Evaluation of treatment and restoration preferences in deep carious teeth with various pulp exposure sizes: A questionnaire-based survey.

This study evaluated the management preferences in a deep carious vital tooth. A questionnaire was e-mailed to members of the Turkish Dental Association. The questionnaire included a photograph and radiographs of an extremely deep carious molar (#16) of a 30-year-old man suffering from cold and chewing sensitivity. The dentists were asked to choose treatments for pulp exposure of <1, 1-2, and ≥2 mm and a permanent restoration. Chi-squared test was used to analyse data (p < 0.05). 504 (4.84%) of 10 411 dentists responded. When the pulp exposure was <1 mm: direct pulp capping (84.9%); 1-2 mm: root canal treatment (49.6%); ≥2 mm: root canal treatment (85.7%) were the most preferred treatments. 69.6% of the respondents chose direct composite restorations. If the tooth would be an abutment, most respondents preferred root canal treatment, regardless of the perforation size. The extent of pulp exposure and the type of permanent restoration influenced the treatment decision-making process.

Irrigant flow characteristics in the root canal with internal root resorption: a computational fluid dynamics evaluation.

Irrigation dynamics of syringe irrigation with different needle designs (side-vented, double side-vented, notched) and ultrasonic irrigation in the root canal with internal root resorption were evaluated using a computational fluid dynamics model. A micro-CT scanned mandibular premolar was used for modeling internal root resorption. The needles and the ultrasonic tip were positioned at 2, 4, and 5 mm from the working length. The insertion depth and the irrigation model were found influential on the shear stress and the irrigant extension. The extension of the irrigant increased toward 2-5 mm from the working length. Ultrasonic irrigation revealed the highest shear stress values regardless of the insertion depth. The shear stress distribution on the resorption cavity walls gradually increased when the needles were positioned coronally. The residence time of the irrigant in the canal was affected by the needle position relative to the internal root resorption cavity and the needle type.

Effect of Shaft Length on the Torsional Resistance of Rotary Nickel-titanium Instruments.

INTRODUCTION: This study was conducted to evaluate the effect of file length on the torsional resistance of nickel-titanium rotary files. METHODS: Forty-five new files with a #25 tip size and variable taper for ProTaper Next (PTN; Dentsply Sirona, York PA), ProTaper Gold (PTG, Dentsply Sirona), and HyFlex CM (HCM; Coltene-Whaledent, Allstetten, Switzerland) were divided into 3 subgroups (n = 15) according to the file length (21, 25, and 31 mm). Torsional tests were performed using a custom-made device (AEndoS; DMJ System, Busan, Korea). The maximum torsional load and distortion angle were measured until file fracture occurred. The toughness was calculated using these data. All data were statistically analyzed using 2-way analysis of variance at a confidence level of 95%. One-way analysis of variance and Duncan post hoc comparison were also conducted to assess the difference among the independent variables, shaft length, and file system. RESULTS: A statistically significant interaction was observed between the file system and instrument length with respect to the maximum torsional load (P < .05). The 31-mm shaft length of HCM showed higher maximum torsional load than that of the 25- and 21-mm shaft length in the HCM groups (P < .05). Among the instrument systems, PTG showed the significantly highest maximum torsional load followed by PTN and HCM (P < .05). The 31-mm shaft length of PTG showed significantly higher toughness than that of the 21- and 25-mm shaft lengths (P < .05), whereas PTN and HCM did not show any difference in relation to the shaft length. CONCLUSIONS: Within the limitations of this study, the instrument with a longer shaft may have higher maximum torsional load or toughness than that with a shorter shaft.

Effective Establishment of Glide-Path to Reduce Torsional Stress during Nickel-Titanium Rotary Instrumentation.

