Computação massivamente paralela para identificação de marcadores RFID

Mestrado em Engenharia de Computadores e TelemáticaNos dias que correm, tem-se assistido a uma grande evolução dos sistemas de identificação através de marcadores RFID, frequentemente sem se dar a devida importância à componente de privacidade nos mesmos. A presente dissertação pretende explorar um paradigma de identificação de marcadores com o intuito de colmatar esta lacuna, recorrendo à utilização de uma função dificilmente invertível, criptográfica ou de síntese, para a geração no marcador de um identificador pseudo-aleatório a partir do identificador real do mesmo, bem como de um conjunto de números aleatórios gerados pelo marcador e pelo leitor. Contudo, torna-se necessária uma pesquisa ao longo de todos os identificadores atribuídos, que por questões de desempenho é realizado de uma forma massivamente paralela. Desta forma, impede-se o seguimento de objectos ou pessoas associados ao marcador por entidades Ilegítimas, que não tenham acesso a uma base de dados de todos os identificadores atribuídos.In recent years, there has been a large evolution of identification systems through the use of RFID tags, often with some disregard for privacy concerns. In this dissertation a paradigm will be explored focusing on the use of a well known cryptographic standard or hashing function to generate a pseudo-random identifier from the real identifier as well as a set of random nonces from the tag and reader. However, a search is required along the set of assigned identifiers, which for the sake of performance shall be done resorting to a massively parallel approach. This way, it becomes unfeasible for an illegitimate reader to relate two activation sessions of the same tag without access to the database of all the assigned identifiers

Lowering of the mouth floor and vestibuloplasty to support a mandibular overdenture retained by two implants: a case report

In Oral Implantology most of the procedures are predictable and have high success rates. The use of osseointegrated implants as a therapeutic option for the rehabilitation of patients with severe mandibular atrophy has decreased the need for pre-prosthetic surgery Nevertheless, complications may occur during implant surgery and also once the prosthesis has been placed. This paper describes the case of a totally edentulous patient with an upper complete removable denture and an implant-retained overdenture with two implants in the intermentonian region. During clinical examination, the implant abutments were totally covered by soft tissue since the floor of the mouth was elevated. The panoramic radiography showed severe mandibular atrophy. Vestibuloplasty was performed together with the lowering of the floor of the mouth under general anesthesia and nasotracheal intubation to expose the implants. A new prosthesis was fabricated for the patient to prevent recurrence and improve the patient's chewing ability as it formed a physical barrier against soft tissue migration on prosthetic attachments

Stafne's bone cavity: An unusual case with involvement of the buccal and lingual mandibular plates

Lingual mandibular bone defects, also known as Stafne bone cavity (SC), are unilateral asymptomatic radiolucencies, generally seen in the mandibular angle, below the inferior alveolar canal. Although panoramic radiographies normally offer enough information to make a correct diagnosis, additional studies are often required, especially in atypical cases. The present report describes an atypical presentation of a Stafne's bone cavity in a 78 years-old male patient. In this particular case, an asymptomatic and radiolucid lesion was observed during a routine dental examination. The computed tomography (CT) showed an involvement of both lingual and buccal mandibular plates producing a tunnel-like lesion. No history of mandibular trauma or surgery was refered. An additional magnetic resonance imaging (MRI) was made to discard submandibular gland pathology and to confirm the diagnosis. Since SC is asymptomatic and nonprogressive, a conservative approach based in clinical and radiological follow-ups was considered to be the most suitable treatment option

