Practical Posterior Composites Efficient Placement and Predictable Results

You will not find my office placing stain in the grooves of posterior composites with endodontic instruments, unless of course a patient asks for it. Seldom do we use more than two types of composite in a single posterior restoration, unless a patient presents a “buy a hybrid—get a microfill free” coupon. Certainly, we could use a dual-cure compomer for ensured set and fluoride release near the pulp, a flowable for the nooks and crannies and for shock absorption, a packable in the boxes to press those matrices tight, a hybrid to bulk fill for its ease of curing, a microhybrid for its strength and aesthetics, some composite stain under the surface for that “life-like” depth of color, a microfill on the surface for better wear and smoothness, all followed by an unfilled resin sealer for that bald-headed shiny look.

Respect must be given to those dentists who feel the conviction to do awesome staining and tertiary anatomy, but in many practices efficiency is a must while trying to maintain high patient care and stay as affordable as possible. We don’t have time to do fillings just to look good for a dental magazine photo. We have a practice in which one dentist has averaged 1,600 direct restorations a year for over 12 years. We charge $100 for a two-surface and $130 for a three-or-more surface posterior composite and, as are many dentists these days, we are so busy that efficiency and doing it right the first time are a must.

“You’d better learn how to do posterior composites because amalgam will be outlawed soon!” is the alarm sounded by some educators. This is usually followed by photos of an awesome MOD composite on a bicuspid with staining, five different types of composite used, tertiary anatomy, and a polish smoother than glass. Almost as good a tooth as God made. We usually aren’t told how long the restoration took to place, nor do we know what the fee was. Many of these restorations are awesome looking, but is the technique practical for a routine practice? How does a filling that takes twice as long as an amalgam, at three times the fees, and with potentially 10 times the headaches, act as the “amalgam replacement?”

Every lecturer seems to have the perfect way to achieve “great aesthetics and zero sensitivity.” Those same teachers claim to be the only ones who can correctly interpret the data from research studies. Certainly, our own clinical success is the real proving ground for us, and what works for me may or may not work in your hands. You hear frequently that a dentist took a course where the instructor claimed almost 100% success, only to have the same technique fail in his or her own practice. Why the difference?

Posterior composites are perhaps the greatest potential waste of time and money in a dental practice, yet they are the only direct restorations many of us place. The following are some of the most common problems associated with posterior composite placement: (1) lack of tight and predictable contacts, (2) postoperative sensitivity, and (3) time-consuming, inefficient placement and finishing.

This article presents a case in which the patient had two mandibular quadrants needing six posterior composite restorations. After anesthesia, total treatment time was only 50 minutes. Nothing about this case is earth shattering, the anatomy isn’t perfect, and neither is the shade, but the technique provides us a cost-effective treatment that is repeatable on a day-to-day basis in a busy practice.

CASE REPORT: A TWO-QUADRANT, SIX-RESTORATION CASE

Figure 1. Occlusal view of left side showing old amalgam fillings.	Figure 2. Pre-op lateral view.
Figure 3. Occlusal view of right side.	Figure 4. Pre-op lateral view.

This case is the kind most of us see every day in practice. There are six composites to do, each replacing amalgams with secondary and interproximal decay (Figures 1 through 4). In this case anesthetic was delivered with bilateral anesthesia blocks, and a rubber dam was placed. Proper isolation cannot be discounted. We use a rubber dam, or at least Denta-Pops (AmeraDent) and Dry Tips (Microcopy) as compromise isolation. A rubber dam certainly is best whenever possible, as it reduces the chance of contamination from saliva and the humidity from the patient’s breath.

Amalgam and gross decay were removed using a new 330 bur, which expedites amalgam removal plus reduces friction and heat buildup. I’m as cheap as the next guy, but spending $0.90 on a new 330 bur for multiple restorations is a money saver. It will cut faster and with less trauma than one you’ve been using since you were in dental school. Throw them away before they rust to the point that the head falls off, or before they catch a tooth on fire from friction.

Figure 5. Rubber dam placement, old alloy removed with 330 bur, gross decay extirpated, and caries indicator placed.	Figure 6. Decay removal and preps on left side. We do not chase anything discolored unless decay is definitely present or if close to the margin.

Figure 7. The right side after decay removal, 45° bevel placed on all margins.

Caries indicator should be applied at least twice, the second time after you think you have all the decay removed (Figure 5). Sable Seek (Ultradent) stains denatured collagen and is just another tool to ensure that the patient is getting the service they are paying for. Leaving decay can lead to sensitivity and restoration failure.¹ The best anatomy, color, finish, or wear is useless if we leave decay under the composite. Some arrogant practitioners who say, “I don’t need no stinking indicator” would be surprised at just how many times small areas of decay are highlighted by the indicator that otherwise would remain. Often, the indicator will show decay just under enamel that is easily missed; conversely, tooth structure can be preserved by confirming what may be healthy tooth even though it looks suspicious. Caries removal is accomplished with a No. 2 or No. 6 round bur on a wobble-free slow-speed handpiece (Figures 6  and 7).

