NewsletterNew materials are optimized for core build-ups and post/core restorations.
Using adhesives in core build-ups and post/core restorations can be a challenge because of the need for adequate light contact to polymerize the adhesive. This becomes increasingly problematic with deeper preparations in the posterior, where unpolymerized adhesive may contribute to marginal leakage as well as bond failure over time. Manufacturers have developed self-cure promoters that can be added to light-curable adhesives, yet these can lead to pooling of adhesive in the apical of post preparations, hampering insertion of the post to the desired depth within the tooth.
Kuraray has addressed this clinical issue with its advanced and improved single-component self-etch adhesive, Clearfil S3 Bond Plus, and Clearfil DC Core Plus dual-cure resin (Figure 1). As an alternative to using a self-cure promoter, new catalysts have been added to the adhesive and core resin, causing Clearfil S3 Bond Plus to set when Clearfil DC Core Plus contacts the adhesive. Working time is thus improved for the adhesive without compromising the bond strength.
Phase separation between the hydrophilic and hydrophobic components in an adhesive leads to blisters (micro-bubbles) within the adhesive layer, decreasing the bond strength with the dentin. Unlike most single-component self-etch adhesives, Clearfil S3 Bond by Kuraray did not undergo phase separation of the hydrophilic and hydrophobic components due to a unique proprietary technology that creates a homogeneous bond layer. This lack of phase separation in the adhesive provides superior bond strength and marginal integrity compared to similar products available.1,2 Recently, Kuraray improved the adhesive (Clearfil S3 Bond Plus) by improving the curing properties through modification of the catalysts, which yielded a subsequent increase in bond strength and decreased the amount of time needed to self-etch the surface and light-cure. The addition of fluoride provides a long-term durable bond to dentin with less technique sensitivity than other single-component self-etch adhesives.
After improving the Clearfil S3 Bond Plus adhesive, Kuraray also improved its dual-cure core resin, Clearfil DC Core Plus to offer better flow and body of the uncured resin core material. The improved body enables placement without slumping prior to light-curing, allowing the practitioner to forgo the use of a matrix in some clinical applications. The improved flow also permits its use, in combination with Clearfil S3 Bond Plus, for cementation of posts, allowing the practitioner to eliminate a separate post-luting material when placing a post/core restoration.
Core Build-ups
Improvement in bond strength has been shown when the initial layer of the dual-cure core material is 1.5 mm compared to bulk filling the preparation. After placement of Clearfil S3 Bond Plus to the dentin and prepared enamel margins with a micro-applicator, a thin layer of Clearfil DC Core Plus is placed to just cover the preparation surface. This is followed by light-curing the adhesive and initial core material layer for 10 seconds, then the remainder of the preparation is bulk filled with additional core resin and light-cured from the occlusal, buccal, and lingual to ensure complete polymerization of the resin.
Post/Core Restorations
Because of the flow properties of Clearfil DC Core Plus, this dual-cure resin may be used to lute the post into the post preparation when combined with Clearfil S3 Bond Plus adhesive, eliminating the need for a separate adhesive cement. After post preparation, Clearfil S3 Bond Plus is applied to the apical depth of the post preparation with a micro-applicator but is not light-cured at this time, to avoid the risk of pooling the adhesive apically in the post preparation, which would hamper full insertion of the post. Using the thin tip on the Clearfil DC Core Plus automix syringe, resin is placed from the apical of the post preparation to the canal orifice, coating all dentin surfaces; then the pre-fitted post is inserted to depth. The resin is then light-cured for 20 seconds, which is then followed by bulk filling the remainder of the preparation and additional light-curing from each side to ensure full polymerization of the core resin. Modification of the accelerators in the core resin decreases light-cure times compared to the previous version of the material (Clearfil DC Core Automix), with an increase in bond strength as well as flexural strength.
1. Kubo S, Yokota H, Yokota H, Hayashi Y. Three-year clinical evaluation of a flowable and a hybrid resin composite in non-caries cervical lesions. J Dent. 2010;38(3):191-200.
2. Brackett MG, Dib A, Franco G, et al. Two-year clinical performance of Clearfil SE and Clearfil S3 in restoration of unabraded non-carious class V lesions. Oper Dent. 2010;35(3):273-278.
For more information, contact:
Kuraray America, Inc.
Phone: 800-879-1676
Web: kuraraydental.com
The preceding material was provided by the manufacturer. The statements and opinions contained therein are solely those of the manufacturer and not of the editors, publisher, or the Editorial Board of Inside Dentistry.
This article was written by Gregori M. Kurtzman, DDS, MAGD, DICOI, a private practitioner from Silver Spring, Maryland.
Figure 1 Clearfil DC Core Plus is an improved dual-core resin material, and can be paired with the advanced Clearfil S3 Bond Plus self-etch adhesive from Kuraray America.
