A randomised crossover clinical trial of masticatory function in complete denture wearers with conventional and lingualised balanced occlusion.

OBJECTIVES: The purposes of the present study were as follows: (1) to conduct a randomised crossover clinical trial to evaluate masticatory performance in wearers of conventional complete dentures in both arcs with conventional balanced occlusion (CBO) and lingualised balanced occlusion (LBO), using almonds as natural test food chewed for (a) 30 chewing cycles, (b) 40 chewing cycles and (c) until the subject felt ready to swallow and (2) to perform a randomised crossover clinical trial of oral health self-perception through the Geriatric Oral Health Assessment Index (GOHAI) questionnaire. BACKGROUND: During rehabilitation with full dentures, achieving stability and retention is essential for masticatory performance. A factor that can act is the appropriate occlusal scheme to be used, although the literature is full of discussions as to the most suitable occlusal scheme to be used, being CBO and LBO the most used in complete dentures. MATERIALS AND METHODS: The clinical trial was conducted with 30 participants (14 males and 16 females; average age 65.8 years). A base of interchangeable posterior teeth in the lower dentures was used, thereby changing the occlusal schemes without needing to make another complete denture. The masticatory tests and GOHAI application were conducted in two sessions: first with each occlusal scheme, and second only after participants did not report discomfort with dentures. The analysis of variance for the mixed repeated-measures test (ANOVA) was used to verify the results (α = 0.05). RESULTS: The results showed no difference in masticatory performance according to the occlusal scheme (P = .519). The masticatory performance increased with the number of cycles (P < .001) tested, regardless of the type of occlusion scheme, and oral health self-perception was higher after the second masticatory evaluation session (P = .027). CONCLUSION: The masticatory performance was similar between the two occlusal schemes, increasing according to the number of chewing cycles. The adaptive period is relevant, regardless of the occlusion scheme, because the time factor was decisive for the improvements noted in the oral health self-perception of the participants (according to the GOHAI results).

Influence of filling materials on the fracture resistance of resin composite used for sealing screw access hole / Influência dos materiais de preenchimento na resistência a fratura das resinas compostas utilizadas para selamento do orifício de acesso ao parafuso

Introduction: Screw-retained restorations have a screw access hole (SAH) sealed with resin composite aiming at safe-guarding the aesthetic features of the ceramic veneer. The loss or wear of the resin composite applied in sealing the SAH is among the most common complications in implant prosthodontics, as the fracture of ceramic veneer. Objective: Evaluate the influence of sealant materials on the fracture resistance of resin composite applied in sealing screw access hole in screwed (SAH) implants. Material and method: The samples were produced from UCLA abutments in metallic NiCr alloy with subsequent application of ceramic. After asperisation and conditioning ceramic surface, was applied silane and dentin adhesive, before sealing the conduits with resin composites Z100 and P60. Nine groups (n=10) were evaluated: sealing with Z-100 (ZNC) and P-60 (PNC) without obturation of SAH; sealing with Z100 (ZCP) and P-60 (PCP) with absorbent cotton; Z100 (ZPT) and P60 (PPT) with polytetrafluoroethylene; Z100 (ZGP) and P60 (PGP) with gutta-percha and a cemented ceramic crown (ICS). After the fracture resistance test, the data were analyzed using two-way ANOVA and Tukey HSD tests (p<.05). Result: The fracture mode was evaluated by scanning electron microscope. Irrespective of the filling material, the highest mean values of fracture resistance were observed in the sealing with P60 (p=.002). When combined with resins composed of a sealing material, the results obtained were: ZGP: 805.5N/ PGP: 929.5N

