Bovine Incisors (bovine + incisor)

Distribution by Scientific Domains

Selected Abstracts

Effect of Light-Curing Method and Cement Activation Mode on Resin Cement Knoop Hardness

Rubens Nisie Tango
Purpose: To evaluate the Knoop hardness (KHN) of the resin cement Enforce activated by chemical/physical mode or physical mode solely; light-cured directly or through a 1.5 mm thick ceramic disc (HeraCeram) on shade DD2. Materials and Methods: Light-curing was carried out using a conventional quartz tungsten halogen light (QTH) (XL2500) for 40 seconds at 700 mW/cm2; light-emitting diodes (LED) (Ultrablue Is) for 40 seconds at 440 mW/cm2; and Xenon plasma arc (PAC) (Apollo 95E) for 3 seconds at 1600 mW/cm2. Bovine incisors had their buccal faces flattened and hybridized. A mold was seated on these surfaces and filled with cement. A disc of the acid-etched and silanized veneering material was seated over this set for light-curing. After dry storage (24 hours at 37C), specimens (n= 10) were sectioned for KHN measurements performed in a microhardness tester (50 gf load for 15 seconds). Data were submitted to ANOVA and Tukey's test (,= 0.05). Results: The highest KHN values were obtained with LED, for both dual-cured and light-cured cement. The lowest KHN value was obtained with light-cured PAC. Light-curing with QTH resulted in hardness values similar to PAC in dual-cured groups. Conclusions: Light-curing through HeraCeram can influence resin cement hardness. [source]

Determination of elastic modulus of demineralized resin-infiltrated dentin by self-etch adhesives

Genta Yasuda
The purpose of this study was to determine ultrasonically the changes in elastic modulus of demineralized adhesive-infiltrated dentin. Dentin disks were obtained from bovine incisors and shaped into a rectangular form. The specimens were immersed in single-step self-etch adhesives, then stored in distilled water and run through thermal cycles between 5 and 60C. The longitudinal and shear wave sound velocities and the elastic modulus were determined using ultrasonic equipment composed of a pulser-receiver, transducers, and an oscilloscope. After 24 h of storage, the elastic modulus of mineralized dentin was 16.9 GPa and that of demineralized dentin was 2.1 GPa. The immersion of demineralized dentin in adhesives significantly increased the elastic modulus to 3.3,5.9 GPa. After 30,000 thermal cycles, the elastic modulus of dentin was 32.4 GPa, whereas that of demineralized adhesive infiltrated dentin was 3.1,4.1 GPa. Thermal stresses did not cause adhesive-infiltrated demineralized dentin to deteriorate, as measured by elastic modulus. [source]

Fracture strength of bovine incisors after intra-radicular treatment with MTA in an experimental immature tooth model

E. A. Bortoluzzi
Abstract Aim, To evaluate, using an experimental immature tooth model, the fracture resistance of bovine incisors submitted to different reinforcement treatments with mineral trioxide aggregate (MTA). Methodology, An immature tooth model was created by sectioning the coronal and apical portions of 40 bovine incisors 8 mm above and 12 mm below the cementoenamel junction. The root canals were irrigated with 1.0% sodium hypochlorite. They were enlarged both coronally and apically using number 703 carbide burs (ISO: 500,104-168-007-021) and their internal diameter was standardized to 2.1 mm. The specimens were assigned to four groups (n = 10): GI-control (without filling); GII-apical MTA plug + filling with gutta-percha and endodontic sealer; GIII-filling with MTA; GIV-apical MTA plug + filling with MTA + metallic post (Reforpost I). A polyether impression material was used to simulate the periodontal ligament. The specimens were submitted to a compressive load at a crosshead speed of 0.5 mm min,1 in a servo-hydraulic universal testing machine (MTS 810) applied at 45 to the long axis of the tooth until failure. Data were submitted to statistical analysis by the Kruskal,Wallis test at 5% significance level. Results, GIV presented the highest fracture resistance (32.7N) and differed significantly from the other groups (P < 0.05). No statistically difference was found between GII (16.6N) and GIII (23.4N) (P > 0.05). GIII had a significantly higher fracture resistance than GI (P < 0.05). Conclusions, The use of MTA + metallic post as an intra-radicular reinforcement treatment increased the resistance to fracture of weakened bovine teeth in an experimental immature tooth model. [source]

