Direct measurement of stain retention in third molars.

AIM: To directly determine the mass of dye retained in teeth following exposure to aqueous solutions of Rhodamine B and to correlate tooth color modifications. MATERIALS AND METHODS: Extracted third molars (25) were selected and sectioned at the cementoenamel junction for coronal staining. Pulp tissue was removed and teeth sonicated to remove debris. Teeth were kept in deionized water for 12 hours and subsequently weighed. They were then stained for 4 hours in 5 ml of Rhodamine B dye at two different concentrations. The samples were then subjected to two 8 hours rinses in deionized water. The tooth shade was recorded with a commercially available intraoral spectrophotometer (Vita Easyshade Compact, Vita Zahnfabrik, Bad Säckingen, Germany) at baseline (T1), after dye immersion (T2), and after water rinsing (T3). A standard absorption curve was then used to calculate the dye mass in the rinse solutions as well as the post- treatment stain solutions. All solution optical absorption curves were recorded using a laboratory research spectrophotometer (Cary 300, Agilent, USA). The mass of dye in each solution was then calculated from the standard curve relating optical absorption to aqueous dye concentration. RESULTS: An average change in the CIE (a) values of 8.0 ± 0.3 were observed for concentrations of Rhodamine B similar to the optical appearance of wine or other darkly colored juices while an increase of 10× in concentration gave values too high to measure using a standard intraoral spectrophotometer. By measuring the optical absorbance of the staining solutions before and after the staining process, we were able to measure dye retention of 54 ± 26 micrograms per gram of tooth. CONCLUSION: While no significant correlation could be found between the amount of stain retention in the dentition and the tooth shade due to the high uncertainties in the spectroscopic measurements, we were able to show that this method should admit such comparisons for future research. CLINICAL SIGNIFICANCE: The development of a reliable chromophore infiltration model may provide standardized and reproducible results in evaluating tooth whitening efficacy.

Discoloration of teeth from tetracyclines--even today?

The aim of this study was to examine whether brownish crown and root discoloration of wisdom teeth was related to treatment of acne with tetracyclines. For this purpose, 17 discolored third molars from nine patients were embedded without being decalcified, ground along the tooth axis, and examined using fluorescence microscopy. A thorough medical history served to determine the start and duration of any administration of tetracyclines. This confirmed the use of drugs against acne containing minocycline in all cases except one. The microscopic analyses of all teeth revealed intensely fluorescent bands in the dentin, which corresponded to the mineralization front at the time of tetracycline intake. More or less uniform discoloration of the entire crown was seen in association with treatment against acne prior to the completion of crown formation at the age of about 15 years. This uniform staining can be attributed to incorporation of minerals during ongoing maturation of the occlusal enamel, which is concomitant with the formation of the cervical crown regions. When acne was treated between 15 and 22 years of age, only the roots of the third molars displayed annular discolorations, which seemed to result from the incorporation of tetracyclines into dentin, while fine fluorescent incremental lines in root cementum were too thin to be apparent clinically. Three accidentally removed interradicular bony septa revealed that tetracyclines incorporated into alveolar bone remained there for about 2 years, but thereafter disappeared as a result of physiological remodelling.

Salivary proteins interact with dietary constituents to modulate tooth staining.

Dietary components rich in polyphenols-for example, tea and red wine-are thought to cause tooth staining. In the present study, hydroxyapatite was used as a model of enamel for study of the influence of salivary proteins on the binding of different polyphenols to hydroxyapatite in vitro. Neither salivary protein pellicles nor salivary proteins in solution significantly altered the binding of the small polyphenol epigallocatechin to hydroxyapatite. However, hydroxyapatite binding of anthocyanin, a small grape-skin-derived polyphenol, or the larger polyphenols of black tea was increased by the presence of salivary proteins, either as a pellicle or in solution. Proline-rich proteins were enriched from parotid saliva and found to increase binding of anthocyanin and black tea polyphenols to hydroxyapatite, while enriched histatins did not increase binding. It is concluded that some salivary proteins, including proline-rich protein, can mediate increased staining of enamel by red-wine- and black-tea-derived polyphenols.

Discoloration of dental carious lesions (a review).

The discoloration of dental carious lesions is a marked feature which has received relatively little attention from dental researchers. In this short review, possible causes are considered: the formation of Maillard pigments, melanins, and lipofuscins, and the uptake of food dyes, metals, and bacterial pigments. It is concluded that the Maillard reaction between proteins and small aldehydes produced by bacteria probably accounts for the discoloration.

Experimental bilirubin pigmentation of rat dentine and its detection by a qualitative analytical method.

