Radio-opaque nanosized bioactive glass for potential root canal application: evaluation of radiopacity, bioactivity and alkaline capacity.

AIM: To produce novel nanosized bioactive glass particles with radio-opaque properties and high alkaline capacity and to evaluate their performance as a potential bioactive root canal dressing or filling material. METHODOLOGY: Flame spray-derived bioactive glass particles in the nanometre range were produced including bismuth oxide as a radiopacifier. Calcium hydroxide, barium sulphate and bismuth oxide served as controls. Corresponding materials were compressed to obtain dense specimens with increased alkaline capacity. Radiopacity was evaluated, and in vitro bioactivity was monitored using Raman spectroscopy and scanning electron microscopy. Leaching of bismuth was controlled using atomic absorption spectroscopy. RESULTS: Bioactive glass particles with up to 50 wt% bismuth oxide revealed radiopacity with an equivalent of 4.94-mm aluminium. The introduction of bismuth into the bioactive glass altered the alkaline capacity and the in vitro bioactivity only for high bismuth oxide quantities. Bismuth oxide leaching out of the glass matrix was hardly detectable. CONCLUSION: Bioactive glass can be modified with bismuth oxide to become radio-opaque.

Composites made of flame-sprayed bioactive glass 45S5 and polymers: bioactivity and immediate sealing properties.

AIM: To engineer systems using polyisoprene (PI) or polycaprolactone (PCL) and nanometric bioactive glass 45S5 (BG) that could create a hydroxyapatite interface and thus ultimately make the use of an endodontic sealer unnecessary. METHODOLOGY: Different composites using PI or PCL as matrix material were prepared with BG contents of up to 30 wt%. Unfilled PI and PCL, commercially available filled PI (Obtura gutta-percha) and PCL pellets (Resilon) served as control materials. Bioactivity (in vitro precipitate formation in simulated body fluid) was investigated using scanning electron microscopy and X-ray diffraction analysis. To test immediate sealing ability, simulated root canals were filled with heated materials, and dye leakage was assessed. Leakage was statistically compared between groups using Kruskal-Wallis analysis of variance followed by Mann-Whitney U tests and Bonferroni correction. The alpha-type error was set at 0.05. RESULTS: Both composite systems revealed hydroxyapatite formation on their surface. This was not observed on control materials. Incorporating 30 wt% BG into PI and PCL significantly (P < 0.05) improved their immediate sealing ability compared to that of unfilled polymers, so that dye leakage in simulated root canals was prevented completely. CONCLUSION: Polyisoprene and PCL composites with BG showed promising results as single root canal filling materials. Incorporation of BG fillers into the polymers under investigation made the resulting composite materials bioactive and improved their immediate sealing ability.

Relationship between nanohardness and mineral content of artificial carious enamel lesions.

The aim of this study was to compare cross-sectional nanohardness, measured using an ultra-microindentation system, with mineral content, from transversal microradiography, of artificial enamel caries lesions. Sections (85 +/- 10 microm) from 16 bovine enamel samples with artificial caries were prepared. The mineral content and cross-sectional nanohardness at known depths from the surface were compared. Both methods showed lesion profiles with a surface layer. The determination of nanohardness seems limited to lesions with a mineral content >45 vol%. There was a moderate linear relationship between mineral content and the square root of nanohardness (R2 = 0.81). It was concluded that the conversion of cross-sectional hardness into mineral content remains questionable and cannot be recommended.

Caries prevalence in 2-year-old children in the city of Zurich.

OBJECTIVES: To establish caries prevalence in 2-year-olds in the city of Zurich; and to investigate the relationship between caries prevalence and dietary habits, and oral hygiene practices in native children and children with immigrant background. METHOD: 1,000 randomly selected 2-year-olds were invited to participate in a clinical examination, at which parents were interviewed about the child's oral hygiene and dietary habits. Caries diagnosis was based on visual inspection of all tooth surfaces and included both initial (d1) and cavitated (d2) lesions. Univariate and multivariate logistic regressions for two subgroups of children (children of Swiss and foreign-born mothers) were performed in order to assess the association between predictor variables and caries. RESULTS: 771 children were examined (participation rate 78%; mean age 2.4 years (age range 2.06-2.90 years)). Although the majority (94%) was born in Switzerland, 61% of children had immigrant backgrounds (mother not born in Switzerland). Cavitated teeth (d2mft) were observed in 12.6% of children (95% CI: 10.4-15.1%). Caries including initial lesions (dl2mft) affected 25.3% of children (95% CI: 22.4-28.5%). There were 34 (4.4%) children with severe caries (all maxillary incisors cavitated). For children with caries, the mean d2mft was 4.3 (+/- 2.8). Children with foreign-born mothers (mothers not born in Switzerland) exhibited a significantly higher caries prevalence than those with Swiss-born mothers (17.4% versus 5.0% with d2mft > 0). CONCLUSIONS: Children with foreign-born mothers exhibited significantly higher caries prevalence rates than those with Swiss-born mothers. Poor oral hygiene and night-time bottle use were identified as risk indicators for caries in all children. Further risk indicators identified in children of foreign-born mothers were a preference for sugar-containing non-milk drinks, no pacifier use, child's age and male gender.

