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PubMed2003

Bonded resin sealant on smooth surface dental enamel--an in vitro study.

The aim of this study was to in vitro evaluate the micro leakage of a fissure sealant on sound and demineralized enamel using thermo cycling. The effect of the sealing procedure on sound and demineralized enamel were assessed on human premolars that were divided into one Control group and two Test groups. The Control group served as a baseline reference for the subsequent test procedures. The crowns of five teeth were covered with wax leaving three separate windows on the buccal surfaces. The enamel in one window was acid-etched, in the second window demineralized, and in the third window demineralized and subsequently acid-etched. In Test group 1, containing ten teeth, a defined enamel area on the buccal surfaces was acid-etched and sealed. The sealed area and a border of sound enamel around it were subjected to the demineralizing procedure. In Test group 2, a defined enamel window of 13 teeth was demineralized and subsequently etched and sealed. The sealed area and a border of surrounding enamel were subjected to a new cycle of demineralization. The longitudinal, bucco-lingual sections were examined in polarized light. When placed on acid-etched surfaces, the resin adhered firmly to the enamel with no evidence of demineralization or enlargement of previously demineralized areas underneath the sealants.

Acid Etching, Dental↗
PubMed1997

The effects of microabrasion on demineralization inhibition of enamel surfaces.

Microabraded enamel acquires a highly polished surface of mineralized tissue. The purpose of this study was to determine if microabraded enamel surfaces are more resistant to demineralization. Twenty extracted permanent incisors were used in the experiment. Four treatment modalities were investigated: (1) microabrasion in conjunction with a topical fluoride treatment, (2) topical fluoride treatment, (3) microabrasion, and (4) no treatment. All surfaces, following their respective treatment regimen, were stored in artificial saliva for 2 months and then exposed to an artificial caries system for 5 days. Teeth treated with microabrasion followed by a 4-minute application of 1% neutral topical sodium fluoride exhibited significantly less enamel demineralization when subjected to an artificial caries challenge than did teeth that underwent microabrasion alone, topical fluoride treatment alone, or no treatment at all.

Analysis of Variance↗
PubMed2006

Effect of xylitol:sorbitol on fluoride enamel demineralization reduction in situ.

OBJECTIVES: To evaluate if sugar alcohols would reduce enamel demineralization enhancing the fluoride (F) effect. METHODS: A crossover in situ study was conducted in four phases, during which 10 volunteers were submitted to one of the treatments: (I) Distilled and deionized water, as a negative control; (II) F (226 microg F/ml as NaF; concentration used in commercial mouthrinse); (III) X:S (xylitol:sorbitol 1:3; final concentration 1.6M; 28% of sugar alcohols) and (IV) F+X:S (same final concentration that groups II and III). The volunteers wore palatal appliances containing four bovine enamel blocks of known surface microhardness (SMH), covered with a 'test plaque' of mutans streptococci, which were immersed during 1 min in one of the allocated treatment solutions simultaneously that the volunteers rinsed their mouths with the same solution. After the rinsing the appliances were put in the mouth and after 20 min a cariogenic challenge was made with 20% sucrose solution during 1 min. After further 45 min the 'test plaque' was collected for F analysis, enamel SMH was again determined and the percentage of change in relation to baseline was calculated; F uptake in enamel was also determined. RESULTS: With respect to all the analyses made, the group F+X:S did not differ from the F treatment (p>0.05) and the groups treated with F and F+X:S differed from the negative control (p<0.05). CONCLUSIONS: The results suggest that xylitol:sorbitol may not enhance the effect of fluoride present in mouth rinse on the reduction of enamel demineralization.

Adult↗
PubMed1995

Potential cariogenicity of starches and fruits as assessed by the plaque-sampling method and an intraoral cariogenicity test.