Large 45º bevels, about 2 to 3 mm in width, are placed on all marginal surfaces for several reasons: to increase surface area of enamel at margins for the most predictable bonding; to provide transition for shade blending; to reduce the chances of ruining a margin upon finishing; and because most of the bonding systems work better on cut or prepared tooth structure.² Angles less than 45º will leave a thinner edge of composite that may fracture more readily.

PREDICTABLE CONTACTS

There are many ways to achieve tight and broad contacts, but using sectional matrices and rings are best for many situations. They offer consistency and predictability that other methods can’t rival. Garrison, Palodent, and Danville are systems we have used, but I greatly favor the newer Composi-Tight Gold System by Garrison Dental. The Garrison rings have small flanges on their ends to help secure them in place, reducing the risk that they will “fly off” the tooth. The Gold System has the same great flange as the old system and has the thicker, stronger tines as found in the Palodent system.

Figure 8. Adjacent contact restored simultaneously because of less than a 3-mm separation between prepared teeth. Garrison Gold matrices and ring placed along with a Flexiwedge.	Figure 9. At the same time, a clear Super Spool matrix is placed on the other side with wedges.

If there is more than 3 mm of space between adjacent teeth after prepping, contacts are much more predictable if one tooth is restored first. The contact is made by filling the other prep afterwards. We want to work fast, but repairing an open contact is a sure way to run behind on the schedule. In this case, one side had less than a 3-mm opening between the prepared teeth, therefore the contact was replaced on two teeth at once. Two Garrison Gold sectional matrices were placed in the right side along with a Flexi Wedge. The Flexi Wedges (Common Sense Dental) are awesome for use with rings because they are rubber and have some “give” to them. They are worked into the contact with a gentle up-and-down motion until snug, then the ring pushes on the wedge, which “flexes” while maintaining its position. Pushing on the wedge while placing the ring will keep the wedge and matrices from backing out (Figure 9).

On the other side, a clear Hawe Super Spool mylar full matrix was placed, as the center tooth was to be restored first. These matrices are contoured three dimensionally and are easy to place if the contacts are broken. Because they are clear, curing can take place through the matrix. It has also been reported that the interproximal composite cures harder when using a clear matrix over a metal band.3# The chances of excellent contacts are increased greatly when the center tooth of three adjacent preparations is restored first. If four teeth would have interproximal preparations in one quadrant, every other tooth would have been restored first, and the contacts made as the last two teeth are restored separately.

REDUCING SENSITIVITY

The future should see the demise of a separate etch step altogether. We can be saved from opening dentinal tubules, over etching, under etching, over drying, under-rinsing, and other potential problems. These types of materials have certainly decreased sensitivity with posterior composites so far in our office. Every bonding system has its own peculiar rules and regulations that need to be followed closely. We have used One-Up Bond (J. Morita) and Clearfil SE (Kuraray) as nonetched systems, and have had great success with them after a couple of years. We also still use dual-cure separate etch systems such as Cabrio (Discus) and Prime&Bond NT (DENTSPLY Caulk) for indirect restorations such as aesthetic posts or bonding crowns.

How often can we use the excuse, “I’ll just adjust your bite and you’ll be fine?” These materials get rid of several of the common reasons that may lead to sensitivity (see Table). Because the smear layer is not removed, we don’t leave open dentinal tubules, we don’t need to place a wetting agent or desensitizer, and we don’t have to worry about under etching the enamel while over etching the dentin. From an assisting point of view, we don’t have to rinse, so the assistant won’t suck up the wedge or knock the matrix or band loose.

Figure 10. One-Up Bond is mixed until orange, and two coats are applied and allowed to remain on the tooth for 20 to 30 seconds.

One-Up Bond (J. Morita) has worked very well for us, and was used in this case. The results have been very good so far, with almost no sensitivity and good margins at recall appointments. Besides, the colors are just plain cool. It is mixed until it turns pink, and is applied to a moist tooth for about 20 seconds on both sides at the same time (Figure 10), then cured until clear. The color changes help increase the chances that it is used properly. We must make sure that the material is applied within 30 seconds of mixing. If more than 30 seconds elapse, the phosphoric esters inside the self-etch components start neutralizing, and bond strengths go down. In other words, the pH won’t stay low long enough to etch properly. “Clumping” of the bonding agent occurs after it has been mixed too long, and should then be discarded and remixed. We thin it with gentle air because of its thickness, but overly aggressive air thinning will weaken the bond strengths significantly.⁴ One-Up Bond is cured until the bonding agent is clear.

