RESUMEN
It is generally accepted that the pain of dental hypersensitivity resulting from gum recession is from the movement of fluid within the exposed tubules of dentin, causing changes in pressure on the nerve within the pulpal cavity. One method of treating hypersensitivity is to occlude the tubules, preventing fluid movement. This article discusses the use of a dye penetration technique, which establishes this mechanism of action for a desensitizing fluoride toothpaste containing calcium and phosphate. Two groups of intact teeth were perfectly sealed with enamel paint. Windows 100-micro to 200-micro deep were opened on opposite sides of each tooth at the dentin-enamel junction and briefly etched using 20% polyacrylic acid. One batch of teeth was treated eight times for 30 mins each with a 1:3 slurry of the desensitizing toothpaste and another set with a similar slurry prepared from a calcium- and phosphate-free control. A 0.85% aqueous solution of acid red fuchsin dye was applied to each window and allowed to dry. After a brief rinse, the teeth were sectioned across the windows. Almost no dye penetration was seen in teeth treated with the desensitizing toothpaste; however, extensive penetration through the dentin was visible in the control-treated teeth. The differences in dye penetration for the two sets of teeth were significant by both subjective (P < .001) and objective (P < .01) measures. Tubule occlusion because of calcium and phosphate ions from the desensitizing toothpaste accounts for its tooth desensitizing efficacy.
Asunto(s)
Desensibilizantes Dentinarios/farmacología , Permeabilidad de la Dentina/efectos de los fármacos , Sensibilidad de la Dentina/prevención & control , Líquido de la Dentina/efectos de los fármacos , Pastas de Dientes/química , Sulfato de Calcio/administración & dosificación , Sulfato de Calcio/farmacología , Cariostáticos/administración & dosificación , Colorantes , Desensibilizantes Dentinarios/administración & dosificación , Sensibilidad de la Dentina/etiología , Fluoruros/administración & dosificación , Recesión Gingival/complicaciones , Humanos , Peróxido de Hidrógeno , Nitratos/farmacología , Fosfatos/administración & dosificación , Fosfatos/farmacología , Compuestos de Potasio/administración & dosificación , Compuestos de Potasio/farmacología , Colorantes de Rosanilina , Bicarbonato de Sodio/química , Bicarbonato de Sodio/uso terapéutico , Fluoruro de Sodio/química , Fluoruro de Sodio/uso terapéutico , Transmisión Sináptica/efectos de los fármacos , Pastas de Dientes/uso terapéuticoRESUMEN
Tooth hypersensitivity can occur when gum recession causes exposure of dentin. Tiny tubules, which permeate dentin, provide open passageways from the mouth to the intradental nerve in the pulpal cavity. Under such circumstances, stimuli in the mouth can cause pressure on the intradental nerve, leading to pain. Sealing the outside of the tubules with an impermeable substance can effectively treat hypersensitivity. One such clinically proven composition is a professionally applied tooth desensitizer, which has been shown to initially produce a layer of amorphous calcium phosphate (ACP) on the surface of dentin. Under the influence of fluoride, ACP reforms as hydroxyapatite (HAP), which has essentially the same composition as tooth mineral. Three fluoride toothpastes that deliver calcium and phosphate salts to the teeth also have been demonstrated in clinical trials to relieve hypersensitivity. This study compared the mechanism of action of these toothpastes to that of the professional desensitizer. A single application of the professional desensitizer or multiple applications of any of the three toothpastes was shown to reduce dentin permeability. A conventional fluoride toothpaste also was found to inhibit fluid flow through the dentin but to a lesser degree than the other toothpastes. The desensitizer and the three toothpastes were found to occlude the dentinal tubules with a layer of calcium phosphate that had a calcium-to-phosphate ratio consistent with the formation of ACP or HAP. The morphology of the coherent mineral layer formed by Arm & Hammer Enamel Care Sensitive was similar, especially to that produced by the desensitizer. In contrast, the conventional toothpaste left localized areas of surface residue composed of silica particles. The mechanism of action of the three toothpastes that deliver calcium and phosphate salts is the same as that of the professional desensitizer.
Asunto(s)
Fosfatos de Calcio/farmacología , Sensibilidad de la Dentina/tratamiento farmacológico , Dentina/efectos de los fármacos , Fluoruros/uso terapéutico , Bicarbonato de Sodio/farmacología , Fluoruro de Sodio/farmacología , Pastas de Dientes/farmacología , Cloruro de Calcio/farmacología , Fosfatos de Calcio/química , Mezclas Complejas/química , Mezclas Complejas/farmacología , Fluoruros/química , Fluoruros/farmacología , Peróxido de Hidrógeno , Microscopía Electrónica de Rastreo , Permeabilidad , Fosfatos/farmacología , Compuestos de Potasio/farmacología , Ácido Silícico , Bicarbonato de Sodio/química , Fluoruro de Sodio/química , Propiedades de Superficie , Pastas de Dientes/químicaRESUMEN
OBJECTIVE: The purpose of this study was to validate and calibrate an in vitro test method for screening the performance of peroxide-containing toothpastes against actual clinical whitening performance. An additional objective was to estimate the whitening performance of a new peroxide-additive gel using the in vitro methodology. METHODS: A one-month longitudinal clinical study was performed to provide a benchmark for the in vivo intrinsic whitening performance of a peroxide-containing fluoride toothpaste. An in vitro study was then conducted, using freshly prepared slurries of the same peroxide-containing toothpaste in artificial saliva, to repeatedly treat extracted human teeth with natural intrinsic stain. The effect of cumulative treatment time on whiteness was determined using objective chromometer whiteness measurements (L*, a*, and b*), and more subjective Vita Shade guide (Vitapan) comparisons, and the results were correlated. A non-peroxide fluoride toothpaste was used as a negative control. The peroxide gel additive, combined in a 1:1 ratio with each of two non-peroxide toothpastes and diluted in artificial saliva, was evaluated using the same instrumental and subjective measures for in vitro whitening efficacy. The previously evaluated peroxide toothpaste and one of the non-peroxide toothpastes were used as positive and negative controls, respectively. RESULTS: In the clinical study, the peroxide-containing toothpaste produced a linear increase in tooth whiteness with time, achieving an approximately two Vita Shade guide improvement in whiteness at the end of four weeks. The same peroxide toothpaste in vitro produced a curvilinear increase in tooth whiteness versus cumulative treatment time, with a two-shade increase being achieved in 116 minutes. The non-peroxide control toothpaste produced less than half a shade guide increase in whiteness within the first 30 minutes, and none thereafter. Both the clinical and in vitro studies indicated that further whitening can be obtained with longer use of the peroxide-containing toothpaste or peroxide-additive gel. CONCLUSION: Treatment of naturally stained teeth in vitro with the peroxide toothpaste for 116 cumulative minutes produced the same two-shade increase in whiteness as obtained with twice-daily brushing for four weeks in vivo. The peroxide-additive gel, combined with a non-peroxide toothpaste, is projected to provide a similar two-shade increase in whiteness when used twice daily for four weeks. There are indications that greater intrinsic whiteness increase would be achieved with the peroxide toothpaste or with the peroxide-additive gel plus non-peroxide toothpaste with more extended regular twice-daily use in vivo.
