Shear bond strength of composite resins to lithium disilicate ceramics using universal bonding and different methods of surface preparation.

Background: Porcelain fracture or chipping is one of the limitations of all ceramic restorations. This study investigated the shear bond strength (SBS) of composite resins to lithium disilicate ceramics using universal bondings and different methods of surface preparation. Materials and Methods: In this experimental study, 72 specimens of e.max computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic blocks were divided into six groups of 12 according to surface treatment: Group I-Hydrofluoric (HF) acid etching + All-Bond Universal bonding (ABU), Group II-Bur roughening (BR) + HF + ABU, Group III-BR + HF + Bis-Silane (Si) + ABU, Group IV-Sandblasting (SB) + ABU, Group V-SB + HF + ABU, Group VI-SB + HF + Si + ABU. After bonding of composite resin to the prepared ceramic surface and storage of samples in distilled water for 24 h, SBS test was done using the universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed using the analysis of variance and Tukey's post hoc test (α = 0.05). Results: The mean values of SBS in six studied groups were 6.65 ± 2.78 MPa, 8.56 ± 2.69 MPa, 8.49 ± 2.14 MPa, 3.13 ± 1.66 MPa, 7.94 ± 2.4 MPa, and 10.04 ± 2.47 MPa, respectively. The mean values of SBS were significantly different (P < 0.001). The highest value of SBS was observed in Group VI and the lowest in Group IV. Conclusion: Ceramic sandblasting followed by HF etching, Bis Si, and ABU resulted in a higher SBS of composite resins to lithium disilicate ceramics.

Marginal adaptation of zirconia complete-coverage fixed dental restorations made from digital scans or conventional impressions: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Intraoral scanners have been increasingly used in recent years. However, the accuracy of digital scans as it affects marginal adaptation is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to compare the marginal adaptation of single-unit zirconia crowns fabricated with digital scans or with conventional impressions. MATERIAL AND METHODS: The electronic databases PubMed (MEDLINE), Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science (ISI), Scopus, and EMBASE were searched and complemented by a manual search. Risks of bias were assessed by using a modified methodological index for nonrandomized studies (MINORS). Mean ±standard deviation (SD) values of marginal accuracy of studies were extracted for both methods. Mean marginal difference and 95% confidence interval (CI) were calculated to evaluate the marginal accuracy of each method. Pooled data were statistically analyzed by using a random-effect model. RESULTS: Seventeen studies were used to perform the meta-analysis. Subgroup analysis was performed based on intraoral scanners. Standardized mean marginal difference and 95% CI of each subgroup were as follows: Lava: -0.85 µm (95% CI: -1.67, -0.03) (P=.043); CEREC: -1.32 µm (95% CI: -2.06, -0.59) (P<.001); iTero: -0.44 µm (95% CI: -1.35, 0.47) (P=.338); TRIOS: -1.26 µm (95% CI: -2.02, -0.51) (P=.001); unknown scanner: -0.21 µm (95% CI: -1.14, 0.72); all studies: -0.89 µm (95% CI: -1.24, -0.54) (P<.001). CONCLUSIONS: Digital scanning of prepared teeth for single-unit zirconia restorations resulted in better marginal accuracy than conventional techniques using elastomeric impression materials.

A Comparative Study of Cervical Composite Restorations Microleakage Using Dental Universal Bonding and Two-step Self-etch Adhesive.

