Caries experience and related factors in 4-6 year-olds attending dental clinics in Kinshasa, DR of Congo.

OBJECTIVES: The aim of this study was to examine the prevalence and severity of caries experience (CE) in 4-6 year-olds attending dental clinics in Kinshasa, DR Congo, and to explore possible associations with reported behavioural and socio-demographic factors. METHODS: A convenience sample of children attending five dental clinics was recruited. Carers, usually parents, completed a questionnaire consisting of socio-demographic information, oral health and tobacco consumption profile of parents, socio-economic family situation and oral health habits of the child. Children were clinically examined using WHO criteria by trained dentist-examiners. To investigate factors associated with CE, multivariate logistic regression was applied with the significance level set at 0.05. RESULTS: Some 158 children with mean age 5.3 (sd 0.7) years were recruited; 80% presented with clinical signs of CE. Between-meal snacking and drinking was reported by 78% and 65%; 35% had sugar-containing drinks. Most (81%) brushed once a day and 82% brushed in the morning. Prevalence of CE was associated with gender, frequency of meals, consumption of drinks during meals and consumption of sugar-containing drinks; severity with type of infant feeding and sugar-content of the last meal at night. CONCLUSION: The present study shows that both prevalence and severity of caries experience were associated with reported dietary habits, confirming the importance of preventive interventions dealing with these habits in young children living in a developing country.

Microradiographic aspects of the growing mandibular body during permanent premolar eruption in the dog.

In order to explore the bony changes in the mandibular body during prefunctional intraosseous eruption of premolars, 18 dogs aged from 8 to 16 wk at the beginning of experimental period, were given two intraperitoneal injections of oxytetracycline (50 mg/kg and 35 mg/kg 2 wk later) and 2 wk later a final injection of Alizarin red S (70 mg/kg). Microradiographic and fluorescent light microscopy studies showed that changes of the alveolar bony crypt walls were influenced by the growing dental germs which they surrounded. The cervical volumetric reduction, which indicates the end of crown formation, induced the apposition of lamellar and then woven bone on the adjacent alveolar walls. Furthermore, with occlusal displacement of the dental crown, the space below the tooth was immediately filled with woven bone trabeculae and chondroid tissue. The same phenomenon was observed at the level of the alveolar base, when the speed of tooth eruption was greater than that of root growth. During premolar development, the changes in the dental germ produces accommodating changes in the adjacent alveolar bone walls, and mandibular transversal growth has the same characteristics as that of a growing diaphysis.

Microradiography and fluorescence microscopy of bone remodeling on the basal crypt of permanent mandibular premolars in dogs during eruption.

Alveolar bone of erupting teeth was studied in order to define the types of calcified tissues deposited as well as the rate of tooth growth. The third (P3) and fourth (P4) mandibular premolars of 30 dogs aged 12-24 weeks were analyzed by microradiography and microscopy in fluorescent and ordinary light. The bone plate separating P3 and P4 from the mandibular canal presented a complex arrangement of lamellar and woven bone, and even of chondroid tissue. During the pre-eruptive phase, this plate shifted towards the base of the mandible by means of selective resorption and apposition activities. As soon as the furcation was formed, bone apposition appeared on the alveolar side and became the main activity under P3 at the outset of eruption. Under the roots of P4 it occurred 4 weeks later. Dynamic morphometry in fluorescence microscopy showed that eruption progressed faster than the radicular growth. The formation of interradicular bone underwent the same acceleration as the eruption. However, though the tissues were formed at a high rate, it cannot be inferred therefrom that they are responsible for tooth shifting. They might just fill the space left by the erupting tooth.

[Chemical and traumatic irritation of a canine premolar tooth germ]. / Irritations chimique et traumatique d'un germe de prémolaire de chien.

The arrest of a premolar bud was observed in an animal experiment that was designed to study the influence of endodontic treatment in dogs' temporary teeth on the eruption of their permanent successors. A chemical irritation was induced by the burst of ZOE (zinc oxide and eugenol) into the dental follicle. Moreover, a mechanical trauma on the temporary molar was promoted by the dog's biting on its cage metallic bars. The devitalization effects were studied in thick undecalcified ground sections which were subjected to microradiographic analysis, to UV light microscopy in order to detect the fluorescent indicators of calcification, and finally to methylene blue staining. The arrest of the bud development was noted in fluorescent microscopic examination. Cellular cementum was formed on the pulpal surface of the dentine, while cementum, chondroid tissue, woven bone and lamellar bone developed in the pulpal tissue. These observations advise caution during root canal therapy of temporary teeth, especially those that are exposed to mechanical trauma. Such as the upper incisors.