Protecting the Pulp in Deep Class I and II Restorations
Calcium- and fluoride-releasing liner and base materials offer protective benefits
Daniel H. Ward, DDS
When preparations are deep enough to approximate the pulp, pulpal protection is necessary to maintain the vitality of the tooth and provide comfort for the patient. Materials such as liners and bases have been developed to serve this function, and they have been shown to reduce the risk of gap formation, microleakage, and bacterial invasion.1 To further protect the integrity of teeth restored in this manner, dentists are increasingly using liners and bases that are designed to release and recharge beneficial ions. Research has demonstrated that calcium-releasing materials provide a strong antibacterial affect, assist in dentin remineralization, and act as a protective barrier.2 In addition, they have been shown to stimulate reparative dentin formation and reduce the likelihood of recurrent decay.3 This article presents two cases that demonstrate the use of such materials in the placement of Class I and Class II restorations.
Case Report 1
The patient in this first case presented to the office with deep occlusal caries (Figure 1). After access was achieved through the enamel, the visible decay was quickly removed. A round bur was then used at a slow speed to remove the final decay (Figure 2). Following debridement, the preparation was irrigated with chlorhexidine, and when it demonstrated the proper level of moisture, a layer of a dual-cure, calcium- and fluoride-releasing, hydrophilic, self-adhesive liner and base material (TheraBase®, BISCO) was placed at the bottom of the preparation and light cured for 20 seconds (Figure 3).
In addition to its excellent physical properties and bond strength to dentin, this material was selected for its ability to release and recharge calcium and fluoride ions4 and provide an alkaline pH within minutes of application. Because it employs a self-etching, self-adhesive mechanism, no separate etching and rinsing step is necessary, which reduces the risk of postoperative sensitivity. Furthermore, many dentists are not aware of the deleterious effects of the heat produced when clear bonding agents are placed near the pulp and light cured. This can increase pulpal temperatures and, subsequently, the chance of pulp irritation.5 This base material's self-adhesive property eliminates the need for a bonding agent in deep areas, and it's opaque, so it covers and protects deep dentin during curing.
Once the base layer was polymerized, the enamel was etched (Uni-Etch® w/BAC, BISCO) for 20 seconds and then thoroughly washed and dried. A universal bonding agent (All-Bond Universal®, BISCO) was then applied for 20 seconds, the solvent was evaporated, and it was light cured. To complete the restoration, a nanohybrid universal composite resin (Harmonize™, Kerr Dental) was placed, shaped, and light cured. The occlusion was then adjusted, and the restoration was finished and polished (Figure 4).
Case Report 2
When the patient in this second case report presented for a recare appointment, significant interproximal decay was observed radiographically. The patient was anesthetized, and the decay was thoroughly excavated (Figure 5). After the preparation was complete, a layer of a light-cure, resin-modified calcium silicate (TheraCal LC®, BISCO) was placed into the deepest area as a protective liner (Figure 6). This material's unique hydrophilic chemistry is alkaline, which promotes healing and apatite formation.6-8 It is recommended for use when in close proximity to the pulp. Once placed, the calcium silicate liner was light cured, and then a thicker layer of the dual-cure, calcium- and fluoride-releasing self-adhesive liner and base material was placed and light cured (Figure 7).
With the pulp protected, a sectional matrix (Composi-Tight® 3D Fusion™, Garrison Dental Solutions) was placed to ensure an effective, predictable, and anatomic interproximal contact (Figure 8). The preparation was then acid-etched, washed thoroughly, irrigated with chlorhexidine, and brought to the proper moisture level. Next, the universal bonding agent was placed and scrubbed for 20 seconds, the solvent was evaporated, and it was light cured. To complete the restoration, a bulk-fill posterior composite restorative (SonicFill 3™, Kerr Dental) was selected for ease of use and to reduce the likelihood of void formation between layers. Once placed, a high-powered curing light (VALO™, Ultradent) was used on the occlusal surface of the restoration for two separate 20-second cures. The retainer was then removed, and the wings of the matrix were bent outward to allow access to the buccal and lingual surfaces for additional light curing. For this step, a second high-powered curing light (PinkWave™, Vista Apex) was added, and both lights were simultaneously activated for 20 seconds. The matrix was then removed, and once again, both lights were activated. After the restoration was adjusted, shaped, and polished, it was postcured for an additional 20 seconds to ensure complete polymerization of the material (Figure 9).
In cases in which the carious tissue is extensive enough to require preparation into deep dentin, the use of liners and base materials has been demonstrated to protect the pulp and maintain the vitality of the tooth. The selection of liners and base materials that also have the ability to release and recharge beneficial ions and that do not require separate etching and bonding steps can help to further protect pulpal vitality, reduce patient sensitivity, and improve restorative outcomes.
About the Author
Daniel H. Ward, DDS
American Board of Aesthetic Dentistry
Academy of General Dentistry
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