Michael Miller, DDS
I have a 17-year-old male patient with severe hypocalcification. The patient and his parents are concerned about esthetics. I was wondering if there is any problem with bonding to such teeth? Which restoration is best — veneers or crowns? What is the best adhesive if bonding is in question? Is there any less bonding strength due to the hypocalcification?
When you say the patient has "severe hypocalcification," I assume you mean white spots, since you obviously can't make a diagnosis of hypocalcification without microscopically examining the teeth. In any event, bonding to areas of atypical tooth structure — such as white spots — has not been thoroughly investigated, although common sense would seem to indicate that it could be problematic. Therefore, if nothing else is wrong with the teeth, using enamel microabrasion, as described in pages 589-593 of our book, The Techniques, would be the first step. If this is not successful, then removing the visible white spots and placing veneers of some kind would be the treatment of choice. Crowns should only be considered as a last resort.
I realize that it is generally true (with a few exceptions) that self-cure composites will not bond to light-cured adhesives. What is the chemical mechanism that causes the incompatibility problem?
This could possibly be due to the pH of the single-component adhesives, which tends to be quite low. The same applies to self-etching adhesives. A low pH seems to interfere with the chemical bond.
Can RelyX Unicem (3M ESPE) be used for cementing IPS Empress (Ivoclar Vivadent) crowns? I have used it successfully with PFG, but don't know about any expansion problems with metal-free restorations.
Our full report on RelyX Unicem (pictured at left) was published in the June issue of our monthly update, REALITY NOW. In summary, our clinical experience, at this point, does not show any of the expansion characteristics that plagued some of the resin ionomer cements. This means it should be acceptable to use with any type of ceramic restoration except veneers.
Do you etch/bond before or after applying Consepsis? REALITY and the manufacturer (Ultradent) differ on instructions.
Actually, you can use Consepsis before etching to clean the preparation and after etching but before placing the adhesive. We agree with the manufacturer on those uses. We don't believe, however, that the "after etching" use is mandatory, but the cleaning step should be, whether you use Consepsis or another cleaner.
When using a self-etching adhesive with a flowable composite, sometimes I like to use a sealant to seal unaffected grooves. My concern is that enamel that hasn't been cut won't bond as well. Do I need to use an etchant in addition to the self-etching primer?
Yes, etching the unprepared enamel with phosphoric acid would be a prudent procedure when sealing pits and fissures adjacent to a preparation that has been bonded using a self-etching adhesive.
I had been using the older Aquasil Rigid/LV Fast Set (DENTSPLY Caulk) with single-tray and triple-tray backups for several years. I changed about four months ago to the newer Aquasil Ultra Heavy/LV Fast Set. Six weeks ago, one of my three C&B labs began sending back non-fitting crowns. The lab blames the non-fits on the newer material and says that only the new Aquasil users are having problems. My other labs are still sending fine work. Another manufacturer has told me that it has heard that the new Aquasil is having problems, but they sell another product. Is anyone else having problems? Is there data available from REALITY that compares the new Ultra to the original version?
All vinyl polysiloxanes have been essentially "shades of grey," varying mainly by viscosities, color, and set times. But Aquasil Ultra (pictured at right) does seem to be different. One study shows it to have the highest tear strength of any impression material (including polyether) and its contact angle is comparable to that of hydrocolloid. With wet teeth, it seems to behave differently, registering subgingival preparations with more reliability. It appears that Aquasil Ultra has again raised the bar for impression materials. With its accuracy and tear resistance, it goes to the top of the category. If two of your three labs are not experiencing any problems, then it may be caused by something internal in the third lab.
As a sworn user of Revolution (Kerr), I am sometimes annoyed by voids embedded in the cured filling. I always bleed the syringe and tip before applying and I also try to avoid lifting the tip while applying. Is this something I must accept? Is there a flowable that can do better? I also use Point 4 (Kerr) and like it, but, too often, I have to remake the filling due to black particles that (I guess) are debris from the production of the tips. Also, can you please state the best protocol for repairing the voids after removing them or the debris?
Most flowables have some voids, but using a very fine (000) sable hair brush to manipulate the material after it is injected can disclose and subsequently allow you to flow more material into the voids. In addition, be sure to use layers of flowable as thin as possible — no thicker than 1 mm. The black specks in Point 4 typically occur when the material is dispensed. This is a problem that many manufacturers have tried to combat with varying levels of success. If you are using the syringes, you can extrude the material and cut off the amount you need with an instrument instead of rubbing the syringe end itself against a pad. Even then, once on the pad, you still may need to examine the material under magnification and remove any sections embedded with the black debris. You could also try another product. As far as repairing the voids, merely apply phosphoric acid to clean the area, apply a thin layer of unfilled resin, and then the restorative material.
Dr. Michael Miller is the publisher of REALITY and REALITY Now, the information source for esthetic dentistry.
Looking for more information on the companies mentioned?