Efeitos de customizações da prótese total mandibular sobre a qualidade de vida, força de mordida e eletromiografia de músculos da mastigação de pacientes edêntulos: um estudo clínico analítico intervencional / Effects of mandibular complete denture customizations on quality of life, bite force, and masticatory muscle electromyography in edentulous patients: an interventional analytical clinical study

Objetivo: Avaliar se customizações da prótese total mandibular (reembasamento e restabelecimento da dimensão vertical de oclusão) influenciam na amplitude eletromiográfica dos músculos masseter e temporal, força máxima de mordida e qualidade de vida relacionada à saúde oral de indivíduos edêntulos. Materiais e métodos: Usuários de próteses totais que usavam o mesmo par de próteses por mais do que 5 anos foram incluídos (sem disfunção temporomandibular) (n=15). Avaliações de qualidade de vida (Oral Health Impact Profile for Edentulous ­ OHIP-EDENT), força máxima de mordida, e eletromiografia dos músculos masseter e temporal foram realizadas em 5 tempos diferentes (T1 ­ próteses antigas originais; T2 ­ após 18 dias de uso da prótese mandibular reembasada; T3 ­ após 18 dias do restabelecimento da dimensão vertical de oclusão; e T4 e T5 ­ 30 e 100 dias de uso de novas próteses totais. Resultados: Não houve diferenças significativas entre os pontos de tempo para todos os testes eletromiográficos e de força máxima de mordida. O OHIP-EDENT mostrou que o reembasamento pode contribuir para uma maior adaptação da prótese total mandibular e conforto do paciente (T2), em contrapartida T3 foi associado com o desconforto do paciente (p<0.05). Conclusão: Baseado na avaliação de qualidade de vida relacionada à saúde oral, o reembasamento da prótese total mandibular ocasionou um aumento do conforto mastigatório para os pacientes, e o restabelecimento prévio da dimensão vertical de oclusão causou um desconforto para os pacientes. A amplitude eletromiográfica mostrou que as customizações realizadas neste estudo não aumentaram ou diminuíram o esforço mastigatório significativamente. Além disso, todos os valores de força máxima de mordida observados estavam dentro do clinicamente aceitável(AU)

Objective: To evaluate whether customizations of mandibular complete dentures (relining and restoration of the vertical dimension of occlusion) influence the electromyographic amplitude of the masseter and temporal muscles, maximum bite force and oral health-related quality of life of edentulous individuals. Materials and methods: Complete denture wearers who wore the same pair of dentures for more than 5 years were included (without temporomandibular dysfunction) (n=15). Assessments of quality of life (Oral Health Impact Profile for Edentulous ­ OHIP-EDENT), maximum bite force, and electromyography of the masseter and temporal muscles were performed at 5 different times (T1 - original old dentures; T2 - after 18 days of wearing relined mandibular denture; T3 - after 18 days of restoration of the vertical dimension of occlusion; and T4 and T5 - 30 and 100 days of wearing new complete dentures. Results: There were no significant differences between the time points for all electromyographic and maximum bite force tests. The OHIP-EDENT showed that relining can contribute to greater adaptation of the mandibular denture and patient comfort (T2), in contrast, T3 was associated with patient discomfort (p<0.05). Conclusion: Based on the assessment of quality of life related to oral health, the reline of the mandibular complete denture caused an increase in masticatory comfort for the patients, and the previous definitive restoration of the vertical dimension of occlusion caused discomfort for patients. The electromyographic amplitude showed that the customizations performed in this study did not significantly increase or decrease masticatory effort. In addition, all observed maximum bite force values were within the clinically acceptable range(AU)

Influência de espessuras de fibromucosa e de material reembasador de próteses totais na distribuição de tensões sobre implantes cone morse durante fase de osseointegração: análise pelo método dos elementos finitos - 3D / Influence of fibromucosal thickness and reline material of complete dentures on stress distribution on cone morse implants during osseointegration phase: analysis by the finite element method - 3D

