ABSTRACT In the restoration of lost or misaligned dental pieces, dissimilar dental alloys are frequently used in the oral cavity, which form galvanic couples that corrode due to the effect of saliva and dentin fluids. In this work, the microstructure of ten non-precious dental alloys was analyzed by optical microscopy, the open-circuit corrosion potential of each alloy was measured against a saturated calomel electrode, they were subjected to accelerated corrosion processes in aerated artificial saliva and plotted the potentiodynamic polarization curves of these alloys. Then, the corrosion potential and current density of the galvanic couples formed by stainless steels 304 and 316L with non-precious dental alloys of Ni-Cr, Co-Cr, and Cu base alloys (Cu-Ni, Cu-Zn and Cu-Al), using the Evans method whose results were not compatible with the principle of galvanic couples, so the Mansfeld equations were used with which results consistent with the aforementioned principle were obtained.

ABSTRACT The copper IUD is an intrauterine device that acts mechanically and chemically to prevent fertilization of the ovum in the mother's womb. In this work, electrochemical methods were used to study the accelerated corrosion of the Cu 380A T in uterine mucosa in a thin film cell, the corrosive attack was analyzed with scanning electron microscopy, the corrosion products by EDS, and the half-life of T Cu-380A in the simulated maternal uterus was calculated, finding that the half-life of the copper IUD is approximately 10 years and the corrosion products formed are CuO, Cu2O, phosphates, Cu2 S, CaCO3 and copper hydroxide (Cu (OH )2) among others.

RESUMEN El DIU de cobre es un dispositivo intrauterino que actúa mecánica y químicamente para evitar la fertilización del óvulo en el útero materno. En este trabajo se usaron métodos electroquímicos para estudiar la corrosión acelerada de la T de Cu 380A en mucosa uterina en una celda de película delgada, se analizó el ataque corrosivo con microscopía electrónica de barrido, los productos de corrosión por EDS, y se calculó la vida media de la T Cu-380A en el útero materno simulado, encontrándose que la vida media del DIU de cobre es 10 años aproximadamente y los productos de corrosión formados son CuO, Cu2O, fosfatos, Cu2S, CaCO3 e hidróxido de cobre (Cu(OH)2) entre otros.

ABSTRACT Dental alloys in the oral cavity release ions by corrosive action of saliva, which are deposited in the lower part of the mouth, others diffuse through the gums and most of them pass to the gastrointestinal system. In the present work, nine dental alloys frequently used in our country by people with low resources (316L stainless steel, low and high copper silver amalgams, Co-Cr and Ni-Cr alloys, Cu and Ti-6Al-4V base alloys). Its open circuit corrosion potential was measured, its potentiodynamic polarization curves were plotted and corrosion products were analyzed by EDAX, finding Hg, Ag, Ni, Co, Cu, Zn and Si ions, which can affect the health of users, so it is recommended that dentists and dental technicians inform patients who suffer from hypersensitivity do not use alloys containing potentially allergic metals.

RESUMEN Las aleaciones dentales en la cavidad oral liberan iones por acción corrosiva de la saliva, los cuales se depositan en la parte inferior de la boca, otros se difunden a través de las encías y la mayor parte pasan al sistema gastrointestinal. En el presente trabajo se sometieron a ensayos de corrosión acelerada en saliva artificial nueve aleaciones dentales de uso frecuente en nuestro país por personas de bajos recursos (acero inoxidable 316L, amalgamas de plata de bajo y alto cobre, aleaciones Co-Cr y Ni-Cr, aleaciones base Cu y Ti-6Al-4V). Se midió su potencial de corrosión a circuito abierto, se trazaron sus curvas de polarización potenciodinámicas y se analizaron por EDAX los productos de corrosión encontrándose iones Hg, Ag, Ni, Co, Cu, Zn y Si, los cuales pueden afectar la salud de los usuarios, por lo que se recomienda a odontólogos y técnicos dentales informar a los pacientes que sufren de hipersensibilidad no usar aleaciones que contengan metales potencialmente alérgicos.

