Firoze Manji

The Nature and Mechanisms of Dental Fluorosis in Man

Any use of fluorides, whether systemic or topical, in caries prevention and treatment in children results in ingestion and absorption of fluoride into the blood circulation. The mineralization of teeth under formation may be affected so that dental fluorosis may occur. Dental fluorosis reflects an increasing porosity of the surface and subsurface enamel, causing the enamel to appear opaque. The clinical features represent a continuum of changes ranging from fine white opaque lines running across the tooth on all parts of the enamel to entirely chalky white teeth. In the latter cases, the enamel may be so porous (or hypomineralized) that the outer enamel breaks apart posteruptively and the exposed porous subsurface enamel becomes discolored. These changes can be classified clinically by the TF index to reflect, in an ordinal scale, the histopathological changes associated with dental fluorosis. Compared with Deans and the TS1F index, we consider the TF index to be more precise. Recent studies on human enamel representing the entire spectrum of dental fluorosis have demonstrated a clear association between increasing TF score and increasing fluoride content of the enamel. So far, no useful data on dose (expressed in mg fluoride/kg b.w.) -response (dental fluorosis) relationships are available. In this paper, we have, therefore, re-evaluated the original data by Dean et al. (1941, 1942), Richards et al. (1967), and Butler et al. (1985) from the USA, by applying the equation of Galagan and Vermillion (1957) which permits the calculation of water intake as a function of temperature. By so doing, it can be demonstrated that there is a linear association between fluoride dose and dental fluorosis (r2 = 0.87). Even with very low fluoride intake from water, a certain level of dental fluorosis will be found in a population. When the linear dose-response curve is applied to previous data from the use of fluoride supplements, these data are in full accordance. This indicates that we already have useful data available which to some extent allows us to predict prevalence and severity of fluorosis in a child population which is exposed to a known amount of fluoride. Because dental fluorosis may occur in some individuals and populations to a higher prevalence and degree than expected, and there exist rare cases who exhibit clinical changes similar to those of fluorosis—but with no known excessive fluoride background—it is concluded that it is important to intensify studies on factors which alone or in combination can make individuals more or less susceptible to the effect of fluoride.

Tooth Mortality in an Adult Rural Population in Kenya

This paper reports on the pattern of tooth loss in a random sample of 1131 adults aged from 15 to 65 years in a rural area of Kenya in which access to formal dental care is minimal. We found that the majority of the population retained most of their dentition in a functional state even up to the age of 65 years: In all age groups, more than 50% had at least 26 teeth present, and more than 90% had at least 16 teeth present. The prevalence of edentulousness was less than 0.3%. The principal cause of tooth loss in all age groups was caries, and this was true for all tooth-types except incisors, for which periodontal disease was the main cause of tooth loss. The cultural practice of removing lower central incisors was observed only in those over 40 years of age. More teeth were lost due to caries among women than among men, while the reverse was true for teeth lost due to periodontal diseases. In view of the fact that most people retain most of their teeth throughout life, it is suggested that the most appropriate strategies for dental health care in this population should be those promoting self care, rather than the introduction of a formal treatment-oriented approach provided by dentists.

Pattern of dental caries in an adult rural population.

A study was conducted amongst 1,131 randomly selected persons aged 15-65 years in a rural area of Kenya, having minimal access to dental care. A relatively low prevalence of frank cavitation was found in the 15- to 24-year-old cohort, but in the older age groups over 80% were so affected. Caries in the youngest cohort was characterized by a predominance of enamel lesions. At the age of 25-34 years, however, involvement of pulpal tissues and loss of teeth due to caries was more common, and this age group exhibited the largest number of dentinal lesions. The 35- to 44-year-old cohort exhibited fewer enamel and dentinal lesions, but more pulpally involved lesions and more extracted teeth. In the group aged 45-54 years, enamel and dentinal lesions were less common, and at the age of 55-65 years, such lesions were less common in comparison to their occurrence in younger cohorts. The 55- to 65-year cohort could generally be characterized as having larger numbers of root surface lesions, lesions involving the pulp, and extracted teeth. Root surface lesions were principally associated with age over 35 years. In all age groups caries exhibited a skewed distribution, most of the lesions occurring in a minority of individuals. This study demonstrates that caries activity continues throughout life and is not a phenomenon confined to any one period of life.

