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Biomedical subjects

I Gedalia

Publications and source records attributed to I Gedalia.

At least 19 recordsLinked to original sources
PubMed1992

Effect of fluoride varnish on the retentive strength of provisional crowns luted with various temporary cements.

The retention of temporary crowns was studied with the use of a fluoride varnish (Duraphat) combined with various temporary cements. The mixture of Duraphat varnish and cement improved retention, with the exception of Opotow cement. Applying Duraphat varnish to the tooth surface before cementation enhanced the retentive strength of Tempbond, weakened the retention of Freegenol, but had no effect on Opotow cement. A "transfer effect" was observed, inasmuch as the Duraphat varnish encouraged adherence of the cement to the tooth structure rather than to the temporary crown.

Analysis of Variance↗
PubMed1992

Effect of bleaching agents on inorganic components of human dentin and cementum.

The effect of bleaching agents on the inorganic composition of human dentin and cementum was examined. Intact teeth were crushed, pulverized, and separated to dentin and cementum powders. The pulverized tissues were exposed to treatments with 30% H2O2, 3% H2O2, 2% sodium perborate in 30% H2O2, 2% sodium perborate in 3% H2O2, and 2% sodium perborate in bidistilled water for periods of 15 min and 1, 24, and 72 h. The degree of dissolution and the percentage of inorganic material for both dentin and cementum were measured. Thirty percent H2O2 and 2% sodium perborate in 30% H2O2 treatments significantly increased the solubility of dentin and cementum. The degree of dissolutions and the percentage of inorganic material remaining in the undissolved dentin and cementum increased with time progression. The greatest increase occurred with 30% H2O2 and 2% sodium perborate in 30% H2O2 after 24- and 72-h treatments. It is concluded that 30% hydrogen peroxide treatment may cause alteration in the chemical structure of the dentin and cementum making them more susceptible to degradation.

Borates↗
PubMed1992

Effect of hard cheese exposure, with and without fluoride prerinse, on the rehardening of softened human enamel.

The in situ rehardening effect was compared between Cheddar cheese consumption and saliva secretion with and without a fluoride pretreatment on softened human enamel. Ten volunteers wearing prostheses which held slices of human enamel participated in this study. Average microhardness of enamel was determined on the surface at baseline, after exposing to an acidic beverage, after exposing to saliva and mastication of cheese, with and without a mouth F prerinse (10 ml Meridol containing 0.025% F). The rehardening was increased in the groups consuming cheese compared to the saliva controls. The effect was increased by an F prerinse; the initial hardness of the intact enamel surface, however, was not reached.

Amines↗
PubMed1991

Effectiveness of fortnightly tooth brushing with amine fluorides in caries-prone subjects.

The aim of this study was to assess the caries incidence and plaque accumulation in schoolchildren at caries risk, after brushing the teeth fortnightly with gels containing 0, 0.4% F, 1.25% F as amine fluoride (AmF) or the common amine fluoride toothpaste containing 0.125% F. The study was conducted double blind over an 18-month period, and after 6 months discontinuation of brushing. Only the group that brushed with the 1.25% AmF gel showed a significant decrease in caries development compared to the group that brushed with the 0.125% AmF toothpaste. During the 6-month discontinuation period, the incidence of caries increased in all groups; the differences in caries development between all groups were not significant. Plaque indices were significantly lower in the AmF-treated groups. The highest fluoride concentration in the gel reduced the development of caries to zero, probably due to increased fluoride levels in the oral milieu of caries risk children. In order to maintain a positive effect of fluoride over an extended time period, caries-prone subjects should continue an initiated fluoride programme.

Adolescent↗
PubMed1991

Tooth enamel softening with a cola type drink and rehardening with hard cheese or stimulated saliva in situ.

