Application value of bone cement containing rhbFGF and RHBMP-2 in PKP treatment of osteoporotic lumbar compression fracture / 中国骨伤

OBJECTIVE@#To investigate the effect of bone cement containing recombinant human basic fibroblast growth factor (rhbFGF) and recombinant human bone morphogenetic protein-2 (rhBMP-2) in percutaneous kyphoplasty(PKP)treatment of osteoporotic vertebral compression fracture(OVCF).@*METHODS@#A total of 103 OVCF patients who underwent PKP from January 2018 to January 2021 were retrospectively analyzed, including 40 males and 63 females, aged from 61 to 78 years old with an average of (65.72±3.29) years old. The injury mechanism included slipping 33 patients, falling 42 patients, and lifting injury 28 patients. The patients were divided into three groups according to the filling of bone cement. Calcium phosphate consisted of 34 patients, aged(65.1±3.3) years old, 14 males and 20 females, who were filled with calcium phosphate bone cement. rhBMP-2 consisted of 34 patients, aged (64.8±3.2) years old, 12 males and 22 females, who were filled with bone cement containing rhBMP-2. And rhbFGF+rhBMP-2 consisted of 35 patients, aged (65.1±3.6) years old, 14 males and 21 females, who were filled with bone cement containing rhbFGF and rhBMP-2. Oswestry disability index (ODI), bone mineral density, anterior edge loss height, anterior edge compression rate of injured vertebra, visual analog scale (VAS) of pain, and the incidence of refracture were compared between groups.@*RESULTS@#All patients were followed for 12 months. Postoperative ODI and VAS score of the three groups decreased (P<0.001), while bone mineral density increased (P<0.001), anterior edge loss height, anterior edge compression rate of injured vertebra decreased first and then slowly increased (P<0.001). ODI and VAS of group calcium phosphate after 1 months, 6 months, 12 months were lower than that of rhBMP-2 and group rhbFGF+rhBMP-2(P<0.05), bone mineral density after 6 months, 12 months was higher than that of rhBMP-2 and group calcium phosphate(P<0.05), and anterior edge loss height, anterior edge compression rate of injured vertebra of group rhbFGF+rhBMP-2 after 6 months and 12 months were lower than that of group rhBMP-2 and group calcium phosphate(P<0.05). There was no statistical difference in the incidence of re-fracture among the three groups (P>0.05).@*CONCLUSION@#Bone cement containing rhbFGF and rhBMP-2 could more effectively increase bone mineral density in patients with OVCF, obtain satisfactory clinical and radiological effects after operation, and significantly improve clinical symptoms.

Comparative study of physical-chemical properties of bioactive glass ionomer cement

Abstract This study analyzed the physical-chemical properties of bioactive ionomer materials. Cention N bioactive materials were evaluated chemically activated (CN) and light-cured (CN-LC), Equia Forte Fill (EQUI); conventional resin composite Filtek Z350 XT (Z350); resin glass ionomer cement Riva light Cure (RIVA) and flowable resin composite Filtek Bulk Fill Flow (BULK-F) were evaluated. Sixty specimens (n=10) were prepared for sorption (SR), solubility (SL), flexural strength (FS), shrinkage stress (SS), conversion degree (CD), microhardness (MI), and surface roughness (SR) tests. Non-cured and light-cured materials were assessed on FTIR. 30 human molar teeth were used in the bond strength test (BS). Data were subjected to ANOVA and post-hoc Tukey's test (5% of significance). EQUI showed more sorption in SR and no statistical difference from RIVA and CN-LC. CN group showed more solubility and EQUI presented less (p<0.05). BULK-F showed higher FS (MPa), without differences from CN and Z350, whereas EQUI presented the lowest FS not differing from RIVA. BULK-F and CN-LC showed more shrinkage stress differing from EQUI. CN-LC and CN showed higher CD differing from the other which showed no differences (p>0.05) between them. EQUI showed the highest hardness (p<0.05) in MI. There were no differences (p>0.05) in SR (µm). Z350 and BULK-F presented higher BS, whereas CN-LC showed the lowest, although not differing from EQUI and RIVA. Equia Forte's solubility and microhardness make it a good alternative as a restorative material. Cention N degree of conversion and flexural strength making it an esthetic option to amalgam.

Resumo Este estudo analisou as propriedades físico-químicas dos materiais de ionômero bioativo. Os materiais bioativos Cention N quimicamente ativados (CN) e fotopolimerizados (CN-LC), Equia Forte Fill (EQUI); resina composta convencional Filtek Z350 XT (Z350); resina de ionômero de vidro Riva light Cure (RIVA) e resina composta fluida Filtek Bulk Fill Flow (BULK-F) foram avaliados. Sessenta espécimes (n=10) foram preparados para testes de sorção (SR), solubilidade (SL), resistência à flexão (FS), tensão de contração (SS), grau de conversão (CD), microdureza (MI) e rugosidade da superfície (SR). Os materiais não curados e curados com luz foram avaliados por FTIR. 30 dentes molares humanos foram usados no teste de resistência de união (BS). Os dados foram submetidos a ANOVA e teste de post-hoc Tukey (5% de significância). O EQUI apresentou maior sorção no SR e não mostrou diferença estatística em relação aos grupos RIVA e CN-LC. O grupo CN apresentou maior solubilidade e o EQUI apresentou menor (p<0,05). O BULK-F apresentou maior FS (MPa), sem diferir do CN e do Z350, enquanto o EQUI apresentou o menor FS, não diferindo do RIVA. O BULK-F e o CN-LC apresentaram maior estresse de contração, diferindo do EQUI. O CN-LC e o CN apresentaram maior CD (%), diferindo dos demais, que não apresentaram diferenças (p>0,05) entre si. A EQUI apresentou a maior dureza (p<0,05) no MI. Não houve diferenças (p>0,05) na SR (µm). Z350 and BULK-F apresentaram BS, enquanto a CN-LC apresentou a menor, embora não diferindo da EQUI e da RIVA. A solubilidade e a microdureza do Equia Forte o tornam uma boa alternativa como material restaurador. O grau de conversão e a resistência à flexão do Cention N o tornam uma opção estética ao amálgama.

