Biomimetics and Conservative Porcelain Veneer Techniques Guided by the Diagnostic Wax-Up, Diagnostic Matrix, and Diagnostic Provisional

Clinical Science Phelan and Heindl Biomimetics and Conservative Porcelain Veneer Techniques Guided by the Diagnostic Wax-Up, Diagnostic Matrix, and Diagnostic Provisional

by Stephen Phelan, D.D.S. Harald Heindl, M.D.T. Stephen Phelan (left) is a 1992 graduate Abstract of the University of Toronto, Faculty of The use of porcelain veneers for a conservative esthetic reha- Dentistry. He trained with Drs. John bilitation can lead to improvement in the biomechanical and Kois, Frank Spear, Peter Dawson, Jimmy esthetic properties of the tooth when the preparation is limit- Eubank, Jeff Morley, Bill Strupp, Buddy Mopper, and Newton Fahl. An Accredited ed mostly to dental enamel. This article presents a predictable Member of the AACD, he is also a system to create the tooth preparations and porcelain veneer member of the Canadian Dental restorations based on the additive diagnostic wax-up. This sys- Association. Dr. Phelan has written in tem promotes a minimally invasive tooth preparation with the the Canadian Dental Association preservation of enamel and the fabrication of conservative and Journal and the AACD Journal. His highly esthetic porcelain restorations. private practice, limited to esthetic, restorative, and implant dentistry, is in Oakville, Ontario. He can be reached at Following the principles of biomimetics as applied to [email protected]. dentistry, the clinician should strive to restore or mimic the biomechanical, structural, and esthetic integrity of the tooth. Mr. Heindl (right) began his career as a ceramist in Germany in 1980. He earned his M.D.T. in 1991 from the Masterschool for Dental Technology in Introduction Munich. In 1997, he founded Aesthetic Biomimetics is the study of the structure and function of bi- Dental Creations in Mill Creek, ological systems as models for the design and engineering of Washington, focusing on bondable porcelain restorations, implantology, and materials. Following the principles of biomimetics as applied complex full-mouth rehabilitations. Mr. to dentistry, the clinician should strive to restore or mimic the Heindl is an affiliate faculty member in biomechanical, structural, and esthetic integrity of the tooth.1 the graduate prosthodontic program at When the patient and clinician’s treatment of choice is a conser- the University of Washington. His work vative esthetic rehabilitation with porcelain veneers, it is para- has appeared in PPAD, Quintessence mount to be respectful of the existing tooth structure, especially of Dental Technology, and Dental the dental enamel. The use of porcelain as an enamel substitute Dialogue. He can be reached at is an excellent application of the biomimetic principle due to [email protected] or haraldheindl@ hotmail.com

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Figure 1: Initial presentation of the patient with Figure 2: Incisors after completion of orthodontic orthodontic therapy. Note the reverse smile line and therapy. Note the poor length-to-width ratio of the short central incisors. central incisors.

