Evaluation of the release of nickel and titanium under orthodontic treatment.

The metal alloys used in dentistry are made mainly of nickel (Ni), titanium (Ti), and other elements such as molybdenum (Mo), zirconium (Zr), iron (Fe), tin (Sn), chrome (Cr), carbon (C), copper (Cu) and niobium (Nb) which can release metal ions in unstable environments. The aim of this work was determine the salivary pH before and during orthodontic treatment; evaluate the release of metal ions, mainly Ni and Ti, in urine and saliva using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES); and evaluate the corrosion using Scanning Electronic Microscopy (SEM). In this study, we selected 35 individuals under orthodontic treatment, from whom saliva and urine samples were collected in 3 stages: (a) basal, (b) at 3 and (c) 6 months after the placement of the fixed appliances. SEM analyzed the Ni-Ti (0.016″) and stainless steel (SS) (0.016 × 0.022″) archs after 1 month of being in contact with the oral cavity. Statistical analysis was performed with Stata using the ANOVA model of repeated measures with a p < 0.05. A statistically significant difference in the concentration of Ni in saliva were found between 3 and 6 months of intervention and Ti in urine was found 3 and 6 months.

Influência da deformação cíclica em torção na resistência à fadiga flexura dos instrumentos rotatórios de NiTi Hyflex CM, Typhoon CM e Vortex Blue / The influence of cyclic torcional straining on the flexural fatigue resistance of Hyflex CM, Typhoon CM and Vortex Blue rotary NiTi instruments

Os instrumentos rotatórios de NiTi são submetidos simultaneamente a tensões cíclicas flexurais e torcionais durante preparo de canais radiculares. As propriedades mecânicas destes instrumentos são afetadas por fatores como geometria, microestrutura, composição química da liga e tratamentos termomecânicos. Neste estudo avaliou-se a influência da deformação cíclica por torção na resistência à fadiga flexural de instrumentos Hyflex CM (HF; Coltene/ Whaladent Inc.), Typhoon CM, (TYP; Clinician´sChoice Dental Products,) e Vortex Blue (VB; Dentsply Tulsa Dental), calibre e taper 30/.06. Dez instrumentos novos de cada sistema foram ensaiados em um dispositivo de bancada para a determinação do número médio de ciclos até a fratura por fadiga (Nf), e outro grupo (n=10) foi submetido a um carregamento cíclico torcional de 20 ciclos contínuos de 0° a 180°. Após o carregamento, os instrumentos foram ensaiados até a ruptura por fadiga flexural nas mesmas condições que o controle. As superfícies longitudinais, bem como as superfícies de fratura por fadiga foram examinadas em microscópio eletrônico de varredura. Os resultados foram analisados pelo teste ANOVA (¿ = .05). Os instrumentos HF novos mostraram-se mais resistentes à fratura por fadiga (P < .05) seguidos por VB e TYP. Durante a ciclagem em torção, os instrumentos apresentaram redução no torque após o primeiro ciclo, com tendência à estabilização nos ciclos subsequentes. A maior queda nos valores médios de torque foi observada nos instrumentos TYP. Após o carregamento em torção, houve redução de 20%, 39% e 45% nos valores médios de Nf dos instrumentos HF, VB e TYP, respectivamente. Trincas longitudinais, decorrentes da ciclagem torcional não foram visualizadas em instrumentos CM (HF e TYP), apenas em VB. A superfície de fratura dos instrumentos HF mostrou maiores áreas de nucleação e crescimento lento de trincas. Os instrumentos avaliados, que envolvem tratamentos térmicos em sua fabricação, apresentaram comportamentos e possivelmente microestruturas distintas. Houve uma redução da resistência à fadiga após a deformação cíclica em todos os instrumentos avaliados

