Impact of cigarette smoke on osteogenic and osteoclast signaling in middle palatal suture

Abstract Considering that smoking is a public health problem that has been growing among adolescents, the aim of this study was to investigate the impact of cigarette smoke on osteogenic and osteoclastogenic signaling in middle palatal suture of rats. Male Wistar rats exposed (n = 30) or not to cigarette smoke (n = 30) were used. Exposure to smoke was carried out for two daily periods of 3 minutes each, with an interval of 12 hours between exposures. After the experimental periods of 3, 7, 14 and 21 days, the animals were euthanized. The collected tissues were analyzed using light microscopy and real-time RT-PCR was performed to investigate gene expression. The data obtained were compared using the Kruskal Wallis and Dunn tests (⍺ = 5%). Morphologically, there were no significant changes in the middle palatal suture of rats exposed or not to cigarette smoke during 3, 7, 14 and 21 days (p> 0.05). On the other hand, osteoclastogenic signaling was increased in animals exposed to smoke and was characterized by a higher production of RANKL at 3 and 14 days (p <0.05), with no change in the synthesis of RANK and osteoprotegerin (p> 0.05). Interestingly, in the exposed animals, an early increase in the synthesis of osteocalcin, bone sialoprotein and osteopontin was also identified at 3 days of exposure (p <0.05), not sustained over time (p> 0.05). Cigarette smoke modulates osteogenic and osteoclastogenic signaling in the middle palatal suture of young rats, although morphological changes have not been evidenced.

Resumo Considerando que a fumaça de cigarro é um problema de saúde pública que está crescendo entre os adolescentes, o objetivo deste estudo foi investigar o impacto da fumaça de cigarro na sinalização osteogênica e osteoclastogênica da sutura palatina mediana de ratos. Foram utilizados ratos Wistar machos expostos (n=30) e não expostos à fumaça de cigarro (n=30). A exposição à fumaça de cigarro foi realizada duas vezes ao dia por 3 minutos, com um intervalo de 12 horas entre as exposições. Os animais foram mortos após o período experimental de 3, 7, 14 e 21 dias. Os tecidos coletados foram analisados em microscópico de luz e pelo RT-PCR em tempo real foi realizado para investigar a expressão gênica. s dados obtidos foram comparados usando o testes de Kruskal Wallis e Dunn (⍺ = 5%). Morfoligicamente, não houve mudança significativa na sutura palatina mediana nos ratos expostos ou não à fumaça de cigarro durante os tempo de 3, 7, 14 e 21 dias (p> 0.05). Por outro lado, a sinalização osteogênica esta aumentada nos animais expostos à fumaça e foi caracterizado por um aumento da produção de RANKL aos 3 e 14 dias (p <0.05), sem mudança na síntese da produção de RANK e osteoprotegerina (p> 0.05). Curiosamente, nos animais expostos, também foi observado um aumento precoce da síntese de osteocalcina, sialoproteína óssea e de osteopontina aos 3 dias de exposição, o que não foi mantido ao longo do tempo. A fumaça de cigarro modula a sinalização osteogênica e osteoclastogênica na sutura palatina mediana de ratos jovens, apesar de não tenha sido evidenciado alterações morfológicas.

Establishing the Finite Element Model of Mid-Palatal Suture Fracture by Microimplant-Assisted Palatal Expansion / 医用生物力学

Objective To analyze mechanical characteristics for stress accumulation of the maxillary complex during expansion until complete fracture of the mid-palatal suture by using the three-dimensional (3D) finite element method, and verify validity of the model. Methods The finite element maxillary complex model containing the microimplants was established. The yield strength of the mid-palatal suture was set, and the transverse displacement of 0.25 mm was loaded every 5 ms as the load until the suture was completely fractured. The CT images of one clinical patient before and after expansion were compared and verified. Results During 0-17 ms, the stress was mainly concentrated around the microimplants, the middle of the mid-palatal suture and the zygomatico-maxillary sutures. During 18-60 ms, cracks began to occur in the mid-palatal suture, and expanded forward and backward. During 61-71 ms, the rupture path was followed by posterior part of the mid, palatal suture-the front part and the back part. Conclusions The 3D finite element model of microimplant-assisted expansion based on fracture mechanics was effective and the calculated fracture process result were more consistent with clinical practice. The research findings provide the mechanical reference model for more effective research on microimplant-assisted palatal expansion in the future.

Ectopic maxillary premolar in palatal suture with a supernumerary tooth in the mentum region: a case report / 华西口腔医学杂志

Ectopic tooth is a common problem reported in clinics. Ectopic tooth generally occurs around its primary position, and long-distance displacement is rare. A case of ectopic maxillary premolar in palatal suture with a supernumerary tooth in the mentum region was reported in this study, and the relevant literature is presented in this paper.