A Validated Finite Element Method Study of Orthodontic Tooth Movement in the Human Subject

Abstract

The aim of the study was to develop a 3D computer model of the movement of a maxillary incisor tooth when subjected to an orthodontic load. A novel method was to be developed to directly and accurately measure orthodontic tooth movement in a group of human volunteers. This was to be used to validate the finite element-based computer model. The design took the form of a prospective experiment at a laboratory at the University of Wales in 1996/7. A laser apparatus was used to sample tooth movement every 0.01 seconds over a 1-minute cycle for 10 healthy volunteers, whilst a constant 0.39 N load was applied. This process was repeated on eight separate occasions and the most consistent five readings taken for each subject. Data were used to calculate the physical properties of the periodontal ligament (PDL). The data gleaned by this method were used to validate the 3D FEM model. This was formed of 15,000 four-noded tetrahedral elements. Tooth displacements ranged from 0.012 to 0.133 mm. An appropriate elastic modulus of 1 N/mm(2) and Poisson's Ratio of 0.45 was derived for the PDL. Strain analysis, using the model, suggested that a maximum PDL strain of 4.77 x 10(-3) was recorded at the alveolar crest, while the largest apical strain recorded was 1.55 x 10(-3). The maximum strains recorded in the surrounding alveolar bone were 35 times less than for the PDL. A novel method for direct measurement of PDL physical properties in the human subject has been developed. The validated FEM model lends further evidence that the PDL is the main mediator of orthodontic tooth movement.

Orthodontic mechanotransduction and the role of the P2X7 receptor

“…However, it is still a challenge to accurately quantify 3D experimental variables such as root resorption and bone formation. It is known that the mechanical stimuli for orthodontic responses are the 3D distributed stresses/strains on the root and bone-PDL (periodontal ligament) interface (Andersen et al, 1991a;Andersen, Pedersen & Melsen, 1991b;Cattaneo, Dalstra & Melsen, 2005;Davidovitch, 1991;Fukui, 1993;Jones et al, 2001;Katona et al, 1995;Kawarizadeh et al, 2003a;Kawarizadeh et al, 2004;Krishnan & Davidovitch, 2006;Melsen, 1999;Melsen, 2001;Middleton, Jones & Wilson, 1996;Provatidis, 2002;Roberts, Goodwin & Heiner, 1981;Rygh, 1976;Toms et al, 2002;Wright & Yettram, 1979). Histology provides only 2D data and the results greatly depend on the choice of the representative sections, as well as choice of method of root resorption assessment.…”

Safe rebuilding of the periodontal loss an experimental study

“…A sample of the forcedisplacement relationship for the lower incisor is presented in Models of tissue material used in the simulation models were isotropic, linear-elastic stress-strain. The literature review, as well as the personal experience, enabled the authors to select mechanical properties of particular tissues personally considered as the most adequate [11][12][13][14][15][16]. The values of the mechanical properties of these tissues are shown in Table 1.…”

En-masse Retraction of the Maxillary Anterior Teeth by Applying Force from Four Different Levels – A Finite Element Study

“…The elements are prescribed the appropriate material properties of the structure they represent. What is achieved is a mathematical model of the likely physical response of that object to load; large volumes of information about stresses, strains, and displacements being obtained through the continuum defined [13].…”