The cariogenicity of starches and fruits was investigated by measuring acidogenicity (plaque sampling) and enamel demineralization. Test foods were oranges, apples, bananas, Cornflakes, Branflakes, Weetabix, Alpen (no added sugar), white bread, wholemeal bread, rice, and spaghetti, with positive and negative controls of sucrose and sorbitol. Plaque sampling indicated that all the foods were less acidogenic than sucrose, but only significantly so (p < 0.05), as follows: maximum drop in plaque pH: all foods; minimum plaque pH reached: Cornflakes, Branflakes, and wholemeal bread; cH area: wholemeal bread. All foods produced enamel demineralization. The low pH of oranges and apples caused more demineralization than sucrose. Overall, the foods were less cariogenic than sucrose, but more than sorbitol.

Adolescent↗
PubMedDate not supplied

Resistance of occlusal fissures to demineralization after loss of glass ionomer sealants in vitro.

Seventy-one caries-free human occlusal fissures were used for this study. Twenty-two fissures were sealed with a glass ionomer sealant (Fuji Ionomer Type III--G-C Dental Industrial Corp., Tokyo, Japan), 24 were widened with a diamond bur and sealed with the glass ionomer sealant, and 25 were left unsealed. After one week, the sealants were removed as completely as possible with a probe. All fissures were demineralized for seven weeks. Sections made from the fissures were examined with a polarizing microscope, and the depths of the fissure lesions were measured. The mean lesion depths for controls, sealed natural fissures, and sealed widened fissures were 143, 93, and 75 microns, respectively. A statistically significant difference was noted between the two experimental groups and the control group (no sealant). The results suggest that fissures sealed with glass ionomer are more resistant to demineralization than control fissures, even after macroscopic sealant loss. This may be the result of the combined effect of fluoride released by glass ionomer and residual material in the bottom of the fissures.

Bicuspid↗
PubMedDate not supplied

An in vitro caries inhibition of photopolymerized glass ionomer liners.

Caries inhibition of traditional chemical cure glass ionomers has been established. The newer photopolymerized glass ionomers demonstrate a different composition that may impair the ability of providing prevention to secondary caries at restoration margins. The purpose of this study was to evaluate the caries inhibition of photopolymerized glass ionomers (Vitrebond-3M Dental Products, Photac Bond-ESPE/Premier Dental Products) compared to a photopolymerized composite resin (Pertac Universal Bond-ESPE/Premier) control. Two standardized Class V preparations were placed in thirty permanent molars, the gingival margin placed below the cementoenamel junction. Equal numbers of preparations were restored with Vitrebond, Photac Bond and Pertac Universal Bond, according to manufacturer's instructions. The teeth were coated with an acid resistant varnish to within 2 mm of the restoration margins. All teeth were subjected to an artificial caries challenge (pH 4.2) for five days, then axial sections of 100 microns were cut longitudinally through the restored margins and photographed under polarized light microscopy. The polarized micrographs were projected onto a digitizing pad, where demineralized areas adjacent to the restoration margins were quantitated. Results demonstrated the mean (+/- S.D.) area (microns2) demineralization 100 microns from the restoration gingival margin to be: Photac Bond 66.1 +/- 27.8; Vitrebond 47.2 +/- 37.2; Pertac Universal Bond 120.9 +/- 66.0. Duncan's multiple range test indicated there was no statistically significant difference in demineralization inhibition between the two photopolymerized glass ionomers Photac Bond and Vitrebond (p < 0.05), but both photopolymerized glass ionomers demonstrated significantly less demineralization than the Pertac Universal Bond composite resin control (p < 0.05).

Dental Caries↗
PubMed2005

Measurement of the severity of natural smooth surface (interproximal) caries lesions with polarization sensitive optical coherence tomography.

