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Introduction: At orthodontic treatment completion, knowledge about the effects of adhesive remnant removal on enamel is paramount., Objective: This study aimed at assessing the effect of different adhesive remnant removal methods on enamel topography (ESI) and surface roughness (Ra) after bracket debonding and polishing., Methods: A total of 50 human premolars were selected and divided into five groups according to the method used for adhesive remnant removal: high speed tungsten carbide bur (TCB), Sof-Lex discs (SL), adhesive removing plier (PL), ultrasound (US) and Fiberglass burs (FB). Metal brackets were bonded with Transbond XT, stored at 37°C for 24 hours before debonding with adhesive removing plier. Subsequently, removal methods were carried out followed by polishing with pumice paste. Qualitative and quantitative analyses were conducted with pre-bonding, post-debonding and post-polishing analyses. Results were submitted to statistical analysis with F test (ANOVA) and Tukey's (Ra) as well as with Kruskal-Wallis and Bonferroni tests (ESI) (P < 0.05)., Results: US Ra and ESI were significantly greater than TCB, SL, PL and FB. Polishing minimized Ra and ESI in the SL and FB groups., Conclusion: Adhesive remnant removal with SL and FB associated with polishing are recommended due to causing little damage to the enamel.

This study aims to investigate a possible correlation between vertical misfits and the stresses transmitted to implants from one-piece casted frameworks fabricated with 3 different materials: commercially pure titanium, cobalt chromium alloy, and nickel chromium titanium alloy. Twelve frameworks simulating screw-retained prosthesis were fabricated from a master cast with 5 implants. Each framework was screwed (20 Ncm) over a metal cast and the vertical mesial and distal misfits were measured using an optical microscope. The stresses transmitted to the implants were measured in a third model by a quantitative photoelastic analysis. Stress and vertical misfit data were statistically analyzed by ANOVA and least significant difference tests and the correlation tests were performed using Pearson Correlation Test (α = 0.05). Mean and standard deviation values of vertical misfit and stress over implants are presented, respectively: commercially pure titanium (29.09 ± 13.24 μm and 11.38 ± 9.23 kPa), cobalt chromium alloy (27.05 ± 10.30 μm and 15.83 ± 9.30 kPa), nickel chromium titanium alloy (24.95 ± 11.14 μm and 16.39 ± 9.51 kPa). There were no significant differences for vertical misfit (P = 0.285). Regarding the stress analysis, there were significant differences between commercially pure titanium, cobalt chromium alloy, and nickel chromium titanium alloy (P = 0.035), with the lowest values for the commercially pure titanium. It may be concluded that stress over implants was affected by different procedures and materials for framework production.

Objective: The purpose of the current in-vivo study was to assess the effect of using 0.12% chlorhexidine (CHX) mouth rinse, before bonding, on shear bond strength of polycarbonate brackets bonded with composite adhesive., Subjects and Methods: Eighteen orthodontic patients with a mean age 21.41 ± 1.2 years, who were scheduled to have 2 or more first premolars extracted, were included in this study. Patients were referred for an oral prophylaxis program which included, in part, the use of a mouth rinse. Patients were divided into 2 groups, a test group of 9 patients who used 0.12% CHX gluconate mouth rinse twice daily and a control group of 9 patients who used a mouth rinse without CHX, but with same color. After 1 week, polycarbonate brackets were bonded to first premolars with Transbond XT composite adhesive. Premolars were extracted after 28 days and tested for shear bond strength on a universal testing machine. Student's t-test was used to compare shear bond strengths of both groups., Results: No statistically significant difference was found in bond strengths' values between both groups. The test group (with CHX) has mean shear bond strength of 14.21 ± 2.42 MPa whereas the control group (without CHX) revealed a mean strength of 14.52 ± 2.31 MPa., Conclusion: The use of 0.12% CHX mouth rinse, for one week before bonding, did not affect the shear bond strength of polycarbonate brackets bonded with Transbond composite. Furthermore, these brackets showed clinically acceptable bond strength.

Objective: To investigate the effects of third-order torque on frictional properties of self-ligating brackets (SLBs)., Materials and Methods: Three SLBs (two passive and one active) and three archwires (0.016 × 0.022-inch nickel-titanium, and 0.017 × 0.025-inch and 0.019 × 0.025-inch stainless steel) were used. Static friction was measured by drawing archwires though bracket slots with four torque levels (0°, 10°, 20°, 30°), using a mechanical testing machine (n  =  10). A conventional stainless-steel bracket was used for comparison. RESULTS were subjected to Kruskal-Wallis and Mann-Whitney U-tests. Contact between the bracket and wire was studied using a scanning electron microscope., Results: In most bracket-wire combinations, increasing the torque produced a significant increase in static friction. Most SLB-wire combinations at all torques produced less friction than that from the conventional bracket. Active-type SLB-wire combinations showed higher friction than that from passive-type SLB-wire combinations in most conditions. When increasing the torque, more contact between the wall of a bracket slot and the edge of a wire was observed for all bracket types., Conclusions: Increasing torque when using SLBs causes an increase in friction, since contact between the bracket slot wall and the wire edge becomes greater; the design of brackets influences static friction.

Objectives: To observe and to compare histologically and histomorphometrically, the combined effect of drilling sequence and implant diameter in vivo., Material and Methods: A total of 72 alumina-blasted and acid-etched Ti-6Al-4V implants with three different diameters (3.75, 4.2, and 5 mm, n = 24 for each group) were placed in the right and left tibiae of 12 beagle dogs. Within the same diameter group, half of the implants were inserted after a simplified drilling procedure (pilot drill + final diameter drill) on one tibia and the other half were placed using the conventional drilling procedure on the other tibia. After 1 week, half of the animals (n = 6) were sacrificed, and the other half was sacrificed after 5 weeks (n = 6). The retrieved bone-implant samples were subjected to non-decalcified histologic sectioning, and the bone-to-implant contact (BIC) and the bone area fraction occupancy (BAFO) were analyzed. Primary statistical analysis used a mixed model analysis of variance with significance level set at P < 0.05., Results: Histologic observation showed that at 1 week, immature woven bone formed in vicinity of the implant, whereas at 5 weeks, the woven bone was replaced by lamellar bone, which formed in proximity with the implant. Histomorphometrically, the simplified technique was associated with significantly greater BIC and BAFO after 1 week. Differences between techniques were not longer apparent after 5 weeks, but BAFO was inversely and significantly associated with implant diameter at that time., Conclusions: The simplified technique did not impair either early or late bone formation for any tested implant diameter; however, wider diameters were associated with less bone formation at longer healing times for both techniques., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: To compare the clinical performance of brackets bonded to anterior and posterior teeth, including second molars., Materials and Methods: One operator, using the straight-wire technique, bonded metallic brackets to the teeth of 127 consecutive patients. All patients were observed for 12 months during their regular orthodontic appointments. Bracket failures were recorded and summarized for statistical analysis. The Cox proportional hazards regression analysis was performed to evaluate bracket failure rates., Results: Statistically significant differences in survival rates were observed between molar tubes and anterior brackets (P < .05). Twelve-month failure rates of incisor, canine, premolar, and molar brackets were 3.6, 1.6, 4.8, and 11.6%, respectively. The first and second molar did not show significant difference in bond failure. Young patients (age <18 years) showed a higher failure rate than old patients (≥18 years)., Conclusions: Brackets directly bonded to the buccal surfaces of molars failed significantly more often than those directly bonded to anterior teeth or premolars, but showed acceptable failure rate especially in adult patients. Bonding on second molars seems to be as reliable as bonding on the first molars.

