Direct Composites for Optimal Restorative Aesthetics

Transcription

1 Direct Composites for Optimal Restorative Aesthetics by Randall G. Cohen, DDS Private Practice Newtown, PA Dentaltown is pleased to offer you continuing. You can read the following CE article in the magazine and go online to to take the post-test and claim your CE credits, free-of-charge, or you can mail in your post-test for a nominal fee. See instructions on page 70. Educational objectives Upon completion of this course, participants should be able to achieve the following: Compare and contrast direct composite restorations with other dental materials such as cast gold and amalgam. Compare and contrast total-etching from self-etching. Understand the relevant qualities of a composite restorative material. Be able to place, contour, finish and polish beautiful composite resin restorations. Understand how the light diffusing capability of a composite enables monolayering. Patients are often interested in aesthetic dental restorations, and it is the clinician s challenge to accommodate them. Despite the advantages of cast gold (excellent durability, fit, and biologic compatibility) and dental amalgam (ease of placement and inexpensive) neither of these materials is of a natural tooth color and so their use compromises the aesthetic outcome. Cast porcelain is an aesthetic material, however its cost approximates that of cast gold, and its longevity when compared to cast gold is unknown since it is a relatively recent dental material. Accordingly, the use of a direct composite resin that simultaneously addresses the issues of a single visit procedure, costs, and aesthetics is a material that the clinician should consider. In this article, the author describes a simplified restorative technique termed, Incremental Monolayering made possible by the development of a new hybrid composite material. Approved PACE Program Provider FAGD/MAGD Credit 12/01/04 to 12/01/08 AGD PACE Approval Number: Dentaltown.com, Inc. is an AGD PACE Recognized Provider. This course offers two AGD PACE Continuing Education Credits free-of-charge. continued on page March 2008 dentaltown.com

2 continued from page 58 Transparency & Light Diffusion Transparency Sample on the paper Trial Product Competitor Light Diffusion Sample off the paper Boundary: Visible Visible Not Visible Visible Similar Transparency Light Diffusion: High Low Dental Adhesives and Permeability When bonding composite resins to dentin, the clinician deals with the consequences of the diffusion of substances and fluids through dentinal tubules to and from the pulp, termed dentin permeability. 1 This fluid movement within the tubules is frequently cited as the model by which pain transmission occurs, an important consideration in reducing post-operative sensitivity. 2 Following preparation with rotary instruments, a layer of debris forms on the cut dentin surface called the smear layer that occludes the dentinal tubules and reduces dentin permeability. Dentin adhesives will achieve a satisfactory bond to the cut dentin if one of the following two clinical conditions is met: 1. The smear layer is completely removed 2. The adhesive penetrates (without removing) the smear layer and modifies it so that it becomes an integral part of the hybrid zone. 3 Adhesives that work in the first way are called total-etch adhesives; utilizing a phosphoric acid pretreatment to remove the smear layer and demineralize the dentin to a depth between 5.0µm to 7.5µm. These kinds of bonding systems open up the dentin tubules, and the primer is then supposed to penetrate the demineralized dentin to create the hybrid zone. In reality, the primer does not penetrate to the full extent of the demineralized zone, thus leaving voids that can lead to postoperative sensitivity and reduced bond strength. Another difficulty with these products is that the acid etch leaves the collagen fiber component of dentin unsupported and susceptible to collapse when air dried, forming an impermeable organic layer. This collapsed protein layer prevents the adhesive resin from reaching the demineralized dentin and causes bond strength to plummet. Leaving a too-wet substrate is similarly problematic since the monomers will not remain dissolved in their solvents, thus forming microscopic water blisters and resin globules. Similarly, bond strength is negatively impacted. This total-etch bonding is known as technique sensitive since there is a relatively narrow window of substrate moisture content that will produce a successful bond. 4 Bonding systems that work in the second way are called self-etch adhesives because they simultaneously etch and prime the dentin substrate, so a phosphoric acid pre-treatment is not required. These self-etch adhesives do not remove the smear layer; rather they penetrate it and change it such that it becomes part of the hybrid zone. The self-etching adhesives monomer and water completely support the collagen fibrils during the entire bonding process, and the dentin, being completely mineralized, can be thoroughly dried prior to bonding. A uniformly dry substrate is much easier to establish than a uniformly wet one, so these self-etch resins are known as not being technique sensitive as a requirement for a successful outcome. The application of self-etching primers is a simplified one; a 20-second application that gets air dried, followed by the bonding resin and a 20-second light cure creates an excellent dentin or enamel bond to the restorative material used. Composite Resin Restorative Materials There are many physical properties that the clinician must consider when using direct composites to restore carious or fractured teeth. A composite must handle easily, possess adequate working time, and have good polishability in order to achieve the desired aesthetics. Its hardness, wear resistance and flexural strength needs to be similar to that of the natural tooth so that it will produce a restoration that lasts many years and provides good value to the patient. The newer composites also focus on the more subtle aesthetic capabilities of this class of materials. The transparency, shade match, the consistency of the shade following polymerization, and the material s ability to diffuse light comparable to continued on page March 2008 dentaltown.com

