Özgür Irmak

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.

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.

Marginal integrity of self-adhering flowable composites used as liner under class II restorations: a comparative in vitro micro-CT study

Abstract This in vitro study aimed to evaluate the internal adaptation of two different self-adhering flowable composite resin materials used as liners under Class II restorations using microcomputed tomography (micro-CT) analysis. Standard box-only cavities were prepared in 30 extracted human third molar teeth. The cervical floor of the proximal box was 1 mm below the cementoenamel junction. After the preparations were completed, the teeth were randomly and equally divided into three groups based on the type of liner used: group 1, universal flowable composite (control; CO); group 2, self-adhering flowable composite (Fusio Liquid Dentin; FU); and group 3, self-adhering flowable composite (Vertise Flow; VE). After lining, the cavities were restored using 2-mm increments of the nanohybrid composite. After storing the specimens for 24 h in distilled water at 37 °C, all teeth were subjected to 5000 thermal cycles of 5/55 °C. Subsequently, the teeth were immersed in a 50% silver nitrate dye at 23 °C for 4 h. Following the immersion, high-resolution micro-CT images were obtained. Silver nitrate penetration into the microgap between the tooth and restoration was calculated for each specimen as a percentage of the entire length of the pulpal floor using image analysis software. One-way analysis of variance was performed to compare the differences among the groups (p = 0.05). No significant differences were observed between the control and self-adhering composite groups (FU, VE; p > 0.05). The performance of self-adhering composites was similar to that of universal flowable composites in terms of marginal microleakage.

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.

Solvent type influences bond strength to air or blot-dried dentin.

BackgroundAir-drying of etched and rinsed dentin surface may force the exposed collagen fibrils to collapse. Blot-drying is an alternative method to wipe the excess water from the dentin surface without compromising the monomer penetration. Contemporary total etch adhesives contain ethanol/water or acetone as solvent in which resin monomers are dissolved. Solvent type of the adhesive system has an important role in bonding to dentin. An adhesive containing tertiary butanol as an alternative solvent has been in the market. Purpose of this study is to determine the shear bond strengths of three total-etch adhesives with different solvents (acetone, ethanol or tertiary butanol) applied to air or blot dried moist dentin.MethodsSixty extracted non-carious human third molars were divided into three main groups according to solvent content of the adhesives [acetone based - One Step (OS, Bisco, IL, USA); ethanol/water based - Optibond Solo Plus (OB, Kerr, CA, USA); and tertiary butanol based - XP Bond (XP, Caulk/Dentsply, DE, USA)]. Each main group was divided into two groups according to drying methods (blot or air) (n = 10). Shear bond strengths (SBS) were measured. Data were analyzed by Student’s t test and Tukey HSD test (p < 0,05).ResultsXP showed highest SBS values in both drying methods applied (p < 0.05). Drying method did not influence the SBS in OS and OB (p > 0.05). XP-blot produced significantly higher SBS than XP-air (p < 0.05).ConclusionsTertiary butanol based adhesive showed higher bond strength values than ethanol or acetone based adhesives. Blot drying of dentin improved the bond strength values of tertiary butanol based adhesive. Further research is necessary to determine in vivo and in vitro performance of tertiary butanol based adhesives.

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.

Laser type effects on repair bond strength of ormocers and nanoceramic based composites

Abstract The aim of this study was to evaluate the effects of different surface treatments and different restoration materials on repair bond strength of ormocer and nanoceramic based composites. 24 (12 Admira, Voco, 12 Ceram X duo, Dentsply) thermally aged blocks (6 × 6 × 5 mm) were roughened with either bur, Er:YAG or Nd:YAG laser. In each group half of the roughened samples were repaired with composite of their respective brand; other half was repaired with composite of the other brand. All samples were subjected to microtensile bond strength test. Data were analyzed with Kruskal-Wallis and Bonferroni correction, Mann-Whitney U test (p = 0.05). For roughening methods no significant difference was found between Bur-Er:YAG (p = 0.536), however between the other groups (Bur-Nd:YAG and Er:YAG-Nd:YAG) significant difference were found (p < 0.001). For Admira as a filler material, no significant differences were found for bur, Er:YAG, Nd:YAG groups based on repair materials. For Ceram X duo as a filler material, while no significant differences were found for bur and Er:YAG groups; a significant difference was found for Nd:YAG group based on repair materials. A weak significant difference was found between the repair composite groups undergone thermocycling or not (p = 0.04). Surface roughening with Er:YAG laser can be used clinically for the repair of aged composite restorations.

ADHESIVE SYSTEM AFFECTS REPAIR BOND STRENGTH OF RESIN COMPOSITE

Purpose: This study evaluated the effects of different adhesive systems on repair bond strength of aged resin composites. Materials and Methods: Ninety composite discs were built and half of them were subjected to thermal aging. Aged and non-aged specimens were repaired with resin composite using three different adhesive systems; a two-step self-etch adhesive, a two-step total-etch adhesive and a one-step self-etch adhesive; then they were subjected to shear forces. Data were analyzed statistically. Results: Adhesive type and aging significantly affected the repair bond strengths (p<0.0001). No statistical difference was found in aged composite groups repaired with two-step self- etch or two-step total-etch adhesive. One-step self-etch adhesive showed lower bond strength values in aged composite repair (p<0.0001). Conclusion: In the repair of aged resin composite, two-step self-etch and two-step total-etch adhesives exhibited higher shear bond strength values than that of one-step self-etch adhesive.

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.