Effects of surface treatments on mechanical behavior of sintered and pre-sintered yttria-stabilized zirconia and reliability of crowns and abutments processed by CAD/CAM.

PURPOSE: This study evaluates the micro shear bond strength of resin cement to an yttriastabilized zirconia ceramic and the survival probability of zirconia abutments and crowns after different surface treatments through a fatigue test. MATERIALS AND METHODS: The study was divided into two parts. For part 1, 95 zirconia disks were divided into five groups (n = 19): control, untreated, airborne particle abrasion with Al2O3 particles before sintering, airborne particle abrasion with Al2O3 particles after sintering, silicatization before sintering, and silicatization after sintering. Three samples of each group were used for evaluation of surface roughness by confocal laser scanning microscopy and afterward were prepared for surface microstructural analysis by scanning electron microscopy. Ten samples of each group were subjected to micro shear bond strength testing, and the interfaces of the remaining six were examined by scanning electron microscopy. In part 2, 70 external hex zirconia abutments and copings were made by computer-aided design/computer-aided manufacturing (n = 14). Marginal fit of abutment/coping was measured in a confocal laser scanning microscope. Afterward, a fatigue test was carried out with progressive load of 80 up to 320 N (40 N steps), 5 Hz frequency, and 20,000 cycles at each step. Thermal cycling was simultaneously performed (5°C to 55°C). RESULTS: The group treated after sintering with SiO achieved statistically higher micro shear bond strength (P < .01). Higher failure loads were associated with a combined failure. The surface changes in the group treated with SiO before sintering suggest silica deposition, and there was a lack of homogeneity, which was more evident on the surface of the groups treated before sintering. The marginal gap was higher for the group treated before sintering with SiO (P < .01), and the survival probability of the sets was similar for all tested groups (P = .57). CONCLUSION: The micro shear bond strength to zirconia was improved after silicatization after sintering, but the survival probability of crown/abutment/implant sets was not affected by different surface treatments.

Microleakage at Different Implant-Abutment Connections Under Unloaded and Loaded Conditions.

PURPOSE: This study evaluated the microleakage at different implant-abutment (I-A) connections under unloaded and loaded conditions. MATERIALS AND METHODS: Forty implants, specially designed with an opening at the apex, were grouped according to the I-A and screw device: external hexagon implants with titanium (EH) or EH diamond-like carbon screws fixing the abutment; internal hexagon implants with titanium screws (IH); and Morse taper implants with solid (MT) or MT passing screws (MTps) abutments. The implants were fixed in a 2-compartment device, and toluidine blue solution (1.0 mg/mL) was placed at the I-A interface (upper compartment). The lower compartment was filled with purified water. Four implants of each group were loaded (50 N, 1.2 Hz) and after 50,000, 100,000, 200,000, and 300,000 cycles, aliquots were collected from the lower compartment for absorbance reading. Data were analyzed using analysis of variance for repeated measurements and Tukey (α = 0.05). RESULTS: Although microleakage increased over time in most of the groups, MTps group showed lower values when loaded (P < 0.05). The DLC on the EH screw did not prevent microleakage (P < 0.05). CONCLUSION: It can be concluded that MT connection is more effective to prevent microleakage.

Avaliação comparativa dos níveis de desajustes marginais de pilares UCLAS calcináveis assentados sobre a plataforma de implantes e sobre pilar cônico em próteses fixas implantosuportadas / Comparative assessment of the levels of marginal misfits UCLAS calcinable pillars seated on the platform and on implant abutment conical

Este trabalho objetivou avaliar os níveis de desajustes marginais de infraestruturas metálicas em próteses fixas assentadas sobre pilar cônico pré-fabricado (estheticone) e diretamente sobre o hexagonal do implante. Foram obtidas quatro amostras de infraestruturas de próteses fixas fundidas em liga de Níquel-Cromo assentadas sobre análogos de implantes regulares e sobre análogos do pilar cônico. As infraestruturas foram distribuídas em dois grupos (n=2) experimentais. Os desajustes marginais verticais (µm) foram avaliados com o emprego de um microscópio mensurador digital. Cada amostra recebeu quatro marcações diametralmente opostas (mesial, distal, vestibular e lingual) e foram avaliadas três vezes em cada uma dessas superfícies com o parafuso de fixação devidamente adaptado. Para a análise estatística foi utilizado o teste de U Mann Whitney na correlação dos valores das quatro faces diametralmente opostas (mesial, distal, vestibular e lingual) de ambos os grupos. Ainda, utilizou-se o teste Kruskal-Wallis para correlacionar os valores obtidos entre os pilares empregados. Os resultados mostraram que não houve diferença estatisticamente significante no desajuste marginal entre os grupos comparados. Concluiu-se que não houve diferença no desajuste marginal de infraestruturas metálicas de próteses sobre implantes fundidas com ligas de Ni-Cr com UCLA assentados sobre pilar estheticone ou diretamente sobre o hexágono de um implante de plataforma regular (AU).

