Study of the surface hardness and modulus of elasticity of conventional and microwave-cured acrylic resins

The aim of this study was to evaluate the following acrylic resins: Clássico®, QC-20® and Lucitone®, recommended specifically for thermal polymerization, and Acron MC® and VIPI-WAVE®, made for polymerization by microwave energy. The resins were evaluated regarding their surface nanohardness and modulus of elasticity, while varying the polymerization time recommended by the manufacturer. They were also compared as to the presence of water absorbed by the samples. The technique used was nanoindentation, using the Nano Indenter XP®, MTS. According to an intra-group analysis, when using the polymerization time recommended by the manufacturer, a variation of 0.14 to 0.23 GPa for nanohardness and 2.61 to 3.73 GPa for modulus of elasticity was observed for the thermally polymerized resins. The variation for the resins made for polymerization by microwave energy was 0.15 to 0.22 GPa for nanohardness and 2.94 to 3.73 GPa for modulus of elasticity. The conclusion was that the Classico® resin presented higher nanohardness and higher modulus of elasticity values when compared to those of the same group, while Acron MC® presented the highest values for the same characteristics when compared to those of the same group. The water absorption evaluation showed that all the thermal polymerization resins, except for Lucitone®, presented significant nanohardness differences when submitted to dehydration or rehydration, while only Acron MC® presented no significant differences when submitted to a double polymerization time. Regarding the modulus of elasticity, it was observed that all the tested materials and products, except for Lucitone®, showed a significant increase in modulus of elasticity when submitted to a lack of hydration.

Radio frequency identification (RFID) of dentures in long-term care facilities.

STATEMENT OF PROBLEM: The difficulty of identifying the ownership of lost dentures when found is a common and expensive problem in long term care facilities (LTCFs) and hospitals. PURPOSE: The purpose of this study was to evaluate the reliability of using radiofrequency identification (RFID) in the identification of dentures for LTCF residents after 3 and 6 months. MATERIAL AND METHODS: Thirty-eight residents of 2 LTCFs in Switzerland agreed to participate after providing informed consent. The tag was programmed with the family and first names of the participants and then inserted in the dentures. After placement of the tag, the information was read. A second and third assessment to review the functioning of the tag occurred at 3 and 6 months, and defective tags (if present) were reported and replaced. The data were analyzed with descriptive statistics. RESULTS: At the 3-month assessment of 34 residents (63 tags) 1 tag was unreadable and 62 tags (98.2%) were operational. At 6 months, the tags of 27 of the enrolled residents (50 tags) were available for review. No examined tag was defective at this time period. CONCLUSIONS: Within the limits of this study (number of patients, 6-month time span) RFID appears to be a reliable method of tracking and identifying dentures, with only 1 of 65 devices being unreadable at 3 months and 100% of 50 initially placed tags being readable at the end of the trial.

Wear of two artificial tooth materials in vivo: a 12-month pilot study.

STATEMENT OF PROBLEM: Wear of methacrylate artificial teeth resulting in vertical loss is a problem for both dentists and patients. PURPOSE: The purpose of this study was to quantify wear of artificial teeth in vivo and to relate it to subject and tooth variables. MATERIAL AND METHODS: Twenty-eight subjects treated with complete dentures received 2 artificial tooth materials (polymethyl methacrylate (PMMA)/double-cross linked PMMA fillers; 35%/59% (SR Antaris DCL, SR Postaris DCL); experimental 48%/46%). At baseline and after 12 months, impressions of the dentures were poured with improved stone. After laser scanning, the casts were superimposed and matched. Maximal vertical loss (mm) and volumetric loss (mm(3)) were calculated for each tooth and log-transformed to reduce variability. Volumetric loss was related to the occlusally active surface area. Linear mixed models were used to study the influence of the factors jaw, tooth, and material on adjusted (residual) wear values (alpha=.05). RESULTS: Due to drop outs (n=5) and unmatchable casts (n=3), 69% of all teeth were analyzed. Volumetric loss had a strong linear relationship to surface area (P<.001); this was less pronounced for vertical loss (P=.004). The factor showing the highest influence was the subject. Wear was tooth dependent (increasing from incisors to molars). However, these differences diminished once the wear rates were adjusted for occlusal area, and only a few remained significant (anterior versus posterior maxillary teeth). Another influencing factor was the age of the subject. CONCLUSIONS: Clinical wear of artificial teeth is higher than previously measured or expected. The presented method of analyzing wear of artificial teeth using a laser-scanning device seemed suitable.