The NiTi rotary instruments undergo simultaneous flexural and torcional stresses during the root canal shaping. The mechanical properties of these instruments are influenced by many factors such as geometry, microstructure, chemical composition of the alloy and thermomechanical treatments. In this study, the influence of cyclic torsional straining on the fatigue resistance of different thermal treated instruments was assessed. Hyflex CM (HF; Coltene/ Whaladent Inc.), Typhoon CM, (TYP;Clinician´sChoice Dental Products,) e Vortex Blue (VB; Dentsply Tulsa Dental), size and taper 30/.06 were the instruments chosen, based on their geometry and specific characteristics of their manufacturing process. Ten new instruments for each system were tested in a bench test device to determine the mean value of the number of cycles to failure (Nf) of new instruments (GC, Control Group); another group (of 10instruments was submitted to 20 cycles of torsional straining between 0° and 180°. After the cyclic straining, the instruments (EG, Experimental Group) were submitted to fatigue until rupture under the same conditions of the control group. The longitudinal area and the fatigue fracture surfaces were examined by scanning electron microscopy (SEM). The results were analyzed by one-way analysis of variance ANOVA ( = .05). The new HF instruments displayed a higher resistance to fatigue (P < .05), followed by VB and TYP. During the torsional preloads, theinstruments exhibited a decrease in the torque values after the first cycle, with a tendency of stabilization in the following cycles. The lowest mean torque value was observed for the TYP instruments. After the torsional preloads, there was reduction of 20%, 39% and 45% of the mean Nf values for the instruments HF, VB and TYP, respectively. Longitudinal cracks, generated during the torsional preload were not observed in the CM instruments (HF and TYP), but were present in VB files. The instruments evaluated that involve a thermal treatment during its manufacturing, presented different mechanical behavior and possible distinct microstructure. There was a reduction in fatigue resistance after cyclic deformation in all instruments evaluated.Key words: Mechanical Torsion, Fatigue, Alloy, Instrumentation, CM instruments, Thermomechanical Treatment, Cyclic Loading

A clinical report of an oral lichen planus associated to epidermoid carcinoma in contact with metallic restorations.

The aim of this study was to relate the clinical case of a patient with oral lichen planus (OLP) and a history of epidermoid carcinoma associated with metallic restorations. The etiology of OLP is a mucocutaneous disease, which is poorly understood. Studies point to the potential of malignant transformation of OLP and its association with metallic restorations. The metallic restorations were replaced by crowns with a ceramic covering associated and osseointegrated implants in the edentulous areas. About 1 year later, it was observed a bilateral regression of the tongue lesions. The replacement of metallic restorations can contribute to improvement of OLP.

Allergy to nickel in orthodontic patients: clinical and histopathologic evaluation.

Adverse reactions stemming from the use of fixed and removable orthodontic appliances have been a cause for concern for both orthodontists and researchers in the health care field. Nickel often has been indicated as a biological sensitizer capable of causing short- and long-term reactions (Type IV immune response). This article addresses the clinical and diagnostic aspects of nickel-related reactions in orthodontic patients, based on the literature. A case report highlighting the periodontal, clinical, and histopathologic aspects of an allergic patient in orthodontic treatment is presented.

The issue of corrosion in dental implants: a review

El titanio puro o en aleación, y en menor grado el circonio, son los metales más utilizados en contacto directo con los tejidos del huésped. Estos biomateriales metálicos son muy reactivos y al exponerse a medios líquidos o al aire, desarrollan rápidamente una capa de dióxido de titanio (TiO2) ó de dióxido de circonio (ZrO2). Esta capa de dióxido limita la interfase entre el medio biológico y la estructura metálica, determinando el grado de biocompatibilidad y la respuesta biológica del implante. La corrosión es el deterioro que sufre un metal debido al medio que lo rodea (ataque lectroquímico) y que produce como consecuencia la liberación de iones en el micro ambiente. In vivo ningún metal o aleación es completamente inerte. Los fenómenos de corrosión, en la zona de la interfase, son de especial importancia en la evolución de los implantes tanto odontológicos como ortopédicos y constituyen una de las posibles causas de fracaso de un implante luego de léxito inicial. El presente trabajo comprende una revisión bibliográfica y la presentación de resultados de las experiencias de nuestro laboratorio en relación al estudio de la corrosión con especial énfasis en los implantes odontológicos. La degradación “in situ” de un implante metálico es un hechono deseable ya que altera la integridad estructural del implante. La problemática de la corrosión no se limitaría a un problema local dado que las partículas resultantes de este proceso podrían migrar a sitios alejados al sitio del implante, cuya evolución plantea interrogantes para futuros estudios.

