The Use of Digital Impressions to Fabricate Tooth-Supported Partial Removable Dental Prostheses: A Clinical Report.

Impression making is a critical step in the fabrication of a partial removable dental prosthesis (RDP). A technique is described for making final impressions to fabricate partial RDPs for Kennedy class III patients using a computer-aided design and computer-assisted manufacturing digital impression system.

Shear resistance of fiber-reinforced composite and metal dentin pins.

PURPOSE: To assess whether dentin pins increase shear resistance of extensive composite restorations and to compare performance of mini fiber-reinforced composite (FRC) anchors with metal dentin pins in the laboratory. METHODS: 30 extracted sound molars were randomly divided into three groups. Occlusal surfaces were ground flat with a standard surface area and resin composite restorations were made in Group A. In Groups B and C similar restorations were made, with additionally four metal pins placed in Group B and four FRC pins in Group C. Specimens were statically loaded until failure occurred. Failure modes were characterized as intact remaining tooth substrate (adhesive or cohesive failure of restoration) or fractured remaining tooth substrate. RESULTS: Mean failure stresses were 6.5 MPa (SD 3.2 MPa) for Group A, 9.7 MPa (SD 2.6 MPa) for Group B and 9.2 MPa (SD 2.6 MPa) for Group C. Difference in mean failure stresses between Group A and Groups B and C was statistically significant (P = 0.01), while the difference between Groups B and C was not (P = 0.63). Failures of the restoration without fracture of tooth substrate were seen for 80% of specimens in Group A and 20% in Groups B and C (P = 0.04).

Effect of home bleaching systems on enamel nanohardness and elastic modulus.

OBJECTIVES: The purpose of this study was to evaluate the nanohardness and elastic modulus of human enamel after treatment with tray and strip bleaching systems. METHODS: Fifty-five human enamel samples were exposed to five different bleaching agents. Nanoindentations were made before and after bleaching treatments following the manufacturer's directions using a Nanoindenter XP (MTS Systems Corporation, Oak Ridge, TN, USA). Nanohardness and elastic modulus measurements were obtained and the results were statistically analyzed using a repeated measures analysis of variance with a post-hoc Tukey-Kramer multiple comparison test. RESULTS: Nanohardness and elastic modulus measurements showed decrease of mean values for each group except the control which remained the same. There were significant differences due to time (before and after treatment) and material effects in nanohardness (P<0.0001) and elastic modulus (P=0.0241). Measurements after treatment showed significant decrease in nanohardness between all groups and the control group. There was a significant difference in hardness between CP and TO after treatment. Additionally, there were significant differences in elastic modulus between the control group when compared to OB and TO after treatment. While there were significant changes in the elastic modulus due to treatment for both CP and TO, there were no significant differences between any of the groups after treatment. CONCLUSIONS: Nanohardness and elastic modulus of human enamel were significantly decreased after the application of home-bleaching systems.

Palatal mini-implants to increase retention and stability of implant-retained maxillary overdentures: a case report.

Maxillary edentulous patients have been successfully treated with implant-supported fixed and removable dental prostheses. The fixed implant-supported dental prosthesis has been used for >20 years. It has lost popularity because the design of this restoration requires special access for oral hygiene around the abutment cylinders creating an esthetic quandary in the maxilla. The use of the mid-sagital palatal suture to osseointegrate anchorage devices for orthodontic purposes has shown satisfactory results. This clinical case documents the successful use of mid-palatal implants as an extension of orthodontic anchorage to gain accessory support and retention for a maxillary complete removable dental prosthesis.

Comparative study of the transverse strength of three denture base materials.

OBJECTIVES: Fracture resistance of recently introduced denture base resins has not been compared to traditional denture base materials. This study compared the transverse strength of three denture base materials, namely, Lucitone 199, Triad VLC, and the newly introduced Eclipse. MATERIALS AND METHODS: A total of 30 specimens (50mmx25mmx2.5mm) were fabricated, 10 from each material. The specimens were loaded until failure on an Instron universal testing machine using a three point flexural test. One-way analysis of variance (ANOVA) was used to compare the mean transverse strength between the three materials tested. RESULTS: The transverse strength values showed significant differences between the three denture base materials (P<0.0001). The mean transverse strength and standard deviations (MPa) were as follows: Eclipse 116.13+/-17.7, Lucitone 87.12+/-8.1, and Triad VLC 57.96+/-7.3. CONCLUSIONS: Within the limitations of this study, Eclipse showed the highest transverse strength among the materials tested. Eclipse denture base material may provide a stronger alternative to traditional denture base resins.

