The aim of the present article is to present the clinical case of a large peripheral ossifying fibroma that evolved from a previously diagnosed pyogenic granuloma in a 50-year-old woman. The patient was referred for treatment of a lesion over the buccal and palatal gingiva close to the left upper first molar. It was purplish-red in color, approximately 3 cm in diameter, having a smooth surface, a pedicled and bleeding base, with seven years of evolution, and diagnosed as pyogenic granuloma. After three years of evasion, the patient returned reporting an increase in the lesion and difficulty in eating. Clinically the nodule was lobular in appearance, pink in color and smooth, pediculated, firm in consistency, non-bleeding, about 5 cm in its greatest extension, extending to the maxillary tuberosity. The lesion was excised and referred for histopathological examination, which led to the diagnosis of peripheral ossifying fibroma. The patient was followed for approximately 18 months, prosthetically rehabilitated, with satisfactory healing and no clinical signs of recurrence.The possible evolution of a pyogenic granuloma to a peripheral ossifying fibroma was observed in this case, based on the histopathological changes that occurred, with the development of calcified material, fibrous maturation, and decreased vascular content of the initial lesion after three years.

Odontogenic cysts are benign non-neoplastic lesions that originate from epithelial cells Arachnida-Araneae) community in the process of the teeth development. Among them, the odontogenic keratocyst is a developmental cyst characterized by its epithelium of parakeratinized stratified and aggressive squamous cells as well as infiltrative behavior. Thus, the objective of this study was to describe a clinical case of surgical treatment of odontogenic keratocysts in a 52-year-old female patient, who presented for the treatment of a large lesion in a region of the left mandibular body and angle. After incisional biopsy and installation of a decompression device, the histopathological diagnosis of odontogenic keratocyst was obtained. Subsequently to a period of 9 months with the decompression device in place, a decrease of the lesion was noticed, thus allowing intervention to be performed the excision of the lesion. Thus, the patient was subjected, under general anesthesia, to enucleation of the lesion as the main treatment, with complementary maneuvers of peripheral ostectomy and application of Carnoy solution over the remaining bone bed. After an outpatient follow-up of 16 months, no signs of recurrence of the lesion were observed. The proposed treatment was efficient in removing the keratocyst with minimal surgical morbidities. In conclusion, the treatment protocol was effective and conservative in the surgical management of the lesion, allowing rapid recovery and return of the  function.       Keywords: Bone Cysts. Decompression. Dental Care. ResumoCistos odontogênicos são lesões benignas não-neoplásicas que tem por origem células remanescentes epiteliais do processo de formação do órgão dental. Dentre elas, o queratocisto odontogênico é um cisto de desenvolvimento caracterizado por seu epitélio de células escamosas estratificadas paraqueratinizadas, pelo comportamento agressivo e infiltrativo. Sendo assim, o objetivo desse estudo foi descrever um caso clínico de tratamento cirúrgico do queratocisto odontogênico em uma paciente do gênero feminino de 52 anos de idade, que compareceu para o tratamento de uma lesão de grande porte em região de corpo e ângulo mandibulares à esquerda. Após biópsia incisional e instalação de um dispositivo descompressivo, obteve-se o diagnóstico histopatológico de queratocisto odontogênico. Posteriormente a um período de 9 meses com o dispositivo de descompressão em posição, notou-se uma diminuição da lesão, permitindo assim a execução de intervenção para exérese da lesão. Assim, a paciente foi submetida, sob anestesia geral, à enucleação da lesão como tratamento principal, com manobras complementares de ostectomia periférica e aplicação de solução de Carnoy sobre o leito ósseo remanescente. Após um acompanhamento ambulatorial de 16 meses, não foi observado nenhum sinal de recorrência da lesão. O tratamento proposto foi eficiente em remover o queratocisto com as mínimas morbidades cirúrgicas. Concluindo, o protocolo de tratamento foi efetivo e conservador no manejo cirúrgico da lesão, permitindo rápida recuperação e retorno da função. Palavras-chave: Cistos Ósseos. Descompressão. Assistência Odontológica.

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