The issue of corrosion in dental implants: a review

El titanio puro o en aleación, y en menor grado el circonio, son los metales más utilizados en contacto directo con los tejidos del huésped. Estos biomateriales metálicos son muy reactivos y al exponerse a medios líquidos o al aire, desarrollan rápidamente una capa de dióxido de titanio (TiO2) ó de dióxido de circonio (ZrO2). Esta capa de dióxido limita la interfase entre el medio biológico y la estructura metálica, determinando el grado de biocompatibilidad y la respuesta biológica del implante. La corrosión es el deterioro que sufre un metal debido al medio que lo rodea (ataque lectroquímico) y que produce como consecuencia la liberación de iones en el micro ambiente. In vivo ningún metal o aleación es completamente inerte. Los fenómenos de corrosión, en la zona de la interfase, son de especial importancia en la evolución de los implantes tanto odontológicos como ortopédicos y constituyen una de las posibles causas de fracaso de un implante luego de léxito inicial. El presente trabajo comprende una revisión bibliográfica y la presentación de resultados de las experiencias de nuestro laboratorio en relación al estudio de la corrosión con especial énfasis en los implantes odontológicos. La degradación ¶in situ÷ de un implante metálico es un hechono deseable ya que altera la integridad estructural del implante. La problemática de la corrosión no se limitaría a un problema local dado que las partículas resultantes de este proceso podrían migrar a sitios alejados al sitio del implante, cuya evolución plantea interrogantes para futuros estudios.(AU)

In vitro cytotoxicity of dental alloys and cpTi obtained by casting.

BACKGROUND: This study aimed to compare the cytotoxicity of base-metal dental alloys and to evaluate if the casting method could influence their cytotoxicity. METHODS: Disks of base-metal dental alloys were cast by two methods: plasma, under argon atmosphere, injected by vacuum-pressure; and oxygen-gas flame, injected by centrifugation, except Ti-6Al-4V and commercially pure titanium (cpTi), cast only by plasma. SCC9 cells were cultured in culture media D-MEM/Ham's F12 supplemented, at 37 degrees C in a humidified atmosphere of 5% carbon dioxide and 95% air, on the previously prepared disks. At subconfluence in wells without disks (control), cell number and viability were evaluated. RESULTS: In plasma method, cpTi and Ti-6Al-4V were similar to control and presented higher number of cells than all other alloys, followed by Ni-Cr. In oxygen-gas flame method, all alloys presented fewer cells than control. Ni-Cr presented more cells than any other alloy, followed by Co-Cr-Mo-W which presented more cells than Ni-Cr-Ti, Co-Cr-Mo, and Ni-Cr-Be. There were no significant differences between casting methods related to cell number. Cell viability was not affected by either chemical composition or casting methods. CONCLUSION: cpTi and Ti-6Al-4V were not cytotoxic while Ni-Cr-Be was the most cytotoxic among tested alloys. The casting method did not affect cytotoxicity of the alloys.

Hypersensitivity to conventional and to nickel-free orthodontic brackets.

The aim of this study was to evaluate the allergenic potential of orthodontic brackets, comparing the cutaneous sensitivity provoked by metals present in conventional metallic brackets to that provoked by brackets with a low concentration of nickel, known as "nickel-free". A sample was selected from 400 patients undergoing treatment in the orthodontic clinic of the Pontifical Catholic University of Minas Gerais (Belo Horizonte, MG, Brazil), in the period from the beginning of 2002 to the end of 2003. A cutaneous sensitivity patch test containing 5% nickel sulphate was used in 58 patients (30 males and 28 females), aged between 11 and 30, which were using fixed appliances with Morelli brackets in both arches. In a second phase, 30 days later, a comparative test of cutaneous sensitivity was applied to the whole sample with two types of test specimens, in the form of a disc. Two alloys were tested: discs composed of the alloy used in the construction of conventional brackets and discs composed of a nickel-free alloy. The internal part of the forearm was chosen for testing, and 20 test specimens of each experiment (corresponding to the twenty brackets of a complete fixed appliance) were applied. Of the 58 patients evaluated, 16 patients were sensitive to the patch test with 5% nickel sulphate. Out of these 16 patients, 12 developed an allergic reaction to experiment 1 (test specimen with nickel), while in experiment 2, only 5 patients showed sensitivity to that sample. The McNemar test revealed that the nickel-free test specimens provoked less allergic reaction when compared with the conventional alloy (p=0.016).

