Failure load of milled, 3D-printed, and conventional chairside-dispensed interim 3-unit fixed dental prostheses.

STATEMENT OF PROBLEM: New techniques and materials for the laboratory fabrication of interim fixed dental prostheses have gained in popularity, yet how their failure strengths compare with conventional chairside materials is unclear. PURPOSE: The purpose of this in vitro study was to compare the strength of computer-aided design and computer-aided manufacturing (CAD-CAM) milled polymethylmethacrylate (PMMA) or 3-dimensionally (3D) printed bis-acryl interim fixed dental prostheses with a traditional chairside-dispensed autopolymerizing bis-acryl prosthesis while taking into account the effect of loading rate and storage time. MATERIAL AND METHODS: A dentiform mandibular second premolar and second molar with a first molar pontic were prepared and scanned. Three groups of 3-unit interim fixed dental prostheses were fabricated: milled PMMA, 3D-printed bis-acryl, and chairside-dispensed autopolymerizing bis-acryl. The interim prostheses were evaluated for fit with a silicone disclosing material and cemented onto 3D-printed resin dies. The specimens were stored in 100% humidity at 37 °C. After 1 or 30 days of storage, the cemented interim prostheses were loaded to failure in a universal testing machine at 1 or 10 mm/min (n=15/group). Failure loads were analyzed by 3-way analysis of variance and multiple comparisons (α=.05). RESULTS: Mean ±standard deviation failure loads ranged from 363 ±93 N (3D-printed bis-acryl, 30 days, 1 mm/min) to 729 ±113 N (milled PMMA, 24 hours, 1 mm/min). Loading rate did not significantly affect failure load of the interim prostheses (P=.306). After 30 days of storage in 100% humidity, the failure load of milled PMMA and 3D-printed bis-acryl interim prostheses decreased significantly, but the chairside autopolymerizing bis-acryl prostheses were not affected. After 30 days of storage, the failure loads of milled PMMA and chairside autopolymerizing bis-acryl were not significantly different. CONCLUSIONS: Regardless of loading rate, interim fixed dental prostheses from milled PMMA had the highest initial strength 1 day after storage. Thirty days of exposure to humidity, however, reduced the strength of the CAD-CAM-manufactured interim prostheses, whereas the traditional chairside prostheses retained their strength.

Accuracy of Additively Manufactured and Milled Interim 3-Unit Fixed Dental Prostheses.

PURPOSE: To investigate the accuracy of additive manufacturing (AM) by means of internal fit of fixed dental prostheses (FDPs) fabricated with two AM technologies using different resins and printing modes (validated vs nonvalidated) compared to milling and direct manual methods. MATERIAL AND METHODS: Sixty 3-unit interim FDPs replacing the first mandibular molar were divided into 6 groups (n = 10): manual (Protemp 4), milled (Telio-CAD), and AM groups were subdivided based on AM technology (direct light processing (Rapidshape P30 [RS]) and stereolithography (FormLabs 2 [FL])) and the polymer type (P-Pro-C&B [St] and SHERAprint-cb [Sh]) (RS-St, RS-Sh, FL-St, FL-Sh). Validated (RS-Sh and RS-St) or nonvalidated (FL-St and FL-Sh) modes were adopted for AM. The specimens were scanned to 3D align (GOM inspect) according to the triple scan method. The internal space between the FDPs and preparation surfaces in four sites (marginal, axial, occlusal, and total) was measured using equidistant surface points (GOM Inspect). Statistical analysis was done using Kruskal Wallis and Dunn post-hoc tests. (α = 0.05). RESULTS: One AM group (FL-Sh) and milling exhibited better adaptation compared to manual and RS-St at molar site (p < 0.05). FDPs with St resin (FL-St and RS-St) displayed bigger marginal space than milled, FL-Sh, and RS-Sh. The nonvalidated printing mode showed better mean space results (p < 0.05) with higher predictability and repeatability (p < 0.001). CONCLUSIONS: The AM interim FDPs tested provided valid alternatives to the milled ones in regard to their accuracy results. The printing mode, resin, and the AM technology used significantly influenced the manufacturing accuracy of interim FDPs, particularly at the marginal area. The nonvalidated printing mode with lower-cost 3D printers is a promising solution for clinical applications.

Strength and stiffness of interim materials and interim fixed dental prostheses when tested at different loading rates.

STATEMENT OF PROBLEM: How the loading rate might affect the mechanical properties of interim materials and interim fixed dental prostheses is unclear. PURPOSE: The purpose of this in vitro study was to compare the material stiffness, material strength, and structural strength of interim 3-unit fixed dental prostheses fabricated from 3 interim materials when stressed at different loading rates. MATERIAL AND METHODS: Bar-shaped specimens and anatomically correct interim 3-unit fixed dental prostheses with a modified-ridge lap pontic were fabricated from polyethyl methacrylate resin (Trim) and 2 bis-acrylic composite resins (TempSmart; Integrity) (n=10). Flexural modulus and strength of the bar specimens, representing material stiffness and strength, were determined with a 4-point bend test in a universal testing machine. The structural strength of the prosthesis was assessed from the failure load from a vertical force applied on the occlusal surface of the pontic. Three loading rates, 0.5, 5, or 10 mm/min, were evaluated. Results were statistically analyzed with 2-way analysis of variance and multiple comparisons (α=.05). RESULTS: Loading rate and material significantly affected flexural modulus, flexural strength, and structural strength (P<.05). Increasing loading rate significantly increased the flexural modulus of all materials (P<.05), but the effect of loading rate on the flexural strength of bis-acrylic composite resins was mostly insignificant. Polyethyl methacrylate specimens did not fracture when loaded at 0.5 or 5 mm/min, and the interim fixed dental prostheses made from polyethyl methacrylate did not fracture at the 0.5 mm/min loading rate. Dual-polymerizing bis-acrylic composite resin had significantly higher flexural modulus and strengths than autopolymerizing bis-acrylic composite resin. CONCLUSIONS: Polyethyl methacrylate resin had the lowest stiffness among the interim materials tested and did not fracture but excessively deformed at the low loading rate. Dual-polymerizing bis-acrylic composite resin consistently had higher stiffness and material strength and provided higher structural strength than the autopolymerizing bis-acrylic composite resin. Loading rate significantly affected the mechanical properties of polyethyl methacrylate resin (P<.05), but the effect was indistinct for the bis-acrylic materials.

