Adapting to changes in molecular biosciences and technologies.

Dental education, like any other educational programme in a research-intensive university environment, must be research led or at least research informed. In this context, as the research and knowledge base of dentistry lies in the biological and physical sciences, dental education must be led by advances in research in both these areas. There is no doubt that biotechnology and nanotechnology have, over the past 25 years, led research in both these areas. It is therefore logical to assume that this has also impacted on dental education. The aim of this paper is twofold; on one hand to examine the effects of biotechnology and nanotechnology and their implications for dental education and on the other to make recommendations for future developments in dental education led by research in biotechnology and nanotechnology. It is now generally accepted that dental education should be socially and culturally relevant and directed to the community it serves. In other words, there can be no universal approach and each dental school or indeed curriculum must apply the outcomes in their own social, cultural and community settings.

Chemomechanical caries removal in primary teeth in a group of anxious children.

Chemomechanical removal of dental caries has considerable potential in the treatment of patients with management problems, especially in paediatric dentistry. The aim of this study was to assess the acceptance and success of the technique in young nervous patients. A group of 20 patients, aged between 4 and 10 years with a high level of dental anxiety was selected. The study achieved a success rate of over 90% in acceptance of cavity preparation by this procedure followed by placement of a restoration. The length of time required for cavity preparation was comparable with conventional methods. The need for local anaesthesia was reduced or eliminated and the children did not complain of any pain during the procedure. It is concluded that chemomechanical caries removal in vivo in primary teeth is an effective alternative to conventional mechanical caries removal and is advantageous in patients who have a phobia to the dental handpiece and/or injections.

[Chemo-mechanical caries removal: a review of the techniques and latest developments]. / Chemisch-mechanische cariësverwijdering: een overzicht van de technieken en de nieuwste ontwikkelingen.

Chemo-mechanical caries removal involves the chemical softening of carious dentine followed by its removal by gentle excavation. The reagent involved is generated by mixing amino acids with sodium hypochlorite; N-monochloroamino acids are formed which selectively degrade demineralised collagen in carious dentine. The procedure requires 5-15 minutes but avoids the painful removal of sound dentine thereby reducing the need for local anaesthesia. It is well suited to the treatment of deciduous teeth, dental phobics and medically compromised patients. The dentine surface formed is highly irregular and well suited to bonding with composite resin or glass ionomer. When complete caries removal is achieved, the dentine remaining is sound and properly mineralised. The system was originally marketed in the USA in the 1980's as Caridex. Large volumes of solution and a special applicator system were required. A new system, Carisolv, has recently been launched on to the market. This comes as a gel, requires volumes of 0.2-1.0 ml and is accompanied by specially designed instruments.

Chemochemical caries removal: a review of the techniques and latest developments.

Chemomechanical caries removal involves the chemical softening of carious dentine followed by its removal by gentle excavation. The reagent involved is generated by mixing amino acids with sodium hypochlorite; N-monochloroamino acids are formed which selectively degrade demineralised collagen in carious dentine. The procedure requires 5-15 minutes but avoids the painful removal of sound dentine thereby reducing the need for local anaesthesia. It is well suited to the treatment of deciduous teeth, dental phobics and medically compromised patients. The dentine surface formed is highly irregular and well suited to bonding with composite resin or glass ionomer. When complete caries removal is achieved, the dentine remaining is sound and properly mineralised. The system was originally marketed in the USA in the 1980's as Caridex. Large volumes of solution and a special applicator system were required. A new system, Carisolv, has recently been launched on to the market. This comes as a gel, requires volumes of 0.2-1.0 ml and is accompanied by specially designed instruments.

Salivary proteins in rheumatoid arthritis and Sjögren's syndrome: one-dimensional and two-dimensional electrophoretic studies.

Parotid saliva from patients with rheumatoid arthritis and Sjögren's syndrome contains elevated levels of multiple anionic proteins of pI approximately 3.75-4.75 and Mr approximately 32,000. Further studies on these components involving narrow range pH 3.5-5.0 immobilized pH gradients (IPGs) and two-dimensional (2D) electrophoresis with narrow- or broad-range IPGs in the first dimension have confirmed their association with these disorders. Immunoblotting showed that these proteins include multiple forms of tissue kallikrein. Treatment with neuraminidase results in removal of these anionic substances from the pH 3.75-4.75 region of gels, thereby indicating that heterogeneity arises from differences in sialation of the carbohydrate residues. The results of treatment with endo-beta-N-acetylglucosaminidase (Endo F) or peptide N-glycosidase (PNGase F) and comparison of the results with studies on human urinary kallikrein suggest that proteins other than kallikrein may also comigrate in the anionic region of gels and that deglycosylation of kallikrien is incomplete in the experimental conditions used, probably because of inadequate denaturation. The paper also reviews the limitations of current criteria used in the investigation of salivary gland function associated with connective tissue disorders and the diagnosis of these. It assesses the potential of electrophoresis in forming the basis of new diagnostic techniques and furthering the understanding of the nature of these diseases. The findings presented in this paper could make a key contribution to this.