Comparison of three different methods for measurement of plaque-pH in humans after consumption of soft bread and potato chips.

Three different techniques for measurement of plaque-pH--the sampling, the microtouch, and the telemetric methods--were compared after subjects had consumed different starch products. Ten volunteers, equipped with partial lower prostheses, incorporating a miniature glass pH electrode, refrained from toothbrushing for 3 days. Four products were tested: (1) soft bread, (2) potato chips, (3) 5% starch, and (4) 5% sucrose. The pH of plaque was measured for 45 min by means of all three of the methods. The results showed that the mean pH at 10 min was 1.5 units lower with the telemetric than with the sampling method and 1.0 unit lower with the telemetric than with the microtouch method. Relatively small differences were found among the effects of the four test products for all three methods, with the clearest distinctions among the pH curves being with the microtouch and telemetric methods. The main conclusions from the present investigation are: (1) that there were large differences in pH levels measured with the sampling, the microtouch, and the telemetric methods, even though they ranked the test products in about the same order, and (2) that the two starchy foods, bread and potato chips, were both easily fermented by dental plaque.

Palatal taste buds in man: topographical arrangement in islands of keratinized epithelium.

In an attempt to find and reconstruct the exact anatomical correlate of taste sensitivity in the human soft palate, a novel approach was used to examine the mucosal surface in conjunction with serial tissue sectioning. Six human subjects, 15 to 29 years of age, 3 females and 3 males, served to take precision impressions of the hard and the anterior soft palate, using non-commercial trays and a self-curing resin. From these impressions, replicas were cast in Epon and subsequently sputter-coated with gold and examined in a scanning electron microscope. In addition, one biopsy was taken from one of the volunteers, in an area including taste bud-suspicious elements. It was found that the anterior soft palate mucosa included 10 to 30, oval to round, site-exotic islands, about 0.2-0.6 mm in diameter, which were covered by a thin, keratinizing stratified squamous epithelium. These islands occurred mainly in an area located in the central part of the soft palate, immediately posterior to the hard/soft palate boundary. The keratinizing epithelium of such islands carried four to seven taste buds which were lacking elsewhere. These islands were formed by a large, mushroom-like connective tissue papilla penetrating most of the site-specific mucosal epithelium, with its cover of keratinizing epithelium, forming sharp external and internal cell-to-cell borderlines with the surrounding, non-keratinizing stratified squamous epithelium. These findings are discussed in relation to induction phenomena necessary to form such islands, and to the variable taste sensitivity detected clinically in this region.

A new reinforced intracoronal composite resin splint. Clinical results after 1 year.

An intracoronal technique for semipermanent splinting of mobile or migrating teeth is described and clinically evaluated. Circumferential grooves of 1 to 1.5 mm depth were cut into the enamel in the occlusal third of the teeth to be splinted. The teeth were splinted by placing a polyester ligature in two or more figure-8 loops along the grooves, and sealing the grooves and interproximal contact areas with an acid-etch composite resin system. A total of 51 splints involving 183 teeth and 132 interproximal contact areas were placed in 34 patients. One year after insertion, 46 splints were found intact. Five splints presented with one fractured interdental element, each. Average mobility of the splinted teeth was 51% below the preoperative level. Splinting improved the masticatory comfort. The esthetic results were satisfactory.

Prevalence and quality of endodontic treatment in an elderly urban population of Switzerland.

