Metal-free root canal pins – a good option? EADT eV

When is a root post needed?

This depends primarily on the extent of the remaining hard tooth structure and thus the extent of the destruction. In addition, a post for the build-up filling must offer sufficient retention (Edelhoff 2003) and transmit the chewing forces axially. For example, in the case of premolars, a post should be inserted if only one or no cavity wall remains. If there are two or more sufficiently sized cavity walls, a pin is usually not necessary (Mangold 2011). Thanks to the adhesive technology, many construction options are available that no longer necessarily require the use of a pen (Edelhoff 2003). This means that work can be done in a more minimally invasive manner. Risks such as B. root fractures or perforations are avoided (Edelhoff 2003). It is important to ensure that there is a sufficient “ferrule” effect (barrel hoop effect).

What advantages do metal-free pens offer?

Prefabricated direct metal-free posts with a plastic composite structure offer the dentist better flexibility during treatment. The pins can be placed relatively inexpensively within one treatment session before preparation. In addition, minimally invasive tooth-colored restorations provide excellent aesthetics. Another advantage: Metal-free pins show no biomechanical degradation or corrosion (Sipahi 2014).

Metal-free – Which materials are most commonly used?

Zirconia posts or quartz/glass fiber reinforced posts are the most commonly used metal-free ready-made posts (Goracci 2011, Baba 2009). Compared to zirconium oxide posts, fiberglass-reinforced posts have the advantage of a modulus of elasticity that is comparable to that of human dentin.

How is a metal-free post attached to the root canal?

For sufficient retention of the post, a luting material is required that creates a good bond between the post surface and the root dentin (Jongsma 2010). According to studies, a loss of this adhesive force (“debonding”) is the main cause of pin failure (Bolla 2007, Cadidiaco 2007, 2008, Dietschi 2007, 2008, Ferrari 2007). The use of traditional cements should be limited to metal-based posts. Metal-free pins should only be attached adhesively (Ferrari 2001, Monticelli 2008). Here you can choose between conventional and self-adhesive luting composites. Since complete light curing cannot be ensured in the apical area of the inserted post, dual or purely chemical curing luting composites are the prerequisite for a secure bond (Ferrari 2001, Monticelli 2008, Goracci 2008). The bond strengths of self-adhesive luting composites are reduced in contrast to conventional luting composites. However, handling is much easier and time-saving because no pretreatment of the dentin walls is necessary. For these reasons, this group of fastening materials is predominantly used in practice.

Metal-free prefabricated pins have long been an alternative to both prefabricated metal pins made of titanium and cast post abutments. The reasons for the increasing acceptance of metal-free prefabricated pins are aesthetic and practical aspects (Goracci 2011). Especially with tooth-colored restorative materials, a metal post can lead to aesthetic problems, e.g. B. at the transition between red and white aesthetics or when covering the darkly discolored tooth stump.

Study

Scientific study of various metal-free fiber optic pins

Study structure

The presented study was intended to determine the tensile load (ZB) and tensile strength (ZF) of five fiberglass post systems that were attached to the dentin in the root canal. A total of 120 caries-free premolars, canines and upper central incisors were assigned to five different fiberglass post systems (n=24):

1) RelyX Fiber Post 3D (3M),

2) RelyX Fiber Post (3M),

3) LuxaPost (DMG GmbH),

4) FibreKleer 4X Tapered Post (Pentron) and

5) ParaPost Taper Lux (Coltѐne/Whaledent).

The fastening methods and plastic structures were made using the products recommended by the manufacturer. All samples were then stored in water at 24 °C for 37 hours. Tensile load and tensile strength were tested on half of the samples (n=12/group) immediately after storage in water. The other half was further stored with thermal cycles in a water bath (10.000 × 5 °C/55 °C) and then measured. The tensile load could be measured directly and the tensile strength could be calculated using the bond surface.

Results

The measurements with FibreKleer 4X Tapered Post and LuxaPost showed the lowest average tensile load values, which, however, did not differ significantly from the values with RelyX Fiber Post and RelyX Fiber Post 3D. The highest tensile load and tensile strength values were observed for ParaPost Taper Lux, but these were in the same statistical subset as RelyX Fiber Post 3D and RelyX Fiber Post. The thermal load change had no influence on the results.

Conclusion and clinical relevance

ParaPost Taper Lux, RelyX Fiber Post and RelyX Fiber Post 3D, together with an adhesive core structure, were able to achieve the highest bond strength to human dentin. The tensile load and tensile strength parameters showed the same trends and statistical significance. The data obtained in this in vitro study and further confirmation from clinical studies make Parapost Taper Lux, RelyX Fiber Post and RelyX Fiber Post 3D a good option for clinical use.

Study listed: Keul C, Köhler P, Hampe R, Roos M, Stawarczyk B. Glass Fiber Post/Composite Core Systems Bonded to Human Dentin: Analysis of Tensile Load vs Calculated Tensile Strength of Various Systems Using Pull-out Tests. Journal of Adhesive Dentistry. 2016;18(3):247-56. doi: 10.3290/j.jad.a36136.

Authors: Anja Liebermann, Annett Kieschnick, Bogna Stawarczyk

Metal-free root canal pins. A good option for everyday clinical practice?

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