Customized fiber posts in root canals prepared with and without laser application: a pull-out evaluation.

This study evaluated the effect of fiber post customization and laser application on the results of pull-out tests in endodontically treated teeth. Forty-eight bovine incisors were stored in aqueous 2% formaldehyde (pH 7.0) for 30 days. At the end of the storage period, the incisors were scraped with No. 11/12 periodontal curettes, rinsed with water and sodium bicarbonate, and stored in 0.9% saline solution for 7 days. Roots with similar shape and dimensions were selected and sectioned to a standard 17-mm length. Root canals were prepared and filled to a depth of 12 mm. The roots were divided into 4 groups (n = 12): 1, conventional fiber post and no laser application; 2, customized fiber post and no laser application; 3, conventional fiber post and laser application; and 4, customized fiber post and laser application. After removal of the obturation material for post space preparation, the canals were enlarged, and a laser beam was applied to the roots of teeth in groups 3 and 4 as an auxiliary disinfection procedure. After cementation of the posts, a pull-out test was performed using an axial tensile load at 0.5 mm/min in a universal testing machine. Analysis of variance and the Tukey test were used for statistical analysis of the results. The mean (SD) maximum tensile force was 10.18 (4.73) kgf in group 1, 38.89 (6.49) kgf in group 2, 27.74 (10.07) kgf in group 3, and 38.92 (6.89) kgf in group 4. These values were significantly higher in groups 2 and 4 than in group 1 (P < 0.05). The customization of fiber posts used for the restoration of pulpless teeth resulted in significantly (P < 0.05) greater pull-out test values, a thinner cement layer, and improved retention.

Análisis de la relación entre la proporción áurea y el parámetro facial / Analysis of the relation between the golden ratio and the facial parameter

Introducción: la habilidad clínica para modificar la forma dentofacial a través del tratamiento ortodóntico, cirugía maxilofacial o cirugía plástica, requiere comprensión de la belleza facial, incluyendo la evaluación de la estética facial, proporciones y simetría. Objetivo: analizar la relación entre los componentes de la proporción áurea con el parámetro facial de estudiantes en la provincia Chiclayo. Métodos: la población de estudio fue representada por 88 estudiantes que cumplieron con los siguientes criterios de inclusión: edad entre 17-28 años, ambos sexos, sin tratamiento ortodóntico, con maloclusión clase I y dentición completa. Se diseñó una ficha de recolección de datos para medidas antropométricas craneofaciales. Se calibraron los examinadores, se evaluó la estabilidad de la concordancia intra e interexaminador mediante el coeficiente Kappa de Cohen. Para el contraste de la hipótesis se utilizó el coeficiente de correlación chi cuadrado. Para todas las pruebas estadísticas el nivel de significancia fue de 5 por ciento (p< 0,05). Resultados: se observó que el 65,91 por ciento del total de pacientes presentaban proporción divina en su dimensión externa, 48,86 por ciento son braquifaciales, 13,64 por ciento mesofaciales, 3,41 por ciento dolicofaciales, y el 57,95 por ciento del total presentaban proporción divina en su relación vertical, 42,05 por ciento son braquifaciales, 10,23 por ciento mesofaciales y 5,68 por ciento dolicofaciales. En cuanto al perfil armónico, el 70,45 por ciento del total de pacientes no presenta proporción divina, de los cuales el 53,41 por ciento son braquifaciales, 10,23 por ciento son mesofaciales y 6,82 por ciento son dolicofaciales. Conclusiones: solo existe relación entre la proporción áurea en su componente de dimensión externa con el parámetro facial. La proporción áurea se cumplió en todos sus componentes, en un mayor porcentaje en los individuos braquifaciales y hubo predominio de la proporción áurea en el sexo femenino(AU)

Introduction: the clinical ability to modify the dentofacial form through orthodontic treatment, maxillofacial surgery, or plastic surgery requires an understanding of facial beauty, including the evaluation of facial aesthetics, proportions, and symmetry. Objective: to analyze the relationship between the components of the golden ratio and the facial parameter of students in the province of Chiclayo. Methods: the study population was represented by 88 students who met the following inclusion criteria: age between 17 and 28 years, both sexes, without orthodontic treatment, with class I malocclusion and complete dentition. A data collection form for craniofacial anthropometric measurements was designed. The examiners were calibrated, the stability of the intra- and inter-rater concordance was evaluated using the Cohen's Kappa coefficient. For the contrast of the hypothesis, the correlation coefficient square chi was used. For all statistical tests, the level of significance was 5 percent (p< 0.05). Results: 65.91 percent of all the patients were observed to have a divine proportion in their external dimension: 48.86 percent are brachifacial, 13.64 percent mesofacial, and 3.41 percent dolichofacial. 57.95 percent of the total number of patients presented divine proportion in its vertical relation: 42.05 percent are brachifacial, 10.23 percent mesofacial, and 5.68 percent dolichofacial. Regarding the harmonic profile, 70.45 percent of the total number of patients did not present a divine proportion: 53.41 percent are brachifacial, 10.23 percent are mesofacial, and 6.82 percent are dolichofacial. Conclusions: there is only a relationship between the golden ratio in its external dimension component and the facial parameter. The golden ratio was fulfilled in all its components, in a greater percentage in the brachifacial individuals, and there was a predominance of the golden ratio in the female sex(AU)

