Bruce Lawrence Henries was 50 years older than the teenager he sexually assaulted in 2004.
He was driving her home from a dance class, where he had recruited her to serve as his assistant teacher, when he made a detour.
Henries took the girl to the house he shared with his elderly mother in Sydney's west, sexually assaulting her in a granny flat on the property.
In a panicked call to another dance teacher, Henries later asked them to inquire about whether the teenager was pregnant.
The sexual assault came after Henries indecently assaulted her on "many occasions," the court was told.
NSW District Court Judge David Arnott noted the "significant age gap" and reliance on his authority as an adult added to the seriousness of Henries' offending at a time when he was trusted with the girl's care.
"The offence was opportunistic, brazen and committed for sexual gratification," the judge said.
Henries was charged in June 2024 over the sexual and indecent assaults committed two decades earlier.
He denied it and questioned why she would "be going after me" 20 years later, but eventually pleaded guilty.
His "betrayal" of the teenager led to fear and shame overshadowing her love of dance, she told the court.
She underwent years of therapy, at her own cost, to manage the impact of his offending and has found it difficult to build and maintain close relationships.
The woman cannot be identified for legal reasons.
The 85-year-old Henries was sentenced on Friday to two years imprisonment, dating from when he entered custody in April.
His full sentence of three years and three months expires in July 2028.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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