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Tooth dimensions in hypodontia with a known PAX9 mutation
A H Brook1, C Elcock, M Aggarwal
1International Collaborating Centre in Oro-facial Genetics and Development, University of Liverpool, School of Dental Sciences, Edwards Building, Daulby Street, Pembroke Place, Merseyside, Liverpool L69 3GN, UK.
Archives of Oral Biology
|July 26, 2008
Summary
This study found that a PAX9 gene mutation causing hypodontia (congenital tooth absence) also results in smaller tooth crown dimensions across the entire dentition, not just missing teeth.
Area of Science:
- Genetics
- Oral Biology
- Developmental Biology
Background:
- Congenital tooth absence (hypodontia) is a complex developmental anomaly.
- The genetic basis of hypodontia involves mutations in key developmental genes, such as PAX9.
- Previous studies focused on tooth number, but the impact on tooth size is less understood.
Purpose of the Study:
- To quantitatively assess tooth crown dimensions in a family with hypodontia caused by a PAX9 mutation.
- To compare these dimensions with those of an unaffected control group using advanced image analysis.
- To investigate the phenotypic effects of the PAX9 mutation on tooth morphology beyond absence.
Main Methods:
- Digital imaging of dental models from 10 affected family members (three generations) and 10 controls.
- Image analysis measured mesio-distal, bucco-lingual, area, and perimeter of teeth up to first permanent molars.
- Statistical analysis (t-tests) compared dimensions between the hypodontia and control groups; reliability assessed via ICC.
Main Results:
- High intra- and inter-operator reliability (mean r > 0.95) for image analysis measurements.
- Family members with hypodontia exhibited significantly smaller tooth crown dimensions across most tooth types and parameters.
- Greatest differences observed in bucco-lingual and perimeter measurements, particularly for upper lateral incisors.
Conclusions:
- The PAX9 mutation associated with hypodontia affects not only tooth number but also tooth crown size.
- Smaller tooth dimensions are a consistent feature across the dentition in individuals with this PAX9 mutation.
- This highlights a broader morphological impact of the PAX9 gene in dental development.
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