Fracture resistance of weakened roots restored with relined or milled CAD-CAM glass fiber posts.

This in vitro study compared the fracture resistance of weakened roots restored with milled or relined glass fiber post (GFP). Seventy bovine incisors were divided into seven groups, according to the weakening protocol (none: control; medium-weakened: MW; highly-weakened: HW) and post anatomization technique (non-relined, relined with Bulk Fill or Z350 resin; milled GFP: M). Roots were thermomechanical cycled and submitted to compression. Frequencies and groups were compared by the chi-square test and two-factor ANOVA, Tukey's, and t-test (α=5%). The HW-M obtained the lowest values, showing significant differences compared to all groups (p<0.001). The highest value was HW-Bulk fill, with significant difference compared to MW-M (p=0.037) and HW-M (p<0.001). The frequency of repairable fractures was 100% in the control, 87%, and 63% in the MW and HW, respectively. Relined or milled GFPs can be considered to rehabilitate weakened teeth since failure patterns were predominantly repairable in all groups.

Fracture resistance and stress distribution of weakened teeth reinforced with a bundled glass fiber-reinforced resin post.

OBJECTIVES: To make an in vitro assessment of fracture resistance of weakened and non-weakened teeth receiving intraradicular reinforcement using Rebilda bundled glass fiber-reinforced composite posts (GT), Rebilda conventional glass fiber posts (RP), or both systems combined (GT + RP). MATERIALS AND METHODS: Eighty sound bovine incisors were prepared and divided randomly into eight groups as follows: (a) nWnR: without simulating weakness, and without intraradicular reinforcement; (b) WnR: simulating weakness, but without intraradicular reinforcement; (c) nWGT: without simulating weakness, but with GT; (d) WGT: simulating weakness, and with GT; (e) nWRP: without simulating weakness, but with RP; (f) WRP: simulating weakness, and with RP; (g) nWGTRP: without simulating weakness, but with GT + RP; (h) WGTRP: simulating weakness, and with GT + RP. The specimens were subjected to the load-to-fracture test using the DL-2000MF universal testing machine. The finite element method assessed the mechanical behavior and stress distribution in endodontically treated teeth. RESULTS: The groups nWGTRP and WGTRP presented the best results in the load-to-fracture test, with the former being better than the latter, but with no statistically significant difference (P > 0.05). However, there was a significant difference between these and the other groups (P < 0.05), except for nWRP. Stress distribution inside the canal wall was different among the groups, with promising mechanical behavior for nWGTRP and nWRP. CONCLUSIONS: The Rebilda conventional fiber post (RP), combined with the Rebilda bundled glass fiber-reinforced composite post (GT) improves the resistance and stress distribution of immature teeth. CLINICAL RELEVANCE: Longitudinal fracture is less frequent in teeth restored with GT and RP posts.

Efeitos sinérgicos antimicrobianos da combinação dos extratos de sálvia e alcaçuz sobre cepas clínicas de Enterococcus faecalis e Enterococcus faecium / Synergistic antimicrobial effects of the combination of sage and licorice extracts on clinical strains of Enterococcus faecalis and Enterococcus faecium

A crescente busca pelo conhecimento do potencial biológico presente nas plantas medicinais tem estimulado pesquisas, principalmente no que diz respeito ao potencial antimicrobiano dos extratos de plantas. Entretanto, mais estudos sobre os efeitos sinérgicos da combinação desses extratos são fundamentais para sua maior aplicação clínica. O objetivo desse estudo foi avaliar in vitro os efeitos sinérgicos antimicrobianos das associações dos extratos naturais de Salvia officinalis (S. officinalis) e Glycyrrhiza glabra (G. glabra). Foi realizada a análise antimicrobiana sobre três cepas clínicas de Enterococcus faecalis (E. faecalis), duas cepas clínicas de Enterococcus faecium (E. faecium) e uma cepa padrão de cada espécie. Foram determinadas as Concentração Inibitória Mínima (CIM) e Concentração Microbicida Mínima (CMM) por microdiluição em caldo com semeadura, e Índice de Concentração Inibitória Fracionada (ICIF) pela técnica checkerboard. Para avaliar o efeito combinado dos extratos sobre biofilme foram utilizadas duas combinações dos extratos sobre biofilme formado de E. faecalis e sobre biofilme formado de E. faecium, por dois períodos diferentes: 5 minutos e 24 h, e foram avaliados os valores médios de unidades formadoras de colônias por mililitro (UFC/mL). A análise estatística foi feita aplicando método ANOVA e teste de Tukey ou Kruskall-Wallis e Dunn (significância de 5%). Os extratos de S. officinalis e G. glabra apresentaram concentração microbicida para as cepas avaliadas. A combinação dos extratos apresentou valores indiferentes (ICIF ˃ 0,5 e ≤ 4) para as cepas de E. faecium, e valores indiferentes e sinérgicos (ICIF ≤0,5) para cepas de E. faecalis. Sobre biofilme as duas combinações apresentaram reduções estatisticamente significantes do grupo controle negativo (p < 0,05). Dessa forma concluiu-se que a combinação dos extratos de S. officinalis e G. glabra possui feito sinérgico antimicrobiano contra E. faecalis e atividade antibiofilme contra E. faecalis e E. faecium (AU)