Hypersensitivity to conventional and to nickel-free orthodontic brackets

The aim of this study was to evaluate the allergenic potential of orthodontic brackets, comparing the cutaneous sensitivity provoked by metals present in conventional metallic brackets to that provoked by brackets with a low concentration of nickel, known as "nickel-free". A sample was selected from 400 patients undergoing treatment in the orthodontic clinic of the Pontifical Catholic University of Minas Gerais (Belo Horizonte, MG, Brazil), in the period from the beginning of 2002 to the end of 2003. A cutaneous sensitivity patch test containing 5 percent nickel sulphate was used in 58 patients (30 males and 28 females), aged between 11 and 30, which were using fixed appliances with Morelli® brackets in both arches. In a second phase, 30 days later, a comparative test of cutaneous sensitivity was applied to the whole sample with two types of test specimens, in the form of a disc. Two alloys were tested: discs composed of the alloy used in the construction of conventional brackets and discs composed of a nickel-free alloy. The internal part of the forearm was chosen for testing, and 20 test specimens of each experiment (corresponding to the twenty brackets of a complete fixed appliance) were applied. Of the 58 patients evaluated, 16 patients were sensitive to the patch test with 5 percent nickel sulphate. Out of these 16 patients, 12 developed an allergic reaction to experiment 1 (test specimen with nickel), while in experiment 2, only 5 patients showed sensitivity to that sample. The McNemar test revealed that the nickel-free test specimens provoked less allergic reaction when compared with the conventional alloy (p = 0.016).

Este trabalho teve como objetivo avaliar a capacidade alergênica provocada pelos bráquetes ortodônticos, comparando a sensibilidade cutânea provocada pelos metais presentes nos bráquetes metálicos convencionais com a provocada por bráquetes com baixa concentração de níquel ("nickel-free"). A amostra foi selecionada dos 400 pacientes em tratamento da clínica de Ortodontia da Pontifícia Universidade Católica de Minas Gerais (Belo Horizonte, MG, Brasil), no período compreendido entre o início de 2002 e o final de 2003. A amostra consistiu de 58 pacientes (30 homens e 28 mulheres), com idades variando de 11 a 30 anos, os quais eram portadores de aparelho ortodôntico fixo Morelli® em ambos os arcos. Estes pacientes foram diagnosticados quanto à sensibilidade ao níquel, por meio da aplicação do "patch test" com sulfato de níquel a 5 por cento. Em uma segunda fase, trinta dias após o "patch test", comparou-se a sensibilidade cutânea provocada pelos metais presentes nos bráquetes convencionais e nos "Nickel Free", por meio de um teste de sensibilidade cutânea utilizando-se dois tipos de corpos-de-provas, em formato de disco, com a mesma composição destes bráquetes. A área de eleição para realização deste teste foi a parte interna do antebraço, sendo aplicados vinte corpos-de-prova de cada experimento (referente a uma boca completa de bráquetes). Dos 58 pacientes avaliados, 16 deles foram sensíveis ao "patch test" com sulfato de níquel a 5 por cento. Dentre estes 16 pacientes, 12 deles desenvolveram reação alérgica ao Experimento 1 (corpo-de-prova com níquel), enquanto que no Experimento 2 (corpo-de-prova "Niquel Free") apenas 5 pacientes apresentaram sensibilidade a esta amostra. O teste de McNemar revelou que os corpos-de-prova "nickel-free" provocaram menor reação alérgica quando comparados aos convencionais (p = 0.016).

Hipersensibilidade a metais utilizados durante o tratamento ortodôntico / Hypersensitivity to metals during orthodontic treatment

Na prática ortodôntica podem ocorrer reações adversas em pacientes devido aos materiais utilizados durante o tratamento, tanto de natureza irritativa como reações de hipersensibilidade. A hipersensibilidade a metais utilizados durante o tratamento ortodôntico consiste em uma resposta inflamatória induzida pela corrosão das estruturas dos dispositivos ortodônticos e subseqüente liberação de íons metálicos. Algumas manifestações clínicas dessa condição compreendem: estomatite, sensação de queimação, presença de gengivite severa com ausência de placa bacteriana, urticária, eczema e dermatite alérgica. Assim, inúmeros estudos foram realizados com o intuito de avaliar a inter-relação entre os metais dos dispositivos ortodônticos e possíveis reações adversas. Em face ao exposto, o presente artigo tem como objetivo realizar uma revisão de literatura, com descrição de um caso clínico sobre a hipersensibilidade a metais utilizados durante o tratamento ortodôntico, contribuindo para um maior conhecimento sobre essa condição.