Objective: To investigate differences in the amount of tooth movement and root resorption that occurred after tipping and bodily movement of the maxillary first molar in rats., Materials and Methods: Ten-week-old female Wistar rats were divided into two groups according to type of tooth movement and subdivided into four subgroups according to the magnitude of applied force. Nickel-titanium closed-coil springs exerting forces of 10, 25, 50, or 100 g were applied to the maxillary left first molars to induce mesial tooth movement. We designed a novel orthodontic appliance for bodily tooth movement. Tooth movement distance and root resorption were measured using microcomputed tomography and scanning electron and scanning laser microscopy., Results: The amount of tooth movement in the bodily tooth movement group was less than half that in the tipping tooth movement group. The greatest amount of tooth movement occurred in the 10-g tipping and 50-g bodily tooth movement subgroups, and the amount of tooth movement decreased with the application of an excessive magnitude of force. Conversely, root resorption increased when the heavier orthodontic force was applied in both groups. Root resorption in the tipping tooth movement group was approximately twice that in the bodily tooth movement group., Conclusions: Root resorption in the tipping tooth movement group was more pronounced than that in the bodily tooth movement group. Although the amount of tooth movement decreased when extremely heavy forces were applied, root resorption increased in both the tipping and bodily tooth movement groups in rats.

Purpose: To use a novel approach to measure the amount of vertical marginal gap in computer numeric controlled (CNC)-milled titanium frameworks and conventional cast frameworks., Materials and Methods: Ten cast frameworks were fabricated on the mandibular master casts of 10 patients. Then, 10 CNC-milled titanium frameworks were fabricated by laser scanning the cast frameworks. The vertical marginal gap was measured and analyzed using the Contura-G2 coordinate measuring machine and special computer software., Results: The CNC-milled titanium frameworks showed an overall reduced mean vertical gap compared with the cast frameworks in all five analogs. This difference was highly statistically significant in the distal analogs. The largest mean gap in the cast framework was recorded in the most distal analogs, and the least amount was in the middle analog., Conclusions: Neither of the two types of frameworks provided a completely gap-free superstructure. The CNCmilled titanium frameworks showed a significantly smaller vertical marginal gap than the cast frameworks.

Purpose: This study aimed to compare the clinical and radiographic success of preveneered posterior NuSmile® and Kinder Krowns® over one year and to assess the level of parental satisfaction with their esthetics., Methods: Three trained operators placed 120 crowns in a split-mouth design with a random allocation for 36 participants (mean age: 5.8 years) who received two, four, six, or eight crowns. Blind assessment of the clinical and radiographic performance of the restorations was performed by four calibrated examiners after one year. Results were analyzed by Fisher's exact test and McNemar test. Examiner reliability was determined by Cohen's kappa score. Visual analogue scale (VAS) was used to assess the level of parental satisfaction., Results: All crowns but one were retained, and the majority (83 percent) had no facing fractures. Parental satisfaction was high (9.4/10 on the VAS). Primary maxillary first molar crowns had more occlusal facing fractures than their mandibular counterparts (P=.02). Primary mandibular second molar crowns showed more facing fractures than their maxillary counterparts (P=.008). Both types showed no statistical difference in most categories, but Kinder Krowns had more facing fractures (P<.02)., Conclusion: Posterior preveneered crowns have predictable durability at 12 months while offering natural appearance to restored teeth.

Objective: To investigate the eff ect of chloride concentration on the corrosion of Co-Cr alloy and pure Ti in a simulated oral environment., Methods: The electrochemical corrosion tests of pure Ti and Co-Cr alloy were carried out in neutral artificial saliva solutions with different NaCl concentrations (0.9%, 2.0%, and 3.0%). Th e morphologies of corroded surface for pure Ti and Co-Cr alloy were observed by scanning electron microscope (SEM)., Results: Th e changes in the self-corrosion potentials (Ecorr) for pure Ti and Co-Cr alloy in three kinds of artificial saliva solutions was not obvious. However, the self-corrosion current densities (Icorr) of pure Ti were much lower than those of Co-Cr. The Icorr of Co-Cr alloy increased in a concentration-dependent manner of NaCl, whereas the breakdown potential (Eb) of Co-Cr alloy decreased in a concentration-dependent manner. Th e potential ranged for the breakdown of oxide film (Ev) was shortened in a concentration-dependent manner of NaCl. There was no obvious difference in the Icorr of pure Ti with different concentrations of NaCl. The breakdown potential was not seen according to the polarization curves., Conclusion: In a certain range, the increase of the concentration of Cl- leads to accelerate the corrosion behavior of Co-Cr alloy, but it does not affect pure Ti.

Statement of Problem: The biomechanical properties of post systems may become more important as the amount of remaining tooth structure decreases, thus different materials may influence the characteristic strength of fatigued endodontically treated teeth., Purpose: The purpose of this study was to assess the characteristic strength and probability of survival of endodontically treated teeth restored with different intraradicular post systems., Material and Methods: Forty human maxillary canines with similar root lengths were randomly divided into 4 groups (n=10): cast post and core, stainless-steel prefabricated post, carbon-fiber post, and glass-fiber post. Cores and metallic crowns were fabricated for all specimens. Restored teeth were exposed to mechanical fatigue (250,000 cycles) in a controlled chewing simulator. Each intact specimen was mounted in a special device and aligned at a 45-degree angle to the long axis of the tooth. A universal testing machine was used to apply a static load at a crosshead speed of 0.5 mm/min until specimen failure. The maximum value was recorded in newtons (N). Probability Weibull curves (2-sided 90% confidence bounds) were calculated for each group, and a probability of survival as a function of load at failure was plotted for the groups., Results: A significantly higher characteristic strength was observed for groups carbon-fiber post (755.82 N) and cast post and core (750.6 N) (P<.05) compared with glass-fiber post (461.35 N) and stainless-steel prefabricated post (524.78 N) groups. All the roots in the cast post and core group demonstrated catastrophic fracture, whereas the remaining groups had no root fractures., Conclusions: Prefabricated posts made of glass fiber and stainless steel showed significantly lower characteristic strength and probability of survival than cast post and core, whereas crowns with carbon-fiber posts presented a single load similar to the fracture values of cast posts., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Background: Orthodontic maxillary expansion is a commonly-performed treatment approach to correct transverse maxillary deficiencies by separating the mid-palatal suture. To obtain a successful treatment result and prevent relapse, the expanded maxillary sutures require maintenance by means of qualified bone reorganisation., Aim: To assess the effects of low-intensity pulsed ultrasound (LIPUS) on sutural bone formation after the expansion of the interpremaxillary suture in rats., Methods: Sixteen male Wistar rats, 6 to 8-week old, were used. The expansion appliance comprised a helical spring fabricated from 0.014 inch stainless steel wire (Dentaurum, Ispringen, Germany). The rats were divided into two equal groups and randomly assigned to the LIPUS treatment group or a sham-operation group. LIPUS was delivered via a 2.5 cm diameter ultrasound transducer (Exogen, Smith and Nephews, Inc., Memphis, TN, USA) for 20 minutes per day during 7 days of post-expansion retention. Following retention, the rats' maxillae were surgically removed and histologic and immunohistochemical specimens were prepared and examined., Results: The number of osteoblasts and blood vessel dimensions in the ultrasound group increased but was not significant, compared with the control group. A statistically significant difference in osteocalcin, VEGF and TGF-β immunoreactivities (p < 0.01) was found in the area of the mineralising tissue. Only VEGF immunoreactivity was significant between two groups (p < 0.01) in the fibrous tissue area., Conclusions: The area of mineralising tissue in the LIPUS-applied group expressed activity markers for osteocalcin, VEGF and TGF-β compared with a surrounding area of fibrous tissue. Cellular activation in the LIPUS group was greater than that of controls. Therefore, LIPUS may be accepted as a useful approach to enhance sutural bone formation.