Introdução: As próteses parafusadas possuem orifício de acesso ao parafuso (SAH), os quais são selados com resina composta. Sua perda ou desgaste está entre as complicações mais comuns em próteses sobre implantes, associadas a fratura da lâmina cerâmica. Objetivo: Assim, é importante avaliar a influência dos materiais de selamento na resistência à fratura de resina composta aplicada ao SAH no selamento de prótese sobre implantes parafusadas. Material e método: As amostras foram produzidas utilizando pilares UCLA em liga metálica de NiCr com posterior aplicação de cerâmica. Após asperização e condicionamento da superfície cerâmica, foram aplicados silano e adesivo dentinário, antes da selagem dos condutos com as resinas compostas Z100 e P60. Foram avaliados nove grupos (n = 10): selamento com Z-100 (ZNC) e P-60 (PNC) sem selamento do SAH; selamento com Z100 (ZCP) e P-60 (PCP) com algodão absorvente; Z100 (ZPT) e P60 (PPT) com politetrafluoroetileno; Z100 (ZGP) e P60 (PGP) com guta-percha e coroa de cerâmica cimentada (ICS). Após o teste de resistência à fratura, os dados foram analisados usando ANOVA de dois fatores e testes Tukey HSD (p<0,05). O tipo de fratura foi avaliado por microscópio eletrônico de varredura. Resultado Independentemente do material obturador, os maiores valores médios de resistência à fratura foram observados no selamento com P60 (p=0,002). Quando combinados com resinas compostas por um material de selamento, os resultados obtidos foram: ZGP: 805,5N/ PGP: 929,5N

Influence of Cusp Inclination and Type of Retention on Fracture Load of Implant-Supported Crowns.

There are few informations about the influence of cusp inclination on the fracture strength of implant-supported crowns. The study aimed to evaluate the influence of cusp inclination and retention type on fracture load in implant-supported metal-ceramic single crowns. Sixty crowns were made, classified as cemented and screw-retained with screw access hole (SAH) sealed or not. Standard (33°) and reduced (20°) cusp inclinations were tested for each group (n=10). To support crowns of a mandibular second molar, analogs of external hexagon implants 5.0 were used. The fracture load was measured in a universal testing machine EMIC DL2000 (10 kN load cell; 0.5 mm/min). Two-way ANOVA (retention and cusp inclination) followed by post hoc Tukey's honest significant difference test was used for the statistical analyses (a=0.05). Crowns with reduced cusp inclination exhibited significantly higher fracture load (p<0.01) than crowns with standard cusp inclination. Cemented crowns showed significantly higher fracture load (p<0.01) than screw-retained crowns. The interaction among these factors was not significant (p>0.05) for the fracture load. The sealing of SAH did not influence the fracture load of screw-retained crowns (p>0.05). In conclusion, fracture load of implant-supported metal-ceramic crowns was influenced by retention and cusp inclination, and there was no influence of the sealing of SAH.

Influence of Cusp Inclination and Type of Retention on Fracture Load of Implant-Supported Crowns

Abstract There are few informations about the influence of cusp inclination on the fracture strength of implant-supported crowns. The study aimed to evaluate the influence of cusp inclination and retention type on fracture load in implant-supported metal-ceramic single crowns. Sixty crowns were made, classified as cemented and screw-retained with screw access hole (SAH) sealed or not. Standard (33°) and reduced (20°) cusp inclinations were tested for each group (n=10). To support crowns of a mandibular second molar, analogs of external hexagon implants 5.0 were used. The fracture load was measured in a universal testing machine EMIC DL2000 (10 kN load cell; 0.5 mm/min). Two-way ANOVA (retention and cusp inclination) followed by post hoc Tukey’s honest significant difference test was used for the statistical analyses (a=0.05). Crowns with reduced cusp inclination exhibited significantly higher fracture load (p<0.01) than crowns with standard cusp inclination. Cemented crowns showed significantly higher fracture load (p<0.01) than screw-retained crowns. The interaction among these factors was not significant (p>0.05) for the fracture load. The sealing of SAH did not influence the fracture load of screw-retained crowns (p>0.05). In conclusion, fracture load of implant-supported metal-ceramic crowns was influenced by retention and cusp inclination, and there was no influence of the sealing of SAH.

