N West

Publications (3)3.86 Total impact

• Article: Exposure time of enamel and dentine to saliva for protection against erosion: a study in vitro.

  S Wetton, J Hughes, N West, M Addy
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  ABSTRACT: Previous research, mainly on enamel, supports a protective role for salivary pellicle against erosion. Pretreatments have tended to be lengthy (24 h or more) and of questionable relevance to the regular intake of acidic food and drink by many individuals. The aim of this study in vitro was to determine the protective effect of salivary pellicle formed on enamel and dentine over time periods up to 4 h. Flattened, polished human enamel and dentine specimens were pretreated with unstimulated human saliva from a single donor for 2 min, 30 min (enamel only), 1, 2, or 4 h. Controls were exposed to water for the same times. Specimens were then exposed to 0.3% citric acid, pH 3.2 for 10 min with stirring. This cycle was carried out 12 times. Tissue loss was measured by profilometry after 3, 6, 9 and 12 cycles. For enamel, statistically significant protection was found at >or=1 h. For dentine, significant protection was achieved at 2 min. Salivary pellicle offered proportionately greater protection to enamel than dentine. Cautiously extrapolating these in vitro data suggests that pellicle should offer erosion protection to individuals who imbibe acidic drinks at frequencies of 1 h or less.
  Caries Research 02/2006; 40(3):213-7. · 2.33 Impact Factor
• Article: Dentine hypersensitivity: the effects of brushing desensitizing toothpastes, their solid and liquid phases, and detergents on dentine and acrylic: studies in vitro.

  N West, M Addy, J Hughes
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  ABSTRACT: 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.
  Journal of Oral Rehabilitation 01/1999; 25(12):885-95. · 1.53 Impact Factor
• Article: Etiology, mechanisms, and management of dentine hypersensitivity.

  M Addy, N West
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  ABSTRACT: Dentine hypersensitivity is a common painful condition of the teeth for which little is known of the etiology and predisposing factors. This tends to compromise management, and recurrence of the condition is frequent. Abrasive and erosive factors, by their effects on enamel and gingiva, are important in localizing sites of exposed dentine. Erosive agents are probably responsible for initiating sensitivity by opening dentinal tubules. Management should not only be treatment based. First, a differential diagnosis should be considered. Then, etiologic and predisposing factors should be identified and where possible removed, reduced, or modified. Treatments are largely aimed at blocking the hydrodynamic mechanism for stimulus transmission across dentine by occluding dentinal tubules. There is a need for further research into understanding the condition itself, its etiology, and the mode of action of the large number of varied but apparently effective therapeutic agents.
  Current opinion in periodontology 02/1994;