Objective: This study aimed to assess tissue changes during orthodontic movement after binge-pattern ethanol 20% exposure., Methods: Male Wistar rats (n = 54) were divided into two groups. The control group (CG) received 0.9% saline solution, while the experimental group (EG) received 20% ethanol in 0.9% saline solution (3 g/kg/day). On the 30th day, a force of 25 cN was applied with a nickel-titanium closed coil spring to move the maxillary right first molar mesially. The groups were further divided into three subgroups (2, 14 and 28 days). Tartrate-resistant acid phosphatase and picrosirius were used to assess bone resorption and neoformation, respectively. Data were compared by two-way ANOVA, Tukey's HSD, Games-Howell and chi-square test. Significance level was set at 5%., Results: There was a decrease in the number of osteoclasts in EG at day 28. The percentage of collagen showed no interaction between group and time., Conclusion: Binge-pattern 20% ethanol promoted less bone resorption at the end of tooth movement, thereby suggesting delay in tooth movement.

Introduction: Temporary skeletal anchorage devices now offer the possibility of closing anterior open bites and decreasing anterior face height by intruding maxillary posterior teeth, but data for treatment outcomes are lacking. This article presents outcomes and posttreatment changes for consecutive patients treated with a standardized technique., Methods: The sample included 33 consecutive patients who had intrusion of maxillary posterior teeth with a maxillary occlusal splint and nickel-titanium coil springs to temporary anchorage devices in the zygomatic buttress area, buccal and apical to the maxillary molars. Of this group, 30 had adequate cephalograms available for the period of treatment, 27 had cephalograms including 1-year posttreatment, and 25 had cephalograms from 2 years or longer., Results: During splint therapy, the mean molar intrusion was 2.3 mm. The mean decrease in anterior face height was 1.6 mm, less than expected because of a 0.6-mm mean eruption of the mandibular molars. During the postintrusion orthodontics, the mean change in maxillary molar position was a 0.2-mm extrusion, and there was a mean 0.5-mm increase in face height. Positive overbite was maintained in all patients, with a slight elongation (<2 mm) of the incisors contributing to this. During the 1 year of posttreatment retention, the mean changes were a further eruption of 0.5 mm of the maxillary molars, whereas the mandibular molars intruded by 0.6 mm, and there was a small decrease in anterior face height. Changes beyond 1 year posttreatment were small and attributable to growth rather than relapse in tooth positions., Conclusions: Intrusion of the maxillary posterior teeth can give satisfactory correction of moderately severe anterior open bites, but 0.5 to 1.5 mm of reeruption of these teeth is likely to occur. Controlling the vertical position of the mandibular molars so that they do not erupt as the maxillary teeth are intruded is important in obtaining a decrease in face height., (Copyright © 2014 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This study investigated the surface, fractured structure, and physicochemical properties related to cyclic fatigue in various nickel-titanium (NiTi) files., Methods: Among a total of 10 groups of NiTi files, conventional NiTi files (ProFile [Dentsply Maillefer, Ballaigues, Switzerland] and K3 [SybronEndo, Orange, CA]) and new-generation NiTi files (ProFile Vortex [PV; Tulsa Dental Specialties, Tulsa, OK], Vortex Blue [VB; Tulsa Dental Specialties], and K3 XF [XF; SybronEndo, Orange, CA]) with the same tip diameter (ISO size 25) and 2 types of taper (0.04 and 0.06) were used in this study. Scanning electron microscopy of the file surface structure, differential scanning calorimetry, and cyclic fatigue resistance tests were conducted., Results: Many mechanical grooves were recognized on the file surface. The surface in the ProFile group was extremely smooth compared with that observed for the other files. Many shallow hollows besides mechanical grooves were noted on the surface in the XF group. A smooth curve was observed in the ProFile, K3, and PV groups. Defined peaks in differential scanning calorimetry were observed in the VB and XF groups. The 0.04 taper files exhibited a statistically higher number of cycles to fracture than the 0.06 taper files in all groups (P < .05). Cracks along the mechanical grooves were observed in the NiTi files, with the exception of the XF group. The start of cracking was detected at U-shape sites in the ProFile group, the cutting edge in the PV and VB groups, and radial islands in the K3 and XF groups., Conclusions: The present findings suggest that new-generation NiTi files are not necessarily improved compared with conventional files., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective: To evaluate the effect of different lubricants on friction between orthodontic brackets and archwires., Materials and Methods: Active (Quick, Forestadent) and passive (Damon 3MX, Ormco) self-ligating brackets underwent friction tests in the presence of mucin- and carboxymethylcellulose (CMC)-based artificial saliva, distilled water, and whole human saliva (positive control). Dry friction (no lubricant) was used as the negative control. Bracket/wire samples (0.014 × 0.025 inch, CuNiTi, SDS Ormco) underwent friction tests eight times in a universal testing machine., Results: Two-way analysis of variance showed no significant interaction between bracket type and lubricant (P  =  .324). Friction force obtained with passive self-ligating brackets was lower than that for active brackets (P < .001). Friction observed in the presence of artificial saliva did not differ from that generated under lubrication with natural human saliva, as shown by Tukey test. Higher friction forces were found with the use of distilled water or when the test was performed under dry condition (ie, with no lubricant)., Conclusion: Lubrication plays a role in friction forces between self-ligating brackets and CuNiTi wires, with mucin- and CMC-based artificial saliva providing a reliable alternative to human natural saliva.

