Flexural strength, surface roughness, micro-CT analysis, and microbiological adhesion of a 3D-printed temporary crown material.

OBJECTIVE: To evaluate the thermocycling effect of 3D-printed resins on flexural strength, surface roughness, microbiological adhesion, and porosity. MATERIALS AND METHODS: 150 bars (8 × 2 × 2 mm) and 100 blocks (8 × 8 × 2 mm) were made and divided into 5 groups, according to two factors: "material" (AR: acrylic resin, CR: composite resin, BIS: bis-acryl resin, CAD: CAD/CAM resin, and PRINT: 3D-printed resin) and "aging" (non-aged and aged - TC). Half of them were subjected to thermocycling (10,000 cycles). The bars were subjected to mini-flexural strength (σ) test (1 mm/min). All the blocks were subjected to roughness analysis (Ra/Rq/Rz). The non-aged blocks were subjected to porosity analysis (micro-CT; n = 5) and fungal adherence (n = 10). Data were statistically analyzed (one-way ANOVA, two-way ANOVA; Tukey's test, α = 0.05). RESULTS: For σ, "material" and "aging" factors were statistically significant (p < 0.0001). The BIS (118.23 ± 16.26A) presented a higher σ and the PRINT group (49.87 ± 7.55E) had the lowest mean σ. All groups showed a decrease in σ after TC, except for PRINT. The CRTC showed the lowest Weibull modulus. The AR showed higher roughness than BIS. Porosity revealed that the AR (1.369%) and BIS (6.339%) presented the highest porosity, and the CAD (0.002%) had the lowest porosity. Cell adhesion was significantly different between the CR (6.81) and CAD (6.37). CONCLUSION: Thermocycling reduced the flexural strength of most provisional materials, except for 3D-printed resin. However, it did not influence the surface roughness. The CR showed higher microbiological adherence than CAD group. The BIS group reached the highest porosity while the CAD group had the lowest values. CLINICAL RELEVANCE: 3D-printed resins are promising materials for clinical applications because they have good mechanical properties and low fungal adhesion.

Bond strength, degree of conversion, and microorganism adhesion using different bracket-to-enamel bonding protocols.

PURPOSE: This study aimed to evaluate the effect of bonding protocols and the type of orthodontic resin on the adhesion of microorganisms, degree of conversion (DC), and shear bond strength (SBS) of metallic brackets to enamel. METHODS: A total of 60 bovine incisors were prepared and randomly divided into 6 groups (n = 10): "bonding protocol" (A: phosphoric acid; AXT: A+Transbond™ XT primer adhesive [all Transbond™ products from 3M Unitek, Monrovia, CA, USA]; and SE: Transbond™ Plus Self Etching Primer) and "orthodontic resin" (XT: Transbond™ XT adhesive paste and CC: Transbond™ Plus Color Change). After bonding, the samples were subjected to thermocycling (5000 cycles) and to the SBS test. Bond failures were classified according to the adhesive remnant index (ARI). Next, 60 enamel blocks were sterilized in ethylene oxide in order to perform the CFU (Streptococcus mutans) assay in vitro to analyze the colony forming units (CFU/mL). Then, 60 discs of each orthodontic resin were made to measure the DC. The SBS (MPa), CFU/mL, and DC (%) data were statistically analyzed by two-way analysis of variance and Tukey's test (5%) was performed for the DC. RESULTS: CFU and SBS revealed no significance for all factors (P > 0.05). Tukey's test showed that A_XT (acid+Transbond™ XT adhesive paste) presented the highest DC (70.38% ± 10.5), while AXT_XT (acid+Transbond™ XT primer adhesive+Transbond™ XT adhesive paste) showed the lowest (23.47% ± 10.4). An ARI score of 2 was more frequent for the CC resin and an ARI score of 4 for the XT resin. CONCLUSION: The CC resin does not reduce adhesion of S. mutans around orthodontic brackets and the bonding protocol did not influence the SBS, although the SE and A_XT groups contributed to a better DC.

Effect of finishing/polishing techniques and aging on topography, C. albicans adherence, and flexural strength of ultra-translucent zirconia: an in situ study.

