Written by Jason Smithson, BDS (Lond) Friday, 13 January 2012 16:24
Direct composite resin placement in the posterior dentition has become a common day-to-day treatment modality for the majority of general dentists practicing in the United States today: indeed, more than two thirds of direct restorations currently being placed in the United States are composite resin.1,2 However, changing patient demographics and technological advances will lead to higher patient expectations and greater and greater demands for oral healthcare in the 21st century.3 Today's patients are more conscious of aesthetics than ever before. Led by much coverage in the media, they expect and demand the best cosmetic results within shorter time frames and at increasingly competitive fees.
Many protocols for direct posterior resin placement utilize complex oblique layering techniques with multiple shades of composite resin and numerous instruments. This is typically followed by a finishing and polishing sequence, which is equal in complexity.1 The net result is a time-consuming procedure, which gives an aesthetic outcome that is unpredictable in all but the most skilled of hands.
The author is presenting a case report supplemented with selected typodont procedural images that will share a simple and predictable technique ("The Simplified Concept") that will allow the average practitioner to produce lifelike Class I and II restorations. Using this technique will ensure the creation of ideal interproximal contacts and also require very little occlusal adjustment and almost no polishing. All of this will be achieved in an acceptable timeframe for the busy general practitioner using only 2 instruments: an Ash No. 6 Probe (Claudius Ash) (Figure 1) and a microbrush (Microbrush) (Figure 2).
Diagnosis and Treatment Planning
A 25-year-old female patient presented to our office with symptoms related to a recently placed composite resin restoration in the lower right first molar (tooth No. 19). She complained of intermittent sensitivity to cold and sweet which was poorly localized (no radiation of the pain), sharp in nature, and not lingering. The symptoms had been present since the restoration had been placed some 8 months previously, and were steadily becoming worse.
|Figure 1. Ash No. 6 Probe (Claudius Ash).||Figure 2. Microbrush (Microbrush).|
|Figure 3. Failing Class II distal occlusal composite resin in lower first molar.|
Upon examination, a Class II distal occlusal composite resin restoration was present. It had obvious breakdown of the margins and caries (Figure 3). The tooth was not tender to pressure and it tested vital to electronic pulp testing. The contour of the existing restoration was poor and, in addition, there was visible discolored tooth structure "shining" through the restoration at the distal aspect. All periodontal probing depths were 2.0 mm or less. Radiographic examination, in conjunction with the clinical findings, led to a diagnosis of bond failure and subsequent secondary caries.
The patient was scheduled for replacement of the restoration with a direct Class II composite resin. The "Simplified Concept" would be utilized as the technique of choice. The adjacent virgin second premolar was observed to have strong milky white translucent enamel effects alongside dentin with yellow-red hue and fairly high chroma; in view of this, a bichromatic (2 shade) approach using separate dentin and enamel composites augmented with appropriate tints was chosen.
The tooth was isolated on a quadrant basis with latex-free rubber dam (Roeko), Wave Wedges (Triodent), and Rubber Dam Caulking (Ultradent Products) (Figure 4). Next, the existing restoration was removed with high- speed pear-shaped diamond burs (ISO 830-010 [KOMET USA]) (Figure 5). At this point, secondary caries was noted globally throughout the cavity. Further caries removal was cautiously achieved with steel rosehead burs (SS White Round sizes 3,7, and 10 [SS White Burs]) in a slow handpiece and verified with Caries Indicator Dye (Henry Schein), the internal line angles were rounded out in a conservative manner with a dome-ended inlay bur4 (ISO 959-018 [KOMET USA]), and peripheral margins were beveled with a fine flame diamond bur5 (ISO 862-010 [KOMET USA]), and the cavity sandblasted (Figure 6) with 27 µm alumina (Micro-Etcher [Danville Materials]) to remove residual biofilm.6 Dentin discoloration with a green-gray hue remained visible in the distal box: this was attributed to corrosion products from an amalgam restoration, which preceded the composite resin.