The effect of surface treatments on the color stability of CAD-CAM interim fixed dental prostheses.

STATEMENT OF PROBLEM: Additive manufacturing or 3D printing is gaining popularity in dentistry, including for interim fixed dental prostheses (IFDPs). However, evidence regarding the color stability of 3D-printed IFDPs is lacking. PURPOSE: The purpose of this in vitro study was to investigate whether different surface treatments could affect the color stability of milled and 3D-printed IFDPs after simulated physiological aging. MATERIAL AND METHODS: Forty milled IFDPs were fabricated with a 5-axis dental mill (DWX-51D; Roland DGA Corp) from polymethyl methacrylate disks (Temp Esthetic 98, A3.5, 98.5×16 mm; Harvest Dental Products, LLC). Forty 3D-printed IFDPs were fabricated with an in-office digital light processing 3D printer (MAX; Asiga) and light-polymerizing resin (NextDent Crown & Bridge A3.5; NextDent B.V). All milled and 3D-printed IFDPs were allocated into 4 different groups (n=10), according to different surface treatments: Control, Polish, Optiglaze, and Skinglaze. In the Control group, no surface treatment was applied to the IFDPs. For the Polish group, IFDPs were finished and polished with aluminum oxide finishers/polishers (Enhance PoGo Complete Kit; Dentsply Sirona). For the Optiglaze and Skinglaze groups, specimens were first finished and polished and prepared with additional light-polymerizing protective coatings (Optiglaze; GC America Inc, or New Outline Skin Glaze; anaxdent North America). Shade measurements were recorded with a digital spectrophotometer (Vita Easyshade V; VITA North America) before and after the thermocycling for the color stability comparisons. The effects of interim prosthesis type and surface treatments on ΔE∗, ΔL∗, Δa∗, and Δb∗ were examined using 2-way analysis of variance (ANOVA), and ΔE∗ was considered as the primary outcome variable. Post hoc pairwise comparisons were performed by using the Tukey honestly significant difference (HSD) method (α=.05 for all tests). RESULTS: Milled IFDPs had significantly smaller ΔE∗ than 3D-printed prostheses for the Control group only (P<.001). Within the milled IFDPs, Optiglaze group (mean ±standard deviation, 1.01 ±0.38) had significantly lower ΔE∗ than all the other surface treatments groups (Control group: 2.38 ±0.44, P<.001; Polish group: 1.83 ±0.51, P=.025; and Skinglaze group: 1.85 ±0.78, P=.021). Within the 3D-printed IFDPs, the Control group (3.83 ±0.71) had significantly larger ΔE∗ than all other surface treatments (Polish group: 2.66 ±0.89, P=.018; Skinglaze group: 1.40 ±0.73, P<.001; and Optiglaze group: 1.37 ±0.67, P<.001). The Polish group had significantly higher ΔE∗ than Skinglaze group (P=.009) and Optiglaze group (P=.007), while Skinglaze and Optiglaze groups were not significantly different from each other (P=1.000). CONCLUSIONS: For the milled IFDPs, only the nano-filled, light-polymerizing protective coating significantly lowered color changes after thermocycling simulating 6 months of intraoral physiological aging. For the 3D-printed IFDPs, surface polishing and both light-polymerizing protective coating agents all significantly reduced color changes of the prostheses after thermocycling. The protective effect of light-polymerizing coating agents was more substantial.

Impacto dos selantes de superfície na preservação das propriedades mecânicas de polímeros de PMMA para CAD/CAM, submetidos a desafio erosivo e termociclagem / Impact of surface sealants on the preservation of mechanical properties of PMMA polymers for CAD/CAM, subjected to erosive challenge and thermocycling

