Stickiness prior to setting of some light cured resin-composites.

OBJECTIVES: To describe and evaluate a method for deriving a laboratory measure of stickiness, and to compare a set of dental resin-composites by this procedure. MATERIALS AND METHODS: Twelve commercial resin composites were selected. Each material was placed in a cylindrical mold (phi=6.1 x 2.2 mm(2) depth) held either at 23 or at 37 degrees C. A flat-ended stainless-steel instrument was placed onto the surface of the unset sample with a force 350 g. After 2s it was moved vertically at 2 cm/s. This caused a sticky composite to be elevated to a maximum height between 0.2 and 1.8 mm until detachment from the instrument occurred. The elevated material was immediately solidified by light curing at 600 mW/cm(2) for 40s. These elevated profiles were mapped for both height and projected area of elevation. An instrument was constructed for this purpose in our laboratories. Both the projected heights and areas were evaluated as potential measures of stickiness. One-way ANOVA and Duncan's multiple range test were used for statistical analysis. RESULTS: Projected heights ranged from 0.2 to 1.8 mm and projected areas of elevation ranged from 4.0 to 23.9 mm(2). The greatest values were found for microfine anterior composites (Silux plus, Filtek A110). There was a significant difference (p<0.05) between the material (SX) with the highest stickiness and all of the others. The set of profile height and area values were found to be strongly correlated (r(2)=0.9600). SIGNIFICANCE: Once inserted and the load removed, the ideal material stays in place. This is generally assisted by an increase in viscosity and a decrease in stickiness. The stickiness test described is original and may prove to be useful as a standard test method for characterizing the handling stickiness of resin composite materials.     

Periodontal pathogen detection in gingiva/tooth and tongue flora samples from 18‐ to 48‐month‐old children and periodontal status of their mothers

Few studies have detected periodontal pathogens in young children, and when detected the prevalence has been relatively low. In this epidemiological study, we determined the prevalence of periodontal pathogen colonization in young children and examined the relationship between periodontitis in mothers and detection of periodontal pathogens in their children aged 18–48 months. Children were selected and enrolled randomly into the study; tongue and gingival/tooth plaque samples were harvested and analyzed by DNA probe checkerboard assay for Porphyromonas gingivalis and Bacteroides forsythus. Clinical measurements included a gingival bleeding score in the children and a periodontal screening and recording (PSR) score in the mothers. Mothers having one or more periodontal sites with probing depths > 5.5 mm were classified as having periodontitis. In this population, 71% (66/93) of the 18‐ to 48‐month‐old children were infected with at least one periodontal pathogen. Detection rates for children were 68.8% for P. gingivalis and 29.0% for B. forsythus. About 13.8% (11/80) of children had gingival bleeding in response to a toothpick inserted interproximally. Children in whom B. forsythus was detected were about 6 times more likely to have gingival bleeding than other children. There was no relationship between bleeding and detection of P. gingivalis. 17.0% (16/94) of the mothers had periodontitis. When all mother–child pairs were considered, the periodontal status of the mother was found not to be a determinant for detection of periodontal pathogens in the floral samples from the children. However, the odds ratio that a daughter of a mother with periodontitis would be colonized was 5.2 for B. forsythus. A much higher proportion of children in this population were colonized by P. gingivalis and/or B. forsythus than has been previously reported for other populations. A modest level of association between manifestations of periodontitis in mothers and detection of B. forsythus in their daughters was observed.     

Digital subtraction arthrography and arthrofluoroscopic dynamic observations on TMJ dysfunction syndrome

Digital subtraction arthrography and arthrofluoroscopic dynamic observation were performed for seventy cases with TMJ dysfunction syndrome. A comparative study between the findings of digital subtraction arthrography and the operative findings was carried out for eleven cases who underwent surgery. It has been found that digital subtraction arthrography can overcome the disadvantages of conventional arthrography and has important diagnostic value for TMJ dysfunction syndrome, especially for disc perforation. In addition. The procedure of digital subtraction arthrography, the normal and abnormal manifestations of digital subtraction arthrograms were described in the present study.     

The treatment of bisphosphonate-associated osteonecrosis of the jaws with bone resection and autologous platelet-derived growth factors

BACKGROUND: Bisphosphonates administered intravenously are used to treat patients with cancer who have hypercalcemia associated with malignant disease, multiple myeloma or metastatic tumors (breast, lung, prostate) in the bones. Bisphosphonates are bone resorption inhibitors and have been associated with osteonecrosis of the jaws. In this article, the authors provide an alternative treatment modality for refractory bisphosphonate-associated osteonecrosis (BON). CASE DESCRIPTION: The authors treated 12 patients with refractory BON and a history of long-term bisphosphonate therapy. Each patient had mucosal ulceration with exposed necrotic bone. The treatment combined bone resection with platelet-derived growth factors (PDGFs). The surgical intervention they used was a marginal resection limited to the alveolar bone. Ten of the patients recovered with complete mucosal and bone healing. CONCLUSION: BON has been shown to be refractory to antibiotics, minor local débridement and 0.12 percent chlorhexidine oral rinse. Treatment of refractory BON with a combination of marginal resection and PDGF has shown favorable results, including complete wound healing in most patients. This modality has been shown to be effective in treating BON and may be a useful alternative to existing treatment strategies.     

