Application of denture adhesive in the oral care / 口腔疾病防治

@#In recent years, the number of edentulous patients has been increasing with the increase of aging popula-tion and the number of patients with complete denture. Denture adhesive is an indispensable material of denture reten-tion intensifier in the clinic, which has been used for long periods in patients with full denture or partial denture. In this paper, we made a brief introduction according to the denture adhensive classification, mechanism of action, clinical at-tention and the latest research progress.

Comparison of retention forces with various fabrication methods and materials in double crowns

PURPOSE: The purpose of this study was to analyze the retention force changes and wear behaviours of double-crown systems over long-term use. MATERIALS AND METHODS: Ten groups, each consisting of six samples, were evaluated. Specifically, casting gold alloy primary crown - casting gold alloy secondary crown (AA), laser sintering primary crown - laser sintering secondary crown (LL), casting Cr alloy primary crown - casting Cr alloy secondary crown, (CC) zirconia primary crown - electroformed secondary crown (ZA), and CAD/CAM titanium alloy primary crown - CAD/CAM titanium alloy secondary crown (TT) groups were evaluated at cone angles of 4° and 6°. The samples were subjected to 5,000 insertion-separation cycles in artificial saliva, and the retention forces were measured every 500 cycles. The wear levels were analyzed via SEM at the beginning and end of the 5,000 cycles. RESULTS: In all samples, the retention forces increased when the conus angle decreased. The highest initial and final retention force values were found in the LL-4° group (32.89 N-32.65 N), and the lowest retention force values were found in the ZA6° group (5.41 N-6.27 N). The ZA groups' samples showed the least change in the retention force, and no wear was observed. In the other groups, wear was observed mostly in the primary crowns. CONCLUSION: More predictable, clinically relevant, and less excursive retention forces can be observed in the ZA groups. The retention force values of the LL groups were statically similar to those of the other groups, except the ZA groups.

Influence of Inner Circular Sealing Area Impression Method on the Retention of Complete Dentures

The aims of the present study were to describe an impression method of "inner circular sealing area" and to evaluate the effect of the method on retention, aesthetics and comfort of complete dentures, which lack labial base for patients with maxillary protrusions. Three patients were subjected to the experiment, and two sets of complete maxillary dentures were made for each patient; the first set was made without labial base via an inner circular sealing area method (experimental group) and the second had an intact base that was made with conventional methods (control group). Retention force tests were implemented with a tensile strength assessment device to assess the retention and a visual analogue scale (VAS) was used to evaluate the comfort between the two groups. Results showed larger retention force, better aesthetics and more comfort in the experimental group. The improved two-step impression method formed an inner circular sealing area that prevented damage to the peripheral border seal effect of the denture caused by incomplete bases and obtained better denture retention.

O objetivo deste caso foi descrever um método de impressão por "área de selamento circular interno" e avaliar o efeito deste método na retenção, estética e conforto de próteses totais sem base labial para pacientes com protrusão maxilar. Três pacientes foram objeto desta experiência e foram feitas duas próteses maxilares completas para cada um deles; a primeira foi elaborada sem base labial pelo método de área de selamento circular interno (grupo experimental) e a outra teve uma base feita pelo método convencional (grupo controle). Foram realizados testes de retenção com estudo de tensão para avaliar a retenção e para avaliação do conforto dos dois grupos, foi empregada a escala analógica visual (EAV). Os resultados demonstraram que o grupo experimental apresentou força de retenção maior, estética melhor e mais conforto. O método modificado de impressão em duas etapas formou uma área de selamento circular interno que evitou danos ao selamento periférico causados por bases incompletas e obteve melhor retenção da prótese.

