Influence of blood contamination during multimode adhesive application on the microtensile bond strength to dentin.

OBJECTIVES: The present study evaluated the effects of blood contamination performed at different steps of bonding on the microtensile bond strength (µTBS) of multimode adhesives to dentin when using the self-etch approach. MATERIALS AND METHODS: Seventy-five molars were randomly assigned to three adhesive groups comprising 25 specimens each: two multimode adhesives [Single Bond Universal (SBU) and All-Bond Universal (ABU)] and a conventional one-step self-etch adhesive [Clearfil S3 Bond Plus (CSBP)]. Each group was subdivided as follows: (1) uncontaminated (control): bonding application/light curing as a positive control; (2) contamination-1 (cont-1): bonding application/light curing/blood contamination/dry as a negative control; (3) contamination-2 (cont-2): bonding application/light curing/blood contamination/rinse/dry; (4) contamination-3 (cont-3): bonding application/blood contamination/dry/bonding re-application/light curing; and (5) contamination-4 (cont-4): bonding application/blood contamination/rinse/dry/bonding re-application/light curing. Dentin specimens were prepared for µTBS testing after the composite resin application. Data were analyzed with two-way ANOVA and post-hoc tests (α = 0.05). RESULTS: µTBS values were similar in cont-3 groups, and ABU/cont-4 and corresponding control groups, but were significantly lower in the other groups than in their control groups (P < 0.05). Cont-1 groups showed the lowest µTBS values (P < 0.05). CONCLUSIONS: Neither decontamination method prevented the decrease in µTBS when contamination occurred after light curing. Drying the blood contaminants and reapplying the adhesive may regain the dentin adhesion when contamination occurs before light curing. Alternatively, rinsing and drying contaminants followed by adhesive re-application may be effective depending on adhesive type.

The force required to fracture endodontically roots restored with various materials as intra-orifice barriers.

OBJECTIVE: To evaluate the effect of various materials as intra-orifice barriers on the force required fracture roots. MATERIALS AND METHODS: One hundred-thirty five mandibular premolars were decoronated and prepared up to size #40. The root canals were filled and randomly divided into two control and seven experimental groups (n = 15), as follows: Positive control group (the intra-orifice barrier cavity was not prepared), negative control group (the intra-orifice barrier cavity was prepared, but not filled), filling using glass ionomer cement, nano-hybrid composite resin, short fiber-reinforced composite, bulk-fill flowable composite, MTA Angelus, Micro Mega MTA or Biodentine. A fracture strength test was performed, and the data were analyzed using one-way ANOVA and Tukey's post hoc tests. RESULTS: Nano-hybrid composite, short fiber-reinforced composite, bulk-fill flow able composite, and glass ionomer cement increased the force required fracture the roots compared to the positive and negative control groups (P < 0.05). While MTA groups did not increase the force required fracture the roots compared to the control groups, Biodentine increased significantly. CONCLUSIONS: Within the limitations of the present study, the use of nano-hybrid composite, short fiber-reinforced composite, bulk-fill flowable composite, and glass ionomer cement as an intra-orifice barrier may be useful in reinforcing roots. MTA placement (MTA Angelus or Micro Mega MTA) did not significantly increase the fracture resistance of endodontically treated roots compared to the control groups, however Biodentine did.

An in vitro comparison of irrigation using photon-initiated photoacoustic streaming, ultrasonic, sonic and needle techniques in removing calcium hydroxide.

