Evaluation of Different Restoration Combinations Used in the Reattachment of Fractured Teeth: A Finite Element Analysis.

OBJECTIVE: The purpose of this study was to test different restoration combinations used for constructing fractured endodontically treated incisors by reattaching their fractured fragments. METHODS: Seven types of 3-D FEM mathematical root canal-filled models were generated, simulating cases of (OB) reattaching fractured fragments; (CrPL) reattaching fractured fragments + ceramic palatinal laminate; (CmPL) reattaching fractured fragments + composite palatinal laminate; (CM) reattaching fractured fragments + coronal 1/3 of the root was filled using core material; (BP) reattaching fractured fragments + glass fiber post; (CP) composite resin restoration + glass fiber post; and (OC) composite resin restoration. A 100-N static oblique force was applied to the simulated teeth with 135° on the node at 2 mm above the cingulum to analyze the stress distribution at the tooth. RESULTS: For enamel tissue, the highest stress values were observed in model BP, and the lowest stress values were observed in model CmPL. For dentine tissue, the highest stress concentrations were observed around the fracture line for all models. CONCLUSIONS: Reattachment of fractured fragments by bonding may be preferred as a restoration option for endodontically treated incisors; also, palatinal laminate decreases the stress values at tooth tissues, especially at the enamel and the fracture line.

Efficacy of Palatal Applications on Fracture Resistance of Reattached Maxillary Central Incisors: An In Vitro Study.

The purpose of this study was to evaluate the effects of different palatal applications on fracture strength of the fractured anterior tooth. Sixty caries-free human maxillary incisors were used. Endodontic treatments of the teeth were performed. Then, the teeth were divided randomly into five groups (n = 12). Crowns of all teeth in groups A-D were cut with diamond discs at a fixed distance of 3 mm from the incisal margin in a plane normal to the buccal surface. In all groups, coronal fragments were reattached to the remaining teeth by bonding with hybrid composite resin. After then, the teeth were restored to the following; group A, bonding and palatal laminate; group B, bonding and creation of a vertical groove; group C, bonding and creation of two slot grooves; group D, bonding only; and group E, intact tooth. It was lesser in group B than in groups C and E (p = 0.007 and p = 0.006, resp.) and lesser in group D than in groups A, C, and E (p = 0.002, p < 0.001, and p < 0.001, resp.). Within the limitations of this in vitro study, it can be concluded that methods employing palatinal laminate and small grooves are clinically feasible for the reattachment of tooth fragments to incisors.

The effect of residual calcium hydroxide on the accuracy of a contemporary electronic apex locator.

OBJECTIVE: The aim of this study was to evaluate the effect of residual calcium hydroxide [Ca(OH)2] on the accuracy of an electronic apex locator (EAL). MATERIALS AND METHODS: Working lengths (WLs) of 56 extracted maxillary incisors were determined initially by two different methods. The first method used the 'APEX' reading of the EAL as a reference point, 0.5 mm was subtracted and recorded as WL0. The second method used the '0.5' reading and the score was recorded as WL0.5 without subtraction. The roots were prepared to WL0 and divided randomly into three experimental groups (n = 16) (1 mm in group A, 2 mm in group B and 4 mm in group C) and a control (n = 8). Specimens in all experimental groups were filled with Ca(OH)2 paste. Following its removal, WLs were re-determined with the same methods. RESULTS: In group C, pre/post WLs were significantly different (p < 0.05). No significant difference was observed between the other experimental groups and the control group. CONCLUSION: Accuracy of EAL decreased proportionally with the amount of paste remaining at the ±0.5-mm tolerance level. Ca(OH)2 paste remnants may cause incorrect EAL readings.

The evaluation of two rotary instrumentation techniques under "operator-related variables" standardized conditions.