the similar elastic modulus, thermal tooth preparation to the desired fi- amount of tooth wear, with the cen- expansion, and optical properties of nal outcome, as represented by the tral incisors displaying a length of the two structures.1 When the origi- additive diagnostic wax-up. A variety 7.8 mm and a width of 7.1 mm (Fig nal tooth has a thinned-out or worn of putty stents have been developed 2). The patient also had a reverse enamel surface and is restored to that aid the clinician in relating the smile line and diastema between the original volume with porcelain as diagnostic wax-up to the tooth prep- maxillary central and lateral incisors. an enamel substitute, studies have arations; this technique has proven The occlusal examination revealed found that the tooth recovers much very predictable in creating a more no temporomandibular disorder, of its original structural, optical, and conservative porcelain veneer prepa- muscle pain, or tooth mobility, but biomechanical properties.1 Numer- ration. This article demonstrates a the patient had a number of poste- ous retrospective studies that look simplified technique to relate the rior centric relation (CR) interfer- at porcelain veneer longevity have diagnostic wax-up to the tooth prep- ences and group function guidance. also found that the veneer will have arations in an efficient and reliable The treatment plan, following the more predictable long-term success manner. This approach also allows completion of orthodontic therapy, if the restoration is bonded primar- the patient to preview the case be- called for initial muscle deprogram- ily to enamel.2,3 This is especially fore any tooth preparation and an- ming and equilibration with the aid true at the facial-axial region of the esthesia begins. of a Kois deprogrammer. This would tooth preparation, and care should be followed by 10 feldspathic por- be taken not to remove excessive celain veneers on the maxillary arch The additive diagnostic wax-up is enamel at this critical region.4 to lengthen the teeth, reestablish a critical step in the biomimetic The traditional approach for por- approach to preservation of cuspid guidance, and create a more celain veneer preparation was to use enamel, and the clinician must be pleasing smile. a depth-cutting diamond on the able to accurately relate this wax- The diagnostic wax-up was com- existing tooth surface and remove up to the final tooth preparations. pleted after the initial equilibration a fixed amount of tooth structure. on a new set of study models that This technique leads to an exces- were mounted in the CR position sive loss of sound dental enamel on a Sam 3 articulator (Great Lakes with unnecessary dentin exposure, Case Presentation Orthodontics; Tonawanda, NY). especially in patients that already The patient, a 39-year-old male, The wax-up was completed using have wear or thinning of the enamel presented prior to the completion of an additive technique that was de- surface that will be restored with orthodontic therapy with the desire signed to preserve the existing intact the new veneers.5 This preparation to enhance his smile with porcelain enamel and add wax to build up the method has been replaced by newer veneers (Fig 1). The initial assess- new tooth form that would then be techniques that attempt to relate the ments revealed a moderate to severe replaced with porcelain (Fig 3). The

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Figure 3: Duplicate die-stone model of the diagnostic Figure 4: The diagnostic matrix, spot-bonded into wax-up. Note the improved length and proportions of place. Note the correction of the reverse smile line. the central incisors.

Figure 5: Depth cut being placed in the cervical third Figure 6: Depth cuts marked with a lead pencil for of the diagnostic matrix. Note that the shank of the easy identification. The diagnostic matrix and a diamond is resting directly on the matrix material to small volume of enamel can now be accurately and ensure that the depth cut is accurate. efficiently removed to the ideal preparation depth.

Figure 7: Rapid reduction to the level of the depth Figure 8: Inspection of the initial veneer preparation cuts is facilitated by larger round-end diamonds. depth with the horizontal putty matrix created from the diagnostic wax-up.

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Figure 9: Inspection of the final axial reduction with Figure 10: Final conservative veneer preparations with the vertical putty matrix created from the the retraction cord in place. diagnostic wax-up.

