There was a time when having unpleasant mouth odour during fasting was considered a source of pride and a humbling experience. The one fasting knew that his foul smelling breath was more pleasing to his Lord than the best smelling perfume of this world.
The times have changed. Now people consider missing their fast in order not to offend their clients or colleagues with their mouth smells.
In the fallowing clip Mufti Akmal explain the permissibility of using toothpaste during fasting. His points are that toothpaste or mouth wash can be used during fasting for people who have to deal with public. While using toothpaste, one must ensure that toothpaste residue do not go down this throat and that one must feel that he/she is doing an undesirable act.
Such permission is not a blanket permissibility for everyone to start using toothpastes or mouthwash during the fasting period.
May Allah make it easier for us. Aameen.