Written by Victor A. Martel, DMD Friday, 31 December 2004 19:00
With the increasing number of smile makeover cases presenting themselves to dental practices in recent years, increased attention is being paid in the literature to the need for thoroughly and properly addressing a patient’s occlusal relationship in order to ensure the long-term stability and successful function of his or her restorative treatments.1,2 Specifically, some authors contend that too much attention is placed on the value of the immediate aesthetic outcome, while too little is given during the restorative process to condular position and bite relationships.3,4 This author contends that synthesizing both requirements through thoughtful treatment planning and material selection can yield long-term prosthetic success and aesthetic satisfaction for the patient.
In this regard, clinicians should resign themselves to the fact that the diagnostic phase of treatment is imperative to clinical success. Therefore, they should resolve to incorporate the protocol that can only enhance the outcomes of their proposed treatments. When it becomes apparent that a patient’s condition warrants more than a mere direct restoration to rectify a carious situation or a new full-coverage crown to replace a restoration that is now fractured, the patient must be advised of the need for a more thorough examination in order to evaluate aesthetics, occlusion, normal function, and potentially parafunctional habits.5
Such a comprehensive diagnostic evaluation should include a review of pertinent medical records, study models mounted in centric relation (CR), a face bow, and facial and profile photographs.3,5 For the CR, in particular, it is advocated that 3 separate CR bites be recorded using bimanual manipulation.3,5,6 When these diagnostic components are reviewed collectively—and when the patient’s expectations for treatment are openly and realistically discussed—only then can a treatment plan be developed that accounts for and anticipates improvements in the patient’s dental configuration, maintains or re-establishes symmetry of the patient’s smile, and harmoniously stabilizes the patient’s oral environment.3,5,7,8
The logical subsequent step in this process is the identification of the most suitable restorative materials for the given case. Direct and indirect composite restorations, vital tooth whitening, all-ceramic veneers and full-coverage crown restor-ations, and porcelain-fused-to-metal (PFM) fixed partial dentures are all available. These are also among the many scientifically proven treatment mod-alities that clinicians may choose to use exclusively or in combination, depending on the specific patient’s condition.
Dictating material selection, however, is the collective conclusion of the diagnostic phase of treatment. Therefore, given the multitude of considerations facing clinicians when comprehensive cases are presented, it behooves them to understand the principles of occlusion, the diagnostic steps necessary to evaluate the patient’s condition thoroughly, and how to interpret those findings into a treatment plan that incorporates materials and restorations indicated for the individual patient.
This article presents a comprehensive case in which a male patient was restored to a proper occlusal relationship through a treatment plan involving the placement of all-ceramic veneers, metal-free full-coverage crowns, and PFM fixed partial dentures.
|Figure 1. Preoperative view of the patient in full smile.||Figure 2. Preoperative view of the patient’s smile at rest.|
|Figure 3. Preoperative right profile view of the patient’s condition.||Figure 4. Preoperative left profile view of the patient’s condition.|
A 45-year-old male patient presented with an uncemented provisional restoration on tooth No. 7 (Figure 1). Upon clinical examination, the provisional was found to be very thin, with no chance of retention as a result of the severity of the patient’s occlusal problems (Figures 2 to 4). At this time, the importance of a full, comprehensive examination was explained to the patient, including a full occlusal analysis.3 The patient agreed to such examination and was reappointed. Previously, the patient’s motivation for seeking dental treatment was to address immediate restorative needs related to obvious aesthetics or pain issues.
|Figure 5. Preoperative view of the patient’s centric occlusion bite.|
During the comprehensive examination, the patient underwent a complete series of digital radiographs (Dexis), complete periodontic probings, a complete history, and a TMJ examination including Doppler Auscultation, centric load test, muscle palpation, initial point of contact, and a CR/centric occlusion slide measurement (Figure 5). Full-arch impressions were taken as well as a face bow transfer and CR bite registration using bimanual manipulation.3,5 The final goal of performing these diagnostic steps was ultimately to ensure a treatment plan that would restore the patient to satisfactory aesthetics and stable function while managing the physical stress on the masticatory system.4
This examination revealed that the patient had multiple fractured teeth; teeth Nos. 30 and 19 were missing; there was advanced wear of the mandibular anterior dentition; and failing crowns were present on teeth Nos. 7 through 10 and No. 14. Periodontal probings were within normal limits. The TMJ diagnosis was Piper class 3B on both the right and left, with no muscle pain on palpation. Due to this patient’s Piper classification, his treatment position would be an adaptive centric position instead of true centric relation. The patient’s history did not include headaches, and his range of motion was within normal limits.
The treatment plan was initiated by setting up the mandi-bular plane of occlusion and waxing up the mandibular teeth to proper length and shape within the arch. Occlusal analysis and model equilibration revealed the need to open the patient’s bite 1 mm in the posterior to allow for prosthetic convenience.