This study compared the torque generation during canal shaping with a nickel-titanium endodontic instrument according to the extent of glide-path establishment. Seventy-five simulated S-shaped canal blocks were divided into five groups (n = 15) according to the number of repetitive insertions to the working length using a One G glide-path instrument: groups with 5, 10, 15, and 20 insertions as well as group Z without glide-path establishment. When the tip of the One G file reached the working length, the file was moved back and forth repetitively at the working length for the designated number of times for each group. The instrumentation procedure with HyFlex EDM had 15 pecking strokes. During instrumentation, the generated torque was transmitted to a customized data acquisition module and collected using customized software. Data were computed to determine the maximum torque and total stress. The maximum screw-in forces were statistically analyzed using one-way analysis of variance and Tukey's post hoc comparison test with a significance level of 95%. While the maximum stress did not have significant differences among the five groups (p > 0.05), groups with more than 10 repetitive insertions generated lower total stress during instrumentation than did the group with 5 insertions and group Z (p < 0.05). Under the limitations of this study, repetitive insertions of glide-path establishment files at the working length reduced stress generation during the shaping using nickel-titanium instruments.

Influence of Post Space Preparation on the Apical Leakage of Calamus, Single-Cone and Cold Lateral Condensation Obturation Techniques: A Computerized Fluid Filtration Study.

PURPOSE: Apical microleakage between the root canal and periapical tissues is considered a common cause of endodontic failure. The aim of this study was to evaluate the apical microleakage of various obturation techniques after immediate post space preparations with different drills. MATERIALS AND METHODS: One hundred twenty human single-rooted teeth were selected for this study. The coronal portions were removed to achieve a uniform length of 15 mm. All root canals were instrumented with ProTaper Next rotary files using crown-down technique. The 120 roots were randomly assigned to 3 experimental groups according to obturation technique (n = 40). The root canals were obturated with lateral condensation in group 1, single-cone technique in group 2, and Calamus 3D obturation system in group 3. Each group was divided into two subgroups (n = 20) according to drill types (Gates Glidden and Peeso drills) leaving 5 mm of apical gutta-percha. The apical microleakage was measured using the computerized fluid filtration meter method. The results were evaluated using Kruskal-Wallis test with Bonferroni Corrected Mann-Whitney U multiple comparison post hoc tests. RESULTS: There was no statistically significant difference between obturation techniques after post space preparation with Peeso drills (p > 0.05). In Gates Glidden drill groups, single-cone technique demonstrated higher leakage (0.0051 ± 0.0037 µl x min-1 × cmH2 O-1 ) than Calamus techniques (0.0019 ± 0.0012 µl x min-1 × cmH2 O-1 ) (p < 0.017). CONCLUSIONS: Gates Glidden drills caused the highest apical leakage in teeth obturated with single-cone technique.

3D FEA of Hollow and Solid Design Zirconia Dental Dowels.

PURPOSE: The aim of this study was to evaluate the stress distribution of hollow and solid design zirconia dowels. MATERIALS AND METHODS: Finite element analysis (FEA) was used to investigate the influence of different dowel designs on the stress distribution of zirconia dowels. The coronal diameter of the dowel was 2.2 mm, the apical diameter was 1.8 mm, and the length was 15 mm. The diameter of the hollow space was 1.2 mm. Occlusal forces (both parallel and oblique) of 100 N were applied from the wider edge of the dowels simulating loads acting on the incisor during clenching and incising. The results were expressed in terms of von Mises criteria. RESULTS: FEA revealed differences in stress distribution. During parallel load, the maximum tensile stress of the hollow design (89.40 MPa) was greater than the solid design (43.30 MPa). During oblique load, the maximum tensile stress of the hollow design (1437.90 MPa) was greater than the solid design (917.96 MPa). The maximum deformation was observed in the coronal part of the dowel in both designs under the two load directions. CONCLUSIONS: FEA results showed that the hollow design zirconia dowels presented higher tensile stress.

Evaluation of senior dental students' general attitude towards the use of rubber dam: a survey among two dental schools.

