In Vitro Biocompatibility Evaluation of a Root Canal Filling Material That Expands on Water Sorption

Effect of CPoint, EndoSequence BC, and Gutta-percha Points on Viability and Gene Expression of Periodontal Ligament Fibroblasts

Objective:

This study aimed to investigate the cytotoxic and biomodulatory potential of conventional gutta-percha (CGP) points, gutta-percha points containing bioceramics (BC), and CPoint polymer (CP) points on periodontal ligament (PDL) cells in vitro.

Methods:

PDL fibroblasts were cultured and stimulated with extracts of CGP, BC, and CP in serial dilutions to evaluate cell viability using MTT assay. Next, the 1:5 dilution was used to stimulate the cells for 72 h to assess the gene expression of type I collagen (COL-1) and cement protein 1 (CEMP-1), by reverse transcription followed by quantitative PCR. Data were statistically analyzed using one-way analysis of variance (ANOVA) (P<0.05).

Results:

Pure extracts of CGP and CP were found to be cytotoxic for PDL (P<0.01). Once diluted to 1:5, only CP showed cytotoxicity. BC did not affect cell viability in any extract sample. No extract significantly altered the gene expression of COL-1. For CEMP-1, a significant increase in gene expression was observed only for CGP (P<0.05).

Conclusion:

CP was found to be more cytotoxic than CGP, while BC demonstrated no cytotoxicity. The tested cones did not affect COL-1 gene expression, while CGP upregulated CEMP-1. Our results suggest that obturation point components may affect the biological responses of PDL fibroblasts.

Cytotoxicity and biocompatibility of a new bioceramic endodontic sealer containing calcium hydroxide

This study evaluated the cytotoxicity and biocompatibility of a new bioceramic endodontic sealer (i.e., Sealer Plus BC) in comparison with those of MTA Fillapex and AH Plus. L929 fibroblasts were cultured and Alamar Blue was used to evaluate cell viability of diluted extracts (1:50, 1:100, and 1:200) from each sealer at 24 h. Polyethylene tubes that were filled with material or empty (as a control) were implanted in the subcutaneous tissue of rats. The rats were killed after 7 and 30 d (n = 8), and the tubes were removed for histological analysis. Parametric data was analyzed using a one-way ANOVA test, and nonparametric data was analyzed via the Kruskal-Wallis test followed by the Dunn test (p < 0.05). A reduction in cell viability was observed in the extracts that were more diluted for Sealer Plus BC when compared to that of Control and AH Plus (p < 0.05). However, the 1:50 dilution of the Sealer Plus BC was similar to that of the Control (p > 0.05). Conversely, more diluted extracts of MTA Fillapex (1:200) and AH Plus (1:100 and 1:200) were similar to the Control (p > 0.05). Histological analysis performed at 7 d did not indicate any significant difference between tissue response for all materials, and the fibrous capsule was thick (p > 0.05). At 30 d, Sealer Plus BC was similar to the Control (p > 0.05) and MTA Fillapex and AH Plus exhibited greater inflammation than the Control (p < 0.05). The fibrous capsule was thin for the Control and for most specimens of Sealer Plus BC and AH Plus. Thus, Sealer Plus BC is biocompatible when compared to MTA Fillapex and AH Plus, and it is less cytotoxic when less-diluted extracts are used.

Novel Calcium Zirconate Silicate Cement Biomineralize and Seal Root Canals

This study evaluated the sealing ability of gutta-percha (GP) with a calcium silicate-based sealer and a novel calcium zirconate containing calcium silicate cement (ZC). The root canals of the extracted premolars were prepared, which were then randomly allocated to three experimental groups (12 root canals per group) for obturation by continuous wave of condensation with the GP and AH 26 sealer (CW); obturation using a single GP with a calcium silicate-based EndoSequence BC sealer (SC); or obturation with ZC. The roots were inserted into sterile Eppendorf tubes, which were inoculated coronally with Porphyromonas gingivalis. The amount of endotoxin leakage into the apical reservoirs were measured using the Limulus Amebocyte Lysate (LAL) assay over 21 days, with comparisons made using one-way ANOVA and Scheffe’s tests (α = 0.05). After 21 days, 75% of the canals that had been obturated by SC, 50% of those obturated by CW and 42% of those obturated by ZC showed endotoxin leakage. The amount of leakage was higher in the SC canals than in the CW (p = 0.031) or ZC (p = 0.03) canals, although there was no significant difference in the amount of leakage for CW and ZC (p > 0.05). X-ray diffraction revealed the presence of tricalcium silicate (Ca₃SiO₅) and calcium zirconate (CaZrO₃) in the synthesized ZC. Scanning electron microscopy revealed mineralized precipitates on the dentin of canals obturated by ZC. The novel calcium zirconate silicate cement appears to promote biomineralization and seal root canals at least as effectively as the conventional sealer.

