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Aesthetic Correction of a Damaged Occlusion Using Varied Preparation Designs and Pressed Ceramic Restorations
Written by Ian E. Shuman, DDS, FAGD Monday, 01 March 2004 00:00
Occlusal damage can be caused by a variety of factors, including primary and secondary malocclusion, parafunctional habits, missing teeth, caries, and failing restorations. In many cases the patient has adapted to his or her occlusal scheme without secondary, extra-occlusal symptoms such as temporomandibular dysfunction, muscular pain, and headaches. In such asymptomatic cases the challenge lies in restoring and strengthening the dentition without significantly altering occlusal function or reducing tooth structure unnecessarily. The preservation of tooth structure is the hallmark of responsible dental care—minimally invasive, atraumatic restorative treatment by virtue of little or no tooth reduction where applicable.
When placing porcelain veneers, it has been demonstrated that little to no tooth reduction in preparation design offers many benefits, including a reduced potential for fracture of the ceramic restoration1 and the avoidance of exposing sensitive tooth structure with possible postoperative sensitivity.2 In addition, maximum preservation of enamel imparts superior bond strengths and provides the option for a reversible procedure if needed.
This article presents a case report in which minimally invasive treatment methodology and a laboratory-fabricated, indirect restorative material were used.
Appointment 1: The Consultation
A 70-year-old female presented with the chief complaint that her teeth were chipping, the colors mismatched, and the bonding of the 2 front teeth dull and dark (Figure 1). In addition, she noticed that black areas were apparent at the gumline of all of her crowns, and food was collecting between the gaps of her lower front teeth. Following a complete examination, including a full mouth series using digital radiography (Trophy RVG, PracticeWorks) and study models, the following findings were noted:
• Teeth Nos. 2, 4, 6, 8, 9, 10, 19, and 31: failing restorations with associated caries;
• Teeth Nos. 5, 7, 12, 13, and 14: porcelain-to-metal (PFM) crowns with exposed metal margins because of gingival recession but with no evidence of caries;
• Teeth Nos. 11, 20, and 22 through 27: severe enamel wear with fracturing and dentinal exposure;
• Teeth Nos. 1, 3, 15, 16, 17, 18, 21, 30, 32: missing; and
• Periodontal exam and temporomandibular analysis and exam were within normal limits despite the loss of posterior teeth, decreased vertical dimension of occlusion, and bilateral group function guided occlusion.
|Figure 1. The case presented with abrasion, failing restorations, mismatched colors, black lines at the cervical of PFMs, and gaps.|
Based on these findings a simplified treatment plan was created that would treat the damaged incisal surfaces and existing carious lesions, correct the aesthetic deficiencies, and enhance the occlusion, all with minimal tooth reduction. It was noted that beneath the large direct composite "crowns" on the maxillary central incisors was subgingival caries that would require the complete removal of existing restorative material as well as the infected carious dentin. These teeth would be restored with pressed Cerinate Porcelain crowns (Den-Mat Corp). The remaining dentition from the right maxillary first premolar to the maxillary left first molar and the mandibular left canine to the mandibular right first premolar would have little or no preparation and be restored with pressed Cerinate Porcelain veneers. These veneers would correct the occlusal wear and damaged enamel and dentin, and would aesthetically correct the clinically acceptable but unaesthetic existing PFM crowns. In addition, the lingual surfaces of the maxillary right and left lateral incisors and canines would be enhanced with pressed Cerinate veneers to correct the occlusal architecture through canine protected occlusion. This plan would preserve the maximum amount of tooth structure and provide even wear by virtue of the new porcelain-to-porcelain contacts. The remaining posterior dentition would be restored with traditional, full-coverage, Captek-to-Porcelain (Keating Dental Arts) fixed restorations.
Cerinate Porcelain is a feldspathic porcelain that can be created in thicknesses as low as 0.2 mm. This allows for minimal to no tooth reduction3 without the additional bulk that would create a fuller lip or cause phonetic difficulties.1 Cerinate Porcelain has been extensively studied for more than 20 years4-7 and has been found to be a material with excellent longevity and strength.8 Its flexural strength falls in a range occupied by aluminum oxide-reinforced core porcelains.9 Its low coefficient of thermal expansion prevents fracturing and debonding, with thermal expansion characteristics similar to enamel. Cerinate Porcelain has been used in a number of applications including veneering to aesthetically compromised natural teeth,10 veneering to existing unaesthetic crowns,10,12 3-unit fixed anterior prostheses,13 periodontal prostheses,14 regaining cuspid guided occlusion,15 diastema closure,16 inlays,17 onlays,18,19 and crowns.
