The puzzle of Tooth Eruption

28 March 2013

The long-standing puzzle of how teeth erupt into the mouth may have been finally solved by an interdisciplinary team of Faculty researchers. It has long been assumed that there is an 'eruptive force' driving teeth out of the bone, but there is little evidence for this and there are inconsistencies between clinical observations and previous theories on the 'eruptive force'.

Prof Zoellner of Oral Pathology has been studying how biological function affects biological form by investigating the microcirculation, but has recently widened his focus to also include bone. Since bone changes shape according to functional loading, Prof Zoellner considered whether bite forces might distribute strain around unerupted teeth in such a way as to drive eruptive bone remodelling.

The expertise of a multidisciplinary team was assembled including Prof Swain of Bomaterials Science and Prof Li of Mechanical Engineering, and PhD student Dr Sarrafpour then constructed a computer three-dimensional model of an 8 year old child's lower jaw containing several unerupted teeth. Using this computational model, Dr Sarrafpour studied internal jaw strain during application of bite forces at both the front and back of the mouth. The thin layer of soft tissue surrounding unerupted teeth was seen to experience far more deformation than bone itself during biting. Importantly, patterns of compression and tension within these soft tissues suggested bone formation and resorption in such a way that teeth would be carried into the mouth.

This work thus establishes a new biomechanics based theory for tooth eruption in which there is no true 'eruptive force', and seems more consistent with clinical and experimental observations than earlier theories. The results of this study have just been published in the prestigious multidisciplinary journal PLoS One. Work continues in development of this conceptual breakthrough, aiming towards novel computer-aided therapies exploiting physiological tooth movement for improved orthodontic outcomes.

A/Professor Hans Zoellner
A/Professor Hans Zoellner