The growing search for knowledge of the biological potential present in medicinal plants has stimulated research, especially with regard to the effective antimicrobial potential of plant extracts, however, further studies on the synergistic effects of the combination of these extracts is essential for their greater clinical application. The aim of this study was to evaluate in vitro the synergistic antimicrobial effects of the association of natural extracts of Salvia officinalis (S. officinalis) and Glycyrrhiza glabra (G. glabra). Antimicrobial analysis was performed on three clinical strains of Enterococcus faecalis (E. faecalis), two clinical strains of Enterococcus faecium (E. faecium) and one standard strain of each species. The Minimum Inhibitory Concentration (MIC) and Minimum Microbicidal Concentration (MMC) were determined by microdilution in broth with seeding, and Fractional Inhibitory Concentration Index by the checkerboard technique. To evaluate the combined effect of extracts on biofilm, two combinations of extracts on biofilm formed by E. faecalis and on biofilm formed by E. faecium were used, for two different periods: 5 min and 24 h, and the mean values of units were evaluated. colony forming agents per milliliter (CFU/mL). Statistical analysis was performed using the ANOVA method and Tukey's or Kruskall-Wallis and Dunn's test (5% significance). The extracts of S. officinalis and G. glabra showed microbicidal concentration for the strains evaluated. The combination of extracts showed indifferent values (FICI ˃ 0.5 and ≤ 4) for E. faecium strains, and indifferent and synergistic values FICI ≤0.5) for E. faecalis strains. On biofilm, the two combinations showed statistically significant reductions compared to the negative control group (p < 0.05). Thus, it is concluded that the combination of extracts of S. officinalis and G. glabra has synergistic antimicrobial effect against E. faecalis and antibiofilm activity against E. faecalis and E. faecium (AU)

Bond strength of cemented fiber posts to teeth with simulated internal root resorption.

BACKGROUND: Teeth with internal root resorption (IRR) have guarded prognosis, considering that IRR defect could influence on the post bond strength. The aim of this study was to evaluate the bond strength and the bond interface between different glass fiber-reinforced posts (FRP) after cementation in teeth with simulated internal root resorption (IRR). MATERIAL AND METHODS: Forty-five (45) human premolar roots with simulated IRR were embedded in acrylic resin blocks and cross-sectioned into two segments, enabling them to be re-approximated by screws. Intracanal medication was inserted for 15-days, removed by passive ultrasonic irrigation (PUI) and examined by stereomicroscopy. The push-out bond strength of two fiber reinforced composite posts (Rebilda Post - RP) and Rebilda Post GT - GT, (VOCO) were evaluated at the cervical and IRR regions (n = 20). And, the bonded interface between resin cement and root dentine was analysed by scanning electron microscopy (SEM). RESULTS: 62.5% of IRR were not completely cleaned by PUI. Bond strength values at the cervical region (9.8 and 14.6 MPa) were higher than the IRR region (6.3 and 4.2 MPa). Micrographies showed bubbles in the cement and spaces in the bonded interface. CONCLUSIONS: RP post showed better bond strength at the cervical region while GT had better bond strength at the IRR region. Key words:Endodontics, root canal filling materials, root resorption, X-Ray microtomography.

Resistência à fratura de dentes fragilizados utilizando reforço intra-radicular com pino de fibra de vidro: Rebilda Post e Rebilda Post GT / Fracture resistance in fragile teeth using root reinforcements with glass fiber posts: Rebilda Post and Rebilda Post GT