A aplicação de selantes de superfície poderá ajudar na diminuição da degradação superficial dos blocos de PMMA para CAD/CAM frente aos desafios de absorção de água, variação de temperatura e desafio erosivo causada pelo suco gástrico (frequente em pacientes com refluxo gastroesofágico (DRGE) ou bulimia. Contudo, poucos estudos na área odontológica foram realizados com essas variáveis, sendo necessário o aprofundamento sobre o assunto. Diante disso, o objetivo deste estudo foi avaliar o impacto de diferentes selantes de superfície (Biscovel LV e Palaseal) na preservação das propriedades mecânicas de polímero de PMMA para CAD/CAM, submetidos a termociclagem (T1 - 5.000 ciclos, de 5 e 55oC ; T2 ­ 10.000 ciclos, de 5 e 55oC) e desafio erosivo (DE1 - imersão em HCl 5% (pH=2,0) durante 45 horas e DE2- 91 horas), por meio da rugosidade de superfície (Ra), microdureza Knoop (MK), resistência flexural (RF) e módulo de elasticidade (ME). Foram confeccionados 90 espécimes quadrados (10x10x3 mm) para as análises de Ra e MK e 180 espécimes retangulares (25x2x2mm) para as análises de RF e ME. Os espécimes foram divididos em grupos (n=10) de acordo com o tratamento de superfície e envelhecimento. Os polimentos realizados foram: PA - pontas de borracha Astropol; PA+SB - polimento com PA + aplicação de selante de superfície Biscover LV e PA+SP - polimento com PA + aplicação de selante de superfície Palaseal. As análises foram realizadas após os tratamentos de superfície e após os períodos dos envelhecimentos. Os dados obtidos foram submetidos ao ANOVA (2 fatores), teste Bonferroni (α=0,05) e a análise de regressão linear simples. Na análise de Ra, em todos os períodos de termociclagem o grupo PA obteve os maiores valores de Ra e PA+SP os menores, com diferença significativa entre eles (p< 0.05). De acordo com a análise de regressão linear, todos os grupos apresentaram tendência linear crescente. Já após DE1 e DE2 os três grupos diferiram estatisticamente entre si (p< 0.05), sendo classificados em ordem crescente de rugosidade em PA+SP < PA+SB< PA. O grupo PA+SP manteve os valores de Ra no decorrer dos períodos de análises. Para RF, ocorreu diminuição significativa dos valores de RF do grupo PA após T1 e T2, diferindo estatisticamente dos demais grupos (p< 0.05). O desafio erosivo diminuiu de forma significante (p< 0.05) os valores de RF dos grupos PA e PA+SP após DE1 e, do grupo PA+SB após DE2. Não houve diferenças significativas nas análises de MK e ME, independente dos tratamentos de superfície e envelhecimentos. Conclui-se que os selantes de superfície foram capazes de preservar a rugosidade de superfície e resistência flexural de polímero de PMMA para CAD/CAM submetidos a termociclagem ou desafio erosivo(AU)

The application of surface sealants can help to reduce the surface degradation of PMMA blocks for CAD/CAM in the face of water absorption challenges, temperature variation and erosive challenge caused by gastric juice (common in patients with gastroesophageal reflux (DRGE) or bulimia. However, few studies in the field of dentistry have been conducted with these variables, requiring a more in-depth look at the subject. Therefore, the aim of this study was to evaluate the impact of different surface sealants (Biscovel LV and Palaseal) on the preservation of mechanical properties of PMMA polymer for CAD/CAM, subjected to thermocycling (T1 - 5,000 cycles, from 5 and 55oC; T2 - 10,000 cycles, from 5 to 55oC) and erosive challenge (DE1 - immersion in 5% HCl (pH=2.0) for 45 hours and DE2-91 hours), through surface roughness (Ra), Knoop microhardness (MK), flexural strength (RF) and modulus of elasticity (ME). The Ra and MK analyzes and 180 rectangular specimens (25x2x2mm) for the RF and ME analyses. Specimens were divided into groups (n=10) according to surface treatment and aging. The polishes performed were: PA - Astropol rubber tips; PA+SB - PA polish + application of Biscover LV surface sealant and PA+SP - polish with PA + application of Palaseal surface sealant. Analyzes were performed after surface treatments and after aging periods. The data obtained were submitted to ANOVA (2 factors), Bonferroni test (α=0.05) and simple linear regression analysis. In the analysis of Ra, in all thermocycling periods, the PA group had the highest values of Ra and PA+SP the lowest, with a significant difference between them (p< 0.05). According to the linear regression analysis, all groups showed an increasing linear trend. After DE1 and DE2, the three groups differed statistically from each other (p< 0.05), being classified in ascending order of roughness in PA+SP < PA+SB < PA. The PA+SP group maintained the Ra values throughout the analysis periods. For RF, there was a significant decrease in the RF values of the PA group after T1 and T2, differing statistically from the others groups (p< 0.05). The erosive challenge significantly decreased (p< 0.05) the RF values of the PA and PA+SP groups after DE1 and of the PA+SB group after DE2. There were no significant differences in the MK and ME analyses, regardless of surface treatments and aging. It was concluded that the surface sealants were able to preserve the surface roughness and flexural strength of PMMA polymer for CAD/CAM submitted to thermocycling or erosive challenge(AU)

Effect of different surface treatment methods on the shear bond strength of orthodontic brackets to temporary crowns.

INTRODUCTION: The number of adult patients seeking orthodontic treatment has been consistently increasing. Since the placing of the final restoration must be postponed until the completion of the orthodontic treatment, provisional restoration is recommended for the duration of the orthodontic treatment. These surfaces have special chemical properties, which necessitate the orthodontists to prepare the bonding area with special measures. METHODS: Polycarbonate and polymethylmethacrylate (PMMA) crowns (n=80) were randomly subdivided into 4 groups. Conditioning methods were grinding, sandblasting, CO2 laser and methyl methacrylate application. Samples underwent SBS testing. A scanning electron microscope (SEM) analysis was carried out. The data was analysed with ANOVA, Student t-test and Post-hoc test. Adhesive remnant index (ARI) was analysed with Chi2 test. RESULTS: In all surface treatments, the mean Shear Bond Strength (SBS) of PMMA was significantly higher than that of polycarbonate (P<0.001). In the polycarbonate groups, there was a significant difference between the mean SBS of the four treatment methods (P<0.001). However, there were no significant differences in PMMA group (P=0.076). In both crown materials, the mode of the failure was adhesive type, regardless of the conditioning method (P>0.05). CONCLUSIONS: PMMAs rendered higher bond strength than polycarbonates. In PMMA, all the surface treatment methods resulted in acceptable bond strength. However, if bonding the brackets to polycarbonate crown is needed, other conditioning methods are preferred over CO2 laser.

Precise Reproduction of Soft Tissue Structure around the Pontic Area Using Computer-Aided Design and Manufacturing.

