Effect of Argon Plasma on Root Dentin after Use of 6% NaOCl

Effect of pretreatment of root dentin surface with cold atmospheric plasma on improving the bond strength of fiber post and resin cement: In vitro study

INTRODUCTION

Achieving stable adhesion between fiber post and interradicular dentin is a challenging process in the restoration of endodontically treated teeth. This study was conducted to investigate the effect of surface pretreatment with cold atmospheric plasma (CAP) on improving the bond strength between them.

MATERIALS AND METHODS

Forty-eight single-canal mandibular premolars were cut 1 mm above the cementoenamel junction to keep the root length of 14 mm or more. After endodontic treatment and preparation of the post space, the teeth were divided into four groups regarding the pretreatment of dentin surfaces, including normal saline, ethylenediaminetetraacetic acid (EDTA), CAP, and CAP + EDTA groups. The data were analyzed using paired and independent t-test and one-way analysis of variance and the significance level was set at p < .05.

RESULTS

The bond strength was significantly higher in the coronal third than in the apical third in all the groups. Moreover, the bond strength was significantly higher in the CAP + EDTA-treated group. The bond strength increased significantly in the CAP group compared to the normal saline group. In addition, the bond strength increased significantly in the CAP or EDTA groups compared to the control group. The lowest bond strength belonged to the control group (normal saline).

CONCLUSION

The surface pretreatment with CAP (alone or in combination with EDTA) played a significant role in improving the bond strength of fiber post and root canal dentin.

Functionalization of gutta-percha surfaces with argon and oxygen plasma treatments to enhance adhesiveness

Gutta-percha's lack of adhesion has been presented as a drawback to avoid gaps at sealer/gutta-percha interface. Plasma treatments have been scarcely assessed on gutta-percha surfaces as a method of enhancing adhesiveness. This study aimed to evaluate the effect of low-pressure Argon and Oxygen plasma atmospheres on conventional and bioceramic gutta-percha standardized smooth discs, assessing their roughness, surface free energy, chemical structure, and sealer wettability. A Low-Pressure Plasma Cleaner by Diener Electronic (Zepto Model) was used. Different gases (Argon or Oxygen), powers (25 W, or 50 W), and exposure times (30 s, 60 s, 120 s, or 180 s) were tested in control and experimental groups. Kruskal-Wallis and Student's t-test were used in data analysis. Statistically significant differences were detected when P < 0.05. Both gases showed different behaviors according to the parameters selected. Even though chemical changes were detected, the basic molecular structure was maintained. Argon or Oxygen plasma treatments favoured the wetting of conventional and bioceramic gutta-perchas by Endoresin and AH Plus Bioceramic sealers (P < 0.001). Overall, the functionalization of gutta-percha surfaces with Argon or Oxygen plasma treatments can increase roughness, surface free energy and wettability, which might improve its adhesive properties when compared to non-treated gutta-percha.

Effect of Root Dentin Pretreatment on Micro-Push-Out Bond Strength of Fiber Posts to Root Canal Dentin: Cold Atmospheric Argon Plasma (CAAP) and Ethylenediaminetetraacetic Acid (EDTA)

Purpose

Debonding from the root canal dentin is the most common failure mode of fiber posts. This study aimed to assess the effects of cold atmospheric argon plasma (CAAP) and ethylenediaminetetraacetic acid (EDTA) on micro-push-out bond strength of fiber posts to root canal dentin.

Materials and Methods

Forty maxillary canine teeth were decoronated, underwent endodontic treatment, and were stored in an incubator for 7 days. After post space preparation, the teeth were randomly divided into four groups for different surface treatments: (I) saline, (II) 17% EDTA, (III) CAAP, and (IV) 17% EDTA + CAAP. Fiber posts (Whitepost no. 2, FGM) were cemented into the root canals using Panavia F2.0 resin cement, and 1 mm-thick sections were made at the coronal, middle, and apical thirds of the roots. The samples underwent micro-push-out bond strength test. The mode of failure was also determined under a stereomicroscope. Data were analyzed using three-way ANOVA and Tukey's post hoc test (α = 0.05). The mode of failure data were analyzed using the chi-square test.

Results

The mean micro-push-out bond strength of fiber posts was not significantly different in the four groups (P > 0.05). However, the bond strength values in the coronal third were significantly higher than the corresponding values in the apical third (P=0.01). There was no significant difference in the modes of failure between the groups (P > 0.05).

Conclusion

Application of CAAP alone or in combination with 17% EDTA could not successfully increase the bond strength of fiber posts to root canal dentin.

Effects of cold atmospheric pressure plasma jet on human apical papilla cell proliferation, mineralization, and attachment

OBJECTIVES

To investigate the direct effects of cold atmospheric pressure plasma jet on cell proliferation and mineralization on human apical papilla cells and its indirect effect on cell attachment on plasma-treated dentin.

