Ekim Onur Orhan

Comparative investigation of 2 rotary nickel-titanium instruments: protaper universal versus protaper

OBJECTIVE The objective of this study was to evaluate whether the changes in the design of the ProTaper canal instruments contribute to the shaping ability of the instrument in terms of the morphology of curved canals measured by the cross-sectional area using the Bramante method. STUDY DESIGN Ten extracted human mandibular molars with root canal curvatures between 25 degrees and 41 degrees were used. Ten mesiobuccal canals were instrumented with ProTaper and 10 mesiolingual canals were instrumented with ProTaper Universal rotary instruments. Pre- and postoperative sections were obtained from the coronal, middle, and apical portions and analyzed. Statistical analysis was performed using the Student t test (P < .05). RESULTS No statistically significant difference was observed in terms of amount of dentin removed, transportation, variation of canal shape factor or change in working length, and working time (P > .05). Only one instrument fracture (F2 in the ProTaper group) and 2 instrument deformations (S1 and F3 in ProTaper and ProTaper Universal, respectively) were noted. CONCLUSION Within the limitations of this study, the modifications on ProTaper instruments were found to not create any discrepancy on the shaping abilities of instruments and the evaluated other factors. In addition, both rotary nickel-titanium instruments prepared a well-shaped root canal with minimal canal transportation.

Odontoblast‐like cell numbers and reparative dentine thickness after direct pulp capping with platelet‐rich plasma and enamel matrix derivative: a histomorphometric evaluation

AIM To collect quantitative information about the numbers of odontoblast-like cells and reparative dentine thickness after direct pulp capping with platelet-rich plasma (PRP) and enamel matrix derivative (EMD). METHODOLOGY The experiment was conducted on 36 Wistar albino rats and a total of 144 incisor teeth. Calcium hydroxide, mineral trioxide aggregate, PRP and EMD were applied as direct capping agents on the pulps of 96 incisors (n = 24). Positive and negative control groups were created on the remaining 48 incisors. The teeth were extracted on the 7th and 28th days. After routine histological preparation, cross-sections were stained with haematoxylin and eosin. The numbers of the odontoblast-like cells were measured histomorphometrically on day 7 and day 28. The thickness of the reparative dentine was also measured. The number of odontoblast-like cells was also measured beneath the dentine bridge. The normal distribution of all data was tested with the Mann-Whitney U test. The statistical differences between groups were analysed using the Kruskal-Wallis test. RESULTS The mean number of odontoblast-like cells increased between day 7 and 28 following pulp exposure (P > 0.01) in all groups except for the EMD group (P < 0.01), when compared with both the experimental and negative control groups (P < 0.01). Reparative dentine formation was observed in all groups of teeth (P > 0.01). CONCLUSIONS Reparative dentine formation was observed, but with no significant difference between the groups. Odontoblast-like cells were observed in association with the outcome of pulps capped with PRP and EMD. PRP and EMD are possible capping agents that influence the thickness of reparative dentine formation.

Does Para-chloroaniline Really Form after Mixing Sodium Hypochlorite and Chlorhexidine?

INTRODUCTION Mixing sodium hypochlorite (NaOCl) with chlorhexidine (CHX) forms a brown-colored precipitate. Previous studies are not in agreement whether this precipitate contains para-chloroaniline (PCA). Tests used for analysis may demonstrate different outcomes. Purpose of this study was to determine whether PCA is formed through the reaction of mixing NaOCl and CHX by using high performance liquid chromatography, proton nuclear magnetic resonance spectroscopy, gas chromatography, thin layer chromatography, infrared spectroscopy, and gas chromatography/mass spectrometry. METHODS To obtain a brown precipitate, 4.99% NaOCl was mixed with 2.0% CHX. This brown precipitate was analyzed and compared with signals obtained from commercially available 4.99% NaOCl, 2% solutions, and 98% PCA in powder form. RESULTS Chromatographic and spectroscopic analyses showed that brown precipitate does not contain free PCA. CONCLUSIONS This study will be a cutoff proof for the argument on PCA formation from reaction of CHX and NaOCl.

Rapid tissue dissolution efficiency of electrically-activated sodium hypochlorite on bovine muscle