Reproducing soft tissue contours around a pontic area is important for the fabrication of an esthetic prosthesis, especially in the anterior area. A gingival model that precisely replicates the soft tissue structure around the pontic area can be easily obtained by taking a pick-up impression of an interim fixed dental prosthesis. After a working cast is fabricated using the customary technique, the pick-up model is superimposed onto the working model for the pontic area using computer-aided design and manufacturing (CAD/CAM). A definitive restoration using this technique would be well adapted to the pontic base, which is formed by the interim prosthesis.

Staged extractions and implant placement in a periodontally compromised patient: A clinical report.

Staging the extraction of selected teeth in a periodontally compromised patient during complete mouth rehabilitation has advantages, including avoiding a transitional complete denture, keeping the patient with a fixed prosthesis throughout the treatment without the need to immediately load the implants, maintaining the interdental papillae, and providing comfort for the patient. The need for a multistep extended treatment and additional cost are the main disadvantage of this approach. This clinical report describes the clinical steps and follow-up of a staging approach and implant placement in a periodontally compromised patient with excessive gingival display to achieve a good functional and esthetic result.

Biomechanical development and evaluation of a new framework for all-on-four rehabilitation / Desenvolvimento e avaliação biomecânica de uma nova infraestrutura para reabilitações "all-on-four"

Abstract Introduction For complete rehabilitation of fully edentulous mandibles, the option for immediate loading determines the use of temporary prostheses that splint the installed implants. Although temporary prostheses with reinforcement provide rehabilitations with biomechanical benefits, the non-adoption of this recommendation coexists in different studies on immediate restorations. Objective This study evaluates a type of prosthesis to restore jaws by the all-on-four concept. Material and method: The mechanical behavior of prostheses with the modified framework was evaluated in vitro, under a cantilever mechanical unilateral bending test. Two representative groups were included in the all-on-four concept, with a G1 test group (n = 10) containing modified frameworks and a G2 control group (n = 10) that included full acrylic prostheses. The samples were submitted to thermal cycling with 500 cycles (5° ± 2 °C for 30 s, and 55° ± 2° for 30 s) and to the mechanical bending test on the cantilever. Result The Mann-Whitney test revealed a significant difference between G1 and G2 (p <0.001). In the descriptive evaluation, G1 averaged 830.50 N until the initial resin fracture, while the control group presented a mean of 403.58N. The maximum resistance until complete fracture was recorded in G1, with a mean of 903.03N, while in G2, a mean of 435.20N was recorded. The linear vertical component of the flexion was 0.68 mm and 0.39 mm until the initial fracture of the bar, respectively for G1 and G2. Conclusion The modified framework for the all-on-four protocol determined better mechanical performance when compared to the same full acrylic prosthesis model.

Resumo Introdução Para reabilitação de mandíbulas totalmente edêntulas, a opção por carga imediata determina a utilização de próteses provisórias que esplintem os implantes instalados. Apesar de provisórias com reforço proverem as reabilitações com benefícios biomecânicos, a não adoção desta indicação coexiste em diferentes estudos sobre restaurações imediatas. Objetivo Este estudo avaliou um tipo de prótese para reabilitar mandíbulas pelo conceito "all-on-four". Material e método: Foi avaliado, in-vitro, o comportamento mecânico de próteses com a infraestrutura modificada, sob ensaio mecânico de flexão unilateral em cantilever. Foram avaliados dois grupos representativos para o conceito "all-on-four", sendo um grupo teste G1 (n = 10) contendo próteses com infraestrutura modificada e outro controle G2 (n = 10) que incluiu próteses totalmente acrílicas. As amostras foram submetidas à ciclagem térmica com 500 ciclos (5° ± 2 °C por 30 segundos e 55° ± 2 °C pelo mesmo tempo) e submetidas ao ensaio mecânico à flexão sobre o cantilever. Resultado O teste de Mann-Whitney revelou diferença significativa entre G1 e G2 (p<0,001). Na avaliação descritiva, G1 mostrou média de 830,50 N até a fratura inicial em resina e o grupo controle apresentou média de 403,58N. A resistência máxima até a fratura completa foi de 903,03 N para G1 e para G2 de 435,20 N. O componente vertical linear de flexão foi 0,68 mm e 0,39 mm até a fratura inicial da barra, respectivamente para G1 e G2. Conclusão A infraestrutura modificada para o protocolo "all-on-four" proporcionou melhor desempenho mecânico quando comparado ao mesmo modelo de prótese totalmente acrílico.

Caracterização superficial e eficácia antibiofilme no uso de digluconato de clorexidina a 0,12% sobre resinas utilizadas na confecção de restaurações provisórias contemporâneas, com e sem a aplicação de glaze fotopolimerizável: estudo in situ / Surface characterization and antibiofilm efficacy in the use of 0,12% chlorhexidine digluconate on resins used in the preparation of contemporary provisional restorations, with and without application of light-curing glaze: in situ study

