| |
The thickness of human dental enamel decreases as a function of time. Common causes are carious demineralization, erosion and abrasion. Because these processes progress very slowly, the reduction of the enamel thickness is difficult to monitor. In this study it was investigated whether the thickness of the enamel could be monitored by measuring the fluorescence from a bonding agent mixed with a fluorescent dye. Extracted molars were cleaned and one of the approximal surfaces of each tooth was etched with a 37% phosphoric acid etch gel (DMG, Hamburg, Germany) for 40s, rinsed with water spray, air dried and sealed with a fluorescent bonding. To obtain a fluorescent bonding, a drop of Fluorol 7GA (excitation maximum at 468 nm and emission maximum at 525 nm) was mixed with two drops of a bonding agent. The bonding was applied onto the etched enamel and cured by light from a polymerization unit. The fluorescence of the bonding was measured by QLF software. The sealant fluorescence was determined by subtracting the fluorescence of the unsealed enamel from that of the sealed enamel. The mesiodistal width of the tooth was measured using a digital micrometer. To allow reproducible measurements, tooth and micrometer were embedded in impression material. Upon each measurement a thin layer was removed from the sealant using a medium grid composite finishing disc, after which the measurements of fluorescence and mesiodistal width were repeated. This procedure was continued until clearly no more sealant fluorescence was observed. The correlation between fluorescence and depth ranged from 0.54 to 0.97 for observations from above the level of the etched surface, and from 0.33 to 0.94 for observations from below the level of the etched enamel surface. It was concluded that the decrease in thickness of sealed enamel can be monitored by measurement of the fluorescence of the sealing agent. |