Clinical Corner: Information on Dental Procedures

Articles

What's Hot: Dr. Glazer on Jazz
Combating Hidden Decay with Early Detection
Atraumatic Removal of Defective Crowns
Balancing: The Art, Science and Business of Dentistry
Intra-Oral Preparation of Titanium Abutments in Order to Obtain Ideal Angulations and Contours
SS White Express Line High Speed Laboratory Metal Finishing Burs
Direct Preparation Of Preexisting Implant Abutments For Case Rehabilitation
Flextime Xtreme: The 80/20 Rule
Fast and Smooth - Efficient Crown Preparation With Carbide Instruments
When Advancing the Bur, One Can Feel the Presence of Dentinal Caries
Precision Trimming and Finishing of Current Dental Restorations Using the Safe End Bur System
Indirect Restorative Tooth Preparation: Extreme Efficiency and Accuracy
Creating Maximum Efficiency and Accuracy In Indirect Restorative Tooth Preparation
Preparation Protocol To Ensure Predictable Aesthetic Restorations
Tooth Preparation Mastering Quality and Efficiency
Fissurotomy: Proactive Treatment for Incipient Decay
Anatomically Adapted Carbide Finishing Burs - Creating Super-Smooth Composite Surfaces in Two Steps
Directions for Use: Dr. David Clark Kit
Placing Traditional Sealants with Enhanced Magnification: Methodology to Increase Both Short-term and Long-term Success - David Clark, DDS
How to Quickly and Conservatively Restore a Natural Shine after Orthodontic Bracket Removal
SS White Surgical Length Oral Surgery Burs: Atraumatic Removal of Teeth for Maximum Bone Preservation

"Flextime Xtreme: The 80/20 Rule"

Howard S. Glazer , D.D.S., F.A.G.D. 

We have all heard about the 80/20 rule applied to various analogies. Within dentistry, we can also apply this “rule” to the fabrications of crowns. In my practice, as well as in many of my colleagues, it seems the 80 percent of the crown and bridge procedures involve single crowns and the remaining 20 percent are multiple units. Further discussion with fellow dentists around the world say I am underestimating the percentages and that it is more like 85 percent of all crown and bridge procedures are single units. If we accept this hypothesis, then we should possibly rethink how we provide this relatively uncomplicated service in the most efficient and comfortable manner for our patients.

Two key components of the single crown procedure involve the preparation of the tooth and the impression of the preparation. Let’s briefly look at tooth preparation and how we can make it more expeditious and exacting.

Figure 1 Establishing the guide planes	Figure 2 Preparing the margin	Figure 3 Preparation completed – buccal view
Figure 4 Ppreparation completed – occlusal view	For many years I have always prepared crowns by using diamond instruments in a high-speed handpiece, either air driven or electric. Recently, I have begun to use carbides to prepare teeth. The reason is simple: carbides cut and diamonds grind. When we are removing enamel it is much more effective to cut it away then to grind it away. The grinding produces more friction with increased heat buildup that could ultimately result in a pulpitis. In order to cut smoothly and efficiently I use the Great White Ultra Carbides (SS White). These are available in various sizes and shapes that allow for all ceramic, all metal, or porcelain-to-metal preparations. There are even shapes highly suitable for inlays and onlays. These burs cut smoothly and efficiently without “grabbing” or “catching”, or “chattering” as you cut into tooth structure, leaving a clean, smooth finish line to preserve marginal integrity. (Figures 1-4)

Now that we have efficiently prepared the tooth we need to have an exacting way to replicate the tooth for the laboratory. In the progression of impression materials for crown and bridge procedures, we have gone from the difficult, hard to use, foul-smelling rubber base materials to the fast setting, easy-to-use, vinyl polysiloxane (VPS) materials. During this evolution, technique, accuracy and stability have become the benchmarks by which all impression materials are measured. The essence of any impression material is to transfer information from the clinician at chairside, to the laboratory technician who will fabricate the restorations. Consequently, the “best” clinicians, with the most ideal preparation, in combination with the “best” technician, utilizing the finest porcelains, are at the mercy of the impression process.

