1,721,248 research outputs found
Occupational dental erosion from exposure to acids--a review
Full text linkObjective Dental erosion is characterized as a disorder with a multifactorial aetiology including environmental acid exposure. The purpose of this article was to summarize and discuss the available information concerning occupational dental erosion. Methods Information from original scientific papers, case reports and reviews with additional case reports listed in PubMed, Medline or EMBASE [search term: (dental OR enamel OR dentin) AND (erosion OR tooth wear) AND (occupational OR worker)] were included in the review. References from the identified publications were manually searched to identify additional relevant articles. Results The systematic search resulted in 59 papers, of which 42 were suitable for the present review. Seventeen papers demonstrated evidence that battery, galvanizing and associated workers exposed to sulphuric or hydrochloric acid were at higher risk of dental erosion. For other industrial workers, wine tasters and competitive swimmers, only a few clinical studies exist and these do not allow the drawing of definitive conclusions. Conclusion Occupational acid exposure might increase the risk of dental erosion. Evidence for occupational dental erosion is limited to battery and galvanizing workers, while data for other occupational groups need to be confirmed by further studie
The accuracy of electronic working length determination
No full textAim To determine in vivo the accuracy of two impedance quotient apex locators under clinical conditions. Methodology Electronic working length determination was carried out before extraction in 79 human teeth with 93 root canals. In 51 root canals, the determination was performed using the apex locator Justy II(R) (Hager & Werken, Duisburg, Germany); in 42 canals, the apex locator Endy 5000(R) (Loser, Leverkusen, Germany) was used. A root canal instrument was fixed at working length with composite material prior to extraction followed by the exposure of a radiograph. After histological preparation of the apical region, the teeth were examined under a light microscope. The distance of the file tips to the target intervals 'minor foramen - major foramen' and 'apical canal constriction' was determined. These values were compared with the calculated working lengths, determined by radiographic assessment. The data were statistically analysed by a paired t-test. Results For both apex locators and both target intervals, no significant differences between the electronic and radiographical assessments were recorded. The probability of determining the area between minor and major foramen was 82.4% for Justy II and 81% for Endy 5000. However, accurate determination of the apical constriction was only successful in 51% (Justy II) and 64.3% (Endy 5000) of canals. Variation of the inaccurate measurements was higher for Endy 5000 than for Justy II. Conclusions Under clinical conditions, it is possible to determine the region between the minor and major apical foramen with electronic length measuring devices (ELD). However, use of these devices does not result in precise determination of the apical constriction
Ex vivo comparison of two electronic apex locators with different scales and frequencies
No full textAim To compare ex vivo the accuracy of two impedance quotient apex locators with different scales and frequencies of the measuring circuit. Methodology In each root of 193 extracted human teeth, electronic working length determination (ELD) was carried out with a newly constructed measuring unit. In all cases, ELD was performed using the apex locators Justy II(R) (Hager & Werken, Duisburg, Germany) and Raypex 4(R) (VDW, Munich, Germany) on the scale points (sp) 0/0.5/1 of each device. A Miller Needle reaching working length was fixed with composite. The corresponding sp and the differences to the other sp were recorded. After histological preparation of the apical region, the teeth were examined under a light microscope. The distances of the Miller Needle tips to the target intervals 'minor foramen-major foramen' and 'apical canal constriction' (apical constriction) were determined for each sp for both devices. The data were statistically analysed by a chi-square test. Results Precise determination of the target interval 'minor foramen-major foramen' was successful with Raypex 4 in 94.8% (sp 1), 90.7% (sp 0.5) and 72.5% (sp 0) of cases and with Justy II in 59.6% (sp 1), 92.2% (sp 0.5) and 68% (sp 0) of cases. No measurement carried out by Raypex 4 and by Justy II on sp 1 was beyond the major apical foramen. However, on sp 0.5, there were eight measurements for Raypex 4 and four measurements for Justy II beyond the major apical foramen. Overinstrumentation was also recorded for sp 0 in 49 specimens (Raypex 4) and 59 specimens (JustyII). The major apical constriction was met exactly by Raypex 4 in 50.7% (sp 1), 14% (sp 0.5) and 5.2% (sp 0) of cases and by Justy II in 32.1% (sp 1), 23.8% (sp 0.5) and 4.1% (sp 0) of cases. The differences between the determination made with the sp suggested by the manufacturers for Raypex 4 (sp 1) and Justy II (sp 0.5) were not significant (P > 0.05) for the target interval 'minor foramen-major foramen' and significant (P <= 0.05) for the apical constriction. The differences between the sp of each device were significant (P <= 0.05) for both target intervals. Conclusions It is possible to determine the region between the minor and major apical foramen with electronic apex locators ex vivo. The best results were obtained using the sp advised by the manufacturers. Raypex 4 gave the best results on sp one without any measurement beyond the apical foramen. Use of ELD does not result in precise determination of the apical constriction
Impact of brushing force on abrasion of acid-softened and sound enamel
