Kürşat Er

Amaç: Bu çalışmanın amacı, yapay kanallar kullanılarak yeni ve kullanılmış Revo-S nikel titanyum döner eğe sisteminin döngüsel yorgunluk (DY) dirençlerinin karşılaştırılmasıdır. Gereç ve Yöntem: Her gruptan 12 adet olmak üzere toplam 72 adet yeni ve 2 defa klinikte kullanılmış Revo-S SC1 (25/.06), Revo-S SC2 (25/.04) ve Revo-S SU (25/.06) eğeler çalışmaya dahil edildi. DY direnci testleri için iç çapı 1.5 mm olan, 60° eğrilik açısı ve 5 mm eğrilik yarıçapına sahip olan kavisli bir yapay kanal içeren paslanmaz çelik blok kullanıldı. Deney sistemi distile su ile dolduruldu ve ortam sıcaklığı 35 ± 1 °C sıcaklıkta sabit tutuldu. Eğeler kırılma gerçekleşene kadar yapay kanal içinde çalıştırıldı. Her eğe için kırılma gerçekleşene kadar geçen süre kronometre ile kaydedildi ve eğelerin kırılıncaya kadar yaptıkları tur sayısı hesaplandı. Elde edilen veriler tek yönlü varyans analizi ve post-hoc Tukey testi kullanılarak değerlendirildi. Bulgular: Eğelerin kırılıncaya kadar yaptığı ortalama tur sayısı en yüksek yeni SC2 eğe grubunda (912.3 ± 76.8), en düşük ise kullanılmış SU eğe grubunda (204.2 ± 59.6) bulundu. SC1 ve SC2 eğeler için yeni ve kullanılmış eğeler arasında DY direnci açısından istatistiksel olarak anlamlı bir fark gözlenmez iken (p>0.05), SU eğe grubunda anlamlı bir fark bulundu (p<0.05). Sonuç: Çalışmamızın sınırlamaları dahilinde; klinik kullanım sonrasında tüm eğelerin DY direncinde azalma olduğu ancak bu azalmanın sadece SU eğe grubunda önemli olduğu bulundu.

Objective: The aim of this study was to investigate the efficacy of an erbium chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser with different irrigation solutions [sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), QMix 2in1, and peracetic acid] in removing calcium hydroxide (CH) from artificial grooves created in root canals. Background data: CH has to be removed totally before the root canal filling. Any CH residue on the dentin walls may affect the dentinal bond strength and the penetration of sealers into the dentin tubules, and may increase apical leakage. In addition, such a remnant could react chemically with sealers and, possibly, influence physical properties. Therefore, complete removal of CH placed inside the root canals is recommended, using various products and techniques. Methods: The root canals of 160 extracted single-rooted mandibular premolars were prepared with ProTaper Universal rotary instruments up to size F4. The roots were split longitudinally along the length of the instrumented canals, and a standardized groove was prepared in the apical part of one segment. CH powder mixed with distilled water was placed into the grooves, and the root halves were then reassembled. The roots were randomly divided into two main groups according to the selected irrigation techniques (needle and laser activation) and then each main group was divided into four subgroups according to the final irrigation (NaOCl, EDTA, QMix 2in1, and peracetic acid) protocols used. After irrigation, the roots were disassembled and digital images were taken using a stereomicroscope. Measurements of residual CH were performed as percentages of the overall groove surface area with image analysis software. The data obtained were analyzed using one way analysis of variance and Tukey's honest significant difference tests. Statistical significance was set at p < 0.05. Results: Significantly less residual CH was obtained in the laser-activated groups than in the needle-irrigated groups ( p < 0.05). According to both main groups' data, NaOCl left significantly more CH than the other groups ( p < 0.05). However, there was no significant difference among the EDTA, QMix 2in1, and peracetic acid groups. Conclusions: None of the techniques removed the CH dressing completely. Laser-activated irrigation was significantly more effective than needle irrigation.