Análisis de la relación entre la proporción áurea y el parámetro facial / Analysis of the relation between the golden ratio and the facial parameter

Introducción: la habilidad clínica para modificar la forma dentofacial a través del tratamiento ortodóntico, cirugía maxilofacial o cirugía plástica, requiere comprensión de la belleza facial, incluyendo la evaluación de la estética facial, proporciones y simetría. Objetivo: analizar la relación entre los componentes de la proporción áurea con el parámetro facial de estudiantes en la provincia Chiclayo. Métodos: la población de estudio fue representada por 88 estudiantes que cumplieron con los siguientes criterios de inclusión: edad entre 17-28 años, ambos sexos, sin tratamiento ortodóntico, con maloclusión clase I y dentición completa. Se diseñó una ficha de recolección de datos para medidas antropométricas craneofaciales. Se calibraron los examinadores, se evaluó la estabilidad de la concordancia intra e interexaminador mediante el coeficiente Kappa de Cohen. Para el contraste de la hipótesis se utilizó el coeficiente de correlación chi cuadrado. Para todas las pruebas estadísticas el nivel de significancia fue de 5 por ciento (p< 0,05). Resultados: se observó que el 65,91 por ciento del total de pacientes presentaban proporción divina en su dimensión externa, 48,86 por ciento son braquifaciales, 13,64 por ciento mesofaciales, 3,41 por ciento dolicofaciales, y el 57,95 por ciento del total presentaban proporción divina en su relación vertical, 42,05 por ciento son braquifaciales, 10,23 por ciento mesofaciales y 5,68 por ciento dolicofaciales. En cuanto al perfil armónico, el 70,45 por ciento del total de pacientes no presenta proporción divina, de los cuales el 53,41 por ciento son braquifaciales, 10,23 por ciento son mesofaciales y 6,82 por ciento son dolicofaciales. Conclusiones: solo existe relación entre la proporción áurea en su componente de dimensión externa con el parámetro facial. La proporción áurea se cumplió en todos sus componentes, en un mayor porcentaje en los individuos braquifaciales y hubo predominio de la proporción áurea en el sexo femenino(AU)

Introduction: the clinical ability to modify the dentofacial form through orthodontic treatment, maxillofacial surgery, or plastic surgery requires an understanding of facial beauty, including the evaluation of facial aesthetics, proportions, and symmetry. Objective: to analyze the relationship between the components of the golden ratio and the facial parameter of students in the province of Chiclayo. Methods: the study population was represented by 88 students who met the following inclusion criteria: age between 17 and 28 years, both sexes, without orthodontic treatment, with class I malocclusion and complete dentition. A data collection form for craniofacial anthropometric measurements was designed. The examiners were calibrated, the stability of the intra- and inter-rater concordance was evaluated using the Cohen's Kappa coefficient. For the contrast of the hypothesis, the correlation coefficient square chi was used. For all statistical tests, the level of significance was 5 percent (p< 0.05). Results: 65.91 percent of all the patients were observed to have a divine proportion in their external dimension: 48.86 percent are brachifacial, 13.64 percent mesofacial, and 3.41 percent dolichofacial. 57.95 percent of the total number of patients presented divine proportion in its vertical relation: 42.05 percent are brachifacial, 10.23 percent mesofacial, and 5.68 percent dolichofacial. Regarding the harmonic profile, 70.45 percent of the total number of patients did not present a divine proportion: 53.41 percent are brachifacial, 10.23 percent are mesofacial, and 6.82 percent are dolichofacial. Conclusions: there is only a relationship between the golden ratio in its external dimension component and the facial parameter. The golden ratio was fulfilled in all its components, in a greater percentage in the brachifacial individuals, and there was a predominance of the golden ratio in the female sex(AU)

Perception and expectation. What do patients really want from the dental treatment? / Percepção e expectativa. O que os pacientes realmente querem do tratamento dental?