Durante o período de osseointegração de implantes em uma reabilitação oral com prótese do tipo protocolo ou overdenture, uma prótese total convencional provisória poderá ser utilizada e revestida com materiais reembasadores macios, os quais têm por objetivo reduzir o estresse para a interface ossoimplante. A avaliação mecânica de tal situação clínica é de extrema relevância, a fim de se estabelecer protocolos mais seguros durante esta fase inicial da implantodontia. O objetivo deste estudo foi realizar uma análise biomecânica pelo método dos elementos finitos 3D, da distribuição de tensões durante a fase provisória de reabilitação com implantes osseointegrados simulando uma situação clínica de protocolo/overdenture inferior sobre 4 implantes do tipo cone morse, na fase de cicatrização. Para este estudo foram confeccionados 6 modelos 3D, sob carregamento em 2 direções (vertical e oblíquo em relação ao plano oclusal), simulando osso tipo II, variando a altura do tecido gengival (2 mm e 3 mm) e a espessura do material reembasador (0 mm - sem material, 2 mm e 4 mm), sendo utilizado um cicatrizador compatível com a altura + 0,5 mm para cada situação gengival. A posição dos 4 implantes cone morse (UNITITE, UCM 3510N, SIN) foi sempre a mesma, nas posições perdidas dos dentes 46, 43, 33 e 36. Para a altura gengival de 2 mm foi utilizado cicatrizador de 2,5 mm de altura (UNITITE, CIMU 4525, SIN) e para a altura gengival de 3 mm, o cicatrizador de 3,5 mm de altura (UNITITE, CIMU 4535, SIN). Os modelos utilizados foram: (G2C2,5-SR) altura gengival de 2mm, cicatrizador de 2,5mm, sem material reembasador; (G2C2,5-R2) altura gengival de 2mm, cicatrizador de 2,5mm, com soft rreembasador de 2mm; (G2C2,5-R4) altura gengival de 2mm, cicatrizador de 2,5mm, com material reembasador de 4mm; (G3C3,5-SR) altura gengival de 3mm, cicatrizador de 3,5mm, sem material reembasador; (G3C3,5-R2) altura gengival de 3mm, cicatrizador de 3,5mm, e reembasador de 2mm e (G3C3,5-R4) altura gengival de 3mm, cicatrizador de 3,5mm e soft reembasador de 4mm. A metodologia para modelagem se baseou em um escaneamento de superfície de uma prótese total inferior montada, sob um modelo inferior padrão, e de seu modelo de assentamento. As geometrias dos implantes (CM 3,5x10mm) e de seus cicatrizadores foram obtidas por simplificação do desenho dos mesmos no programa SolidWorks e no programa Rhinoceros 3D. O software utilizado para análise foi o ANSYS 17.0. A visualização dos resultados foi qualitativa através de mapas de deslocamento, von Mises e tensão máxima principal. As regiões com maiores deslocamentos foram as dos implantes mais anteriores (#33 e #43), sendo os do modelo 6 submetidos a forças verticais os que apresentaram maiores deslocamentos, próximos a 0,05 mm. A força oblíqua, de forma geral, tendeu a sobrecarregar mais os implantes do lado onde as cargas foram aplicadas. No tecido ósseo foi possível observar que o osso cortical se mostrou com mais concentração de tensão de tração que o osso trabecular. A utilização do material reembasador gerou menores tensões transmitidas para o tecido gengival, concentrando estas tensões principalmente no material reembasador. A não utilização de material reembasador aumenta as concentrações de tensões nos implantes/cicatrizadores, independentemente de sua espessura ou da espessura gengival. Concluiu-se que o uso de reembasador soft diminuiu as tensões nos implantes/cicatrizadores e tecido gengival; o aumento da espessura do material reembasador não influenciou na diminuição das tensões aos tecidos de suporte e tecidos gengivais mais espessos foram favoráveis em diminuir as tensões transmitidas ao tecido ósseo, mas concentram mais tensões nos implantes/cicatrizadores(AU)

During the period of osseointegration of implants in an oral rehabilitation with a protocol or overdenturetype prosthesis, a conventional temporary complete denture can be used and coated with soft reline materials, which aim to reduce the stress to the bone-implant interface. The mechanical assessment of such a clinical situation is extremely relevant in order to establish safer protocols during this initial phase of implantology. The objective of this study was to perform a biomechanical analysis by the 3D finite element method, of the stress distribution during the provisional phase of rehabilitation with osseointegrated implants simulating a clinical situation of protocol/lower overdenture on 4 cone morse implants, in the healing phase. For this study, 6 3D models were made, under loading in 2 directions (vertical and oblique in relation to the occlusal plane), simulating type II bone, varying the height of the gingival tissue (2 mm and 3 mm) and the thickness of the reline material (0 mm - without material, 2 mm and 4 mm), using a healer compatible with the height + 0.5 mm for each gingival situation. The position of the 4 cone morse implants (UNITITE, UCM 3510N, SIN) was always the same, in the missing positions of teeth 46, 43, 33 and 36. For the 2 mm gingival height, a 2.5 mm high healer was used. (UNITITE, CIMU 4525, SIN) and for a gingival height of 3 mm, the healer with a height of 3.5 mm (UNITITE, CIMU 4535, SIN). The models used were: (G2H2,5-WS) 2mm gingival height, 2.5mm healing, without soft material; (G2H2,5-S2) 2mm gingival height, 2.5mm healing, with 2mm reline; (G2H2,5-S4) 2mm gingival height, 2.5mm healing, with 4mm reline; (G3H3,5-WS) gingival height of 3mm, healing of 3.5mm, without soft material; (G3H3,5-S2) 3mm gingival height, 3.5mm healing, and 2mm reline and (G3H3,5-S4) gingival height of 3mm, healing of 3.5mm and reliner of 4mm. The methodology for modeling was based on a surface scan of a complete lower denture assembled, under a standard lower model, and its seating model. The geometries of the implants (CM 3.5x10mm) and their healers were obtained by simplifying their design in the SolidWorks program and in the Rhinoceros 3D program. The software used for analysis was ANSYS 17.0. The visualization of the results was qualitative through displacement maps, von Mises and maximum principal stress. The regions with the greatest displacements were those of the most anterior implants (#33 and #43), and those of model 6 submitted to vertical forces presented the greatest displacements, close to 0.05 mm. The oblique force, in general, tended to place more stress on the implants on the side where the loads were applied. In the bone tissue, it was possible to observe that the cortical bone showed a higher concentration of tensile stress than the trabecular bone. The use of soft material generated lower tensions transmitted to the gingival tissue, concentrating these tensions mainly in the soft material. The non-use of soft material increases stress concentrations on implants/healers, regardless of their thickness or gingival thickness. It was concluded that the use of a soft reliner reduced the stresses on the implants/healers and gingival tissue; the increase in the thickness of the reline material did not influence the reduction of tensions to the supporting tissues and thicker gingival tissues were favorable in reducing the tensions transmitted to the bone tissue, but concentrated more tensions in the implants/healing agentes(AU)

Reabilitação prótetica convencional após remoção cirúrgica de hiperplasia fibrosa: relato de caso / Conventional prosthetic rehabilitation after surgical removal of fibrous hyperplasia: case report

