Recent Studies

The prevailing question we address is how does the whole tooth-periodontal ligament-alveolar bone complex function during mastication? We use a top down approach in this research, and have taken advantage of optical metrology methods that make it possible to map deformations on the surface of a tooth (Lev-Tov Chattah et al., 2009; Zaslansky et al., 2006a; Zaslansky et al., 2006b). We have shown that when loaded both the tooth itself deforms, as well as the soft periodontal ligament (PDL) in ways that complement each other. Furthermore different tooth types seem to have different ways of deforming under load (). Recently we have taken advantage of a high resolution microCT (XRadia) to monitor how a tooth actually moves in the root cavity when loaded. We found that even well within physiological loads, the root surface interacts directly with the bone surface at specific contact points. It is these contact points which essentially dictate much of the whole tooth movement under load (Naveh et al., 2011).

Figure 5. 3D view of the rat M1 in the alveolar bone socket. The molar and surrounding bone were volume rendered using “Avizo” software, and superimposed on a 2D slice. The bone is virtually “cut” in the distal-mesial plane that includes the furcation to expose the internal structure, and reveals the relatively thick PDL of the mesial and distal roots. The arrows indicate the rocking or see-saw like motion observed when the tooth is loaded on either the mesial or distal cusps. Scale bar: 500 microns. (From Naveh et al 2012).

During this study Naveh observed that in the high humidity environment of the loading chamber and with the optical set up of the XRadia, that the soft collagenous network of the PDL can be imaged directly without the need for fixing or staining (Naveh et al., 2012b). Naveh et al report that there two types of collagen networks – a dense network and a sparse network and that one functions mainly under compression (sparse network) and the other dense network mainly in tension. This new method opens up the opportunity to explore many soft tissue 3D structures. See Naveh et al for a review of the response of the tooth-PDL-bone complex to loading (Naveh et al., 2012a).

Figure 6. 3D volume rendering of a loaded M1 lingual root. A. Cross-section through half of the PDL surrounding the root viewed in the buccal direction. Black arrows show the longitudinal sheets, white arrows show the oblique sheets. b Thinned 3D cross-section of the same image in figure 4a. c Transverse section at the level of line no. 1 in figure 4a. d. Transverse section, more apically, at the level of line no.2. in figure 4a. Note that towards the apex, where the blood vessels and nerves enter the tooth, the spaces between the sheets are larger. D is for distal, M is for mesial. Scale bar for all images:  100 microns. (From Naveh et al 2013)