The in-situ remineralization effect of hard cheese was compared with that of saliva on tooth enamel in man. The intra-oral test of softening enamel surfaces by a cola type drink followed by rehardening by chewing hard cheese and/or parafilm was assessed by microhardness and SEM measurements. Cheese consumption significantly increased the enamel hardness, whereas stimulated saliva did not have this effect. The remineralizing effects are presumably due to uptake of calcium and phosphate salts by the surface enamel. Morphologically, the enamel surfaces did not return to their original state.

Carbonated Beverages↗
PubMed1991

Effect of glycyrrhizin-containing toothpaste on dental plaque reduction and gingival health in humans. A pilot study.

Glycyrrhizin, the main saponin of licorice, a surfactant producing aqueous gel, was tested for its effect on gingival health, as a supplemental agent in a toothpaste. 40 male and female volunteers brushed their teeth twice daily, with a toothpaste containing 0.25% and 0.50% glycyrrhizin, or a control toothpaste, respectively. All 3 toothpastes contained sodium lauryl sulfate as detergent. The subjects of the 3 groups were examined at days 0, 7, 14, 28, 35 and 42 for plaque, gingival and bleeding indices. The examiner was unaware of subject assignment. None of the brushing regimens with the experimental toothpastes induced significant changes in the examined indices, that were distinct from those observed with the control toothpaste. The decrease (insignificant) in the indices of the study period from 0 to 14 days may be considered as an increased oral hygiene awareness by the subjects examined. Possible explanations for the lack of efficiency in improvement of plaque, gingival and bleeding indices, may have been an insufficient glycyrrhizin concentration and/or chemical incompatibility in a toothpaste containing a mixture of an anionic detergent and an organic antibacterial surface agent.

Adult↗
PubMed1991

Modulatory effect of fluoride and irradiation on rat molar rate of wear.

The hypothesis was tested that fluoride (F-) modulates molar wear rate in the irradiated rat and that enamel solubility and dentin hardness are involved in this process. Seventy five 21 day-old rats were divided into 5 groups. Groups received either F-(25 ppm) in the drinking water or irradiation to the head (15 Gy in a single dose), or a combination of the two. The rate of occlusal wear was assessed by computerized planimetry. The amount of wear was significantly higher in the F- and irradiation monotreated rats, while under combined treatment it did nor differ significantly from the control values. Fluoridation or irradiation suppressed enamel solubility, as measured by calcium release in the etchant. Dentin microhardness, expressed in Vickers hardness number, was enhanced after either treatment, but remained unaffected when F- administration preceded irradiation. Enamel solubility and dentin microhardness did not correlate significantly with the rate of occlusal wear.

Animals↗
PubMed1991

Enamel softening with Coca-Cola and rehardening with milk or saliva.

Rehardening effects by cow's milk and by secreted saliva were investigated, in situ, following softening of human enamel with an acidic beverage (Coca-Cola). Volunteers wearing orthodontic removable appliances participated in the study. The intra-oral test was chosen for measuring microhardness of enamel slabs inserted into the dental appliance. The softening and the rehardening degrees were defined as the alterations between initial- and experimental-microhardness value at the enamel surface. In addition, SEM photos were prepared from the initial and experimental stages. Exposure of enamel slabs to the acidic beverage during 1 hour had a softening effect as expressed by the hardness decrease and visualized by the SEM photo. Rehardening effects following milk or saliva exposures respectively were evident, presumably due to deposited organic and mineral material on the enamel surface.

Adult↗
PubMed1990

Fluorosis and dental caries in 6-8-year-old children in a 5 ppm fluoride area.

Fluorosis levels and caries prevalence were evaluated in 152 children aged 6-8 yr residing from birth in an area with 5 ppm fluoride in the drinking water. Sixty-two of the subjects had mild fluorosis in both primary and permanent dentition, 31 were defined as moderate, and 4 cases had no signs of fluorosis; 14 cases had a more severe fluorosis level in the primary dentition as compared to 41 cases in which fluorosis was more severe in the permanent dentition. More primary dentitions were free of fluorosis in females than in males (P less than 0.05). No differences between males and females were found in the permanent dentition fluorosis. The decay rate in the permanent dentition gradually increased with increasing fluorosis severity, a finding not observed in the primary dentition. Reasons are discussed for the lower fluorosis level in the primary dentition and the more severe fluorosis in older age groups as well as the fluorosis severity difference by gender.

