The effect of different reinforcements on the fracture toughness of materials for interim restorations

STATEMENT OF PROBLEM. Fracture of an interim fixed partial denture (FPD) may jeopardize the success of the interim prosthodontic treatment phase and cause patient discomfort. PURPOSE. The purpose of this study was to compare the fracture toughness of a polymethyl methacrylate (PMMA) resin and a bis-acryl composite (BAC) resin reinforced with stainless steel wire, glass, and polyethylene fiber. MATERIAL AND METHODS. Four groups (n=13) of each of the 2 materials were prepared for the single-edge 3-point-bending test. Three groups had the different reinforcements, and the group without reinforcement served as control. Using a universal testing machine, peak load to fracture was recorded and fracture toughness (KIC) was calculated in MNm-1.5. Median KIC values were compared by means of nonparametric ANOVA (Kruskal-Wallis test, α=.05). RESULTs. For the controls, the fracture toughness for PMMA resin (KIC=27.9) was significantly lower (P.10, for BAC resin and KIC=25.8, P>.10, for PMMA resin). There was no significant difference between the fracture toughness of the wire and glass fiber reinforcements for both interim materials (P>.10 in both instances). CONCLUSIONS. Of the 3 reinforcement methods evaluated, wire and glass fiber reinforced the PMMA and BAC resin materials best.Web of Scienc

Insights into chitosan hydrogels on dentine bond strength and cytotoxicity

Contemporary dental adhesives show favorable im- mediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. Materials and Methods: Preparation of 3 chitosan-antioxidant hydrogels was achieved us- ing modified hydrogel preparation method. Their effect on the bond strength to dentine both short term (after 24 hours) and long term (after 6 months) were evaluated using shear bond strength measurements using Instron Universal Testing Mascine). The SEM was used to study the surface of the hydrogels. The cell survival rate (cytotoxicity) of the antioxidants re- sveratrol, β-carotene and propolis towards Balb/c 3T3 mouse fibroblast cells was also assessed using the standard MTT assay. Results: It was found that chi- tosan-H treated dentine gives significantly (p propolis (68%) > resveratrol (33%). Conclusion: the antioxidant-chitosan hydro- gels significantly improved bonding to dentine with or without phosphoric acid treatment. The pH of the growth medium had a high influence on the cell survival rate of Balb/c mouse 3T3 fibroblast cells. The release of the antioxidant β-carotene would not have an influence on the pulp cells. These materials might address the current perspectives for improving bond durability.DDF fund of the South African Dental Association; School of Dentistry and Oral Health, Griffith UniversityWeb of Scienc

n In vitro en in vivo studie van mikrolekkasies by tande wat met verskillende amalgaambindingsisteme herstel is

One copy microfiche.Thesis (M. Sc.) -- University of Stellenbosch, 1997.Full text to be digitised and attached to bibliographic record

Genital herpes zoster as a consequence of cancer chemotherapy-induced immunosuppression: report of a case

Herpes zoster (HZ) is a clinical manifestation of the reactivation of the varicella zoster virus (VZV). HZ of the male genital area is a rarely reported condition. The exact mechanism of latency and reactivation of VZV in these patients is unknown. The incidence of HZ can be associated with various conditions such as malignancies, immune deficiencies, autoimmune diseases, psychological conditions, and human immunodeficiency infection or HIV disease. In this report, we describe a rare case of HZ on male genitalia following the administration of immunosuppressant drugs for bowel cancer. The patient developed classical features of HZ during chemotherapy, 2 years after the initial chemotherapy for his bowel cancer. The ulcers of HZ lesions were treated with chlorhexidine (Curasept) ointment to prevent secondary bacterial infection. All the lesions subsided gradually and in 2 weeks with no later symptoms or pain. Genitalia are an unusual site of eruption in HZ. Patients with malignancy and iatrogenic immunodeficiency have an increased risk of reactivation of VZV and development of HZ

Effect of four over-the-counter tooth-whitening products on enamel microhardness

OBJECTIVES: This in vitro study evaluated the effect of four over-the-counter tooth-whitening products on enamel microhardness. METHODS: Fifty enamel blocks were prepared from extracted human molar teeth. The enamel surfaces were polished up to 1200 grit fineness and the specimens randomly divided into five groups. Enamel blocks were exposed to: Rapid White (n=10); Absolute White (n=10); Speed White (n=10) and White Glo (n=10) whitening products, according to the manufacturers' instructions. As control, ten enamel blocks were kept in artificial saliva at 37 degrees C without any treatment. Microhardness values were obtained before exposure (baseline) and after 1, 7 and 14-day treatment periods using a digital hardness tester with a Vickers diamond indenter. Data were analysed using Wilcoxon Signed Rank Sum Test, one-way ANOVA and Tukey-Kramer Multiple Comparison Test (p<0.05). RESULTS: Both Rapid White and Absolute White reduced enamel microhardness. Speed White increased the microhardness of enamel, while White Glo and artificial saliva had no effect on hardness. CONCLUSIONS: Over-the-counter tooth-whitening products might decrease enamel microhardness depending on the type of product.Department of HE and Training approved lis