O uso de próteses mal adaptadas pode ocasionar o surgimento de processos proliferativos não neoplásicos. A hiperplasia fibrosa inflamatória (HFI) é uma lesão benigna, proveniente de reação hiperplásica do tecido conjuntivo fibroso em resposta às injúrias crônicas de baixa intensidade. O objetivo do presente trabalho é relatar um caso clínico sobre remoção cirúrgica de HFI, seguida de reabilitação oral com próteses removíveis. Paciente de 75 anos do sexo masculino relatou que gostaria de fazer a troca da sua prótese, pois a mesma estava fraturada. Ao exame clínico intra-oral constatou-se que suas próteses possuíam higienização precária, e, a superior, possuía uma borda cortante que causou uma lesão hiperplásica na região de fundo de vestíbulo anterior. Quanto ao aspecto clínico, apresentava-se com consistência fibrosa e firme à palpação, de coloração semelhante a mucosa e assintomática. O plano de tratamento proposto foi reembasamento da prótese antiga com resina Soft Confort (Dencril, Brasil) eliminando as áreas que traumatizavam a mucosa, cirurgia pré-protética para a remoção da HFI, exame histopatológico e a confecção de novas próteses, sendo a superior prótese total convencional e a inferior prótese parcial removível. Observa-se a importância no cuidado do planejamento reabilitador protético dos pacientes, pois, como foi descrito neste caso, em algumas situações pode haver necessidade de lançarmos mão de diversas modalidades de tratamento prévias à reabilitação(AU)

The use of poorly adapted prostheses can lead to the emergence of non-neoplastic proliferative processes. Inflammatory fibrous hyperplasia (HFI) is a benign lesion, resulting from a hyperplastic reaction of fibrous connective tissue in response to low-intensity chronic injuries. The aim of the present study is to report a clinical case about surgical removal of HFI, followed by oral rehabilitation with removable prostheses. A 75-year-old male patient reported that he would like to change his prosthesis, because it was fractured. On intra-oral clinical examination, it was found that his prostheses had poor hygiene, and the upper one had a cutting edge that caused a hyperplastic lesion in the deep region of the anterior vestibule. As for the clinical aspect, it was fibrous and firm on palpation, mucosa-like and asymptomatic. The proposed treatment plan was to repurpose the old prosthesis with Soft Confort resin (Dencril, Brazil), eliminating the areas that traumatized the mucosa, pre-prosthetic surgery for the removal of HFI, histopathological examination and the making of new prostheses, the upper prosthesis being conventional total and the lower partial removable prosthesis. It is observed the importance in the care of the prosthetic rehabilitation planning of the patients, because, as it was described in this case, in some situations it may be necessary to resort to different treatment modalities prior to the rehabilitation(AU)

Effects of relining materials on the flexural strength of relined thermoplastic denture base resins

PURPOSE: The aim of this study was to evaluate the effects of relining materials on the flexural strength of relined thermoplastic denture base resins (TDBRs). MATERIALS AND METHODS: For shear bond strength testing, 120 specimens were fabricated using four TDBRs (EstheShot-Bright, Acrytone, Valplast, Weldenz) that were bonded with three autopolymerizing denture relining resins (ADRRs: Vertex Self-Curing, Tokuyama Rebase, Ufi Gel Hard) with a bond area of 6.0 mm in diameter and were assigned to each group (n=10). For flexural strength testing, 120 specimens measuring 64.0×10.0×3.3 mm (ISO-1567:1999) were fabricated using four TDBRs and three ADRRs and were assigned to each group (n=10). The thickness of the specimens measured 2.0 mm of TDBR and 1.3 mm of ADRR. Forty specimens using four TDBRs and 30 specimens using ADRRs served as the control. All specimens were tested on a universal testing machine. For statistical analysis, Analysis of variance (ANOVA) with Tukey's test as post hoc and Spearman's correlation coefficient analysis (P=.05) were performed. RESULTS: Acry-Tone showed the highest shear bond strength, while Weldenz demonstrated the lowest bond strength between TDBR and ADRRs compared to other groups. EstheShot-Bright exhibited the highest flexural strength, while Weldenz showed the lowest flexural strength. Relined EstheShot-Bright demonstrated the highest flexural strength and relined Weldenz exhibited the lowest flexural strength (P < .05). Flexural strength of TDBRs (P=.001) and shear bond strength (P=.013) exhibited a positive correlation with the flexural strength of relined TDBRs. CONCLUSION: The flexural strength of relined TDBRs was affected by the flexural strength of the original denture base resins and bond strength between denture base resins and relining materials.

Standardizing the evaluation criteria on treatment outcomes of mandibular implant overdentures: a systematic review

PURPOSE: The aim of this review was to analyze the evaluation criteria on mandibular implant overdentures through a systematic review and suggest standardized evaluation criteria. MATERIALS AND METHODS: A systematic literature search was conducted by PubMed search strategy and hand-searching of relevant journals from included studies considering inclusion and exclusion criteria. Randomized clinical trials (RCT) and clinical trial studies comparing attachment systems on mandibular implant overdentures until December, 2011 were selected. Twenty nine studies were finally selected and the data about evaluation methods were collected. RESULTS: Evaluation criteria could be classified into 4 groups (implant survival, peri-implant tissue evaluation, prosthetic evaluation, and patient satisfaction). Among 29 studies, 21 studies presented implant survival rate, while any studies reporting implant failure did not present cumulative implant survival rate. Seventeen studies evaluating peri-implant tissue status presented following items as evaluation criteria; marginal bone level (14), plaque Index (13), probing depth (8), bleeding index (8), attachment gingiva level (8), gingival index (6), amount of keratinized gingiva (1). Eighteen studies evaluating prosthetic maintenance and complication also presented following items as evaluation criteria; loose matrix (17), female detachment (15), denture fracture (15), denture relining (14), abutment fracture (14), abutment screw loosening (11), and occlusal adjustment (9). Atypical questionnaire (9), Visual analog scales (VAS) (4), and Oral Health Impact Profile (OHIP) (1) were used as the format of criteria to evaluate patients satisfaction in 14 studies. CONCLUSION: For evaluation of implant overdenture, it is necessary to include cumulative survival rate for implant evaluation. It is suggested that peri-implant tissue evaluation criteria include marginal bone level, plaque index, bleeding index, probing depth, and attached gingiva level. It is also suggested that prosthetic evaluation criteria include loose matrix, female detachment, denture fracture, denture relining, abutment fracture, abutment screw loosening, and occlusal adjustment. Finally standardized criteria like OHIP-EDENT or VAS are required for patient satisfaction.

Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

OBJECTIVE: The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated. MATERIAL AND METHODS: Disk specimens (diameter 10 mm and thickness 2.5 mm) were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1) air-abraded with 50-70-µm grain alumina (CON); 2) 1) + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA); 3) 1) + conditioned with a primer including a diphosphate monomer (MDP); 4) treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. RESULTS: The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05) greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy. CONCLUSION: Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material ...

Effect of thermal cycling on denture base and autopolymerizing reline resins

Objective This study evaluated the fracture toughness (FT) of denture base and autopolymerizing reline resins, with and without thermocycling (T). Material and Methods Specimens of each material (denture base acrylic resin - Lucitone 550 – L; autopolymerizing reline resins - Ufi Gel Hard–UH, Tokuyama Rebase II-TR, New Truliner–NT and Kooliner-K), were produced, notched and divided into two groups (n=10): CG (control group of autopolymerizing reline resins and L): FT tests were performed after polymerization; TG (thermocycled group): FT tests were performed after T (5°C and 55°C for 5,000 cycles). Results: Results (MPa.m1/2) were analyzed by two-way ANOVA and Tukey's test (p=0.05). L exhibited the highest FT mean values in both groups (CG - 2.33; TG - 2.17). For the CG groups, NT showed the highest FT (1.64) among the autopolymerizing reline resins, and K the lowest (1.04). After T, when the autopolymerizing reline resins were compared, a statistically significant difference in FT was found only between the NT (1.46) and TR (1.00). Conclusions Thermocycling increased the FT of K and did not influence the FT of L, UH, TR and NT. .

Peel bond strength of resilient liner modified by the addition of antimicrobial agents to denture base acrylic resin

In order to prolong the clinical longevity of resilient denture relining materials and reduce plaque accumulation, incorporation of antimicrobial agents into these materials has been proposed. However, this addition may affect their properties. OBJECTIVE: This study evaluated the effect of the addition of antimicrobial agents into one soft liner (Soft Confort, Dencril) on its peel bond strength to one denture base (QC 20, Dentsply). MATERIAL AND METHODS: Acrylic specimens (n=9) were made (75x10x3 mm) and stored in distilled water at 37ºC for 48 h. The drug powder concentrations (nystatin 500,000U - G2; nystatin 1,000,000U - G3; miconazole 125 mg - G4; miconazole 250 mg - G5; ketoconazole 100 mg - G6; ketoconazole 200 mg - G7; chlorhexidine diacetate 5% - G8; and 10% chlorhexidine diacetate - G9) were blended with the soft liner powder before the addition of the soft liner liquid. A group (G1) without any drug incorporation was used as control. Specimens (n=9) (75x10x6 mm) were plasticized according to the manufacturers' instructions and stored in distilled water at 37ºC for 24 h. Relined specimens were then submitted to a 180-degree peel test at a crosshead speed of 10 mm/min. Data (MPa) were analyzed by analysis of variance (α=0.05) and the failure modes were visually classified. RESULTS: No significant difference was found among experimental groups (p=0.148). Cohesive failure located within the resilient material was predominantly observed in all tested groups. CONCLUSIONS: Peel bond strength between the denture base and the modified soft liner was not affected by the addition of antimicrobial agents.

Reembasamento em prótese total: material resiliente versus material rígido / Rebasing in total prosthesis: resiliente material versus rigid material

A reabsorção óssea do rebordo alveolar é um processo crônico e irreversível. Com o objetivode minimizar estas alterações, tem-se indicado o reembasamento imediato ou mediato das próteses removíveis. Existem estudos que demonstram que este procedimento traz maior qualidade de uso aos pacientes, pois promove uma adaptação mais satisfatória das mesmas com a mucosa. O objetivo deste artigo é comparar as indicações, vantagens e limitações dos materiais, resilientes e rígidos, indicados para o reembasamento imediato de próteses removíveis em consultório, através de dois casos clínicos. Após o acompanhamento destes casos clínicos, pode-se concluir que para obtenção do sucesso do reembasamento é importante que se respeite a indicação clínica, as propriedades físicas e mecânicas de cada material, bem como a proservação do comportamento do material, através de um rigoroso controle clínico. Também que os reembasadores rígidos podem ser utilizados por um maior período em relação aos resilientes, os quais devido às suas limitações devem ser utilizados apenas em condições transitórias.

The alveolar bone resorption is a cronic and irreversible processo In order to minimize thesechanges, it has been indicated the mediate or immediate relining of dentures. Studies have shown that the procedure for rebasing of dentures brings higher quality of use to patients, as this will promote a more satisfying adaptation of the prosthesis with the mucosa. The aim of this paper is to compare the indications, advantages and limitations of relíning materiais, resilient and hard, in office by two clinical cases. After the clinical monitoring of these cases, it can be concluded that to obtain the success of the relining is important to respect the indication, the physical and mechanical prerties of each material, as well as preservation the behavior of the material, through a rigorous clinical control. Also the hard reline can be used for a longer period compared to resilient, which due to their limitations should only be used in transient conditions.