Retention force attenuation of 2 kinds of clasps and surface abrasion of the Cr-Co crowns / 实用口腔医学杂志

Objective:To investigate the the retention force changes of 2 kinds of T bar clasps on Cr-Co crowns and the surface ab-rasion of the crowns.Methods:Standard Cr-Co crowns were made,and standard T bar clasps were made of Cr-Co alloy and Vitalli-um2000 with 0.25 mm and 0.5 mm undercut depth respectively.1 800 times repeated placement and removal(fatigue test)were car-ried out on instron testing machine in or without saliva soak condition.The attenuation curves of the maximum retention force was an-alysed.The surface abrasion of the crowns was observed before and after the fatigue test by SEM.Results:The retention force attenu-ation of the clasps in every group was accord with the logarithm attenuation law.SEMexamination showed that in the same condition, there was less surface abrasion in Vitallium2000 group than that in Cr-Co group.Vitallium2000 clasp was superior to Cr-Co clasp in maintaining the retention force.Conclusion:Vitallium2000 T bar clasp may provide better retention force with less furface abrasion on Cr-Co crown than Cr-Co clasp.

In vitro study on the influence of the light polymerization technique and appliance on the bond strength of intra-radicular posts / Estudo in vitro da influência da técnica e do aparelho de fotopolimerização sobre a resistência de união de pinos intra-radiculares

The purpose of this study is to verify the influence of light curing type on retention force of direct technique and direct-indirect technique.Forty bovine single root teeth with 12mm length were used in this study. Roots were endodontically treated and randomly divided into four groups according to the light curing unit and the technique used: group HD (direct technique, halogen lamp), group LD (direct technique, LED), group HI (direct-indirect technique, halogen lamp), group LI (direct-indirect technique, LED). Retention force was determined using a Universal Testing Machine (Instron). All data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s test. After the test, failure was examined and classified according to the fracture place: post/ resin; resin/dentin; mix. Group HI (246.05N ± 29.51) and LI (241.60N ± 28.95) did not show difference statistically but presented higher retention force than group HD (142.30N ± 25.60) and LD (178.56N ± 25.67). Most of fracture occurred in interface between dentin/resin. Based on the obtained results, it was concluded that adhesive cementation technique influenced in the retention of glass fiber post

O objetivo deste estudo foi avaliar a influência do tipo de luz sobre força de adesão de pinos feitos pela técnica direta ou indireta. Quarenta dentes bovinos unirradiculares com 12 milímetros de comprimento foram utilizadas neste estudo. As raízes foram tratadas endodonticamente e divididas aleatoriamente em quatro grupos de acordo com a unidade de fotoativação e técnica utilizada: grupo 1 (técnica direta, lâmpada halógena), grupo 2 (técnica direta, LED), grupo 3 (técnica direta indireta, lâmpada halógena ), grupo 4 (técnica direta indireta, LED). A força de retenção foi determinada utilizando-se uma máquina universal de ensaios (Instron). Todos os dados foram analisados pela análise de variância (ANOVA) e teste de Tukey. Após o teste, as falhas foram analisadas e classificadas de acordo com o local de fratura: pino / resina; resina / dentina ou mista. Os Grupos 3 (246,05 N ± 29,51) e 4 (241,60 N ± 28,95) não apresentaram diferenças estatísticas entre si, mas apresentou maior força de retenção que os grupos 1 (142,30 N ± 25, 60) e 2 (178,56 ± 25,67 N). A maioria das fraturas ocorreu na interface entre a dentina / resina. Com base nos resultados obtidos, concluiu-se que a técnica de cimentação adesiva influenciou na retenção dos pinos de fibra de vidro

Fatigue test of retention force of magnetic attachment and stud-type attachment / 实用口腔医学杂志

Objective:To study retention force durability of root-type attachments.Methods:Five magnetic attachments(Magfit EX-600),semi-precise stud-type attachments(Bedent) and precise stud-type attachments(Dalbo-classic) were fixed on a thermal-cycling and mechanical-loading machine respectively.The retention force of each attachment was measured at the baseline and after every 1,000 cycles of seating-removing.Results:The average retention force of magnetic attachments was(3.85?0.107) N at the baseline which attenuated for 3.38% after 10,000 cycles;The retention force of semi-precise group was(14.10?0.144) N originally and decreased 90.06% of the original force after 10,000 cycles.The primary force of the precise group was 33.14 N and was adjusted to(11.95?0.082) N as baseline attenuating for 74.56%.Conclusion: The retention force of magnetic attachments is lower than the stud attachments but is stable for 10 years.The retention force of stud-type attachments is larger at the baseline but reduced rapidly.