Asunto(s)
Peróxido de Hidrógeno/química , Blanqueamiento de Dientes/normas , Decoloración de Dientes/terapia , Adolescente , Adulto , Anciano , Calibración , Femenino , Geles , Humanos , Técnicas In Vitro , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Cepillado Dental/instrumentación , Pastas de Dientes/química , Resultado del TratamientoRESUMEN
Surface defects such as scratching, acidic erosion, and natural dimpling of the tooth enamel can significantly affect its cosmetic appearance. There are many analytical techniques that can be used to view the surface of enamel and to assess the effect of surface treatments. Light microscopy, scanning electron microscopy (SEM), profilometry, and atomic force microscopy (AFM) can usefully be applied to viewing mineral surfaces and obtaining information about surface morphology and smoothness. Energy-dispersive x-ray fluorescence and other surface-ionizing techniques can give information about surface chemistry. Microhardness instrumentation can be used to determine surface hardness, while gloss meters and reflectometry can provide measurements of gloss and whiteness. In this study, four sets of in vitro experiments were performed, which illustrate the value of three of these techniques. Specially formulated calcium-containing toothpastes, designed to fill in surface defects in tooth enamel, were evaluated in four experiments for their ability to effect cosmetic improvements in etched tooth enamel: (1) two calcium-containing, sodium-bicarbonate-based toothpaste formulations were shown by SEM to smooth tooth enamel without introducing new scratches. In contrast, a commercial whitening toothpaste removed similar scratches but also created new ones; (2) calcium-containing dentifrices were shown by SEM and hardness measurements to put mineral onto the surface of enamel and to harden it. The effects of uneven dispensing of the two-phase, bicarbonate-based, calcium-containing formulation were shown to be small; (3) a number of different calcium-containing toothpastes were shown by SEM to deliver mineral onto the etched enamel surfaces, whereas a conventional fluoride toothpaste did not; and (4) AFM was used to follow the smoothing of an etched enamel surface after serial treatments with a calcium-containing, bicarbonate-based toothpaste. After 15 in vitro cycles, surface roughness was reduced by more than 50% and peak height was reduced by about two thirds. The results illustrate the effectiveness of the three analytical techniques and show that the calcium-containing toothpastes can deposit mineral into enamel surface deformities under a wide variety of conditions and from a wide variety of formulas.
Asunto(s)
Bicarbonatos/uso terapéutico , Abrasión de los Dientes/terapia , Remineralización Dental/métodos , Pastas de Dientes/química , Pastas de Dientes/uso terapéutico , Calcio/uso terapéutico , Esmalte Dental/química , Microanálisis por Sonda Electrónica , Dureza , Humanos , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Propiedades de SuperficieRESUMEN
New dual-phase fluoride toothpastes that contain soluble calcium, phosphate, and baking soda have recently been introduced into the market. These toothpastes are designed to fill in small surface defects in tooth enamel and thereby enhance tooth esthetics such as gloss. This two-part study was designed to assess these superficial mineralizing effects from using one of these products compared with an experimental calcium-containing, bicarbonate-free formulation and a conventional fluoride toothpaste using an intraoral model. Enamel specimens with 4 types of defects were mounted into an intraoral appliance and placed in the mouths of volunteers for 1 month. The four types of defects were whitening toothpaste abrasion, coarse abrasion, natural dimpling, and acid etching. Before and after intraoral exposure, scanning electron microscope photographs of the specimens were made. The surface microhardness of the acid-etched specimens also was determined. The volunteers brushed their specimens twice daily with one of three randomly assigned toothpastes. The toothpastes were a two-phase, calcium-containing, bicarbonate-based toothpaste; an experimental, two-phase, calcium-containing, bicarbonate-free toothpaste; and a conventional toothpaste. Only the calcium-containing toothpastes showed unequivocal signs of mineral deposition into surface defects, leading to smoothing of the enamel. All three products significantly increased the hardness of the etched enamel, presumably because of fluoride. However, only the two calcium-containing toothpastes gave significantly greater hardness increases than the conventional toothpaste; the specimens treated with a conventional toothpaste were indistinguishable from those treated with saliva.