1Dows Institute for Dental Research, University of Iowa, 2Orthodontics Private Practice, Iowa City, Iowa, 3Department of Orthodontics, University of Iowa, 4Department of Prosthodontics, University of Iowa
Friday 2:00-2:15, 200ABC
Human dental arch shape is an important aspect of craniodental variation with implications in evolutionary biology, comparative anatomy, functional morphology, and clinical treatment. Most studies have focused on characterizing the morphological variation in dental arches; however the genetic determinants underlying such variation are largely unknown, particularly in individuals with severe malocclusion. To address this knowledge gap, a largely Euro-American adult sample (n=276) of dental casts (100 males, 179 females) presenting moderate to severe distal and mesial malocclusion (i.e. Class 2 and Class 3 malocclusion) were digitized in occlusion and landmarked with 58 landmarks along the gingival margins of the maxillary and mandibular arches. 3D coordinate landmark data were analyzed in MorphoJ using relative warps analysis (RWA) to extract symmetric and asymmetric arch shape phenotypes. For a subsample of 115 individuals, phenotypes were regressed (adjusting for sex) against genotypes of 23 single nucleotide polymorphisms (SNPs) within 16 candidate genes (PAX7, EPB41, ABCA4, IRF6, LEFTY1, LEFTY2, MSX1, 4p16, PiTX2, GHR, ISL1, 8q, FOXE1, MAFB, SNAI1) implicated in human midfacial and mandibular phenotypes, symmetry, and dental variation. Significant (p<0.05) correlations for symmetric shape components representing variation in antero-posterior and transverse arch relations were found with GHR and LEFTY2 respectively. Also, significant correlations were found for asymmetric shape components demonstrating right to left arch rotations and ABCA4, IRF6, LEFTY1, PAX7 and TGFB3. Finally, centroid size was correlated with LEFTY1 and 4p16 and fluctuating asymmetry was correlated with PITX2. Results provide insights into the craniofacial genetic pathways that are also important in determining arch shape.
Funding for the research provided by: AAOF 2008 OFDFA, National Center for Advancing Translational Sciences, and the National Institutes of Health (NIH), through Grants 2 UL1 TR000442-06, T32-DEO14678-09 and T32 DE 14678-10.