Fracture resistance of simulated immature teeth after apexification with calcium silicate-based materials.

OBJECTIVE: To compare the fracture resistance of simulated immature teeth filled with an apical barrier of mineral trioxide aggregate (MTA), Biodentine, and calcium-enriched mixture (CEM). MATERIALS AND METHODS: Fifty-two single-rooted human maxillary central incisors were used. For standardization, the teeth were sectioned 6 mm above and 9 mm below the cementoenamel junction to simulate immature apex. Simulations of roots into immature apices were carried out using 1.5 mm diameter drills. The specimens were then randomly divided into three experimental groups (n = 13) and one control group (n = 13). In experimental groups, MTA, Biodentine, and CEM were placed to apical 4 mm of the simulated immature roots. The samples were stored at 37° C and 100% humidity for 1 week. A load was applied on the crown of all teeth at 135° to their long axis until fracture. The data were analyzed using one-way analysis of variance and Tukey post-hoc tests. RESULTS: No statistically significant differences were found among MTA, CEM, and Biodentine (P > 0.05), and these groups demonstrated higher fracture resistance than control group (P < 0.05). CONCLUSIONS: Using any of the MTA, Biodentine, and CEM as an apical plug and restoring with fiber post and composite resin increases the fracture resistance of immature teeth.

Effects of different instrumentation techniques on calcium hydroxide removal from simulated immature teeth.

The aim of this study was to evaluate the effectiveness of endodontic instrument systems in the removal of calcium hydroxide [Ca(OH)(2)] from simulated immature teeth. The root canals of 106 human single-rooted teeth were shaped with ProTaper rotary files up to an F5 file size. Simulation of roots with immature apices was carried out using size 4 green 1.5-mm diameter Unicore drills. A non-setting Ca(OH)(2) was injected into each root canal and inserted into the working length using lentulo spiral, after which cotton pellets were placed over canal orifices. The apical and coronal side of the roots were then sealed with glass ionomer cement and light cured. Specimens were stored in distilled water for 3 months at 37 °C. After 3 months, the temporary coronal seal was removed and the samples were randomly divided into five experimental groups according to the method used for Ca(OH)(2) removal (ProTaper, Reciproc, OneShape, WaveOne, and Manual) (n = 20), one positive control group (n = 3) and one negative control group (n = 3). The amount of remaining Ca(OH)(2) in the canal walls was measured under a stereomicroscope at 30× magnification. The data were analyzed using Kruskal-Wallis test and Mann-Whitney U test at a significance level of 0.05. Positive and negative control groups were found to be statistically different from all other groups (p < 0.05). There were no significant differences among the ProTaper, Reciproc, OneShape, WaveOne, and Manual groups (p > 0.05). As a conclusion, none of the techniques completely removed Ca(OH)(2) from simulated immature teeth.

Shear Bond Strength of a Self-adhering Flowable Composite and a Flowable Base Composite to Mineral Trioxide Aggregate, Calcium-enriched Mixture Cement, and Biodentine.

INTRODUCTION: The purpose of this study was to investigate the shear bond strength (SBS) of a self-adhering flowable composite (Vertise Flow; Kerr, Orange, CA) and a flowable composite (X-tra base; Voco GmbH, Cuxhaven, Germany) to mineral trioxide aggregate (MTA), Biodentine (Septodent, Saint-Maur-des-Fosses Cedex, France), and calcium-enriched mixture (CEM; Yektazist Dandan, Tehran, Iran). METHODS: Sixty cylindric acrylic blocks with a hole (3 mm in diameter and 1.5 mm in height) were prepared. The acrylic blocks were filled with MTA, Biodentine, and CEM (n = 20) and accordingly allocated into 3 groups. The specimens were stored for 72 hours at 37°C and 100% humidity. Then, each group was divided into 2 subgroups according to the composite resin type used (n = 10). Vertise Flow and X-tra base were applied over MTA, Biodentine, and CEM and then polymerized. SBS was tested in a universal testing machine with a crosshead speed of 1 mm/min. Data were analyzed using 2-way analysis of variance and the Tukey test. RESULTS: The Vertise Flow-CEM and X-tra base-MTA groups showed significantly higher SBS values than the group made of Vertise flow-Biodentine (P < .05). There were no statistically significant differences among the other groups (P > .05). CONCLUSIONS: MTA and CEM exhibited higher SBS than Biodentine; therefore, they could be preferred under flowable composites.