Toothbrushing effects on the surface roughness and cement volume loss of bonded enamel-ceramic interface

Abstract This study evaluated the effect of toothbrushing on enamel-cementing material-ceramic bonded interfaces, using different cementing materials. Materials and Methods: Thirty enamel and thirty ceramic blocks were bonded with cementing materials to produce the samples that were bonded with three types of cementing materials: 1- RelyX Ultimate resin cement (REXU), 2- RelyX Unicem 2 self-adhesive resin cement (REU2) and 3- heated Z100 restorative composite (60°C). Bonded interfaces of the samples were toothbrushed and the surfaces of the 3 cementing materials were evaluated for roughness (RG, in µm), roughness profile (RP, in µm), and volume loss (VL, in µm3) (baseline and after 20,000 and 60,000 toothbrushing cycles). Data were evaluated by Generalized Linear Analysis (two factors: "material" and "toothbrushing cycle") and Bonferroni test (α=0.05). Results: REXU and Z100 exhibited lower RG than that presented by REU2, except after 60,000 toothbrushing cycles when only Z100 differed from REU2. The increase in toothbrushing cycles increased the RG and RP for all materials. REU2 also showed higher RP than those showed by REXU and Z100 when it was analyzed regarding the enamel. The VL of Z100 was the lowest with 20,000 toothbrushing cycles, regarding the enamel and ceramic. For 60,000 cycles, REXU showed the lowest VL regarding the ceramic, and REU2 had the highest VL regarding the enamel and ceramic. Conclusion: In general, REXU and Z100 showed the best results regarding the evaluations performed and the REU2 exhibited the highest RG, RP, and VL.

Resumo Este estudo avaliou o efeito da escovação nas interfaces de união esmalte-material cimentante-cerâmica, utilizando diferentes materiais cimentantes. Materiais e Métodos: Trinta esmaltes e trinta blocos cerâmicos foram unidos com materiais de cimentação para produzir as amostras que foram unidas com três tipos de materiais de cimentação: 1- cimento resinoso RelyX Ultimate (REXU), 2- cimento resinoso autoadesivo RelyX Unicem 2 (REU2) e 3-compósito restaurador aquecido Z100 (60°C). As interfaces coladas das amostras foram escovadas e as superfícies dos 3 materiais cimentantes foram avaliadas quanto à rugosidade (RG, em µm), perfil de rugosidade (RP, em µm) e perda de volume (VL, em µm3) (baseline e após 20.000 e 60.000 ciclos de escovação). Os dados foram avaliados por Análise Linear Generalizada (dois fatores: "material" e "ciclo de escovação") e teste de Bonferroni (α=0,05). Resultados: REXU e Z100 apresentaram menor RG do que REU2, exceto após 60.000 ciclos de escovação, quando Z100 diferiu apenas de REU2. O aumento dos ciclos de escovação aumentou o RG e RP para todos os materiais. O REU2 também apresentou PR maior que o REXU e Z100, quando analisado em relação ao esmalte. O VL de Z100 foi o menor com 20.000 ciclos de escovação em relação ao esmalte e cerâmica. Para 60.000 ciclos, o REXU apresentou o menor VL em relação à cerâmica e o REU2 o maior VL em relação ao esmalte e à cerâmica. Conclusão: De maneira geral, REXU e Z100 apresentaram os melhores resultados nas avaliações realizadas e o REU2 apresentou os maiores RG, RP e VL..

In vitro cytotoxicity of resin cement and its influence on the expression of antioxidant genes / Avaliação in vitro da toxicidade de cimentos resinosos e sua influência na expressão de genes antioxidantes em fibroblastos humanos

ABSTRACT Aim: This study evaluated cytotoxicity and antioxidant gene expression of resin cements on human gingival fibroblasts (hGF). Materials and Method: RelyX Ultimate™(RXU), Variolink™II(VLII), and RelyXU200™(RXU200) resin cements were incubated with culture medium for 24 h to obtain eluates. Then, the eluates were applied over hGF to assess cell viability at 24 h, 48 h, and 72 h and antioxidant gene expression at 24 h. hGF cultures non-exposed to the eluates were used as Control. Data were submitted to ANOVA and Bonferroni tests (α≤0.05). Results: RXU and RXU200 reduced the number of viable cells in 24 h. Longer exposure to cement extracts caused cell death. Gene expression showed peroxiredoxin 1 (PRDX1) induction by all resin cement types, and superoxide dismutase 1 (SOD1) induction by RXU200 and VLII. Moreover, RXU200 induced not only PRDX1 and SOD1, but also glutathione peroxidase 1 (GPX1), catalase (CAT), and glutathione synthetase (GSS). Conclusions: All resin cements showed toxicity, and induced antioxidant genes in hGF. Antioxidant gene induction is at least partly associated with cytotoxicity of tested cements to oxidative stress experience.

RESUMO Objetivo: O objetivo deste estudo foi avaliar a toxicidade dos cimentos resinosos Rely X Ultimate 2, Rely X U200 e Variolink II, bem como sua influência na expressão de genes antioxidantes em fibroblastos gengivais humanos. Materiais e Método: Corpos de prova de cada cimento foram colocados em meio de cultura por 24 h e os extratos correspondentes foram aplicados aos fibroblastos. A viabilidade celular foi avaliada após 24, 48 e 72 h de exposição pelo ensaio de exclusão do azul de tripano e MTT. A expressão gênica foi avaliada por PCR quantitativo após 24 h de exposição aos extratos. Estes parâmetros foram comparados aos das células não expostas aos cimentos. Os dados foram submetidos ao teste ANOVA, seguido pelo pós-teste de Bonferroni (a≤0.05). Resultados: Os resultados demonstraram que todos os cimentos promoveram redução do número de células viáveis e da atividade mitocondrial nos períodos de 48 e de 72 h (p < 0,01), sendo que o Variolink II apresentou o menor efeito e os cimentos Rely X Ultimate e Rely X U200 promoveram similarmente os maiores efeitos. A análise de expressão gênica evidenciou influência significativa em todos os cimentos avaliados sobre os níveis de transcritos de PRDX1, SOD1, GPX1 e GSS (p> 0,05), com um aumento considerável no Rely X U200. Conclusão: A indução de genes antioxidantes está, pelo menos em parte, associada à citotoxicidade dos cimentos testados para a experiência de estresse oxidativo.

Insertion methods and gap/void formation in atraumatic restorative technique: A micro-CT analysis

Abstract Wetting the dentin is critical to atraumatic restorative treatment. The conventional insertion can be challenging when using high-viscosity glass-ionomer cement. This study evaluated the formation of gaps and voids after three insertion methods using micro-CT. Teeth underwent removal of occlusal and proximal caries through the atraumatic restorative treatment technique. Then, they were fixed in an artificial dental arch to simulate the clinical condition and were restored using three insertion methods: conventional, Centrix injection, and double-filling. Previous dentin conditioning procedures, steel matrix and wooden wedge application, and post-insertion procedures (digital compression and surface protection) were the same. The material was inserted using a manual instrument in the conventional technique and was inserted with a syringe in the Centrix injection group. In the double-filling technique, the tooth received a first layer of a flowable ionomer (through modifying the powder/liquid ratio), and a second layer (with standard ratio) was applied before the final set of the first one. A micro-CT unit scanned each tooth before and after restoration. Each cavity was defined as the volume of interest, and the volumes of gaps and voids were calculated. Data were analyzed using one-way ANOVA and Tukey posthoc test (p < .05). Double-filling had improved filling volume with lower values for gap volume, followed by Centrix injection. The conventional technique had the highest gap volume. No statistically significant difference was observed for void volume. Double-filling demonstrated fewer gaps, followed by Centrix injection, which is critical to obtain better adhesive, remineralizing, and antibacterial activities.

