Glutaraldehyde is more than a desensitizer: Lesser-known uses for total-etch adhesive techniques

While adhesive dentistry has added a whole new world of benefits to the field, it’s not without its frustrations and shortcomings. One of the most common complaints is postoperative sensitivity. It’s frustrating for the patient, and it’s frustrating for the practitioner. It’s an extra appointment with a disgruntled or uncomfortable patient that doesn’t have to happen.

Glutaraldehyde is commonly used to decrease sensitivity. Many practitioners use it for deep fillings, but I’ve found through conversations I’ve had that very few are using it as part of their protocol for all bonded direct and indirect restorations.

I want to elucidate some of the lesser-known benefits of glutaraldehyde, and in doing so, I hope that you’ll come away with a greater understanding of how this little liquid can decrease those unnecessary second visits. I’m going to make a case for using glutaraldehyde as the second step in all of your total-etch adhesive techniques—that is, any time you use a fourth- or fifth-generation bonding system.

Desensitizes, disinfects, and strengthens

Glutaraldehyde, popularized by the name brand Gluma Desensitizer by Kulzer (figure 1), has become well-known as an additive to desensitize. But glutaraldehyde’s benefits extend far beyond desensitization. It not only desensitizes, but it also disinfects and strengthens the bonding agent’s ability to penetrate, therefore making your bond last longer.

Figure 1: Gluma Desensitizer (Kulzer)

Gluma has been used as a desensitizing agent since 1991 and is a combination of 5% glutaraldehyde and 35% hydroxyethylmethacrylate (HEMA). In recent years, Gluma’s patent has run out, and there are now less expensive options available with the same chemical composition. I use G5 All-Purpose Desensitizer by Clinician’s Choice Dental Products Inc. (figure 2) in my practice. MicroPrime Desensitizer from Danville Materials (figure 3) and Hema-Glu Desensitizer by Healthdent’l LLC (figure 4) are other less expensive alternatives.

Figure 3: MicroPrime Desensitizer (Danville)

Current bonding techniques are known to cause postoperative sensitivity through the hydrodynamic theory of pain. When desensitizer is used, the glutaraldehyde creates a plug inside the dentinal tubules that eliminates the hydrodynamic mechanism. It basically clogs the dentin pores so fluid can’t seep out, and post-op discomfort is significantly reduced.

Figure 4: Hema-Glu Desensitizer (Healthdent’l)

Inactivates the harmful enzymes that break down bond strength

While the desensitizing effect of glutaraldehyde is reason enough to use it, there’s a second compelling reason that has gained attention recently. Glutaraldehyde has been shown to affect the longevity of the dentin-resin interface. Without getting too scientific, our bodies make enzymes that break down proteins called MMPs that get trapped in the demineralized dentin layer. It’s the MMPs that result in reduced bond strength and debonding over time.1 Those MMPs are activated by our acid etchant during the adhesion process.2-3

MMPs, which degrade Type I collagen, can slowly degrade the collagen fibrils at the interface of the dentin with the resin. Glutaraldehyde cross-links MMPs, inactivating their enzymatic activity. If you use glutaraldehyde on acid-etched dentin, you can effectively inactivate most MMP activity.2-3

It is the water-loving monomers, such as acetone or ethanol, in the primer that allow bonding to moist, etched dentin. Although our bonding techniques have improved significantly, we still aren’t able to completely replace the water in the collagen matrix of dentin with monomer in our primer. Since this isn’t possible, we get the hybrid layer containing some voids.

So, we have MMPs activated by etching that want to break down collagen if they can get in there, and we have voids left during the adhesion process. These voids at the dentin-adhesive interface make the bond more susceptible to degradation by enzymes such as MMPs over time.2-3

Rewetting agent

There’s another bonus we should highlight. If we air-dry the dentin after acid-etching, the air removes water from the collagen matrix, causing the collagen to collapse and condense. When there are fewer spaces between the collagen fibers, our monomer’s ability to get into the collagen is decreased.4 So, not only do we have voids in the hybrid layer, now we’ve desiccated the collagen and made it even harder to penetrate. When we rewet the dentin after air-drying from the etchant, the collapsed collagen network expands again and our bond strength is increased. We can use glutaraldehyde for this rewetting.4

Antibacterial agent

Glutaraldehyde has several benefits to its use as an antibacterial agent. It has a broad spectrum of action, a fast kill rate, and can destroy not only bacteria, but fungal spores, tubercle bacilli, and viruses as well. Mechanical debridement alone doesn’t effectively remove bacteria from a carious lesion. Acid-etching kills Streptococcus mutans, but doesn’t kill acid-loving (acidophilic) and acid-producing (acidogenic) bacteria. In fact, it may even stimulate them.5-6

Recap

So, why are we going to use glutaraldehyde after acid-etching teeth? There are four main reasons. One major benefit is that it desensitizes the tooth by blocking fluid flow. In addition, it inactivates the harmful enzymes that break down bond strength, such as MMPs. It serves as a rewetting agent to plump up the collagen fibers for monomer penetration, and finally, it is antibacterial.

Technique is everything in adhesive dentistry. Make sure to follow the manufacturer’s instructions very closely for drying and wetting times, scrub when indicated, and consider adding glutaraldehyde to your adhesive protocol.

References

1. Cilli R, Prakki A, de Araújo PA, Pereira JC. Influence of glutaraldehyde priming on bond strength of an experimental adhesive system applied to wet and dry dentine. J Dent. 2009;37(3):212-218. doi: 10.1016/j.jdent.2008.11.017.

2. Perdigão J, Reis A, Loguercio AD. Dentin adhesion and MMPs: a comprehensive review. J Esthet Restor Dent. 2013;25(4):219-241. doi: 10.1111/jerd.12016.

3. Sabatini C, Scheffel DL, Scheffel RH, et al. Inhibition of endogenous human dentin MMPs by Gluma. Dent Mater. 2014;30(7):752-758. doi: 10.1016/j.dental.2014.04.006.

4. Bedran-Russo AK, Pashley DH, Agee K, Drummond JL, Miescke KJ. Changes in stiffness of demineralized dentin following application of collagen crosslinkers. J Biomed Mater Res B Appl Biomater. 2008;86(2):330-334.

5. Felton D, Bergenholtz G, Cox CF. Inhibition of bacterial growth under composite restorations following GLUMA pretreatment. J Dent Res. 1989;68(3):491-495.

6. Gorman SP, Scott EM, Russell AD. Antimicrobial activity, uses and mechanism of action of glutaraldehyde. J Appl Bacteriol. 1980;48(2):161-190.

Courtney Lavigne, DMD, is a board member of the affiliate committee of the American Academy of Cosmetic Dentistry, the secretary and treasurer of the New England Academy of Cosmetic Dentistry, visiting faculty for Spear Education, and a contributor for Spear Digest online. Dr. Lavigne is also a national lecturer. Visit her website at courtneylavigne.com.