Muriel Macdonald, 49, the former head of a small school on Lewis, also had previous convictions for assaulting a police officer and drink-drinking, a disciplinary hearing of the General Teaching Council for Scotland (GTCS) heard yesterday.
The hearing, in Edinburgh, was told Mrs Macdonald had been convicted at Stornoway Sheriff Court of treating a child in a "manner likely to cause him unnecessary suffering or injury to health". The charge added that she "did wilfully and against medical advice remove a plaster cast from his left arm which had been applied by medical professionals".
The former teacher was placed on two years' probation following the court appearance in August last year.
Paul Marshall, the solicitor to the hearing, said Macdonald's breach of the law had called into question her fitness to be a teacher. Her behaviour could damage confidence in the profession and amounted to a failure to act as a role model, Mr Marshall added.
Macdonald did not appear at the hearing and she was not legally represented.
Mr Marshall said there was written mitigation from Macdonald, which made reference to alcohol, but he asked the committee not to place significance on any submission that drinking was a relevant factor. He said: "In short, this is an offence of causing suffering to a child. The committee is justified in viewing this in a serious light."
Mr Marshall said Macdonald had been convicted in 2008 of a breach of the peace and assaulting a police officer. He added that in March this year she had been convicted of drink-driving.
"This shows a worrying pattern of criminal behaviour over the last two years or so," he said.
Convener of the disciplinary sub-committee Freida Fraser said they considered a recent medical report from Broadbay Medical Practice, Stornoway.
The previous convictions "were not held to be of significance to its considerations", she said.
Ms Fraser said a reprimand had been considered but ruled that out because Macdonald had not shown any remorse or acceptance of responsibility for harming a child in her care.
She said the only appropriate decision was to direct that Macdonald be struck off the teaching register.
Macdonald's name will also be considered for inclusion on the list of adults banned from working with children.
Macdonald was at the centre of scandal in 2008 when it was alleged she had attacked her own son at a party.
At the time some parents expressed anger that Macdonald was allowed to keep her 50,000-a-year job as head of Bragar primary, which has just 26 pupils.
Under GTCS rules, Mrs Macdonald can appeal, but it is unlikely she would be successful.
Reciprocal rules mean she would be banned from working in any school in the UK.
A council spokesman for the Western Isles said the council did not comment on individual cases but confirmed Mrs Macdonald had been dismissed several weeks ago.