Photoelastic Analysis of Implant-Retained and Conventional Obturator Prostheses With Different Attachment Systems and Soft Relining

Complete and partial loss of maxillary bone may jeopardize oral physiology and generate complications as oral-sinus-nasal communication. Palatal obturator prostheses are a treatment alternative for rehabilitation of these patients. The aim of this study was to assess stress distribution, through photoelasticity, on palatal obturator prostheses associated with different attachment systems (o'ring, bar clip, and o'ring/bar clip) of implants and submitted to relining. Two photoelastic models were fabricated according to an experimental maxillary model with oral-sinus-nasal communication. One model did not present implants, whereas the other included 2 implants with 13.0 mm in length in the left ridge. Four colorless maxillary obturator prostheses were fabricated and relined with soft silicone. One of these prostheses presented no attachment system, whereas the remaining prostheses included attachment systems adapted to the implants. The assembly (model/attachment system/prosthesis) was positioned in a circular polariscope during loading with 100 N at 10 mm/s. The results were based on observation during the experiment and photographic records of stress on the photoelastic model. The bar clip system exhibited the highest stress concentration followed by o'ring/bar clip and o'ring systems. The attachment systems presented different stress distribution with greater concentration surrounding the implants and homogenous stress distribution on the photoelastic model without implants. The highest concentration of fringes occurred, in ascending order, with o'ring, o'ring/bar clip, and bar clip systems.

Effect of thermocycling on hardness, absorption, solubility and colour change of soft liners

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

TMJ Vibrations in Asymptomatic Patients Using Old and New Complete Dentures

Purpose: The aim of this study was to assess the presence of temporomandibular joint (TMJ) noises in subjects with severe bone resorption, who have worn the same complete dentures for over 10 years, and 5 months after treatment with increments of acrylic resin on the occlusal surface after having new dentures in place.Methods: After applying the research diagnostic criteria (RDC)/temporomandibular disorder (TMD) questionnaire, 20 asymptomatic subjects were assessed before and 5 months after the new dentures were put in place. Joint vibrations were assessed by the Sono Pak program by selecting the vibrations that occurred during the opening and closing cycle.Results: The means of the results revealed a nonnormal distribution and were submitted to Kruskal-Wallis statistical analysis (p < 0.05). The vibration means were of low intensity (<= 9.96 Hz). After rehabilitation, there was a reduction in the vibrations (<= 5.2 Hz) statistically significant only at the end of mouth opening with the old dentures when compared with the other cycles.Conclusion: The intensity and number of occurrences of joint vibrations were reduced after 5 months of wearing new dentures.

Mobility, Aesthetic, Implants, and Satisfaction of the Ocular Prostheses Wearers

During the process of facial rehabilitation, the mobility of ocular prostheses must be considered. Whereas some factors depend exclusively on the dentist, such as molding techniques and selection of material for denture construction, regarding ocular rehabilitation, factors, such as type of surgery, whether to adopt implants, and the use of lubricants, deserve special attention owing to their integration and their association with other factors pertaining exclusively to the patient. To establish harmony, and with the intention of aiding the dentist, after a discerning evaluation, the authors of this study report the factors that provide greater or less mobility to ocular prostheses and conceal the prosthesis in a more natural way, thereby contributing toward achieving a favorable aesthetic result in rehabilitations.

Photoelastic analysis to compare implant-retained and conventional obturator dentures

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

Antimicrobial Properties and Cytotoxicity of an Antimicrobial Monomer for Application in Prosthodontics

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

Microscopical analysis of Candida albicans biofilms on heat-polymerised acrylic resin after chlorhexidine gluconate and sodium hypochlorite treatments

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of metal conditioners on the adhesive bonding of resin cements to cast titanium

Objective: To assess the effect of metal conditioners on the bond strength between resin cements and cast titanium. Method and Materials: Commercially pure titanium (99.56%) was cast using an arc casting machine. Surfaces were finished with 400-grit silicon carbide paper followed by air abrasion with 50-mu m aluminum oxide. A piece of double-coated tape with a 4-mm circular hole was then positioned on the metal surface to control the area of the bond. The prepared surfaces were then divided into 4 groups (n=10): G1, unprimed Panavia F; G2, Alloy Primer-Panavia F; G3, unprimed Bistite DC; G4, Metaltite-Bistite DC. Forty minutes after insertion of the resin cements, the specimens were detached from the mold and stored in water at 37 C for 24 hours. Shear bond strength was performed in a testing machine (MTS 810) at a crosshead speed of 0.5 mm/min. Data were analyzed using ANOVA and Tukey's test with a .05 significance level. The fractured surfaces were observed through an optical microscope at 10x magnification. Results: the G1 group demonstrated significantly higher shear bond strength (17.95 MPa) than the other groups. G3 (13.79 MPa) and G4 (12.98 MPa) showed similar mean values to each other and were statistically superior to G2 (9.31 MPa). Debonded surfaces generally presented adhesive failure between metal surfaces and resin cements. Conclusion: While the Metaltite conditioner did not influence the bond strength of the Bistite DC cement, the Alloy Primer conditioner significantly decreased the mean bond strength of the Panavia F cement.

