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This in vitro study compared the effectiveness between ProFile 29 Series rotary system followed by continuous wave obturation and the Endo-Eze system. Thirty-six human mandibular canine and premolar teeth were randomly separated into 2 groups of 18. Each tooth was embedded in resin and sectioned at 2, 6, and 12 mm from the apex and viewed under the scanning electron microscope at 50-150x magnification. The percentages of canal space occupied by gutta-percha, sealer, debris, and voids were measured and analyzed with Image J software. Results were calculated by using an analysis of variance model with fixed effects for method, distance, and distance interaction. Repeatability of measurements and intraclass correlation coefficients were calculated. These results demonstrated that obturation with the continuous wave technique achieved significantly more gutta-percha occupying the canal space than the Endo-Eze system. Under the conditions of this study, the continuous wave technique was less likely to exhibit voids than the Endo-Eze technique. Furthermore, neither the Profile Series 29 nor the Endo-Eze system cleaned and shaped elliptical canals consistently.

This investigation compared microleakage of teeth obturated with gutta-percha and teeth obturated with Resilon by using a fluid filtration model. Forty-six human, single-rooted, mandibular premolars were studied. Teeth were randomly assigned to 2 experimental groups of 21 teeth each, designated as group G (gutta-percha) and group R (Resilon). Two control groups, both containing 2 teeth, served as positive and negative controls. Group G, gutta-percha and AH 26 sealer, and group R, Resilon and Epiphany sealer, were obturated by using warm vertical condensation. The specimens were tested for microleakage with an in vitro fluid filtration apparatus at 10 psi at 4 intervals: 1, 7, 30, and 90 days. A two-way repeated measures analysis of variance model with fixed effects for group, time, and group by time interaction was used to analyze microleakage data. This study demonstrated that canals obturated with Resilon and Epiphany sealer leaked statistically less than canals obturated with gutta-percha and AH 26 sealer at day 1 (P < .0014), day 7 (P < .0002), day 30 (P < .0015), and day 90 (P < .0170). The mean fluid microleakage for both group G and group R increased from day 1 to day 90. The results showed that Resilon is a suitable replacement for gutta-percha as a root canal filling material on the basis of its increased resistance to fluid microleakage.

The purpose of this study was to compare the contents of root canals obturated with gutta percha and AH-26 sealer (Dentsply, Tulsa, OK) to canals obturated with the Resilon and Epiphany (Pentron, Wallingford, CT) system. Canal contents were assessed by determining the percentage of canal space occupied by core material, sealer, voids, and debris. Forty extracted human maxillary anterior teeth were instrumented, and the teeth were randomly assigned to either the gutta percha/AH 26 group or the Epiphany/Resilon group. Canals were obturated, and the teeth were subsequently embedded in resin and sectioned horizontally at 2, 4, and 6 mm from the anatomic apex. Sections were photographed by using a low vacuum scanning electron microscope. Image-J (Wayne Rasband; National Institute of Health, Bethesda, MD) software was used to quantify the proportion of core material, sealer, voids, and debris in each canal. Percentages and statistical comparisons for each method were compared. There were no significant differences found among the two groups in terms of the percentage of core (p = 0.9), sealer (p = 0.58), debris (p = 0.999), or voids (p = 1.00). Additionally, there were no differences in the percentage of core material, sealer, debris, or voids at any of the examined levels (2, 4, or 6 mm).

Endodontic sealers should demonstrate adhesive properties to dentin to reach the objectives of the obturation of the canal space and seal the canal space both apically and coronally, thus decreasing the chance of endodontic treatment failure. Adhesion to dentin with bonding to the tooth structure in the canal may provide greater resistance to tooth fracture and greater clinical longevity of an endodontically treated tooth. In this study, human single-canal canines were endodontically treated and obturated with two different endodontic obturation systems (Epiphany/Resilon system and gutta-percha/AH 26). Thirty roots (divided into two groups) were horizontally sliced for a push-out strength test, which was performed from apical to coronal in the universal testing machine. Differences in push-out bond strength between the two different material systems were obtained using repeated measures analysis of variance on ranks. Gutta-percha had significantly higher push-out bond strength than Epiphany (p<0.0001).

