Case Report Recurrent Monostotic Fibrous Dysplasia in the Mandible Nilton Alves, 1 Reinaldo José de Oliveira, 2 Denise Takehana, 2 and Naira Figueiredo Deana 3 1 CIMA Research Group, Faculty of Dentistry, La Frontera University, 1145 Francisco Salazar Avenue, P.O. Box 54-D, 4780000 Temuco, Chile 2 Faculty of Sciences of Guarulhos (FACIG), 1844 Guarulhos Avenue, 7196 Guarulhos, SP, Brazil 3 Private Physical Terapist, 1171 Pasaje Frankfurt, 4780000 Temuco, Chile Correspondence should be addressed to Nilton Alves; niltonnalves@yahoo.com.br Received 25 March 2016; Accepted 15 May 2016 Academic Editor: Giuseppe Colella Copyright © 2016 Nilton Alves et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Fibrous dysplasia (FD) is a condition in which normal bone marrow is replaced by an abnormal proliferation of new fbrous connective tissue. Female patient, white, 20 years old, attended the dental clinic reporting a slow increase in volume in the right mandible region over the last 5 years. She was examined by imaging: the panoramic X-ray revealed a lesion with the appearance of ground glass while the cone-beam computed tomography showed an extensive lesion in the region of the right hemimandible. Te histopathological examination was compatible with fbrous dysplasia. Bone gammagraphy was indicated, plus an endocrinological study to eliminate polyostotic forms, which produced a negative result. Monostotic fbrous dysplasia in the right hemimandible was diagnosed. Conservative surgery was carried out and afer 1 year recurrence of the tumour was observed. We may conclude that conservative surgery might not be the best choice for treatment for monostotic fbrous dysplasia in the mandible and that other options must be considered, such as radical surgery or the use of bisphosphonates. In our study, we may also conclude that it is very important to explain to the patient the possibility of recurrence of the lesion and the need for monitoring with periodic imaging studies. 1. Introduction Fibrous dysplasia (FD) is a condition in which normal bone marrow is replaced by an abnormal proliferation of new fbrous connective tissue [1, 2]. FD is caused by the genetic mutation of the cell-surface receptor guanine nucleotide protein (G protein) [3]. Te - subunit of the stimulatory G protein (G S ) activates the adenylyl cyclase, which in turn catalyzes the formation of cyclic adenosine monophosphate from ATP [4]. Te gene for G S  (GNAS1), when it sufers a mutation, is associated with the FD disorder spectrum. Tis mutation occurs in a somatic cell producing somatic mosaicism, in which the cells descending from the mutated cell produce abnormal characteristics, while the cells descending from the unaf- fected cells produce normal characteristics [5]. Te increase in the activity of stimulatory G protein (G S ) in osteoblast progenitor cells is thought to be the result of an increase in their proliferation and abnormal diferentiation. Studies have established a link between the G S  mutation and the increased production of interleukin-6 stromal cells, which promotes osteoclast activity [6]. Tus, the complex of the FD pathogenesis arises from an imbalance between bone formation and destruction [7]. It generally appears in the frst or second decade of life; it is asymptomatic, progresses slowly, and afects women twice as frequently as men [1, 2]. It afects the maxilla more fre- quently than the mandible and may involve one (monostotic) or less commonly two or more bones (polyostotic) [1]. Te signs and symptoms vary depending on the type and location of the FD and include facial deformity and asymmetry, visual alteration, auditory disability, nasal congestion and/or obstruction, pain, paraesthesia, or malocclusion [8]. Te den- tal arch is usually maintained, although tooth displacement, malocclusion, and interference with dental eruption may occur occasionally [1]. Te object of this paper is to present a case of recurrent monostotic fbrous dysplasia in the mandible region, which Hindawi Publishing Corporation Case Reports in Dentistry Volume 2016, Article ID 3920850, 6 pages http://dx.doi.org/10.1155/2016/3920850