Effect of surface treatments on push-out bond strength of calcium silicate-based cements to fiber posts.

BACKGROUND: To evaluate the effect of surface treatments on the push-out bond strength of Biodentine (BD) and white mineral trioxide aggregate (WMTA) to fiber posts. METHODS: Two brands of fiber posts were used: Reblida post; RP and RelyX post; RX. Each type of post (n = 80/group) was divided into four groups (n = 20/group) and exposed to surface treatment as follows: Control (no treatment), sandblasting (SB), hydrofluoric acid (HF), and TiF4 4 wt/v%. Each group was further subdivided into two subgroups (n = 10/subgroup) based on the type of CSCs used as follows: Subgroup A: BD and Subgroup B: WMTA. Push-out bond strength of BD and WMTA to glass fiber posts was assessed. Data were statistically analyzed using three-way ANOVA and Tukey's test. A Weibull analysis was performed on the push-out bond strength data. RESULTS: BD showed higher bond strength than WMTA (P < 0.001). The push-out bond strength for posts treated with TiF4 4 wt/v% showed greater bond strength than the other surface treatments (P < 0.05). The BD/RP-TiF4 4 wt/v% showed the greater characteristic bond strength (σ0) (15.93) compared with the other groups. Surface treatments modified the surface topography of glass fiber posts. CONCLUSIONS: The BD/RP-TiF4 4 wt/v% showed greater bond strength compared with the other groups. The TiF4 4 wt/v% surface treatment enhanced the bond strength of BD and WMTA to glass fiber posts than the other treatments. Surface treatment of fiber post with TiF4 4 wt/v% could be used to improve the bond strength with calcium silicate-based cements.

In vitro comparison of cyclic fatigue resistance of TruNatomy in single and double curvature canals compared with different nickel-titanium rotary instruments.

BACKGROUND: The purpose of this study was to compare the cyclic fatigue resistance of newly developed TruNatomy instruments (TRN) in single and double (S-shaped) curvature canals with HyFlex CM (HCM), Vortex Blue (VB) and RaCe (RC) instruments. METHODS: Size 20/.04 taper and size 25/0.04 of HCM, VB and RC were used. For TRN instruments, size 20/.04 taper (small) and size 26/.04 taper (prime) were used. The instruments were tested in artificial canals with double curvature (coronal curve; 60° curvature, 5 mm radius and apical curve; 70° curvature and 2 mm radius) and single curvature (60° curvature, 5 mm radius). The number of cycles to failure (NCF) was recorded. Data were statistically analyzed by Kruskal-Wallis and Dunn's multiple comparison tests. Weibull analysis was performed on NCF data. Statistical significant was set at p < 0.05. RESULTS: TRN and HCM revealed higher NCF compared with the other instruments for both tested sizes in single and double curvature canals (p < 0.05). TRN and HCM showed no statistically significant difference in the NCF (p > 0.05). The probability of survival was higher for HCM and TRN instruments than VB and RC instruments. CONCLUSIONS: HCM and TRN instruments were more resistant to cyclic fatigue than VB and RC instruments in single and double curvature canals. HCM and TRN instruments were anticipated to survive with higher number of cycles than the other tested instruments. RC instrument had the lowest fatigue resistance than the other instruments.

Effectiveness of XP-endo Finisher, EndoActivator, and File agitation on debris and smear layer removal in curved root canals: a comparative study.

The purpose of this study was to assess the efficacy of the XP-endo Finisher (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) file on debris and smear layer removal in curved root canals in comparison to different irrigation regimens. Seventy-five freshly extracted human mandibular molar teeth with mesial root curved more than 20° were used in this study. The mesial root canals were mechanically prepared using the BT-Race rotary system (FKG Dentaire) and divided into five groups (n = 15) according to the following irrigation techniques: positive control, non-agitated, File agitation, XP-endo Finisher, and EndoActivator (Dentsply Tulsa Dental Specialities, Tulsa, OK, USA). Root canals were split longitudinally and evaluated by scanning electron microscopy. Five-grade scoring system was used to assess the presence of debris and smear layer at the coronal, middle, and apical regions. The XP-endo Finisher and EndoActivator groups revealed significantly lower debris and smear layer scores than the other groups at the coronal, middle, and apical regions (P < 0.05). There was no significant difference between XP-endo Finisher and EndoActivator groups (P > 0.05). The apical region had higher debris and smear layer scores compared with the coronal regions in all groups (P < 0.05), except for the positive control group; there was no significant difference between the three regions of the root canal (P > 0.05). Irrigation of curved root canals using XP-endo Finisher and EndoActivator methods appears to be more effective on debris and smear layer removal than the other tested groups.