ABSTRACT Objective The aim of this study was to investigate the subjective aspects related to the perception of dental appearance and expectations of patients who receive dental treatment in graduation clinics of the Araçatuba Dental School. Methods It was evaluated 362 patients of both gender aged over 18. The questionnaire included questions of demographic data, questions to assess facial and dental aesthetics, dental satisfaction and treatments considering patients notion to improve dental esthetics. The data collected was analyzed using descriptive statistics and the chi-square test. Results The factor teeth for facial analysis and factor positioning in the arch for smile analysis were considered the most important subjects regarding the esthetic according to the respondents. 67.5% of patients were dissatisfied with the appearance of their teeth, and dissatisfaction with the color was the most important factor (66.8%). The treatment most desired was tooth whitening and 85.0% of patients said yes to it. Conclusion Respondents place great value on the teeth on the face appearance, and it can be seen that aesthetic treatments are highly valued in all age groups. There is a need for treatments to restore the function, but treatments to improve dental appearance were the most requested.

RESUMO Objetivo Avaliar os aspectos subjetivos relacionados à percepção da aparência dental e expectativas de pacientes que recebem tratamento odontológico nas clínicas de graduação da Faculdade de Odontologia de Araçatuba. Métodos Foram avaliados 362 pacientes de ambos os sexos com idade superior a 18. O questionário incluiu perguntas sobre dados demográficos, perguntas para avaliar a estética facial e dentária, a satisfação dental e tratamentos considerando a noção dos pacientes de melhorar a estética dental. Os dados coletados foram analisados por meio de estatística descritiva e o teste do qui-quadrado. Resultados O fator dentes para análise facial e o fator posicionamento no arco para análise sorriso foram considerados os temas mais importantes a respeito da estética, de acordo com os entrevistados. 67,5% dos pacientes estavam insatisfeitos com a aparência de seus dentes, a insatisfação com a cor foi o fator mais importante (66,8%). O tratamento mais desejado foi o clareamento dental e 85,0% dos pacientes disse sim a ele. Conclusão Os pacientes dão grande valor aos dentes sobre a aparência rosto, e ele pode ser visto que os tratamentos estéticos são altamente valorizados em todos os grupos etários. Há uma necessidade de tratamentos para restabelecer a função, mas os tratamentos para melhorar a aparência dentária foram os mais solicitados.

Esplintagem em próteses implantossuportadas: revisão de literatura / Splinting in implant-supported prostheses: literature review

A distribuição da carga oclusal na interface osso/implante é um fator de sucesso a longo prazo dos implantes, o objetivo da esplintagem dos implantes é aumentar a resistência da unidade esplintada e minimizar a transferência da carga horizontal à interface osso/ implante, aumentando a área de superfície óssea. O propósito do deste estudo foi realizar uma revisão de literatura sobre a esplintagem das próteses implantossuportadas, a fim de discutir o comportamento biomecânico, vantagens e desvantagens das próteses esplintadas. Para a identificação dos estudos deste trabalho foi realizada uma estratégia de busca nas bases de dados PubMed, e LILACS, entre 2007 e maio 2017, utilizando os descritores: splinting, implant-supported prostheses, dental implant. Os critérios de inclusão foram: estudos clínicos, estudos in vitro, estudos prospectivos e retrospectivos, revisões de literatura e sistemáticas, relacionados ao tema proposto. Os critérios de exclusão foram: artigos cujo idioma não fosse o inglês ou português. Após a aplicação dos critérios de inclusão e exclusão 24 artigos foram analisados. Demostrou-se que: A maioria dos estudos in vitro analisados indicam a vantagem biomecânica da esplintagem dos implantes adjacentes, a fim de favorecer a distribuição das tensões na região periimplantar. A esplintagem de implantes curtos na região posterior teve um comportamento favorável tanto nos estudos clínicos quanto nos estudos in vitro, principalmente sob carregamento oblíquo. Os estudos clínicos ainda se mostram contraditórios em relação a conservação do nivel ósseo crestal. Entretanto, pesquisas têm apontado uma melhor efetividade da esplintagem na proporção coroa/implante sendo mais favorável para certas alturas da coroa(AU)

The stress distribution of the occlusal load at the bone/ implant interface is a factor for the long-term success of the implants, the goal of splinting implants is to increase the strength of the splinting unit and to minimize horizontal load transfer at the bone/implant interface, increasing the bone area. The purpose of this study was to perform a review of the literature on the splinted implant-supported in order to discuss the biomechanical behavior, advantages and disadvantages of the splinted prostheses. For the identification of the studies of this study, a search strategy was performed in PubMed and LILACS databases between 2007 and May 2017, using the descriptors: splinting, implant-supported prostheses, dental implant. The inclusion criteria were: clinical studies, in vitro studies, prospective and retrospective studies, literature reviews and systematic, related to the proposed theme. The exclusion criteria were: articles whose language was not English or Portuguese. After applying the inclusion and exclusion criteria, 24 articles were analyzed. It has been demonstrated that: Most of the in vitro studies analyzed indicate the biomechanical advantage of the splinting of the adjacent implants, in order to favor the distribution of the stress in the peri-implant region. The splinting of short implants in the posterior region had a favorable behavior both in clinical studies and in in vitro studies, especially under oblique loading. Clinical studies are still contradictory regarding preservation of the crestal bone level. However, research has indicated a better effectiveness of the splinting crown/implant ratio being more favorable for certain crown heights(AU)

Removable Partial Denture After Gunshot Injury: Five Year Follow-Up.

