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

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.

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.

Color stability, Roughness, and Microhardness of Enamel and Composites Submitted to Staining/Bleaching Cycles.

OBJECTIVE: To compare the effect of two bleaching systems (bleaching gel and whitening strips) on the color change, roughness, and microhardness of enamel and two resin composites. MATERIAL AND METHODS: Two cavities were prepared on bovine enamel specimens (n = 16) and restored with two composites: a nano-hybrid [Herculite Ultra (HU)] and a micro-hybrid composite [TPH Spectra (TS)]. Baseline color (CIE L*a*b*), roughness (µm), and microhardness (kgf/mm2) were measured using a spectrophotometer, optical profilometer, and Vickers microhardness (VHN) tester, respectively. The specimens were stained with coffee for 14 days, and randomized into two bleaching groups: gel and strips (n = 8), then submitted to a 10-day bleaching/staining test. Color, roughness, and microhardness were re-measured. The outcomes were analyzed using two-way ANOVA and Fisher's-PLSD test (α = 0.05). RESULTS: Gel significantly improved the color (ΔE 4.9-8.3) and increased the roughness (Ra 0.04-0.08 µm) of all substrates (p < 0.0001) compared to strips. Enamel color was significantly improved (ΔE 5.4-8.3) compared to that of HU (ΔE 2.6-4.9) and TS (ΔE 2.0-4.9) with either gels or strips. TS roughness (0.03-0.08 µm) was significantly higher than that of enamel (0.01-0.05 µm) and HU (0.02-0.04 µm). Enamel had significantly reduced microhardness compared to HU (p = 0.0144). CONCLUSION: Gels produced the greatest color improvement and roughness compared to strips. Enamel had significant color improvement but had the greatest decrease in microhardness. CLINICAL SIGNIFICANCE: There was unacceptable color change between enamel and the composites after the combined cyclic effects of staining and bleaching.

The discoloration effect of diluted minocycline containing triple antibiotic gel used in revascularization.

BACKGROUND/PURPOSE: Triple antibiotic paste (TAP) has been successfully used in revascularization procedure. However, one of the problems associated with TAP use is teeth discoloration, which is attributed to the presence of minocycline constituent. The aim of this study is to investigate the discoloration effect of different concentrations of triple (TAP) and double (DAP) antibiotics pastes on root dentine. MATERIALS AND METHODS: Sterilized dentine specimens (4 × 4 × 1) were prepared, and randomly assigned to 5 groups; 1000 mg/mL of Triple antibiotic paste (TAP), 1000 mg/mL of Double antibiotic paste (DAP), 1 mg/mL of TAP in Methylcellulose gel (MTAP), 1 mg/mL of DAP in Methylcellulose gel (MDAP), and distilled water control groups (n = 12). The assigned treatment was applied for 14 days. The CIE L*a*b calorimetric parameters were measured for all dentine specimens using a Chroma meter. One-way ANOVA and multiple comparisons were used for statistical analyses (p < 0.05). ΔE for the different treatments as compared to distilled water group was calculated. RESULTS: TAP and MTAP groups significantly affects the L* values of the root dentine (p < 0.05). ΔE change was noticeable between TAP and MTAP compared to the distilled water group. CONCLUSION: The incorporation of minocycline in TAP medicaments, even in low concentrations, can still provoke a noticeable tooth discoloration.

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.

Evaluation of Residual Antibacterial Effect of Human Radicular Dentin Treated with Triple and Double Antibiotic Pastes.

INTRODUCTION: The aim of this study was to investigate the residual antibacterial effect of human radicular dentin treated with various concentrations of triple antibiotic paste and double antibiotic paste (DAP). METHODS: Sterilized dentin specimens were randomly assigned to 6 treatment groups and a no-treatment control group (n = 45 per group). For treatment groups, specimens were treated with either TAP or DAP at various concentrations (1000, 1, or 0.5 mg/mL) for 2 weeks. Then, each specimen was irrigated with 5 mL saline and incubated in phosphate-buffered solutions for 3, 7, 14, or 30 days. After that, Enterococcus faecalis was cultured on the specimens for 3 days. Each specimen was then transferred to a tube containing 200 µL saline, sonicated, and vortexed to detach the bacterial biofilm. The detached biofilm was spiral plated, and the number of colony-forming units was determined using an automated counting machine. RESULTS: Dentin specimens treated with 1000 mg/mL TAP or DAP had a significant residual antibacterial effect up to 14 days and 30 days, respectively. No significant difference was observed between 1000 and 1 mg/mL TAP and DAP at all time points. Dentin treated with all concentrations of DAP has a significantly longer residual antibacterial effect compared with dentin treated with TAP at the same concentrations. CONCLUSIONS: Radicular dentin treated with TAP and DAP showed a significant residual antibacterial effect compared with untreated dentin. All concentrations of DAP showed a significantly longer residual antibacterial effect compared with the same concentrations of TAP.

