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Sandwich Technique

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Outline

• Introduction• Types• Technique• Indications and Contraindications• Advantages and Disadvantages• Conclusion• References

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What is sandwich?• Something resembling a sandwich; especially composite structural material consisting of layers often of high-strength facings bonded to a low strength central core.

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• A restoration in a tooth in which two restorative materials are used that are chemically bound together.

• Here, a glass-ionomer or flowable composite material is used as a liner under some composite restorations.

Introduction

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Types• Closed sandwich technique: The underlying

material does not come into contact with the oral cavity.

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• Open sandwich technique: Usually used for Class II restorations where the underlying material forms part of the axial wall and is exposed to the oral environment.

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Glass Ionomer Cement

• Benefits as a liner: –Bonds both to the tooth structure and the

composite, increasing retention form and providing better seal when used at non- enamel margins.– Fluoride in the GI material reduces

potential for recurrent caries.

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Flowable Composite• Benefit as a liner:–Acts as a shock absorber, distributing

stresses applied to the more rigid composite–May reduce some of the negative effects of

polymerization shrinkage.

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Indications of Sandwich Technique

• Lesions where one or more margins are in dentin-like cervical lesions (class V)

• Class II composite restorations• When any part of the gingival margin of class II

preparation has been extended past the CEJ, and no longer has an enamel cavo-surface

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How to do the Sandwich Technique

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1. Prepare Class I/II cavity

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2. Condition the dentin and enamel surfaces using an acid conditioner (preconditioning)

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• Function of conditioner: –Creates stronger bond between tooth and

GIC–Removes smear layer and debris from tooth

surface • Citric acid and polyacrylic acid have been

used as conditioners.

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3. Place an increment of GIC over the cavity floor, extending up DEJ around the perimeter of the preparation, or just short of the cavo-margin at the base of proximal box (In Class II)

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4. Etch the enamel and GIC

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5. Apply bonding agent

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6. Light cure and apply composite resin in increments

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7. After finishing and polishing…

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Conclusion

• It is recommended that the sandwich technique be the restoration of choice when proximal gingival margins extend beyond the cementoenamel junction.

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References

• Art and Science of Operative Dentistry - Studervant – page 304

• http://pocketdentistry.com/9-the-tooth-coloured-restorative-materials-iii-glass-ionomer-cements/

• Liebenberg W.. Return to the Resin-Modified Glass–Ionomer Cement Sandwich Technique; JCDA 2005; 71(10): 743-747.

• http://www.merriam-webster.com/dictionary/sandwich