The aim of this study was to report a patient of rehabilitation with removable partial denture retained by implants in-patient who suffered injury after firearm shooting. A 19-year-old man presented to the hospital of the Val Paraíso city after being hit by a bullet in the right on the face, affecting the teeth 12 to 16. The surgery to remove the shards of teeth, and bullet was performed. Surgical team opted for installation of implants without bone grafts; however, due to extensive loss of alveolar bone, only 3 tilted implants (2 Ø3.75 × 8.5 mm and 1 Ø3.75 × 10 mm) were installed. After recovery, the patient was referred to the Araçatuba Dental School-UNESP for the rehabilitation on the affected region. The difficulty of rehabilitation with conventional fixed prostheses was verified during the prosthetic phase. This way, it was opted for rehabilitation with removable partial dentures associated with dental implant. Two attachment system ERA (ERA, Sterngold) were positioned in the bar to make the removable partial denture. After 5 years of follow-up, the authors can conclude that the use of removable partial denture retained by implants is effective for functional and aesthetic rehabilitation, favoring socialization and self-esteem of the patient.

Análise das tensões em diferentes conexões de implante/ abutment / Stress analysis in different implant/abutment connections

O objetivo deste estudo foi comparar, por meio de uma análise fotoelástica, as tensões geradas na região peri-implantar dos implantes com diferentes conexões protéticas. Foram confeccionados 4 modelos em resina fotoelástica com implante unitário e coroa em alturas padronizadas. Mod 1: Hexágono Externo; Mod 2: Hexágono Interno; Mod 3: Cone-Morse e Mod 4: Corpo-único. Foi aplicada uma carga de 100N, tanto axial quanto obliquamente (45°) por meio da máquina de ensaio universal. O carregamento foi realizado em pontos fixos padronizados na superfície oclusal. Os resultados foram registrados fotograficamente por meio de uma câmera digital e analisados de forma qualitativa com auxílio do Adobe Photoshop. Tanto no carregamento axial quanto no carregamento oblíquo, observou-se que o implante de corpo-único apresentou a maior quantidade de franjas, ao contrário dos implantes de conexão interna. A diferença encontrada entre os modelos, quando da variação do sentido da carga, ocorreu devido ao fato de na carga oblíqua haver um maior número de franjas, e essas se concentram não só na região apical mas também do lado oposto à aplicação da carga, na região cervical. Concluiu-se que os implantes de conexão interna apresentaram a situação biomecânica mais favorável e os implantes de corpo-único apresentaram a maior concentração de tensões... (AU)

The aim of this study was to compare, by means of aphotoelastic analysis, the stresses generatedin the periimplantar regionof different implant/abutment connections. 4 modelswere fabricatedinphotoelastic resinwithsingle dental implantandstandardheight crowns. Mod 1: External Hexagon; Mod 2: Internal Hexagon; Mod 3: Morse-Taper and Mod4: One-Piece. It were applieda 100N axial and oblique (45°) loading by means of a universal testing machine. The loadwas appliedat standardized points on the occlusal surface. The results were recordedphotographicallyusinga digital camera andanalyzed qualitativelywiththeaid of the AdobePhotoshop software. Both inaxial and in the oblique loading, it was observed that one-piece implantshowed the highest number of fringes, apart from the internal connection implants. The differencebetween the models,whenthedirection of the load was changed, occurred duetotheoblique loading that caused greaternumber of fringes concentrated not onlyin the apical region, but also in the opposite side of the load application in the cervical region. It was concluded thattheinternal connection implants presented themost favorablebiomechanical situationand the one-piece implant presented the higheststress concentration... (AU)

Effect of mechanical cycling on screw torque in external hexagon implants with and without platform switching.

This in vitro study evaluated the effect of mechanical cycling on the torque of retaining screw in external hexagon implants with platform switching (PS), regular platform (RP) and wide platform (WP). A total of 30 specimens were equally divided into 3 groups: PS, PR and WP. Each specimen was prepared with implants: 3.75 x 10 mm for RP group and 5.0x10 mm for PS and WP groups and its respective abutment with 32 Ncm torque. All groups were subjected to 106 cycles with 100 N (corresponding to about 40 months of chewing). The results were obtained with the reverse torque of each specimen and data were evaluated using ANOVA and Tukey test (p<0.05). The PS group showed statistically significant difference in screw removal torque (30.06±5.42) compared with RP (23.75±2.76) and WP (21.32±3.53) (p<0.05) groups; the RP and WP groups showed no statistically significant difference between them. It was concluded that the PS group showed higher reverse torque value, suggesting lower susceptibility of the abutment screw loosening.