Objective: Sodium hypochlorite (NaOCl) is a common antimicrobial and tissue-dissolving irrigant. The aim of this in vitro study is to evaluate and compare dissolution capacities of sodium hypochlorite solutions after electrically activation (E-NaOCl) on bovine muscle specimens at various time periods and concentrations. Materials and Methods: Three sodium hypochlorite solutions of 1.25%, 2.5%, and 5% were tested at 3-min. and 5-min. with and without activation by electrically. Distilled water and NaOCl solutions without electrically activation were used as controls. Pieces of bovine muscle tissue (34 ± 2 mg) were placed in 10 mL of each solution at room temperature. In the group of E-NaOCl, electrically activation was performed through the potentiostat. The tissue specimens were weighed before and after treatment, and the percentage of weight loss was calculated. Results: Weight loss of the tissue increased with the concentration of E-NaOCl and NaOCl. Higher concentration and electrically activation considerably enhanced the efficacy of sodium hypochlorite. The effect of electrically activation on tissue dissolution was much greater than that of same concentrations in the groups of NaOCl (P < 0.001). Tissue weight loss was significantly higher in 2.5% and 5% E-NaOCl at 3 min. than in 2.5% and 5% NaOCl at 5 min. (P < 0.05). There were not any significant differences between the 2.5% E-NaOCl and 5% NaOCl at 5 min. (P > 0.05). Conclusion: Electrically activation can improve the tissue-dissolving effectiveness of sodium hypochlorite.

Kinematic analysis of new and used reciprocating endodontic motors in 2 different modes

Purpose: The actual reciprocating angles of endodontic motors might differ from the manufacturers’ set values. This study analyzed the effect of clinical usage on the kinematics of reciprocating endodontic motors with 2 different reciprocal modes. Methods: 1 new and 3 used reciprocating endodontic motors (X-Smart Plus, Dentsply Maillefer) with 2 different reciprocating modes, WaveOne mode (W-mode) or Reciproc mode (R-mode), were analyzed. An angle measurement disc was inserted into a contra-angle. Reciprocating motions were recorded with a high-speed camera at 1,200 fps and analyzed on a computer. The following kinematic parameters were calculated: duration of each reciprocating motion, engaging and disengaging angles, cycle rotational speeds, engaging and disengaging rotational speeds, net cycle angle, total cycle angle, and number of cycles to complete full rotation. One-way ANOVA and Kruskal-Wallis test followed by multiple comparison tests were used for statistical analysis (p = 0.05). Results: In W-mode, the actual engaging angles of all used and new motors were different from the manufacturer’s set values (p<0.0001), whereas there was no difference between actual engaging angles among the motors (p>0.05). In R-mode, the actual engaging angles of all used and new motors were similar to the manufacturers’ set values (p>0.05). There was no difference between the actual engaging angles among motors (p>0.05). Both the W-mode and R-mode showed statistically different values of actual disengaging angles for all used and new motors when compared with the manufacturers’ set value (p<0.0001). Conclusions: This study confirmed that the actual kinematics of reciprocating endodontic motors differ from the manufacturers’ set values. Some kinematic parameters were influenced by the clinical usage of the motors.

Endodontic Outcomes in Mandibular Second Premolars with Complex Apical Branching

Introduction: Mandibular premolars that have rare and complex anatomies may have the highest failure rate in nonsurgical endodontic treatment. Awareness of rare and complex anatomies of mandibular second premolars would aid in better outcomes of the treatment. This study aimed to evaluate the success of nonsurgical root canal treatment of mandibular second premolar teeth with complex apical branching. Methods: Twenty‐six mandibular second premolar teeth with complex apical branching treated with multiple‐visit nonsurgical root canal treatment or nonsurgical retreatment were retrospectively evaluated. Results: For the clinical outcomes, 9 subjects had complete healing, 1 subject had functional healing, and no subject had no healing scores out of 10 root canal treatment subjects. Six subjects had complete healing, 8 subjects had functional healing, and 2 subjects had no healing scores out of 16 retreatment subjects. For the radiographic outcomes, 7 subjects had complete healing, 3 subjects had incomplete healing, and no subject had no healing scores out of 10 root canal treatment subjects. Six subjects had complete healing, 8 subjects had incomplete healing, and 2 subjects had no healing scores out of 16 retreatment subjects. The clinical outcome of root canal treatment subjects was significantly different than retreatment subjects (P < .05). Similarly, the radiographic outcome of root canal treatment subjects was also significantly different than retreatment cases (P < .05). Conclusions: The outcome of endodontic treatment of mandibular second premolars may be influenced by treatment type.

Effect of rubbing force magnitude on bond strength of universal adhesives applied in self-etch mode

This study investigated the effect of rubbing force magnitude on dentin bond strengths of multi-mode adhesives applied in self-etch mode. Seventy-two extracted human molar teeth were used. Two different universal adhesives Single Bond Universal (SB) and Clearfil Universal (CL) were applied onto dentin surfaces in three different modes: without rubbing (NR), rubbing with 40 gf (gram-force) (40) or 80 gf (80) load. Teeth were restored with a resin composite. Half of the specimens were subject to thermal aging (10,000 cycles). Microtensile bond strength was measured and data were statistically analyzed with two-way analysis of variance and Tukeys test (α=0.05). Baseline bond strength values for CL adhesive were improved by rubbing (40 and 80 gf) as compared to no rubbing (p<0.05). Rubbing did not significantly improve bond strength values for SB, regardless of aging (p>0.05). Rubbing improves bonding performance of some universal adhesives to dentin when applied in self-etch mode.

