Scanning electron microscope characterization of abrasion in human teeth.

Abstract

Objectives: The purpose of this study was to examine the surface changes of abrasion in human teeth by scanning electron microscopy. Materials and methods: Ten human premolars with cervical abrasion from 10 patients requiring tooth extraction, one tooth from each patient, were used in this study. The specimens were collected from the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Mahidol University and private dental clinics. After extractions, all teeth were stored in 10% formalin until required. The specimens were cut in mesiodistal directions, immersed in 5.25% sodium hypochlorite and then dehydrated using increasing ethanol concentrations (two changes 15 minutes each): 50%, 60%, 70%, 85%, 95%, 100% and dried by leaving the specimens at room temperature for 24 hours, mounted on aluminum stubs, coated with gold, 100-300 Å thick, with an ion sputter coater, and viewed with a JEOL JSM-6610 LV scanning electron microscope, at seven magnifications: X20, X30, X100, X500, X1,000, X3,500, and X10,000. The photomicrographs were described. Results: In the abraded areas which were limited to the enamel surfaces, most of the enamel surfaces appeared uniformly smooth and showed presence of horizontal, vertical, and oblique scratches. In the abraded areas which were deep and extended into the dentin, dentinal tubules were exposed and could be observed in oblique and longitudinal sections. In some areas, the enamel surfaces showed dissolution of enamel rod ends which gave the enamel surface a honeycomb appearance. In other areas, the dentin surfaces appeared rough with numerous openings of dentinal tubules. Parallel linear scratches arranged in various directions were also noted. Dentinal tubules showed a variation in the diameter of the openings, from patent to completely obliterated. In a few areas, an opening of the dentinal tubule was surrounded by a dentin matrix which consisted of a network of collagen fibers. In one tooth, two vertical fissures were seen in the abraded area. Conclusions: The abraded enamel surfaces appear smooth with a variable number of parallel scratch marks which are arranged in various directions. The abraded dentin surfaces show linear scratches similar to those of the abraded enamel and contain numerous openings of dentinal tubules. Evidence of erosion and abfraction is found.