MATERIALS AND METHODS

Plasma was directly applied to cell culture for various durations. Cell proliferation was evaluated using AlamarBlue® assay. Mineralization was assessed using Alizarin Red S staining after 14 and 21 days. The cell attachment to plasma-treated dentin surface was evaluated using an ex vivo immature tooth model, and the protocols varied based on root canal irrigants (NSS or 17% EDTA), the durations of plasma application (0, 30, or 60 s), and the different positions of the plasma needle (coronal or middle). The attached cells were visualized using the immunofluorescence staining and the positive-staining cells were counted.

RESULTS

There was no difference in the cell proliferation between the untreated and plasma-treated cells. However, the plasma-treated cells tended to have lower levels of calcium deposition, especially after the 60-s plasma application (p < 0.05). Finally, significantly greater numbers of attached cells were shown when NSS was combined with plasma treatment when compared to the untreated cells (p < 0.05), whereas no difference was observed when EDTA was used as the irrigant.

CONCLUSIONS

Plasma might disturb the mineralization of the cells. Interestingly, the dentin conditioning process using a plasma jet with NSS irrigation may enhance cell attachment.

CLINICAL RELEVANCE

Cold atmospheric pressure plasma jet may be an alternative treatment in regenerative endodontic procedures in order to improve cell attachment in the root canal system.

The effects of non-thermal plasma and conventional treatments on the bond strength of fiber posts to resin cement

Objectives

This study compared the effect of hexamethyldisiloxane (HMDSO) and ammonia (NH₃) plasmas on the bond strength of resin cement to fiber posts with conventional treatments.

Materials and Methods

Sixty-five fiber posts were divided into 5 groups: Control (no surface treatment); H₂O₂ (24% hydrogen peroxide for 1 min); Blasting (blasting with aluminum oxide for 30 sec); NH₃ (NH₃ plasma treatment for 3 min); HMDSO (HMDSO plasma treatment for 15 min). After the treatments, the Ambar adhesive (FGM Dental Products) was applied to the post surface (n = 10). The fiber post was inserted into a silicon matrix that was filled with the conventional resin cement Allcem Core (FGM). Afterwards, the post/cement specimens were cut into discs and subjected to a push-out bond strength (POBS) test. Additionally, 3 posts in each group were evaluated using scanning electron microscopy. The POBS data were analyzed by one-way analysis of variance and the Tukey's honest significant difference post hoc test (α = 0.05).

Results

The Blasting and NH₃ groups showed the highest POBS values. The HMDSO group showed intermediate POBS values, whereas the Control and H₂O₂ groups showed the lowest POBS values.

Conclusion

Blasting and NH₃ plasma treatments were associated with stronger bonding of the conventional resin cement Allcem to fiber posts, in a procedure in which the Ambar adhesive was used.

Efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl

Resumo Introdução O tratamento de plasma é uma tecnologia eficaz que pode manter as propriedades internas dos materiais inalteradas após o tratamento, modificando apenas a superfície. Objetivo Avaliar o efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl 6%. Material e método Foram utilizados 60 incisivos bovinos. A coroa foi removida, a raiz foi dividida e as faces planificadas, totalizando 120 segmentos referentes ao terço cervical. As amostras foram divididas em dois grupos: controle (imersa em NaOCl 6%, lavada com água destilada, seca, imersa em EDTA 17%, lavada e seca) e plasma de oxigênio (após tratamento descrito no grupo controle, plasma de oxigênio foi aplicado por 30 s). As amostras foram avaliadas qualitativamente em relação à topografia por microscopia eletrônica de varredura, utilizando-se microfotografias com ampliação de 1.000×. O goniômetro Ramé-hart foi utilizado para a mensuração do ângulo de contato entre as superfícies e as seguintes soluções foram utilizadas: água, etilenoglicol e di-iodometano. Em seguida, a energia de superfície, representada pelas componentes polar e dispersiva, foi calculada. Avaliou-se também o escoamento dos cimentos Pulp Canal Sealer EWT (PCS) e Real Sal SE (RS) na superfície dentinária. Os dados foram analisados estatisticamente utilizando os testes Kruskal-Wallis e Mann-Whitney U (p<0,05). Resultado O tratamento com plasma levou à formação de uma camada semelhante à smear layer na superfície dentinária. Este tratamento levou a um aumento da energia de superfície e da componente polar, favorecendo a hidrofilicidade da superfície. Entretanto, desfavoreceu o escoamento do cimento PCS e não influenciou no escoamento do cimento RS. Conclusão O plasma de oxigênio ocasionou mudanças topográficas na superfície dentinária, favorecendo a hidrofilicidade desta. Contudo, não favoreceu o escoamento dos cimentos endodônticos na dentina.