Restoration of molar teeth

[john da dentist]

Hi there

I am a final year student at Bristol Uni dental school. My question(s) is aimed at Larry Stein, the diving dentist, although i would welcome comments from other readers. I am not a diver either!

I am currently treating a patient whose work involves dives. He reports a previous dental history of amalgam restorations being lost, and gold inlay/onlays debonding. He is adamant that full gold crowns (FGC) are the diving panacea. He has well developed muscles of mastication (large head and neck!) which he reports is from biting down constantly on his regulator during a dive, although he does not have abnormal tooth surface loss.

I have just completed RCT of UL7 with GP; the access cavity was restored with GIC. The access cavity covers approximately 1/3-2/3 of the occlusal surface area. The marginal ridges are sound.

What is the recommended restorative procedure for my patient, given his PDH? Is it safe to assume that his molars will experience increased occlusal loads compared to 'normal', given his heavy bite? Is it prudent to delay the definitive restoration until is it clear that the RCT has been successful?

Additionally, the contralateral molar (UR7) has an occlusal cavity, which i prepared following enamel fissure biopsy. Caries was present. Its occlusal surface area is not more than 1/3 of the total, although the dital marginal ridge is just breached. The cavity is presently temporised with GIC. Again, what restoration would you recommend? My patient is determined that a FGC is the treatment of choice, but I am concerned about the destructiveness of this option.

I am currently sifting through the literature trying to find answers!

Looking forward to hearing from you.

With best wishes

John.

 

[Laurence Stein DDS]

Hi John,

You've posed several questions that have to be evaluated by any dentist devising an appropriate treatment plan.

I'm not sure that I totally agree with your diving patient. To have teeth capped that would normally be filled is probably overkill. There use would normally be indicated if there was no other way to restore the tooth.

While your patient reports breaking alloy fillings while diving, I doubt that the dive per se was the causitive factor. Filling age, occlusal loads, functional and para-function and muscular structure must certainly be considered first. If your patient is a bruxer, then I would be more likely to consider caps.

Caps have their own drawbacks. They sacrifice tooth structure, subject the tooth to more trauma during preparation and may increase the need for root canal therapy in the future.

A good rule of thumb is that if the filling or anticipated filling has a width greater than 1/3-1/2 the intercuspal distance in the ithmus between cusps, then a cast restoration should be considered.

Cerainly, if the patient wants the most durable restorations possible, then the use of gold inlays and onlays would be useful. The inlay is no more destructive than a filling preparation. An onlay is somewhat larger but less tooth is sacrificed than the full crown.

I would have no qualms placing inlays rather than simple fillings.

That being said, most teeth should be capped following root canal therapy. In addition to the cap, a core or post and core should probably be placed. This would be true for the tooth you treated. It doesn't sound like there is much left on the inside. Once you prepare the outside, what ever tooth structure is left will be thin and weak.

Remember, the tooth with the root canal should have no cotton or airspace left under the crown.

The UR7 sounds like a tooth that can be filled. My preference would be an alloy filling or a gold INLAY. IMHO, silver alloy is a better choice for a high occlusal load area...especially in a person with a strong bite. I don't feel that a bonded posterior composite filling is as strong and it certainly is not a s durable.

There is evidence that repeated hyperbaric cycling can weaken the cements tested in the following article:
From Dec. 1995 of Prosthetics
http://www.odop.it/dentistry/site/ISSUE95-01/ART-01-01/ART1-CORBAR.html

Unfortunately, there is little in the literature about dental restoration and diving.

I wish you luck. Feel free to contact me if you have more questions.

Laurence Stein, DDS
:doctor: