Effects of bone type and occlusal loading pattern on bone remodeling in implant-supported single crown: A finite element study.

PURPOSE: To assess the influence of bone types and loading patterns on the remodeling process over 12 months according to the variations in stress, strain, strain energy density (SED), and density allocation in the bone of implant-supported single crown. MATERIALS AND METHODS: A three-dimensional finite element of a single crown implant was modeled in five different bone types (D1-D4, and grafted bone). A 200 N load was applied on an implant crown with three occlusal loading patterns (nonfunctional contact, functional contact at center, and at 2-mm offset loading). During the first 12 months after implant placement, the SED was employed as a mechanical stimulus to simulate cortical and cancellous bone remodeling. RESULTS: Functional contact at 2-mm offset loading led to a higher bone remodeling rate and stress compared to functional contact at center and nonfunctional contact. Under 2-mm offset loading, the greatest remodeling rate after 12 months was achieved with D3 and D4, D2, grafted, and D1 cortical bone with an average peri-implant density of 1.95, 1.77, 1.56, and 1.50 g/cm3 , respectively. Meanwhile, the highest von Mises stresses were found in D4 (22.2 MPa) and D3 (21.9 MPa) bones. CONCLUSIONS: A greater stress concentration and remodeling rate were found when an off-axial load was applied on an implant placed in low bone density. Although the fastest remodeling processes resulting in increased bone density and strength were found in D3 and D4 bone types with greater off-axial loading that may provide greater bone engagement, it could increase stress concentrations that are susceptible to inducing implant failure.

Effectiveness of surface treatment on bond strength of ceramic brackets to two types of CAD/CAM-prepared nanohybrid composites.

OBJECTIVES: The aim of this study was to assess the influence of surface treatment on the shear bond strength of two different adhesive-coated orthodontic ceramic brackets to computer-aided design/computer-aided manufacturing (CAD/CAM) nanohybrid composite. METHODS: A total of 120 specimens (10 mmâ€¯× 10 mmâ€¯× 3 mm) were prepared from each type of CAD/CAM block (Grandio [GR], VOCO Cuxhaven, Germany; Lava Ultimate [LU], 3M ESPE, St. Paul, MN, USA). For each type of CAD/CAM block, the plates were divided into four groups based on the applied surface treatment: hydrofluoric acid (HF), grinding bur (GB), silica coating with CoJet system (CS), and titanium tetrafluoride (TiF4) 2 wt/v%. Maxillary central incisors of adhesive-coated ceramic orthodontic brackets (APC Flash-free Clarity Advanced Ceramic, 3M Unitek, Monrovia, CA, USA) were bonded using Transbond XT Primer (3M Unitek, Monrovia, CA, USA). Shear bond strength was conducted, and the modes of failure were assessed utilizing the adhesive remnant index. Surface roughness and topography of treated CAD/CAM were evaluated. Data were statistically analyzed using two-way analysis of variance (ANOVA) and Tukey's test. The Weibull analysis was conducted on shear bond strength data. RESULTS: Surface treatment with 2% TiF4 wt/v revealed significantly higher bond strength (GR, 14.51 ± 2.57 MPa; LU, 11.19 ± 2.17 MPa) than other groups for both types of CAD/CAM restorative materials (p < 0.05). Adhesive failures were the predominant mode of failure. Surface treatment with CS revealed higher surface roughness than other groups (p < 0.05). CONCLUSIONS: Surface treatment with 2% TiF4 wt/v enhanced the adhesion between orthodontic ceramic brackets to GR and LU CAD/CAM composite restorative materials. GR CAD/CAM nanohybrid composite had higher bond strength than LU to ceramic orthodontic brackets.

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.

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 Different Customized Abutment Types on Stress Distribution in Implant-Supported Single Crown: A 3D Finite Element Analysis.

PURPOSE: The purpose was to investigate stress distribution among 4 different customized abutment types: titanium abutment (Ti), titanium hybrid-abutment-crown (Ti-Hybrid), zirconia abutment with titanium base (Zir-TiBase), and zirconia hybrid-abutment-crown with titanium base (Zir-Hybrid-TiBase). MATERIALS AND METHODS: To achieve this purpose, 4 types of abutment configurations were simulated. A static load of 200 N (vertical) and 100 N (oblique) were applied to the models. The volume average, maximum, and stress distribution of von Mises stress, including percentage difference, were analyzed with 3D finite element analysis. RESULTS: According to the volume average von Mises stress, the Ti and Zir-TiBase comparison group showed that the Zir-TiBase group dominantly generated the higher value at Ti-base (22.57 MPa) and screw (17.68 MPa). To evaluate the effect of the hybrid-abutment-crown on volume average von Mises stress by comparing the Ti-Hybrid and Zir-Hybrid-TiBase groups, it was revealed that the combination of abutment and crown in the Ti-Hybrid group generated the worst stress concentration at the screw (12.42 MPa), while in the Zir-Hybrid-TiBase group presented stress concentration at the implant (8.90 MPa). CONCLUSIONS: A titanium base improved stress distribution at implant in zirconia abutment with titanium base by absorbing stress itself. Customized titanium hybrid-abutment-crown and zirconia hybrid-abutment-crown with titanium base created concentrated stress at screw and implant; respectively. Both abutment types should be cautiously used and maintenanced regularly.

