NuSmile ZR Technical Support
How do I properly cement a NuSmile ZR crown?
According to published scientific evidence it is very important to be sure that saliva or blood does not contaminate the internal surface of zirconia crowns. For this reason we provide NuSmile ZR Try-In crowns for use during try-in (test fitting) to avoid saliva or blood contamination of the actual NuSmile ZR crown to be used. All NuSmile ZR Try-In crowns are precision manufactured to be identical in size and shape to NuSmile ZR crowns, and can be used and autoclaved repeatedly for try-in purposes. If contamination of the internal NuSmile ZR crown surface does occur one of two processes is recommended for best retention of the cement to the crown. Sandblast the inside of the crown with pure aluminum oxide, or clean internal crown surface with Ivoclean (www.ivoclarvivadent.us/en-us/products/luting-material/accessories/ivoclean) NuSmile BioCem® Universal BioActive Cement, Ceramir, or a resin modified glass ionomer cement indicated for zirconia restorations can be used to cement NuSmile ZR crowns. Though not recommended in most literature, some doctors do successfully use high quality glass ionomer cements to cement preformed zirconia crowns. Completely load the crown so there are no voids during placement. If pulpal therapy has been performed with a eugenol based material placed in the pulp chamber, cover the eugenol based material with pure glass ionomer before cementation unless using GI for cementation. The NuSmile ZR crown should have a passive fit and be held in position until the cement self-sets or is light cured.
Is there something you can send me that will help me better understand the technique for using NuSmile ZR crowns? Do you have training videos available for your crowns?
Yes, we offer technical videos which are available on our YouTube Channel that demonstrate preparation and placement procedures (on actual patients), used for achieving the highest degree of success and efficiency when using both anterior and posterior NuSmile ZR crowns. You can access our clinical videos at: www.youtube.com/channel/UCAsG3apKAwtgCPNikyXjOSQ NuSmile also conducts both live "hands-on" workshops and web-based trainings periodically in major cities in the US and Canada, and through our distributors worldwide. See our listing of upcoming training opportunities.
Do you offer sample NuSmile ZR crowns for interested doctors?
Yes, we will provide a sample of our NuSmile ZR crown which also includes our Technical Guide/IFU and QuickStart guide explaining the product in more detail. Please contact NuSmile Customer Service if you’d like to receive a sample.
What are your NuSmile ZR crowns made of?
NuSmile ZR crowns are made of high quality Japanese Y-TZP monolithic zirconia ceramic.
How do I sterilize NuSmile ZR crowns?
Cold sterilization, autoclave or steam sterilization according to the manufacturer of the sterilizers standard instructions are all acceptable methods.
What is the difference between NuSmile ZR 1st Primary Molar and NuSmile ZR Narrow 1st Primary Molar crowns?
The mesial-distal width of the Narrow 1st Primary Molar crowns is 0.5 mm narrower than the regular 1st Primary Molar crowns. Both types of crowns have the same buccal-lingual dimension.
Can I shorten a NuSmile ZR crown? If so, how?
NuSmile ZR adjustment burs can be used to circumferentially reduce & feather the crown margin. It is important to use a light touch and a continuous water spray. NuSmile ZR crown polishers should be used to restore a smooth surface to the crown following any adjustments.
Are NuSmile ZR crowns crimpable?
NuSmile ZR crowns are not crimpable.
What ADA Code is recommended for NuSmile ZR crowns? Is it the same for both anterior & posterior crowns?
For NuSmile ZR Anterior and Posterior crowns use: D2929 – Prefabricated porcelain/ceramic crown – primary tooth.
Can I use a bite stick to seat a NuSmile ZR crown?
No, NuSmile ZR crowns must be seated with finger pressure only. If the crowns will not seat passively, more reduction of the tooth structure is required.
Is placing a NuSmile ZR crown the same as placing a SSC?
Similar, however NuSmile ZR crowns require more tooth reduction than for SSCs. The tooth preparation for NuSmile ZR crowns is slightly more conservative than for NuSmile Signature crowns, especially occlusally. NuSmile ZR crowns require about 20% more reduction than a SSC around the entire circumference of the tooth. The occlusal reduction is almost the same amount as for a SSC. Always prep the tooth to fit the crown and remember that a "snap fit" is contraindicated for NuSmile ZR crowns.
How is gingival response to NuSmile ZR crowns?
Gingival response is excellent due to the anatomically correct contours and high biocompatibility of NuSmile ZR. With a properly fitted crown, good gingival response is expected within 7-10 days. With reasonable hygiene, good gingival health should remain long-term.
