For the past several months, we have been offering e.max restorations as our newest all-ceramic option. The e.max system was created by Ivoclar Vivadent, and improves upon the strength and aesthetics of other pressed zirconia crowns.
-Eric P.
Monday, August 3, 2009
Sunday, April 26, 2009
Dental Intelligence
Another excerpt from studies conducted by Dr. Yada Chaiyabutr at the Kois Center...
Q: When the ceramic onlay comes back from the lab, it is already acid-etched and I should silanate it before anything, right? After I try it in, do I need to re-etch and re-silanate?
A: The silane solution should be applied directly on a ceramic restoration for 60 seconds. Then let the ceramic surface dry prior to a try-in process. Studies confirmed that this step is important for acheiving a durable adhesion of the resin cement bonding to the ceramic. Silane, X-(CH2) Si-(OR), creates chemical bonds between organic surfaces (e.g. resin materials and polymers) and inorganic surfaces (e.g. silica-based ceramics). The silanol groups, on one end, react with silica oxide forming a siloxane network (-Si-O-Si-O-) while the monomeric groups, on the other end, react with the methacrylate groups of the resin material. If the ceramic surface is contaminated after the try-in process, retreat it first by cleaning with an appropriate amount of solvent (water or acetone) and then re-etching with phosphoric acid (30-40%) for 60 seconds. Rinse with water and re-apply the silane solution.
Q: Why isn't self-adhesive resin cement used for adhesively retained restorations? How strong is the bonding compared to traditional resin cement?
A: Adhesively retained restorations (e.g. onlays, inlays, and veneers) rely on the bonding interface between the tooth (mainly, enamel) and restorations. The chemical bonding of the self-adhesive resin cement and the enamel is insufficient due to an inadequate etching through the enamel smear layer. Therefore, traditional resin cement is more appropriate to use. Studies showed that the total acid-etching step created deeper micromechanical interlock between the resin cement and the enamel and that resulted in stronger bonding. To avoid unnecessary risks of failure, self-adhesive resin cement is recommended for cohesively retained restorations and traditional resin cement is recommended for adhesively retained restorations.
Q: When the ceramic onlay comes back from the lab, it is already acid-etched and I should silanate it before anything, right? After I try it in, do I need to re-etch and re-silanate?
A: The silane solution should be applied directly on a ceramic restoration for 60 seconds. Then let the ceramic surface dry prior to a try-in process. Studies confirmed that this step is important for acheiving a durable adhesion of the resin cement bonding to the ceramic. Silane, X-(CH2) Si-(OR), creates chemical bonds between organic surfaces (e.g. resin materials and polymers) and inorganic surfaces (e.g. silica-based ceramics). The silanol groups, on one end, react with silica oxide forming a siloxane network (-Si-O-Si-O-) while the monomeric groups, on the other end, react with the methacrylate groups of the resin material. If the ceramic surface is contaminated after the try-in process, retreat it first by cleaning with an appropriate amount of solvent (water or acetone) and then re-etching with phosphoric acid (30-40%) for 60 seconds. Rinse with water and re-apply the silane solution.
Q: Why isn't self-adhesive resin cement used for adhesively retained restorations? How strong is the bonding compared to traditional resin cement?
A: Adhesively retained restorations (e.g. onlays, inlays, and veneers) rely on the bonding interface between the tooth (mainly, enamel) and restorations. The chemical bonding of the self-adhesive resin cement and the enamel is insufficient due to an inadequate etching through the enamel smear layer. Therefore, traditional resin cement is more appropriate to use. Studies showed that the total acid-etching step created deeper micromechanical interlock between the resin cement and the enamel and that resulted in stronger bonding. To avoid unnecessary risks of failure, self-adhesive resin cement is recommended for cohesively retained restorations and traditional resin cement is recommended for adhesively retained restorations.
-Tony L.