additive diagnostic wax-up is a criti- mented with the diagnostic matrix 0.5 mm in the cervical and 0.7 to 0.9 cal step in the biomimetic approach to produce better overall tooth form mm in the middle third.8 In order to to preservation of enamel, and the and contour. The patient was happy achieve the actual depth cut, the cli- clinician must be able to accurately with the new esthetic result and the nician needs to ensure that the shank relate this wax-up to the final tooth new incisal edge position, so the lo- of the diamond is resting directly preparations.6 A number of putty cal anesthetic was administered and on the resin matrix and not angled stents have been used to effect this depth cuts were placed in the incisal into the matrix, which would create but their use can be very time-con- and the cervical third of the matrix. a deeper depth cut than desired (Fig suming during the initial stages of If the patient is unsure about the 5). Once the depth cuts are created, the tooth preparation procedures. esthetic or phonetic changes made they are marked with pencil for easy The technique advocated by Magne with the diagnostic matrix, it can be identification (Fig 6). Any remain- and Gurel uses a diagnostic resin altered immediately or left in place ing resin material and the minimal matrix created from the diagnostic for a week or two and reevaluated. necessary surface enamel are effi- wax-up to preview the case prior ciently and quickly removed (Fig 7) to tooth preparation.5,7 After the with larger round-ended diamonds Considerable knowledge, patient approves the results of this such as the KS2 (Axis Dental). This understanding, and artistic skill mock-up, the resin matrix can be in porcelain layering techniques system of placing depth cuts into a used as the platform to create depth are prerequisites for creating the resin matrix allows for the preser- cuts to guide the initial preparation ceramic veneer restorations. vation of the maximum volume of dimensions.5,7 healthy enamel and the creation of In this case, a Copyplast (Great an even thickness for the ceramic; In order to preserve the maxi- Lakes Orthodontics) stent was creat- this leads to less potential for post- mum amount of intact enamel, the ed from a duplicate die stone model bonding crack development in the incisal depth cut measured 0.7 mm 9 of the diagnostic wax-up using a porcelain veneer restoration. The and the cervical depth cut 0.4 mm. Biostar vacuum-forming machine preparations are then completed The depth cuts were created with an (Great Lakes Orthodontics). The pa- and checked with vertical and pala- 801-023SC (0.7-mm depth cut) and tient was not given local anesthesia tal putty stents created from the di- an 801-018SC (0.4-mm depth cut) prior to the mock-up creation, to al- agnostic wax-up (Figs 8–10). round diamond (Axis Dental; Cop- low for an accurate assessment of the The provisional restoration was pell, TX). A study by Ferrari and col- new incisal edge position for esthet- created on a duplicate Copyplast leagues, which looked at the thick- ics and phonetics (Fig 4). The teeth stent using an A1 shade of Protemp3 ness of dental enamel in maxillary were lengthened by 1.5 to 2.5 mm Garant (3M ESPE; St. Paul, MN) and anterior teeth, found that the enam- and missing facial enamel was aug- removed to adjust and trim. Particu- el thickness is approximately 0.3 to

Volume 22 • Number 3 Fall 2006 • The Journal of Cosmetic Dentistry 83 Clinical Science Phelan and Heindl

Figure 11: Diagnostic provisional restorations three Figure 12: Lateral view of the diagnostic provisional days after tooth preparations. Note the correction of restorations. Note the three planes to the facial the reverse smile and the tooth proportions. surface of the central incisors.

Figure 13: Incisal matrix generated by the model Figure 14: Refractory dies with marked preparations of the diagnostic provisional restoration, to ensure against incisal matrix. proper incisal edge position and length during the ceramic build-up.

lar attention was given to the embra- with the Kois Dento-Facial Analyz- The refractory die technique offers sure form, especially in the cervical, er (Panadent; Grand Terrace, CA). significant advantages over pressed so that a small space was created for The upper provisional model was veneers. Extremely sophisticated ef- the tissue and papilla to rebound mounted on the Sam 3 articulator, fects of color and translucency can after the preparation, retraction, the remaining models were cross- be achieved through a full-thickness and impression procedures. The mounted to the upper provisional layering technique, resulting in high- provisional was spot-etched with a model, and the case was sent to the ly esthetic and vital restorations.10 small amount of Ultra-Etch (Ultra- dental ceramist. Also, discolorations of underlying dent; South Jordan, UT) phosphoric tooth substrate can be effectively acid solution in the incisal third masked with ultra-thin opacious Laboratory Procedures of the preparation, and luted into layers without compromising the The porcelain layering technique place with Neo-Temp resin cement esthetics. Considerable knowledge, presented here is specially designed (WaterPik Technologies; Ft. Collins, understanding, and artistic skills in for the use of fluorapatite leucite CO). The provisional restorations porcelain layering techniques are glass-ceramic material (d.SIGN, Ivo- were evaluated a few days after the prerequisites for creating the ceramic clar Vivadent; Amherst, NY) for di- preparation appointment (Figs 11 & veneer restorations discussed here. rect application on refractory dies. 12) and a new facebow was created

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Figure 15: Deep dentin layer to smooth the transition Figure 16: Dentin build-up carried out with three between the incisal edge of the preparation and the different types of dentins to enhance vitality. incisal porcelain.

