Potential Serious Complications When Esthetic Restorative Procedures Create or Fail to Correct Malocclusion: A Case Report

Richard Liu, DMD, MMSc

As with any profession, dentistry continues to evolve based on ongoing research, which allows dentists to provide what the patients (“customers”) demand. What is important is that dentists continually balance the application of modern techniques to meet patients’ changing demands while also keeping an eye firmly focused on all of the acquired knowledge about basic function.

In the 1960s, research taught dentists that occlusal factors are important in restoring patients’ dentitions. After some clinicians proposed a relationship between the length of the anterior teeth and the phonetics of speech, dentists also began to set up anterior teeth position in dentures with this principle in mind. In the 1970s, periodontal therapy and the widespread use of fluoride emerged, and dentists began to encourage and allow patients to retain their own teeth long term. In the 1980s, research brought newer composite restorative materials and enamel adhesive agents, which allowed the esthetic restoration of missing portions of teeth in the anterior region. Since the 1990s, the ability to restore teeth both functionally and esthetically has boomed. And, bolstered by the media, dentists now encourage patients to demand teeth that look better than their natural dentitions ever did.

Unfortunately, in the determination to satisfy patient demand for perfect smiles, many clinicians may have begun to overlook some important basic principles of good function, including proper occlusion. This has become evident in the author’s practice as well as the practices of many prosthodontic colleagues, who are now seeing a considerable number of patients with porcelain veneer restorations that have fractured or otherwise failed because of occlusion problems that were either not corrected initially or that were actually created by veneer application.

For instance, dentists may put too much faith in the most modern restorative materials, stretching them beyond their proper capacity for use. Some may mistakenly believe that because the latest restorative materials are better and more forgiving than in the past, basic clinical principles, such as the first principle of occlusion, are outdated and no longer need to be followed.

Poor preparation technique can be a major culprit in such veneer problems. Early on, some clinicians advocated bonding porcelain veneer restorations without tooth preparation, but some degree of tooth reduction—although not an excessive amount—is now known to result in better outcomes both esthetically and functionally.^1-4 Ideally, the enamel reduction depth should allow the veneer material to be in confluence with the natural contours of each tooth being treated. “Overbulking” with veneers may create problems both esthetically and functionally.

The following case, which involved a multiple-unit porcelain veneer restoration that created an excessively open vertical dimension in the anterior dentition, illustrates the complications that can occur when proper occlusion as part of veneer application is overlooked. Guidance is offered on how to address resulting complications as well as how to prevent them from occurring in the first place.

CLINICAL CASE

A 35-year-old woman presented for prosthetic consultation and emergency treatment of continuous extreme pain, muscle spasms, and thermal sensitivity in her maxillary and mandibular anterior area. She reported that the acute pain began immediately after the application of porcelain laminate restorations, which had been applied to all of the teeth in that area (teeth Nos. 5 through 12 and 21 through 28). She had no symptoms in these teeth before the restorative procedures, although she reported some initial moderate pain and thermal sensitivity in the area during the provisional stage.

According to the patient, the veneer treatment had been undertaken after she visited her family dentist for an orthodontic consultation because she was interested in improving the esthetics of some long-standing misaligned anterior teeth. Sixteen units of veneers were recommended instead of orthodontic treatment to address the patient’s chief complaint and to improve the shade and alignment of her teeth quickly and concurrently.

When the acute pain and sensitivity began after the veneers were applied, the patient returned to her original dentist, who was unable to determine what went wrong and provided no corrective treatment. After several attempts to have him address the problem, she sought specialist assistance on her own 6 weeks after application of the veneers.

At her initial consultation with our office, the patient was in continuous intense pain and could not tolerate even the cool air flow from a ceiling fan, although it was hot summer weather. When she was asked to close her mouth, it was clear that only her anterior teeth were making contact between teeth Nos. 22 through 27 in the upper arch. The unveneered teeth in the posterior area made no contact whatsoever. This likely contributed to the temperature hypersensitivity, muscle spasm, and pulpal trauma she experienced.

Ultimately, veneer debonding may have occurred. Because this patient was restored with bulky anterior veneer restorations that left uneven occlusal contacts anteriorly and posteriorly, the anterior veneers were forced to endure excessive stress, which could have created further fatigue to the cement bonds. When veneer debonds, temperature sensitivity can ensue and leakage can also result in veneer discoloration as was seen in this case.

Initial Corrective Treatment

Limited occlusal equilibration was performed during the initial consultation to provide more even occlusal contact points and to diminish the patient’s discomfort (Figure 1). When the patient returned a week later, she reported that her bite felt better and more even. Over the next several appointments, more aggressive occlusal adjustments were performed to establish even more stable occlusal contacts (Figure 2; Figure 3; Figure 4; Figure 5). Unfortunately, the thermal sensitivity did not dissipate.

