Joseph Kim, DDS

Articles

A case study presenting the techniques needed for successful adhesive dentistry.

Adhesion Dentistry 101

	In 1955, Michael Buonocore, DDS, docu­mented the use of phosphoric acid to improve adhesion of resin to dental enamel

. Since Dr. Buonocore’s observation, adhesion dentistry has played an important role in the evolution of dentistry. Bonding proce­dures are performed by dentists every day, ranging from bonding orthodontic brackets to delivering stunning porcelain veneers. Because adhesion dentistry is such an indispensable part of the day to day practice of dentistry, a review of its principles will help to refresh the minds and influence the hands of clinicians practicing at every level of experience.

 is the chemical and micromechanical union of an adhesive system to enamel, dentin, and a restorative material. Put another way, adhesion is the bond between a tooth and an adhesive, the bond between an adhesive and a resin, and in the case of indirect restorations, the 

 between a resin and a restoration. Practical applications of this process include superior retention of restorations, improved performance and durability of certain materials, the ability to affect the color properties under an indirect restoration and low solubility. Clinically, these benefits are tempered by heightened technique sensitivity, increased moisture control and isolation requirements, and shrinkage of resin based materials.

Related article: Bonding resin to tooth structure is still confusing

	Due to its low water content and mineralized crystalline structure, adhesion to etched enamel is very strong and predictable. It is advised that phosphoric acid with a concentration of 32 to 37 percent be applied for 15 seconds on cut enamel, and 30 seconds on uncut enamel.

 Appropriate moisture control measures will prevent enzymes and organic molecules within blood, saliva and crevicular fluid from contaminating the etched enamel. These may include use of various suction devices, a mouth prop, cotton drying aids, retraction cord or a rubber dam. Isolation techniques may include using plastic or metal matrices, wedges and rubber dam isolation.

	Up next: See a step-by-step enamel adhesion case

	A post-orthodontic direct composite case is an example of enamel bonding, as the discrepancy in the incisal edges are limited to the patient’s enamel (Fig. 1).

Fig. 2 Enamel prepared with coarse diamond

	In this case, the enamel was prepared with a coarse diamond, extending the margin of the bevel far from the actual restoration site in order to improve retention surface area, minimize the optical transition from tooth to resin and move the restorative junction away from the center of the tooth (Fig. 2).

	It is noteworthy that no dentin was exposed in the preparation. Etchant was applied to the right central incisor for 15 seconds and thoroughly rinsed and dried (Fig. 3). 

	Adequately etched enamel will display a frosty white appearance, and should be protected from saliva contamination (Fig. 4).

	A mylar strip was used to provide isolation from the adjacent central incisor. All-Bond Universal adhesive was applied in two coats to the etched and visibly moist enamel, followed by gentle air pressure to thin out the adhesive and evaporate the solvent. In this case a wedge was not used, as the patient was not anesthetized. The adhesive was light-cured for a minimum of 10 seconds (Fig. 5). 

	Composite resin was applied in two layers and sculpted, with each layer receiving an initial cure through the lingual tooth surface in order to shrink the composite against the facial surface (Fig. 6).

	The final contour of the restoration was accomplished using a carbide finishing bur to blend in the margins, while an instru­ment was used to protect the gingiva from trauma (Fig. 7). Primary facial anatomy was also established at this stage (Fig. 8).

	A #12 scalpel was used to remove any interproximal flash and define the facial embrasure (Fig. 9).  

	Brown and green composite finishing rubber points were used to attain a polished surface (Fig. 10). 

	The same procedures were used for the left central incisor, and the patient was satisfied with the final result (Fig. 11). 

	Adhesive dentistry is a staple of most dental practices today, and will continue to play a role in the dentistry of tomorrow. In future articles, we will review adhesion topics includ­ing best practices for adhesion to dentin, bonding to porcelain and metal, and other areas that will help you provide predictable solutions for your patients.

	1 Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res. 0955;34(6):849-853.

	2 Suh, Byoung In. Principles of Adhesion Dentistry: A Theoretical and Clinical Guide for Dentists. Newtown, PA: AEGIS Communications, 2013.

