Impact of different scan strategies and implant angulation on impression accuracy of full arch multiple implant: an in vitro study / Impacto de diferentes estratégias de escaneamento e angulação dos implantes na acurácia da moldagem de implantes múltiplos em arco completo: um estudo in vitro

Objective: to evaluate the impact of three different scan strategies and implant angulation on impression accuracy of an intraoral scanner for full-arch multiple implant scan. Material and Method: A maxillary edentulous model with six implant analogs served as a reference model. The four anterior analogs were positioned parallel to each other, the distal right and the distal left was placed with an angulation of 15o and 20o, respectively. Thirty impression were performed using an intraoral scanner (CEREC Primescan). The master cast was digitalized with an industrial reference scanner (ATOS Core 80). All scans were converted to standard tessellation language (STL), superimposed on the reference scan with a 3d inspection software (GOM Inspect Professional 2019) and then analyzed. Results: All linear distances presented equivalence [p<0.01] to those found on the reference scan for all scan strategies. All scan strategies presented a tendency of negative means for linear distances except for d4 in strategy C. All angular distances did not present equivalence [p=0.05] to those found on the reference scan. Significant 3D deviations [p<0.05] were found between strategy B (0.02 ± 0.01) and C (0.05 ± 0.04) for d1. In all others linear and angular distances no statistically significant difference was found between strategies A, B and C. Conclusions: There was no statistically significant difference between strategies A, B and C except for d1 in strategy B and C; Implant angulation did not affect the accuracy of the CEREC Primescan IOS (AU)

Objetivo: avaliar o impacto de três diferentes estratégias de escaneamento e angulação do implante na acurácia da moldagem de um scanner intraoral na moldagem de múltiplos implantes em arco completo. Material e Métodos: Um modelo edêntulo de maxila contendo seis análogos de implante serviu como modelo de referência. Os quatro análogos anteriores foram posicionados paralelos entre si, o distal direito e o distal esquerdo foram posicionados com angulação de 15o e 20o, respectivamente. Trinta moldagens foram realizadas usando um scanner intraoral (CEREC Primescan). O modelo mestre foi digitalizado com um scanner de referência industrial (ATOS Core 80). Todas as escaneamentos foram convertidas para a linguagem de mosaico padrão (STL), sobrepostas ao escaneamento de referência com um software de inspeção 3D (GOM Inspect Professional 2019) e, em seguida, analisadas. Resultados: Todas as distâncias lineares apresentaram equivalência [p <0,01] àquelas encontradas na escaneamento de referência para todas as estratégias. Todas as estratégias de escaneamento apresentaram tendência de médias negativas para distâncias lineares, exceto para d4 na estratégia C. Todas as distâncias angulares não apresentaram equivalência [p = 0,05] às encontradas no escaneamento de referência. Desvios 3D significativos [p <0,05] foram encontrados entre a estratégia B (0,02 ± 0,01) e C (0,05 ± 0,04) para d1. Em todas as outras distâncias lineares e angulares, nenhuma diferença estatisticamente significativa foi encontrada entre as estratégias A, B e C. Conclusões: Não houve diferença estatisticamente significante entre as estratégias A, B e C, exceto para d1 na estratégia B e C; A angulação do implante não afetou a precisão do CEREC Primescan. (AU)

Analysis of behavior of the wear coefficient in different layers of acrylic resin teeth.

STATEMENT OF PROBLEM: Analysis of the wear coefficient (k) of the superficial and deep layers of acrylic resin teeth can help predict denture durability, but little has been published on the wear coefficient of denture teeth. PURPOSE: The purpose of this in vitro study was to determine the k value for the superficial and deep layers of the acrylic resin teeth of 6 different brands by using the fixed-ball microabrasive wear method. MATERIAL AND METHODS: Six artificial tooth specimens of 4 commercial brands were tested: Artiplus IPN (Ar), Biotone IPN (Bi), Magister (Ma), Premium (Pr), Trilux (Tr), and SR Vivodent (Vi). Two specimens from each brand were created, one for the superficial layer and the other for the deep layer. The test was performed on fixed-ball microabrasive wear equipment set to operate at a constant normal force of 0.5 N and a rotation speed of 100 rpm. The test time periods were 5.00, 8.33, and 11.66 minutes. The characteristics of the wear craters were measured by using an optical microscope at a magnification of ×50 and Leica Microsystems software. Wear coefficient (k) values were deduced by using the Archard equation for abrasive wear, Q=k·N, and were analyzed by using 1-way analysis of variance, complemented by the Tukey HSD test (α=.05). A different analysis was used for each layer. RESULTS: The analysis of variance of the wear coefficient revealed significant differences among the groups regarding the superficial layers (P=.009). The Tukey HSD test showed that the k values for the superficial layers of Artiplus specimens were significantly lower than those of the Vivodent and Magister specimens. CONCLUSIONS: One brand (Ar) presented significantly lower wear coefficient value for the surface layer. No difference in wear coefficient values was found among the tooth brands for the deep layer.