Objective: The purpose of this study was to determine the effect of Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) paste on demineralization of bovine enamel by measuring changes in the ultrasound transmission velocity., Methods: The enamel specimens were prepared by cutting bovine teeth into blocks. The specimens were stored in 0.1 M lactic acid buffer solution (pH 4.75, Ca 0.75 mM, P 0.45 mM) for 10 min twice a day, and then stored in the artificial saliva (pH 7.0). Other specimens were stored in a 10-times diluted solution of CPP-ACP paste and a placebo paste without CPP-ACP for 10 min, followed by 10 min immersion into a demineralization solution twice a day before storage in the artificial saliva. The propagation time of longitudinal ultrasonic waves was measured by a Pulser-Receiver (Model 5900, Panametrics) with a transducer (V112, Panametrics). Six specimens were used for each condition, and one-way ANOVAs followed by the Tukey HSD tests (alpha = 0.05) were done., Results: The sonic velocity was found to decrease with time for specimens stored in the demineralization solution. On the other hand, a significant increase in sonic velocity was found for specimens stored in the CPP-ACP solution., Conclusions: From the result of this study, it was suggested that the conditions of de- and remineralization of the enamel structure could be measured non-destructively by using an ultrasonic pulse method. It could be concluded that the inorganic components contained in high concentrations in CPP-ACP acted to enhance remineralization of the enamel structure.

In the past, most frictional resistance studies have been conducted in a steady state condition that does not simulate the dynamics of the oral environment. Various oral functions as chewing, swallowing, speaking, etc, as well as the oral tissues contacting any orthodontic appliances, result in periodic, repetitive, minute relative motion at the bracket/arch wire interfaces several thousand times each day. This in turn affects the normal forces at the interfaces, and because frictional resistance is directly proportional to the normal force, a pilot study was undertaken to emulate the dynamic environment of the oral cavity and its effect on frictional resistance. Tests of a limited sample of stainless steel arch wires and brackets typically used in sliding mechanics revealed that frictional resistance was effectively reduced to zero each time minute relative movements occurred at the bracket/arch wire interfaces. Factors such as the degree of dental tipping, relative arch wire/slot clearances, and method of tying, did not have a measurable effect on frictional resistance in the simulated dynamics of the oral environment.

Objectives: In clinical situations, a dentine primer is usually applied to enamel, in addition to dentine. This study was carried out to determine the influence of the air drying time of self-etching primers on their bond strength to enamel., Methods: Three self-etching primer systems, Fluoro Bond (FB, Shofu Inc.), Liner Bond II (LB, Kuraray Co.) and Mac Bond 2 (MB, Tokuyama Co.) were employed. Bovine mandibular incisors were mounted in self-curing resin and the enamel surfaces were wet ground with number 600 SiC paper. Following primer application, the enamel surface was dried with compressed air for 0, 2, 5, 10, 20, and 30 s from 10 cm above the enamel surface using a three-way syringe. Adhesives were applied and composites were condensed into a Teflon mold (4 x 2 mm) placed on the enamel and light activated. Ten samples per test group were stored in 37 degrees C water for 24 h, then shear tested at a crosshead speed of 1.0 mm min-1. One-way ANOVAs followed by Duncan tests (p < 0.05) were done., Results: The enamel bond strengths varied with the different air drying times and ranged from 8.2 +/- 3.2-17.4 +/- 3.0 MPa for LB, 10.9 +/- 2.8-16.3 +/- 3.3 MPa for FB, and 17.5 +/- 2.5-19.4 +/- 2.2 MPa for MB. For LB and FB, there appeared to be a minimum drying time of 10 s. LB was the most affected by drying time, while MB did not change., Conclusions: The data suggests that the enamel bond strengths of these bonding systems can be influenced by the drying time of the primer applied prior to bond agent application and the tendency was different among the systems studied.

The corrosion of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel. The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material. Both stainless steels were subjected to electrochemical and immersion (crevice) corrosion tests in 37 degrees C, 0.9 wt% sodium chloride solution. Electrochemical testing indicates that 2205 has a longer passivation range than 316L. The corrosion rate of 2205 was 0.416 MPY (milli-inch per year), whereas 316L exhibited 0.647 MPY. When 2205 was coupled to 316L with equal surface area ratio, the corrosion rate of 2205 reduced to 0.260 MPY, indicating that 316L stainless steel behaved like a sacrificial anode. When 316L is coupled with NiTi, TMA, or stainless steel arch wire and was subjected to the immersion corrosion test, it was found that 316L suffered from crevice corrosion. On the other hand, 2205 stainless steel did not show any localized crevice corrosion, although the surface of 2205 was covered with corrosion products, formed when coupled to NiTi and stainless steel wires. This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires.

