Developing an Inhouse Lab With
BelleGlass HP

Cincinnati Ohio Dentist: Thomas K. Hedge D.D.S., F.A.C.E.
Dentistry Today
June 1999

I have been restoring teeth for the last three years using laboratory-fabricated inlays, onlays, crowns and veneers with the new bonded systems such as Targis/Vectris, Sculpture Fibrekor, Empress, OPC, Concept and belleGlass. The results have been quite remarkable with respect to fit, esthetics, and conservatism. I have always felt that there must be a more efficient method to deliver these restorations other than making an impression and sending it to the lab for fabrication. If we could make the restoration at the preparation visit, we could save the patient a second visit, avoid the need to make a provisional restoration, eliminate a lab bill, and decrease overhead by freeing the chair time for the second visit.

My first attempt was to explore the possibility of using the CEREC II CAD/CAM milling device. I took my staff to two training courses at the office of an experienced CEREC practitioner. On the ride home we concluded that the CEREC machine was a tremendous technology, but we didn't feel that the esthetics and fit were as good as our lab fabricated inlays and onlays. Kelly Dental, our lab, does a phenomenal job of providing beautiful restorations that fit "as good as gold".

Recently, I came across an ad in Lab Management Today offering a two day course for lab technicians on the belleGlass HP system. My interest in Belleglass has been a result of hearing Gordon Christianson and Karl Leinfelder speak very highly about this restorative material at their current lectures. I called Kerr and explained that I was a dentist and was interested in taking the course. It was explained to me that I was welcome and that a number of dentists have taken the course. The belleGlass System costs under $5000. The CEREC II System is in excess of $80,000.

I had three motives for taking the course. First, I figured that every time I prepared an indirect restoration, my assistants fabricate a provisional restoration that has most of the qualities of the final restoration. What if we could go ahead and make the final restoration in a short period of time while the patient relaxes in the reception area? My second motive was to see if we could perform shade modifications and characterizations at the cementation visit. My third motive was to figure out just how the lab gets those restorations so smooth and polished. It seemed that no matter how hard we tried, that we could never achieve the lab delivered beauty after adjustments to occlusion and contacts.

Patty, my assistant, and I traveled to Columbus, Ohio to participate in the course offered at the Columbus Institute for Cosmetic Dentistry, owned and operated by Moshe Mizrachi. The facility is beautiful and is an incredible learning environment and has hosted courses with Frank Spear, Gerard Chiche, Karl Leinfelder etc. The morning began with a lecture by Mr. Mizrachi explaining his frustration with the problems associated with traditional gold and porcelain, mainly the lack of esthetics with gold and the wear to opposing tooth structure with porcelain.

He went on to explain the benefits of processed composite resins used in place of gold and porcelain. We first experimented at fabricating a veneer, inlay and onlay. We were instructed on how to prepare the die and how to layer opacious and translucent dentin, enamel, and add characterizations to the restorations. Patty fabricated a nearly perfect MOD inlay in twenty minutes. Patty is no ordinary dental assistant. In the State of Ohio, we have certified expanded duty assistants who can place restorations. She does beautiful work intraorally with direct composites and therefore has had a great deal of experience in working with composites. Still - twenty minutes! Our lab bill would have been $150 for this restoration. Mr. Misrachi explained to us that the material cost for this restoration is about four dollars. A Targis/Vectris unit costs about $40. This made me wonder why the lab bills for these two restorations are about the same. Of course you have to amortize the equipment expense to each unit fabricated, but I think that you can see the potential overhead savings. Remakes due to shade selection could be eliminated because you could do a rough mock-up right on the tooth. The wasted material is very inexpensive.

Research has shown belleGlass to be excellent with respect to wear, biocompatibility, strength, fit and esthetics. The wear rate of belleGlass has been shown to be 1.3 microns per year. Fracture resistance is greater than Targis/Vectris. Dimensional accuracy is rated at 2% shrinkage versus Targis/Vectris at 3%.

Belleglass restorations are made, by stacking various layers of the composite Belleglass Dual Cure over a die coated with rubber sep. Each layer is stabilized with a curing light before final processing in a heat and nitrogen atmosphere. It is interesting to note that this composite is designed to be stacked like porcelain and will stay put when placed. It is unlike the composite dentists are accustomed to using intraorally. Subtle irregularities placed on facial surfaces do not melt back into the smooth surface. It seems that this system, designed with lab technicians in mind is more oriented to placing the anatomy with composite placement instruments than with hand pieces after curing as most dentists are accustomed to.

This is fine, but it will take some getting used to.After the restoration is completed, it is placed in the processor where is processed for ten or twenty minutes at 140 degrees Celcius and 80 psi in a nitrogen environment. The time required depends on the size of the restoration. A 98 % conversion of monomer to polymer is achieved in the process which accounts for it's very low wear rate. When the restoration is retrieved from the oven, it is frosty white opaque in appearance. After finishing and polishing it is lustrous and beautiful.

