Today’s challenge was a tooth #2 belonging to my former hygienist. An all-ceramic crown fractured in half and debonded. It had been endodontically treated before. The tooth was under-prepped occlusally and over-prepped and over-tapered axially, particularly on the distal. The existing prep had very little retention and resistance form…. really NONE. I couldn’t re-prep it as it was. I needed to recreate some of the lost tooth structure.
So, I roughened / freshened the axial walls by “dusting” it with a diamond bur and removed a millimeter or two of the core build-up on the occlusal. I couldn’t get a metal Tofflemire band to engage the tooth. There was nothing for it to “grab,” as the tooth was turned into a “teepee” by the previous dentist. The band would just slip off as it was tightened. Then I found some old crown core forms in the back closet. They were made by Pentron. But, they’ve been discontinued! Editing to add: I found a similar product from EDS. Scroll down this EDS webpage page to see the product. But, the webpage lacks a “BUY” button for the core forms. Give them a call to order it.
I etched and bonded with Scotchbond universal. I warmed up some Filtek Bulk composite in hot water and filled both the endo access in the tooth and the crown core-former. Then I “smashed” the composite-filled former over the tooth and used an explorer to remove the extruded excess. Then cured from all sides with a Valo curing light.
When I removed the core-former, I was left with a grossly-overbuilt core. But, at least now I could do what I wanted with it in terms of trying to recreate a prep with better axial parallelism.
I re-prepped the tooth for a new gold crown (instead of ceramic) for two reasons. First, it was opposing a gold crown (#31). Secondly, I could keep the prep more conservative. After prepping, I cured the build-up again with the Valo light.
Due to the angulation of the teeth, it was hard to visualize if I had enough occlusal reduction. So, I made a Blu-Mousse bite registration and used a caliper to indirectly measure and confirm adequate clearance.
After I was satisfied with the prep on #2, I used a fine diamond to smooth and square up the distal proximal and marginal ridge of #3. Yeah… that tooth needs a crown, too.
After prepping, we took a final Impregum impression (diode laser retraction) and then an alginate to help me make the temporary (since I didn’t have the original crown to make a pre-op impression. After the alginate impression was made, I took a #8 slow-speed round bur and carved out the alginate to make a negative of the temp crown. Then I used Luxatemp and seated it in the mouth. I had to use a bit of flowable to fill in some blanks and then high-speed flame diamond to free-hand carve it to look somewhat like a tooth.
I considered adding a retentive groove or two to the prep, but the fit of the temp restoration confirmed that I had decent retention and resistance form.
While the occlusal reduction appears excessive in the clinical photos and the final x-ray, I can tell you that (by measuring the bite registration), it was only 1 – 1.5 mm. Due to some likely super-eruption of #31, and a steep curve of Spee, there was very little room inter-occlusally.
And, that’s the end of today’s story!