Effect of A Clinical-Replicable Cooling Protocol on the Cyclic Fatigue Resistance of Heat-Treated Nickel-Titanium Instruments.

Introduction: The aim of this study was to evaluate the bending and cyclic fatigue resistance of Wave One Gold (WOG) and X1 Blue (X1B) instruments when tested at body temperature (36°C ± 1°C) with and without subjected to an alloy cooling protocol. Materials and Methods: A total of sixty instruments (n=30) were tested. Forty instruments (n=20) were randomly selected and divided into two groups: body temperature (BT; n=20) and body temperature with cooling protocol (CP; n=20). Cyclic fatigue test was performed until fracture in a conventional stainless-steel device with water bath equipment to simulate body temperature. CP group instruments were subjected to 5 seconds of spray cooling every 30 seconds. Time to fracture was recorded in seconds. Resistance to bending at an angle of 45 degrees was evaluated using twenty instruments (n=10). Fractured surfaces were examined under scanning electron microscopy (SEM). Statistical analysis was performed at a 5% significance level. Results: There was no difference in the cyclic fatigue resistance between instruments in BT groups (P>0.05). Cooling protocol significantly increased the cyclic fatigue resistance of X1B instruments (P=0.0003) and WOG instruments (P=0.0003). Results: WOG instruments had a significantly lower cyclic fatigue resistance compared to X1B instruments in CP group (P=0.0001). There were no significant differences between the values of resistance increase presented by the instruments after cooling (P>0.05). Bending test presented no statistically significant differences between the tested instruments (P>0.05). Both instruments in both groups showed typical features of cyclic fatigue behavior under SEM. Conclusions: X1 Blue #25.06 and WaveOne Gold #25.07 instruments presented similar cyclic fatigue resistance. The investigated clinical-replicable cooling protocol improved the cyclic fatigue resistance of the tested instruments, with X1 Blue #25.06 presenting a greater cyclic fatigue resistance after cooling. Both instruments presented a similar bending capacity.

Evaluation of the Cyclic and Torsional Fatigue Resistance of Thermally Treated Hyflex CM versus Aurum Blue Nickel-titanium Rotary Instruments.

Introduction: We aim to evaluate the cyclic and torsional fatigue resistance of two rotary instruments, Hyflex CM 25/0.06 (HCM) (Coletene-Whaledent, Allstetten, Switzerland) and Aurum Blue (AB) 25/0.06 (Meta-Biomed, Republic of Korea). Methods and Materials: Forty rotary instruments, HCM 25/0.06 and AB 25/0.06 (n=20 each) were used. The instruments were rotated in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature (n=10) at body temperature (35°±1°C). The torsional test evaluated the torque and angle of rotation at failure of new instruments (n=10) in the portion 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by scanning electron microscopy. The data were analyzed using unpaired student's t- test, and the level of significance was set at 5%. Results: AB 25/0.06 had significantly greater number of cycles to failure than HCM 25/0.06 (P<0.05). The torsional test showed there were no significant differences in the torsional strength and angular rotation to fracture between the groups (P>0.05). Conclusion: Based on this in vitro study, AB 25/0.06 instrument was more resistant to cyclic fatigue than the HCM 25/0.06 instrument, suggested that these instruments are safer than HCM 25/0.06 for the preparation of severely curved canals. However; there was no significant difference in the torsional properties of the two instruments then appear to have similar performance during constricted canal preparation.

Inflammatory response and macrophage polarization using different physicochemical biomaterials for oral and maxillofacial reconstruction.

Knowledge about the action of immune system in the recognition of biomaterials has been extremely helpful when it comes about understanding host response and biomaterials' fate in human body. This study aimed to investigate inflammatory response and macrophage polarization during bone healing process of rat's calvaria critical defects using different bone materials in order to evaluate their influence on bone repair and on the quality of the newly formed bone tissue. Eighty male albinus Wistar rats underwent surgical procedure for the confectioning of a 5-mm diameter bone defect in their right parietal bone, and divided in four groups (n = 20 each), according the biomaterial: AG - Control, particulate intramembranous autogenous bone graft, HA/TCP - particulate biphasic calcium phosphate with HA/TCP (60/40), DBB - particulate deproteinized bovine bone, VC - particulate bioactive vitroceramic. After 3, 7, 21, and 45 days, the specimens were removed and prepared for microcomputed tomography (microCT), light and polarized microscopy, immunohistochemical analysis, and histomorphometry. No significant differences were detected considering percentage of leukocytes among the groups and periods, as well as in relation to immunolabeling for inflammatory (M1) and reparative (M2) macrophages. However, immunolabeling for bone marker indicated a delayed osteoblast differentiation in VC group, resulting in a decrease in mineralized bone matrix parameters in this group, revealed by microCT. In addition, AG and HA/TCP presented a satisfactory bone collagenous content. Despite the distinct origins and physicochemical properties of the tested biomaterials, they presented similar immune-inflammatory responses in the present experimental model, influencing bone-related proteins and bone quality, which must be considered according to their use.