Shear bond strength of the amalgam-resin composite interface.

OBJECTIVE: This study compared the initial and one year shear bond strengths (SBS) of resin composite bonded to amalgam using Amalgambond-Plus. METHODS: Resin composite cylinders (Point 4, Kerr Corporation) were bonded to either etched-enamel (A), 50% etched enamel-50% polished amalgam (B), airborne-particle abraded amalgam (C), carbide bur prepared amalgam (D) and airborne-particle abraded 50% amalgam-50% etched-enamel (E). Shear bond strengths were determined using a standardized testing device (Ultradent Products) in a universal testing machine (Instron model 4204). The failed interfaces were evaluated with SEM to obtain visual evidence of the failure mode. RESULTS: ANOVA indicated significant differences among the groups (p < 0.0001). SBS in MPa (Mean/SD) were for A at year 0: (24.63/4.19), A at year 1: (16.84/7.25), B at year 0: (9.13/2.18), B at year 1: (15.54/6.41), C at year 0: (16.82/3.60), C at year 1: (15.26/3.90), D at year 0: (9.27/4.03), D at year 1: (7.97/7.17), E at year 0: (16.67/4.87) and E at year 1: (8.63/3.64). CONCLUSION: In vitro testing demonstrated that resin composite masking has the strongest, most durable SBS on airborne-particle abraded amalgam and airborne-particle abraded enamel-amalgam surfaces and could be used as a method to improve the esthetics of amalgam restorations.

Tendencias y principios en las corrientes bioéticas

Propósito/Contexto. Este artículo es producto de una investigación que buscó establecer cuáles son los principios bioéticos más tratados, estudiados y discutidos en las corrientes médica, clínica, laica, cardinal, principialista, personalista, realista, europea y latinoamericana, buscando determinar las principales tendencias en el periodo comprendido entre 1970 y 2018. Metodología/Enfoque. Se construyó una matriz como instrumento de registro y categorización para un estudio cualitativo, con enfoque descriptivo y de tipo documental, y de método deductivo lógico. Así se efectuó una selección y descripción de las corrientes bioéticas a las cuales pertenecen cada uno de los principios abordados. A partir de esto se hizo un seguimiento descriptivo del estatus de los principios, para encontrar vacíos de conocimiento y para generar condiciones óptimas que susciten debates de orientación interdisciplinar y transdisciplinar. Resultados/Hallazgos. La conjunción de los hallazgos permitió identificar catorce principios bioéticos en las corrientes y tendencias predominantes, reconociendo a su vez el origen y la definición de los mismos, y estableciendo relaciones entre autores de diferentes nacionalidades y distintas corrientes bioéticas. Discusiones/Conclusiones/Contribuciones. Se detectaron catorce principios bioéticos predominantes en un periodo cuarenta y ocho años: autonomía, beneficencia, no maleficencia, justicia, información, dignidad, integridad, vulnerabilidad, respeto por la vida, individualidad, universalidad, conservación, realización, propiedad. Cada uno de estos principios se asoció a un instrumento internacional y a una corriente bioética, observando un pluriprincipialismo y una orientación hacia las tendencias de bioeticistas europeos y estadounidenses.

Purpose/Context. This article seeks to determine the most covered, studied, and discussed bioethical principles in the medical, clinical, secular, cardinal, principlist, personalist, realist, European, and Latin American currents and identify the main trends between 1970 and 2018. Methodology/Approach. We built a matrix as a recording and categorization instrument for a qualitative study with a descriptive and documentary approach and a deductive method. Thus, we selected and outlined the bioethical currents of the principles addressed with a descriptive follow-up of their status to find knowledge gaps and create optimal conditions for inter- and transdisciplinary debates. Results/Findings. The conjunction of findings allowed identifying fourteen bioethical principles in the predominant currents and tendencies, recognizing their origin and definition, and establishing relationships between authors of different nationalities and bioethical currents. Discussions/Conclusions/Contributions. We detected fourteen prevailing bioethical principles in forty-eight years: autonomy, beneficence, non-maleficence, justice, information, dignity, integrity, vulnerability, respect for life, individuality, universality, conservation, realization, property. Each principle was associated with an international instrument and a bioethical current, noting pluriprinciplism and orientation towards European and American bioethicists' trends.

Objetivo/contexto. Este artigo procura estabelecer quais são os princípios bioéticos mais tratados, estudados e discutidos nas correntes médica, clínica, leiga, cardinal, principialista, personalista, realista, europeia e latino-americana, além de identificar as principais tendências no período compreendido entre 1970 e 2018. Metodologia/Abordagem. Construiu-se uma matriz como instrumento de registro e categorização para um estudo qualitativo, com abordagem descritivo e de tipo documental, e de método dedutivo lógico. Assim se efetuou uma seleção e descrição das correntes bioéticas às quais pertencem cada um dos princípios abordados. A partir disso, fez-se um seguimento descritivo do status dos princípios, para encontrar lacunas de conhecimento e para gerar condições ótimas que suscitem debates de orientação interdisciplinar e transdisciplinar. Resultados/Descobertas. A conjunção das descobertas permitiu identificar catorze princípios bioéticos nas correntes e tendências predominantes, reconhecendo por sua vez a origem e a definição dos mesmos, estabelecendo relações entre autores de diferentes nacionalidades e diferentes correntes bioéticas. Discussões/Conclusões/Contribuições. Foram detectados catorze princípios bioéticos predominantes num período de quarenta e oito anos: autonomia, beneficência, não maleficência, justiça, informação, dignidade, integridade, vulnerabilidade, respeito pela vida, individualidade, universalidade, conservação, realização, propriedade. Cada um destes princípios se associou a um instrumento internacional e a uma corrente bioética, observando um pluriprincipialismo e uma orientação para as tendências de bioeticistas europeus e dos EUA.

Human enamel nanohardness, elastic modulus and surface integrity after beverage contact.

This study evaluated nanohardness, elastic modulus and surface roughness of human enamel after contact with citric beverages. Human enamel samples were assigned to 3 groups according to the type of beverage used: carbonated drink, orange juice and tap water (control). Surface roughness was assessed using a profilometer, and nanohardness and elastic modulus were recorded using a nanoindenter. The pH of the beverages was measured before and after citric contact during 5 weeks. Means(SD) were as follows: Carbonated drink: elastic modulus decreased from 111.6(14.5) to 62.3(10.3) GPa, nanohardness decreased from 4.62(0.67) to 1.28(0.46) GPa, roughness increased from 5.30(2.39) to 6.86(2.56) microm, and the pH changed from 2.69(0.35) to 2.29(0.24); Orange juice: elastic modulus changed from 115.15(12.94) to 92.11 GPa (13.83), nanohardness from 5.54(1.48) to 3.18 GPa (0.64), roughness from 5.26(2.27) to 6.73(2.25) microm, and pH from 3.46(0.20) to 3.03(0.14); Tap water (control): elastic modulus changed from 117.87(22.3) to 107.91(20.05) GPa, nanohardness from 4.35(1.66) to 4.28(0.93) GPa, roughness from 5.76(3.11) to 6.11(2.65) microm, and pH from 7.97(0.28) to 8.11(0.21). In conclusion, soft drink exposure caused a significant decrease in nanohardness and elastic modulus. The pH of the soft drink was more acidic from 5 degrees C to 37 degrees C. Orange juice showed a similar trend but, surprisingly, it had less effect on hardness, elastic modulus and roughness of enamel than the carbonated drink.

Mechanical wear behavior of nanocrystalline and multilayer diamond coatings on temporomandibular joint implants.

We used microwave plasma chemical vapor deposition to deposit nanocrystalline and multilayer (nanocrystalline/microcrystalline/nanocrystalline) diamond thin films on Ti-6AI-4V substrates imitating the condyle and fossa components of the temporomandibular joint. We tested the condyle/fossa pairs for wear in a mandibular movement simulator for an equivalent of two years of clinical use. Analysis of the wear surfaces by optical microscopy, scanning electron microscopy (SEM), and Raman spectroscopy showed that damage in both the films was minimal, no loss of film occurred and the wear performance was superior for the multilayer film. Comparisons with an uncoated condyle/fossa pair showed that the coated temporomandibular joint pairs had improved wear performance.