How do NuSmile ZR crowns compare to strip crowns?
NuSmile ZR crowns are less technique sensitive than strip crowns and they offer the same full coverage protection as a SSC (SSC-8% failure; Tate et al, Pediatric Dentistry 2002; 24:69-71). NuSmile ZR crowns take less time to place and are more durable than strip crowns (strip crowns-51% failure; Tate et al, Pediatric Dentistry, 2002, 24:69-71). NuSmile ZR crowns, once seated, should last until the tooth exfoliates. Zirconia crowns have had a history of more than 10 years of success in adult dentistry and more than 5 years of success in pediatric dentistry.
What expectation of success should I have over time with NuSmile ZR anterior crowns, posterior crowns and canine crowns?
NuSmile ZR crowns do not chip or stain and should last until the tooth exfoliates. Zirconia crowns have had a history of more than 10 years of success in adult dentistry and more than 5 years in pediatric dentistry. When placed according to instructions a success rate of 99% or greater should be expected.
Can I repair a NuSmile ZR crown that has fractured?
Due to the structural nature of zirconia, no manufacturer’s zirconia crowns, including NuSmile’s, are repairable. If a NuSmile ZR crown fractures, which is very rare, it should be replaced. NuSmile will replace at no charge the occasional fractured crown if you will return it to NuSmile after replacement. Before returning a NuSmile crown for replacement please contact NuSmile Customer Service.
Is pulpal therapy needed or required when using NuSmile ZR crowns?
Similar to SSC restorations, pulpal therapy should not be needed for NuSmile ZR crown placement unless dictated by the extent of caries.
I am having difficulty seating adjacent and opposing posterior NuSmile ZR Posterior crowns. What should I do?
First, make sure you have removed enough tooth structure to be able to passively seat the crowns. This will be a more aggressive preparation than for a SSC "snap fit" crown. When placing adjacent crowns or for cases with mesial-distal space loss we recommend using our NuSmile ZR Narrow 1st Primary Molar crowns. These crowns are 0.5 mm narrower than the regular NuSmile ZR 1st Primary Molar crowns. You can also try using a contralateral upper posterior crown for a lower restoration when there has been mesial-distal space loss. Some doctors will reduce the distal of the deciduous canine a little if necessary.
For NuSmile ZR crowns, do I need to remove the letters or numbers after cementation with a polishing bur, or do they normally disappear in few months?
No, most doctors do not remove the identification mark. The identification mark on the lingual is fairly indelible. It will fade over time (usually within 6 months – 1 year), however, it can be removed with a zirconia crown polishing bur. We recommend a rubberized zirconia polisher. We offer two polishers that work well which are included in our NuSmile ZR Adjustment bur kit: ZR Green medium point #W16MZR, used after adjustments or shortening for pre-polishing. 2 - ZR Orange fine point #W16FZR, used after adjustments or shortening for final polishing.
There is often space loss due to decay in the cases I treat. Can I use NuSmile ZR crowns in these cases?
Yes, but you will always need to use a crown size that fits in the space and prepare the tooth accordingly. It will usually be at least one or two crown sizes smaller than if traditional SSCs were being used, maybe more if there is space loss. This always requires preparation of the tooth to fit the crown. With lower posterior crowns, you might find that an upper contralateral crown may work best. We also offer NuSmile ZR Narrow 1st Primary Molars specifically for these type of posterior cases. NuSmile ZR Central and Lateral crowns are available in a size 0 for these cases.
Can you provide the research that has been done with NuSmile ZR crowns?
Our website contains information regarding research and studies that have been done with NuSmile ZR crowns. Zirconia crowns have been used effectively for permanent tooth restoration for many years. You can expect the same good results for primary teeth.
What are the advantages of using NuSmile ZR Try-In crowns as part of the NuSmile ZR crown system?
Scientific research, specifically a study by Kern, et al, published in Dental Materials 24, 508 (2008), showed that saliva contamination on zirconia adversely affected the bond strength of the cement to the zirconia material. Utilizing the NuSmile Try-In crowns ensures optimal cement retention because it allows you to avoid any saliva or hemorrhage contamination to the actual NuSmile ZR crown being cemented.
How can I cement a band or space maintainer to a NuSmile ZR crown?
We recommend pumicing the crown surface and cementing the band or space maintainer with NuSmile BioCem® Universal BioActive Cement.
If I need to do pulp therapy after a NuSmile ZR crown is placed, how can I repair the access opening in the crown?
You can repair the opening in the crown the same as you would for an open-face crown technique (with some mechanical undercuts under the opening and by slightly roughening the zirconia at the opening) and repair the void with composite.