AIM: To evaluate the effect of various techniques including photon-initiated photoacoustic streaming (PIPS), ultrasonic, sonic and needle irrigation on the removal of calcium hydroxide [Ca(OH)2 ] from artificial grooves created in root canals. METHODS: The root canals of 48 extracted single-rooted teeth with straight canals were prepared using ProTaper rotary instruments up to size 40. After the specimens had been split longitudinally, a standardized groove was prepared in the apical part of one segment that was filled with Ca(OH)2 powder mixed with distilled water. Each tooth was reassembled and the apices closed with wax. The specimens were irrigated for 60 s with one of the following techniques: needle irrigation using 17% EDTA, PIPS with 17% EDTA, ultrasonic irrigation using 17% EDTA and sonic irrigation (EndoActivator) using 17% EDTA. The root segments were then disassembled, and the amount of remaining Ca(OH)2 evaluated under a stereomicroscope at 25× magnification. A pixel count of Ca(OH)2 remaining on the artificially created grooves was recorded as a percentage of the overall groove surface. The data were evaluated statistically using one-way analysis of variance and the least significant difference post hoc tests at 95% confidence level (P = 0.05). RESULTS: Photon-initiated photoacoustic streaming was superior in removing Ca(OH)2 as compared to needle irrigation (P < 0.001), sonic irrigation (P < 0.001) and ultrasonic irrigation (P = 0.046). CONCLUSION: Photon-initiated photoacoustic streaming provided complete removal of Ca(OH)2 from artificial grooves in straight root canals. Ultrasonic irrigation enhanced the Ca(OH)2 removal capacity of irrigating solution but did not provide complete removal from artificial grooves.

Effect of photon-initiated photoacoustic streaming on removal of apically placed dentinal debris.

AIM: To compare the efficacy of photon-induced photoacoustic streaming (PIPS) technique with conventional, sonic and ultrasonic irrigation on the removal of apically placed dentinal debris from an artificial groove created in a root canal. METHODOLOGY: Root canal preparation was performed up to size 40 on 48 extracted single-rooted teeth using ProTaper rotary instruments. The specimens were then split longitudinally, and a standardized groove was prepared in the apical part of each segment. Each groove was filled with dentinal debris mixed with 5% NaOCl. Each tooth was reassembled and irrigated as follows: (i) conventional irrigation with 1% NaOCl, (ii) sonic, (iii) ultrasonic irrigation, and (iv) PIPS. The root segments were disassembled, and the amount of remaining dentinal debris was evaluated under a stereomicroscope at 20× magnification, using a four-grade scoring system. The data were evaluated statistically using Kruskal-Wallis and Mann-Whitney U-tests with a 95% confidence level (P = 0.05). RESULTS: Photon-induced photoacoustic streaming removed significantly more dentinal debris than conventional irrigation (P < 0.001), sonic irrigation (P < 0.001) or ultrasonic irrigation (P = 0.005). There was no significant difference between sonic and ultrasonic irrigation (P = 0.377). CONCLUSIONS: Photon-induced photoacoustic streaming was more effective than conventional, sonic and ultrasonic irrigation in the removal of apically placed dentinal debris.

Effectiveness of laser-assisted irrigation and passive ultrasonic irrigation techniques on smear layer removal in middle and apical thirds.

The purpose of this study was to investigate the evaluation of laser-assisted irrigation (LAI) on the removal of the smear layer as compared to passive ultrasonic irrigation (PUI). Forty-eight single-rooted, upper-central incisor teeth were selected and prepared with ProTaper rotary instruments up to size #40 (F4) at the working lengths. Specimens were divided into four groups, as follows: (a) PUI with 5 mL of 2.5% NaOCl for 60 s; (b) PUI with 2.5 mL of 17% EDTA and 2.5 mL of 2.5% NaOCl each for 30 s; (c) LAI with 5 mL of 2.5% NaOCl for 60 s; and (d) LAI with 2.5 mL of 17% EDTA and 2.5 mL of 2.5% NaOCl each for 30 s. In the PUI groups, the ultrasonically activated file was inserted 1 mm short of the working length, but in the LAI groups, the fiber tip was applied into the pulp chamber. LAI in the pulp chamber with the combination of 17% EDTA and 2.5% NaOCl removed more of the smear layer than the other groups (p < 0.018). LAI in the pulp chamber with the combination of 2.5% NaOCl and 17% EDTA better removed the smear layer than LAI applied similarly but without EDTA or PUI with the same NaOCl and EDTA combinations using an ultrasonically activated file inserted 1 mm short of the working length.