BACKGROUND AND OBJECTIVES: Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to image early dental caries. The purpose of this study was to compare the measured reflectivity of natural caries lesions found on smooth surfaces (interproximal lesions) with the mineral loss measured using digital microradiography (DM) in order to determine if PS-OCT can be used as a non-destructive method to measure the severity of dental decay and resolve the internal structure of caries lesions. MATERIALS AND METHODS: A PS-OCT system operating at 1,310 nm was used to acquire polarization resolved images of natural white spot lesions and pigmented lesions on the smooth surfaces of extracted teeth. The integrated reflectivity from lesion areas was compared to polarized light microscopic images (PLM) and to the integrated mineral loss from the same lesion area measured using high resolution DM. RESULTS: The frequently complex internal structure of caries lesions could be resolved with PS-OCT. Such structural information is potentially useful for determining whether or not the lesion is active and progressing or whether it has become arrested and remineralized and does not require intervention. There was a strong correlation between the integrated mineral loss of the caries lesions measured using DM and the integrated reflectivity in the perpendicular polarization axis of the PS-OCT system. CONCLUSIONS: The integrated reflectivity in the perpendicular polarization channel can be used to represent the severity of demineralization in natural early caries lesions. Therefore, PS-OCT has considerable potential as a non-destructive clinical probe of early caries lesions to assess their severity, monitor their progression over-time and potentially assess lesion activity.

Dental Caries↗
PubMed2002

Effect of fluoride varnish on demineralization adjacent to brackets bonded with RMGI cement.

Far too often a less-than-optimal esthetic result occurs after orthodontic treatment due to demineralization of enamel adjacent to fixed orthodontic appliances in patients with inadequate oral hygiene. In vitro studies have shown that a resin-modified glass ionomer (RMGI) cement and a fluoride varnish might help clinicians combat this problem. The purpose of this study was to evaluate, in vitro, the effect of a fluoride-releasing cavity varnish on inhibition of enamel demineralization adjacent to orthodontic brackets bonded with RMGI and composite resin cements. Brackets were bonded to 48 extracted human third molars. Half were bonded with a composite resin (Transbond, 3M Unitek, Monrovia, Calif) and half with an RMGI (Fuji Ortho LC, GC America, Alsip, Ill). Each group was further divided into 2, with half receiving an application of fluoride-releasing varnish (Duraflor, Pharmascience, Montreal, Québec, Canada). The samples were cycled in an artificial caries solution for an hour twice daily for 31 days. After each caries challenge, the teeth were brushed with a soft toothbrush to simulate normal mechanical wear of the varnish. The loss of fluoride varnish was timed. Teeth were sectioned longitudinally and photographed under polarized light microscopy. Mean lesion depth was measured, and analysis of variance (ANOVA) (P <or=.0001) and the Duncan multiple range test (P <or=.05) indicated significant differences among the groups. Teeth bonded with composite resin showed a 35% reduction in mean lesion depth when fluoride varnish was applied. Teeth bonded with RMGI cement showed no significant differences in lesion depth between varnish and nonvarnish groups. Both RMGI groups had 50% smaller mean lesion depths when compared with the composite resin group without fluoride varnish. Samples bonded with RMGI cement illustrated a wedge effect, with lesion depth shallower near the bracket. A chi-square test showed that the fluoride varnish was lost significantly faster in samples bonded with Fuji Ortho LC (P =.013). Although the fluoride varnish could not prevent demineralization, it appears to be beneficial in reducing lesion formation. Clinicians should consider applying fluoride varnish on areas of enamel that exhibit demineralization or are at risk of demineralization in patients with poor oral hygiene.

Acrylic Resins↗
PubMed2003

Quantifying enamel demineralization from teeth with orthodontic brackets--a comparison of two methods. Part 1: repeatability and agreement.