RESUMO Neste trabalho foram determinados os potenciais e densidades de corrosão das ligas Ti-6Al-4V, Co-Cr e Ni-Cr e, usando o método Evans, os potenciais e densidades de corrosão dos acoplamentos galvânicos formados pela liga de titânio com cada uma das ligas dentárias de Co-Cr e Ni Cr, mostrando que os pares galvânicos mais resistentes à corrosão na saliva artificial ai-reada são aqueles formados entre Ti-6Al-4V com as ligas de Co-Cr e o menos resistente entre a liga de titânio e as ligas de Ni-Cr. A superfície das sete ligas consideradas neste trabalho também foi estudada e pela EDAX os produtos de corrosão foram analisados.

ABSTRACT In this work, the open-circuit corrosion potentials of the alloys studied in aerated artificial saliva were determined; in the same solution, the potentiodynamic polarization curves of said alloys have been drawn. The corrosion potentials and current intensities of the galvanic coupling of the Ti-6Al-4V alloy with the Co-Cr and Ni-Cr alloys were determined using the Evans method, finding that the galvanic couples more resistant to corrosion in the electrolytic medium considered are those formed between the Ti alloy and the Co-Cr alloys; the least resistant are those formed between Ti alloy and Ni-Cr alloys. The corroded surfaces of the seven alloys considered in this work were also studied, and by EDAX the corrosion products due to the ions detached in the electrolytic medium were analyzed.

ABSTRACT In the restoration of lost or damaged dental pieces, different alloys are frequently used, leaving the mouth exposed to electrical currents that circulate through saliva and dental fluids. In the present work, electrochemical methods are used to determine the corrosion rate of galvanic pairs of a high copper silver amalgam with Co-Cr dental alloys in artificial saliva. It is observed that when the difference in corrosion potentials of dissimilar alloys are small (less than 100 mVecs), Evans diagrams do not give good results, so the Mansfeld correction formulas must be used. Thus, it is found that the most resistant to corrosion is the pair formed between the amalgam and the bulk Co-Cr alloy (PG1,3) and that the corrosion products released in greater quantity to the electrolyte are those that contain ions of Co, Cr, Ag, Sr and Cu.

RESUMEN En la restauración de piezas dentales perdidas o deterioradas se usan frecuentemente diferentes aleaciones quedando la boca expuesta a corrientes eléctricas que circulan a través de la saliva y los fluidos dentarios. En el presente trabajo se utilizan métodos electroquímicos para determinar la velocidad de corrosión de pares galvánicos de una amalgama de plata de alto cobre con aleaciones dentales Co-Cr en saliva artificial. Se observa que cuando la diferencia de potenciales de corrosión de las aleaciones disímiles son pequeñas (menos de 100 mVecs), los diagramas de Evans no dan buenos resultados, por lo que deben usarse las fórmulas de corrección de Mansfeld. De éste modo se encuentra que el más resistente a la corrosión es el par formado entre la amalgama y la aleación Co-Cr a granel (PG1,3) y que los productos de corrosión liberados en mayor cantidad al electrolito son los que contienen iones de Co, Cr, Ag, Sr y Cu.

ABSTRACT Galvanic corrosion is a metal dissolution process that occurs when two metals of different electrochemical potential are immersed in an electrolyte causing electrical currents between the metals through the conducting medium. To restore lost or damaged teeth, different alloys are used, leaving the mouth exposed to electrical currents that circulate through saliva and dental fluids. In the present work, the potentials and densities of corrosion currents of galvanic pairs of silver amalgams and copper base dental alloys were determined simultaneously using potenciodynamic methods, finding that the most resistant to corrosion are the pairs formed by silver amalgams of high copper and Cu -Zn alloys, and that the corrosion products released in greater quantity in the electrolytic medium are formed by Hg, Cu, Zn and Ni ions.

RESUMEN La corrosión galvánica es un proceso de disolución metálica que se produce cuando dos metales de distinto potencial electroquímico se sumergen en un electrolito originando corrientes eléctricas entre los metales a través del medio conductor. Para restaurar las piezas dentales perdidas o deterioradas se usan diferentes aleaciones quedando la boca expuesta a corrientes eléctricas que circulan a través de la saliva y los fluidos dentarios. En el presente trabajo se determinaron simultáneamente, los potenciales y densidades de corrientes de corrosión de pares galvánicos de amalgamas de plata y aleaciones dentales base cobre usando métodos potenciodinámicos, encontrando que los más resistentes a la corrosión son los pares formados por amalgamas de plata de alto cobre y aleaciones Cu – Zn, y que los productos de corrosión liberados en mayor cantidad en el medio electrolítico están formados por iones Hg, Cu, Zn y Ni.