Influence of parafunctional loading and prosthetic connection on stress distribution: a 3D finite element analysis.

STATEMENT OF PROBLEM: Clinicians should consider parafunctional occlusal load when planning treatment. Prosthetic connections can reduce the stress distribution on an implant-supported prosthesis. PURPOSE: The purpose of this 3-dimensional finite element study was to assess the influence of parafunctional loading and prosthetic connections on stress distribution. MATERIAL AND METHODS: Computer-aided design software was used to construct 3 models. Each model was composed of a bone and an implant (external hexagon, internal hexagon, or Morse taper) with a crown. Finite element analysis software was used to generate the finite element mesh and establish the loading and boundary conditions. A normal force (200-N axial load and 100-N oblique load) and parafunctional force (1000-N axial and 500-N oblique load) were applied. Results were visualized as the maximum principal stress. Three-way analysis of variance and Tukey test were performed, and the percentage of contribution of each variable to the stress concentration was calculated from sum-of squares-analysis. RESULTS: Stress was concentrated around the implant at the cortical bone, and models with the external hexagonal implant showed the highest stresses (P<.001). Oblique loads produced high tensile stress concentrations on the site opposite the load direction. CONCLUSIONS: Internal connection implants presented the most favorable biomechanical situation, whereas the least favorable situation was the biomechanical behavior of external connection implants. Parafunctional loading increased the magnitude of stress by 3 to 4 times.

Effect of Mechanical Cycling on Screw Torque in External Hexagon Implants with and without Platform Switching

This in vitro study evaluated the effect of mechanical cycling on the torque of retaining screw in external hexagon implants with platform switching (PS), regular platform (RP) and wide platform (WP). A total of 30 specimens were equally divided into 3 groups: PS, PR and WP. Each specimen was prepared with implants: 3.75 x 10 mm for RP group and 5.0x10 mm for PS and WP groups and its respective abutment with 32 Ncm torque. All groups were subjected to 106 cycles with 100 N (corresponding to about 40 months of chewing). The results were obtained with the reverse torque of each specimen and data were evaluated using ANOVA and Tukey test (p<0.05). The PS group showed statistically significant difference in screw removal torque (30.06±5.42) compared with RP (23.75±2.76) and WP (21.32±3.53) (p<0.05) groups; the RP and WP groups showed no statistically significant difference between them. It was concluded that the PS group showed higher reverse torque value, suggesting lower susceptibility of the abutment screw loosening.

Este estudo in vitro avaliou o efeito da ciclagem mecânica no torque dos parafusos de retenção em implantes de hexágono externo com plataforma switching (PS), plataforma regular (RP) e plataforma larga (WP). Foram utilizados 30 corpos de prova divididos em 3 grupos equitativamente: PS, RP e WP. Cada corpo de prova foi preparado com implantes: 3,75x10 mm para o grupo RP e 5,0x10 mm para os grupos PS e WP, e seu respectivo abutment com o torque de 32 Ncm. Todos os grupos foram submetidos a 106 ciclos com 100 N de força (o que corresponde a aproximadamente 40 meses de mastigação). Os resultados foram obtidos com o torque reverso de cada espécime e os dados foram avaliados com ANOVA comparado com o teste de Tukey (p<0,05). O grupo PS apresentou diferença estatisticamente significante no torque de remoção do parafuso (30,06±5,42) comparado com os grupos RP (23,75±2,76) e WP (21,32±3,53) (p<0,05); os grupos RP e WP não apresentaram diferença estatisticamente significante entre si. Concluiu-se que o grupo PS apresentou maior valor de torque reverso sugerindo menor susceptibilidade de afrouxamento do parafuso de fixação do abutment.

Streptococcus mutans adhesion and releasing of metallic ions in dental alloys

To evaluate the adherence of Streptococcus mutans to the surface of the amalgam and copper/aluminum alloy samples and also evaluate the release of metallic ions. METHODS: The prepared medium was changed every 72 h and analyzed by atomic absorption spectrophotometer. Samples were removed from the prepared medium at 15, 30, 48 and 60 days. RESULTS: The result shows that ions released were statistically different among all groups, and so were both biofilm and pits formation and the corrosion induced by the S. mutans in both types of samples. SEM observation of the samples immersed in the prepared medium with S. mutans showed adherence of microorganisms on the whole surface, in all groups. CONCLUSIONS: The S. mutans adhere to both amalgam and copper/aluminum alloy causing corrosion of those restorations. S. mutans produced a greater ions release in Cu/Al alloy; in amalgam, the ions release was not influenced by exposure to S. mutans...

