfaction of dental graduates

Abstract Background In a country where admission to dental schools is based solely on the cognitive abilities of students, the aim of the study was to investigate the correlation between high school grade point average and graduating academic achievement for dental students; moreover, determine whether a correlation exists between dental students’ graduating academic achievement and their career choices and job satisfaction. Methods A five-year retrospective cohort study was conducted at the University of Jordan, involving (828) dental graduates first enrolled between 2010 and 2014. Correlations comparing high school grade point average and graduating academic achievement were done for the total sample composed of (736) students. A short survey was constructed to assess the career choices and job satisfaction for recently graduated dentists and correlate them with their graduating academic achievement. Results Statistically significant but weak positive correlation (0.3) was found between high school grade point average and graduating academic achievement for dental students (p ≤ 0.05). Statistically significant correlations were found between graduating academic achievement and career choices and job satisfaction. Conclusion The significant positive correlation between the high school grade point average and graduating academic achievement of our dental students indicate that our school admission system depending on high school grade point average is a valid system. There was a significant negative correlation between the graduating academic achievement and both the career choices and job satisfaction among fresh graduate dentists in Jordan. This information is required to update the dental school admissions procedures in response to the changing dental educational landscape

Effects of air-abrasion pressure on the resin bond strength to zirconia: a combined cyclic loading and thermocycling aging study

OBJECTIVES To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide (Al2O3) particles at different pressures. MATERIALS AND METHODS Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and χ2 tests (α = 0.05). RESULTS The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. CONCLUSIONS CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used