Dentine hypersensitivity: the effects of brushing desensitizing toothpastes, their solid and liquid phases, and detergents on dentine and acrylic: studies in vitro.
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.
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ABSTRACT: OBJECTIVES: The paper's aim is to review dentin hypersensitivity (DHS), discussing pain mechanisms and aetiology. MATERIALS AND METHODS: Literature was reviewed using search engines with MESH terms, DH pain mechanisms and aetiology (including abrasion, erosion and periodontal disease). RESULTS: The many hypotheses proposed for DHS attest to our lack of knowledge in understanding neurophysiologic mechanisms, the most widely accepted being the hydrodynamic theory. Dentin tubules must be patent from the oral environment to the pulp. Dentin exposure, usually at the cervical margin, is due to a variety of processes involving gingival recession or loss of enamel, predisposing factors being periodontal disease and treatment, limited alveolar bone, thin biotype, erosion and abrasion. CONCLUSIONS: The current pain mechanism of DHS is thought to be the hydrodynamic theory. The initiation and progression of DHS are influenced by characteristics of the teeth and periodontium as well as the oral environment and external influences. Risk factors are numerous often acting synergistically and always influenced by individual susceptibility. CLINICAL RELEVANCE: Whilst the pain mechanism of DHS is not well understood, clinicians need to be mindful of the aetiology and risk factors in order to manage patients' pain and expectations and prevent further dentin exposure with subsequent sensitivity.Clinical Oral Investigations 12/2012; · 2.20 Impact Factor
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ABSTRACT: Abstract Objective: The objective of this in vitro study was to evaluate the immediate and short-term effects of laser neodymium-doped yttrium aluminum garnet (Nd:YAG) irradiation and in-office desensitizing treatment on dentin tubule occlusion. Background data: Literature shows a lack of long-lasting treatments for dentin hypersensitivity. Methods: Forty-eight dentin slabs (4×4×2 mm) were ground flat, polished, and treated with 27% ethylenediaminetetraacetic acid (EDTA) to open the dentinal tubules. Specimens were randomly divided into the following experimental groups (n=12): Group 1: Control (no treatment); Group 2: Nd:YAG laser irradiation (100 mJ, 85 J/cm(2) per pulse with a quartz fiber of 400 μm, in scanning movements); Group 3: In-office prophylaxis with pumice; Group 4: In-office Colgate Sensitive Pro-Relief™ Desensitizing Paste. Treatments were performed according to the manufacturer's instructions. After treatment, the specimens were submitted to a sequence of erosive and abrasive challenges, twice a day for 5 days. The specimens were qualitatively and quantitatively evaluated by scanning electron microscopy immediately after treatment and after 4 and 5 days. The response variable was the amount of occluded dentin tubules per area, determined by three different examiners with the use of visual criteria, with a standardized grade created in the PowerPoint program. Data were compared with ANOVA and Tukey's test, considering a 5% significance level. Results: Immediately after treatment, a reduction in the number of opened dentin tubules was observed for the laser group when compared with the control group (p<0.05). After the experimental procedures, there were no quantitative differences between the amount of opened dentin tubules for all groups; however, micrographs showed some qualitative tubule occlusion for the laser group after the erosive/abrasive challenge. Conclusions: only laser irradiation was capable of immediately sealing the dentinal tubules; however, none of the treatments showed efficacy in maintaining tubule occlusion after the chemical and mechanical challenges.Photomedicine and laser surgery 05/2013; · 1.76 Impact Factor
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ABSTRACT: Release of CO2 has caused significant climate change, and agricultural land use consitutes an important carbon source as well as principal carbon sinks. This paper, by examining carbon functions of main agricultural land in China, shows that in 2000-2008 the annual growth rate of carbon emission for arable land amounted to 2.47 percent, the average annual growth of carbon sinks for forest reached 3.19 percent, and the diminishing rate of carbon sink for grassland turned to be small but quite distinct. For arable land, higher carbon emissions are mainly located in its central provinces and major agricultural provinces, while higher carbon intensity in its eastern coastal provinces. Agricultural land of 9 provinces in China was found with net carbon emissions, primarily in the agricultural provinces and ecologically fragile urban areas, whereas the other 22 provinces with net carbon sinks. The EKC tests between carbon intensity of agricultural land and agricultural output per capita illustrate a significant inverted Ucurve relationship; as for agricultural output per capita, the inflection point of 9,615 RMB yuan was surpassed by 11 provinces, mainly in eastern China, developed cities and the northeast region. Finally, policy recommendations are proposed to reduce carbon emissions of agricultural land use across China.Energy Procedia 01/2011; 5:1949-1956.