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Scientific Journal Vol. II - 2008

SILORANE COMPOSITE SYSTEM

- Review Article

Prachi Joshi¹, Rujuta Chitnis²,

Abstract

Composite materials have been used in dental practices to restore teeth since the pioneeringwork of R. L. Bowen and the introduction of composites to the dental market in the early 1960s.Significant improvements have been made since then. Composites are an essential part oftoday’s dentistry due to their versatile clinical use and high esthetics that allow the creation ofvirtually invisible restorations. It is striking that, over the years, polymerization shrinkage has

been only incrementally reduced, and remains as one of the major drawbacks of compositematerials. Shrinkage during curing results in stress which challenges the tooth/compositeinterface. Polymerization shrinkage and the resulting shrinkage stress lead to microleakage,which is among the major factors for composite material failures in the oral environment. It’s time to face the next challenge: the fundamental improvement of the resin matrix byadvancing beyond the current methacrylate resin systems. Filtek Low Shrink Posterior

Restorative resin is based on silorane chemistry and does not contain methacrylates. The siloranering-opening monomers provide for low polymerization shrinkage. This article provides a review

on Silorane Low Shrink Posterior Restorative System.

Introduction

Adhesive dentistry has undergone evolution

since the introduction of composite materials.

Significant improvements in strength, wear-resistance, color and bonding have been made

since dental composite resins were introduced.

But the issue of volumetric shrinkage and itseffect on marginal integrity has largely gone

unresolved. Over the years, polymerization

shrinkage has been only incrementally reduced,

and remains as one of the major drawbacks of

composite materials.

Associate Professor¹, PG Student², Department of Conservative

Dentistry & Endodontics, Dr D. Y Patil Dental College & Hospital,

Navi Mumbai

Effects of Polymerization Shrinkage



Silorane Composite System ……………………………………………………………………… Prachi Joshi et al


Initially in order to reduce shrinkage, there was

increase in filler load and reduction of

methacrylate resin. However polymerizationshrinkage is an intrinsic property of resin. Upon

curing, the single methacrylate resin molecules

move towards each other and are linked bychemical bonds to form a polymer network. This

reaction leads to a significant volume

contraction.

Silorane: It's All Gain….

SILORANE system has been developed to

minimize polymerization shrinkage andpolymerization stress, while providing a high-

performance bond to the tooth.

Siloranes are a totally new class of compoundsfor the use in dentistry. The name silorane

derives from its chemical building blocks

siloxanes and oxiranes. The combination of thetwo chemical building blocks of siloxanes and

oxiranes provides the biocompatible,

hydrophobic and low-shrinking silorane base of Filtek LS Low Shrink Posterior Restorative.This innovative resin matrix represents the

major difference of Filtek LS restorative

compared to conventional methacrylates. Also,the initiating system and the filler were adapted

in order to provide the best performance of the

new technology.

Chemistry

As silorane-based composite polymerizes, “ring-

opening” monomers connect by opening,

flattening and extending towards each other. Theresult is significantly less volumetric shrinkage

compared to methacrylate-based composites. As

methacrylate-based composites cure, themolecules of these “linear monomers” connect

by actually shifting closer together in a linear

response. The result is a loss of volume.

SILORANE





METHACRYLATE

Initiator System

This consists of camphorquinone, iodonium salts& electron donors and reactive cationic species.

Filler Component

This consists of fine quartz particles and

radiopaque yttrium fluoride.

ADHESIVE SYSTEM

Two-step adhesive

Self-Etch Primer : HydrophilicHelps in adhesion to the tooth

Bond : Hydrophobic

Helps in adhesion to silorane system

hydrophilic hydrophobic

Tooth Filtek

Silorane

1x

SiloraneSystem Adhesive

Primer

1x

Silorane SystemAdhesiveBond

Self-Etch Primer

Composition: Phosphorylated methacrylates

Vitrebond copolymer BisGMA , HEMA

Water , Ethanol Silane-treated silica filler : 7 nmPhotoinitiator : Camphorquinone Stabilizers

Refrigeration required: To prevent loss of water

and ethanol pH : 2.7 – provides mild etchingand demineralization of tooth structure

Adhesive Bond

Composition : Hydrophobic dimethacrylatePhosphorylated methacrylates TEGDMA

Silane – treated silica filler

Photoinitiator : Camphorquinone Stabilizer

Mechanism Of Chemical Bonding Between

Adhesive Bond And Silorane





Indications

Low Shrink Posterior Restorative System, is a

system for direct, posterior restorations. It can be

used for the following posterior restorations:Class I

Class II

This system may be used together with glassionomer cements or resin-modified glass

ionomer cements, as cavity liners or bases.

Shades

Low Shrink Posterior Restorative composite isoffered in the following shades : A2, A3, B2 and

C2

Advantages

1) The first composite to shrink less than 1%

2) Strong and durable

3) Low water sorption leading to decreasedexogenic staining

4) Radiopaque

5) Up to 9 minutes operatory light stability

6) Easy to handle, nonsticky & excellent abilityto hold shape

7) Dedicated self-etch adhesive with excellent

bond strength8) Excellent marginal integrity

Conclusion

Low Shrink Posterior Restorative System

represent the next generation of restorativefilling materials, combining esthetics with

excellent mechanical properties. This scientificbreakthrough is the long-awaited solution that

combines lowest volumetric shrinkage withbiocompatibility. We are now probably looking

at a REVOLUTION in direct filling therapy, as a

new matrix based on Silorane chemistry seemsvery promising.

References

1. www.mmm.com (3M ESPE website)

2. Properties of silorane-based dental

resins and composites containing astress-reducing monomer: Dental

Materials, Volume 23, Issue 8, Pages

1011-1017J. Eick, S. Kotha, C. Chappelow, K.

Kilway, G. Giese, A. Glaros, C. Pinzino

3. Siloranes in dental composites: Dental

Materials, Volume 21, Issue 1, Pages

68-74

W.Weinmann, C.Thalacker,R.Guggenberger

4. Incremental layers bonding of siloranecomposite: The initial bonding

properties: Journal of Dentistry, Volume

36, Issue 7, Pages 560-563

A. Tezvergil-Mutluay, L. Lassila, P.Vallittu

5. Comparison of the hybrid layer formedby Silorane adhesive, one-step self-etch

and etch and rinse systems usingconfocal micro-Raman spectroscopy and

SEM: Journal of Dentistry, Volume 36,Issue 9, Pages 683-691

A. Santini, V. Miletic

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