Effect of surface treatments on the flexural properties and adhesion of glass fiber-reinforced composite post to self-adhesive luting agent and radicular dentin.

This study evaluated the effect of different surface treatments on the flexural properties and adhesion of glass fiber post to self-adhesive luting agent and radicular dentin. Seventy-five single-rooted human teeth were prepared to receive a glass fiber post (Reblida). The posts were divided into five groups according to the surface treatment: Gr C (control; no treatment), Gr S (silanization for 60 s), Gr AP (airborne-particle abrasion), Gr HF (etching with 9 % hydrofluoric acid for 1 min), and Gr M10 (etching with CH2Cl2 for 10 min). Dual-cure self-adhesive luting agent (Rely X Unicem) was applied to each group for testing the adhesion using micropush-out test. Failure types were examined with stereomicroscope and surface morphology of the posts was characterized using a scanning electron microscopy (SEM). Flexural properties of posts were assessed using a three-point bending test. Data were analyzed using ANOVA and Tukey's HSD test. Statistical significance was set at the 0.05 probability level. Groups treated with M10 showed significantly higher bond strength than those obtained with other surface treatments (P < 0.05). In general, improvements in bond strength (MPa) were found in the following order: M10 > C > S > AP > HF. Most failure modes were adhesive type of failures between dentin and luting agent (48.2%). SEM analysis revealed that the fiber post surfaces were modified after surface treatments. The surface treatments did not compromise the flexural properties of fiber posts. Application of M10 to the fiber post surfaces enhanced the adhesion to self-adhesive luting agent and radicular dentin.

Fracture resistance of simulated immature teeth filled with Biodentine and white mineral trioxide aggregate - an in vitro study.

BACKGROUND: The purpose of this study was to evaluate the long-term fracture resistance of simulated immature teeth filled with Biodentine (BD) and white mineral trioxide aggregate (WMTA) as pulp space barriers for regenerative endodontic procedures (REPs). MATERIALS AND METHODS: Sixty extracted human maxillary anterior teeth were divided into four groups of 15 teeth each. Positive control teeth received no treatment. The remaining teeth were prepared until a size 6 Peeso (1.7 mm) could be passed 1 mm beyond the apex. Then, an engineering twist drill of 3 mm diameter was used to extend the preparation of the canal 3 mm below CEJ. The root canals were irrigated and disinfected according to AAE considerations for REPs. The canals were filled with either BD or WMTA. The negative control canals were left unfilled. The coronal access cavities were restored with glass ionomer followed by composite resin. The teeth were placed in phosphate-buffered saline solution and stored for 12 months. Each specimen was then subjected to fracture testing using a universal testing machine. The peak load to fracture and the fracture resistance were recorded, and the data were analysed statistically. RESULTS: The positive control group had the highest fracture resistance and differed significantly (P < 0.05) from the other experimental groups. No significant difference was found between BD and WMTA (P > 0.05). CONCLUSIONS: Considering the risk of cervical root fracture for pulpless infected immature teeth treated with REPs, after 12 months, there was no difference between WMTA and BD regarding the resistance to root fracture.

Influence of QMix irrigant on the micropush-out bond strength of biodentine and white mineral trioxide aggregate.