Effectiveness of different irrigation solutions on triple antibiotic paste removal from simulated immature root canal.

To evaluate the effectiveness of different irrigation solutions and ultrasonic activation of irrigation solutions on removal of triple antibiotic paste (TAP) from root canals of the simulated immature teeth. Fifty single-rooted teeth were used. TAP was placed into each root canal, and specimens were stored in distilled water for 4 weeks at 37°C. After 4 weeks, the temporary coronal seal was removed and the samples were randomly divided into five groups as follows: (i) saline; (ii) ultrasonic activation of saline; (iii) NaOCl; (iv) ultrasonic activation of NaOCl; (v) chlorhexidine digluconate (CHX). The amount of remaining TAP on the canal walls was measured under stereomicroscope with 30× magnification. The data were analyzed using a one-way ANOVA and post-hoc Tukey test at a significance level of 0.05. There were statistically differences among CHX and ultrasonic activation of NaOCl and other groups (p < 0.05). There were no significant differences among the ultrasonic activation of saline, NaOCl, and saline groups (p > 0.05). Irrigation solutions and ultrasonic activation of the irrigation solutions could not completely remove the triple antibiotic paste from simulated immature root canals. Ultrasonic activation of the NaOCl gave the best and CHX was the worst results.

Fracture strength of roots instrumented with three different single file systems in curved root canals.

OBJECTIVE: The aim of this study was to compare the fracture strength of roots instrumented with three different single file rotary systems in curved mesial root canals of maxillary molars. MATERIALS AND METHODS: Curvatures of 25°-35° on mesial roots of 60 maxillary molar teeth were sectioned below the cementoenamel junction to obtain roots 11 mm in length. The roots were balanced with respect to buccolingual and mesiodistal diameter and weight. They were distributed into three experimental groups and one control group (no instrumentation) (n = 15): Reciproc rotary file (R25, VDW, Munich, Germany), WaveOne Primary rotary file (Dentsply Tulsa Dental Specialties, Tulsa, UK) and OneShape (Micro-Mega, Besancon, France) rotary file. Vertical load was applied until fracture occurred. Data were statistically analyzed using one-way analysis of variance test (P < 0.05). RESULTS: The mean fracture load was 412 ± 72 Newton (N) for the control group, 395 ± 69 N for the Reciproc group, 373 ± 63 N for the WaveOne group and 332 ± 68 N for the OneShape group. The fracture load differences among three experimental groups were not statistically significant (P > 0.05.) Whereas, the fracture loads of control and OneShape groups were significantly different (P = 0.012). CONCLUSIONS: Fracture resistance of the roots instrumented with WaveOne and Reciproc file systems were similar to the control group whereas it was observed that OneShape rotary file systems enhance the fracture strength of standardized curved roots when compared with the control group.

Comparison of cytotoxicity of various concentrations origanum extract solution with 2% chlorhexidine gluconate and 5.25% sodium hypochlorite.

OBJECTIVE: The purpose of this in vitro study was to compare the cytotoxicity of 0.5-4.5 origanum extract solution (OES), 2% chlorhexidine gluconate (CHX) and 5.25% sodium hypochlorite (NaOCl) with WST-1 test on human periodontal ligament (hPDL) fibroblasts. MATERIALS AND METHODS: About 0.5-4.5% OES, 2% CHX and 5.25% NaOCl solutions cytotoxicity was evaluated with cell culture test using PDL fibroblasts. Viability of hPDL cells was evaluated with WST-1 (Cell Proliferation Reagent WST-1 Roche) test at 1, 24 and 72(nd) h. hPDL cells were plated at 20 × 10(3) cells per well in 96-well plates. Absorbance values were read in optical density 480 nm by ELISA plate reader spectrophotometer. The statistical differences between various groups were evaluated using one-way ANOVA, post-hoc Duncan's Multiple Range test using SAS software. Statistically, a significant difference was considered at P < 0.001. RESULTS: According to the 1-h cytotoxicity results, 0.5% OES showed the least cytotoxic effect in test groups. There were not found any statistical significance between 1% OES and 2% CHX. About 5.25% NaOCl showed more cytotoxic effect than 1% OES and 2% CHX. In 24 and 72 h, different concentrations of OES, 5.25% NaOCl, 2% CHX solutions showed similar cytotoxic effect. CONCLUSIONS: Based on these results, 1% OES and 2% CHX showed similar results and less cytotoxic effect than 5.25% NaOCl. It could be considered as a favorable solution concentration when OES was used as root canal irrigation solution.

