Mehmet Baybora Kayahan

In vitro comparison of induction capacity and biomineralization ability of mineral trioxide aggregate and a bioceramic root canal sealer

AIM To compare the effect of mineral trioxide aggregate (MTA) and iRoot SP, a bioceramic root canal sealer, on the cell viability, hard tissue deposition capacity and odontogenic differentiation of human tooth germ stem cells (hTGSCs). METHODOLOGY The dental materials MTA, iRoot SP and Dycal were packed into Teflon rings and placed on transwell inserts for toxicity evaluations by the MTS assay on days 3 and 7. Dycal was used as a positive control for the cell viability assay. Teflon rings were cocultured with hTGSCs, followed by the induction of odontogenic differentiation. The odontogenic differentiation of hTGSCs and biomineralization ability of the materials were evaluated by analysing the mRNA expression levels of dentine sialophosphoprotein (DSPP) and collagen type 1A (COL1A) by real-time polymerase chain reaction expression analysis, measurement of alkaline phosphatase (ALP) activity and visualization of calcium deposits by von Kossa staining. RESULTS MTA and iRoot SP exhibited no cytotoxicity, but Dycal caused cytotoxicity (P < 0.05) of almost all of the cells after 7 days. MTA significantly stimulated (P < 0.05) the odontogenic differentiation of hTGSCs compared with iRoot SP. MTA and iRoot SP increased (P < 0.05) the mRNA levels of COL1A and DSPP mRNA compared with noninduced hTGSCs, which served as a negative control (NC). iRoot SP, however, significantly decreased (P < 0.05) COL1A and DSPP mRNA expression levels compared with the PC. CONCLUSION MTA and iRoot SP induced hTGSC differentiation into odontoblast-like cells, but MTA might provide more inductive potential and hard tissue deposition compared with iRoot SP.

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.

Comparison of the force required to fracture roots vertically after ultrasonic and Masserann removal of broken instruments

AIM To evaluate the force required to fracture roots vertically after the removal of broken instruments using ultrasonic tips and a Masserann kit. METHODOLOGY Thirty-nine extracted human anterior teeth with single and straight roots were used. The crown of each tooth was removed until the full length of the tooth was 13 mm. All canals were instrumented with the step-back technique to a size 25 K-file. The teeth were randomly divided into three groups: two experimental groups and a control group. The size 30 K-files used for the test were notched to a depth of half of the instrument with a No. 2 round bur at a point 3 mm from the tip to facilitate breakage of the file at this point. The fractured instruments were removed from the canals using ultrasonic tips or a Masserann kit. The samples were subjected to a continual vertical loading, using a universal testing machine. For each root, the force at the time of fracture was recorded in Newtons. The results were analysed statistically using one-way anova and Tukey HSD test. RESULTS The force required to fracture the roots vertically was significantly higher in the control group than the experimental groups (P < 0.01). The roots from which the broken instruments had been removed using ultrasonic tips required more force to fracture than roots in the Masserann group; however, the difference was not statistically significant. CONCLUSION Removal of a fractured instrument from the middle third of the root decreased the force required to fracture the root vertically, regardless of the technique used for instrument removal. There was not difference between the ultrasonic technique and the Masserann technique.

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.

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.

In Vitro Comparison of Fracture Strength of Experimental Hollow and Solid Design Zirconia Dowels

PURPOSE The aim of this study was to evaluate the fracture strength of experimental hollow and solid design zirconia dowels. MATERIALS AND METHODS Three types of dowels (fiber-reinforced composite [FRC], hollow design, and solid design zirconia dowels) were tested in the study (n = 10). A three-point bending method was conducted, and a load was applied until fracture. The values were recorded as Newtons (N) and then converted to megapascals (MPa) according to the diameter of the dowels. Statistical analyses were performed using one-way ANOVA and Tukey HSD tests. The significance was set at p < 0.05. RESULTS The mean fracture strength of the hollow design zirconia dowels was significantly higher (960.72 MPa) than solid zirconia dowels (741.78 MPa) and FRC dowels (687.64 MPa) (p < 0.05). CONCLUSIONS The hollow design zirconia dowel seems to have sufficient fracture strength for anterior restorations. This design may be beneficial to access the apical region when retreatment is necessary, without any dowel-removing procedure.

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.

Efficacy of ethylenediamine tetraacetic acid and calcium hydroxide in the removal of root canal filling during retreatment

Objective: To compare the effect of Ethylenediamine tetraacetic acid (EDTA) and calcium hydroxide [Ca(OH)2] in the removal of root canal filling material during retreatment procedure. Methodology: Eighty extracted, single-rooted human teeth were used. Root canals were shaped with a crown-down technique using Ni-Ti rotary instruments (ProTaper, Dentsply Maillefer, Switzerland) and filled with a cold lateral condensation method. AH Plus was used as a sealer. After filling, the teeth were divided into 4 groups and root fillings were removed by ProTaper Universal rotary retreatment system. In each group different irrigation and disinfection protocols were followed; Group I. Sodium hypochlorite (5.25%) + EDTA (17%1 min.) Group II. Sodium hypochlorite (5.25%) Group III. Sodium hypochlorite (5.25%) + Ca (OH)2 Group IV. Sodium hypochlorite (5.25%) + Ca(OH)2 + EDTA (17%-1 min.). Irrigation with 17% EDTA was performed only before D3-Retreatment instrumentation in all groups. AutoCAD system was used to detect the amount of residual root canal filling material. The results were statistically analyzed by SPSS (Statistical Package for Social Sciences) for Windows 15.0, one way ANOVA and Tukey’s HSD tests. The significance was evaluated at the level of p<0.05. Results: The amount of the remnant filling material in the root canals retreated in Group I was less than the amount of the material in Group II (p<0.01) and Group III (p<0.05). There was no significant difference observed between the other groups in terms of the quantity of the remnant root canal filling materials (p>0.05). Conclusions: Irrigating the canals with EDTA enhanced the removal of root canal filling during retreatment. However, disinfecting the canals with Ca(OH)2 had no effect in the removal of filling material.

Prosthodontic Management of a Patient with Oligodontia: A Case Report

Abstract Oligodontia or severe hypodontia is a rare developmental dental anomaly which is described as congenital absence of 6 or more teeth excluding the third molars. In this case report, the treatment of a 31-yearold woman with congenital absence of 9 permanent teeth is described. The treatment with occlusal appliance and fixed a partial dentures ended up in functional and aesthetic results.

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

Abstract 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.