EFFICIENT PLACEMENT AND FINISHING

Flowable composite is great to use on every restoration because of its ability to decrease voids and increase adaptation of the composite against the tooth.⁵ It must be remembered that flowable composites generally have the least amount of filler, the most shrinkage, and are the hardest to cure of the composites we use, and therefore they have the worst physical properties#.6 We want to use them to fill any areas of potential voids because of their increased adaptability to the prep walls, but we don’t want to use them on the most critical parts of the restoration, namely the margins.

Figure 11. A small amount of flowable is applied followed by viscous microhybrid. The materials are pulled towards the facial, and excess is wiped away.	Figure 12. Similarly, composite is applied to the other side. Curing takes place slowly and through the facial on both sides for 10 seconds, then 10 seconds from the occlusal.

Matrixx Flow (Discus) was placed on all floors, in line angles, and in all corners, but was not cured. A microhybrid, Point 4 (Kerr), was injected into the prep to fill about one fourth of the prepared volume (Figures 11 and 12). The hydrostatic pressure of the more viscous microhybrid will force the flowable out of the prep except for where it fills the very small places the larger particle hybrid can’t get into. It is pulled away from the margins toward the facial with a plastic instrument; the excess flowable is then wiped away.

There is controversy about the stresses created by fast curing, or the use of plasma arc lights.⁷ In my opinion, there is no way using a plasma arc light saves a practice many thousands of dollars a year as some have suggested. The high initial cost, coupled with how little we really pay our assistants (who do most of the curing), would necessitate research showing tremendous clinical advantages before we purchased another of these. Why take the chance when many researchers feel the high intensity may cause more tooth and restoration stresses?⁸

The first curing takes place for 10 seconds from the facial through the natural tooth structure. This has three major advantages over curing directly on the occlusal: the intensity of cure is lessened, as the enamel and dentin act as a “filter” before the light reaches the composite; the chances of reaching deeper parts of the composite are increased over occlusal curing alone; and any shrinkage that may happen toward the light will be directed toward the bonded walls of the restoration. The ring and sectional matrix system allow us to get the light to the interproximal, and give us a chance for deeper composite curing through the tooth. The assistant turns on the curing light as it is handed to the dentist, as the tip heads towards the facial of the tooth. This provides some initial curing at a weaker intensity as the tip is at a greater distance from the restoration, and 10 seconds per surface will set the composite initially without building up too much pulp-damaging heat.⁹

The flowable and microhybrid are added again and pulled toward the lingual, then cured for 10 seconds from the lingual in the same manner the facial. Care must be taken not to damage the margins by whacking them with the plastic instruments. We must treat the margins as being fragile before curing, perhaps gently afterwards too. The occlusal part of the restoration is added separately if the restoration is quite large (more than 4 mm wide or deep). Again, flowable is added every time the microhybrid is added, and the majority of the flowable is wiped from the restoration before curing for 10 seconds from the occlusal.

Stresses from curing are real and have to be dealt with.¹⁰ There are more questions than definitive answers at this point, and there are many varying concepts and opinions, but it just makes sense to do what we can to reduce the chances that curing and shrinkage stresses will have a negative impact on our restoration. “C-factor” refers to the configuration of the preparation, and the theory is that we try to create situations that give us the lowest factor possible when curing.¹¹ The fewer bonded surfaces to which we are curing at one time, the less stress we put on the tooth and margins. That explains why some of the smallest class I cavities give patients the most postoperative problems. We always try to cure towards one wall at a time if possible, and try to avoid the stresses of curing to all walls of a multi-walled preparation. When we pull composite towards the facial, we are curing towards that wall of the prep and basically take the lingual, mesial, and distal out of the equation.

There is some suspicion that curing fast may create more tooth stress, so let’s cure a little slower to make sure. There is doubt that curing over 3 or 4 mm deep into a composite results in a complete cure, so let’s cure in increments and/or use trans-enamel curing. There is evidence that heat buildup from intense curing lights over long periods of curing may build up enough heat to damage the pulp, so let’s cure only 10 seconds per surface before finishing, and then 10 to 20 seconds per surface after initial curing, while giving the tooth 10 seconds to cool in between surfaces. The curing stresses can be one of the causes of white lines around composite restorations. Other causes of white lines around the margins of composite restorations after placement include excessive finishing vibrations or heat, and placing composite on nonetched/bonded tooth structure.

Figure 13. The remainder of each is filled in the same manner as the composite is pulled toward and cured from the lingual. The marginal ridges are quickly shaped with a No. 8 round bur and the contacts flattened with a finish bur.	Figure 14. The matrices are applied to the neighboring teeth and the matrix is burnished well against the new restoration.