The aim of this investigation was to compare the repeatability of measuring enamel demineralization surrounding an orthodontic bracket using two techniques: computerized image analysis from digitally converted photographic slides and quantitative light-induced fluorescence (QLF). Fifteen human molars were halved and shaped to look like incisors. The teeth were individually numbered and orthodontic brackets bonded to the buccal surface. The crowns were covered with acid resistant varnish, except for windows approximately 1.5 x 3 mm adjacent to the gingival, occlusal, mesial, and distal edges of the bracket. The windows were variously exposed to a demineralizing gel for 0, 3, 7, or 14 days, and the acid resistant varnish was removed. Standardized photographic slides and QLF images of the teeth were taken. These were repeated after 1 week. The slides were converted to grey scale digital format and analysed using Image-Pro Plus 3.0. The QLF images were stored, processed, and analysed using customized software. All images were recoded for blind analysis. The four surfaces of the bracket were inspected and only areas of suspected demineralization were analysed. This was repeated after 1 week. The limits of agreement and mean difference between repeat readings of the area of demineralization were similar for both techniques (-0.04 +/- 0.43 for photographs and -0.10 +/- 0.63 for QLF). Mean grey level (photographs) and mean loss of fluorescence from that area (deltaF) (QLF) showed acceptable limits of agreement. The Intra Class Correlation (ICC) was below 0.81 for the measurement of area from QLF, suggesting that random error needs to be reduced. There was evidence of systematic bias for the repeat readings of the grey levels from the photographs (P < 0.001). Enamel demineralization surrounding an orthodontic bracket can be measured reproducibly using these two techniques.

Bias↗
PubMed1996

The threshold effects of Nd and Ho: YAG laser-induced surface modification on demineralization of dentin surfaces.

Laser irradiation alters the structure of dentin and produces surface layers that give the appearance of being more enamel-like. The laser-modified surface may be more resistant to demineralization; hence, many investigators are proposing continued development of the laser as a possible preventive treatment for caries. The purpose of this study was to explore the morphological changes that occur in dentin when treated at threshold illuminance with two clinically interesting laser wavelengths, and to evaluate the effectiveness of the laser-treated surface at resisting demineralization in an acid-gel solution. The Nd: YAG laser (wavelength 1060 nm) produced significant recrystallization and grain growth of the apatite, without the formation of second phases such as beta-tricalcium phosphate. This recrystallized surface layer showed resistance to demineralization; however, the layer did not provide protection of the underlying dentin from demineralization because of cracks and macroscopic voids that allowed for penetration of the demineralizing gel. The Ho: YAG laser-treated surface (wavelength 2100 nm) did not show significant evidence of recrystallization and grain growth, and only a trace amount of an acid-resistant layer was observed with demineralization. It is speculated that the Ho:YAG laser is coupling with absorbed water, and that the heat transfer from the water to the mineral phase is inefficient. For the purposes of creating a demineralization-resistant layer, threshold illuminance with both Nd: YAG and Ho: YAG was ineffective.

Absorption↗
PubMed1996

[Constant composition study on kinetics of enamel demineralization].

The aim of this work was to investigate the kinetic behaviour of whole enamel demineralization compared with that of powder enamel. Constant composition technique was used to maintain a constant undersaturation degree with respect to hydroxyapatite in the demineralizing solutions. The demineralizing processes were monitored by recording the volume of adding titrant solution. Finally, sections were measured for lesion depth by microradiography, and blocks were tested for microhardness. The results showed that demineralization of enamel powder nearly completed within 40 minutes, while demineralization of whole enamel was much slower and with a constant rate within the experimental time. It was also found there were significant increases of concentrations of calcium and phosphate in solutions during the first 40 hours of whole enamel demineralization. It suggests that the kinetic behaviour of whole enamel demineralization is different from that of powder enamel, which is not only due to the unique transport process in whole tissue, but also possible due to a different phase transformation before and after formation of a surface layer.

Calcium↗
PubMed1996

Clinical and microbiologic evaluation of a resin modified glass ionomer cement for orthodontic bonding.

This study evaluated the clinical performance of a new resin modified glass ionomer cement, Geristore (Den-Mat Corp., Santa Maria, Calif.), for the bonding of orthodontic brackets and its effect on certain caries-associated microorganisms. This cement has been shown to possess increased mechanical properties and long-term fluoride release. There were 716 brackets bonded in 40 patients (17 males and 23 females), with a split-mouth technique and a composite resin, Phase II (Reliance, Itasca, III.), as a control. Bond failures were recorded up to 1 year. Plaque scores and plaque samples were taken from the area of the bonding adhesive in 20 patients, before, at 1 week, and 5 months after the placement of brackets. The plaque samples were investigated for the presence of Streptococcus mutans and lactobacilli. The overall bond failure rate was found to be 8.9% for Geristore and 3.1% for Phase II (p < 0.05). Labially, there was no significant difference (p > 0.05) in bond failure rate: 3.8% for Geristore and 1.7% for Phase II. The proportions of S. mutans and lactobacilli in plaque taken from around Geristore cement were reduced at 1 week and 5 months, when compared with Phase II resin, and this reduction was statistically significant (p < 0.05) at 1 week. Results of this study suggest that Geristore may be of use in the labial segments, especially in caries prone patients, in whom demineralization at debond may present an esthetic and restorative problem several years after treatment.