Figure 17: Enamel covering with a combination of Figure 18: First dentin enamel bake, indicating translucent and opalescent powders to mimic proper incisal edge position and length. natural enamel.

After the refractory dies have been is to be rebuilt, it is advisable to the palatal aspect of the unprepared degassed, margin material is applied carry out a separate vacuum bake be- tooth surfaces. Subsequently, the ve- in a thin layer up to the margins and fore starting with the dentin/enamel neers were built up to full contour fired. This layer provides a secure layering. with dentin layers of different values bond between the refractory die It is extremely important to main- and degrees of translucency (Fig 16). and the subsequent porcelain layers tain control during all stages of the For instance, a dentin layer blended (Fig 13). The porcelain stratification porcelain stratification by using the with a chroma-intensive enamel begins with deep dentin, placed on matrices generated from the cast of layer was used on the cervical area, the facial aspect of the prepared ve- the diagnostic provisional restora- thus creating a pleasing chromatic neer and also interproximally and tion (Fig 15). The incisal matrix is effect on the cervical area of the ve- incisally (Fig 14). This dentin layer, very useful during the build-up by neer restorations. The incisal matrix with slightly more opacity, prevents raising the incisal guide pin around was used to establish proper incisal excessive light absorption and also 1 mm before porcelain firing. A length and edge position prior to helps to smooth the transition from palatal matrix, however, is more re- cutback, for internal characteriza- incisal edge of the prepared tooth to liable for designing the incisal edge tions and the enamel covering. the porcelain. In cases where more and incisal embrasures since the In contrast to other ceramic ma- than 3 mm of the incisal length precise fit can easily be ensured on terials, the dentin of the d.SIGN

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Figure 19: Coating of the entire surface with silver Figure 20: Definitive porcelain veneer restorations on powder for better assessment of symmetry and surface the solid cast. texture and morphology.

system is so translucent that it is helpful to coat the surface with sil- and the tooth preparations were possible to apply internal effects ver powder for better assessment of pumiced and cleaned. The restora- and characterizations directly onto contours and surface morphology of tions were tried in individually to the reduced dentin body.11 The den- the restorations (Fig 19). inspect the fit and then were tried in tin lobes were enhanced slightly by A combination of thermo-glaz- collectively to evaluate the contact using ivory and cream-colored in- ing and mechanical polishing was areas. The veneers were then tried in tensives and feathered out toward utilized to mimic the desired natural with Prevue try-in gel (Cosmedent; the incisal edge with a brush tip. surface luster of the patient’s natu- Chicago, IL), and the patient ap- No stains should be used for this ral dentition. The solid cast allows proved the esthetics of the case. The purpose (they have the tendency a proper assessment of the gingival veneers were then luted into place to appear as a single layer and not contours and the closure of the gin- two at a time using the standard three-dimensional like the intensive gival embrasures of the restorations bonding protocol with OptiBond FL powders with defined volume as (Fig 20). At this stage, small correc- adhesive (Kerr; Orange, CA) and In- used for this case). For the enamel tions can be made only with low-fus- sure resin cement (Cosmedent). The covering the entire facial surface, ing material. The interproximal con- veneers were polished and the occlu- a combination of translucent and tacts were made shim stock-ready sion was checked and adjusted using opalescent powders are overlayed before delivery to the clinician red and black AccuFilm articulating specially to simulate shaded enamel paper (Parkell; Edgewood, NY) and (Fig 17). the T-Scan II system (Tekscan Inc.; The system requires the ceramist At this stage the volume of the Boston, MA). to fabricate the porcelain veneer build-up should be slightly high, es- restorations with a homogeneous pecially toward the incisal, in order thickness of ceramic that has a Conclusion to compensate for the anticipated favorable configuration to the The ultimate goals for an esthetic baking shrinkage. After the first den- luting composite thickness. rehabilitation are the biomimetic tin/enamel bake, the incisal edge recovery of the tooth, as well as the should fit into the matrix with the esthetic enhancement of the smile. incisal guide pin at the 0 position These goals can be achieved by fol- (Fig 18). A subsequent correction Adhesive Luting and lowing a minimally invasive prepara- bake is necessary to optimize form Finishing of the Case tion protocol guided by the additive and contours. The case was received from the diagnostic wax-up, diagnostic ma- Final contouring and surface tex- ceramist and inspected on the solid trix, and the diagnostic provisional. turing were carried out using various and die models (Fig 20). The pro- With this system, the clinician has diamond burs and green stones. It is visional restorations were removed the ability to limit the majority of

