Effect of Silver Nanoparticles on Physicochemical and Antibacterial Properties of Calcium Silicate Cements

Abstract Mineral trioxide aggregate (MTA) and Portland cement (PC) are calcium silicate cements. They have similar physicochemical, mechanical and biological properties. The addition of zirconium oxide (ZrO2) to PC provides radiopacity. Silver nanoparticles (AgNPs) may improve some properties of cements. The aim of this study was to evaluate the effect of AgNPs on physicochemical/mechanical properties and antibacterial activity of white MTA (WMTA) and PC associated with ZrO2. The following materials were evaluated: WMTA; PC 70% + ZrO2 30%; WMTA+ AgNPs; and PC 70% + ZrO2 30% + AgNPs. The study evaluated radiopacity, setting time, pH, compressive strength and solubility. For radiopacity analysis, radiographs were made alongside an aluminum (Al) step wedge. To evaluate the antibacterial activity, direct contact test was performed on planktonic cells and Enterococcus faecalis biofilm induced on bovine root dentin for 14 days. The experimental periods were 5 and 15 h. Data were obtained as CFU mL-1. The obtained data were submitted to ANOVA and Tukey tests (p<0.05). The addition of AgNPs to WMTA increased the pH, lowered the solubility and the initial and final setting times. The addition of AgNPs to PC/ZrO2 maintained the pH, lowered the solubility, and increased the setting time and compressive strength. The radiopacity of all materials was higher than 4 mmAl. The addition of AgNPs promoted an increase in antibacterial activity for calcium silicate cements and favored the physicochemical and mechanical properties of the materials.

Resumo Mineral trióxido agregado (MTA) e cimento Portland (CP) são cimentos à base de silicato de cálcio. Eles apresentam propriedades físico-químicas, mecânica e biológicas semelhantes. A adição de óxido de zircônio (ZrO2) ao CP confere radiopacidade. Nanopartículas de prata (NPsAg) podem melhorar propriedades dos cimentos. O objetivo deste estudo foi avaliar o efeito da NPsAg nas propriedades físico-químicas, mecânicas e na atividade antibacteriana do MTA branco (WMTA) e CP associado ao ZrO2. Os seguintes materiais foram avaliados: WMTA; CP 70% + ZrO2 30%; ; WMTA + NPsAg; CP 70% + ZrO2 30% + NPsAg. Foram avaliados a radiopacidade, tempo de presa, pH, resistência à compressão e solubilidade. Para análise da radiopacidade foram tiradas radiografias ao lado de uma escala de alumínio (Al). Para avaliar a atividade antibacteriana, foi realizado o teste de contato direto sobre células planctônicas e biofilme de Enterococcus faecalis formado em dentina radicular bovina durante 14 dias. Os períodos experimentais foram 5 e 15 h. Os dados foram obtidos como UFC mL-1 e submetidos aos testes de ANOVA e Tukey (p<0,05). A adição de NPsAg ao WMTA elevou o pH, diminuiu a solubilidade e os tempos de presa inicial e final. A adição de NPsAg ao CP/ZrO2 manteve o pH, diminuiu a solubilidade, aumentou o tempo de presa e a resistência à compressão. A radiopacidade de todos os materiais foi maior do que 4 mmAl. A adição de NPsAg promoveu um aumento da atividade antibacteriana dos cimentos à base de silicato de cálcio e favoreceu as propriedades físico-químicas e mecânicas dos materiais.

Effect of addition of nano-hydroxyapatite on physico-chemical and antibiofilm properties of calcium silicate cements

ABSTRACT Objective Mineral Trioxide Aggregate (MTA) is a calcium silicate cement composed of Portland cement (PC) and bismuth oxide. Hydroxyapatite has been incorporated to enhance mechanical and biological properties of dental materials. This study evaluated physicochemical and mechanical properties and antibiofilm activity of MTA and PC associated with zirconium oxide (ZrO2) and hydroxyapatite nanoparticles (HAn). Material and Methods White MTA (Angelus, Brazil); PC (70%)+ZrO2 (30%); PC (60%)+ZrO2 (30%)+HAn (10%); PC (50%)+ZrO2 (30%)+HAn (20%) were evaluated. The pH was assessed by a digital pH-meter and solubility by mass loss. Setting time was evaluated by using Gilmore needles. Compressive strength was analyzed by mechanical test. Samples were radiographed alongside an aluminum step wedge to evaluate radiopacity. For the antibiofilm evaluation, materials were placed in direct contact with E. faecalis biofilm induced on dentine blocks. The number of colony-forming units (CFU mL-1) in the remaining biolfilm was evaluated. The results were submitted to ANOVA and the Tukey test, with 5% significance. Results There was no difference in pH levels of PC+ZrO2, PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p>0.05) and these cements presented higher pH levels than MTA (p<0.05). The highest solubility was observed in PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p<0.05). MTA had the shortest initial setting time (p<0.05). All the materials showed radiopacity higher than 3 mmAl. PC+ZrO2 and MTA had the highest compressive strength (p<0.05). Materials did not completely neutralize the bacterial biofilm, but the association with HAn provided greater bacterial reduction than MTA and PC+ZrO2 (p<0.05) after the post-manipulation period of 2 days. Conclusions The addition of HAn to PC associated with ZrO2 harmed the compressive strength and solubility. On the other hand, HAn did not change the pH and the initial setting time, but improved the radiopacity (HAn 10%), the final setting time and the E. faecalis antibiofilm activity of the cement.