Limitation of diagnostic value of cone-beam CT in detecting apical root isthmuses

Abstract Isthmuses are reported as common anatomic complexities in teeth often associated with failures in endodontic treatment. They should be considered before starting treatment and a preoperative computed tomography scan (CT) may demonstrate these complexities. Objective To assess the diagnostic value of the highest resolution settings of a cone-beam CT (CBCT) system in identifying and measuring apical isthmuses, using micro-CT as reference. Methodology After micro-CT scanning, 40 humans' lower first molars with isthmuses in the apical-3 mm of mesial roots were scanned by the highest resolution settings of the New Generation i-Cat ® CBCT equipment. Two blinded observers recorded the detection of isthmuses in CBCT scans. The lengths of isthmuses were compared between micro-CT and CBCT to assess the diagnostic value of CBCT. Quantitative data for sensitivity were represented as percentages (95% confidence interval). The Bland-Altman method was used to assess differences between gold standard lengths (micro-CT) and CBCT lengths. Results BCT demonstrated 30 positive findings, representing sensitivity for isthmus identification of 75% (95% CI=0.4114-1.1364). Differences between the lengths in micro-CT (1.99±0.40 mm) and CBCT (1.53±0.41 mm) were significant (p<0.0001). Conclusion The CBCT device used presented limited diagnostic value in the identification and measurement of apical isthmuses in the mesial roots of lower molars. In some cases, the actual anatomy of the apical root canal may not be completely delineated in this type of CBCT system, even using the highest resolution settings.

Antibacterial efficacy of endodontic irrigating solutions and their combinations in root canals contaminated with Enterococcus faecalis.

OBJECTIVE: The objective of this study was to evaluate the antibacterial efficacy of irrigating solutions and their combinations against Enterococcus faecalis. STUDY DESIGN: One hundred ten single-rooted human teeth were inoculated with E. faecalis and incubated for 21 days. Teeth were divided according to the irrigant: Group I (GI), 2.5% sodium hypochlorite solution (NaOCl); GII, 2.5% NaOCl + 10% citric acid; GIII, 2.5% NaOCl + apple cider vinegar; GIV, apple cider vinegar; GV, 2% chlorhexidine solution; GVI, 1% peracetic acid; GVII, saline solution. Microbiological samples were taken after root canal preparation and 7 days later. Data were submitted to ANOVA (5%). RESULTS: All solutions promoted reduction of E. faecalis after instrumentation, but bacterial counts were higher in the final sample. GI, GV, and GVI had lower bacterial counts than the other groups. CONCLUSIONS: The irrigating solutions may present activity but do not eradicate E. faecalis in the root canal system.

Evaluation of the physical and chemical properties of two commercial and three experimental root-end filling materials.

OBJECTIVE: The aim of this study was to evaluate the pH, calcium release, setting time, and solubility of two commercially available mineral trioxide aggregate (MTA) cements (white MTA Angelus and MTA Bio), and of three experimental cements (light-cured MTA, Portland cement with 20% bismuth oxide and 5% calcium sulfate, and an epoxy resin-based cement). STUDY DESIGN: For evaluation of pH and calcium ion release, polyethylene tubes with 1.0 mm internal diameter and 10.0 mm length were filled with the cements and immediately immersed in flasks containing 10 mL deionized water. After 3, 24, 72, and 168 hours, the tubes were removed and the water from the previous container was measured for its pH and calcium content with a pH meter and an atomic absorption spectrophotometer. For analysis of the setting time, Gilmore needles weighing 100 g and 456.5 g were used, in accordance with the American Society for Testing and Materials specification no. C266-03. Solubility of each cement was also tested. RESULTS: All the cements were alkaline and released calcium ions, with a declining trend over time. After 3 hours, Portland cement + bismuth oxide and MTA Bio had the highest pH and light-cured MTA the lowest. After 1 week, MTA Bio had the highest pH and light-cured MTA and epoxy resin-based cement the lowest. Regarding calcium ion release, after 3 hours, Portland cement + bismuth oxide showed the highest release. After 1 week, MTA Bio had the highest. Epoxy resin-based cement and light-cured MTA had the lowest calcium release in all evaluation periods. Regarding setting times, white MTA Angelus and MTA Bio had the shortest, Portland cement + bismuth oxide had an intermediate setting time, and the epoxy resin-based cement had the longest. The materials that showed the lowest solubility values were the epoxy resin-based cement, Portland cement + bismuth oxide, and light-cured MTA. The highest solubility values were presented in white MTA Angelus and MTA Bio. CONCLUSIONS: The white MTA Angelus and MTA Bio had the shortest setting times, higher pH and calcium ion release, and the highest solubility. In contrast, the epoxy resin-based cement and light-cured MTA showed lower values of solubility, pH, and calcium ion release.