Retrospective clinicopathological study of 418 odontogenic cysts

Objectives: To determine the relative incidence of odontogenic cysts and to identify the main clinicopathological features among patients treated in the Oral Surgery Department of the Dental Clinic of the University of Barcelona (Spain). Study design: A retrospective observational study was made of 418 odontogenic cysts diagnosed in 380 patients included in the database of 1235 histopathological diagnoses. The subjects were treated in the Master degree program of Oral Surgery and Implantology of the University of Barcelona in the period 1997-2006. The following variables were recorded: gender, age, clinical characteristics of the lesions (size and location), radiological features, duration, treatment, complications and relapses. A descriptive analysis was made of the study variables, using the SPSS version 15.0. Results: The incidence of odontogenic cysts was 33.8%. The mean patient age at appearance of the lesion was 42 years (range 7-83). The cysts were slightly more prevalent in males (58.4%). The lesion size ranged from 2-60 mm, with a mean size of 18.4 mm. The most frequent diagnosis was radicular cyst (50.2%). The most common location of the odontogenic cysts was in the mandible (61.5%), particularly the lower third molar region (36.8%). Conclusions: The most frequently diagnosed lesion was the radicular cyst. Odontogenic cysts were seen to be slightly more prevalent in males, and showed a high mandibular incidence. Knowledge of the biological and histological behavior of odontogenic cysts and their frequency are key aspects for ensuring early detection and adequate treatment

Surgical treatment vs. conservative treatment in intravenous bisphosphonate-related osteonecrosis of the jaws. Systematic review

Aims: To determine the success rates of the surgical and non-surgical treatments in the management of bisphosphonate-related osteonecrosis of the jaws (BRONJ). Material and Methods: A systematic review of the literature was made. A PubMed Medline database search was performed in order to include clinical studies published in English, between 2004 and 2014 with the following keywords: "BRONJ AND treatment" and "NOT osteoporosis". The following data was gathered: authors, title, year of publication, aim of study, level of evidence, sample size, treatment performed, treatment outcomes and follow-up. Studies including more than 20 patients with at least 6 months of follow-up, and that specify the different treatment approaches and their outcomes were included. Systematic reviews were excluded. All studies were classified according to the SORT criteria (Strength of Recommendation Taxonomy). Results: The initial electronic search yielded 169 papers, and 13 studies were added after a manual search (total of 182 studies). After analysing the title and abstract and removing duplicates, 31 full-texts were obtained. A total of 12 papers were finally included. Two were classified as level 3 evidence and 9 as level 2. The quality of the selected studies and the risk of bias were also reported. Conclusions: Surgical treatments like sequestrectomy, surgical debridement and bone osteotomies provide successful treatment outcomes, with success rates ranging from 58 to 100%. Controlled randomized clinical trials with larger samples and longer follow-up are needed to support these findings

Sensibility and taste alterations after impacted lower third molar extractions. A prospective cohort study

Objectives: To determine the incidence, severity and duration of lingual tactile and gustatory function impairments after lower third molar removal. Study Design: Prospective cohort study with intra-subject measures of 16 patients undergoing lower third molar extractions. Sensibility and gustatory functions were evaluated in each subject preoperatively, one week and one month after the extraction, using Semmes-Weinstein monofilaments and 5 different concentrations of NaCl, respectively. Additionally, all patients filled a questionnaire to assess subjective perceptions. Results: Although patients did not perceive any sensibility impairments, a statistically significant decrease was detected when Semmes-Weinstein monofilaments. This alteration was present at one week after the surgical procedure and fully recovered one month after the extraction. There were no variations regarding the gustatory function. Conclusions: Lower third molar removal under local anesthesia may cause light lingual sensibility impairment. Most of these alterations remain undetected to patients. These lingual nerve injuries are present one week after the extraction and recover one month after surgery. The taste seems to remain unaffected after these procedures

Quality of life after upper third molar removal: a prospective longitudinal study

Background: Third molar extraction is a very common procedure in Dentistry. The aim of this study was to evaluate the quality of life (QoL) and satisfaction of patients undergoing extraction of an upper third molar under local anesthesia. A second objective was to describe the evolution of self-reported pain measured in a visual analogue scale (VAS) in the 7 days after surgery and its relationship with pre- and intraoperative factors. Material and Methods: A prospective longitudinal cohort study was made. Fifty-five patients received a questionnaire assessing social and working isolation, eating and speaking ability, diet modifications, sleep impairment, physical appearance, discomfort at suture removal and overall satisfaction. Pain was registered daily on a VAS scale. A descriptive and bivariate analysis of the data was performed. Results: Forty-seven patients were included. Pain decreased lineally across the 7 days, and relief was significant between days 2 and 3. Intraoperative complications were significantly associated with pain. The complication that showed the highest pain score was the tuberosity fracture. Conclusions: Upper third molar removal significantly affects the patient's quality of life, particularly during the first 2 days after extraction

