A Retrospective Histological Study on Palatal and Gingival Mucosa Changes during a Rapid Palatal Expansion Procedure

Abstract

The most common inflammatory reactions in the oral mucosa are found at the gingival level. The treatment of these inflammations requires, first of all, the removal of the causative factor; often, this maneuver is sufficient. The aim of this retrospective study was to evaluate clinical and histopathological changes that occur in terms of gingival and palatal mucosa enlargement during palatal expansion treatment and their evolution during treatment. Twenty-five (n = 25) research participants, aged between thirteen and twenty-six years old, were examined in this retrospective study. At the end of the treatment, fragments of tissue from the affected level were obtained via incisional biopsy and sent to the histopathology laboratory for a specialized examination. The changes identified were specific to mechanical traumatic injuries, thus excluding hyperplasia from other etiologies (infectious, tumoral, or non-mechanical traumatic). The examined fragments showed hyperplasia. The histopathological examination revealed the mechanical character of the lesion, strengthening the causal relationship between the insertion of the expander and the occurrence of hyperplasia of the palatal mucosa. The type of palatal expander influenced the degree of inflammation, with the severity of hyperplasia being more pronounced in the case of mini-implant-anchored rapid palatal expander (MARPE) usage than in the case of tooth-borne rapid palatal expander (RPE) usage. The analysis of the distance between the expander and the palatal mucosa did not provide conclusive results; the incidence and severity of the reaction were variable in patients with the same distance between the expander and the palatal or gingival mucosa.

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“…The oral cavity has several functional structures, including the tongue, salivary glands, cheeks, lips, and palate including teeth, all of which play an important role in physiological processes [35,36]. Histologically, the oral mucosa is a multilayered structure consisting of the epithelium (basement membrane and chorion), and the epithelium presents the stratum basale (basal layer), stratum spinosum (spinous layer), stratum granulosum (granular layer), and stratum corneum [35][36][37][38]:…”

“…These cells have intensely colored voluminous nuclei located in the basal third of the cells. Basal cells exhibit intense metabolism and frequent mitoses that provide flaking turnovers [35][36][37][38]; -The stratum spinosum is arranged above the basal layer and presents 7-8 rows of well-defined polyhedral cells with visible intercellular spaces; between the cells of the stratum spinosum there are fine cytoplasmic filaments arranged in the form of thorns. The nuclei of the cells of the spinosum stratum stain less intensely than the nuclei of the cells of the stratum basale, so that the stratum spinosum is well delineated from the stratum basale.…”

“…The nuclei of the cells of the spinosum stratum stain less intensely than the nuclei of the cells of the stratum basale, so that the stratum spinosum is well delineated from the stratum basale. The cells in the deep areas of the stratum spinosum show mitosis and together with the basal cells form the germinative zone of the epithelium, and towards the surface, the cells of the stratum spinosum become flatter [35][36][37][38]; -…”

“…The stratum granulosum occurs when there is also the stratum corneum, and in the absence of the stratum corneum, may be absent. It is located above the stratum spinosum and consists of 2-3 rows of flattened cells that present kerato-hyaline granules in the cytoplasm [35][36][37][38]; -…”

“…The cells of the stratum corneum are flattened and degenerated with nuclear pycnosis, or without nuclei, they are weakly joined to each other. The ep-ithelium is separated from the dermis by the basement membrane, which presents itself as a condensation of the fundamental substance of the underlying connective tissue [35][36][37][38].…”