A 5-week Non-Surgical Approach towards Denture Induced Hyperplasia.

BACKGROUND: Despite the standard approach towards denture-induced hyperplasia being surgery, as elderly population increases the systemic problems are carried along. Thus, surgery might be risky for patients with medical conditions. OBJECTIVE: In this report, a patient with severe inflammatory papillary hyperplasia, medical problems and dental fear was treated with a 5-week nonsurgical protocol. METHOD: Once in a week, the upper denture was relined with a zinc enolic paste, for four weeks. In the fifth week, the denture was relined with fast set polymethyl methacrylate resin instead of zinc enolic paste so that the material would last longer than only a week until the new pair of dentures was manufactured. RESULTS AND CONCLUSION: The generated pressure combined with antioxidant and anti-inflammatory properties of the paste led to the elimination of the inflammatory papillary hyperplasia completely, satisfying the patient and allowing the manufacturing of a new set of complete dentures.

In Vivo Comparison of the Masticatory Efficiency of Artificial Teeth with Two Different Cusp Heights in Complete Dentures: A Preliminary Study.

PURPOSE: The goal of complete denture rehabilitation is to restore facial esthetics and masticatory function to edentulous patients. Several types of artificial teeth with different occlusal anatomy are available. Theoretically, teeth with a higher cusp height provide improved masticatory efficiency. The aim of this study was to compare the masticatory efficiency of complete denture wearers using artificial teeth with two cusp heights. MATERIALS AND METHODS: Sixteen complete denture wearers were given complete dentures with Heraeus Premium teeth. Fifteen days after denture installation, a first masticatory efficiency test was performed with Optocal. A new pair of complete dentures with Dentsply Biotone teeth was then given to each participant to replace the first set. This second set was fabricated by duplicating the same models used to fabricate the first set of dentures. Fifteen days after installation of the dentures with Biotone teeth, a second masticatory efficiency test was performed with Optocal. On both tests, the comminuted material was treated and sieved through a stack of sieves under vibration. The content of each sieve was weighed, and the obtained data were tabulated. Statistical analysis was performed using the Kolmogorov-Smirnov and Wilcoxon tests. RESULTS: Mean and standard deviation of participants' masticatory efficiency, as measured by X50 particle size (mm), were 8.39 and 5.59 for dentures with Premium teeth, and 8.56 and 5.84 for dentures with Biotone teeth. CONCLUSION: According to the results, there were no differences (p < 0.05) in the masticatory efficiency of the complete denture sets using teeth with the two cusp heights.

Different Occlusal Schemes in a Persistent Protruding Complete Denture Wearer.

Different types of artificial teeth and occlusal designs can be used in complete dentures. Bilateral balanced occlusion, lingualized occlusion, canine guidance, and monoplane are the main occlusal designs; however there is no agreement on which tooth arrangement is ideal for achieving success in complete dentures. This report presents an alternative for persistent involuntary protruding complete denture wearers through the use of artificial teeth with higher cusps. Due to an old and worn pair of complete dentures, the patient had the habit of protruding. New dentures were made with Biotone artificial teeth and in the trial session, the patient would still protrude. A new set was made with Premium artificial teeth, which present higher cusps. With these dentures, the involuntary protrusion did not occur. From the delivery to the follow-up sessions, the patient stopped protruding.

Impacto de uma experiência extensionista na formação universitária / Impact of an extension experience in university education

Este estudo teve como objetivo analisar o impacto do projeto de extensão universitária, Resgatando Sorrisos, na formação de estudantes do curso de Odontologia da FOP - UPE, nos anos de 2013 e 2014. Foram utilizados 02 questionários em momentos distintos, tendo como amostra 71 alunos. Foi utilizado o teste de hipótese estatística Wilcoxon para comparar as respostas de antes e depois da ação. Diante da elevada frequência de respostas, como "muitíssimo" e "bastante", observamos um alto grau de aceitação e entendimento da importância do projeto na formação do aluno, assim como no que se refere à capacidade de mudança que o projeto pode causar na vida dos pacientes e sua possível aplicabilidade no sistema público de saúde, dentre outras questões. Contudo, observa-se no ano de 2014 em quesito referente ao grau de expectativa inicial e satisfação final do projeto, uma diferença estatística entre a ida e a volta, p=o,o1. Conclui-se que os alunos apresentam um entendimento positivo em relação à ação extensionista, considerando-a importante para sua formação profissional e pessoal... (AU)

The aim of this study was to analyze the impact of the University Extension Project, ResgatandoSorrisos, in the graduation process of students of Dentistry course FOP - UPE in the years of 2013 and 2014. There were 02 questionnaires used, at different times, with a sample size 71 students. Wilcoxon statistical hypothesis test was used to compare responses before and after the action. Such high frequency responses of "vital" and "enough", a high degree of acceptance and understanding of the importance of the project in the formation of the student was observed, as well as the capacity of a change that the project may cause in the lives of patients and its possible applicability in the public health system, among other issues. However, in 2014, there was a statistical difference between the outward and return (p = o, o1) in a question referring to initial degree of expectation and ultimate satisfaction of the project. It was concluded that students have a positive understanding about the extension action, and they consider it important for their professional and personal training... (AU)

Use of Silver Nanoparticles Reduces Internal Contamination of External Hexagon Implants by Candida albicans.

Since the dental implant/abutment interface cannot totally seal the passage of microorganisms, the interior of implant becomes a reservoir of pathogenic microorganisms that produce and maintain chronic inflammation in the tissues around implants. Silver nanoparticles (nano-Ag) are potent and broad-spectrum antimicrobial agents. The aim of this study was to evaluate the capacity of the nano-Ag to prevent the contamination of the implant internal surface by Candida albicans, caused by the implant/abutment microgap infiltration. Thirty-six implants were used in this experiment. Three study groups were performed: experimental group (implants receiving an application of nano-Ag in their inner cavity before installation of the abutment); positive-control group (implants receiving sterile phosphate buffer saline application instead of nano-Ag) and negative-control group (implants receiving the application of nano-Ag in the inner cavity and immersed in a sterile medium). In the positive-control and experimental groups, the implants were immersed in a Candida albicans suspension. The abutments of all three groups were screwed with a 10 N torque. After 72 h of immersion inC. albicans suspension or sterile medium, the abutments were removed and the inner surface of the implants was sampled with absorbent paper cone for fungal detection. No C. albicans contamination was observed in the negative-control group. The positive-control group showed statistically higher values of colony forming units (CFUs) of C. albicans compared with the experimental group. In conclusion, silver nanoparticles reduced C. albicans colonization inside the implants, even with low torque screw abutment.

Use of Silver Nanoparticles Reduces Internal Contamination of External Hexagon Implants by Candida albicans

Abstract: Since the dental implant/abutment interface cannot totally seal the passage of microorganisms, the interior of implant becomes a reservoir of pathogenic microorganisms that produce and maintain chronic inflammation in the tissues around implants. Silver nanoparticles (nano-Ag) are potent and broad-spectrum antimicrobial agents. The aim of this study was to evaluate the capacity of the nano-Ag to prevent the contamination of the implant internal surface byCandida albicans, caused by the implant/abutment microgap infiltration. Thirty-six implants were used in this experiment. Three study groups were performed: experimental group (implants receiving an application of nano-Ag in their inner cavity before installation of the abutment); positive-control group (implants receiving sterile phosphate buffer saline application instead of nano-Ag) and negative-control group (implants receiving the application of nano-Ag in the inner cavity and immersed in a sterile medium). In the positive-control and experimental groups, the implants were immersed in a Candida albicans suspension. The abutments of all three groups were screwed with a 10 N torque. After 72 h of immersion inC. albicans suspension or sterile medium, the abutments were removed and the inner surface of the implants was sampled with absorbent paper cone for fungal detection. No C. albicans contamination was observed in the negative-control group. The positive-control group showed statistically higher values of colony forming units (CFUs) of C. albicans compared with the experimental group. In conclusion, silver nanoparticles reduced C. albicans colonization inside the implants, even with low torque screw abutment.