An animal model of bilirubinemia was used to determine whether bilirubin present in pigmented teeth can be extracted and qualitatively analysed. The bile ducts of 10 Long-Evans Agouti rats were ligated and bilirubin (14 mg/kg per day) was injected intraperitoneally for 4 days. When the animals were killed 2 weeks later, pigmented lower incisors were observed in three animals. These teeth were dried, powdered and bilirubin was extracted with chloroform/methanol/acetic acid, 30:10:0.5, v/v for 10 min under sonication. After centrifugation, the supernatant was collected and evaporated. The residue was dissolved in chloroform and its absorption spectrum measured before and after diazo reaction. This resulted in a shift of the absorption maximum from 450 to 540 nm and indicated the presence of bilirubin in pigmented teeth. No bilirubin was found in the lower incisors of untreated control rats. This technique may be useful in distinguishing bilirubin staning from other intrinsic discolorations of teeth.

Tetracycline staining of wisdom teeth.

Tetracycline hydrochloride given by mouth for acne vulgaris was found to be deposited in the amelogenetic region of developing wisdom teeth.

The chemistry and mechanisms of extrinsic and intrinsic discoloration.

The literature on the methods of removing dental stain and whitening teeth is extensive. By comparison, little has been published on the chemical mechanisms that cause dental discolorations. This article proposes a classification for extrinsic dental stain and describes the chemical mechanisms involved in causing tooth discolorations. It also discusses the current theories of the chemistry of stain removal processes.

Effective tooth-bleaching protocols capable of reducing H(2)O(2) diffusion through enamel and dentine.

OBJECTIVES: To evaluate the effects of experimental protocols on bleaching effectiveness and hydrogen peroxide (HP) diffusion through enamel and dentine. METHODS: Enamel/dentine discs were subjected to six bleaching sessions, consisting of 1 or 3 applications of 17.5% or 35%-HP gel for 5/15min, or 37% carbamide peroxide (CP) gel for 10/20min. Discs undergoing the regular protocol (35%-HP; 3×15min) constituted the positive control group. Colour change (ΔE) was assessed (CIE L*a*b* system) after each session. HP diffusion was quantified (sessions 1, 3, and 6) in enamel/dentine discs adapted to artificial pulp chambers. Data were analysed by Pillai's Trace and Bonferroni test, or by one-way ANOVA and SNK/Tamhane's test (α=5%). RESULTS: All tooth-bleaching protocols significantly increased the ΔE values. A reduction in HP diffusion and no significant difference in ΔE compared with the positive control were observed for the following bleaching protocols: 17.5%-HP 3×15min, at the 4th session; and 35%-HP 1×15 and 3×5min, at the 5th session. HP diffusion in the 37%-CP 3×20min bleaching protocol was statistically similar to that in the positive control. The other experimental bleaching protocols significantly decreased HP diffusion through enamel/dentine discs, but the ΔE values were statistically lower than those observed in the positive control, in all sessions. CONCLUSION: Shortening the contact time of a 35%-HP gel or reducing its concentration produces gradual tooth colour change and reduced HP diffusion through enamel and dentine. CLINICAL SIGNIFICANCE: A reduction in HP concentration, from 35% to 17.5%, in a bleaching gel or shortening its application time on enamel provides a significant tooth-bleaching improvement associated with decreased HP diffusion across hard dental tissues. Therefore, these protocols may be an interesting alternative to be tested in the clinical situation.

Mineral content in teeth with deciduous molar hypomineralisation (DMH).

OBJECTIVES: We report the mineral (hydroxyapatite) density of sound and opaque areas in DMH molars with sound parts of (carious) deciduous teeth serving as controls. METHODS: Twenty-nine extracted second primary molars obtained from 15 children were studied. Thirteen of these molars were DMH molars with yellow opacities, seven were DMH molars with white opacities, three DMH molars with brown opacities and eleven were molars without DMH. Prior to microCT scanning, the teeth were mounted in impression material (Impregum(®)) and stored in water with a thymol crystal. Spot analysis and line scans were performed in areas with opacities and in sound areas. An ANOVA test and t-tests were used to test if there were significant differences between the groups. RESULTS: The average densities of the hydroxyapatite in yellow and brown opacities (1368mg HA/cm(2) and 1407mg HA/cm(2), respectively) were significantly lower than in clinically unaffected enamel (1747mg HA/cm(2)) of DMH molars or of sound molars (1758mg HA/cm(2)). The mineral density in white opacities (1737mg HA/cm(2)) was not different from that in the enamel of sound molars. The mineral density values in yellow and brown enamel opacities were in between those of dentine (1018mg HA/cm(2)) and enamel. CONCLUSIONS: DMH molars with yellow or brown opacities had a 20-22% lower mineral density in the hypomineralised enamel compared with sound molars. White opacities do not show a lower mineral content. The reduction in enamel mineral content in DMH molars stressed the need for a preventive approach in DMH.

