Dental caries in rats associated with Candida albicans.

In addition to occasional opportunistic colonization of the oral mucosa, Candida albicans is frequently found in carious dentin. The yeast's potential to induce dental caries as a consequence of its pronounced ability to produce and tolerate acids was investigated. Eighty caries-active Osborne-Mendel rats were raised on an ampicillin-supplemented diet and exposed to C. albicans and/or Streptococcus mutans, except for controls. Throughout the 28-day test period, the animals were offered the modified cariogenic diet 2000a, containing 40% various sugars. Subsequently, maxillary molars were scored for plaque extent. After dissection, the mandibular molars were evaluated for smooth surface and fissure caries. Test animals exposed to C. albicans displayed considerably more advanced fissure lesions (p < 0.001) than non-exposed controls. While S. mutans yielded similar results, a combined association of C. albicans and S. mutans had no effect on occlusal caries incidence. Substituting dietary sucrose by glucose did not modify caries induction by C. albicans. However, animals fed a diet containing 20% of both sugars showed no differences to non-infected controls. Smooth surface caries was not generated by the yeast. This study provides experimental evidence that C. albicans is capable of causing occlusal caries in rats at a high rate.

Acid production by oral strains of Candida albicans and lactobacilli.

Both Candida albicans and lactobacilli are common colonizers of carious lesions in children and adolescents. The purpose of this study is to compare the velocity of acid production between C. albicans and several Lactobacillus species at different pH levels and concentrations of glucose. Washed, pure resting-cell suspensions were obtained by culturing a total of 28 oral isolates comprising the species C. albicans, Lactobacillus rhamnosus, Lactobacillus paracasei paracasei, Lactobacillus paracasei tolerans and Lactobacillus delbrueckii lactis. Acid production from glucose was determined at a constant pH of 7.0, 5.5, 5.0 and 4.0 by repeated titrations with NaOH in an automated pH-stat system. Acid formation rates of yeast and lactobacilli proved to be similar at both neutral and low pH, while in a moderately acidic environment C. albicans produced less acid than the lactobacilli. Ion chromatographic analysis of the cell-free medium after titration revealed pyruvate to be the predominant organic acid anion secreted by C. albicans. The proportion of organic acids to overall acid production by the yeast was below 10% at neutral conditions, in contrast to 42-66% at pH 4.0. Compared to lactobacilli, yeast required a concentration of glucose that was about 50 times higher to allow acid production at half the maximum speed. Considering the clinical data in the literature about the frequency and proportions of microorganisms present in early childhood caries lesions, the contribution of oral lactobacilli as well as C. albicans to overall microbial acid formation appears to be important.

Microbial ingrowth around single- and multi-component adhesives studied in vitro.

The aim of this study was to compare the in vitro microbial leakage in 4 micro-hybrid composites in combination with 4 single-component dental adhesives (Scotchbond 1/Z100 MP = group 1; Syntac Single-Component/Tetric Flow = group 3; OptiBond Solo/XRV Herculite = group 5; Solobond M/Arabesk Top = group 7) and 4 multi-component dental adhesives (Scotchbond Multi-Purpose/Z100 MP = group 2; Syntac/Tetric Flow = group 4; OptiBond FL/XRV Herculite = group 6; Solobond Plus/Arabesk Top = group 8). Ninety-four mixed standardized Class V cavities of human caries-free extracted premolars were filled with eight different composite adhesive systems using a one-layer (groups 1-4) or a two-layer technique (groups 5-8). After thermocycling and incubation in a broth culture of Streptococcus mutans and Lactobacillus acidophilus, followed by decalcification and staining, the extent and the type of microbial leakage were measured histologically. The extent of microbial leakage in the composite restorations was very low in all groups and there were no significant differences between adhesives. Z100 MP in combination with single- and multi-component adhesives showed a significantly higher microbial leakage than Tetric Flow systems (U test: p=0.037). XRV Herculite adhesive systems showed significantly less extensive microbial leakage than Arabesk Top adhesive systems (U test: p<0.001). The single-component dental adhesives achieved a marginal adaptation of composites comparable to that of multi-component adhesives in vitro.

[Lifestyle, living conditions and health status--a cross-sectional study of the Saxon population in the period 1993 to 1994]. / Lebensweise, Lebensumstände und Gesundheitszustand--Eine Querschnittsstudie in der sächsischen Bevölkerung im Zeitraum 1993 bis 1994.