OBJECTIVE: We aimed here to evaluate the enlargement characteristics of two nickel-titanium rotary instrument systems that use two different preparation techniques, in simulated root canals under "operator-related variables" standardized conditions. MATERIALS AND METHODS: A total of 40 simulated canals in resin blocks were divided into two groups as the Mtwo group for use with a single-length technique and the ProTaper instrument system group for use with crown down technique. To standardize the operator-related variables, all preparations were carried out with a computer controlled device that was developed and used previously as described in a published study. The pre- and post-operative digital images of the canals were superimposed and measured at 11 levels from the apical tip. The distances between the pre- and post-operative outer lines of the root canals were measured at both the inner and outer sides of the curve. The amount of removed material and the symmetry of the preparations were evaluated. Statistical analyses were performed with Mann-Whitney test. RESULTS: Significantly more material was removed by Mtwo at 9 levels and by ProTaper at 2 levels (P < 0.05) while no significant difference was determined at 11 levels. The preparations made with ProTaper were more symmetrical at 4 levels while no significant difference was determined at 7 levels. CONCLUSION: Mtwo removed significantly more material than ProTaper at different levels of the curved root canals. Mtwo and ProTaper made symmetrical preparations and maintained the original shape of the root canal at different levels under controlled operator-related variables.

Effects of simulated lateral canals on the accuracy of measurements by an electronic apex locator.

BACKGROUND: Accurate determination of the apical terminus plays a significant role in the success of root canal therapy, but accuracy may be affected by the presence of accessory canals. OBJECTIVE: To evaluate the accuracy of a ratio-based electronic apex locator for roots with simulated lateral canals. METHODS: Forty-two single-rooted human teeth were randomly divided into 2 groups. For each tooth, the root canal was prepared to the visually determined working length, and the working length was then measured with the Justy II electronic apex locator. Simulated lateral canals (of 2 different diameters) were then prepared at 3 mm (group A) or 6 mm (group B), and the working lengths were measured again with the same instrument. The measurements were analyzed by one-way analysis of variance. RESULTS: For both groups, there were no significant changes in working length after the creation of simulated canals (p > 0.05). CONCLUSION: Measurements obtained with the ratio-based electronic apex locator were not affected by the preparation of simulated lateral canals, and the instrument was able to accurately determine the location of the tooth apex.

Effects of irrigation solutions on the surface of ProTaper instruments: a microscopy study.

The aim of this study was to evaluate the effects of sodium hypochlorite (NaOCl), chlorhexidine digluconate (CHX), and mixture of tetracycline, citric acid, and detergent (MTAD) solutions on the surfaces of nickel titanium (NiTi) rotary files with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Irrigation solutions including 2.5% NaOCl, 5% NaOCl, 2% CHX, and MTAD were used. Four new ProTaper rotary NiTi files (F3) were immersed in each four irrigation solutions for 10 min, separately. One untreated NiTi file was used as a control specimen. The surface analysis was performed with SEM and AFM. The surface analysis in AFM was performed on 12 different regions located between first and second millimeters from the tip. SEM images were taken with different magnifications. No surface alteration was recorded under SEM evaluation. AFM revealed that the root mean square (RMS) values of all treated specimens were statistically higher than the control sample (P < 0.05). The sample which was treated with CHX showed lowest RMS values in test groups. All tested solutions caused surface alterations. CHX demonstrated limited surface alterations when compared to the other tested solutions.

Effects of sodium hypochlorite on gutta-percha and Resilon cones: an atomic force microscopy and scanning electron microscopy study.

The aim of this study was to evaluate the effects of 6% sodium hypochlorite (NaOCl) on gutta-percha (GP) and Resilon cones. Six standardized GP and Resilon cones were selected and cut 3mm from their tip. One GP and 1 Resilon cone were used as control samples. Cones were immersed in 6% NaOCl for 1, 5, 10, 20, and 30 minutes, thoroughly rinsed with nanopure water, and dried with filter paper. Then, surface topography was analyzed by atomic force microscopy and scanning electron microscopy coupled to an energy-dispersive x-ray (EDX) spectrometer. According to the root mean square and depth analysis values obtained from atomic force microscopic evalution, there were no significant differences found among the GP groups. However significant differences were found among Resilon cones (P ≤ .05). SEM images and EDX graphics showed that there were no prominent differences between GP and Resilon groups. These results showed that 6% NaOCl solution can be used in the disinfection of GP and Resilon cones. No alterations were observed on the GP cones, but it can change the surface of Resilon cones.