Resumo: A interface implante/pilar não pode ser totalmente selada para passagem de microrganismos, com isso o interior do implante torna-se um reservatório de microrganismos patogênicos que promovem e mantêm a inflamação crônica nos tecidos em volta dos implantes. Nanopartículas de prata são agentes antimicrobianos potentes e de amplo espectro. O objetivo deste estudo foi avaliar a capacidade das nanopartículas de prata em evitar a contaminação porCandida albicans do interior de implantes, originada da infiltração do fungo através da interface implante/pilar. 36 implantes foram utilizados neste experimento. Três grupos de estudo foram estabelecidos: grupo experimental (os implantes receberam aplicação de nanopartículas de prata na sua cavidade interna, antes da instalação do pilar); grupo controle positivo (os implantes receberam PBS estéril em vez das nanopartículas de prata) e grupo controle negativo (implantes receberam aplicação de nanopartículas de prata na cavidade interna, mas os implantes foram imersos em meio estéril). Nos grupos controle positivo e experimental, os implantes foram imersos em suspensão deCandida albicans. Os pilares protéticos de todos os grupos foram parafusados com torque de 10 N. Após 72 h imersos na suspensão deC. albicans ou em meio estéril, os pilares foram removidos e amostras da superfície interna dos implantes foram coletadas com cone de papel absorvente para a detecção de Candida. No grupo controle negativo não foi observada contaminação por C. albicans. O grupo-controle positivo mostrou valores de unidades formadoras de colônia deCandida estatisticamente maiores quando comparado com o grupo experimental. Conclui-se que nanopartículas de prata reduzem a colonização de C. albicans dentro dos implantes, mesmo quando o pilar é parafusado com torque baixo.

Análise do eixo vertical de rotação da mandíbula nos movimentos de lateralidade / Mandible vertical rotation axis analysis on lateral movements

A busca pelo esclarecimento da mecânica dos eixos dos movimentos mandibulares estimulam o emprego de diversas metodologias para se observar a dinâmica das articulações temporomandibulares. O entendimento desse funcionamento, a possibilidade de registros precisos e sua reprodutibilidade correta fascinam os militantes da área de Prótese Dentária que buscam métodos de simulação precisos dos movimentos mandibulares de interesse protético. Neste trabalho, utiliza-se uma metodologia inédita com uso de imagens e inferências aplicadas, com o propósito de analisar o posicionamento do eixo vertical de rotação da mandíbula durante os movimentos de lateralidade de Bennett e de lateralidade a partir da Posição de Ocíusão Central em pacientes portadores de próteses totais. Vinte e dois indivíduos foram reabilitados com novas próteses totais e os seus registros maxilomandibulares foram realizados com a técnica de Gysi utilizando-se a plataforma e pua extraoral. Algumas modificações foram introduzidas na Técnica de Tamaki (1983): fixação de duas puas inscritoras no plano de orientação superior, para que com o mesmo movimento, fossem obtidos dois registros distintos; fixação sobre a plataforma, de um fino papel carbono, através de uma fita adesiva dupla face, no qual foram feitos os registros. A obtenção de imagens digitalizadas dos articuladores com seus respectivos planos e registros no papel carbono dos dois arcos góticos permitiu com a utilização de recursos digitais de um programa de tratamento de imagens, localizar a posição do eixo vertical de rotação condilar durante os movimentos de lateralidade de Bennett e de lateralidade a partir da Posição de Oclusão Central. Os resultados mostraram uma associação positiva das posições do eixo vertical do côndilo nos quadrantes Látero-Posterior e Médio- Posterior durante a lateralidade de Bennett direita e esquerda.

Em lateralidade a partir da posição de OC de ambos os lados ocorreu uma predominância de eventos localizados no quadrante Médio-Posterior. Em alguns casos, o eixo vertical de rotação condilar coincidiu com o centro da esfera do articulador, demonstrando a ocorrência do movimento de rotação puro e a ausência do movimento de translação do côndilo de trabalho nos movimentos de lateralidade. De acordo com a metodologia aplicada nessa pesquisa, na maior parte dos casos, os eixos não coincidiram com aquele sobre o centro da esfera condilar.

The search for clarifying the axes' mechanics of the mandibular movements stimulates the use of diverse methodologies to observe the dynamics of the temporomandibular joints. The understanding of its working, the possibility to take accurate records and its correct reproducibility fascinate militants of Prosthodontics seeking accurate simulation methods of mandibular mavements. In this study, an unprecedented methodology was applied through images and applied inferences with the purpose of analyzing the behavior of jaw condyle Bennett's side shift and lateral movements starting trom the position of centric occlusion in complete denture wearers. Twenty- twa subjects had new dentures constructed. The mandible tracings were made using the technique of Gysi with an extra oral device. Some madifications were added to Tamaki's Technique (1983): the extra oral device with two registration markers was attached to the superior occlusion rim in arder to obtain two separate registrations with a single movement; a thin articulating paper was fixed with double face adhesive tape to the platform, where the tracing was registered. The articulators' digitalized images with its acclusion rims and gothic arches traces in the articulating paper combined with an image treatment program allowed locating the position of the vertical rotation axis during Bennet's side shift and lateral movement starting trom centric occlusion.