Antibacterial and smear layer removal capability of oregano extract solution.

OBJECTIVE: The aim of this in vitro study was to evaluate the antimicrobial effect of oregano extract solution (OES) against Enterococcus faecalis within root canals and dentin tubules, and its effect on smear layer. MATERIALS AND METHODS: A total of 180 human maxillary central incisors was selected. After removal of coronal part of the teeth, root canals were prepared using ProTaper rotary files (Dentsply, Tulsa Endodontics, OK, USA) to #F3 with the crown-down manner. The roots were randomly assigned to 15 groups (n = 12 for each). In the first seven groups, the antimicrobial effects of the test groups were evaluated. Suspensions of E. faecalis cultures were adjusted to 1.0 McFarland (1 × 10(8) colony-forming unit [CFU]/ml), and sterilized teeth were placed in Eppendorf tubes and kept at 37°C for 4 weeks. Samples were then taken from the root canals before irrigation using three sterile paper points. Dentin samples were taken from root canals with ProTaper #F4 and #F5 series rotary instruments after irrigation. The aliquots of samples were placed into the brain heart infusion and incubated at 37°C for 48 h and then the CFUs were counted. In the other eight groups, the efficacy of the irrigation solutions on removing the smear layer was evaluated using scanning electron microscope (Leo 440, Oxford Microscopy Ltd., Cambridge, England) analysis. Statistical evaluation of the microbiological data was performed using the Kruskall-Wallis and Mann-Witney U-test (P < 0.05). RESULTS: There was a statistically difference between the groups (P < 0.05). Chlorhexidine gluconate (CHX), 5% and 2% OES wasn't found to be statistically significant regarding their antibacterial activities against E. faecalis (P > 0.05). 1% OES and NaOCl showed similar antimicrobial effect (P > 0.05), and 1% OES and NaOCl were better than ethylenediaminetetraacetic acid (EDTA) and saline (P < 0.05) but not as successful as CHX. According to the results obtained from dentin, CHX is the most effective solution within dentinal tubules. Different concentrations of OES were not achieved smear layer removal alone but OES in conjunction with 17% EDTA was the final irrigating solution achieved the smear layer removal without dentin erosion. CONCLUSIONS: Within the limitations of this study, OES appears to be a possible alternative to NaOCl as a root canal irrigant on the eradication of E. faecalis and removal of smear layer.

Effectiveness of different irrigation protocols on calcium hydroxide removal from simulated immature teeth after apexification.

Aim: To evaluate the effectiveness of different irrigation solutions and ultrasonic activation of the irrigation solutions on the removal of calcium hydroxide (Ca(OH)2) from the simulated immature root canals after apexification. Materials and methods: One-hundred and one single-rooted teeth were used. The root canals were shaped with ProTaper rotary files up to F5. Simulation of roots with immature apices was carried out using size 4 Unicore drills. An injectable Ca(OH)2 was injected into each root canal, and packed to the working length. Then, cotton pellets were placed over canal orifices, and apical and coronal parts of the roots were sealed with resin-modified glass ionomer cement, and light cured. Specimens were stored in distilled water for 3 months at 37°C. After 3 months, the temporary coronal seal was removed and the samples were randomly divided into: (a) saline (n = 20), (b) ultrasonic activation of saline (n = 20), (c) sodium hypochlorite (NaOCl) (n = 20), (d) ultrasonic activation of NaOCl (n = 15), (e) chlorhexidine digluconate (CHX) (n = 20) and one positive control group (n = 3) and one negative control group (n = 3). The amount of remaining Ca(OH)2 on the canal walls was measured under stereomicroscope with 30× magnification. Comparisons between groups were made by the non-parametric Kruskal-Wallis test and Dunn post-test at a significance level of p < 0.05. Results: There were no significant differences among the saline, ultrasonic activation of saline, NaOCl, ultrasonic activation of NaOCl and CHX (p > 0.05) groups. Conclusions: Irrigation solutions and ultrasonic activation of the irrigation solutions could not completely remove Ca(OH)2 from the simulated immature root canals.

Applicability of the Demirjian method for dental age estimation in western Turkish children.