The aim of this cross-sectional study was to record the living conditions, lifestyle variables and health status in a part of the population of Saxony and to examine statistical relationships between the three categories. The interview by post took place from March 1993 to August 1994. The sample consisted of 602 participants, i.e. a return of 52.3%. The survey proved conditionally representative for the population of Saxony. Statistical methods used were Chi2 test, H test, Spearman correlation and multiple regression procedures. Males and females showed clear differences in their lifestyles and in the state of health. It was found that the lifestyle was associated with age. The following variables were significantly associated with the subjective health status: sex, daily routine, number of negative life events, utilisation of preventive measures, contentment, age, and domicile. Significant connections were found between the objective health status (number of chronic diseases) and the variables: utilisation of preventive measures, number of negative life events, employment, daily routine, smoking, alcohol consumption, contentment, and age. In the statistical relationship the primary health status had the most distinct influence on the lifestyle and this covered the influence of lifestyle on health status.

Antibacterial effects of Nd:YAG laser irradiation within root canal dentin.

The microbial flora of the root canal dentin can cause failures in the conventional treatment of infected root canals if it cannot be sufficiently removed by preparation and chemical disinfection of the root canal. The aim of this study is to examine the bactericidal effects of neodymium:yttriumaluminum garnet (Nd:YAG) laser irradiation in the depth of the root canal dentin. Following sterilization, longitudinal section dentin slices of different thicknesses (100-1000 microns) were inoculated on one side with 4 microliters of a Streptococcus mutans suspension. The opposite sides of the dentin slices were then irradiated four times for 10-20 sec (according to the sample area) using the Nd:YAG laser at a setting of 1.5 W, 15 pps with a 200 microns glass fiber from an angle of about 5 degrees. The bacteria were then removed from the dentin using vibration and plated out on culture dishes that were selective for Streptococcus mutans. When compared with untreated control slices, counting of the colonies revealed a highly significant elimination of bacteria for all thicknesses following laser irradiation. Although the intensity of the laser irradiation decreased after penetration of a 1000-micron dentin slice, the bactericidal mode of action was still effective.

[Preventive-curative dental care in a large East German urban population. The 4-year experiences of a Dresden prevention study with 16- to 35-year-old subjects]. / Präventiv-kurative zahnmedizinische Betreuung in einer ostdeutschen Grossstadtpopulation. 4-Jahres-Ergebnisse der Dresdener Präventionsstudie an 16- bis 35jährigen.

The present 4-year Dresden preventive study was carried out to realize a dental care concept with preventive emphasis in 6 Dresden state health services. 2502 patients aged 16-35 years were randomly selected in 1988. The effectiveness of this study was evaluated by means of the parameters oral health behaviour, oral health state and preventive care needs. The spectrum of methods included extended anamnesis, plaque index according to Silness & Löe, DMF/T, DMF/S, GPM/T index, CPITN and saliva tests in case of high caries risk. The dental care based on a basic and a risk strategy. The basic strategy included a complex symptomatic dental treatment and a dental prophylaxis, repeated once every 3 month. The patients were given instruction, demonstration, remotivation, professional oral hygiene measures and topical application of fluorides. The 4-year preventive intervention resulted in an improved consultation and oral hygiene behaviour. The nutritional behaviour did not change essentially. Within the cohort plaque index decreased from 1.01 to 0.68, the GPM/T index from 11.7 to 10.4 as well as the preventive care needs. It was found a low caries increment. The care concept with preventive emphasis is recommendable by its effectiveness.

[The symptomatic therapy of cervical hard-substance defects with dentin-adhesive-composite systems]. / Symptomatische Therapie zervikaler Hartsubstanzdefekte mit Dentinadhäsiv-Komposit-Systemen.

For covering of hypersensitive, morphologically disturbed and non-esthetic cervical (wedge-shaped) defects of hard dental tissues, dentine adhesive composite systems are suitable for a careful and less invasive preparation. Presumption is a smooth and at probing hard-touched defect surface. A clinical 2 year study (15 patients with 143 cervical lesions) using 5 different dentine adhesive composite systems resulted in superiority of the hybrid composite P-30 in view of low filling losses (after 1 year: 1 of 28 fillings after 2 years: 2 of 27 fillings), the acceptable bond zone morphology (after 1 and 2 years clinical intact bond zones), and a constant volume behaviour (after 1 and 2 years no clinical changes of volume). The micromorphological evaluation correlated in a lot of cases with the clinical findings after 2 years. It has to be expected that improved dentine adhesive composite systems together with changed setting mechanisms of dentine adhesives will be able to eliminate filling losses in the treated indication.