Resumo Existem poucas informações sobre a influência da inclinação de cúspide na resistência à fratura de coroas implantossuportadas. O objetivo do estudo foi avaliar a influência da inclinação de cúspide e do tipo de retenção na carga de fratura de coroas unitárias metalocerâmicas implantossuportadas. Sessenta coroas foram confeccionadas, classificadas como cimentadas e parafusadas com orifício de acesso ao parafuso selado ou não. Cúspides com inclinação padrão (33°) e reduzida (20°) foram testadas para cada grupo (n=10). Para suportar as coroas de um segundo molar inferior, análogos de implante hexágono externo 5.0 foram utilizados. A carga de fratura foi mensurada em máquina de ensaios universais EMIC DL2000 (célula de carga de 10 kN; 0,5 mm/min). ANOVA dois fatores (retenção e inclinação da cúspide) seguido do pós-teste de Tukey da diferença honestamente significativa foi utilizada para análise estatística (a=0,05). Coroas com inclinação de cúspide reduzida exibiram carga de fratura significativamente maior (p>0,05) que coroas com cúspides de inclinação padrão. Coroas cimentadas apresentaram carga de fratura significativamente maior (p<0,01) que coroas parafusadas. A interação entre os dois fatores não foi significante (p>0,05) para a carga de fratura. O selamento do orifício de acesso ao parafuso não influenciou a carga de fratura das coroas parafusadas (p>0,05). Concluindo, a carga de fratura de coroas metalocerâmicas implantossuportadas foi influenciada pelo tipo de retenção e inclinação da cúspide, e não houve influência do selamento do orifício de acesso ao parafuso

Influence of Sealing of the Screw Access Hole on the Fracture Resistance of Implant-Supported Restorations.

The purpose of this study was to assess the influence of sealing of the screw access hole (SAH) on the fracture resistance of metal-ceramic implant-supported restorations. UCLA abutments were used to make 30 implant-retained mandibular molar restorations and divide equally into three groups: Group SRS: screw-retained restorations with SAH sealed; Group SRNS: screw-retained restorations with SAH not sealed; Group CR: cement-retained restorations. The following protocol was adopted to restore the SAH: the ceramic surface of the SAH was air-abraded with aluminum oxide; etched with 10% hydrofluoric acid; a silane coupling agent and a bonding agent were applied; cotton pellets were used as filling material and P-60 resin composite as restoring material. The cement-retained restorations were cemented with Rely-X U100. A metal rod with a spherical tip of 6.0 mm diameter was used to apply a vertical static load, simultaneously on the buccal and lingual incline cusps, at a crosshead speed of 0.5 mm/min until the fracture of the specimens. Data were analyzed using one-way ANOVA and Dunnet test (p<0.05) for multiples comparisons. The mode of failure was evaluated by a scanning electron microscopy (SEM). No significant difference between screw-retained restorations was found. The highest mean fracture resistance values were observed with CR group. Therefore, it was shown that SAH sealing did not influence the fracture resistance of the screw-retained restorations.

Influence of Sealing of the Screw Access Hole on the Fracture Resistance of Implant-Supported Restorations

Abstract The purpose of this study was to assess the influence of sealing of the screw access hole (SAH) on the fracture resistance of metal-ceramic implant-supported restorations. UCLA abutments were used to make 30 implant-retained mandibular molar restorations and divide equally into three groups: Group SRS: screw-retained restorations with SAH sealed; Group SRNS: screw-retained restorations with SAH not sealed; Group CR: cement-retained restorations. The following protocol was adopted to restore the SAH: the ceramic surface of the SAH was air-abraded with aluminum oxide; etched with 10% hydrofluoric acid; a silane coupling agent and a bonding agent were applied; cotton pellets were used as filling material and P-60 resin composite as restoring material. The cement-retained restorations were cemented with Rely-X U100. A metal rod with a spherical tip of 6.0 mm diameter was used to apply a vertical static load, simultaneously on the buccal and lingual incline cusps, at a crosshead speed of 0.5 mm/min until the fracture of the specimens. Data were analyzed using one-way ANOVA and Dunnet test (p<0.05) for multiples comparisons. The mode of failure was evaluated by a scanning electron microscopy (SEM). No significant difference between screw-retained restorations was found. The highest mean fracture resistance values were observed with CR group. Therefore, it was shown that SAH sealing did not influence the fracture resistance of the screw-retained restorations.