Human enamel nanohardness, elastic modulus and surface integrity after beverage contact

This study evaluated nanohardness, elastic modulus and surface roughness of human enamel after contact with citric beverages. Human enamel samples were assigned to 3 groups according to the type of beverage used: carbonated drink, orange juice and tap water (control). Surface roughness was assessed using a profilometer, and nanohardness and elastic modulus were recorded using a nanoindenter. The pH of the beverages was measured before and after citric contact during 5 weeks. Means(SD) were as follows: Carbonated drink: elastic modulus decreased from 111.6(14.5) to 62.3(10.3) GPa, nanohardness decreased from 4.62(0.67) to 1.28(0.46) GPa, roughness increased from 5.30(2.39) to 6.86(2.56) mum, and the pH changed from 2.69(0.35) to 2.29(0.24); Orange juice: elastic modulus changed from 115.15(12.94) to 92.11 GPa (13.83), nanohardness from 5.54(1.48) to 3.18 GPa (0.64), roughness from 5.26(2.27) to 6.73(2.25) mum, and pH from 3.46(0.20) to 3.03(0.14); Tap water (control): elastic modulus changed from 117.87(22.3) to 107.91(20.05) GPa, nanohardness from 4.35(1.66) to 4.28(0.93) GPa, roughness from 5.76(3.11) to 6.11(2.65) mum, and pH from 7.97(0.28) to 8.11(0.21). In conclusion, soft drink exposure caused a significant decrease in nanohardness and elastic modulus. The pH of the soft drink was more acidic from 5ºC to 37ºC. Orange juice showed a similar trend but, surprisingly, it had less effect on hardness, elastic modulus and roughness of enamel than the carbonated drink.

Este estudo avaliou a nanodureza, módulo de elasticidade e rugosidade de superfície do esmalte humano após contato com bebidas ácidas. Amostras de esmalte humano foram divididas em três grupos de acordo com o tipo de bebida utilizada: refrigerante gaseificado, suco de laranja e água potável (controle). A rugosidade de superfície foi avaliada usando-se um perfilômetro e a nanodureza/módulo de elasticidade utilizando-se um nanoindentador. O pH das bebidas foi medido antes e após a exposição das amostras por 5 semanas. Os valores médios (DP) foram: Refrigerante Gaseificado: o módulo de elasticidade diminuiu de 111,6(14,5) para 62,3(10,3) GPa; a nanodureza diminuiu de 4,62(0,67) para 1,28(0,46) GPa, a rugosidade de superfície aumentou de 5,30(2,39) para 6,86(2,56) mim, e o pH sofreu uma alteração de 2,69(0,35) para 2,29(0,24); Suco de Laranja: módulo de elasticidade sofreu alteração de 115,15(12,94) para 92,11(13,82) GPa; a nanodureza de 5,54(1,48) para 3,18(0,64) GPa, a rugosidade de superfície de 5,26(2,27) para 6,73(2,25) mim, e o pH sofreu uma alteração de 3,46(0,20) para 3,03(0,14); Água Potável (Controle): módulo de elasticidade sofreu alteração de 117,87(22,3) para 107,91(20,05) GPa; a nanodureza de 4,35(1,66) para 4,28(0,93) GPa, a rugosidade de superfície de 5,76(3,11) para 6,11(2,65) mim, e o pH de 7,97(0,28) para 8,11(0,21). Como conclusão, a exposição ao refrigerante provocou uma diminuição significante na nanodureza e no módulo de elasticidade do esmalte. O pH do refrigerante foi o mais ácido entre 5ºC e 37ºC. A exposição ao suco de laranja mostrou uma tendência similar, contudo o seu efeito sobre a nanodureza, módulo de elasticidade e rugosidade de superfície foi menos pronunciado.