Durante a reabilitação com próteses fixas, o uso de provisórios é importante para que se alcance o sucesso clínico e a longevidade da prótese definitiva, mantendo a saúde e protegendo os tecidos dentais e periodontais. O objetivo deste estudo foi avaliar a estabilidade de cor, microdureza, rugosidade e energia livre de superfície de resinas de restaurações provisórias, com e sem a aplicação de glaze fotopolimerizável, e avaliar a eficácia antibiofilme do digluconato de clorexidina a 0,12% sobre as mesmas. Para isso, foram confeccionadas amostras de resina de Bis-Acril (Protemp 4, 3M ESPE, São Paulo, Brasil) e de resina acrílica ativada quimicamente (RAAQ) (Dencor, Artigos Odontológicos Clássico LTDA, São Paulo, Brasil), de forma que, apenas metade dessas amostras foi submetida ao polimento químico com glaze fotopolimerizável. Essas amostras foram posicionadas em dispositivos palatinos contendo 4 nichos (1 RAAQ sem glaze, 1 RAAQ com glaze, 1 Bis-Acril sem glaze, 1 Bis-Acril com glaze), utilizados por voluntários (n=20). As fases experimentais foram: Os voluntários usaram o dispositivo contendo as amostras do grupo controle, durante dias, sendo realizada aplicação de sacarose 30% sobre as amostras. Posteriormente, usaram o dispositivo contendo novas amostras do grupo teste, durante mais sete dias, sendo realizado tratamento com digluconato de clorexidina a 0,12% e aplicação de sacarose 30%. A seguir, determinou-se a alteração de cor, microdureza, rugosidade e energia livre de superfície, inicialmente e após o período experimental, de todas as amostras, tendo sido realizada a coleta do biofilme para posterior análise de polissacarídeos extracelulares álcali-solúveis (PEC). Os dados foram submetidos à análise de variância e ao teste Tukey (p<0,05); exceto os valores de PEC, submetidos à análise de variância e ao teste Student-Newman-Keuls (p<0,001). Os grupos teste apresentaram menor alteração de cor que seus respectivos grupos controle, com diferença estatística significante somente entre os grupos Bis-Acril sem glaze. Com relação à microdureza, os valores aumentaram para os grupos teste em relação aos seus respectivos grupos controle, com diferença estatística significante no período final, com exceção do grupo RAAQ e Bis-Acril sem glaze, que mostraram apenas um aumento e diminuição numérica, respectivamente. Comparando-se os grupos teste com seus respectivos grupos controle, os valores de rugosidade aumentaram apenas numericamente entre os grupos RAAQ sem glaze, no período final. Já na análise de energia livre de superfície, os valores aumentaram para os grupos teste em relação ao seu respectivo grupo controle, sem diferença estatística significante. Os grupos teste apresentaram redução estatisticamente significativa da quantidade de PEC formado, em relação aos grupos controle. Pode-se concluir que o enxaguatório à base de digluconato de clorexidina a 0,12% foi satisfatório neste estudo in situ, melhorando significativamente as propriedades de alteração de cor, microdureza e energia livre de superfície e proporcionou uma melhora, no entanto, não significativa para a rugosidade, contribuindo assim, para um melhor desempenho das resinas analisadas. A aplicação do glaze também contribuiu de maneira significativa para a melhora de todas as propriedades analisadas, com exceção da alteração de cor, na qual, foi prejudicial(AU)

During rehabilitation with ceramic fragments, it is important to use provisional restorations, which are essential to achieve clinical success and longevity of the definitive prosthesis, maintaining the health and protecting dental and periodontal tissues. The aim of this study was to evaluate color stability, microhardness, roughness, and surface free energy of provisional prosthesis samples, with and without the application of light-curing glaze on the surface, and to evaluate the antibiofilm efficacy of 0.12% chlorhexidine digluconate in these samples. For this, resin samples of Bis-Acryl (Protemp, 3M ESPE, Sao Paulo, Brazil) and chemically-activated acrylic resin (CAAR) (Dencor, Artigos Odontológicos Clássico LTDA, Sao Paulo, Brazil) were made. Half of these samples were submitted to chemical polishing with light-curing glaze. These samples were placed in intraoral devices, which contained 4 niches (1 CAAR without glaze, 1 CAAR with glaze, 1 Bis-Acryl without glaze, 1 Bis-Acryl with glaze), used by volunteers (n=20). The experimental pases were: The volunteers initially used the device containing the samples from the control group for seven days, in which 30% sucrose were applied. Then, they used the device containing the samples from the test group for another seven days, in which 0.12% chlorhexidine digluconate and 30% sucrose were applied. Next, the tests of color change, microhardness, roughness and surface energy, initially and after the experimentais phases, of all samples, and the biofilm was collected for later analysis of alkali-soluble extracellular polysaccharides (EPS). Data were submitted to the analysis of variance (ANOVA) and to the Tukey test (p<0.05), except for the EPS values, which were submitted to the ANOVA and Student-Newman Keuls (p<0.001). The test groups had lower color alteration in relation to their respective control groups, and there was a statistically significant difference only between the Bis-Acryl groups without glaze. Regarding the microhardness, the values increased for the test groups in relation to their respective control groups, with a significant statistical difference in the final period, except for the CAAR group without glaze, which had only a numerical increase, and the Bis-Acryl group without glaze, in which values decreased numerically. Comparing the test groups with their respective control groups, the roughness values increased only numerically for the CAAR group without glaze, in the final period. In the surface energy analysis, the values statistically increased for the test groups, when compared to their respective control group. The test groups presented a statistically significant reduction of the biofilm amount in relation to the control groups. It can be concluded that the 0.12% chlorhexidine digluconate base rinse was clinically satisfactory, significantly improving the properties of color change, microhardness, surface energy properties, and provided non-significant improvement of the roughness, thus contributing to a better clinical performance of the resins analyzed. The glaze application also contributed significantly to all the analyzed properties, except for the color change, in which it was deleterious(AU)

Evaluación in vitro de la fuerza de desprendimiento y de la filtración marginal de coronas provisorias fijadas con diferentes agentes cementantes / In vitro evaluation of retention force and marginal leakage of temporary crowns using different luting agents

