A disgraced rural NSW dentist who used hypnosis to sexually abuse patients has begun a prison sentence of at least eight years.
Werner Otto Schwarz, now 82, was last year found guilty of 17 sex offences against four boys aged under 16 years in the 1980s.
He faced a sentencing hearing in the NSW District Court on Friday, where Judge Helen Syme described the abuse as "horrific and systematic".
The victims, the youngest of which was nine, underwent hypnosis under the belief it would be beneficial and, in one case, ease a fear of medical care.
Schwarz will be 90 when he's available for parole in October 2025.
© AAP 2018