The purpose of this study was to determine the prevalence of odontogenic cysts at the Pernambuco School of Dentistry - Universidade de Pernambuco (Brazil) and compare this prevalence with other international studies. Data for the study were obtained from reports of patients diagnosed with odontogenic cysts between 1992 and 2007. Case records of patients who fit the Histological Classification of the World Health Organization (2005) were included. The following variables were analyzed: gender, age group, anatomical location, histological type and ethnic background. Odontogenic cysts accounted for 9.94% of all lesions biopsied throughout the study period. Mean patient age was 28.9 years and 57.6% of the patients were males (P > 0.05). Radicular cyst was the most prevalent histological type (52.2%), followed by dentigerous cyst (30.7%). Regarding ethnic background, 41.8 % of the patients were of African descent, followed by Caucasians and other ethnic groups (P > 0.05). The mandible was the most prevalent site of the lesions (56%). Odontogenic cysts appear to have a distinct predilection for the male gender, the second and third decades of life (P < 0.05) and are more frequent in the mandible. The removal of odontogenic keratocysts from the new WHO classification has not altered the order of the most prevalent cysts in the maxillofacial complex.

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Ameloblastic fibroma (AF) is an extremely rare true mixed benign tumor that can occur in either the mandible or the maxilla, but is most frequently found in the posterior region of the mandible. It usually occurs in the first two decades of life and is associated with tooth enclosure, causing a delay in eruption or altering the dental eruption sequence. AF is diagnosed on routine radiographic evaluation and is clinically and radiographically similar to ameloblastic fibrodontoma and odontoma, which makes an accurate diagnosis mandatory. There is controversy in the literature as to whether treatment should be conservative or agressive. A conservative treatment strategy, such as enucleation and curettage, is usually sufficient. However, extensive lesions require radical treatment. We describe a case of ameloblastic fibroma with a very unusual clinical manifestation: it demonstrated considerable extension but no associated impacted tooth, was located in the anterior region of the mandible, and became symptomatic in the fifth decade of life. A radical surgical approach was taken, with immediate reconstruction.

The aim of the present study was to histologically analyze the effects of bovine and human demineralized bone matrix and a Ricinus communis polymer on the bone regeneration process. Two surgical bone defects were created in rabbit calvaria, one on the right and the other on the left side of the parietal suture. Eighteen rabbits were divided into three groups. In Group I, the experimental defect was treated with bovine demineralized bone matrix, Group II with human demineralized bone matrix, and in Group III, the experimental cavity was treated with polyurethane resin derived from Ricinus communis oil. The control defects were filled with the animals' own blood. The animals were sacrificed after 7 and 15 weeks. Histological analysis revealed that in all groups (control and experimental), bone regeneration increased with time. The least time required for bone regeneration was noted in the control group, with a substantial decrease in the thickness of the defect. All materials proved to be biologically compatible, but polyurethane resorbed more slowly and demonstrated considerably better results than the demineralized bone matrices.

Both materials proved to be biologically compatible, however polyurethane was more slowly resorbed presented considerable better results when compared with demineralized bone matrix.