PURPOSE: To evaluate the effect of QMix and other conventional endodontic irrigants on the micropush-out bond strength of Biodentine (BD) and white mineral trioxide aggregate (WMTA). MATERIALS AND METHODS: One hundred eighty midroot dentin slices with a thickness of 1.0 mm were prepared. BD and WMTA were placed inside the lumens of the root slices (n = 90). Then the specimens of each material were divided into 6 groups (n = 15) according to irrigation solution (saline, 5.25% NaOCl, 2% CHX, 17% EDTA, or QMix) immersed in the same for 30 min. For the control group, a wet cotton pellet was placed over the specimen. After that, the micropush-out bond strength was determined using a universal testing machine, and the bond failure mode was determined using a stereomicroscope. The morphological microstructures of specimens were evaluated with scanning electron microscopy (SEM). Data were analyzed using ANOVA and Tukey's post-hoc test. RESULTS: BD revealed higher bond strength than WMTA (p < 0.05). WMTA was significantly affected after exposure to 2% CHX solution. QMix irrigant did not compromise the bond strength of BD or WMTA. Most failures for BD were cohesive, while for WMTA, adhesive failures were the predominant type. A substantial change in the microstructure of BD and WMTA occurred after exposure to different irrigation solutions. CONCLUSIONS: QMix did not affect the bond strength of BD or WMTA. BD showed higher resistance than WMTA to dislodgement forces from root dentin.

Effectiveness of oral premedication of meloxicam, ketorolac, dexamethasone, and ibuprofen on the success rate of inferior alveolar nerve block in patients with symptomatic irreversible pulpitis: a prospective, double-blind, randomized controlled trial.

OBJECTIVE: The aim of this prospective, double-blind, randomized controlled trial was to compare the effect of oral premedication of meloxicam, ketorolac, dexamethasone, ibuprofen, or placebo on the success of inferior alveolar nerve blocks (IANB) of mandibular posterior teeth in patients experiencing symptomatic irreversible pulpitis. METHOD AND MATERIALS: Two hundred and fifty emergency patients in moderate to severe pain diagnosed with symptomatic irreversible pulpitis of a mandibular first or second molar randomly received, in a double-blind manner, identical capsules containing either meloxicam 7.5 mg, ketorolac 10 mg, dexamethasone 0.5 mg, ibuprofen 600 mg, or placebo 60 minutes before the administration of an IANB. Profound lip numbness was assessed after 15 minutes. Access cavities were then prepared and success of IANB was defined as no or mild pain (Heft-Parker visual analog scale recordings) during access preparation and root canal instrumentation. The data were analyzed using chi-square and Kruskal-Wallis tests. RESULTS: The overall success rates for the meloxicam 7.5 mg, ketorolac 10 mg, dexamethasone 0.5 mg, and ibuprofen 600 mg groups were 52%, 64%, 54%, and 58%, respectively, with no significant differences in success rates among the premedications groups (P > .05). However, the tested premedications revealed significant differences compared with the placebo group (32% success rate) (P < .05). CONCLUSION: Premedication with meloxicam, ketorolac, dexamethasone, and ibuprofen increased the efficacy of IANB in mandibular molars with symptomatic irreversible pulpitis. (Quintessence Int 2023;54:92-99; doi: 10.3290/j.qi.b3605097).

Effect of preoperative tramadol, ibuprofen, ibuprofen/acetaminophen on the anaesthetic efficacy of inferior alveolar nerve block in patients with symptomatic irreversible pulpitis.

The purpose of this double-blind clinical trial was to compare the effect of preoperative tramadol 50 mg, tramadol 100 mg, ibuprofen 600 mg, ibuprofen 600 mg/acetaminophen 1000 mg or placebo 60 min before the administration of inferior alveolar nerve blocks (IANB) of mandibular teeth in patients experiencing symptomatic irreversible pulpitis (SIP). Two hundred and fifty emergency patients diagnosed with SIP were randomly divided into five groups and received medications. Endodontic access was begun 15 min after completion of the IANB, and all patients had profound lip numbness. The Heft-Parker visual analogue scale was used to evaluate pain. Premedication with tramadol 100 mg significantly increased the success rate to 62% than the other groups (p < 0.05). The success rates of ibuprofen, ibuprofen/acetaminophen and tramadol 50 mg groups were not significantly different (p > 0.05). Premedication with tramadol 100 mg enhanced the anaesthetic success of IANB in mandibular molars with SIP.