Relation between bruxism and dental implants / Relação entre bruxismo e próteses sobre implantes

OBJECTIVE: The aim of this study was to gather information and discuss the predictability of implant-supported prostheses in patients with bruxism by performing a literature review. METHODS: In order to select the studies included in this review, a detailed search was performed in PubMed and Medline databases, using the following key words: bruxism, dental implants, implant supported prosthesis, and dental restoration failure. Items that were included are: case reports, randomized controlled trials, in vitro studies, literature and systematic reviews, with or without meta-analysis, of the last 20 years that addressed the theme. Articles without abstracts, animal studies, articles in languages other than English and articles from journals unrelated to the dental field were excluded. RESULTS: after analysis according to inclusion and exclusion criteria, 28 articles were selected from a total of 54. It is known from the array of scientific articles which have assessed, either through retrospective, prospective or experimental studies, that the biomechanical and biological impact of bruxism on implant-supported prostheses is small, and that the literature has contributed little to exemplify the prosthetic limits of safety for the specialist from a clinical point of view. CONCLUSION: Although there is still no general consensus on this matter, most of the literature review articles do provide clinical guidelines that contribute to implant supported prostheses longevity and stability in patients with bruxism. .

OBJETIVO: Realizar uma revisão sistemática, a fim de reunir informações e discutir a previsibilidade de próteses sobre implantes em pacientes com bruxismo. MÉTODOS: Para a identificação dos estudos dessa revisão, foi realizada uma estratégia de busca detalhada e avançada nos bancos de dados PubMed e Medline. Foram utilizados como descritores: bruxismo, implantes dentários, prótese implantossuportada e falha da restauração dentárial; bruxism, dental implants, implant-supported prosthesis e dental restoration failure. Os critérios de inclusão foram: artigos clínicos, estudos controlados aleatórios, estudos in vitro, revisões de literatura e revisões sistemáticas com e sem meta-análise dos últimos 20 anos que abordassem o tema proposto. Os critérios de exclusão foram: artigos sem resumo, estudos em animais, artigos cujo idioma não fosse o inglês e artigos de periódicos que não pertencessem à área odontológica. RESULTADOS: De um total de 54 artigos, após uma análise segundo o critério de inclusão e exclusão, foram selecionados 28 artigos. É sabido que a quantidade de artigos científicos que avaliaram, seja através de estudos retrospectivos, prospectivos ou experimentais, o impacto biológico e biomecânico do bruxismo em próteses sobre implantes é pequena e pouco tem contribuído para melhor exemplificação e discernimento dos limites protéticos de segurança para o especialista sob um ponto de vista clínico. CONCLUSÃO: Portanto, ainda não há um consenso geral acerca desse assunto, porém, a maioria dos artigos de revisão de literatura fornecem guias de orientação clínica, os quais auxiliam na longevidade e estabilidade de próteses sobre implantes em pacientes com bruxismo. .

Effect of the Parafunctional Occlusal Loading and Crown Height on Stress Distribution

The aim of this study was to assess, by the three-dimensional finite element method, the influence of crown-to-implant ratio and parafunctional occlusal loading on stress distribution in single external hexagon implant-supported prosthesis. Computer-aided design software was used to confection three models. Each model was composed of a block bone and an external hexagon implant (5x10.0 mm) with screw-retained implant prostheses, varying the height crown: 10, 12.5 and 15 mm. Finite element analysis software was used to generate the finite element mesh and to establish the loading and boundary conditions. Normal (200 N axial and 100 N oblique load) and parafunctional forces (1,000 N axial and 500 N oblique load) were applied. The results were visualized by von Mises and maximum principal stress. In comparison with the normal occlusal force, the parafunctional occlusal force induced an increase in stress concentration and magnitude on implant (platform and first threads) and screw (neck). The cortical bone showed the highest tensile stress under parafunctional force (oblique load). The stress concentration increased as the crown height increased. It was concluded that: increasing the C/I increased stress concentration in both implant components and cortical bone; parafunctional loading increased between 4-5 times the value of stresses in bone tissue compared with functional loading; the type of loading variation factor is more influential than the crown-to-implant factor.

