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Effect of different surface treatments on the push-out bond strength of fiber post to root canal dentin

OBJECTIVE The purpose of this study was to evaluate the effects of different surface treatments on the bond strength of a fiber post to dentin. STUDY DESIGN Sixty extracted human maxillary incisor teeth were manually shaped with K-files using the step-back technique. ISO size 45 files were used as master apical files. Post spaces were prepared and then the root canals were subjected to one of the following 5 surface treatments: irrigation with 5% sodium hypochlorite (NaOCl); treatment with ethanol, ethyl acetate, and acetone-based cleansing agent (Sikko Tim); irrigation with 17% EDTA; etching with 37% orthophosphoric acid for 15 seconds; and etching with 10% citric acid for 15 seconds. Fiber posts were luted using self-etching/self-priming dual polymerized resin cement. From the coronal part of each root, 3 slides of 0.6-mm thickness were obtained. A push-out bond strength test was performed by a universal testing machine at a crosshead speed of 0.5 mm/min. Dentin surfaces were examined under scanning electron microscopy (SEM) after different surface treatments. Data were analyzed with a one-way analysis of variance (ANOVA) and Tukey HSD test. RESULTS ANOVA revealed that canal surface treatment affected the bond strength (P < .001). The highest bond strength was obtained in the Sikko Tim group. The results also showed that surface treatment methods increased the bond strength to dentin when compared with the control group. CONCLUSIONS Sikko Tim group was the more effective surface treatment agent compared with EDTA, orthophosphoric acid, citric acid, and control groups; however, it could not remove the smear layer and sealer remnants effectively on radicular dentin surfaces. Removal of the smear layer and opening of dentinal tubules are not recommended when a self-etching/self-priming adhesive system is used.

Effects of Three Canal Sealers on Bond Strength of a Fiber Post

INTRODUCTION This study evaluated the effects of three different endodontic sealers on the bond strength of a fiber post cemented with adhesive resin cement. METHODS Forty-eight extracted maxillary central incisors were prepared with the step-back technique and randomly divided into four groups (n=12 for each group): group 1, control group (gutta-percha points only, no sealer); group 2, resin-based sealer (AH plus; Dentsply De Trey GmbH, Konstanz, Germany); group 3, zinc oxide-eugenol-based sealer (Endofill; Produits Dentaires SA, Vevey, Switzerland); and group 4, calcium hydroxide-based sealer (Sealapex; Kerr, Romulus, MI). The roots were obturated with gutta-percha using the cold lateral compaction technique. Fiber posts were cemented into the prepared post spaces with the adhesive resin cement Panavia F 2.0 (Kuraray Medical, Okayama, Japan). A push-out test was performed in a universal machine, and failure modes were observed. Morphologic changes of the root canal dentin surfaces were examined with scanning electron microscopy (SEM). RESULTS One-way analysis of variance revealed that sealers have significant effects on bond strength (p<0.05). The control group had the highest mean push-out bond strength. No statistical difference was detected between the eugenol-based sealer group and the resin-based sealer group (p>0.05). The root surfaces were covered with the smear layer and debris in all the groups after post space preparation in SEM analysis. However, some of the dentin tubules were partially open in the control and calcium hydroxide-based sealer groups after the application of the resin monomer. CONCLUSION The results of this study showed that the type of canal sealer and chemomechanical preparation of the root canals affect the bond strength of a fiber post cemented with resin cement.

Comparison of shaping ability of RaCe and Hero Shaper instruments in simulated curved canals

OBJECTIVE This study compared the shaping ability of Hero Shaper and RaCe instruments in simulated curved canals. STUDY DESIGN Forty simulated canals in resin blocks were divided into 2 experimental groups, each comprising 20 resin blocks, and prepared with Hero Shaper and RaCe using the crown-down technique. Preoperative and postoperative photographs, recorded using a digital camera, were superimposed and aberrations were recorded. Material removal was measured at 10 points beginning 1 mm from the end point of the canal. Mean total widths, outer and inner width measurements, were determined on each central canal path and differences were statistically analyzed using Student t test. RESULTS The Hero Shaper and RaCe instruments removed almost the same amount of material from the inner side of the simulated canals. On the outer canal wall, the RaCe instruments removed significantly more material from the first 3 mm (P < .05). However, Hero Shaper removed more material from the middle and coronal aspects of the canal and the differences were statistically significant (P < .01). CONCLUSION RaCe instruments removed more resin from the outside of the curvature at the apical thirds, while Hero Shaper removed more material from the middle and coronal thirds on the outer canal wall. Hero Shaper instruments showed better centering ability and fewer aberrations. No instrument fractures but some deformations were observed for both systems.

Endodontic treatment of a taurodontic premolar with five canals.

