The Sandwich Restoration Dental Technique

The sandwich restoration dental technique was developed by McLean and Wilson in 1977. The technique was called “sandwich” because the finished product resembles it. As with the two pieces of bread, we have composite resin above and the tooth structure below; meanwhile in between them is the resin-modified glass ionomer. The purpose of the procedure is to combine the advantages of glass ionomer fillings and composite resin to achieve better results. 

In this blog, we will explore the sandwich technique: the different types and materials used, its benefits, and the clinical steps involved.   

What Is the Sandwich Technique in Dentistry?  

The sandwich technique is a restorative treatment, also known as the layering technique, that combines the advantages of restorative materials, such as glass ionomer fillings, dental adhesive, and composite resin. These are then placed in layers as in a “sandwich.” Thus, it is used when the preparation of the tooth extends beyond the enamel to the dentin and cementoenamel junction. 

What Are the Various Types of the Sandwich Restorative Technique? 

There are two commonly used types of sandwich restorative techniques: the closed sandwich technique and the open sandwich technique.  

• Closed Sandwich Technique: In this technique, the underlying glass ionomer cement does not come in contact with the oral cavity because above it a layer of composite is applied. 
• Open Sandwich Technique: In this technique, the underlying material forms a part of the axial wall and is exposed to the oral cavity, usually found in class II and class III restorations. The glass ionomer in the open technique is used to replace the dentin as well as fill the cervical area of the tooth, thus exposing a part of it to the oral cavity. When there is no more enamel at the gingival margin, this approach is used (Ian Shuman, 2017). 

 What Are the Layers Involved in the Sandwich Technique?  

The sandwich technique consists of three layers: 

• The first layer is the dentin replacement layer, which provides the foundation and adhesion to the tooth structure. 

• The middle layer is the reinforcement layer, which offers strength and resilience to withstand occlusal forces. 

• The final layer is the enamel layer, which provides excellent esthetics that closely mimic the appearance of natural tooth enamel. 

What Are the Indications for the Sandwich Technique?

• Lesions where one or more margins are in the dentin, such as cervical lesions (class V restorations). 

• Lesions in the interproximal area (class II and class III). 

• When the gingival margins of class II restorations have been extended past the cementoenamel junction and no enamel remains (CEJ). 

• Deep posterior restorations (class I). 

Read more: Posterior Restorations: Materials & Techniques and Patient Care 

What Materials Are Used in the Sandwich Technique? 

• EQUIA Forte® HT, a biocompatible bulk-fill glass-hybrid restorative, is placed on the floor of the tooth cavity. It is a glass hybrid that combines physical properties, such as high compressive strength, translucency for natural esthetic tooth results, and superior fluoride release, which prevent recurrent carious lesions in high-risk patients. The simplified procedure and a flip-top coat bottle design, provides ergonomics and a more efficient use of time and materials. 
• G-Premio BOND™ is a single-component light-cured adhesive. It is a universal eighth-generation bonding agent that is compatible with all etching techniques and provides excellent versatility. Despite the use in direct restorations, it has a low film thickness (three microns), which enables its use in indirect restorations. 
• GC Fuji II LC® is a light-cured resin modified glass ionomer. It provides excellent flexural strength and bond strength to teeth even in the presence of saliva. The ionomer is a fantastic choice for class V restorations, cervical erosions abfraction lesions, and as a liner/base. Its continual rechargeable fluoride release helps strengthen the tooth structure. 
• G-ænial Sculpt® is a universal nano hybrid composite. It is easy to shape, sculpt, and polish. It ensures strong and wear-resistant restorations with beautiful esthetics. 

What Are the Advantages of the Combined Materials? 

• Glass ionomer cement’s biocompatibility, fluoride release, dentin bondability, and marginal integrity are excellent;  
• Composite resin has excellent flexural and bond strengths  , with high polishability  and esthetically properties. 
• Therefore, the combined glass ionomer- resin composite restoration provides a reliable bond to tooth steructure and an acceptable esthetic result (Suzuki M, 1999). 

What Are the Advantages of the Sandwich Technique? 

The sandwich technique has various advantages over others because it combines favorable characteristics from both materials. Some of these advantages are as follows: 

• Lower polymerization shrinkage. 

• It has a favorable pulpal response. 

• It chemically bonds to the tooth. 

• Fluoride release from glass ionomer materials 

How Is the Sandwich Technique Performed? 

After determining the patient requires the sandwich technique, start preparing the  tooth cavity beyond the margins of enamel and down to the dentin and cementum.  

Isolate the tooth and create a dry field by using a rubber dam. If there is a class II cavity, use a matrix that helps to create the axial wall of the tooth. After this, the procedure can commence. 

• Pre-condition the tooth surface: Precondition the dentin surface to remove the smear layer and debris of the dentin, which creates a stronger bond between the tooth and glass ionomer filling. Wash the conditioner away and leave the tooth slightly moist. 
• Place the glass ionomer or glass hybrid: EQUIA Forte® HT or GC Fuji II LC® have amazing physical properties, excellent strength, and superior fluoride release, which make them the perfect choice for patients with high caries risk.  
• Etch the tooth structure and glass ionomer filling with 37% phosphoric acidmto improve the mechanical bond to the glass hybrid material.   
• Use a bonding agent: Apply a thin layer of bonding agent with a micro brush. The G-Premio BOND™ is a perfect choice for an effective and long-last bonding. 
• Place the composite :  The nanoparticulated composite  G-ænial Sculpt®, is highly esthetic, and has wonderful physical properties.  
• Finish and polish: polish the restoration with a low RPM handpiece and a fine diamond finishing bur.