Resumo O objetivo deste estudo foi avaliar a influência do selamento do orifício de acesso ao parafuso (OAP) na resistência à fratura de coroas metalocerâmicas implantossuportadas aparafusadas. Pilares UCLA foram utilizados para fazer 30 molares inferiores implantossuportados e divididos igualmente em três grupos: Grupo AS: coroas aparafusadas com o OAP selado; Grupo ANS: coroas aparafusadas com o OAP não selado; Grupo CC: coroas cimentadas. O seguinte protocolo foi utilizado para selar o OAP: a superfície de cerâmica do OAP foi jateada com óxido de alumínio; condicionada com ácido fluorídrico a 10%; um agente silano e um adesivo dentinário foram aplicados; bolinhas de algodão foram utilizadas como material de preenchimento e a resina composta P-60 como material de restauração. As coroas cimentadas foram cimentadas com Rely-X U100. Uma haste de metal com uma ponta esférica de 6.0 mm de diâmetro foi usada para aplicar uma carga estática vertical, simultaneamente nas vertentes triturantes das cúspides linguais e vestibulares, com 0,5 mm/min velocidade do atuador até a fratura das coroas. Os dados foram analisados através de ANOVA um fator e teste de Dunnett (p<0,05) para as comparações múltiplas. O modo de falha foi avaliado por um microscópio eletrônico de varredura (MEV). Não houve diferença significativa entre restaurações aparafusadas. Os maiores valores médios de resistência à fratura foram observados com o Grupo CC. Portanto, observou-se que o selamento do OAP não influenciou a resistência à fratura das coroas aparafusadas.

Influence of three types of abutments on preload values before and after cyclic loading with structural analysis by scanning electron microscopy.

PURPOSE: To evaluate the effectiveness of three types of abutments in the maintenance of screw joint preload before and after cyclic loading as well as to observe possible microdamage in the structure of the components using a scanning electron microscope (SEM). MATERIALS AND METHODS: Forty-five external-hex implants were embedded in epoxy resin, received their respective abutments, and were randomly divided into three experimental groups (n = 15): (1) machined titanium (Ti) abutments; (2) pre-machined gold (Au) abutments; and (3) machined zirconia (ZrO(2)) abutments. The abutment screws were tightened according to the manufacturer's recommended torque. Initially, a static bending test was performed using five specimens of each group to determine the load applied in the cyclic loading test. Thus, 10 specimens of each group were used to measure the reverse torque value (preload) of the abutment screw before and after loading. A cyclic loading (0.5 × 10(6) cycles; 15 Hz) between 11 and 211 N was applied at an angle of 30 degrees to the long axis of the implants. The group means were compared using analysis of variance and the Tukey test (α = .05). RESULTS: The reverse torque analysis before cyclic loading showed no significant difference among the groups (P > .05). After cyclic loading, all preload means decreased significantly. The lowest decrease in preload was observed in the Ti group, whereas the highest decrease was observed in the ZrO(2) group, with a significant difference noted between them (P = .010). The Au group presented an intermediate decrease, with no significant difference compared to the other groups (P > .05). SEM images showed structural changes in the mating surfaces of the abutments after cyclic loading. CONCLUSION: The load application reduced the preload means significantly in all groups, and more significantly in the ZrO(2) group.

Resistência à fratura de diferentes selamentos de orifício de acesso ao parafuso de fiação e da porcela de cobertura de restaurações metalo-cerâmicas parafusadas implantossuportadas / Fracture resistance of different sealings of the screw access hole and of ceramic veneer of the metal-ceramic screw-retained implant-supported restorations

O objetivo deste estudo foi: A) avaliar a influência de diferentes materiais obturadores do canal de acesso ao parafuso sobre a resistência à fratura da resina de selamento, B) avaliar a influência do selamento do orifício de acesso ao parafuso (OAP) sobre a resistência à fratura da porcelana de cobertura. Para a confecção dos corpos-de-prova das duas partes do estudo foram usados componentes protéticos do tipo UCLA anti-rotacional (Biomet 3i) para implantes de hexágono externo com plataforma de 5,0 mm de diâmetro. Na primeira parte do estudo, foram testadas as resinas compostas fotopolimerizáveis Z100 e P60 (3M ­ ESPE) para selar o OAP, e como materiais de obturação do canal foram utilizados algodão hidrófilo, fita de politetrafluoretileno (fita veda rosca) e guta-percha. Os corpos-de-prova foram fundidos em liga de NiCr, e uma camada de 2,0 mm de espessura de porcelana feldspática foi aplicada sobre a face onde estava localizado o orifício de acesso ao parafuso. A porcelana do OAP foi jateada com óxido de alumínio, condicionada com ácido fluorídrico 10 %, e recebeu aplicação de silano e agente adesivo. Após a condensação do material obturador, o orifício foi selado com a resina composta, de acordo com o grupo experimental proposto e efetuado o teste de resistência à fratura por meio de uma força axial compressiva aplicada no centro da superfície do selamento até a fratura. Os valores foram analisados estatisticamente por meio da ANOVA um fator e teste de Tukey (p≤0,05). O melhor selamento foi observado com a resina P-60 associada ao algodão. Na segunda parte do estudo, foram confeccionadas 30 coroas metalocerâmicas implanto-suportadas, correspondentes a um molar inferior, e divididas igualmente nos seguintes grupos: 1) coroas parafusadas com o orifício de acesso selado através do protocolo de melhor resultado na primeira parte do estudo; 2) coroas parafusadas com o orifício não selado; 3) coroas cimentadas implantossuportadas. Todas as coroas foram padronizadas e submetidas ao ensaio mecânico com uma força axial compressiva concomitantemente sobre as vertentes triturantes das cúspides vestibulares e linguais até a fratura da coroa. Os dados foram analisados pela ANOVA dois fatores e teste de Dunnett para comparações múltiplas, com nível de significância de 5%. Os resultados mostraram não haver diferenças significantes entre os grupos 1 e 2, sendo que os maiores valores médios de resistência à fratura foram obtidos pelo grupo 3. As conclusões do estudo foram as seguintes: o material obturador influenciou na resistência à fratura da resina composta utilizada para selar o OAP; o selamento do OAP não aumentou a resistência à fratura da porcelana de cobertura das coroas parafusadas