The purpose of this study was to evaluate the general attitude of senior dental students towards rubber dam use, specifically focusing on endodontic practices prior to starting to serve community. Questionnaires were distributed to senior year students of a private school and a state school in Istanbul. Questions were asked about areas where the students used rubber dam, its advantages and difficulties, and whether they agreed or disagreed with some aspects of the rubber dam. The private school students rated isolation whereas those of the state school selected prevention of aspiration which the top advantage rubber dam provides. Students of the state school agreed with the opinion that isolation cannot be achieved without rubber dam and it extended the procedure with a significantly higher ratio compared to the private school. Within the limitations of the present study, it can be concluded that the perceptions of dental students on rubber dam needs to be improved and strategies should be developed so that this valuable adjunct will comprise one of the indispensable elements of dental care.

Comparision of two different preparation protocol of Ni-Ti Rotary PathFile-ProTaper instruments in simulated s-shaped canals.

INTRODUCTION: The aim of this study is to compare the root canal transportation with the PathFile-ProTaper recommended protocol, PathFile-ProTaper modified protocol and stainless steel K-flexofiles. METHODS: Forty-five ISO 15, 0.02 taper S-shaped Endo Training Blocks were divided randomly into three groups of 15 each and prepared as follows: PathFile-Protaper recommended protocol, Pathfile-Protaper modified protocol and manual preparation with K-Flexofiles. The amount of transportation was assessed by scanning the blocks before and after preparation and superimposing the images. The cutting effects of the instruments from the inner and outer aspects of the root canals were measured and statistically analyzed with the One-way Anova test and Tukey HSD test. RESULTS: Manual preparation caused significantly more transportation than both PathFile-Protaper systems. There was no significant difference regarding transportation between the two Pathfile-Protaper protocols. CONCLUSION: The modified Pathfile-Protaper protocol transported the canal similar to the recommended Pathfile-Protaper protocol. It may be suggested that, while working safety remains unchanged, the shaping procedure and consequently working time can be shortened with fewer instruments. The results of this study can help clinicians to reduce the preparation time with the PathFile-ProTaper rotary system while the preparation quality remains the same.

Treatment approaches and antibiotic use for emergency dental treatment in Turkey.

The purpose of this study was to gather information about Turkish general dental practitioners' treatment approaches towards endodontic emergencies, antibiotic-prescribing habits, and their participation in lifelong learning programs. Questionnaires were given to dentists who attended the 16th National Congress organized by the Turkish Dental Association. From 1,400 questionnaires distributed, 589 (43%) were deemed usable in this study. This survey dealt with questions that were subdivided into two main topics: dental emergency treatment approaches, and antibiotic prescription and information on lifelong learning program participation. The statistical analysis was conducted with a χ (2) test at a significance level of P<0.05. For irreversible pulpitis cases in vital teeth, most of the dental practitioners (65.3%) preferred single-visit root canal treatments. For teeth presenting a periapical lesion, the preferred treatment approach was root canal treatment (91.5%). The rate of prescription of analgesics and antibiotics was 21.7% in untreated acute apical periodontitis cases and 41% in acute apical abscess cases. Frequently prescribed antibiotics were amoxicillin-clavulanate (61.8%) and amoxicillin (46.5%). There was a tendency for practitioners to attend congresses as their years of professional practice increased (P<0.0001). There have been discrepancies between taught and observed practice. Educational initiatives are needed to prevent inappropriate prescription of antibiotics.

Comparison of the radiopacities of different root-end filling and repair materials.

