Influence of different heat treatments and temperatures on the cyclic fatigue resistance of endodontic instruments with the same design.

OBJECTIVES: To evaluate the influence of different heat treatments and temperatures on the cyclic fatigue resistance of 2Shape instruments (Micro Mega, Besancon, France) with the same design. MATERIALS AND METHODS: A total of 80 2Shape TS1 (#25/.04) and 80 TS2 (#25/.06) files with different heat treatments (no heat-treated, NHT; C-Wire; T-Wire; CM-Wire) were tested at room (25° ± 1 °C) and body (37° ± 1 °C) temperatures in 16-mm stainless steel artificial canal with a curvature of 60° and 5 mm of radius. Files were tested in continuous rotation at 300 rpm using a customized device. Cyclic fatigue resistance was expressed in the number of cyclic to fracture (NCF). The phase transformation temperature of each file was determined by differential scanning calorimetry. Data were statistically analyzed using the two-way ANOVA and the Bonferroni post-hoc test with p < 0.05. RESULTS: All CM-Wire TS1 and TS2 files showed higher NCF than the other groups at both temperatures (p < 0.001). C-Wire TS2 showed higher resistance than NHT and T-Wire TS2 (p < 0.001), with no significant differences between the last two. Body temperature significantly decreased NCF of all tested files (p < 0.05) except for NHT and T-Wire TS1. CONCLUSIONS: Body temperature negatively affected the cyclic fatigue resistance of C-Wire and CM-Wire TS1 and of all TS2 files compared with room temperature. The CM-Wire instruments exhibited the highest cyclic fatigue resistance of all tested files. CLINICAL RELEVANCE: Heat-treated nickel-titanium files can differently perform according to environmental temperature and file dimensions. The CM-Wire 2Shape prototypes displayed the highest flexural resistance in all experimental conditions.

Influence of NiTi Wire Diameter on Cyclic and Torsional Fatigue Resistance of Different Heat-Treated Endodontic Instruments.

We compared the mechanical properties of 2Shape mini TS2 (Micro-Mega, Besançon, France) obtained from 1.0 diameter nickel-titanium (NiTi) wires and 2Shape TS2 from 1.2 diameter nickel-titanium (NiTi) wires differently thermally treated at room and body temperature. We used 120 NiTi TS2 1.0 and TS2 1.2 files made from controlled memory (CM) wire and T-wire (n = 10). Cyclic fatigue resistance was tested by recording the number of cycles to fracture (NCF) at room and body temperatures using a customized testing device. Maximum torque and angle of rotation at failure were recorded, according to ISO 3630-1. Data were analyzed by a two-way ANOVA (p < 0.05). The CM-wire files had significantly higher NCFs at both temperatures, independent of wire dimensions. Testing at body temperature negatively affected cyclic fatigue of all files. The 1.0-mm diameter T-wire instruments showed higher NCF than the 1.2-mm diameter, whereas no significant differences emerged between the two CM wires at either temperature. The maximum torque was not significantly different across files. The TS2 CM-wire files showed significantly higher angular rotation to fracture than T-wire files. The TS2 CM-wire prototypes showed higher cyclic fatigue resistance than T-wire prototypes, regardless of wire size, exhibiting suitable torsional properties. Torsional behavior appears to not be affected by NiTi wire size.

Effects of ultrasonic refinement on endodontic access cavity walls: A microcomputed tomography analysis.

OBJECTIVES: The present study aimed in assessing the coronal defects after access cavity finishing and refinement by micro. METHODS: Access cavities on thirty molars were prepared using a diamond bur. To finish and refine the access cavity, the Endo-Z was used in group 1 (n=15) and Start X 1 in group 2. Preparation time was recorded. A micro-CT scan was done before and after access preparation. Formation and location of the new defects were registered, the extension of defects calculated and the direction of the extension registered, preparation time and surface roughness determined (P < 0.05). RESULTS: Preparation time was significantly higher with ultrasonics (P <0.001). Internal walls showed smoother surfaces for Endo-Z group. Newly counts and extension length of defects weren't significantly different between groups (P > .05). CONCLUSION: Ultrasonic tips induced new cracks. Both instruments caused the extension of cracks. Ultrasonic tips requires more time and results in significantly rougher surfaces.