Introduction: The aim of this study was to describe the canal shaping properties of ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Johnson City, TN), and WaveOne (Dentsply Maillefer) nickel-titanium instruments in mandibular first molars by using micro-computed tomographic (micro-CT) scanning., Methods: A total of 36 maxillary first molars with 2 separate mesial canals and 1 distal canal were selected and scanned preoperatively and postoperatively by using micro-CT scanning with a voxel size of 30 μm. Canals were prepared with PTU, PTN, and WaveOne systems under hypochlorite irrigation. The volume of the untreated canal; the volume of dentin removed after preparation; the amount of the uninstrumented area; and the transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time and instrument failure were also recorded., Results: Instrumentation of canals increased their volume and surface area. The distal canals had a significantly higher proportion of unprepared surfaces than mesial canals (P < .05). The PTN system produced less transportation than the WaveOne and PTU systems in the apical third of the mesial canals (P < .05). There was no significant difference on apical transportation in distal canals among the 3 instrument systems. Instrumentation with WaveOne was significantly faster than with the other 2 instruments (P < .05)., Conclusions: The PTN, PTU, and WaveOne instruments shaped root canals in mandibular first molars in vitro without significant shaping errors. The curved canals prepared using PTN had less apical transportation than the canals prepared using WaveOne and PTU., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare the accuracy and reproducibility of digital versus conventional dental impressions and fabrication techniques for single units and full-arch implant frameworks., Materials and Methods: A total of 24 samples, divided into four groups, were created using conventional and digital implant impression/fabrication techniques: group 1 (conventional single implant), group 2 (digital single implant), group 3 (conventional complete arch), and group 4 (digital complete arch). All impressions were made at the abutment level. Marginal fit measurements were made using an optical microscope at two points (buccal and lingual) for each sample. Statistical analysis was performed using F and t tests (α = .05)., Results: For single implants, the conventional impression/fabrication pathway resulted in a mean marginal discrepancy of 24.1 μm compared to 61.43 μm for the digital impression/fabrication pathway. For full-arch frameworks, the conventional impression/fabrication pathway resulted in a mean marginal discrepancy of 135.1 μm compared to 63.14 μm for the digital technique., Conclusion: The conventional pathway resulted in a smaller marginal discrepancy for single-implant frameworks. In contrast, the digital pathway resulted in a smaller marginal discrepancy for full-arch implant frameworks.

Statement of Problem: It is unknown whether dental implant systems with a platform-switched configuration have better periimplant bone stress distribution and lead to less periimplant bone level changes., Purpose: The purpose of this study was to quantitatively investigate interfacial stress and stress distribution in implant bone in 2 implant abutment designs (platform-switched design and conventional diameter matching) by using a nonlinear finite element analysis method., Material and Methods: A finite element simulation study was applied to 2 commercially available dental implant systems: the Ankylos implant system with a reduced-diameter abutment (platform-switched implant) and the Anthogyr implant system with an abutment of the same diameter (regular platform implant). These 2 dental implant systems were positioned in a bone block, which was constructed based on a cross-sectional image of a human mandible in the molar region. In simulation, a single vertical load of 50 N, 100 N, or 150 N and horizontal loads of 50 N and 100 N were applied to the occlusal surface of the abutment., Results: The finite element analysis found that the Ankylos implant system has a higher maximum von Mises stress in the implant abutment connection section and a lower maximum von Mises stress in the periimplant bone. The opposite results were found in the Anthogyr implant system., Conclusions: Lower stress levels in the periimplant bone with a more uniform stress distribution were found for the Ankylos implant system with a platform-switched configuration. Although relatively higher stress was found in the abutment, premature implant failure is not anticipated because of the high strength of titanium alloy., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objective: To analyze the effect of various coating formulations on the mechanical and corrosion properties of nickel-titanium (NiTi) orthodontic wires., Materials and Methods: Uncoated, rhodium-coated, and nitrified NiTi wires were observed with a three-point-bend test, surface roughness (Ra) measurement, scanning electron microscopy, energy dispersive spectroscopy, and electrochemical testing (open circuit potential, electrochemical impedance spectroscopy, and cyclic polarization scan). Differences in the properties of tested wire types were analyzed with analysis of variance and Tukey post hoc test., Results: Uncoated and nitrified NiTi wires showed similar mechanical and anticorrosive properties, while rhodium-coated NiTi wires showed the highest Ra and significantly higher modulus of elasticity, yield strength, and delivery of forces during loading but not in unloading. Rhodium-coated NiTi wires also had the highest corrosion current density and corrosion potential, lowest impedance modulus, and two time constants on Bode plot, one related to the Rh/Au coating and the other to underlying NiTi., Conclusion: Working properties of NiTi wires were unaffected by various coatings in unloading. Nitrification improved corrosion resistance. Rhodium coating reduced corrosion resistance and pronounced susceptibility to pitting corrosion in artificial saliva because of galvanic coupling between the noble coating and the base alloy.

Objectives: To assess and compare the papilla presence mesially and distally to dental implants restored with customized abutments and custom metal abutments in the anterior maxilla., Material and Methods: Thirty-eight patients receiving 38 single-tooth implants, restored with 26 customized abutments and 12 custom metal abutments in the anterior maxillary region were enrolled in this study. The cases where did not existed contact point were excluded. Presence/absence of the interproximal papilla, inter-tooth-implant distance (ITD) and distance from the base of the contact point to dental crest bone of adjacent tooth (CPB) were accessed. Global P-values were determined for changes in CPB and papilla score over time (P < 0.05)., Results: Thirty-six patients with 36 implants were available for the 12-month follow-up. The abutments and reconstruction survival rate was 100% with no fracture or crown loss. A mean mesial CPB of 5.71 ± 1.54 mm and distal CPB of 4.01 ± 1.73 mm were assessed in the customized abutment group for an overall mean papilla presence of 1.69 ± 0.46. A mean mesial CPB of 5.41 ± 1.31 mm and distal CPB of 4.77 ± 1.21 mm were assessed in the control group for an overall mean papilla presence of 1.08 ± 0.65., Conclusions: The restoration of single-implants using computer-assisted design/computer-assisted manufacturing abutments appears to help maintaining a regular papillary filling although the variations of the implant positioning or the restoration/teeth relation., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Statement of Problem: The mechanical stability of the implant-abutment connection is of fundamental importance for successful implant-supported restorations. Therefore, understanding removal torque values is essential., Purpose: The purpose of this study was to evaluate the reverse torque values of indexed and nonindexed abutments of the Morse Taper system., Material and Methods: Twelve Morse taper implants with their respective abutments were divided into 2 groups (n=6): group NI, nonindexed abutments; and group IN, indexed abutments. Each abutment received a sequence of 2 consecutive torques for insertion (15 Ncm) at an interval of 10 minutes, and 1 reverse torque, all measured with a digital torque wrench. The Student t test with a 5% significance level was used to evaluate the data., Results: Statistical analysis showed no significant difference in reverse torque values between nonindexed and indexed abutments (P=.57). When comparing insertion torque and reverse torque values between the groups, group NI presented a mean torque loosening percentage of 8% (P=.013), whereas group IN presented a loosening of 15.33% (P<.001)., Conclusion: The use of indexed abutments for the Morse taper system presented similar biomechanical stability when compared with nonindexed abutments, both with a significant reduction in reverse torque values., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to evaluate four in-house optimized, non-contrast enhanced sequences for MRI-investigation of maxillo-mandibular and dental structures by use of 3 T., Methods: 12 volunteers with different dental status were examined by using a 3 T MRI with a 20-channel standard head-and-neck coil. All images performed were evaluated by using 3D-techniques, with different slice-thicknesses, in 3D T1- and T2-weighted sequences, as well as by using new techniques of image depictions. In addition phantom measurements were performed to estimate the extent of image artefacts caused by retainers and metal implants., Results: Mean age of the participants was 33 years (range, 25.5-62.75 years), and the sex ratio was 5 females to 7 males. We identified different techniques to improve osseous and dental structures, despite problems caused by dental implants, tooth crowns or braces., Conclusion: The sequences evaluated offered excellent visualization in 2D and 3D of osseous and dental structures. Anatomical, osseous and dental structures were described at their ROI, in relation to patients with dental and head and neck pathologies. The ability to detect and distinguish pathological processes as soon as possible in 3D with excellent image quality avoiding ionizing radiation remains a challenging domain., (Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

The role of surface preparation, hydrothermal ageing exposure and subsequent cyclic fatigue testing on the biaxial strength of a dental Y-TZP material are investigated. The initial strength and survival rate of a dental Y-TZP ceramic material to fatigue testing was found to be highly dependent upon surface preparation more so than exposure to various hydrothermal exposure conditions. The results suggest that the monoclinic phase generated by either surface damage (especially sandblasting) and to a lesser extent hydrothermal exposure does appear to mitigate strength and fatigue degradation. The results are discussed in terms of the size of defects generated following various surface treatments and the role of cyclic fatigue induced crack growth. A critical ratio is established between the monotonic strength and fatigue stress survival. From the specimens that failed and exhibited reduced strength after cycling a plot of averaged crack growth rate versus max cyclic stress intensity factor was established which closely matched existing results for Y-TZP ceramics.

