A miniature dental robot could one day prepare teeth for crowns automatically and reduce the number of appointments needed for treatment.
A routine dental check-up can reveal that decay has left a large cavity and the tooth needs a crown.
Treatment usually involves several follow-up appointments. During the first, the dentist removes the decay, fills the cavity and prepares the tooth before taking an impression and fitting a temporary crown.
The permanent crown is made from the impression and fitted at a later appointment.
Researchers at the University of Basel’s Department of Biomedical Engineering have developed a small robot that could speed up this process.
The prototype is about the size of a wine cork and measures 43 by 26 by 28 millimetres.
Its motors and control system are positioned outside the device and connected to it through flexible drive shafts, cables and tubes.
Yukiko Tomooka, first author of the research, said: “It is designed to be small enough to fit comfortably into an open mouth.”
The prototype, called MIR, short for Miniature Intraoral Robot, is designed to prepare teeth precisely according to a digital plan.
Under the proposed approach, a dentist would scan the patient’s mouth during the first appointment and plan exactly how the robot should remove the tooth material.
The permanent crown could then be ordered straight away rather than after a second appointment.
The scan would also be used to create a custom-fitted dental splint to which the robot would be attached. A dental splint fits over the teeth and would hold the device in place.
Tomooka said: “Even if the patient turns their head, the MIR moves with them.”
The researchers tested the device on tooth models made from synthetic resin and a ceramic material with a hardness similar to tooth enamel.
MIR prepares the tooth in two stages. A wide drill first removes material from the upper surface before a longer, thinner drill shapes the sides.
Tests found that its positional error was less than 0.2 millimetres, even though the prototype does not yet have sensors that can directly measure or correct its position.
The researchers expect to reduce the error further once sensors have been added.
They also measured the forces produced during drilling, which remained below five newtons.
This is roughly equal to the gravitational force exerted by a half-litre bottle of water.
The team is also examining the noise made by the system to assess whether it would be suitable for use in dental practices.
More work is needed before MIR can be used in dental practices.
The researchers next plan to add sensors and a camera so the system can monitor its position and the progress of treatment.
Georg Rauter, professor and research group leader, said: “Even after a power outage, MIR would know where it is and where it needs to continue based on the sensor data.”
The aim is to add these features without making the robot any larger.
Rauter’s team regularly works with practising doctors and dentists to develop robots for medical use.
The device was developed through an Innosuisse-funded project involving the University of Zurich’s Center for Dentistry, Basel-based Camlog Biotechnologies and the University of Bern.