No full textObjective: The study aimed to analyse the effects of different brushing loads on abrasion of acid-softened and sound enamel surfaces. Design: Sound and acid-softened surfaces of each 10 human enamel samples were submitted to brushing abrasion in an automatic brushing machine at 1.5 N (A), 2.5 N (B), 3.5 N (C) or 4.5 N (D) brushing load. Prior to abrasion, demineralisation of half of each enamel surface was performed by storage in hydrochloric acid (pH 2.0) for 60 s. Brushing was carried out (1000 strokes) using a manual toothbrush and toothpaste slurry in a ratio of 1:3. Enamel loss was measured after 10, 20, 50, 100, 150, 200, 250, 300, 350 and 1000 brushing strokes (BS). Pre- and post-brushing values of Knoop indentation length (5 indentations each sample) were measured and mean enamel loss was calculated from the change in indentation depth. Within- and between-group comparisons were performed by ANOVA and t-test followed by Bonferroni-correction. Results: Enamel loss of acid-softened surfaces was significantly influenced by the brushing load applied and was mostly significantly higher in group D (10-1000 BS: 225-462 nm) compared to A (10-1000 BS: 164-384), B (10-1000 BS: 175-370 nm) and C (10-1000 BS: 191396 nm). Abrasion of acid-softened enamel was fourfold higher compared to sound surfaces. Sound enamel was significantly influenced by the brushing force at 20-200 brushing strokes only, but revealed no significant differences between groups A-D. Conclusion: Brushing load influences abrasion of briefly eroded enamel, but might be of minor importance for abrasion of sound enamel surfaces. (c) 2007 Elsevier Ltd. All rights reserved
Effect of different fluoridation regimes on the microhardness of bleached enamel
No full textPurpose: This in vitro study evaluated the effects of toothpaste fluoridation and toothpaste plus gel fluoridation and influence of the time period of fluoride gel application on the microhardness of bleached enamel. Methods: Ninety bovine enamel samples were distributed among nine groups (A-I), each having 10 samples. Half of each surface was bleached with 10% carbamide peroxide gel (8 hours/daily) for 14 days, while the remaining surface was not bleached and served as the control. Groups A-H were fluoridated with toothpaste twice daily throughout the experiment (42 days) and assigned to fluoride gel treatment during the prebleaching period (14 days), during the bleaching period and/or during the post-bleaching period (14 days): A: prior, B: during, C: post, D: prior+during, E: during+post, F: prior+post, G: prior+during+post, H: no gel. Group I was neither fluoridated by toothpaste nor gel. The Knoop microhardness (KHN) of each specimen was determined at baseline, after pre-bleaching (day 14), after bleaching (day 28) and after postbleaching (day 42). Statistical analysis of the percentage of change at baseline KHN was performed by ANOVA and t-test (p<0.05). Results: Bleaching led to a significant decrease of KHN in Group I (unfluoridated) compared to Groups A-H, where microhardness did not fall below baseline values. Fluoridation treatment in Groups A-H increased microhardness in bleached and unbleached samples, but additional supplementation of fluoride gel in Groups A-G was not superior to toothpaste fluoridation only (H). After the post-bleaching period, the microhardness of the bleached and unbleached surfaces was not significantly different in Groups A-H. Conclusion: Regular toothpaste fluoridation prevents microhardness loss due to bleaching treatment in vitro. The additional supplementation of fluoride gel did not enhance the beneficial effect of toothpaste fluoridation, and microhardness was not influenced by the time period of gel fluoridation
In vitro evaluation of abrasion of eroded enamel by different manual, power and sonic toothbrushes
No full textThis study aimed to evaluate the susceptibility of eroded enamel to brushing abrasion performed by manual, power or sonic toothbrushes. Bovine enamel samples were subjected to 5 cycles, each consisting of 5 min demineralisation, 15 min remineralisation and 10 min brushing in a machine. Toothbrushing with the activated electric devices was supplemented with 20 linear strokes/ min. Furthermore, enamel specimens were brushed with 20 linear strokes/ min or 80 linear strokes/ min with the electric toothbrushes without their individual operating action. A manual brush was applied at 100, 20 or 80 linear strokes/ min. Specimens of the control group were not brushed after demineralisation. Loss of enamel was determined by profilometry. For all groups, substrate loss for linear brushing treatment applying 20 or 80 strokes/ min did not differ significantly from the control (4.97 +/- 1.49 mu m). Three power toothbrushing treatments significantly increased abrasion compared to linear brushing treatment with 20 or 80 strokes/ min in their inactivated condition. The results indicate that brushing treatment with power or sonic toothbrushes may lead to significantly higher loss of demineralised enamel compared to toothbrushing without power or sonic support. Copyright (C) 2006 S. Karger AG, Basel
Comparative fluorescence spectroscopy of root caries lesions
No full textIn this study, the light-emission properties of carious and sound root surfaces were investigated under a wide range of excitation wavelengths. Human molar teeth with exposed root surfaces containing light- and dark-discolored root caries (n = 3 of each) were selected. Emission spectra were recorded from carious and corresponding sound root surface areas from each tooth by using a fluorescence spectrophotometer at excitation wavelengths from 360 nm up to 580 nm, in steps of 20 nm. The spectra were corrected for fluctuations in detector sensitivity and excitation light intensity, and normalized to peak intensity. Excitation spectra were recorded for selected emission wavelengths that showed maximum intensity. Light- and dark-discolored root surface caries showed distinct fluorescence emission bands between 600 and 700 nm that were not present in sound root surface areas. These bands were strongest for excitation wavelengths between 390 and 420 nm. The excitation spectra of root caries revealed maximum excitation at around 405 nm, which is equivalent to the Soret band of porphyrin compounds. The emission spectra of both types of root caries lesions were shifted towards longer wavelengths (red shift at half maximum) when compared to the spectra of corresponding sound root surfaces. The red shift for dark-discolored root caries was higher than for light-discolored lesions at all excitation wavelengths
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