Abtesam Aljdaimi

Background: Fractures of endodontic files are one of the serious concerns affecting root canal treatment prognosis. Recently, countless innovations have been presented to optimize their microstructure and flexibility, reflected in different commercial brands. However, their performance has not been evaluated in complex root canals. Aim: To evaluate and compare the resistance to cyclic fatigue of three rotary endodontic files utilizing artificial canals designed with different angles and radii of curvature. Materials and Methods: sixty rotary instruments of the following types were used. Group I: Edge endo X7; Group II: Luster dent pliancy total solution; and Group III: Race Evo FKG. Instruments in each group were constrained into two subgroups (n=20) to be examined in artificial canals having a single curvature or a double curvature. The cyclic fatigue resistance of each rotary file was tested, where the number of cycles to fracture (NCF) and the fractured segment length (FL) were recorded. Results: In both single and double curvature canals, the Edge endo X7 files (9162.50 ± 441.14 and 2210.00 ± 341.07, respectively) demonstrated significantly higher resistance to cyclic fatigue than did the Race Evo FK (3866.66 ± 410.99 and 1825.00 ± 230.17, respectively) and Luster dent pliancy total solution (7077.77 ± 1001.84 and 1257.77 ± 126.95, respectively). However, in the double canal tests, the Luster dent pliancy total solution had a greater mean NCF than the Race Evo FK. In relation to the FL, there was no statistically significant difference between any of the groups, and only the edge of the Endo X7 file was significantly different between single- and double-curvature canals (P = 0.058). Conclusion: The Edge Endo X7 rotary file demonstrated greater cyclic fatigue resistance than did the Race Evo FKG and Luster dent pliancy total solution.

Background: Comprehending how bacteria adhere to different materials is essential for ensuring the long-term success of dental restorations. Various types of ceramic dental materials with distinct chemical and mechanical properties have been developed for this purpose. Therefore, this in vitro study aimed to investigate bacterial inhibition on E-max and zirconia disks after different surface treatments. Materials and Methods: Forty discs of zirconia and 40 discs of lithium disilicate-pressed E-max were prepared with standardized dimensions. Each main group was divided into two subgroups (20 for each). One subgroup was subjected to polishing and glazing, while the second one was not. After thermocycling, discs in each subgroup were placed on the bacteria culture plates containing either Streptococcus mutans (S. mutans) or Escherichia coli (E. coli). Results: The zirconia polishing group achieved the greatest bacterial inhibition, followed by the polished E-max group. The glazed zirconia and glazed E-max groups had lower values and highly significant differences were found. Conclusion: Bacteria were more inhibited in the polished groups than in the glazed groups of both zirconia and E-max.

Peracetic acid (PAA) is widely used as a sterilizing/disinfecting agent, and, in endodontics, it has been introduced as a promising irrigant in root canal treatment. It has been used at different concentrations to achieve various functions. However, endodontic instruments in contact with PAA of a certain concentration may affect their fatigue resistance. Therefore, the aim of this study was to investigate the impact of PAA on the cyclic fatigue resistance of three commercial heat-treated nickel-titanium (NiTi) rotary files. Three types of heat-treated NiTi rotary files were selected: One Curve (OC), ProTaper Gold (PTG), and Wave One Gold (WOG). Each type was divided into three subgroups (n = 6 for each file type): (1) untreated instruments; (2) files immersed in 0.002% PAA; and (3) files immersed in 0.35% PAA. The performance of each file type was tested in a simulated canal. The number of cycles to fracture (NCF) was determined to assess cyclic fatigue resistance of the files. Independent sample t-test was applied to compare each treated file within a subgroup with its respective control group, and one-way ANOVA was used for comparison among the main groups. All types of tested files revealed a significant decline in the cyclic fatigue resistance after exposure to 0.002% PAA except the PTG ( ). After exposure of the files to a higher concentration (0.35% PAA), a dramatic reduction was demonstrated by all the groups. Before and after exposure of the files to PAA, PTG displayed the highest cyclic fatigue resistance, followed by the WOG, while the OC showed the lowest resistance. Exposure of heated-treated NiTi files to PAA in a relatively high or low concentration adversely affects the cyclic fatigue resistance. The PTG files demonstrated the best performance among the tested types and can be disinfected with 0.002% PAA for clinical purpose.

Biodentine is a calcium silicate cement (CSC) that has been broadly applied in vital pulp therapy. The quality of the Biodentine-composite bond has a significant effect on the longevity of the definitive restoration. The aim of this study is to investigate the shear bond strength (SBS) between Biodentine and composite restoration at different maturation times of Biodentine aged in artificial saliva. Fifteen Biodentine discs were allocated into three groups (n = 5) based on the timeframe of performance of composite restoration: immediate (after 12 min), after 14 days, and after 28 days of Biodentine maturation. Total etch and rinse adhesive system and bulk-fill regular resin composite were used. The shear bond strength and the failure pattern were assessed. One-way ANOVA with the Bonferroni post hoc test was applied for statistical analysis at . The highest (32.47 ± 8.18 MPa) and the lowest (4.08 ± 0.81 MPa) SBS values were recorded for 14 days and 12 min groups, respectively. Significant statistical differences were reported among the groups, and a high statistically significant difference was found between the immediate group and the other groups. Adhesive failure patterns were evident in all groups. More clinically acceptable bond strength between the Biodentine and overlaid composite restoration is at 14 days after Biodentine maturation. Delaying the coverage of Biodentine later than 14 days may significantly reduce the SBS. Using the artificial saliva as an aging medium may affect the SBS between Biodentine and composite material.

The aim of this study was to see the effect of Er:YAG laser irradiation in dentine and compare this with its effect in enamel. The mechanism of crack propagation in dentine was emphasised and its clinical implications were discussed.

The aim was to investigate the effect of the Er‐YAG laser radiation on morphology and chemical composition of enamel, dentin, and bone. The specimens of the three groups were irradiated with a very long pulse mode (VLP) of 2.94 µm Er‐YAG laser with 100 mJ pulse energy and energy density of 8.42 J/ for 30 s, at a repetition rate of 15 Hz. The organic and inorganic content of the samples were investigated by Fourier Transforms Infrared spectroscopy (FTIR). The morphological characteristics were investigated with scanning electron microscopy (SEM) and elemental analysis (calcium and phosphorus) with energy‐dispersive X‐ray spectroscopy (EDX). FTIR data were analyzed with a One‐Way ANCOVA test and EDX data with the independent sample t‐test. Following the laser radiation, FTIR showed a significant decrease in the organic content of all tissues. The weight percentage (wt %) calcium content of dentin and bone increased significantly following irradiation with a p‐value of .002 for both tissues, but the wt % of phosphorus content was not influenced significantly. The morphological alterations expressed signs of fusion in all the samples.