Technique: Adhesion dentistry 101

Over the past several years, there has been widespread adoption of lithium disilicate based restorations (e.g. IPS e.max®*) by the restorative dental community. 

Previously, restorative dentists were limited in their material selection depending on the need for strength or esthetics. Now, this proven material allows clinicians to address most situations without sacrificing strength or beauty. 

However, this unified material approach often requires the use of different bonding or cementation techniques depending on the location, opacity and type of prosthesis being
	delivered.

, meets the various delivery requirements in a single, simplified kit that incorporates both light cure and dual cure resin cements. This kit was created specifically for lithium disilicate and most other all-ceramic restorations.

In addition to the two different cements, the kit includes a combination of innovative and proven products to simplify the adhesive protocol: etch for both the tooth and ceramic, porcelain primer and a bonding agent. In the following case, the dual cure cement was chosen because of the thickness and low translucency of the finished restoration.

The patient presented with tooth No. 12, which recently had been treated with root canal therapy and a bonded post and core. Restoring premolars that have had root canal therapy can be challenging because of the minimal residual dentinal wall thickness, as well as their visibility in the esthetic zone.

Increasing the difficulty, the premolar exhibited a short clinical crown height, and a widened mesiodistal space because tooth No. 11 was rotated.

Being mindful of biologic width requirements, the tooth was prepared with a subgingival margin to allow enough room to create natural emergence contours, especially on the mesial and distal surfaces. A shallow margin would not have allowed an esthetic outcome, while maintaining a cleansable proximal profile.

At delivery, the provisional crown was removed, and the polycarboxylate temporary cement was removed from the tooth surface with an air driven sonic scaler. The lithium disilicate crown was tried in and the marginal fit, proximal contacts, and occlusion were verified.

The intaglio of the restoration was etched with the eCEMENT kit’s porcelain etchant for 25 seconds, then rinsed and dried. The included porcelain primer was then brushed inside the crown and left for 30 seconds, then dried.

Two coats of All-Bond Universal® from BISCO Dental Products, a single bottle, self-etching adhesive were applied to the tooth according to the manufacturer’s instructions, and light cured for 10 seconds. The film thickness of the adhesive is less than 10 microns and will not interfere with seating of the restoration

After bleeding the automix syringe, the crown was filled with dual-cured eCEMENT. The crown was fully seated onto the prepared tooth. The cement was tack cured for three seconds facially and palatally, and the excess was easily removed with an explorer.

After thoroughly removing any subgingival marginal cement, the facial, occlusal and palatal surfaces were cured for 20 seconds each with a high-output LED curing light. While this step is optional, it is my habit to post-cure dual-cured adhesive cements to inactivate any light sensitive molecules.

The final result fulfilled the unique space, height and color requirements of this case, and the patient was very satisfied with the outcome. The occlusion and contacts were rechecked, and the patient was dismissed.

Compared to alternative bonding and cementation systems, the eCEMENT™ system was uniquely suited for this particular case, where the margins were placed in a significantly subgingival position to idealize the contours, strength and retention.

To control bleeding during delivery of a fixed prosthesis with subgingival margins, several criteria must be met, including a properly fabricated provisional and gentle but complete removal of all provisional cement. Even then, it can be a challenge to keep the site free of blood when etchants and bonding agents come into contact with the gingiva.

In this case, the materials in the eCEMENT kit did not cause any issues with bleeding. In
	fact, the only blood that was encountered was during the final cleanup of the subgingival margins.

From an inventory point of view, stocking and becoming familiar with a single bonding system maximizes efficiency while minimizing errors and material waste. In doing so, delivery times and esthetic outcomes approach an optimal level of predictability.

In summary, the eCEMENT kit provides a comprehensive bonding solution to every lithium disilicate restorative situation, including veneers, inlays, onlays, crowns, fixed prostheses and CAD/CAM fabricated restorations. In doing so, it allows the unified approach of this versatile material to reach its full potential in an efficient and predictable manner.

Over the past several years, there has been widespread adoption of lithium disilicate based restorations (e.g. IPS e.max®*) by the restorative dental community.  Previously, restorative dentists were limited in their material selection depending on the need for strength or esthetics. Now, this proven material allows clinicians to address most situations without sacrificing strength or beauty. 