Journal of Conservative Dentistry
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JOURNAL REVIEWS Table of Contents   
Year : 2009  |  Volume : 12  |  Issue : 4  |  Page : 176-177
Journal Reviews


Post-graduate Students, Department of Conservative Dentistry & Endodontics Meenakshi Ammal Dental College, Maduravoyal, Chennai - 600095, India

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Date of Web Publication15-Dec-2009
 

How to cite this article:
Bhardwaj A, Albuquerque D. Journal Reviews. J Conserv Dent 2009;12:176-7

How to cite this URL:
Bhardwaj A, Albuquerque D. Journal Reviews. J Conserv Dent [serial online] 2009 [cited 2019 Apr 21];12:176-7. Available from: http://www.jcd.org.in/text.asp?2009/12/4/176/58348
Improving the effect of NaOCl pretreatment on bonding to caries-affected dentin using self-etch adhesives

Taniguchi G, Nakajima M, Hosaka K, Iwamoto N, Ikeda M, Foxton RM, Tagami J

The effect of sodium hypochlorite pretreatment on adhesion to normal and caries-affected dentin using self-etch adhesives was evaluated. Forty extracted human molars with coronal carious lesions were used in this experiment. The occlusal dentin surfaces including the caries-affected dentin in each group were treated as follows: group 1, rinsed with water; group 2, treated with 6% NaOCl for 15s; group 3, treated with 6% NaOCl for 30 s; group 4, application with Accel (a reducing agent containing p-toluenesulfunic acid sodium salt) for 30 s after NaOCl-30 s pretreatment. After rinsing with water and air-drying, the treated dentin surfaces were applied with self-etch systems (Bond Force and Clearfil Protect Bond) according to the manufacturers' instructions, and built-up with resin composite. After 37° C water storage for 24 h, the bonded normal or caries-affected dentin areas were isolated to create an hourglass configuration with a cross-sectional area of approximately 1 mm 2 . The specimens were subjected to tensile stress at a cross-head speed of 1.0 mm/min. The results showed that NaOCl-15 s pretreatment significantly improved the µTBS of both self-etch adhesives to caries-affected dentin, while the 30 s pretreatment did not affect them. For normal dentin, NaOCl-30 s pretreatment significantly reduced the µTBS of both self-etch adhesives although the 15s pretreatment did not alter them. Furthermore, the application of Accel with a reducing effect increased the µTBS to normal and caries-affected dentin treated with NaOCl for 30 s. SEM images revealed that the smear layer on caries-affected dentin layer exhibited a different morphology, which was thick and irregular with fibril-like structures, compared to the smear layer on normal dentin, which had a compact surface. NaOCl pretreatment thinned out the smear layer and did not show the presence of fibrin like structures. This could help in better diffusion of self-etch adhesives and stronger hybrid layer formation. The authors concluded that the effects of NaOCl pretreatment on bonding of both self-etch adhesives were dependent upon type of dentin (normal and caries-affected dentin) and the treatment time.

J Dent. 2009 Oct;37(10):769-75.

Effects of adhesive temperature on the early and 6-month dentin bonding

Reis A, Klein-Júnior CA, Accorinte Mde L, Grande RH, dos Santos CB, Loguercio AD

The aim of this study was to test the effect of adhesive temperature on the bond strength to dentin (µTBS) and silver nitrate uptake (SNU) of an ethanol/water (Adper Single Bond 2 [SB]) and an acetone-based (Prime&Bond 2.1 [PB]) etch-and-rinse adhesive system. The bottles of each adhesive were kept in various temperatures (5° C, 20° C, 37° C and 50° C) for 1 hour prior to its application in the occlusal demineralized dentin of 40 molars. Bonded sticks (0.8 mm 2 ) were tested in tension (0.5 mm/min) immediately (IM) or after 6 months (6 M) of water storage. Two bonded sticks from each hemi-tooth were immersed in silver nitrate and analyzed by SEM. Data were analyzed by two-way repeated measures ANOVA and Tukey's test (a=0.05). Results revealed no significant difference in µTBS for both adhesives at 37° C and SB at 50° C as the adhesives could have been heated sufficiently to higher temperatures by the unavoidable heat produced by the light curing units. The highest bond strength for PB was observed in the 37° C group while for SB it was in the 50° C. An increase in temperature is accompanied by an increase in the reaction rate and could lead to better bond strength at these temperatures. Also at higher temperatures, the viscosities and spreading velocities of the adhesive systems are increased causing a deeper penetration rate into the acid etched dentin. Significant reductions of bond strengths were observed for PB at 37° C and SB at 50° C after 6 M of water storage. Heating of the adhesive beyond a critical point could cause alteration or evaporation of chemical species from the adhesive systems leading to slowing of or complete stoppage of the chemical reaction and thus affecting bond strength. Silver nitrate deposition was seen in all hybrid layers, irrespective of the group. Lower silver nitrate deposition (water trees) in the adhesive layer was seen for PB and SB at higher temperatures. It was concluded that the heating or refrigeration of the adhesives did not improve their resin-dentin bond resistance to water degradation over time.