Associations between Salivary Levels of Streptococcus mutans, Streptococcus sobrinus, Lactobacilli, and Caries Experience in Kenyan Adolescents

Salivary levels of mutans streptococci (S. mutans and S. sobrinus) and lactobacilli were determined in a random sample of rural Kenyans between 15 and 19 years of age (n = 149). It is possible for the natural history of dental caries in this population to be studied since it is characterized by a limited access to conventional dental treatment. Using a short set of biochemical tests, we identified from seven to ten presumptive mutans streptococcus colonies-cultured from the saliva of each individual-to differentiate between S. mutans and S. sobrinus. No colonies resembling S. rattus (S. mutans serotype b) were isolated. Lactobacilli were identified as Gram-positive, catalase-negative rods. The mean D1-4MFS and D3-4MFS were 7.03 ± 6.43 and 1.46 ± 3.44, respectively. The mean mutans streptococcus and lactobacillus levels were 8. 7 x 104 and 6. 7 x 104, respectively. The salivary mutans streptococcus and lactobacillus levels were significantly correlated (p<0.01). Of the subjects, 64% harbored only S. mutans, 4% only S. sobrinus, 30% both species, and 2% neither. Lactobacilli were ubiquitous. The caries experience of the group was significantly (p<0.001) correlated with both the total salivary level of mutans streptococci and the salivary S. mutans levels, but not with the salivary S. sobrinus level.

Dental Fluorosis in an Area of Kenya with 2 ppm Fluoride in the Drinking Water

We examined 102 children born and reared in an area of rural Kenya with 2 ppm fluoride in the drinking water for dental fluorosis, using the index developed by Thylstrup and Fejerskov (1978). The prevalence of dental fluorosis was 100%, 92% of all teeth exhibited a TFI score of 4 or higher, and 50% of the children had pitting or more severe enamel damage in at least half the teeth present. The fluorotic changes showed a high degree of bilateral symmetry. The intra-oral distribution of the changes corresponded to the pattern of fluoride-induced enamel changes reported by other investigators in high-fluoride areas. The high prevalence and severity of dental fluorosis in a 2-ppm-fluoride area is in accordance with recent observations on dental fluorosis being very prevalent in Kenya, even in low-fluoride areas (<1 ppm F). We are presently investigating the possible variables which may explain this unexpected susceptibility of large populations in Eastern Africa to fluorosis from exposure to low levels of fluoride.

Enamel Changes in Two Low-Fluoride Areas of Kenya

317 children born and raised in two rural areas of Machakos District in Kenya were examined for enamel changes. All sources of drinking water were monitored for F–– over a period of 1 year.

Chewing sticks, toothpaste, and plaque removal

The aim of the present study was to assess the efficacy of brushing with chewing sticks in removing plaque and to evaluate whether toothpaste has any additional effect on the removal of established dental plaque. Kenyan schoolchildren had their plaque deposits disclosed by means of disclosing tablets and subsequently recorded on four buccal sites of all permanent teeth. The children were then allocated to two groups in a crossover design; in one group the children brushed with chewing sticks and toothpaste; the other group brushed with chewing sticks only. Substantial amounts of plaque were recorded at base line in most children. Brushing with a chewing stick for 5 min resulted in a net reduction of the proportion of plaque deposit sites per child. Toothpaste resulted in no additional effect.

Transition dynamics of HIV disease in a cohort of African prostitutes: a Markov model approach.

The progression of HIV-related disease from infection to death is represented as a staged Markov model. Transitions between stages are considered reversible. The model is fitted to data from a cohort of African prostitutes by means of maximum likelihood. It appears that the progression to symptomatic disease (Centers for Disease Control stage IV) in this population is considerably more rapid than that reported from studies in Western countries.

Dentistry in crisis: time to change. La Cascada Declaration

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/adj.12546 This article is protected by copyright. All rights reserved. PROF. NEWELL WALTER JOHNSON CMG (Orcid ID : 0000-0001-5866-262X)

Caries and Periodontitis: Contesting the Conventional Wisdom on Their Aetiology

We review the literature on the oral microbiome and the role of the microbiota in the development of dental caries and periodontitis. While most research has been focused on identifying one or more specific determinants of these diseases, the results have provided limited predictive value and have not been able to explain the variation in the distribution of these diseases observed in epidemiological or clinical studies. Drawing on existing knowledge about the nature of the oral microbiota, we suggest that a stochastic model based on the Weiner process provides simple and parsimonious explanations for the pathogenesis of both caries and periodontitis, making few assumptions, and providing explanations for phenomena that have hitherto proved difficult, or have required complex arguments, to explain. These diseases occur as the result of the dental hard tissues and periodontal tissues integrating the random “noise” caused by normal metabolic activities of commensal microorganisms in the dental biofilm. The processes that result in the progression and regression of caries and periodontitis may be considered as “natural,” rather than pathological, even if, when left unchecked over long periods of time, they can result in the development of pathologies. The likelihood of progression or regression can be influenced by other determinants, but these processes will nevertheless occur in the absence of such influences. The distributional characteristics of the model approximate the findings of epidemiological studies indicating that, for both caries and periodontitis, there will be few sites affected in the early period after the eruption of the permanent dentition, but in those older there is an almost linear relationship with increasing age; furthermore, the longer a site survives without being affected, the less likely that it will be affected. We discuss the clinical and public health importance of these findings.