Ag Dijkman

In vivo Investigation on the Fluoride Content in and on Human Enamel after Topical Applications

In this in vivo study the amount of fluoride present on and in human enamel was followed longitudinally for a period of 3 months. The fluoridating agents were an APF gel and the fluoridating lacquers

In vivo Remineralization of Plaque-Induced Initial Enamel Lesions – A Microradiographic Investigation

Shallow initial enamel lesions approximately 50 μm in depth were experimentally induced by plaque in sound intact human enamel. The lesions were subsequently remineralized in vivo without any fluoride

Effect of Xylitol and Sorbitol in Chewing-Gums on Mutans Streptococci, Plaque pH and Mineral Loss of Enamel

Seventeen subjects with more than 3 x 10(5) mutans streptococci per millilitre of saliva completed this randomised, cross-over study. Four different chewing-gums, containing: (1) 70% xylitol, (2) 35% xylitol + 35% sorbitol, (3) 17.5% xylitol + 52.5% sorbitol, and (4) 70% sorbitol, were tested. The participants used 12 pieces of each gum per day for 25 days. During the four experimental periods, they wore a removable palatinal plate containing two demineralised enamel samples, and brushed their teeth with a non-fluoridated toothpaste. The results showed that an increased concentration of xylitol in the gum resulted in a lower number of mutans streptococci in both saliva and dental plaque, although the decreases were only significant in the saliva samples (p < 0.01). The pH drop in plaque, measured in vivo after a 1-min mouthrinse with a 10% sorbitol solution, was least pronounced after the 70% xylitol gum and most pronounced after the 70% sorbitol gum period (p < 0.01). No significant differences were found after a mouthrinse with a 10% sucrose solution. All demineralised enamel samples lost mineral during the experimental periods. However, the lesion depth as well as the mineral loss values, assessed microradiographically, did not differ significantly between the four chewing-gums.

FLUORIDE DEPOSITED BY TOPICAL APPLICATIONS IN ENAMEL - KOH-SOLUBLE AND ACQUIRED FLUORIDE

A single topical treatment with three different fluoride-containing systems on human enamel resulted both in an enrichment of the F content in the enamel and an accumulation of F re

Remineralization of Human Enamel in situ after 3 Months: The Effect of not Brushing versus the Effect of an F Dentifrice and an F-Free Dentifrice

The in situ remineralization of 100-microns-deep enamel lesions positioned in a full prosthesis just under the first molar was determined in 13 participants after 3 months. The outer surface of the samples was always flush with the acrylic surface: there was no measurable plaque accumulation on the samples. The effect of not brushing of the samples (A) is compared with the effect of brushing with a nonfluoridated dentifrice (B) or with a fluoridated paste (C) containing 1,250 ppm F. The results show that lesion depth (and mineral loss) data increase by about 50% (case A), do not change statistically in case B and decrease by about 40% in case C. The increase of lesion depth in case A is most likely due to acidic food and/or beverage intake by the participants. With respect to nonbrushing, the remineralization effect of brushing with an F-free paste is about 50% and with the fluoridated paste about 90% in 3 months. It is suggested that the remineralization efficacy of fluoridated pastes is due to the cleaning effect of the brushing by the dentifrice (presumably on the pellicle) as well as due to the fluoride effect on mineral nucleation and growth.

THICKNESS OF ENAMEL LAYERS REMOVED BY HCLO4 ETCHING

The fluoride content of enamel is usually expressed in ppm F- in an enamel layer with a given thickness. A common procedure is to etch away a thin layer of enamel, to measure the F content by solid state electrode and to calculate the enamel layer thickness from the amount of calcium in the etch solution. The layer thickness influences therefore directly the fluoride profiles (F- content vs distance) in enamel.In this investigation, buccal surface areas of permanent human teeth were exposed to 0.1 M perchloric acid for different periods. The resulting distances between the control and acid etched surfaces were determined by both chemical depth determination (dCa) and by an optical depth determination (dOP). These techniques were applied to the same samples. The results show in most cases a statistical significant difference between the two values of interest dCa and d0P; d0P is greater than dCa. Increased exposure times result in larger differences dOP and dCa. For long exposure times d0P is considerably greater than dCa; the difference can be as much as 50%. The reason for discrepancy between optical and chemical depth determination is most likely due to the prism structure of the enamel. SEM pictures on 0.1 M HClO4 etched specimen strongly indicate an increasing roughness of the surface with increasing etching periods.

In vivo Plaque Formation on Enamel Surfaces Treated with Topical Fluoride Agents

Three patients with a partial natural dentition in one jaw and a full denture in the other participated in this study. Enamel treated with APF gel, Duraphat or Fluor Protector and untreated controls were positioned in a full denture for periods up to 3 months. Plaque accumulation on the enamel blocks was evaluated by scanning electron microscopy. The results show that in all 3 patients studied the formation of CaF2 inhibited dental plaque accumulation.

INFLUENCE OF HCLO4 STRENGTH AND ETCHING TIME ON RATE OF ETCHING AND SURFACE-ROUGHNESS OF HUMAN-ENAMEL

The aim of this study was to compare the rate of etching and the surface roughness of HClO4 etched enamel surfaces. The average thickness of the enamel layer removed is a linear function of the total etching period (except for very short periods). The rate of etching (β) in μm s––1 with HCIO4 is strongly influenced by acid strength and stirring rate during etching; it is ∼ 0.02, 0.06, 0.18 and 0.74 μm s––1 for 0.02, 0.1, 0.5 and 2.0 M HCIO4, respectively, β is a linear function of the acid strength. Scanning electron microscopy (SEM) pictures of the specimens show that acid strength, etching time and chemical composition of the enamel are most likely important factors determining surface morphology of etched enamel. A lower acid concentration gives a sharper etch; increasing acid strength causes increasing surface roughness.