Affinity interactions between natural pigments and human whole saliva.

OBJECTIVE: The aim of the present study was to assess the null hypothesis that there are no differences of affinity between pigments and human whole saliva (WS), and the affinity is not influenced by the functional groups of pigments, temperatures, pH values, and salt concentrations. METHODS: The affinity constants of interactions between WS and theaflavin (TF)/curcumin (Cur)/cyanidin (Cy) were determined by surface plasmon resonance (SPR) and fluorescence quenching. Mass-uptake at various temperatures, pH values, and salt concentrations was also carried out. RESULTS: The order of affinity of the pigments binding to WS is TF>Cur>Cy. A large number of complexes and precipitations of pigments/proteins were formed through a quick, strong, and almost irreversible binding process. The mass-uptake of pigments was affected not only by the functional groups, but also by molecular weight of pigments, temperatures, pH values, and salt concentrations. CONCLUSION: The complex of pigments may easily and rapidly deposit onto the WS film, and are difficult to remove from the WS surface. However, the complex of pigments can be reduced by properly regulating the physicochemical conditions, such as temperatures, pH values, and salt concentrations.

An in vitro model of chlorhexidine-induced tooth staining.

BACKGROUND: Tooth staining is a common feature of chlorhexidine treatment for periodontal disease and there is a large variation between patients as to the degree of their tooth staining. Although the mechanism of tooth staining is uncertain, diet, smoking and oral hygiene appear probable factors. OBJECTIVES: This study investigated the role of saliva in chlorhexidine-induced tooth staining and used tea as the staining agent in an in vitro model with hydroxyapatite mimicking teeth. METHODS: Saliva has been used to create an acquired pellicle and in solution to mimic its effects in vivo. Using different combinations of tea, chlorhexidine and parotid saliva, substances binding to hydroxyapatite were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Using this system, tea, chlorhexidine and salivary proteins were clearly identifiable following staining by Coomassie Brilliant Blue. RESULTS: The results indicated that tea interacted with many salivary proteins, in particular proline-rich proteins and histatins. Chlorhexidine did not appear to complex with or precipitate salivary proteins nor prevent the formation of an acquired pellicle on the hydroxyapatite. In isolation, tea and chlorhexidine bound in small amounts to hydroxyapatite, but when added in combination, binding of both to hydroxyapatite was greatly increased. The acquired pellicle reduced chlorhexidine and tea binding, but conversely increased the binding of either tea or chlorhexidine alone to hydroxyapatite. CONCLUSION: In conclusion, salivary proteins play an important role in the staining process and the combination of tea and chlorhexidine appears to be a very potent staining factor.

Discoloration of dental pellicle by tannic acid.

The ability of tannic acid to discolor pellicle was studied in vitro and in vivo. Freshly extracted teeth were submerget in solutions of tannic acid, and in the clinical study individuals rinsed three times daily with 0.1% or 0.2% tannic acid. It was fount that 0.2% tannic acid caused brownish discolorations within 10-12 days both in vitro and in vivo. Discolored pellicle material collected from the in vivo test group was shown to contain furaldehyde after hydrolysis. The origin of the furaldehyde is not ascertained, but could be due to the presence of dietary deposits, transformation of pellicle pentoses, or from reactions between reducing sugars and amino compounds.

Ion probe analysis of discolored areas in the enamel of deciduous teeth.

Discolored and normal areas in the enamel of eleven primary teeth from children born to diabetic mothers were analysed with ion probe technique. These teeth were compared with four teeth from children born to healthy mothers. Fourteen different mass numbers were recorded. The affected areas showed a proportionally higher content of organic material, but the differences in recorded values reached statistical significance only in the postnatal enamel. The study revealed a considerable biological variation in the chemical composition of deciduous tooth enamel. The brown areas may be partly related to variation in physical properties.

Adsorption from black tea and red wine onto in vitro salivary pellicles studied by ellipsometry.

The adsorption of black tea and red wine components onto a pellicle-like protein layer formed in vitro by adsorption from whole unstimulated saliva on hydroxyapatite discs were studied by in situ ellipsometry. It was found that components from black tea readily adsorbed to the pellicle. Subsequent exposure to saliva led to further adsorption of salivary components to give an overall increase in the amounts adsorbed. The amounts adsorbed increased still further following a third tea and saliva exposure. Components of red wine gave significantly greater amounts of adsorption to the pellicle than black tea. The adsorption of components of black tea gave a concomitant increase in colour or stain as measured by a reflectance chromameter. In all cases, the black tea- and red wine-modified pellicles were not eluted by either phosphate buffer or sodium dodecyl sulphate (SDS) rinses. Thus, black tea and red wine components have been shown to have a profound effect on in vitro pellicle maturation, causing thickened layers of stained material to build up, which are not readily removed.