"Burnishing" demineralization of root surfaces: ultrastructural surface characteristics

The purpose of this study was to compare the surface topography of roots treated with a resin bonding demineralizing agent using either a "placed" or "burnished" application technique.

Fifteen roots of human teeth were sectioned in half and a treatment area prepared on the coronal portion of each proximal section. This area was root planed to expose dentin. Treatment areas were demineralized with (1) a commercially available demineralizing agent (10% citric acid with 3% ferric chloride) (Amalgambond; Parkell) or (2) 30% citric acid solution. Cotton pellets saturated in either solution were placed or burnished (vigorously rubbed) on the treatment area for 3 min. Sections were prepared for SEM analysis using liquid CO2 dehydration.

Areas of cementum and dentin were evident on most treatment areas. Specimens of both placed groups lacked a smear layer and exhibited a cracked-eroded, flat surface of matted or ridged fibrous material. Specimens in both burnished groups also lacked a smear layer, yet in stark contrast, exhibited an abundant array of deeply tufted fibril material similar to that of a "shag carpet". Two types of tufted fibril patterns were present: a lace-like array of shorter fibrils seen on dentin, and a voluminous mass of longer fibrils seen on cementum.

Root cementum and dentin, treated with either demineralizing agent using the burnishing application technique, were ultrastructurally similar in that both displayed an abundant array of deeply tufted fibril material. This differed from the flat/matted fibril material seen using the placed application technique.