The purposes of this study were: A) to assess the influence of filling materials on the fracture resistance of resin composites used to seal the SAH; B) to assess the influence of sealing of the (SAH) on the fracture resistance of metal-ceramic (MC) screw-retained implant-supported restorations. An UCLA plastic abutment to external hexagon implant with a diameter of 5.0 mm was used to perform the experimental samples of the two research parts. In the first part, the resin composite, Z-100 and P-60, were used to seal the SAH, and the filling materials used were cotton pellets, polytetrafluorethylene tape and gutta-percha. The experimental samples were cast in NI-Cr metal alloy a ceramic layer with 2.0 mm of diameter was applied on the surface where is placed the SAH. The ceramic surface of the SAH was airabraded with aluminum oxide, etched with 10% hydrofluoric acid, and a silane coupling agent and a bonding agent were applied. After condensation of the filling materials, the SAH was sealed with resin composite and an axial compression load was applied at the central of the sealing restoration until the fracture. Data were analyzed using two-way ANOVA and Tukey HSD test (p < 0.05). The best sealing was with P60 associated with absorbent cotton. In the second part, were performed 30 implant-supported restorations divided equally into 3 groups: 1) screw-retained restorations with restored screw access hole; 2) screw-retained restorations with unrestored screw access hole; 3) cement-retained restorations. All restorations were standardized and underwent to an axial compression load applied simultaneously on the buccal and lingual incline cusps until fracture. Data were analyzed using one-way ANOVA and Dunnett test for multiple comparisons, and the statistical significance was set at p < 0,05. No significant difference between screw-retained restorations was found. The highest mean fracture resistance values were observed with group 3. The following conclusions were reached: the filling material influenced on fracture resistance of resin composite used to seal the SAH; the sealing of the SAH did not increase the porcelain fracture resistance of the screw-retained crowns

Antimicrobial activity of disinfectant agents incorporated into type IV dental stone.

PURPOSE: This study evaluated the antimicrobial activity of two disinfectant agents, 2% chlorhexidine digluconate solution (CHX) and 98% chlorhexidine hydrochloride powder (HYD), incorporated into type IV dental stone at the time of mixing. MATERIAL AND METHODS: Agar diffusion test was used for the following microorganisms: Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Candida albicans. The specimens were grouped in: (1) dental stone mixed with sterile distilled water; (2) paper disc soaked with CHX; (3) dental stone mixed with CHX; and (4) dental stone with incorporation of HYD, in 1% proportion of the dental stone mass and mixed with sterile distilled water. The culture medium was inoculated with microbial suspensions 1 and 24 h after pouring of the dental stone. The antimicrobial activity was evaluated by the average diameter of microbial growth inhibition zones. The data were analysed with a nested anova (p < 0.05) and Tukey test for specific comparisons. RESULTS: The disinfectant agents demonstrated antimicrobial activity against all microorganisms, with the exception of C. albicans, against which the CHX was ineffective in two periods of analysis. Significant differences between disinfectants were found with all microorganisms. CONCLUSION: The disinfectant agents analysed were effective against most of the microorganisms tested, except C. albicans.

