We understand it can be frustrating when after getting your braces on, one of the brackets come loose. What causes this and how can it be avoided? There are at least three reasons why this happens:
1) The tooth
2) The placement technique
3) The patient (yes YOU!)
Ideal bond strength is most easily achieved between normal ivory colored enamel and a new orthodontic bracket. Although there are different orthodontic adhesives on the market, most have at least enough strength to hold a bracket on a normal tooth under regular conditions. When an orthodontic bracket is attached to any other surface besides normal enamel, there is a loss of bond strength that results in more frequent debonding. Examples of other surfaces include porcelain, hyper-calcified enamel (usually have a white, chalky appearance), hypo-calcified enamel (usually yellow or brown staining visible), or any number of dental restorations including tooth-colored composite and silver fillings. If a bracket must be attached to any of these surfaces, there will be a loss of bond strength. Another tooth-related cause of loose brackets is a bad bite. If a tooth in the opposing arch hits on a bracket when the patient bites down, or even if a cusp tip in the opposing arch is directly across from a bracket, it is more likely that bracket will become dislodged during chewing. After placing brackets in our office, we have our patients bite together to see if any are in occlusion. If they are, we place some temporary composite between the teeth to keep things from hitting.
The second variable that determines if a bracket stays on is the clinical technique used by the orthodontist. Modern bonding techniques require that teeth are clean, isolated, and dry before they are sealed. Although there are some cements (like glass ionomer) and some conditioning systems (like self-etching primer) that are more forgiving of contamination by water and saliva, both of these techniques produce bonds that are clinically weaker than regular etching and sealing. A second step in the procedure that can affect bond strength is how well the adhesive is forced into the mesh pad on the back of the bracket. If the cement is not thoroughly incorporated into the mesh, weaker bond strength will result. Finally, there is also a direct correlation between the amount of time that the doctor takes “fiddling” with a bracket before curing it and the strength of the bond. The more times the bracket is moved, the thinner and less uniform the cement on the back of it and therefore the weaker the resulting bond.
The patient is the third cause of bracket failure. Although all patients receive instructions about what they can and cannot eat with their braces on, changing eating habits is challenging. Hard and sticky foods must be avoided. This includes ice! Some patients forget that even some healthy foods (like raw carrots) are not good for their braces and must be avoided during treatment. Sports mouthguards are essential, but they can also dislodge brackets and should be reported to the orthodontist. Last but not least, any habit that involves foreign objects going into the mouth (like pens, fingernails, etc.) must be identified and stopped.
It is important that you check your braces every night when you brush to make sure that none of the brackets have come loose during the day. Although patients commonly tell me a bracket came off during brushing, in reality it was probably already loose but was merely discovered at that time. You can tell if a bracket is loose by gently pushing on it with your finger. If you notice that it moves but the tooth does not, it is probably no longer attached.