The results were a predominance of the events where the vertical axis were located in the backward medial region for the lateral movement starting from centric occlusion in both sides and were located both in the backward medial and in the forward lateral region for the Bennett's side shift. In some cases, the vertical rotation axis coincided with the center of the articulator's sphere, showing the occurrence of apure rotation movement and the absence of translation on the working side condyle during lateral movements. According to the methodology applied in this study, in most cases, the axes were not coincident with the one on the center of the condyle sphere.

Study of the surface hardness and modulus of elasticity of conventional and microwave-cured acrylic resins.

The aim of this study was to evaluate the following acrylic resins: Clássico, QC-20 and Lucitone, recommended specifically for thermal polymerization, and Acron MC and VIPI-WAVE, made for polymerization by microwave energy. The resins were evaluated regarding their surface nanohardness and modulus of elasticity, while varying the polymerization time recommended by the manufacturer. They were also compared as to the presence of water absorbed by the samples. The technique used was nanoindentation, using the Nano Indenter XP, MTS. According to an intra-group analysis, when using the polymerization time recommended by the manufacturer, a variation of 0.14 to 0.23 GPa for nanohardness and 2.61 to 3.73 GPa for modulus of elasticity was observed for the thermally polymerized resins. The variation for the resins made for polymerization by microwave energy was 0.15 to 0.22 GPa for nanohardness and 2.94 to 3.73 GPa for modulus of elasticity. The conclusion was that the Classico resin presented higher nanohardness and higher modulus of elasticity values when compared to those of the same group, while Acron MC presented the highest values for the same characteristics when compared to those of the same group. The water absorption evaluation showed that all the thermal polymerization resins, except for Lucitone, presented significant nanohardness differences when submitted to dehydration or rehydration, while only Acron MC presented no significant differences when submitted to a double polymerization time. Regarding the modulus of elasticity, it was observed that all the tested materials and products, except for Lucitone, showed a significant increase in modulus of elasticity when submitted to a lack of hydration.

Avaliação da angulação do sulco de trabalho de dentes artificiais em relação ao plano de orientação e ao eixo de rotação vertical de lateralidade da mandíbula no articulador / Evaluation of the relationship amongst the working groove angulation of artificial teeth and the orientation plane and the vertical rotation axis of mandibular lateral translation in the articulator

Introdução - Na reabilitação protética, a oclusão e os movimentos mandibulares estão intrinsecamente ligados. Um dos conceitos sempre abordados na busca deste ideal é a relação entre os sulcos e as cúspides dos dentes com os movimentos mandibulares, que deve permitir um deslizamento livre de interferências entre ambos. Assim, foi proposto avaliar o grau de coincidência da angulação do sulco de trabalho do primeiro molar inferior artificial, quando posicionado no arco, em relação à trajetória descrita pela cúspide mésio-palatina do primeiro molar superior em relação ao eixo de rotação vertical de lateralidade da mandíbula no articulador semi-ajustável. Material e Métodos - Utilizou-se uma metodologia, através de um programa de editoração gráfica, que permitiu avaliar as imagens digitais de montagens em cera de dentes artificiais em prótese totais inferiores e de seus respectivos planos de orientação. Localizou-se o sulco de trabalho do primeiro molar inferior (A), a trajetória da cúspide mésio-palatina do primeiro molar superior adotando-se o eixo de rotação vertical no centro das esferas condilares (B), e a perpendicular à tangente ao plano de orientação (C). Resultados e Conclusões - Assim, mediram-se os ângulos formados entre A-C e A-B. Os resultados mostraram que houve casos onde A coincidiu com C, nos demais casos a angulação apresentou, em média, valores baixos, demonstrando que os parâmetros adotados para a montagem dos dentes artificiais foram seguidos. Não foi observada a coincidência entre A e B, indicando que, durante a reprodução do movimento de lateralidade no articulador, ocorre interferência na excursão da cúspide mésio-palatina do primeiro molar superior.