AIM: The aim of this study is to compare microleakage of cervical restorations using universal bonding and two-step self-etch adhesive with or without enamel etching through a dye penetration testing method. MATERIALS AND METHODS: In this in vitro experimental study, 70 maxillary premolar teeth with no anomaly or decay were randomly divided into five groups of 14. Conventional cervical cavities were prepared with diamond bur on the facial surface of the teeth. The teeth were prepared using G-Premio Bond/self-etch technique, G-Premio Bond/total-etch technique, G-Premio Bond/selective-etch technique, Clearfil SE Bond/self-etch technique, and Clearfil SE Bond/selective-etch technique in Groups I to V, respectively, and restored with composite. Microleakage at the occlusal enamel margin and the cervical dentinal margin was ranked from 0 to 4 based on dye penetration using stereomicroscope (×32). Statistical analysis was carried out using Kruskal-Wallis and Mann-Whitney tests at a significance level of α = 0.05. RESULTS: The mean occlusal microleakage in the five study groups was 1.07, 0.57, 0.57, 1.28, and 0.78, respectively. The mean cervical microleakage was 0.97, 0.85, 0.64, 1.35, and 1.14, respectively. Kruskal-Wallis test showed significant difference between the microleakage scores of different groups in enamel (p = 0.022) and dentin (p = 0.01). Clearfil SE Bond/self-etch technique group showed the highest mean score of microleakage in enamel margins, and G-Premio Bond/total-etch technique and G-Premio Bond/selective-etch technique groups showed lowest enamel microleakage mean. Clearfil SE Bond/self-etch group showed the highest mean score of microleakage in dentin margins, while G-Premio Bond/selective-etch technique group showed the lowest mean score of dentin microleakage. CONCLUSION: Selective etching of enamel will decrease enamel microleakage. G-Premio Bond shows better microleakage results in comparison to Clearfil SE Bond in dentinal margins. CLINICAL SIGNIFICANCE: A major problem in cervical composite restorations is the presence of microleakage in the cervical wall. Different adhesive systems have been designed to overcome this problem.

Management of Symptomatic Horizontal Mid-root Fractures after Unsuccessful Orthograde Endodontic Retreatments.

This case report describes the management of symptomatic horizontal mid-root fractures in previously traumatized central incisors, which initially had been treated endodontically and retreated afterwards. A 26-year-old female, who had suffered a traumatic injury to the maxillary anterior teeth, was referred owing to the failure of the corresponding orthograde endodontic retreatment and consequent pain/discomfort. Periapical radiographs and cone beam computed tomography showed that both central incisors had horizontal root fractures in their middle third, root canal fillings in their coronal segments, a considerable dislocation of the apical fragments and large radiolucent lesions between their apical segments and coronal fragments. Based on the obtained radiographic and clinical findings, a surgical endodontic retreatment approach for the main segments without removing the apical fragments was applied employing calcium-enriched mixture (CEM) cement as the retrograde biomaterial. Thirty-month clinical and radiographic follow-ups demonstrated successful outcomes. This case report showed the healing potential of horizontal mid-root fractures after surgical endodontics using CEM cement without removing apical fragments.

Management of merged external/internal root resorption using CEM cement: a case report

Chronic pulpal inflammation and infection are the main predisposing factors for internal and external root resorption (IRR & ERR); however, merging of IRR and ERR is a rare lesion which rigorously alters the anatomy of root canals. this study reports a case of merged IRR and ERR in an asymptomatic maxillary left central incisor in a 33-year old caucasian woman that was managed by one-visit root canal therapy (RCT) using calcium-enriched mixture (CEM) cement. radiographic examination showed a short root with under-filled root canal obturation associated with ERR/IRR and an apical lesion. after thorough chemo-mechanical preparation, the root canal was obturated with CEM cement; one week later, the access cavity was permanently restored. clinical/radiographic examinations at 1-year follow-up revealed uneventful healing, reestablishment of lamina dura and stabilization of the resorptive defects. the treatment outcome demonstrates that one-visit RCT using CEM cement may be a viable treatment option in cases with merged external/internal root resorption. further clinical trials with a larger number of cases are suggested to document a higher level of evidence.

Intra-manufacture Diameter Variability of Rotary Files and Their Corresponding Gutta-Percha Cones Using Laser Scan Micrometre.

INTRODUCTION: Manufacturers offer gutta-percha (GP) cones matched with different sizes of endodontic files as an attempt to simplify the obturation process and create a tight seal in the canal. The purpose of this study was to evaluate whether intra-manufacture GP diameters matched the diameters of their corresponding files at different levels using laser micrometre. METHODS AND MATERIALS: Twenty files and corresponding GP master cones of Reciproc R40 (40/0.06) (VDW, Munich, Germany), WaveOne Large(40/0.08)(Dentsply Maillefer, Ballaigues, Switzerland), ProTaper F3 (30/0.09) (Dentsply Maillefer, Ballaigues, Switzerland), and Mtwo 40/0.06 (VDW, Munich, Germany) were examined using laser micrometre (LSM 6000 by Mitutoyo, Japan) with accuracy of 1 nm to establish their actual diameter at D0, D1, D3 and D6. The data was analysed using the independent t-test. The differences were considered at 0.05. RESULTS: The diameter of GP master cones was significantly larger than that of the corresponding files at all levels in all brands. ProTaper GP diameter was closest to the file diameter at D1 (GP=0.35, File=0.35 mm), and D3 (GP=0.48, File=0.49). CONCLUSION: Within the same manufacturer, GP cone diameters do not match the diameters of their corresponding files. Clinicians are advised to use a GP gauge to cut the tip so as to appropriate the diameter from a smaller sized GP cone.

