Building Beautiful Smiles with Resin and Porcelain
The science of dental materials and occlusion in your everyday practice
Obtaining an accurate diagnosis is essential to analyzing a patient’s dental condition and ultimately completing a successful treatment. This process includes evaluating periodontal, restorative, functional, and cosmetic issues. Once a proper dignosis is made, treatment options become more apparent. The vast array of restorative materials today gives the dentist many treatment alternatives. Some materials, such as composite resin, may be used for preliminary treatment, esthetic previews, and even as a final treatment. Other more durable materials, such as the newer porcelains, are ideal for the definitive treatment. Once the final plan is determined, the dentist may then choose the appropriate material.
A great deal of restorative treatment is done for occlusal rehabilitation and for esthetic reasons. If the occlusal issues are not addressed, the esthetic treatment will fail. Therefore, part of every initial patient evaluation should include an occlusal analysis. One must determine how the patient’s occlusal scheme currently functions. If there is breakdown in the system, one must determine how the patient got into his or her current condition and decide what needs to be done to correct it.
This patient was seeking a correction of severe wear on her anterior and right mandibular arch (Figure 1). She wanted a conservative option and did not want her tooth structure reduced for crowns, if possible. A complete examination was performed including periodontal, functional, and esthetic issues. After the treatment plan was reviewed, initial treatment was begun using a Kois occlusal deprogrammer.1 The deprogrammer allows the muscles to relax and places the mandible in centric relation (CR), irrespective of the position of the teeth.
After 1 week, the patient returned and a bite registration was taken with the Kois appliance in place. Diagnostic models of both arches were acquired, as well as a Kois facial analyzer (Panadent Corporation, www.panadent.com) measurement. The models were mounted on a Panadent articulator for evaluation. The patient was diagnosed with a restricted envelope of function and a decreased vertical dimension from past wear.
After the models were further evaluated, the vertical was increased on the articulator by the addition of wax (tooth structure) on the lower arch. The patient was not interested in any cosmetic improvement on the maxilla at this time. The decision was made to accomplish this treatment through the placement of resin-bonded veneers on teeth Nos. 21 to 28 and replacement of the crowns on teeth Nos. 18 to 20, 30, and 31, as well as a new ceramic crown on tooth No. 29. After 4 weeks to allow for proper deprogramming of the muscles, the treatment began.
While the patient was wearing the deprogrammer, which contacted teeth Nos. 24 and 25, composite was added to the lateral incisors first to contact the lingual of the maxillary anteriors. Composite veneer restorations were completed on the cuspids and first bicuspids, and then the deprogrammer was removed. Resin was then applied to the central incisors.2
A few days later at the second appointment, the remaining teeth were prepared for crowns, with provisional crowns placed at the new increased vertical dimension. The patient was able to “test drive” the new occlusal scheme, then she returned for evaluation of the restorations. The anteriors were completed in resin to reduce cost to the patient (versus porcelain) and maintain the ability to repair the resin if necessary.
Several weeks later, the lower anteriors were closely evaluated for any signs of chipping. As there were no occlusal problems and the patient relayed that the bite “felt great,” the final impressions were taken of the posterior teeth for fabrication of the IPS e.max® (Ivoclar Vivadent, www.ivoclarvivadent.us) crowns. The crowns were seated using G5 desensitizer (Clinician’s Choice, www.clincianschoice.com) and RelyX™ Unicem 2 cement (3M ESPE, www.3mespe.com) (Figure 2).3
Occlusal wear cases can be very challenging and even unpredictable. If there is anterior chipping, one must ask if this is an envelope of function issue, occlusal dysfunction, or are there sleep apnea components? The most important aspect of occlusal treatment is to start with a predictable method that works for the clinician to help restore these cases. It may be a variety of treatments: mouth guards, deprogrammers, or other methods. If one is unsure of the long-term success of new restorations, resin bonding can be a great treatment modality. Resin can be easily repaired, and it holds up better than acrylic provisional veneers and crowns do.