This study evaluated the radiopacity of 3 repair materials, Biodentine, MM-MTA, and MTA Angelus. Standardized cylindrical rings were prepared. Samples of Biodentine MM-MTA and MTA Angelus were prepared (n = 10 in each group), filled into the rings, and preserved at 37°C until setting. A 1 mm thick dentin slice was used as control. All set specimens were removed and radiographed along with the dentine slice and a graduated aluminium step wedge. Digital images were transferred to the computer using a software. The radiographic densities of the specimens were determined, and the values were converted into millimetres of aluminium (mm Al). One-way ANOVA was used for intergroup comparison, whereas Tukey HSD test was used for detecting the group with the difference. The mean radiopacities of Biodentine, MTA Angelus, and MM-MTA were 2.8 ± 0.48, 4.72 ± 0.45, and 5.18 ± 0.51 mm Al, respectively. The radiopacity of Biodentine was significantly lower compared to other materials (P = 0.001), whereas no significant difference was noted between MTA Angelus and MM-MTA (P = 0.109). All materials had significantly higher radiopacities compared to dentine. The relatively lower radiopacity of Biodentine can be improved to achieve more reliable results in procedures such as retrograde fillings.

Effect of acid etching procedures on the compressive strength of 4 calcium silicate-based endodontic cements.

INTRODUCTION: The purpose of this study was to evaluate the effect of acid etching on the compressive strength of 4 calcium silicate-based cements. METHODS: One gram of each corresponding powder of ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN), MTA Angelus (Angelus, Londrina, PR, Brazil), and CEM cement (BioniqueDent, Tehran, Iran) and a 0.33-g aliquot of liquid were placed in a plastic mixing capsule that was then mechanically mixed for 30 seconds at 4500 rpm in an amalgamator. For the preparation of Biodentine (Septodont, Saint Maur-des-Fossés, France), the liquid provided was added to the powder within the plastic capsule supplied by the manufacturer and then mechanically mixed for 30 seconds at 4500 rpm using the amalgamator. The resulting slurries were then placed incrementally into 40 cylindrical molds to give a total of 160 specimens that were incubated at 37°C for a week. Twenty specimens of each material were then subjected to the acid etch procedure. The compressive strength of the samples was then calculated in megapascals using a universal testing machine. The results were then subjected to 2-way analysis of variance analysis of variance followed by the Tukey post hoc test. RESULTS: The application of acid etch significantly reduced (P < .0001) the compressive strength of Angelus MTA and CEM cement; however, it did not reduce the compressive strength of ProRoot MTA or Biodentine. Regardless of the acid etch application, Biodentine showed significantly higher compressive strength values than the other materials (P < .0001), whereas CEM cement had the lowest compressive strength values. There was no significant difference between CEM cement and MTA Angelus. The compressive strength of ProRoot MTA was significantly lower (P < .0001) than Biodentine but significantly higher (P < .0001) than MTA Angelus and CEM cement in both the test and control groups. CONCLUSIONS: When the application of acid etchants is required, Biodentine and ProRoot MTA seem to be better options than MTA Angelus or CEM cement.

Human tooth germ stem cell response to calcium-silicate based endodontic cements.

OBJECTIVE: The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs). MTA Fillapex, a mineral trioxide aggregate (MTA)-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer. MATERIAL AND METHODS: To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm) and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM) analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO2 for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium). The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods. RESULTS: On the 1st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC) group (p<0.008). No significant difference was observed between the other tested materials at this period (p>0.05). After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008). In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface. CONCLUSIONS: Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials have exerted cellular toxicity, iRoot SP and AH Plus Jet may promote better attachment to hTGSCs.

Human tooth germ stem cell response to calcium-silicate based endodontic cements

OBJECTIVE: The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs). MTA Fillapex, a mineral trioxide aggregate (MTA)-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer. MATERIAL AND METHODS: To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm) and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM) analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO2 for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium). The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods. RESULTS: On the 1st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC) group (p<0.008). No significant difference was observed between the other tested materials at this period (p>0.05). After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008). In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface. CONCLUSIONS: Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials ...

Potential of an Er:YAG laser in the removal of calcium hydroxide from root canals.