Effect of staining beverages and bleaching on optical properties of a CAD/CAM nanohybrid and nanoceramic restorative material.

BACKGROUND: The purpose of this study was to evaluate the optical properties of nanohybrid Grandio (GR) and nanoceramic Lava Ultimate (LU) CAD/CAM restorative materials subjected to different beverage solutions and subsequently bleached. METHODS: Five groups of each restorative material (n = 20/group, shade A2-high translucent) were immersed in distilled water, coffee, tea, cola, and ginger for one week. Changes in whiteness index, translucency parameter, and color changes of the specimens were evaluated. The data of color measurements after staining, bleaching, and the residual differences were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at the significance level of P < 0.05. RESULTS: LU and GR revealed the highest differences in whiteness index after coffee staining (P < 0.001). GR revealed lower translucency parameter differences after staining with coffee than LU (P = 0.007). There were no significant differences in translucency changes between LU and GR after staining with tea, cola, or ginger (P > 0.05). LU revealed significantly greater color changes than GR after staining (P < 0.001). CONCLUSIONS: LU nanoceramic CAD/CAM restorative material revealed higher color changes than GR nanohybrid material. Staining beverage solutions had a distinct influence on the optical properties of the tested CAD/CAM restorative materials.

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.

Effect of gastric acids on surface topography and bending properties of esthetic coated nickel-titanium orthodontic archwires.

OBJECTIVE: The purpose of this study was to evaluate the effect of simulated gastric acid solution on surface topography and bending properties of esthetic coated nickel-titanium (NiTi) archwires. MATERIALS AND METHODS: Three brands of as-received white-coated superelastic NiTi upper archwires were used in this study: Dany, Perfect, and Nitanium. Uncoated metallic areas for each white-coated NiTi archwire were used for comparison with the coated areas. The specimens for each archwire were divided into two groups according to coating as follows: Group A, uncoated, and group B, coated. Then, each group was further subdivided into two subgroups according to the immersion medium as follows: Subgroup 1, immersed in artificial saliva, and subgroup 2, immersed in simulated gastric acid. Surface roughness, surface morphology, and three-point bending test were performed. The data were analyzed statistically using ANOVA and Tukey test. RESULTS: The archwires immersed in simulated gastric acid solution showed significantly higher surface roughness and lower forces on loading and unloading than the archwires immersed in artificial saliva (P < 0.001). Perfect archwire showed significantly the highest surface roughness compared with Dany and Nitanium archwires (P < 0.001). The uncoated archwires showed higher loading and unloading forces compared with coated archwires for all groups (P < 0.001). Nitanium archwire showed the lowest loading and unloading forces at different deflections (P < 0.001). CONCLUSIONS: The simulated gastric acid solution decreased considerably the amount of force applied at a given deflection. The loading-deflection and surface roughness properties of coated archwires were affected by the type of coating material. CLINICAL RELEVANCE: The impact of gastric acids on surface and mechanical properties of orthodontic archwires depend on type of coating materials.

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.

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.

Fracture resistance of simulated immature roots using Biodentine and fiber post compared with different canal-filling materials under aging conditions.

OBJECTIVE: The aim of this study was to evaluate the fracture resistance of simulated immature roots using Biodentine (BD) and fiber post (FP) compared with different root canal-filling materials under aging conditions. MATERIALS AND METHODS: One hundred and forty maxillary central anterior teeth were randomly divided into seven groups (n = 20/group). Negative control received no treatment. In the other groups, the root canals were prepared to simulate immature teeth. The root canals were filled with a 4-mm apical plug of BD and restored intraradicular with BD, BD + FP, composite resin (CR), CR + FP, and gutta-percha (GP). Positive controls were instrumented but without restoration. Teeth were subjected to thermocycling and received cyclic loading before fracture resistance test. Fracture resistance was conducted using a universal testing machine with a crosshead speed of 0.5 mm/min until fracture. Load to fracture was recorded in newtons (N). Data were statistically analyzed using one-way analysis of variance and Tukey's test at P < 0.05. RESULTS: Root canals restored intraradicular with BD + FP and CR + FP showed the highest fracture resistance compared with the other experimental groups (P < 0.001). There was no significant difference in the fracture resistance between CR and BD groups (P = 0.998). GP and positive control groups were significantly lower resistance to fracture than the other groups (P < 0.001). CONCLUSIONS: Intraradicular reinforcement with BD + FP and CR + FP enhanced the fracture resistance of simulated immature teeth than the other experimental groups. CLINICAL RELEVANCE: Biodentine or composite resin combined with fiber post could be used to reinforce immature teeth with an apical Biodentine plug.