Microtensile Bond Strength of Luting Materials to Coronal and Root Dentin

ABSTRACT Purpose:: The purpose of this study was to evaluate the microtensile bond strength (,TBS) of two dual-cured resin cements and a glass ionomer cement to coronal dentin versus root dentin. Materials and Methods: RelyX Unicem (3M ESPE, St. Paul, MN, USA) and Panavia F (Kuraray Medical Inc., Tokyo, Japan) were the resin cements used and FujiCEM (GC Corp., Tokyo, Japan) was the glass ionomer cement used. Once separated, the labial coronal and root surfaces of six bovine incisors were ground with 600-grit SiC papers to expose middle dentin. Then, the dentin surfaces were treated following the manufacturers'instructions and a 1 mm thick layer of each material was applied to the flattened coronal and root surfaces. Each material was cured following the manufacturers'recommendations and a composite buildup was made over the cured luting materials for testing purposes. After 24 hours in water at 37C, the teeth were sectioned into 1 mm 1 mm 6 mm beams and tested for ,TBS. The data were analyzed by one- and two-way analysis of variance and Fisher's Protected Least Squares Differences test (p < .05). Results: The ,TBSs to coronal and root dentin were similar within each cement. Comparing the materials, RelyX Unicem presented the highest ,TBS, followed by Panavia F and FujiCEM, respectively (p < .0001). Conclusions: Although there were differences in ,TBS among the materials tested, no significant differences were found between bond strengths to coronal and root substrates. [source]

Microradiographic study on the effects of salivary proteins on in vitro demineralization of bovine enamel

summary, The aim of this investigation was to evaluate the effects of various proteins on in vitro demineralization of bovine enamel. From each of 100 bovine incisors two samples were prepared. The specimens were embedded in epoxy resin and polished up to 4000 grit. Subsequently, the specimens' surfaces were partly covered with nail varnish, thus serving as control of sound enamel. The specimens were divided randomly into five groups (n = 40) and demineralized in a solution of constant composition (pH 50; 10 days). For each subgroup of specimens (n = 10) 4 L were taken and either low (50% of medium conc.), medium, or high (150%) concentrations of the proteins [human albumin (100% conc. = 7 mg L,1), mucin (5775 mg L,1), immunoglobulin G (IgG) (46 mg L,1), casein isolated from bovine milk (12 g L,1)] or amino acid [l -Proline (7 mg L,1)] were added to 1 L of the demineralizing solution, whereas 1 L served as control. Mineral loss and lesion depth (LD) were evaluated from microradiographs of thin sections (110 ,m) by a dedicated software package (TMR 1.24). No differences were found between the five control groups (P > 005; anova). Albumin, l -Proline, and IgG did not affect enamel demineralization, whereas the addition of both casein and mucin resulted in significant reductions of both mineral loss and LDs (P < 001; Tukey's test). Within the limitations of an in vitro study, the present investigation indicates that casein and mucin seem to affect enamel demineralization significantly. Thus, these proteins might be helpful as an additive to saliva substitutes or mouthwashes if the quality of saliva is altered. [source]

Impact of modified acidic soft drinks on enamel erosion

ORAL DISEASES, Issue 1 2005
T Attin
Objective:, To evaluate the enamel erosive potential of modified acidic soft drinks under controlled conditions in an artificial mouth. Materials and methods:, From each of 144 bovine incisors one enamel sample was prepared. Labial surfaces of the samples were ground flat, polished and covered with adhesive tape, leaving an exposed area. The samples were distributed among four (A,D) groups for treatment with A: Coca-Cola, B: Sprite; C: Sprite light, D: orange juice. Either 1.0 mmol l,1 calcium (Ca) or a combination (comb.) of 0.5 mmol l,1 calcium plus 0.5 mmol l,1 phosphate plus 0.031 mmol l,1 fluoride was added to the beverages. Samples of each group were subdivided into three subgroups (-original; -Ca and -comb.) for treatment with original and modified drinks. De- and remineralization cycles were based on a standard protocol described earlier. Surface loss of the specimens was determined using profilometry after test procedure. Results:, In all subgroups, loss of enamel was observed. The enamel loss recorded for the samples rinsed with original Sprite and original orange juice was significantly higher compared with all other solutions (P = 0.001). Lowest enamel loss was recorded for the original Coca-Cola group (P = 0.001). With the exception of Coca-Cola, demineralization with the modified beverages led to significantly lower losses compared with the respective original solutions. Conclusion:, Modification of the test soft drinks with low concentrations of calcium or a combination of calcium, phosphate and fluoride may exert a significant protective potential with respect to dental erosion. [source]