21 research outputs found
Compressive fatigue in titanium dental implants submitted to fluoride ions action
The aim of this study was to assess the influence of a fluoridated medium on the mechanical properties of an internal hexagon implant-abutment set, by means of compression, mechanical cycling and metallographic characterization by scanning electronic microscopy. Five years of regular use of oral hygiene with a sodium fluoride solution content of 1500 ppm were simulated, immersing the samples in this medium for 184 hours, with the solutions being changed every 12 hours. Data were analyzed at a 95% confidence level with Fisher's exact test. After the action of fluoride ions, a negative influence occurred in the mechanical cycling test performed in a servohydraulic machine (Material Test System-810) set to a frequency of 15 Hz with 100,000 cycles and programmed to 60% of the maximum resistance of static compression test. The sets tended to fracture by compression on the screw, characterized by mixed ruptures with predominance of fragile fracture, as observed by microscopy. An evidence of corrosion by pitting on sample surfaces was found after the fluoride ions action. It may be concluded that prolonged contact with fluoride ions is harmful to the mechanical properties of commercially pure titanium structures
Análise do Interesse e Consumo de Produtos Ecologicamente Corretos pela População do MunicĂpio de Medianeira-PR
Em decorrĂŞncia dos avanços tecnolĂłgicos das Ăşltimas dĂ©cadas, as explorações dos recursos naturais de forma desenfreada resultaram em impactos de grande escala no meio ambiente, e, na vida do ser humano. Com o surgimento e aprimoramento das normas ambientais, o desenvolvimento econĂ´mico se torna cada vez mais sustentável, e busca aproveitar das suas práticas e produtos sustentáveis como diferencial de mercado. Nesse sentido, o presente trabalho buscou avaliar as práticas de consumo de produtos ecologicamente corretos da população do municĂpio de Medianeira-PR, por meio de uma pesquisa exploratĂłria em forma de questionários com perguntas objetivas. ApĂłs a coleta e compilação dos dados, observou-se uma participação relativamente positiva da população, destacando maior motivação dos entrevistados de maior renda para pagar mais por produto ecologicamente correto (29%) em relação aos que possuem renda de atĂ© trĂŞs salários mĂnimos (21%). Haver um maior engajamento dos entrevistados de maior escolaridade em relação a percepção ambiental (97%) em relação aos de atĂ© ensino mĂ©dio completo (85%). AlĂ©m de um maior conhecimento sobre rotulagem ambiental de produtos para entrevistados de maior escolaridade (33%) face aos entrevistados de atĂ© ensino mĂ©dio completo (26%)
Surface Morphology Alterations In Bovine Dentin Exposed To Different Bleaching Agents
Aim: This study evaluated the morphological changes caused by internal bleaching agents on dentin surface. Methods: Twenty crowns of bovine incisors were cut into slabs that were randomly distributed in six experimental groups (n = 5), according to the bleaching agent used: G1 – sodium perborate + water, G2 – sodium perborate + 2% chlorhexidine gel, G3 – sodium perborate + 30% hydrogen peroxide, G4 – 30% hydrogen peroxide, G5 – 37% carbamide peroxide and G6 – gel base without carbamide. Two Control Groups were used: C1 with distilled water and C2 with 2% chlorhexidine gel. The specimens were immersed in the respective test bleaching agent and incubated at 37 °C for seven days. Following, they were prepared for scanning electron microscopy and five images from each tooth segment were recorded and analyzed for surface morphological alterations, by three previously calibrated examiners. Inter-examiner agreement was verified using the Kappa test. The rank averages obtained for the groups were subjected to Kruskal-Wallis analysis of variance at 5% significance level. Results: The analysis of the scores obtained indicated that all tested materials caused some morphological alteration on dentin, except for sodium perborate + water (G1) and Control Groups 1 and 2. Hydrogen peroxide and carbamide peroxide caused significantly more severe alterations (p < 0.05) to dentin structure, than the other bleaching agents evaluated. Conclusions: Sodium perborate-based pastes seemed to be the most harmless agent to dentin structures in non-vital tooth bleaching, while hydrogen peroxide solutions and carbamide peroxide agents caused the greatest alterations.8125-2
Compressive fatigue in titanium dental implants submitted to fluoride ions action