J Dent. 2009 Oct;37(10):791-8.

Limited ability of three commonly used thermoplasticized gutta-percha techniques in filling oval-shaped canals

De-Deus G, Reis C, Beznos D, de Abranches AMG, Coutinho-Filhoand T, Paciornik S

The present study was designed to compare the percentage of gutta-percha-filled area (PGFA) achieved in oval-shaped canals after filling by 3 thermoplasticized techniques. Study is designed to compare the percentage of gutta-percha-filled area (PGFA) achieved in oval-shaped canals after filling by 3 thermoplasticized techniques. Eighty-seven oval-shaped root canals were prepared and root-filled as follows: lateral condensation (n=20), thermomechanical compaction (n= 20), wave of condensation (n= 20), and Thermafil system (n = 20). A cross section of each tooth was made 5 mm from the apex, and the samples were prepared for microscopic analysis. Digital image measurements of the cross-sectioned area of the canal and the gutta-percha were performed, and the PGFA was calculated. Nonparametric statistical analysis was performed with the Kruskal-Wallis H test and post hoc Dunn test. Overall, PGFAs were variable among the experimental groups, ranging from 37.1%-98.5%, and the pooled data from all techniques had a general mean of 69.6% ± 18%. Thermafil system, wave of condensation, and thermomechanical compaction produced significantly higher PGFAs than lateral condensation (P< .05); however, no significant differences among these techniques were detected (P< .05). Therefore, a limited ability to fill oval-shaped canals was achieved in the 3 thermoplasticized techniques tested. The present study results yields an interesting thought for further consideration; in as much as the 3 thermoplasticized obturation techniques tested displayed a similar filling ability, the most simple and cost-effective technique should be indicated for the typical endodontic practice. Moreover, by the present results it can be clearly stated that the quality of root canal filling in oval-shaped canals is compromised even when thermoplasticized techniques are used.

J Endod, Volume 34, Number 11, November 2008.

To assess the influence of multiple clinical uses on the torsional behaviour of ProTaper Universal rotary NiTi instruments.

Vieira EP, Nakagawa RKL, Buono VTL, Bahia MGA

Root canal treatment was performed on patients using the ProTaper Universal rotary system to prepare canals. Ten sets of instruments were used by an experienced endodontist, each set being used in five molar teeth. After clinical use, S1, S2, F1 and F2 instruments were analysed for damage by optical and scanning electron microscopy. The used sets, along with a control group of 10 sets of new instruments, were then torsion tested based on the ISO 3630-1 specification. Data obtained were subjected to a one-way analysis of variance (Anova) with a = 0.05. The use of the ProTaper Universal rotary instruments by an experienced endodontist allowed for the cleaning and shaping of the root canal system of five molar teeth without fracture. The maximum torque for instruments S2, F1 and F2, and the angular deflection at fracture for instruments S2 and F1 were significantly lower following clinical use. The largest decrease in maximum torque was 18.6% (P = 0.014) for S2 instruments. The same maximum percent decrease was found for angular deflection at fracture for F1 instruments (P = 0.009). Structural fatigue takes place during the clinical use of the instruments and, in addition to the usual transversal cracks generate by flexural fatigue, longitudinal cracks were also observed on the surface of the used instruments. The cross-sectional shape of instruments affects the stress distribution pattern as well as their torsional properties and maximum torque of endodontic instruments increases as instrument diameter becomes larger. ProTaper instruments indicate that the cumulative effects of multiple clinical uses on rotary NiTi endodontic instruments have a stronger influence on flexural fatigue behaviour than on their torsional resistance. It was concluded that torsional resistance and angular deflection of used instruments, as compared to that of new instruments, were reduced following clinical use.

Int Endodon J, 42, 947-953, 2009.

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Correspondence Address:
Anuj Bhardwaj
Post-graduate Students, Department of Conservative Dentistry & Endodontics Meenakshi Ammal Dental College, Maduravoyal, Chennai - 600095
India
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Source of Support: None, Conflict of Interest: None


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