A J Gwinnett1. 1. Department of Oral Biology and Pathology, School of Dental Medicine, State University of New York at Stony Brook, 11794-8702, USA.
Abstract
OBJECTIVES: The purpose of this study was to compare the structure of acid-conditioned dentin in its wet and dry state. METHODS: Using conventional and environmental scanning electron microscopy, conditioned dentin was examined in a wet, air-dried and critical point-dried state. Six different treatments were used including citric, maleic, nitric, oxalic and phosphoric acids in their commercial formulations and applied in accordance with manufacturer's instructions. RESULTS: Loss of moisture from acid-conditioned dentin through simple air drying and drying under controlled conditions of environmental scanning microscopy resulted in morphological alteration of the fibrous, collagenous structure. Critical point drying preserved the fibrous integrity of the outer mineral-depleted zone. This observation was true for all the acids used. SIGNIFICANCE: While the ultrastructure of dentinal collagen may be chemically stabilized or relatively unaltered by acid conditioning, it is nonetheless subject to morphological degradation and collapse during water loss. Only critical point drying can control the interfacial stress accompanying water transport and loss at the fiber boundary. Confirming previous observations, this study supports the concept of maintaining the moist state of dentin and the morphological integrity of the collagen so as to facilitate optimal resin infiltration in the bonding procedure.
OBJECTIVES: The purpose of this study was to compare the structure of acid-conditioned dentin in its wet and dry state. METHODS: Using conventional and environmental scanning electron microscopy, conditioned dentin was examined in a wet, air-dried and critical point-dried state. Six different treatments were used including citric, maleic, nitric, oxalic and phosphoric acids in their commercial formulations and applied in accordance with manufacturer's instructions. RESULTS: Loss of moisture from acid-conditioned dentin through simple air drying and drying under controlled conditions of environmental scanning microscopy resulted in morphological alteration of the fibrous, collagenous structure. Critical point drying preserved the fibrous integrity of the outer mineral-depleted zone. This observation was true for all the acids used. SIGNIFICANCE: While the ultrastructure of dentinal collagen may be chemically stabilized or relatively unaltered by acid conditioning, it is nonetheless subject to morphological degradation and collapse during water loss. Only critical point drying can control the interfacial stress accompanying water transport and loss at the fiber boundary. Confirming previous observations, this study supports the concept of maintaining the moist state of dentin and the morphological integrity of the collagen so as to facilitate optimal resin infiltration in the bonding procedure.
Authors: Paulette Spencer; Qiang Ye; Jonggu Park; Elizabeth M Topp; Anil Misra; Orestes Marangos; Yong Wang; Brenda S Bohaty; Viraj Singh; Fabio Sene; John Eslick; Kyle Camarda; J Lawrence Katz Journal: Ann Biomed Eng Date: 2010-02-27 Impact factor: 3.934