The objective of this work was to evaluate the levels of marginal mismatches of metallic infrastructures on fixed prostheses seated on the following types of platforms: pre-fabricated conical pillar (estheticone), pillar UCLA, and directly on the hexagonal of the implant. Samples of infrastructures of fixed prostheses made of nickel-chrome alloy and seated on similar regular implants and on similar conical pillar were used. The infrastructures were distributed in two experimental groups (pillar estheticone and direct pillar on the platform). For the evaluation of vertical marginal mismatches (µm), each sample was seated on its platform and observed with the aid of a digital measuring microscope. Each sample received four marks, diametrically opposite to each other (mesial, distal, vestibular, and lingual) and all samples were evaluated three times in each surface with the fixation screw properly adapted. The averages of these evaluations were obtained using U Mann Whitney and Kruskal-Wallis statistical tests. The result of the U Mann Whitney test,did not show significant statistical difference while Kruskal-Wallis test showed difference between the estheticone pillar and the UCLA pillar. The estheticone pillar showed lower mismatches averages than the UCLA pillar and, no significant statistical difference was observed in the comparison with the hexagonal platform of the implant (AU).

Bacterial Adhesion and Surface Roughness for Different Clinical Techniques for Acrylic Polymethyl Methacrylate.

This study sought to assess the effect of different surface finishing and polishing protocols on the surface roughness and bacterial adhesion (S. sanguinis) to polymethyl methacrylates (PMMA). Fifty specimens were divided into 5 groups (n = 10) according to their fabrication method and surface finishing protocol: LP (3 : 1 ratio and laboratory polishing), NF (Nealon technique and finishing), NP (Nealon technique and manual polishing), MF (3 : 1 ratio and manual finishing), and MP (3 : 1 ratio and manual polishing). For each group, five specimens were submitted to bacterial adhesion tests and analyzed by scanning electron microscopy (SEM). Two additional specimens were subjected to surface topography analysis by SEM and the remaining three specimens were subjected to surface roughness measurements. Data were compared by one-way ANOVA. The mean bacterial counts were as follows: NF, 19.6 ± 3.05; MP, 5.36 ± 2.08; NP, 4.96 ± 1.93; MF, 7.36 ± 2.45; and LP, 1.56 ± 0.62 (CFU). The mean surface roughness values were as follows: NF, 3.23 ± 0.15; MP, 0.52 ± 0.05; NP, 0.60 ± 0.08; MF, 2.69 ± 0.12; and LP, 0.07 ± 0.02 (µm). A reduction in the surface roughness was observed to be directly related to a decrease in bacterial adhesion. It was verified that the laboratory processing of PMMA might decrease the surface roughness and consequently the adhesion of S. sanguinis to this material.

Retrieval technique for full-arch implant-supported fixed prosthesis: a clinical report.

In the event of the loss of an implant and to take advantage of the preexisting structures, a rescue procedure that allows continuous use of the original fixed restoration during the restoration of the tripod support at the implant level can be used. When nonphysiological occlusion forces are avoided, the success rate of this rescue procedure is very similar to any other rehabilitation made following a conventional protocol. Furthermore, the fact that the patient has already adapted to the prosthesis position and its vertical dimension results in easier functional adaptation in the postoperative period and, consequently, greater comfort.

Influence of abutment screw design and surface coating on the bending flexural strength of the implant set.

The purpose of this study was to analyze the influence of the setting and the presence of solid lubricant on the abutment screw surface on the flexural strength of the joint implant/abutment/screw. Forty abutments were connected to external hex implants, divided into 4 groups (n = 10): FE (titanium alloy screw threaded in the extremity), LE (titanium alloy screw with solid lubricant and thread in the extremity), FT (titanium alloy screw with threaded in all its length), and LT (titanium alloy screw with solid lubricant and thread in all its length). Through the mechanical flexural test, the implant/abutment resistance was evaluated with load applied perpendicular to the long axis in a mechanical testing machine (EMIC) under a speed of 0.5 mm/min. Data were submitted to a statistics test, and results showed statistically significant differences between the FE group and the other groups, and the FE group showed the lowest values. The LE group showed greater values than the LT group, and the values were statistically significant. According to the methodology used, it can be concluded that within noncoated titanium screws, a screw threaded along its entire length provided greater rigidity to the implant set, while with the screw containing solid lubricant, the screw threaded in all its length provided less rigidity of the implant set than screws with the thread only on the end. Among screws with the same geometry, those with the solid lubricant are statistically higher than those which do not have threads just at the end, but those with threads along their entire length do not show statistically significant differences.

