STRUCTURAL EVIDENCE OF A SEALED TISSUE INTERFACE WITH A TOTAL-ETCH WET-BONDING TECHNIQUE IN-VIVO

The resin-dentin interface of in vivo specimens restored with the All- Bond 2 system by use of a total-etch wet-bonding technique on vital de ep human dentin was investigated by: (a) SEM examination of cryofractu red specimens; (b) SEM examination of acid-rinsed, highly polished, em bedded specimens; and (c) TEM examination of demineralized ultrathin s ections. Ultrastructural features that were pertinent to the formation of an effective clinical seal were characterized. It is suggested tha t the establishment of an effective seal of the patent dentinal tubule s following total etching is accomplished by: (1) the formation of an outer zone of a solid resin plug surrounded by a circumferential cuff of resin-impregnated dentin; and (2) the formation of an inner zone of a hollow resin sheath with resin globules along the internal walls of the tubules, closely adapting to the odontoblast process. The structu ral appearance and functional implications of these two zones were str ikingly similar, with the sealing of exposed dentinal tubules in arres ted carious lesions or cervical abfraction lesions. It appeared that t here is a common denominator in physiologic isolation defense mechanis ms and the total-etch, wet-bonding technique in the All-Bond 2 system in preserving the biological and morphological integrity of the pulpo- dentinal complex.