Mobility is a fundamental characteristic of dental biomechanics, allowing the tooth to move within its socket to disseminate and relieve loads. Tooth mobility is determined structurally by periodontal tissues (ligament, gingiva, extracellular matrix and attachments to cementum and bone) and functionally by occlusal and muscular forces, and has been one of the most widely used periodontal parameters to determine individual tooth prognosis. However, excessive mobility may not be a valid indicator for extraction, because mobility is also an intrinsic protective and adaptive response. Effective treatment planning requires an understanding of the normal range of tooth mobility during function. Surprisingly, functional tooth mobility has never been directly measured, thus we know neither the normal range of movement nor the threshold for "excessive" mobility. Consequently, clinical guidelines for the management of unstable teeth do not exist. The lack of such data reflects the difficulty of making intraoral measurements during normal function as well as the impossibility of performing invasive studies on human subjects, much less clinical patients. Hence, we propose to develop a minipig model. This species is the most accepted and well-described animal analogue to human mastication and its multi-rooted posterior teeth are quite similar to those of humans. Through the innovative combination of implantable miniature transducer technology for measuring 3D tooth root displacement within its socket and accompanying alveolar bending and interstitial fluid pressure, we plan to examine the normal range of functional mobility of mesial roots of the maxillary first molar (Aim 1), and to assess how these physiological kinetics are affected by various degrees of alveolar bone loss (Aim 2). The work will establish proof-of-principle for the engineering methods involved and baseline data for planned future studies that will investigate the prognosis for teeth that are mobile because of loss of alveolar bone. The deliverables of the proposed study will be the first in vivo determinations of how chewing displaces teeth, and the potential translational payoffs will be to develop better clinical strategies to preserve compromised teeth.
Knowledge of functional tooth mobility will translate into improved clinical understanding of occlusal pathologies, periodontal diseases, dental trauma, orthodontic treatment, and craniofacial growth abnormalities. The proposed studies will provide for the first the measurements of tooth mobility during mastication, and will show how it is affected by progressive alveolar bone loss. The findings will have direct relevance for developing better treatment strategies for the retention of compromised teeth. Furthermore, the proposed work will provide baseline biomechanical data for bioengineering replacement teeth that can function appropriately and for computational models.