Ahmed Jamleh

Adhesion of Epiphany Self-etch Sealer to Dentin Treated with Intracanal Irrigating Solutions

INTRODUCTION This in vitro study assessed the adhesion of Epiphany self-etch (SE) root canal sealer to dentin treated with different irrigation regimens. METHODS Flat dentin surfaces were obtained from human third molar teeth; smear layer was created on each sample. Five groups of 10 samples each were conditioned with one of the following regimens: (1) deionized water for 10 minutes; (2) 5% sodium hypochlorite (NaOCl) for 10 minutes; (3) 5% NaOCl for 10 minutes and then 10% sodium ascorbate (Na-Ascr) for 10 minutes; (4) 5% NaOCl for 10 minutes and then 2% chlorhexidine (CHX) for 5 minutes; or (5) 5% NaOCl for 10 minutes and then 10% Na-Ascr for 10 minutes, followed by 2% CHX for 5 minutes. The conditioned dentin surfaces were dried with absorbent paper points. The Epiphany SE sealer was placed on each dentin surface with the use of hollow stainless steel tubes with specific diameter and height. The samples were stored in 100% humidity at 37°C for 7 days and then tested for shear bond strength in a universal testing machine. RESULTS Shear bond strength data were analyzed by one-way analysis of variance and Tukey post hoc tests (P < .05). There were statistically significant differences among the groups. CONCLUSIONS NaOCl decreased the bond strength of Epiphany SE sealer to dentin, whereas the use of Na-Ascr reversed this negative effect of NaOCl. CHX had neither negative nor positive influence on the bond strength.

Nano-indentation testing of new and fractured nickel-titanium endodontic instruments

AIM To investigate the effect of cyclic fatigue on nickel-titanium (NiTi) endodontic instruments using a nano-indentation test. METHODOLOGY Eight ProFile NiTi rotary instruments (size 30, taper 0.06; Dentsply Maillefer, Ballaigues, Switzerland) were tested using a cyclic fatigue set-up until fracture. The fractured instruments and eight new NiTi instruments of the same size and taper were used for a nano-indentation test on the internal surfaces of a NiTi instruments in the region just adjacent to their fractured edge (group I) and in the same region of the new group (group II), and the cutting part beside the shaft for both instruments [group III (fractured) and group IV (new)]. Data were statistically analyzed using one-way analysis of variance and Games-Howell post hoc test. The alpha-type error was set at 0.05. RESULTS Significant differences in terms of hardness and elastic modulus for each group (P < 0.05) were found, with group I having the lowest mean values followed by group III. Additionally, standard deviations increased remarkably after failure, as represented by groups I and III. CONCLUSION The nano-indentation technique can be applied to determine the performance and the failure mechanism of NiTi instruments. The fatigue process revealed a significant decrease in the hardness and elastic modulus of the NiTi instrument. As indicated by the low hardness, the fatigue process did not result in work hardening but rather work softening.

Effect of nickel titanium file design on the root surface strain and apical microcracks

The aim of this study was to determine the effect of nickel titanium file design on the root surface strain generated and apical microcracks caused during canal shaping. Thirty-three mandibular incisors were distributed into LightSpeed X, FlexMaster and a control group. A strain gauge was fixed apically on the proximal root surface to determine the maximum strain during canal shaping. Except for the control group, all root canals were enlarged to size 50. Images were taken after removing the apical 1 and 2 mm of the root end. Mean maximum strain values and presence of microcracks were statistically compared using the t-test and chi-square test, respectively. During canal shaping, the strain increased cumulatively with mean maximum strains of 808.2 ± 228.8 and 525.1 ± 168.9 microstrain in LightSpeed X and FlexMaster, respectively (P = 0.004). Both systems caused comparable microcracks. Although LightSpeed X produced higher maximum strain, no difference in microcrack development was found between both systems.

Endodontic instruments after torsional failure: Nanoindentation test

This study aimed to evaluate effects of torsional loading on the mechanical properties of endodontic instruments using the nanoindentation technique. ProFile (PF; size 30, taper 04; Dentsply Maillefer, Switzerland) and stainless steel (SS; size 30, taper 02; Mani, Japan) instruments were subjected to torsional test. Nanoindentation was then performed adjacent to the edge of fracture (edge) and at the cutting part beside the shank (shank). Hardness and elastic modulus were measured under 100-mN force on 100 locations at each region, and compared to those obtained from the same regions on new instruments. It showed that PF and SS instruments failed at 559 ± 67 and 596 ± 73 rotation degrees and mean maximum torque of 0.90 ± 0.07 and 0.99 ± 0.05 N-cm, respectively. Hardness and elastic modulus ranged 4.8-6.7 and 118-339 GPa in SS, and 2.7-3.2 and 52-81 GPa in PF. Significant differences between torsion-fractured and new instruments in hardness and elastic modulus were detected in the SS system used. While in PF system, the edge region after torsional fracture had significantly lower hardness and elastic modulus compared to new instruments. The local hardness and modulus of elasticity of endodontic instruments adjacent to the fracture edge are significantly reduced by torsional loading.