Immediately upon returning to my practice on Monday morning, I ordered a Belleglass laboratory system. After spending the afternoon setting up the equipment, between patients, I was ready to go the next day.

The next day, I prepared two inlays on my partner, an occlusal and a MO inlay on tooth numbers 30 and 31. The final restorations appear in figure 1. These restorations were delivered the next day. Both fit perfectly with minimal adjustment. The esthetic results were quite good.

The following Monday, I prepared the MO inlay on tooth number 3 seen in figure 2 and 3 prior to preparation. The amalgam was removed with a 331 carbide bur, and the final preparation was shaped with a Brassler molar inlay bur, as seen in Figure 4. A narrow soft tissue trough was created using a needle electrosurgery tip in lieu of retraction cord. The final impression was made with Permadyne Garant as seen in Figure 5. Permadyne Garant is a poly-ether impression material, and requires two hours to de-gas prior to pouring. The impression was poured in Silky Rock and allowed to set overnight.

A model was prepared by grinding the base flat on a model trimmer. A die saw was utilized to cut between the prepared tooth, and tooth number 4 mesial to the margin. This cut was only made half way through the model. The cut was then broken with finger pressure, to allow the two sides of the model to be re-approximated, as see in Figure 6. The margin was ditched to allow for finishing to proper contour.

The restoration was built with three layers, A2 Opacious Dentin, A2 Translucent, and finally Cuspal Enamel over the top and out to all of the margins. After curing in the processor for ten minutes, minimal recontouring, and polishing was performed. A final polish was not attempted because final adjustment would be made in the mouth with subsequent polish. How many times can we recall having a beautiful restoration returned from the lab, that after adjustment has little anatomy remaining and requires repolishing. Why not polish after intraoral adjustment? The final restoration prior to baking appears in figure 7.

The final restoration was cemented after sand blasting the internal aspects. The Variolink II resin dual cure cement kit was used. The final restoration can be seen in Figures 8 and 9. Preparation and temporization required twenty minutes, fabrication required 25 minutes and seating required twenty minutes. This entire procedure could be completed on one visit in approximately one hour.

Let's examine the economics of this procedure. Traditionally, we would use one and a half hours of chair time, two visits, and incur a laboratory bill of at least $100. This procedure could be completed in one hour with one visit and four dollars in material cost utilizing this technique. Interim visits to re-cement the provisional restoration would not occur. There would be no cost for provisional materials. The patient would only have to visit your office once, and receive only one injection of local anesthetic.

Let's assume the chairtime is billable at $300 per hour. The one-half hour savings is worth $150 plus the $100 laboratory bill. Profitability increases by $250 on this one hour procedure. This is in addition to the profitability of the traditional technique.

The average fee for this procedure is $450. At one and one half hours of chairtime, this amounts to $300 per hour of production. With a 60% overhead and a $100 lab bill, this amounts to a profit of $180. Utilizing the technique outlined in this article, production amounts to $450 per hour with no lab bill. The same overhead level would amount to a profit of $270. The kicker is that this $270 profit was generated in only one hour while the $180 profit required one and a half hours, diminishing it's relative value to $120 per hour. The profitability is over twice as much.

Obviously, we need to factor in the cost of the laboratory equipment, but I think that it is quite clear that the payoff would occur within a few months.

Let's now examine the quality of the restoration. The color blend should be perfect, because the doctor has the ability to do a mock-up of the restoration with the belleGlass HP material in the tooth. The doctor will trim his or her own margin, insuring an accurate impression and marginal interpretation. Finally, the polish is performed to a mirror like finish after adjustment.

Ultimately the patient benefits in the quality of the restoration, the decreased chair time, and the ability of the restoration to be placed in one visit to the dentist.

I think that we are all guilty of placing a direct restoration when we know that it is a bit too large, and should have been done indirectly. Perhaps if it were easier to perform, and could be done in one visit, we would perform more indirect procedures.

The Belleglass laboratory system, although developed for the commercial dental laboratory, is very appropriate for the restorative dental practice. The technique and materials used are very "dentist friendly" given our skills in sculpting composite and knowledge of contour, occlusion, color, translucency and preparation design. This technique is ideal for inlays and applications to fabricate veneers, onlays, crowns and bridges are not difficult with some experience.

One final comment I must make is that this system has enhanced my staff's enthusiasm about our practice. We are all very excited about this new technology and this spills over to our patients, further enhancing our cutting edge perception by our patients.

One final note. My wife just read this article and asked me if I should note that I am not being paid by Kerr to write this article. My comment to you my reader is that this enthusiasm is genuinely sincere.

I have never understood why laboratories take two weeks to fabricate a restoration when Ford can make a car in a day. In addition to fabricating and seating many restorations on the preparation visit, I imagine that we can seat the rest of the restorations in a couple of days. This is a tremendous benefit to the patient.