O objetivo deste estudo foi avaliar, através do método dos elementos finitos tridimensionais, a influência do carregamento oclusal parafuncional e da altura da coroa na distribuição das tensões em próteses unitárias implantossuportadas de hexágono externo. Foram confeccionados três modelos com o auxílio de programas de desenho assistido. Cada modelo foi composto por um bloco ósseo da região molar mandibular, por um implante de tipo hexágono externo (5x10,0 mm) e por coroa com diferentes alturas: 10, 12,5 e 15 mm. Os modelos foram exportados para o programa de elementos finitos NEiNastran 9.0, para geração das malhas e estabelecer as condições de contorno. Aplicou-se uma carga funcional (200 N axial e 100 N oblíqua), bem como uma carga parafuncional (1.000 N axial e 500 N oblíqua). Os resultados foram visualizados por meio de mapas de Tensão de von Mises e mapas de Tensão Máxima Principal. O carregamento parafuncional induziu um aumento da área de distribuição e da magnitude das tensões no implante (plataforma e primeiras roscas) e parafuso (pescoço) em comparação com o carregamento funcional. A cortical óssea apresentou maiores áreas de tensão por tração sob carregamento parafuncional oblíquo. A concentração de tensões aumentou à medida que aumentou a altura da coroa. O aumento da altura da coroa induziu um aumento na concentração de tensões, tanto nos componentes do implante, quanto na cortical óssea; o carregamento parafuncional induziu um aumento entre 4-5 vezes da magnitude das tensões no tecido ósseo; o tipo de carregamento apresenta-se como um fator de variação mais influente do que a proporção coroa/implante.

Effect of the parafunctional occlusal loading and crown height on stress distribution.

The aim of this study was to assess, by the three-dimensional finite element method, the influence of crown-to-implant ratio and parafunctional occlusal loading on stress distribution in single external hexagon implant-supported prosthesis. Computer-aided design software was used to confection three models. Each model was composed of a block bone and an external hexagon implant (5x10.0 mm) with screw-retained implant prostheses, varying the height crown: 10, 12.5 and 15 mm. Finite element analysis software was used to generate the finite element mesh and to establish the loading and boundary conditions. Normal (200 N axial and 100 N oblique load) and parafunctional forces (1,000 N axial and 500 N oblique load) were applied. The results were visualized by von Mises and maximum principal stress. In comparison with the normal occlusal force, the parafunctional occlusal force induced an increase in stress concentration and magnitude on implant (platform and first threads) and screw (neck). The cortical bone showed the highest tensile stress under parafunctional force (oblique load). The stress concentration increased as the crown height increased. It was concluded that: increasing the C/I increased stress concentration in both implant components and cortical bone; parafunctional loading increased between 4-5 times the value of stresses in bone tissue compared with functional loading; the type of loading variation factor is more influential than the crown-to-implant factor.

Photoelastic analysis of stress distribution with different implant systems.

The aim of this study was to evaluate stress distribution with different implant systems through photoelasticity. Five models were fabricated with photoelastic resin PL-2. Each model was composed of a block of photoelastic resin (10 × 40 × 45 mm) with an implant and a healing abutment: model 1, internal hexagon implant (4.0 × 10 mm; Conect AR, Conexão, São Paulo, Brazil); model 2, Morse taper/internal octagon implant (4.1 × 10 mm; Standard, Straumann ITI, Andover, Mass); model 3, Morse taper implant (4.0 × 10 mm; AR Morse, Conexão); model 4, locking taper implant (4.0 × 11 mm; Bicon, Boston, Mass); model 5, external hexagon implant (4.0 × 10 mm; Master Screw, Conexão). Axial and oblique load (45°) of 150 N were applied by a universal testing machine (EMIC-DL 3000), and a circular polariscope was used to visualize the stress. The results were photographed and analyzed qualitatively using Adobe Photoshop software. For the axial load, the greatest stress concentration was exhibited in the cervical and apical thirds. However, the highest number of isochromatic fringes was observed in the implant apex and in the cervical adjacent to the load direction in all models for the oblique load. Model 2 (Morse taper, internal octagon, Straumann ITI) presented the lowest stress concentration, while model 5 (external hexagon, Master Screw, Conexão) exhibited the greatest stress. It was concluded that Morse taper implants presented a more favorable stress distribution among the test groups. The external hexagon implant showed the highest stress concentration. Oblique load generated the highest stress in all models analyzed.

