The long-term research goal in my laboratory is to identify morphogenetic mechanisms of craniofacial growth and development. Studies focus on growth of the cranial base and midface in skeletal Class III malocclusion. Skeletal Class III malocclusion results from a deficient midface. My laboratory is identifying deficient growth trajectories in human orthodontic groups displaying Class III malocclusion. In addition, we are using a unique mouse mutant called Brachyrrhine (Br) to examine the role of the sphenoid bone in the emergence of midfacial profile. This mutant strain shows midfacial retrognathia in a heritable fashion.

Over the past few years, we have collaborated with dental clinicians to examine the morphometric characteristics of the cranial base in human skeletal Class III orthodontic patients. This work has lead to a number of new insights including the observation that patients with Class III malocclusion display abnormal sphenoidal morphology in the cranial base. This finding is contrary to the generally accepted view that midfacial retrognthia results from deficiencies in the intramembranous osseous elements of the midface. In response to these data, clinical therapies are being modified to alter more posterior elements of the midface as well as the application of new computerized diagnostic tools developed in my laboratory. Experimental work using the Br mouse has shown that sphenoidal growth is significantly altered in this midfacially retrognathic mouse corroborating the findings from our studies involving human patients. Recently, we have begun to analyze the Br genotype. Using microsatellite mapping analysis, we have localized the Br gene to chromosome 17 in the area of D17Mit41 ± 1.9cM. High-resolution mapping studies are now being performed with the aim of sequencing the Br gene.

Related References:

Diewert, V.M., and S. Lozanoff. 2000. Animal Models of Facial Clefting. In: "Understanding Craniofacial Anomalies". M. Siegel and M. Mooney (eds). Wiley Life Sciences, New York, (in press).

Singh, G.D., J.A. McNamara, and S. Lozanoff. 2000. Soft tissue thin-plate spline analysis of prepubertal Korean and European-American Subjects with untreated Angle’s Class III malocclusions. Submitted to Journal of Craniofacial Genetics and Developmental Biology .

Lozanoff, S. 1999. Sphenoethmoidal growth, malgrowth and midfacial profile. In: On Growth and Form: Spatio-temporal Patterning in Biology. Chapter 19. MAJ Chaplain, GD Singh and J. McLachlan (eds.). John Wiley and Sons, New York, pp: 357-372.

Singh, G.D., J.A. McNamara, and S. Lozanoff. 1999. Finite element morphometry of soft tissues of prepubertal Korean and European-American Subjects with Class III malocclusions: Finite element morphometry. Archives of Oral Biology, 44:429-436.