Little oral health data on the elderly are available in Switzerland. This study assessed endodontic findings in 66-yr-old residents of the city of Zurich using intraoral radiographs. Of the 143 volunteers having a total of 2004 natural teeth, 78% had at least one endodontically treated tooth. Twenty percent of all teeth were root filled, two thirds of them being in the upper jaw. Sixty-four percent of the root fillings were judged insufficient and 8.5% of all teeth showed periapical radiolucencies, most of the latter (73%) being associated with insufficient root canal treatments. Ninety-eight percent of the root-filled teeth had intracanal retentive devices. Fifty-two percent of the teeth with insufficient root fillings were judged not to need revision, 37% needed revision, 9% needed apicectomy, and 2% were ready for extraction. The considerable endodontic treatment needs of the elderly can only be reduced by an improvement of quality of initial endodontic treatment.

A critical comparison of dentifrice abrasion scores on dentine recorded by gravimetric and radiotracer methods.

Dentifrice abrasivity on dentine is conventionally ranked by various in vitro methods. The abrasivity of selected dentifrices in Switzerland was ranked in 1985 by the gravimetric and in 1989 by the radiotracer method. Because same-named brands of dentifrices were differently ranked by these methods, Swiss clinicians were unsure which ranking to follow. This paper lists the errors known to occur in both techniques, but unfortunately it is difficult to quantitate the magnitudes of these errors. Consequently, it is impossible to determine which method yields the more reliable results. Thus, researchers should look into the problem of dentifrice abrasion scores and try to formulate tests which could simplify the selection of brand-named dentifrices by clinicians and the consumers.

Enamel remineralization: how to explain it to patients.

The term remineralization of initial enamel caries is frequently used, but mainly at research conferences and in lecture rooms. Clinicians avoid discussing remineralization and white-spot enamel lesion formation with patients because details of the processes are complex. Patients, therefore, incorrectly assume that cavitation occurs right at the onset of caries and that a restoration must be placed to halt further progression of the lesion. Although laboratory and clinical studies have shown that initial white-spot enamel lesions can remineralize, patients have little or no access to this information. The schematic diagrams in this paper explain the diffusion of organic acids from plaque between enamel crystals, the partial loss of mineral from enamel crystals, and subsequent demineralization and remineralization that produces the white-spot lesion. Further, these diagrams may help clinicians explain remineralization as simply as possible to patients who present with white-spot enamel lesions.

Self-adjusting abrasiveness: a new technology for prophylaxis pastes.

An ideal prophylaxis paste should have both cleaning and polishing properties. Key elements would be abrasive particles that become less aggressive under load. The abrasive perlite, a volcanic glass with a sheetlike geometry, is claimed to have these unique properties. This study evaluated the average particle size, size distribution, and morphology of perlite in raw form, in an unused prophylaxis paste, and a used prophylaxis paste. The surface roughness induced on enamel and dentinal specimens was quantitated after paste application in either a rubber cup or a nylon brush. Flour of pumice, a standard prophylaxis paste, a polishing paste, and water were tested similarly. The luster induced by the tested pastes and controls was assessed. Perlite blunted and disintegrated under load. The perlite-containing prophylaxis paste acted as a fine or superfine prophylaxis paste, although it was ranked as medium, based on the mean particle size of its abrasive in the fresh, unused form. Perlite might provide the properties required for the abrasive material of an ideal prophylaxis paste.

Comparison of the efficacy of prophylaxis pastes with conventional abrasives or a new self-adjusting abrasive.

A newly developed prophylaxis paste that contains perlite as an abrasive medium (Cleanic) was compared to conventional prophylaxis pastes with regard to relative dentin and enamel abrasion, cleaning ability, and polishing power. Rubber cups and nylon brushes were used as paste carriers. Water, flour of pumice, and the dentin-polishing paste CCS 40 served as controls. The tested prophylaxis pastes, selected according to their popularity among clinicians, were CCS 250, Détartrine Z, Nupro Coarse, and Zircate. The Prophylaxis Paste Index was created to assess the clinical potential of the various prophylaxis pastes more accurately. The Index was computed for dentin as cleaning ability dended by relative dentin abrasion x surface roughness (in Ra) x 10, and for enamel as cleaning ability dended by relative enamel abrasion x surface abrasion (in Ra). On dentin and enamel, Cleanic consistently yielded low relative dentin and enamel abrasion values, a good cleaning ability, and low surface roughness scores with both rubber cups and nylon brushes. Of all tested prophylaxis pastes, Cleanic excelled in the Prophylaxis Paste Index on dentin and enamel and with both rubber cup and nylon brush applications. Therefore, a perlite-containing prophylaxis paste has broad professional therapeutic indications and may be used universally as a single paste to clean and polish both dentin and enamel.

