May 1, 2003
by Dr. Elliot Mechanic, DDS
Sometimes what appears obvious to one person is not always obvious to another. The technique we use in our practice to fabricate single unit temporary crowns is often cited by dentists attending my lectures and hands on courses as a most valuable “pearl.” It may cost slightly more than your current technique, but the time and aggravation it will save, will be priceless.
The last few years have seen staggering advances in dental techniques, technologies, and materials. When I attended dental school in the 1970’s there where but a handful of dental material manufacturers and an extremely rigid protocol to carry out dental procedures. Today we have a myriad of creative “boutique” dental products, and dentists are encouraged to think “outside the box” for innovative ways to carry out procedures, which makes every new day in dentistry both fun and exciting.
The fabrication of temporary crowns is a basic procedure that every dentist performs. There are numerous techniques used, ranging from pre-fabricated crowns, alginate impressions with acrylic reline, to free hand carving of acrylic which is the technique I used for over twenty years and which I still believe every dentist should master in order to understand dental anatomy, occlusion, form and function.
Over the years we have done our best to simplify our office protocol and standardize our techniques. Due in large part to ideas contributed by my assistant Sophie LaBelle temporization of single crowns that require virtually no adjustment are quickly performed. It pays to listen to your staff!
At the start of the dental appointment, before the patient is anesthetized, the tooth to be prepared is first visually inspected. If necessary the form of the tooth can be quickly modified using composite resin to restore form and function. The opposing teeth should be checked for plunger cusps and any occlusal modifications necessary. A dual arch impression using a triple tray and polyvinyl impression material is now taken (Fig. 1).
This is a very wise financial investment on your part. Your patient will be able to practice closing their mouth correctly with the triple tray at the beginning of the appointment before being anesthetized. In this way they will understand what to do and get accustomed to closing correctly before the stress of the actual procedure begins. Above all they will be biting in perfect occlusion and you will now have a guide and template to consistently place them back into that position. And finally, as an added bonus you will have a polyvinyl impression that you can keep as a back up to quickly fabricate a new provisional if necessary.
We use Quad Trays (Clinician’s Choice) because (Fig. 2) they are rigid, easy to place, and extremely accurate as they do not have sidewalls to create distortion. Our preferred impression material is Status Blue (Zenith/DMG), which is described as an A-Silicone situation impression material designed as a highly efficient alternative to alginate. What it really is, is a very inexpensive polyvinyl which is quick (1:45), captures excellent detail due to being pressure sensitive, and is effortlessly dispensed from Zenith’s Mixstar or 3M’s Pentamix (Fig. 3). A very minimal amount of material is required. All brands of quadrant trays and polyvinyl materials will work. Others we like are Template (Clinician’s Choice) and Blue Mousse (Parkell).
After removing the preliminary impression from the patients mouth (Fig. 4), we then anesthetize and prepare the crown. Next we fabricate our temporary crown with an automix bisacryl material before taking our final impression (Figs. 5 & 6). We may use this to verify that we have adequately prepared our tooth and we are now able to trim and glaze our temp during the time the final impression is being taken.
I have tried virtually every bisacryl material on the market and I consistently return to Luxatemp (Zenith/DMG). It is the benchmark bisacryl material, has been around the longest, and with its patented 10:1 base: catalyst ratio provides the prefect blend of strength and esthetics. Luxatemp is a highly accurate material, sets in about two minutes, is easily removed, has excellent marginal adaptation, low shrinkage (.45% linear), and produces negligible heat slightly above body temperature during polymerization (38C/ 100F). The narrow diameter mixing tips minimize air bubbles, porous surfaces, and material waste.
Above all, I find Luxatemp strong, extremely esthetic, and just plain user friendly. Many of the other bisacryl’s don’t set hard, are difficult to polish, and fracture easily. Integrity (3M) is also a fine material, but Luxatemp is without a doubt my favorite material in dentistry.
We now take our final impression of the crown prep. As the impression is setting in our patient’s mouth we remove the Luxatemp crown from the Quadtray (don’t worry its set) and mark (Fig. 7). the interproximal contacts and gingival margin with an HB pencil. I use a Seattle Institute Provisional Trimming Kit (Brasseler), which I find trims bisacryl easily and accurately. The temporary crown will require very minimal trimming as the occlusion should be dead on, crown contours sharp due to the accuracy of the Status Blue and if you don’t touch the pencil marks on the contacts and margins, the crown should fit tight, floss perfectly, and have accurate closed margins. I repeat; never trim away the pencil marks!
The temporary crown should require less than 30 seconds trimming and should be ready before the permanent impression is set. You will find that once tried in the mouth, temporaries fabricated using this technique will rarely require any adjustment, not trap any food, and be comfortable and hassle free. Any modifications can be made with Luxaflow (Zenith/ DMG) an add-on flowable microhybrid light cored specifically formulated for Luxatemp (Fig. 8).
The temporary is then removed from the mouth, can be custom stained with Perfect Stain (Great Lake Orthodontics) (Fig. 9) and is then brush glazed with Luxaglaze (Zenith/DMG) (Fig. 10) Light Cured Varnish. Luxaglaze gives a high gloss finish, exhibits life like appearance, provides stain resistance, minimizes plaque and debris accumulation, and above all eliminates the need for mechanical polishing. What a time saver!!!
We then place a small amount of temporary cement, air blow it for thin even distribution and presto you will find that your temporary crown will seat perfectly, need no adjustments, and have minimal temporary cement to clean up (Fig. 11).
If all this sounds too simple and too good to be true, our technique has an added bonus. Why is it that patients always manage to break, de-cement, or lose their temporary crowns and come to our offices at times when we are our busiest? How many times have you squeezed a patient into your schedule and have to hand fabricate a new temporary crown with your stomach churning? How many times have you rushed and made substandard new temp?
Because now you have foresight, you have now been smart and have saved the triple tray polyvinyl impression you can now make a perfect new temporary with minimal effort and stress in just minutes.
That is why I am sharing my obvious, “idiot proof,” “no brainer,” provisional crown technique with you. It will make your dentistry just a little bit easier and less stressful and as we dentist surely know, every little bit counts.
Dr. Mechanic received his DDS from McGill University, Montreal. He is a fellow of the International Academy for Dental Facial Aesthetics and a member of the American Academy of Cosmetic Dentistry.
Oral Health welcomes this original article.