Patients are for the most part tolerant of our treatment. However patient constantly reports two common complaints. For years, practitioners have heard complaints from patients that the impression materials tasted bad, and took too long to set. Complaints from the dentist included too long a setting time, and difficulty in handling. Laboratory technicians voiced their complaints of tearing at the critical margins and dimensional instability. Add all this up and you have a lack of harmony between the dentist and technician and the patient who ultimately had to endure yet another office visit to repeat an impression. Lost chair time, lab time, patient time and diminished patient confidence, all became “hostage” to the quality of the material used for the impression.

Manufacturers have long realized they need to address these concerns and have made tremendous progress in that direction. Today, we have a vinyl polysiloxane material that sets quickly, has a pleasant aroma and most importantly from the dental perspective, offers a high degree of dimensional stability. Welcome the new impression material Flexitime Xtreme (Heraeus Kulzer, Armonk, NY).

Flexitime Xtreme is available in monophase, heavy tray and correct flow viscosities just like the regular Flexitime line of impression materials. The big difference here is that it sets on only 90 seconds and has a very pleasant wild berry aroma. Working time is also 90 seconds and the material will not actually set until placed in the patient’s mouth due to Kulzer’s advanced Thermasense which accelerates the setting time based on the body’s temperature to allow for a 90 second hard set. That’s the beauty of Flexitime Xtreme’s Advance Thermasense technology, especially in a material that is ideal for a single unit. Materials are available in automix cartridges with disposable tips that provide super “no fuss-no mess!” impressions.

The wild berry scent is caused by aromatic oil not a flavoring. The key difference is that a flavoring induces salivary flow and that is not good when taking an impression. Patients really enjoy the pleasant aroma and more importantly enjoy the relatively short setting time. The difference between 90 seconds and 180 seconds can be an eternity to a patient with an active gag reflex.

Upon removal of the impression you will notice great detail and super marginal integrity that will remain stabile over and extended period of time. So whether you lab is around the corner or around the world the impression will remain dimensionally stabile. (Figures 5-10)

Figure 5 Crown preparations – tooth # 13 & 14	Figure 6 Impression of tooth #13 & 14 with Flexitime Xtreme Heavy Tray & Correct flow	Figure 7 Preparation of tooth # 9
Figure 8 Impression of tooth #9 with Flexitime Xtreme Heavy Tray & Correct Flow showing exact replication of marginal detail	Figure 9 Preparation of tooth #14	Figure 10 Impression of tooth #14 with Flexitime Xtreme Heavy Tray & Correct Flow showing excellent replication of marginal detail

There are many different burs and impression materials in the marketplace and a dentist often has a difficult time in deciding which bur or material to select. Ultimately, he or she will select what works well in his/her hands, and is easy for the patient to tolerate. Three crucial points to consider are speed, accuracy and patient comfort. Poor preparation and a poor impression can only lead to a poor restorative outcome. In making the decision of which materials to use, it is incumbent upon the dentist to make a selection that will provide technical and clinical results and superior patient satisfaction. The combination of Great White Ultra Carbides and Flexitime Xtreme are perfect in satisfying those requirements. .

Case Report:

Photo 1 Tooth #25 fracture to gingival crest	Photo 2 Post & core placed	An 81-year-old male presented with a previously un-restored and now fractured lower central incisor tooth #25 (photo 1). The tooth was fractured to the gingival crest and required root canal therapy, a post, core (photo 2) and modified crown lengthening prior to preparing for a crown.
Photo 3a Tooth being prepared and establishing margins w/ GW Ultra Carbide 847-16	Photo 3b Tooth being prepared and establishing margins w/ GW Ultra Carbide 847-16	Tooth #2 was then prepared using a Great White Ultra Carbide 847-16 with the Optima MX (Bien Air) electric motor and handpiece (photos 3a and 3b).

After preparation, Tissuegoo (Clinician’s Choice) was syringed around the preparation to control bleeding and act as a lubricant for the placement of Stay-Put retraction cord (Roeko) (photo 4). The impression was made with a triple tray using Flexitime Xtreme (Heraeus Kulzer) heavy tray and correct flow materials (photo 5). A porcelain-to-metal crown was fabricated and inserted using Embrace Resin Cement (photo6).

Photo 4 Retraction cord in place and fluids controlled

Photo 5 Impression of tooth #25 with Flexitime Xtreme Heavy Tray & Correct flow

Photo 6 PFM cemented in place