Hardness of heat-polymerized acrylic resins after disinfection and long-term water immersion

Statement of the problem. In selecting a disinfectant for dental prostheses, compatibility between the disinfectant and the type of denture base material must be considered to avoid adverse effects on the hardness of the acrylic resin.Purpose. This study investigated the hardness of 2 denture base resins after disinfection and long-term water immersion.Material and methods. Thirty-two disk-shaped specimens (13 mm in diameter and 8 mm thick) were fabricated from each resin (Lucitone 550 and QC-20), polished, stored in water at 37degreesC for 48 hours, and submitted to hardness tests (Vickers hardness number [VHN]) before disinfection. Disinfection methods included scrubbing with 4% chlorhexidine gluconate for 1 minute, immersion for 10 minutes in I of the tested disinfectant Solutions (n=8) (3.78% sodium perborate, 4% chlorhexidine gluconate, or 1% sodium hypochorite), and immersion in water for 3 minutes. The disinfection procedures were repeated 4 times, and 12 hardness measurements were made on each specimen. Control specimens (not disinfected) were stored in water for 56 minutes. Hardness tests (VHN) were also performed after 15, 30, 60, 90, and 120 days of storage in water. Statistical analyses of data were conducted with a repeated measures 3-way analysis of variance (ANOVA) and Tukey post-hoc test (alpha=.05).Results. Mean values +/- SD for Lucitone 550 (16.52 +/- 0.94 VHN) and QC-20 (9.61 +/- 0.62 VHN) demonstrated a significant (P<.05) decrease in hardness after disinfection, regardless of material and disinfectant solutions used (Lucitone 550: 15.25 +/- 0.74; QC-20: 8.09 +/- 0.39). However, this effect was reversed after 15 days of storage in water. Both materials exhibited a continuous increase (P<.05) in hardness values for up to 60 days of water storage, after which no significant change was observed.Conclusion. Within the limitations of this in vitro study, QC-20 and Lucitone 550 specimens exhibited significantly lower hardness values after disinfection regardless of the disinfectant solution used.

Resistência de união entre dentes artificiais e resinas acrílicas para base protética

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of partially dentate patients' knowledge about caries and periodontal disease

Objective: This investigation evaluated the knowledge of dental caries and periodontal disease among removable partial denture (RPD) wearers.Method: A total of 127 partially dentate patients participated in this observational study. A structured questionnaire, which included eight questions referring to knowledge about aetiology and prevention of dental caries and periodontal disease, was developed in the local language (Portuguese) and used to collect the data of all the partial denture wearers. A descriptive analysis of data was performed by means of drafting tables.Results: The results demonstrated that 68.5% of patients interviewed had previously received information about oral health care. With regard to bacterial plaque, it was observed that only 34.6% reported having knowledge of this. Whereas, in relation to caries, 76.4% of the interviewees replied that they knew the meaning of this. Nevertheless, 28.3% referred to caries as a whole in the teeth, 16.5% as bad teeth and 9.4% bacteria/creatures on the teeth. Only 17.3% of the partially edentulous patients evaluated were shown to know what disease of the gingiva was.Conclusion: By means of the methodology applied, it could be concluded that the patients who wore RPDs presented deficient knowledge with regard to the prevention, aetiology and development of dental caries and periodontal disease.

Validation of the Brazilian versions of two inventories for measuring oral health-related quality of life of edentulous subjects

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

Photodynamic inactivation of microorganisms present on complete dentures. A clinical investigation

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

Adherence in vitro of Candida albicans to plasma treated acrylic resin. Effect of plasma parameters, surface roughness and salivary pellicle

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

Effectiveness of chlorhexidine on the disinfection of complete dentures colonised with fluconazole-resistant Candida albicans: in vitro study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)