Impact of Warm Vertical Compaction on the Sealing Ability of Calcium Silicate-Based Sealers: A Confocal Microscopic Evaluation.

The aim of this in vitro study was to evaluate the dentinal tubule penetration of two calcium silicate-based sealers used in warm vertical compaction (WVC) obturation technique in comparison with the single cone (SC) technique by confocal laser scanning microscopy (CLSM). The null hypothesis was that both obturation techniques produced similar sealer penetration depths at 1 and 5 mm from the apex. Forty-four mandibular single-rooted premolars were randomly divided into four equally experimental groups (n = 10) and two control groups (n = 2) according to the type of sealer (Bio-C Angelus, Londrína, PR, Brazil or HiFlow Brasseler, Savannah, GA, USA) with either SC or WVC. The sealers were mixed with a fluorescent dye Rhodamine B (0.1%) to enable the assessment under the CLSM. All the specimens were sectioned horizontally at 1 and 5 mm from the apex. The maximum penetration depth was calculated using the ImageJ Software (ImageJ, NIH). Data were analyzed by Mann-Whitney U and Kruskal-Wallis tests (p < 0.05). A significant difference was shown between the four groups at 1 mm (p = 0.0116), whereas similar results were observed at 5 mm (p = 0.20). WVC allowed better diffusion for both sealers at 1 mm (p = 0.01) and 5 mm (p = 0.034). The maximum penetration of the Bio-C and HiFlow sealers was more important at 5 mm with the two obturation techniques. Within the limitations of this study, WVC enhanced the penetration of calcium silicate-based sealers into the dentinal tubules in comparison with the SC technique at both levels.

Assessment of root canal transportation of 2Shape and ProTaper gold in mandibular molar mesial canals: A micro-computed tomographic study.

The aim of this study was to compare shaping abilities of Protaper Gold® (PTG) and 2Shape® (TS) by using a new automatic process and micro-computed tomography (Micro-CT). 32 first mandibular molars with two separate mesial canals were selected. Only mesial roots were prepared with PTG and TS. Pre- and post-operative scans were performed using Micro-CT to provide volumes with a voxel size of 20 µm. Volumes, non-instrumented area, amount of transportation and centering ability in coronal, middle and apical third shaping time and procedural errors were recorded. TS and PTG increased the endodontic volume of 2.98 mm3 (±1.56) and 3.21 mm3 (±1.78) respectively with no statistical difference (p = .168) and no procedural errors. No significant difference was found concerning canal transportation among groups but only within the same group PTG (p value < .001) and TS (p value < .001). The mean centering ratio was significantly different only between the section levels for PTG (p value < .001) and TS (p value = .01); it was significantly reduced in the cervical third. The percentage of untouched canal walls ranged between 29.78% (±15.145) and 36.60% (±11.968) respectively for PTG and TS with no statistical difference among groups (p value = .168). TS and PTG with post machining heat treatment were able to produce centered preparations with no significant difference or procedural errors. TS system provided a shorter preparation time than PTG files.

Canal Transportation and Centring Ability of Reciproc and Reciproc Blue With or Without Use of Glide Path Instruments: A CBCT Study.

Objective: The objective of this ex vivo study was to evaluate canal transportation and centring ability of Reciproc and Reciproc blue systems in curved root canals with or without prior use of PathFile rotary system (PF) using Cone Beam Computed Tomography (CBCT). Methods: One hundred and twenty curved root canals from maxillary and mandibular premolars were selected. Canals were divided randomly into 4 groups (n=30): Reciproc 25 (R25), (PF+R25), Reciproc Blue 25 (RB25), (PF+RB 25). Specimens were scanned before and after root canal preparation. Using CBCT, root canal transportation and centring ability was assessed by measuring the shortest distance from the edge of uninstrumented canal to the periphery of the root (mesial and distal) before and after preparation. Data were analysed using a one-way analysis of variance and Tukey test. The p value was set at 0.05. Results: Less transportation and better centring ability occurred when PF was used before R25 or RB25 (P<0.0001). There was no significant difference between R25 and RB25 groups. Conclusion: Using PF before R25 and RB25 resulted in less root canal transportation and better centring ability. The specific thermo-mechanical treatment of RB25 did not provide better results when compared to R25.