3 continued from page 60 enamel and dentin will enable the dentist to mask a dark background and replicate the lost tooth structure in a way that creates a nearly seamless restoration. Shade match is what accounts for the ability of the composite to mask a dark background. These composites are called hybrids since they are a combination of nano fillers (0.02µm) and sub micron glass fillers (0.7µm.). Different companies use different fillers, and the type and amount of filler used has profound implications in the material s ability to vanish within the preparation. Fig. 1 Fig. 2 Light Diffusing Composite Resin The clinician s goal in replicating the appearance of natural tooth structure is greatly facilitated by a composite resin restorative material that has the same ability as natural tooth structure to transmit and diffuse light. The hybrid composite that was utilized in these aesthetic cases contains pre-polymerized composite nano fillers, which impart the special light diffusing properties that so closely resemble the optical qualities of enamel and dentin, 4 as well as allow for a highly polishable surface 5 (the nano sized particles give it an improved polishability over previous composites). Graphic 1 demonstrates two composites that are the same in translucency, but different in terms of light diffusion. The product that is used in the following cases was able to mask out the line of demarcation when the samples are lifted from the testing paper such that the black and white backgrounds were indistinguishable from one another. Incremental Monolayering: A Simplified Clinical Procedure The clinician s objective is to create a restoration that is not only durable and biocompatible but highly aesthetic as well. To this end, some clinicians will use multiple composites of different shades in order to create an aesthetic result. In contrast to this time-consuming procedure, the author presents in the following examples a different technique called incremental monolayering. The demonstrated method of composite placement utilizes a singular composite resin material whose shade and light diffusing capabilities are similar to that of the tooth substrate (Clearfil Majesty Esthetic, Kuraray America, Inc.). This is required for incremental mono layering. Accordingly, this material enables the clinician to create durable restorations that are indistinguishable from the surrounding tooth structure. In each case, a highly filled, low-shrinkage flowable composite (Clearfil Majesty Flow, Kuraray America, Inc.) was placed as a liner prior to the application of the aesthetic composite material. This thin layer was placed in order to achieve better surface wetting and adaptation of the material to the cut dentin as well as to the matrix, and also to minimize the effects of polymerization shrinkage of the overlying composite. The liner flows better against the matrix and minimizes voids. The bonding material used was Clearfil Protect Bond (Kuraray America, Inc.), a sixth-generation, self-etching adhesive that contains an antibacterial and fluoride components. The antibacterial adhesive monomer has been shown to be effective in disinfecting the dentin surface, thus eliminating the need for multiple disinfecting scrubs prior to the bonding procedure. The fluoride component has been shown to stabilize the dentin-resin bond over time. Case #1: Deep Class I Restoration In this case, routine examination of this young female patient revealed caries in the occlusal aspect of tooth #31 [Fig. 1]. Following satisfactory anesthesia and isolation, an appropriate outline form of the restoration was created with a 330 bur and the dentin stained with Caries Detector Solution (Kuraray America, Inc.) [Fig. 2] to reveal the extent of the infected and affected dentin. Staining of the dentin in continued on page March 2008 dentaltown.com

4 continued from page 62 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. A Fig. B Fig. C this manner is more reliable than the tactile detection with an explorer, and should be done routinely as part of any restorative procedure. As there was substantial decay present, a wider preparation was created using a shoulder-former diamond (Pollard F62) with the deep caries removal done with the #4 round bur on a low speed handpiece under irrigation. Caries Detector Solution was periodically applied and rinsed, but the operator stopped the preparation before a pulp exposure would have occurred [Fig. 3]. In the opinion of this author as well as many others, it is preferable to leave a thin layer of affected dentin over the pulp in a restoration such as this one, rather than create a pulpal exposure that might likely cause pulpal degeneration