September 1, 2001
by Leny Sferlazza, BSc, DDS, FAGD
The past decade has witnessed sophistication in the quality of aesthetic simulation of natural tooth structure that is unprecedented. The impact of new generation porcelain fused to metal, all ceramic, and resin restorations has added immeasurably to the cosmetic service mix provided by the practitioner.
The introduction of the Aestheti-Plus post (the Aestheti-Plus post is an evolution of the original carbon fiber post Composipost from RTD Grenoble, France) for coronal- radicular rehabilitation has obviated the deficiencies inherent in traditional systems. The post is composed of unidirectional, pre-tensed quartz fibers bound in an epoxy matrix. The characterization of the final restoration is significantly enhanced as the white color of the Aestheti-Plus post negates the need for opaquing under the new generation porcelain anterior crowns. In addition, the modulus of elasticity (structural rigidity) of the Aestheti- Plus post (15-40 Gpa) is close to dentin and composite (20-60 Gpa) and as such the potential for root fracture is significantly diminished in contrast to that of most metal posts (110 – 200 Gpa – titanium – stainless steel).
Studies have been performed using intermittent loading testing simulating the recurrent forces of mastication at a rate of 1800 cycles per minute, for as many cycles as it takes for the post to fail. The Aestheti-Plus post demonstrated a fatigue factor resistance of as great as 6 to 1 in comparison to metal and other non-metallic posts.1
The primary purpose and main indication for a post is to retain a core that can be used to support the final restoration. Posts do not reinforce endodontically treated teeth, and a post is not necessary when substantial tooth structure is present after a tooth has been prepared.2 The use of Quartz fiber materials offers substantive further advantage. The tensile strength of Quartz fiber is greater than titanium and stainless steel by a factor of 3 to 1 (2900 Mpa to 1000 and 800 Mpa respectively).
In a study of the fracture resistance of teeth restored with RTD fiber posts,3,4 Purton and Payne reported that tooth fractures were uncommon and that the most frequent site of failure was the post and core interface. The epoxy resin used in both the Composipost and the Aestheti-Post is chemically similar to BIS-GMA resin used in most adhesives. This is significant in that resin cements and core composites demonstrate equivalent modulus of elasticity (20-60 GPa). The fact that the resin, cement, adhesive and core are all virtually insoluble in oral fluids, contributes to a resistance to de-bonding (0.0051%) that lasts for years in clinical trials. The root is usually not damaged and the remaining tooth structure can be salvaged. By contrast, in teeth restored with a cast-post and core, fracture of the root was observed in 91% of the specimens.5,6,7
The patient presented with tooth #2.2 fractured supragingivally (Fig. 1). Radiographic examination revealed a successful endodontic procedure had been performed on the tooth (Fig. 2). The treatment plan proposed included a post/core rehabilitation of the lost coronal tooth structure and a full coverage restoration.
The removal of the coronal gutta-percha was initiated with the #70 torpan (green ring) supplied with the Aestheti-Plus System (Fig. 3). The torpan is designed with a safe end that negates the possibility of iatrogenic perforation.
The lead channel was prepared with the first stage reamer to the desired length of the post channel (7-8mm). The root canal space was then further enlarged with the second stage reamer to make room for the wider portion of the post.
The canal was cleansed with 5.25% sodium hypochlorite, rinsed with water for 30 seconds and air dried with a Stropko irrigator (Spartan/Obtura St. Louis, MO) and Ultradent microtip (UDP South Jordan, UT). The selected post was fit into the prepared canal (Fig. 4) and a radiograph taken to determine accuracy of fit (Fig. 5).
The canal was etched with 37% phosphoric acid (UDP South Jordan, UT) for 15 seconds, rinsed with water and air dried as indicated previously. DiamondBond A & B dentin primer was applied and dried with gentle air blasts. The DiamondBond (Base & Catalyst) self-cure dentin resin was then applied to the walls of the post channel and the post and thinned out with an air stream from the Stropko irrigator. The dual-cure luting cement, DiamondLink (Base and Catalyst) was injected into the canal. The Aestheti-Plus post (Biodent Montreal, QC) was passively inserted into the canal using slight pressure.
Excess surface composite was removed using a rubber tip and the post held in place with finger pressure. The self-cure completes in approximately 2.5 minutes. The excess post extension was removed with a diamond-separating disc (Fig. 6) and the core constructed using DiamondLite composite (Fig. 7). The tooth was prepared for the final restoration (Fig. 8).
The carbon fiber post and the quartz fiber post are reported to have a modulus of elasticity nearly identical to dentin resulting in less stress on tooth structure and thereby reducing the incidence of root fracture. It is corrosion and fatigue resistant, and biocompatible with the properties of the natural tooth. The Aestheti-Plus System offers a safe and retrievable method for the inclusion of a non-metallic post in coronal-radicular rehabilitation. The features of this system facilitate the achievement of a more pleasing and aesthetic restoration.OH
Leny Sferlazza, BSc, DDS, FAGD maintains a private practice in aesthetic/restorative dentistry in Mississauga, Ontario.
Thanks to Dr. Ken Serota for his support and assistance with the preparation of the manuscript.
Oral Health welcomes this original article.
1.Lsidor F, Odman P. BrondLtrn K. Intermittent loading of teeth restored using prefabricated carbon fiber posts. Intl Prosthodont 1996:9:131-6.
2.American Association of Endodontics Website — www.aae.org — Colleagues for Excellence: Restoring Endodontically Treated Teeth Fall/Winter 1995.
3.Dean JP, Jeansonne BG, Sarkar N. In Vitro Evaluation of A Carbon Fibre Post. J Endodon 24(12) Dec 1998.
4.Martinez-Insua A, DaSilva L, Relo B, Santana U. Comparison of the fracture resistance of pulpless teeth restored with a cast post and core or carbon-fibre with a composite core. The Journal of Prosthetic Dentistry, 80(5) Nov 1998.
5.Purton DG, Payne JA. Comparison of carbon fibre and stainless steel root canal posts. Quintessence Int. 27:93(7)1996.
6.Fredriksson M, Astback J., Pamenius M, Arvidson K. A retrospective study of 236 patients with teeth restored by carbon fibre-reinforced epoxy resin posts. The Journal of Prosthetic Dentistry. 80(2)Aug1998.
7.Glassman, G, Serota, K, Soll, J. A new method for the restoration of the endodontically treated tooth: The Luscent Anchor System. Oral Health, Dec 1999.
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