Effect of 2 Heat-treated Nickel-Titanium Files on Enlargement and Deformation of the Apical Foramen in Curved Canals: A Scanning Electronic Microscopic Study.

INTRODUCTION: The aim of this study was to evaluate under scanning electronic microscopy the enlargement and deformation of the apical foramen of curved mesiobuccal roots with both reciprocating and rotary single-file systems made of a newly heat-treated alloy through the use of Reciproc Blue (REC Blue; VDW, Munich, Germany) and XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland). METHODS: Forty mesiobuccal roots of mandibular and maxillary molars presenting a curvature ranging from 20°-40° were used in this study. The apical foramens were initially scanned with a scanning electronic microscope under 200× magnification. Roots were divided into 2 groups (n = 20): the REC Blue group instrumented with the REC Blue system and the XPS group instrumented with the XPS system. Both groups were instrumented at the foramen. The apical foramens were scanned after root canal preparation. The area, circularity, and ratio of the Feret diameters were calculated from each image. The Kolmogorov-Smirnov, Mann-Whitney, and Wilcoxon tests were used for statistical analysis (P ≤ .05). RESULTS: The area of the foramen increased significantly after canal shaping with REC Blue and XPS. The variation of the area was significantly greater with XPS. However, there were no significant differences in circularity and the ratio of the Feret diameters with both instruments. CONCLUSIONS: No transportation was found when using REC Blue and XPS. The newly heat-treated nickel-titanium alloy did not promote deformation of the apical foramen in curved canals.

Anatomical Investigation of Middle Mesial Canals of Mandibular Molars in a Middle Eastern Population: A Cross-sectional Cone-beam Computed Tomography Study.

AIM: To identify the prevalence of middle mesial canals (MMC) in mandibular molars in a Lebanese population to determine the relationship between MMC and different factors (age, sex, and tooth type) and to examine the canal's morphological aspects (category, length, orifice position, and dentin width toward furcation). MATERIALS AND METHODS: The presence of MMC in the mesial roots of 505 mandibular molars of 200 patients was analyzed using cone-beam computed tomography (CBCT). Then, the position of the MMC orifices with respect to the pulpal floor and the main canals orifices, and the width of dentin along the canal toward the furcation were determined using 3D Slicer 4.10.1. RESULTS: In all, 14.65% of the first and second mandibular molars presented an MMC. A higher frequency of confluent canals was noted mostly joining the mesiobuccal canal (MBC). Gender appears to be a factor influencing the prevalence of MMCs, contrary to age-groups and tooth type. In mandibular first molars, the orifice is located at a mean distance of 1.22 ± 0.44 mm from the pulpal floor, 1.42 ± 0.53 mm from the MBC orifice, and 1.57 ± 0.60 mm from the mesiolingual canal (MLC) orifice. The width of dentin toward the furcation varies between 0.95 and 2.29 mm. In mandibular second molars, the orifice is located at a mean distance of 1.00 ± 0.51 mm from the pulpal floor, 1.39 ± 0.60 mm from the MBC orifice, and 1.37 ± 0.50 mm from MLC orifice. The width of dentin toward the furcation varies between 0.71 mm and 2.22 mm. CONCLUSION: Middle mesial canal is present in 14.65% of mandibular molars in the Lebanese population, with its orifice located under the pulpal floor. The majority of MMCs join the MBC. CLINICAL SIGNIFICANCE: Middle mesial canal is not a rare finding in the Lebanese population (14.65%). Clinicians should take time to search for this canal in the isthmus between the main mesial canals.

Post-endodontic Flare-ups after a Single-visit Treatment Using the FUI Scoring Method and Associated Factors: A Clinical Prospective Study.

