Efecto de la hipoxia sobre los tejidos de la cavidad oral: revisión de la literatura / Effect of hypoxia on oral tissues: a review of the literature

La exposición a hipoxia es considerada un estímulo estresante, por lo que el organismo desarrolla meca-nismos de aclimatación para asegurar la homeosta-sis. Si bien el efecto de la hipoxia sobre los distintos sistemas de tejidos y órganos ha sido bien documen-tado, el rol de los bajos niveles de O2 en la cavidad oral no ha recibido el mismo análisis. En este trabajo se revisaron los datos bibliográficos disponibles sobre el efecto de la hipoxia sobre el tejido periodontal, las glándulas salivales, la pulpa dental y el hueso mandi-bular y alveolar. De lo analizado en la bibliografía, re-sulta evidente que los bajos niveles de O2 aumentan el número de mediadores inflamatorios que inducen la progresión de la enfermedad periodontal y, a su vez, la inflamación establecida durante dicha enfermedad agrava aún más las condiciones de hipoxia tisular. Las glándulas salivales también se encuentran afectadas durante la exposición a hipoxia, disminuyendo la can-tidad de saliva secretada, observándose alteraciones ultraestructurales en el parénquima glandular. Por otra parte, se ha establecido que la hipoxia puede te-ner efectos deseados para el cultivo de células madre de la pulpa dental, lo cual resulta útil en el campo de la odontología reparativa y también para el movimien-to dental durante los tratamientos ortodónticos. En conclusión, para determinar los efectos de la hipoxia en la cavidad oral se debe analizar no sólo el tipo de tejido involucrado sino también las condiciones de hi-poxia a las cuales éste es sometido, así también como la duración de la exposición y la modalidad de hipoxia (AU)

Exposure to hypoxia is considered a stressful stimulus, therefore the organism develops acclimation mechanisms to try to ensure homeostasis. Although the effect of hypoxia on different tissues and organs has been very well documented, the role of low levels of O2 in the oral cavity has not received the same analysis. In this review, we analyzed the available bibliographic data concerning the effects of hypoxia on periodontal tissue, salivary glands, and dental pulp. The published evidence demonstrates that low O2 levels increase the number of inflammatory mediators that induce the progression of periodontal disease, and, in turn, the inflammation established during the progression of periodontitis aggravates tissue hypoxia conditions. Salivary glands are also affected during hypoxic exposure, decreasing salivary secretion, and leading to ultrastructural alterations in the glandular parenchyma. On the other hand, hypoxia could also be beneficial in some scenarios. It has been established that dental pulp cells grow better in culture under hypoxic conditions than they do in normoxia. Furthermore, mild hypoxia seems to stimulate periodontal ligament cells proliferation and matrix degradation, key events during for orthodontic treatments. In conclusion, to determine the effects of hypoxia in the oral cavity, it is necessary to analyze not only the type of tissue involved but also the hypoxic conditions to which it is subjected, as well as its duration and modality (AU)

Mandibular biomechanical behavior of rats submitted to chronic intermittent or continuous hypoxia and periodontitis.

BACKGROUND: The aim of this study was to investigate the effects of exposure to continuous (CH) and intermittent (IH) hypoxia on biomechanical properties of the mandible and periodontal tissue of animals submitted to experimental periodontitis (EP) when applying loads in a hypoxic environment. METHODS: Adult female Wistar rats were exposed during 90 days to IH or CH (simulated high altitude of 4200 m above sea level). Fourteen days prior to the euthanasia, EP was induced to half of the animals of each group. RESULTS: Only in the rats with EP, IH decreased the maximum capacity of the mandible to withstand load and the limit of elastic load. Indicators of intrinsic properties of the bone material were significantly reduced by both types of hypoxia in rats with EP. Hypoxia enhanced the alveolar bone loss induced by EP in the buccal side of the mandible, without showing additional effects in lingual or interradicular bone. Hypoxia increased prostaglandin E2 content in gingival tissue of healthy animals and further elevated the E2 levels increased by EP. CONCLUSIONS: When periodontitis is present, hypoxic stress induces a decrease in mineral properties that ultimately affects the ability of the mandible to resist load, mainly during intermittent exposure to hypoxia. These effects on bone may be related to the higher levels of prostaglandin E2 reached in the surrounding gingival tissue. The findings of this study may stimulate strategies to prevent unwanted effects of hypoxia on periodontal tissues.