Objetivo: Analizar mediante pruebas in vitro la fuerza de desprendimiento y la microfiltración marginal de restauraciones coronarias temporales, realizadas sobre premolares, confeccionadas con tres tipos de resinas acrílicas y cementadas con tres materiales de fijación. Materiales y métodos: Se utilizaron 108 premolares a los que se les tallaron pilares con paredes convergentes hacia oclusal (8°), desgaste de 0,8 mm y chánfer a nivel adamantino. Las muestras fueron distribuidas en dos grupos: 54 muestras, para pruebas de desprendimiento; y 54, para pruebas de filtración. Los materiales utilizados en la confección de las coronas fueron: grupo A, resina de acrílico reticulado con relleno de micropartículas (Sistema Cerec, Sirona), grupo B, resina Duralay (Reliance Dental) y grupo C, resina Luxatemp (DMG). Para el cementado se emplearon: subgrupo I, cemento de hidróxido de calcio (Dycal; Dentsply); subgrupo II, cemento de óxido de zinc con el agregado de fluoruros, clorhexidina y nitrato de potasio (GC Temp Advantage; American In); subgrupo III, cemento de ZnO con el agregado de silicona y silano (Temposil; Coltène). Se desarrolló el estudio in vitro de la fuerza de desprendimiento y se realizó un análisis de correlación entre la fuerza (N) requerida para el desalojo de las coronas y la superficie de unión corona-diente (mm2). El análisis de filtración fue efectuado con lupa estereoscópica Olympus (20X y 32X), posicionando las muestras sobre portaobjeto y accionando luz incidente blanca. Por contraste colorimétrico, se determinó el grado de filtración por la penetración longitudinal del colorante en la interfaz diente-restauración. Resultados: Se encontró correlación significativa entre la fuerza requerida para el desalojo de las coronas y la superficie de unión corona diente (correlación de Pearson: 0,423, P=0,0001). Los valores medios obtenidos de la fuerza de desprendimiento fueron: grupo A, 41,09 N; grupo B, 43,52 N; grupo C, 41,26 N, sin diferencias significativas (P=0,484). Con respecto al factor cemento, subgrupo I, 56,87 N; subgrupo II, 40,75 N; y subgrupo III, 28,25 N, y la diferencia fue estadísticamente significativa (P=0,0001). En relación con las pruebas de filtración marginal in vitro considerando solo el factor categoría corona, se observó que los valores de longitud de filtración estuvieron dentro de rangos similares en los tres grupos, aunque el grupo B registró los valores más altos. Teniendo en cuenta solo el factor cemento, el subgrupo II arrojó los valores más bajos, en tanto que los subgrupos I y III registraron valores semejantes y algo mayores, con una media de 0,94 mm y 1,00 mm, respectivamente. La combinación que arrojó menor penetración fue la del grupo A con el subgrupo II (media de 0,62 mm), en tanto que la combinación con valores de longitud o profundidad de filtración más elevados fue la del grupo B con el subgrupo III (media de 1,25 mm), aunque no se alcanzaron diferencias estadísticamente significativas. Conclusión: Se pudo observar que las coronas cementadas con hidróxido de calcio generan las mejores condiciones referidas a la fuerza de desprendimiento, y que las confeccionadas por el sistema Cerec Sirona, mediante tecnología CAD-CAM y cementadas con cemento de óxido de zinc con el agregado de fluoruros, clorhexidina y nitrato de potasio, podrían ofrecen mejores propiedades en cuanto a la filtración marginal (AU)

Aim: To in-vitro analyze the detachment force and the marginal leakage of bicuspid temporary crowns made with three types of acrylic resins and cemented with three luting agents, Materials and methods: 108 premolars were used to drill 0.8 mm depth preparations with 8° taper and chamfer at adamantine level. Half of the specimens were used for detachment tests and the other for leakage. Temporary crowns were fabricated using: group A, acrylic resin with microparticle fillers (Cerec System, Sirona); group B, Duralay resin (Reliance Dental); and group C, Luxatemp resin (DMG). Dycal calcium hydroxide cement (Dentsply)subgroup I, zinc oxide cement with added fluorides, chlorhexidine and potassium nitrate GC TempAdvantage (American In) subgroup II and zinc oxide cement with silicone aggregate and Temposil Silane (Coltène) subgroup III, were used as luting agents and the load required to detach each of the crowns was determined. A correlation analysis was performed between the force (N) required and the crown-tooth involved area (mm2). Microleakage was assessed using an Olympus stereomicroscope (20X and 32X), under white incident light. By colorimetric contrast, the degree of leakage was defined by the longitudinal penetration of a dye at the tooth-restoration interface. Results: Significant correlation (Pearson: 0.423, P=0.0001) was found between force of detachment and surface. Average values obtained from the detachment force were: group A, 41.09 N; group B, 43.52 N; group C, 41.26 N, without significant differences (P=0.484). The cement factor, subgroup I, 56.87 N; subgroup II 40.75 N; and subgroup III, 28.25 N, was found significant (P=0.0001). Leakage was similar in the three groups, although group B recorded the highest values. Taking into account only the cement factor subgroup II yielded the lowest values, while subgroups I and III recorded similar and somewhat higher values, with an average of 0.94 mm and 1,00 mm, respectively. The combination that showed the lowest penetration was that of group A with subgroup II (average 0.62 mm), while the combination with higher values was seen in group B with subgroup III (average 1.25 mm). Conclusion: Temporary crowns cemented with calcium hydroxide generated the best conditions related to the detachment strength and temporary crowns fabricated using Cerec System with CAD-CAM tecnology, luted with a zinc oxide cement with the addition of fluorides, chlorhexidine and potassium showed, although not significant statistically, better properties in terms of marginal leakage (AU)

Immediate vs conventional loading of variable-thread tapered implants supporting three- to four-unit fixed partial dentures in the posterior maxilla: 1-year interim results of a split-mouth randomised controlled trial.