AIM: Flare-ups following a root canal treatment are still a major problem both to the patient and to the clinician. Its definition, etiology, incidence, and risk factors have been the subject of long-standing debate. We conducted this study to investigate the incidence of flare-ups after a single-visit treatment and to identify the factors associated with the flare-up index (FUI). MATERIALS AND METHODS: All patients treated by postgraduate residents in endodontic specialty at Saint Joseph University of Beirut from June 2018 to January 2019 were invited to participate in the study. After a routine root canal treatment, patients were given a questionnaire to fill after 24 hours-48 hours-7 days, covering a postoperative assessment of symptoms using the visual analogue scale (VAS) and FUI. Patients who experienced a severe postoperative pain and/or swelling were identified and categorized as having a flare-up. RESULTS: A total of 423 patients (age: 39.76 ± 12.428 years) were included in the study. The incidence of flare-up was 1.9%. The mean FUI was 5.94 ± 5.646 and was highly correlated with the VAS score (p < 0.001). The factors that significantly influenced the occurrence of flare-ups were: pulpal diagnosis (p < 0.001), preoperative drug intake (p < 0.001), preoperative symptoms (>24 hours) before treatment (p < 0.001), and tooth type (p = 0.013). CONCLUSION: FUI should be used in further studies to confirm our results since it is a valid quantitative method to assess this clinical phenomenon. CLINICAL RELEVANCE: Endodontists should take into consideration the diagnosis and the history of preoperative symptoms since it plays an important role in predicting the occurrence of flare-ups and the success of the treatment.

Evaluation of Two Shaping Systems and Two Ultrasonic Irrigation Devices in Removing Root Canal Filling Material from Mesial Roots of Mandibular Molars: A Micro CT Study.

We assessed the efficiency of two shaping file systems and two passive ultrasonic irrigation (PUI) devices for removing filling material during retreatment. The mesial canals from 44 extracted mandibular molars were prepared and obturated. The teeth were randomly divided into two groups, and then one group was retreated with Reciproc R25 (VDW, Munich, Germany) (n = 44) and the other group was retreated with 2Shape (TS, Micro Mega, Besançon, France) (n = 44). A micro-computed tomography (CT) scan was taken before and after the retreatment to assess the volume of the filling material remnants. The teeth were then randomly divided into four groups to test two different PUI devices: Irrisafe (Satelec Acteon Group, Merignac, France) and Endo Ultra (Vista Dental Products, Racine, WI, USA). The teeth in Group A were retreated with 2Shape to test the Endo Ultra (n = 22) device, the teeth in Group B were retreated with 2Shape in order to test the Irrisafe (n = 22) device, the teeth in Group C were retreated with Reciproc to test the Endo Ultra (n = 22) device, and Group D was retreated with Reciproc to test the Irrisafe (n = 22) device. A third micro-CT scan was taken after the retreatment to test the PUIs. The percentage of Gutta-Percha (GP) and sealer removed was 94.75% for TS2 (p < 0.001) and 89.3% for R25 (p < 0.001). The PUI significantly enhanced the removal of the filling material by 0.76% for Group A (p < 0.001), 1.47% for Group B (p < 0.001), 2.61% for Group C (p < 0.001), and by 1.66% for Group D (p < 0.001). 2Shape was more effective at removing the GP and sealer during retreatment (p = 0.018). The supplementary approach with PUI significantly improved filling material removal, with no statistical difference between the four groups (p = 0.106).

Influence of the Maxillary Sinus on the Accuracy of the Root ZX Apex Locator: An Ex Vivo Study.

This study evaluated the accuracy of the Root ZX (J. Morita, Tokyo, Japan) electronic apex locator in determining the working length when palatal maxillary molar roots are in a relationship with the sinus. Seventeen human maxillary molars with vital pulp were scheduled for an extraction and implant placement as part of a periodontal treatment plan. The access cavity was prepared, and a #10 K file (Dentsply Maillefer, Ballaigues, Switzerland) was inserted into the palatal root using the Root ZX apex locator in order to determine the electronic working length (EWL); then, the teeth were extracted. To determine the real working length (RWL), a #10 K file was introduced into the root canal until its tip touched a glass plate. EWL and RWL were compared. Images reconstructed with CBCT (cone beam computerized tomography) revealed that eight palatal roots were related to the maxillary sinus, whereas nine were not. The results showed a significant difference between the EWL and the RWL of the palatal roots related to the sinus (p < 0.001). No significant difference was observed in measurements of roots not in contact with the sinus (p > 0.05). Within the study limitations, the reliability of Root ZX was influenced by the relationship of the roots with the maxillary sinus.

Dentinal tubule penetration of AH Plus, BC Sealer and a novel tricalcium silicate sealer: a confocal laser scanning microscopy study.