Atualização em síndrome da apnéia obstrutiva do sono na infância

A prevalência de SAOS em crianças é de 0,7-3%, com pico de incidência nos pré-escolares. Fatores anatômicos (obstrução nasal severa, más-formações craniofaciais, hipertrofia do tecido linfático da faringe, anomalias laríngeas, etc.) e funcionais (doenças neuromusculares) predispõem à SAOS na infância. A principal causa da SAOS em crianças é a hipertrofia adenotonsilar. As manifestações clínicas mais comuns são: ronco noturno, pausas respiratórias, sono agitado e respiração bucal. A oximetria de pulso noturna, a gravação em áudio ou vídeo dos ruídos respiratórios noturnos e a polissonografia breve diurna são métodos úteis para triagem dos casos suspeitos de SAOS em crianças, e o padrão-ouro para diagnóstico é a polissonografia em laboratório de sono durante uma noite inteira. Ao contrário dos adultos com SAOS, as crianças costumam apresentar: menos despertares associados aos eventos de apnéia, maior número de apnéias/hipopnéias durante o sono REM e dessaturação mais acentuada da oxihemoglobina mesmo nas apnéias de curta duração. O tratamento da SAOS pode ser cirúrgico (adenotonsilectomia, correção de anomalias craniofaciais, traqueostomia) ou clínico (higiene do sono, pressão positiva contínua nas vias aéreas - CPAP).

Relation between speaking space of the /s/ sound and freeway space in dentate and edentate subjects.

The purpose of this study is to assess the relation between the speaking space of the /s/ sound and the freeway space in two subject groups. One group had natural dentition (Group I, n = 61) and the other comprised complete denture wearers (Group II, n = 33). The analysis was done by means of a jaw-tracking device (K6-I Diagnostic System, Myotronics Research Inc., Seattle, WA, USA). Freeway space was determined by asking the subjects to occlude from the postural rest position. Speaking space of /s/ was measured during the pronunciation of the word seis and comprised the mean distance from the /s/ speaking position to maximal intercuspation. A weak correlation was found between the speaking space of /s/ and the freeway space in Group I (r = 0.41, p < 0.01), but in Group II, the correlation was stronger (r = 0.75, p < 0.01). The speaking space of /s/ and freeway space were different in Group I, but statistically similar in Group II (paired t-test, alpha = 0.05). It can be suggested that anatomic changes following prosthetic procedures caused a functional adaptation which resulted in more similar values for the speaking space of /s/ and the freeway space.

Edentulous patients' knowledge of dental hygiene and care of prostheses

Objective: The aim of this study was to analyse denture users' oral care habits with regard to the use of their prostheses. Background: Rehabilitative treatment is only successful when patients are motivated and aware of correct prosthesis use and hygiene. Materials and methods: Questionnaires were distributed to 150 complete denture users at the Federal University of Bahia School of Dentistry, the Esmeralda Natividade Health Center, the Bahian Science Development Foundation and a Salvador nursing home. The questionnaire included information on gender, age, length of prosthesis use, cleaning methods and materials, etc. The data were analysed using EpiInfo version 6 software. The chi-squared test was used for statistical analysis, with a significance level of 5%. Results: Questionnaire results showed that 78% of the subjects, with an average age of 67.3 years, had used the same complete denture for over 5 years. 64% slept with their prostheses and 44% removed them from the mouth only for cleaning. None of the patients interviewed knew anything about brushes designed specifically for complete dentures. 37.3% had a restricted diet and 44% believed that a complete denture would last for more than 10 years. Conclusion: Within the limitations of this study, it was concluded that the edentulous patients surveyed had limited awareness of prosthetic hygiene and long-term oral care despite extended periods of denture use. © 2008 The Authors.