Effect of Surface Treatment and Aging on Bond Strength of Composite Cement to Novel CAD/CAM Nanohybrid Composite.

PURPOSE: To evaluate the effect of surface treatments and aging on the bond strength of composite cement to a novel CAD/CAM nanohybrid composite. MATERIALS AND METHODS: Microtensile bond strength (µTBS) of a dual-curing composite cement (Bifix QM; BQ) to three CAD/CAM restorative materials (Grandio [GR], Vita Enamic [VE], and Lava Ultimate [LU]) was evaluated after different surface treatments. The surfaces of specimens received the following treatments: control (no treatment), sandblasting (SB), SB + silane (Ceramic Bond; CB), hydrofluoric acid (HF), HF + CB, TiF4 2 wt/v%, TiF4 2 wt/v% + CB, TiF4 4 wt/v%, and TiF4 4 wt/v% + CB. Half of the specimens in each group were aged. Surface topography and surface roughness were evaluated. Statistical analysis was conducted using ANOVA and Tukey's test. The Weibull analysis was conducted on µTBS data of aged groups. RESULTS: The µTBS was significantly affected by the type of CAD/CAM material, type of treatment, and aging (p < 0.001). Silane application significantly improved the µTBS (p < 0.05). The µTBS decreased significantly with aging (5000 thermocycles) (p < 0.05). BQ cement resulted in the highest µTBS to GR treated with TiF4 2% wt/v + CB compared to the other groups (p < 0.05). Aged GR/BQ treated with TiF4 2% wt/v + CB had the highest predicted µTBS (19 MPa). CONCLUSION: TiF4 2% wt/v followed by silane application enhanced the adhesion of GR/BQ and LU/BQ systems. On the other hand, HF surface treatment followed by silane application improved the adhesion of the VE/BQ system.

Dynamic cyclic and torsional fatigue resistance of TruNatomy compared with different nickel-titanium rotary instruments.

This study evaluated the dynamic cyclic and torsional fatigue resistance of recently introduced TruNatomy instruments (TRN) and compare with HyFlex CM (HFC), Vortex Blue (VB) and FlexMaster (FM) instruments. Size 20, 0.04 taper of TRN, HFC, VB and FM instruments was tested for dynamic cyclic and torsional fatigue resistance. Dynamic cyclic fatigue resistance was evaluated using an artificial canal with a radius of 5 mm and a 90° angle of curvature. The number of cycles to failure (NCF) was calculated. The dynamic torsional fatigue resistance was evaluated by holding a 5 mm of the tip of each instrument in a metal block with composite resin. Torsional fatigue resistance was recorded by counting the number of load applications before fracture for each instrument. The HFC instruments had greater fatigue resistance than VB, TRN and FM. FM had a higher resistance to torsional stress than TRN, HFC and VB instruments.

Bonding durability of titanium tetrafluoride treated glass fiber post with resin cement.

This study evaluated the effect of titanium tetrafluoride (TiF4) solution on the bond strength of glass fiber post to resin cement. The specimens were divided into eight groups according to the method of surface treatment performed. Flexural properties and microtensile bond strength (µTBS) were determined. Data were analyzed using two-way ANOVA and Tukey's post hoc tests. The highest µTBS achieved with the TiF4 (4 wt/v%-4 min) group compared with the other groups (p<0.05). This finding could be attributed to the effectiveness of TiF4 (4 wt/v%-4 min) on removing the surface layer of the resin matrix of fiber posts that provides more uncovered surface areas of posts which improved the micromechanical retention of the resin cement. Surface treatments did not affect the flexural properties of fiber posts (p>0.05). Surface treatment of fiber post with TiF4 (4 wt/v%-4 min) solution exhibited higher bond strength to resin cement compared with other surface treatments.

Effect of titanium tetrafluoride addition on the physicochemical and antibacterial properties of Biodentine as intraorfice barrier.

