Surfaces Of First Molars Research Articles

Timing of first fillings on different permanent tooth surfaces in Finnish schoolchildren.

The timing of the placement of first fillings because of caries on different permanent tooth surfaces was determined at three health centers in Finland. The 927 subjects analyzed were born either in 1970-71 o4 in 1980-81. Basically, two different types of filling placement site were identified: 1) fissures and pits and 2) proximal and smooth surfaces. In some fissures and pits a 'post-eruptive'--that is, fillings placed in the year of emergence--was observed. This step had decreased markedly in the cohort born in 1980-81. The curves plateaued (retardation phase) at 50-60% for the occlusal surfaces in first molars for the children born in 1970-71 and at 20-30% for the younger cohort. The time without any filling varied from 1 to 7 years on smooth surfaces, and some surfaces remained totally filling-free. The filling placement curves followed the pattern of caries attack and can thus be used as an indicator of dental health.

Juvenile periodontitis – pattern of progression and relationship to clinical periodontal parameters

The present investigation was carried out 1) to identify subjects with juvenile periodontitis (JP) in a group of schoolchildren from a community with a high prevalence of periodontal diseases and with no access to preventive dental care, and 2) to study the clinical features of the disease and the progression pattern during a period of 1 yr, and the relationship of JP to clinical periodontal parameters. The periodontal condition of a group of 502 Iraqi schoolchildren (260 girls and 242 boys) was assessed radiographically and clinically at baseline. Children showing > or = 3 mm arc-shaped angular radiographic bone loss at the proximal surfaces of two or more first molars and who showed clinical attachment loss at the same sites were regarded as JP patients. A second group of children with no signs of JP were randomly chosen from the study material. One year later, the JP and the non-JP groups were re-examined radiographically and clinically to assess plaque, gingivitis and presence of calculus. The results showed that nine children (1.8%) had JP. The ratio of girls to boys was 3.5:1, and of localized to generalized forms 2:1. Mesial surfaces of first molars were more often affected than distal surfaces. Clinical assessments showed a more profound loss than was depicted radiographically. All JP patients exhibited evidence of periodontal disease progression during the following year. There were no differences between JP and non-JP children with respect to gingival inflammation, dental plaque, or calculus deposits on teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of prenatal caffeine exposure on the enamel surface of the first molars of newborn rats

Timed-pregnant rats were randomly divided into three groups at day 7 of gestation. A caffeine tablet was implanted subcutaneously in the experimental group and a placebo tablet in the control group. The third group was used as surrogate dams. At birth, eight randomly selected pups born either to the experimental or control dams were placed with surrogate dams that had produced pups on the same day; these were then used in either the experimental or the control group, and so the surrogate dams raised pups that came from either the experimental or control group. At day 22 after birth, the pups were killed, and their first and second maxillary and mandibular molars were removed. They were then placed in a specially designed chamber and exposed to an acid solution. The outflowing acid solution was collected every 20 min and up to 80 min. Then the calcium, phosphorus, and magnesium contents of each fraction were measured. The enamel surfaces of untreated and acid-treated first molars of the caffeine and control groups were examined by scanning electron microscopy. Untreated teeth were powdered and separated into enamel and dentine. Pure enamel samples were examined with a Gandolfi X-ray powder camera to measure the crystallite size. At 20-, 40- and 60-min intervals, calcium and phosphorus contents of the first molars of the caffeine group were significantly higher than those of the control. The enamel surface of the untreated and acid-treated first molars of the caffeine group had significantly different scanning microscopic appearances from those of the non-caffeine untreated and acid-treated control groups. The more diffuse lines in the caffeine group than in the controls suggested that the enamel crystallites were smaller. The findings unequivocally indicate that caffeine exposure of fetuses through maternal caffeine intake during gestation affects the developing first molars of newborn rats.

The prevalence of caries in groups of children aged 4-5 and 7-8 years in Khartoum, Sudan.

