Dissolvable stitches are able to dissolve because they’re made of materials that the body can readily breakdown and absorb. Depending on the suture material, they will either be dissolved via proteolytic enzymes or via hydrolysis.
What dissolving sutures are made of
Self dissolving stitches can be made of natural or synthetic materials.
- The natural dissolvable sutures are made of the intestines of ruminant animals.
- The synthetic dissolvable sutures are made of polymers or copolymers.
The table below shows every type of absorbable suture, the type of material they’re made of, and how they dissolve in the body.
|Type of Suture||How its Made||Type of Material||How it Dissolves|
|Fast Gut||Natural||Animal intestines||Proteolytic enzymes|
|Plain Gut||Natural||Animal intestines||Proteolytic enzymes|
|Chromic Gut||Natural||Animal intestines||Proteolytic enzymes|
Polymer vs Copolymers
Both polymers and copolymers are synthetically made. The only difference between them is that copolymers are simply multiple polymers that are stringed together. Polymers on the other hand are repeating strings of the same monomer.
Copolymer vs polymer vs monomer:
- Monomer – single molecule, often organic meaning it has carbon atoms.
- Polymer – multiple monomers that are stringed together into a long chain.
- Copolymer – multiple polymers that are stringed together into a long chain.
If that is a little confusing, we’ve drawn an illustrative diagram to show what we’re talking about.
Essentially you can think of synthetic dissolving sutures as a string of beads.
- If they’re made of polymers, its a string of the same colored bead.
- If they’re made of copolymers, its a string of multi-colored beads.
Hopefully that clears up what exactly are sutures. In the next section we will go through the dissolution mechanism.
How do dissolvable stitches work?
The natural dissolving sutures get dissolved via proteolytic enzymes while the synthetic ones dissolve via hydrolysis. How long it takes them to dissolve will depend on their material.
How natural sutures dissolve
The only type of natural absorbable stitches are the family of gut sutures. They’re actually made out of the intestines of ruminant animals (cows, sheeps, goats). That makes them very collagenous and very similar to food.
Since they’re literally made out of collagen which is food, the way they breakdown is self-explanatory. Our body digests food all the time and absorb them. These gut sutures are no exception, they get broken down proteolytically via enzymes just like the food you eat.
How synthetic sutures dissolve
Dissolvable synthetic sutures dissolve via hydrolysis. That means when the material comes into contact with water, the ester bond of the polymer gets cleaved. In other words, the bonds which holds each monomer together to form a polymer gets broken.
As an example, we’ll use the breakdown mechanism of polyglycolic acid (PGA) sutures.
Specifications of PGA:
- Monomer = glycolic acid
- Polymer = polyglycolic acid
- Essentially it is a string of glycolic acids
When PGA comes into contact with water, it undergoes hydrolysis and breaks down into glycolic acid.
The glycolic acid will undergo further metabolism into oxalic acid which precipitates with calcium to form an insoluble calcium oxalate crystal. This is the same substance that you find in spinach!
Ultimately, the oxalates get excreted from the body via urine. Oxalates are generally a natural byproduct of metabolism in the body.
The other types of synthetic stitches all work in a similar manner. They all get broken down via hydrolysis so we don’t think its necessary for us to repeat what we’ve wrote that many times. We believe you get the idea from this PGA example.
How long do PGA sutures take to dissolve?
The median survival time of polyglycolic acid in the mouth is 15 days before they fall out. However, complete dissolution of the stitch doesn’t happen until 6 months.
What we mean by these numbers is that, the suture will typically dissolve enough for them to fall out on their own after about 2 weeks. Although for it to be 100% completely absorbed by the body it does take up to 6 months.
Do stitches hurt when they dissolve?
When the sutures dissolve, it generally does not hurt. However, you may get an itchy or tingly sensation at times in the area as it heals. That is about the most discomfort that you will ever get from absorbable stitches.
What do dissolvable sutures dissolve into?
For the synthetic stitches, they all breakdown into their respective monomers. Whether they’re polymers or copolymers, they’re still made out of monomer(s).
You think think of the dissolution process as a string of beads getting separated into single beads. Please refer to our colored drawing above.
Also, to be crystal clear all of the dissolving sutures technically don’t have a color. However, manufacturers have universally decided to dye them to a uniform color across all brands. The color is simply there to help your doctor readily identify which type of material it is made out of. Not to confuse you but they can also come in an undyed version as well!
What if they don’t dissolve?
Dissolvable sutures will eventually dissolve but sometimes the body can reject them. If that happens, it ends up as what we call a spitting suture.
That is when the body tries to push the stitches out of the body instead of trying to dissolve them. If this happens you will need to seek medical help to have them removed.
Hopefully that satisfies your curiosity of how do dissolvable stitches work. Basically, they’re all made out of a material that our bodies can naturally absorb. The natural materials get broken down via proteolytic enzymes while the synthetic ones breakdown via hydrolysis.