Using extracted teeth for research: the effect of storage medium and sterilization on dentin bond strengths

BACKGROUND: The Centers for Disease Control and Prevention has adopted guidelines for infection control of extracted teeth used for research and teaching, requiring that teeth be sterilized before use. The authors conducted a study to test the null hypothesis that the storage medium and sterilization method have no effect on composite-to-dentin bond strengths. MATERIALS AND METHODS: The authors collected 170 bovine incisors, cleaned them and placed them randomly into one of six storage media at 37 degrees C for 60 days: distilled water (dH(2)O), 0.9 percent sodium chloride, 0.5 percent chloramine-T, 5.25 percent sodium hypochlorite (NaClO), 2 percent glutaraldehyde and 10 percent formalin. For sterilization, they autoclaved a subset of 10 specimens from every sample, while they stored another subset of 10 specimens from every sample (except for the 10 percent formalin sample) in 10 percent formalin for 14 days. The authors then embedded the specimens in epoxy and ground flat the facial surface to expose middle-depth dentin, which they polished to 600 grit. They used a dental adhesive to apply composite to the exposed dentin. The authors tested the composite-to-dentin shear bond strength 24 hours after bonding. They analyzed the data using global analysis of variance and, when appropriate, multiple post hoc tests (P = .05). RESULTS: Storage in NaClO resulted in significantly lower bond strength than that of the other treatment specimens. Sterilization with the autoclave negatively affected the bond strength of specimens stored initially in dH(2)O or 10 percent formalin, while sterilization with formalin alone had no significant effect on bond strengths. CONCLUSIONS: Storing bovine teeth in 5.25 percent NaClO may negatively affect composite-to-dentin bond strengths. Immersion in 10 percent formalin might be the best option for storage and sterilization of bovine teeth that are to be used in dental bonding studies in vitro.     

Condensation silicones: do new materials really presents better dimensional stability?

The aim of this study was evaluate the dimensional stability of some condensation silicones. The following materials were studied: Coltex/Coltoflax - Coltène, Speedex - Coltène, and Optosil Comfort/Xantopren VL Plus - Kulzer. They were evaluated by dimensional analysis and gas chromatography (GC) performed at the following times: T0, T1, T2, T3, T4, and T5 (immediately after setting, thirty minutes, two hours, twenty four hours, seventy two hours, and seven days after setting, respectively). The dimensional changes were measured directly in the molds using a Mitutoyo microscope. The Coltex fine/Coltoflax and Optosil Comfort/Xantopren VL Plus materials presented dimensional stability for up to thirty minutes after molding, while the Speedex material remained stable for up to two hours after molding. The gas chromatography experiment demonstrated that these materials release ethanol even after clinical setting.     

Oral events related to low-dose methotrexate in rheumatoid arthritis patients

Low-dose methotrexate (MTX) is frequently used for patients with rheumatoid arthritis (RA). High doses of MTX frequently produce side effects. The aim of this study was to explore oral complications of low-dose MTX therapy in a population of RA patients. This is a cross-sectional study in which oral examination was performed on a population of RA patients. Patients undergoing MTX therapy (5-20 mg weekly) for at least six months were included in the study group, and RA patients being treated under another regimen were used as controls. The frequency of oral lesions was compared between groups. The chi-square test was used to compare frequencies. Relative risk (RR) and its confidence interval (CI) were established. Significance level was set at 0.05. Twenty-eight RA patients on a low-dose MTX regimen and 21 controls were enrolled in the study. Oral lesions were found in 22 patients (78.6%) undergoing MTX therapy, and in 5 patients (23.8%) undergoing other therapies (p < 0.001). There were no significant differences regarding age, gender or dosage. The most common oral events observed in patients in the MTX group were ulcerative/erosive lesions (60.7%) and candidiasis (10.7%). Patients in the control group presented lower prevalence of the same lesions (p < 0.001). The RR for developing oral lesions was 11.73 (CI 2.57 - 58.98), with low-dose MTX therapy. In conclusion, the prevalence of oral mucosa lesions in RA patients receiving low doses of MTX therapy is higher than in RA patients not receiving the drug.     

In vitro evaluation of frictional forces between archwires and ceramic brackets.

The aim of this study was to evaluate the frictional force between orthodontic brackets and archwires. The differences in magnitude of the frictional forces generated by ceramic brackets, ceramic brackets with metal reinforced slot, and stainless steel brackets in combination with stainless steel, nickel-titanium, and beta-titanium orthodontic archwires were investigated. Brackets and wire were tested with tip angulations of 0 degrees and 10 degrees. Friction testing was done with the Emic DL 10000 testing machine (S?o José do Rio Preto, PR, Brazil), and the wires were pulled from the slot brackets with a speed of 0.5 cm/min for 2 minutes. The ligation force between the bracket and the wire was 200 g. According to the data obtained, the brackets had frictional force values that were statistically significant in this progressive order: stainless steel bracket, ceramic bracket with a metal reinforced slot, and traditional ceramic bracket with a ceramic slot. The beta-titanium wire showed the highest statistically significant frictional force value, followed by the nickel-titanium and the stainless steel archwires, in decreasing order. The frictional force values were directly proportional to the angulation increase between the bracket and the wire.     

Esthetic alternative for fluorosis blemishes with the usage of a dual bleaching system based on hydrogen peroxide at 35%

Esthetic dental procedures in pediatric dentistry represent sources of satisfaction and realization, as much for the patient as for the professional. Lack of dental esthetics may develop psychological problems in infant as well as in adolescent patients. Blemishes produced by fluorosis appear as a challenge to the pediatric dentist and alternatives for treatment are desired. The scope of this present paper is to relate a clinical case with esthetic solution for blemishes in teeth enamel due to fluorosis. A dual system of bleaching was used (photo/chemically activated) based on hydrogen peroxide at 35% (Hi-Lite-Shofu) in a male eight-year-old patient with white fluorosis blemishes on teeth 11 and 21. The bleaching system used was efficient in bleaching teeth with white blemishes due to fluorosis, thus masking the blemishes and providing a more uniform appearance.     

Evaluation of oral and nasal odor in patients with and without cleft lip and palate: preliminary report.

OBJECTIVE: To evaluate oral and nasal halitosis parameters in patients with and without clefts. DESIGN: Randomized and prospective study. Patients with and without clefts were evaluated as to oral and nasal halitosis. SETTING: University of S?o Paulo, Bauru Dental School and Hospital for Rehabilitation of Craniofacial Anomalies, Bauru, Brazil. PATIENTS: Twelve patients with clefts and 12 without clefts were evaluated, and no exclusion criteria were followed. INTERVENTIONS: Nasal and oral halitosis were measured with the use of a portable sulfide monitor during a single visit. RESULTS: One hundred percent of the patients with clefts had altered values for volatile sulfur compounds. Only 33.3% of the patients without clefts had at least one strong value for nasal halimeter measurements, and 58.3% of these patients showed alteration in the nasal values. Statistical evaluation, made using the Mann-Whitney U test, classifying the nasal halimeter values as normal, weak, and strong, showing a statistical significant group difference (p = .003). There was no significant difference in the oral halimeter values between the two groups. CONCLUSIONS: Patients with cleft lip and palate had a tendency to present higher values for the nasal halimeter measurements, when compared with patients without clefts.