Taurodontism is a morpho-anatomical abnormality in the shape of a tooth. An enlarged pulp chamber, apical displacement of the pulpal floor and no constriction at the level of the cemento-enamel junction are the characteristic features. Special care is required in all aspects of endodontic treatment of a taurodontal tooth, including identifying the orifice, canal exploration, cleaning, shaping and obturation of the root canal. This case report describes the successful endodontic treatment of a taurodontic mandibular second premolar with five root canals.

Clinical evaluation of direct composite restorations and inlays: Results at 12 months

Background: The purpose of this study was to compare the clinical performance of Class II direct and indirect composite restorations according to the United States Public Health Service criteria (USPHS). Materials and Methods: Seventy patients were included and four different composite resins, P60 (FP), SureFil Posterior (SP), Gradia Posterior (GP), and Bisco Aelite LS Packable (BAP) were used as direct restorative material. All of the composite resins except BAP were used as indirect restorative material. Instead of BAP, Tescera Laboratory composites were polymerized in Tescera inlay oven. All restorations were evaluated according to USPHS criteria during a one-year period. Results: There were no statistically significant differences between direct and indirect composite restorations according to the retention, marginal discoloration, surface staining, proximal contact continuity, and secondary caries. Indirect restorations have less surface roughness, postoperative sensitivity (P < 0.05), and soft tissue irritation (P < 0.1) than direct ones. Conclusion: The clinical performances of the indirect restorations were more satisfactory than the direct restorations.

Microtensile bond strength of three adhesive systems to different dentin tissues

Purpose: The aim of this in vitro study was to determine the micro-tensile bond strengths (mTBS) of three adhesive systems (Prime&Bond NT, Clearfil SE Bond, G Bond) to four different dentin structures; bovine dentin and unerupted, sound, caries affected human dentins. Materials and Methods: Flat bovine molar, unerupted, sound and caries affected human molar dentin structures were obtained at the occlusal surfaces of the extracted teeth. Final surface grindings were performed using 600-grit Silicon carbide paper. Three adhesive systems (Prime&Bond NT, Clearfil SE Bond, G Bond) were used to bond composite resin (P60, 3M ESPE) to the prepared dentin surfaces. After 24 h distilled-water storage, the bonded specimens were cross-sectioned (0.8 ± 0.2 mm 2 ) and subjected to a (μTBS) test. One-way analysis of variance multiple comparison test were used to statistically analyze the mean bond strength data α =0.05. Results: There was statistically significant difference in mTBS among the dentin types (P < 0.0005). Mean bond strength to sound human and bovine dentin was significantly higher than to caries-affected dentin and dentin of unerupted human teeth (P < 0.05). Statistically similar bond strength was obtained with Prime&Bond NT and Clearfil SE Bond while G-Bond showed the lowest bond strengths. Conclusion: The type of dentin structure has an important effect on the mTBS values of adhesive systems.

ADEZİF SİSTEMLERİN DERİN VE YÜZEYEL DENTİNE MİKRO-TENSİLE BAĞLANMA DAYANIMLARI MICRO-TENSILE BOND STRENGTHS OF ADHESIVE SYSTEMS TO DEEP AND SUPERFICIAL DENTIN

OZET Bu calismanin amaci total-etch [Prime&BondNT-PBNT, Single Bond-SB, Excite-EB, One Coat Bond-OCB] ve self-etch [Clearfil SE Bond-CSEB, Xeno III-XIII, Tyrian/One Step Plus-TOSP, Prompt L-Pop-PLP] adezif sistemlerin derin ve yuzeyel dentine mikro-tensile baglanma (µTBS) dayanimlarini karsilastirmaktir. Bu calismada 56 adet cekilmis, curuk icermeyen mandibular 3. buyuk azi disi kullanildi. Yuzeyel okluzal dentin aciga cikarildi ve kompozit recine (TPH Spectrum) bir adezif recine ile baglandi. Ornekler z ve y akslari yonunde, disin uzun aksina paralel, bir elmas disk kullanarak kesildi. Elde edilen cubuklar geride kalan dentin kalinligina gore yuzeyel ve derin dentin olarak iki gruba ayrildi. Kompozit-recine-dentin uclusunden olusan cubuklara, baglantida kopma oluncaya kadar, 1 mm/dk hizla kuvvet uygulandi. Ortalama µTBS degerleri iki yonlu varyans analizi kullanilarak karsilastirildi (I± =0.05). Adezif sistemlerin derin ve yuzeyel dentine baglanma dayanimlari arasinda istatistiksel olarak anlamli bir farklilik bulunmadi (p>0.05). Total-etch adezif sistemler, CSEB disindaki, self-etch adezif sistemlere gore daha yuksek baglanma dayanimi gosterdi (p 0.05). Total-etch systems obtained higher bond strength than the self-etch adhesive systems, except for CSEB (p<0.05). The depth of dentin may be not important on bond strength of actual dentin adhesive systems. Key Words: Adhesives, Micro-tensile test, Depth of dentin