Oceania Group chief executive Guy Eady said that immediately after Mrs Ross complained via email on February 28, an official investigation was launched.
"Oceania Group let Mrs Ross know that under no circumstances was it acceptable that her mother was given someone else's false teeth to wear. Our company takes such allegations extremely seriously and this necessitated the immediate investigation."
Mr Eady said it was made very clear to Mrs Ross that this was a marked deviation from the standards of care that the company expected of its staff and resthomes.
"Thankfully, this is an isolated case that we have moved swiftly to rectify," he said.
Mr Eady said the investigation found there were delays in notifying Mrs Tipler's family that her bottom false teeth had gone missing.
Relevant staff had been spoken to about the incident and the company would deliver further oral hygiene education to all Melrose staff, he said.
Mr Eady "apologised unreservedly" to Mrs Tipler and Mrs Ross for the distress caused and wished to reassure them appropriate steps had been taken to ensure the incident could not occur again.
Last night, Mrs Ross said she would accept Mr Eady's apology only if the resthome followed through with everything it had offered to do, including bringing in a dental technician to attend to her mother at no cost to her or her family.
"However, the matter hasn't been resolved completely yet as my mother still hasn't got any bottom teeth, and I want to know who has gone into her room and taken the bloody things.
"I hope they are not sitting in that drawer of all the other lost dentures or sitting in someone else's mouth.
"It's a shocking state of affairs. I'm going to be everyone's worst nightmare from now on to ensure the resthome gives my mother the level of care she richly deserves."