Rough shape is given with a No. 8 round bur on high speed (Figure 13). Special care must be given to the margins, which are basically left alone unless grossly overfilled, and the contacts are also smoothed and adjusted as needed before restoring the adjacent teeth. Matrices, wedges, and rings are applied to complete the other restorations. The metal matrices are always burnished to ensure a good contact (Figure 14). The remaining two teeth in this case were restored with the same protocol as the other teeth were. Sectional metal matrices were removed with Matheau locking forceps (Patterson), which also are used to hold the articulating paper when the bite is checked later.

Figure 15. Matrices are removed, curing is done again for 10 seconds per surface, and basic anatomy is applied with a No. 8 round flame-shaped finish bur.	Figure 16. Basic anatomy, no grooves so deep that cannot be polished.

Basic anatomical shaping was done with the same No. 8 round bur (Figures 15 and 16), which works well because it cuts very efficiently, easily installs basic grooves and pits, and can be moved facial or lingual without flipping the handpiece over. Always check that the restoration is dry before placing the sealer. Fluid on the tooth hides a large number of defects, as some dentists involved in teaching have discovered. You can have cracks in a filling, open margins, and even no contact, and have them suddenly “healed” by adding some water on the tooth. This may work in showing cases on the lecture tour, but it will not work to alleviate problems a patient may have with a restoration later.

Figure 17. Occlusion is checked and adjusted with a 7408 finish bur.	Figure 18. Check for broad contacts and smooth margins. Polishing is completed with rubber cups, points, and brushes.
Figure 19. Bonding agent is again applied to finished restoration to help ensure sealed surfaces.	Figure 20. Certainly not perfect, but efficient and very functional.

A thin-pointed finish bur was used to smooth the facial and lingual, then a bullet-shaped finish bur (7408) was used to adjust the occlusion and to finish shaping the occlusal surface. Polishing was done with wet Diamond Hybrid Polisher (D*Fine) points and cups. The occlusion was checked, the surfaces were polished with Hawe Occlubrushes (Kerr), and sealed with the same bonding agent used in the restorations (Figures 17 through 20).

SUMMARY

Certainly, we could spend more time matching shades, applying characterizations, placing secondary anatomy, and even finishing. However, if posterior composite restorations are to be a viable alternative to amalgam in appropriate cases, we must accomplish efficient and predictable placement so that fees for the two types of restorations are somewhat in line. Contact must be solid, sensitivity must be kept to a minimum, and placement and finishing must be fairly simple and organized. If the problems with posterior composites aren’t kept to a minimum, all of dentistry will suffer.

Our contacts are excellent most of the time, but occasionally we need to redo a “light” one. Our best estimate is that about one in 100 fillings that had no preoperative symptoms needed some postoperative care after restoring. Usually these complaints are corrected by occlusal adjustment, and very rarely by replacing the restoration.

We have not yet made a perfect restoration in our practice—we are still trying.

References

1. Miller MB. Reality. Houston, Tex: Reality Publishing; 2002;16:72-73.

2. Hoelscher DC, Gregory WA, Linger JB, Pink FE. Effect of light source position and bevel placement on facial margin adaptation of resin-based composite restorations. Amer J Dent. 2000,13:171-175.

3. Szep S, Frank H, Kenzel B, Gerhardt T. Comparative study of composite resin placement: centripetal buildup versus incremental technique. Pract Proced Esthet Dent. 2001;13:243-250.

4. Miller MB. Reality Now. Houston, Tex: Reality Publishing; 2002;3:3.

5. Chuang SF, Liu JK, Jin YT. Microleakage and internal voids in class II composite restorations with flowable composite linings. Oper Dent. 2001;26:193-200.

6. Bouschlicher MR, Rueggeberg FA. Effect of ramped light intensity on polymerization force and conversion in a photoactivated composite. J Esthetic Dent. 2000;12:328-339.

7. Yoshikawa T, Burrow MF, Tagami J. The effects of bonding system and light cuing method on reducing stress of different c-factor cavities. J Adhesive Dent. 2000;12:328-339.

8. Dennison JB, Yaman P, Seir R, Hamilton JC. Effect of variable light intensity on composite shrinkage. J Prosthetic Dent. 2000;84:499-505.

9. Porko C, Hietala EL. Pulpal temperature change with visible light curing. Oper Dent. 2001;26:181-185.

10. Terry DA. Restoring posterior teeth using a new low-shrinkage composite. Restorative Quarterly. 2002;5:1-5.

11. Hornbrook D. Dr. David Hornbrook interviews Dr. John Kanca. Dental Practice Report. 2002;4:38-44.

After completing a general practice residency, Dr. Griffin has maintained a general practice in Eureka, Mo in a practice that focuses on efficiency in almost all phases of general dentistry while providing state-of-the-art care for affordable fees. He enjoys teaching on practice efficiency and predictable posterior techniques, and is always willing to do courses for groups or to raise money for charity.