Effectiveness of antibiotic medicaments against biofilm formation of Enterococcus faecalis and Porphyromonas gingivalis.

INTRODUCTION: In this study we compared the antibacterial effect of triple antibiotic paste (TAP), double antibiotic paste (DAP), and calcium hydroxide [Ca(OH)2] against Enterococcus faecalis and Porphyromonas gingivalis biofilm. METHODS: The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and biofilm formation were measured by using microtiter plate methods. The 2 bacteria were treated with different dilutions of TAP, DAP, and Ca(OH)2 solutions. The turbidities of the bacterial cultures in the microtiter plate were measured by optical density at 490 nm by using a spectrophotometer. Data were analyzed by 2-way analysis of variance (α = 0.05). RESULTS: For TAP, the MIC and MBIC values were 0.003 mg/mL for E. faecalis and 0.006 mg/mL for P. gingivalis. The MBC values for TAP were 0.3 mg/mL for both bacteria. The MIC and MBIC values for DAP were 0.001 mg/mL for E. faecalis and P. gingivalis. The MBC values for DAP were 0.14 mg/mL for both bacteria. Biofilm formation of the 2 bacteria was significantly decreased with TAP and DAP at all tested dilutions (P < .0001) compared with control groups; however, TAP and DAP biofilm formations were not significantly different from each other. Ca(OH)2 significantly decreased bacterial biofilm formation compared with the control, but it was significantly less than TAP and DAP (P < .05). CONCLUSIONS: Both TAP and DAP were more effective than Ca(OH)2 against E. faecalis and P. gingivalis. DAP can be considered an effective and comparable antibacterial substitute for TAP.

Full-contour Y-TZP ceramic surface roughness effect on synthetic hydroxyapatite wear.

OBJECTIVE: To investigate the effects of polishing techniques on the surface roughness of Y-TZP ceramic and on the wear behavior of synthetic hydroxyapatite (HA). METHODS: Thirty-two full-contour Y-TZP (Diazir(®)) sliders (φ=2 mm × 1.5 mm in height) were manufactured using CAD/CAM, embedded in acrylic resin using brass holders, and randomly allocated into four groups (n=8): according to the finishing/polishing procedure: G1-as-machined, G2-glazed, G3-diamond bur finishing and G4-G3+OptraFine(®) polishing kit. Thirty-two sintered HA disks (φ=13 mm × 2.9 mm in height) were similarly mounted in brass holders. Y-TZP sliders baseline surface roughness values (Ra and Rq, in µm) were recorded using a non-contact profilometer (Proscan 2000). A two-body pin-on-disc wear test was performed. HA height (µm) and volume (mm(3)) losses were measured. Y-TZP height loss was measured using a digital micrometer. One-way ANOVA was used to determine the effect of the polishing techniques on the surface roughness. Comparisons between groups for differences in antagonist height loss/volume, and slider height loss were performed using one-way ANOVA. Statistical significance was set at α=0.05. RESULTS: Roughness measurements showed significant differences (p=0.0001) among the surface treatments with G1 (Ra=0.84, Rq=1.13 µm) and G3 (Ra=0.89, Rq=1.2 µm) being the roughest, and G2 (Ra=0.42, Rq=0.63 µm) the smoothest (p=0.0001). Y-TZP slider height loss was highest for the glazed group (35.39 µm), and was lowest for the polished group (6.61 µm) (p=0.0001). Antagonist volume and height losses for groups (G1-G3) were similar, while the polished group (1.3 mm(3), 14.7 µm) showed significant lower values (p=0.0001). SIGNIFICANCE: Although glazed zirconia provides an initially smooth surface, significantly increased antagonist wear was observed compared to the polished Y-TZP zirconia surface.