Appointment 2: Preparation
The maxillary left and right central and lateral incisors were locally anesthetized and all existing restorative material was removed. Upon complete removal of the defective composites, there was little remaining of the original central incisors, and it appeared as if the teeth were previously prepared for full coverage preparations. Infected caries was then removed using SmartPrep (SS White), a rotary polymer instrument, at 700 rpm. Because of their subgingival nature and close pulpal proximity, the lesions were restored with Geristore Syringeable, (Den-Mat Corp), a resin reinforced glass ionomer in a dual-cartridge delivery system. Because of its histological biocompatibility20,21 and kindness to the pulp,22 it is an ideal restorative material in deep carious lesions.
The crown preparations of the central incisors were completed with full shoulder margins and shallow antirotation slots. Temporary crowns were fabricated for the maxillary central incisors in shade A1 using CBV TEMP (Den-Mat Corp) bis-acryl temporary material. These were used as a guide to determine the amount of labial reduction required in the maxillary teeth and the amount of incisal reduction needed in the lower anterior teeth. The remaining maxillary teeth were minimally prepared with facial recontouring and rounding of sharp incisal edges (Figure 2). The mandibular anterior teeth (Figure 3) were then reduced at the inciso-labial aspect to remove sharp, unsupported enamel and create sufficient room to accommodate adequate incisal thickness for the ceramic restorations. It should be emphasized that this technique does not require the fabrication of temporary veneers because of its minimally invasive preparation design. The provisional crowns were removed and a final polyvinyl impression made in a triple tray using 1st Impression (Den-Mat Corp); Heavy (purple) base fast-set was followed by Light (yellow) wash, and the provisional crowns were temporarily cemented.
|Figure 2. (Top) A closeup view of the upper anterior teeth prior to preparation. (Bottom) Ceramic crown preparations of the central incisors; only facial recontouring and rounding of incisal edges were needed to prepare the remaining upper teeth for veneers. Provisional veneers were not needed.||Figure 3. (Top) A closeup view of the lower anterior teeth prior to preparation. (Bottom) Preparations were made only at the inciso-labial to remove sharp, unsupported enamel and create sufficient room to accommodate adequate incisal thickness for the ceramic restorations. This technique does not require the fabrication of temporary veneers because of its minimally invasive preparation design.|
Using simple technology and standard dental materials, the laboratory can be given a wealth of information. In addition to the standard prescription form and detailed final impressions, preoperative study models are essential. Also, preoperative images of the patient's dentition using a digital camera and color printer can be created in minutes. These data offer the laboratory technician a powerful view of what you are attempting to aesthetically correct and rehabilitate. Also, your vision of tooth dimension and color is critical, and when conveyed through writing or as a wax-up creates the opportunity for unbelievable success. In this case, all of the above items were sent, as well as measurements of the original maxillary central incisor width and the desired width in keeping with the Rule of Golden Proportions.
Appointment 3: Case Insertion
The definitive Cerinate Porcelain pressed ceramic restorations were received from the Den-Mat laboratory in shade B1 (Figure 4). The veneers are pre-etched in the lab first by sandblasting with aluminum oxide then chemically etching with hydrofluoric acid. Nevertheless, when working with the Cerinate Porcelain System, prior to evaluation with try-in paste and/or final cementation, Porcelain Conditioner (Den-Mat Corp) is applied to the intaglio surfaces of the veneers for 15 to 20 seconds, rinsed, and dried. This increases the surface tension of porcelain and activates the Cerinate Prime (Den-Mat Corp), a silane-coupling agent that is immediately applied to these surfaces for 30 to 60 seconds and gently air-dried. It is important to note that there is a component of light-cured resin in this silane, and therefore the veneers should not be light cured at this time. The temporary crowns of the central incisors were removed and the maxillary teeth prophylaxed, rinsed, and dried. The maxillary labial veneers and crowns were tried in using Ultra-Bond Try In Paste Clear Shade (Den-Mat Corp), a noncure try-in resin. Excess paste was removed, margins were examined, and the overall aesthetic scheme was evaluated.
