Ameloblastic carcinoma ex ameloblastoma: report of a case-possible involvement of CpG island hypermethylation of the p16 gene in malignant transformation.

Ameloblastic carcinoma is described in the updated World Health Organization (WHO) classification as a rare malignant lesion. Ameloblastic carcinoma meeting the WHO criteria may arise either as a result of malignant change in a pre-existing benign ameloblastoma (carcinoma ex ameloblastoma) or as a primary malignant ameloblastoma not preceded by an ordinary ameloblastoma (de novo carcinoma). We report a case of ameloblastic carcinoma ex ameloblastoma and examine how this case underwent malignant transformation. The DNA was extracted separately from benign and malignant areas in paraffin sections of the tumor. Direct sequencing showed no genetic mutation of exons 5-8 of the p53 gene. Hypermethylation of CpG islands of the p16 gene was detected in the malignant parts of the tumor. The results indicate that hypermethylation of p16 may have been involved in the malignant transformation of the ameloblastoma in the present case.

Er:Yag laser irradiation of the microbiological apical biofilm.

One problem in cases of healing-resistant periapical lesions is to eradicate the contamination at the periapical area. This contamination is due to the microbiological biofilm formed by microorganisms and their subproducts lodged in apical third of the root, on both cementum and dentin surface. Paraendodontic surgery consists of the mechanical removal of harmful agents to promote healing and periapical health. The purpose of this study was to assess the results of Er:YAG laser irradiation on the apical root third of newly extracted teeth to eliminate microbial contamination on root apex surface. Apical irradiation was performed with an Er:YAG laser device using an experimental contact tip, at 100 mJ, 10 Hz, 1 W, 39 J/cm(2), 3 times on the target area. SEM analysis showed the elimination of part of the irradiated cementum and the formation of small roughened without exposing the subjacent dentin. Vaporization of the remaining periodontal tissue and removal of microbiological apical biofilm (MAB) were also observed on the irradiated areas. Under the tested conditions and based on the findings of this study, Er:YAG laser may be considered effective for removal of microbiological apical biofilm.

Er: Yag laser irradiation of the microbiological apical biofilm

One problem in cases of healing-resistant periapical lesions is to eradicate the contamination at the periapical area. This contamination is due to the microbiological biofilm formed by microorganisms and their subproducts lodged in apical third of the root, on both cementum and dentin surface. Paraendodontic surgery consists of the mechanical removal of harmful agents to promote healing and periapical health. The purpose of this study was to assess the results of Er:YAG laser irradiation on the apical root third of newly extracted teeth to eliminate microbial contamination on root apex surface. Apical irradiation was performed with an Er:YAG laser device using an experimental contact tip, at 100 mJ, 10 Hz, 1 W, 39 J/cm², 3 times on the target area. SEM analysis showed the elimination of part of the irradiated cementum and the formation of small roughened without exposing the subjacent dentin. Vaporization of the remaining periodontal tissue and removal of microbiological apical biofilm (MAB) were also observed on the irradiated areas. Under the tested conditions and based on the findings of this study, Er:YAG laser may be considered effective for removal of microbiological apical biofilm.

A problemática dos casos envolvendo pacientes portadores de lesões periapicais resistentes é a eliminação da infecção que atinge a região periapical. Esta infecção é composta por microrganismos e seus subprodutos alojados no cemento e dentina do terço apical, sob forma de biofilme microbiano. A execução da cirurgia paraendodôntica com vistas à promoção da saúde do periápice, invariavelmente resume-se em remover mecanicamente os agentes causadores da doença, com objetivo de proporcionar a reparação. O propósito deste estudo foi avaliar o resultado da irradiação com laser de Er:YAG no terço apical de dentes recém extraídos com relação à infecção microbiana na superfície do ápice radicular. O laser Er:YAG foi empregado para irradiação de ápices radiculares, com ponteira experimental de contato (Chisel, Morita co.), utilizando energia de potência de 100 mJ, 10 Hz, por 3 vezes em área delimitada no terço apical das raízes. Os resultados do estudo em microscopia eletrônica de varredura mostraram a eliminação do tecido periodontal remanescente juntamente com quantidade significativa de microrganismos. Portanto, pode-se concluir que o laser de Er:YAG nas condições experimentais testadas mostrou-se efetivo na remoção de microrganismos do tecido periodontal contaminado e do cemento sem expor a dentina subjacente.