Caries detector dyes--an in vitro assessment of some new compounds.

Previous studies have shown that the caries detector dyes, basic fuchsin and acid red, lack specificity. Accordingly, their clinical use can lead to the unnecessary removal of sound tissue. In the present study, the specificity of three further dyes, Carbolan Green, Coomassie Blue and Lissamine Blue was studied. Carious dentine was removed in vitro by means of rotary instruments until the cavities were deemed caries free by conventional clinical criteria. Experimental dyes were applied to the cavity floors, all of which became stained. Stained dentine was removed from half the cavity by means of a burr, the other half remaining as a control. Further stain was then applied and the procedure repeated until no further reduction of the staining of the cavity floor could be achieved. Light microscopy of ground sections of experimental teeth showed that sound tissue had been removed unnecessarily from the experimental half of the cavity due to the lack of specificity of these dyes. This lack of specificity of staining was similar to basic fuchsin and acid red. Only Carbolan Green showed possible differential staining between control and experimental sites, but this was not caries specific. If a clinically useful dye is to be developed, it would need to specifically stain either bacteria in infected dentine and/or the carious degradation products of dentine matrix.

Chemomechanical removal of dental caries in deciduous teeth: further studies in vitro.

OBJECTIVE: To further investigate the efficacy of N-monochloro-DL-2-aminobutyrate (NMAB) and NMAB containing 2 M urea (NMAB-urea) as chemomechanical caries removal reagents in deciduous teeth using standardised lesions and limited applicator pressure. DESIGN: In vitro. METHOD: Carious dentine was removed from standardised lesions in deciduous teeth using NMAB, NMAB-urea or isotonic saline (control); 50 lesions were studied with each reagent. The surface of the dentine remaining in cavities where complete caries removal was achieved was examined by light and scanning electron microscopy. MAIN RESULTS: NMAB-urea (but not NMAB) gave significantly improved caries removal compared with saline. The dentine surfaces remaining after complete caries removal were irregular and approximately one third were bacterially contaminated. CONCLUSIONS: The improved efficacy of NMAB by the addition of urea has been confirmed. Toxicity studies are still necessary prior to clinical use of this reagent.

Human salivary sugar clearance after sugar rinses and intake of foodstuffs.

The aetiology of dental caries is in part related to the retention time of dietary carbohydrates in the oral cavity and their subsequent metabolism by the oral bacteria. Salivary clearance of fermentable carbohydrates from three different foodstuffs was examined in 5 subjects and analyses performed by high-performance anion-exchange chromatography with pulsed amperometric detection. The clearance of glucose, fructose, sucrose, maltose and sorbitol rinses was studied as well as that of chocolate bars, white bread and bananas. Of the sugar rinses studied, sucrose was removed from saliva most rapidly whilst appreciable levels of sorbitol remained even after 1 h. Clearance of residual carbohydrates from bananas and chocolate bars seemed marginally faster than in the case of bread, but sucrose levels still tended to fall more quickly than other carbohydrates studied. Surprisingly, carbohydrate residues from the three foods studied were still present in the mouth even 1 h after ingestion, which is longer than has hitherto been reported.

Nutrition in dental education: a European perspective.

Previous studies have highlighted the diversity of levels of nutrition teaching in European Dental Schools, ranging from extensive courses in Scandinavia and the Netherlands to little or none in some other countries. A current survey has shown that whilst on average there has been a small increase in nutrition teaching since 1989, the profile over all is unchanged. The major exception however, is the UK, where nutrition teaching has improved substantially since the introduction of the extended preclinical curriculum in 1990. Despite improved living standards and better nutrition in much of Europe, nutrition is still an essential component of the dental curriculum. New problems such as erosion and obesity have arisen as a result of a diet of affluence and modern lifestyles. European Union guidelines on nutrition teaching would be helpful.

Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of human parotid salivary proteins: comparison of dansylation, coomassie blue R-250 and silver detection methods.