|Figure 4. Rubber dam isolation.||Figure 5. Restoration removed, visible caries distally and midlingual.|
|Figure 6. Caries-free, with visible staining in the distal.|
A green regular-sized V3 matrix with a 4.5-mm matrix band (Triodent) was placed and burnished lightly with a cotton pledget in locking tweezers to create a contact point (Figure 7). The author prefers sectional matrix bands for direct composite resin placement because they produce a firmer, more predictable proximal contact point7 with a more anatomical contour and favorable emergence profile. Burnishing with a cotton pledget, rather than a metal instrument, avoids scarring the soft metal matrix, which would otherwise result in rough composite resin at the contact point. The matrix was secured with a purple (large) Wave Wedge (Triodent). If the wedge fails to seal the gap between the gingival margin of the proximal box and the matrix band, Polytetrafluoroethylene (Teflon) plumbers' tape (Home Depot) can be packed interproximally to ensure a perfect marginal seal. (Note: This was not necessary in this case.)
|Figure 7. V3 Matrix (Triodent) applied.|
The tooth was etched with 37.5% phosphoric acid gel (EnamelEtch [Cosmedent]) and a fourth-generation bonding agent placed (Optibond Fl [Kerr]) using the "Wet Bonding Technique."8
The Role of Opaque
Since the distal box of the cavity was fairly shallow, the author had some concerns regarding potential "shine through" of the gray discoloration and the consequent effects on the aesthetics of the final restoration. In view of this, an opaque to block out the undesirable underlying shade was selected. The opaque selected was A3 Creative Color (Cosmedent) mixed in a ratio of 5:1 with Pink Opaque (Cosmedent). The pink is at the opposite end of the color spectrum from the gray discoloration and serves a dual function by blocking out the underlying undesirable color while also giving some "red-shift" to more closely mimic the dentin shade. The A3 and Pink Opaque were mixed in the well of a Resin Keeper (Cosmedent) with a No. 1 brush (Cosmedent) and then applied in 3 thin layers, polymerizing the composite between each layer for 10 seconds (Figure 8). The author likes the Renamel Creative Color Opaque (Cosmedent because they come in 13 shades, covering the whole of the VITA shade system; subtle variations can be made to the shade by adding in either white or pink. In addition, the Creative Color Opaque can be applied in very thin section, which is especially useful when space for restorative material is at a premium.
The Resin Buildup
Initially, a thin layer (less than 1.0 mm) of Renamel Flowable Microhybrid (Cosmedent) was placed in the base of the cavity and adapted to the cavity walls with an Ash No. 6 Probe. Care should be taken to avoid the margins of the cavity preparation, especially when the margins of the proximal box are in dentin and/or cementum.9 The flowable composite gives improved adaptation to the cavity walls as a result of its reduced viscosity, and rounds out the internal line angles leading to dereased stress concentration during the polymerization of the following composite layers. In addition, the flowable composite acts by increasing the tensile resistance of the adhesive layer of the Optibond Fl bonding agent; this allows it to better withstand the tensile forces which are generated by the polymerization shrinkage of the overlying restorative composite. This layer is polymerized for 30 seconds so that the flowable layer achieves a high modulus before the restorative composite is placed.
The composite resin (Renamel Nano [Cosmedent]) shade IL (Incisal Light) was selected for this case to mimic the high value semitranslucent enamel, and Cosmedent Renamel Nano shade A3 for the dentin. The shade selected for the dentin buildup was deliberately 2 shades darker than the actual overall VITA shade of the tooth. This meant that the higher chroma of the dentin shade composite would be visible through the thinner enamel shade at the center of the occlusal table, giving the "warmer" effect, which is visible in the adjacent virgin second premolar.
The author chooses to heat the dentin shades using an Ease-It Composite Heater (Ronvig) to improve the physical characteristics (ie, increased modulus of elasticity and flexural strength10), but mainly to decrease the viscosity, which improves the adaptation of the composite resin to the cavity walls. The occlusal enamel shades are not heated because the author prefers the stiffer handling of the nonheated composite for more precise layering effects to allow him to mimic detailed cuspal forms.
|Figure 8. Creative Color Opaque (Cosmedent) applied to mask staining.||Figure 9. Cosmedent Renamel Nano (Cosmedent) arranged on Ease-It Composite Heater (Ronvig).|
|Figure 10. Pick up of resin increments.||Figure 11. Resin carried on Ash No. 6 Probe.|
|Figure 12. Application of resin to cavity.||Figure 13. Condensation of resin with microbrush.|
|Figure 14. Typodont demonstration model: applying resin with an Ash No. 6 Probe.||Figure 15. Typodont demonstration model: |
condensing the resin with a microbrush.