The Intra-Manufacture Diameter Variability of Rotary Files and Their Corresponding Gutta-Percha Cones Using Laser Scan Micrometer.

Introduction: As an attempt to simplify the obturation process and create a tight seal, manufacturers offer gutta-percha (GP) cones matching different sizes of endodontic files. The purpose of this study was to evaluate whether intra-manufacture GP diameters matched the diameters of their corresponding files at different horizontal levels of the canal. Methods and Materials: Twenty files and corresponding GP master cones of Reciproc R 40/0.08 (VDW, Munich, Germany), WaveOne Large (40/0.08) (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper F3 (30/0.09) (Dentsply Maillefer, Ballaigues, Switzerland), and Mtwo (40/0.06) (VDW, Munich, Germany) were examined using laser micrometer (LSM 6000 by Mitutoyo, Japan) with accuracy of 1 nm to establish their actual diameter at D0, D1, D3 and D6. Data were analysed using the independent t-test. The differences were considered as significant for P<0.05. Results: The diameter of GP master cones was significantly larger than the corresponding files at all levels with all the above brands. ProTaper GP diameter were closest to the file diameter at D1 (GP=0.35, File=0.35 mm), and D3 (GP=0.48, file=0.49). Conclusion: This in vitro study showed that within the same manufacturer GP cone diameters do not match the diameters of their corresponding files.

Feasibility of Cone-beam Computed Tomography in Detecting Lateral Canals before and after Root Canal Treatment: An Ex Vivo Study.

INTRODUCTION: The study objective was to evaluate the effectiveness of cone-beam computed tomographic (CBCT) imaging for the detection of lateral canals (LCs) in endodontically treated premolars. METHODS: Two evaluators classified 80 extracted premolars into 2 groups based on the absence (n = 40) or presence (n = 40) of LCs according to micro-computed tomographic analysis. The extracted teeth were fixated in a human mandible and scanned with CBCT imaging. Subsequently, each tooth was endodontically treated, and CBCT scans were repeated. Three experienced examiners evaluated all images randomly. Receiver operating characteristic curves were compared using the McNemar test, and sensitivity, specificity, positive predictive value, and negative predictive value (NPV) were obtained. RESULTS: The area under the receiver operating characteristic curve values were 0.58 and 0.49 before and after root canal treatment, respectively. These values were statistically significantly different (P < .001). Before root canal treatment sensitivity, specificity, positive predictive value, and negative predictive value were 55%, 52%, 55%, and 56%, whereas after root canal treatment the values were 33%, 61%, 46%, and 48%, respectively. CONCLUSIONS: LC detection in nontreated teeth presented low accuracy, whereas among treated teeth CBCT imaging showed no efficacy. The results suggest that CBCT imaging is not an effective diagnostic tool for LC detection.

Accuracy of Cone-beam Computed Tomography in the Detection of a Second Mesiobuccal Root Canal in Endodontically Treated Teeth: An Ex Vivo Study.

INTRODUCTION: There is a high incidence of a second mesiobuccal root canal (MB2) in maxillary molars. The study aim is to assess the accuracy of cone-beam computed tomographic (CBCT) imaging in detecting a second mesiobuccal root canal in endodontically treated maxillary molars. METHODS: The study sample consisted of 60 extracted maxillary molars, which were endodontically opened and examined under a dental operating microscope for the presence of an MB2. The teeth were then further examined using micro-computed tomographic imaging as the gold standard. Root canals were filled (except the MB2) and were then subdivided into an experimental and a control group. After fixing the teeth in a dry human skull, they were scanned using CBCT imaging (AccuiTomo 170; Morita Inc, Tarumi-cho Suita City, Osaka, Japan). The observers for this study were 2 experienced radiologists blinded to the group allocation of controls and experiments; they evaluated the images twice independently. Sensitivity, specificity, and accuracy were calculated as well as the kappa values for both inter- and intraobserver agreement. RESULTS: From 30 teeth, which were diagnosed without an MB2 under examination with a dental operating microscope, 6 teeth proved to have an MB2 using µCT (20%). Intraobserver reliability was high for both observers 1 (R = 0.85) and 2 (R = 0.96). Interobserver reliability as assessed by the Cohen kappa was excellent (R = 0.89). CBCT sensitivity for detecting an MB2 was 96%, specificity was 100%, and total accuracy was 98%. CONCLUSIONS: CBCT imaging is a suitable diagnostic technique for detecting a missed MB2 in endodontically treated teeth.