OBJECTIVE: To investigate the influence of different finishing/polishing techniques and in situ aging on the flexural strength (σ), surface roughness, and Candida albicans adherence of 5 mol% yttria-stabilized zirconia (ultratranslucent zirconia). MATERIALS AND METHODS: A total of 120 zirconia bars (Prettau Anterior, Zirkonzahn) with dimensions of 8 × 2 × 0.5 mm were divided into 8 groups (n = 15) according to two factors: "in situ aging" (non-aged and aged (A)) and "finishing/polishing" (control (C), diamond rubber polishing (R), coarse grit diamond bur abrasion (B), and coarse grit diamond bur abrasion + diamond rubber polishing (BR)). Half of the samples from each group were subjected to a 60-day in situ aging by fixing the bars into cavities prepared in the posterior region of the base of complete or partial dentures of 15 patients. The samples were then subjected to the mini flexural (σ) test (1 mm/min). A total of 40 zirconia blocks (5 × 5 × 2 mm) were prepared and subjected to roughness (Ra) analyses and fungal adherence and complementary analyses (X-ray diffraction (XRD) and scanning electron microscopy (SEM)). The data of mean σ (MPa) and roughness Ra (µm) were statistically analyzed by two-way and one-way ANOVA, respectively, and Tukey's test. The Weibull analysis was performed for σ data. The fungal adhesion (Log CFU/mL) data were analyzed by Kruskal-Wallis tests. RESULTS: For flexural resistance, the "finishing/polishing" factor was statistically significant (P = 0.0001); however, the "in situ aging" factor (P = 0.4458) was not significant. The non-aged (507.3 ± 115.7 MPa) and aged (487.6 ± 118.4 MPa) rubber polishing groups exhibited higher mean σ than the other techniques. The non-aged (260.2 ± 43.3 MPa) and aged (270.1 ± 48.8 MPa) bur abrasion groups presented lower σ. The coarse-grit diamond bur abrasion group (1.82 ± 0.61 µm) presented the highest roughness value (P = 0.001). Cell adhesion was not different among groups (P = 0.053). Group B presented the most irregular surface and the highest roughness Ra of 0.61 m. CONCLUSIONS: The finishing of ultratranslucent zirconia might be preferably done with a diamond rubber polisher. Moreover, the protocols used did not interfere with Candida albicans adhesion. CLINICAL RELEVANCE: Coarse-grit diamond burs might be avoided for finishing ultratranslucent monolithic zirconia, which might be preferably performed with a diamond rubber polisher.

Effect of different repair methods on the bond strength of resin composite to CAD/CAM materials and microorganisms adhesion: An in situ study.

OBJECTIVE: To evaluate the influence of different repair protocols andin situ aging on colony forming units (CFU) and shear bond strength (SBS) between CAD/CAM materials and resin composite. METHODOLOGY: 150 blocks (6 × 5 × 2.5 mm) were made out of each restorative material (CAD/CAM resin composite -RC), polymer-infiltrated ceramic - PIC and glass ceramic (VS), totaling 450 blocks. Fifty blocks of each material were submitted to a 60-day in situ aging by fixing the blocks into cavities prepared in the posterior region of the base of complete dentures. The aged and non-aged blocks were randomly divided into 30 groups of 10 (N = 300) according to the following factors: "Restorative material", "Surface Treatment", and "Aging". Z350 resin composite cylinders were made on the surface of the blocks, and the specimens were submitted to thermocycling, shear test, failure mode analysis, and complementary analyses of roughness, fungal and bacterial CFUs, SEM, and EDS. The SBS (MPa) and CFU/mL data were statistically analyzed by ANOVA and Tukey's test (5%). The other variables were analyzed by qualitative analyzes. RESULTS: The "aging" factor was significant for RC and VS and the "surface treatment" factor was significant for the three restorative materials. Hydrofluoric (HF) acid etching followed by silanization was the best protocol for PIC and VS and diamond bur + SBU was the best protocol for RC. CFU/mL was similar among the restorative materials. CONCLUSION: In situ aging reduced the bond strength between the resin composite repair and RC and VS materials. CLINICAL SIGNIFICANCE: The repair protocol for each restorative material is different and may be influenced by the time of clinical use.