OBJECTIVE: To evaluate the influence of titanium tetrafluoride (TiF4) incorporation on the physicochemical and antibacterial properties of Biodentine (BD; Septodont, Saint Maur des Faussés, France) as an intraorfice barrier material. METHODS: Three different proportions of TiF4 powder were used with BD; 1wt%, 2wt%, and 3wt%; respectively. BD without TiF4 addition was used as the control group. The setting time (ST) was determined using Gillmore needle apparatus. Diametral tensile strength (DTS) and fracture resistance were measured in a universal testing machine. Solubility was assessed using mass variation after 7days water storage. The hardness test was conducted using Vickers microhardness tester. The antibacterial activity was assessed using direct contact test against Enterococcus faecalis. Radiopacity was assessed and expressed in thickness of aluminum. Surface topography and elemental composition of modified BD were also assessed. The pH of soaking water was measured up to 168h. Data of tested properties were analyzed using one-way analysis of variance, the paired t-test, two-way repeated measures analysis of variance, and Tukey post hoc tests (P<0.05). RESULTS: BD-incorporating 2wt% TiF4 revealed the highest surface microhardness, DTS, and fracture resistance compared with the unmodified group (P<0.001). Higher concentrations of TiF4 (3wt%) compromised the solubility and prolonged the ST of BD (P<0.05). Bacterial growth of BD-incorporating TiF4 was significantly reduced when compared with the control group (P<0.05). The tested materials induced alkalization of the soaking water that decreased with time. SIGNIFICANCE: Biodentine-incorporating TiF4 (1wt% and 2wt%) is a promising intraorfice barrier material with enhanced physicochemical and antibacterial properties.

Cyclic Fatigue Resistance of One Curve, 2Shape, ProFile Vortex, Vortex Blue, and RaCe Nickel-Titanium Rotary Instruments in Single and Double Curvature Canals.

INTRODUCTION: The aim of this study was to evaluate and compare the resistance to cyclic fatigue of the new One Curve (OC) instrument in double (S-shaped) and single curvature canals compared with other nickel-titanium rotary instruments. METHODS: Size 25/.06 of OC, 2Shape (TS), Vortex Blue (VB), ProFile Vortex (PV), and RaCe (RC) instruments were tested inside artificial canals with a single curvature (60° curvature, 5 mm radius) and double curvature (coronal curve, 60° curvature, 5 mm radius; and apical curve, 70° curvature and 2 mm radius) while immersed in saline at 37°C ± 1°C. The number of cycles to failure (NCF) was calculated, and the fracture surface was examined by using a scanning electron microscope. The data of NCF and fragment length were analyzed by using one-way analysis of variance and Tukey post hoc tests. The t test was performed between the data of fragment length in different curvatures. The level of significance was set at P < .05. RESULTS: The VB instrument had a significantly higher NCF compared with the other instruments in double (S-shaped) and single curvature canals (P < .05). There was no significant difference between OC and TS in the NCF in single, apical, and coronal double curvature canals (P > .05). The lowest NCF values were recorded for RC instrument in all curvatures (P < .05). CONCLUSIONS: The fatigue resistance of VB was greater than that of other instruments. OC and TS instruments displayed superior cyclic fatigue resistance than PV and RC instruments.

Evaluation of root canal transportation, centering ratio, and remaining dentin thickness of TRUShape and ProTaper Next systems in curved root canals using micro-computed tomography.

OBJECTIVE: To evaluate and compare the volume of removed dentin, transportation, and centering ability of TRUShape (TRS; Dentsply Tulsa Dental Specialties) system with ProTaper Next (PTN; Dentsply Maillefer) by using micro-computed tomography (µCT). METHOD AND MATERIALS: Twenty extracted human mandibular first molars with two separate mesial canals with curvatures of 25 to 35 degrees were divided into two experimental groups (n = 20) according to the rotary nickel-titanium file system used in canal instrumentation as follows: group TRS and group PTN. Canals were scanned before and after instrumentation using µCT to evaluate root canal transportation, centering ratio, and volumetric changes. Data of canal transportation and centering ratio values were analyzed using independent t test. Volume changes data were statistically analyzed using Mann-Whitney test. Statistical significance level was set at P < .05. RESULTS: The PTN group had a significantly lower mean volume of removed dentin (2.09 ±â€¯0.41 mm3) than the TRS group (2.77 ±â€¯0.72 mm3) (P < .05). At the coronal level, there was no significant difference in canal transportation (P = .170) and centering ratio (P = .111) between TRS and PTN groups. However, at the apical and middle levels, the PTN group had a significantly lower mean transportation value and higher centering ratio than the TRS group (P < .05). CONCLUSION: Root canal preparation with the PTN system revealed better performance with fewer canal aberrations than the TRS system in curved root canals.