OBJECTIVE: The aim of this study was to examine whether the Demirjian method would be appropriate for estimation of the dental age of western Turkish children. MATERIALS AND METHODS: This study comprised 635 Turkish children (age = 7-16 years) from the western Aegean region who were chosen on the basis of radiological evidence from digital orthopantomograms. Their dental maturity was evaluated according to the stages proposed by Demirjian. A paired t-test was used for statistical analysis. RESULTS: The mean difference between the chronological and dental ages ranged from 0.10-0.76 years for males and from 0.28-0.87 years for females. CONCLUSION: The applicability of the Demirjian method is not suitable for western Turkish children and western Turkish children have a lower degree of dental maturity than that observed in the eastern, northeastern and northern Turkish subjects.

Effect of the size of the apical enlargement with rotary instruments, single-cone filling, post space preparation with drills, fiber post removal, and root canal filling removal on apical crack initiation and propagation.

INTRODUCTION: The purpose of this study was to investigate the incidence of apical crack initiation and propagation in root dentin after several endodontic procedures. METHODS: Sixty intact mandibular premolars were sectioned perpendicular to the long axis at 1 mm from the apex, and the apical surface was polished. Thirty teeth were left unprepared and served as a control, and the remaining 30 teeth were instrumented with ProTaper Universal instruments (Dentsply Maillefer, Ballaigues, Switzerland) up to size F5. The root canals were filled with the single-cone technique. Gutta-percha was removed with drills of the Rebilda post system (VOCO, Cuxhaven, Germany). Glass fiber-reinforced composite fiber posts were cemented using a dual-cure resin cement. The fiber posts were removed with a drill of the post system. Retreatment was completed after the removal of the gutta-percha. Crack initiation and propagation in the apical surfaces of the samples were examined with a stereomicroscope after each procedure. The absence/presence of cracks was recorded. Logistic regression was performed to analyze statistically the incidence of crack initiation and propagation with each procedure. RESULTS: The initiation of the first crack and crack propagation was associated with F2 and F4 instruments, respectively. The logistic regression analysis revealed that instrumentation and F2 instrument significantly affected apical crack initiation (P < .001). Post space preparation had a significant effect on crack propagation (P = .0004). The other procedures had no significant effects on crack initiation and propagation (P > .05). CONCLUSIONS: Rotary nickel-titanium instrumentation had a significant effect on apical crack initiation, and post space preparation with drills had a significant impact on crack propagation.

Evaluation of technical quality and periapical health of root-filled teeth by using cone-beam CT

Objective This study aimed to assess the quality of root fillings, coronal restorations, complications of all root-filled teeth and their association with apical periodontitis (AP) detected by cone-beam computed tomography (CBCT) images from an adult Turkish subpopulation. Material and Methods The sample for this study consisted of 242 patients (aging from 15 to 72 years) with 522 endodontically treated teeth that were assessed for technical quality of the root canal filling and periapical status of the teeth. Additionally, the apical status of each root-filled tooth was assessed according to the gender, dental arch, tooth type and age classification, undetected canals, instrument fracture, root fracture, apical resorption, apical lesion, furcation lesion and type and quality of the coronal structure. Statistical analysis was performed using percentages and chi-square test. Results The success rate of the root canal treatment was of 54.4%. The success rates of adequate and inadequate root canal treatment were not significantly different (p>0.05). Apical periodontitis was found in 228 (45.6%) teeth treated for root canals. Higher prevalence of AP was found in patients aging from 20 to 29 years [64 (27%) teeth] and in anterior (canines and incisors) teeth [97 (41%) teeth]. Conclusions The technical quality of root canal filling performed by dental practitioners in a Turkish subpopulation was consistent with a high prevalence of AP. The probable reasons for this failure are multifactorial, and there may be a need for improved undergraduate education and postgraduate courses to improve the clinical skills of dental practitioners in endodontics. .

A cone-beam computed tomography study of the root canal morphology of anterior teeth in a Turkish population.