Purpose: To assess the influence of non-ionizing radio frequency signals of magnetic resonance imaging (MRI) on physical properties of dental alloys and metal-ceramic adhesion., Materials and Methods: A total of 120 disk-shaped wax patterns (10 mm x 10 mm x 1 mm) were cast in a base metal alloy (Ni-Cr alloy) and commercially pure titanium (Ti) following the manufacturing recommendation. After casting, air abrasion and ultrasonic cleaning, feldspathic ceramic was applied and fired according to manufacturer's instructions using a standard mold. The specimens were subjected to 3000 thermocycles in distilled water between 5°C and 55°C, then veneered alloy specimens were randomly assigned to three groups according to MRI exposure time: a) 15 min of MRI exposure, b) 30 min of MRI exposure and c) no MRI exposure (control group). The specimens were subjected to shear loading until failure. A separate set of Ni-Cr and Ti specimens were prepared, and after exposure to MRI for 15 and 30 min, x-ray diffraction (XRD) analysis, surface roughness, and Vicker's hardness were measured., Results: Both the alloy type (p < 0.005) and exposure duration (p < 0.005) had a significant effect on the bond results. While the control group presented the highest bond strength for Ni-Cr and Ti (36.9 ± 1.4 and 21.5 ± 1.6 MPa, respectively), 30 min MRI exposure significantly decreased the bond strength for both alloys (29.4 ± 1.5 and 12.8 ± 1.5 MPa, respectively) (p < 0.05). XRD analysis indicated formation of the crystalline phase as well as change in crystal size and position for Ni-Cr and Ti after MRI. Compared to the control group where alloys were not exposed to MRI (Ni-Cr: 0.40 μm; Ti: 0.17 μm), surface roughness increased (Ni-Cr: 0.54 μm; Ti: 1.1 μm). Vicker's hardness of both alloys decreased after 30 min MRI (Ni-Cr: 329.5; Ti: 216.1) compared to the control group c (Ni-Cr: 356.1; Ti: 662.1), being more significant for Ti (p < 0.005)., Conclusion: Ni-Cr alloy is recommended over Ti for the fabrication of metal-ceramic restorations for patients with a history of frequent exposure to MRI.

Adverse effects of nickel ions being released into the living organism have resulted in development of high nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also improves steel properties. The cell cytocompatibility, blood compatibility and cell response of high nitrogen nickel-free austenitic stainless steel were studied in vitro. The mechanical properties and microstructure of this stainless steel were compared to the currently used 316L stainless steel. It was shown that the new steel material had comparable basic mechanical properties to 316L stainless steel and preserved the single austenite organization. The cell toxicity test showed no significant toxic side effects for MC3T3-E1 cells compared to nitinol alloy. Cell adhesion testing showed that the number of MC3T3-E1 cells was more than that on nitinol alloy and the cells grew in good condition. The hemolysis rate was lower than the national standard of 5% without influence on platelets. The total intracellular protein content and ALP activity and quantification of mineralization showed good cell response. We conclude that the high nitrogen nickel-free austenitic stainless steel is a promising new biomedical material for coronary stent development., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The CAD/CAM technology associated with rapid prototyping (RP) is already widely used in the fabrication of all-ceramic fixed prostheses and in the biomedical area; however, the use of this technology for the manufacture of metal frames for removable dentures is new. This work reports the results of a literature review conducted on the use of CAD/CAM and RP in the manufacture of removable partial dentures., (© 2014 by the American College of Prosthodontists.)

Objectives: The purpose of this study was to compare several different single-cone obturations in the gutta-percha-filled areas (PGFA), sealer-filled areas (PSFA) and voids, also determining the volumetric characteristics of the tested cones., Materials and Methods: Curved mesial roots of 120 mandibular molars were instrumented using several different systems (ProTaper Next, Twisted File Adaptive, OneShape, ProTaper Universal, WaveOne and Reciproc) and filled with corresponding single cones. The teeth were then sectioned horizontally at 2, 4, 6 and 8 mm from the apex. The area values of each section were calculated and converted to percentages (PGFA, PSFA and voids) of the total area. To determine volumetric characteristics of the tested cones, 20 gutta-percha points of each tested group were scanned with CBCT using the same parameters., Results: The ProTaper Next and WaveOne groups presented the most PGFA and least PSFA. The Twisted File Adaptive group presented the least PGFA and most PSFA (p < 0.05) and the least gutta-percha volume., Conclusions: The Twisted File Adaptive system matched cones had the least volume and the least PGFA in severely curved mesiobuccal canals of mandibular first molars. Single matched cones volume varied.