Shaping ability of ProTaper Gold and ProTaper Universal files by using cone-beam computed tomography.

CONTEXT: This study evaluated and compared the shaping ability of ProTaper Gold (PG) (PG; Dentsply, Tulsa Dental Specialties, Tulsa, OK, USA) system with ProTaper Universal (PU) (PU; Dentsply Maillefer, Ballaigues, Switzerland) using cone-beam computed tomography (CBCT) imaging. MATERIALS AND METHODS: Forty mesiobuccal canals of mandibular first molars with curvatures of 25-30° were divided into two experimental groups (n = 20) according to the rotary nickel-titanium (NiTi) file system used in canal instrumentation as follows: Group PG and group PU. Canals were scanned before and after instrumentation using CBCT scanner to evaluate root canal transportation and centering ratio at 3, 5, and 7 mm from the apex and volumetric changes. Data were statistically analyzed using independent t-tests and the significance level was set at P < 0.05. RESULTS: There was no significant difference between PG and PU systems in the mean volume of removed dentine, canal transportation, and centering ratio (P > 0.05). CONCLUSIONS: The PG and PU NiTi rotary systems showed similar root canal shaping abilities in the preparation of mesial canals of mandibular first molars.

Mechanical properties of zirconia reinforced lithium silicate glass-ceramic.

OBJECTIVE: The aim of this study was to assess the mechanical properties of recently introduced zirconia reinforced lithium silicate glass-ceramic. METHODS: Two types of CAD/CAM glass-ceramics (Vita Suprinity (VS); zirconia reinforced lithium silicate and IPS e.max CAD (IC); lithium disilicate) were used. Fracture toughness, flexural strength, elastic modulus, hardness, brittleness index, and microstructures were evaluated. Data were analyzed using independent t tests. Weibull analysis of flexural strength data was also performed. RESULTS: VS had significantly higher fracture toughness (2.31±0.17MPam(0.5)), flexural strength (443.63±38.90MPa), elastic modulus (70.44±1.97GPa), and hardness (6.53±0.49GPa) than IC (P<0.001). On the other hand, VS glass-ceramic revealed significantly a higher brittleness index (2.84±0.26µm(-1/2)) (lower machinability) than IC glass-ceramic (P<0.05). VS demonstrated a homogeneous fine crystalline structure while, IC revealed a structure with needle-shaped fine-grained crystals embedded in a glassy matrix. The VS glass-ceramic revealed a lower probability of failure and a higher strength than IC glass-ceramic according to Weibull analysis. SIGNIFICANCE: The VS zirconia reinforced lithium silicate glass-ceramic revealed higher mechanical properties compared with IC lithium disilicate glass-ceramic.

Torsion and bending properties of OneShape and WaveOne instruments.

INTRODUCTION: The purpose of this study was to compare the torsion and bending properties of OneShape (OS; Micro Mega, Besançon, France) and WaveOne (WO; Dentsply Maillefer, Ballaigues, Switzerland) single-file systems. METHODS: The torsional strength of OS size #25, 0.06 taper and WO primary size #25, 0.08 taper was measured by using a torsiometer after fixing the apical 5 mm of the instrument rigidly. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of broken files. The files were tested for bending resistance by using the cantilever bending test. Data were statistically analyzed using the independent t test. Statistical significance level was set at P < .05. RESULTS: WO had a significantly higher torsional resistance than OS (P < .001). The average bending resistance as measured by the maximum force (gf) to bend instruments revealed that the WO had a significantly lower resistance to bend than OS (P < .001). Scanning electron microscopic analysis of the fractured cross-sectional surfaces revealed typical features of torsional failure including skewed dimples near the center of the fracture surface and circular abrasion streaks. CONCLUSIONS: The WO single-file system showed higher torsional resistance and flexibility than the OS single-file system. Different cross-sectional geometry and the alloy from which the instrument is manufactured could have significant influence on the torsional resistance and flexibility of the instruments.