Introduction - In prosthetic rehabilitation, occlusion and mandibular movements are closely linked. Harmony between these factors is essential for treatment success. Therefore, the present study proposes to evaluate the degree of coincidence of the working groove angulation from the artificial mandibular first molar, when positioned on the arch, with the trajectory traced by the mesio-palatal cuspid from the maxillary first molar during mandibular lateral translation determined by the vertical axis rotation in a semi-adjustable articulator. Material and Methods - To identify this trajectory, it was utilized a graphical editing program. It was possible to evaluate digital images from artificial teeth mounted on wax for mandibular complete dentures, and their respective orientation planes positioned on the articulator. Through these images, the author located the working groove from the mandibular first molar (A), the trajectory described by the mesio-palatal cuspid from the maxillary first molar considering the vertical axis rotation at the center of the condilar spheres (B), and the perpendicular to the tangent of orientation plane (C). Results and Conclusions - Thus, the angle between A-C and the angle between A-B were measured. The results showed some cases where A coincided with C. In the remaining cases, the angulation displayed low mean values, illustrating that the mounting of artificial teeth followed the parameters adopted for the orientation plane according to the proposed technique. The coincidence between A and B was not observed, indicating that, during the lateral translation movement in the articulator, there is interference in the trajectory of the maxillary first molar mesio-palatal cuspid.

Reattachment of rehydrated dental fragment using two techniques.

UNLABELLED: The reattachment of dental fragments is a conservative treatment and should be considered in the restoration of anterior tooth fractures. This study compared the fracture strength of dehydrated and rehydrated tooth fragments submitted to two different bonding techniques. MATERIALS AND METHODS: Sixty human central and lateral mandibular incisors were divided into six groups and sectioned 3 mm from the incisal edge, using a diamond disk. Two reattachment techniques were applied: (a) bonding, using the Single Bond adhesive system and FiltekZ250 composite resin, followed by placement of a chamfer on the fracture line that was filled with composite resin (Groups 1, 3 and 5); and (b) use of the same bonding technique after dentin removal from the tooth fragment (Groups 2, 4 and 6). The following hydration treatments were applied to the fragments before bonding: (a) 48-h hydration (Groups 1 and 2); (b) 48-h dehydration (Groups 3 and 4); (c) 48-h dehydration followed by rehydration 30 min before bonding (Groups 5 and 6). The reattached teeth were mounted in acrylic resin cylinders and stored in distilled water for 24 h. The specimens were fractured at a speed of 1 mm min(-1) in a universal testing machine. RESULTS: The following mean fracture strengths (kgf) were recorded: (G1) 12.9 +/- 0.6; (G2) 18.8 +/- 4.8; (G3) 7.3 +/- 1.5; (G4) 15.2 +/- 2.4; (G5) 13.4 +/- 2.2; and (G6) 17.1 +/- 3.2. Analyses using two-way anova and the Tukey test (P < 0.01) revealed significant differences between the restorative techniques and the hydration treatments. CONCLUSIONS: The bonding technique that incorporated dentin removal from the fragment before bonding showed greater fracture strength across all groups. Fragment dehydration for 48 h caused a reduction in fracture strength, which was recovered by a 30-min rehydration.

Planejamento em prótese dentária: consideração sobre trabalhos executados em laboratórios / Treatment planning in dental prosthesis: considerations about laboratory work

Várias são as possibilidades de se reabilitar um paciente parcialmente edentado: prótese parcial removível (PPR), prótese parcial fixa (PPF) e prótese parcial fixa sobreimplante (PI). Este estudo propôs-se a identificar qual o tipo de prótese tem sido indicada mais frequentemente pelos cirurgiões-dentistas. Para tanto, seis laboratórios de Prótese Dentária da cidade de São Paulo, Brasil, participaram do estudo respondendo a um questionário que visava identificar quais os tipos de planejamento protético são mais indicados. Após o levantamento das informações, estas foram submetidas à análise estatística por intervalo de confiança. De um total de 228 casos, 18,4% eram de PPR, 36,8% eram PPF e 44,8% eram PI. Em 84 casos de PPF, 102 dentes foram reabilitados, 102 casos de PI reabilitaram 279 dentes e 292 dentes foram reabilitados com 42 casos de PPR. Nos 102 casos de PI, 30 eram de PPF e 72 de coroas unitárias (19 de coroas reabilitando um só elemento). A conexão mais utilizada foi o hexágono externo (56,6%) e a maioria das próteses era cimentada (69,3%). Quanto à classificação de Kennedy, 17 eram de Classe I reabilitando 121 dentes, 16 eram de Classe II reabilitando 104 dentes e nove eram de Classe III reabilitando 62 dentes. O número de PI foi maior do que o de PPF, que foi maior do que PPR. A PPF ainda é bastante indicada, visto que o número de PPF de três elementos foi maior do que o de PI em casos onde um implante unitário reabilitaria um espaço protético único. A PPR talvez tenha tido menor indicação pela possibilidade de reabilitação com PI. Porém, ainda é alternativa de tratamento, reabilitando um maior número de dentes. O número de PI foi grande, pois teve indicação em casos de espaços protéticos com mais de um elemento. A conexão externa foi mais encontrada, assim como o número de próteses cimentadas.