Volume 22 • Number 3 Fall 2006 • The Journal of Cosmetic Dentistry 87 Clinical Science Phelan and Heindl

Figure 21: Final esthetic and biomimetic Figure 22: Macro view of the final layered feldspathic rehabilitation for the patient with conservative bonded porcelain restorations. Note the improved porcelain veneers. Note the correction of the length and proportions of the central incisors. reverse smile line.

the veneer preparation to enamel 4. Magne P, Douglas WH. Porcelain veneers: and minimize the potential for sig- Dentin bonding optimization and biomi- metic recovery of the crown. Int J Prostho- nificant dentin exposures. It should dont 12(2):111-121, 1999. also be stressed that the system re- 5. Magne P, Belser UC. Novel porcelain lami- quires the ceramist to fabricate the nate preparation approach driven by a porcelain veneer restorations with a diagnostic mock-up. J Esthet Rest Dent Keep In Touch 16(1):7-16, 2004. homogeneous thickness of ceramic 6. Magne P, Douglas WH. Additive contour of We want to keep you that has a favorable configuration porcelain veneers: A key element in enam- informed! to the luting composite thickness. el preservation, adhesion, and esthetics for If you recently moved, please The potential for crack propagation aging dentition. J Adhes Dent 1(1):81-92, 1999. send us your new contact within the porcelain restorations 7. Gurel G. The Science and Art of Porcelain may be significantly reduced with a information so we can ensure Laminate Veneers. Hanover Park, IL: Quin- prompt communication ceramic-to-luting composite thick- tessence Pub.; 2003; 242-288. 9 about AACD activities and ness ratio above 3. The dentist can 8. Ferrari M, Patroni S, Balleri P. Measurement also facilitate the ceramist’s work by of enamel thickness in relation to reduc- offerings. You can submit providing an excellent final impres- tion for etched laminate veneers. Int J Peri- your contact information to odont Rest Dent 12(5):407-413, 1992. sion and smooth preparations with [email protected]. 9. Magne P, Kwon KR, Belser UC, Hodges JS, rounded contours and the absence Douglas WH. Crack propensity of porce- of any undercuts.9 lain laminate veneers: A simulated opera- tory evaluation. J Prosthet Dent 81(3): 327- References 334, 1999. 1. Magne P, Douglas WH. Rationalization of 10. Magne P, Belser U. Bonded Porcelain esthetic restorative dentistry based on bio- Restorations in the Anterior Dentition. mimetics. J Esthet Dent 11(1):5-15, 1999. Hanover Park, IL: Quintessence Pub; 2002; 294-331. 2. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6- to 12-year 11. Morr T, Heindl H. A systematic approach clinical evaluation—A retrospective study. to predictable esthetics using porcelain Int J Perio Rest Dent 25(1):9-17, 2005. veneers. Quint Dent Tech 27:43-57, 2004. 3.Friedman MJ. A 15-year review of porce- lain veneer failure: A clinician’s observa- ______tions. Compendium of Cont Ed 19:625-636, v 1998.

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