Resumo O molhamento da dentina parcialmente desmineralizada no fundo da cavidade dentária é fundamental para o sucesso do tratamento restaurador atraumático. No entanto, o método de inserção convencional pode ser desafiador ao usar cimento de ionômero de vidro de alta viscosidade. Este estudo avaliou a formação de gaps e vazios internos após três métodos de inserção de cimento de ionômero de vidro de alta viscosidade usando micro-CT. Dez terceiros molares foram submetidos à remoção de cárie oclusal através da técnica de tratamento restaurador atraumático e complementação proximal (com ou sem lesão pré-existente). Em seguida, foram fixados em uma arcada dentária artificial para simular a condição clínica. Os dentes foram restaurados usando a técnica de tratamento restaurador atraumático com três métodos de inserção: convencional, injeção Centrix e dupla inserção. Os procedimentos anteriores de condicionamento dentinário, inserção de matriz de aço, aplicação de cunha de madeira e procedimentos pós-inserção do material (como compressão digital e proteção de superfície) foram os mesmos para os três grupos testados. O material foi inserido com instrumento manual na técnica convencional, seguindo a metodologia clássica do tratamento restaurador atraumático. O material foi inserido com um dispositivo desenvolvido especificamente para esse fim na técnica de inserção com seringa tipo Centrix. Na técnica de dupla obturação, o dente recebeu uma primeira camada do cimento de ionômero de vidro mais fluido (obtido através da modificação da relação pó/líquido), e uma segunda camada (com relação pó/líquido padrão) foi aplicada antes da presa final da primeira. Um micro-CT escaneou cada dente antes e depois da restauração. Cada cavidade foi definida como o volume de interesse, e os volumes de gaps e vazios foram calculados. Os dados foram analisados por ANOVA one-way e teste post-hoc de Tukey com nível de significância de 5%. A dupla inserção melhorou significativamente o volume de preenchimento com valores percentuais mais baixos para o volume do gap, seguido pela injeção com seringa tipo Centrix. A técnica convencional apresentou o maior percentual de volume de gap. Nenhuma diferença estatisticamente significativa foi observada para o volume de vazios internos. O grupo de dupla inserção demonstrou menor formação de gaps, seguido pelo grupo de injeção com seringa tipo Centrix, que é fundamental para obter melhores atividades adesivas, remineralizantes e antibacterianas.

Effect of sodium/calcium hypochlorite on adhesion and adaptation of fiber posts luted with a dual resin cement

Abstract This study aimed to evaluate the effect of different concentrations of sodium hypochlorite (NaOCl) and calcium hypochlorite [Ca(OCl)2] on the bond strength and adaptation of glass fiber posts luted with a dual-curing resin cement. Fifty decoronated premolars were sectioned 14 mm from the apex and endodontically treated. The root canal filling was partially removed. The specimens were divided into 5 groups (n=10) according to the irrigant for post space irrigation: 0.9% sodium chloride (NaCl), (control); 2.5% NaOCl; 5.25% NaOCl; 2.5% Ca(OCl)2; and 5.25% Ca(OCl)2. For each group, irrigation was performed with 5 ml of solution. Afterward, the posts were luted with a dual-curing resin cement. One slice from each third was obtained and submitted to the push-out test and failure modes analysis. An additional slice from the middle third was submitted to confocal images for analysis of adaptation failures (gaps). Two-way ANOVA, Tukey's post-hoc, Kruskal-Wallis with Bonferroni adjusted, and chi-square tests, analyzed data. The group treated with 5.25% NaOCl showed lower bond strength values and generated more cohesive failures compared to the control (p < 0.05). Bond strength decreased from coronal to apical in the post space (p < 0.001). The groups treated with NaOCl had the highest percentages of gaps compared to the control (p < 0.05). Regardless of concentration, Ca(OCl)2 did not influence the bond strength and the occurrence of gaps (P > 0.05). Ca(OCl)2 is a good option for irrigating the post space before luting a fiber post with a dual-curing resin cement.

Resumo Este estudo teve como objetivo avaliar o efeito de diferentes concentrações de hipoclorito de sódio (NaOCl) e hipoclorito de cálcio [Ca(OCl)2] na resistência de união e adaptação de pinos de fibra de vidro cimentados com um cimento resinoso dual. Cinquenta pré-molares tiveram suas coroas removidas, foram seccionados a 14 mm do ápice e tratados endodonticamente. A obturação do canal radicular foi parcialmente removida. Os espécimes foram divididos em 5 grupos (n=10) de acordo com o irrigante para irrigação do espaço do pino: cloreto de sódio 0.9% (NaCl), (controle); NaOCl 2.5%; NaOCl 5.25%; Ca(OCl)2 2.5%; e Ca(OCl)2 5.25%. Para cada grupo, a irrigação foi realizada com 5 ml da solução. Posteriormente, os pinos foram cimentados com um cimento resinoso dual. Uma fatia de cada terço foi obtida e submetida ao teste push-out e análise dos modos de falha. Um corte adicional do terço médio foi submetido a imagens confocais para análise de falhas de adaptação (gaps). Os dados foram analisados pelos testes ANOVA de duas vias, post-hoc de Tukey, Kruskal-Wallis com ajuste de Bonferroni e qui-quadrado. O grupo tratado com NaOCl 5.25% apresentou menores valores de resistência de união e gerou mais falhas coesivas em relação ao controle (p < 0.05). A resistência de união diminuiu de coronal para apical no espaço do pino (p < 0.001). Os grupos tratados com NaOCl apresentaram os maiores percentuais de gaps em relação ao controle (p < 0.05). Independentemente da concentração, o Ca(OCl)2 não influenciou a resistência de união e a ocorrência de gaps (P > 0.05). O Ca(OCl)2 é uma boa opção para irrigar o espaço do pino antes de cimentar um pino de fibra com um cimento resinoso dual.

