Finite element analysis suggests functional bone strain accounts for continuous post-eruptive emergence of teeth.
OBJECTIVE
To explore the possible role of functional stress in driving continuous post-eruptive emergence of teeth.


METHODS
A two dimensional finite element analysis model was established with a single mandibular premolar subjected to sagittal bending. Equivalent strain was charted for the inner and outer surfaces of the lamina dura, because bone deposition and resorption of this structure is confined to surface osteoblasts and osteoclasts. Bone disuse resorption was assumed to take place at equivalent strain values below 0.0008, while deposition was above 0.002. Strain in the periodontal ligament and principal stress throughout the model were also characterized.


RESULTS
Strain analysis indicated bone maintenance for the lamina dura throughout most of the root length, but in both the apical and upper root regions, resorption was predicted for the outer surface, and bone deposition was predicted for the inner surface of the lamina dura. Strain in the periodontal ligament varied little with the exception of a marked increase close to the crown. Principal stress analysis revealed compression of the lower model border, with areas of increasing tension towards the upper model border.


CONCLUSIONS
Strain from functional forces may continuously drive post-eruptive emergence of teeth through bony remodelling of the lamina dura, lifting teeth by both raising the apical lamina dura, and narrowing the upper root space to accommodate tapering root form. Such strain-driven bone turnover may contribute to pre-eruptive movement of teeth.
The Cellular and Molecular Pathology Research Unit, Department of Oral Pathology and Oral Medicine, Faculty of Dentistry, The University of Sydney, Westmead Centre for Oral Health, Westmead Hospital, NSW 2145, Australia. babak.sarrafpour@sydney.edu.au
Babak
B
Sarrafpour
Chaiy
C
Rungsiyakull
Michael
M
Swain
Qing
Q
Li
Hans
H
Zoellner
D001641:Bicuspid; D001696:Biomechanical Phenomena; D016723:Bone Remodeling / Q000502:physiology*; D003799:Dental Stress Analysis / Q000379:methods*; D020342:Finite Element Analysis; D006801:Humans; D008334:Mandible / Q000502:physiology*; D013314:Stress, Mechanical; D014078:Tooth Eruption / Q000502:physiology*; D014085:Tooth Migration / Q000503:physiopathology*; D020390:Tooth Socket / Q000502:physiology*