The resin was first laid out in 2 mm x one mm increments on the composite heater (Figure 9), the resin was then picked up with the Ash No. 6 Probe (Figure 10), and carried to the tooth (Figure 11). Because the resin heater is Teflon coated and the Ash No. 6 Probe is surgical steel, the increment of composite should be very easy to pick up. The distal contact was then rebuilt in 2 separate increments. This stage is demonstrated on a typodont model: the increment of composite is placed at the mesiolingual (ML) line angle (Figure 12). Since the tooth has a large surface area and is coated in bonding agent and the Ash No. 6 Probe has a small surface area, as the probe is withdrawn, the composite increment will remain in the cavity. The assistant should wipe the probe with an alcohol wipe to remove any resin debris at this stage. The composite is then lightly condensed with a microbrush against the matrix band and ML line angle (Figure 13). Any excess is removed with the Ash No. 6 Probe prior to polymerizing. The mesiobuccal aspect of the proximal box was restored in an identical fashion thus converting the cavity into a Class I.
The Class I dentin layer was then restored in a similar fashion (also seen on a typodont): the Cosmedent Renamel Nano A3 shade was placed within the cavity with the Ash No. 6 Probe (Figure 14) and condensed with the microbrush (Figure 15). As the dentin anatomy is built up, the fissure pattern is defined with the Ash No. 6 Probe using the instrument in an up-and-down "sewing machine" type movement to minimize dragging and voids within the material (Figure 16). The dentin layer should be built out in a cusp-by-cusp basis; building one cusp at a time in oblique layers to reduce "C-Factor" and thus the stress imparted on the cavity by the effects of polymerization shrinkage.11 This is seen completed in Figure 17.
Tints were then placed at this stage to mimic the white hypocalcification and brown fissure staining effects, which were present within the adjacent natural teeth. Creative Color Dark Brown tint (Cosmedent) was selected for the fissure stain and Opaque White (Cosmedent) for the hypocalcification effects. The tints were placed within the well of the Resin Keeper and applied with an Ash No. 6 Probe and a Cosmedent No. 1 brush. The brown was applied first only to the main occlusal pits; the brush was then cleaned with Cosmedent Brush Cleaner before applying the Opaque White (Figure 18). The tints have fairly intense chroma and should be applied sparingly to avoid a "cartoonish" effect. Each tint is polymerized before applying the next to avoid the shades bleeding into each other. Any excess tint may be gently blotted away with a clean microbrush.
|Figure 16. Typodont demonstration model: defining fissure pattern with an Ash No. 6 Probe.||Figure 17. Dentin buildup.|
|Figure 18. Application of Tints (Creative Color [Cosmedent]).||Figure 19. No. 1 brush (Cosmedent).|
|Figure 20. No. 3 brush (Cosmedent).||Figure 21. Final restoration prior to finishing.|
|Figure 22. Final nanohybrid composite resin restoration.|
The enamel layers were then built up on a cusp-by-cusp sequence, in an identical way to the dentin, using the Renamel Nano IL. The cusps were applied with the Ash No. 6 Probe and condensed with the microbrush; further modeling can be achieved with the tip of the Ash No. 6 Probe. As an optional extra, a very smooth glossy surface can be achieved by adapting the composite by brushing from composite resin to tooth margin with a No. 1 (Figure 19) or No. 3 (Figure 20) brush (depending on the size of the increment) and "brush and sculpt." Brush and Sculpt (Cosmedent) is a 36%-filled colorless liquid resin that allows the dentist to smooth and manipulate the composite with no pullback. In addition, it contains no HEMA, so there is no long-term discoloration of the composite resin restoration.
Each cusp increment was polymerized for only 3 seconds as advocated by the "Pulse Activation" Technique.12 Pulse activation is suggested for the bonding to enamel (high modulus), but is not necessary for dentin (lower modulus) bonding. The theory is that the energy (from the curing light) is applied to the composite over time rather than all at once; this reduces the conversion rate, which results in decreased polymerization stresses.