Influence of surface treatments on the flexural strength of denture base repair.

OBJECTIVE: The purpose of this study was to evaluate the flexural strength of repairs made with autopolymerising acrylic resin after different treatments of joint surfaces. MATERIAL AND METHODS: Fifty rectangular specimens were made with heat-polymerised acrylic resin and 40 were repaired with autopolymerising acrylic resin following joint surface treatments: group 1 (intact specimens), group 2 (chemical treatment: wetting with methyl-methacrylate for 180 s), group 3 (abraded with silicon carbide paper), group 4 (abraded and wetting with methyl-methacrylate for 180 s) and group 5 (without surface treatment). The flexural strength was measured by a three-point bending test using a universal testing machine with a 100 Kgf load cell in the centre of repair at 5 mm/min cross-head speed. All data were analysed using one-way anova and Tukey HSD test for multiple comparisons (p < 0.05). RESULTS: Among repaired specimens, groups 2 and 4 had 66.53 ± 3.4 and 69.38 ± 1.8 MPa mean values and were similar. These groups had superior flexural strength than groups 3 and 5 that were similar and had 54.11 ± 3.4 and 51.24 ± 2.8 MPa mean values, respectively. Group 1 had a mean value of 108.30 ± 2.8 MPa being the highest result. CONCLUSION: It can be concluded that the treatment of the joint surfaces with methyl-methacrylate increases the flexural strength of denture base repairs, although the strength is still lower than that observed for the intact denture base resin. Abrasion with sandpaper was not able to influence the flexural strength of repaired denture bases.

Rahabilitación oral sobre implantes instalados por medio de la técnica sin colgajo (flapless) y carga inmediata / Oral rehabilitation with flapless surgical technique and immediate implant loading

La rehabilitación oral con implantes osteointegrados es un tratamiento que está bien documentado y con un alto porcentaje de éxito. Sin embargo, exigencias relacionadas al tiempo de tratamiento y a la técnica quirúrgica fueron surgiendo. En ese contexto, el procedimiento de carga inmediata, en el cual la prótesis dental es instalada inmediatamente después del procedimiento quirúrgico se tornó una práctica constante. A pesar de que la carga inmediata ha sido un importante avance, procedimientos mínimamente invasivos, como la instalación de implantes con la técnica directa, sin desplazamiento del colgajo mucoperiostio (flapless) vienen siendo cada vez más realizados. La asociación de la carga inmediata con la técnica directa o de flapless mejora la aceptación de los pacientes y profesionales, pues no hay necesidad de sutura, además de reducir el edema, la hemorragia durante y después de la cirugía, el dolor post-operatorio, el tiempo quirúrgico, la incomodidad y hematoma, reduciendo también la necesidad de medicación post-operatoria. Esas características facilitan las etapas de rehabilitación inmediatamente después de la colocación de los implantes, colaborando con el trabajo del técnico protésico. De esa forma, la propuesta de este trabajo es presentar un caso clínico de rehabilitación oral con implantes osteointegrados y prótesis fijas en ambas arcadas, donde se realizó la técnica directa seguida por carga inmediata, relatando el diagnóstico, planificación, procedimientos quirúrgico/protésicos y seguimiento de 20 meses

The oral rehabilitation with osseointegrated implants is a well-documented treatment with high rate of success. Nevertheless, demands related to treatment time and surgical technique began to appear. In this context, the procedure of immediate loading in which the dental prosthesis is placed right after implant surgery has become a constant practice. Although immediate loading has been an important advance, minimally invasive procedures, such as implant placement without raising a mucoperiosteal flap (flapless) are increasingly being performed. Association of immediate loading with the flapless technique improves acceptance by patients and professionals, because no suturing is required. Moreover, it reduces swelling, bleeding during and after surgery, postoperative pain, surgery time, discomfort and hematoma, as well as the need for postoperative medication. These characteristics ease the stages of rehabilitation soon after implant placement, cooperating with prosthodontist's work. Thus, the proposal of this study is to present a clinical case of oral rehabilitation with osseointegrated implants and fixed prosthesis in both arches, in which the flapless technique was applied, followed by immediate loading. It will discuss the diagnosis, prosthetic planning, surgical/prosthodontic procedures and follow-up for 20 months

Flexural strength of acrylic resin repairs processed by different methods: water bath, microwave energy and chemical polymerization.