Comparison of the mechanical effects of a toothbrush and standard abrasive on human and bovine dentine in vitro.

Dentine abrasion is an important possible side effect of individually used mechanical oral hygiene products. Since human teeth are sometimes not available in sufficient numbers for research purposes, bovine teeth are often used as a substitute for in vitro tests of dentine abrasion. The aim of the present comparative study was to determine the mechanical effects of a manual toothbrush and a standard abrasive on human and bovine dentine under standardized conditions. Roots of human and bovine teeth were radioactivated and subjected to standardized machine brushing using a manual toothbrush and a standard abrasive slurry. Dentine abrasion was assessed by measuring radioactive phosphorus contained in the slurry after brushing. Non-radioactive human and bovine roots were brushed in the same machine, and the generated surface roughness was assessed using profilometry. Artificially stained human and bovine roots were brushed as described, and the cleaning effect was expressed as the extent of stain-free surfaces after different brushing times. The results for abrasion and surface roughening found with bovine and human dentine suggest that if standardized methods are used, roots of bovine mandibular front teeth can be used in place of human roots for in vitro studies of the mechanical effects of toothbrushes and toothpastes on dentine. The use of bovine dentine for measuring the cleaning effects of these products is, however, not recommended.

A new fluoride-releasing rubber cup for professional oral hygiene.

Rubber cups in combination with prophylaxis pastes are commonly used for supragingival professional tooth cleaning. This procedure requires frequent interruption in order to collect fresh paste. Moreover, the paste-saliva slurry blurs the visibility, which implies intermittent rinsing to look for residual discolorations. Hawe Neos Dental (Bioggio, Switzerland) has developed a new prophylaxis cup aimed at cleaning and smoothing the tooth surfaces, while simultaneously fluoridating the enamel without a prophylaxis paste. This new prophylaxis cup was tested with respect to cleaning efficiency, resulting surface roughness, abrasivity, and the promotion of fluoride uptake into enamel. After 15 seconds of use, the new cup showed a cleaning efficiency which was 20 to 30% higher than that of a conventional rubber cup (p < 0.01) used with the prophylaxis pastes Nupro coarse or Hawe cleanic (78% vs. 57 and 49%). The fluoride cup had a smoothing effect on the enamel surface comparable to that effected by the two prophylaxis pastes. The abrasivity on enamel was lowest with the new cup. On dentin, abrasivity was comparable to Nupro coarse, but higher than with Hawe cleanic. The fluoride cup also produced a higher amount of KOH-soluble fluoride on the enamel surface when compared to Hawe cleanic. With respect to the structurally bound fluoride, no difference was found. The newly developed fluoride releasing Hawe Neos cup represents an effective alternative to conventional procedures for supragingival professional tooth cleaning on enamel.

[Dental status in relation to age: research in Switzerland 1980-1990]. / Zahnbestand in Relation zum Alter: Erhebungen in der Schweiz 1980-1990.

The number of missing teeth in relation to the patients' age was assessed in fourteen studies of the oral status of different patient groups performed in Switzerland and published between 1980 and 1990. The prognosis of the future development of the average dentition made by Marthaler in 1978 proved to hold true.

[Dental calculus-inhibiting tooth pastes and mouthwashes. A review of the literature of clinical trials]. / Antizahnstein-Zahnpasten und -Mundwässer. Eine Literaturübersicht klinischer Versuche.

Several brands of anticalculus dentifrices and mouthrinses claim to reduce the formation of supragingival calculus. These products contain soluble pyrophosphates (with or without Gantrez), zinc citrate trihydrate or zinc chloride which reduce the amount of supragingival but not subgingival calculus after a scaling. Most of the clinical anticalculus trials ran for 3 or 6 months and the calculus reductions were assessed using the Volpe-Manhold Index. This index assesses the coronal extension of supragingival calculus. Calculus reductions varied from 9% to 50% but no plaque scores were quantitated. However, the ADA has stipulated that dentifrices claiming anticalculus effects must clearly state that the products have not therapeutic effect on periodontal diseases. Some of the placebo dentifrices used in the clinical trials also reduced the calculus scores although they are not as yet advertised as anticalculus dentifrices.

Clinical caries studies with polyalcohols. A literature review.

