In Vitro Tests to Determine the Cariogenic Potential of Oral Microorganisms

In the aetiology of dental caries, a definite bacterial role was first proposed by W.D. Miller (1890). In the interim, many researchers have investigated the relationship of oral microorganisms to the disease process. Since the 1960's, members of the mutans streptococci have been implicated consistently as playing a major role in dental caries, due mainly to significant correlations between the number of these streptococci in saliva, and caries experience. The recent decline in caries prevalence has demonstrated that individuals differ in caries susceptibility, and within communities there exist high-risk groups and individuals. Such findings have highlighted the desirability of determining accurately the caries susceptibility of an individual patient prior to, or at a very early stage of disease initiation. Currently available caries-activity tests have concentrated mainly on the numbers of organisms present in saliva, with no account taken of potential differences in virulence. Increasingly, it has been realised that such tests lack sufficient sensitivity and specificity to permit reliable identification of the at-risk individual, rendering them of limited usefulness clinically. Macpherson (1988), suggested that strains of S. mutans differ in their cariogenic potential and that such differences correlated with clinical disease experience. This thesis aimed to investigate further, the in vitro cariogenic potential of oral microorganisms. The microbiological methods and analytical techniques used in the study, and the isolation, identification and storage of clinical isolates were described (Chapter 2). The technique of isotachophoresis was also detailed, and previously unreported factors influencing isotachophoretic analysis were identified whilst validating the technique. This Chapter concluded by describing the detection of calcium by complexation with o-cresolphthalein and compared the technique with atomic adsorption spectroscopy. The in vitro test system described by Macpherson (1988), involved the incubation of a bacterial cell slurry, a slab of bovine enamel, and a 5% sucrose solution for two, 24 hour incubation periods at 3

The impact of a reduction in fluoride concentration in the Malaysian water supply on the prevalence of fluorosis and dental caries

Objective To assess the prevalence and severity of dental fluorosis and caries among Malaysian children following the reduction in fluoride concentration from 0.7 to 0.5 parts per million (ppm) in the public water supply. Methods This study involved lifelong residents aged 9‐ and 12‐year‐olds in fluoridated and nonfluoridated areas in Malaysia (n = 1155). In the fluoridated area, children aged 12 years and 9 years were exposed to 0.7 and 0.5 ppm, respectively, at the times when maxillary central incisors developed. Standardized photographs of maxillary central incisors were blind scored for fluorosis using Dean's criteria. Dental caries was examined using ICDAS‐II criteria. Results The prevalence of fluorosis (Dean's score ≥ 2) among children in the fluoridated area (35.7%, 95% CI: 31.9%‐39.6%) was significantly higher (P < 0.001) than children in the nonfluoridated area (5.5%, 95% CI: 3.6%‐7.4%). Of those in the fluoridated area, the prevalence of fluorosis decreased from 38.4% (95% CI: 33.1%‐44.3%) for 12‐year‐olds to 31.9% (95% CI: 27.6%‐38.2%) for 9‐year‐olds, although this difference was not statistically significant (P = 0.139). The mean caries experience in the permanent dentition was significantly lower in the fluoridated area than in the nonfluoridated area for both age groups (P < 0.05). In the multivariate models, the difference in the differences of caries experience between fluoridated and nonfluoridated areas remained statistically significant. This suggests that caries‐preventive effect is still maintained at 0.5 ppm. Conclusion Findings indicate that the change in fluoride level from 0.7 to 0.5 ppm has reduced fluorosis and maintains a caries‐preventive effect. Although there is a reduction in fluorosis prevalence, the difference was not statistically significant

Time to complete contemporary dental procedures – estimates from a cross-sectional survey of the dental team

