Özgür Topuz

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.

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.

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.

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. Microsc. Res. Tech.

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

Abstract 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.

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.