UNLABELLED: Denture fractures are common in daily practice, causing inconvenience to the patient and to the dentists. Denture repairs should have adequate strength, dimensional stability and color match, and should be easily and quickly performed as well as relatively inexpensive. OBJECTIVE: The aim of this study was to evaluate the flexural strength of acrylic resin repairs processed by different methods: warm water-bath, microwave energy, and chemical polymerization. MATERIAL AND METHODS: Sixty rectangular specimens (31x10x2.5 mm) were made with warm water-bath acrylic resin (Lucitone 550) and grouped (15 specimens per group) according to the resin type used to make repair procedure: 1) specimens of warm water-bath resin (Lucitone 550) without repair (control group); 2) specimens of warm water-bath resin repaired with warm water-bath; 3) specimens of warm water-bath resin repaired with microwave resin (Acron MC); 4) specimens of warm water-bath resin repaired with autopolymerized acrylic resin (Simplex). Flexural strength was measured with the three-point bending in a universal testing machine (MTS 810 Material Test System) with load cell of 100 kgf under constant speed of 5 mm/min. Data were analyzed statistically by Kruskal-Wallis test (p<0.05). RESULTS: The control group showed the best result (156.04±1.82 MPa). Significant differences were found among repaired specimens and the results were decreasing as follows: group 3 (43.02±2.25 MPa), group 2 (36.21±1.20 MPa) and group 4 (6.74±0.85 MPa). CONCLUSION: All repaired specimens demonstrated lower flexural strength than the control group. Repairs with autopolymerized acrylic resin showed the lowest flexural strength.

Flexural strength of acrylic resin repairs processed by different methods: water bath, microwave energy and chemical polymerization

Denture fractures are common in daily practice, causing inconvenience to the patient and to the dentists. Denture repairs should have adequate strength, dimensional stability and color match, and should be easily and quickly performed as well as relatively inexpensive. OBJECTIVE: The aim of this study was to evaluate the flexural strength of acrylic resin repairs processed by different methods: warm water-bath, microwave energy, and chemical polymerization. MATERIAL AND METHODS: Sixty rectangular specimens (31x10x2.5 mm) were made with warm water-bath acrylic resin (Lucitone 550) and grouped (15 specimens per group) according to the resin type used to make repair procedure: 1) specimens of warm water-bath resin (Lucitone 550) without repair (control group); 2) specimens of warm water-bath resin repaired with warm water-bath; 3) specimens of warm water-bath resin repaired with microwave resin (Acron MC); 4) specimens of warm water-bath resin repaired with autopolymerized acrylic resin (Simplex). Flexural strength was measured with the three-point bending in a universal testing machine (MTS 810 Material Test System) with load cell of 100 kgf under constant speed of 5 mm/min. Data were analyzed statistically by Kruskal-Wallis test (p<0.05). RESULTS: The control group showed the best result (156.04±1.82 MPa). Significant differences were found among repaired specimens and the results were decreasing as follows: group 3 (43.02±2.25 MPa), group 2 (36.21±1.20 MPa) and group 4 (6.74±0.85 MPa). CONCLUSION: All repaired specimens demonstrated lower flexural strength than the control group. Repairs with autopolymerized acrylic resin showed the lowest flexural strength.

Effect of incorporation of disinfectant solutions on setting time, linear dimensional stability, and detail reproduction in dental stone casts.

PURPOSE: The aim of this paper was to analyze the influence of incorporation of disinfectants during the cast die stone-setting time. Setting time, linear dimensional stability, and reproduction details on casts were measured. MATERIALS AND METHODS: Die stone type IV specimens with disinfection solutions (sodium hypochlorite 1%, glutaraldehyde 2%, chlorhexidine 2%) were incorporated in two concentrations (50%, 100%). The detail reproduction, dimensional stability, and setting time were tested in accordance with ADA recommendations. RESULTS: Disinfecting solutions promoted an increase in setting time compared to control; sodium hypochlorite was responsible for the highest setting time. The addition of undiluted sodium hypochlorite 1.0% led to contraction during setting, but the groups with 50% diluted sodium hypochlorite 1.0% and undiluted chlorhexidine 2.0% resulted in intermediate values compared to the other groups, thus matching the control. The others did not demonstrate any effect on expansion. For detail reproduction, it was observed that the control group presented results similar to the others, except those where sodium hypochlorite was added. CONCLUSIONS: The addition of sodium hypochlorite in both dilutions significantly altered, negatively, all the evaluated properties. But the addition of glutaraldehyde and chlorhexidine did not promote any significant alterations in the evaluated properties.

