An audit of shade reproduction of fixed metal ceramic prostheses.

This investigation aimed to evaluate the colour difference between metal ceramic restorations and their corresponding shades and any reasons for a colour mismatch in the dental laboratory. The colour of 50 consecutive metal ceramic restorations produced in a laboratory was measured using a spectrophotometer and compared to the shade tabs. Colour reproduction was optimal at porcelain thicknesses between 1.4-1.6 mm, varied between technicians within the same laboratory and was better for shades in the 2M group. Most crowns were above the threshold for a clinically acceptable shade match and almost all crowns were lighter than the corresponding shade tab.

The acrylic tooth-denture base bond: effect of mechanical preparation and surface treatment.

The bond strength of acrylic teeth to denture base resins was tested using a widely-accepted technique. The pre-treatments included abrading and grooving the teeth, the application of monomer and the application of a proprietary bonding agent. Each of the 360 specimens was tensile-tested until fracture, using a universal testing machine. When bonded to heat-cured resin, the grooved teeth had the highest mean bond strength while the grooved monomer-treated group had the lowest. When bonded to cold cure resin, the unabraded monomer-treated teeth had the highest mean bond strength and the unabraded group the lowest.

Assessing the efficacy of denture cleaners with quantitative light-induced fluorescence (QLF).

The aim of this study was to evaluate Quantitative Light Induced Fluorescence (QLF) analysis as a means of determining the ability of denture cleaners to remove stain from denture teeth. This study investigated the appearance of acrylic resin denture teeth subjected to QLF conditions in vitro. It aimed to determine if QLF was an appropriate method for detecting stain and its removal on acrylic resin denture teeth in vitro and also to develop a quantitative and reproducible method for assessing the efficacy of denture cleaners using QLF. This study showed that not all acrylic resin denture teeth fluoresced under QLF examination. QLF demonstrated the ability to detect and quantify longitudinal changes in stain removal by the various denture cleaners used in the study.

Dissolution of human enamel in still flavoured water drinks in vitro

AIM: This study aimed to investigate the erosive potential of these drinks using human enamel in vitro. MATERIAL AND METHODS: A range of bottled, still flavoured water drinks available in the UK were investigated and their erosive potential was compared by measuring pH and titratable acidity. Six beverages were chosen for the main study and also both a negative (distilled water) and positive control (orange juice). Human enamel specimens were prepared, sectioned and varnished leaving an exposure window visible to have contact with test solutions. Each specimen was randomly allocated in groups of six. Each group was exposed to 20 ml of one of the eight test solutions for 10, 30, 60 and 90 min. Quantitative light-induced fluorescence was used to ensure the teeth selected were free of artefacts and diseased areas. Erosion was measured using non-contact optical profilometry. RESULTS: Enamel loss occurred with all test drinks and the positive control (p<0.05) and in most cases the still water drinks were just as erosive as the positive control. Only vitamin water at 30 min was not significantly different from the negative control (p= 0.86), All drinks tested resulted in significant enamel loss (p<0.01). These results may indicate that consumers should think of still water beverages as potentially acidic drinks rather than just flavoured healthy water alternatives. CONCLUSION: This study indicates the need for preventive advice to be given by dentists about such beverages and therefore ultimately to make patients and consumers more aware of hidden erosive risks.