Tissue repair capacity of bioceramic endodontic sealers in rat subcutaneous tissue

Abstract This study aimed to evaluate the tissue repair capacity of four bioceramic endodontic sealers by quantifying type I and III collagen fibers. The following sealers were tested: EndoSequence BC Sealer (Brasseler, Brasseler, Savannah, USA), Bio C Sealer (Angelus, Londrina, Brazil), Bioroot RCS (Septodont, Santa Catarina, Brazil), and Sealer Plus BC (MKLife, Porto Alegre, Brazil). Polyethylene tubes 1.5 mm in diameter and 1 cm in length containing the endodontic sealers were implanted in the subcutaneous tissue of five rats (Rattus norvegicus albinus, Wistar lineage). After 14 days, the animals were euthanized, and collagen fibers were quantified from the histological tissue sections. Given a non-normal distribution of the data, a gamma regression with log link function was employed and implemented through the generalized linear models module, was used to test whether there was a significant difference between the sealers. The pairwise comparison was performed using Least significant difference. There were significant differences between the sealers for type I (p=0.001), type III (p=0.023), and total collagen (p=0.002). Overall, Bioroot sealer was statistically superior to the other sealers, except in the analysis of type III collagen, in which there was no difference between the Bioroot sealer and Bio C Sealer sealer and the control group (p>0.05). Bioroot RCS bioceramic endodontic sealer stimulates a greater production of collagen.

Resumo Este estudo visou avaliar a capacidade de reparação de tecidos de quatro cimentos endodônticos biocerâmicos através da quantificação de fibras colágenas de tipo I e III. Foram testados os seguintes cimentos: EndoSequence BC Sealer (Brasseler, Brasseler, Savannah, EUA), Bio C Sealer (Angelus, Londrina, Brasil), Bioroot RCS (Septodont, Santa Catarina, Brasil), e Sealer Plus BC (MKLife, Porto Alegre, Brasil). Foram implantados tubos de polietileno de 1,5 mm de diâmetro e 1 cm de comprimento contendo os cimentos endodônticos no tecido subcutâneo de cinco ratos (Rattus norvegicus albinus, linhagem Wistar). Após 14 dias, os animais foram eutanasiados e as fibras colágenas foram quantificadas a partir de cortes histológicos do tecido. Diante de uma distribuição não-normal dos dados, uma regressão gama com função de ligação log, implementada por meio do módulo de modelos lineares generalizados, foi empregada para testar se havia diferença significativa entre os cimentos. A comparação dois a dois foi realizada utilizando Least significant difference. Houve diferença significativa entre os cimentos para os colágenos tipo I (p=0,001), tipo III (p=0,023) e colágeno total (p=0,002). No geral, o cimento Bioroot foi estatisticamente superior aos demais cimentos, com exceção na análise do colágeno tipo III na qual não houve diferença entre o cimento Bioroot e o cimento Bio C Sealer e o grupo controle (p>0,05). O cimento endodôntico biocerâmico Bioroot RCS foi capaz de estimular uma maior produção de colágeno.

Influence of different surface treatments on bond strength of a Self-Adhesive resin cement to CAD-CAM materials / Influencia de los diferentes tratamientos superficiales en la unión del cemento resinoso autoadhesivo a los materiales CAD-CAM

To evaluate the shear bond strength (SBS) of self-adhesive resin cement when used with two different computer-aided design (CAD)-computer-aided manufacturing (CAM) materials after various surface treatments. Nanoceramic resin Lava Ultimate (LU) and feldspathic ceramic Vita Mark II (VM) CAD-CAM block samples were prepared with 1.5-mm thickness, and a total of 90 samples were obtained (N=90), with five samples of each block. The samples were divided into the following five groups according to the surface treatments (n=9): group 1, untreated (control); group 2,5% hydrofluoric acid etching; group 3, Er: YAG laser irradiation; group 4, tribochemical silica coating (Cojet); and group 5, air-abrasion with Al2O3. After silane application, resin cement was applied on a transparent matrix (diameter, 3mm; height, 2mm) on the blocks. SBS was determined using a universal testing device at a crosshead speed of 1mm/min. Two-way analysis of variance (ANOVA) and Tukey's post hoc tests were used to analyze the SBS values. LU showed the highest SBS value in group 4. The average SBS values in groups 3 and were found to be lower than that in the control group (p<0.05). When VM was examined, while all surface treatments increased the SBS values significantly, the highest SBS value was observed in group 4 (p<0.05). This study revealed that all surface treatments used negatively affected the bond strength values of self-adhesive resin cement to LU, except for Cojet application. The SBS values of resin cement with VM increased in all surface treatment application groups.

Evaluar la resistencia de unión al corte (SBS) del cemento de resina autoadhesivo cuando se utiliza con dos materiales diferentes de diseño asistido por computadora (CAD) y fabricación asistida por computadora (CAM) después de varios tratamientos superficiales. Se prepararon muestras de bloques CAD-CAM de resina Lava Ultimate (LU) y cerámica feldespática Vita Mark II (VM) con un espesor de 1,5mm, y se obtuvieron un total de 90 muestras (N=90), con cinco muestras de cada bloque. Las muestras se dividieron en los siguientes cinco grupos según los tratamientos superficiales (n=9): grupo 1, sin tratar (control); grupo 2, grabado con ácido fluorhídrico al 5%; grupo 3, irradiación con láser Er: YAG; grupo 4, recubrimiento triboquímico de sílice (Cojet); y grupo 5, aire-abrasión con Al2O3. Después de la aplicación de silano, se aplicó cemento de resina sobre una matriz transparente (diámetro, 3mm; altura, 2mm) sobre los bloques. La SBS se determinó usando un dispositivo de prueba universal a una velocidad de cruceta de 1mm/min. Se utilizaron análisis de varianza bidireccional (ANOVA) y pruebas post hoc de Tukey para analizar los valores de SBS. LU mostró el valor más alto de SBS en el grupo 4. Los valores promedio de SBS en los grupos 3 y fueron más bajos que en el grupo de control (p<0,05). Cuando se examinó VM, mientras que todos los tratamientos superficiales aumentaron significativamente los valores de SBS, el valor más alto de SBS se observó en el grupo 4 (p<0,05). Este estudio reveló que todos los tratamientos de superficie utilizados afectaron negativamente los valores de resistencia de la unión del cemento de resina autoadhesivo a LU, a excepción de la aplicación Cojet. Los valores de SBS del cemento de resina con VM aumentaron en todos los grupos de aplicación de tratamiento de superficie.