Based on the diagnostic wax-up of the mandibular arch, it was concluded that this could be accomplished by placing fixed partial dentures on teeth Nos. 18 to 20 and Nos. 29 to 31 that would be fabricated from porcelain-fused-to-high-noble metal. Due to the 10:1 increase in bite force in the posterior region, these areas require stronger restorations, and PFMs were the ideal choice to eliminate the possibility of fractures.
The premolar area—specif-ically teeth Nos. 21 and 28—would be restored with metal-free full-coverage crown restor-ations as a result of the de-crease in bite strength presented in this more anterior area. These restorations would provide enhanced aesthetics compared to porcelain-fused-to-gold restorations.
Teeth Nos. 22 through 27 were planned for all-ceramic veneer restorations. This area presents a low-to-minimal bite force, and metal-free veneers were considered by the clinician to be the best aesthetic restoration for this area and this particular patient.
The same guiding principle was used in treatment planning the maxillary arch for this patient. Teeth Nos. 2, 3, 14, and 15 would be re-stored with full-coverage crown restorations fabricated with porcelain-fused-to-high-noble metals, again to account for the 10:1 bite force increase from the second molar back to the first molar area. Teeth Nos. 4 through 13 were planned for metal-free full-coverage crowns (as opposed to veneers) to enable control of the lingual contours of maxillary dentition, to allow for proper centric stop contacts, to create lateral excursions that would be in harmony with the envelope of function, and to establish immediate disclusion of the posterior teeth in lateral excursions.
In this case, it was important to integrate the restorative materials selected to ensure a uniform, aesthetic appearance of the patient’s smile while still providing the adequate strength necessary to support the specific indication. For the maxillary crown restorations, a metal-free, all-ceramic restorative material (IPS Empress II/Eris, Ivoclar Vivadent) was selected based on the high-strength lithium disilicate framework it provides for clinical reliability.9,10 Indicated for anterior and posterior crowns, the IPS Empress II/Eris material en-ables the creation of restor-ations that demonstrate true-to-nature opalescence, natural translucency, and brightness for lifelike aesthetics.11 Additionally, restorations fabricated with this material could be conventionally cemented or adhesively placed.
For the fixed partial dentures and PFM crowns, a coordinated system of fluorapatite glass ceramic that demonstrates low wear against opposing enamel12 and specifically designed alloys was used (IPS d.SIGN, Ivoclar Vivadent). Unlike typical feldspathic porcelains, IPS d.SIGN comes closer to mimicking all of the properties of natural teeth.
For the veneers, the original leucite-reinforced, pressed-ceramic material (IPS Empress, Ivoclar Vivadent) was prescribed. Because this material is integrated with the other porcelains prescribed for this patient, it would facilitate aesthetic uniformity while providing the clinical performance,13-17 exceptional wear compatibility,17,18 and excellent translucency and aesthetics13,15 necessary for this case.
Due to the fact that the entire aesthetic zone of this patient’s smile was being restored, shade selection was based on subjective criteria, including skin tone, eye color, hair color, and the patient’s desired results. For example, patients with a lighter complexion and hair and eye color can accommodate restorations with lighter colors and still present with a natural appearance.
However, it is important to note that temporization color also plays a key role in determining final shade selection, since this enables patients to preview the color of their final restorations in a temporary phase and allows them to decide if it’s the proper shade for them. If patients are going from a fairly dark color to a fairly light color, the appearance of their teeth will be somewhat shocking no matter what they do. In this case, the patient was given a week to adjust to his new shade.
PREPARATION AND IMPRESSION PROTOCOL
The preparation design for the anterior, full-coverage crown restorations included full, rounded shoulder preparations with 1 mm to 1.5 mm reduction and 2 mm reduction on the incisal edge.
Full-arch final impressions (Aquasil LV, DENTSPLY) were taken utilizing cord packing and electrosurge when needed.
|Figure 6. View of the diagnostic wax-up on the model.|
Provisional restorations were fabricated from a siltex matrix created from the full contour diagnostic wax-up (Figure 6). Luxatemp shade A1 provisional material (Zenith) was used.
In creating the provisional restorations, time and attention were given to establishing an ideal occlusion, including equilibrating from centric relation to centric occlusion and ensuring that there were no posterior prematurities in lateral excursions. In this case, the patient was allowed to wear the provisional restorations for an extended time of 4 to 6 weeks to ensure no loosening or chipping of the temporaries, of which there was none.
