ABSTRACT
AIM: To evaluate the effect of unidirectional or woven glass fibre tapes inserted into MOD cavity preparations on the fracture resistance of root filled molar teeth. METHODOLOGY: Extracted human molar teeth were randomly divided into six groups (n = 15) : G1 - sound teeth, control; G2 - MOD cavity preparation; G3 - MOD + root canal treatment (Endo); G4 - MOD + Endo + composite resin restoration (Resin); G5 - MOD + Endo + unidirectional fibre (UF) + Resin; G6 - MOD + ;Endo + woven fibre (WF) + Resin. The teeth were subjected to a compressive fracture test in a universal testing machine. After testing, two failure modes were classified: pulp chamber floor or cusp. RESULTS: The highest and the lowest mean fracture strengths were found in sound teeth (G1) (4960N) and MOD + root canal treatment (G3) (612.84N), respectively, with significant differences from the other groups (P < 0.05). The remaining groups had statistically similar means. In G5 and G6, there was a tendency for fracture to occur in the pulp chamber floor compromising tooth integrity. CONCLUSIONS: The insertion of glass fibres into MOD cavity preparations and restoring them with composite resin was not different than molar teeth filled with composite resin only in terms of fracture resistance. Fibres placed into MOD cavities do not reinforce teeth.
Subject(s)
Dental Materials/chemistry , Dental Restoration, Permanent/methods , Glass/chemistry , Molar/pathology , Root Canal Therapy/methods , Tooth Fractures/physiopathology , Tooth, Nonvital/therapy , Acid Etching, Dental , Bisphenol A-Glycidyl Methacrylate/chemistry , Composite Resins/chemistry , Compressive Strength , Dental Cavity Preparation/methods , Dental Enamel/injuries , Dental Pulp Cavity/injuries , Dental Stress Analysis/instrumentation , Glass Ionomer Cements/chemistry , Gutta-Percha/therapeutic use , Humans , Maleates/chemistry , Materials Testing , Molar/injuries , Root Canal Filling Materials/therapeutic use , Stress, MechanicalABSTRACT
AIM: The aim of this study was to evaluate the longitudinal effect of chemical disinfection on Shore A hardness, surface roughness (Ra) and morphology of two tissue conditioners (Dura Conditioner [DC] and Softone [SO]). METHODS: Twenty-four specimens (2 mm-thick) were made of each material and randomly divided into three groups (N.=8): control (no disinfection), 10 000 ppm chloride solution (sodium hypochlorite) and Corega Tabs solution (peroxide solution). Soaking was performed daily for 15 min, and Shore A hardness and Ra were measured at baseline and 3, 7, 10, and 14 days. Data were analyzed by repeated measures ANOVA and Bonferroni's test (alfa= 0.05). RESULTS: Chemical disinfection for 14 days with sodium hypochlorite and Corega Tabs affected differently the tested materials. Hardness varied from 8 to 20 for DC and from 8 to 23 for SO with significant interaction (P<0.05) between material and disinfection treatment up to day 7. Ra values (in microm) varied from 1.51 to 4.35 for DC and from 2.08 to 4.15 for SO; there was a significant difference between disinfection treatments (P=0.043) but not between materials (P=0.119). Sodium hypochlorite groups displayed smaller Ra values than the control groups, but did not differ from Corega Tabs groups. Scanning electron microscopy showed different pattern of degradation for each material. CONCLUSIONS: The results suggest that the effect of chemical disinfection on degradation of tissue conditioners is material-specific, but hardness is less affected than surface topography. The overall results support the use of the tested materials for up to three days, independently from the disinfection treatment.
Subject(s)
Denture Cleansers/pharmacology , Denture Liners , Disinfectants/pharmacology , Disinfection , Hardness/drug effects , Polymethacrylic Acids/pharmacology , Polymethyl Methacrylate/pharmacology , Sodium Hypochlorite/pharmacology , Surface Properties/drug effects , Viscoelastic Substances , Hardness Tests , Materials Testing , Microscopy, Electron, Scanning , Random Allocation , Time FactorsABSTRACT
AIM: The purpose of this study is to evaluate and compare the Vickers microhardness of one microhybrid composite polymerized with different sources and stored in different solutions for up to 14 days. METHODS: Using a bipartite PTFE mould with 6 mm inner diameter and 3 mm high, 30 samples were manufactured with Charisma B1 shade for each polymerization procedures (halogen light, LED and halogen light and postcure cycles) stored in tree types of storage solution. RESULTS: The postcuring method tended to improve the microhardness, but was not statistically different from halogen or LED curing methods (P>0.05). The storage solutions interfered in surface hardness, with the samples eluted in red wine showing the lowest hardness values (P<0.05). After seven days, the hardness values were higher than the first day, but statistically equal to 14 days (P<0.05). CONCLUSION: On accordance with the findings of this study, different storage solutions can change the surface microhardness of a composite resin. An alcoholic solution seems most harmful to the composite. Samples postcured in autoclave had an improved mean value, however, without differing from those of the LED and halogen photo polymerized specimens.