RESUMO
AIM: To validate the protocol described here to be used in future clinical trials related to the effect of laser therapy on dental pulp. METHODS: Histologically treated samples from eight human healthy premolar teeth obtained from the middle root level were distributed in four groups: group 1 (G1) absolute control; group 2 (G2) only laser irradiation; group 3 (G3) exposed only to orthodontics; and group 4 (G4) treated with orthodontics and laser. Laser treatment was performed at 830 nm wavelength, 100 mW (energy 80 J/cm(2), 2.2 J), for 22 s in the vestibular surface and 22 s in the palatal surface, 1 mm away from the dental root mucosa. Three staining methods were performed: hematoxylin-eosin (HE), Masson's Trichrome method and Gomori's method. RESULTS: The pulp histology parameters were evaluated and the results classified in to 3 parts: an inflammatory response, soft tissue response (dental pulp) and hard tissue response (dentin and predentin). There was no inflammation (chronic or acute) in any of the evaluated groups. The zones of pulp necrosis were found in one premolar of G3 and in one of G4; in groups G2 and G4 there was higher angiogenesis than in the other two groups. G4 group presented the highest level of vascularization. A reduced nerve density was observed in G3. A G2 specimen showed increased nerve density. A higher rate of calcification was observed in G1 compared to G2. Denticles, either real or false, were observed in G1, G2 and G3. Sclerosis of dentin and focal dentin loss was observed among all the groups. Secondary dentin was present in one sample in G1 and G2. A necrosis zone was found in one sample of G3 and G4. No differences between groups were observed in the odontoblast irregularity layer but the layer was wider in the group treated with laser only. A notable difference was detected in reduction of the cell-free layer between the groups G1 and G4. The findings in pulp tissue favor its adaptative response against dental movement induced by orthodontics. No definitive conclusions may be derived as this is a pilot study. CONCLUSION: The protocol described here was shown to be an effective method to evaluate changes in dental pulp submitted to low level laser in teeth under orthodontic movement.
RESUMO
Low level laser application in orthodontics attempts to accelerate the induced orthodontic movement and to dissipate the dental discomfort during treatment. The recognition of its biological foundation is a fundamental issue to understand the effect of all tissues involved in the irradiated zone.There have been research findings on the cell proliferation and empowerment of cell functions, promotion of bone remodeling, and decreasing of the local swelling and pain during orthodontic treatments. However, the positive results of the laser application on cells involved in the orthodontic movement have not widely been investigated.Literature indicates a lack of research finding on the effect of low laser therapy on the dentin-pulp complex, which demands randomized controlled trials. For these reasons, the aim of this paper attempts to compile the main publications done regarding the effect of low level laser therapy on dental pulp tissue...(AU)
La aplicación del laser de baja intensidad en Ortodoncia, busca acelerar el movimiento dental inducido y manejar la sensación dolorosa durante el curso del tratamiento. El conocimiento de su fundamento biológico, es un aspecto fundamental para comprender el efecto de todos los tejidos involucrados en las zonas irradiadas.Se han reportado hallazgos acerca de cambios en las proliferaciones celulares y potencialización de sus funciones, promoción del remodelado óseo, disminución de la inflamación local y alivio del dolor durante los tratamientos de ortodoncia. Sin embargo, los resultados positivos de la aplicación del láser de baja intensidad en las células involucradas en el movimiento ortodóncico no han sido ampliamente investigados. La literatura indica falta de investigaciones acerca del efecto de la terapia láser de baja intensidad en el complejo dentino-pulpar, por tanto se requieren estudios aleatoriamente controlados sobre el tema. El objetivo de esta revisión es recopilar las publicaciones que reportan el efecto del laser de baja intensidad sobre el tejido pulpar...(AU)