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Results for “Tooth Permeability”

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At least 235 records · Page 13Linked to original sources
PubMed2005

Penetration depth of laser Doppler flowmetry beam in teeth.

OBJECTIVE: The aim of this study was to determine the penetration depth of laser light in teeth for contact and noncontact probe tip. STUDY DESIGN: Fifty-one freshly extracted human mature maxillary and mandibular single rooted teeth were selected for the study. A laser Doppler flowmeter was used as a laser source. A digital camera was used to take pictures (with "night shot" mode in total darkness). When probe tip was in contact and when it was 1 mm away from the tooth, the depths of the areas illuminated in high and low density were measured. RESULTS: In contact probe, root was illuminated to 4.28 +/- 0.14 mm depth with high density and 13.27 +/- 0.27 mm depth with low density. In noncontact probe, 4.36 +/- 0.16 mm with high density and 13.28 +/- 0.30 mm with low density of illumination were seen on the root. Between contact and noncontact probe situations the difference was not statistically significant in the depth of illumination. On the other hand, in both groups the difference between areas illuminated in high and low density was statistically significant (P < .05). CONCLUSION: Contact or noncontact of the probe on tooth surface did not show any significant difference in light penetration. Besides, we think that, for the present, it is impossible to eliminate the contamination from periodontal tissues completely even if the necessary precautions (periodontal paste etc.) are taken.

Dental Pulp↗
PubMed2002

Effect of calcium hydroxide as a supplementary barrier in the radicular penetration of hydrogen peroxide during intracoronal bleaching in vitro.

AIM: To examine pH changes in the cervical external root surface, when calcium hydroxide was used as a supplementary barrier to the protective base material during intracoronal bleaching. METHODOLOGY: Twenty-eight single-rooted human premolars extracted for orthodontic reasons were instrumented with K-Flex files, obturated with gutta-percha and subjected to thermocatalytic bleaching. The teeth were divided into four groups. In group A, a glass-ionomer cement barrier was placed at the cemento-enamel junction (CEJ) level and in group C, the barrier was placed 1 mm apical to the CEJ. In groups B and D, Ca(OH)2 was placed in contact and apical to the glass-ionomer cement at the CEJ and 1 mm apical to the CEJ, respectively. The teeth were placed in vials containing distilled water and the pH values of the medium surrounding the teeth were recorded after 1, 2, 4, 10 and 15 days, following renewal of the medium. RESULTS: The pH in the medium became acidic in all groups. No statistically significant differences existed between groups for all the experimental days (P = 0.790). CONCLUSION: The placement of Ca(OH)2 as a supplementary barrier during intracoronal bleaching did not have a significant effect in reversing the acidic pH created at the external root surface in vitro. Its potential effect during these procedures in vivo needs to be further investigated.

Adult↗
PubMed1995

The influence of air-drying on hyper-remineralization of demineralized dentine: a study on bulk as well as on thin wet section of bovine dentine.

The influence of air-drying on the remineralization of demineralized bovine dentine was examined in wet bulk samples, in dried bulk samples as well as in wet thin sections. Bulk samples of bovine dentine were first demineralized in an acidic gel (pH = 5) at 37 degrees C for 3 weeks. After 24-hour pre-treatment of either air-drying or immersion in water, the bulk samples were remineralized in a solution containing 1.5 mM Ca, 0.9 mM phosphate and 10 ppm F (pH = 7) at 37 degrees C for 2, 4 or 8 days. Separately thin sections prepared from demineralized bulk dentine were immersed in water for 24 h and were also exposed to the remineralization solution for 2, 4 or 8 days. The results show that air-drying of the bulk samples increased remineralization of dentine considerably; the microradiographic parameters (ld, delta Z and la) show that the degree of remineralization ranks: thin wet sections > bulk dried > bulk wet. Especially, the remineralization inside lesions was greatly enhanced in thin sections and dried samples. It is presumed that the increased remineralization in dried samples is caused by a 'sponge effect', in which the remineralization fluid is sucked up in a dried shrunken lesion, resulting in fast and deep penetration of remineralization solution and/or presumably increased nucleation.

Air↗
PubMed2002

Understanding and managing dentin hypersensitivity.

Dental hygienists frequently encounter clients who present with one or several sensitive teeth. These clients often rely on the dental hygienist to help determine the cause and to provide supportive treatment to relieve their discomfort. Therefore, it is essential for dental hygienists to fully understand the complexity of dentin sensitivity, be well informed about treatment approaches, and have an appreciation of the difficulties inherent in designing and conducting clinical hypersensitivity trials. Difficulties in designing hypersensitivity research have precluded a definitive answer concerning a best treatment approach. The purpose of this course is to present dental hygienists with current information about the pain of sensitive teeth and the associated differential diagnosis. The theory of pain transmission, etiology of dentin sensitivity, professional and self-care treatment modalities, and natural remission of tooth sensitivity will be discussed. Tooth and pulp biology will be reviewed as a means of explaining treatment and management approaches. At completion of this course, as measured by a post-test, participants with be prepared to apply the knowledge gained to their evidence-based practice to positively impact the oral health of their clients.

Dental Hygienists↗
PubMedDate not supplied

Shear bond strength of 4th & 5th generation dentin bonding agents in the presence and absence of moisture. An in vitro study.

Extracated human molars were used for the study, flat dentinal surfaces were prepared on the occlusal surfaces, and then 4th and 5th generation dentin bonding agents were used in dry and moist conditions to bond composite resin onto the flat dentin surfaces. Shear Bond Strength was measured using Instron Universal Testing machine. Failures were recorded as adhesive, cohesive and mixed. Bond strength was highest in moist condition, because the moist surface permits more porous collagen network and hence greater infiltration of adhesive monomers, than do surfaces that are air dried. Moreover, those dentin bonding agents whose primers are based on acetone show improved bond strength, because acetone aggressively pursues and displaces water in the substrate, resulting in the primer resin being carried into tissue channels and porosities. When the dentin is air dried, the water that is supporting the collagen network evaporates causing the collagen network to collapse network is greatly reduced, which in turn decreases the premeability of intertubular dentin to adhesive resin and as a result causes decrease in bond strength. 5th generation dentin bonding agent showed significant improvement in the moist dentin bond strength.

Bisphenol A-Glycidyl Methacrylate↗