Orthodontic pain: c-Fos expression in rat brain nuclei after rapid maxillary expansion.

BACKGROUND: The aim of this in vivo study was to quantitatively evaluate pain after rapid maxillary expansion (RME) in young rats by analyzing the activation of nociception-related structures, that is, the caudalis, interpolaris, and oralis subnuclei, according to the Fos expression. METHODS: A total of 65 Wistar rats were assigned to three groups: control group (n = 15) with no treatment, positive control group (n = 25), and experimental group (n = 25) with RME. The experimental animals were euthanized at 6, 12, 24, 48, and 72 hours after RME, and the brain was later carefully collected. Coronal sections through the spinal trigeminal caudalis, spinal trigeminal interpolaris, and spinal trigeminal oralis were cut (thickness of 40 µm) on a cryostat and processed for Fos immunohistochemistry. Images from the sections were captured under light microscopy, and ImageJ software was used to count Fos-like immunoreactive neurons. The Analysis of variance (ANOVA) and Tukey test were used for statistical analysis, and the significance level was set at 5%. RESULTS: RME induced incisor distalization and opening of the midpalatal suture, as well as neuronal activation of the spinal trigeminal nucleus. The experimental group demonstrated significantly more Fos-positive neurons in subnuclei caudalis and subnuclei interpolaris 6 hours after the maxillary expansion. The Fos immunoreactivity significantly decreased at 12 hours and increased again at 24 and 48 hours (P < 0.001). CONCLUSIONS: The RME increases the neural activation of brain regions involved in the nociception region, as determined by the Fos expression. The most intense Fos-like immunoreactive expression was detected in the brain 6 hours after the start of the palatal expansion.

Influence of cigarette smoke on enamel color stability after orthodontic debonding: an in vitro study

Objective: The aim of this study was to evaluate the color stability of dental enamel exposed to cigarette smoke after orthodontic debonding. Methods: Thirty-two bovine incisors were allocated into control (C1 and C2) and experimental groups (n=8) according to distinct bonding protocols: with adhesive (B1) and without adhesive (B2) and exposure to cigarette smoke. Samples from B1, B2 and C2 were exposed to ten cycles of smoke in a specific and hermetic chamber while the C1 remained stored in artificial saliva. Color analysis was performed with a spectrophotometer according to the L*a*b* system. Intergroup comparisons and effect of time were estimated with ANOVA/Tukey and paired Student t tests, respectively (a=0.05). Results: Statistically significant color changes have not been observed in C1 (L*: -0.69 ± 0.80; a*: 0.36 ± 0.23; b*: 0.17 ± 0.50) and without adhesive (B2) (L*: -3.74 ± 2.85; a*: 0.93 ± 0,73; b*: 1.13 ± 1.16) through the study time (p>0,05). However, the group with adhesive (B1) presented significant color changes in L*:-5.55 ± 2.28, a*: 2.33 ± 0.77 and b*: 3.30 ± 1.37, what means, darker, greener and more yellow, respectively (p<0,05) and the control group that was exposed to the cigarette smoke (C2) presented significant color changes in L*: -1.72 ± 0.28 e b*: 1.82 ± 0.22, what means, darker and more yellow, respectively. Conclusion: Enamel color stability was affected by exposure to cigarette smoke after orthodontic debonding, especially when bonding protocolcomprised the application of primer adhesive.

Objetivo: O objetivo deste estudo foi avaliar a estabilidade da cor do esmalte dentário exposto à fumaça de cigarro após a descolagem ortodôntica. Métodos: Trinta e dois incisivos bovinos foram alocados nos grupos controle (C1 and C2) e experimental (n = 8) de acordo com protocolos de colagem ortodôntica distintos: com adesivo (B1) e sem adesivo (B2) e expostos à fumaça de cigarro. Amostras do B1, B2 e C2 foram expostas a dez ciclos de fumaça em uma câmara específica e hermética, enquanto o C1 permaneceu armazenado em saliva artificial. A análise da estabilidade de cor foi realizada com um espectrofotômetro de acordo com osistema L* a* b*. As comparações intergrupos e o efeito do tempo foram verificados com ANOVA / Tukey e testes t de Student, respectivamente (a=0,05). Resultados: Não foram observadas alterações de cor estatisticamente significativas no C1 (L*: -0,69 ± 0,80; a*: 0,36 ± 0,23; b*: 0,17 ± 0.50) e sem adesivo (B2) (L*: -3,74 ± 2,85; a*: 0,93 ± 0,73; b *: 1,13 ± 1,16) durante o tempo de estudo (p>0,05). No entanto, o grupo com adesivo (B1) apresentou alterações significativas de cor em L*: - 5,55 ± 2,28, a*: 2,33 ± 0,77 eb*: 3,30 ± 1,37, o que significa, mais escuro, mais verde e mais amarelo, respectivamente (p<0,05) e o grupo controle exposto à fumaça de cigarro (C2) apresentou alterações significativas de cor em L*: -1,72 ± 0,28 e b*: 1, 82 ± 0,22, o que significa, mais escuro e mais amarelo, respectivamente. Conclusão: A estabilidade da cor do esmalte foi afetada pela exposição à fumaça de cigarro após a descolagem ortodôntica, principalmente quando o protocolo de colagem incluía a aplicação de adesivo.

The Effect of Cigarette Smoking And Low-Level Laser Irradiation in RANK/RANKL/OPG Expression.