Nuclear magnetic resonance spectroscopy and infrared spectroscopy analysis of precipitate formed after mixing sodium hypochlorite and QMix 2in1

Background Mixing sodium hypochlorite (NaOCl) with chlorhexidine (CHX) forms a brown precipitate. QMix-2in1 (QMix) was introduced as a final irrigant. Manufacturer recommends interim flushing with saline between the application of NaOCl and QMix to prevent formation of precipitation. This study assessed whether para-chloroaniline (PCA) is formed after mixing NaOCl with QMix. Methods Commercially available, 5.25% NaOCl solution, 2% CHX, QMix, 15% ethylenediaminetetraacetic acid (EDTA) and 98% PCA in powder form were used. Groups were prepared at room temperature. Group 1, 98% PCA in powder form; Group 2, 2% chlorhexidine (CHX); Group 3, QMix; Group 4, 5.25% sodium hypochlorite (NaOCl) mixed with QMix; Group 5, 5.25% NaOCl mixed with CHX; Group 6, 15% EDTA mixed with CHX. The precipitates were extracted and analysed with Proton Nuclear Magnetic Resonance (1H-NMR) and Infrared (IR) Spectroscopy, using PCA as an internal standard. Results No PCA was found in any of the irrigant-mixture groups tested. Conclusions This study used the interpretation of spectral results for the amino signals of precipitate formed after mixing QMix with 5.25% NaOCl using different nondestructive analysis methods, with PCA as an internal standard (control). We conclude that mixing QMix or 2%CHX with 5.25% NaOCl does not yield free PCA.

Enhancing antibacterial effect of sodium hypochlorite by low electric current-assisted sonic agitation

Background This research focused on the effects of low electric current (μE)-assisted sonic agitation of sodium hypochlorite on Enterococcus faecalis infected human root dentin. Methods Extracted human canine roots were instrumented, sterilized, and experimentally contaminated with E. faecalis. After incubation for 21 days, the presence of the biofilm was confirmed by scanning electron microscopy (n = 3). Roots were randomly divided into seven groups according to decontamination procedures: G1: no treatment; G2: sterile saline; G3: 5.25% sodium hypochlorite; G4: passive ultrasonic irrigation; G5: EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK) agitation (EA); G6: μE agitation; and G7: μE-assisted sonic agitation. Fixed μE amperage and intensities were applied in G6 and G7. Following microbial sampling, bacterial colonies were counted using the direct plating method. Results Biofilm was not eradicated in any sample. The μE-assisted sonic agitation of sodium hypochlorite revealed the lowest cfu values (p<0.05), whereas there were no significant differences among the passive ultrasonic irrigation, EndoActivator and μE agitation alone (p>0.05). Conclusions Based on available evidence, the following conclusions were drawn: The μE-assisted sonic agitation increased the antibiofilm efficiency of sodium hypochlorite than passive ultrasonic irrigation and EndoActivator. The μE-assisted sonic agitation on 5.25% sodium hypochlorite is not capable to eradicate biofilms at 10mA energy level in 60s.

The effect of canal cleansing protocols on cementation of a fiber post to saliva-contaminated root canals

Abstract Objective: This study investigated the effect of saliva contamination and cleansing effect of a self-etching primer (SEP), phosphoric acid (PA), chlorhexidine (CHX), and ethanol (EtOH) on the microtensile bond strength (μTBS) of a fiber post cemented with a self-adhesive resin cement (SAC) to root canal dentin. Material and methods: Sixty human lower premolar roots were randomly divided into 10 groups: (1) no saliva contamination, no cleansing (Control); (2) no saliva contamination, cleansing with SEP (NC-SEP); (3) no saliva contamination, cleansing with PA (NC-PA); (4) no saliva contamination, cleansing with CHX (NC-CHX); (5) no saliva contamination, cleansing with EtOH (NC-EtOH); (6) with saliva contamination, no cleansing (SC-NC); (7) with saliva contamination, cleansing with SEP (SC-SEP); (8) with saliva contamination, cleansing with PA (SC-PA); (9) with saliva contamination, cleansing with CHX (SC-CHX); (10) with saliva contamination, cleansing with EtOH (SC-EtOH). After cementation of posts, the roots were transversally sectioned to obtain six slices (n = 36) followed by μTBS test. Data were analyzed with ANOVA and Tukey HSD tests (p = 0.05). Results: Saliva contamination and cleansing methods had a significant effect on μTBS values (p < 0.0001). All cleansing agents improved bond strengths when compared with Control and SC-NC. Cleansing with CHX and ethanol showed lower μTBS values than phosphoric acid and SEP, regardless of saliva contamination (p < 0.05). Conclusions: Saliva contamination negatively affected bonding performance of SAC to root dentin. However; SEP, PA, CHX and EtOH can be used on contaminated dentin surfaces to optimize bonding performance of self-adhesive cements.