Attack of the Collagen Eaters

The COLLAGEN EATERS have been released! When you prep a tooth, actually, when you create injury to any bodily tissue, some stuff called matrix metalloproteinases get released. These substances consist of secreted or membrane bound zinc endopeptidases and include collagenases, gelatinases and stromelysins.

IMPORTANT: If you experienced a biochemistry flashback from that last sentence, I can assure you that the nausea will not last, just lie down until the feeling passes.

When you think you are ready, sit up slowly, take two deep breaths, come back, and complete your reading by skipping to the next bold type. Everything will be okay. Stop reading now and go lie down.

If you felt an electric shiver of excitement up your spine just thinking about the biochemical mechanisms of matrix metalloproteinase here are two articles that might serve to continue that excitement:

Effect of dentin etching and chlorhexidine application on metalloproteinase-mediated collagen degradation. Osorio R, Yamauti M, Osorio E, Ruiz-Requena ME, Pashley D, Tay F, Toledano M. Eur J Oral Sci. 2011 Feb;119(1):79-85. doi: 10.1111/j.1600-0722.2010.00789.x.

Limitations in bonding to dentin and experimental strategies to prevent bond degradation. Liu Y, Tjaderhane L, Breschi L, Mazzoni A, Li N, Mao J, Pashley DH, Tay FR. J Dent Res. 2011 Aug;90(8):953-68. Epub 2011 Jan 10. Review.

The problem for dentists (welcome back) with these substances is that they destroy collagen – the stuff that you are counting on to bond your resin materials to dentin. Fortunately, there is a way to reduce the impact of these biochemical assasins, prep every tooth for a crown and cement it. Okay, we're not going to do that, so we have to try to inhibit the action of these collagen eaters, fortunately there is a way.

Many of us have been minimizing the effect of the matrix metalloprotienases for years without even knowing it. Turns out that chlorhexidine can reduce the activity of these substances, so those of us who have been cleaning the prep with a disinfectant have unknowingly helped our bonds stay bonded. The literature regarding this action of inhibition with dental materials has been done exclusively with chlorhexidine, but the medical literature is replete with examples of this inhibition using a 3% glutaraldehyde solution. Since Gluma is a 5% solution I bet it inhibits the dental collagen eaters too.

Ed McClaren was at the center recently participating on a panel for our Visiting Faculty day and I had an oppportunity to talk with him regarding this. He shared that they have found washing the prep with a 2% chlorhexidine solution first, and then using Gluma, provided a 10% increase in bond strength over chlorhexidine alone.

This information has changed my protocol for bonding anything to dentin. Remember The Checklist Manifesto article I wrote a while back? Time to change the checklist. Here's my new one.

For Total Etch

• Etch everything
• Rinse
• 2% Chlorhexidine
• Gluma
• Bondy stuff

For Selective Etch

• Etch enamel
• Rinse
• 2% Chlorhexidine
• Gluma
• Bondy stuff

For Self Etch

• 2% Chlorhexidine
• Gluma
• Bondy stuff