Thank you all for the really helpful answers, I must admit I am not sure if one will be required or not, I'm having a filling removed and replaced - there is an image of the tooth here
http://www.dentalfearcentral.org/fo...c-button-and-there-s-still-a-week-to-go/page4 I think it is quite a deep filling, the tooth is dead.
In answer to Carole's query
My main fear is the smell of it I notice it goes right under the nose. At the moment I hold my breath so as not to smell the latex gloves but if I've got that right under my nose I don't know what I would do in order to cope.
I've also read a number of posts from people with a similar history to mine in terms of the root cause of the dental phobia and they all mention having problems with the dam eg the post here
http://www.dentalfearcentral.org/fears/abuse-survivors/
I don't honestly know how I would react to it. Perhaps if the dentist where to do as SSOCEA helpfully suggests and let me try it before deciding to continue I would be a bit easier about it. Would that be possible do you think?