Rubber Dam Isolation: Maximizing Bond Strength to Enamel

By: Christopher Mazzola, DDS
Topic Originally Appeared on PankeyGram.org. Dr. Mazzola granted permission for igniteDDS to share with our readers.

Advantages of Utilizing Rubber Dam 

Rubber dam isolation has a lot of advantages to be used in dentistry, that are supported with many clinical studies. By making our everyday procedures easier, without having to worry about the surrounding tissues, saliva, and blood, the rubber dam provides an ideal dry field.

Although the benefits of using rubber dams were already well known, the findings of many clinical studies guide us in the decisions we make when performing treatments our patients are counting on to be long-lasting. 

Dr. Markus Blatz is the co-founder and past President of the International Academy for Adhesive Dentistry (IAAD) and Chairman of the Department of Preventive and Restorative Sciences at the University of Pennsylvania School of Dental Medicine. He and his research team aimed to test two essential hypotheses in adhesive dentistry, that were supported by the results reported in the Journal of Esthetic and Restorative Dentistry in November of 2022. 

Hypothesis 1: Rubber dam isolation improves sheer bond strength independent of the adhesive system used. 

Hypothesis 2: A highly filled 3-step etch and rinse adhesive will provide higher bond strength values than an isopropyl-based universal adhesive. 

To test these hypotheses, the research team used two adhesive systems: 

1. OptiBond FL from Kerr, a 3-step etch and rinse adhesive
2. Prime & Bond Universal Adhesive, an isopropyl-based universal adhesive

The mesial, distal, lingual, and vestibular enamel surfaces of 30 human third molars were prepared (total n = 120 surfaces). A custom splint was made to fit a volunteer’s maxilla, holding the specimens in place in the oral cavity. Four composite resin cylinders were bonded to each tooth with one of two bonding agents (OptiBond FL and Prime & Bond) with or without rubber dam isolation. Shear bond strength was tested in a universal testing machine and failure modes were assessed. 

Key Findings of This Study 

• Enhanced Bond Strength with Rubber Dam: Rubber dam isolation significantly improved the performance of both adhesives, approximately twice the shear bond strength compared to procedures without a rubber dam.
• Highest Mean Bond Strength of Optibond FL: The 3-step OptiBond FL system resulted in a more resilient bond, particularly when combined with rubber dam isolation, than the Prime & Bond Universal adhesive. 
• Fracture Modes: Specimens bonded without rubber dam isolation showed adhesive and cohesive fractures within enamel. In contrast, those bonded with rubber dam isolation exhibited only cohesive fractures.

For the benefit of our patients, we shouldn’t cut corners that will impact the longevity of a restoration. Whenever we have basic pure enamel bonding it should be under a rubber dam, using a total etch, 3-step adhesive system. But considering dentin likes to be moist, we may need to make other clinical judgments.  

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