Clínica integrada e mudança curricular: desempenho clínico na perspectiva da integralidade / Integrated clinic and curriculum change: clinical performance in the perspective of integrality

Introdução: Diante da necessidade estabelecida de mudança na formação profissional em função das novas demandas em saúde, busca-se a construção de um modelo pedagógico capaz de equilibrar excelência técnica e relevância social, visando à integralidade da atenção. No curso de odontologia a instituição da Clínica Integrada seria a responsável por resgatar essa condição de totalidade e unicidade da prática odontológica. Objetivo: Investigar o desempenho clínico de estudantes na perspectiva da integralidade em uma clínica integrada, comparando duas turmas da Faculdade de Odontologia (FO) da Universidade Federal de Goiás (UFG), uma do currículo antigo (G1) e outra da nova matriz curricular (G2). Metodologia: Neste estudo adotou-se multimétodos, sendo realizada análise documental do histórico escolar dos estudantes e dos prontuários de pacientes, aplicação de questionário autoavaliativo de desempenho clínico e grupo focal com os estudantes. Resultados: Durante o período analisado os estudantes do G1 realizaram 102 procedimentos preventivos e os do G2 272; mais de 55% dos estudantes do G1 consideraram ser suficiente a produção realizada de procedimentos preventivos. Estudantes apontaram como principais fatores relacionados ao desempenho clínico problemas operacionais da clínica (G1-88,5%; G2-54,9%) e formação científica (G1-71,2%; G2-66,7%). Conclusão: Os estudantes da nova matriz curricular apresentaram maior produtividade de atividades preventivas, enquanto os estudantes do currículo antigo apresentaram caráter curativista, entretanto, a autoavaliação de desempenho dos estudantes nem sempre se mostrou compatível com os dados de produção registrados nos prontuários. Além disso, os estudantes apontaram a formação científica e o processo organizacional como os principais fatores relacionados aos seus desempenhos.

Introduction: Given the need for a change in professional training following the new demands in health care, there has been a search to build a pedagogic model capable of balancing technical excellence and social relevance, setting comprehensive health care as the goal. In a Dental School, the institution of an integrated clinic could be a form to restore this condition of wholeness and oneness of dental practice. Objective: To investigate the clinical performance of students from a comprehensive point of view in an integrated clinic, comparing two groups of students from the Dental School of Federal University of Goiás (UFG), Brazil, one taught by the old curriculum (G1) and the other by the new curriculum (G2). Methods: For this purpose, a multi-method approach was adopted according to which the students' school records and the patients' clinical records were reviewed, self-evaluation questionnaires of clinical performance were applied and focal groups were performed with the students. Results: In the analyzed period, the students from G1 performed 102 preventive procedures and those from G2 performed 272. More than 55% of the students from G1 considered sufficient their production of preventive procedures. The students indicated as main factors related to the clinical performance the organizational process (G1-88.5%, G2-54.9%) and scientific training (G1-71.2%, G2-66.7%). Conclusions: Students from the new curriculum had higher productivity of preventive activities, while students from the old curriculum presented a curative behavior. However, self-evaluation of student performance was not always compatible with the production data from medical records. Additionally, the students indicated scientific training and organizational process as the main factors related to their performance.

Terapia periodontal de suporte: objetivos, procedimentos e intervalos / Supportive periodontal therapy: objectives, procedures and intervals

A Terapia Periodontal de Suporte (TSP) denota a necessidade básica dos procedimentos terapêuticos para que os pacientes, por meio de esforços próprios, possam controlar a infecção periodontal, sendo considerada abordagem que está diretamente relacionada com o sucesso da terapia periodontal como um todo. Inúmeras experiências clínicas sobre os efeitos em longo prazo do tratamento de periodontite têm demonstrado que manutenção profissional cuidadosa pós-terapêutica é parte integrante do tratamento periodontal, constituindo o único meio de garantir a manutenção por longo período dos efeitos benéficos da terapia. Assim, o objetivo desse artigo é revisar alguns aspectos relacionados à TSP, incluindo filosofia e periodicidade do tratamento, índices para controle periodontal, abordagem profissional, recursos e técnicas disponíveis bem como o processo de reavaliação de pacientes. A avaliação desses tópicos permite afirmar que a TSP é pré-requisito indiscutível para garantir resultados benéficos dos tratamentos com manutenção dos níveis de inserção clínica por longos períodos de tempo, mesmo que abordagens em relação à avaliação contínua do risco nos níveis do paciente, dos dentes e dos sítios dos dentes representem desafio para o conceito da TSP.

Supportive Periodontal Therapy (SPT) denotes the basic need of therapeutic procedures in order patients can control periodontal infection through their own efforts, considering the approach that is directly related to the success of the periodontal therapy as a whole. Several clinical experiences on long-term effects of periodontitis treatments have shown that a careful professional post-therapeutic maintenance therapy is part of the periodontal treatment, consisting in the only means of assuring the maintenance of the therapy beneficial effects in long term. This paper aims to review a few aspects related to SPT, including philosophy and frequency of treatment, periodontal control indexes, professional approach, available resources and techniques, as well as the process of reassessing patients. The analysis of those topics allows us to state that SPT is an undeniable prerequisite to ensure beneficial outcomes of periodontal treatment with maintenance of clinical attachment levels for long periods, even though approaches to continuous assessment of the patient?s risk levels, teeth and tooth sites pose a challenge to SPT concept.