Wednesday, December 3, 2008
Taking a Break for the Holidays
With the holidays fast approaching, we are looking ahead to our schedule during the last two weeks of December. This year, Tony and Cindy will be enjoying Christmas with Tony's family in Las Vegas, and they will return to the office on January 5th. From December 22nd to January 2nd, our office hours will be as follows:
Monday and Tuesday: 8AM-2PM
Wednesday: 8AM-12PM
Thursday and Friday: Closed
Please note that while the office is open for pickups, deliveries, and phone calls, we will not be completing any cases during this time. If you are seating a case during this time period, please call for a pickup no later then December 15th.
As always, we appreciate your business, and thank you for helping us have another successful year.
Happy Holidays, from everyone at AOA.
-Eric P.
Wednesday, October 15, 2008
Pacific Implant Institute - Dr. Ron Zokol
Implant Retained Removeable Denture
(Cementable/Overdenture)
On October 23 - 27, I will be out of the office and heading over to the Pacific Implant Institute in Vancouver, BC to take an Implant Prosthodontics course. The course will be about Implant Retained Removeable Dentures, both either with cementable restorations or, with Overdentures and will be presented by Dr. Ron Zokol. "Due to implant rigidity in bone, laboratory tolerances are finer and requirement for acuracy and strong laboratory communication is essential to providing high quality services." - Dr. R. Zokol.
This program will provide solution for all prosthetic services involving implant retained dentures and will have a strong component for comprehensive diagnosis and case selection to ensure the case we are treating is suited to our skills.
For years now, I've always been intrigued by these implant retained denture restorations and have been very interested in how I might be able to create these in the laboratory. I'm fascinated as how beautiful they turn out, but hold reservations knowing these are not easy to do. Excuses aside, I will be stepping up to the plate to learn this boutique side of dentistry that is slowly becoming standard care.
I would like to whole-heartedly and personally, thank Dr. Kari Chellis for helping to make this course possible for me to get into. Thank you so much Kari.
- Tony L.
Wednesday, September 24, 2008
Dental Intelligence
Intelligence: the ability to learn or, understand or, to deal with new or, trying situations.
"Good Things We Learned From the Kois Center"
Q: Does alumina oxide particle abrasion affect the bond strength of self-adhesive luting cement for final restorations?
A: No. Our study reveals that alumina oxide particle abrasion does not have an adverse effect on the bond strength of the self-adhesive cement (e.g. RelyX
Unicem, Maxcem, Multilink) but, to the contrary, helps increase it. It is clear from Scanning Electron Microscope (SEM) pictures and Energy Dispersive Analysis (EDS) that most of the particles were gone after being sprayed with water and an irregular, rough surface appeared on the tooth surface after particle abrasion. The roughness on the surface increased the bonding area, which consequently increased the bond strength. When applying the mechanical cleaning protocol before final cementation, it is advisable to use small nozzle tips (0.015), small alumina oxide particles (27 um), low parameters (e.g. nozzle tip diameter, nozzle tip
distance, air pressure, particle size and type of air abrasive) could affect the bond strength.
Q. Why is RelyX Unicem cement occasionally too thick and viscous?
A. Mostly, excessive cement viscosity and film thickness result from improper mixing. It is important that the capsules be securely placed in the activator and the lever arm firmly pressed down to activate the liquid for an adequate time period. If the capsule is activated for too short a time, some of the liquid will not be injected into the powder and a "thick" mix will be observed. We tested various mixing protocols to find the most efficient. Our data revealed that a long liquid activating time (5 seconds) and a longer mixing time (15 seconds) for both a centrifugal mixing machine (e.g. Rotomix) or a high frequency mixing machine (eg. Capmix/Amalgamator) yielded the best results. If possible, light-curing the restoration for about 20 seconds for indirect
restoration is also suggested. Recently, a new RelyX unicem paste named "Clicker" was introduced into the market, which we also included in our study. It was found that this
type of cement's shear bond strength was comparable to the capsule-mixed cements. Unfortunately, with the paste system you may need to use a hand-mixed protocol, which might cause the mixing to be technique sensitive again.
