Dental caries

The most generally accepted theory as to the cause of dental caries is that certain bacteria in the mouth, in the presence of fermentable sugars, cause the formation of acids which in turn decalcify teeth. Physicians may help reduce the incidence of caries by recommending elimination of refined sugars from the diet, or at least control of the amount consumed.Cleaning the teeth with a well designed tooth brush after each meal will to a certain extent mechanically remove the fermentable sugar and debris from the teeth. One step further in oral hygiene that may be beneficial is to use a dentifrice with 5 per cent dibasic ammonium phosphate and 3 per cent urea to reduce the formation of acid. Anything that will increase salivation will aid in buffering any acids that may be present.A 2 per cent solution of sodium fluoride applied to the thoroughly dried "intact" enamel surface may prevent caries. Sodium fluoride added to drinking water to a concentration of 1 part per million is utilized by the body in formation of an enamel that is particularly resistant to caries.     

Time-gated in vivo autofluorescence imaging of dental caries.

Laser-induced time-resolved autofluorescence from carious lesions of human teeth was studied by means of ultrashort pulsed laser systems, time-correlated single photon counting and time-gated imaging. Carious regions exhibited a slower fluorescence decay with a main 17 ns fluorescence lifetime than healthy hard dental tissue. The long-lived fluorophore present in carious lesions only emits in the red spectral region. Fluorescence decay time and spectral characteristics are typical of fluorescent metal-free porphyrin monomers. The spatial distribution of the long-lived endogenous porphyrin fluorophore within the tooth material was detected by time-gated nanosecond autofluorescence imaging. In particular, high contrast video images were obtained with an appropriate time delay of 15 ns to 25 ns between excitation and detection due to the suppression of short-lived autofluorescence of healthy tissue. First in vivo applications are reported indicating the potential of time-resolved fluorescence diagnostics for early caries- and dental plaque detection.     

An effect of zinc deficiency on dental caries.

Rat pups suckled by dams fed a zinc-deficient diet developed higher levels of dental caries following a caries-test challenge than pups suckled by dams fed a zinc-adequate diet. The zinc deficient treatment was administered during the mineralization stage of tooth development before the molars erupted. The data shows that suboptimal zinc nutriture was associated with an increase in dental caries.Fluoride, a trace element, is recognized as a factor in preventing dental caries and its use has had a significant impact on dental health in this country. However, the possible roles of other trace elements have not been closely examined. Zinc is a trace element important to bone mineralization as well as in general nutrition.The effects on dental caries produced by the addition of zinc to rat diets have been reported (1, 2, 3). In those investigations, however, zinc supplements were added to diets that were adequate in zinc. Moreover, zinc supplements were fed after the teeth had appeared in the oral cavity. Because the critical period of tooth maturation occurs before eruption (4), post-eruptive zinc supplements probably should not markedly influence the development and, specifically, the mineralization of the tooth. Therefore, we investigated the influence of pre-eruptive zinc deficiency on caries development in rats.     

Ultrastructure of lipid bodies in Tilletia caries teliospores.

The ultrastructure of lipid bodies within developing, dormant, and germinating Tilletia caries (DC). Tul. (race T-16) teliospores was studied by freeze-etching and thin-sectioning techniques. When teliospores were prefixed in sodium cacodylate-buffered glutaraldehyde-acrolein for 24 h before further processing, most of the lipid bodies appeared to have a uniformly osmiophilic matrix. Some of these lipid bodies were surrounded by thin electron-dense lines that appeared to be half-unit membranes. Occasionally this membrane seemed to be absent, allowing for a direct interface between lipid and cytosol. Irregular electron-dense patterns were occasionally observed in lipid bodies of developing, dormant, and germinating teliospores. A lamellar substructure with 6- to 10-nm center-to-center spacing was visible in the electron-dense patterns at high magnifications. Irregular fracture patterns were visible in freeze-etch replicas.     

Failure of environmental lighting to influence dental caries rate.

Two experiments involving littermate cotton rats were conducted to determine the effect of cool-white fluorescent versus artificial sunlight environments on caries incidence. There were no significant differences in either the incidence or extent of caries associated with the different types of lighting. This contradicts our previous observations (1) with this species using identical experimentation and calls for a retraction. It is suggested that the difference is due primarily to the application of an inappropriate statistical approach in the earlier work.     

Spectral characteristics of caries autofluorescence obtained from different locations and caries severities

Dental caries usually occurs at interproximal and occlusal surfaces. The purpose of the present study was to determine if characteristic spectral factors extracted from autofluorescence (AF) spectra are informative regarding caries detection and the determination of caries stage as compared with DIAGNOdent results. AF spectra were obtained from caries lesions of different severities at two locations using a 405 nm laser. Three spectral factors, that is, spectral slope at 550 to 600 nm, spectral area under the curve at 500 to 590 nm and two‐peak ratio between 625 and 667 nm, were extracted. The values of three spectral factors linearly decreased as caries progressed. According to micro‐CT images, conventional visual and tactile inspections of lesions under or overestimated (25%‐65%) caries states, and brown or thickly stained layer on interproximal or occlusal surfaces, respectively, caused misclassifications of caries stage. Of the spectral factors examined, spectral slope and area under curve for interproximal and occlusal surfaces, respectively, were found to be significantly related to caries stage and showed least data overlap. For interproximal and occlusal surfaces, DIAGNOdent readings of different stages overlapped considerably though their mean values were significantly different regardless of stage.      

Log-linear analysis of dental caries occurrence in four skeletal series.

