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Restoration of the Worn and Eroded Dentition: The Maxillary Enamel Sandwich
Stephen J. Markus, DMD
Erosion from gastric acids often compromises tooth structure. Couple acid erosion with a nail-biting habit and there is even less enamel available on which to bond ceramic restorations. This case report demonstrates a technique for placing separate labial and lingual veneers on maxillary anterior teeth to preserve the remain-ing limited enamel. It also demonstrates a technique for increasing the vertical dimension of occlusion that enables a reliable intervisit cross-check to ensure that the condyles have not seated further and resulted in a changed jaw position.
Today’s complex treatment plans help dentists to achieve outstanding functional, esthetic, and time-proven results using techniques and materials that were unavailable just 15 years ago. The importance of marrying form with function cannot be overstressed, and this realization has led many dentists to take extensive courses on treating advanced cases.
Opening the vertical dimension of occlusion (VDO) is an area of uncharted territory for many dentists. This procedure’s success depends on being able to obtain a comfortable jaw position that remains unchanged during a transitional phase while the patient is in temporaries. The establishment of a level plane of occlusion is important so that even, simultaneous contacts can be made.1
Measuring simultaneity of contacts and equal distribution of contacts can be achieved through technology. The paradigm has shifted as recent research has shown that articulating paper marks do not accurately represent the amount of bite force being registered.2 Paper marks also do not show premature contacts. Through the use of a computerized occlusal analysis system (eg, T-Scan® III, Tekscan Inc, South Boston, MA), occlusal contact, functional and parafunctional forces, contact timing sequences, and occlusal surface interface pressures can be analyzed. With this data the clinician can fine tune the patient’s bite to distribute forces equally between all teeth.
Parafunctional habits often wreak havoc on the dentition. Nail biting is probably one of the worst of these in terms of wearing out the incisal edges of teeth. The widespread use of drugs like omeprazole and esomeprazole are indicative of the vast numbers of people with gastroesophageal reflux disease (GERD), erosive esophagitis, and heartburn. Eating disorders such as bulimia also create acid, which, when vented through the upper extent of the alimentary canal, have the effect of eroding enamel on teeth.3
Enamel preservation has always been a major concern when restoring teeth. Bonding to enamel, which is preferred over dentinal bonding whenever and wherever possible,4 was the impetus for newer limited-preparation veneers, such as feldspathic porcelain and DURAthin® veneers (The Nashville Center for Aesthetic Dentistry, Brentwood, TN), that allow for minimal incursion into pristine enamel.
The case presented here encompasses all of these concepts. As will be detailed, when coupled together, a laboratory technician and cosmetic/advanced restorative dentist can provide results that are long-lasting and life-changing.
A 29-year-old man presented for a consultation regarding the esthetic problems he was facing with his smile. He already had consulted with an orthodontist who had suggested intrusion of the lower anterior teeth, with the need for veneers following stabilization. It was estimated that this course of action would take 2 years. The patient wanted a more immediate result. After looking at his smile (Figure 1) and fingernails, the patient was informed that no porcelain veneers could be guaranteed to withstand the forces that he was using to bite his nails. The patient was instructed to return to the office in 3 weeks, sporting unworn, neatly trimmed fingernails. Without this request being met, no restoration of his teeth would be considered.
The patient returned 3 weeks later for the record-taking visit. Full-mouth radiographs (Figure 2) showed a healthy dentition with minimal restorations in the posterior teeth. Examination of the arches showed areas of erosion on the lower molars, which indicated the patient might be suffering from GERD (Figure 3). Specifically, erosion was visible on tooth No. 19, the buccal cusp tip of tooth No. 21, the mesiobuccal cusp inner incline on tooth No. 30, and the mesiolingual inner incline on tooth No. 31.
The examination of the maxillary arch was more revealing in that there was total erosion of the enamel down to the cementoenamel junction on the cervical aspect on the palatal of the six anterior teeth (Figure 4). The patient denied any history of bulimia; however, he noted that he had been treated in his early twenties for GERD. In cases where there is a history of an underlying medical problem, the author recommends having a consultation from a physician, in this case a gastroenterologist, to ensure that the condition is not ongoing or exacerbating the oral symptoms. The physician’s report was negative, and diagnosis and treatment planning moved forward.
One of the more obvious areas of concern was the lingual cant of the upper centrals contributing to a locked-in dentition (Figure 5). The patient was in a crossbite, without any premolar support on the left side. The occlusion on the right side was Class I (Figure 6 and Figure 7). The treatment plan called for creating a more favorable occlusal relationship and correcting the cant of the centrals through long-centric in the provisional and permanent restorations.
