The actor had only just returned to the show, after missing his week three performance due to an illness.
"I had a little bit of a turn, a little bit of an episode with vertigo," he said during an appearance on companion programme Strictly: It Takes Two.
"But it was all OK, I made myself right again with the help of some good people at the hospital," he added.
Dennis's return, in week four of the show on Saturday, saw him and Buswell secure their highest score of the series - performing a Charleston to the song Dance Monkey by Australian musician Tones and I.
Strictly judge Shirley Ballas said Dennis had come "back with a bang", and that he had pushed his limits with a difficult routine.
The pair are scheduled to be interviewed on Strictly: It Takes Two on Wednesday.
Dennis is best known for playing Paul Robinson in Neighbours, the longest-running character in Australian television history.
Following his first appearance in 1985, he went on to feature in 6,000 episodes across four decades.
His partner Buswell made history this Strictly series - becoming the first professional dancer to compete on the show while pregnant.
"I'm still doing everything I did before," she said ahead of the beginning of the series.
Speaking on her podcast Winning Isn't Everything, she added: "Obviously with lifts there's going to be a bit more caution. But my doctor has said everything is normal."