Analysis of Variance↗
PubMed1989

Effect of prenatal and postnatal fluoride on the human deciduous dentition. A literature review.

Fluoride passes from the mother to fetal teeth. Much of the fluoride is taken up in secretory enamel, probably by the forming mineral apatite crystals. Some is retained with residual proteins. The low concentration of fluoride in the inner enamel is incorporated mainly during the secretory stage, while the enhanced concentration in the surface enamel is produced during the much longer maturation stage. Mature, hard enamel is generally absent during fetal life. The clinical question is whether prenatal fluoride imparts an additional benefit to the universally accepted effect of postnatal fluoride. In general, surface enamel fluoride levels of deciduous teeth increase with increasing pre- and postnatal fluoride administration. A consistent level of caries protection has been reported with pre- and postnatal administration of fluoride unrelated to the acquisition of fluoride in the surface enamel. Many children develop enamel opacities in their deciduous dentition related by various factors to enamel mineralization disturbances in drinking water areas even low in fluoride. Accumulation of fluoride due to an increased fluoride intake is a feature of fluorosed enamel in the deciduous as well as permanent dentition. The resulting mature fluorosed enamel retains a relatively high proportion of immature matrix proteins onto the crystal surface. The degree of fluorosis of the deciduous dentition is less compared with that of the permanent dentition, due probably to a partial protection afforded by the maternal loss of fluoride, formerly known as the "placental barrier".

Dental Enamel↗
PubMed1989

The effect of fluoride drop administration on dental caries increment--a longitudinal study.

The effect of fluoride drop supplementation was investigated in a longitudinal study initiated in 1980. The def-t and DMF-T indices were used to estimate the incremental caries rate of the deciduous and first molars of 211 children aged 7-8 and 9.5-10.5 years. No statistically significant differences between the experimental and control def-t and DMF-T scores were found after 3 years. The incremental caries rate of the deciduous dentition of the experimental group was found to be significantly lower than that of the control group (def-t = 0.61 and 1.07 respectively), whereas the difference in the caries increments of the first molars was not significant (DMF-T = 1.62 in both groups). It is estimated that the efficacy was due to the long-term cariostatic effect of the topically acting fluoride on the erupting primary dentition, whereas the permanent dentition (first molars) had already completed calcification of the crown, but had not erupted at initiation of the study. It was estimated that the most effective cariostatic benefits would be apparent in the late erupting teeth of this study group.

Child↗
PubMed1986

The uptake of lithium ions by synthetic carbonated hydroxyapatite.

Carbonated hydroxyapatites in the presence of F- and Li+ were synthesized. Limited uptake (0.2-1.6 ppm) of Li+ by the apatites was observed, which was proportional to the initially added Li+ and the carbonate concentration of the samples. Fluoride has retarding effect on the Li+ uptake. Li+ causes a decrease in the solubility of carbonated hydroxyapatite.

Animals↗
PubMed1985

Iron uptake by teeth and bones: a Mossbauer effect study.

Iron uptake (Fe2+ and Fe3+) by bones, teeth, and dental enamel was studied, in vivo and in vitro, by chemical, powder X-ray diffraction and Mossbauer spectroscopy methods. Atomic absorption tests have revealed the permanent uptake of small amounts of iron by dental enamel soaked in vitro in solutions containing Fe2+. Mossbauer spectra show that the iron attached to the dental enamel stays at the same valency it had in the soaking solutions. Mossbauer measurements of in vivo samples show that iron is present in bones and teeth mainly as Fe3+ (10% Fe2+ in teeth), in compound similar to FeOOH. Iron is released or exchanged from teeth at a much lower rate than from bones.

Animals↗