Estudio comparativo de capacidad retentiva de medios de cementación temporal al ser utilizados en restauraciones provisionales de preparaciones para corona completa / Comparative study of retentive capacity of two temporary cements used for luting provisionals on complete crown preparations

Fallas en el medio cementante son la causa más común de la descementación de coronas provisionales. Objetivos: Comparar la capacidad retentiva de dos medios de cementación temporal para provisionales, un material con base en óxido de zinc y otro conbase en hidróxido de calcio. Métodos: Se utilizaron 20 terceros molares humanos sanos recientemente extraídos. Se realizaron preparaciones para corona completa metal porcelana. El grado de convergencia y la altura de las preparaciones fueron estandarizados. Se elaboraron coronas provisionales asegurando buena adaptación marginal, pulimento y brillado. El grupo A secementó utilizando un material con base en hidróxido de calcio (Life® Kerr Corporation, Orange CA, USA) y el grupo B se cementó con un material con base en óxido de zinc (TempBond Clear® Kerr Corporation, Orange CA, USA). La fuerza de cementación fue de 2.5 Kg/5 minutos. Se realizó la prueba de resistencia al desalojo con la máquina universal de pruebas (Instron®modelo 4204 Canton, MA, USA). Para la descementación se utilizó una velocidad de funcionamiento de 0.5 milímetros porminuto. Resultados: Las fuerzas promedio de desalojo fueron 47.8N para el grupo A y 21.1N para el grupo B. El Análisis Welch de ANOVA mostró diferencias estadísticamente significativas (P<0.001) en la capacidad retentiva entre los dos grupos. Losresultados de altura y grados de convergencia de las preparaciones no tuvieron diferencias significativas. Conclusiones: El material con base en hidróxido de calcio mostró mejor capacidad retentiva que el material con base en óxido de zinc.

Desarrollo de un simulador de movimientos mandibulares para pruebas de resistencia abrasiva de biomateriales / Development of a mandibular movement simulator for wear testing of biomaterials

El objetivo de este estudio fue diseñar y elaborar un Simulador de Movimientos Mandibulares (SMM) que pudiera reproducir enforma precisa los movimientos y fuerzas mandibulares de la Articulación Temporo-Mandibular (ATM) y de la mandíbula. Uncráneo humano de características antropométricas normales se duplicó en fibra de vidrio, con arcos dentales metálicos colados(Aleación de Ni-Cr), con cavidades oclusales previamente preparadas en premolares y molares. La simulación del ligamentoperiodontal se hizo con polivinilsiloxano liviano y la del disco articular con silicona. Se replicaron los movimientos de la ATM yla mandíbula con servomotores de tecnología de robótica: Apertura (45mm), cierre, lateralidad (5mm) y protrusiva (5mm), confuerzas masticatorias promedio de 200 Newtons. Se desarrolló un programa computarizado que simula los movimientosmandibulares en 12 ciclos diferentes, cada ciclo se repitió aproximadamente 4,000 veces durante las pruebas.Este estudio desarrolló una herramienta de investigación de características más reales para realizar estudios de desgaste demateriales dentales en el laboratorio.

The purpose of this study was to design and fabricate a mandibular movement simulator (MMS) that can closely reproduce themovements of the human temporomandibular joint and (TMJ) and the mandible. A human skull was duplicated in fiberglass withcast metallic teeth (Ni-Cr alloy) with occlusal cavities in premolars and molars. Light polyvinyl siloxane was used to simulate theperiodontal ligament and Medigel-Z® to simulate the TMJ disc. The TMJ and mandibular movements were simulated withrobotic technology and servomotors: Opening (45mm), closure, lateral (5 mm) and protrusive (5 mm) with an average chewingforces of 200 Newtons. Computer software was developed to simulate mandibular movements in 12 different cycles; each cyclewas typically repeated more than 4,000 times during testing. This study developed a research tool with more realistic features toperform wear test in the laboratory.

Evaluación del tratamiento no invasivo de apnea obstructiva del sueño con placas de avance mandibular con espacio interincisal / Evaluation of the noninvasive treatment for obstructive sleep apnea by mandibular advance plates with interincisal space