Cyclic fatigue resistance of OneShape and WaveOne instruments using different angles of curvature.

This study compared the cyclic fatigue resistance of OneShape (OS) instrument which used continuous rotation with WaveOne (WO) instrument which used reciprocating motion. OS size 25, 0.06 taper and WO primary size 25, 0.08 taper were used in simulated canals with 45°, 60°, and 90° angles of curvature until fracture. The number of cycles to fracture (NCF) was recorded to evaluate cyclic fatigue resistance. Data were statistically analyzed using two-way analysis of variance and Tukey's HSD test. Weibull analysis was performed on NCF data. WO had a significantly higher NCF than OS for all angles of curvature (p<0.05). According to Weibull distribution, WO instrument was predicted to have a higher number of cycles to survive than OS instrument. WO instrument which used the reciprocating motion had a greater resistance to cyclic fatigue than OS which used continuous rotation movement.

Influence of acidic environment on properties of biodentine and white mineral trioxide aggregate: a comparative study.

INTRODUCTION: The purpose of this study was to evaluate the surface microhardness, compressive strength, bond strength, and morphologic microstructures of Biodentine (BD; Septodont, Saint Maur des Fossés, France) and white mineral trioxide aggregate (WMTA) after exposure to a range of acidic pH levels. METHODS: For each test, 4 groups of each material were exposed to pH values of 7.4, 6.4, 5.4, and 4.4, respectively, for 7 days. The surface hardness was determined using Vickers microhardness. The compressive strength and micro-push-out bond strength were determined using the universal testing machine at a crosshead speed of 0.5 mm/min. The morphologic microstructures of specimens were evaluated using scanning electron microscopy. RESULTS: BD showed higher surface hardness, compressive strength, and bond strength to root dentin compared with WMTA after exposure to different pH values. A substantial change in the microstructure of BD and WMTA occurred after exposure to different pH values. WMTA appeared to be more sensitive to acidic pH environments than BD. CONCLUSIONS: BD material seems more appropriate for use when exposed to an acidic environment compared with WMTA.

Evaluation of root canal transportation, centering ratio, and remaining dentin thickness associated with ProTaper Next instruments with and without glide path.

INTRODUCTION: The purpose of this study was to evaluate and compare the volume of removed dentin, transportation, and centering ability of ProTaper Next (PTN) system with and without glide path preparation by using cone-beam computed tomography (CBCT) imaging. METHODS: Sixty mesiobuccal canals of mandibular first molars with curvatures of 25°-35° were divided into 3 experimental groups (n = 20) according to the instrumentation technique as follows: group PG/PTN (glide path was created with ProGlider [PG]) and canals were shaped with PTN system), group PF/PTN (glide path was created with PathFile [PF]) and canals were shaped with PTN system), and group PTN (glide path was not performed and canals were shaped with PTN system only). Canals were scanned before and after instrumentation by using CBCT scanner to evaluate root canal transportation and centering ratio at 3, 5, and 7 mm from the apex and volumetric changes. Data were statistically analyzed, and the significance level was set at P < .05. RESULTS: There was no significant difference among the tested groups regarding the volume of removed dentin and centering ratio (P > .05). At 3-mm and 5-mm levels, the PG/PTN group showed a significantly lower mean transportation value among the groups (P < .05). However, at 7-mm level, there was no significant difference in canal transportation among the groups (P > .05). CONCLUSIONS: PG/PTN instrumentation method revealed better performance with fewer canal aberrations when compared with instrumentation performed with PF/PTN or PTN only.