OBJECTIVE: The aim of this study was to determine the root and canal morphology of the maxillary and mandibular anterior teeth in a Turkish population by analyzing cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: CBCT images of 417 females and 410 males with a mean age of ranging from 14 to 70 years were examined in this study. A total of 1453 maxillary central incisors, 1504 maxillary lateral incisors, 1523 maxillary canines, 1582 mandibular central incisors, 1603 mandibular lateral incisors, and 1604 mandibular canines were analyzed. The number of root canals and the canal configurations were investigated and then were classified according to Vertucci's classification. The data were analyzed with the Pearson Chi-square test. RESULTS: The Type 1 canal configuration was most prevalent in the maxillary anterior teeth (96.8-99.7%). The Types 2, 3, 4, and 5 canal configurations were observed within the range of 0-1.3%, 0-0.8%, 0-0.7%, and 0-1.8%, respectively. In the mandibular anterior teeth, the Type 1 canal configuration was most prevalent (77-95%). The Types 2, 3, 4, and 5 canal configurations were observed within a range of 0.2-2.7%, 0.2-1.6%, 0.9-5.9%, and 1.8-14.4%, respectively. The prevalence of two canals was higher in males than in females both in the maxillary and mandibular anterior teeth (P < 0.05). CONCLUSIONS: Type 1 was the most prevalent canal configuration of maxillary and mandibular anterior teeth in the Turkish population. Type 5 was the most frequently observed canal configuration of the two canalled teeth. The incidence of root canal numbers and configurations differed with sex.

Push-out bond strength of different mineral trioxide aggregates.

OBJECTIVE: This study was aimed to evaluate and to compare the push-out bond strength of different brands of mineral trioxide aggregate (MTA) with a calcium enriched mixture cement (CEM). MATERIALS AND METHODS: Fifteen extracted, single-rooted human teeth were used. The middle-third of the roots were sliced perpendicular to the long axis into 1.00 ± 0.05 mm thick serial slices (15 root × 4 slice = 60 specimen). The specimens were then divided into three groups (n = 20). The standardized root discs were filled with white CEM, ProRoot MTA, MTA-Angelus and wrapped in a serum-soaked gauze. After 3 days at relative humidity, the push-out bond strengths were measured with a universal testing machine. Data were analyzed using one-way analysis of variance and post hoc Tukey tests. RESULTS: The mean push-out bond strength value of the ProRoot MTA group (12.7 ± 2.5 MPa) was the highest and statistically significant difference was recorded between ProRoot MTA and other groups (P < 0.001). There was no significant difference between the mean bond strength of CEM cement (4.6 ± 1.1 MPa) and MTA-Angelus (4.5 ± 1.5 MPa) (P = 0.982). CONCLUSION: The push-out bond strength of MTA was changed with the brands and ProRoot MTA had the highest push-out bond strength.

Efficacy of needle irrigation, EndoActivator, and photon-initiated photoacoustic streaming technique on removal of double and triple antibiotic pastes.

INTRODUCTION: Photon-induced photoacoustic streaming (PIPS) is a novel technique used for the removal of material on root canal walls, such as bacteria and the smear layer. This study evaluated the efficacy of needle irrigation, the EndoActivator System (Dentsply Tulsa Dental Specialties, Tulsa, OK), and PIPS on the removal of antibiotic pastes from an artificial groove created in a root canal. METHODS: Root canal preparation was performed up to size #40 on 84 extracted single-rooted teeth using ProTaper rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland). The specimens were then split longitudinally, and 2 standardized grooves were prepared in the coronal and apical part of each segment. Double (DAP) and triple antibiotic pastes (TAP) were placed in the grooves for 4 weeks, and the root halves were reassembled. Needle irrigation, the EndoActivator System, and PIPS were used for the removal of DAP and TAP. The root segments were disassembled, and the amount of remaining antibiotic pastes was evaluated under a stereomicroscope at 20× magnification using a 4-grade scoring system. The data were evaluated statistically using Mann-Whitney U tests with a 95% confidence level (P = .05). RESULTS: PIPS removed significantly more antibiotic pastes than the EndoActivator and needle irrigation (P < .001). The EndoActivator was superior to needle irrigation in removing antibiotic pastes (P < .001). There were no statistically significant differences between DAP and TAP and between coronal and apical thirds in their removing from artificially created grooves (P > .05). CONCLUSIONS: PIPS was more effective in removing both DAP and TAP from artificial grooves in root canals than the EndoActivator System and needle irrigation. The EndoActivator was also more effective than needle irrigation. It is difficult to completely remove antibiotic pastes from root canals.

Effect of photo-activated disinfection on bond strength of three different root canal sealers.

