Thursday, May 3, 2012

Zirconia Cementation Update

The generally accepted practice of conventionally cementing monolithic ceramic restorations is clinically efficient and is the most popular method of placing our all-zirconia TLZ, BruxZir, and lithium-disilicate eMax restorations. In a recent edition of Inside Dental Technology, however, Dr. Ed McLaren takes issue:  “The problem is that these cements are much more soluble than resin-based cements. If, over time, the cement solubilizes and fails, exposing the glass cement to saliva, the restoration can undergo hydrolytic degradation which weakens the material.” He recommends bonding these restorations, particularly in situations where the preparation is non-retentive. Dr. Russell Giordano, Boston University Goldman School of Dental Medicine, an authority on dental materials agrees. It has been established that bonding almost doubles the load and increases resistance to failure. Low pressure, sandblasting the interior of the restoration at the laboratory with alumina, and the use of primers, such as AZ Primer (Shofu Dental Corporation), Clearfil™ Ceramic Primer (Kuraray), Metal/Zirconia Primer (Ivoclar Vivadent), and Z-Prime Plus® (BISCO), significantly improve adhesion. Recently, The Dental Advisor gave Bisco’s Z-Prime Plus a 5-Star rating and claimed that it doubles zirconia bond-strength. Z-Prime is a priming agent that enhances the adhesion between zirconia and composite resin cements, in both self-cure and light-cure modes.

Based on what we’ve recently learned about the effects of primers, therefore, we recommend their use on both full-contour zirconia and porcelain fused-to-metal restorations, particularly with minimally retentive preparations.

Komet ZR Intraoral Zirconia Adjustment Kit

ROE now offers a special kit for intraoral adjustment of full-contour zirconia and lithium disilicate restorations. The new, diamond-interspersed, ZR Flash Polishers are designed to re-glaze hi-strength ceramics simply,  once seating adjustments are complete.  These slow-speed points and cups complement Komet’s excellent long-lasting adjustment burs.

Call our customer service team to place an order. The kit comes in a sleek stainless steel block and is available for $85.

Lucia Jig - Anterior Nightguard

Anterior nightguards have become very popular appliances. The minimally-invasive design is comfortable and unobtrusive and does not affect the airway. Also, coverage is usually limited to the incisors, which minimizes a patient’s biting force, clenching and bruxing. These devices are  commonly prescribed to patients who suffer from migraines and TMJ pain.

ROE’s anterior nightguard is called the Lucia Jig ($119). To order, simply send maxillary and mandibular casts and a maximum protrusive measurement. To capture this measurement, ask the patient to push his or her jaw forward, and measure the horizontal distance from the lower incisal edge to the upper incisal edge. The appliance requires 3 days in the laboratory and modified designs are available based upon your specific needs.

All-On-4 Support

If you are currently restoring or thinking of becoming involved with All-On-4 type cases ROE can be of tremendous service to you. During the past several years we have supported countless dental offices with every step in the process from case-planning and surgical-guidance to chairside denture-conversion the day-of-surgery (Ohio only). For the surgical appointment, we visit the office with all the tools and materials necessary to convert and finish the provisional or final hybrid.

Today, all the major implant brands have a variation of All-On-4: Zimmer - RevitalizeTM, Astra – Uni-For-FixedTM, and 3i - DIEM®2. We support all these systems, as well as Straumann and Thommen, who offer components suited for the protocol.

Can you detect a midline discrepancy?

According to a study published in the Journal of Esthetic Dentistry, which evaluated the perceptions among dentists, orthodontists, and lay people on a variety of esthetic discrepancies, a maxillary midline deviation of 4 mm was necessary before orthodontists rated it significantly less esthetic than the others. However, general dentists and lay people were unable to detect even a 4-mm midline deviation. Conversely, when the midline angulation deviated only 1mm, all three groups noticed. As a team, it is important that we pay particular attention to ensure the angulation of the midline is perpendicular.

Cosmetic Acrylic Mock-up

A diagnostic wax-up is a great tool when discussing the potential of a new smile.  Wouldn’t it be nice also, in a reproduction of the final restoration, to verify all the critical components of anterior esthetics? This is possible by performing an intraoral, reversible, composite build-up.  This procedure, however, is very time-consuming and may result in a less-than-ideal representation of the desired result. ROE offers a “Mock-Up” service, which enables a patient to try-in and visualize the proposed smile quickly and easily. Both form and function can be evaluated prior to tooth preparation.

A “Mock-Up” is created by duplicating the patient’s study model, fabricating a diagnostic wax-up, and reproducing the result of the wax-up on the master model with a very thin acrylic laminate veneer. This replica of the diagnostic wax-up is then placed clinically with try-in paste, or spot-tacked with temporary cement. This disposable laminate is intended for chairside-presentation and evaluation only, and not recommended to be worn outside the dental office. The total cost of this service is $45 per unit, and includes preparation and temporization matrixes for use at the preparation appointment.

Heraeus Kulzer Mondial Teeth

In our last ROE Reports we wrote about the many exciting changes we’ve made to our implant-supported hybrids and overdentures. One update was the adoption of the Mondial tooth line (Heraeus Kulzer). These premium teeth are ideal for implant prosthetics due to proven, clinical success at both the Malo Clinics and ClearChoice®. New NanoPearl® technology makes these teeth much stronger and more resistant  to wear than PMMA teeth. In fact, an independent study conducted by Tufts University found them to be the #1 wear-resistant tooth. Also, according to Heraeus, there is a true chemical bond to acrylic. These key benefits will increase longevity. It is important to note that the switch to these premium teeth for implant cases does not affect our recently introduced All-in-One pricing. Special shade and mold guides are available through ROE.