Wear resistance of nickel-titanium endodontic files after surface treatment.

OBJECTIVES: The purpose of this work was to submit the Nitinol files to plasma immersion ion implantation (PIII) and evaluate the effects of the surface treatment. MATERIALS AND METHODS: Wear resistance was determined in vitro by using an equipment for the application of horizontal movements on previously prepared notched plates made of resin. Vickers microhardness was measured in plates and files, before and after surface treatment and the surface chemical composition of the instruments was determined by X-rays photoelectron spectroscopy. RESULTS: The hardness values found for the treated Nitinol files were significantly lower than the hardness values measured before the implantation process. The comparison of commercially available instruments shows that the wear resistance of the stainless steel file is higher than the resistance of the Nitinol. CONCLUSIONS: The results found led to the conclusion that the surface treatment significantly increased the Nitinol files wear resistance.

Aggressive behaviour of cherubism in a teenager: 4-years of clinical follow-up associated with radiographic and histological features.

Cherubism is a rare hereditary fibro-osseous childhood disease characterized by bone degradation and fibrous tissue replacement at the angles of the mandible and at the tuberosity areas of the maxilla that leads to prominence of the lower face and an appearance reminiscent of the cherub's portrayal in Renaissance art. This disease has an autosomal dominant hereditary characteristic. The purpose of this report is to analyse laboratory tests, clinicopathological and radiographic features of cherubism and its intraoral manifestations in a patient during 4-years of follow-up, correlating the features observed in this case with those of the literature. Also discussed is the atypical and aggressive behaviour of this case during puberty.