February 2010 | Dental Products Report Clinical 360°: restorative technique How to: Use a self-adhesive resin cement for a posterior crown Ivo
February 2010 | Dental Products Report
Clinical 360°: restorative technique
How to: Use a self-adhesive resin cement for a posterior crown
Ivoclar Vivadent’s SpeedCEM allows for easy cementation of a posterior lithium disilicate crown.
by Dr. Edward Lowe, Vancouver, BC, Canada
Information provided by Ivoclar Vivadent
When placing restorations in the posterior region, it is reassuring to know that those fabricated from IPS e.max lithium disilicate provide dentists and their patients with strength, esthetics and the security of monolithic structures. These uniformly constructed restorations perform at maximum strength and potential durability. The minimal draw and adequate height of the preparation ensure good resistance and retention.
Further enhancing restorative predictability and simplicity is SpeedCEM®, a self-curing, self-adhesive resin cement with a light-curing option for quickly and easily cementing high-strength indirect restorations fabricated from metal, metal-ceramic, high-strength all-ceramic, and fiber-reinforced composite materials. With excellent shear bond values to dentin and enamel, SpeedCEM offers a simple conventional placement technique to achieve predictable bonding characteristics.
When using this resin cement, the need for dentists to condition the tooth preparation or apply dentin/enamel bonding agents is eliminated. Thus, SpeedCEM facilitates a more rapid and efficient technique for definitively seating high-strength restorative materials. Furthermore, because the resin cement is applied directly through a double push syringe, additional mixing devices and applicators are not required. SpeedCEM is available in three shades, (transparent, yellow and white opaque) offering various degrees of translucency.
A 57-year-old female presented with a failing porcelain-fused-to-metal (PFM) crown on tooth No. 29 due to caries under the margin (Fig. 1). Throughout the years, the patient received regular dentistry and was in good health. Like many patients who grew up in the 1950s and 1960s, her existing direct and indirect restorations were created with a potpourri of restorative materials. The resulting mosaic was not the most esthetic smile ever seen, but both form and function were sound.
The patient’s goal was to replace tooth No. 29 with a durable restoration that would match tooth No. 28. As a clinician, my goal was to place a restoration that would be both esthetic and fracture resistant. Therefore, based on its ability to satisfy certain esthetic and functional demands, IPS e.max lithium disilicate was selected as the restorative material that would best fulfill the patient’s needs.
Preparation and provisionalization
The patient was anesthetized, and pre-operative digital photographs and a photograph of the final shade were taken. Using the Chromascop shade guide, Shade 220 was selected for the final restoration (Fig. 2). Prior to tooth preparation, a clear polyvinyl siloxane (PVS) impression of the existing restoration was made and set aside for use in fabricating the acrylic provisional restoration.
Tooth No. 29 was vital, with a composite buildup under the existing PFM crown. The old PFM crown was removed, and the tooth was prepared for a full-coverage IPS e.max lithium disilicate crown. Final occlusal reduction of 2 mm and axial reduction of 1.5 mm were accomplished using an 856-016 super coarse diamond from Axis Dental’s NTI line (axisdental.com) and finished using a similar diamond in a fine grit (Fig. 3). All sharp edges were removed, and the preparation had minimal taper.
A PVS bite registration was taken with Ivoclar Vivadent’s Virtual while the patient was sitting up. A #0 cord was placed in the sulcus, and a #1 cord was placed above it. Then, a triple tray impression of the preparation was taken using an extra light body PVS material around the tooth using a medium body PVS material loaded in the tray. The impression was inspected for accuracy and set aside.
The preparation shade was determined to be ST1. This was recorded on the laboratory prescription, along with the final shade and a shade map of the restoration (Fig. 4).
The provisional crown was fabricated using the following technique: the acrylic was placed in the clear matrix and then onto the moistened prepared tooth. After 2 minutes, the matrix was removed and the excess acrylic flash discarded. The provisional crown was allowed to set for another minute prior to removal from the matrix. A medium Soflex XT disk from 3M ESPE (solutions.3m.com) was used to trim and shape the provisional.
A brush was used to buff the provisional (Fig. 5), after which it was cemented using a dual-cure provisional cement (Ivoclar Vivadent’s Systemp.link). The occlusion was verified, and the patient was dismissed.
A week later, the patient returned for delivery and cementation of the definitive IPS e.max lithium disilicate crown restoration. The crown was inspected on the model for fit and color accuracy (Fig. 6).
01. The patient was anesthetized, and the provisional crown removed with hemostats. The preparation was cleaned with 3% hydrogen peroxide and a 0.12% chlorhexidine rinse.
02. The lithium disilicate restoration was then tried-in dry, and the margins were checked using an explorer.
03. It was determined that the transparent shade of SpeedCEM should be used for luting. The preparation then was rinsed clean with water and blotted dry.
04. The intaglio surface of the restoration was cleaned with a 35% phosphoric acid etch for 15 seconds and rinsed with water. After drying, a silane coupling agent (Ivoclar Vivadent’s Monobond Plus) was painted onto the etched surface and remained in contact for 1 minute prior to being air dried.
05. Using an automix syringe, the transparent shade of SpeedCEM was dispensed directly into the restoration (Fig. 7).
06. The crown was seated and held in place with uniform pressure using a ball burnisher and spot tacked for 2 seconds using a 2 mm tacking tip (Fig. 8).
07. Excess resin cement was light cured with Ivoclar’s bluephase® polymerization light for 1 second per quarter surface (i.e., mesio-lingual, disto-lingual, mesio-buccal, disto-buccal) at a distance of approximately 0-10 mm. The excess material then was easily removed with a scaler (Fig. 9).
08. The contacts were flossed, and Ivoclar’s Liquid Strip glycerin gel was applied to all margins before curing for 20 seconds from the occlusal, buccal and lingual aspects.
09. Using a fine finishing carbide (Axis Dental’s TDF 9), residual cement was removed from around the margins.
10. The contacts were checked with floss, and the occlusion was adjusted in MIP and all excursions. Note that the high value of the old zirconium crown on tooth No. 30 adjacent to the esthetic and life-like IPS e.max lithium disilicate crown on tooth No. 29 became more apparent (Fig. 10).
SpeedCEM was used to cement the definitive restoration based on its easy cleanup. It is user-friendly and, in many cases, the patient does not need local anesthetic at the seating appointment. When searching for an easy-to-use conventional cementation technique, the protocol outlined here is as close as you can get.
Edward Lowe, B.Sc., D.M.D., established and heads the Vancouver Centre for Cosmetic and Implant Dentistry in Vancouver, BC, Canada.
Acknowledgement: The IPS e.max lithium disilicate restoration was fabricated by Brian Lee from SmileTec Dental Lab, Vancouver, BC, Canada.