and necrosis. As is evident in the photo, some Caries Detector Solution did remain in the thin affected dentin directly over the pulp prior to placement of the adhesive and composite. The preparation was cleaned thoroughly with a slurry of coarse pumice then rinsed. The self-etching material chosen, Clearfil Protect Bond, has an antibacterial component as part of its primer, and was applied directly to the deep dentin substrate, thus affording a measure of surface disinfection [Fig. 4]. After 20 seconds it was air-dried, then the bonding resin applied, air-thinned, then light cured for 20 seconds. The flowable composite was applied with a dispensing brush, and then light cured for 20 seconds. The single packable composite was monolayered along the walls of the preparation using a curved composite instrument (Karl Schumacher, Inc.) gradually reducing the prep s size and following the contours that were still intact. In this way, the restoration was made highly aesthetic as well as functional. When composites are placed in this way, there is minimal finishing and polishing to do. In this case the occlusion was checked, and the occlusal surface of the restoration was finished with a sharpened white rubber point (Dedeco) [Fig. 5], followed by coarse pumice, followed by a smooth polishing paste consisting of a slurry of calcium carbonate (Bon Ami Company) and water, creating the smooth anatomy evident in the completed restoration [Fig 6]. Case #2: Multiple Class II Restorations Here the patient presented with radiographic evidence of interproximal caries with no occlusal involvement [Fig. A]. The use of adhesive technology enabled the operator to remove caries and create proximal boxes in a conservative manner that avoided disrupting the majority of the occlusal surface of each of the teeth. A Tofflemyre matrix band and wooden wedges was applied to each tooth separately to retain control of the proximal contacts [Fig. B]. Following the recommended application of the self-etch primer and adhesive (Clearfil Protect Bond) and thin layer of flowable composite (Clearfil Majesty Flow) was deposited at the gingival margin and dispersed using a ball burnisher. This first layer was light cured (20 seconds), then followed with the packable composite (Clearfil Majesty Esthetic) that was contoured then light cured for the recommended 20 seconds. Finishing and polishing was minimized by this conservative approach that preserves tooth structure, simplifies the occlusal contacts, and eliminates the need to recreate the majority of the occlusal anatomy [Fig. C]. Case #3: Multiple Class III Restorations In this case, the patient presented with old composites that had recurrent caries and discoloration, wanting them to be replaced. The pre-treatment examination [Fig. 7] did not reveal any facial or proximal display of the old discolored restorations, and clearly the patient was interested in maintaining the existing appearance. Once satisfactory anesthesia and isolation was accomplished, the old composites continued on page March 2008 dentaltown.com

5 Case #4: Large Posterior Restoration This 47-year-old man came to the office for routine dental care, requiring restorative treatment for tooth #14. The old amalgam had recurrent caries and there was a fractured off buccal cusp [Fig. 12]. Initial cavity debridement was accomplished with a 330 carbide bur, followed by the shaping of the cavity with a shoulder-former diamond (Pollard F-62). Caries Detecting Solution was used to verify the full extent of the decay so that it could be removed carefully with a #4 round bur on the low-speed handpiece under irrigation. Friable enamel was removed with a minimal bevel, the preparation was cleansed thoroughly with a slurry of coarse pumice then rinsed and dried. The self-etching primer was applied (Clearfil Protect Bond) and dried after 20 seconds, followed by an application of the bonding resin. The preparation was lightly air-dried and light cured for 20 seconds using a standard halogen light. At this point, the highly filled flowable composite (Clearfil Majesty Flow) was applied to the dentin substrate in a thin layer using a ball burnisher [Fig. 13], followed by incremental monolayering of the aesthetic composite resin restorative material (Clearfil Majesty Esthetic). The increments were built from the periphery of the preparation circumferentially, using the cuspal inclines that were still intact to serve as a guide for establishing the occlusal anatomy of the restoration [Figs. 14, 15, 16]. The composite instrument used had a curved tip with a coating that prevented the material from sticking to it, which, in concert with the very workable consistency of the composite, afforded maximum control over this case. Once the material was added to the preparation and cured, the occlusion was checked, and the sharpened white rubber polishing point was used to polish the restoration. The final polish was achieved with coarse pumice followed by a high gloss achieved using a paste of Bon Ami and water [Fig. 17]. Although some clinicontinued from page 64 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 were removed and the outlines of the preparations were completed with 330 burs (TRI HAWK). Following the use of a dye to reveal caries (Caries Detecting Solution) the decay was found to extend through the facial aspects of teeth # s 7 and 8, thus increasing the aesthetic requirements of the restoration [Fig. 8]. Once the preparations were completed, a minimal