Avaliação de propriedades físico-químicas, mecânicas e antimicrobianos do MTA e cimento Portland associado a solução de nanopartículas de prata / Evaluation of physico-chemical, mechanical and antimicrobial properties of MTA and Portland cement associated with silver nanoparticles solution

A substituição do óxido de bismuto por óxido de zircônio (ZrO2) e a adição de nanopartículas de prata (NPsAg) pode favorecer as propriedades físico-químicas mecânicas e antimicrobianas. Capítulo 1: Foram avaliados pH, solubilidade, tempo de presa, radiopacidade e resistência à compressão. Grupos: G1 - MTA Angelus; G2 - CP/ZrO2; G3 - MTA/NPsAg; G4 -CP/ZrO2/NPsAg. O pH foi analisado em pHmetro digital, a solubilidade pela perda de massa e o tempo de presa pelo teste de Gilmore. A resistência à compressão foi avaliada em ensaio mecânico. Para análise da radiopacidade, as amostras foram radiografadas com uma escala de alumínio. Os resultados foram submetidos aos testes ANOVA e Tukey (p<0,05). O G3 apresentou aumento de pH e diminuição da solubilidade e tempo do presa inicial e final. O G4 apresentou diminuição da solubilidade e aumento da resistência à compressão. A radiopacidade dos materiais foi superior a 4 mmAl. As associações G3 e G4 apresentam propriedades físico-químicas e mecânicas adequadas. Capítulo 2: Bactérias na forma planctônica foram colocadas sobre o cimento fresco e a análise foi realizada em espectrofotômetro. Na avaliação antibiofilme, os materiais foram colocados em contato com biofilme de E. faecalis formado sobre blocos de dentina e analisados pela contagem de unidades formadoras de colônia. Os resultados foram submetidos aos testes ANOVA e Tukey (p<0,05). Na forma planctônica, melhores resultados foram encontrados no G2 e G4. Maior redução de biofilme foi apresentada pelos G3 e G4. A incorporação de NPsAg ao CP e MTA, melhora a atividade antibacteriana e antibiofilme dos materiais à base de silicato de cálcio.

The bismuth oxide replacement by zirconium oxide (ZrO2) and the addition of silver nanoparticles may improve the physicochemical, mechanic and antimicrobial properties. Chapter I: It was evaluated pH, solubility, setting time, radiopacity and compressive strength. Groups: G1-MTA Angelus; G2-PC/ZrO2; G3-MTA/NPsAg, G4-PC/ZrO2/NPsAg. The pH was measured with a digital pH meter, the solubility by the weight loss and the setting time was evaluated by Gilmore needle. Compressive strength was tested in universal testing machine. For radiopacity analysis material samples were radiographed alongside an aluminium step-wedge. The results were submitted to ANOVA and Tukey tests (p<0.05). The G3 showed a pH increase and a decrease of solubility and initial and final setting time. The G4 showed a decrease in solubility and an increase of compressive strength. All materials presented radiopacity greater than 4 mmAl. The G3 and G4 associations showed good physicochemical and mechanical properties. Chapter 2: For the first test bacterias in planktonic form were placed over fresh cement, and the analysis was performed in spectrophotometer. Also for the antibiofilm test, the samples were placed in direct contact with E. faecalis biofilm previously induced on bovine dentine and analysed by the counting of colony-forming units. The results were submitted to ANOVA and Tukey tests (p<0.05). On the planktonic form, the best results were showed by G2 and G4. The greater reduction of biofilm were showed by G3 and G4. The incorporation of NPsAg to PC and MTA improves the antibacterial and antbiofilm activity of calcium silicate cements

Otitis media crónica complicada en un adolescente con malformación auditiva / Complicated chronic otitis media in an adolescent with auditory malformation

Se describe el caso clínico de un adolescente de 17 años de edad, multimalformado, con agenesia del pabellón auricular, así como en el oído externo y medio, quien presentó otitis media crónica complicada. Fue ingresado en el Servicio de Otorrinolaringología del Hospital Provincial Docente Clinicoquirúrgico "Saturnino Lora Torres" y se le indicó antibioticoterapia triple. Posteriormente se realizó una incisión en la región mastoidea del lado izquierdo, se drenó abundante pus, se colocó drenaje y se mantuvo la medicación con antibióticos. El paciente evolucionó favorablemente y egresó a los 10 días. Se concluyó el caso como una otitis media crónica con mastoiditis aguda.

The case report of a 17 year-old adolescent, with multiple malformations, agenesia of pinna as well as of the external and middle ear who presented with complicated chronic otitis media is described. He was admitted to the Otorhinolaryngology Service of "Saturnino Lora Torres" Clinical Surgical Teaching Provincial Hospital and he was indicated triple antibiotic therapy. Later an incision in the mastoid region of his left side was carried out, abundant pus was drained, drainage was placed and the medication with antibiotics was maintained. The patient had a favorable clinical course and he was discharged 10 days later. It was concluded that the case was a chronic otitis media with acute mastoiditis.