The authors compared the retention and clinical performance of a resin-modified glass ionomer, or RMGI, restorative and a light-cured resin sealant. The first permanent molars on one side of the dental arch in 50 children were sealed with an RMGI, and the same teeth on the other side were sealed with a resin sealant. At baseline, six months after placement and one year after placement, examiners documented sealant retention, secondary caries, marginal discrepancy and marginal staining. In general, the RMGI appeared to wear markedly. At one year, the retention of the RMGI was significantly less than the resin, but the RMGI had significantly fewer marginal discrepancies. There were no significant differences in caries development or marginal discoloration.

Objective: The purpose of this study was to examine the influence of light irradiation of dentine primers that contain camphoroquinone (CQ) on the shear bond strength to dentine and their contact angle., Method: Three dentine bonding systems which contain CQ, Imperva Bond, OptiBond and XR-Bond; and Light Bond, which does not contain CQ, were employed. Labial surfaces of freshly extracted lower bovine incisors were ground with no. 600 grit SiC paper. Dentine primers were applied to the dentine surfaces in two groups, irradiated and non-irradiated. A shear bond strength test was performed and the direct contact angle was measured., Results: Statistical analysis (Newman-Keuls multiple comparison P < 0.05) of the data indicated that light irradiation of the dentine primer for systems containing CQ resulted in increased bond strength and decreased contact angle., Conclusion: This study indicates that for these dentine bonding systems containing CQ in their primers, light irradiation of the dentine primer is effective in improving wettability and increasing the bond strength to dentine.

One hundred fifty-three single rooted teeth were divided into four groups. Canals were cleaned and shaped using the balanced forces technique. In one group of 50 teeth, irrigation was delivered with the irrigation needle deep within the root canal. In the other group of 51 teeth, the needle was placed passively in the coronal access cavity and the irrigation carried into the root canal during filing. The remaining 52 teeth in the control groups were treated in the same manner using distilled water as the irrigation solution. The concentration of sodium extruded apically was measured by means of atomic emission spectrophotometry, and the volume of sodium hypochlorite extruded was calculated. Significantly more sodium hypochlorite was extruded apically during deep delivery of the irrigation (p<0.05). It is concluded that the use of a reservoir of irrigation in the coronal access cavity results in significantly less apical extrusion of irrigation solution than with deep delivery.

A self-setting apatite cement, EBA cement, and amalgam with varnish were tested for root end sealing ability using a fluid filtration and dye technique. Single-rooted human teeth were prepared in vitro to receive root end fillings. Experimental groups were amalgam with two layers of varnish, EBA cement with dry cavity, EBA cement within a wet cavity, apatite cement within a dry cavity, and apatite cement within a wet cavity. Fluid filtration measurements were made at 6, 24, and 7 days, and 1 and 3 months. Each specimen was also subjected to a dye leakage test using Procion Green dye at 3 months. Results indicated that apatite cement provided a comparable seal to amalgam and EBA cement. This finding, in conjunction with its excellent biocompatibility, suggests that apatite cement is an acceptable alternative to present-day root end filling materials.

A finite element model (FEM) of an orthodontic bracket bonded to enamel with glass ionomer cement was developed. The loading on the model simulated tensile loading conditions associated with the testing of bonding system strength. The primary purpose of this project was to ascertain the effects of load misalignment on the calculated stresses within the cement layer. The results indicate that peak stress values increase as the load deflection angulation increases. If the tensile load is inadvertently applied entirely on one wing of the bracket, the stress components nearly double in magnitude.

Two microleakage detection tests were evaluated to compare their capabilities for revealing the extent of leakage at the interface between amalgam restorations and tooth structure. Class V cavities were prepared in the buccal surfaces of extracted human canine and premolar teeth and were treated in one of the following ways: no liner or varnish, a copal varnish, or an adhesive resin liner. The cavities were restored with a high-copper single composition spherical amalgam alloy and the specimens thermally cycled. Following storage for 6 months, the teeth were exposed to separate solutions of 45Ca and an ultraviolet fluorescing dye. The teeth were hemisected longitudinally and leakage was evaluated by determining the degree of penetration of the two tracers at the occlusal and gingival margins. Statistical analysis revealed a significant difference between the two leakage techniques (P less than 0.05). The radioisotope test generally indicated a greater degree of leakage than did the ultraviolet dye test.