A total of 544 children, 275 pre-school children (aged 4-5 years) and 269 school children (aged 7-8 years), were examined for dental caries using WHO criteria with some modifications. The children were resident in Khartoum, Sudan. The mean dmft was 1.68 in the 4-5-year group, and 58% of them were caries-free. In the 7-8-year group the mean dmft (molars and canines) was 2.77, and 33% of the children were caries-free. Most of the caries in both groups was untreated. In decayed teeth which were not beyond repair, occlusal caries was most prevalent in the pre-school group and approximal caries most prevalent in the school group. The mean DMFT in the 7-8-year group was 0.15, and only occlusal surfaces in first molars were affected. Ninety-four percent in the 7-year group and 88% in the 8-year group were caries-free in the permanent dentition. When the children were grouped according to their socio-economic level, there were no statistically significant differences in caries prevalence between the groups. Since this is the first comprehensive caries prevalence study of these age groups in Sudan, it is impossible to conclude whether caries is increasing or not. The prevalence of caries-free preschool children is above the global goal of FDI/WHO for the year 2000, but below the goal for developing countries.

Periodontal disease progression in teenagers with no preventive dental care provisions

Periodontal disease progression was studied on bitewing radiographs taken at baseline and after 1 year for a group of 422 teenagers who had no access to preventive or therapeutic dental services. Subjects exhibiting one or more proximal surfaces of 1st molars with longitudinal bone loss and/or with vertical bone defects at the 2nd examination were regarded as periodontal risk patients. This group then underwent a further examination in which periapical radiographs of the anterior teeth were taken and the clinical loss of attachment at the proximal surfaces of all teeth was assessed. Subsequently, the radiographic and clinical states of the risk group were compared. Most sites exhibiting bone loss during the study period displayed vertical bone defects and were largely confined to mesial surfaces of first molars. 24% of sites showing alveolar bone loss at baseline demonstrated further loss 1 year later. Girls exhibited significantly higher prevalence and incidence of sites showing bone loss than did boys. 24 children (5.7%) were regarded as periodontal risk patients. The radiographs significantly underestimated the prevalence of periodontal destruction in the risk group as compared to clinical measurements. It was concluded that using 2 bitewing radiographs is adequate for the identification of risk subjects, and that periodontal progression in adolescence occurs mainly in the first molar region and may affect girls more often than boys.

The occurrence of Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, Bacteroides intermedius and spirochaetes in the subgingival microflora in relation to the early onset of periodontitis in a group of adolescents.

Subgingival samples were obtained from mesial and distal surfaces of first molars in 100 subjects aged 14 years at baseline. Sites were monitored at 6-monthly intervals for clinical loss of attachment. Six subjects showed greater than 1 mm loss of attachment at one site 18-24 months later. Further samples were obtained from these sites together with a comparison sample from the contralateral site and equivalent sites in a matched control subject. Actinobacillus actinomycetemcomitans was more frequently isolated from sites following loss of attachment, but it was also found in one comparison site and one control subject. Bacteroides gingivalis was found in only one subject at a site which subsequently experienced loss of attachment. A higher median proportion of spirochaetes was observed in sites after diagnosis of loss of attachment. The median proportion of Bacteroides intermedius was higher at both the baseline and 12-month examinations in subjects who subsequently lost attachment. Further work is required to substantiate the differences which preceded diagnosis of loss of attachment.

Gingival recession in schoolchildren at 7, 12 and 17 years of age in Espoo, Finland.

The present study was undertaken in response to a growing concern among clinicians about an increase in gingival recession among children and adolescents. Groups of 50 boys and 50 girls aged respectively 7, 12, and 17 yr were examined at Espoo Health Centre in 1983. Gingival recession was measured on the facial and lingual aspects of all permanent teeth. Whenever the gingival margin was located on root cementum, the distance from the gingival margin to the enamel border was measured to the nearest 0.5 mm. Recession was categorized as "slight" (0.5 or 1 mm) or "extensive" (1.5-3.5 mm). The prevalence of gingival recession was 5% at 7 yr, 39% at 12 yr, and 74% at 17 yr of age. More girls than boys had recession in the two youngest age groups. At 17 yr recession was equally common in both sexes and both "slight" and "extensive" recession was most often recorded on facial surfaces of first molars, premolars and canines. The alarmingly high prevalence of gingival recession at young age warrants further study of both the reasons and the consequences of early cementum exposure.