In orthodontical practice, adverse reactions can occur due to the materials used during the treatment, either irritation or hypersensitivity reactions. The hypersensitivity to metals used during the orthodontic treatment consists in an induced inflammatory response by the corrosion of the structures of the orthodontic devices and subsequent release of metallicions. Some clinical manifestations of this condition are: stomatitis, burning sensation, severe gingivitis in the absence of plaque, generalized urticaria, eczema and allergic dermatitis. Thus, several studies have been carried through with intention of evaluating the interrelation among metals of the orthodontic devices and possible adverse reactions. Therefore, the purpose of this article is to review the literature and discuss a case report about the hypersensitivity to metals used during the orthodontic treatment, contributing to the knowledge of this condition.

Clinical and histologic evaluation of the periodontal response to restorative procedures in the dog.

This study evaluated, in the dog, the periodontal response to resin-modified glass-ionomer cement or amalgam restorations placed in surgical windows and left for 124 days. Plaque control was performed in half of the sites. Histologic analyses showed that sites restored with amalgam were consistently more inflamed than sites restored with resin-modified glass-ionomer. Plaque control was associated with less inflammation in both cases. Some sites restored with resin-modified glass-ionomer presented bone repair and a connective tissue lining. The inflammatory response of the periodontium to resin-modified glass-ionomer restorations is less pronounced than that associated with amalgam restorations.

Porosidade de uma liga de Ag-Pd fundida utilizando dois revestimentos e três fontes caloríficas / Porosity of a Ag-Pd alloy cast using two investiment materials and three heat sources

A porosidade e a análise foram estudadas através de MO e a análise da fração volumétrica de poros, através de um analisador digital de imagens acoplados ao MO, para uma liga do sistema Ag-Pd. Os corpos de prova (em forma de Moeda e MOD), foram incluídos sob pressão, utilizando dois tipos de revestimentos (aglutinado por gesso e fosfato) e três fontes caloríficas (GLP/ar, GLP/oxigênio e máquina de indução). A porosidade esteve presente em todos os corpos de prova, concentrando-se sempre na região próxima ao canal de alimentação

Comparative radiographic evaluation of the alveolar bone crest after orthodontic treatment.

This study evaluated and compared the heights of the alveolar bone crests (AC) among orthodontic patients treated with either the simplified standard edgewise technique (group 1, n = 30), the edgewise straight-wire system (group 2, n = 30), or bioefficient therapy (group 3, n = 26). These 3 groups were compared with an untreated control group (group 4, n = 30). A comparison by sex of AC height was also conducted. The first premolars were extracted in every treated patient, and measurements were performed on bitewing radiographs taken after a mean posttreatment period of 2.17 years. The distances from the AC to the cementoenamel junction (CEJ) on the mesial and distal surfaces of the first molars and second premolars and on the distal surface of the canines were measured; the larger the distance, the greater the alveolar bone loss. The data were analyzed by 1-way analysis of variance and the Newman-Keuls test (P <.05) for comparison among the groups. Sex differences of the AC height were evaluated with the t test. All treated groups had larger, statistically significant CEJ-AC distances than the untreated group, primarily at the extraction areas. There were no consistent statistically significant differences in the areas among the treated groups. Mean distances of the CEJ-AC in boys were larger than or similar to those in girls. The patients in the treated groups showed a greater number of proximal surfaces with statistically significant differences between sexes, compared with the control subjects.

Evaluation of immunologic profile in patients with nickel sensitivity due to use of fixed orthodontic appliances.

The aim of this study was to develop a new approach to testing the impact of nickel antigen on in vitro cell-proliferation assay, to identify adverse reactions to casting alloys among orthodontic patients. Cell-proliferation assay in vitro was used as the basic methodology to assess the influence of such variables as source of nickel antigen, type of serum used to supplement the culture medium, and number of cells in the culture. We selected 35 orthodontic patients who were classified as nickel sensitive and non-nickel sensitive, based on their clinical records. Our results showed that hexahydrated nickel sulfate at 10 microg/mL, 10% of autologous sera, and 2 x 10(5) cells was the best condition for inducing the most marked nickel proliferation response in vitro. This optimized method was able to distinguish nickel-sensitive from non-nickel-sensitive dental patients and also to discriminate those with positive skin tests. Our data suggest that continuous exposure to nickel casting alloys might lead to oral tolerance mechanisms that modulate nickel sensitivity, as evidenced by the lower cell proliferation index in patients undergoing orthodontic treatment over 24 months. Finally, our findings demonstrated a known nickel-induced type 2 immune response and a marked lack of type 1 immunity (interferon gamma) as the hallmarks of nickel-sensitive patients. Further studies are needed to clarify the major cell phenotype associated with this type 2 immune response and the lack of type 1 immunity observed in nickel-sensitive people.