Optical and Mechanical Properties of Newly Developed Monolithic Multilayer Zirconia.

PURPOSE: To evaluate the optical and mechanical properties of newly introduced monolithic multilayer zirconia with two types of monolithic zirconia. MATERIALS AND METHODS: Three brands of monolithic zirconia were used in this study: Ceramill Zolid FX Multilayer (CZF), Prettau Anterior (PA), and Zenostar T (ZT). Translucency parameter (TP), contrast ratio (CR), flexural strength, fracture toughness, hardness, brittleness index, and microstructures were assessed. Data were analyzed using one-way ANOVA and Tukey's test. The statistical significance was set at p < 0.05. A Weibull analysis was conducted on the flexural strength data. RESULTS: CZF revealed significantly higher TP and lower CR compared with PA and ZT monolithic zirconia (p < 0.05). ZT showed higher flexural strength and fracture toughness compared with CZF and PA (p < 0.001). On the other hand, CZF revealed significantly higher hardness values compared with PA and ZT (p < 0.001). CZF and PA revealed higher brittleness index than ZT monolithic zirconia (p < 0.001). ZT showed small grain microstructure while CZF and PA showed larger grains. ZT had a higher characteristic strength (σ0 ), Weibull modulus (m), and a lower probability of failure compared with CZF and PA. CONCLUSIONS: The optical and mechanical properties of the tested monolithic zirconia are material dependent. Fully stabilized monolithic zirconia materials (CZF and PA) are relatively more translucent than partially stabilized zirconia (ZT).

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.

Effectiveness of Titanium Tetrafluoride on the Bond Strength of Composite Cement to Titanium.

PURPOSE: To assess the influence of titanium tetrafluoride (TiF4) solution on the adhesion of composite cement to commercially pure titanium (cp Ti). MATERIALS AND METHODS: cp Ti plates with dimensions of 30 mm × 8 mm × 1.5 mm were machined and polished. The specimens were divided into seven groups according to the surface treatment as follows: group 1: control (machined); group 2: sandblasted with 110 µm Al2O3; group 3: hydrofluoric acid (HF); group 4: TiF4 (5%-5 min); group 5: TiF4 (5%-10 min); group 6: TiF4 (10%-5 min); and group 7: TiF4 (10%-10 min). One type of composite cement (Multilink Speed) was applied to each group for assessing the bond strength using strain energy release rate (G-value, J/m2) test. SEM analysis and surface roughness evaluation of cp Ti were carried out after treatment. The debonded specimens were examined with a stereomicroscope and SEM. Data were analyzed by the Kruskal-Wallis and Dunn's multiple comparison tests. Statistical significance was set at the 0.05 probability level. RESULTS: All the tested groups showed significantly higher bond strengths compared with the control group (p < 0.05). Surface treatment of cp Ti with TiF4 (10%-10 min) showed higher bond strength compared with sandblasting and HF groups (p < 0.05). Surface topography of treated cp Ti showed alterations in surface roughness and morphology. CONCLUSION: Adhesion between composite cement and cp Ti could be improved by using TiF4 (10%-10 min) solution prior to composite cement application as an alternative technique to sandblasting and HF.

Cyclic fatigue resistance of XP-endo Shaper compared with different nickel-titanium alloy instruments.

OBJECTIVE: The aims of this study were to assess and compare the resistance to cyclic fatigue of XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments with TRUShape (TRS; Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), HyFlex CM (HCM; Coltene, Cuyahoga Falls, OH, USA), Vortex Blue (VB; Dentsply Tulsa Dental Specialties), and iRace (iR; FKG Dentaire) nickel-titanium rotary instruments at body temperature. MATERIALS AND METHODS: Size 30, 0.01 taper of XPS, size 30, 0.04 taper of HCM, VB, iR, and size 30, 0.06 taper of TRS instruments were immersed in saline at 37 ± 1 °C during cyclic fatigue testing. The instruments were tested with 60° angle of curvature and a 3-mm radius of curvature. The number of cycles to failure (NCF) was calculated and the length of the fractured segment was measured. Fractographic examination of the fractured surface was performed using a scanning electron microscope. The data were analyzed statistically using Kruskal-Wallis H test and Mann-Whitney U tests. Statistical significance was set at P < 0.05. RESULTS: XPS had a significantly greater NCF compared with the other instruments (P < 0.001). The topographic appearance of the fracture surfaces of tested instruments revealed ductile fracture of cyclic fatigue failure. CONCLUSION: XPS instruments exhibited greater cyclic fatigue resistance compared with the other tested instruments. CLINICAL RELEVANCE: XP-endo Shaper instruments could be used more safely in curved canals due to their higher fatigue resistance.

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.

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.