Using a large photographic mirror, the maxillary anterior teeth were evaluated from the incisal aspect (Figure 5). This provides a view of tooth contours in the vertical and horizontal dimensions, as well as arch form, tooth width, and rotations, among others. In addition, the interarch distance was examined, demonstrating the amount of room easily created by this minimally invasive preparation design. The patient was then given a mirror in order to evaluate her new smile. Once it was agreed that the restorations were excellent, they were removed and the majority of the try-in paste was removed with a resin-saturated applicator (Dabeze, Den-Mat Corp). Because Ultra-Bond Try In Paste has all the chemical components of a bonding cement minus the photo or chemical bond initiators, the remaining thin layer is incorporated into the final dual-cure composite cement and therefore need not be entirely removed. The veneers and crowns were set aside and the teeth prepared for cementation.
|Figure 4. The definitive pressed ceramic restorations were received from the laboratory in shade B1.||Figure 5. With the upper restorations in place with try-in paste, this incisal view demonstrates the amount of space available for the lower veneers, easily created by this minimally invasive preparation design.|
The preparation of the intraoral surfaces required bonding to 2 different substrates: existing porcelain and enamel/dentin. The Ultra-Bond Try In Paste was removed from all surfaces using a cotton pellet saturated in an alcohol-based mouthrinse. The surfaces were then rinsed and dried. Gingival tissue surrounding the porcelain surfaces were isolated using Light Cure Paint-On Dental Dam (Den-Mat Corp). The porcelain surfaces of the existing PFM crowns were mechanically etched with 50-um aluminum oxide using an intraoral sandblaster (Microetcher IIA, Danville Engineering), then rinsed and dried. These surfaces were then acid etched for 2 minutes using Porcelock (Den-Mat) a biocompatible hydrofluoric acid, then rinsed and dried. The blockout resin was removed, and all enamel and dentin surfaces were etched for 15 seconds with EtchN'Seal (Den-Mat Corp), a 25% phosphoric acid gel containing oxalate crystals designed to prevent acid etch induced sensitivity. The tooth surfaces were then rinsed and dried, followed by the application of Porcelain Conditioner for 30 seconds, rinsed, and dried. Then Cerinate Prime silane was applied to all porcelain surfaces and dried.
Tenure A and B (Den-Mat Corp), a 2-bottle, chemical- curing, multipurpose adhesive system, was applied in 5 coats to all surfaces, followed by the application of Tenure S (Den-Mat Corp), a single-component, light-cured, hydrophilic agent that further enhances bonding. For the past 2 decades, the Tenure system has demonstrated a proven clinical record of high bond strength,23 excellent retention,24 and significant reduction of microleakage25 and postoperative sensitivity. These characteristics can be attributed to the formation of a hybrid zone26 that can quickly eliminate root sensitivity. The easy 2-step process of Tenure A, B, and S exhibits bond strengths to dentin of more than 20 MPa.
The veneers and crowns were then cemented into place by dispensing Clear shade Ultra-Bond Plus (Den-Mat Corp) from an automix dual barrel syringe. Ultra-Bond Plus is a multipurpose, dual-cure resin cement designed specifically for bonding porcelain restorations. A study reviewed an initial veneer placement of Cerinate Veneers with Ultra-Bond in 1985 and then evaluated the veneers after 17 years when they were replaced due to aesthetic wear.4 The 17-year-old case showed no evidence of microleakage, gingival recession, cracks, or fractures.
The restorations were all seated to place, and excess cement was removed using an applicator brush saturated in an unfilled resin (Visar Seal, Den-Mat Corp). Each restoration was then firmly seated (Figure 6) by directing gentle pressure from the incisal and facial aspects simultaneously until a thin bead of resin cement was expressed from the marginal areas. The Cerinate Porcelain restorations were held in this fashion and light-cured one-by-one for 3 seconds each using the Sapphire Curing Light (Den-Mat Corp), a versatile PAC (Plasma Arc) Light known for deep penetration and rapid 3- to 5-second curing ability. In a study by Watanabe,27 the bond strength achieved by plasma-arc curing was found to be relatively unaffected by the shade or opacity of porcelain. It was found that plasma-arc curing for 6 seconds was sufficient to obtain bond strengths similar to those of specimens polymerized with halogen light for 40 seconds. The same procedure was then followed for the bonding of the Cerinate Porcelain veneers from teeth Nos. 22 through 28 and the upper lingual of the maxillary lateral incisors and canines.