Effect of Adhesive Resin Type for Bonding to Zirconia Using Two Surface Pretreatments.

PURPOSE: This laboratory study evaluated the short-term adhesive properties of one 10-MDP-containing and two MDP-free resin composite cements, using two types of zirconia surface pretreatments. MATERIALS AND METHODS: Eighteen sintered zirconia disks (Procera, Nobel Biocare) were randomly divided into three study groups according to their surface treatment: (a) polished surface (control group); (b) airborne-particle abraded (grit blasted) with 50-µm aluminum trioxide (APA); and (c) selective infiltration etching (SIE). The zirconia disks were then bonded to 180 pre-aged composite resin disks (0.9 mm×0.7 mm) using three different resin composite cements (Panavia F2.0, Esthetic, and Aegis). Resin-zirconia adhesion strength was evaluated using the microshear bond strength test (µSBS) after 24 h (baseline) and 2 weeks of storage in deionized water at 37°C. Three-way ANOVA, one-way ANOVA, and Scheffé's post-hoc tests were used to analyze the data (p=0.05). RESULTS: Surface treatments significantly influenced the µSBS (p<0.001). The highest mean µSBS values were recorded with the MDP-containing resin composite cement (Panavia F2.0) in both SIE (32.4±5.3 MPa) and APA (28.6±8.8 MPa) groups. Water storage significantly reduced the bond strength obtained with the MDP-free cements (Esthetic and Aegis) and in the control group, while the bond strength in SIE and APA groups using the 10- MDP-containing resin composite cement exhibited relatively unchanged values. CONCLUSION: SIE and APA in combination with the 10-MDP-containing resin composite cement established a strong, durable bond to zirconia substrates under short-term aging conditions. The cement containing amorphous calcium phosphate (Aegis) did not bond to zirconia surfaces. During the observation period, µSBS decreased significantly due to hydrolytic degradation, except when the 10-MDP-containing resin composite cement (Panavia F2.0) was used in the SIE and APA groups.

Effect of a two-step placement procedure on the dislocation resistance of a methacrylate resin-based root canal sealer: a proof of concept.

PURPOSE: To investigate whether the placement of a methacrylate root canal sealer or a conventional epoxy root canal sealer in two steps increases their dislocation resistance when compared to a one-step placement procedure. MATERIALS AND METHODS: Eighty single-rooted teeth were randomly allocated to 4 groups (n=20). All canals were instrumented to size 40, 0.06 taper and irrigated according to a standardized protocol. Root canal filling was conducted as follows: group 1: methacrylate sealer placed in two steps; group 2: methacrylate sealer placed in one step; group 3: epoxy sealer placed in two steps; group 4: epoxy sealer placed in one step. After setting, thin slices at different root levels were obtained and submitted to push-out testing. RESULTS were analyzed with non-parametric tests to compare the two-step procedures to their one-step counterparts. Failure modes were determined by stereomicroscopy. Random untested methacrylate sealer specimens were also examined with scanning electron microscopy. RESULTS: At each root level, dislocation resistance was significantly higher for the two-step procedure than for the one-step procedure using the methacrylate sealer (p=0.003, p=0.005, p<0.001) but not the epoxy sealer (p=0.83, p=0.1, p=0.06). Among root levels, there were no significant differences in dislocation resistance in the methacrylate sealer two-step group, while all other groups showed differences. CONCLUSION: A two-step placement procedure resulted in significantly higher dislocation resistance for the methacrylate sealer but not for the epoxy sealer.

Surface characteristics and bioactivity of a novel natural HA/zircon nanocomposite coated on dental implants.

