RESUMEN
OBJECTIVE: To investigate the interface bond and thermal compatibility between Mark II machining ceramic and Vita VM9 veneering porcelain. METHODS: A bar shaped specimen (30 mm x 15 mm x 1 mm in size) of Mark II block was prepared, with 0.5 mm-deep notch (vertical to the long axis of specimen) at the middle of the bottom surface. The upper surface was veneered with 0.3 mm VM9 dentin base porcelain. Then the specimen was fractured from the notching site and the fracture surface was examined under scanning electron microscope (SEM) and electron microprobe analyzer (EMPA) with electron beam of 1 microm in diameter. Another ten specimens (30 mm x 15 mm x 1.5 mm in size) were fabricated and the temperature of thermal shock resistance were tested. RESULTS: SEM observation showed tight bond between these two materials and EMPA results showed penetration of Al element from Mark II block into veneering porcelain and Ca element from veneering porcelain into Mark II block occurred after sintering baking. The average temperature of thermal shock resistance for specimens in this study was (194.0+/-10.3) degrees C. Cracks were mainly distributed in veneering porcelain. CONCLUSION: Chemical bond exists between the Mark II machining ceramic and Vita VM9 veneering porcelain, and there is good thermal compatibility between them.
Asunto(s)
Cerámica , Porcelana Dental , Aleaciones Dentales , Análisis del Estrés Dental , Coronas con Frente Estético , Ensayo de Materiales , Resistencia al Corte , CirconioRESUMEN
OBJECTIVE: To evaluate the effects of all-ceramic veneers in clinic fabricated by computer aided design/computer aided manufacturing (CAD/CAM) system and veneered with Vita VM9. METHODS: 54 all-ceramic veneers were made for 12 patients. The patients were divided into three groups: Tetracycline staining group, fluorosis group and devitalization group. The color of patients' teeth was checked before and after laminates with Shade Eye. All-ceramic veneers was checked on the white background and abutment background. The value of L*, a* and b* were calculated to compare the color difference among 3 groups. The color, fitness and fracture of all-ceramic veneers were checked in clinic after restoration every 3 months. RESULTS: All-ceramic veneers as a replacement for discolored teeth showed good appearance. The substructures and veneers showed significant color difference between white background and abutment background in tetracycline staining group and devitalization group, but there was no significant color difference in fluorosis group. All veneers had good esthetic effect, excellent marginal fit, good gingival and adjacent condition. The fracture was not found in clinic. CONCLUSION: The effects of all-ceramic veneers were perfect in color, fitness and stability to fracture. Fluorosis teeth is the best indication for all-ceramic veneers. To tetracycline teeth and devital teeth, the fundic porcelain with deep color should be chosen, or an opaquing material be applied as fundus in all-ceramic veneers repairing.