Statement of Problem: The chipping of ceramic veneers is a common problem for zirconia-based restorations and is due to the weak interface between both structures., Purpose: The purpose of this study was to evaluate the mechanical behavior of ceramic veneers on zirconia and metal frameworks under 2 different bond-integrity conditions., Material and Methods: The groups were created to simulate framework-veneer bond integrity with the crowns partially debonded (frictional coefficient, 0.3) or completely bonded as follows: crown with a silver-palladium framework cemented onto a natural tooth, ceramic crown with a zirconia framework cemented onto a natural tooth, crown with a silver-palladium framework cemented onto a Morse taper implant, and ceramic crown with a zirconia framework cemented onto a Morse taper implant. The test loads were 49 N applied to the palatal surface at 45 degrees to the long axis of the crown and 25.5 N applied perpendicular to the incisal edge of the crown. The maximum principal stress, shear stress, and deformation values were calculated for the ceramic veneer; and the von Mises stress was determined for the framework., Results: Veneers with partial debonding to the framework (frictional coefficient, 0.3) had greater stress concentrations in all structures compared with the completely bonded veneers. The metal ceramic crowns experienced lower stress values than ceramic crowns in models that simulate a perfect bond between the ceramic and the framework. Frameworks cemented to a tooth exhibited greater stress values than frameworks cemented to implants, regardless of the material used., Conclusion: Incomplete bonding between the ceramic veneer and the prosthetic framework affects the mechanical performance of the ceramic veneer, which makes it susceptible to failure, independent of the framework material or complete crown support., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of the study was to compare the diagnostic ability to radiographically detect separated stainless steel (SS) versus nickel-titanium (NiTi) instruments located at the apical third of filled root canals with either AH 26 (Dentsply DeTrey GmbH, Konstanz, Germany) or Roth sealer (Roth International Ltd, Chicago, IL)., Methods: Sixty single-rooted extracted human teeth with 1 straight root canal were instrumented to a size 25 apical diameter. In 40 teeth, apical 2-mm segments of SS (n = 20) or NiTi (n = 20) files were intentionally fractured in the apical part of the root canal. The remaining 20 teeth without fractured files served as a control group. Subsequently, the root canals were filled using laterally condensed gutta-percha and either AH 26 sealer (AH) or Roth sealer (Roth). All teeth were radiographed using conventional Kodak film (Eastman Kodak Co, Rochester, NY) and a charge-coupled device digital sensor. The evaluation of the images for the presence of a fractured instrument was performed independently by 2 blinded observers. The data were statistically analyzed using McNemar and Fisher exact tests., Results: The kappa values were 0.76 and 0.615 for the first and second observers, respectively, and 0.584 between the observers. There were no significant differences in the diagnostic ability between digital and conventional radiography or the different root canal sealers (AH vs Roth, P > .05). The sensitivity to detect fractured SS was significantly higher than NiTi (P < .05)., Conclusions: It may be difficult to radiographically detect a retained separated instrument. It is easier to radiographically detect fractured SS than NiTi instruments retained at the apical third of the root canal., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of the present study was to evaluate crack formation after flaring root canals with Gates Glidden drills and ProTaper Universal (SX; Dentsply Maillefer, Ballaigues, Switzerland), Endoflare (MicroMega, Besançon, France), Revo-S (MicroMega), and HyFlex (Coltene-Whaledent, Allstetten, Switzerland) flaring instruments., Methods: One-hundred eight mandibular molars were selected. Eighteen teeth were left unprepared to serve as negative controls; the experimental groups consisted of the mesiobuccal and mesiolingual root canals of the remaining 90 teeth, which were instrumented with the following coronal flaring instruments: Gates Glidden drills and ProTaper Universal SX, Endoflare, Revo-S SC1, and HyFlex 25.08 instruments. All roots were then sectioned perpendicular to the long axis at 1, 2, 3, 4, 6, and 8 mm from the cementoenamel junction. The sections were inspected under a stereomicroscope, and any crack formations were recorded. The data were analyzed using the chi-square test (P = .05)., Results: The Gates Glidden drills resulted in a higher rate of crack formation than that noted in the control group (P < .05). Flaring of the root canals using the ProTaper Universal, Endoflare, Revo-S, and HyFlex instruments resulted in crack formation similar to that of the control group (P > .05)., Conclusions: The use of the Gates Glidden drills resulted in the formation of the most cracks. However, the results for the ProTaper Universal, Endoflare, Revo-S, and HyFlex flaring instruments were similar to those of the control group in terms of crack formation., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to evaluate corticotomy-facilitated orthodontics (CFO) using piezosurgery versus conventional rotary instruments., Materials and Methods: Ten healthy adult male mongrel dogs of comparable age with a complete set of permanent dentition with average weights between 13-17 kilograms were used. CFO using conventional rotary instruments versus piezosurgery was performed on each dog in a split mouth design. For every dog, mandibular 2nd premolar retraction on each side was attempted after extracting 3rd premolars followed by corticotomy-facilitated orthodontics using conventional rotary surgical burs on the left side and an ultrasonic piezosurgery system on the right side of the same animal. Intraoral measurements of the rate of tooth movement were taken with a sliding caliper. Measurements were performed by the same operator at the time of surgery (appliance delivery) and every month for six months. The dogs were sacrificed after six months from initiation of tooth movement to evaluate the amount of tooth movement for both conventional rotary and piezosurgery corticotomy techniques., Results: A statistically significantly higher mean amount of tooth movement for conventional rotary instrument versus the piezosurgery corticotomy technique was observed at all time intervals., Conclusions: Tooth movement was 1.6 times faster when CFO was done using conventional rotary instruments as compared to a piezosurgery device.

Introduction: The purpose of this study was to compare the in vitro amount of apically extruded debris with new endodontic rotary nickel-titanium instruments., Methods: Sixty mandibular premolars were instrumented up to size 25 using ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (Dentsply Maillefer), Twisted File Adaptive (SybronEndo, Orange, CA), and HyFlex (Coltene-Whaledent, Allstetten, Switzerland) rotary systems. The apically extruded debris was collected and dried in preweighed Eppendorf tubes. The amount of extruded debris was assessed with an electronic balance. The total time required to complete root canal shaping with the different instruments was also recorded. The significance level was set at P = .05., Results: The instrumentation time with the ProTaper Universal rotary system was significantly longer than with all the other instruments (P < .05). The Twisted File Adaptive and ProTaper Next systems extruded significantly less debris than the ProTaper Universal and HyFlex systems (P < .05)., Conclusions: The ProTaper Next and Twisted File Adaptive instrumentation systems were associated with less debris extrusion compared with the ProTaper Universal and HyFlex systems., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This study aimed to investigate the torsional resistance of 2 reciprocating nickel-titanium instruments (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer, Ballaigues, Switzerland]) operated at the maximum rotating angle in a proprietary motor., Methods: With the file tip secured at various levels (3, 4, or 5 mm) of Reciproc R25 and WaveOne Primary, the distortion angles and torsional loads were monitored during counterclockwise movement at 2 rpm until fracture (n = 10 at each level) for a load-distortion graph. The rotation angles and loads at the beginning point of the plateau, the ultimate torsional strength, final fracture angle, and toughness were determined. The data were analyzed using 1-way analysis of variance and the Tukey post hoc test at α = .05. The lateral longitudinal aspect and the fracture cross-section of each specimen were examined by scanning electron microscopy after the test., Results: The rotation angle at the beginning point of the plateau was significantly greater for a binding site farther away from the tip of the instrument for both systems (P < .05), and all were greater than 170° (preset in the dedicated motor from manufacturer). The ultimate strength and toughness also increased significantly at levels farther away from the instrument tip (P < .05). All specimens showed typical topographic features of torsional fracture, including the circular abrasion marks and fibrous dimples near the rotation center after the test., Conclusions: It was determined that the 2 brands of reciprocating files are safe when operated at the rotational angle in the proprietary motor., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Background: The aim of this study is to calculate and compare the play and torque expression of 0.018 and 0.022 bracket slots when engaged with archwires of different size, cross section and material., Methods: Eight orthodontic brackets, two of slot height 0.018 and six of slot height 0.022, from different manufacturers, were measured and fixed to a vertical support. Twenty-four archwires of differing size, cross section and material were selected, measured and tested in each bracket of compatible slot width. Compression testing by Instron dynamometer and geometric calculations enabled us to determine the play angle of each bracket/archwire combination, and the angle at which a clinically efficacious force couple, sufficient for dental movement, is exerted., Results: All bracket/archwire combinations considered were found to have play angles far above the ideal. This is ascribable to the slots being oversized with respect to the manufacturers' claims. Likewise, some archwires were found to be oversized, while others undersized.When the same archwire was tested with brackets from different manufacturers, the play and torque expression differed, despite the same nominal dimensions of the slots. When the same bracket was tested with the same size archwires, their construction material was found to influence the torque expression, due to the difference in elastic modulus, but not the wire/slot play., Conclusions: The dimensional precision of orthodontic brackets and archwires and the rigidity of the latter have a profound influence on the torque expression of pre-angled appliances.