The patient’s temporomandibular joint examination was normal with no joint sounds, normal range of motion, and no history of headache or temporomandibular dysfunction.
Study models were made, and a facebow transfer was taken to mount the case on a Denar® articulator (Whip Mix Corp, Ft. Collins, CO) in centric relation (CR). CR was determined using a small ball of acrylic on the upper anterior teeth per Kois.5 It was determined that the VDO would need to be increased to create enough clearance in the anterior region for lower incisal edges and maxillary palatal porcelain.
The mandibular arch showed a cathedralized lower anterior segment. Often caused by airway disturbances while young, the inability to breathe through the nose while sleeping has been shown to create an irregular occlusal plane in the mandible. Because the growth and development of the maxilla is slowed, the mandible cannot expand beyond the confines of the upper anterior teeth, and so the lower anteriors become “cathedralized,” ie, erupted to the palate rather than the maxillary anterior cingulums, and the posterior teeth never erupt to their fullest potential.6 To open the VDO, the posterior teeth were overlaid with IPS Empress® porcelain onlays (Ivoclar Vivadent, Inc, Amherst, NY). The laboratory was given specific instructions about the setting of the anterior guide pin on the articulator, and returned eight overlays that would be bonded directly to the occlusal surfaces of the molar teeth in the mandible. The laboratory also was instructed to perform a cosmetic sculpture in wax of the six upper and lower anterior teeth and to provide Sil-Tech® (Ivoclar Vivadent, Inc) matrices for fabrication of the temporary restorations.
Two weeks later, the patient was given the opportunity to review the sculpture and make any changes to it that he wished. The esthetic importance of veneering the maxillary bicuspids to widen the buccal corridor was discussed with the patient. While he understood the results would be compromised esthetically, the costs precluded performing this treatment in the first phase of his rehabilitation. No changes to the treatment were needed; therefore, an appointment was scheduled to accomplish this dentistry.
The appointment began by isolating the lower left quadrant beneath a rubber dam. Using the International Academy of Oral Medical Toxicology (IAOMT) protocol for mercury removal, his mercury/ amalgam restorations were removed and the surfaces of all posterior teeth were roughened and cleaned with a micro-etcher. All restorative surfaces were etched with phosphoric acid and any exposed dentin was treated with Gluma® (Hereaus Kulzer, Inc, Armonk, NY) before luting the overlays to the teeth. Each tooth was painted with Prime & Bond® NT™ Unit Dose (DENTSPLY Caulk, Milford, DE), and the onlays were etched, silanated, painted with Prime & Bond NT, and luted using dual-cured luting cement (Vitique®, Zenith/DMG Brand Division Foremost Dental LLC, Englewood, NJ). An ultrathin metal matrix (0.001-mm thick) was placed proximally to prevent the need to break a “welded” contact.
The same steps were taken on the right side, and the occlusion balanced, as best as possible, using the T-Scan III for verification. Figure 8 shows the immediate post-bonding, pre-adjustment bite record. The lower anterior teeth were then roughened, etched, and coated with a self-cure bonding agent; the lower Sil-Tech index was placed over the arch with Luxatemp® (Zenith/DMG Brand Division Foremost Dental LLC) within the six anterior teeth hollows, resulting in six splinted lower anterior temporaries in place (Figure 9).
Similarly, the upper anterior teeth were overlaid with composite, not yet prepared, in anticipation of ensuring that the jaw relationship would be stable for a period of at least 1 month without deviation or dysfunction. It is important to take time when altering VDO. T-Scan III analysis enables a more accurate fingerprinting than simply relying on articulating paper marks. T-Scan III movies can be compared between visits to ensure that no changes in force distribution have occurred. Often, when opening VDO, the condyles are not seated properly within the articular fossae. As the condyles seat further, an anterior open bite can develop because the posterior teeth hit first.3
After seating the anterior temporaries, the patient was dismissed and instructed to return to the office in a few days to inspect his oral hygiene, his fingernails, and his occlusion. The patient was sent home with a nocturnal inhibition of trigeminal nociception (NTI) device (NTI-tss, San Diego, CA) that fit over his upper temporaries to prevent breakage if his musculature attempted to find a more comfortable position nocturnally.
The completed first iteration of the temporaries was also adjusted to all excursions (Figure 10 and Figure 11). A T-Scan III recording was made, to cross-verify that the occlusion remained unchanged between bite-assessment visits (Figure 12).