[The oral health of an East German population of a large city. The basic research of the Dresden prevention study on 2500 16- to 35-year-olds]. / Orale Gesundheit einer ostdeutschen Grossstadtpopulation. Basisuntersuchungen der Dresdener Präventionsstudie an 2500 16- bis 35jährigen.

Oral health behaviour, oral health state, dental care effectiveness and preventive-curative care needs were subject of a basic examination using 2500 randomly selected patients aged 16-35 years in 6 Dresden state health services in 1988. The spectrum of methods included extended anamnesis, plaque index according to Silness & Löe, DMF/T index and DMF/S index according to WHO criteria without X-ray diagnostics, GPM/T index, CPITN, as well as assessment of gingival recessions, acute and chronic trauma and the prosthetic status. Considering a mean DMF/T of 9.88, DMF/S of 17.93 and GPM/T of 11.9 in patients being 16-19 years and a DMF/T of 15.21, DMF/S of 40.94 and GPM/T of 12.9 in patients being 30-35 years, as well as the insufficient dental care, the majority of patients was in need of preventive care measures. Filling therapy and gingivitis treatment were necessary from the curative point of view. Early chronic tooth surface loss required early preventive-curative intervention. The key for an effective care in the early and middle adult age is a functioning individual concept with preventive emphasis which should include a basic and a risk strategy.

[Oral health behavior and state and the effect and necessity of dental care in young and medium adults (Dresden prevention study)]. / Orales Gesundheitsverhalten und Oraler Gesundheitszustand sowie stomatologische Betreuungswirksamkeit und -notwendigkeit im frühen und mittleren Erwachsenenalter (Dresdener Präventionsstudie).

In a baseline examination of a preventive study 319 randomly recruited patients of a dental school aged between 16 and 35 years were inquired about oral health behavior and the oral health state was determined clinically. The spectrum of methods included extended anamnesis, plaque index according to Silness/Löe, DMF/T- and GPM/T-index. The health behaviour and the derived preventive and curative care needs show that the majority of patients need individual oral hygiene and nutrition advising, professional oral hygiene measures, fluoride application, as well as filling therapy. Early therapy of periodontitis is of importance.

[Qualitative marginal gap research on amalgam fillings]. / Qualitative Randspaltuntersuchungen an Amalgamfüllungen.

Using x-ray spectroscopy the inorganic contents of the interface tooth restoration of conventional and gamma-2-reduced amalgam fillings were analysed after short and long clinical application. Qualitative difference did not exist between interface layer of both amalgam types. The amalgam elements mercury, silver and copper were not detected, but tin occurred everywhere. Zinc and oxygen were frequently analysed in the interface layer. Calcium, phosphorus, sodium and magnesium were detected, too.

[Scanning electron microscopic studies on the efficacy of irrigated, hand root canal preparation]. / Rasterelektronenmikroskopische Untersuchungen zur Effektivität der feuchten manuellen Wurzelkanalaufbereitung.

The effectiveness of hand preparation and irrigation of 48 root canals of upper anterior teeth was evaluated by scanning electron microscopy. Independently of instrument (K reamer or combination K reamer and H file), irrigating solution (sodium chloride) and root canal dressing a similar degree of preparing and cleaning effectiveness of root canals was detected. In all groups a homogeneous or inhomogeneous smear layer of different thickness and extent dominated. A scale of preparing and cleaning effectiveness is recommended.

[Criteria of high caries risk in the targeted preventive-curative care of 16- to 35-year-olds. The Dresden prevention study]. / Kriterien des erhöhten Kariesrisikos bei der gezielten präventiv-kurativen Betreuung 16-35jähriger. Dresdener Präventionsstudie.