OBJECTIVE: The purpose of this study was to assess the calcium hydroxide (CH) removal potential of an Er:YAG laser in combination with ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) irrigation. BACKGROUND DATA: Removal of the CH dressing prior to the root canal filling is mandatory, as its remnants may mechanically block the apical area of the root canal system and also have an effect on the texture, viscosity, working time, penetration, and adhesion of root canal sealers. However, the removal of CH from the canal space is challenging, because it should ideally be placed deep and densely, so that its biological effects can be exerted in close proximity to the appropriate tissues. METHODS: In this study, the mandibular premolar teeth were embedded in acrylic blocks and sectioned longitudinally through the canal, forming two halves following shaping of the root canals with ProTaper (Maillefer, Ballaigues, Switzerland) rotary instruments. The teeth were reassembled after standard grooves created onto canal walls were filled with CH. In group 1, conventional irrigation was performed with 10 mL of 17% EDTA and 10 mL of 5% NaOCl, and in goup 2, Er:YAG laser following conventional irrigation was performed. Images of the grooves taken before and after irrigation were scored and the Mann-Whitney U test was used to statistically evaluate the results. RESULTS: The percentage of CH score reduction was 46.30% in group 1 and 60.58% in group 2. No significant difference was found between two groups (p>0.05). CONCLUSIONS: The laser did not improve the removal of CH during conventional root canal irrigation performed with NaOCl and EDTA under the conditions of current study.

The effect of the gap between the post restoration and the remaining root canal filling on the periradicular status in a Turkish subpopulation.

OBJECTIVE: The aim of this study was to evaluate whether the gap between the post restoration and the remaining root canal filling had an impact on the periapical health of endodontically treated teeth in a Turkish subpopulation. STUDY DESIGN: Digital panoramic radiographs, evaluated for this cross-sectional study, were randomly selected from files of patients who attended to Yeditepe University, Faculty of Dentistry, between June 2007 and December 2008. The total number of teeth with endodontic posts and crowns was 407. Two observers assessed the radiographs and evaluated the quality of root canal filling and the gap between the root canal filling and the post restoration. Periapical status of the teeth was assessed by the Periapical Index (PAI) scores. Only the teeth with a minimum of 5 mm apical root canal filling that was classified as "good endodontic treatment" were included in the study. Teeth that had no root canal filling, poor endodontic treatment, or less than 5 mm remaining root canal filling beyond post restoration were not assessed. Chi-square test was used for statistical analysis and significance level was established at 5%. RESULTS: In cases with good endodontic treatment, there were 207 teeth that had no gap between the remaining root canal filling and the post restoration. In this group, 135 (65%) teeth had healthy periapex and 72 (35%) teeth showed signs of apical periodontitis. There were 81 teeth that had a gap between the remaining root canal filling and the post restoration. Of these teeth, 69 (85%) had periapical pathosis; however, only 12 (15%) teeth had healthy periapex. CONCLUSION: Statistical analysis revealed that the success rate of good endodontic treatment was significantly affected by the gap between the post restoration and remaining root canal filling (P < .001).

Periapical health related to the type of coronal restorations and quality of root canal fillings in a Turkish subpopulation.

OBJECTIVE: The purpose of this study was to evaluate the relationship between the quality of root canal fillings and type of permanent coronal restorations and their association with the periapical status in a Turkish subpopulation. STUDY DESIGN: There were 1268 endodontically treated teeth from 280 panoramic radiographs that were evaluated. Two observers assessed the radiographs using an x-ray viewer with 2 times magnification. Teeth were classified according to the type of restorations. The quality of root canal fillings were evaluated according to the criteria determined by Tronstad et al. Apical status was assessed by the Periapical Index scores (PAI) proposed by Ørstavik et al. Chi-square test was used for statistical analysis. RESULTS: There were 59.5% of endodontically treated teeth that showed healthy periapex. Teeth with good endodontic treatment showed statistically significant high healthy periapex rates regardless of the type of the restoration. In addition, the evaluation of the entire material also showed that the roots with posts had significantly more periapical pathosis than roots without posts (P = .001). CONCLUSIONS: It can be concluded that, although the quality of the root canal filling plays a key role in the outcome of endodontic therapy, the type of restoration can also be a contributing factor in the treatment outcome.