Conversation with Dr. Rella Christensen

By many reports and surveys, Zirconia is now the most popular, indirect restorative material. Despite its wide use, some dentists and laboratories still have questions regarding wear, longevity, hardness, removal, esthetics, etc. We recently consulted with Rella Christensen, PhD, Director of TRAC Research Provo, UT, on zirconia properties. TRAC Research is a 37-year-old, respected dental-materials testing company that, during the past few years, has placed an emphasis on in-vitro and in-vivo zirconia restoration studies, and will publish the three-year-findings in several months. Following our conversation, we became even more convinced that full-contour zirconia is the most viable material for posterior restoration. Monolithic zirconia has it all: high-strength, low-wear, softness, low-heat conductivity, and conservative preparation. 

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Dr. Christensen will be joining us in Cleveland, OH on April 11, 2014 for a complete materials update seminar. This will include the release of TRAC’s findings on zirconia and emax CAD, as well as announcements of other material options that are currently being tested. 

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Dr. Christensen did mention a few clinical cautions. Due to the difficulty in removal and endodontic access, she recommends following preparation and occlusal reduction parameters similar to full-cast restorations. Full zirconia should be seated using reinforced glass ionomers, and not bonded. When restorations are adjusted, it is recommended a high-shine polish be completed to ensure natural wear to the opposing teeth. And, if a crown must be removed, it should be addressed with a new, fine diamond, low-to-medium pressure, with lots of water allowing the diamond to do the work.

When asked what she would place in her own mouth, the immediate response was “absolutely full-contour zirconia, and yes I’m speaking about 1st and 2nd molars”.

Go Digital & Save Lab Fees

Did you know that when ROE receives a digital impression and the case can be designed model-free and monolithic, you receive a $20 discount? Model-free restorations are the future of indirect dentistry. They require less laboratory fabrication time and have the potential for less error. ROE accepts files from all digital impression scanners.

New ClearFrame Partial Dentures

If you are looking for a patient-pleasing, lightweight, metal-free, partial frame that is esthetic, relineable, adjustable, monomer-free, and affordable, you will want to try our new ClearFrame.

The chief complaint with thermoplastic partials is their future adaptability. Nearly all thermoplastic partials must be either jumped or remade if a patient loses a tooth or a denture tooth breaks free. This is not the case with ClearFrame since the frame mater-ial bonds to itself. Also, the pink material surrounding the teeth is conventional acrylic, so it can be repaired, relined and even accept implant components. The ClearFrame sub-structure is nylon thermoplastic and, be-cause of its extreme density, is very rigid, color stable and easy to adjust. Moreover, due to the material strength, rest seats can be incorporated!

As with all our ROE partial dentures, cases are accurately fabricated using CAD/CAM survey and design, which offers digital blockout and the elimination of refractory casts. All this amounts to well-fitting, repairable partial dentures.

Linear Shade Guide

If you’ve considered switching to Vita’s 3D shades, now is a good time. Vita’s new Linear Shade Guide includes the same shade tabs as the innovative 3D Master, yet the layout is more intuitive for the guide’s intended use…choosing value first. The Linear Guide includes a Valueguide for making the initial value choice. Once the value family is chosen, the chroma and hue are determined. The 3D Master has helped our clients with shade-taking for many years, and we highly recommend its successor.

Complimentary Shade Service

Calibration Tab

1 of 3 Printouts

Many shade-taking systems have come and gone through the years. The challenges with this technology have been cost, provider-support, and effectiveness. ClearMatch, a system we recently launched, is showing promise. It is a software that determines shade, value, and translucency from a chairside photograph. A special black-n-white calibration tab and a Vita A2 shade tab are held edge-to-edge to a target tooth, and a photograph is taken. The image is emailed to ROE and analyzed with the ClearMatch system. Shade, value and translucency maps are printed and provided to the ceramist (figure 1), and returned with the completed case.

The quality of the photograph is critical to the success of the shade analysis. Proper flash and focus are the two key components. We recommend in-office training, which is available to offices throughout Ohio at no charge. If you are interested, please contact Alan Banks at ROE. Complete instructions can also be found on our website at the Shade & Smile Service page along with a link to a thorough YouTube video.

ClearMatch software, developed a dozen years ago, is proving to be very effective. We use it, along with ShadeVision and other tools, when patients visit us for shade analysis.

Shade legend

In.a.Box Implant Pricing

With a single phone call, a dentist can now virtually plan an implant case, order a surgical guide with drills, order the implant(s), healing caps, and/or a provisional. We call this service In.a.Box. Pricing. It was developed through a partnership between ROE and BlueSkyBio, for implants that are compatible with Zimmer, Astra, Straumann, or Nobel. This service is designed for ease-of-use to help reduce office inventory, and save time and expense, when ordering components for surgery. When cases are planned virtually, the implant size is determined. At this point, everything you need to place, protect, or provisionalize can be ordered.

An economical option in this service is the Direct Cut Kit from BlueSkyBio. This kit was developed for a one-drill protocol for an osteotomy. This computer-guided package includes a surgical guide, the implant and healing abutment, one drill, and the final screw-retained restoration. The total cost is $909.

3 Solutions to Cement Clean-Up on Implant Restorations

In the last couple of years there has been a lot of chatter concerning the effect of residual cement on implant cases: bacteria build-up, peri-implantitis, bone loss, etc. Although there are many methods of managing cement, we would like to offer three.

The number one method of eradicating these issues is, of course, to eliminate cement altogether, and choose screw-retention. We have witnessed a surge in one-piece, screw-retained crowns and bridges. Our most popular is a zirconia/titanium hybrid (TLZ-SR) that is very durable and esthetic and only costs $299.

Another method is to request a two-piece restoration, which includes a custom abutment and a crown designed with a hole in the occlusal or lingual surface. This allows simple clean-up through the following method: seat the abutment using a thumb driver; place a cotton pellet in the access hole of the abutment; insert the crown to check margins, contacts and occlusion; cement the crown in place; remove the cotton pellet before the cement hardens; unscrew the abutment through the hole; remove the crown and abutment together; clean the excess cement; torque down the cleaned restoration, and fill the screw hole with composite. Be sure to have an abutment removal tool, or a driver that can be reversed, when using a friction-fit system, i.e. Zimmer Dental.

A third method is to order a duplicate resin die. This die can be used for “cement pumping”. Here are the steps: torque in the abutment; check margins, contacts and occlusion; place cement in the crown; seat the crown on the duplicate die; clean the excess cement expressed at the margin, and transfer the crown from the die to the mouth.