OBJECTIVES: The aim of this in vitro study was to assess the dentinal tubule penetration of three different sealers, AH Plus, BC Sealer and a novel tricalcium silicate sealer (NTS). MATERIALS AND METHODS: Ninety-six human maxillary central incisors were divided into three experimental groups (n = 32) and were filled with gutta-percha using a single-cone technique in conjunction with one of the three sealers: AH Plus, BC Sealer or NTS. The roots in each group were cross-sectioned at 1 and 5 mm from the root apex, and the surfaces were examined under confocal laser scanning microscopy (CLSM). The sealer penetration depths were measured at their maximum depths and at four circumferential depths (12, 3, 6 and 9 o'clock) and were evaluated using ImageJ software (ImageJ, NIH). RESULTS: The maximum and mean penetration depths were significantly higher at 5 mm compared to 1 mm from the apex in the AH Plus (p < 0.001), BC Sealer (p < 0.001) and NTS groups (p < 0.001). No significant difference was observed between the groups at 1 mm for both parameters. The maximum and mean penetration depths were significantly lower at 5 mm for AH Plus compared with the other two groups (p = 0.012). CONCLUSIONS: Within the study limitations, the BC Sealer and NTS demonstrated better tubule penetration results than the AH Plus sealer. CLINICAL RELEVANCE: Although no study has confirmed a relationship between the penetration depth of root canal sealers and the prevention of apical periodontitis, dentinal tubule sealer penetration may improve obturation quality.

Properties of Tricalcium Silicate Sealers.

INTRODUCTION: Sealers based on tricalcium silicate cement aim at an interaction of the sealer with the root canal wall, alkalinity with potential antimicrobial activity, and the ability to set in a wet field. The aim of this study was to characterize and investigate the properties of a new tricalcium silicate-based sealer and verify its compliance to ISO 6876 (2012). METHODS: A new tricalcium silicate-based sealer (Bio MM; St Joseph University, Beirut, Lebanon), BioRoot RCS (Septodont, St Maure de Fosses, France), and AH Plus (Dentsply, DeTrey, Konstanz, Germany) were investigated. Characterization using scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction analysis was performed. Furthermore, sealer setting time, flow, film thickness, and radiopacity were performed following ISO specifications. pH and ion leaching in solution were assessed by pH analysis and inductively coupled plasma. RESULTS: Bio MM and BioRoot RCS were both composed of tricalcium silicate and tantalum oxide in Bio MM and zirconium oxide in BioRoot RCS. In addition, the Bio MM contained calcium carbonate and a phosphate phase. The inorganic components of AH Plus were calcium tungstate and zirconium oxide. AH Plus complied with the ISO norms for both flow and film thickness. BioRoot RCS and Bio MM exhibited a lower flow and a higher film thickness than that specified for sealer cements in ISO 6876. All test sealers exhibited adequate radiopacity. CONCLUSIONS: Bio MM interacted with physiologic solution, thus showing potential for bioactivity. Sealer properties were acceptable and comparable with other sealers available clinically.

Quantitative volumetric analysis of cross-linked gutta-percha obturators.

AIM: The purpose of this study was to evaluate the effects of technique on the filling quality of 2 recently introduced obturation systems comparatively with warm vertical compaction using micro-computed tomography. METHODS: 36 single-rooted teeth were selected, root canals prepared, and assigned to 3 groups (n=12), according to the filling technique: warm vertical compaction technique WVC, GuttaCore (Dentsply Tulsa Dental Specialties, Tulsa, OK) and Gutta Fusion (VDW, Germany). Each specimen was scanned using a micro-CT. Percentage of voids was calculated and data statistically analyzed using Kruskal Wallis test with a significance level of 5%. RESULTS: All obturations showed satisfactory similar results at the apical level. Differences between the three obturation methods were not significant at 1 mm (-p-value >0.05), 3 mm (-p-value >0.05) and 5 mm (-p-value >0.05). No root fillings were void-free. No significant difference was found between the WVC technique, the GuttaCore technique and the Gutta Fusion technique concerning percentage of apical voids regardless of canal level. CONCLUSION: This study shows the efficiency of cross-linked obturators in filling root canals hermetically by comparing them to the warm vertical compaction technique. Results show that these obturation techniques were equally sufficient concerning apical adaptation making them appropriate to use in endodontic obturations.

