Hakan Arslan

Comparison of Cyclic Fatigue Resistance of Nickel-Titanium Coronal Flaring Instruments

INTRODUCTION The purpose of this study was to compare the cyclic fatigue resistance of coronal flaring instruments. METHODS Three groups of nickel-titanium (NiTi) endodontic coronal flaring instruments were tested in steel canals with a 3-mm curvature radius and 60° (n = 18) and 45° of curvature (n = 18). The cyclic fatigue of the following NiTi instruments was tested: ProTaper Sx (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex 25.08 (Coltene-Whaledent, Allstetten, Switzerland), and Revo-S SC1 (Micro-Mega, Besancon, France). The length and diameter of the fractured fragment and the total area of the fractured surface of each instrument were measured. The data were then statistically analyzed using a 1-way analysis of variance and the post hoc Tukey test (α = .05). RESULTS At the 60° of curvature, Revo-S had the highest fatigue resistance, HyFlex had the second highest fatigue resistance, and ProTaper Universal had the least fatigue resistance. At the 45° of curvature, the Revo-S and HyFlex showed superior cyclic fatigue resistance compared with the ProTaper. The length of the fracture fragment of the ProTaper instrument was longer than that of the other groups at the 60° of curvature. At the 45° of curvature, the length of the fracture fragment of the ProTaper and HyFlex instruments was longer than that of Revo-S. The mean diameter and surface area of the HyFlex instruments in the fractured part was higher than that of other groups at both angles of curvature. CONCLUSIONS The Revo-S SC1 and HyFlex 25.08 instruments showed better cyclic fatigue resistance than the ProTaper Sx instrument.

In Vitro Fracture Resistance of Endodontically Treated Roots Filled with a Bonded Filling Material or Different Types of Posts

AIM This study aimed to compare the fracture resistance of roots filled with a bonded material, fiber posts, or titanium post systems. METHODS Canals in the first group were filled with AH Plus and gutta-percha cones, and roots in the second group were filled with Epiphany sealer and Resilon cones. The root fillings (60 roots) were removed up to 4 mm from the canal apex to obtain 10-mm-deep post spaces, and posts were cemented. The groups were as follows: AH Plus control group, Epiphany control group, AH Plus fiber post group, AH Plus titanium post group, Epiphany fiber post group, and Epiphany titanium post group. Fracture tests were performed by using an Instron testing machine. The force was applied at a 45° axial angle with a constant speed of 1 mm/min. For each sample, the force at which fracture occurred was recorded in units of newtons. Statistical analysis was carried out by using analysis of variance test. RESULTS There was no statistically significant difference between all groups (P > .05). CONCLUSIONS Titanium posts, fiber posts, and Epiphany root canal filling systems were found to have no reinforcing effect on endodontically treated roots.

Comparison of single cone obturation performance of different novel nickel-titanium rotary systems

Abstract Objectives. The purpose of this study was to compare several different single-cone obturations in the gutta-percha-filled areas (PGFA), sealer-filled areas (PSFA) and voids, also determining the volumetric characteristics of the tested cones. Materials and methods. Curved mesial roots of 120 mandibular molars were instrumented using several different systems (ProTaper Next, Twisted File Adaptive, OneShape, ProTaper Universal, WaveOne and Reciproc) and filled with corresponding single cones. The teeth were then sectioned horizontally at 2, 4, 6 and 8 mm from the apex. The area values of each section were calculated and converted to percentages (PGFA, PSFA and voids) of the total area. To determine volumetric characteristics of the tested cones, 20 gutta-percha points of each tested group were scanned with CBCT using the same parameters. Results. The ProTaper Next and WaveOne groups presented the most PGFA and least PSFA. The Twisted File Adaptive group presented the least PGFA and most PSFA (p < 0.05) and the least gutta-percha volume. Conclusions. The Twisted File Adaptive system matched cones had the least volume and the least PGFA in severely curved mesiobuccal canals of mandibular first molars. Single matched cones volume varied.