O objetivo deste trabalho foi avaliar, in vitro, pelo teste de compressão, a resistência à fratura de dentes fragilizados que receberam como reforço intra-radicular sistema de pino de fibra de vidro. Foram utilizados 80 dentes bovinos divididos de acordo com o tipo de reforço intra-radicular e com a presença ou não de preparos para simular fragilidade radicular (n=10): SF/SR - sem fragilização e sem reforço intra- radicular; F/SR - com fragilização e sem reforço intra-radicular; SF/GT - sem fragilização e com reforço intra-radicular Rebilda Post GT; F/GT ­ com fragilização e com reforço intraradicular Rebilda Post GT; SF/RP - sem fragilização e com reforço intra-radicular Rebilda Post; F/RP ­ com fragilização e com reforço intra-radicular Rebilda Post; SF/GT+RP - sem fragilização e com reforço intra-radicular Rebilda Post GT + Rebilda Post; e F/GT+RP ­ com fragilização e com reforço intra-radicular Rebilda Post GT + Rebilda Post. Todos os espécimes tiveram suas coroas seccionadas, comprimento radicular padronizado em 16 mm e canais radiculares preparados endodonticamente. Para os espécimes com fragilização simulada, o desgaste radicular foi realizado até 9 mm no interior do canal e a espessura do remanescente radicular obtida foi de aproximadamente 2 mm. Exceto para o SF/SR, todos os canais radiculares foram obturados. O material obturador foi removido dos terços cervical e médio, permanecendo apenas 4 mm no terço apical. A cimentação dos pinos foi realizada seguindo o protocolo do fabricante. Apenas para os espécimes dos grupos SF/GT+RP e F/GT+RP, após a inserção do pino Rebilda Post GT e antes da polimerização final, foi inserido no centro do conjunto o pino Rebilda Post. Os espécimes foram submetidos ao teste de compressão à 45º. Os valores de resistência à fratura encontrados para os grupos, em ordem decrescente, foram: F/SR ­ 5,045 kgf, SF/SR ­ 9,157 kgf, SF/GT ­ 14,032 kgf, F/RP ­ 27,727 kgf, F/GT ­ 28,303 kgf, SF/RP ­ 29,986 kgf, F/GT+RP ­ 38,650 kgf e SF/GT+RP ­ 39,783 kgf. Os resultados obtidos foram submetidos à análise estatística (ANOVA e Tukey) que demonstrou diferença estatisticamente significativa (p<0,05). Dessa forma observouse que o pino único, Rebilda Post, proporcionou maior resistência à fratura que o sistema Rebilda Post GT e os grupos sem reforço intra-radicular, SF/SR e F/SR; e que a associação dos sistemas produziu os maiores valores de resistência à fratura do que os demais(AU)

The objective of this work was to evaluate, in vitro, by the compression test, the fracture strength of fragile teeth that received a fiberglass pin system as intra- radicular reinforcement. It was used 80 bovine teeth divided according to the type of intraradicular reinforcement and with the presence or not of preparations to simulate root fragility (n = 10): SF / SR - without embrittlement and without intra-radicular reinforcement; F / SR - with embrittlement and without intra-radicular reinforcement; SF / GT - without embrittlement and with intra-radicular reinforcement Rebilda Post GT; F / GT - with embrittlement and intra-radicular reinforcement Rebilda Post GT; SF / RP - without embrittlement and with intra-radicular reinforcement Rebilda Post; F / RP - with embrittlement and intra-radicular reinforcement Rebilda Post; SF / GT + RP - without embrittlement and with intra-radicular reinforcement Rebilda Post GT + Rebilda Post; and F / GT + RP - with embrittlement and with intra-radicular reinforcement Rebilda Post GT + Rebilda Post. All specimens had their crowns sectioned, root length standardized at 16 mm and root canals prepared endodontically. For specimens with simulated embrittlement, root wear was performed up to 9 mm inside the canal and the thickness of the root remainder obtained was approximately 2 mm. Except for SF / SR, all root canals were filled. The obturator material was removed from the cervical and middle thirds, remaining only 4 mm in the apical third. Pin cementation was performed following the manufacturer's protocol. Only for the specimens of the groups SF / GT + RP and F / GT + RP, after the insertion of the Rebilda Post GT pin and before the final polymerization, the Rebilda Post pin was inserted in the center of the set. The specimens were submitted to the 45º compression test. The values of fracture resistance found for the groups, in descending order, were: F / SR - 5,045 kgf, SF / SR - 9,157 kgf, SF / GT - 14,032 kgf, F / RP - 27,727 kgf, F / GT - 28,303 kgf, SF / RP-29.986 kgf, F / GT + RP-38.650 kgf and SF / GT + RP-39.783 kgf. The results were submitted to statistical analysis (ANOVA and Tukey), which showed a statistically significant difference (p< 0,05). In this way, it was observed that the single post, Rebilda Post, provided greater resistance to fracture than the Rebilda Post GT system and the non-reinforced groups, SF / SR and F / SR; and that the association of the systems produced the highest values of fracture resistance than the others(AU)