El propósito de este estudio es evaluar los efectos terapéuticos de placas de avance mandibular con espacio intericisal en pacientes con diagnóstico de Apnea Obstructiva del Sueño (A.O.S). Para llevar a cabo esta investigación se seleccionaron 20 pacientes (15 hombres, 5 mujeres) a los cuales se les realizó un estudio polisomnográfico previo a la terapia, confirmando así el diagnótico de Apnea Obstructiva del Sueño. Posteriormente se colocaron las placas de avance mandibular con espacio interincisal y se requirió de un periódo de un mes para habituar al paciente y luego evaluar su efectividad mediante la realización de otro estudio polisomnográfico postratamiento. Se valoró el índice de Apnea e hipopnea, saturación de oxígeno, la somnolencia, el ronquido y la cefalea. Los resultados mostraron que se presentó mejoría en el ronquido y diferencias estadísticamente significativas en cuanto al índice de somnolencia, apnea e hipopnea; mientras que no se evidenciaron cambios estadísticamente significativos en la saturación del oxigeno. Se concluyó que los pacientes con (A.O.S) presentan óptimas respuestas ante el tratamiento con placas de avance mandibular en sus signos y síntomas.

Cambio dimensional, de un hidrocoloide irreversible después de la desinfección de las impresiones con dos marcas comerciales de un glutaraldehido al 2 e hipoclorito de sodio al 0.525 / Dimensional change of irreversible hydrocoloids after impression desinfection with two commercial marks of a glutaldehyde to the 2 per cent and sodium hypochlorite to the 0.525 per cent

El propósito de este estudio fue evaluar los cambios dimensionales ocurridos en modelos de yeso, obtenidos de impresiones con Hidrocoloide irreversible (Kromopan) después de un proceso de desinfección con dos marcas comerciales de glutaraldehído al 2 e hipoclorito de sodio al 0.525 por un tiempo de 10 minutos en inmersión. Se utilizó un grupo control y tres de estudio. Las impresiones se lavaron con agua potable por 10 segundos después de la toma de impresión del modelo maestro y las impresiones de los grupos de estudio fueron llevadas al desinfectante correspondiente por 10 minutos que fueron lavadas nuevamente por 10 segundos. Posteriormente se realizaron los vaciados con yeso tipo III Quik Stone de la casa Whip Mix, con eyuda de un vibrador. Los cambios dimensionales se evaluaron en sentido transversal (A-B), antero posterior (A-C), diagonal (A-D), y de profundidad (E-F) con un calibrador digital de 0.01mm y un micrómetro de profundidad de 0.1mm de precesión (mitutoyo) por una persona con experiencia en esta área. Los resultados se evaluaron mediante el análisis de varianza de una sola vía (ANOVA), se realizó una comparación entre los promedios de los grupos de Glutaraldehido al 2 y el grupo control, según el método de "Boferroni" se demostró que no había cambios dimensionales significativos al utilizar Glutaraldehido al 2 en las impresiones dentales, comparandolas con el grupo control. Al igual que no existen diferencias significativas entre el Vides "y el Microcide GL", en cuanto a cambios dimensionales en el hodrocoloide irreversilble (Kromopan), a diferencia con el Hipoclorito de Sodio que se comparó con el grupo control por medio del test student que evidenció que hay cambios dimensionales significativos.

Estudio de la confiabilidad de un registrador extraoral de los movimientos mandibulares en apertura y cierre en un plano frontal / Studies of the reliability of an extra oral register of the mandibular movements in opening and closes in frontal plane

El análisis de las trayectorias de aperturas y cierre y los movimientos mandibulares que las acompañan ha sido descrito y analizado en estudios anteriores en los cuales se han diseñado aparatos que registran dichos movimientos en el plano frontal, pero estos prototipos de aparatos no demostraron ser totalmente confiables ni exactos. Para este estudio se diseño un aparato en aluminio totalmente ajustable. Este aparato consta de un componente extraoral que parte de la importancia de los puntos de apoyo en nasin y contraapoyos localizados en el rea occipital; y un componente extraoral que se ajusta al segmento inferior que por medio de un elaborado sistema de resorte permite que una aguja inscriptora de proximadamente 0.002mm de grosor, transcriba los trozos a un papel de copia fijado en una pantalla inscriptora, que a su vez se encuentralocalizada en la parte anterior del componente extraoral. Con el fin de determinar la confiabilidad del aparato registrador, se seleccionaron 30 pacientes al azar y a cada uno de ellos se le tomaron tres muestras, una cada día, durante tres días seguidos y aproximadamente a la misma hora. Se le pidió a cada paciente que realizara un movimiento en máxima intercuspidación. Los resultados se evaluaron mediante una técnica, que permita evaluar la confiabilidad de mediadas repetidas, conocida como ANOVA simple o de una via.