Incorporation of a ß-AgVO3 Semiconductor in Resin Cement: Evaluation of Mechanical Properties and Antibacterial Efficacy.

PURPOSE: This in vitro study aimed to investigate the effect of incorporating the semiconductor nanostructured silver vanadate decorated with silver nanoparticles (ß-AgVO3) in a dual-cure resin cement on the degree of conversion (DC), microhardness, roughness, color, adhesion properties before and after artificial aging, and antimicrobial efficacy. MATERIAL AND METHODS: Three test groups were established: control (without ß-AgVO3), with the incorporation of 2.5% and 5% (by weight) of ß-AgVO3 in dual-cure resin cement (Allcem, FGM). The degree of conversion was measured using Fourier transform infrared spectroscopy (FTIR). To evaluate roughness (n = 10), microhardness (n = 10), color (n = 10), and to perform agar disk diffusion (n = 8), disks of 6-mm diameter and 2-mm height were manufactured using the same concentrations. For the color and shear bond strength test (n = 6), orthodontic brackets (Morelli) were used, which were cemented to natural human enamel and evaluated before and after artificial aging via thermocycling at 5°C and 55°C for 1000 cycles. For color measurements, a portable spectrocolorimeter and the CIE-Lab method were used. Data were analyzed using Student's t-test, ANOVA, and Tukey's multiple comparisons with significance set at α = 0.05. RESULTS: Semiconductor incorporation did not influence the cements's DC. The incorporation of 2.5% and 5% of ß-AgVO3 resulted in a significant increase in Knoop microhardness and surface roughness. Significant changes were observed in the color of the specimens when the semiconductor was incorporated. Adhesion after aging remained within the clinically recommended values in all groups, and antimicrobial activity was observed against Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis at both concentrations tested. CONCLUSION: It is suggested to incorporate the semiconductor ß-AgVO3 in the dual-cure resin cement at both concentrations. Moreover, the physical-mechanical properties remained satisfactory for the proposed application.

Effect of Auricular Acupuncture on the Reduction of Symptoms Related to Sleep Disorders, Anxiety and Temporomandibular Disorder (TMD).

BACKGROUND: Auricular acupuncture (AA) is a complementary/integrative therapy, and can be used as adjuvant treatment in sleep disorders, anxiety and the painful symptomatology of temporomandibular disorders (TMDs). OBJECTIVE: The aim of this investigation was to evaluate the effectiveness of AA in reducing the symptoms of sleep disorders, anxiety and TMDs by applying the Fletcher and Luckett, Beck-BAI and RDC/TMD questionnaires: Axis II, respectively. DESIGN: This was a nonrandomized clinical trial in which AA was administered to patients between the ages of 20 and 45 years from the School of Dentistry at Ribeirão Preto, São Paolo, Brazil, who had at least one of the following: sleep disorder, anxiety or TMD. INTERVENTION: Mustard seeds were applied to predetermined auricular acupoints including: Shen Men, neurovegetative system (sympathetic), kidney, anxiety, stomach, maxilla and mandible, liver and stress, once a week for 8 weeks. OUTCOME MEASURES: To analyze the reduction in sleep disorder symptoms, we used the Fletcher and Luckett questionnaire; for anxiety symptoms, the Beck-BAI questionnaire, and for the degree of chronic TMD pain, the RDC/TMD (Axis II) questionnaire. RESULTS: Data on sleep, anxiety and TMD disorders were analyzed via Fisher's exact, Wilcoxon and Chi-Square non-parametric tests (α = 0.05), respectively. Reduction in sleep disorder symptoms after the proposed intervention was verified, showed a statistically significant difference (P = .014). There was a reduction in mean anxiety score and a decrease in painful TMD symptoms, but no significant difference (P = .50; P = .947, respectively) before and after AA. CONCLUSION: In our study, AA was effective in reducing sleep disorder symptoms and our data suggests some relief of symptoms of anxiety and TMD pain.

Influence of chemical composition on cell viability on titanium surfaces: A systematic review.