Resistencia de unión al cizallamiento de diferentes agentes de fijación a aleaciones metálicas odontológicas / Shear bond strength of different bonding agents to dental metal alloys

Introducción: La fijación de las restauraciones indirectas es uno de los pasos más importantes, para conseguir una adecuada retención y sellado de la interfase entre el material restaurador y el diente. Objetivo: Evaluar la resistencia de unión al cizallamiento de diferentes agentes de fijación a dos aleaciones metálicas utilizadas en odontología. Métodos: Estudio experimental in vitro. Cien especímenes de aleaciones de metales base, 50 de níquel-cromo y 50 de níquel-cromo-titanio fueron preparados y divididos de manera aleatoria en 5 grupos. Esta división se realizó acorde con el agente de fijación utilizado: sistema autograbante de dos pasos (Clearfil SE Bond; CSB), sistema adhesivo universal (Single Bond Universal; SBU), cemento resinoso autoadhesivo (Maxcem Elite; ME), ionómero de vidrio (IV) y fosfato de zinc (ZnPO). Posteriormente a la aplicación de cada agente de fijación, los especímenes tratados fueron almacenados en agua destilada por 24 h a 37 ºC y sometidos a un ensayo de resistencia de unión al cizallamiento. Resultados: La resistencia de unión al cizallamiento fue influenciada significativamente por el tipo de agente de fijación (p = 0,002) y el tipo de aleación utilizada (p < 0,001). La resistencia de unión al cizallamiento fue mayor, al utilizar el sistema Clearfil SE Bond, seguida de Single Bond Universal; las diferencias entre Maxcem Elite y el Fosfato de zinc no fueron significativas. Finalmente, el IV no mostró adhesión a ninguna de las aleaciones metálicas utilizadas. Conclusiones: El uso de Clearfil SE Bond aumentó la resistencia de unión de los cementos resinosos a las aleaciones metálicas(AU)

Introduction: The bonding of indirect restorations is one of the most important steps, in order to achieve adequate retention and sealing of the interface between the restorative material and the tooth. Objective: To evaluate the shear bond strength of different bonding agents to two metal alloys used in dentistry. Methods: In vitro experimental study. One hundred specimens of base metal alloys, 50 nickel-chromium and 50 nickel-chromium-titanium were prepared and randomly divided into 5 groups. This division was made according to the bonding agent used: two-step self-etching system (Clearfil SE Bond; CSB), universal adhesive system (Single Bond Universal; SBU), self-adhesive resin cement (Maxcem Elite; ME), glass ionomer (IV) and zinc phosphate (ZnPO). After the application of each bonding agent, the treated specimens were stored in distilled water for 24 hr at 37 ºC and subjected to a shear bond strength test. Results: Shear bond strength was significantly influenced by the type of bonding agent (p = 0.002) and the type of alloy used (p < 0.001). Shear bond strength was highest when using the Clearfil SE Bond system, followed by Single Bond Universal; the differences between Maxcem Elite and Zinc Phosphate were not significant. Finally, IV did not show adhesion to any of the metal alloys used. Conclusions: The use of Clearfil SE Bond increased the bond strength of resinous cements to metallic alloys(AU)

Effect of aging and cementation systems on the bond strength to root dentin after fiber post cementation

Abstract This study evaluated the effect of aging and cementation of fiber posts using glass ionomer and resin cements on push-out bond strength, failure mode, and resin tag formation. One hundred and twenty bovine incisors were used. After post-space preparation, the specimens were randomly allocated into 12 groups (n = 10) according to the cementation system used: GC - GC Gold Label Luting & Lining); RL - RelyX Luting 2; MC - MaxCem Elite; RU - RelyX U200 and the aging periods (24 hours, 6 months, and 12 months). Slices from the cervical, middle, and apical thirds were obtained and analyzed by push-out bond strength test and confocal laser scanning microscopy. One-way ANOVA and Tukey's post-hoc test was used at a significance level of 5%. For the push-out bond strength test, no differences among GC, RU, and MC in the cervical and middle thirds were observed, regardless of the period of storage (P > 0.05). In the apical third, GC and RU showed similar bond strength but higher than other groups (P > 0.05). After 12 months, GC showed the highest bond strength (P < 0.05). Bond strength to post-space dentin decreased over time, regardless of the cementation system used. Cohesive failure was the most frequent, regardless of the period of storage, cementation system, and post-space third. Tag formation was similar among all groups. After 12 months, GC showed the highest bond strength values.

Resumo Avaliar o efeito do envelhecimento e sistemas de cimentação usando ionômero de vidro e cimentos resinosos na resistência de união à dentina após a cimentação do pino de fibra. Cento e vinte incisivos bovinos foram utilizados. Após o preparo do pós-espaço, os corpos de prova foram distribuídos aleatoriamente em 12 grupos (n = 10) de acordo com o período de envelhecimento (24 horas, 6 meses e 12 meses) e o sistema de cimentação utilizado: GC - cimento de ionômero de vidro (GC Gold Label Cimentação e Revestimento); RL - RelyX Luting 2; MC - MaxCem Elite; RU - RelyX U200. Cortes dos terços cervical, médio e apical foram obtidos e analisados por teste de resistência de união push-out e microscopia confocal de varredura a laser. ANOVA one-way e teste de Tukey foi usado a um nível de significância de 5%. Para o teste de resistência de união, não foram observadas diferenças entre GC, RU e MC nos terços cervical e médio, independentemente do período de armazenamento (P > 0,05). No terço apical, GC e RU apresentaram resistência de união semelhante, porém superior aos demais grupos (P > 0,05). Após 12 meses, o GC apresentou a maior resistência de união (P < 0,05). A resistência de união à dentina no espaço para pino diminuiu ao longo do tempo, independentemente do sistema de cimentação utilizado. A formação de tags foi semelhante entre todos os grupos. Após 12 meses, o GC apresentou os maiores valores de resistência de união.

Mechanism of action of Bioactive Endodontic Materials

Abstract A continuous search for bioactive materials capable of supporting the replacement of damaged pulp tissue, with effective sealing potential and biocompatibility, has represented the attention of studies over the last decades. This study involves a narrative review of the literature developed by searching representative research in PUBMED/MEDLINE and searches in textbooks associated with the mechanism of action of bioactive materials (calcium hydroxide, mineral trioxide aggregate (MTA), and calcium silicate cements). The reflective analysis of the particularities of the chemical elements of these materials, considering the tissue and antibacterial mechanism of action, allows a better understanding of the characteristics and similarities in their tissue responses. Calcium hydroxide paste remains the antibacterial substance of choice as intracanal dressing for the treatment of root canal system infections. Calcium silicate cements, including MTA, show a favorable biological response with the stimulation of mineralized tissue deposition in sealed areas when in contact with connective tissue. This is due to the similarity between the chemical elements, especially ionic dissociation, the potential stimulation of enzymes in tissues, and the contribution towards an alkaline environment due to the pH of these materials. The behavior of bioactive materials, especially MTA and the new calcium silicate cements in the biological sealing activity, has been shown to be effective. Contemporary endodontics has access to bioactive materials with similar properties, which can stimulate a biological seal in lateral and furcation root perforations, root-end fillings and root fillings, pulp capping, pulpotomy, apexification, and regenerative endodontic procedures, in addition to other clinical conditions.

