Much has been written about porcelain veneers and crowns: how to prep, impress, and bond them. However, little is written about what in fact is the most critical step in ensuring predictable exquisite results—the provisional restoration. When significant changes are made in tooth morphology or position it is essential that the provisional be used as a diagnostic tool. Many dentists espouse how rapidly the provisionals are made; yet when results are reviewed with a critical eye, there is often room for significant improvement. Too often, midlines are not precisely located, and incisal cants are evident. There is also a trend toward allowing bis-acryl resin to cure on the teeth and be retained without trimming. This runs contrary to everything this author has learned about keeping the gingiva free of inflammation, which is important to a smooth and predictable seating appointment.
The provisional diagnostic restoration should be a source of pride for the cosmetic dentist wishing to provide exquisite results. Provisionals are a communication tool which, when used properly, provide vital information to the laboratory, and remove all the guesswork about what the doctor desires.
Two case studies are discussed in this article. In each case the patient had cosmetic dentistry performed by another dentist. Both cases were functionally adequate, but cosmetic failures. In neither case was any significant attention given to the provisional restoration.
|Figures 1 and 2. This patient was unhappy with existing veneers on teeth Nos. 7 through 10 because of cosmetic problems and excessive thickness of the veneers.|
In case 1, teeth Nos. 7 through 10 had been veneered. The overall cosmetic result was severely compromised by a failure to recognize the need for crown lengthening to eliminate the square shape of the teeth. Furthermore, the overall cant of the incisal edges of the restorations was rotated counterclockwise approximately 10 degrees. The patient also complained of too much labial fullness. The teeth felt “thick” (Figures 1 and 2).
Because soft tissue modification, incisal position changes, and changes of thickness were necessary, the choice was made to fabricate the provisional directly in the mouth because the final result would be difficult to predict on models alone.
PREPARATION FOR SOFT TISSUE MODIFICATION
|Figures 3 and 4. Using a template the gingival tissue was reduced to “lengthen” the teeth.|
At the patient’s diagnostic appointment she was anesthetized and a periodontal probe was used to sound the bone. Because a 6-mm distance was found from the gingival margin to the alveolar crest, it was determined that a simple gingivectomy would not violate the biological width. A study model was taken and the proposed gingival reduction was outlined on it. A vacuform template was then fabricated and trimmed to the desired length. Using this template, the gingival tissue was reduced to lengthen the teeth as desired (Figures 3 and 4).
|Figure 5. Tooth preparations were accomplished.|
After the gingival reduction was completed, preparation was accomplished (Figure 5). After preparation of tooth No. 8 it was discovered that the existing veneers were in excess of 2 mm thick. A freehand composite veneer was fabricated for No. 8 prior to preparation of teeth Nos. 7 and 9. This would serve as a guide for fabrication of the other provisional restorations. Crown forms were used for teeth Nos. 7 and 10, with additional freehand veneers for teeth Nos. 5, 6, 9, 11, and 12.
|Figures 6 and 7. The provisional restorations achieve excellent aesthetics.|
|Figure 8. A putty index indicating the incisal edge position was fabricated on the lower model.||Figure 9. The upper working model is mounted using the putty index.|
|Figure 10. The final restorations are precisely fabricated to match the index, leaving nothing to chance.|
|Figures 11 and 12. The final restorations are predictably the same size and shape as the provisionals.|
Figures 6 and 7 show the results that can be achieved with excellent provisionalization. A study model was then taken and mounted on the articulator. At the laboratory a putty index indicating the incisal edge position was fabricated on the lower model (Figure 8). The upper working model was then mounted to this (Figure 9). The final restorations can then be precisely fabricated to match this index, leaving nothing to chance (Figure 10). The final restorations (Figures 11 and 12) are predictably the same desired size and shape as the provisionals.
|Figures 13 and 14. The incisal edge position and mesial-distal proportions of this patient’s maxillary anterior restorations were inappropriate.|
Case 2 is a simple case in that the contour of the teeth was relatively correct. However, the incisal edge position and the mesial-distal proportions of the teeth were inappropriate (Figures 13 and 14). The teeth did have a rather square shape to them, however, the patient’s low lip line made soft tissue modification unnecessary. Because the overall changes did not involve significant contour changes or soft tissue changes, a good result could more easily be achieved using indirect technique.
|Figure 15. Two vacuform stints were fabricated, one thinner and one thicker.||Figure 16. The thinner stint was placed in the patient’s mouth.|
A preoperative model was modified. Composite was used to make the changes so that duplication would not be necessary for fabrication of the stints. Two vacuform stints were then made (Figure 15), one made of 2.0 coping material and the other made of rigid, thick night guard material. This thicker stint was made directly over the model with the thinner stint in place. The thinner stint should be lightly sprayed with silicone spray prior to sucking the thicker material over it, for ease of separation. Luxatemp material (Zenith) was used in the thinner stint, and placed in the mouth (Figure 16). The thicker stint was then placed over the thinner stint and used as a press, which caused the excess material to be expelled, and provided an even more accurate temporary with less need for adjustments. If the margins are completely supragingival the material can be allowed to harden on the teeth and “shrink to fit.” If, however, as in this case we are replacing a previous prosthesis, the provisional must be trimmed so that proper gingival enclosures can be created for soft tissue health and ease of hygiene.
The patient was then sent home to live with the provisionals for at least 24 hours. This step is critical for taking cosmetics to the next level. In most cosmetic cases the change between the condition with which the patient presents and the well-made provisional is the “most dramatic” change that will occur. Practitioners and patients are often blinded by this change and willing to accept it as satisfactory. As practitioners we are often guilty of “not seeing the forest through the trees.”
Having the patient return after sleeping with the provisionals will be what separates your provisionals from the pack. Given a fresh look with rested eyes, modifications are necessary in almost every case, for the practitioner is adamant about doing his or her finest work. Midlines, which seemed fine on prep day, are discovered to be at an angle. Furthermore, the entire smile line will look different when the patient can smile normally as opposed to when anesthetized.
|Figure 17. A study model of the modified provisionals was mounted in an articulator.||Figure 18. The laboratory technician fabricates the final restorations using a putty incisal index.|
|Figures 19 and 20. The final restorations achieve predictable aesthetic results.|
After this appointment, a study model of the modified temporaries was made and mounted to the articulator (Figure 17). An incisal index was fabricated, and the lab could again fabricate the case knowing precisely what was desired (Figure 18). Cemented or bonded, the results were exactly what are expected as opposed to hoping for good results (Figures 19 and 20).
Provisional restorations can be and should be used as a diagnostic aid and communication tool by the doctor to the laboratory. Using them in this manner will ensure outstanding results.
When changes to soft tissue and contour are significant, the direct technique will often be the best and most efficient method. When changes are less significant the indirect technique will be the quicker and easier method. In any case, when changes are made the patient should be brought back after at least 24 hours to view and suggest modifications to the provisionals. Once this is done, indexing the incisial position on the lower model after mounting the study model to it will ensure that the result you desire will be the result you achieve. Taking the extra time to do this will provide more satisfaction to the highly artistic dentist.