“Why do dentists drill before filling?”
I am a 22 year old female. I want to know why do dentists drill before filling?
13 Answers
DentistDentist
Most cavities undermine the enamel and it is not possible to reach the decay without drilling through the enamel.

Dr. Champaka Nagaraju
Dentist
To remove the decayed rotten tooth structure, to remove the caries and bacteria , and also provide space and form for the filling to be retentive.
Good question. Personally, I like to apply silver diamine fluoride to all decayed areas first. This arrests and reverses decay...sometimes no drill or fill is needed! But conventional practice is to remove the tooth destroyed by the decay process down to sound tooth structure, then, fill it back to normal contours for form and function.
A dentist will typically drill prior to placing a filling or repairing a tooth to remove all the infected tooth structure. Dental decay or caries is an infectious invasive disease that destroys tooth structure. When it first effects the tooth structure it weakens it, then as the bacteria progress they invade the tooth structure living in the weakened area. From there the invasion continues and the damage deepens and broadens. The dentists goal is to remove all the infected tooth structure to eliminate the destruction so not only does he/she need to fill the damaged portion but remove the infected portion so the damage does not progress.
In almost every situation it is to remove decayed tooth structure. A filling should not be placed over decay in the tooth, otherwise a serious infection will occur.
The drilling is done to remove active decay. If that decay is left it will continue to destroy healthy tooth structure.
To remove the decayed and broken tooth structure. Imagine a wall that is termite infested. You have to remove the infestation and degraded structures prior to rebuilding the wall. Same for the tooth.
To remove destructed tooth structure, the fillings have to go on a healthy, sound tooth structure. Think about it: you can't build a house in a muddy land.
Filling is removing decayed tooth structure and fill with clean material. Drilling is a must do procedure and have to do right. If do not remove cavity properly, "secondary cavity" can develop under the filling.