The effect of casting procedures on rotational misfit in castable abutments

PURPOSE: Misfit of implant components has been linked to restorative complications such as screw loosening. Although previous studies have shown a correlation between rotational misfit and screw loosening, the impact of casting procedures on rotational misfit is lacking. The aim of this in vitro study was to evaluate the effect of casting procedures on rotational misfit of cast abutments when compared to machined titanium abutments. MATERIALS AND METHODS: Forty-eight external hexagonal implants and 48 abutments were placed in 4 groups of 12 samples each: (1) machined titanium abutments, (2) premachined palladium abutments cast-on with palladium, (3) plastic burnout abutments cast with nickel chromium, and (4) plastic burnout abutments cast with cobalt chromium. Rotational misfit between the external hexagon of the implant and the internal hexagon of the abutment was measured using standardized techniques and recorded in degrees. Mean values for each group were analyzed with analysis of variance and Tukey test. RESULTS: The mean rotational misfit was 1.21 +/- 0.57 degrees for machined titanium abutments, 1.77 +/- 130 degrees for cast-on abutments, 1.98 +/- 0.72 degrees for cast NiCr abutments, and 2.79 +/- 1.13 degrees for cast CoCr abutments. Significantly greater rotational misfit was recorded with cast CoCr abutments when compared to machined titanium abutments (P < .05). CONCLUSION: Rotational misfit was less than 2 degrees for all groups except for cast CoCr abutments, which demonstrated a significantly greater rotational misfit.     

The effect of ketoprofen creams on periodontal disease in rhesus monkeys

Ketoprofen creams were evaluated for the treatment of periodontal disease in a placebo-controlled, double-blind study in the rhesus monkeys, Macaca mulatta. Two formulations containing ketoprofen (1%), with or without vitamin E, were evaluated against appropriate controls (8 monkeys per group). Two weeks prior to treatment, the animals received prophylaxis on only the left side of the mouth (spontaneous model). Selected teeth on the right side of the mouth were ligated (ligature model). The creams were administered to the gingiva once daily at a standard dose of 1.8 ml per monkey for 6 months. Clinical assessments were made 2 wk before initiation, at baseline and 1, 2, 3 and 6 months post-treatment. The clinical parameters included plaque formation, gingival redness, edema, bleeding on probing and Ramfjord Attachment Level measurements (RAL). Radiographs were taken at 2 wk before initiation, baseline and at 3 and 6 months post-treatment. Digital subtraction radiography was used to measure vertical linear bone loss along the interproximal root surfaces of the left and right mandibular first molars. Gingival crevicular fluid (GCF) was collected for biochemical assays on PGE₂, TxB₂, LTB₄, IL-1β and TNFα. There were no significant differences among groups with respect to gingival indices. Radiographic data demonstrated significant positive effects on bone activity in both groups treated with ketoprofen formulations with improvement over time in the ligature model (0.01 ≤p≤ 0.04). The placebo group exhibited bone loss of 1.96±0.48 and 1.40±0.56 mm per site at 3 and 6 months, respectively. The group treated with ketoprofen cream showed an apparent bone gain of 0.28±0.41 and 0.78±0.47 mm per site at 3 and 6 months, respectively. The group treated with ketoprofen cream containing vitamin E showed a mean bone loss of 0.41–0.48 mm per site at 3 months with improvement to an apparent bone gain of 0.31±0.44 mm per site at 6 months. The biochemical data demonstrated early and significant suppression of GCF-LTB₄ by both ketoprofen formulations at 1 month, which preceded the significant suppression of GCF-PGE₂ at 2 and 3 months in the ligature model (p≤0.003) and at 2 to 6 months in the spontaneous model (p≤0.02). We conclude that ketoprofen at 1% level in suitable topical vehicles can effectively inhibit GCF-LTB₄ and GCF-PGE₂ and positively alter alveolar bone activity in the ligature-induced model of periodontitis in the monkey.     

Measurement of proteases in human subgingival dental plaque by fluorescence polarization

Fluorescence polarization (FP) was examined as a rapid quantitative method to assay the proteases in subgingival plaque. Protease activity was measured by a decrease in FP at 0.5-min intervals over 5 min, using BODIPY®--casein, a protein substrate. To quantitate activity, the least absolute deviation (LAD) slope for each assay was determined. Protease activity increased with the quantity of plaque (r=0.416, P<0.001). Of the 208 subgingival plaque samples, 87 contained detectable protease activity, with a mean of about 4 μg trypsin equivalents above a general background of 1 μg per site. The mean plaque protease activity of 89 paired samples from 15 individuals had decreased by 1.1 μg trypsin equivalents per site when measured at 8 months after tooth scaling and root planing (P<0.01). Most isolates of Porphyromonas gingivalis, Treponema denticola, Prevotella nigrescens, and Prevotella intermedia implicated in the pathogenesis of adult periodontitis exhibited high activity in the FP assay. The assay is rapid, quantitative and requires only one-tenth of the plaque sampled using a single pass with a Gracey curette at a single tooth site.