Comparison of the efficacy of three different mouthrinse solutions in decreasing the level of streptococcus mutans in saliva.

OBJECTIVES: The aim of this study was to evaluate the effectiveness of three different antiseptic mouthrinse solutions on the saliva samples obtained from the individuals, who had high caries activity rate. METHODS: The efficacy of three antiseptic mouthrinses were evaluated in a study with healthy volunteers. The three antiseptic solutions used in this study were 0.1% octenidine dihydrochloride (Octenisept, Schülke&Mayr, UK), 0.12% chlorhexidine digluconate (Kloroben, Drogsan, Turkey) and an antimicrobial enzymatic rinse (Biotene, Laclede, Inc, USA). A total of 27 adult volunteer subjects were participated in the study. The subjects were stratified into three balanced group. Then the mouth rinses were used by each group according to the manufacturer's directions. The subjects were restricted for 60 minutes for food intake after using the prescribed mouthrinse. The saliva samples were collected from the volunteers at 1, 10 and 60 minutes after their usage in tubes. The tubes were kept in +4 degrees C in a fridge till the evaluation. 10(-3) and 10(-5) dilutions were prepared for each solution and S. mutans were evaluated according to total number of colony forming unit (CFU) per ml. The dilutions were spreaded on the surface of Brucella agar plates for anaerobic incubation for 48 hours. The dilutions were 100, 10(-3) and 10(-5) of the solutions Kloroben, Biotene, Octenisept, and the time factor were 0, 1, 10 and 60 minutes. The statistical analyses were performed by Duncan and Bonferroni tests. RESULTS: Octenisept was found to be more effective over S. mutans than the other mouthrinse solutions (P<.05). CONCLUSIONS: All mouthrinse solutions except Biotene were effective on oral microorganisms.

Efficacy of 3 techniques in removing root canal filling material.

OBJECTIVE: Retreatment of a root canal in the case of infection requires complete removal of previous filling material. This study evaluated the efficacy of 3 techniques in removing laterally compacted Resilon/Epiphany and gutta-percha/AH Plus from straight and curved canals during retreatment. MATERIALS AND METHODS: Extracted human teeth (90 maxillary anterior teeth with single,straight root canals and 90 mandibular molars with mesial canal root curvatures of 20 degrees to 35 degrees ) were divided into 6 groups each consisting of 15 straight and 15 curved root canals. Three groups were obturated using gutta-percha/AH Plus and 3 were obturated with Resilon/Epiphany. After 3 weeks storage at 37 degrees C and 100% humidity, all root canal fillings were removed using a Gates Glidden drill, a Gates Glidden drill plus chloroform or a System B device. RESULTS: For all removal techniques, specimens obturated with gutta-percha/AH Plus showed significantly more remnants of obturation material than specimens filled with Resilon/Epiphany for both straight and curved canals (p < 0.05). Removal time was shorter for Resilon/Epiphany than gutta-percha/AH Plus filling for all techniques and for both curved and straight canals. The Gates Glidden drill and Gates Glidden drill plus chloroform removal techniques were significantly faster than the System B technique for both straight and curved canals. The Gates Glidden drill technique was best for straight canals, whereas the Gates Glidden drill plus chloroform was the best technique for curved canals when removing Resilon/Epiphany sealer. CONCLUSIONS: Removal of Resilon/Epiphany filling resulted in fewer remnants and was faster than gutta-percha/AH Plus removal using a Gates Glidden drill with or without chloroform in both straight and curved canals.