PURPOSE: To compare the outcome of immediately loaded and one-stage conventionally loaded variable-thread tapered implants in the posterior maxilla. MATERIALS AND METHODS: This study was designed as a split-mouth randomised controlled trial. Twenty-six patients missing teeth bilaterally in the posterior maxilla received three to four implants in each of the posterior sextants. Bone quality was recorded based on Misch criteria (D1-D4) and insertion torque values were measured using a manual wrench. The implants on one side were immediately loaded with a temporary resin fixed partial denture on definitive multi-unit abutments. The implants in the contralateral side received definitive multi-unit abutments according to the one-stage unloaded protocol. Three to 3.5 months following implant placement, the implants were restored with metal-ceramic fixed prostheses. Outcome measures were implant and prosthesis failure rates, complications, and peri-implant bone level changes at 1 year following delivery of the definitive prostheses. RESULTS: Two patients dropped out prior to the delivery of definitive prostheses. Four implants supporting a four-unit immediately loaded prosthesis failed in one patient, 3 months following delivery of the definitive prostheses. None of the conventionally loaded implants or prostheses failed. There were no significant differences in the proportions of implant and prosthesis failures (difference = 4.2%; 95% CI -4.2 to 12.6%; P = 0.999). In the immediately loaded group, four early prosthetic complications occurred during the provisionalization phase (three small resin chippings and one prosthetic screw loosening). No other complications were reported. The difference in the rate of complications between the two interventions was not statistically significant (difference = 16.7%; 95% CI -1.2% to 35.6%; P = 0.125). The 1-year peri-implant marginal bone level changes were evaluated in 23 patients (77 immediately loaded and 76 conventionally loaded implants). On average, patients lost 0.42 mm at the immediately loaded and 0.46 mm at the conventionally loaded implants, the difference being statistically not significant (difference = 0.044 mm; 95% CI -0.27 to 0.18 mm; P = 0.701). CONCLUSIONS: Immediate loading of 3- to 4-unit fixed partial prostheses supported by variable-thread implants in the posterior maxilla can yield good and similar 1-year results to one-stage conventionally loaded implants.

Fabrication of an interim complete removable dental prosthesis with an in-office digital light processing three-dimensional printer: A proof-of-concept technique.

This report describes a proof of concept for fabricating an interim complete removable dental prosthesis with a digital light processing 3-dimensional (3D) printer. Although an in-office 3D printer can reduce the overall production cost for an interim complete removable dental prosthesis, the process has not been validated with clinical studies. This report provided a preliminary proof of concept in developing a digital workflow for the in-office additively manufactured interim complete removable dental prosthesis.

NON-REMOVABLE DENTURE PROTOTYPES, EFFECTIVE IN DENTAL IMPLANTATION.

Temporary prosthesis transformed into a prosthetic prototypes and manufactured by CAD/CAM technologies (computer copy milling) are used to specify the final form of future permanent restoration and to correct occlusal relationships, vertical size of non-removable dentures, and their occlusal surfaces. A progressive loading on bone tissue in the implantation area and soft tissues formation, have been assessed. In this regard, the choice and placement of temporary mini-implants, as the supports for non-removable denture prototypes for the period of osseointegration of two-stage intraosseous dental implants, are the issues of great importance. Temporary dental implants are the object of complex loads of different magnitude, duration and direction. The action of the prosthesis is closely related to load delivery to the surface of dental implant between the components of the system - "implant-temporary prosthesis". According to the study results, minimization of the momentum acting on temporary implants in the mesiodistal direction allows reducing stress level in the areas of permanent implant placement.

Immediate Vacuum Formed Overdenture for a Pediatric Patient with Ectodermal Dysplasia.

Restoring the dental and facial esthetics in a growing patient with ectodermal dysplasia (ED) is fundamental to improve psychosocial issues, esthetics, and function. The purpose of this clinical report was to present a simple, fast, and cost-effective technique to re-establish a pleasant smile of an eight-year-old male patient with hypohydrotic ED. A vacuum-formed overdenture prosthesis is described, which is recommended as an immediate interim restorative treatment in the maxillary arch with excellent stability and retention.

Description and characterization of an alternative technique for temporary crown cementation with calcium hydroxide cement

The purpose of this study was to describe and characterize (using the tensile test) an alternative handling technique for calcium hydroxide cement in temporary crown cementation. In the group treated with the conventional technique (n=10), the base and catalyst pastes of a calcium hydroxide cement (Dycal) were dispensed at a 1:1 ratio and mixed. The cement was then applied to the internal cervical surfaces of the provisional restoration, and the restoration was placed on the prepared tooth and kept in place with digital pressure. In the group treated with the alternative technique (n=10), the base paste of the calcium hydroxide cement (Dycal) was placed on the tooth and the catalyst paste was inserted into the temporary crown. The provisional prosthesis was placed on the tooth and kept in place with digital pressure. Tensile values were evaluated and compared between groups using Student's t test with a 5% level of significance (α = 0.05). Use of this alternative technique resulted in significantly lower tensile strength compared to the conventional technique (0.58 ± 0.12 vs. 1.08 ± 0.13 MPa; p<0.001). The technique presented here (alternative) could avoid the undesired removal of cemented cast posts or cores at the time of provisional prosthesis removal and ensures the cementation of extensive provisional prostheses with calcium hydroxide cement (AU)

O objetivo deste estudo foi descrever e caracterizar (utilizando o ensaio de tração) uma técnica alternativa de manuseio para o cimento de hidróxido de cálcio na cimentação de coroa temporária. No grupo tratado com a técnica convencional (n=10), as pastas base e catalisadora de um cimento de hidróxido de cálcio (Dycal) foram dispensadas na proporção de 1:1 e misturadas. O cimento foi então aplicado às superfícies cervicais internas da restauração provisória, e a restauração foi colocada sobre o dente preparado e mantido no local com pressão digital. No grupo tratado com a técnica alternativa (n=10), a pasta base do cimento de hidróxido de cálcio (Dycal) foi colocada no dente e a pasta catalítica foi inserida na coroa provisória. A prótese provisória foi colocada sobre o dente e mantida no local com pressão digital. Os valores de tração foram avaliados comparados entre os grupos pelo teste t de Student, com nível de significância de 5% (α = 0,05). O uso desta técnica alternativa resultou em resistência à tração significativamente menor em comparação com a técnica convencional (0,58 ± 0,12 vs. 1,08 ± 0,13 MPa; p <0,001). A técnica aqui apresentada (alternativa) poderia evitar a remoção indesejada de pinos ou núcleos fundidos no momento da remoção da prótese provisória e garantir a cimentação de próteses provisórias extensas com cimento de hidróxido de cálcio (AU)