The aim of this study was to assess the influence of a fluoridated medium on the mechanical properties of an internal hexagon implant-abutment set, by means of compression, mechanical cycling and metallographic characterization by scanning electronic microscopy. Five years of regular use of oral hygiene with a sodium fluoride solution content of 1500 ppm were simulated, immersing the samples in this medium for 184 hours, with the solutions being changed every 12 hours. Data were analyzed at a 95% confidence level with Fisher's exact test. After the action of fluoride ions, a negative influence occurred in the mechanical cycling test performed in a servohydraulic machine (Material Test System-810) set to a frequency of 15 Hz with 100,000 cycles and programmed to 60% of the maximum resistance of static compression test. The sets tended to fracture by compression on the screw, characterized by mixed ruptures with predominance of fragile fracture, as observed by microscopy. An evidence of corrosion by pitting on sample surfaces was found after the fluoride ions action. It may be concluded that prolonged contact with fluoride ions is harmful to the mechanical properties of commercially pure titanium structures
Clinical assessment of masticatory efficiency in the rehabilitation of edentulous patients
Introduction: Rehabilitation of edentulous patients has been a constant
concern in dentistry. Several studies have reported a reduction in the
masticatory function in these patients. Osseointegrated implants have
been used in order to obtain better masticatory efficiency, but more
studies are needed to confirm these results. Aim: To evaluate the
masticatory function of patients with conventional dentures and
implant-supported dentures. Methods: A double-blinded controlled
clinical study was conducted. The sample was composed of 60 patients
divided into three groups: G1 with 20 patients with conventional upper
(maxillary) and lower (mandibular) complete dentures, G2 with 20
patients with mandibular overdentures and upper (maxillary) complete
dentures, and G3 with 20 patients with lower fixed implant-supported
complete dentures (protocol). Objective data were collected through the
masticatory efficiency test performed by the colorimetric method with
the beads, in which capsules of a synthetic material enclosing
fuchsine-containing granules were used. Results: A statistically
significant difference was found for masticatory efficiency between
groups G1 and G2 (pd”0.05) and between G1 and G3 (pd”0.05),
and there was no statistically significant difference between G2 and G3
(pe”0.05). Conclusions: The results suggest that placement of
osseointegrated implants in complete denture wearers improves their
masticatory efficiency
Ultrasonic irrigation in the removal of smear layer and Enterococcus faecalis from root canals
Aim: This study evaluated both smear layer removal and reduction of
Enterococcus faecalis after instrumentation with ultrasonic
irrigation. Methods: Root canals were experimentally inoculated with E.
faecalis for 20 days and microbiological samples were collected before
and after chemomechanical preparation by using sterilized absorbent
paper points. The irrigation solutions used were NaOCl 2.5% and EDTA
17%. In Group 1 (G1), conventional irrigation was used, whereas in
Group 2 (G2) ultrasonic irrigation was performed. In group 3 (control),
root canals were irrigated with distilled water. The samples were
inoculated in BHI broth and turbidity was observed after 48 h to
evaluate the reduction in the number of bacteria. Residual smear layer
was examined by scanning electron microscopy (SEM). Results: The
results showed no significant differences between ultrasonic and
conventional irrigation. Conclusions: It was concluded that the level
of disinfection and cleanliness of root canals achieved with ultrasonic
irrigation is comparable to that obtained by conventional methods
Clinical assessment of masticatory efficiency in the rehabilitation of edentulous patients
itation of edentulous patients has been a constant concern in dentistry. Several studies have reported a reduction in the masticatory function in these patients. Osseointegrated implants have been used in order to obtain better masticatory efficiency, but more studies are needed to confirm these results. Aim: To evaluate the masticatory function of patients with conventional dentures and implant-supported dentures. Methods: A double-blinded controlled clinical study was conducted. The sample was composed of 60 patients divided into three groups: G1 with 20 patients with conventional upper (maxillary) and lower (mandibular) complete dentures, G2 with 20 patients with mandibular overdentures and upper (maxillary) complete dentures, and G3 with 20 patients with lower fixed implant-supported complete dentures (protocol). Objective data were collected through the masticatory efficiency test performed by the colorimetric method with the beads, in which capsules of a synthetic material enclosing fuchsine-containing granules were used. Results: A statistically significant difference was found for masticatory efficiency between groups G1 and G2 (pd0.05) and between G1 and G3 (pd0.05), and there was no statistically significant difference between G2 and G3 (pe0.05). Conclusions: The results suggest that placement of osseointegrated implants in complete denture wearers improves their masticatory efficiency