Statement of Problem: Previous studies have not resolved the question as to which post and core combination optimizes the stress distribution within the post restoration and tooth., Purpose: The purpose of this study was to determine which post and core combination provides the most favorable stress distribution upon loading., Material and Methods: Three-dimensional models of teeth were created with the Ansys program to simulate different materials used for post and cores (Ti, NiCr, AuPd, zirconia, zirconia post/composite resin core, glass fiber post/composite resin core, and carbon fiber post/composite resin core) and metal ceramic crowns (nickel chromium alloy [Group NiCr] and gold palladium alloy [Group AuPd]). A force of 400 N was applied to the occlusal surface, and von Mises equivalent stress values were calculated., Results: Carbon fiber post/composite resin core/metal ceramic crowns with NiCr alloy core had the highest stress values in the weakened root, tooth/post interface, and post. NiCr post/NiCr core/metal ceramic crowns with NiCr alloy core had the lowest stress values in the weakened root and post. The zirconia post and core had the lowest stress value in the tooth/post interface., Conclusions: A post material with a high elastic modulus led to lower stress in the weakened root (approximately 6%) and tooth/post interface (approximately 12%) and to higher stress in the post (approximately 5 times). A composite resin core led to higher stress in the weakened root (approximately 11% to 17%) and lower deformation in the tooth/post interface (approximately 17.5%) and post materials (approximately 24%). Group AuPd resulted in lower stress in the root and high stress in the post (approximately 4.5% to 7%) and affected the amount of deformation in posts with a composite resin core., (Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was to assess the influence of M-Wire (Dentsply Tulsa Dental Specialties, Tulsa, OK) and controlled memory technologies on the fatigue resistance of rotary nickel-titanium (NiTi) files by comparing files made using these 2 technologies with conventional NiTi files., Methods: Files with a similar cross-sectional design and diameter were chosen for the study: new 30/.06 files of the EndoWave (EW; J. Morita Corp, Osaka, Japan), HyFlex (HF; Coltene/Whaledent, Inc, Cuyahoga Falls, OH), ProFile Vortex (PV; Dentsply Tulsa Dental Specialties, Tulsa, OK), and Typhoon (TYP; Clinician's Choice Dental Products, New Milford, CT) systems together with ProTaper Universal F2 instruments (PTU F2; Dentsply Maillefer, Ballaigues, Switzerland). The compositions and transformation temperatures of the instruments were analyzed using x-ray energy-dispersive spectroscopy and differential scanning calorimetry, whereas the mean file diameter values at 3 mm from the tip (D3) were measured using image analysis software. The average number of cycles to failure was determined using a fatigue test device., Results: X-ray energy-dispersive spectroscopy analysis showed that, on average, all the instruments exhibited the same chemical composition, namely, 51% Ni-49% Ti. The PV, TYP, and HF files exhibited increased transformation temperatures. The PTU F2, PV, and TYP files had similar D3 values, which were less than those of the EW and HF files. The average number of cycles to failure values were 150% higher for the TYP files compared with the PV files and 390% higher for the HF files compared with the EW files., Conclusions: M-Wire and controlled memory technologies increase the fatigue resistance of rotary NiTi files., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Context: Moist environment in the mouth varies and causes variable amounts of corrosion of dental materials. This is of concern particularly when metallic implants, metallic fillings, orthodontic appliances are placed in the hostile electrolytic environment in the human mouth. Components of diet rich in salt and spices are important factors influencing the corrosion of metallic appliances placed in the oral cavity., Aims: To study in vitro corrosion of orthodontic metallic brackets immersed in solutions of salt and spices in artificial saliva., Materials and Methods: Orthodontic brackets were used for corrosion studies in artificial saliva, salt, and spices using electrochemical technique and surface analysis. Electrochemical studies using different parameters were done in solutions of artificial saliva containing salt and spices. Photomicrographs from the optical microscope were also obtained., Results: RESULTS of corrosion studies have clearly demonstrated that certain spices such as turmeric and coriander are effective in reducing corrosion, whereas salt and red chili have been found to enhance it. Surface analysis of small pits present on the surface of the as-received bracket will initiate corrosion which leads to more pitting.

Introduction: The aim was to study nickel-titanium closed-coil springs in a clinically relevant test setting with respect to the accuracy of the "preactivation" for nickel-titanium closed-coil springs application and whether it is possible to keep activation forces constant during the whole time of treatment., Methods: We tested 10 types of springs from 5 manufacturers under clinically relevant conditions, allowing us to study the interactions between load and temperature over time. Hystereses were compared using t tests., Results: Springs with a large mechanical hysteresis also showed a large thermal hysteresis. After heating shock, these springs showed intensive force spikes and persistent high loads. Some springs showed negligible thermal and mechanical hysteresis. Such springs never showed any clinically significant persistent high loads., Conclusions: Springs with a large hysteresis were unable to keep activation forces constant during the whole time of treatment even after any preactivation, and they might cause persistently high loads and possibly overloading. Only springs with minor hysteresis, low temperature dependence of force, and a clinically useful plateau have the following clinical advantages: reduced chair time, optimal rates of tooth movement, reproducible clinical results, and conservation of anchorage., (Copyright © 2014 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Aim: The purpose of this study was to assess in vitro the tooth color alterations associated with two commonly used endodontic irrigants, the chlorhexidine gluconate (CHX) and the sodium hypochlorite (NaOCl) up to 15 days post-treatment. Additionally, the possible influence of endodontic access preparation on tooth color was investigated., Materials and Methods: Thirty intact human anterior teeth were used. Black adhesive tape with a 4 mm diameter window was used to standardize the enamel surface intended for color analysis. After the access cavity, preparation and the initial root canal negotiation with stainless steel hand files, the root canal shaping was completed with rotary nickel-titanium files. The teeth were divided into three groups (n = 10). Conventional syringe irrigation was performed with one irrigant for each group. The enamel surfaces were colorimetrically evaluated before access cavity, after cavity preparation and at 1, 3, 7 and 15 days post-treatment. The CIE color parameters (L*, a*, b*) were recorded and averaged for each material and the corresponding color differences (ΔE) were calculated and statistically analyzed., Results: The most significant factor in tooth color alteration, during the endodontic treatment, was the access preparation. CHX and NaOCl caused tooth color changes comparable with the saline. CHX and NaOCl did not increase the tooth color changes relative to the values induced by the access preparation., Conclusion: The two endodontic irrigants were not able to induce tooth color alteration to a greater extent than the access preparation., Clinical Significance: Chlorhexidine and NaOCl cannot be considered as discoloring endodontic materials. The most contributing factor in tooth color alteration during endodontic treatment in the anterior teeth is access preparation.

This study evaluated the effects of the remaining coronal tissue and post type on the fracture strength of incisors. Sixty human maxillary central incisors were sectioned at the cemento-enamel junction or at 2 mm above this junction. The roots received cast cores and posts, fibre posts, or relined fibre posts (n = 10 each). A compressive load was applied over the cores untilfracture. In the absence of coronal structure, the fracture strength did not differ among the post types evaluated. In the presence of remaining coronal structure, the fracture strength was higher in specimens with cast cores and posts.