INTRODUCTION: The aim of this in vitro study was to evaluate the bond strength of Photo-Activated Disinfection (PAD) system to dentin with different root canal sealers by using a push-out test design. MATERIALS AND METHODS: A total of 30 extracted mandibular premolar teeth with single and straight roots were used. The crowns were removed and the root canals were prepared by using ProTaper rotary files. The smear layer was removed and the roots were randomly divided into two groups (n = 15) according to the use of PAD system as the final disinfecting agent. Each group was then divided into 6 (n = 5) subgroups and obturated with gutta-percha and 3 different root canal sealers. The groups were Group 1: Sodium hypochlorite (NaOCl) + ethylenediaminetetraacetic acid (EDTA)-AH Plus sealer; Group 2: NaOCl + EDTA + PAD-AH Plus; Group 3: NaOCl + EDTA-Sealapex; Group 4: NaOCl + EDTA + PAD-Sealapex; Group 5: NaOCl + EDTA-mineral trioxide aggregate (MTA)-Fiallapex; and Group 6: NaOCl + EDTA + PAD-MTA-Fillapex. 1-mm thickness horizontal sections (n: 5 × 4 = 20) were sliced for the push-out bond strength measurement. RESULTS: Group 3 and 4 showed significantly lower bond strengths compared with all the other groups (P < 0.05). No statistically significant difference was found among Groups 1, 2 and 5, but there was statistically significant difference between Group 5 and 6 (P < 0.05). CONCLUSION: This in vitro study indicated that the PAD system adversely affected the bond strength of the MTA Fillapex root canal sealer.

Evaluation of the root and canal morphology of mandibular permanent molars in a south-eastern Turkish population using cone-beam computed tomography.

OBJECTIVE: The aim of this retrospective study was to determine the root and canal morphology of the mandibular first and second permanent molars in a Turkish population using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT images of mandibular first (n = 966) and second molar (n = 1165) teeth from 850 Turkish patients were evaluated. The root canal configurations were classified according to the method of Vertucci. The data were analyzed by Pearson's Chi-square test. RESULTS: The majority of mandibular molars were two rooted with three canals; however, three roots were identified in 0.05% of the first molars and 0.01% of the second molars, and 100% of the additional root canals were of type I configuration. Mesial roots had more complex canal systems with more than one canal, whereas most distal roots had a type I configuration. CONCLUSIONS: Within the limitations of this study, it can be concluded that CBCT scanning provides supplemental information about the root canal configurations of mandibular molars in a Turkish population. This study may help clinicians in the root canal treatment of mandibular molars.

Evaluation of the relationship between the maxillary posterior teeth and the sinus floor using cone-beam computed tomography.

AIM: The aim of this study was to evaluate the relationship between each root of maxillary premolars and molars and the maxillary sinus floor according to sex, sinus position, and age by decade in a Turkish population by using cone-beam computed tomography (CBCT) scanning. METHODOLOGY: We evaluated a database of 5,166 (2,680 maxillary premolars and 2,486 maxillary molars) CBCT scans obtained from 849 patients. The vertical relationship between each root of the molar and premolar teeth to the sinus floor was classified into three types: type 1, the roots penetrated into the sinus floor; type 2, the roots contacted the sinus floor; and type 3, the roots extended below the sinus floor. RESULTS: The results of the classification of each root in relationship to the sinus floor were as follows: type 3 occurred most frequently in the first (92.4 %) and second (71.6 %) premolar teeth, type 1 (34.2 %) occurred most frequently in the palatinal roots of the first molar teeth, type 3 occurred most frequently in the mesiobuccal (39.9 %) and distobuccal (39.7 %) roots of the first molar teeth, and type 2 (36.7 %) occurred most frequently in the mesiobuccal roots of the second molar teeth. No significant differences were found between the left and right sides, but several differences were found between males and females. The relationship between the posterior teeth and the sinus floor differed according to the age decade interval (p < 0.05). CONCLUSIONS: The maxillary first premolars have no relationship with the maxillary sinus floor, but the maxillary second molars are closer to the sinus floor. Also the second decade and males were most susceptible to undesirable results.

Comparative study of different novel nickel-titanium rotary systems for root canal preparation in severely curved root canals.