As part of the Kois Center program, we benefit from the knowledge and experience of doctors who support the Center. In the premier issue of our newsletter "Excellence", we found an informative monthly Q&A from Dr. Yada Chaiyabutr (DDS, MSD, DSc). - Eric P. & Tony L.
"Good Things We Learned From the Kois Center"
Q: Does alumina oxide particle abrasion affect the bond strength of self-adhesive luting cement for final restorations?
A: No. Our study reveals that alumina oxide particle abrasion does not have an adverse effect on the bond strength of the self-adhesive cement (e.g. RelyX
Unicem, Maxcem, Multilink) but, to the contrary, helps increase it. It is clear from Scanning Electron Microscope (SEM) pictures and Energy Dispersive Analysis (EDS) that most of the particles were gone after being sprayed with water and an irregular, rough surface appeared on the tooth surface after particle abrasion. The roughness on the surface increased the bonding area, which consequently increased the bond strength. When applying the mechanical cleaning protocol before final cementation, it is advisable to use small nozzle tips (0.015), small alumina oxide particles (27 um), low parameters (e.g. nozzle tip diameter, nozzle tipdistance, air pressure, particle size and type of air abrasive) could affect the bond strength.
Q. Why is RelyX Unicem cement occasionally too thick and viscous?
A. Mostly, excessive cement viscosity and film thickness result from improper mixing. It is important that the capsules be securely placed in the activator and the lever arm firmly pressed down to activate the liquid for an adequate time period. If the capsule is activated for too short a time, some of the liquid will not be injected into the powder and a "thick" mix will be observed. We tested various mixing protocols to find the most efficient. Our data revealed that a long liquid activating time (5 seconds) and a longer mixing time (15 seconds) for both a centrifugal mixing machine (e.g. Rotomix) or a high frequency mixing machine (eg. Capmix/Amalgamator) yielded the best results. If possible, light-curing the restoration for about 20 seconds for indirect
restoration is also suggested. Recently, a new RelyX unicem paste named "Clicker" was introduced into the market, which we also included in our study. It was found that this
type of cement's shear bond strength was comparable to the capsule-mixed cements. Unfortunately, with the paste system you may need to use a hand-mixed protocol, which might cause the mixing to be technique sensitive again.
As part of the Kois Center program, we benefit from the knowledge and experience of doctors who support the Center. In the premier issue of our newsletter "Excellence", we found an informative monthly Q&A from Dr. Yada Chaiyabutr (DDS, MSD, DSc). - Eric P. & Tony L.
Wednesday, September 10, 2008
Tom is happy! Next, we'll do the lowers.
Back in July of this year, we fabricated eight beautiful teeth for Tom. We used, all-ceramic "Press to Zirconia" restorations to achieve the results seen here. We'll be doing the lowers next year.
(Tom's before picture below)
Teeth involved:
#6, 7, 8, 9, 10 & 11 = Nobel Biocare Zirconia
#12 & 13 = Cercon Zirconia
Pressed with DeguDent Cercon Ceram Porcelain Ingots
Finishing touches: DeguDent "Press & Smile" with GC IQ Initial
Dental Intelligence - incorporating the best elements of metal-free restorations, by combining the best of both worlds. If you like the unmatched strength of Zirconia (ie: Cercon, Kavo, Lava...), as well as the beautiful lifelike esthethics of Pressable ceramics (ie: Empress, Authentic, Finesse...), then we have something for you.
- Eric P. / Tony L.
Thursday, September 4, 2008
AOA Lab Picnic
Below, you can see the photos from our annual lab picnic. The weather was perfect and the turnout was high. This year we had nearly 50 guests, and that number seems to grow every year. Thank you all for your friendship and support. - AOA
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