Pónticos ovoides en el manejo de tejidos blandos, zona posterior con y sin extracción: reporte de dos casos clínicos / Ovate pontics in soft tissue management, posterior zone with and without extraction: report of two clinical cases

Un problema que sucede a menudo en la práctica clínica es la ausencia dental por diversos factores. Esto conduce a un gran desafío para surehabilitación, ya que debido a la pérdida dentaria se genera un colapsodel reborde alveolar, lo que ocasiona alteración en la morfología óseay gingival, o en diversos casos, se realizaron extracciones sin una planeación restaurativa, por lo que su sustitución implica mayores procedimientos. Una alternativa a esta ausencia dental es el diseño de póntico ovoide, siempre y cuando cumpla los requisitos clínicos para un mejor resultado estético, funcional e higiénico. El objetivo de este artículo es mostrar el empleo del póntico ovoide en el sector posterior con distintos aspectos clínicos: por un lado, utilizando la técnica de conformación del lecho gingival a presión y por el otro, la técnica directa postextracción, mediante prótesis fija de tres unidades en metal/porcelana.

A problem that often occurs in clinical practice is the dental absence caused by various factors. This leads to a great challenge for rehabilitation since due to tooth loss, a collapse of the alveolar ridgeis generated, causing an alteration in bone and gingival morphology; also, in many cases, extractions were made without restorative planning, so their replacement involves major procedures. An alternative to this dental absence is ovate pontic design, provided it meets the clinical requirements for better esthetic, functional and hygienic result. The aim of this article is to show the use of the ovoid pontic in the posterior region with different clinical aspects: first, using the technique of forming the gingival bed under pressure and on the other, postextraction direct technique through a three-unit fi xed prosthesis in metal/porcelain.

Clinical comparison of short and conventional implants placed in the posterior region of the mandible. A pilot study / Comparação clínica de implantes curtos e convencionais instalados na região posterior da mandíbula. Estudo piloto

Objective: To evaluate and correlate the values of radiographic bone density, peri-implant bone height and resonance frequency analysis (RFA) of short or conventional implants placed in the posterior region of the mandible after installing a prosthesis. Material and method: Eleven patients were selected for this prospective parallel pilot study. The prostheses were supported by two types of implants: short implants (n = 18) (5.0 x 5.5 mm and 5.0 x 7.0 mm) and conventional implants (n = 23) (4.0 x10 mm and 4.0 x 11.5 mm). The implants were evaluated by RFA, by measuring the bone height, and peri-implant bone density. The implants were evaluated at the periods T0 (immediately after installation of the prosthesis), T1 (after 90 days), and T2 (after 180 days). Result: There were no statistically significant differences between groups with respect to radiographic bone density (152.50 ± 15.39 vs. 157.60 ± 28.46, for conventional and short implants, respectively at T2), stability of the implants (Conventional implants: 66.76 ± 10.39 at T0, and 61.85 ± 8.38 at T2 vs. Short implants: 57.50 ± 12.17 at T0, and 61.53 ± 7.39 at T2) and peri-implant bone loss (0.03 mm vs.-0.17 mm, for conventional and short implants, respectively at T2). Additionally, a significant correlation between the evaluated parameters was not detected. Conclusion: The short and conventional implants presented similar stability, bone level and density after the activation of occlusion loading.

Objetivo: Avaliar e correlacionar os valores de densidade óssea radiográfica, altura óssea peri-implantar e de frequência de ressonância nos implantes curtos e convencionais instalados na região posterior da mandíbula após a instalação da prótese provisória. Material e método: Esse estudo piloto clínico prospectivo contou com a participação de 11 pacientes que foram divididos previamente em dois grupos: implantes curtos (n=18) (5,0 x 5,5 mm e 5,0 x 7,0 mm) e implantes convencionais (n=23) (4,0 x 10 mm e 4,0 x 11,5 mm). Foram executadas análise da frequência de ressonância, altura óssea e densidade óssea peri-implantar. Os implantes foram avaliados nos períodos T0 (imediatamente após a instalação do provisório), T1 (após 90 dias) e T2 (após 180 dias). Resultado: Não houve diferenças estatisticamente significativas entre os grupos com relação a densidade óssea radiográfica (152,50 ± 15,39 vs. 157,60 ± 28,46, para implantes convencionais e curtos respectivamente no período T2), estabilidade dos implantes (Implantes convencionais: 66,76 ± 10,39 no período T0 e 61,85 ± 8,38 no período T2 vs. Implantes curtos: 57,50 ± 12,17 no período T0 e 61,53 ± 7,39 no período T2) e quanto a perda óssea periimplantar (0,03 mm vs. -0,17 mm, em implantes convencionais e curtos no período T2, respectivamente). Adicionalmente a isso, não foram detectados correlação significativa entre densidade radiográfica com altura óssea peri-implantar e nem com a frequência de ressonância. Conclusão: Verificou-se que os implantes curtos apresentaram um comportamento semelhante aos implantes de comprimento convencionais com relação à frequência de ressonância, a densidade radiográfica peri-implantar e a manutenção dos níveis ósseos periimplantares.