Accuracy of Cone-beam Computed Tomography and Periapical Radiography in Endodontically Treated Teeth Evaluation: A Five-Year Retrospective Study.

BACKGROUND: This study aimed to evaluate the accuracy of two imaging methods in detecting the apical pathology in endodontically treated teeth. MATERIAL AND METHODS: A clinical examination from a sample of 156 teeth of patients treated by students of masters in endodontics at the Care Center of the Faculty of Dentistry at St. Joseph University, Beirut was done after 5 years of follow-up. Periradicular digital radiographs and a cone-beam computed tomography (CBCT)scans were taken and analyzed statistically using both the Exact Fisher tests and McNemar tests. RESULTS: The prevalence of lesions was significantly higher with CBCT (34.8%), whereas for digital radiography (13.8%). The CBCT was revealed more precise to identify periapical lesions. As for the clinical success, the rate was 82.5%. CONCLUSION: Within the limitations of the present study, CBCT was more reliable in detecting periapical lesions compared with digital periapical radiographs.

The influence of brushing motion on the cutting behavior of 3 reciprocating files in oval-shaped canals.

INTRODUCTION: The purpose of this study was to compare the cutting efficiency of 3 reciprocating single-file systems used with a brushing motion in oval-shaped canals. METHODS: Sixty premolars with single oval canals were selected and randomly assigned to 3 groups according to the file used in canal instrumentation: R25 Reciproc (VDW, Munich, Germany), Primary WaveOne ((Dentsply Maillefer, Ballaigues, Switzerland), and a novel prototype instrument (UFile; MicoMega, Besancon, France). Instrumentation was performed in 4 consecutive steps; according to manufacturers' instructions, 5 brushing strokes against the buccal wall with a nonworking instrument followed by another 5 and 15 brushing strokes with a working file. Cone-beam computed tomographic scans were taken after each step of preparation. Pre- and postinstrumentation images were superimposed at the apical and midroot levels and then evaluated in terms of changes in the maximum buccolingual (ΔBL) and mesiodistal dimensions (ΔMD). RESULTS: Instrumentation with a brushing motion resulted in the following findings. At the apical levels, no significant difference was found in ΔBL for the 3 groups (P > .05). However, ΔMD was significantly less for the Reciproc (P = .006) and UFile (P = .03) groups. At the midroot levels, the UFile group showed the highest significance in terms of ΔBL (P < .0001) but the lowest in terms of ΔMD (P = .003). ΔMD was significantly the highest for the WaveOne group at the midroot levels (P = .05). CONCLUSIONS: The prototype file was more efficient than the other files at the midroot levels, whereas all systems acted the same at the apical levels. The increase in the number of brushing strokes resulted in more dentinal cutting in the direction of those strokes.

Dentinal crack formation during root canal preparations by the twisted file adaptive, Reciproc and WaveOne instruments.

OBJECTIVE: This study aimed to compare the frequency of dentinal microcracks after root canal shaping with 2 reciprocating (Reciproc and WaveOne) and 1 combined continuous reciprocating motion twisted files adaptive (TFA) rotary system. MATERIALS AND METHODS: Ninety molars were chosen and divided into three groups of 30 each. Root canal preparation was achieved by using Reciproc R25, Primary WaveOne and TFA systems. All the roots were horizontally sectioned at 15, 9, and 3 mm from the apex. The slices were then viewed each under a microscope at × 25 magnification to determine the presence of cracks. The absence/presence of cracks was recorded, and the data were analyzed with a Chi-square test. The significance level was set at P < 0.05. RESULTS: Instrumentation with Reciproc produced significantly more complete cracks than WaveOne and TFA (P = 0.032). The TFA system produced significantly less cracks then the Reciproc and WaveOne systems apically (P = 0.004). CONCLUSIONS: Within the limits of this study, the TFA system caused less cracks then the full reciprocating system (Reciproc and WaveOne). Single-file reciprocating files produced significantly more incomplete dentinal cracks than full-sequence adaptive rotary motion.

Micro-computed tomographic evaluation of canal transportation instrumented by different kinematics rotary nickel-titanium instruments.