Nowadays, there are many ways to rehabilitate a partially edentulous patient: removable partial prosthesis (RPP), fixed partial prosthesis (FPP) and implant-supported fixed partial prosthesis (PI). The objective of this study is to identify what type of prosthesis has been more frequently indicated by dental surgeons. Six dental commercial laboratories at São Paulo, Brazil, participated answering a questionnaire whose aim was to identify what kinds of prosthetic planning are mostly indicated. After data collection, results were submitted to statistical analysis by the confidence interval's method. Of 228 cases, 18.4% were RPP, 36.8% were FPP and 44.8% were PI. In 84 cases of FPP, 102 cases of PI rehabilitated 279 teeth and 292 teeth were rehabilitated with 42 cases of RPP. In the 102 cases of PI, 30 were FPP and 72 of single crowns (19 of single-tooth implant crowns). The most used connection was the external hexagon (56.6%) and most of the prostheses were cement-retained (69.3%). Regarding to Kennedy's classification, 17 were class I rehabilitating 121 teeth, 16 were class II rehabilitating 104 teeth and nine were class III rehabilitating 62 teeth. The number of PI was higher then the number of FPP, which was higher the RPP. The FPP is still very much indicated - the number of 3-element- FPPs was higher than the number of PI in cases where a single implant would rehabilitate a single edentulous space. The RPP has maybe had fewer indications because of rehabilitation with PI modality. However, it is still a treatment alternative rehabilitating a higher number of teeth. The number of PI was high because there was indication in cases of prosthetic spaces with more than one missing dental element. The external connection design was the most used as well as the number of cemented prostheses.

Study of the surface hardness and modulus of elasticity of conventional and microwave-cured acrylic resins

The aim of this study was to evaluate the following acrylic resins: Clássico®, QC-20® and Lucitone®, recommended specifically for thermal polymerization, and Acron MC® and VIPI-WAVE®, made for polymerization by microwave energy. The resins were evaluated regarding their surface nanohardness and modulus of elasticity, while varying the polymerization time recommended by the manufacturer. They were also compared as to the presence of water absorbed by the samples. The technique used was nanoindentation, using the Nano Indenter XP®, MTS. According to an intra-group analysis, when using the polymerization time recommended by the manufacturer, a variation of 0.14 to 0.23 GPa for nanohardness and 2.61 to 3.73 GPa for modulus of elasticity was observed for the thermally polymerized resins. The variation for the resins made for polymerization by microwave energy was 0.15 to 0.22 GPa for nanohardness and 2.94 to 3.73 GPa for modulus of elasticity. The conclusion was that the Classico® resin presented higher nanohardness and higher modulus of elasticity values when compared to those of the same group, while Acron MC® presented the highest values for the same characteristics when compared to those of the same group. The water absorption evaluation showed that all the thermal polymerization resins, except for Lucitone®, presented significant nanohardness differences when submitted to dehydration or rehydration, while only Acron MC® presented no significant differences when submitted to a double polymerization time. Regarding the modulus of elasticity, it was observed that all the tested materials and products, except for Lucitone®, showed a significant increase in modulus of elasticity when submitted to a lack of hydration.

Development of an experimental optoelectronic device to study the amplitude of mandibular movements.

This study aimed to present a wireless mandibular motion tracking device and optoelectronic data acquisition system developed to analyze the real-time spatial motion of the entire mandible during mouth opening and closing with no restriction of any movement. The procedures were divided into three phases: confection of a kinematic arch, dynamic digital video image acquisition, and image processing and analysis by using graphic computation. Four sequences of jaw opening/closing movements were recorded in lateral view: two from the maximum intercuspation (MIC) and the other two from a forced mandibular retruded position. Jaw motion was recorded by a digital video camera and processed as spatial coordinates corresponding to the position variation of the markers in the kinematic arch. The results showed that the method was capable of recording and processing the dynamics of the mandibular movements during jaw opening/closing using pixel-magnitude points. The mandible showed points with less displacement located near the temporomandibular joint during the opening/closing movements from the mandibular retruded position. When the jaw movements were recorded from MIC, these points were located near the mandibular foramen.

