Biomedical subjects

W G Geraets

Publications and source records attributed to W G Geraets.

25 records · Page 2Linked to original sources

PubMed1991

[Approximal caries in children].

A longitudinal radiological study in children (N = 549) who participated in a comprehensive maintenance program (they were treated in the clinic of the Department of Pedodontics of the Academic Centre for Dentistry Amsterdam) suggests that changes in the approximal surfaces of deciduous molars may differ from the changes in the approximal surfaces of permanent (pre)molars. Regression and initiation possibly occur more frequently in the deciduous teeth than in permanent teeth.

Adolescent↗

PubMed1990

A new method for automatic recognition of the radiographic trabecular pattern.

This study reports a method to describe and analyze the structure of the trabecular pattern seen on radiographs of the distal radius. The structure is measured and related to the bone mineral density (BMD) of the lumbar spine measured by dual-photon absorptiometry. Radiographs of hand and wrist combined with additional information of the bone mineral density of the vertebrae serve as testing material. With a computer-aided imaging system, a part of the depicted radius is scanned. The image is filtered and segmented into a bilevel picture consisting of a light network with dark meshes. Seven features of the bilevel picture are measured and analyzed. It is shown that six features correlate significantly with the bone mineral density measured at the lumbar spine, although the correlations between the trabecular pattern and the BMD are too weak to allow precise predictions of BMD values for individuals. Nevertheless, the correlations confirm the existence of a relationship between the radiographic trabecular pattern and the bone mineral density of the lumbar spine. The method is worth being further developed for use on individual patients. It provides a noninvasive tool to make an objective and quantitative assessment of the trabecular pattern.

Absorptiometry, Photon↗

PubMed1990

Posteruptive age dependency of cariogenic changes in enamel of permanent teeth of children.

During a cariogenic attack at the enamel surface a white spot can be formed (initiation) or disappear (regression) or remain the same (stabilisation). In the present clinical study it was shown that at least regression and stabilisation depend significantly on the posteruptive age and may be associated therefore with changes in porosity or mineral composition in the young enamel surface after eruption. In contrast, the progression of a white spot towards a cavity, which took place in this study almost exclusively in the fissures, does not change with posteruptive age. An explanation for this may be that in such white spots remineralization is less effective due to retention of acids in the fissures. On the other hand, rapid development of a cavity from sound enamel within half a year decreased with posteruptive age.

Adolescent↗

PubMed1985

Digitized image processing and pattern recognition in dental radiographs with emphasis on the interdental bone.

Diagnosis of bone lesions on dental radiographs can be difficult due to the irregular trabecular pattern and subjectivity on the part of the observer. The purpose of this study is to improve the recognition of bone lesions by means of objective computer-aided pattern recognition techniques. This article describes a method for the separation of teeth and bone regions in the image to facilitate further analysis, especially of the interdental bone.

Alveolar Process↗

PubMed1985

Digitized pattern recognition in the diagnosis of periodontal bone defects.

Radiography is an important tool in the diagnosis of periodontal bone lesions. Due to subjective factors in the interpretation by the observer, however, an error-free diagnosis of bone lesions in an early stage is very difficult. The aim of this study was to reduce the influence of observer subjectivity by means of computer-assisted image processing and pattern recognition in dental radiographs. The findings of the study show that periodontal lesions can be recognized and described in an objective way by means of digitized pattern recognition.

Alveolar Process↗

PubMedDate not supplied

The radiographic trabecular bone pattern during menopause.

The purpose of this study is to increase the diagnostic value of radiographs by observing the radiographic trabecular pattern during occasions of changing three-dimensional bone structure. We explored how the shape of the radiographic trabecular pattern of the distal radius relates to bone mineral density, time, and menopausal status. We found that the trabecular pattern correlates with bone mineral density and time, especially in the early years of the climacterium.

Bone Density↗

PubMedDate not supplied

Influence of fluoride in saliva during the early cariogenic changes in the enamel of boys and girls.

In boys and girls cariogenic changes in the dental enamel in relation to fluoride (F-) concentrations in stimulated and unstimulated saliva were studied in a six-month period. Also the use of various types of applications of F- was assessed. No difference in the use of F- between boys and girls before and after the interval was observed. Also no clear differences were found between boys and girls in the levels of F- in both types of saliva, determined at the end of the six-month period. The most important finding was that for all children, a significantly positive relationship was found between the disappearance of white spots turning into sound enamel (regression) and the F-concentration in unstimulated saliva. In addition, girls who developed new white spots had higher levels of F-, but those who developed new cavities had lower F- levels in both types of saliva. Apparently F- can prevent dental caries by acting very early on remineralization and demineralization processes in enamel surfaces.

Adolescent↗