Nickel hypersensitivity reaction before, during, and after orthodontic therapy.

Nickel is a strong biological sensitizer and consequently may induce a delayed hypersensitivity reaction (type IV immune response). Because nickel is a component of the majority of the orthodontic alloys, the objectives of this cross-sectional study were to determine the prevalence of nickel hypersensitivity reaction before, during, and after orthodontic therapy with conventional stainless steel brackets and wires; to evidence the induction of this reaction by the orthodontic appliances; and to characterize the nickel hypersensitive persons. Nickel patch tests and a questionnaire were used to evaluate the hypersensitivity to this metal. The total sample consisted of 170 patients, 105 females and 65 males, from the orthodontic department at Bauru Dental School, University of São Paulo. They were divided into three groups as follows: A (n = 60), patients before the beginning of orthodontic therapy; B (n = 66), patients currently undergoing orthodontic treatment, and C (n = 44), patients who had undergone orthodontic treatment previously. The chi-square test (chi2) showed an allergic reaction in 28.3% of the total sample with 23% female and 5.3% male. This indicated a gender difference (chi2 = 10.75, p < 0.001). There was a positive association between nickel hypersensitivity and previous personal allergic history to metals (chi2 = 34.88, p < 0.0001) as well as with the daily use of metal objects (chi2 = 11.95, p < 0.0005). There was no statistically significant difference in the prevalence of contact dermatitis among the three groups (chi2 = 0.39, p = 0.848). This suggests that orthodontic therapy with conventional stainless steel appliances does not initiate or aggravate a nickel hypersensitivity reaction.

Clinical evaluation of gallium alloy as a posterior restorative material.

This study evaluated 30 gallium alloy (Gallium alloy GF) and 31 amalgam (Dispersalloy) restorations over a period of 8 months in both Class I and Class II cavity preparations in 28 human subjects. At baseline, all gallium alloy and amalgam restorations were considered acceptable (Alfa) in terms of caries, anatomic form, marginal adaptation, surface texture, and bulk fracture. Postoperative sensitivity was reported in 67% of the gallium alloy restorations and in 29% of the amalgam restorations. At 8 months, 61% of the gallium alloy restorations were rated Beta for marginal adaptation, and all restorations exhibited tarnish and corrosion. With a few exceptions, the amalgam restorations were rated Alfa for those criteria. Three gallium alloy restorations had to be replaced during the evaluation period because of severe postoperative sensitivity and 39% of gallium restorations still presented some sensitivity at 8 months. Additional problems exhibited by gallium restorations were tooth fractures, tooth cracks, and marginal whitening.

Efeitos da fonte de calor e do tratamento térmico sobre a dureza superficial e a resistência à corrosäo de ligas metálicas alternativas para uso odontológico / Effects of casting sources and heat treatment on hardness and corrosion resistance of dental base metal alloys

Estudou-se a dureza superficial e a resistência à corrosäo de cinco ligas metálicas alternativas para uso odontológico, fundidas por duas diferentes fontes de calor e sofrendo três diferentes tipos de tratamentos térmicos. Concluiu-se que a liga P (experimental) apresentou os maiores resultados de dureza superficial e os menores resultados de corrosäo superficial. Também foi a liga P (experimental) a única sensível aos tratamentos térmicos e às fontes de calor utilizadas

Corrosión: conceptos generales y posibles efectos biológicos / Corrosion: general concepts and possible biological effects

Como consecuencia de encontrarse metales de distinta composición en boca suelen producirse fenómenos de corrosión que pueden ocasionar alteraciones a nivel de las restauraciones como a nivel local y sistémico. Se presenta una revisión bibliográfica sobre el tema y se analiza dicho fenómeno en estos tres ámbitos: alteraciones de las aleaciones metálicas, alteraciones locales y sistémicas como producto del proceso de corrosión. Se concluye que hay liberación de iones en el medio bucal, pero que los problemas que ocasionan al paciente dependen de sus características individuales, y que las reacciones adversas son bajísimas en comparación al vasto número de restauraciones que son efectuadas; se hace presente la importancia de la anamnesis y el conocimiento sobre las aleaciones metálicas que debe poseer todo odontólogo a fin de prevenir y tratar las posibles alteraciones