INTRODUCTION: The purpose of this study was to evaluate and compare canal transportation of curved root canals by using 3 nickel-titanium systems: Reciproc, WaveOne, and Twisted Files Adaptive (TF). METHODS: Twenty-four extracted human mandibular molars with 2 separate mesial canals and severe angle of curvature were selected. Individual canals were divided randomly to 1 of the 3 experimental groups: Reciproc group, reciprocating instrumentation with Reciproc R25; WaveOne group, reciprocating instrumentation with the Primary WaveOne file; and TF Adaptive group, Adaptive Rotary Motion with the TF files. Each group consisted of 16 root canals. Specimens were scanned before and after root canal preparation with an isotropic resolution of 20 µm by using micro-computed tomography. The degree of canal transportation, in addition to instruments' centering ability, was recorded. RESULTS: Less transportation occurred with TF Adaptive rotary instruments (P < .0001). The mean degree of canal transportation in the apical third was significantly lower with TF Adaptive group (P < .0001). No significant difference was found between Reciproc and WaveOne systems (P = 1.000). Mean centering ratio was the highest statistically with TF Adaptive (P < .0001), followed by WaveOne, and was minimal with Reciproc (P < .05). CONCLUSIONS: The TF Adaptive system was found to have less canal transportation and better centering ability when compared with the reciprocating groups.

Removal efficiency of calcium hydroxide dressing from the root canal without chemically active adjuvant.

AIM: Compare the efficiency in removing two calcium hydroxide [Ca(OH)2] preparations from root canal and apical third using single use syringe, ultrasonics and RinsEndo((®)) with saline solution. MATERIALS AND METHODS: One hundred and eighty human singlerooted teeth were instrumented using ProTaper((®)) rotary system, divided into two groups according to Ca(OH)2 filling. A: Powder mixed with water, B: Pulpdent((®)). Each group was divided into three subgroups for the irrigation: A1, B1: Single use syringe; A2, B2: Ultrasonics; A3, B3: RinsEndo((®)). Teeth were split longitudinally, photographed and imported into Adobe Photoshop. The percentage ratios of Ca(OH)2 remaining in the canal and in the apical third were calculated. Data were statistically analyzed using 'ANOVA two-way' and 'univariate tests'. RESULTS: (a) Remnants of medicament were found in all teeth, (b) no statistically significant difference in the elimination of both Ca(OH)2 from the entire canal (p = 0.436), however, mixed powder was better eliminated from the apical third (p = 0.005), (c) no statistically significant difference among the irrigation techniques in the whole canal (p = 0.608), though, RinsEndo((®)) and ultrasonics were the most effective in cleaning the apical third (p = 0.032) when mixed powder was used. CONCLUSION: None of the techniques removed completely Ca(OH)2 from the canal. In the apical third, RinsEndo((®)) and ultrasonics were the most effective when mixed powder was used. CLINICAL SIGNIFICANCE: Ca(OH)2, the most commonly used intracanal dressing, should be completely eliminated before the obturation to assure a good endodontic sealing. Based on the results of this study, RinsEndo((®)) and ultrasonics were the most effective in removal of Ca(OH)2 especially the powder mixed with water presentation.

MM-MTA for direct pulp capping: a histologic comparison with ProRoot MTA in rat molars.

AIM: To compare the histomorphological response of rat dental pulps capped with MM-MTA and ProRoot MTA at 1, 2 and 4 weeks postoperatively. MATERIALS AND METHODS: Direct pulp capping with MM-MTA and ProRoot MTA, overlaid with light-cured composite resin, was performed on right and left maxillary first molars of 20 Wistar rats. Animals were killed at 1, 2 and 4 weeks postoperatively. Biopsy samples were stained and viewed by light microscopy to determine dentin bridge formation. Data were statistically evaluated with the Kruskal-Wallis test (p < 0.05). RESULTS: Absence of dentin bridge formation at 1 week, partial dentin bridge formation at 2 weeks and complete dentin bridge formation at 4 weeks are observed with MM-MTA and ProRoot MTA. The results showed no statistically significant difference between both materials at 4 weeks. CONCLUSION: Both materials produced similar responses in the pulp when used for pulp capping in intact, caries-free molars of rats.