An in vitro evaluation of the contents of root canals obturated with gutta percha and AH-26 sealer or Resilon and Epiphany sealer

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).     

Processed bovine dentine as a bone substitute

OBJECTIVES: Different forms of allogenic dentine have been studied for their potential use as bone substitutes. We report a new method for processing bovine dentine that results in a sterile bioactive material for repair and regeneration of bone. METHODS: Extracted bovine dentine was processed mechanically and chemically with inorganic and organic solvents, and sterilised. The in vitro biocompatibility on human gingival fibroblasts was assessed by the Alamar Blue assay and the in vivo biocompatibility evaluated by implantation of the processed dentine into rats' femurs. RESULTS: The dentine showed excellent biocompatibility in vitro, stimulated formation of new bone and was completely incorporated into the new bone in vivo. SIGNIFICANCE: Processed bovine dentine has the potential to be used as a suitable substitute in bone repair and regeneration.     

The effects of viscoelastic parameters on residual stress development in a zirconia/glass bilayer dental ceramic.

OBJECTIVES: The aim of this study was to test the hypothesis that the residual stresses in a zirconia-based bilayer dental composite system can be tailored through heat treatment above and below the glass transition temperature of glass veneers. METHODS: Ceramic bilayer disc specimens were prepared from a zirconia core and a glass veneer. Each bilayer ceramic group was heat treated 40 degrees C below, 20 degrees C and 40 degrees C above and at the glass transition temperature of the glass veneer, and cooled using a fast or a slow cooling rate. Specimens were tested for flexure strength using a biaxial bending fixture. Residual stresses were calculated using a fracture mechanics approach. RESULTS: Heat treatments produced significant differences (p < or =0.05) between the mean flexural strengths of the heat treatment groups when the specimens were cooled using a fast cooling rate. However, there was not a significant difference (p >0.05) between the mean flexural strengths of the heat treatment groups when a slow cooling rate was used. Fractures initiated from the veneer surfaces of the specimens. SIGNIFICANCE: Heat treatment above and below the glass transition temperature of the veneer layer, and the cooling rate have a significant effect on the flexural strength of the bilayer ceramic laminates. The existence of residual compressive stress is the most likely reason for the observed strength increases. Residual stresses can be modified using the elastic-viscoelastic relaxation behavior of a glass veneer.     

Myositis ossificans traumatica of the masseter muscle: Review of the literature and report of two additional cases

Myositis ossificans traumatica of the masseter muscle is uncommon. The condition is benign and results in reactive heterotopic bone formation, usually producing limitation of opening of the jaws. Radiographic and microscopic examination can confirm the diagnosis. Treatment of myositis ossificans traumatica of the masseter muscle is surgical, with other modalities used when occurring in other muscles of the body     

Smoking and Oral Health: a Population Survey in Finland

Objectives: A survey was conducted to study smokers' oral health behaviors and attitudes, and to determine if smokers were advised by their dentists to quit smoking. Methods : A random sample of 1,200 adults 15 to 64 years of age living in the province of North Karelia, Finland, was selected in each of two study years (1990 and 1991) and surveyed using a mail questionnaire. The 102-item questionnaire solicited information on smoking status, oral health behaviors, missing teeth, perceptions of tobacco's harmful effects on oral health, smoking status and quitting, and advice on smoking cessation provided by dentists. Variations in behaviors and opinions according to smoking status were analyzed. Results : Nonsmokers reported more frequent healthy oral health behaviors than did daily smokers, with the exception that no difference in toothbrushing frequencies existed among women. Daily smoking was associated with increased use of sugar in tea or coffee, and with more frequent alcohol consumption. Daily smoking was correlated with the number of missing teeth in bivariate analyses, but not in multivariate analyses. Fewer daily smokers than nonsmokers considered smoking to have harmful effects on oral health. The majority of daily smokers, however, wanted to quit. Eight percent of daily smokers reported that they had been advised by their dentist to quit. Conclusions : Dentists need to provide patients with counseling on tobacco use because of the desire of many smokers to quit. Counseling of smokers by the oral health team requires special attention and skills, because smokers' health behaviors and attitudes appear to be less favorable to oral health compared to nonsmokers.