Adolescent↗
PubMed2005

Microradiographic study on the effects of salivary proteins on in vitro demineralization of bovine enamel.

The aim of this investigation was to evaluate the effects of various proteins on in vitro demineralization of bovine enamel. From each of 100 bovine incisors two samples were prepared. The specimens were embedded in epoxy resin and polished up to 4000 grit. Subsequently, the specimens' surfaces were partly covered with nail varnish, thus serving as control of sound enamel. The specimens were divided randomly into five groups (n = 40) and demineralized in a solution of constant composition (pH 5.0; 10 days). For each subgroup of specimens (n = 10) 4 L were taken and either low (50% of medium conc.), medium, or high (150%) concentrations of the proteins [human albumin (100% conc. = 7 mg L(-1)), mucin (577.5 mg L(-1)), immunoglobulin G (IgG) (46 mg L(-1)), casein isolated from bovine milk (1.2 g L(-1))] or amino acid [l-Proline (7 mg L(-1))] were added to 1 L of the demineralizing solution, whereas 1 L served as control. Mineral loss and lesion depth (LD) were evaluated from microradiographs of thin sections (110 mum) by a dedicated software package (TMR 1.24). No differences were found between the five control groups (P > 0.05; ANOVA). Albumin, l-Proline, and IgG did not affect enamel demineralization, whereas the addition of both casein and mucin resulted in significant reductions of both mineral loss and LDs (P < 0.01; Tukey's test). Within the limitations of an in vitro study, the present investigation indicates that casein and mucin seem to affect enamel demineralization significantly. Thus, these proteins might be helpful as an additive to saliva substitutes or mouthwashes if the quality of saliva is altered.

Albumins↗
PubMed2004

Relationship between S. mutans and the autofluorescence of carious dentin.

PURPOSE: To investigate the relationship between the presence of S. mutans and the autofluorescent signal detected in carious dentin, using confocal laser-scanning microscopy. METHODS: Experiment 1:15 visually caries-free freshly extracted premolars were coated with varnish except for two 2 mm x 2 mm windows; five were subjected to a 15-day bacterial artificial caries system using Streptococcus mutans while 10 underwent a 7-day controlled, lactic acid (0.5 M, pH 2.7) demineralization protocol. At the end of both periods, all teeth were longitudinally sectioned and the 20 bacterial and 40 acid-induced artificial lesions were examined by confocal laser-scanning microscopy. The media containing the S. mutans was also examined for autofluorescence. Experiment 2: 20 750 microm-thick caries-free coronal dentin disks were prepared from 10 healthy premolars. Ten underwent a demineralization protocol using 0.1 M EDTA (pH 4.8) for 21 days. All 20 were finally subjected to the same artificial bacterial caries system as above for 15 days and then examined for autofluorescence using confocal laser-scanning microscopy. RESULTS: Experiment 1 results showed that acid-demineralized lesions did not generate any autofluorescence. Lesions created by the bacterial system did exhibit autofluorescence. The media with or without S. mutans did not exhibit autofluorescence. Experiment 2: bacteria-induced lesions on dentin that had previously been acid-demineralized generated a visibly stronger autofluorescence signal than those lesions grown on sound dentin. It is hypothesized that dentin demineralization during the carious process exposes more matrix to a bacteria-matrix interaction, thus generating or refining the matrix chromophore responsible for the autofluorescence signal detected in carious dentin.