Changes in roughness of denture base and reline materials by chemical disinfection or microwave irradiation: Surface roughness of denture base and reline materials

OBJECTIVE: The effect of disinfection by immersion in sodium perborate solution and microwave irradiation on surface roughness of one denture base resin (Lucitone 550 -L), 3 hard chairside reline resins (Tokuyama Rebase II-TR, New Truliner-NT, Ufi Gel hard-UH) and 3 resilient reline materials (Trusoft-T; Sofreliner-S, Dentusil-D) was evaluated. MATERIAL AND METHODS: Thirty specimens of each material were made and divided into 3 groups: Control - not disinfected; P - daily disinfection by immersing in sodium perborate solution (3.8 percent); MW - microwave disinfection (6 min/650 W). Roughness measurements were made after polymerization (baseline) and after 1, 3 and 28 days. Roughness differences relative to the baseline readings were analyzed by Student's t-test (P=0.05). RESULTS: At baseline, Trusoft showed the highest (P<0.001) mean surface roughness (3.54 µm), and its surface roughness was significantly reduced after 28 days of disinfection by immersion in sodium perborate (P=0.013). Roughness measurements of material Trusoft were not performed after microwave disinfection due to the severe alterations on the surface. In the 3 groups evaluated, changes in roughness were significant for materials Ufi Gel hard (from 0.11 to 0.26 µm; P<0.041) and New Truliner (0.19 to 0.76 µm; P<0.019). The roughness of materials Lucitone 550 (0.37 µm), Tokuyama Rebase II (0.37 µm), Sofreliner (0.49 µm) and Dentusil (0.38 µm) remained unaffected (P>0.05). CONCLUSIONS: The roughness of the hard reline materials Ufi Gel hard and New Truliner was adversely affected by microwave disinfection, immersion in water or in sodium perborate. Microwave disinfection caused severe alterations on the surface of the resilient liner Trusoft.

Propiedades de materiales resilientes para rebase de prótesis: [revisión] / Properties of resilient materials used for relining dentures: [review]

La presente revisión de literatura tiene por objetivo mostrar las principales características, ventajas y limitaciones de los rebases blandos con el fin de acercar su utilización al clínico general. Los materiales resilientes para rebase de prótesis han sido desenvueltos para minimizar las posibles molestias causadas por las bases de las prótesis en la mucosa. Estos materiales forman un grupo de materiales elásticos que llenan total o parcialmente la base de las prótesis, con la finalidad de disminuir el impacto de la fuerza masticatoria sobre la mucosa de revestimiento, pudiendo ser utilizados como material temporal o de un carácter más permanente. Los rebases blandos además de clasificarse según el tiempo de uso como provisionales (corta duración) o permanentes (larga duración), estos pueden ser divididos según la base del material: acrílico o silicona. Dentro de las indicaciones se encuentran la estabilización de prótesis después de cirugías, el condicionamiento de tejidos fibromucosos, el rebase de prótesis provisionales durante el periodo de óseo integración de implantes o como medio retentivo para sobredentaduras implanto-soportadas, además pueden ser utilizados como material para impresiones funcionales. A pesar de que los materiales resilientes para rebase de prótesis poseen algunas desventajas, estos pueden ser usados para el rebase de prótesis removible parcial o total con un buen desempeño clínico, al indicarlas correctamente y por un tiempo determinado.

The objective of this literature review is to show the main features, advantages and limitations of soft liners to bring information for the general dentist use. Soft liners have been developed minimize any inconvenience caused by the hard bases of the prosthesis in the mucosa. These materials form a group of elastic materials that fill all or part of the prosthesis denture base, in order to reduce the impact force on masticatory mucosa, this soft liner can be used as temporary or more permanent material. Soft liners can be classified according to time of use as temporary (short term) or permanent (long term), and also these can be divided according to the material: acrylic based or silicone bases. The indications are stabilizing prosthesis after surgery fibromucosous tissue conditioning, the breaching of temporary restorations during the osseointegration of implants to over-retentive implant-supported dentures, it can also be used as material for functional impressions. Although soft liners have some disadvantages, they can be used for the relining of partial or complete removable prosthesis with a good clinical performance, with correct indications and for a given time.

The effect of bur preparation on the surface roughness and reline bond strength of urethane dimethacrylate denture base resin.

Background: The clinical success of relining depends on the ability of reline resin to bond to denture base. Surface preparations may influence reline bond strength of urethane-based dimethacrylate denture base resin. Aim: To investigate the effect of bur preparation on the surface roughness (R a ) of eclipse denture base resin and its shear bond strength (SBS) to an intra-oral self-curing reline material. The mode of reline bonding failure was also examined. Materials and Methods: Twenty-four cylindrical Eclipse™ specimens were prepared and separated into three groups of eight specimens each. Two groups were subjected to mechanical preparation using standard and fine tungsten carbide (TC) burs and the third group (control) was left unprepared. The R a of all specimens was measured using a contact stylus profilometer. Subsequently, relining was done on the prepared surface and SBS testing was carried out a day later using a universal testing machine. Results: One-way ANOVA revealed significant differences (P<0.05) in R a and SBS values for all the groups. Post-hoc Tukey's HSD test showed significant differences (P<0.05) between all the groups in the R a values. For SBS also there were significant differences (P<0.05), except between standard bur and control. Conclusions: 1) There was a statistically significant difference in the R a of Eclipse™ specimens prepared using different carbide burs (P<0.05). 2) There was a statistically significant difference in the relined SBS (P<0.05) when prepared using different burs, but the difference between the standard bur and the control group was not statistically significant.

Impact strength of denture base and reline acrylic resins subjected to long-term water immersion

Water may influence the mechanical properties of the acrylic resins. Thus, the effect of water storage on the impact strength (IS) of one denture base (Lucitone 550 - L) and four reline resins (Tokuyama Rebase II - T; UfiGel Hard - U; Kooliner - K; New Truliner - NT) was evaluated. Bars of L were made (60 x 6 x 2 mm) and relined (2 mm) with T, U, K, NT and L. Intact specimens of each material (60 x 6 x 4 mm) were also fabricated for comparative purposes. Specimens were submitted to Charpy impact tests without water storage (control) and after immersion in water for 7, 90 and 180 days. Data (kJ/m²) analyzed by two-way ANOVA and Tukey's test (p=0.05) revealed that after 90 days, U exhibited an increase in the IS (0.93) compared to 7 days (0.58). K (1.48) and L/K (7.21) exhibited a decrease at the 7-day period (1.01 and 3.23, respectively). NT (0.60) showed an increase in the IS after 180 days (1.52), whereas L/NT (7.70) showed a decrease (3.17). Water immersion improved the IS of U and NT, and decreased the IS of K, L/K, and L/NT. Water may affect differently the IS of acrylic resins and, consequently, the resistance to fracture of relined denture bases.