The aim of this study was to compare the neurotoxicity of various root canal sealers on rat sciatic nerve by electrophysiologic and histopathologic analyses. A total of 40 male rats were randomly divided into five groups: Control, AH Plus, GuttaFlow, Sealapex and Smartpastebio. Sciatic nerves of the rats were uncovered using the surgical procedures, and the prepared sealers were then applied on nerves with a polyethylene tube vehicle for 15 days. Nerve potentials were recorded at initial exposure, 5, 30 and 120 min (early phase), and 15 days (late phase) by an electrophysiologic analysis system for all groups. The obtained measurements were then used to calculate the nerve conduction velocities (NCV). Subsequently, all rats were sacrificed, and their sciatic nerves were removed for histopathologic analysis. Statistical analysis was performed using the Kruskal-Wallis and Mann-Whitney U tests for intergroup variables and the Friedman and Wilcoxon test for intragroup variables. Statistical significance was set at P < 0.05. There was no significant difference between early and late phase results in the control group. This group showed little or no lasting damage to nerve tissue. All sealers decreased the NCV in the early phase time periods, but this decrease was only statistically significant in the AH Plus group at 120-min time period (P < 0.0125). During the late phase, the AH Plus and GuttaFlow groups almost reached initial NCV values, and it was lower than the initial values in the Sealapex and Smartpastebio groups. However, this decrease was not statistically significant. When intergroup comparisons were performed, statistically significant differences occurred at 30 min in the Sealapex group and 120 min in the AH Plus group compared with the control group (P < 0.0125). All sealers induced neurotoxicity as a result of degenerative and inflammatory responses of nerve tissue in histologic analysis. Histologic analysis revealed Sealapex and GuttaFlow to be the most and least neurotoxic, respectively. All tested root canal sealers exhibited a variable degree of neurotoxicity depending on their chemical compositions. Apical extrusion of endodontic filling materials may cause undesired consequences, such as inflammation and severe neurotoxic damage; therefore, extrusion factor plays an important role during the root canal treatment.

The aim of this study was to compare the push-out bond strength of three calcium silicate cements to dentine after two different irrigation regimes. One hundred eighty 2-mm-thick root sections were prepared. The sections were divided into three main groups (n = 60). In group A, the sections were immersed in 1 % NaOCl for 3 min. In group B, the sections were immersed in 17 % EDTA for 3 min followed by 1 % NaOCl for the same period of time. In group C (control group), no irrigation was applied to the sections. The samples from each group were divided into four subgroups (n = 15). In subgroups A1, B1 and C1, DiaRoot BioAggregate; in subgroups A2, B2 and C2, MTA-Angelus and in subgroups A3, B3 and C3, MM-MTA were mixed with hand-mixing. In subgroups A4, B4 and C4, MM-MTA was mixed with auto-mixing. The mixed cements were then placed into cavities with a carrier. The samples were submitted to the push-out test and were loaded. All the data were analysed with one-way analysis of variance and the Tukey HSD multiple comparisons (p < 0.05). There were no statistically significant differences between the irrigation regimes regardless of the used materials. The resistance to displacement in subgroup B4 was significantly greater than that presented by subgroups A3, B3 and C3 (p < 0.05) while not different than all other groups. Irrigation regimes had not affected the push-out bond strength of the calcium silicate cements. Also, strength of auto-mixed MM-MTA was similar to the other cements. The novel calcium silicate cements would be a potentially useful material in endodontic procedures with favourable properties.

Objectives: This study was designed to evaluate the fracture resistance of retreated roots using different rotary retreatment systems. Methods: Forty eight freshly extracted human canine teeth with single straight root canals were instrumented sequentially increasing from size 30 to a size 55 using K-files whit a stepback technique. The teeth were randomly divided into three experimental and one control groups of 12 specimens each. The root canals were filled using cold lateral compaction of gutta-percha and AH Plus (Dentsply Detrey, Konstanz, Germany) sealer in experimental groups. Removal of gutta-percha was performed with the following devices and techniques: ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), R-Endo (Micro-Mega, Besançon, France), and Mtwo (Sweden & Martina, Padova, Italy) rotary retreatment systems. Control group specimens were only instrumented, not filled or retreated. The specimens were then mounted in copper rings, were filled with a self-curing polymethylmethacrylate resin, and the force required to cause vertical root fracture was measured using a universal testing device. The force of fracture of the roots was recorded and the results in the various groups were compared. Statistical analysis was accomplished by one-way ANOVA and a post hoc Tukey tests. Results: There were statistically significant differences between the control and experimental groups (P<.05). However, there were no significant differences among the experimental groups. Conclusions: Based on the results, all rotary retreatment techniques used in this in vitro study produced similar root weakness. (Eur J Dent 2011;5:387-392)

To determine the percent gutta-percha-filled area in the apical third of root canals after filling with 2 different root filling techniques. Thirty extracted human lower premolars were instrumented with ProTaper rotary files (Dentsply Maillefer) and then randomly divided into 2 groups of 15 teeth each. The first group was filled using the single-cone technique with a tapered gutta-percha cone. The second group was filled with the lateral condensation technique. Horizontal sections were cut 2 and 4 mm from the apical foramen of each tooth. Photomicrographs of the apical surface of each cross-section were obtained at magnification x40. Digital image analysis was used to measure the overall area of the canal and the aggregate area occupied by gutta-percha; from these values, the percent gutta-percha-filled area was calculated. The data were compared by t test. The single-cone technique produced significantly greater percent gutta-percha filled area at 2 mm from the apex (p = 0.046), but there was no significant difference between the techniques at 4 mm from the apex (p = 0.17). These results suggest that the single-cone technique with tapered gutta-percha cones may yield better filling (measured as the percent gutta-percha-filled area) than the lateral condensation technique, at a level 2 mm from the apex.