Photoelastic study of the support structures of distal-extension removable partial dentures.

PURPOSE: The double system of support, in which the distal-extension removable partial denture adapts, causes inadequate stress around abutment teeth, increasing the possibility of unequal bone resorption. Several ways to reduce or more adequately distribute the stress between abutment teeth and residual ridges have been reported; however, there are no definitive answers to the problem. The purpose of this study was to analyze, by means of photoelasticity, the most favorable stress distribution using three retainers: T bar, rest, proximal plate, I bar (RPI), and circumferential with mesialized rest. MATERIALS AND METHODS: Three photoelastic models were made simulating a Kennedy Class II inferior arch. Fifteen dentures with long saddles, five of each design, were adjusted to the photoelastic patterns and submitted first to uniformly distributed load, and then to a load localized on the last artificial tooth. The saddles were then shortened and the tests repeated. The quantitative and qualitative analyses of stress intensity were done manually and by photography, respectively. For intragroup analyses the Wilcoxon test for paired samples was used, while for intergroup analyses Friedman and Wilcoxon tests were used to better identify the differences (p < 0.05). RESULTS: The RPI retainer, followed by the T bar, demonstrated the best distribution of load between teeth and residual ridge. The circumferential retainer caused greater concentration of stress between dental apexes. Stress distribution was influenced by the type of retainer, the length of the saddle, and the manner of load application. CONCLUSIONS: The long saddles and the uniformly distributed loads demonstrated better distribution of stress on support structures.

Mandibular periosteal (juxtacortical) chondrosarcoma.

Periosteal (juxtacortical) chondrosarcoma (PC) is a well-differentiated malignant cartilage-forming tumor arising from the external bone surface, especially in long bones. The therapy of choice is en-bloc resection and, in general, its prognosis is good. This paper reports a rare case of PC affecting the mandible of a 41-year-old man. The lesion presented as a slow-growing-painless swelling that lasted 2 months. Computed tomography scan showed a tumoral mass arising from the external bone surface, extending into the adjacent soft tissue presenting patchy regions of popcorn-like calcifications. A final diagnosis of PC (grade II) was rendered after biopsy. Hemimandibulectomy was undertaken followed by complementary radiotherapy with 70 Gy. Although no episodes of recurrence or metastasis had been noticed after 18 months of follow-up, the patient died and causa mortis could not be established.

Mandibular periosteal (juxtacortical) chondrosarcoma

Periosteal (juxtacortical) chondrosarcoma (PC) is a well-differentiated malignant cartilage-forming tumor arising from the external bone surface, especially in long bones. The therapy of choice is en-bloc resection and, in general, its prognosis is good. This paper reports a rare case of PC affecting the mandible of a 41-year-old man. The lesion presented as a slow-growing-painless swelling that lasted 2 months. Computed tomography scan showed a tumoral mass arising from the external bone surface, extending into the adjacent soft tissue presenting patchy regions of popcorn-like calcifications. A final diagnosis of PC (grade II) was rendered after biopsy. Hemimandibulectomy was undertaken followed by complementary radiotherapy with 70 Gy. Although no episodes of recurrence or metastasis had been noticed after 18 months of follow-up, the patient died and causa mortis could not be established.

Condrossarcoma (juxtacortical) periosteal (CP) é um tumor maligno produtor de cartilagem bem diferenciado que normalmente surge na superfície externa dos ossos longos. O tratamento de escolha para esse tumor é a ressecção em bloco e, em geral, apresenta um prognóstico bom. Nesse trabalho, nós apresentamos um caso raro de CP afetando a mandíbula de um homem de 41 anos de idade. A lesão apresentava um crescimento lento e indolor de 2 meses de evolução. A tomografia computadorizada revelou a presença de uma massa tumoral surgindo na superfície externa do osso mandibular exibindo agregados de tecido calcificado no seu interior e que se estendia para os tecidos moles adjacentes. Depois de realizada uma biópsia, um diagnóstico final de CP (grau II) foi estabelecido. O tratamento de escolha foi hemimandibulectomia seguida por radioterapia complementar na dose de 70 Gy. Embora nenhum episódio de recorrência ou metástase tenha sido noticiado após 18 meses de acompanhamento, o paciente morreu e a causa mortis não pôde ser determinada.

Primeiro pré-molar inferior trirradiculado: Relato de caso / Three-rooted first lower premolar: a case report

Embora a ocorrência de três raízes em um primeiro pré-molar inferior não seja uma situação comum, o profissional deve conhecer a possibilidade de esse dente vir a ser trirradiculado. Este fato deve ser avaliado com cautela para que se evitem riscos durante atos cirúrgicos e outros procedimentos realizados na cavidade oral, tais como tratamentos endodônticos. Observou-se a presença de três raízes em primeiros pré-molares inferiores do acervo da disciplina de Anatomia Humana do Instituto de Ciências Biomédicas da Universidade Federal de Uberlândia, confirma-se a possibilidade de acordo com relatos da literatura.

The occurrence of a three-rooted first lower premolar is an uncommon situation; however, theprofessional must be informed about the possibilities of finding this tooth with three roots. This fact must be analyzed with cautious to avoid risks when performing dental surgeries, and others procedures in the oral cavity, such as endodontic treatments. The purpose of this paper was to support the possibility of this tooth being three-rooted, according to data available.