Background: There are few contemporary studies on the time taken to complete dental procedures, those most heavily relied on in the United Kingdom date back to 1999. Objectives: This work aimed to establish how long members of the dental team took to complete specific dental procedures, relevant to their scope of practice. Methods: Data were collected via a purposive sample of 96 dentists, dental hygienists/therapists and dental nurses. Via an online survey, participants were asked to state the mean, minimum and maximum time they estimated that they took to complete individual dental procedures. Results: The mean time taken to complete procedures common to both dentists and dental hygienists/therapists ranged from 3.7 to 4 min respectively for clinical note reading prior to seeing patients to 30.1 and 28 min to undertake root surface debridement. There were no significant differences between the time taken by dentists and dental hygienists/therapists to treat adult patients. However, in all but one procedure, dental hygienists/therapists reported taking longer (p = 0.04) to treat child patients. Conclusions: The data provided here represent an up to date assessment of the time taken to complete specific tasks by different members of the dental team. These data will be of value to service planners and commissioners interested in evolving a dental care system that employs a greater degree of skill-mix and preventively oriented care

The development and application of a chairside oral health risk and need stratification tool in general dental services

Objective To describe the development and application of the Assessment of Clinical Oral Risks and Needs (ACORN) stratification tool based on a traffic light system in National Health Service (NHS) general dental services (GDS) Wales, UK. Materials and methods This was a secondary analysis of routinely-collected dental care data. All courses of treatment provided in dental practices participating in NHS GDS Reform Programme between July 2018 and September 2019, in which an ACORN assessment and age were recorded were included in the analysis. Results A total of 236,490 subjects contributed 339,933 courses of treatment during the study period. ‘Amber’ and ‘red’ ACORN outcomes were associated with more courses of treatment per annum than ‘green’ outcomes. Outcomes indicating an increased risk of decay or other dental problems were associated with a greater likelihood of several operative treatment items. Patients at greater risk of poor periodontal health were more likely to receive extractions and dentures than low-risk patients. Patients were most likely to either remain in the same ACORN outcome categories or move to a healthier state between assessments. Conclusion More research is required to understand the utility of the ACORN tool in risk communication and behaviour change

Protocol for 'Seal or Varnish' (SoV) trial: A randomised controlled trial to measure the relative cost and effectiveness of pit and fissure sealants and fluoride varnish in preventing dental decay

Background Dental caries remains a significant public health problem, prevalence being linked to social and economic deprivation. Occlusal surfaces of first permanent molars are the most susceptible site in the developing permanent dentition. Cochrane reviews have shown pit and fissure sealants (PFS) and fluoride varnish (FV) to be effective over no intervention in preventing caries. However, the comparative cost and effectiveness of these treatments is uncertain. The primary aim of the trial described in this protocol is to compare the clinical effectiveness of PFS and FV in preventing dental caries in first permanent molars in 6-7 year-olds. Secondary aims include: establishing the costs and the relative cost-effectiveness of PFS and FV delivered in a community/school setting; examining the impact of PFS and FV on children and their parents/carers in terms of quality of life/treatment acceptability measures; and examining the implementation of treatment in a community setting. Methods/design The trial design comprises a randomised, assessor-blinded, two-arm, parallel group trial in 6–7 year old schoolchildren. Clinical procedures and assessments will be performed at 66 primary schools, in deprived areas in South Wales. Treatments will be delivered via a mobile dental clinic. In total, 920 children will be recruited (460 per trial arm). At baseline and annually for 36 months dental caries will be recorded using the International Caries Detection and Assessment System (ICDAS) by trained and calibrated dentists. PFS and FV will be applied by trained dental hygienists. The FV will be applied at baseline, 6, 12, 18, 24 and 30 months. The PFS will be applied at baseline and re-examined at 6, 12, 18, 24, and 30 months, and will be re-applied if the existing sealant has become detached/is insufficient. The economic analysis will estimate the costs of providing the PFS versus FV. The process evaluation will assess implementation and acceptability through acceptability scales, a schools questionnaire and interviews with children, parents, dentists, dental nurses and school staff. The primary outcome measure will be the proportion of children developing new caries on any one of up to four treated first permanent molars. Discussion The objectives of this study have been identified by the National Institute for Health Research as one of importance to the National Health Service in the UK. The results of this trial will provide guidance on which of these technologies should be adopted for the prevention of dental decay in the most susceptible tooth-surface in the most at risk children