Objective: Torque is applied to orthodontic brackets in order to alter the buccal-lingual angulation of a tooth. One factor that can affect torque is the ligation mode used to retain the archwire in the bracket slot. The objective of this study was to investigate the effects of stainless steel ligation on torque expression and bracket deformation., Methods: This study utilized 60 upper right central incisor Damon Q brackets and 60 Ormco Orthos Twin brackets. The brackets used in this study were subdivided into four groups: (1) Damon Q ligated with SS ligature; (2) Damon Q with the sliding bracket door; (3) Orthos Twin bracket ligated with SS wire; and (4) Orthos Twin ligated with elastic ties. All brackets were tested using an orthodontic torque simulating device that applied archwire rotation from 0° to 45°., Results: All brackets ligated with stainless steel ties exhibited greater torque expression and less deformation than brackets without stainless steel ties. As well, Damon Q brackets exhibit less bracket deformation than Orthos Twin brackets., Conclusions: Stainless steel ties can reduce the amount of plastic deformation for both types of brackets used in this study., (© 2014 British Orthodontic Society.)

Introduction: During chemomechanical instrumentation, several liquid or paste substances are used to ease the action of the files and to eliminate debris and the smear layer. The aim of this study was to evaluate whether the use of a paste containing EDTA during cleaning and shaping of the root canal helps to eliminate debris., Methods: Twenty root canals in dog teeth were instrumented by a crown-down technique by using nickel-titanium rotary files. In 10 root canals (group A), sodium hypochlorite was used during instrumentation, followed by a final irrigation with 17% liquid EDTA. In another 10 canals (group B), sodium hypochlorite was again used as the irrigating solution, but Glyde File Prep paste was used with every instrument, and a final irrigation with EDTA was also carried out. Two additional teeth were used as positive and 2 as negative controls. The jaws were prepared for histologic evaluation., Results: In group A where Glyde was not used during cleaning and shaping, little or no debris was found in the apical third of the instrumented root canals; however; in group B in which Glyde File Prep paste was used during chemomechanical instrumentation, moderate to high accumulation of debris was observed in the apical third., Conclusions: The use of Glyde File Prep paste during rotary mechanical instrumentation favors the accumulation of debris in the apical third of the root canals. Irrigation with NaOCl and a final flush with EDTA by means of a small-gauge needle with simultaneous aspiration led to less accumulation of debris than in the Glyde File Prep group (P < .05)., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Background: Titanium dental material can become corroded because of electrochemical interaction in the oral environment. The corrosion process may result in surface modification. It was hypothesized that a titanium surface modified by corrosion may enhance the attachment of periodontal pathogens. This study evaluates the effects of corroded titanium surfaces on the attachment of Porphyromonas gingivalis., Methods: Commercially pure titanium (cp-Ti) and titanium-aluminum-vanadium alloy (Ti-6Al-4V) disks were used. Disks were anodically polarized in a standard three-electrode setting in a simulated oral environment with artificial saliva at pH levels of 3.0, 6.5, or 9.0. Non-corroded disks were used as controls. Surface roughness was measured before and after corrosion. Disks were inoculated with P. gingivalis and incubated anaerobically at 37°C. After 6 hours, the disks with attached P. gingivalis were stained with crystal violet, and attachment was expressed based on dye absorption at optical density of 550 nm. All assays were performed independently three times in triplicate. Data were analyzed by two-way analysis of variance, the Tukey honestly significant difference test, t test, and Pearson's correlation test (α = 0.05)., Results: Both cp-Ti and Ti-6Al-4V alloy-corroded disks promoted significantly more bacterial attachment (11.02% and 41.78%, respectively; P <0.0001) than did the non-corroded controls. Significantly more (11.8%) P. gingivalis attached to the cp-Ti disks than to the Ti-6Al-4V alloy disks (P <0.05). No significant difference in P. gingivalis attachment was noted among the corroded groups for both cp-Ti and Ti-6Al-4V alloy (P >0.05). There was no significant correlation between surface roughness and P. gingivalis attachment., Conclusion: A higher degree of corrosion on the titanium surface may promote increased bacterial attachment by oral pathogens.

Introduction: New designs and alloys have been developed to increase cyclic fatigue (CF) resistance of rotary files. The aim of this study was to compare CF resistance of ProTaper Universal (PTU; Dentsply Tulsa Dental, Tulsa, OK) and ProTaper Next (PTN, Dentsply Tulsa Dental) instruments at different points of curvature., Methods: A total of 420 files (240 PTU, S1, F1, F2, and F3 and 180 PTN, X1, X2, and X3) were divided in 14 groups of 30 instruments each. Instruments in groups S1-5, F1-5, X1-5, F2-5, X2-5, F3-5, and X3-5 were tested at 5 mm from the tip. Groups S1-12, X1-12, and F1-12 were tested at 12 mm from the tip because S1, X1, and F1 instruments have the same diameter at that level. Groups F2-8, X2-8, F3-8, and X3-8 were tested at 8 mm (F2/X2 and F3/X3, respectively, had the same diameter at 8 mm). All files were rotated at 300 rpm until fracture. CF resistance was tested in stainless steel curved canals (60°, r = 3 mm). Time to fracture was recorded. The mean half-life and beta and eta were calculated for each group and were compared with Weibull analysis., Results: PTN instruments will last significantly longer than PTU files with a probability higher than 98% at all tested levels except for S1, which was the significantly the most resistant instrument to CF at 5 mm from the tip., Conclusions: PTU S1 was significantly the most resistant instrument at 5 mm from the tip. PTN files were significantly more resistant to CF than PTU instruments at all the other tested levels., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Orthodontic therapy is a force management procedure largely based on use of arch wires for storing and distributing biologically tolerable forces by means of which position of teeth is altered. Advances in material science and technology has resulted in an array of newer arch wire materials, opening new vistas, in orthodontic treatment. Materials with widely diverging properties are in the market today and their usage has profound implications on appliance mechanics, and are very much different from stainless steel which is popular even today. The dentists who practise orthodontics have to therefore clearly outline the phases of treatment and select the arch wire most suited for attaining specific treatment goals.

Introduction: The aim of the present study was to investigate the incidence of cracks in root dentin after root canal preparation with ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex (Coltene-Whaledent, Allstetten, Switzerland), and ProTaper Universal (Dentsply Maillefer) rotary instruments., Methods: One-hundred mandibular premolars were selected. Twenty-five teeth were left unprepared and served as a negative control; another 25 teeth were instrumented with the ProTaper Universal system up to size F4 as a positive control, and the remaining 50 teeth were shaped with the following experimental groups with an apical size 40 file: ProTaper Next X4 and HyFlex 40/0.4. After root canal preparation, all of the roots were sectioned perpendicular to the long axis at 2, 4, 6, and 8 mm from the apex, and the sections were then observed under a stereomicroscope. The absence/presence of cracks was recorded, and the data were analyzed with a chi-square test. The significance level was set at P = .05., Results: No cracks were observed in the negative control group. Vertical root fractures were not observed in any of the groups. The ProTaper Next and HyFlex instruments caused fewer cracks (28%) than the ProTaper Universal instrument (56%) (P < .05). However, there were no significant differences in crack formation between the ProTaper Next and HyFlex groups (P > .05)., Conclusions: Within the limitations of this in vitro study, all of the instrumentation systems used in this study created cracks in the root dentin. The ProTaper Next and HyFlex instruments tended to cause fewer dentinal cracks compared with the ProTaper Universal instrument., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)