Are these correct sentences?

[anamica]

Robert called he has a dentist appointment today Nov. 02/07 for 11:00A. He therefore will be coming in late to the meeting.

[Clare James]

Better might be:

'Robert called to say he will be arriving late to the meeting as he has a dental appointment today for 11.00am."

But it depends on the context. This might be too formal or too informal - it depends who the message is for.