Resumo Uma busca contínua de materiais bioativos com capacidade de substituir o tecido pulpar danificado, com efetiva capacidade de selamento e biocompatibilidade, tem representado a atenção e foco de muitos estudos ao longo das últimas décadas. Este estudo envolve uma revisão narrativa da literatura desenvolvida por meio de pesquisas representativas encontradas no PUBMED/MEDLINE e pesquisas em livros didáticos associadas ao mecanismo de ação de materiais bioativos (hidróxido de cálcio, agregado de trióxido mineral (MTA) e cimentos de silicato de cálcio). A presente análise reflexiva das particularidades dos elementos químicos destes materiais bioativos, considerando o mecanismo de ação tecidual e antibacteriano, possibilita um melhor entendimento das características e similaridades no comportamento tecidual. A pasta de hidróxido de cálcio continua sendo a substância antibacteriana de escolha como medicação intracanal para o tratamento das infecções do sistema de canais radiculares. Este fato se deve a disponibilidade química de íons cálcio e hidroxila do hidróxido de cálcio aos tecidos, e a inibição enzimática bacteriana. Os cimentos de silicato de cálcio, dentre os quais inclui o MTA, apresentam uma resposta biológica favorável ao estímulo à deposição de tecido mineralizado nas áreas seladas e em contato com tecido conjuntivo. Este fato é decorrente da similaridade entre os elementos químicos, em especial devido a dissociação iônica, ao potencial estímulo de enzimas teciduais, e a contribuição com um meio alcalino decorrente do pH destes materiais. O comportamento dos materiais bioativos, em especial o MTA e os novos cimentos de silicato de cálcio na atividade de selamento biológico mostraram efetivos. A endodontia contemporânea atualmente conta com o potencial de materiais bioativos com propriedades análogas capaz de estimular o selamento biológico em perfurações radiculares laterais e de furca, em obturações radiculares, capeamento pulpar, pulpotomia, apicificação e procedimentos endodônticos regenerativos, além de outras condições clínicas.

Finite element analysis of PMMA bone cement reinforced screw plate fixation for osteoporotic proximal humeral fracture / 中国骨伤

OBJECTIVE@#With the help of finite element analysis, to explore the effect of proximal humeral bone cement enhanced screw plate fixation on the stability of internal fixation of osteoporotic proximal humeral fracture.@*METHODS@#The digital model of unstable proximal humeral fracture with metaphyseal bone defect was made, and the finite element models of proximal humeral fracture bone cement enhanced screw plate fixation and common screw plate fixation were established respectively. The stress of cancellous bone around the screw, the overall stiffness, the maximum stress of the plate and the maximum stress of the screw were analyzed.@*RESULTS@#The maximum stresses of cancellous bone around 6 screws at the head of proximal humeral with bone cement enhanced screw plate fixation were 1.07 MPa for No.1 nail, 0.43 MPa for No.2 nail, 1.16 MPa for No.3 nail, 0.34 MPa for No.4 nail, 1.99 MPa for No.5 nail and 1.57 MPa for No.6 nail. These with common screw plate fixation were:2.68 MPa for No.1 nail, 0.67 MPa for No.2 nail, 4.37 MPa for No.3 nail, 0.75 MPa for No.4 nail, 3.30 MPa for No.5 nail and 2.47 MPa for No.6 nail. Overall stiffness of the two models is 448 N/mm for bone cement structure and 434 N/mm for common structure. The maximum stress of plate appears in the joint hole:701MPa for bone cement structure and 42 0MPa for common structure. The maximum stress of screws appeared at the tail end of No.4 nail:284 MPa for bone cement structure and 240.8 MPa for common structure.@*CONCLUSION@#Through finite element analysis, it is proved that the proximal humerus bone cement enhanced screw plate fixation of osteoporotic proximal humeral fracture can effectively reduce the stress of cancellous bone around the screw and enhance the initial stability after fracture operation, thus preventing from penetrating out and humeral head collapsing.

Clinical application of targeted sealing with high viscosity bone cement and secondary injection of low viscosity bone cement in vertebroplasty / 中国骨伤

OBJECTIVE@#To observe the clinical efficacy of targeted sealing with high viscosity bone cement and secondary injection of low viscosity bone cement in the treatment of OVCFs patients with the fracture lines involved vertebral body margin.@*METHODS@#The elderly patients who underwent vertebroplasty for osteoporotic vertebral compression fractures from January 2019 to September 2021 were selected as the screening objects. Through relevant standards and further CT examination, 56 patients with fracture lines involving the anterior wall or upper and lower endplates of the vertebral body were selected for the study. There were 21 males and 35 females, aged from 67 to 89 years old with an average of (76.58±9.68) years. All 56 patients underwent secondary injection of bone cement during operation. Only a small amount of high viscosity cement was targeted to seal the edge of the vertebral body for the first time, and low viscosity cement was injected to the vertebral bodies during second bolus with well-distributed. The operation time, bone cement volume and bone cement leakage were recorded, and the pain relief was evaluated by visual analogue scale (VAS).@*RESULTS@#All patients were followed up for more than 3 months and the surgeries were successfully complete. The operation time was (50.41±10.30) min and the bone cement volume was (3.64±1.29) ml. The preoperative VAS was (7.21±2.41) points, which decreased significantly to (2.81±0.97) points 3 days after operation(P<0.05). Among the 56 patients, 2 cases(3.57%) had bone cement leakage, 1 case leaked to the paravertebral vein, and 1 case slightly bulged to the paravertebral through the crack when plugging the vertebral crack. Both patients had no obvious clinical symptoms.@*CONCLUSION@#In vertebroplasty surgery, targeted sealing of high viscosity bone cement and secondary injection of low viscosity bone cement can reduce intraoperative bone cement leakage and improve the safety of operation.

