Agitation, in its simplest form, is the active brushing or scrubbing of your bonding agent layer inside the cavity, using your microbrush.
So, instead of applying the bond gently, almost like painting a wall, you’ll grab your microbrush and actively scrub and rub it across all dentin and enamel surfaces within the cavity for at least 15-20 seconds. The core idea isn’t merely distribution; it’s about “forcing” the bond into every single nook and cranny.
Why Is This Scrubbing So Crucial? What Happens During Agitation? (The Science Behind the Rub)
To truly grasp the significance of this motion, we need to recall what dentin looks like under a microscope. Dentin isn’t a solid, impenetrable surface; it’s a complex network of tiny dentinal tubules that extend from the cavity surface all the way to the pulp.
When you perform agitation, you’re accomplishing several extremely important things simultaneously:
1. Assisting Solvent Evaporation
Bonding agents typically contain a solvent, such as acetone or alcohol. For the bond to function optimally, this solvent absolutely must evaporate. Active scrubbing significantly increases the surface area and speeds up this evaporation process, leaving you with a concentrated layer of resin monomer that will actually form the bond.
2. Enhancing Bond Penetration
This scrubbing action literally forces the liquid bonding agent to deeply penetrate and infiltrate into the open dentinal tubules, and also into the intricate collagen network that the etching process has exposed.
3. Forming Strong Mechanical “Tags”
As the bond enters these tubules and you proceed with curing, it solidifies within them, creating thousands of microscopic resin protrusions we call Resin Tags. These resin tags effectively act like tiny “pegs” or “nails,” powerfully anchoring the bond layer to the tooth with formidable strength (1). The longer and more numerous these tags are, the stronger the bond will be.
4. Breaking Up Filler Aggregates
Some types of bonding agents contain a percentage of filler particles. The scrubbing helps distribute these particles homogeneously, preventing them from clumping together in one area.
What Clinical Benefits Will I See in My Practice? (The Clinical Benefits)
All this scientific talk is great, but as a dentist, how does this actually benefit my daily work?
1. Significantly Higher Bond Strength
Extensive research has unequivocally shown that merely performing agitation for 15-20 seconds can increase bond strength by as much as 30-40% compared to static application (2). This translates directly into restorations that last longer and have a much lower chance of debonding.
2. Reduced Post-operative Sensitivity
This is arguably the most critical benefit for your patient. When the resin tags completely and securely seal the open dentinal tubules, you effectively block the pathway for any fluid movement within these tubules (which, according to Brännström’s Hydrodynamic Theory, is the primary cause of sensitivity). A hermetic seal means significantly less, or even zero, sensitivity (3).
3. Better Marginal Seal
A strong bond ensures that the restoration margins are perfectly sealed to the tooth, which in turn reduces microleakage. This directly lessens the likelihood of developing secondary caries.
How to Perform Agitation Correctly? (The Precise Technique)
The process is straightforward and requires no extra tools, but it does demand your focused attention:
1. Choose Your Brush Wisely:
Use a good quality microbrush with strong, cohesive bristles that won’t easily fray inside the cavity.
2. Apply Sufficient Bond:
Dispense enough bonding agent onto your brush to generously cover all cavity surfaces.
3. Active Scrubbing:
Begin scrubbing the bond with active, deliberate circular, up-and-down motions across all cavity walls and the floor. Pay close attention to corners and margins. Don’t be aggressive, but be firm and active.
4. Observe the Time:
Aim for at least 15-20 seconds of continuous scrubbing. Do not rush this vital step.
5. Gentle Air Thinning:
After scrubbing, use a light, gentle stream of air to evaporate any excess solvent and evenly distribute the bond layer. You absolutely must see a shiny, immobile surface before proceeding with curing.
Conclusion: A Small Movement… A Massive Difference
In the world of dentistry, success and failure can sometimes hinge on the smallest details. The agitation technique is one of those details that costs you no extra time or money, yet offers enormous benefits: stronger bonds, dramatically less sensitivity, and a significantly longer lifespan for your restorations.
Starting tomorrow in your clinic, when you apply your bonding agent, remember you’re not just “painting.” You are actively “scrubbing,” “penetrating,” and “establishing” a formidable bond that will endure for years. This tiny movement is one of the true secrets of meticulously crafted work, distinguishing one practitioner from another.