A água pode influenciar as propriedades mecânicas das resinas acrílicas. Assim, o efeito do armazenamento em água na resistência ao impacto (RI) de uma resina para base de prótese (Lucitone 550-L) e quatro materiais reembasadores (Tokuyama Rebase II-T; UfiGel Hard-U; Kooliner-K; New Truliner-NT) foi avaliado. Barras da resina L foram confeccionadas (60 x 6 x 2 mm) e reembasadas (2 mm) com T, U, K, NT e L. Amostras não reembasadas de cada material também foram confeccionadas (60 x 6 x 4 mm) para fins comparativos. As amostras foram submetidas aos testes de impacto tipo Charpy sem armazenamento (controle) e após imersão em água por 7, 90 e 180 dias. Os resultados (kJ/m²) analisados por meio de ANOVA dois fatores e teste de Tukey (p=0,05) revelaram que, após 90 dias, U exibiu aumento na RI (0,93) comparado com 7 dias (0,58). K (1,48) e L/K (7,21) exibiram diminuição no período de 7 dias (1,01 e 3,23, respectivamente). NT (0,60) apresentou aumento na RI após 180 dias (1,52), enquanto L/NT (7,70) apresentou redução (3,17). A imersão em água melhorou a RI de U e NT e diminuiu a RI de K, L/K, e L/NT. A água pode afetar de maneira diversa a RI das resinas acrílicas e, consequentemente, a resistência à fratura das bases de próteses reembasadas.

Effect of microwave postpolymerization treatment on residual monomer content and the flexural strength of autopolymerizing reline resin.

Background : Microwave postpolymerization has been suggested as a method to improve the flexural strength of an autopolymerizing denture reline resin. However, the effect of microwave postpolymerization on the residual monomer content and its influence on flexural strength have not been investigated. Objectives : This study analyzed the effect of microwave postpolymerization on the residual monomer content and its influence on the flexural strength of an autopolymerizing reline resin (Denture Liner). Materials and Methods : A total of 70 specimens (64 Χ 10 Χ 3.3 mm) were polymerized according to the manufacturer's instructions and divided into 7 groups (n = 10). Control group specimens were not subjectedto any further processing. Before testing, the specimens were subjected to postpolymerization in a microwave oven using different power (550 and 650 W) and time (3, 4, and 5 min) settings. Two specimens of each group were then manually ground into fine powder and samples extracted from the specimens using reflux method. The samples were then subjected to gas chromatography for residual monomer determination in area%. Eight specimens were subjected to a three-point bending device with a span of 50 mm and crosshead speed of 5 mm/min, and the flexural strength was determined in MPa. Data analyses included Student's t-test and one-way analysis of variance. Results : For the Denture Liner reline resin, the residual monomer content decreased and the flexural strength increased significantly with the application of microwave irradiation using different time/power combinations. The specimens with the lowest residual monomer content were the similar specimens which presented with the highest flexural strength. Conclusion : Microwave postpolymerization irradiation can be an effective method for increasing the flexural strength of denture liner (at 650 W for 5 min) by reducing the residual monomer content by further polymerization at free radical sites.

Effects of thermocycling on mechanical properties of soft lining materials / Influencia del termociclado sobre las propiedades físicas de los materiales softs para rebasado

Soft linings are materials used to reduce the tension and forces of mastication, forming all or part of the fitting surface of a denture. This study evaluated the effect of thermocycling on waterabsorption, solubility, Shore A hardness and color stability of permanent soft liner materials. MATERIAL AND METHODS: Two chemically activated soft liner materials (Sofreliner S; GC Reline Ultrasoft) were tested. Twenty cylindrical specimens (30.0 x 1.0 mm) were prepared for measuring water absorption and solubility and another twenty (30.0 x 3 mm) for analyzing Shore A hardness and color stability. Color was measured by a spectrophotometer before and after 2000 thermocycles. A one-way ANOVA test and Tukey test at a 5% confidence level (p<0.05) were performed. RESULTS: The results did not show statistical differences for water absorption, solubility or color stability. The post-thermocycling Shore A hardness values were significantlyhigher than those before the treatment. CONCLUSION: Thermocycling of soft liner materials increased Shore A hardness.

Objetivo: Los materiales para rebasado tienen como propósito disminuir la tensión, la presión masticatoria en los tejidos de soporte y aumentar la retención de la dentadura, además de serindicados para prótesis buco-maxilo-faciales. El objetivo de este estudio fue evaluar el efecto del termociclado en los materiales para rebasado blandos considerados definitivos y evaluar lasalteraciones en relación a la absorción de agua, solubilidad, dureza Shore A y estabilidad de color. Materiales y Métodos: Dos materiales para rebasado blandos definitivos (Sofreliner S y GC Reline Ultrasoft) fueron examinados. Fueron confeccionados 20 muestras, midiendo 30 mm de diámetro x 1 mm deespesor, aquellos destinados al test de absorción y solubilidad y 20 muestras con 30 mm de diámetro x 3 mm de espesor para dureza y estabilidad de color. Fueron realizados los tests deabsorción y solubilidad. La dureza fue medida en un durometroy la estabilidad de color por medio de un spectrofotómetro en los periodos inicial y después de 2000 ciclos de termociclaje. Una vez obtenidos los datos, estos fueron submetidos al análisis de varianza (ANOVA) seguido por el test Tukey (p<0,05). Resultados:En relación a la absorción, solubilidad y estabilidad de color no hubo diferencia estadísticamente significativa entre losmateriales, en relación al test de dureza fue constatada una diferencia estadísticamente significativa entre los periodos y los materiales examinados. Conclusión: El termociclaje no interfirióen la absorción, solubilidad y estabilidad de color de los materiales evaluados, sin embargo interfirió de forma significativaen la dureza Shore A. Los materiales tuvieron sus valores promedios de dureza aumentados después del termociclaje.