Two subsequent visits, 2 weeks apart, allowed slight enhancement of the occlusion, but no major changes were necessary. The patient was totally comfortable with the esthetics, phonetics, and function. He was scheduled to have the lower anterior teeth prepared for veneers. An impression of the upper arch with its six temporaries was taken, and a facebow transfer was performed. Several weeks later, the six lower anterior veneers were bonded to place (Figure 13), as described in a later section. Then, the upper anterior teeth were prepared in a very unique manner for their veneers.
The Maxillary Enamel Sandwich
Preservation of enamel for bonding on the patient’s severely eroded teeth was important for long-term results. In this case, there was an option to avoid considerable reduction of tooth structure. As Figure 4 showed, erosion had “prepared” the palatal aspect of the maxillary anterior teeth. If these teeth were to be crowned rather than veneered, a considerable aspect of support for the porcelain—the intact interproximal enamel—would be lost. Again, a facebow transfer (Denar® Slidematic, Whip Mix Corp) was necessary, and 12 veneers for the upper six anterior teeth were prepared against a model of the completed lower arch.
In discussion with the laboratory technician, it was decided not to risk potential transportation and/or insertion fracture of a V-shaped veneer. Instead, 12 veneers (six labial, six palatal) would be inserted onto the anterior teeth. A comparison of Figure 14 with Figure 4 demonstrates how little of the palatal aspect of these teeth changed after preparation. Minimal reduction was performed on the labial, and an EF 853 size 008 “mosquito” diamond (Coltène Whaledent, Inc, Cuyahoga Falls, OH) was used to break the contacts and allow for die separation and finishing of the porcelain margins. The laboratory returned the 12 veneers labeled and coded for facilitation of insertion.
The Insertion of 12 Veneers on Six Teeth
The patient’s six maxillary anterior teeth were anesthetized, and the temporary veneers were removed using a slit with a bur and Christensen Crown Remover (Hu-Friedy, Chicago, IL). The preparations were polished with Consepsis® scrub (Ultradent Products, Inc, South Jordan, UT) to eliminate bacteria from the tubules, and the teeth were isolated with an OptraGate® (Ivoclar Vivadent, Inc). In pairs, the labial and palatal veneers for each tooth were tried in to assess fit. Minimal internal adjustment was necessary. With the knowledge that everything was going to fit together, working six-handed, seating began.
To complete the complicated procedure, the author and his chairside assistant etched the palatal surfaces, one tooth at a time; an additional assistant prepared the palatal veneer for that tooth by conditioning the surface with hydrofluoric acid, silanating the surface, and then applying bonding agent. When ready, the veneer was loaded with Calibra® esthetic resin cement (DENTSPLY Caulk) and pressed to place. The excess cement was cleaned using a paintbrush and, while being held in place, the labial veneer was tried in to ensure that each palatal veneer was in the correct position. After ensuring the position, the palatal veneer was tacked for 3 seconds with a tacking tip. The labial veneer was then removed, and the additional assistant used acetone to cleanse its internal aspect. This process was repeated for all six palatal veneers (Figure 15).
At that point, centric occlusion was verified (Figure 16) and adjusted slightly. In the author’s experience, adjusting the occlusion after the labial veneers are placed runs the risk of slight flexure in a hyperocclusive tooth, which could cause partial delamination of the labial veneers.
After adjustment, the buccal veneers were placed individually using a similar technique as for the palatal veneers. Figure 17 shows the immediate post-insertion results for the maxillary arch. A comparison of Figure 5 with Figure 18 shows the establishment of long-centric anterior occlusion. Another NTI was fabricated for nocturnal protection of the porcelain artistry. The patient returned for postoperative porcelain adjustment to all excursions, as verified using the T-Scan III (Figure 19, Figure 20, Figure 21, Figure 22, Figure 23 and Figure 24).
The author would like to thank colleagues Brian McKay (Seattle, Washington) and Urs Belser (Geneva, Switzerland) for their collaboration on this case. Juan Olivier (Advanced Dental Design, Sandy, Utah) once again helped me to achieve an outstanding result for our patient.
The author is a current consultant for Zenith Dental.
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4. Castelnuovo J, Tjan AHL, Philips K, et al. Fracture load and mode of failure of ceramic veneers with different preparations. J Prosthet Dent. 2000;83:171-180.
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6. Hinton VA, Warren DW, Hairfield WM. Upper airway pressures during breathing: a comparison of normal and nasally incompetent subjects with modeling studies. Am J Orthod. 1986;89:492-498.
7. Dawson PE. Functional Occlusion: From TMJ to Smile Design. St. Louis, MO: Mosby; 2006:259-270.
About the Author
Stephen J. Markus, DMD
Haddon Heights, New Jersey