Traumatic bone cyst: a retrospective study of 21 cases

Objective: To describe the clinical and radiological characteristics, and surgical findings of traumatic bone cysts. Study Design: A retrospective observational study was made of 21 traumatic bone cysts. The diagnosis was based on the anamnesis, clinical examination, and complementary tests. Panoramic and periapical X-rays were obtained in all cases, together with computed tomography as decided by the surgeon. A descriptive statistical analysis was made of the study variables using the SPSS v12.0 for Windows. Results: There was a clear female predominance (14:7). The mean age was 26.5 years (range 8-45 years). The cysts in all cases constituted casual findings during routine radiological exploration. In those cases where computed tomographic images were available, preservation of the vestibular and lingual cortical layers was observed. Five of the 21 patients (23.8%) reported a clear antecedent of traumatism in the affected zone. All the lesions were subjected to surgery, and the cavities were found to be vacant in 90.5% of the cases. In only two patients were vascular contents seen within the cavity. Two of the patients presented postoperative paresthesia of the inferior dental nerve that subsided within two weeks. The 19 patients in whom adequate postoperative follow-up proved possible all showed complete bone healing. Conclusions: Traumatic bone cysts were a casual finding. During the surgery, most cases showed to be vacant cavity without an ephitelial lining. Careful curettage of the lesion favors progressive bone regeneration, offering a good prognosis and an almost negligible relapse rate. Other treatment options only would be justified in cases of relapse

Cistoadenoma de glándulas salivales menores. Presentación de dos casos y revisión de la literatura

El cistoadenoma es un tumor salival benigno de origen epitelial muy infrecuente que se caracteriza por presentar múltiples proyecciones papilares y espacios microquísticos recubiertos de células cilíndricas o cuboideas. La OMS define el cistoadenoma como una neoplasia salival muy similar al tumor de Warthin, que carece de componente linfoide. La mayoría de cistoadenomas se han descrito a nivel de la laringe, la nasofaringe, así como en la glándula parótida y las glándulas lacrimales. Sin embargo, pueden localizarse con menor frecuencia en las mucosas labial y bucal, en la fosa tonsilar y en el paladar. El 35% se sitúan en las glándulas salivales menores

Long-term outcomes of oral rehabilitation with dental implants in HIV-positive patients: A retrospective case series

Background: The existing information on oral rehabilitations with dental implants in VIH-positive patients is scarce and of poor quality. Moreover, no long-term follow-up studies are available. Hence, the aims of this study were to describe the long-term survival and success rates of dental implants in a group of HIV-positive patients and to identify the most common postoperative complications, including peri-implant diseases. Material and Methods: A retrospective case series of HIV-positive subjects treated with dental implants at the School of Dentistry of the University of Barcelona (Spain) was studied. Several clinical parameters were registered, including CD4 cell count, viral load and surgical complications. Additionally, the patients were assessed for implant survival and success rates and for the prevalence of peri-implant diseases. A descriptive statistical analysis of the data was performed. Results: Nine participants (57 implants) were included. The patients' median age was 42 years (IQR= 13.5 years). The implant survival and success rates were 98.3% and 68.4%, respectively, with a mean follow-up of 77.5 months (SD= 16.1 months). The patient-based prevalence of peri-implant mucositis and peri-implantitis were 22.2% and 44.4% respectively at the last appointment. Patients that attended regular periodontal maintenance visits had significantly less mean bone loss than non-compliant patients (1.3 mm and 3.9 mm respectively). Conclusions: Oral rehabilitation with dental implants in HIV-positive patients seems to provide satisfactory results. In order to reduce the considerably high prevalence of peri-implant diseases, strict maintenance programmes must be implemented