Dentine exhibiting symptoms of
dentine hypersensitivity has tubules open at the dentine surface and patent to the pulp. The mechanisms whereby dentinal tubules are exposed is ill understood but probably involves a variety of abrasive and/or erosive agents. This study in vitro examined the quantitative and qualitative effects of
toothpastes, their solid and liquid phases and
detergents on dentine and acrylic. Abrasion of dentine and acrylic were measured by surfometry. Morphological changes to dentine were assessed by scanning electron microscopy. Abrasion of dentine and acrylic by
toothpastes increased with increasing brushstrokes with marked differences in the extent of abrasion between different
pastes. Brushing dentine with water or
detergents produced progressive abrasion but which appeared to plateau around 2 microm loss. Water and
detergents produced minimal effects on acrylic. At 5000
strokes dentine abrasion by solid phases was less than the parent
toothpastes but the ranking order of abrasivity was the same as the parent
toothpastes. Loss of dentine produced by liquid phases was minimal and in the order of 1-2 microm. Observationally, all
toothpastes removed at least the dentine
smear layer to expose many tubules; with one desensitizing product leaving a particulate deposit occluding most tubules. The solid phases of the
toothpaste produced identical morphological changes to the parent
paste. The liquid phases and
detergents all exposed dentinal tubules by 5000
strokes. Water had little or no effect on the dentine
smear layer. It is concluded that
toothpastes, solid phase, liquid phase and
detergents have the potential to abrade or erode dentine to a variable degree and result in tubule exposure. The effects of the liquid phases and
detergents appear limited to the removal of the
smear layer. Such detrimental effects seen in vitro could have relevance to the aetiology and management of
dentine hypersensitivity.
Toothpaste formulations which despite exposing tubules have ingredients capable of occluding tubules may be an area of development for such products.