When the enamel buildup was completed (Figure 21) there was very little excess composite other than a small amount of flash at the axial walls. This is very simple to remove using a No. 12 scalpel blade in a Bard-Parker handle to plane off the excess. A firm finger rest should be taken on the tooth for this manuver.
Next, the rubber dam was removed, and any occlusal adjustment carried out with a small round high-speed diamond under water spray. Occlusal adjustment tends to be fairly minimal with this technique, and if no adjustment is carried out, no polishing is required. Any areas that have been adjusted are then polished with one half inch FlexiDiscs (Cosmedent) (medium grit through to fine) on a mandrel. The author likes to cut 4 slashes in the discs from the edge to the center; this allows the disc to flex more, producing a more rounded and lifelike anatomical surface. Final polishing is achieved with PumicePlus (Vertex) on a Goat Hair Brush, followed by Enamelize Paste (Cosmedent) on a FlexiBuff Wheel (Cosmedent): this is a one-µm aluminium oxide paste that, in conjunction with the FlexiBuff, produces a very high luster. The Enamelize is very easy to wash away with a water spray. The restoration is then coated in KY Jelly (Johnson & Johnson) and postcured for 40 seconds to ensure optimal wear resistance.13 The procedure is then complete (Figure 22) and the patient dismissed.
The use of 2 simple instruments in this technique confers considerable advantages to the busy practitioner. These instruments are inexpensive and easy to obtain. However, the main advantage is one of efficiency: since the procedure involves only 2 instruments, 4-handed dentistry becomes intuitive and can be carried out without verbal communication or looking up (thereby reducing eye strain). This reduces stress and enhances the speed of the procedure resulting in increased profits and workflow, giving an overall "win-win" for the dentist, assistant, and patient alike.
- Smithson J. Posterior direct composite resins: Keeping it simple. ppdentistry.com/dental-clinical-articles/article/posterior-direct-composite-resins-keeping-it-simple. Accessed October 24, 2011.
- Christensen GJ. Should resin-based composite dominate restorative dentistry today? J Am Dent Assoc. 2010;141:1490-1493.
- Douglass CW, Sheets CG. Patients' expectations for oral health care in the 21st century. J Am Dent Assoc. 2000;131(suppl):3S-7S.
- Ben-Amar A, Metzger Z, Gontar G. Cavity design for class II composite restorations. J Prosthet Dent. 1987;58:5-8.
- Opdam NJ, Roeters JJ, Kuijs R, et al. Necessity of bevels for box only Class II composite restorations. J Prosthet Dent. 1998:80:274-279.
- Yazici AR, Kiremitçi A, Celik C, et al. A two-year clinical evaluation of pit and fissure sealants placed with and without air abrasion pretreatment in teenagers. J Am Dent Assoc. 2006;137:1401-1405.
- Loomans BA, Opdam NJ, Roeters FJ, et al. A comparison of proximal contacts of Class II resin composite restorations in vitro. Oper Dent. 2006;31:668-693.
- Kanca J III. Improving bond strength through acid etching of dentin and bonding to wet dentin surfaces. J Am Dent Assoc. 1992;123:35-43.
- Tredwin CJ, Stokes A, Moles DR. Influence of flowable liner and margin location on microleakage of conventional and packable class II resin composites. Oper Dent. 2005;30:32-38.
- Daronch M, Rueggeberg FA, De Goes MF. Monomer conversion of pre-heated composite. J Dent Res. 2005;84:663-667.
- Feilzer AJ, De Gee AJ, Davidson CL. Setting stress in composite resin in relation to configuration of the restoration. J Dent Res. 1987;66:1636-1639.
- Kanca J III, Suh BI. Pulse activation: reducing resin-based composite contraction stresses at the enamel cavosurface margins. Am J Dent. 1999;12:107-112.
- Simonsen RJ, Kanca J III. Surface hardness of posterior composite resins using supplemental polymerization after simulated occlusal adjustment. Quintessence Int. 1986;17:631-633.
Disclosure: Dr. Smithson is a paid lecturer for Cosmedent and Triodent.
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