The objective of this study was to investigate the effects of low-level laser therapy (LLLT) and cigarette smoke on alveolar socket osteoclastogenesis signaling after tooth extraction, in rats. Sixty male Wistar rats were randomly assigned to four groups with 15 animals each: Control Group (with right maxillary molar extraction - ME), Experimental I (with ME and LLLT), Experimental II (with ME and cigarette smoke) and Experimental III group (with ME, LLLT and cigarette smoke). Euthanasia was performed at 3, 7 and 14 days postoperative. qRT-PCR was used to evaluate expression of Tnfrsf11a (RANK), Tnfsf11 (Rankl) and Tnfrsf11b (OPG). Data were submitted to statistical analysis using two-way ANOVA followed by Bonferroni test (α=0.05). There was an upregulation of RANK, RANKL and OPG genes over all the time of healing in Exp I group compared to control group. Exp II group showed a decreased expression of all genes over time, whereas Exp III genes expression were higher than Exp II values but lower than Control and Exp I values over time. The results of this study concluded that the LLLT had a positive effect, whereas cigarette smoke had a negative effect on RANK, RANKL and OPG gene expression in bone remodeling process.

Análise das alterações pulpares após expansão rápida da maxila em ratos / Analysis of pulpal changes after rapid maxillary expansion in rats

O objetivo deste estudo foi avaliar os efeitos da expansão rápida da maxila (ERM) na polpa dentária de dentes de ancoragem de ratos jovens, através das análises histomorfológica, histomorfométrica e de expressão gênica. Oitenta (n=80) ratos Wistar machos foram distribuídos aleatoriamente em 2 grupos: Grupo Controle (GC, n=40), em que os animais não tiveram ERM e foram sacrificados nos períodos de 3, 7, 14 e 21 dias após o início do experimento; e Grupo Experimental (GE, n=40), cujos animais foram submetidos à ERM e sacrificados nos mesmos períodos do Grupo Controle. As polpas dentárias dos incisivos superiores de 20 animais (n=20) de cada grupo, GC e GE, foram extraídas para a análise da expressão gênica do RNAm, pela técnica de Reação em Cadeia da Polimerase em Tempo Real (RT-PCR), para os genes Fator de Crescimento Endotelial Vascular (Vegf), Sialofosfoproteína da Dentina (Dspp) e Ciclooxigenase-2 (Cox-2), e de 20 animais (n=20) para as análises histomorfológica e histomorfométrica do tecido pulpar. Todos os grupos que sofreram ERM apresentaram sinais da ocorrência de inflamação e aumento da densidade de vasos sanguíneos, com alterações transitórias na camada de odontoblastos. Houve aumento significativo da expressão gênica de Vegf em todos os períodos experimentais, sendo para Cox-2 apenas nos períodos de 3 e 7 dias, e para Dspp no 7º e 14º dias. Concluise que a ERM induziu a remodelação do tecido pulpar, com modulação transitória das expressões gênicas analisadas e da vascularização. (AU)

The objective of this study was to evaluate the effects of rapid maxillary expansion (RME) on the dental pulp of anchoring teeth of young rats through histolomorphological, histomorphometric and gene expression analyzes. Eighty (n= 80) male Wistar rats were randomly assigned to 2 groups: Control Group (CG, n=40), in which the animals had no ERM and were sacrificed at 3, 7, 14 and 21 days after initiation of the experiment; and Experimental Group (GE, n=40), whose animals were submitted to RME and sacrificed in the same periods of the GC. The dental pulps of the upper incisors of twenty animals (n=20) from each group, GC and GE, were extracted for analysis of the mRNA gene expression by the Reverse Transcription Polymerase Chain Reaction (RT-PCR) technique for the Vascular Endothelial Growth Factor (Vegf), Dentin Sialophosphoprotein (Dspp) and Cyclooxygenase-2 (Cox-2) genes, and twenty animals (n=20) for the histolomorphological and histomorphometric analyzes of the pulp tissue. All groups that suffered RME showed signs of inflammation occurrence and increased blood vessel density, with transient changes in the odontoblast layer. There was a significant increase in Vegf gene expression in all experimental periods, being for Cox-2 only in periods of 3 and 7 days, and for Dspp in the 7th and 14th days. It was concluded that ERM induced remodeling of pulp tissue, with transient modulation of the analyzed gene expression and vascularization. (AU)

Histological, histochemical, and protein changes after induced malocclusion by occlusion alteration of Wistar rats.

Although disorders of the stomatognathic system are common, the mechanisms involved are unknown. Our objective was to study the changes in the masseter muscles after unilateral exodontia. Molar extraction was performed on Wistar rats (left side), and the animals were sacrificed after either 14 or 26 days. The masseter muscle was processed for histological analysis, conventional and in situ zymography, and immunohistochemistry. The morphological analysis showed unique and specific characteristics for the experimental group. By conventional zymography no significant values of 72 kDa MMP-2 (P < 0.05) were found in both of the sides of masseter muscle after 14 and 26 days of unilateral extraction. The in situ zymography showed gelatinolytic activity on all deep masseter muscles, with significant increase on the contralateral side after 14 and 26 days (P < 0.05). The immunohistochemistry demonstrated greater expression of MMP-2 than MMP-9 and MMP-14 in all masseter muscles and there were few differences in the staining of 4 TIMPs. This knowledge about morphology and molecular masticatory muscle remodeling following environmental interventions can be used to develop clinically successful treatments.