Efeito do carregamento funcional e parafuncional em próteses unitárias implantossuportadas com diferentes plataformas protéticas: análise 3D por elementos finitos / Effect of functional and parafunctional loading on single-tooth implant-supported prostheses with different prosthetic platforms: a 3-D finite element analysis

Objetivo: analisar a influência do carregamento oclusal parafuncional e da conexão protética na distribuição das tensões no tecido ósseo, utilizando o método de elementos finitos tridimensionais. Material e métodos: cada modelo foi composto por um bloco ósseo da região molar mandibular, com um implante do tipo hexágono externo ou cone-morse (5 mm x 10 mm), e as respectivas coroas metalocerâmicas unitárias parafusadas e cimentadas (altura da coroa: 12,5 mm). A camada de cimento foi construída com 30 μm de espessura. Uma carga funcional (quatro pontos, 200 N axial, 100 N oblíqua) e uma parafuncional (dois pontos, 1.000 N axial, 500 N oblíqua) foram aplicadas, e os resultados visualizados por meio de mapas de von Mises e tensão máxima principal. Resultado: o carregamento parafuncional produziu aumento da concentração e magnitude das tensões, principalmente sob carga oblíqua. A conexão cone-morse proporcionou uma área maior de distribuição de tensões no implante, ao nível da junção implante/parafuso. O parafuso do implante cone-morse apresentou maiores tensões ao nível do pescoço, principalmente no carregamento parafuncional. No osso cortical, as tensões por tração e por compressão localizaram-se ao redor da plataforma e ao nível da primeira rosca do implante em ambos os implantes, e em maior área na conexão externa. Conclusão: 1) Em relação ao osso, o implante cone-morse apresentou a situação biomecânica mais favorável sob ambos os tipos de carregamento e de direção da carga; 2) O carregamento parafuncional induziu ao aumento na magnitude das tensões nas estruturas analisadas.

Influência do aumento do comprimento de implantes dentários / Influence of increasing the length in dental implants

A utilização dos implantes de maior comprimento pode ser mais favorável para a previsibilidade dos implantes dentários. Essa afirmação é pertinente, uma vez que a causa dos fracassos em implantes osseointegrados está mais relacionada às complicações biomecânicas. Assim, o objetivo deste estudo foi avaliar a influência da ampliação do comprimento ao redor da superfície do implante. Seis modelos foram criados com a presença apenas de um implante (Conexão Master Screw, Sistemas de Próteses, São Paulo, Brasil) do tipo hexágono externo de 3.75 mm x 7.0 mm (Modelo A), 3.75 mm x 8,5 mm (Modelo B), 3.75 mm x 10.0 mm (Modelo C), 3.75 mm x 11.5 mm (Modelo D), 3.75 mm x 13 mm (Modelo E), 3.75 mm x 15 mm (Modelo F) utilizando a metodologia de fotoelasticidade. Os resultados foram visualizados através de uma análise qualitativa de tensões (número e intensidade de franjas). O modelo A apresentou um padrão de distribuição de tensões menos favorável; o carregamento oblíquo foi o mais prejudicial para as estruturas relacionadas. Conclusão: O aumento do comprimento permitiu uma melhor distribuição de tensões. O carregamento oblíquo foi o mais prejudicial, quando comparado com o carregamento axial.

The use of implants of greater length may be more favorable for the predictability of dental implants. This statement is relevant, since the cause of failures in dental implants are more related to biomechanical complications. The aim of this study was to evaluate the influence of increase of the length around the entire body of the implant. Six models were created with the presence of only one hexagonal implant (Master Screw connection, Implant Systems, São Paulo, Brazil) of 3.75 mm x 7.0 mm (Model A), 3.75 mm x 8.5 mm (Model B ), 3.75 mm x 10.0 mm (Model C) 3.75 mm x 11.5 mm (Model D) 3.75 mm x 13.0 mm (Model E) 3.75 mm x 15.0 mm (Model F) using the method of photoelasticity. The results were visualized through a qualitative analysis of stresses (number and intensity photoelastic fringes). The model A showed a pattern of less favorable stress distribution, the oblique loading was the most detrimental to the related structures. Conclusion: The increased length allowed for a better distribution of stresses. The oblique loading was more detrimental when compared to axial loading.

Photoelastic analysis of the influence of residual ridge inclination in conjugated class I mandibular prostheses with different attachment systems.

OBJECTIVES: The aim of this study was to evaluate the stress distribution in mandibular free-end removable partial dentures (RPD) associated with FPD in the abutment teeth considering different inclinations of the residual ridge: (1) horizontal and (2) distal descending ridges and two designs of free-end RPD with different attachment systems were tested: (1) clasp and (2) system ERA. METHODS: Axial loads (100 N) were applied on the teeth of the RPD. The images were recorded and the stress distribution was evaluated through photoelastic fringes. RESULTS: In general, the distal descending ridge presented more photoelastic fringes in the region of the roots of the abutment teeth while the horizontal ridge exhibited higher compression in the base of the prosthesis. In the horizontal ridge, the denture with clasp presented more favourable stress distribution than the denture with the system ERA. In the distal descending ridge, the denture with the system ERA relieved the region of the abutment teeth and overloaded the residual ridge. CONCLUSION: The horizontal ridge presented more favourable performance; the dentures with clasp exhibited better performance for both ridges evaluated; the denture with the system ERA presented better results in the distal descending ridge.