Three-dimensional measurements of the occlusal surface of upper first molars in a modern Japanese population.

Moiré photographs of the occlusal surface of first molars of Japanese children were taken by means of a specially designed moiré contourograph apparatus. They were then used for three-dimensional measurements. The heights of 4 cusps and some other points were measured by counting contour lines. Distances and angles between them were also measured. Sex differences of these measurements are found mainly around the metacone and hypocone. There is no clear correlation of the four cuspidal heights to the distances between them.

Variation in caries prevalence related to combinations of dietary and oral hygiene habits in 6-year-old children.

The original sample consisted of 179 randomly chosen children aged 6 years and 1 month at the time of examination. Of these children, those 88 were selected who had been exposed, since the age of 4, to consistent oral hygiene measures and dietary habits. The investigation involved clinical registration of caries, including subsurface lesions, and restorations in buccal and lingual surfaces in primary molars and cuspids. The mesial surface of second molars, distal and mesial surfaces of first molars, and the distal surface of cuspids were recorded from X-ray pictures. 85 children were classified as follows, beletary habits: (1) > 6 or (2) 5–6 meals and snacks a day including at least one ‘unsuitable’ Dack with a high-sucrose component, or (3)

A Study on the Illumination of Dental Surfaces

Although there is much published literature on lighting equipment in the dental field, studies on the illumination in this field are scanty. In the present study, the author was concerned with the measurement of illuminative degrees on the surfaces of individual teeth by directly introducing photoconductive cells into the mouth of a subject. Along with the measurement of illumination on the teeth, efforts were also made to find out how much contribution would be made by the dental mirror by way of promoting the dental surface illumination.For experimental purposes, a complete denture was constructed with 16 photoconductive cells embedded on the distal, lingual and buccal sides 6, labial side of 1, lingual side of 1, occlusal surfaces of 4 5 6 7 distal, lingual and buccal sides of 6, occlusal surfaces of 4 5 6 7. This experimental denture was installed in the mouth, so that indices of the photoconductive cells on the illuminative surfaces would be measured and the indices were subsequently converted numerically by the illuminometer. A subject was instructed to sit in a dental chair and light was projected from three directions: the occlusal surface of the upper jaw (A), the occlusal surface of the lower jaw (C), and midway between the two (B). At the same time, three positions of 20° right of the median line (X), median line (Y) and 20° left of the median line (Z) were established. Therefore, light was be projected from each of these nine directions.As a result of these comprehensive efforts, the author arrived at the following conclusions.1) Under direct light at the different positions, the degree of illumination increased in the order of A, B and C with the upper jaw; the highest degree was registered on the labial surface of the central incisors and the lowest was on the distal surface of first molars. The lowest was on the distal surface of the first molars at a position of CX, the latter corresponding to only 0.1% of the former.2) With the exception of a 19mm dental mirror for the distal surface of the upper and lower first molars, dental mirrors with larger diameter were found to be more efficient. A dental mirror of much larger diameter, devised for the purpose of this study, was quite efficient.3) All of the commercial dental mirrors failed to come up to the Japanese Industrial Standards in the rate of light reflection.4) Although a dental mirror of small diameter had a large reflecting rate, mirrors of larger diameter had correspondingly large reflecting rates on the whole.5) In separating colored rice grains by subjects inexperience with dental mirrors, the 19mm mirror was found less efficient than the 35mm mirror and, when a mirror of smaller diameter was used, more sense of fatigue was complained of. The result was more or less the same with dentists. The illumination of 34000 lux was very efficient. The fact that the 35mm mirror was very efficient was also endorsed by the findings of a flcker test.6) In a test where Landolt rings were used, the findings were also in favor of the 35mm mirror and 34000 lux. From these facts, it was found that the efficiency differed according to the diameter of dental mirrors and projecting rates.7) In a group dental examination, it was found that working efficiency and accuracy of the diagnosis were definitely influenced by the diameter of the dental mirrors used.