The development of the dentition is a good model of general development; it has the general characteristics of a complex adaptive system. The developmental variation of hypodontia presents with a reduced number of teeth with several other phenotypic changes. The teeth formed are smaller in size, have different crown and root morphology and are delayed in development. The present study is a component of a multi-centre and multidisciplinary collaborative study to investigate hypodontia from genotype to phenotype. This study uses enhanced 3D-imaging techniques in order to increase the range of parameters of the phenotypic outcome: tooth size and tooth shape. The sample consists of orthodontic patients, 60 with hypodontia (30 males and 30 females), and 60 controls matched for age, sex and ethnicity. The material studied for these measurements are the dental models of each patient; these have been imaged with an Amann Girrbach Ceramill Map400 3D scanner. The 3D images produced were all taken by one operator and viewed on MeshLab. The accuracy of the measurements taken was determined through repeat measurements of the same images, undertaken to determine intra and inter-operator reproducibility. This new system was validated by repeating these measurements using the standard 2D caliper technique. Ten repeat measurements were taken on ten models of the lower and upper premolar inter-cuspal distances. The average intra-operator reproducibility for the inter-cuspal distances when measuring the distance between the buccal and palatal cusp of the maxillary premolar was 0.20 mm; the mandibular premolar was 0.32 mm. The results for inter-operator reproducibility demonstrate an average difference of 0.24 mm for the maxillary premolar and 0.16 mm for the lower premolar. This novel method provides an increased range of measurements with good levels of accuracy. This study will go on to establish the variations on the 3D images between the hypodontia and the control group.
3D-Imaging, complex adaptive system, error, hypodontia, inter, intra, linear, measurement, reliability, reproducibility
 AlShahrani, I., Togoo, R.A. & AlQarni, M.A., A review of hypodontia: classification, prevalence, etiology, associated anomalies, clinical implications and treatment options.
World Journal of Dentistry, 4(2), pp. 117–125, 2013. https://doi.org/10.5005/jp-journals-10015-1216
 Werther, R. & Rothenberger, F., Anodontia, a review of its etiology with presentation of a case. American Journal of Oral Surgery, 25, pp. 61–81, 1939.
 Brook, A.H., Dental anomalies of number, form and size: their prevalence in British schoolchildren. Journal of the International Association of Dentisity for Children, 5(2),
pp. 37–53, 1974.
 Brook, A.H., O’Donnell, M.B., Hone, A., Hart, E., Hughes, T.E., Smith, R.N. & Townsend, G.C., General and craniofacial development are complex adaptive processes
influenced by diversity. Australian Dental Journal, 59, pp. 13–22, 2014. https://doi.org/10.1111/adj.12158
 Taduran, R.J.O., Ranjitkar, S., Hughes, T., Townsend, G. & Brook, A.H., Complex systems in human development: sexual dimorphism in teeth and fingerprints of Australian
twins. International Journal of Design & Nature and Ecodynamics, 11(4), pp. 676–685, 2016. https://doi.org/10.2495/DNE-V11-N4-676-685
 Brook, A., Koh, K. & Toh, V., Influences in a biological complex adaptive system: environmental stress affects dental development in a group of Romano-Britons.
International Journal of Design & Nature and Ecodynamics, 11(1), pp. 33–40, 2016. https://doi.org/10.2495/DNE-V11-N1-33-40
 Koh, K., Toh, V., Brook O’Donnell, M., Ranjitkar, S. & Brook, A., A complex adaptive system in which environmental stress affects gene expression during development.
International Journal of Design & Nature and Ecodynamics, 11(4), pp. 686–695, 2016. https://doi.org/10.2495/DNE-V11-N4-686-695
 Lam, F., Yong, R., Ranjitkar, S., Townsend, G.C. & Brook, A.H., Agents within a developmental complex adaptive system: intrauterine male hormones influence human tooth
size and shape. International Journal of Design & Nature and Ecodynamics, 11(4), pp. 696–702, 2016. https://doi.org/10.2495/DNE-V11-N4-696-702
 Patel, P., Yong, R., Ranjitkar, S., Townsend, G. & Brook, A., Agents within a development complex adaptive system: intrauterine male hormones and dental arch size
in humans. International Journal of Design & Nature and Ecodynamics, 11(4), pp. 703–711, 2016. https://doi.org/10.2495/DNE-V11-N4-703-711
 Brook, A.H., Elcock, C., Al-Sharood, M.H., McKeown, H.F., Khalaf, K. & Smith, R.N., Further studies of a model for the etiology of anomalies of tooth number and size in
humans. Connective Tissue Research, 43(2–3), pp. 289–295, 2002. https://doi.org/10.1080/03008200290000718
 Cicchetti, D., Guidelines, criteria, and rules of thumb for evaluating normed and standardized assessment instruments in psychology. Psychological Assessment, 6(4),
pp. 284–290, 1994. https://doi.org/10.1037/1040-35126.96.36.1994
 Harris, E.F. & Smith, R.N., Accounting for measurement error: a critical but often overlooked process. Archives of Oral Biology, 54(1), pp. 107–117, 2008.
 Bell, A., Ayoub, A. & Siebert, P., Assessment of the accuracy of a three- dimensional imaging system for archiving dental study models. Journal of Orthodontics, 30,
pp. 219–223, 2003. https://doi.org/10.1093/ortho/30.3.219
 Moreira, D., Gribel, B., Torres, G., Vasconcelos, K., Freitas, D. & Ambrosano, G., Reliability of measurements on virtual models obtained from scanning of impressions
and conventional plaster models. Brazilian Journal of Oral Sciences, 13(4), pp. 297–302, 2014. https://doi.org/10.1590/1677-3225v13n4a11
 Stevens, D., Mir, C., Nebbe, B., Raboud, D., Heo, G. & Major, P., Validity, reliability, and reproducibility of plaster vs digital study models: comparison of peer assessment
rating and Bolton analysis and their constituent measurements. American Journal of Orthodontics and Dentofacial Orthopedics, 129, pp. 794–803, 2006.