Artificial White Spot Lesions Research Articles

Is the analysis of a QLF measurement reliable and reproducible?

Objective To assess the reliability of the analysis stage of quantitative light-induced fluorescence (QLF). The QLF analysis involves subjective input from the user and this study examines the influence of this on the reproducibility of the QLF data. Method QLF images were taken of 20 human molar teeth that had been previously subjected to a demineralising solution (phosphoric acid 37%) to create artificial white spot lesions on their buccal surfaces. Following examination of the images, 16 were chosen to represent a range of lesion size and severity. Three copies were made of the images and each was allocated a different filename. 10 examiners in three centres were asked to analyse each of the 16 images on three occasions, with at least seven days between each attempt. Simple instructions describing the analysis procedure were supplied and examiners asked to adhere to these directions. Examiners were asked to rate each of the 16 teeth on their first attempt both quantitatively (5 point scale) and qualitatively in terms of difficulty of analysis. Data reported were the δQ at 5% threshold for each tooth on each of three attempts. Results Using ANOVA and paired t-tests to detect statistical differences, the three attempts of each examiner were used to determine intra-examiner reliability. Only one examiner (a novice at the technique) demonstrated differences between all three attempts and two demonstrated difference between one attempt. When the mean scores were compared to determine the inter-examiner reliability, only one examiner's results were statistically different when compared with two others. Conclusion This study has demonstrated that the analysis stage of QLF is reliable between examiners and within multiple attempts by the same examiner, when analysing in vitro lesions. Novices at the technique should be trained before analysing experimental data.

The intra- and inter-examiner reliability of quantitative light-induced fluorescence (QLF) analyses.

To assess the reliability of the analysis stage of quantitative light-induced fluorescence (QLF). The QLF analysis involves subjective input from the user and this study examines the influence of this on the reproducibility of the QLF data. QLF images were taken of 20 human molar teeth that had been previously subjected to a demineralizing solution (phosphoric acid 37%) to create artificial white spot lesions on their buccal surfaces. Following examination of the images, 16 were chosen to represent a range of lesion size and severity. Three copies were made of the images and each was allocated a different filename. 10 examiners in three centres were asked to analyse each of the 16 images on three occasions, with at least seven days between each attempt. Simple instructions describing the analysis procedure were supplied and examiners were asked to adhere to these directions. Examiners were asked to rate each of the 16 teeth on their first attempt both quantitatively (5 point scale) and qualitatively in terms of difficulty of analysis. Data reported were the delta Q at 5% threshold for each tooth on each of three attempts. Using ANOVA and paired t-tests to detect statistical differences, the three attempts of each examiner were used to determine intra-examiner reliability. Only one examiner (a novice at the technique) demonstrated differences between all three attempts and two demonstrated difference between one attempt. When the mean scores were compared to determine the inter-examiner reliability, only one examiner's results were statistically different when compared with two others. This study has demonstrated that the analysis stage of QLF is reliable between examiners and within multiple attempts by the same examiner, when analysing in vitro lesions. Novices at the technique should be trained before analysing experimental data.

Reproducibility of Quantitative Measurement of White Enamel Demineralisation by Image Analysis

The reproducibility of measuring artificial enamel white spot lesions from captured photographic images using computerised image analysis was assessed. Enamel lesions were induced on the buccal surface of 22 human teeth over periods of 3, 7 and 14 days. Standardised photographs were taken from above and below the occlusal plane. These were repeated after 2 weeks. The photographs were converted into TIFF images and mean grey scale levels of the areas of etched enamel were measured using computerised image analysis. Assessment of repeat readings of the same slide showed good reproducibility for photographs taken below the occlusal plane. The limits of agreement showed reasonable agreement between readings carried out on two slides of the same tooth. Capturing TIFF images via 35–mm film and measuring grey scale levels by computerised image analysis is a useful method of quantitative study of early enamel demineralisation. This may be developed for application in the clinical setting.