Among 300 patients 16-35-yr-old 21 of them showed a high individual caries risk. Estimation of caries risk was based on the following criteria: caries experience, sugar consumption, fluoride application, dry mouth, plaque accumulation, secretion rate, buffer capacity and S. mutans and lactobacillus counts in saliva. In case of high caries risk a sure diagnosis and directed preventive-therapeutic intervention depend on a complex consideration of all the risk factors.

[The oral health knowledge and behavior as well as the oral findings in young adults with different courses of education (the Dresden prevention study)]. / Mundgesundheitswissen und -verhalten sowie orale Befunde bei jungen Erwachsenen mit unterschiedlichem Bildungsweg (Dresdener Präventionsstudie).

In a dental-psychological investigation 100 young adults, aged 18-25, characterized by different courses of education, were subject to a standardized interview, action oriented diagnostics and dental examination. Knowledge, behaviour as well as state of oral health were different and in all did not come up to our expectations; but there were some correlations. It is indicated to optimize knowledge, behaviour and state of oral health by means of individual and collective measures taking educational specifics into consideration.

[Clinical variations of the so-called wedge-shaped defect]. / Klinische Variationen des sogenannten keilförmigen Defektes.

Clinical variations of 288 so-called wedge-shaped defects were described at the model and in the clinic in 50 patients aged 21 to 67 years and classified according to depth, profile and en face contour. Defect formation starts in early adult age increasing in dependence on age. The term "wedge-shaped defect" is only partly indicative and incorrect.

[Chlorhexidine in the treatment of root canal infection and its sequels]. / Chlorhexidin in der therapeutischen Trias des infizierten Wurzelkanals und seiner Folgeerkrankungen.

The plaque inhibitor chlorhexidine digluconate was used for intra- and transcanal irrigation in the endodontic treatment triad for periapical lesions (circumscribed, diffuse, fistulating, cystic, suspected cystic lesions). 50 patients were followed up by clinical and standardized radiologic studies. In another 18 patients microbiologic criteria were also used. 16 root canals showed pretreatment infection with mixed aerobic and anaerobic organisms. Mechanical preparation of the root canals with or without extension of the foramen and triple irrigation with 0.5% chlorhexidine digluconate produced clinical relief of symptoms (49 pts.), sterility (14 of 18 pts.) and reduction of the size of periapical lesions (12 pts.). At a mean follow-up of 24 months 30 patients have so far shown complete restitution of periapical bone.

[Toxicity of different endodontic antiseptics]. / Tierexperimentelle Untersuchungen zur Toxizität verschiedener Wurzelkanalantiseptika.

The median lethal dose (LD 50) of endodontic antiseptics sodium hypochlorite, chloramine and chlorhexidine digluconate was determined in experiment on albino mice using the method described by Litchfield and Wilcoxon. Sodium hypochlorite and chloramine have shown a twice stronger toxic effect than chlorhexidine digluconate. The difference was significant.

[Antimicrobial effect of endodontic antiseptics]. / Zur antimikrobiellen Wirksamkeit verschiedener Wurzelkanalantiseptika.

The endodontic antiseptics chloramine, sodium hypochlorite and chlorhexidine digluconate were evaluated for antimicrobial effect by a complex of susceptibility testing. In the agar diffusion test, tube dilution test and plate flooding test chlorhexidine digluconate was the most efficient agent against isolates of infected root canal.

[Transparent dentinal sclerosis and its clinical significance]. / Uber transparente Dentinsklerose und ihre klinische Bedeutung.

Localisation, extension, age dependence and permeability of the translucent zones in different progression stages of the dentine caries were examined by light microscopy, histochemical methods and dye penetration on ground sections, thin-ground sections and decalcified material of extracted human teeth. This phenomenon is observed in every age and more interpreted as a passive chemical precipitation than a protective activity of the pulp-dentine-system. As it is developed incompletely, it represents at most a relative, but not a proof protection from penetrating noxious actions.

[Experimental research on the genotoxicity of various root canal antiseptics in the SOS chromotest]. / Experimentelle Untersuchungen zur Genotoxizität verschiedener Wurzelkanalantiseptika im SOS-Chromotest.

The genotoxicity of the endodontic antiseptics chlorhexidine digluconate, chloramine and sodium hypochlorite was determined by SOS chromotest using Bioscreen Analyzer Systems (Labsystem OY). All antiseptics did not show a genotoxic effect. Chlorhexidine digluconate was the most efficient antimicrobial agent against E. coli PQ 37.