Effect of sodium bicarbonate on Candida albicans adherence to thermally activated acrylic resin

The purpose of this study was to evaluate the effect of 5% sodium bicarbonate on the adherence of Candida albicans to thermally activated acrylic resin. Fifty 4 mm specimens of acrylic resin were obtained using a metallic matrix. The specimens received chemical polishing, were sterilized and then immersed in Sabouraud broth, inoculated with Candida albicans standardized suspension. After 24 hours of incubation at 37°C, the specimens were divided into four groups according to the substance used for disinfection (5% sodium bicarbonate, 0.12% digluconate chlorhexidine, vinegar and Corega Tabs). A control group was included, in which distilled water was used. The adhered microorganisms were dispersed, diluted and plated onto culture media to determine the number of colony-forming units (cfu/mL). The results were analyzed through the Mann-Whitney statistical test at the 5% level of significance. Only 0.12% digluconate chlorhexidine and 5% sodium bicarbonate presented a statistically significant difference (p = 0.0010 and p = 0.0156, respectively) compared to the control group, decreasing the number of cfu/mL. However, when the different disinfecting solutions were compared with each other, only 0.12% digluconate chlorhexidine presented a statistically significant difference in the reduction of cfu/mL. It was concluded that although 0.12% digluconate chlorhexidine was more effective in the reduction of Candida albicans adherence values to thermally activated acrylic resin, 5% sodium bicarbonate also proved to be a viable alternative.

Effects of mandibular fixed implant-supported prostheses on masticatory and swallowing functions in completely edentulous elderly individuals

Purpose: To evaluate the effect of oral rehabilitation with immediately loaded fixed implant-supported mandibular prostheses on chewing and swallowing in elderly individuals. Materials and Methods: Fifteen completely edentulous patients aged more than 60 years (10 women and rive men), wearing removable dentures in both arches, had a mandibular denture replaced by an implant-supported prosthesis. All individuals were evaluated before surgery and again 3, 6, and 18 months later with regard to mastication and swallowing conditions. Examinations entailed an interview, evaluation of tactile sensitivity of the face, and observation of food intake, masticatory type, formations of bolus, and pain during mastication. The swallowing evaluation comprised observation of clinical signs related to the oral and pharyngeal stages of swallowing, as well as the presence of oral residue. The findings of different evaluations before and 3, 6, and 18 months after the surgical-prosthetic procedure were statistically compared by analysis of variance for repeated measurements at a significance level of 5%. Results: The questionnaire revealed a reduction in complaints of masticatory and swallowing disturbances, a decreased need for liquid ingestion, and reduced choking and coughing. Clinical evaluations showed improved oral function and bolus propulsion for both solid and paste-consistency foods; pain during mastication was also resolved. Conclusion: Treatment with mandibular implant-supported dentures had positive effects on the clinical aspects of mastication and swallowing in elderly individuals.

Oral health of the elderly with Alzheimer's disease

Objective: The objective of this study was to describe the oral health of elderly people diagnosed with Alzheimer's disease (AD). Study Design: Thirty elderly subjects with AD (mild, moderate, and severe) and 30 without AD (controls) were included in the study. Volunteer-reported oral health data were collected using the General Oral Health Assessment Index (GOHAI). Demographic and oral characteristics were assessed, including the number of natural teeth; number of decayed, missing, and filled teeth (DMTF); oral health index (OHI); removable prosthesis conditions; and oral pathologies. Results: GOHAI values were similar for both groups. Compared with the controls, the subjects with AD had a higher age, DMTF, OHI, and number of oral pathologies and a lower educational level and number of natural teeth. Conclusions: Elderly subjects with AD had poorer oral health than those without the disease. Despite the positive self-perception of their oral health, the oral health of subjects with AD tended to decline as their disease progressed. © 2012 Elsevier Inc.

Efetividade da irradiação por microondas na desinfecção de próteses totais contaminadas por diferentes espécies de Candida isoladas de pacientes HIV positivo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efetividade de duas soluções desinfetantes e da irradiação por micro-ondas na desinfecção de próteses totais contaminadas com staphylococcus aureus resistente à meticilina (MRSA)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo cinesiográfico do espaço de pronúncia do som /s/ em indivíduos dentados e desdentados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Disfunção craniomandibular em pacientes desdentados totais com alteração da dimensão vertical. -

Pós-graduação em Reabilitação Oral - FOAR

Movimentação dos dentes artificiais em próteses totais com diferentes profundidades de palato

Pós-graduação em Odontologia - FOA