Avaliação in vitro da citotoxidade de resinas acrílicas para reembasamento baseadas em uma nova formulação / In vitro cytotoxicity evaluation of reline acrylic resins based on new formulation

O objetivo deste estudo foi determinar a citotoxicidade in vitro de duas resinas reembasadoras experimentais autopolimerizáveis contendo alta concentração de agentes de ligação cruzada, etilenoglicol dimetacrilato (EGDMA) e 1,4-butanodiol dimetacrilato (BDMA) comparadas com uma resina reembasadora comercial (Tokuyama Rebase Fast II). Foram confeccionados corpos-de-prova em forma de discos das três resinas acrílicas reembasadoras rígidas sob condições assépticas. Os fibroblastos (L929) foram cultivados em placas com 96 compartimentos e incubadas por 24 h em meio de cultura Eagle. Os extratos foram preparados, colocando-se três amostras de cada resina em frascos de vidro estéreis com 9 mL de meio de Eagle e incubadas a 37º C por 24 h. O efeito citotóxico dos extratos foram avaliados utilizando os testes de incorporação do 3 H-timidina e MTT, que refletem os níveis de síntese de DNA e metabolismo celular, respectivamente. Os dados foram analisados estatisticamente, utilizando análise de variância (P<0.05). Para o teste de incorporação do 3 H-timidina, não foram observadas diferenças significativas (P>0.05) entre os materiais. A média da quantidade do isótopo incorporado no DNA celular para todas as resinas acrílicas foi estatisticamente menor do que para o controle. Todas as resinas acrílicas foram classificadas pelo teste de incorporação do 3 Htimidina como moderadamente citotóxicas. Da mesma forma, para o teste do MTT, não foi encontrada diferença significativa para a citotoxicidade entre os materiais (P>0.05). Quando a citotoxidade foi comparado com o grupo controle, todas as resinas foram classificadas entre não citotóxicas e discretamente citotóxicas pelo teste do MTT. Assim, conclui-se que a incorporação dos agentes de ligação cruzada, EGDMA e BDMA não influenciaram significativamente sobre a citotoxicidade observada. Não houve diferença entre a viabilidade celular para os materiais avaliados em ambos os testes

The aim of this study was to determine the cytotoxicity in vitro of two trials autopolymerizing reline systems made with higher concentration of cross-linking agents, EGDMA and BDMA compared to a commercial reline resin. Sample disks of the three hard reline acrylic resins were fabricated under aseptic conditions. The Fibroblast L929 cells were cultured in 96-well plates and incubated for 24 h in Eagle's medium. Eluates were prepared by placing three samples into a sterile glass vial with 9 mL of Eagle's medium and incubating at 37ºC for 24 h. The cytotoxic effect from the eluates was evaluated using the 3H-thymidine incorporation and MTT assays, which reflect DNA synthesis levels and cell metabolism, respectively. The data were statistically analyzed by using the one-way analysis of variance (P<.05). With the 3H-thymidine incorporation assay, no significant differences (P > .05) were found between the materials. The mean quantity of isotope incorporated into cellular DNA for all acrylic resins was statistically smaller than for the control. All acrylic resins were graded by the 3Hthymidine incorporation assay as moderate cytotoxic. Similarly, with the MTT assay, no significant difference in cytotoxicity was found between the materials (P > .05). When the cytotoxicity was compared with control group, all resins assay were between non cytotoxic and slight cytotoxic by the MTT. The incorporation of cross-linking agents, EGDMA and BDMA had no significant influence on the cytotoxicity observed. There was no cell viability difference between all materials in both assays.

Wettability of denture relining materials under water storage over time

STATEMENT OF PROBLEM: Poor wettability of denture relining materials may lead to retention problems and patient discomfort. PURPOSE: Purpose of this study is to compare and evaluate wettability of nine denture relining materials using contact angle measurements under air and water storage over time. MATERIAL AND METHODS: Nine denture relining materials were investigated in this study. Two heat-curing polymethyl-methacrylate (PMMA) denture base materials: Vertex RS, Lang, one self-curing polyethyl-methacrylate (PEMA) chairside reline resin: Rebase II, six silicone relining materials: Mucopren soft, Mucosoft, Mollosil(R) plus, Sofreliner Touch, GC Reline(TM) Ultrasoft, Silagum automix comfort were used in this experiment. Contact angles were measured using high-resolution drop shape analysis system (DSA 10-MK2, KRUESS, Germany) under three conditions (in air after setting, 1 hour water storage, and 24 hours water storage). Nine materials were classified into three groups according to material composition (Group 1: PMMA, Group 2: PEMA, Group 3: Silicone). Mean values of contact angles were compared using independent samples t-test and one-way ANOVA, followed by a Scheffe's post hoc analysis (alpha= 0.01). RESULTS: Contact angles of materials tested after air and water storage increased in the following order: Group 1 (PMMA), Group 2 (PEMA), Group 3 (Silicone). Heat-cured acrylic denture base resins had more wettability than silicone relining materials. Lang had the highest wettability after 24 hours of water storage. Silicone relining materials had lower wettability due to their hydrophobicity. Wettability of all denture relining materials, except Rebase II and Mollosil(R) plus, increased after 24 hours of water storage. CONCLUSIONS: Conventional heat-cured resin showed the highest wettability, therefore, it can be suggested that heat-cured acrylic resin is material of choice for denture relining materials.

