Evaluation of bond strength of various margin ceramics to a zirconia ceramic

OBJECTIVE: This study evaluated the bond strengths of four different margin ceramics based on fluoroapatite and feldspath to a zirconia ceramic. METHODS: Zirconia cores (Zirconzahn) (N=28, n=7/margin ceramic group) were fabricated according to the manufacturers' instructions (diameter: 4mm; thickness: 2mm) and ultrasonically cleaned. Four different margin ceramics (thickness: 5mm) (Cerabien Zr, Noritake; Ceramco PFZ, Ceramco; e.max, Ivoclar Vivadent and Triceram, Dentaurum) were vibrated and condensed in a stainless steel mould and fired onto their zirconia cores. After trying the specimens in the mould for minor adjustments, they were again ultrasonically cleaned and embedded in PMMA. The specimens were stored in distilled water at 37 degrees C for 1 week and shear bond strength (MPa+/-S.D.) tests were performed in a universal testing machine (crosshead speed: 0.5mm/min). Failure modes were recorded under SEM. RESULTS: Significant effect of margin ceramic types were found on the bond strength values (P<0.05). The mean bond strength values of Ceramco margin ceramic to zirconia was significantly lower (25.4+/-4.5MPa) (P<0.05) than those of Cerabien (31.6+/-6.4MPa), e.max (35.9+/-8.4MPa), and Triceram margin ceramic (38.8+/-7.1MPa) systems. CONCLUSIONS: Margin ceramics, compatible with zirconia framework material tested in the present study, exhibited high bond strength values. Variations in thermal expansion coefficients might influence their bond strength values.     

Dentin treatment with MMPs inhibitors does not alter bond strengths to caries-affected dentin

OBJECTIVES: This study aimed to investigate if the use of protease inhibitors (EDTA and chlorhexidine) may influence microtensile bond strength (MTBS) of an etch-and-rinse adhesive system to caries-affected human dentin. METHODS: Flat middle coronal dentin surfaces with a central region of caries-affected dentin surrounded by sound dentin were bonded with Adper Scotchbond 1 after: (1) etching with 35% H3PO4; (2) etching with 0.1M EDTA and (3) 35% H3PO4-etching followed by 5% chlorhexidine application. Resin composite build-ups were constructed incrementally and trimmed to yield hourglass specimens (0.8mm2 bonded area) that contained sound or caries-affected dentin (confirmed after debonding by microhardness measurements - KHN). Bonded specimens were tensioned at 0.5mm/min. Data were analyzed by ANOVA and multiple comparisons tests (p<0.05). Failure mode analysis was performed by scanning electron microscopy (SEM). RESULTS: H(3)PO(4), EDTA and chlorhexidine pre-treatments yielded similar MTBS values, in both dentin substrates. Bond strength to sound dentin was significantly higher than that to caries-affected dentin after H3PO4-etching. Caries-affected dentin exhibited lower KHN than sound dentin. CONCLUSIONS: Conditioning of caries-affected dentin with EDTA or a combined use with H3PO4 and chlorhexidine may be proposed as these protease inhibitors do not reduce MTBS to caries-affected dentin if compared to conventional H3PO4 treatment.     

Cellular profile of the peritumoral inflammatory infiltrate in squamous cells carcinoma of oral mucosa: Correlation with the expression of Ki67 and histologic grading

Background  

Squamous cells carcinoma is the most important malignant tumor with primary site in the oral cavity and, given the great exposure of mucosa and lips to the etiologic factors of this neoplasm, its incidence is high. Investigation of the prognostic determinants is significant for the expectations of treatment proposal and cure of the patient. The local immune response represented by peritumoral inflammatory infiltrate is a possible prognostic factor.     

Mandibular reconstruction with bone transport in a patient with osteogenesis imperfecta

Osteogenesis imperfecta (OI) was originally considered a connective tissue disorder, primarily involving type 1 collagen. It is characterized by numerous skeletal and extraskeletal defects, including bone fragility, multiple fractures, blue sclerae, hearing deficits, skin and ligament laxity, and dentinogenesis imperfecta (DI). The authors describe a 24-year-old Japanese man with OI and DI who had an ossifying fibroma of the mandible. Segmental resection was performed, and the mandible was reconstructed by distraction osteogenesis with the transport segment technique. This is the first report to describe a patient with OI undergoing mandibular reconstruction with bone transport, to the authors' knowledge.