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Abstract Objective To assess whether bleaching gel volume influences chromatic changes, hydrogen peroxide (HP) diffusion, inflammation, and oxidative stress in the pulp tissue. Methodology A total of 60 bovine teeth were divided into four groups, according to bleaching gel volume (n=15): without gel (WG); V30 (30 µL of 35% HP); V60 (60 µL); and V120 (120 μL). HP diffusion analysis was performed in the first session (T1). Chromatic changes (ΔE, ΔE00, and WID) were assessed after the first (T1), second (T2), third (T3) sessions, and 15 d (T4) after the end of treatment. Moreover, 20 rats were randomly divided into four groups (n=10) and their upper first molars were treated with different gel volumes: control (no treatment); V2 (2 μL of 17.5% HP); V4 (4 μL); and V8 (8 μL). After 24 h, rats were euthanized and the specimens processed for histological and immunohistochemical (nitric oxide synthase) evaluation. Data were analyzed using the Wilcoxon and Mann-Whitney tests (p<0.05). Results In vitro (bovine teeth), chromatic changes were not influenced by bleaching gel volume, showing similar values in all groups and sessions, except for the control group (p<0.05). The V120 group had the highest HP diffusion values (p<0.05). In vivo (pulp tissue), the V4 and V8 groups showed the highest inflammatory infiltrate in the pulp and significant oxidative stress (p<0.05). Conclusion The adverse effects on the dental pulp related to HP diffusion, pulp inflammation, and oxidative stress depend on bleaching gel volume, while the bleaching effect is not proportional to the volume used.
RESUMO
Objetivo: Avaliar a influência do LED Violeta, associado ou não ao gel clareador a base de peróxido de hidrogênio (PH) a 17,5% no complexo dentino-pulpar de ratos. Materiais e métodos: Molares superiores de 80 ratos foram distribuídos nos grupos (n = 10): CONT sem tratamento, PH 1 aplicação de 30 minutos de PH a 17,5%, LED 1 aplicação de 20 minutos do LED Violeta, e PH+LED - aplicação do PH e LED Violeta. Imediatamente (T0), e aos 7 (T1), 15 (T2) e 30 dias (T3) após o tratamento, os ratos foram eutanasiados e as maxilas processadas para avaliação histológica, imunoistoquímica (IL-17, IL-23 e osteocalcina), e de picrosírius red, sendo realizados os testes de Wilcoxon e Mann-Whitney e Teste-T pareado e Teste-T, respectivamente. (α = 0,05). Resultados: Necrose e infiltrado inflamatório severo foram observados nos grupos PH e PH+LED. Apenas o grupo PH+LED manteve a imunomarcação severa para IL-17 e IL-23, diferindo do grupo LED e PH que apresentaram moderada imunomarcação em T0. Os grupos PH e PH+LED apresentaram severa imunomarcação de OCN em T2 e moderada imunomarcação em T3. O grupo LED apresentou menor quantidade de fibras imaturas em T2 e T3 que o grupo CONT. Conclusão: A terapia com LED violeta não induziu inflamação e fibrose no tecido pulpar, apesar de acelerar a maturação das fibras de colágeno da dentina e, quando associada ao peróxido de hidrogênio, pode tornar os dentes mais sensíveis(AU)
Objective: Was to evaluated the influence of the Violet LED, associated or not with a 17.5% hydrogen peroxide (HP) bleaching gel in the dentin-pulp complex of rats. Materials and methods: Upper molars of eighty Wistar rats were distributed in the groups (n = 10): CONT - without treatment, HP - 1 application of 30 minutes of 17.5% HP, LED - 1 application of 20 minutes of the Violet LED, and HP+LED - application of HP and LED Violet. Immediately (T0), and at 7 (T1), 15 (T2) and 30 days (T3) after treatment, the rats were euthanized and the jaws were processed for histological, immunohistochemical evaluation (IL-17, IL-23 and osteocalcin), and picrosirius red, with Wilcoxon and Mann-Whitney tests and paired T-test and T-test, respectively (α = 0.05). Results: Necrosis and severe inflammatory infiltrate were observed in the PH and PH+LED groups. Only the PH+LED group maintained severe immunostaining for IL-17 and IL-23, differing from the LED and PH group which presented moderate T0 immunostaining. The PH and PH+LED groups presented severe immunostaining of OCN in T2 and moderate immunostaining in T3. The LED group had a lower amount of immature fibers in T2 and T3 than the CONT group. Conclusion: Violet LED therapy induced no inflammation and fibrosis in the pulp tissue, however accelerating the maturation of dentin collagen fibers and, when associated with hydrogen peroxide, can make the teeth more sensitive(AU)