University of Sydney researchers have found chewing and biting to be the cause of adult teeth breaking through the gums rather than an innate, unknown force.

Dr Babak Sarrafpour and his team of researchers from the faculties of Dentistry and Engineering and Information Technologies developed a 3D biomechanical model that shows the stress distribution within the jaw as it bites and chews.

Dr Sarrafpour says that his multidisciplinary team used CT scan images of an eight year old’s mandible to design a 3D model they could then use to look at the forces produced by the jaw when biting and chewing.

“We designed the hard and soft tissues in the jaw and input the data we had about jaw movements into the software. We simulated both the back teeth and front teeth chewing and we could assess the stress on the teeth, bone and soft tissue,” he says.

It was found that the chewing and biting actions of the jaw deform the thin layer of soft tissue surrounding the teeth that are yet to appear, forcing them outwards. Dr Sarrafpour says the team developed the theory after a number of long–standing hypotheses were unsupported by clinical evidence.

“There were a number of hypotheses surrounding how adult teeth erupted. Perhaps it was from the root forming and pushing the tooth towards oral cavity, maybe it was the blood pressure in dental pulp or perhaps it was the periodontal ligaments forming and contracting, pushing against the tooth.

“However there were a number of studies that showed even if you disconnected the root and the ligaments from the tooth, it would still erupt through the bone. So we developed the theory that perhaps soft tissue dental follicle around unerupted adult teeth acts as a mechanosensor in response to biting forces and remodels surrounding bone in a way that carries the tooth to the mouth.”

It’s believed this research could perhaps lead to further preventative treatments that could correct the angle of a tooth before it erupts rather than rely on orthodontic bands or braces to realign the tooth later in life.

“At the moment we’re conducting an In Vitro study to look at dental follicular cells response to compressive and tensile forces and to see their potential role in bone remodeling.

“There is the possibility that, if that is the case, we could use a form of intraoral appliance or stress shielding implants that could redistribute stress on certain parts of the jaw, and trigger teeth to erupt at the right angle,” Dr Sarrafpour says.