Guidelines for Successful Adhesion

Richard B. Price, BDS, DDS, MS,PhD (RP): A medical-dental consensus is a public statement about a particular aspect of medical-dental knowledge made by a representative group of experts who have convened and agreed on guidelines that are evidence-based and represent the current state of the science.¹ Its primary objective is to counsel clinicians on the best possible and most acceptable ways to diagnose and treat certain diseases or how to address a particular decision-making scenario.

Consensus statements in medicine and dentistry have been instrumental in updating current practices and dispeling long-standing views that do not have adequate evidence to support them. In dentistry, consensus conferences have provided valuable information that has improved patient care.^2-6

ID: Who participates in creating these guidelines, and what is their approach?

Howard E. Strassler, DMD (HS): Appropriate decision-making is critical for effective patient care. Both the medical and dental professions have used an evidence-based approach to help guide clinicians, researchers, and manufacturers in the development and implementation of appropriate techniques and procedures to treat patients.

Critical to the success and adoption of consensus guidelines is that the panel tasked with their development includes representatives from all of the groups that have an investment in the decisions that the guidelines will affect. When applied to dentistry, this would include clinicians, academicians, researchers, and representatives from the dental industry.

ID: What types of guidelines have been initiated through consensus conferences at Dalhousie University?

RP: Several meetings have been held at Dalhousie University in Halifax, Nova Scotia (Canada), bringing together key opinion leaders who represent these groups. At these meetings of the International Symposium on Light Sources in Dentistry (Northern Lights meetings), participants discuss relevant topics related to light curing in restorative dentistry and create evidence-based guidelines for laboratory research and clinical treatment. At the conclusion of the meeting, a consensus statement is agreed upon by the participants, who then disseminate this information in their respective countries of origin.

To date, discussions have been had and consensus achieved for many topics, including identifying the important issues in light curing (2012), light curing guidelines during restoration placement (2014), factors to consider when buying a new curing unit (2015),⁷ and guidelines when using bulk-fill composites (2016).⁸

ID: What topic was addressed by the panel at the latest meeting, and how will the guidelines contained in the consensus statement impact dental practices?

HS: During the 2017 Northern Lights meeting, the topic under discussion was adhesive dentistry. Currently, most restorative and esthetic procedures performed in dentistry are based on the adhesion of synthetic materials such as resins, ceramics, or metals to natural dental structures. These topics have been widely researched, and considerable scientific evidence has been generated to guide the respective procedures, thus ensuring that they are performed correctly and result in clinical longevity.

Regardless of which adhesive system is selected for an indication, the meeting's participants all agreed that it is critical for clinicians to closely follow the manufacturer's instructions for use (see Consensus Guidelines for Adhesive Dentistry). There is no single technique that can be applied to all of the available products because adhesive systems have different compositions, and therefore, they require different protocols.

Richard B. Price, BDS, DDS, MS, PhD
Professor of Prosthodontics
Dalhousie University
Halifax, Nova Scotia

Howard E. Strassler, DMD
Professor
Department of General Dentistry
University of Maryland
School of Dentistry
Baltimore, Maryland

1. Follow the adhesive manufacturer's instructions. Bonding systems and agents are not all the same. Some bonding agents are incompatible with dual-cure resins. Also, do not use expired products or products that are not licensed for use in your country.

2. Do not dispense the bonding agent until it is ready to be used. If the solvent in the adhesive evaporates before the adhesive is applied to the tooth, the bond strength will be reduced. If using bottles of adhesive agents, always replace the caps to reduce the amount of solvent evaporation.

3. For successful bonding, there must be complete control of bleeding, sul-cular fluids, saliva, moisture, the tongue, and the cheeks. Avoid contaminating the bonding surfaces with hemostatic agents.

4. Prepare peripheral tooth structure to reach sound, nondemineralized enamel and hard dentin. Hard, sclerotic dentin should be roughened with a dental bur. Etch the enamel with phosphoric acid, even when using a self-etching adhesive.

5. If it appears that the preparation requires disinfection, only use products that are approved by the manufacturer of the adhesive resin. Never use a peroxide-containing product in the preparation prior to adhesive bonding.

6. Most instructions recommend leaving the dentin moist before applying the bonding agent. However, tooth surfaces that are moist with saliva or blood should be considered contaminated.

7. To maximize bond strengths, the bonding agent should be actively applied to the dentin or enamel according to the manufacturer's instructions. Reapply if necessary; do not rush this step.

8. If the tooth surface becomes contaminated with blood or saliva, do not proceed. Instead, rinse and dry the surface, then reapply the bonding agent as described in the product's instructions for use. Some products may also require re-etching the enamel.

9. It is critical to use a clean and dry air source to gently evaporate the solvent from the adhesive agent as well as to air thin the adhesive. Gently evaporate the solvent from all regions of the tooth with moderate air pressure until there is no movement and the surface is shiny. Some bonding agents require longer drying times than others. Certain regions of the tooth are more challenging to reach than others, so carefully inspect these hard-to-reach areas for pooling of adhesive or inadequate adhesive coverage.

10. After light curing the adhesive, carefully place the composite as soon as possible without introducing voids.

11. To keep instruments clean, use a damp alcohol wipe. Never dip instruments into the bonding agent because the uncured bonding agent may then be incorporated into the composite. This will both weaken and discolor the composite.

12. Know your curing light. Regularly check that the light is in good working order.

13. Use and position the light correctly so that all bonding surfaces receive sufficient exposure. Class II restorations benefit from additional light curing of the buccal and lingual surfaces after the matrix has been removed.

14. To avoid overheating the pulp, do not use a high-power light where the dentin is thin. If needed, use cooling techniques to prevent overheating the pulp when light curing.