Optical Evaluation of Enamel Microleakage with One-Step Self-Etch Adhesives

OBJECTIVE In this in vitro study, cross-polarization optical coherence tomography (CP-OCT) was used to evaluate microleakage in dental composite restorations bonded to enamel with two types of one-step self-etching (SE) adhesives. BACKGROUND DATA One-step SE adhesives were proposed to simplify bonding of composite restorations. However, bonding of these simplified adhesive to dental enamel is still questionable. OCT is a promising diagnostic tool that allows micron-scale imaging of biological tissues and structures. METHODS Class-V cavities (4-mm diameter × 1-mm depth) were prepared on the labial surfaces of extracted human anterior teeth with margins and floor located in enamel. The cavities were then divided into two groups (n = 5) and restored with either Tetric N-Bond Universal (Ivoclar Vivadent, Liechtenstein) or Palfique Bond (Tokuyama Dental Corporation, Japan), followed by Estelite Flow Quick flowable composite (Tokuyama Dental Corporation). After storage in 100% humidity for 24 h, specimens were immersed in ammoniacal silver nitrate solution for another 24 h. Later, they were rinsed and immersed in photo-developing solution under fluorescent light for 8 h. CP-OCT at 1310 nm center wavelength was used to scan seven two-dimensional cross-sectional images from each specimen. Each cross-sectional image was analyzed using ImageJ software to quantify interfacial microleakage at the cavity floor. RESULTS Students t-test showed significant difference between the tested adhesives (p < 0.05). Palfique Bond adhesive presented inferior interfacial adaptation as it obtained higher values of floor microleakage compared to Tetric N-Bond Universal adhesive group. CONCLUSIONS CP-OCT enabled nondestructive quantitative assessment of microleakage in enamel dental restorations.

Time sensitivity associated with the application of water-based all-in-one adhesive system

Abstract This in vitro study was performed to investigate effect of delayed composite application on dentin bonding durability of water-based all-in-one self-etch adhesive system using micro-tensile bond strength (MTBS) testing. Fifteen freshly extracted, non-carious premolar teeth were randomly selected. After removing the roots, the teeth were occlusally trimmed to expose superficial dentin. Then, the exposed occlusal dentin was bonded with a self-etching adhesive (Tetric-N Bond self-etch; Ivoclar/Vivdent) according to the manufacturer’s instructions. After that, the samples were divided equally into 3 groups based on the time of application of Tetric-N Ceram composite resin (Ivoclar/Vivdent, Liechtenstein). In group 1, the composite build-up was carried out immediately after curing the adhesive, and polymerized according to the manufacturer instructions. In groups 2 and 3, the samples were restored after 1 and 5 min following adhesive curing, respectively. After 24 h storage, each bonded sample was sectioned into beams (0.7 mm × 0.7 mm) for MTBS testing. Results of the MTBS were analysed and tested using one-way ANOVA and post hoc Tukey test at significance level of 5%. The results showed that applying composite restoration immediately after adhesive curing gave strength of 11 ± 6 MPa. Composite application after curing the adhesive by 1 and 5 min showed 16 ± 8 MPa and 11 ± 5 MPa, respectively. The 1 min delayed application group had significantly higher bond strength than the other tested groups (p > 0.05). In conclusion, delaying the composite application after polymerization of water-based all-in-one adhesive for 1 min showed better bond strength.

The Antifungal Effect of Propolis Endodontic Irrigant with Three Other Irrigation Solutions in Presence and Absence of Smear Layer: An In Vitro Study

Introduction: The aim of this in vitro study was to compare the antifungal effect of propolis as an endodontic irrigant agent with a mixture of doxycycline, citric acid, and a detergent mixture (MTAD), 2% chlorhexidine (CHX) and 3% sodium hypochlorite (NaOCl) against Candida albicans in presence and absence of smear layer. Methods and Materials: Extracted teeth with single canals (n=104) were prepared and randomly distributed into four experimental groups; 30% propolis, MTAD, 2% CHX and 3% NaOCl. Each group had two subgroups; with and without smear layer. The antifungal effectiveness was evaluated. The Kruskal-Wallis and Mann-Whitney tests were used to compare the overall effectiveness of different treatments at significance level of 0.05. Results: Propolis, CHX and NaOCl had similar levels of effectiveness to each other against C. albicans, and these levels were not affected by the presence or absence of the smear layer. Each irrigant was significantly more effective than MTAD or saline solution. MTAD was less effective in the presence of the smear layer than in its absence. Conclusions: Propolis irrigation can produce root canals that are free of C. albicans, even in the presence of the smear layer.