In this case, the patient was a severe grinder. The main reasons people are severe grinders is because there is an imbalance in their bite (ie, a prematurity) or because they’re a delta bruxer (ie, genetic makeup). Therefore, it was necessary to observe the patient during the 4- to 6-week provisional phase of treatment to ensure proper establishment of a balanced bite and also determine if the grinding was due to the previous imbalance or genetics. If the grinding persisted, it would indicate that the porcelain on the final restor-ations might be at risk of fracturing and thus that a night guard was needed. However, at the point of balancing his bite through provisionalization, the patient’s grinding stopped, so the proposed final restorations could be confidently placed without danger of fracture or loosening due to grinding.
|Figure 7. Right-side view of the maxillary/mandibular anterior provisional restorations in centric relation bite.||Figure 8. Left-side view of the maxillary/mandibular anterior provisional restorations in centric relation bite.|
The laboratory was provided with full-arch impressions, the CR bite registrations, a face bow transfer registration, photographs, and models of the patient’s preoperative condition and oral environment with provisionals in place (Figures 7 and 8).1 The wax-up and a detailed prescription were also provided.
When the definitive restorations were returned from the laboratory, the patient was anesthetized, the provisional restorations were removed, and the preparations were cleansed with pumice and an antimicrobial scrub mixture (Consepsis, Ultradent). The maxillary crowns were tried in first to check the fit, color, and aesthetics. Aesthetic checks included the length of the teeth with lip at smile, the length of teeth with lip at rest, and the shape and contour of the restorations. The mandibular restorations were then tried in and checked in the same manner, and the patient was asked to close lightly to check for even occlusal contacts throughout the mouth. At this point, the most important thing to verify was the absence of any contact that could only be added in the laboratory.
Following satisfactory try-in, final cementation was conducted following a very specific sequence to ensure that proper occlusion was maintained. Crowns No. 6 through No. 11 were cemented with a luting cement (Rely-X, 3M ESPE). This was followed by the placement of veneers on teeth Nos. 22 through 27 according to adhesive protocol and the manufacturer’s specific instructions (eg, etching, bonding agent, Variolink translucent cement [Ivoclar Vivadent], etc).
|Figure 9. Right lateral view of only the final anterior crown restorations.|
|Figure 10. Left lateral view of only the final anterior crown restorations.|
|Figure 11. View of the anterior centric stops of the final restorations.|
|Figure 12. View of the anterior lateral excursion of the final restorations.|
|Figure 13. Retracted view of only the final anterior crowns following cementation.|
The all-ceramic restorations were light cured for 20 seconds each. All excess cement was removed with a scaler. At this time, only the upper and lower anterior restorations were definitively placed (Figures 9 through 13).
The anterior occlusion was then checked, particularly lateral excursions and anterior contacts. The rationale for checking the anterior occlusion and contacts without the posterior crowns in place is be-cause when the posterior crowns are eliminated, the location of the temporomandibular joint in its ideal, fully-seated position—otherwise known as centric relation or adaptive centric position—can be assured, since the only thing that moves the joint out of the centric relation position is a posterior tooth that’s hitting prematurely.
The mandibular posterior crowns were then placed using luting cement (Rely-X) and were checked against the aesthetic zone for conformity. Centric relation was maintained, since the maxillary posterior restorations were not in place, thereby eliminating the possibility of any prematurities or movement of the TM joint from centric relation. At this time, 75% of the restorations were seated.
Finally, the maxillary posterior restorations were seated 2 teeth at a time, from the anterior to the posterior bilaterally, and the occlusion was checked. The presence of anterior contacts was verified, and the absence of prematurities in and out of lateral excursions was assured. All of the incline contacts were eliminated in both maximum intercuspation and lateral excursions, while simultaneously rechecking for good anterior coupling.
|Figure 14. Retracted right lateral postoperative view of the final restorations.|
|Figure 15. Retracted left lateral postoperative view of the final restorations.|
|Figure 16. Retracted view of the final restorations with patient in full occlusion.|
This exact process was re-peated until the farthest crowns in the posterior segment were finally seated. In between each of those seatings, the occlusion was checked, thereby ensuring that the position of the TM joint had not been altered at any point (Figures 14 through 16).
|Figure 17. Right lateral view of the patient in relaxed smile.||Figure 18. Left lateral view of the patient in relaxed smile.|
After all of the restorations were seated, the occlusion was checked again using bimanual manipulation to ensure that centric relation and centric occlusion were the same, without any posterior contacts in lateral excursions (Figures 17 and 18). Excess resin cement was removed, and the definitive restorations were polished using the Brasseler Dialite Kit.
Finally, the patient was asked to sit up, and long centric was checked. Since long centric is an increase in the anterior contact due to a postural change in position, if there were any prematurities or contact in the seated position, those could be eliminated at that time.
|Figure 19. Retracted postoperative view of the final restorations following cementation.||Figure 20. Postoperative view of the patient’s relaxed smile.|
The success of today’s comprehensive cases can no longer be judged immediately based on the visible aesthetic outcome, but rather must be evaluated based on how the overall treatment and prescribed restorations respond to the conclusions drawn during the diagnostic phase. By incorporating the tools indicative of an astute awareness of the importance of occlusal relationships into the comprehensive examination process, clinicians can obtain the important information they need about a patient’s dental architecture in order to make the most appropriate treatment decisions and material/restoration selections to ensure long-term function and patient satisfaction (Figures 19 and 20).
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