Caracterização de materiais experimentais e comerciais para reembasamento imediato por meio de análise de propriedades físico-químicas e mecânicas / Characterization of experimental and commercially available chairside reline resins by physical-mechanical and chemical properties

Este estudo avaliou o comportamento exotérmico de 5 resinas rígidas para reembasamento imediato, duas experimentais (E1 e E2) à base de agentes de ligação cruzada (etileno glicol dimetacrilato e 1,4-butanediol dimetacrilato) e três comerciais (Kooliner-K, New Truliner-NT, Tokuyama Rebase II-TR II), bem como o grau de conversão (GC), a sorção (Sor) e a solubilidade (Sol) em água, a contração linear de polimerização (CLP), as propriedades viscoelásticas e a resistência à flexão desses materiais e de uma resina para base de prótese (Lucitone 550-L). Foi avaliada, ainda, a resistência de união (RU) entre os reembasadores e a resina de base. O comportamento exotérmico foi avaliado (n=4) com termopar tipo K inserido no interior das resinas, em matriz circular (60 x 2,0 mm), e mantido até a polimerização. O GC (%) foi avaliado (n=5) por espectroscopia de infravermelho por transformadas de Fourier (32 leituras; resolução 4,0 cm-1). A Sor e a Sol (μg/mm3) foram mensuradas (n=5) seguindo as recomendações da ISO 1567. A CLP (%) foi avaliada (n=10), em projetor de perfil (Nikon 6C), em corpos-de-prova circulares (50 x 0,5 mm). Para avaliar as propriedades viscoelásticas, corpos-de-prova (40 x 10 x 3,3 mm) foram submetidos (n=2) à análise térmica dinâmico-mecânica (DMTA) em diferentes intervalos de temperatura (ciclos). O módulo de armazenamento (E’) e o amortecimento mecânico (tan δ) a 37ºC foram registrados durante o primeiro e último ciclo da DMTA. A temperatura de transição vítrea (Tg) foi mensurada somente no último ciclo da DMTA. Os ensaios mecânicos de flexão (0,5 mm/min) foram realizados (n=10) em corpos-de-prova (64 x 10 x 3,3 mm) intactos ou reembasados e a resistência (MPa) calculada na tensão máxima (RFM) e no limite de proporcionalidade (RFLP). Para avaliar a RU (MPa) entre os materiais, 60 cilindros (20 x 20 mm) da resina L foram processados...

This study evaluated the exothermic behavior, degree of conversion (DC), water sorption (WSor), water solubility (WSol), linear polymerization shrinkage (LPS), viscoelastic properties and flexural strength of 5 hard chairside reline resins, two experimental (E1 and E2) based on crosslinking agents (ethylene glycol dimethacrylate and 1,4-butanediol dimethacrylate) and three commercially available (Kooliner-K, New Truliner-NT and Tokuyama Rebase II-TR II), and one heat-polymerized denture base resin (Lucitone 550-L). The shear bond strength (SBS) between the denture base resin and the reline materials was also evaluated. The exothermic behavior of circular specimens (60 x 2.0 mm) during polymerization was assessed (n=4) using a type K thermocouple. The DC (%) was measured (n=5) by Fourier Transformed infrared-attenuated total reflectance (FTIR-ATR) spectroscopy (32 scans; resolution of 4.0 cm-1). WSor and Wsol (μg/mm3) were determined (n=5) according to the recommendation stated in ISO 1567. The LPS (%) was measured (n=10) in circular specimens (50 x 0.5 mm) using a perfilometer (Nikon 6C). The viscoelastic properties of the specimens (40 x 10 x 3.3 mm) were evaluated (n=2) by dynamical-mechanical thermal analysis (DMTA) under different temperature ranges (runs). Values of storage modulus (E’) and loss tangent (tan δ) at 37ºC were obtained from the first and last runs. The glass transition temperature (Tg) was only measured from the last run. Ultimate flexural strength (UFS - MPa) and flexural strength at the proportional limit (FSPL - MPa) were determined (n=10) by three-point test (0.5 mm/min) using intact and relined specimens (64 x 10 x 3.3 mm). To evaluate the SBS between the materials, 60 cylinders (20 x 20 mm) of the denture base resin L were processed, relined (3.5 x 5.0 mm) and submitted to shear testing (0.5 mm/min). Data were analyzed by ANOVA and Tukey...

Efeito das soluções de limpeza de dentadura na degradação de dois reembasadores macios / Effect of denture cleansers in the degradation of two soft liners

O objetivo deste estudo foi avaliar a degradação de dois materiais reembassadores macios. Coe Soft e Ufi Gel P, quando submetidos a tratamentos de limpeza química para próteses (Corega Tabs e hipoclorito de sódio a 1%). Foram confeccionados 30 corpos-de-prova de cada material divididos em 6 grupos G3 e G4 foram imersos diariamente na solução de Corega tabs e os dos grupos G5 e G6 da solução de hipoclorito de sódio 1%, por 5 e 10 minutos, respectivamente, durante 15 dias. Os resultados mostraram que o Coe Soft foi degredado nas três soluções, enquanto o Ufi Gel P foi pelo hipoclorito e água destilada, e não apresentou degradação no Corega tabs. A degradação entre os materiais foi similar nos diferentes tempos.

Effect of cervical relining of acrylic resin copings on the accuracy of stone dies obtained using a polyether impression material

The purpose of this study was to evaluate the accuracy of the respective dies after polyether elastomeric procedure in the presence or absence of cervical contact of the acrylic resin shell with the cervical region, establishing a comparison to dies obtained with stock trays. This study consisted of three groups with 10 specimens each: 1) acrylic copings without cervical contact, (cn); 2) acrylic copings with cervical contact (cc); 3) perforated stock tray, (st). The accuracy of the resulting dies was verified with the aid of a master crown, precisely fit to the master steel die. ANOVA test found statistically significant differences among groups (p<0.001). Tukey's test found that the smallest discrepancy occurred in group cn, followed by cc, while the st group presented the highest difference (cc x cn: p=0.007; st x cn: p<0.001; st x cc: p<0.001).