Analysis on characteristic of stage Ⅰ occupational cement pneumoconiosis patients / 中华劳动卫生职业病杂志

Objective: To analyze the clinical and imaging characteristics of stage Ⅰ occupational cement pneumoconiosis patients. Methods: In October 2021, the data of patients with occupational cement pneumoconiosis diagnosed by the Third Hospital of Peking University from 2014 to 2020 were collected, and the data of the patients' initial exposure age, dust exposure duration, diagnosis age, incubation period, chest X-ray findings, lung function and other data were analyzed retrospectively. Spearman grade correlation was used for correlation analysis of grade count data. The influencing factors of lung function were analyzed by binary logistic regression. Results: A total of 107 patients were enrolled in the study. There were 80 male patients and 27 female patients. The inital exposure age was (26.2±7.7) years, the diagnosis age was (59.4±7.9) years, the dust exposure duration was (17.9±8.0) years, and the incubation period was (33.1±10.3) years. The initial dust exposure age and the dust exposure duration in female patients were less than those in men, and the incubation period was longer than that in men (P<0.05). The imaging analysis showed the small opacities as"pp"accounted for 54.2%. 82 patients (76.6%) had small opacities distributed in two lung areas. The lung areas distribution of small opacities in female patients was less than that in male patients (2.04±0.19 vs 2.41±0.69, P<0.001). There were 57 cases of normal pulmonary function, 41 cases of mild abnormality and 9 cases of moderate abnormality. The number of lung regions with small opacities on X-ray was the risk factor for abnormal lung function in cement pneumoconiosis patients (OR=2.491, 95%CI=1.197-5.183, P=0.015) . Conclusion: The patients with occupational cement pneumoconiosis had long dust exposure duration and incubation period, light imaging changes and pulmonary function damage. The abnormal lung function was related to the range of pulmonary involvement.

Treatment of cement dislodgement after vertebral augmentation / 中华创伤骨科杂志

Objective:To analyze the clinical efficacy of treatment of cement dislodgement after vertebral augmentation for osteoporotic vertebral fractures.Methods:A retrospective study was conducted to analyze the data of 13 patients who had been treated at Department of Orthopaedics, The First Affiliated Hospital of Soochow University for cement dislodgement after vertebral augmentation for osteoporotic vertebral fractures from July 2013 to July 2022. There were 4 males and 9 females, with an average age of (76.5±8.6) years and a T value of bone mineral density of -3.3±0.6. By the CT and MRI features of cement dislodgement, their conditions fell in 4 types: cement loosening in situ (4 cases), anterior cement moving (6 cases), anterior cement moving with posterior bone mass moving (2 cases), and posterior cement moving (1 case). They were treated by percutaneous vertebroplasty (3 cases), pedicle screw fixation combined with bone graft fusion and decompression (7 cases), and conservative therapy (3 cases). The curative effects for surgical patients were evaluated by comparing their visual analogue scale (VAS), Oswestry dysfunction index (ODI) and cobb angle of kyphosis at preoperation, 1 week and 1 month postoperation, and the last follow-up, and Frankel grading for nerve injury as well. The curative effects for patients undergoing conservative treatment were evaluated by observing their symptoms.Results:This cohort was followed up for 7 (5, 12) months after treatment. The VAS scores [5.0 (4.0, 5.0) points, 3.0 (2.0, 3.0) points, and 3.0 (2.0, 3.0) points] in the 10 surgical patients at 1 week and 1 month postoperation and the last follow-up were significantly improved compared with the preoperative value [8.5 (8.0, 9.0) points] ( P<0.05); the VAS scores at 1 month postoperation and the last follow-up were also significantly improved compared with that at 1 week postoperation ( P < 0.05), but there was no significant difference between the last follow-up and 1 month postoperation ( P > 0.05). The ODIs (50.6%±4.2%, 37.8%±4.5%, and 29.3%±5.6%) in the 10 surgical patients at 1 week and 1 month postoperation and the last follow-up were significantly improved compared with the preoperative value (93.2%±3.6%), showing significant differences in pairwise comparisons ( P<0.05). The cobb angles [10.0 (9.0, 11.0)°, 9.0 (9.0, 11.0)°, and 10.0 (9.0, 12.0)°] in the 10 surgical patients at 1 week and 1 month postoperation and the last follow-up were significantly improved compared with the preoperative value [12.5 (11.0, 14.0)°] ( P<0.05) , but there was no statistically significant difference between the time points after operation ( P>0.05). The Frankel grading was significantly improved in the 6 patients with nerve injury after operation. Of the 3 patients undergoing conservative treatment, the symptoms were cured in one, showed no change during follow-up in one, and aggravated in one. Conclusion:Surgical treatment can significantly relieve pain, improve spinal dysfunction and repair nerve injury in patients with bone cement dislodgement after vertebral augmentation.

Risk analysis of bone cement leakage after percutaneous puncture vertebroplasty for osteoporotic spinal compression fractures and construction of a predictive model with column line drawings / 解剖学报

Objective To analysis risk factor and to construct a line graph prediction model for bone cement leakage after percutaneous transluminal vertebroplasty treatment in patients with osteoporotic spinal compression fractures. Methods A total of 236 patients with osteoporotic spinal compression fractures who came to our hospital from December 2019 to December 2021 were selected for the stud)', and they were divided into a leakage group (n = 58) and a non-leakage group (n = 178) according to whether bone cement leakage occurred after percutaneous transluminal vertebroplasty treatment. The clinical data were collected to analyze the factors associated with bone cement leakage; The work receiver operating characteristic

Biomechanical Analysis on NiTi Memory Alloy Stent for Lumbar Interbody Fusion / 医用生物力学

Objective To evaluate biomechanical properties of the nickel-titanium (NiTi) memory alloy stent and its in vitro biomechanical properties for lumbar interbody fusion. Methods The mechanical properties of the NiTi memory alloy stent were tested on mechanical testing machine. Moreover, lumbar interbody fusion was simulated on fresh lumbar specimens, and biomechanical properties of the NiTi memory alloy stent with matching bone graft for used for lumbar interbody fusion were analyzed and compared with the traditional box-shape cage. Results The maximum compressive strength of the NiTi memory alloy stent was ( 12 964 ± 962) N. The maximum deformation within the effective range of memory characteristics was (4. 68±0. 03) mm. The recovery rate of the NiTi memory alloy stent was up to 99. 86% . Compared with the intact lumbar model, the stability of the operative segment after the simulated lumbar interbody fusion using NiTi memory alloy stent alone was increased in the direction of anterior flexion, posterior extension, lateral flexion and rotation, which was equivalent to the box shape cage group (P>0. 05). After the combined use of autogenous bone granule and absorbable bone cement the ROM of the operative segment was further reduced (P0. 05). The pull-out strength of the NiTi memory alloy stent with matching bone graft group was significantly stronger than that of the box-shape cage group (P<0. 05). Conclusions The NiTi memory alloy stent in this study was designed with a matched bone granule-absorbable bone cement graft,which provided a new idea for the further optimization and development of lumbar interbody fusion. With excellent support and deformation properties, this NiTi memory alloy stent is biomechanical equivalent to the traditional box shape cage for lumbar interbody fusion, and can greatly improve the stability of surgical segment and the pull-out strength of implants after the combined use of autogenous bone granule and absorbable bone cement.