Purines and ischemic preconditioning in rat hearts

The aim of the study was to evaluate the effect of resin infiltration on colour changes and surface roughness of artificial white spot lesions (WSLs) on maxillary and mandibular premolar.Sixty (60) extracted sound Maxilla (Mx) and Mandibular (Mn) premolars were randomly divided into 2 groups (test and control). Artificial WSLs were produced on buccal surface of teeth and were immersed in artificial saliva for 8 weeks. Colour components (L∗, a∗, b∗) and surface roughness (Sa∗) were assessed on 40 teeth using colour difference meter RD-100 and Alicona® Infinite Focus profilometer respectively. The measurements were done at baseline (T1), directly after artificial WSLs (T2), after 24 hours immersed in saliva and application of resin (T3) and immersion in artificial saliva for 1 (T4), 2 (T5), 4 (T6), 6 (T7) and 8 (T8) weeks. SEM images analysis were carried out on 20 teeth in four time points.The values of L∗ (lightness), b∗ (yellow/blue) and Sa∗ (surface roughness) are gradually reduced to the baseline value. Whereas, the value of a∗ gradually increased with distinct treatment time to achieve the baseline value. The higher value of L∗ and Sa∗, the whiter the lesion suggesting higher degree of enamel demineralization and surface roughness. Lower L∗ values suggest a masking colour effect.The material produced favorable esthetics on colour and the surface roughness of teeth at distinct treatment times. It is recommended to be used to improve WSL post orthodontic treatment.

The Influence of Fluoride-releasing Bonding Composites in the Development of Artificial White Spot Lesions. An Ex Vivo Study

This study investigates the effects of fluoride-releasing bonding composites on the development of artificially created white spot lesions ex vivo. The severity of the lesions was estimated visually using the von der Fehr Caries Index. The integrated mineral loss of the lesions (delta z) was measured using microradiography/microdensitometry. The results of the visual assessment indicated that teeth bonded with Reliance exhibited more Grade 2 lesions than expected. Teeth bonded with Mirage Dual Cure, however, showed a high prevalence of teeth with no lesions (Grade 0) and few with Grade 2. Microdensitometric analysis found 17 subsurface lesions; 14 of these were in the non-fluoridated groups (Right-On and Heliosit), and 3 and 1 in the fluoridated groups (Reliance and Mirage Dual Cure), respectively. Lesion mineral content ranged from 64.93 to 20.43 per cent for Right-On, from 32.53 to 26.72 per cent for Heliosit, from 19.52 to 19.58 per cent for Reliance, and 23.58 per cent for Mirage Dual Cure. The results of this study suggest that fluoride-releasing composites may have a caries preventive effect around orthodontic brackets.

Optical Quantification of Approximal Caries in vitro

A fluorescent dye was applied to extracted premolars with either early artificial lesions or natural white-spot lesions. The teeth were placed in an approximal geometry, and with a specially designed fibre-optic probe the fluorescence of the dye was measured in the lesions. The same fibre-optic probe was used to measure the transmission of light at a wavelength where the dye does not absorb. This transmission of light was used to correct the fluorescence for attenuation by the intermediate layer of sound enamel situated between the probe and the lesion. Both signals varied with time because of the necessary addition of ethanol during the measurement. The mineral loss from the lesions was measured with wavelength independent microradiography (WIM) for the artificial lesions, and the optical caries monitor (OCM) for the natural white-spot lesions. The correlation coefficient between corrected fluorescence and mineral loss was r = 0.86. The results indicate that measurement of dye uptake may be a very sensitive method to diagnose early approximal caries lesions and may enable quantification of these lesions.

Remineralization of artificial caries-like lesions in human enamel in situ by chewing sorbitol gum.

The objective of the study was to determine quantitatively the effect on the potential for in situ remineralization of artificial caries-like lesions in human enamel when sugar-free gum containing mainly sorbitol as sweetener was chewed after meals and snacks. Artificial white-spot lesions were created in extracted human premolars and divided into three parts. One part was used as reference and the other two worn consecutively for two 21-day periods by 10 volunteers in a cast silver band cemented on lower molar teeth and covered with gauze to promote plaque formation. During the experimental periods, the subjects used fluoridated toothpaste twice daily, and consumed three meals (breakfast, lunch, and dinner) and two snacks (selected from chocolate bar, raisins, chocolate wafer, and iced cupcake). Sorbitol gum was chewed for 20 min immediately after each meal or snack during one of the experimental periods. The three parts of the enamel lesions were then sectioned (congruent to 80 microns) and examined together by means of quantitative microradiography and by polarized light microscopy. All estimates of mineral content indicated that significant remineralization occurred and was approximately doubled with gum-chewing. It is suggested that sorbitol gum stimulates salivation, which is responsible for the significantly enhanced remineralization, thus contributing to a therapeutic, caries-preventive effect. Because the gum was chewed immediately after meals and snacks, inhibition of demineralization may also have occurred.

