Enamel lamellae in first and second molar teeth of rat mandibles, 4 weeks after birth, were observed by scanning electron microscopy with EDTA-treated samples. The lamellae succeeding to organic pellicles were occasionally seen in the buccal and lingual regions of the mid-coronal to cervical enamel, and the mesial and distal regions of the fissure walls of the cuspal-side enamel. However, the lamellae were always found throughout the fissure floors buccolingually, where fissure caries is apt to occur.
The purpose of this study was to investigate the factors affecting the bonding of Silicoater MD (SMD) system for resin veneering to cp titanium. Cp titanium plates were sandblasted according to the instruction of the system followed by the pre-heat treatment at 300 to 600°C. Specimens for the bond strength were prepared with different heating time for Sililink and the opaque resin was cured by two light exposure units. Post-cure heat treatment of the opaque and resin composites was performed at 100°C for 15 to 60 minutes. The bond strength was determined by a tensile shear test after storing the specimen in deionized water at 37°C for one day and also after thermal cycling at 5°C and 55°C for 16.5 days (20,000 cycles). Contact angles of cp titanium plates with pre-heat treatment was measured. SEM observation of the surface of the sandblasted cp titanium plate on the cross section was performed. Pre-heat treatments for titanium didn't enhance bond strengths significantly, though contact angle had a tendency to decrease with the increase of temperature and treating time. Heating time of Sililink influenced the bond strength which was an important step to prepare Si-Ox layer for a chemical bond. The light exposure unit influenced the bond strengths because of the temperature rising of the opaque resin. The post-cure heat treatment had little effects on the bond strengths. The handling properties of the SMD system was very easy but was still technically sensitive. We suggest the 2 minutes heating for Sililink and the use of Triad II for the curing of opaque resin to increase the bond between titanium and resin for the current system.