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Biomedical subjects

G Townsend

Publications and source records attributed to G Townsend.

41 records · Page 3Linked to original sources
PubMed1984

Reduced tooth size in 45,X (Turner syndrome) females.

Mean values and variances of deciduous and permanent tooth dimensions were compared between 121 45,X (Turner syndrome) females and 171 control subjects to clarify the role of the X chromosome on dental development. Although deciduous molars tended to be smaller than normal in 45,X females, there was no evidence of a reduction in tooth size for deciduous anterior teeth. In the permanent dentition, all mesiodistal dimensions were significantly smaller in 45,X females but only some of the buccolingual dimensions were smaller. The findings for deciduous tooth-size may reflect a sampling effect related to the extremely high frequency of spontaneous abortion in 45,X individuals. Results for permanent teeth are consistent with the concept of a decrease in enamel thickness in 45,X females.

Dental Enamel↗
PubMed1982

Dentition of a 48,XYY,+21 male.

Although the dentition of a 48,XYY,+21 male showed some typical features of Down's syndrome, metric analysis indicated a marked increase in tooth size particularly for early developing teeth. The extra Y chromosome can influence phenotypic expression, overcoming the superimposed effects of the additional 21 chromosome.

Chromosome Aberrations↗
PubMedDate not supplied

Effect of Down syndrome on the dimensions of dental crowns and tissues.

Abnormal growth in Down syndrome (DS) is reflected by variable reduction in size and simplification in form of many physical traits. This study aimed to compare the thickness of enamel and dentine in deciduous and permanent mandibular incisor teeth between DS and non-DS individuals and to clarify how these tissues contribute to altered tooth size in DS. Sample groups comprised 61 mandibular incisors (29 permanent and 32 deciduous) from DS individuals and 55 mandibular incisors (29 permanent and 26 deciduous) from non-DS individuals. Maximum mesiodistal and labiolingual crown dimensions were measured initially, then the crowns were sectioned midsagittally and photographed using a stereomicroscope. Linear measurements of enamel and dentine thickness were obtained on the labial and lingual surfaces of the crowns, together with enamel and dentine-pulp areas and lengths of the dentino-enamel junction. Reduced permanent crown size in DS was associated with a reduction in both enamel and dentine thickness. After adjustments were made for tooth size, DS permanent incisors had significantly thinner enamel than non-DS permanent teeth. The DS permanent teeth also exhibited significant differences in shape and greater variability in dimensions than the non-DS permanent teeth. Crown dimensions of deciduous incisors were similar in size or larger in DS compared with non-DS deciduous teeth. Enamel and dentine thicknesses of the deciduous teeth were similar in DS and non-DS individuals. The findings indicate that growth retardation in DS reduces both enamel and dentine deposition in the permanent incisors but not in the earlier-forming deciduous predecessors. The results are also consistent with the concept of amplified developmental instability for dental traits in DS.

Adolescent↗