bevel with a thin diamond was placed in order to remove unsupported enamel. The preparations were cleaned with a slurry of coarse pumice, then rinsed and dried. The simultaneous enamel and dentin conditioning was done with Clearfil Protect Bond primer, applied for 20 seconds then air-dried thoroughly. Next, the clear plastic mylar strips (EPITEX) were placed interproximally to avoid the unintentional bonding together of adjacent teeth. Next, the microfilled Protect Bond resin was applied, lightly aired, and then light cured for 20 seconds. A thin layer of Clearfil Majesty Flow was applied to the cut dentin surface from the composite syringe. It was then spread across the dentin surface using a small ball burnisher and light cured for 20 seconds. Next, a single shade of the packable material (shade A2 of Clearfil Majesty Esthetic) was dispensed via compules incrementally into the preparations, and contoured with a curved composite instrument (Karl Schumacher, Inc.). The plastic matrix was pulled facially across the preparation in order to establish the correct proximal contours [Fig. 9], and then light cured. Once the composite was fully polymerized, the minimal finishing was accomplished with Brasseler finishing burs, Sof-Lex (3M) disks, finishing strips (3M) and rubber points (Dedeco) [Fig. 10]. A high gloss was achieved with coarse pumice then the smooth polishing paste (Bon Ami, Bon Ami Company) resulting in undetectable restorations [Fig. 11]. continued on page March 2008 dentaltown.com

6 continued from page 66 cians create elaborate, stained secondary occlusal anatomy, using tiny endodontic files, this author has found that this detail work imparts little clinical benefit while extending chairtime significantly. Most importantly, however, patients simply do not want this kind of natural looking restoration and would prefer the clean appearance of the single shaded composite. Fig. 18 Fig. 19 Author s Bio Dr. Randall G. Cohen is in private practice of general, cosmetic and restorative dentistry in Bucks County, Pennsylvania, since his graduation from Temple University School of Dentistry in He has published papers in several journals and has lectured nationally on adhesive dentistry. Disclosure: Dr. Cohen declares having received an honorarium from Kuraray America, Inc., for this course. References 1. Pashley DH. Dynamics of the pulp-dentin complex. Crit Rev Biol Med 1996;7(2): Brannstrom M, Astrom A, The hydrodynamics of the dentine; its possible relationship to dental pain. Int Dent J 1972; 22: Pashley DH, Carvallo RM, Dentine permeability and dentine adhesion J Dent 1997; 25: Inokoshi S, Kataumi M, Yamada T, Tagami J, Yuasa S, Study on Optical Properties of tooth colored restoratives, Part IV: Effect of filler size on regular and diffuse transmissions trough resin composites containing spherical fillers. 15(27) O Brien WJ, Johnston WM, Fainian F, Lambert S, The surface roughness and gloss of composites. J Dent Res. 63(5) , 1984 This CE activity is supported by an unrestricted grant from Kuraray America. Case #5: Class IV Restorations to Close Diastemas This 15-year-old female had her orthodontic appliances removed that morning, in preparation for an implant (#10 area) and porcelain laminate veneers (#s 7, 8, and 9.) The patient was unhappy about the large diastema [Fig 18] that was left between her two front teeth while the implant integrated into the bone, so large Class IV composites were placed on the mesials of #8 and #9 until the anterior segment was ready for the final restoration. In this case, minimal preparation was necessary; only the roughening of the proximal enamel followed by a slurry of coarse pumice to prepare the teeth for the restoration. The bonding procedure onto the enamel was accomplished again with the self-etching Clearfil Protect Bond. The primer and bonding resin were applied in the same manner as described above. Then, the flowable composite was applied directly to the cut enamel surface followed by the monolayering of a single shade (A1) of aesthetic composite material to the mesials of #s 8 and 9. The material was applied incrementally and the restorations kept separate with a clear mylar strip that prevented the inadvertent bonding together of these large restorations. No attempt was made to cover the intrinsically stained enamel that will be addressed later with the porcelain laminate veneers, as the purpose of these restorations was only to provide temporary, yet aesthetic closure of the diastemas [Fig. 19]. Summary Composite restorations that are not only functional but also highly aesthetic are made routine by using a simplified application technique. This procedure is accomplished at four levels: 1. Effective caries removal and preparation. 2. Antibacterial self-etching bonding strategy. 3. Incremental Monolayering of the aesthetic composite restorative material. 4. Finishing and polishing of the completed restoration. The use of a dye to detect caries is central to effective caries removal and the appropriate cavity preparation. The bonding portion of the procedure utilizes an antibacterial self-etching adhesive that disinfects the dentin prior to creating the hybrid zone that is rapidly and predictably accomplished. The restorative material used is a special light-diffusing composite resin that handles easily and possesses the appropriate physical characteristics to the clinical requirement. In many cases it is no longer necessary to utilize multiple shades of composite resin to achieve the lifelike effect for which clinicians strive. The transition zone between tooth and composite, even with a through and through restoration is rendered invisible by using this kind of composite restorative material in concert with attention to detail in its application. When the Incremental Monolayering technique is done correctly, the polymerization shrinkage is minimized, the tooth anatomy is easier to carve, the light cure is more effective, and the finishing and polishing is done with a minimum number of procedural steps. With a predictable procedure such as this, aesthetic composite resin placement becomes more simplified, since multiple shades of the material are unnecessary to create the lifelike effect that patients demand. continued on page March 2008 dentaltown.com