The surface characteristics of implant which influence the speed and strength of osseointegration include surface chemistry, crystal structure and crystallinity, roughness, strain hardening, and presence of impurities. The aim of this study was to evaluate the bioactivity and roughness of a novel natural hydroxyapatite/zircon (NHA/zircon) nanobiocomposite, coated on 316L stainless steel (SS) soaked in simulated body fluid (SBF). NHA/zircon nanobiocomposite was fabricated with 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.% of zircon in NHA using ball mill for 20 minutes. The composite mixture was coated on 316L SS using plasma spray method. The results are estimated using the scanning electron microscopy (SEM) observation to evaluate surface morphology, X-ray diffraction (XRD) to analyze phase composition, and transmission electron microscopy (TEM) technique to evaluate the shape and size of prepared NHA. Surfaces roughness tester was performed to characterize the coated nanocomposite samples. The maximum average R a (14.54 µm) was found in the NHA 10 wt.% of zircon coating. In addition, crystallinity (X c ) was measured by XRD data, which indicated the minimum value (X c = 41.1%) for the sample containing 10 wt.% of zircon. Maximum bioactivity occurred in the sample containing 10 wt.% of zircon, which was due to two reasons: first, the maximum roughness and, second, the minimum crystallinity of nanobiocomposite coating.

Effect of post diameter and cement thickness on bond strength of fiber posts.

OBJECTIVE: This study evaluated the effects of different post diameter and oversized post spaces on the push-out bond strength of a fiber post to dentin. METHOD AND MATERIALS: Fifty extracted human maxillary central incisors and canines were divided into five groups and submitted to the push-out test (0.5 mm min-1). Groups 1, 2, and 3 were restored using a fiber post size that was identical to the drill size (sizes 1, 2, and 3, respectively), and groups 4 and 5 were both prepared with drill size 3, and restored using the size 2 and 1 fiber post, respectively. The fiber posts were cemented using self-adhesive dual-polymerized resin cement (RelyX Unicem). The data were analyzed using a one-way analysis of variance (ANOVA) and the Tukey test. RESULTS: There were no significant differences in the mean values for push-out bond strength between groups with different post diameters (P > .05). However, the push-out bond strengths were significantly different between groups with different cement thicknesses, and group 4 yielded the highest bond strength (11.7 ± 0.4 MPa). For all groups, the apical third had the lowest bond strength value (P < .05). CONCLUSION: The highest push-out bond strength values were obtained when one incremental oversized post space was used. Clinically, fiber post space has to provide an optimum cement thickness (around 120 µm) for adequate cementation.

Influence of salivary enzymes and alkaline pH environment on fatigue behavior of resin composites.

PURPOSE: To evaluate the effect of enzymatic activity and alkaline medium on flexural strength and rotary fatigue resistance of direct and indirect resin composite restorative materials. METHODS: Three direct resin composite materials Filtek Z100, Filtek Z250 and Filtek Silorane (3M ESPE), and two indirect resin composite materials; Sinfony (3M ESPE) and an experimental composite (Heraeus Kulzer) were used to fabricate bar-shaped specimens (2 x 2 x 25 mm; n=10) to determine the flexural strength (Fs) by means of a 3-point bending test according to ISO 4049. Additional specimens of the same dimensions (n=20) were used to prepare hour-glass shaped specimens which were immersed in distilled water for 48 hours, transferred to one of five aqueous media at 37 degrees C for 2 weeks; phosphate buffer, distilled water, 0.1N NaOH, 1 unit/ml Amylase, 0.1 unit/ml Esterase, and a group in 0.1N NaOH at 60 degrees C. Rotary fatigue resistance (RFR) was determined in a rotating-bending cantilever test with the highest stress located at the constriction of the hour glass. The rotary fatigue resistance tests were conducted according to the staircase approach (10(4) cycles, 1.0 Hz) and the mean RFR was calculated using logistic regression analysis. RESULTS: NaOH produced a significant decrease in Fs of all materials. The effect of enzymatic biodegradation on Fs of Filtek Z100 and Filtek Z250 was found to be significant, however, for Silorane and indirect composites it was not significant. Except for NaOH the influence of the different aqueous solutions on RFR was not significant for all tested materials.

Innovations in bonding to zirconia based ceramics: Part III. Phosphate monomer resin cements.

