With odds of a single session, motivational interviewing is a good bet.

I’ve long believed that a good first encounter (with subsequent continuity of care) is paramount in establishing a lasting and trusting relationship between patient and practitioner. But what if you only have one encounter? While this study is from Psychotherapy, we can certainly take the lessons learned and apply them to dentistry.

https://www.ncbi.nlm.nih.gov/pubmed/30667246