RESUMO
OBJECTIVE: Bleeding control is a major concern during dental surgery. A novel photocoagulation method using an irradiating blue-violet light emitting diode (LED) was investigated. BACKGROUND: Some dental light-curving units can emit blue-violet wavelengths around 380-515 nm with two peaks (410 nm and 470 nm). These wavelengths can cover the maximum absorption spectra of hemoglobin (430 nm). MATERIALS AND METHODS: Blue-violet LED 380-515 nm, 750 mW/cm(2), 10 sec (7.5 J/cm(2)) was used. Irradiation was performed for 10 sec or an additional 10 sec for 10 cases of tooth extraction at a distance of 1 cm from the socket. Bleeding was stopped by conventional roll pressure in another five cases as a control. Bleeding time for both procedures was measured. A Mann-Whitney U test was used for statistical analysis. In vitro transmission electron microscope (TEM) studies were performed to clarify the mechanism of hemostasis by blue-violet LED irradiation. RESULTS: Irradiation with the blue-violet LED yielded immediate hemostasis of the socket. Five cases showed coagulation within the first 10 sec, and another five cases required an additional 10 sec to fully control the bleeding. In contrast, the conventional method required 2-5 min (median 180 sec) to obtain hemostasis. The difference between the time required to stop the bleeding in the two methods was found to be statistically significant (p = 0.0014). A week later, the LED-irradiated sockets were healed uneventfully with epithelial covering. TEM showed the formation of a thin amorphous layer and an adjacent agglutination of platelets and other cellular elements under the layer at the interface of the irradiated blood. CONCLUSION: Blue-violet LED irradiation of bleeding sockets caused immediate clot formation and hemostasis. This procedure was safe and reliable and showed no adverse effects.