Effects of Sodium Hypochlorite Concentration and Temperature on the Cyclic Fatigue Resistance of Heat-treated Nickel-titanium Rotary Instruments

Introduction We tested the cyclic fatigue resistance of heat‐treated instruments immersed in sodium hypochlorite solution under different concentrations and temperature conditions. Methods Based on the irrigating solutions concentration and temperature, 135 ProTaper Gold (PTG; Dentsply Sirona, York, PA) F2 instruments were divided equally into 9 groups of 15. Cyclic fatigue testing was performed by using a block with artificial canals with a curvature angle of 60°, a curvature radius of 5 mm, and a curvature center 5 mm from the instrument tip. The block was fixed inside a water bath of distilled water, 2.5% sodium hypochlorite (NaOCl), or 5.25% NaOCl. The temperature was preset at 25°C, 37°C, or 60°C. The instrument was rotated at 300 rpm until fracturing occurred. The number of cycles to fracture was calculated, and the fragment length was measured. Fractured surfaces were examined via scanning electron microscopy. NCF data were analyzed statistically via Kruskal‐Wallis and Mann‐Whitney tests. All statistical analyses were performed using SPSS software Version 22 (IBM Corp, Armonk, NY) at a 5% significance level. Results The number of cycles to fracture of the PTG F2 was highest in distilled water at 25°C and lowest in 5.25% NaOCl at 60°C. Changing the irrigating solution from distilled water to NaOCl and increasing the surrounding temperature reduced the fatigue resistance. Conclusions NaOCl irrigating solution at different concentrations and temperatures influenced the cyclic fatigue resistance of PTG instruments. Future NiTi instrument failure studies should be conducted under simulated body temperature conditions in commonly used irrigating solutions. HighlightsIncreasing the temperature of the sodium hypochlorite (NaOCl) solution to body temperature and above significantly decreased ProTaper Golds resistance to cyclic fatigue.The irrigant solution and simulated body temperature should be considered in future nickel‐titanium instrument failure studies.The irrigant temperature and concentration were shown to play a vital role in the cyclic fatigue resistance of endodontic instruments manufactured with heat‐treated NiTi alloy.

Vertical Force Induced with WaveOne and WaveOne Gold Systems during Canal Shaping

Introduction The aim of this study was to evaluate the amount of vertical force induced with WaveOne (WO; Dentsply Sirona, York, PA) and WaveOne Gold (WOG, Dentsply Sirona) systems during the canal shaping of extracted teeth. Methods Thirty canals in 15 maxillary premolars were divided into 2 groups: WO and WOG. The canals were gently shaped with WO/WOG Primary instruments according to the manufacturers instructions. The vertical forces induced during canal shaping in the apical and coronal directions were recorded. The apically and coronally directed peak forces were used for analysis using the Mann‐Whitney U test. The instrumentation time was analyzed using the Student t test. All statistical analyses were performed using SPSS software (Version 22.0; IBM, Armonk, NY) at a 5% significance level. Results The force increased with the successive instrument insertions within each group. The apically and coronally directed peak forces of the WO and WOG groups ranged from 2.89–11.58 N and from 1.53–2.92 N, respectively. In the 3 insertions, WO showed higher peak forces in both directions. For apically directed peak forces, WO had significantly higher peak forces in the first and third insertions than WOG (P < .01). For coronally directed peak forces, WO had significantly higher values in the first and second insertions (P < .05). Conclusions The WOG system had significantly lower apically and coronally directed peak force values compared with the WO system. HighlightsThis study provided data on the vertical forces induced during the shaping of narrow canals with the WaveOne and WaveOne Gold systems.The WaveOne Gold Primary instrument had lower peak vertical forces compared with that induced with the WaveOne Primary instrument.The WaveOne Gold system can be used for the safe and efficient preparation of root canals.

Successive spreader insertion forces induced by undergraduate students during canal obturation

Introduction: To investigate the forces induced by successive spreader insertions by undergraduate dental students. Materials and Methods: Thirty-eight artificial resin teeth (Real-T Endo, Acadental, Lenexa, KS, USA) were used. After canal preparation, the teeth were distributed equally into male and female students to perform canal obturation with the lateral compaction technique. A force gauge (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY, USA) was used for recording the spreader insertion force. Linear mixed model was used to assess the effects of both gender and repeated measures of spreader insertion on spreader penetration forces during canal obturation at a significance level of 5%. Results: The mean maximum forces measured were in the range of 1.13 ± 0.44–1.67 ± 0.64 kg. There was a significant difference between the five insertion times (P = 0.003), and the initial three insertion times were lower than the fourth and fifth times. Although female students apply more force, there was no significant difference when compared to that of male students (P = 0.136). Conclusion: The force gauge device can be used as educational tool to measure the force applied during canal obturation. Although the forces applied by female students were higher than the male students, they were all considered safe.