Structural effects of sodium hypochlorite solution on RaCe rotary nickel-titanium instruments: an atomic force microscopy study.

OBJECTIVE: The aim of this study was to investigate the effect of sodium hypochlorite immersion on the surface characteristics of RaCe rotary nickel-titanium instruments using atomic force microscopy (AFM). STUDY DESIGN: Four new RaCe instruments were used in this study (two 30.06 and two 30.02). One 30.06 and one 30.02 instrument were immersed in sodium hypochlorite solution for 5 min. Surface topography of the instruments was evaluated using the AFM. The instruments were analyzed on 11 points along a 3-mm section. Root mean square (RMS) values were used to compare the topographic deviations. The data were analyzed using Student t test. RESULTS: Mean RMS values for NaOCl measurements were higher than the measurements on new files, and the difference was statistically significant (P < .01). CONCLUSION: The AFM results show that NaOCl causes deterioration on the surface of RaCe instruments and should be used with care during clinical use because of the risk of unexpected failure.

Accuracy of two apex-locating handpieces in detecting simulated vertical and horizontal root fractures.

The aim of this study was to evaluate in vitro the effectiveness of TCM Endo V and Tri Auto ZX handpieces in detecting simulated horizontal and vertical root fractures. Forty extracted maxillary incisor teeth were randomly divided into 2 groups as simulated incomplete horizontal and vertical root fractures. Auto reverse and electronic apex locator functions of the 2 handpieces were used in both groups. Repeated measures of analysis test and pairwise comparisons were used for statistical analyses. Both handpieces detected the root fractures in an acceptable range. Furthermore, electronic apex locator function of both devices was more efficient in the process than auto reverse function.

Apical accuracy of two apex-locating handpieces in root canal retreatments of root-end resected teeth.

We aimed to evaluate the accuracy of 2 apex locator integrated endodontic motors during retreatment of root-end resected teeth by using 40 extracted incisor teeth. The apical 3 mm of the roots were resected, and the root lengths were recorded as resected length of the roots. Forty roots were randomly divided into 2 groups of 20 to evaluate the 2 handpieces, Tri Auto ZX and TCM Endo V. The working lengths measured during the auto reverse function and during the electronic apex locator function with Tri Auto ZX and TCM Endo V were recorded and compared with resected length of the roots. The repeated measures analysis of variance was used for statistical analyses. Electronic apex locator functions of both devices might be used for apical accuracy, but the auto reverse functions might not be useful to 0.0-mm accuracy in retreatment procedures of root-end resected teeth.

Enlarging characteristics of four nickel-titanium rotary instrument systems under standardized conditions of operator-related variables.

We aimed to describe a computer-controlled testing device and evaluate the amount of material removed by using 4 Ni-Ti systems in simulated root canals. Eighty resin blocks were used. Hero 642, Hero Shaper, ProFile, and ProTaper rotary instruments were used to prepare the canals. Operator-related variables were standardized with the aforementioned device. Preoperative/postoperative photographic images of canals were measured at 11 levels from the apical tip. Statistical analyses were done with one-way analysis of variance, Tukey honestly significant difference, and Bonferroni tests. Significantly more material was removed by the ProTaper at 9 levels, ProFile at 6, and Hero 642 at 2 levels (P < .05); no significant difference was determined at 5 levels. Our results showed that ProTaper and ProFile removed significantly more material than Hero 642 and Hero Shaper at different levels of the curved root canals under controlled conditions of operator-related variables.

Evaluation of the surface characteristics of used and new ProTaper Instruments: an atomic force microscopy study.

The purpose of this study was to evaluate the topography of new and used ProTaper rotary nickel-titanium (NiTi) instruments by using atomic force microscope. Four new and four used size S1, S2, F1, and F2 instruments were selected for this study. New and used instruments were analyzed on 11 points along a 3-mm section at the tip of the instrument. Quantitative measurements according to the topographic deviations (root mean square) were recorded. Data were analyzed by paired samples t test. Mean root mean square values for used ProTaper instruments were higher than the new ones, and the difference between them was statistically significant. The results of this study showed that used ProTaper instruments demonstrated more surface deformation and wear.