Robot-assisted PVP for the treatment of osteoporotic fractures of the upper thoracic vertebra / 中国骨伤

OBJECTIVE@#To investigate the clinical effect of "Tianji" orthopedic robot-assisted percutaneous vertebro plasty(PVP) surgery in the treatment of upper thoracic osteoporotic fracture.@*METHODS@#A retrospective analysis was performed on 32 patients with upper thoracic osteoporotic fracture who underwent PVP surgery in Shenzhen Hospital of Traditional Chinese Medicine from August 2016 to June 2022. There were 8 males and 24 females, ranging in age from 58 to 90 years old, with a mean of (67.75±12.27) years old. Fifteen patients were treated with robot-assisted PVP surgery (robot group), including 3 males and 12 females, with an average age of (68.5±10.3) years. Fracture location:1 case of T2 fracture, 1 case of T3 fracture, 3 cases of T4 fracture, 3 cases of T5 fracture, and 7 cases of T6 fracture. The follow-up period ranged from 1.0 to 3.0 months, with a mean of (1.6±0.7) months. Seventeen patients underwent routine PVP surgery (conventional group), including 5 males and 12 females, with an average age of (66.8±11.6) years old. Fracture location:1 case of T1 fracture, 5 cases of T4 fracture, 2 cases of T5 fracture and 9 cases of T6 fracture. The follow-up period ranged from 0.5 to 4.0 months, with a mean of (1.5±0.6) months. Preoperative and postoperative visual analogue scale(VAS) and Oswestry disability index(ODI) scores were compared between the two groups, and the number of punctures, perspective times, operation time, intraoperative blood loss, bone cement distribution, bone cement leakage, and intraoperative radiation dose were compared between the two groups.@*RESULTS@#Number of punctures times, perspective times, operation time, intraoperative blood loss, bone cement distribution, bone cement leakage and intraoperative radiation dose in the robot group were all significantly better than those in the conventional group(P<0.05). VAS of 2.03±0.05 and ODI of (22.16±4.03) % in the robot group were significantly better than those of the robot group before surgery, which were (8.67±0.25) score and (79.40±7.72)%(t=100.869, P<0.001;t=25.456, P<0.001). VAS of 2.17±0.13 and ODI of (23.88±6.15)% in the conventional group were significantly better than those before surgery, which were (8.73±0.18) score and (80.01±7.59)%(t=121.816, P<0.001;t=23.691, P<0.001). There was no significant difference in VAS and ODI between the two groups after operation (t=-3.917, P=0.476;t=-0.922, P=0.364).@*CONCLUSION@#Robot-assisted PVP in the treatment of upper thoracic osteoporotic fractures can further improve surgical safety, reduce bone cement leakage, and achieve satisfactory clinical efficacy.

Research progress of new multifunctional bone cement in bone tumor therapy / 中国修复重建外科杂志

OBJECTIVE@#The research progress of new multifunctional bone cement in bone tumor therapy in recent years was reviewed, in order to provide help for the future research of anti-tumor bone cement.@*METHODS@#The related literature on the treatment of bone tumors with new multifunctional bone cement at home and abroad in recent years was extensively reviewed and summarized.@*RESULTS@#The new multifunctional bone cements include those with the functions of photothermotherapy, magnetic thermotherapy, chemoradiotherapy, and antibacterial after operation, which are discussed from the aspects of anti-tumor, drug controlled release, and cytotoxicity. Controlled drug release has been achieved in multifunctional bone cements by adjusting heat and pH or incorporating particles such as chitosan oligosaccharides and γ-cyclodextrin. At present, multifunctional bone cement with hyperthermia, radiotherapy, and chemotherapy has effectively inhibited the local recurrence and distant metastasis of bone tumors. Broadening the application of bone cement for photothermal and magnetic thermal therapy to deeper bone tumors, investigating more precise controlled release of drug-loaded bone cement, and introducing nanoparticles with both thermal conversion and intrinsic enzymatic activities into bone cement for synergistic anti-tumor therapy are promising research directions.@*CONCLUSION@#The new multifunctional bone cement inhibits bone tumor cells, promotes new bone formation in bone defects, and prevents incision infection after tumor resection. Certain progress has been made in anti-tumor, antibacterial, drug-controlled release, and reduction of cytotoxicity. Expanding the deeper application range of the new multifunctional bone cement, verifying the safety in clinical application, and focusing on the individualized treatment of the new multifunctional bone cement are the problems that need to be solved in the future.

Influence of paper mixing pads thickness on the compressive strength of glass ionomer cement / 北京大学学报(医学版)

OBJECTIVE@#To explore the influence of the thickness of mixed cardboard on the compressive strength of glass ionomer cement and the associated factors.@*METHODS@#Three different types of glass ionomer cements were mixed on the top of 60, 40, 20 and 1 pieces of paper (P60, P40, P20 and P1), respectively. The compressive strength of the materials was tested after solidification, and the bubble rate was calculated with the assistance of scanning electron microscope.@*RESULTS@#(1) Compressive strength: ① ChemFil Superior glass ionomer (CF): The average compressive strength of P1 group was the highest, which was significantly different from that of P40 and P60 groups (P values were 0.041 and 0.032 respectively); ② To Fuji IX GP glass ionomer (IX): The average compressive strength of P1 group was the highest, which was statistically different from that of P40 and P60 groups (P values were 0.042 and 0.038 respectively); ③ Glaslonomer FX-Ⅱ glass ionomer cement (FX): The average compressive strength of P1 group was the highest, which was statistically different from that of P20, P40 and P60 groups (P values were 0.031, 0.040 and 0.041 respectively), but there was no statistical difference among the other groups. All the three materials showed that the compressive strength of glass ions gradually increased with the decrease of the thickness of the blended paperboard, and the two materials had a highly linear negative correlation, the correlation coefficients of which were CF-0.927, IX-0.989, FX-0.892, respectively. (2) Scanning electron microscope: P1 group had the least bubbles among the three materials.@*CONCLUSION@#It indicates that the thickness of mixed cardboard has a negative correlation with the compressive strength of glass ions. The thicker the mixed cardboard is, the greater the elasticity is. Excessive elasticity will accelerate the mixing speed when the grinding glass ions. Studies have shown that the faster the speed of artificial mixing is, the more bubbles is produced.The thicker ther mixed cardboard is, the more bubblesn are generated by glass ionomer cement, and the higher the compressive strength is. Using one piece of paper board to mix glass ionomer cement has the least bubbles and can obtain higher compressive strength.