That Didn’t Work Out So Well

fig-01 fig-02 fig-03 fig-04 fig-05 fig-06 fig-07 fig-08 fig-09 fig-10 fig-11 fig-12 fig-13 fig-14 fig-15 fig-16 fig-17 fig-18

By: Rhys Spoor, DDS, FAGD

The original chief complaint of this pleasant patient was that she had been chipping her front teeth and wanted to slow the chipping and get more volume to her teeth as they appeared short to her. At her initial presentation, she had a porcelain fused to metal crown on tooth #3 and a DO composite on tooth #15. The remaining teeth were unrestored.

When she presented for a consultation in our practice, she had recently seated full coverage lithium disilicate crowns and missing provisional restorations for veneers on #7- #10. The missing provisionals had been replaced several times and kept fracturing, usually within hours of being replaced (Figs. 01, 02, 03, 04 and 05).

Patient and Dentist Frustrated
Needless to say, this patient was frustrated, as I’m sure was the dentist. She just wanted to fix a couple of chipped teeth and now she found herself in a position where she felt like she had made a big mistake and had lost not only trust in the first dentist, but trust in dentistry as a whole.

I discussed with her why the provisional restorations kept being pushed off. The functional envelope her teeth were traveling through did not match the shape of the teeth that had been fabricated and were being fabricated. She thanked me for my time and opinion, and I didn’t hear from her for three months.

What Patient Was Told Wasn’t the Case
When the patient returned, she had the final restorations on #7-#10 seated about two weeks prior. The veneer on #7 was missing and #8 was fractured with what appeared to be delaminations between the cement and the restorations (Figs. 06, 07 and 08). The treating dentist had told her he thought once he had placed the final restorations in the final cement the breakage problem would be eliminated. Unfortunately, that was not the case.

Breakage Was Inevitable
We scheduled her to come in for removal of the maxillary restorations and new provisionals about a week later. I also let her know that unless we changed the underlying occlusal cause and decreased the excessive force on the final restorations, further breakage was inevitable. When she returned the following week, tooth #9 had also fractured (Fig 09).

Rationale Was to Build Cuspid Rise Back Into Final Restorations
We removed and reprepped #7-#10 to the original design as there was no advantage to removing any more of the natural tooth structure. We also added very conservative veneer preparations on #6 and #11. The rationale was to build cuspid rise back into the final restorations (Fig. 10).

Risk of Perforation
The mandibular anterior restorations were aggressively reduced facially, just short of perforating the restorative material. The patient was apprised of the risk of perforation and possibly needing to replace some or all of the restorations if that were to occur. Fortunately, there was still enough thickness to maintain the restorations and not replace them (Figs. 11 and 12). The rationale here was to increase the amount of overjet, along with the redesigned cuspid rise, and reduce the lateral forces during parafunction on the incisal edges of the maxillary incisors.

5 Weeks With No Chipping or Breakage
A final impression was taken, along with a centric bite registration and a stick bite, to reference the horizontal plane of occlusion. Shades were selected and photographs sent to the laboratory. A directly made, self-curing bisacryl composite provisional material was shaped and tinted with composite tints (Figs. 13, 14 and 15). This important step was used to determine that forces generated during mastication and parafunction had been altered enough to not fracture the provisional material. The patient was in the provisionals for five weeks with no chipping or breakage.

Renewed Confidence
The final lithium disilicate restorations were seated routinely with a resin cement. Both the patient and I had renewed confidence these would be successful as the provisionals were intact after the five-week trial. The final restorations met the patient’s initial expectations of strengthening the incisal edges of the maxillary anterior teeth and adding a slight amount of length (Figs. 16, 17 and 18). She was also very pleased with the aesthetics.

The key learning issues with this case were:

  • Excessive incisal edge wear is a history of the occlusal forces and unless something is done to change the environment, that same pattern will be recreated.
  • The mandibular incisors are relatively small and preparing unrestored teeth for full coverage crowns leaves greatly compromised teeth. A more conservative veneer would have been a better choice and would have worked well with a resin cement. The final facial contour usually cannot be any fuller than the original facial contour.
  • Use the cuspids to help protect the incisors in parafunction.
  • Clearly explain the benefits and risks of treatment or no treatment. Patients deserve and are required to be informed in terms they can understand.

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