Panorama da Radiologia Odontológica no Brasil: disponibilidade de aparelhos e produção ambulatorial de radiografias / Panorama de la Radiología Odontológica en Brasil: disponibilidad de equipos y producción ambulatoria de radiografías / Overview of Dental Radiology in Brazil: availability of equipment and ambulatory production of radiographs

Objetivo: estabelecer o panorama da radiologia odontológica no Brasil, pautando-se nos aspectos: disponibilidade de aparelhos e produção ambulatorial de radiografias. Métodos: realizou-se um estudo ecológico, utilizando dados secundários oriundos de bases eletrônicas disponibilizadas pelo Ministério da Saúde. Para cada unidade federativa do Brasil (n= 27) foram coletados os dados: número e distribuição de aparelhos de Raios-X Odontológico , bem como sua esfera administrativa; produção ambulatorial de radiografias; população total e população coberta na Atenção Básica. Procedeu-se à análise comparativo-descritiva dos dados. Resultados: existem 34 066 aparelhos de Raios-X Odontológico em uso no Brasil, dos quais 83,8 porcento pertencem à esfera privada. Das cidades brasileiras, 47,9 porcento possuem aparelhos, porém, analisando-se somente o serviço público, em 35,6 porcento das cidades há aparelhos de Raios-X Odontológico. Há 56 20,9 pessoas por aparelho. No serviço público, há 20 591,6 pessoas cadastradas na atenção básica por aparelho público. Quanto à produção de radiografias, 94 porcento foram de periapicais/interproximais. Conclui-se que o quantitativo de aparelhos está sob administração da esfera privada. Conclusão: a produção ambulatorial é representada por radiografias periapicais/interproximais, verificando-se discrepâncias severas entre atenção prestada e quantitativo de procedimentos executados na rede pública de saúde(AU)

Objetivo: establecer el panorama de la radiología odontológica en Brasil, atendiendo a los aspectos: disponibilidad de aparatos y producción ambulatoria de radiografías. Métodos: se realizó un estudio ecológico para lo cual se utilizaron datos secundarios recogidos de bases electrónicas que están disponibles por el Ministerio de la Salud. Para cada unidad federativa de Brasil (n= 27) se recogieron los datos: número y distribución de equipos de Rayos-X Odontológico, así como en el área administrativa; producción ambulatoria de radiografías; población total y población tratada en la Atención Básica. Se procedió al análisis comparativo-descriptivo de los datos. Resultados: en Brasil existen en uso 34 066 equipos de Rayos-X Odontológico, de los cuales 83,8 por ciento pertenecen a la esfera privada. De las ciudades brasileñas, 47,9 por ciento poseen equipos, sin embargo, analizándose solamente el servicio público, un 35,6 por ciento de las ciudades cuenta con equipos de Rayos-X Odontológico. Hay 56 209 personas por cada equipo. En el servicio público, existen 20 5916 personas registradas en la atención básica por cada equipo público. En cuanto a la producción de radiografías, 94 por ciento fueron de periapicales/interproximales. Se concluye que el cuantitativo de equipos se encuentra en manos de la esfera privada. Conclusión: la producción ambulatoria es representada por radiografías periapicales/interproximales, comprobándose discrepancias severas entre la atención prestada y el cuantitativo de los procesos ejecutados en la red pública de salud(AU)

Objective: To provide an overview of dental radiology in Brazil, based on the availability of equipment and outpatient production of X-rays. Methods: An ecological study was conducted by using secondary data from electronic databases provided by the Health Ministry. For each federal unit of Brazil (n = 27) the following data were collected: number and distribution of equipment for dental X-rays (ARXO) as well as its administrative level; outpatient production of radiographs; total population and population covered in Primary Care. A comparative and descriptive analysis of these data was made. Results: There are 34 066 X-ray equipment in operation in Brazil, of which 83.8 percent belongs to the private sector. Among the Brazilian cities, 47.9 percent have their own equipment; however, just considering the public service, 35.6 percent of the cities have dental X-ray equipment. There are 5 6209 people per equipment. In the public service, there are 20 5916 people enrolled in primary care per public equipment. Regarding the production of radiographs, 94 percent were periapical and/or interproximal. Conclusions: It is concluded that the amount of equipment is concentrated under the management of the private service. The outpatient production in dental radiology is represented by periapical/interproximal radiographs. Serious discrepancies between the care rendered and the amount of procedures performed in the public health network have been disclosed(AU)