Advise the patient to refrain from wearing any protective devices at night, such as a night guards or mouth guards. Keep the restorations independent of each other; do not splint the teeth together. Look closely for any cracks or chips in the restorative material. Note if there is any tooth mobility prior to beginning the case, and evaluate to see if any mobility develops or if existing mobility improves. Evaluate the patient’s speech for any changes. Patients should certainly let you know if they cannot speak normally. Note if any discomfort arises in the temporomandibular joint (TMJ) or muscles of mastication. If any of these factors are present, ask yourself, is the treatment helping to improve these issues?4
A 59-year-old female patient presented to the office with the chief complaint that she was not happy with her smile (Figure 3). Specifically, she did not like the discolored bonding on her central incisors and the unesthetic appearance of her missing lateral incisors. She inquired about options to replace her existing dental treatment. The two options discussed were dental implants to replace the missing lateral incisors and single crowns on teeth Nos. 6, 8, 9, and 11, or fixed ceramic bridges on teeth Nos. 6 through 8 and 9 through 11. Because significant tooth preparations had already been done on the existing teeth, and considering the additional expense of dental implants, temporization, and laboratory costs, the best option was determined to be two new fixed prosthetic bridges.
After the patient underwent a full evaluation, the decision was made to keep her occlusion unchanged. There was no wear on her teeth, no mobility, and no discomfort in her TMJs. Models were taken in maximum intercuspation (MIP), mounted on an articulator with the Kois facial analyzer, and sent to the laboratory for a diagnostic wax-up of teeth Nos. 5 through 12.5 Evaluation of the smile photographs showed that the buccal corridor could be improved by including the first bicuspids. The patient also was asked to bring in several historical photographs from her high school and college years, which are often invaluable for showing how her original teeth appeared before any tooth preparations. The dentist can evaluate incisal edges, lip position, and overall shape of the natural teeth from her youth. The patient agreed with the esthetic improvements in restoring the bicuspids, but initially decided to proceed only with the six anterior units.
During the preparation appointment, the existing restorations were removed and the edentulous tissue in the lateral incisor spaces was prepared for ovate pontics.6 A Kois bur kit KS-5 diamond bur (Brasseler, www.brasselerusa.com) was used to remove gingival tissue for the ideal pontic contour. The bur is buried in the gingival tissue to the correct depth and height of the adjacent central incisors, which will give the appearance of the prosthetic teeth emerging in a natural way from the tissue. The hemorrhage was controlled with ferric sulfate on a cotton pellet. The diagnostic wax-up had been returned with a putty matrix, which was filled with bis-GMA resin and applied over the prepped teeth and tissue. The provisional bridges were fabricated, and the pontics were fine-tuned to an ideal shape with additional composite resin. The provisional bridges were glazed with Palaseal® (Heraeus Kulzer, http://heraeus-kulzer-us.com). The provisionals were seated with UltraTemp® cement, (Ultradent Products, Inc., www.ultradent.com). This tissue was allowed to heal for 6 weeks, prior to final insertion of the e.max bridges.
Several weeks later, the patient decided to proceed with veneers on teeth Nos. 5 and 12. The teeth were prepared, a final impression taken, and provisional veneers placed with direct composite, spot etched, and bonded with flowable resin. The lab-fabricated layered e.max restorations were returned and seated with Insure Clear (Cosmedent, www.cosmedent.com). The patient returned several weeks later for final photographs (Figure 4).
The tissue adapted very well in the pontic areas, by design. An excellent final result takes several months of tissue maturation. One must be careful in the initial preparation of the ovate pontics. Overly aggressive removal of tissue is very hard to recapture and would result in uneven gingival heights. In this author’s view and from past experience, it is better to slightly underprepare the tissue and then place a slight amount of pressure on the tissue with the ovate portion of the pontic in the temporary. This way the tissue is displaced exactly where it looks best.
A long-term relationship between the dentist and lab technician ensures predictability in the final restorations. The dentist knows exactly how the lab technician will fabricate the pontics based on tissue reduction and can expect a precise, intimate fit. The other component of the bridge is having connectors between the pontic and abutment that are the correct length. Connectors can be thought of as interproximal contact areas. Based on the 50-40-30 rule,7 an anterior bridge has longer connectors on the centrals and decreases as it moves toward the posterior. If an ideal central is 10 mm long, the connector is 5 mm with the adjacent central incisor. The central to lateral would be 4 mm on decreasing further at the cuspid. This ensures a bridge that looks natural (Figure 5).
A patient in her 50s presented to the practice with existing porcelain veneers on teeth Nos. 6 through 11 and a fractured veneer on tooth No. 8. There was evidence of severe acid erosion to the facial aspect of all anterior teeth from dietary and digestive issues (Figure 6). The fractured veneer was re-cemented in fragments and polished using porcelain polishing disks and diamond paste. Afterwards, the patient underwent a comprehensive evaluation. Of note, there was mobility on most maxillary teeth and teeth Nos. 24 and 25. The diagnosis was occlusal dysfunction. There was also noted gingival recession on several teeth. The patient wore an occlusal deprogrammer for the usual 4-week period, and then underwent an occlusal equilibration.