Development of an experimental optoelectronic device to study the amplitude of mandibular movements

This study aimed to present a wireless mandibular motion tracking device and optoelectronic data acquisition system developed to analyze the real-time spatial motion of the entire mandible during mouth opening and closing with no restriction of any movement. The procedures were divided into three phases: confection of a kinematic arch, dynamic digital video image acquisition, and image processing and analysis by using graphic computation. Four sequences of jaw opening/closing movements were recorded in lateral view: two from the maximum intercuspation (MIC) and the other two from a forced mandibular retruded position. Jaw motion was recorded by a digital video camera and processed as spatial coordinates corresponding to the position variation of the markers in the kinematic arch. The results showed that the method was capable of recording and processing the dynamics of the mandibular movements during jaw opening/closing using pixel-magnitude points. The mandible showed points with less displacement located near the temporomandibular joint during the opening/closing movements from the mandibular retruded position. When the jaw movements were recorded from MIC, these points were located near the mandibular foramen.

Estudo comparativo do efeito da retenção a barra no ciclo mastigatório de pacientes usuários de overdenture / Comparative study of the bar retention effect in the masticatory cycle in overdenture wearers

O presente trabalho objetivou analisar as alterações no ciclo mastigatório quanto a sua forma, largura máxima, comprimento máximo e área total, em pacientes usuários de prótese total convencional superior e overdentures mandibulares, tanto com a manutenção quanto com a remoção da barra de retenção. Foram selecionados nove pacientes, entre 35 e 58 anos e sem histórico de disfunção articular. Com a mastigação de pedaços de cenoura crua, padronizados em 1 cm³ os registros no plano frontal foram obtidos por meio do aparelho Arcus Digma (Kavo Dental GmbH & Co. KG, Alemanha). Quanto à forma, encontrou-se uma variação inter-individual grande, porém, uma similaridade marcante nos dois registros de um mesmo paciente. Em relação à largura, quatro pacientes apresentaram aumento dos valores quando dos registros com a barra e para a altura, cinco pacientes com a barra apresentaram aumento desta variável. Sete pacientes apresentaram aumento da área total dos ciclos com a barra. Na análise estatística com a aplicação do teste não paramétrico de Wilcoxon, adotando o nível de significância de 5%, não foram encontradas diferenças significantes para os registros com e sem a barra. Os resultados demostraram que existe um padrão individual do ciclo mastigatório e uma grande variação inter-individual do mesmo. Nos registros com a barra, de modo geral, os ciclos foram mais regulares, lisos e com melhor direcionamento do que nos registros sem a barra, sugerindo uma mastigação mais efetiva.

Análise fotoelástica da dissipação de cargas oclusais por meio de overdentures mandibulares com barra Dolder resiliente implanto-retida / Photoelastic analysis of occlusal loads between mandibular overdentures with implant retained Dolder resilient bar

Esse trabalho objetivou analisar a disposição de tensões oclusais em overdentures com barra Dolder resiliente implanto-retida. Para tanto, utilizou-se um modelo fotoelástico com quatro implantes, sobre o qual foi construída uma infra-estrutura metálica apoiada nos dois implantes centrais e contendo uma barra Dolder, unindo-os. Foi confeccionada, então, uma prótese com material resiliente na região posterior, permitindo a movimentação comum às situações in vivo. A carga oclusal foi aplicada por meio de um modelo dentado superior em três intensidades (3, 6 e 10 kg) e em quatro posições oclusais (máxima intercuspidação, protusão, trabalho e balanceio). As imagens foram obtidas nos planos frontal e sagital, e analisadas com o auxílio do programa Leica Qwin Pro 2.3. As áreas de leitura foram: no plano frontal, região A (área disto-cervical do implante 42) e região B (área entre os implantes 32 e 42 no terço apical); no plano sagital, região de rebordo e região de mento. Os resultados permitiram concluir que: (1) a distribuição mais equlibrada de tensões ocorreu na posição de máxima intercuspidação; (2) a maior média de tensões foi encontrada na posição de trabalho; (3) em posição de protrusão, a barra recebeu a maior quantidade de tensões axiais.