Bicuspid↗
PubMed1998

Effects of acid-etching on the tensile properties of demineralized dentin matrix.

OBJECTIVES: Little research has been done to evaluate the effects of acids commonly used in adhesive dentistry, on the tensile properties of the demineralized dentin matrix. The purpose of this study was to evaluate the effects of a number of acidic conditioners on the ultimate tensile strength (UTS) and modulus of elasticity (E) of human coronal dentin matrix. METHODS: Small hour-glass shaped (for UTS) or l-beam shaped (for determination of E) were prepared from mid-coronal dentin of extracted human third molars. After protecting the ends with varnish, the middle of the specimens was completely demineralized in 0.5 M EDTA (pH 7). UTS was determined by tensile stressing to failure. Modulus of elasticity was calculated from stress strain curves. The results were analyzed by ANOVA and Student-Neuman-Keuls test at the 95% confidence level. RESULTS: Brief (ca. 1-2 min) exposure of demineralized dentin matrix to acids had no measurable effects on its tensile properties. Ten-minute exposures to 2.5% and 17.5% nitric acid lowered (p < 0.05) the UTS compared to phosphate buffered saline (PBS)-exposed controls. Exposure of the decalcified dentin to 10% citric acid containing 3% ferric chloride, 10% citric acid, 37% phosphoric acid or 17.5% nitric acid containing 3% ferric chloride for 10 min had no effect on UTS. None of these acids consistently lowered stiffness. SIGNIFICANCE: The results indicate that relatively long exposures to acids are required to alter the tensile properties of demineralized dentin. It is unlikely that the brief exposures to acids that are used in adhesive dentistry would acutely weaken the physical properties of demineralized dentin. However, long-term studies should be done to determine if such treatment increases the susceptibility of the matrix to hydrolysis.

Acid Etching, Dental↗
PubMed1993

Shrinkage prevention of in vitro demineralized human dentine in transversal microradiography.

The shrinkage of demineralized dentine is a serious problem in the assessment of mineral distributions and mineral changes by means of microradiography. In this article it is shown that a treatment with ethanediol of the thin slices used for transversal microradiography prevents shrinkage for about 1 h. Without this so-called diol treatment, the shrinkage effects in demineralized dentin are about 20% in lesion depth and about 30% in mineral loss (delta Z) after 120-second drying in air. The prevention of shrinkage by diol treatment of dentine lesions is not influenced by the presence of a surface layer.

Dentin↗
PubMedDate not supplied

Assessment of enamel demineralization using conventional, digital, and digitized radiography.

This experimental research aimed at evaluating the accuracy of enamel demineralization detection using conventional, digital, and digitized radiographs, as well as to compare radiographs and logarithmically contrast-enhanced subtraction images. Enamel subsurface demineralization was induced on one of the approximal surfaces of 49 sound third molars. Standardized radiographs of the teeth were taken prior to and after the demineralization phase with three digital systems--CygnusRay MPS, DenOptix and DIGORA--and InSight film. Three radiologists interpreted the pairs of conventional, digital, and digitized radiographs in two different occasions. Logarithmically contrast-enhanced subtraction images were examined by a fourth radiologist only once. Radiographic diagnosis was validated by cross-sectional microhardness profiling in the test areas of the approximal surfaces. Accuracy was estimated by Receiver Operating Characteristic (ROC) analysis. Chi-square test, at a significance level of 5%, was used to compare the areas under the ROC curves (A(z)) calculated for the different imaging modalities. Concerning the radiographs, the DenOptix system (A(z) = 0.91) and conventional radiographs (A(z) = 0.90) presented the highest accuracy values compared with the other three radiographic modalities. However, logarithmically contrast-enhanced subtraction images (A(z) = 0.98) were significantly more accurate than conventional, digital, and digitized radiographs (p = 0.0000). It can be concluded that the DenOptix system and conventional radiographs provide better performance for diagnosing enamel subsurface demineralization. Logarithmic subtraction significantly improves radiographic detection.

Dental Caries↗