Four skeletal series (Corinth, Greece; Gran Quivira, New Mexico; Semna South, Sudanese Nubia, and a large group from scattered sites in England) were coded for sex, jaw, tooth group, dental attrition, dental caries, site and time period. Through thec concepts of a basal level of caries and a cariosity gradient, a single model was found which best described the occurrence of this disease in these samples. All factors were found to contribute significantly to the model. Within the possible subsamples the general characteristics are that the profiles of males, of the mandibulae and of those with light attrition are more likely to have lower overall dental caries levels and to be relatively more carious in the back of the mouth than the front when compared to the pooled sample of all teeth and caries. The opposite is also found to be generally true; the teeth of females, maxillae and heavy attrition are associated with more caries, especially toward the front of the mouth. These results imply that samples appearing otherwise homogeneous display much variation. They also reveal distinct regularities in the reactions of diverse human groups to dental caries.     

Epidemiology of root caries

Many epidemiological studies have been conducted on a variety of populations. Unfortunately, comparison of the prevalence data, and to a lesser degree of the incidence data, between the various studies is of little use due to the lack of standardised diagnostic criteria, reporting methods and population diversity. In the few incidence studies which have been conducted around 30–40% of people developed root caries, although many adults in the population appear to have been affected by root caries. Many risk factors associated with the occurrence of root caries have been identified and these include oral, medical, mental, behavioural and psychosocial conditions.     

Remineralisation study of artificial root caries lesions after fluoride treatment. An in vitro study using electric caries monitor and transversal micro-radiography

Aims: To evaluate and compare remineralisation of root caries lesions after in vitro treatment with various fluoride (F) agents using an Electric Caries Monitor (ECM) and Transversal Micro‐Radiography (TMR). Materials: Permanent human teeth were extracted and root surface specimens were sectioned, prepared (n = 35), and randomly allocated into seven different experimental groups (groups 1–7). Methods: Root surfaces were demineralised in an acidified gel (pH = 5.0) for 3 weeks followed by various F treatments and stored in a standardised remineralising solution at 37°C for 6 weeks. The root surfaces were treated twice daily with different dentifrice slurries for 2 min, either with a neutral placebo dentifrice without F (group 5); or a neutral sodium fluoride (NaF) 1400 p.p.m. F dentifrice (group 1); or a neutral 1250 p.p.m. F dentifrice (group 6); or an acid dentifrice (pH 4.7) with 1400 p.p.m. F containing amine fluoride (AmF) (groups 3 and 4) or a 1250 p.p.m. (pH 4.7) AmF dentifrice (group 6). In groups 1, 2, 5, 6, and 7, the root surfaces were additionally rinsed for 2 min with a neutral non‐F placebo solution. In groups 3 and 4, rinsing were performed for 2 min with an acid (pH 4.7) 250 p.p.m. F solution, containing 125 p.p.m. F as AmF and 125 p.p.m. F as potassium fluoride (KF), once or twice per day respectively. ECM was used to measure electrical resistance on root surfaces at baseline and after 3 and 6 weeks respectively. TMR technique was used to measure and compare root surface lesion depths and mineral loss. Results: Six weeks daily treatment with a dentifrice slurry containing AmF followed by rinsing with a combination of equal amounts of AmF and KF solution twice a day showed a statistical significant higher ECM values compared with the other groups. TMR data measuring lesion depths and mineral loss reduction supported the results of the ECM findings. Conclusions: Daily application of a dentifrice slurry containing 1400 p.p.m. F as AmF combined with twice daily rinsing with a 250 p.p.m. F solution containing equal amount of AmF and KF significantly remineralise primary root caries lesions in vitro. ECM and TMR are valuable complementary methods in order to analyse the remineralisation processes.     

Molecular analysis of ancient caries

An 84 base pair sequence of the Streptococcus mutans virulence factor, known as dextranase, has been obtained from 10 individuals from the Bronze Age to the Modern Era in Europe and from before and after the colonization in America. Modern samples show four polymorphic sites that have not been found in the ancient samples studied so far. The nucleotide and haplotype diversity of this region have increased over time, which could be reflecting the footprint of a population expansion. While this segment has apparently evolved according to neutral evolution, we have been able to detect one site that is under positive selection pressure both in present and past populations. This study is a first step to study the evolution of this microorganism, analysed using direct evidence obtained from ancient remains.     

Dental caries in disabled children

The aim of the study was to evaluate oral health conditions and dental caries status in disabled and healthy children. Two groups of randomly selected children 3-17 years old were examined. The first group comprised 80 children with disabilities (cerebral palsy, mental retardation, Down syndrome, autism and hearing-speaking disorders) and the second (control) group included 80 healthy children. Examined children were selected from several institutions which take care of disabled persons, kindergardens and four elementary schools. Clinical examination was performed by using a mirror and a probe and revealed the presence of dental caries, missing (extracted) and filled teeth. All clinically detected cavitations were registered as dental caries. The degree of oral hygiene was evaluated according to the OHI-S index values, which was determined by marking the plaque with 1% eozine solution. The values of OHI-S index ranged from 3.8-4.53 in disabled children and 2.73-2.84 in healthy children. In disabled children, the average dft values were 3.42 in deciduous teeth and 5.24 in mixed dentition. In healthy children, the average dft values were 1.43 in deciduous teeth and 5.1 in mixed dentition. The average DMFT index in disabled children was 1.41 for mixed and 6.39 for permanent dentitions. In healthy children, the average DMFT values were 1.23 in mixed and 4.76 in permanent dentitions. In general, the results revealed significantly poor level of oral hygiene and quite high level of caries prevalence in both disabled and healthy children, accentuating the need to reorganize preventive care measurements and improve dental care, particularly in disabled children in Croatia.