At this point, the patient was referred to an endodontist. After the endodontic examination, root canal therapy was suggested and eventually undertaken in all of the veneered teeth, as described in a separate publication.⁵ The result was a dramatic improvement in the patient’s symptoms. Once her discomfort completely subsided, a treatment plan was formulated for more definitive treatment.

Reparative Restorative Treatment

Upper and lower alginate impressions were taken. The upper cast was then mounted using a face bow with a SAM semi-adjustable articulator. A centric occlusion record was obtained by using the bilateral mandible manipulation technique. The next step was to determine the vertical dimension of occlusion for this patient. First, it is important to determine whether the current vertical dimension is appropriate, reduced, or exaggerated. As mentioned, the patient started with even anterior and posterior teeth in contact in maximum intercuspation and centric occlusion. After the veneer application, her vertical dimension of occlusion was clearly exaggerated by the restorations. In this situation, the first step would be to occlusally reduce the veneer restorations to re-establish proper contacts between the posterior teeth. Once that is accomplished, the next step was to determine the appropriate length of the upper anterior teeth in relation to the lower teeth and lip. To help guide this, the patient was asked to enunciate the “E,” “S,” “V,” and “F” sounds.

A full diagnostic wax-up was performed on the mounted study cast (Figure 6; Figure 7; Figure 8). The measurements made with the patient enunciating sounds were used to determine the incisal edge positions of teeth Nos. 8 and 9. The width of the teeth in the anterior region was evaluated using the rule of golden proportion. The axial inclination of the maxillary teeth was evaluated and the posterior occlusal plane was evaluated. The diagnostic wax-up on the lower teeth was designed to be in an acceptable overjet relationship with the upper diagnostic wax-up. Once the patient approved these wax-ups, the models were duplicated for use in fabricating a heat-cured acrylic temporary bridge.

During the provisional phase, the patient received local anesthesia via 2% lidocaine with epinephrine 1:100,000. All of the veneers were removed at this point (Figure 9), and post spaces were created using a Gates Glidden drill. The posts were cemented with RelyX™ Unicem (3M ESPE, St. Paul, MN) resin cement.

The provisional restoration was then relined and the occlusal contacts were finalized to achieve even, bilateral occlusal contact points in centric occlusion. Canine guidance ensured excursive movement of the anterior teeth to disocclude the patient’s posterior teeth. For the final impression phase, the patient was anesthesized again with 2% lidocaine before the temporary restorations were removed. Size #00 cords were placed at the bottom of the sulcus, followed by #0 cords. Both types of cords were presoaked with Hemodent™ (Premier Dental, Plymouth Meeting, PA) solution before placement. The finished lines of the tooth preparations were finalized at this point. Impregum™ Soft (3M ESPE) heavy body with Permadyne™ (3M ESPE) materials were used for the final impression. The cords were subsequently removed, and the sulcus areas were irrigated with 0.12% chlorhexidine solution.

Before the final impression stage, it is important to determine whether the patient is comfortable with the provisional restorations and to make corrections as needed at this point in the treatment phase. The provisional restorations in the patient’s mouth become the blueprint for the final restoration, as long as the patient confirms that they are comfortable in terms of chewing, speaking, and hypersensitivity.

Alginate impressions of the upper and lower provisionals were taken and face bow records made with the upper provisional restorations to relate the upper cast to the articulator. The purpose of the face bow is to relate the upper cast to the same axis position on the articulator as the condyle axis on the patient. The lower provisional restoration cast was hand-articulated to the face-bow?mounted upper provisional cast. The condylar component was present at 30° on the SAM articulator, and the locking mechanism was loosened to make a custom incisal guide table. The incisal pin on the articulator was first raised by 1 mm to provide sufficient thickness of the self-polymerized resin (GC Pattern Resin, GC America, Inc, Alsip, IL). This material is applied to the incisal guide block whereupon the articulator is closed. The incisal pin should penetrate into the resin and all functional movements are then carried out with tooth contact until polymerization is complete. This set up the envelope of functional movement for this particular patient, guided by the existing provisional restorations that she had already “put to the test” and with which she felt comfortable.

This custom incisal guide table was then used to fabricate final crowns that would be the same length and provide the same occlusal contact points as the provisional restorations. Three sets of occlusal bite records were made. The first set included the upper prepared teeth against the lower provisional restoration. The second set included the lower prepared teeth against the upper provisional restoration. The third set included the upper prepared teeth against the lower prepared teeth. This was done to verify that die models of both the upper and lower prepared teeth are mounted correctly on the articulator. Because the patient underwent root canal therapy in the previously veneered teeth, it was necessary to provide full-coverage restorations for these teeth. A skilled technician can apply porcelain-fused-to-metal crowns with porcelain butt joints, which hide the metal margins. For the ultimate esthetic result—incorporating optimal translucency and light reflection in porcelain—the material of choice is all-ceramic crowns. Of the various kinds of these types of crowns, the zirconia coping with porcelain layering variety offers both good strength and esthetics (Table 1). For this particular patient, Procera® (Nobel Biocare, Yorba Linda, CA) crowns were used with excellent results (Figure 10; Figure 11; Figure 12; Figure 13; Figure 14).