A atividade antimicrobiana de agentes desinfetantes incorporados ao gesso tipo IV / The antimicrobial activity of disinfectant agents incorporated into type IV dental stone

Vários protocolos de desinfecção podem ser usados para romper a cadeia de infecção cruzada entre o consultório odontológico e o laboratório de prótese. A inclusão de agentes antimicrobianos à composição do gesso ou a manipulação do gesso com soluções desinfetantes podem ser usados com esta finalidade. O propósito deste estudo foi avaliar a atividade antimicrobiana de dois agentes desinfetantes (digluconato de clorexidina 2% e cloridrato de clorexidina 98%) incorporados ao gesso IV (FujiRock - GC Europe, Leuven, Bélgica) durante sua manipulação. No teste microbiológico de difusão em Agar foram utilizados os seguintes microorganismos: Escherichia coli, Staphylococcus aureus, Bacilus subtilis e Candida albicans. Amostras com 5 mm de diâmetro e 3 mm de espessura foram separadas em quatro grupos: 1) gesso manipulado com água destilada esterilizada (controle positivo); 2) discos de papel embebidos com solução de digluconato de clorexidina 2% (controle negativo); 3) gesso manipulado com solução de digluconato de clorexidina 2%; 4) gesso com a incorporação de cloridrato de clorexidina 98% em pó, na proporção de 1% da massa do gesso, e manipulado com água destilada esterilizada. Após 1 hora e 24 horas do vazamento do gesso, as amostras foram posicionadas em placas de Petri com meios de cultura específicos inoculados com as suspensões microbianas. A atividade antimicrobiana dos desinfetantes foi avaliada pelo diâmetro médio dos halos de inibição do crescimento microbiano. Os valores foram analisados pela ANOVA Aninhada (p<0,05) e teste de Tukey para comparações específicas. Os resultados encontrados demonstraram que os agentes desinfetantes analisados apresentaram atividade antimicrobiana quando misturados ao gesso, com exceção para Candida albicans, na qual não houve efeito da solução de clorexidina nos dois períodos de análise. Sobre os dois períodos de análise, houve diferença significante somente com o controle negativo para a Escherichia coli

Many protocols for disinfection procedures can be used to break the chain of cross-contamination between dental office and dental laboratory. The inclusion of antimicrobial agent to the composition of gypsum or the manipulation of gypsum with disinfectant substances can be used to that aim. The purpose of this study was to evaluate the antimicrobial activity of two disinfectant agents (2% chlorhexidine digluconate and 98% chlorhexidine hydrochloride) incorporated into type IV dental stone (FujiRock - GC Europe, Leuven, Belgium) at the time of mixing. The microbiological test used was the Agar diffusion test to the following microorganisms: Escherichia coli, Staphylococcus aureus, Bacilus subtilis and Candida albicans. Samples of 5 mm in diameter and 3 mm in length were separated in four groups: 1) dental stone mixed with sterile distilled water (positive control); 2) paper disk soaked with solution of 2% chlorhexidine digluconate (negative control); 3) dental stone mixed with solution of 2% chlorhexidine digluconate; 4) dental stone with incorporation of chlorhexidine hydrochloride 98% powder, in proportion of 1% of the dental stone mass, and mixed with sterile distilled water. The samples were placed, 1 hour and 24 hours after pouring of dental stone, in Petri plates with specific culture medium wich were inoculated with the microbial suspensions. The antimicrobial activity of disinfectant was evaluated by the average diameter of microbial growth inhibition zones. The data were analyzed with a Nested ANOVA (p<0,05) and Tukey test for specific comparisons. The disinfectant agents analyzed demonstrated antimicrobial effect against microorganisms used in this study, in exception to Candida albicans, against wich there was not effect from chlorhexidine digluconate at two periods of analysis. Significant difference between disinfectantes were found to all microrganisms. About two periods of analysis, there was significant difference only with negative control to the Escherichia coli. The disinfectant agents derived from chlorhexidine incorporated into dental stone at the time of mixing were effective against the most microorganisms tested, except against Candida albicans