The bonding of light-cured composites to tooth tissues is known to be disturbed by polymerization shrinkage, and polymerization shrinkage is affected by the filler content of composites. This in vitro research examined the relationship between the filler content and bond strength to dentine of light-cured composites. Experimental light-cured composite systems with filler contents of 45, 55, 65 and 75 per cent by volume were used in both bond strength to dentine and shrinkage tests. The surfaces selected as substrates were a flat surface and a box-shaped cavity prepared in bovine dentine. The lowest bond strength was obtained with the 45 per cent filler content composite in the box-shaped cavity. Bond strength increased with increasing filler content. Volumetric polymerization shrinkage decreased with increasing filler content. The polymerization shrinkage at 120 s after light curing was 5.24 per cent for the 45 per cent filler content system, 4.77 per cent for the 55 per cent, 2.14 per cent for the 65 per cent and 1.68 per cent for the 75 per cent. The correlation between bond strength and shrinkage was greater for the cavity than it was for the flat surface. This implies that bond strength in the box-shaped cavity may have been affected more by polymerization shrinkage than with the flat surface. The findings lend support to the view that filler content is one of the important factors influencing the physical properties of composites.

Two Type II glass polyalkenoate (ionomer) cements were evaluated for their repairability by measuring tensile bond strength of new material added to previously placed cement. Variables included time of repair (20 min vs. 24 h) and surface condition prior to repair (smooth and unetched, smooth and etched, rough and unetched, rough and etched). Failures were evaluated using light microscopy and categorized as cohesive, adhesive, or mixed. Scanning electron microscopy was employed to view the cement surfaces following each of the four pretreatments. Surface pretreatment was found to significantly affect both materials when repaired at 20 min (P less than 0.05). The highest bond strength was achieved when bonding to the smooth, unetched surface. Surface pretreatment did not significantly affect bond strength when the cements were repaired at 24 h (P greater than 0.05). Tensile bond strengths were greater for repairs made at 20 min than for those made at 24 h, but the differences were not always statistically significant.

One hundred eighty bracket and arch wire combinations of nitinol, beta titanium, and stainless steel were compared as to force (grams) required to overcome a simulated canine retraction assembly. Results showed a significantly larger force required during canine retraction using beta titanium and nitinol when compared with stainless steel.

The acceptance of simplified technical procedures that minimize clinical effort is exemplified by the popularity of direct bonding. This study (1) measured the comparative tensile bond strengths of brackets bonded directly in vitro to both glazed and deglazed porcelains by the use of five adhesive systems, and (2) recorded failure sites. System 1+, Enamelite 500, Isopast/Silanit, and Concise/Scotchprime proved to have strengths that should be acceptable clinically. Ultra-bond produced a bond that was significantly less in strength as compared with the other four systems. There was no significant difference in the bond of glazed and deglazed porcelains. Diamond polishing paste was better at restoring the porcelain surface to original smoothness in comparison with polishing stones. Irreversible damage to the porcelain surface may result from the bonding procedure.

This study was undertaken to assess the effect of mixing speed on the setting rate of high-copper dental amalgam. The surface hardness during setting of two representative brands of dental amalgam was related to working and carving times determined by clinicians. From this information, a means of evaluating setting rate of amalgam based on surface hardness was developed.

Etching or roughening the surface of glass ionomer cement before use of composite resins and bond agents produces bond strengths comparable to the bond strength between glass ionomers and dentin. Bond failure at such surfaces occurs within the glass ionomer. Adequate washing with water after acid etching the glass ionomer is essential to obtain optimal bond strength. Apparently, some combinations of ionomer cements and resins are more effective than are others in providing a good bond in the "sandwich technique".

The in vivo disintegration of luting cements was determined at 6- and 12-month intervals in two test series of 20 participants each. Four cements were inserted in the wells located in the mesial and distal surfaces of cast crowns. Glass ionomer, silicophosphate, polycarboxylate, and zinc phosphate cements prepared with recommended powder/liquid ratios are discussed, and are ranked with respect to disintegration at 6 and 12 months.