Clinical Application of a New Self-Adhesive Resin Cement for Zirconium-Oxide Ceramic Crowns

Several new materials and technologies have demonstrated tremendous impact on clinical dentistry and have revolutionized traditional restorative treatment concepts. For example, zirconium-oxide ceramics have fundamentally changed clinical applications and the range of indications of all-ceramic restorations, from single-tooth crowns to full-mouth implant-supported rehabilitations.^1-3 Recent clinical studies reveal favorable success rates of zirconia crowns,⁴ which can be cemented conventionally with traditional cements. However, the clinical success of all-ceramic restorations can be influenced by the type of luting agent and technique applied for definitive cementation.^5-7

Composite resin luting agents and compatible bonding systems increase retention and improve marginal seal and fracture strength of all-ceramic restorations.^5-8 In general, compressive and tensile strength, toughness, and resilience of composite resin cements equal or exceed those of other luting agents. Solubility is low and esthetic qualities are excellent. Pretreatment with hydrofluoric acid and silanization enhance resin bonds to silica-based ceramics.⁵ However, alternative materials and pretreatment steps are necessary to achieve long-term durable bond strengths to non-silica, high-strength ceramics such as zirconia.^5-8 Airborne-particle abrasion seems the most practical and effective pretreatment to enhance resin bond strengths to zirconia.^5-7,9,10 Numerous studies have confirmed that ceramic primers (eg, Clearfil™ Ceramic Primer, Kuraray America, Inc., www.kuraraydental.com) and resin cements (eg, Panavia™ 21 and Panavia™ F 2.0, Kuraray America, Inc.) that contain the adhesive monomer 10-methacryloyloxydecyl dihydrogen phosphate (MDP) provide superior and long-term durable resin bonds to zirconia.^5-7,9-13 Such high bond strengths are especially necessary for restorations that completely rely on resin bonding, such as resin-bonded fixed partial dentures (RBFPD).¹⁴

The need for priming and bonding agents for both tooth- and restoration-bonding surfaces, however, makes the proper application of resin cements a time-consuming and technique-sensitive, multiple-step procedure. In addition to these shortcomings, dental practitioners have demanded more user-friendly protocols and materials. Consequently, self-adhesive resin cements, which are based on the chemistry of resin cements and self-etching adhesives, were recently developed.¹⁵ Self-adhesive resin cements provide good bond strengths to tooth structures and restorative materials without pretreatment or bonding agents. Their application can be accomplished in a single clinical step, similar to cementation procedures with conventional luting agents. Besides simplified application techniques, they seem less susceptible to moisture contamination and cause little postoperative sensitivity.¹⁶ Self-adhesive resin cements are indicated for adhesive cementation of virtually all indirect dental materials and have, therefore, gained immediate market acceptance and great popularity among dental clinicians in a very short time.^15,16

The new self-adhesive resin cement, Panavia™ SA Cement (Kuraray America, Inc.) replaces the original version of Clearfil SA Cement and is a dual-cure and fluoride-releasing, one-step cementation material that provides excellent bond strengths to tooth structures (dentin and enamel) and dental materials. It is indicated for definitive cementation of all indirect restorations and materials, including metal alloys (eg, cast gold and porcelain-fused-to-metal [PFM]), high-strength ceramics (eg, alumina and zirconia), and silica-based ceramics, such as leucite-reinforced ceramics (eg, IPS Empress^®, Ivoclar Vivadent, www.ivoclarvivadent.us) and lithium disilicate (eg, IPS e.max^®, Ivoclar Vivadent). Clinical indications comprise full-coverage crowns, fixed-partial dentures (FPDs), inlays and onlays, endodontic posts, and implant-supported restorations. Panavia SA Cement also contains the functional adhesive monomer MDP, which, among other features, provides excellent bond strengths to high-strength ceramics. It is, therefore, an ideal luting agent for alumina and zirconia restorations. Airborne-particle abrasion with aluminum oxide (Al2O3) is recommended to further enhance bond strengths to high-strength ceramics.^15,17

Panavia SA Cement is currently offered in two application formulas: automix and handmix (Figure 1). The automix version is directly applied from the syringe through a mixing tip into the restoration for easy and fast cementation. A special “Endo tip” allows for controlled cement application into an endodontic canal for post cementation. The handmix version provides enhanced control over the mixing procedure and reduces material waste. One of the most striking features over comparable products is the fast and simplified cleaning process, which is carried out after an initial “tack” light-cure step following seating of the restoration. Panavia SA Cement is also called the “everyday Panavia” due to its simplicity and wide range of indications. However, comprehensive multiple-step composite-resin luting systems (eg, Panavia 21, Panavia F 2.0, or Clearfil Esthetic Cement), along with the suggested bonding and priming agents, are still the materials of choice for adhesive restorations, such as laminate veneers and RBFPDs.