INTRODUCTION: We compared the effects of 6 different rotary systems on transportation, canal curvature, centering ratio, surface area, and volumetric changes of curved mesial root canals of mandibular molar via cone-beam computed tomographic (CBCT) imaging. METHODS: Mesiobuccal root canals of 120 mandibular first molars with an angle of curvature ranging from 20°-40° were divided into 6 groups of 20 canals. Based on CBCT images taken before instrumentation, the groups were balanced with respect to the angle and radius of canal curvature. Root canals were shaped with the following systems with an apical size of 25: OneShape (OS) (MicroMega, Besancon, France), ProTaper Universal (PU) F2 (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next X2 (Dentsply Maillefer), Reciproc (R) R25 (VDW, Munich, Germany), Twisted File Adaptive (TFA) SM2 (SybronEndo, Orange, CA), and WaveOne primary (Dentsply Tulsa Dental Specialties, Tulsa, OK). After root canal preparation, changes were assessed with CBCT imaging. The significance level was set at P = .05. RESULTS: The R system removed a significantly higher amount of dentin than the OS, PU, and TFA systems (P < .05). There was no significant difference among the 6 groups in transportation, canal curvature, changes of surface area, and centering ratio after instrumentation. CONCLUSIONS: The 6 different file systems straightened root canal curvature similarly and produced similar canal transportation in the preparation of mesial canals of mandibular molars. R instrumentation exhibited superior performance compared with the OS, TFA, and PU systems with respect to volumetric change.

A cone-beam computed tomography study of root canal morphology of maxillary and mandibular premolars in a Turkish population.

AIM: The aim of this study was to evaluate the root canal number and configuration of maxillary and mandibular premolar teeth by gender, intervals for decades, tooth position and unilateral or bilateral occurrence in a Turkish population using Cone Beam Computed Tomography(CBCT) scanning. METHODOLOGY: CBCT images of 5496 maxillary and mandibular premolars from 849 patients were evaluated. The following was evaluated in all the images: numbers of roots and root canals, the morphology of the root canal configuration according to the Vertucci classification, male-female differences in the tooth position and male-female differences in unilateral or bilateral occurrence. The reliability data were analyzed with a chi-square test. RESULTS: The most prevalent root canal frequency was the two canals (86.2%) and type IV (76.9%) configuration for maxillary first premolar, one canal (59.7%) and type I (54.5%) canal configuration for second premolar. The incidence of one canal was higher in females and the occurrence of two or three canals was more common in males. The incidence of one canal was higher on the left side of maxillary premolars and the incidence of two canals was higher on the right side. Most mandibular first (93.5%) and second (98.5%) premolars had one canal. In general, females had one root canal of the mandibular premolar, whereas males had two or three canals. The type I configuration was most common and the incidence was higher on the right side. There were some differences found in the frequency distribution of the number of root canals and configuration of maxillary and mandibular premolar teeth according to intervals for decades. CONCLUSION: CBCT scanning provides comprehensive information about the root canal morphology of maxillary and mandibular premolar teeth. These data may help clinicians in root canal treatment of premolar teeth.

Effects of different irrigating solutions and disinfection methods on push-out bond strengths of fiber posts.

OBJECTIVE: The aim of this study was to evaluate the effects of various irrigating solutions and photoactivated disinfection (PAD) on the push-out bond strengths of fiber posts to root dentin. MATERIALS AND METHODS: Thirty-two human teeth were divided into eight groups, as follows: (1) irrigation with physiologic saline (control), (2) NaOCl irrigation, (3) chlorhexidine (CHX) irrigation, (4) ethanol (EtOH) irrigation, (5) NaOCl followed by 17% EDTA irrigation, (6) NaOCl-EDTA supplemented with CHX irrigation, (7) NaOCl-EDTA supplemented with EtOH irrigation and (8) NaOCl-EDTA irrigation supplemented with PAD. After the posts were cemented, the roots were transversally sectioned to obtain four slices (1 mm thick) (n = 16). Push-out tests were conducted by applying a load at 0.5 mm/min, types of fracture failures were recorded and data were analyzed with one-way ANOVA and Tukey post-hoc tests (p = 0.05). RESULTS: Push-out bond strength was significantly affected by the type of irrigating solution and the disinfection protocol (p < 0.05). The bond strength of the EtOH, NaOCl and NaOCl-EDTA-CHX irrigated groups was significantly higher than that of the other groups. The highest bond strength was observed in the EtOH irrigated group and the lowest was the NaOCl-EDTA irrigated group. CONCLUSIONS: Irrigation with NaOCl and EDTA combined caused lower bond strength than observed in the control group. However, supplementing this combination with CHX improved the post-dentin bond strengths; supplementing with PAD did not.