I used to work in dental research at an RG dental school and interviewed potential undergraduates. There was a group session where potential students were given a scenario or problem (e.g. discuss the arguments for and against water fluoridation) and one to one interviews.
interviews didn’t focus on technical dental knowledge and anatomy (which is taught as part of the course and ALevel students were not necessarily expected to have this knowledge ) but more about a wider evidence base concerning things like, evidence based practice, dental public health and prevention and the wider determinants of health, the NHS and private practice, motivations for choosing dentistry and the specific course/ uni. So if the course has e.g. a problem based learning element, or a community placement, what is appealing about this to your DC.
I was told to look for potential students who I would want chair side as a patient and who I thought had the motivation and staying power to complete the course and attend lectures and tutorials. Good stress management techniques and a balanced lifestyle were also valued as they don’t want people dropping out.
The scoring matrix for the group session was related to team work and contribution and the ability to debate and discuss wider issues pertinent to dentistry.
I suggest useful preparation would be around an awareness of the lack of availability of NHS dentistry in the community, childhood caries and the social issues that contribute to poor dental health, possible prevention strategies that are out there and the wider socio-political context in which dentistry operates, including post- Covid and the affect the pandemic had on services.
Caveat is that I left in 2021 so thing may have changed since.