Polyalcohols represent the most important group of sugar substitutes. Those most widely used in products advertising dental benefits compared to their sucrose containing homologues are sorbitol, mannitol (hexitols), xylitol (pentitol), maltitol, lactitol (12-carbon polyols), Lycasin (hydrogenated starch hydrolysate) and Palatinit (mixture of two 12-carbon polyols). All these polyalcohols have been proven to be non-cariogenic or extremely low cariogenic in rat caries experimentation, and some of them also in human clinical caries studies. They have also been shown to be non-acidogenic or hypoacidogenic in plaque pH telemetry. The low or non-cariogenicity of the above polyols can be termed a "passive" feature, because it is based on the fact that they are not, or only poorly and very slowly, fermented by the oral flora. More recent research, however, has also propagated "active", i.e. bacteriostatic and/or cariostatic properties of xylitol or mixtures of xylitol with other sugar substitutes. Such claims have not yet been substantiated in human caries trials.

[The subjective evaluation of oral health in 40- to 69-year-old subjects. A representative survey of 600 persons in German- and French-speaking Switzerland]. / Subjektiver Stellenwert der oralen Gesundheit bei 40- bis 69jährigen. Eine repräsentative Umfrage bei 600 Personen in der deutsch- und französischsprachigen Schweiz.

Individual oral hygiene, professional dental care and subjective satisfaction with the oral health were investigated in 600 persons representative for the German- and French-speaking population of Switzerland. They cleaned their teeth on average 2.4 x per day, 85% had a "family dentist" whom they had last visited 14.6 months ago and who works to their full satisfaction. On average, every 13.5 month they underwent professional cleaning of their teeth which was performed in 55% by their dentist and in 45% by a dental hygienist. They were well satisfied with the condition of their teeth and gums and even better so with their reconstructions. In 1984 a gap of consumption of toothbrushes and toothpastes had been apparent in over 50-year-old people. Today this is just visible in the over 60 year old. 40 to 60 year old people care for their oral hygiene and regularly go to professional control and cleaning appointments. Only over 60 year old people are consuming slightly less dental services and buying less toothbrushes and toothpastes. Turning points are loss of teeth, retirement, isolation and sharp cuts in income.

No effect of waxed dental floss on enamel fluoride uptake or on enamel dissolution changes.

Enamel specimens were flossed in vitro with "waxed" dental floss and then treated with water, Act, Meridol, or Elmex Gel to evaluate the effect of "waxed" floss on the enamel fluoride uptake and on the enamel dissolution rate. The flossed and treated enamel was etched 4 times successively in 2N HCl for 5, 10, 15 and another 15 s. The concentrations of fluoride, calcium and phosphorus were assayed in the etching solutions. The enamel fluoride concentration was significantly increased in only the first layer of the Elmex Gel group compared to the other 3 groups. Respective etching depths were similar for the water, Act and Elmex Gel groups. However, the first layer in the Meridol group was less etched than that in the 3 other groups. This study showed that "waxed" dental floss did not compromise the fluoride uptake by surface enamel after treatment with a concentrated acidic topical fluoridating agent. Moreover, previously reported results showing that Meridol solution containing SnF2 and amine fluoride 297 significantly decreased the in vitro dissolution rate of enamel were confirmed by the present study. Even though the enamel was first treated with "waxed" dental floss, the SnF2/amine fluoride 297 still produced a decreased enamel dissolution rate.

[Prophylaxis pastes--the new abrasive Perlit compared to conventional polishing substances]. / Prophylaxepasten--das neue Abrasiv Perlit im Vergleich zu konventionellen Putzkörpern.

Perlit is a new dental abrasive, based on volcanic silica. It has a flat, irregular disc-shaped structure which fractures readily in use. Individual discs tend to become oriented parallel to the tooth surface during use while the rough edges also become rounded. A Perlit-based prophylactic paste thus produces polished surfaces although it also has excellent cleaning properties on both enamel and dentin when used with either rubber polishing cups or bristle brushes. The Perlit-based prophy paste, Cleanic, yielded the best results when compared to other prophy pastes during laboratory test scored with the Prophylaxis Paste Index (PPI: Cleaning efficacy: [Abrasivity x Surface roughness]). Consequently, Perlit-based prophy pastes can be used initially as cleaning pastes and the same portion will subsequently polish the dental surfaces as well. Thus Perlit nullifies the rule that an efficient cleaning paste will be abrasive and must produce a roughened dental surface.