The Formation and Remineralization of Artificial White Spot Lesions: A Constant Composition Approach

Artificial white spot lesions have been prepared on bovine enamel surfaces by the controlled addition of lactate buffer containing methylhydroxydiphosphonate ions. The rates of remineralization have been measured using a constant composition method in solutions of calcium phosphate of low supersaturation. Deposition of new hydroxyapatite solid phase takes place exclusively within the white spot lesion at a rate appreciably slower than that of an acid-etched enamel surface, probably due to the presence of methylhydroxydiphosphonate located within the intact surface region of the lesion.

Effect of soluble calcium on fluoride uptake by enamel from sodium monofluorophosphate.

The fluoride uptake by sound, acid-etched and artificial white spot lesions treated with sodium monofluorophosphate in dentifrice slurries, abrasive slurries, or calcium chloride solutions was determined. Fluoride uptake by sound enamel decreased in the presence of soluble calcium; however, uptake by etched and white spot enamel was greatly enhanced. The optimum Ca:MFP molar ratio was 0.5. Because fluorine-containing dentifrices probably inhibit dental caries by interaction with white spots or at the initial stage of acid-attack, the soluble calcium contained in saliva or a dentifrice might enhance the anti-caries effect of monofluorophosphate.

Effect of fluoridation on lesion depth and microhardness indentations of artificial white spot lesions.

Effect of fluoridation on lesion depth and microhardness indentations of artificial white spot lesions.

Lesion depth and microhardness indentations on artificial white spot lesions.

In this paper the relation between the average lesion depth (1) of artificial carious lesions and the length of microhardness indentations (D) on the surface (the load perpendicular to the surface) is investigated. The results show that an empirical linear relationship does exist between 1 and D for both human and bovine enamel. Linearity has been found for decalcification periods 2–8 days and pH values 4.5 and 4.0. The slope of the curves as well as the load dependency is discussed. The error in the lesion depth determinations is 10–15%. The study also gives a numerical comparison between the average lesion depth in human and in bovine enamel decalcified under the same conditions. After 4 days at pH 4.5 or 4.0, the relations are 1 (bovine) ≈ 1.4 # 1(human) and 1 (bovine) ≈ 1 (human), respectively. The advantage of the technique presented here is that is does not destroy the specimen and is suitable for experiments in in vivo situations.

Microhardness and Densitometric Measurements of the Effect of 4% SnF2Solution on Artificial White Spot Lesions

The effect of differing periods of 4% stannous fluoride treatment at 50 °C on artificial white spot lesions was investigated on cross-sections. Microhardness, densitometric and microprobe measurements were made through the same place on the sections. Both hardness and radiodensity increased significantly after half an hour and reached a maximum after 6h treatment with SnF2 solution. The rate of hardness increase, even in heavily demineralized sections, appears to be superior to that so far achieved using remineralizing solutions. The microprobe results indicated that the increase in radiodensity was linked to the tin uptake. There was, however, no such correlation with the hardness increase, which appears to be due to an alteration in structure.

Hardness tests on sound enamel and artificially demineralized white spot lesions.

The accuracy and reproducability of hardness measurements have been investigated in this study. Sound and demineralized enamel were used as the main test materials. The reproducability of hardness measurements on artificial white spot lesions produced by a hydroxyethyl cellulose/lactic acid demineralizing solution was also investigated on embedded cross-sections. The operator error was found to be less than 5% when reading both steel and enamel indentations. The maximum hardness of the surface layer and the minimum hardness of the subsurface lesion were measured in three positions in each of 10 artificial white spot lesions. An analysis of the results showed that: (a) the hardness values at the same distance from the surface but in different areas of the same lesion were very similar; (b) hardness values between lesions were also very even; (c) the drop in hardness after demineralization was related to the initial hardness of the enamel.