A 24-year-old woman presented to the authors’ clinics seeking esthetic treatment of her insufficiently restored maxillary central incisors (Figure 2). Her medical history was unremarkable, and her past dental history included orthodontic treatment for several years, routine recall visits, and minor operative dentistry. Extraoral findings were normal. Intraoral and radiographic findings revealed no caries, except in the marginal areas of the extensive composite restorations on the maxillary central incisors. Soft tissues were generally normal and healthy. A gingival asymmetry was present, with a recession and thin-tissue morphology on the left maxillary central incisor. The patient was unhappy with the shade and the shape of her maxillary central incisors, especially the unilateral gingival recession and the uneven incisal edges (Figure 3). Due to the limited space and persistent crowding, with the maxillary lateral incisors in a retruded and the central incisors in a slightly protruded position, orthodontic tooth repositioning and alignment was recommended as the initial and most important treatment step. The uneven gingival levels and thicknesses would have also been corrected through proper orthodontic alignment, however the patient adamantly refused orthodontic treatment.

The initial treatment phase included removal of the failing composite restorations in the maxillary central incisors, revealing severe destruction of these teeth. Preliminary crown preparations were carried out, and provisional restorations made from acrylic were inserted (Figure 4). The provisional crowns were used to idealize prospective tooth proportions, lengths, and position of the incisal edges. The margins of the previous restorations determined the position of the preparation finish line, which was located more apically on the left than on the right maxillary central incisor. A connective-tissue graft was harvested from the palate and placed in a split-thickness gingival pouch on the labial aspect of the left maxillary central incisor to create more even gingival margins and a “cushion” of increased soft-tissue thickness to limit further gingival recession (Figure 5). After 6 months of healing and soft-tissue maturation, the crown preparations were finalized (Figure 6) and a final impression was made. The definitive crowns (Figure 7) were fabricated with zirconia copings (Katana, Kuraray America, Inc., www.kuraraydental.com) veneered with a compatible and proven veneering porcelain (Noritake CZR, Kuraray America, Inc. ).¹⁸ Prior to cementation, the intaglio surfaces of the crowns were pretreated with airborne particle abrasion (60 μm Al2O3 particles) (Figure 8), and the Panavia SA cement automix was directly dispensed into the restorations (Figure 9). After seating of the crowns on the preparations, the cement was tack-light-cured for 5 seconds (Figure 10). While complete polymerization of the cement takes approximately 5 minutes from the time of seating the crown, excess cement can already be removed after the light-curing step (Figure 11). Figure 12 and Figure 13 reveal the final postoperative situation.

Reliable cementation protocols and materials are fundamental for clinical success of indirect dental restorations, especially those made from all-ceramic materials. Modern self-adhesive resin cements combine bonding abilities and material advantages of composite-resin luting agents with the simplified one-step clinical protocol of conventional cements. Panavia SA Cement is a new fluoride-releasing, dual-cure self-adhesive cement. Its specific composition and special adhesive monomer (MDP) provide excellent long-term adhesive bonds to high-strength ceramics and make it ideal for final insertion of full-coverage zirconia restorations. Additional primers or bonding agents are not required, and the post-cementation cleaning process is remarkably easy and fast.

Dr. Blatz has received support from Kuraray America, Inc. for this manuscript.

Markus B. Blatz, DMD, PhD
Professor of Restorative Dentistry and Chair
Department of Preventive and Restorative Sciences
School of Dental Medicine
University of Pennsylvania
Philadelphia, Pennsylvania

Michael Bergler, MDT
Director, CAD/CAM Ceramic Center
Department of Preventive and Restorative Sciences
School of Dental Medicine
University of Pennsylvania
Philadelphia, Pennsylvania

Related content: For more information, read Zirconia: A Proven, Durable Ceramic for Esthetic Restorations at dentalaegis.com/go/cced262