Jan 23

“A Filling I Just Had Done on a Back Tooth Hurts When I Chew…”

It feels like one new patient a month arrives to my office from elsewhere with this same complaint.  The symptoms and history of treatment are almost identical, as follows:

The patient was told they had a small and shallow cavity on the back tooth that had no symptoms prior to treatment.  The filling was performed and now the tooth hurts when biting on it.  After waiting a week or two they report back to the treating dentist and are told “the bite” was too high.  Adjustments are then performed to relieve symptoms.  Yet after waiting, sometimes longer than a month, the pain on the “shallow and small” filling when biting returns.

Another visit has the patient feeling silly and they are told all is fine and the filling is “too tiny” to have these symptoms, or told if symptoms worsen a root canal will need to be performed.  Unfortunately, many times both patient and dentist are confused, frustrated and bewildered.  X-rays will not demonstrate the problem and a thorough physical exam of the tooth, filling, and “bite” what dentists call occlusion will reveal the issue.

Very frequently teeth – even without fillings – fracture or split through the cusps. When a tooth is developing in a patient’s jaw, the cusps grow together or fuse, very much like dinner rolls being baked together.  These “fault” lines over decades of chewing can start to split or break.  I always like to use the analogy of a chip in a car windshield. You see that little chip for months, and then one day it just gets bigger and bigger and now it’s a crack.

With a tooth, careful, forceful and continuous displacement of, say, the tongue side of the back tooth towards the tongue will evoke the discomfort  The patient will look at me and say “yeah that’s the pain, whats going on?”

I will give them a hand mirror and demonstrate that only one portion of the tooth hurts, and only if it is pushed in the correct direction.

If the tooth is not fractured, other times the problem lies in the order of placement of the composite filling and adhesives.  Examining or applying pressure with a small instrument just to the filling will cause the discomfort, whereas biting on the tooth alone or taping the tooth does not evoke the pain.

The cause here is a “stressed composite filling”. What is occurring is the composite or bonded filling is shrinking when it hardens or sets up.

Some composites shrink more than others, and the bonded seal on the floor of the prepared tooth, which is closest to the nerve, is pulled out, leaving a void.  The patient really gets this because when I push down with the instrument the tooth hurts for a second but when I release the pressure, discomfort is felt again as the compressed void sucks back against the tooth.

To avoid this condition low shrinkage composite fillings should be used and/or the filling should be placed in increments or at least not on all the walls at the same time.

The paradox here is the smaller the filling the more likely this can occur.

Many properly placed fillings will demonstrate sensitivity to cold and biting for some time.  However, over a month points to a chronic issue which requires intervention.

Dr. John Dibling uses Bis Fill Aelite  composite which has a very low shrinkage and high wear resistance.  These are important characteristics for composite fillings on back teeth.  But really sequence and technique are more important than the materials themselves.

What’s in your mouth?