Chitosan for antimicrobial activity and wound healing in post-extraction sockets: a prospective clinical study

Every time a tooth is removed, it leaves behind a small, open cavity in the jawbone. This space is a vulnerable entry point for the countless bacteria that live naturally in the mouth. For a healthy person, the body usually handles this challenge on its own: a blood clot forms to stop the bleeding, soft tissue grows over the opening, and new bone slowly fills the gap. However, this process can sometimes go wrong. The clot might dissolve too early, bacteria might take hold and cause infection, or the bone might not heal as quickly as needed, leaving the jaw weaker for future dental work. While doctors sometimes prescribe strong antibiotics to prevent these issues, there is growing concern that using them too often creates bacteria that are harder to kill later. This has led researchers to look for local solutions—materials placed directly into the hole that can stop bleeding, fight germs, and help the body repair itself without relying on pills.

One such material is chitosan, a substance derived from the shells of crustaceans like crabs and shrimp. In its natural state, it is a tough, fibrous polymer, but when processed for medical use, it becomes a fine powder or a gel. What makes it special is its electrical charge. Most bacteria have a negative charge on their outer surface, while chitosan carries a positive charge. This creates a natural attraction, much like a magnet pulling on metal, allowing the material to stick to and disrupt the bacterial cells. Beyond fighting germs, chitosan can also help blood clot by attracting blood cells to the wound site, and it mimics the structure of the body's own tissues, potentially guiding new bone to grow.

A team of researchers at SRM Dental College in India set out to test whether using this material could improve the healing process after a routine tooth extraction. They recruited sixty adults who needed a tooth removed and divided them into two equal groups. For the first group, the "study" group, the dentist placed a paste made of chitosan powder mixed with salt water directly into the empty socket after pulling the tooth. They then covered the area with a chitosan-based gel and applied more of this gel on top of the stitches during follow-up visits. The second group, the "control" group, received the standard treatment: a gelatin sponge, which is a common material used to help stop bleeding, placed in the socket, along with a standard gel on top. Neither group received systemic antibiotics, ensuring that any differences in healing came from the local materials used.

The researchers checked on the patients over several weeks, looking at how well the gums healed, how much pain the patients felt, whether bleeding occurred, and how the bone inside the jaw was changing. They measured the soft tissue healing using a standard scoring system and asked patients to rate their pain on a scale from zero to ten. To see what was happening inside the bone, they took X-rays at five, thirteen, and twenty weeks after the surgery. They also analyzed the stitches removed on the seventh day to see if any bacteria had grown on them.

The results showed a clear difference in how the wounds closed. By the seventh day, the group treated with chitosan had significantly better soft tissue healing than the group with the gelatin sponge. The chitosan group also showed much stronger signs of bone healing in the X-rays. At every check-up point—five, thirteen, and twenty weeks—the sockets treated with chitosan appeared denser and more filled in with new bone compared to the control group. The researchers used digital tools to measure the brightness of the bone on the X-rays, and the chitosan group consistently showed higher values, indicating a faster and more complete mineralization of the bone.

When it came to pain, the study found that both groups felt similar levels of discomfort on the first, third, and seventh days. The chitosan did not make the procedure significantly less painful than the standard treatment, but it did not cause any extra pain either. The most striking finding, however, was in the fight against infection. When the researchers cultured the stitches from the control group, they found significant growth of two common types of mouth bacteria: Streptococcus and Lactobacillus. In contrast, the stitches from the chitosan group showed no detectable bacterial growth at all. This suggests that the chitosan effectively prevented bacteria from colonizing the healing wound.

The study also confirmed that the material was safe. No patients reported any adverse reactions, and the bleeding stopped in both groups within the first few days, showing that chitosan was at least as good as the traditional gelatin sponge at controlling blood flow. The researchers noted that while chitosan is a powerful tool for routine extractions, it is not a replacement for antibiotics in cases where a patient has a severe infection, a weakened immune system, or a known allergy to shellfish. They also pointed out that this specific method was tested on straightforward extractions and might not be suitable for more complex cases involving impacted teeth.

Ultimately, this research suggests that placing chitosan into a tooth socket offers a biologically friendly way to speed up healing. It helps the gums close faster, encourages the bone to fill in the gap more quickly, and keeps the wound free of bacteria without the need for systemic drugs. While the material did not change the level of pain patients felt, its ability to create a cleaner, faster-healing environment could be a valuable addition to dental surgery, potentially leading to better outcomes for future dental implants and prosthetics. The findings provide a strong case for using this natural, biodegradable material as a standard part of the healing process after a tooth is removed.