Accuracy of the apex locating function of TCM Endo V in simulated conditions: a comparison study.

OBJECTIVE: The aim of this study was to evaluate the accuracy of the apex-locating function of the TCM Endo V and to compare the results to these of the Root ZX. STUDY DESIGN: Forty-seven extracted maxillary incisor teeth with mature apices and patent single root canals were used for the study. After the root surfaces were cleaned and access cavities were prepared, the true working lengths (TL) were determined with a #10 stainless steel file. All samples were mounted in an alginate model especially developed to test the apex locators. Both electronic apex locators were used according to the manufacturer's recommendations and adjusted to 0.5-mm accuracy to the apical foramen. EL(1) was designates as the working length measured with Root ZX and EL(2) was designated as the working length measured with TCM Endo V. A paired t test was used to statistically analyze the significance of the mean differences at the 95% confidence interval of the differences (P = .001) among TL, EL(1), and EL(2). RESULTS: There were no statistically significant differences between TL and EL(1), TL and EL(2), and EL(1) and EL(2) (P = .001). Both Root ZX and TCM Endo V gave similar results. CONCLUSIONS: TCM Endo V proved to be as reliable as Root ZX but the use of the device to determine the working length was not easy as Root ZX. Further studies are needed to compare TCM Endo V in clinical conditions with similar electric motor and apex locator combined devices.

The efficiency of three different films and radiovisiography in detecting approximal carious lesions.

OBJECTIVE: The aim of this study was to evaluate the efficiency of Ultraspeed, Ektaspeed Plus, and Insight radiographic films, and radiovisiography in detecting approximal carious lesions. METHOD AND MATERIALS: Eighty approximal surfaces of 40 extracted human molars and premolars were evaluated. Radiographs of teeth blocks were taken with three different films and radiovisiography under standard conditions. The presence or absence of approximal caries was evaluated by three observers according to a five-point confidence scale. The actual status of each surface of the teeth was histologically determined from the teeth sections. Sensitivity, specificity, positive and negative predictive values, and likelihood ratios of the imaging modalities were calculated, and observer responses were assessed with Kendall's tau and Spearman's rho tests. RESULT: The sensitivity values for Ultraspeed, Ektaspeed Plus, Insight, and radiovisiography were 0.39, 0.48, 0.45, and 0.49, respectively, while the specificity values were 0.91, 0.88, 0.84, and 0.90, respectively. The difference in detecting approximal carious lesions between the systems was not statistically significant. CONCLUSION: This study suggests that there is no significant difference between the four imaging modalities in detecting approximal carious lesions.

Lateral perforation in parallel post space preparations.

This study evaluates the amount of remaining tooth structure and possibility of producing lateral perforation following the use of different diameters of parallel-sided Parapost drills in groups of different canal curvatures (0 degrees-15 degrees, 16 degrees-25 degrees, 26 degrees <) in distal canals of first and second mandibular molar teeth. After enlargement of root canals using the crown-down pressureless technique, Parapost drills #1, #2, and #3 were used in the different canal groups for the preparation of a post space. Standardized digital radiographs were taken before the post space preparation and after each Parapost drill application. Four horizontal lines (a, b, c, and d) were drawn at equal distances on these images, starting from the pulp chamber floor moving apically at 2 mm increments. There were no significant differences between the different curvature groups at the a, b, c, and d levels for the critical level of the remaining tooth structure (multiple comparison test; p>0.05). However, in considering root perforation, both at the inner and outer side of the roots, there were statistically significant differences at "c" and "d" levels in group 3 (#3 drill) without taking into account the root curvature (ANOVA; p< 0.5). None of the specimens showed strip perforation.