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Aim: The purpose of this paper is to review the most recent epidemiological data (1985-2000) on dental caries and periodontal diseases in Vietnam in an attempt to obtain a 'baseline' for future national oral health surveys., Methods: Studies on periodontal diseases and caries were included when CPITN and WHO caries criteria had been applied and when the sample size was at least n = 200 for each age group., Results: Almost all subjects had calculus. The median number of sextants with calculus in the 15-19-year- and in the 35-44-year-olds was 4.2 and 5.0, respectively. Only 2-7% of the 35-44-year-olds had one or more deep periodontal pockets. The estimated DMFT of the 12-, 15- and 35-44-year-olds was 1.8, 2.0 and 5.4, respectively, in the years around 1990., Conclusion: This review shows that (often neglected) epidemiological studies from the past on caries and periodontal diseases can contain comprehensive data sets that provide an estimate of the past oral health status which may serve as a baseline for future national surveys.

Aim: To estimate the prevalence and severity of dental caries and periodontal diseases in Syria and to determine possible secular changes in the last two decades., Methods: Epidemiological studies performed between 1980-1999, using the WHO criteria for dental caries and the CPITN criteria for periodontal diseases in Syria were retrieved and reviewed., Results: The caries experience of 5-year-old children was high (dmft of 4.7-5.2). The estimated DMFT score of 12-year-old Syrian children was 1.9-2.3. A secular change of the caries experience in the last two decades was not apparent. The amount of untreated caries lesions was high and had not changed substantially in the last two decades. The D component comprised 72-90% of the DMFT of 12-15-year-old children and 26-30% of the DMFT of 35-44-year-old Syrians. The majority of 15-24-year-olds, and more than 80% of the 35-44-year-olds had calculus. Despite the widespread and chronic existence of calculus, only 3-11% of the 35-44-year-old persons had one or more deep periodontal pockets., Conclusion: The caries experience in Syria is moderately low and does not seem to have changed in the last two decades. The increased output of graduate dentists in the last decade has not changed the large amount of untreated caries lesions. In Syria, where the prevalence of unmet (caries) treatment needs is high, regular removal of calculus (scaling) for the sake of preventing periodontal pockets should not have a high priority in the oral health services.

This paper reviews the results of studies on periodontal diseases and dental caries in Bangladesh. Almost all subjects aged 12 to 19 years (82-95 per cent) and 35 to 44 years (98-100 per cent) had calculus. The various studies showed a wide range of prevalences (14-65 per cent) of subjects with deep periodontal pockets in the age group of 35 to 44. According to a median estimate of the prevalence of subjects with deep periodontal pockets (26 per cent), it can tentatively be concluded that Bangladesh belongs to the 20 per cent of countries in the world where periodontal conditions of the population are among the worst. To assess the caries experience, median DMFT-values of age cohorts from the various studies were calculated. Twelve year olds had a DMFT of 1.7, 15 to 19 year olds of 1.6, 20 to 34 year olds of 1.0 and 35 to 44 year olds had a DMFT of 1.4. These DMFT-values are considered to be upper limit values since they were almost exclusively obtained from urban and peri-urban populations. The age effects observed indicated that there might have been an upward trend in caries activity in (urban) children before 1980. Cohort effects indicating secular changes in caries experience over the last 15 years have not been observed. It is therefore tentatively concluded that the caries activity in Bangladesh has remained stable in the last 15 years.

The purpose of the study was to determine microscopically the %s of spirochetes at sites without periodontal destruction in subjects with destructive periodontal diseases (cases) and in subjects free of it (controls), who had not received professional prophylaxis. From a sample of 164 individuals aged between 30-44 years living in rural and urban areas of Tanzania, cases and controls were selected. Cases (n = 25) were selected who exhibited at least 3 teeth with pocket depth of > 5 mm. The controls (n = 28) had no pockets deeper than 3 mm. From each subject, 1 subgingival plaque sample was taken at the mid point of the lingual surface of 1 of the upper premolars which showed bleeding on probing but no calculus and no pockets. In addition, one subgingival sample was obtained from a pocket. Pockets contained the highest %s of spirochetes, which confirms earlier findings. A significant difference in % of spirochetes between cases and controls was found at non-destructive sites, indicating a host effect on the subgingival microflora. However, the spirochete counts at non-destructive sites did not provide a reliable measure to identify subjects with destructive periodontal disease.

Changes in the periodontium produced by removal of bone cylinders at one interdental site of a dry human mandible, were recorded radiographically. These artificial lesions had diameters of 0.3 mm increasing to 1.4 mm in steps of 0.1 mm. Radiographs were obtained using 3 different X-ray tube potentials and 3 different amounts of radiation. These 9 exposure variables resulted in 9 series of radiographs from the artificial lesions. Observers were asked to determine the presence or absence of these periodontal bone lesions on conventional radiographs and on photographically subtracted images. The images were also evaluated by a quantitative digital subtraction technique. This study showed that the smallest periodontal bone changes were detected with the quantitative digital subtraction technique compared to the other methods using observers. On photographically subtracted images, smaller bone changes were detected by the observers than on conventional radiographs. Only the detection threshold of the quantitative digital subtraction technique was influenced by the 2 exposure factors: kVp and mAs.