Once cured, gross excess Ultra-Bond Plus resin cement was first removed from the facial aspects using the Schure 349 (Den-Mat Corp), a nonscratching resin removal hand instrument (Figure 7). This was followed by fine removal at the margins using carbide finishing burs (ET Carbide Combo Kit, Brasseler USA). The often flake-like remaining translucent resin cement can be removed from the facial surfaces using an Occlubrush (Kerr). If interproximal contacts cannot be easily flossed following curing, it is best to engage the contacts after 24 hours to avoid disturbing the ongoing curing process of the Ultra-Bond Plus resin cement. In addition, the interproximal cement of porcelain veneers bonded to existing porcelain crowns should ideally be adjusted 24 hours after bonding.
|Figure 6. The veneers seated to place by directing gentle pressure from the incisal and facial aspects simultaneously until a thin bead of resin cement is expressed from the marginal areas.||Figure 7. Any remaining Ultra-Bond Plus resin cement is first removed from the facial aspects using the Schure 349 hand instrument, a nonscratching resin remover, followed by fine removal at the margins using carbide finishing burs.|
Unlike porcelain veneers bonded to enamel, porcelain veneers bonded to porcelain will attain their maximum optimal bond strength after 24 hours. In a study by Peters and Meiers28 the shear bond strengths to porcelain were evaluated using dual-cured resin cement with light/chemical curing (dual) or chemical only curing vs. time. Dual curing provided significantly higher shear bond strengths vs. chemical curing at both the 60-minute and 24-hour time periods. Occlusal adjustment was accomplished with finishing diamond burs (Et Diamond Combo Kit, Brasseler USA), carefully insuring that proper canine protected occlusion (Figure 8), anterior guidance, and occlusal contacts were correct. When compared to the patient's original presentation (Figure 9), vertical dimension of occlusion was now increased and harmony was restored to the patient's dentition (Figure 10). The adjusted areas were polished using the Dialite Ultra Porcelain Resurfacing System (Brasseler USA). The patient was placed on a home care program and given a 24-hour follow-up appointment.
|Figure 8. Carefully insuring proper canine protected occlusion.|
|Figure 9. Patient's pretreatment occlusion.||Figure 10. Vertical dimension of occlusion is now increased and harmony restored to the patient's dentition.|
Appointment 4: Follow-Up
One day later, the existing interproximal resin cement had loosened in many places, making the task of cleanup easier. All interproximal contacts were flossed to evaluate the areas requiring attention, and noted. To separate the resin cement in these areas, a manual interproximal separating instrument, the CeriSaw (Den-Mat Corp), was used. The CeriSaw, a stainless steel 0.05-mm serrated blade, was placed at a 45o angle to the incisal plane of the interproximal junctions and gently rocked in a see-saw fashion toward the gingival until the cement bond was separated (Figure 11). Any remaining interproximal resin was removed and polished using the CeriSander (Den-Mat Corp), a single-sided, diamond-coated interproximal strip that utilizes the same handle as the CeriSaw. The case was then completed by restoring the remaining posterior teeth with fixed, full-coverage, Captek-to-Porcelain restorations (Keating Dental Arts) and evaluated from an occlusal view (Figure 12). The patient's before and after appearance was evaluated from both smile closeup (Figures 13 and 14) and portrait views (Figures 15 and 16).
|Figure 11. The CeriSaw placed at a 45o angle to the incisal plane of the interproximal junctions and gently rocked in a seesaw fashion toward the gingival until the cement bond is separated.||Figure 12. The case completed by restoring the remaining posterior teeth with fixed, full-coverage Captek-to-Porcelain restorations and evaluated from an occlusal view.|
|Figure 13. Smile before.||Figure 14. Smile after.|
|Figure 15. Portrait view before.||Figure 16. Portrait view after.|
When treating a severely damaged dentition, many preparation designs and restorative choices are available. The advantages of the minimally invasive preparation design are numerous. When combined with the proper restorative material that provides the required aesthetics, strength, and reliability in high-stress occlusal situations, the rewards are many.
The author would like to thank Dr. Robert Ibsen for invaluable assistance in the preparation of this article. His creative approach and innovative concepts give true meaning to the phrase "out of the box" thinking. Steve Ostapiuk and Den-Mat Laboratories for their expert craftsmanship and aesthetic excellence. Gloria Barnette, a true gem. And special thanks to Shaun Keating of Keating Dental Arts, a superb technician, for his contribution to this case.
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Dr. Shuman maintains a full-time private practice outside Baltimore, Md, emphasizing reconstructive and aesthetic dentistry. He is a fellow in the Academy of General Dentistry, a fellow of the Pierre Fauchard Academy, and a member of the American Dental Association. Since 1989, Dr. Shuman has published more than 50 dental research and clinical articles that have appeared in numerous dental journals. Dr. Shuman has produced educational videos, and books that are enjoyable, provocative,and invaluable resources. For more information, call (877) 4-SHUMAN or visit ianshuman.com.
Disclosure: Dr. Shuman has received research support from Den-Mat Corporation in preparation for this article.
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