PURPOSE: To compare the bond strength values and the ranking order of three phosphate monomer containing resin cements using microtensile (microTBS) and microshear (microSBS) bond strength tests. MATERIALS AND METHODS: Zirconia discs (Procera Zirconia) were bonded to resin composite discs (Filtek Z250) using three different cements (Panavia F 2.0, RelyX UniCem, and Multilink). Two bond strength tests were used to determine zirconia resin bond strength; microtensile bond strength test (microTBS) and microshear bond strength test (microSBS). Ten specimens were tested for each group (n=10). Two-way analysis of variance (ANOVA) was used to analyze the data (alpha=0.05). RESULTS: There were statistical significant differences in bond strength values and in the ranking order obtained using the two test methods. microTBS reported significant differences in bond strength values, whereas microSBS failed to detect such effect. Both Multilink and Panavia demonstrated basically cohesive failure in the resin cement while RelyX UniCem demonstrated interfacial failure. CONCLUSION: Based on the findings of this study, the data obtained using either microTBS or microSBS could not be directly compared. microTBS was more sensitive to material differences compared to microSBS which failed to detect such differences.

The influence of rotating fatigue on the bond strength of zirconia-composite interfaces.

OBJECTIVES: To evaluate the effect of cyclic loading on the bond strength of resin composite to zirconia framework material. METHODS: Bar shaped zirconia/composite specimens (2 mm x 2 mm x 25 mm) were prepared using three different resin cements and placed in a four-point bending test setup. The flexure strength (F(s)) was calculated by placing the bars (n=10) fixed between the four supports (at 10 and 20 mm) with the interface centered between the inner rollers and subsequently loaded (1 mm/min crosshead speed) until fracture. Rotating fatigue resistance (RFR) was determined in a rotating bending cantilever test setup (104, 1.2 Hz) with the highest stress located at the interface (n=20). The RFR was determined by the staircase method and the mean RFR was calculated using logistic regression analysis. RESULTS: Resin cement composition had no significant influence on the bond strength value obtained by both F(s) (F=0.6, P> or =0.5) and RFR (F=1.1, P> or =0.3) tests. However, after rotating fatigue testing there was a significant reduction in bond strength between 46 and 50% of the three resin cements. CONCLUSION: Zirconia resin bond strength is liable to deterioration under the influence of fatigue.

Influence of enzymatic and chemical degradation on zirconia resin bond strength after different surface treatments.

PURPOSE: To investigate the influence of chemical and enzymatic degradation on the stability of zirconia resin bond strength using micro-shear bond strength test. METHODS: Zirconia discs were airborne particle abraded (SB) or selective infiltration etched (SIE) while no surface treatment served as control. Resin composite (Filtek Z250) microdiscs were bonded to zirconia using self-adhesive universal resin cement (RelyX UniCem). Micro-shear bond strength (microSBS) test was conducted after immersion in the following degrading media: 24 hours and 2 weeks of water storage, and 2 weeks in NaOH, alcohol, or esterase enzyme (n=10). RESULTS: There was a significant influence of the surface finish (P < 0.001, F=154.5), biodegradation medium (P < 0.001, F=52.9), and their interaction (P < 0.001, F=6.0) on zirconia resin bond strength. In general SIE group revealed the highest microSBS values (8.1 - 34.5 MPa) after degradation in different media, followed by SB group (8.7 - 28.5 MPa), while the control group showed significantly lower bond strength (0.4 - 9 MPa).

Rotating fatigue and flexural strength of direct and indirect resin-composite restorative materials.

PURPOSE: To evaluate the flexural strength and rotating fatigue resistance of direct and indirect resin composite restorative materials. METHODS: Filtek Z100 and Filtek Z250 (3M ESPE) are direct resin composite restorative materials, and Sinfony (3M ESPE) and Neco (Heraeus Kulzer) are indirect composites. Bar specimens (2 x 2 x 25 mm; n=10) of these materials were used to determine the flexural strength (Fs) by means of 3-point bending tests according to ISO 4049. The same size specimens (n=20) were used to prepare hour-glass shaped specimens. Rotating fatigue resistance (RFR) was determined in a rotating-bending cantilever test with the stress located at the constriction of the hour glass. The rotating fatigue resistance tests were conducted according to the staircase approach (104 cycles, 1.0 Hz) and the mean RFR was calculated using logistic regression analysis. RESULTS: Fs ranged between 100.0 and 141.9 MPa and the RFR 51.6 to 89.6 MPa. After 10,000 cycles the strength of the materials decreased between 35 and 48%. RFR of Filtek Z100, Filtek Z250, and Neco (77.4 - 89.6 MPa) were significantly higher than Sinfony (51.6 MPa).