After the patient was stabilized with her bite and hygiene, she had a periodontal consultation for gingival grafts. The periodontist suggested postponing the grafts until after the restorative treatment was completed. After her new porcelain restorations, her anterior recession would be stable and gingival levels would be even. The only gingival concerns were the lower anteriors and some posterior teeth that would not be restored; therefore, postponement would not make any situations worse.
The patient then proceeded with treatment. Diagnostic models were taken in CR/MIP, which were coincidental after the equilibration. The models were sent to the lab technician for a diagnostic wax-up on teeth Nos. 6 through 11. The incisal edge was to remain in the same position postoperatively. The putty matrix enclosed with the completed wax-up was utilized with bis-GMA temporary resin and tried in her mouth for an esthetic evaluation. After the shape and length of the proposed teeth were approved, the patient was scheduled for a preparation appointment.
The existing porcelain was removed, as well as the old composite underneath. The decision was made to prep for a 3/4 crown, leaving as much lingual tooth structure as possible. This increase in remaining porcelain helps to reduce flexure in the tooth.8 The preparations were made with a KS1-L Brasseler bur to the gingival margin. Retraction cord size 0 dipped in ViscoStat® Clear (Ultradent) was used to prevent any discoloration of the provisional crowns or underlying tooth structure. When the tissue was retracted, the margin was dropped another 0.5 mm to ensure non-visible margins in the final restoration. A second cord was placed for the impression technique and removed just prior to injecting the light body impression material (Impressiv Putty and Impressiv Light Body, Cosmedent). Provisional restorations were fabricated in the lab putty matrix using MirrorImage™ (Cosmedent). They were adjusted, sealed with MirrorImage Gloss, seated with ClearTemp™ LC clear cement (Ultradent), and light cured.
The patient returned several weeks later for the final insertion of the e.max crowns. After anesthesia, the provisionals were removed and the preparations were cleaned of the cement with a periodontal scaler. Retraction cord size 000 was placed in the sulcus, soaked in ViscoStat Clear. The preparations were further cleaned with a Danville PrepStart (www.danvillematerials.com) with 27-micron aluminum oxide at 40 psi.9 The crowns were tried in, occlusion checked, and the crowns approved by the patient for color and shape. Each tooth was rinsed, lightly dried, coated with G5 desensitizer, left in place for 30 seconds, then blotted dry. The crowns were then seated with RelyX Unicem and light-cured for 1 second, then excess cement was removed. Then each crown was further cured for 40 sec on all surfaces. The retraction cords were removed, the teeth cleaned further to ensure all excess cement was removed, and the occlusion was refined. As the patient sat upright in the chair, 200-micron articulating paper was used to check for interferences in the envelope of function. All interferences were removed, and the patient was dismissed. A follow-up visit a few weeks later was scheduled to check for proper healing and accuracy of occlusal stability (Figure 7 and Figure 8)
Once the patient discussed replacement of her veneers, the decision became what type of preparation was necessary, taking into account longevity and conservative principles.10 The material choice was also addressed. Based on the existing tooth preparation color, strength desired, and final shade, e.max lithium disilicate was chosen. The e.max was to be pressed and cut back to layer the final porcelain by hand. During preparation, placement of cord with ferric sulfate needed to be avoided to prevent staining when using a resin based clear temporary cement. During cementation, a variety of cements could be used: One could place either cohesive or adhesive cement. An adhesive cement preparation is prepared in a typical bonded restoration fashion and is used when there is not enough tooth structure for retention. The preparations had more than adequate retention form; therefore, a cohesive cement was used.
Many factors need to be considered in any restorative treatment. The patient’s desires are paramount, but must work within the confines of acceptable practices of dental techniques. Occlusal factors must be addressed to ensure longevity. When an occlusal issue is diagnosed but not addressed, the probability of failure increases substantially. If the patient chooses not to treat the occlusion, the decision to proceed must be considered.
For material options, there is a wide variety of resin as well as porcelain choices for the final restorations. Color needs to be considered, based on the color of the underlying tooth structure as well as the final desired outcome. Finally, the dentist must be familiar with the cement properties for not only cohesion/adhesion, but also color interaction of the cement.
The science of dental materials and occlusion comes into play everyday in practice. Our dental treatment depends on understanding and utilizing the proper technique.
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