DISCUSSION

As this case report illustrates, overlooking the basic principle of ensuring proper occlusion when performing restorative or esthetic dental treatment can be extremely frustrating to both the patient and the dentist when complications occur. This concern is becoming increasingly recognized among prosthodontic specialists who are being called on to address such complications, which might have been prevented had the original dentists better balanced both esthetic and functional priorities.

In a June 2004 editorial in the Journal of Prosthodontics,⁶ editor-in-chief David A. Felton, DMD, raised a red flag about the public’s growing demand for extreme makeover miracle results, the resulting boom in quick-hit esthetic training programs for dentists, and the use of porcelain veneers for patients who might be better treated with other options. “I am saddened by what may have become the ‘standard of care’ for dental treatment in this country,” Felton wrote. In particular, he noted a troubling number of cases published in the dental literature with photographs depicting “teeth in such malocclusion and malalignment that they scream for orthodontic consultation and treatment.”

In an April 2005 article in the Journal of the American Dental Association,⁷ Gordon J. Christensen, DDS, PhD, suggested that “Observation of occlusion, providing patient education about occlusion, and treatment of occlusal conditions sadly are neglected in the profession....I encourage practitioners needing education in occlusion to seek it.” His editorial was followed by a flurry of letters to the editor from practitioners who added their own observations on the subject.

The bottom line is that “smile lifts” always require both a functional and esthetic perspective.⁸ And for porcelain veneers, occlusion and other basic factors contribute directly to their long-term clinical outcome.⁹ The reality is that functional principles can limit potential esthetic outcomes. Patients who often eagerly present themselves with extreme makeover dreams should be thoroughly educated about this basic fact. Esthetics and self-esteem are important, but clearly not at the expense of function or comfort.

References

1. Garber DA. Rational tooth preparation for porcelain laminate veneers. Compend Contin Educ Dent. 1991;12(5):316,318,320 passim.

2. Friedman MJ. Porcelain veneer restorations: A clinician’s opinion about a disturbing trend. J Esthet Restor Dent. 2001;13(5):318-327.

3. Christensen GJ. Facing the challenges of ceramic veneers. J Am Dent Assoc. 2006;137(5):661-664.

4. Swift Jr EF, Friedman MJ. Critical appraisal: Porcelain veneer outcomes, part I. J Esthet Restor Dent. 2006;18(1):54-57.

5. Nasseh AA. Endodontic complications of esthetic restorative procedures. Inside Dentistry. 2006;2(4):72-75.

6. Felton DA. Do no harm. J Prosthodont. 2004;13(2):71-72.

7. Christensen GJ. The major part of dentistry you may neglecting. J Am Dent Assoc. 2005;136(5):497-499.

8. Bloom DR, Padayachy JN. Smile lifts: A functional and aesthetic perspective. Br Dent J. 2006;200(4):199-203.

9. Peumans M, de Munck J, Fieuws S, et al. A prospective ten-year clinical trial of porcelain veneers. J Adhes Dent. 2004;6(1): 65-76.


Figure 1 After initial occlusal adjustments, posterior occlusion was reestablished.		Figure 2 After additional occlusal adjustments, proper contacts with lateral excursive movement on the left side were established.


Figure 3 After additional occlusal adjustments, proper contacts with lateral excursive movement on the right side were established.		Figure 4 The patient's posterior teeth are again in contact after occlusal adjustments.


Figure 5 View of the mandibular veneers after occlusal adjustments to obtain posterior teeth contacts.		Figure 6 Frontal view of the diagnostic wax-up.


Figure 7 Wax-up of the mandibular teeth.		Figure 8 Wax-up of the maxillary teeth.


Figure 9 After the maxillary veneers were removed, profuse staining was seen as a result of leakage.		Figure 10 Mandibular crowns seated on the die model before insertion.


Figure 11 Maxillary crowns seated on the die model before insertion.		Figure 12 Frontal view of the crowns.


Figure 13 Right lateral view of the crowns.		Figure 14 Left lateral view of the crowns.


Table 1

About the Author
Richard Liu, DMD, MMSc Assistant Professor Department of Prosthetic Dentistry School of Dental Medicine Tufts University Boston, Massachusetts Clinical Instructor Department of Restorative Dentistry Division of Postgraduate Prosthetic Dentistry School of Dental Medicine Harvard University Boston, Massachusetts