An ex vivo comparison of root canal length determination by three electronic apex locators at positions short of the apical foramen.

OBJECTIVE: The aim of this study was to evaluate the precision of working length determination of 3 electronic apex locators (EALs): Root ZX, RomiApex D-30, and Ipex at 0.0 mm, at the apical foramen (AF), and at 1.0 mm short of the AF. METHODOLOGY: Thirty-eight mandibular premolars had their real lengths previously determined. Electronic measurements were determined at 1.0 mm, followed by measurements at 0.0 mm, performed in triplicate. RESULTS: Precision of devices at 1.0 mm and 0.0 mm were: 94.7% and 97.4%, respectively (Root ZX); 78.9% and 97.4% (RomiApex D-30); and 76.3% and 97.4% (Ipex). Although no statistical differences were observed between the EALs at 0.0, at 1.0 mm Root ZX performed significantly better than the others. CONCLUSION: The EALs had acceptable precision when measuring the working length at the AF. However, when used at levels short of the AF, only Root ZX did not suffer a significant negative effect on precision.

Evaluation of the radiopacity of some commercial and experimental root-end filling materials.

OBJECTIVE: The aim of the present study was to evaluate the radiopacity of 5 root end filling materials (white MTA Angelus, MTA Bio, light-cured MTA, Sealepox RP, and Portland cement clinker with bismuth oxide and calcium sulfate). METHOD: Five specimens, 10 mm in diameter and 1 mm in thickness according to specification ISO 6876:2001 were fabricated from each material and radiographed using Insigth occlusal films close to a graduated aluminum step-wedge (2 to 16 mm in thickness). Radiographs were digitized and compared to the aluminum step-wedge. The radiographic density data were converted into millimeters of aluminum (mm Al), using the Digora 1.51 software. Results were evaluated statistically using the analysis of variance (ANOVA) followed by Tukey test. The level of significance was set at 5% (P <.05%). RESULTS: Radiopacity values ranged from 1.21 mm Al (light-cured MTA) to 6.45 mm Al (MTA Angelus). Comparison between materials showed significant difference (P < .05) between MTA Angelus and all other materials, between Sealepox RP and MTA Bio, and between light-cured MTA and Portland cement clinker. Light-cured MTA was significantly less radiopaque than all other materials. No significant difference (P > .05) was found between MTA Bio and Portland cement clinker. CONCLUSIONS: All retrograde filling materials evaluated showed greater radiopacity than dentin. All the materials, except light-cured MTA met the minimum radiopacity standards of 3 mm Al recognized by the ISO 6876:2001 and ADA n.57.

Use of cone-beam volumetric tomography in the diagnosis of root fractures.

OBJECTIVES: The diagnosis of root fractures by conventional radiographs is still difficult because of limitations of 2D images. Cone-beam volumetric tomography improves the diagnosis capacity in dentistry, such as increased radiation dose to the patient and presence of artifacts on the image. STUDY DESIGN: This study compared the images obtained on conventional periapical radiographs and 3D scans (Accuitomo 3DX) for the diagnosis of root fractures. Twenty patients with suspected root fractures were submitted to examination by periapical radiography and CBCT. Two professionals, unaware of the symptomatology, examined these radiographs and CBCT images according to pre-established scores, which were later checked against the signs and symptoms. RESULTS: The results revealed statistical difference for cone-beam volumetric tomography compared with conventional radiographs in the diagnosis of root fractures. CONCLUSION: It could be concluded that cone-beam volumetric tomography was better than conventional radiography in the diagnosis of root fractures, thereby constituting an excellent alternative for diagnosis in general practice.