RESUMEN
Early caries lesions consist of noncavitated subsurface demineralization caused by the dissolution of hydroxyapatite from the surface to the subsurface area of the enamel. Such lesions cannot be remineralized effectively by the conventional treatment. Thus, there is a need for a noninvasive technique capable of delivering the remineralizing agent to subsurface sites. For this purpose, fluoride iontophoresis (IP) using weak currents has been investigated with some conflicting results and no information on the crystal structure and composition. Because enamel remineralization involves the role of fluid from dentin, the presence of enamel fluid is necessary to determine the repair associated with the physiological condition. This study aimed to investigate structural and compositional characteristics, including the remineralizing effect of 5% sodium fluoride (NaF) IP with different polarities, cathodal iontophoresis (CIP), and anodal iontophoresis (AIP) for the treatment of natural enamel caries under simulated pulpal pressure. A bulk measurement of the crystal structure inside the lesion was first determined using calcium (Ca) K-edge X-ray absorption spectroscopy. IP with both polarities significantly promoted subsurface remineralization. The CIP generated a significant increase in the Ca/phosphorus ratio, and fluoride at the surface lesion significantly correlated with higher mineral density (MD) and more strengthening crystal structure of the lesion volume, while the lesion's MD and other impurities at the lesion surface, mostly the carbonate ions, affected the significant increase in MD with the unchanged structure of the lesion volume after AIP. The CIP of NaF is an ideal method for rapid enamel remineralization and recrystallization of fluoroapatite/fluorohydroxyapatite.
Asunto(s)
Caries Dental , Fluoruros , Humanos , Fluoruros/química , Iontoforesis , Cristalización , Remineralización Dental/métodos , Fluoruro de Sodio/uso terapéutico , Caries Dental/terapia , Caries Dental/patología , Durapatita , Cariostáticos/uso terapéuticoRESUMEN
AIMS: (1) To determine the pulpal sensory thresholds in human teeth obtained from using various EPT conducting media and (2) to determine whether there are gender differences. METHODOLOGY: One intact maxillary central incisor was randomly selected from each of 40 participants (20 male, 20 female) aged 19-24 year. A constant-current electrical stimulator (University of Bristol, UK) was used to apply electrical stimuli with different conducting media at intervals of 1 min on the middle of the crown to evaluate the sensory threshold of the tooth. The tip of the electrode was coated with a thin layer of test media. The sensory thresholds and the pain scores were measured simultaneously after applying stimuli twice a second and gradually increasing the intensity until felt by the participants. Test media included water-based gels (K-Y UltraGel; Xylocaine 2% Jelly, electrode gel, fluoride gel) and toothpastes (Colgate Total; Sensodyne Repair & Protect; Dentiste' Plus White; Sparkle White). The sensory threshold data were evaluated using two-way anova followed by the Tukey test. RESULTS: Xylocaine 2% Jelly and fluoride gel evoked significantly lower threshold values when compared with Sensodyne Repair & Protect (P < 0.001). With all test media, the mean sensory threshold from the female group was significantly lower than that of the male group (P < 0.001). CONCLUSION: The sensory thresholds to electrical stimuli in human teeth was influenced by the type of conducting media and gender.
Asunto(s)
Prueba de la Pulpa Dental , Dentífricos , Geles , Umbral Sensorial , Celulosa/análogos & derivados , Combinación de Medicamentos , Femenino , Fluoruros , Fluoruros Tópicos , Glicerol , Humanos , Incisivo , Lidocaína , Masculino , Nitratos , Dimensión del Dolor , Fosfatos , Glicoles de Propileno , Factores Sexuales , Ácido Silícico , Pastas de Dientes , Adulto JovenRESUMEN
Evidence suggests that postural changes in systemic blood pressure may significantly affect blood flow in the dental pulp. This in vivo study examined the responses of pulpal perfusion, systemic blood pressure, and heart rate to postural changes in humans. The experiments were done on 21 premolars in 16 participants aged 20-31 yrs. Pulpal blood flow recordings were measured by means of a laser Doppler Flowmeter. A blood pressure monitor was used to record blood pressure and heart rate. All measurements were simultaneously recorded for 1 min, 5 min after participants made postural changes. Changing from supine to standing caused a significant reduction in pulpal perfusion, while heart rate and diastolic blood pressure increased significantly. A significant non-linear relationship was found between percentage changes in pulpal perfusion and heart rate resulting from standing up. We speculate that when patients arise from the supine position, the shift in venous blood to the legs transiently (2-10 sec) lowers venous return and cardiac output, causing less inhibition of the vasomotor center, which, in turn, results in increased heart rate and blood pressure, but a decrease in pulpal blood flow. These results suggest that pulpal blood flow is affected by postural change, presumably via the autonomic nervous system.
Asunto(s)
Sistema Nervioso Autónomo/fisiología , Pulpa Dental/irrigación sanguínea , Postura/fisiología , Adulto , Diente Premolar/irrigación sanguínea , Presión Sanguínea/fisiología , Gasto Cardíaco/fisiología , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Flujometría por Láser-Doppler/instrumentación , Pierna/irrigación sanguínea , Masculino , Flujo Sanguíneo Regional/fisiología , Posición Supina/fisiología , Factores de Tiempo , Sistema Vasomotor/fisiología , Adulto JovenRESUMEN
In this study, two types of ceramic brackets--monocrystalline and polycrystalline--were bonded to unroughened and roughened resin-composite discs using a light-cured orthodontic adhesive, and the bonds tested under shear stress in a universal testing machine. There was no significant difference in the shear bond strength between the combinations of ceramic brackets, and between the surface treatments of the resin composite. A higher frequency of resin-composite fracture was observed with the polycrystalline brackets (12/20) than with the monocrystalline ceramic brackets (7/20). It is concluded that debonding any type of ceramic bracket from a resin-composite surface may cause damage to the resin composite itself.