Detection of human parotid salivary proteins by dansylation and UV-transillumination after sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) has been compared with Coomassie Blue R-250 and silver staining procedures. Dansylation gives superior results in terms of both resolution and sensitivity, especially with basic proline-rich proteins (PRPs).

Human salivary glucose analysis by high-performance ion-exchange chromatography and pulsed amperometric detection.

The aim of this project was to develop an analytical procedure with the required level of sensitivity for the determination of glucose concentrations in small volumes of unstimulated fasting whole saliva. The technique involves high-performance ion-exchange chromatography at high pH and pulsed amperometric detection. It has a high level of reproducibility, a sensitivity as low as 0.1 mumol/l and requires only 50 microliters samples (sensitivity = 0.002 pmol). Inhibition of glucose metabolism, by procedures such as collection into 0.1% (w/v) sodium fluoride, was shown to be essential if accurate results are to be obtained. Collection on to ice followed by storage at -20 degrees C was shown to be unsuitable and resulted in glucose loss by degradation. There were inter- and intraindividual variations in the glucose concentration in unstimulated mixed saliva (range; 0.02-0.4 mmol/l). The procedure can be used for the analysis of other salivary carbohydrates and for monitoring the clearance of dietary carbohydrates from the mouth.

Adherence of oral microorganisms to human parotid salivary proteins.

Bacterial colonisation of oral surfaces by microorganisms may be dependent on their interaction with specific host receptor molecules. Primary oral colonisers are known to remove specific proteins from parotid saliva. The aim of this study was to determine whether these interactions facilitate microbial attachment to a surface and hence identify specific salivary components as putative host receptor molecules. Parotid saliva was resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and then electroblotted onto nitrocellulose membranes. Suspensions of fluorescently labelled microorganisms were incubated with the blots and salivary components with adherent bacteria identified as fluorescent bands under ultraviolet (UV) transillumination. Species of streptococci known to be early colonisers of the clean tooth surface were found to adhere specifically to certain salivary proteins, especially to basic proline-rich proteins (PRPs). Polymorphic variations in these patterns could form the basis of differences in oral microflora, susceptibility to oral infections and consequent disease.

An improved reagent for chemomechanical caries removal in permanent and deciduous teeth: an in vitro study.

OBJECTIVES AND METHODS: An in vitro study has been carried out on the chemomechanical removal of caries in deciduous and permanent teeth. The aims of the study were to compare the efficacy of caries removal by various chemical agents including N-monochloro-DL-2-aminobutyrate (NMAB) and NMAB containing urea (NMAB-urea), to compare the efficacy on permanent and deciduous teeth and to study the dentinal surfaces produced. RESULTS: The addition of urea to NMAB resulted in an improvement in the efficacy of caries removal. Sodium hypochlorite, saline and urea alone were also studied as caries removal agents, but were not significantly different from NMAB. Chemomechanical caries removal solutions were more effective in removing caries from deciduous teeth than from permanent teeth, especially in terms of the volume of solution used. The improvement on addition of urea was found to be greater in deciduous than in permanent teeth, the number of deciduous teeth with 'complete cares removal' being increased by about 25%. The dentinal surfaces of the cavities prepared using these solutions and in which 'complete caries removal' had been achieved were studied by scanning electron microscopy. Generally after treatment with NMAB or NMAB-urea, the surface appearance was very uneven with many undermined areas. NMAB-urea produced a 'cleaner' surface compared with that produced by NMAB alone. CONCLUSIONS: NMAB appears to be potentially more effective and clinically more useful in removing caries in deciduous teeth than in permanent teeth, and the addition of urea may enhance its efficacy, especially in the treatment of paediatric dental patients.

Mineral content of the dentine remaining after chemomechanical caries removal.

Although the dentine remaining after chemomechanical caries removal appears sound by normal clinical criteria, no definitive evidence has yet been obtained to confirm that the dentine surface is in fact mineralised. The aim of this study was to use backscattered electron (BSE) imaging and electron probe micro-analysis (EPMA) to ascertain the level of mineralisation of the dentine remaining in cavities prepared by this technique. Carious dentine was removed from carious lesions by means of N-monochloro-DL-2-aminobutyric acid (NMAB) or NMAB containing 2 mol/l urea. Sections of teeth in which caries removal was complete by normal clinical criteria were examined by EPMA and BSE. Dentine adjacent to the pulp was found to be less mineralised than the surrounding dentine. Although the superficial layer of dentine remaining on the cavity floors frequently appeared to have a slightly reduced mineral content, the results clearly indicated that there was no significant difference between this dentine and the underlying sound dentine.