7 continued from page 68 Post-test Answer the Post-test Questions Online for FREE You have two options to claim your CE credits: 1) Go online and answer the test for free or 2) answer the test on the Continuing Education Answer Sheet and submit it by mail or fax with a processing fee of $35. To take the test online: After reading the preceding article, type the following link into your browser and click the button TAKE EXAM: You can also view the course online in a Webcast format by clicking the above link and then the button REVIEW COURSE. If you choose that latter option, you can take the test by scrolling down and clicking I wish to claim my CE credits. Please note: If you are not already registered on you will be prompted to do so. Registration is fast, easy and of course, free. 1. Direct composites are often used more than cast gold in routine dental practice because: a. Lower materials cost b. Single visit restorations c. More aesthetic d. All of the above 2. Self etch adhesives differ from total etch adhesives in that: a. Self etching primers completely remove the smear layer. b. Post-operative sensitivity is more common in self etching adhesives. c. The adhesive monomer and water will condition the dentin without risking collapse of the organic portion of the dentin. d. A phosphoric acid pre-treatment is required. 3. The nano sized particles within the newer direct composites: a. Give the material improved polishability over earlier composites. b. Are about 0.7 µm in size. c. Reduce polymerization shrinkage. d. None of the above. 4. The following property of direct composite material is what accounts for its ability to mask a dark background: a. Shade match b. Light diffusion c. Surface gloss d. Transparency 5. The flowable composite is used as a liner under most composite resin restorations because: a. It improves the esthetics in posterior restorations. b. It is easily polishable. c. It contains an antibacterial component. d. It better wets the cut dentin surface, flows better against the matrix and mimimizes voids. 6. Advantages of conservative treatment of Class II carious lesions using adhesive dentistry are: a. Simplified management of the occlusal contacts. b. Not having to re-create the occlusal anatomy. c. Better preservation of tooth structure than what is afforded by a classic amalgam or gold prep design. d. All of the above. 7. The Mono-Layering of composite material: a. Involves using several different shaded composites to replicate the exact color of the surrounding tooth structure. b. Always shows a stark transition zone. c. Can be done if the material s light diffusion and shade are similar to that of the tooth. d. Should be done in bulk rather than in small increments in order to minimize the effects of polymerization shrinkage. 8. In the author s opinion, asymptomatic teeth with deep preparations that will receive composite restorations are best handled: a. By leaving some affected dentin over the pulp rather than risking an exposure. b. By initiating elective endodontics to avoid subsequent symptoms. c. By removing all dentin that stains with the caries detecting solution, irrespective as to whether the pulp will be breached. 9. A solution to detect caries: a. Shows infected and affected dentin. b. Is more reliable than relying on tactile detection with an explorer. c. Should be used routinely in restorative dentistry. d. All of the above. 10. Incremental building of composite restorations will: a. Minimize polymerization shrinkage. b. Afford better control of cuspal inclines and fossae. c. Maximize the effectiveness of the light cure process. d. All of the above. Legal Disclaimer: The CE provider uses reasonable care in selecting and providing content that is accurate. The CE provider, however, does not independently verify the content or materials. The CE provider does not represent that the instructional materials are error-free or that the content or materials are comprehensive. Any opinions expressed in the materials are those of the author of the materials and not the CE provider. Completing one or more continuing courses does not provide sufficient information to qualify participant as an expert in the field related to the course topic or in any specific technique or procedure. The instructional materials are intended to supplement, but are not a substitute for, the knowledge, expertise, skill and judgment of a trained healthcare professional. Licensure: Continuing credits issued for completion of online CE courses may not apply toward license renewal in all licensing jurisdictions. It is the responsibility of each registrant to verify the CE requirements of his/her licensing or regulatory agency. 70 March 2008 dentaltown.com