STATEMENT OF PROBLEM: A consensus on which dental implant alloy and surface treatment provide the best cell viability is unclear. PURPOSE: The purpose of this systematic review was to provide information on the influence of surface and intrinsic titanium alloy chemical components on cell viability. MATERIAL AND METHODS: The PubMed, LILACS, COCHRANE library, and Science Direct databases were electronically searched for the terms dental implants AND titanium AND cytotoxicity. Inclusion criteria were research articles that studied titanium or its alloys for chemical composition and cell viability and were published in English between 1999 and 2019. Articles that did not study titanium and its alloys, articles with nondental or biomedical implants, and articles that were not found in their entirety were excluded. RESULTS: A total of 1226 articles selected by title or abstract according to the inclusion and exclusion criteria resulted in 51 articles that were reduced to 27 after reading in full. The treatments analyzed were arc fusion, electron beam physical deposition, plasma electrolytic oxidation, coating addition, micro arc oxidation, anodization, thermochemical process, BMP-2 immobilization, pressure-assisted sintering, and alkali heat treatment. CONCLUSIONS: The evaluated literature did not allow a determination of the best surface treatment for cell viability because of the heterogeneity of the studies regarding the type of alloy, cell used in the MTT assay, study, and implant purpose (biomedical or dental). The cytotoxic effect of chemical components was dependent on dose, time, size, temperature, and cell type. The niobium, tantalum, zirconium, and molybdenum elements have been most often added in the development of less toxic Ti alloys with lower modulus of elasticity and increased strength.

Relationship between the surface chemical composition of implants and contact with the substrate.

The purpose of the study was to use scanning electron microscopy and energy dispersive x-ray spectrometry to assess possible morphologic and chemical changes after performing double-insertion and pullout tests of implants of different shapes and surface treatments. Four different types of implants were used-cylindrical machined-surface implants, cylindrical double-surface-treated porous implants, cylindrical surface-treated porous implants, and tapered surface-treated porous implants-representing a total of 32 screws. The implants were inserted into synthetic bone femurs, totaling 8 samples, before performing each insertion with standardized torque. After each pullout the implants were analyzed by scanning electron microscopy and energy dispersive x-ray spectrometry using a universal testing machine and magnified 35 times. No structural changes were detected on morphological surface characterization, only substrate accumulation. As for composition, there were concentration differences in the titanium, oxygen, and carbon elements. Implants with surface acid treatment undergo greater superficial changes in chemical composition than machined implants, that is, the greater the contact area of the implant with the substrate, the greater the oxide layer change. In addition, prior manipulation can alter the chemical composition of implants, typically to a greater degree in surface-treated implants.

Análise da superfície de implantes odontológicos submetidos a ensaio de torção / Surface analysis of dental implants tested in torsion

Objetivo: Avaliar o comportamento mecânico de im-plantes odontológicos submetidos à torção manual, a fim de analisar o ponto de ruptura e determinar a região mais frágil e susceptível à deformação, por meio de mi-croscopia eletrônica de varredura, antes e após a reali-zação do ensaio de torção. Materiais e método: Foram selecionados quatro modelos de implantes da marca Co-nexão® (n=5): Master Screw, Porous, Conect AR e Conect Cônico. Foi utilizado um torquímetro digital para a apli-cação de torque e com um microscópio eletrônico de varredura avaliou-se a superfície dos implantes antes e após o ensaio de torção. Resultados: Os resultados foram obtidos pela análise estatística ANOVA (P < 0,05), segui-do do teste de Tukey (P < 0,05). Após a torção verificou--se que as quatro amostras de implantes apresentaram diferentes médias para a variável força máxima, porém, sem diferença estatística significante para os implantes Master Screw, Porous e Conect AR (p > 0,05), sendo ape-nas o implante Conect Cônico estatisticamente diferente (p < 0,05). Quanto às imagens obtidas a partir da análise ao MEV observou-se fratura do montador dos implantes Master Screw e Porous, ruptura dos implantes Conect AR, e espanamento das roscas internas dos Cônicos. Conclusão: Os modelos de implantes testados apresen-taram diferentes comportamentos mecânicos quando submetidos à aplicação de forças, com os Cônicos apre-sentando menor resistência ao ensaio de torção.