Hi Dentistdiver
Contrary to popular belief, it is not voids within fillings that are implicated in barodontalgia. In experiments in which there were air pockets purposely left in restored teeth, the barodontalgia rate was no different.
In my experience, barodontalgias are associated with teeth with a compromised vitality. The tooth may be decayed and bacterial toxins have reached the pulp chamber (with no frank nerve exposure), fractured teeth, symptomatic teeth needing endodontic treatment, unsymptomatic teeth needing endodontic treatment, previously endondontically treated teeth in which there may be a void or short fill. I have also seen a case in which there was a recently placed alloy and the patient went diving a week after placement. Removal, sedative filling placement for several weeks followed by alloy replacement over a sedative base was successful.
In all seemingly "vital" cases, i.e., teeth presumed to have normal vitalilty, the most likely cause was an undiagnosed non-vital or partially vital pulp. Radiographs were negative and there was no reported sensitivity to hot, cold, pressure or percussion. Following a painful dive, the diver would go to their dentist and a root canal was necessary...for whatever reason. Even in the above mentioned case with the recently placed alloy, the tooth vitality was certainly compromised but would have been categorized as a "reversible" pulpitis.
Keep in mind that the most common cause of barodontalgia is not a tooth problem but the maxillary sinus referring pain to a tooth. I wouldn't surprise me if any number of old fillings have been removed from these patients because it was the only possiblity left to the dentist. The barodontalgia resolved because the barosinusitis had gone away AND the patient had a brand new filling to boot.
I am of the opinion that most barodontalgias occur in teeth in which the pulps have been compromised but are undetected. Air bubbles under a filling are not a problem unless the pulp already has a problem. I realize that this might not be the conventional wisdom but I have had the opportunity to treat or consult on a number of these. At no time was there mention of a bubble of gas under the filling.
For that matter, how many fillings have you removed in which you have visually determined that there is a void in the FILLING MASS? By the time you finish drilling on the old filling, there is nothing left to examine. There ARE voids that can occur under old alloys between the alloy and the floor of the preparation. These are usually the area that was occupied by an old cavity liner or base. The base gets wet and turns to "mud". Calcium hydroxide is one of the worst offenders. There will be a void here...there is usually an undetected area of decay in close proximity to the washed out base.
So, what to use. Either material can be used. Keep in mind that you cannot use any "sedative" material under composite. The eugenol in the sedative material specifically "poisions" the curing reaction of composite. The uncured composite will then be prone to leakage, recurrent decay, tooth discoloration will occur, AND a good chance of needing a root canal.
I also believe that bonded composite IS more likely to result in pulpal irritation than an amalgam placed over a good base. I realize that the "dental gods that be" don't say thatbut let's face it, part of the reason that composite is so "technique sensitive" is because it is very easy to create a sensitive tooth following the filling. It may be caused by moisture contamination, cavity prep contamination, germs in the tubules, and polymerization shrinkage...which may well be true...BUT all these same causes occur under alloys but there is usually no sensitivity in a properly based preparation. In cases when sensitivity to a new alloy does occur, a sedative filling and than alloy replacement usually works.
In composite filled teeth, if there is sensitivity, there is an increased risk of pulpal damage leading to root canal treatment.
IMHO, neither composite nor alloy are really indicated for teeth with really large preparations or visible fractures. A composite will shrink and stress the cusps and an alloy will expand...increasing the chance of a fracture.
If you do use a composite, there is a greater chance of trapping voids within the filling mass. I don't believe these will be of consequence. I would suggest that when using the composite, under rubber dam, first apply an appropriate (glass ionomer) base as needed, then a layer of flowable composite...and examine it for small bubbles...as a base layer, followed by the composite of your choice...added in layers. If you want to do a "total" etch technique, make sure to use the flowable composite as your liner. You might also want to use a self etching primer because the sensitivity is supposed to be lower.
If you use alloy, make sure to place a sedative base under deeper fillings or use a glass ionomer or resonomer type of fluoride liner (like GC lining cement). As a matter of technique, if you are treating a known scuba diver, always, always, always place a zinc oxide/eugenol base under the filling and even consider placing Temrex, IRM or SuperEBA cement as a base. Cavitec is fine under a shallow filling.
Man, I think I just rattled some of my old fillings loose typing so much!
Hope this helps post again if you need more info.
Regards,
Laurence Stein, DDS
