Children lose their baby teeth as their adult teeth begin to emerge, though long-standing hypotheses about what triggers this growth have not been supported by clinical evidence. Researchers at the University of Sydney, however, have found that chewing and biting cause adult teeth to break through the gums, not an innate, unknown force.
The researchers developed a 3-D biomechanical model that shows the stress distribution in the jaw as it bites and chews. They used CT scan images of an 8-year-old’s mandible to design a 3-D model they then could use to examine the forces produced by the jaw in 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,” said Babak Sarrafpour, DDS, PhD. “We simulated both the back teeth and front teeth chewing, and we could assess the stress on the teeth, bone, and soft tissue.”
The researchers 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 outward.
“There were a number of hypotheses surrounding how adult teeth erupted. Perhaps it was from the root forming and pushing the tooth towards the 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,” said Sarrafpour.
“However, there were a number of studies that showed even if you disconnected the root and ligaments from the tooth, it would still erupt through the bone,” he continued. “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 caries the tooth to the mouth.”
The researchers believe this work could lead to further preventive 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 comprehensive and tensile forces and to see their potential role in bone remodeling,” said Sarrafpour. “There’s 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.”
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