Effect of citric acid irrigation on the fracture resistance of endodontically treated roots

Objective: The aim of this study was to evaluate the effect of citric acid irrigation on root fracture in different concentrations and at various time exposures on root fracture. Materials and Methods: Forty-eight human mandibular incisors with similar dimensions were selected. The specimens were decoronated, then divided into 6 groups as follows: A group without instrumentation and filling (G1) and the 5 other groups with canal preparation and irrigation of distilled water (G2), 10% citric acid for 1 min (G3), 50% citric acid for 1 min (G4), 10% citric acid for 10 min (G5), and 50% citric acid for 10 min (G6). In the experimental groups, the canals were obturated and subjected to the strength test. Statistical analysis was performed using Kruskal-Wallis test (P = 0.05). Results: G6 showed the highest fracture resistance (629.97 N), and G3 showed the lowest fracture resistance (507.76 N). However, there was no statistically significant difference among the groups. Conclusions: The results of this study suggest that use of citric acid is safe in terms of fracture resistance.

Effects of different irrigating solutions and disinfection methods on push-out bond strengths of fiber posts

Abstract Objective. The aim of this study was to evaluate the effects of various irrigating solutions and photoactivated disinfection (PAD) on the push-out bond strengths of fiber posts to root dentin. Materials and methods. Thirty-two human teeth were divided into eight groups, as follows: (1) irrigation with physiologic saline (control), (2) NaOCl irrigation, (3) chlorhexidine (CHX) irrigation, (4) ethanol (EtOH) irrigation, (5) NaOCl followed by 17% EDTA irrigation, (6) NaOCl-EDTA supplemented with CHX irrigation, (7) NaOCl-EDTA supplemented with EtOH irrigation and (8) NaOCl-EDTA irrigation supplemented with PAD. After the posts were cemented, the roots were transversally sectioned to obtain four slices (1 mm thick) (n = 16). Push-out tests were conducted by applying a load at 0.5 mm/min, types of fracture failures were recorded and data were analyzed with one-way ANOVA and Tukey post-hoc tests (p = 0.05). Results. Push-out bond strength was significantly affected by the type of irrigating solution and the disinfection protocol (p < 0.05). The bond strength of the EtOH, NaOCl and NaOCl-EDTA-CHX irrigated groups was significantly higher than that of the other groups. The highest bond strength was observed in the EtOH irrigated group and the lowest was the NaOCl-EDTA irrigated group. Conclusions. Irrigation with NaOCl and EDTA combined caused lower bond strength than observed in the control group. However, supplementing this combination with CHX improved the post-dentin bond strengths; supplementing with PAD did not.

Effects of physical and morphological properties of roots on fracture resistance.

Objective: The aim of this study was to determine how physical and morphological properties affect the fracture resistance of roots, and which criteria are important for root specimen standardization in fracture resistance studies. Materials and Methods: Seventy-five freshly extracted human canine teeth were selected. Crowns were sectioned from the cement-enamel junction and the root lengths were set at 16 mm. Then they were prepared up to ProTaper F3 file. Each root was numbered and data were obtained by measuring mesiodistal and buccolingual dimensions, volume, weight, and density. Tests for fracture strength were performed using an Instron Testing Machine (Instron Corp. MA, USA). The force was applied axially, angled at 45 degrees with a constant speed of 1 mm/min. For each sample, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically using linear regression analysis. Results: Volume and weight of the roots had more effect than mesiodistal or buccolingual dimensions on root fracture resistance. Conclusions: In root fracture resistance studies, volume or weight of the roots must be standardized when distributing roots to groups.

Nonsurgical management of a large periapical lesion in the anterior mandibular region of a patient with a deep traumatic overbite: A 3-year follow-up

The aim of this case report is to describe the management of a large periapical lesion in a patient without a trauma history, but with a deep traumatic overbite. The large periapical lesion in the region of the mandibular anterior teeth was detected in a routine radiographic examination. The patient was asymptomatic, and teeth 33, 32, 31, 41, and 42 failed to respond to thermal and electric testing. Nonsurgical endodontic treatment was performed on these teeth. Follow-up at 6 months, 1 year, and 2 years indicated that the radiolucency was reduced. Finally, follow-up at 3 years revealed that the large periapical lesion had disappeared.