Sealing ability of a novel hydrophilic vs. conventional hydrophobic obturation systems: A bacterial leakage study

Aim:

Comparative assessment of apical sealing ability of a novel Smart-Seal System, Resilon, and conventional Gutta-Percha system using a bacterial leakage model.

Materials and Methods:

Seventy freshly extracted human single rooted teeth with fully formed apices were randomly divided into three groups (20 each) and two control groups (5 positive and 5 negative). Teeth were de-coronated, and roots were standardized to a working length of 16 mm. Root canal preparation was done with rotary pro-taper file system in all groups. Group A was obturated using Smart-Seal system (Hydrophilic), Group B using Resilon/Epiphany system (Hydrophilic), and Group C using Gutta-Percha (GP)/AH plus system (Hydrophobic) in a single cone technique. Using Enterococcus faecalis, a split chamber bacterial leakage model was developed to evaluate the sealing ability of three obturation systems. Samples will be monitored every 24 hours for 60 days.

Results:

All three groups have shown leakage. Novel Smart-Seal System and Resilon have shown similar results and relatively lesser samples leaked in comparison to GP obturations at the end of the observation period. There was no significant difference amongst Resilon and Smart-Seal System (P > 0.05) but there was a significant difference amongst them when compared to GP obturations (P < 0.05).

Conclusion:

Hydrophilic obturations of the root canal shows a better resistance to bacterial leakage as compared to hydrophobic obturations.

Quality of obturation achieved by a non-gutta-percha-based root filling system in single-rooted canals

INTRODUCTION

The present study examined the quality of obturation in root canals filled by an experimental non-gutta-percha-based (NGP) root filling system using warm vertical or cold lateral compaction. The quality of obturation was evaluated by comparing the volumetric percentage of gaps and voids identified from similar canals obturated with gutta-percha and an epoxy resin-based sealer using the same obturation techniques.

METHODS

Forty single-rooted premolars with oval-shaped canals were cleaned, shaped, and obturated with 1 of the 4 material/obturation technique combinations (n = 10). Filled canals were scanned with micro-computed tomographic imaging. Reconstructed images were analyzed for the volumetric percentage of gaps and voids at 3 canal levels (0-4, 4-8, and 8-12 mm from the working length). Roots were sectioned at the 4-mm, 8-mm, and 12-mm levels. Scanning electron microscopic images of negative replicas of root sections were examined to quantify the circumferential percentage of interfacial gaps and the area percentage of intracanal voids. Data were analyzed with parametric or nonparametric statistical methods.

RESULTS

A statistically significant difference was found for the volumetric percentage distribution of gaps and voids for "obturation technique" but not for "material." Significantly higher percentages of gaps and voids were identified in canals obturated with the NGP system using cold lateral compaction. Examination of negative replicas ascribed this difference to a higher area percentage of interfacial gaps rather than more intracanal voids.

CONCLUSIONS

Using warm vertical compaction, the NGP system fulfils the objective of 3-dimensional obturation of the canal space in a manner comparable with the results achieved with gutta-percha and a root canal sealer.

Effects of tricalcium silicate cements on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells in vitro

Tricalcium silicate cements have been successfully employed in the biomedical field as bioactive bone and dentin substitutes, with widely acclaimed osteoactive properties. This research analyzed the effects of different tricalcium silicate cement formulations on the temporal osteoactivity profile of human bone marrow-derived mesenchymal stem cells (hMW-MSCs). These cells were exposed to four commercially available tricalcium silicate cement formulations in osteogenic differentiation medium. After 1, 3, 7 and 10 days, quantitative real-time polymerase chain reaction and Western blotting were performed to detect expression of the target osteogenic markers ALP, RUNX2, OSX, OPN, MSX2 and OCN. After 3, 7, 14 and 21 days, alkaline phosphatase assay was performed to detect changes in intracellular enzyme level. An Alizarin Red S assay was performed after 28 days to detect extracellular matrix mineralization. In the presence of tricalcium silicate cements, target osteogenic markers were downregulated at the mRNA and protein levels at all time points. Intracellular alkaline phosphatase enzyme levels and extracellular mineralization of the experimental groups were not significantly different from the untreated control. Quantitative polymerase chain reaction results showed increases in downregulation of RUNX2, OSX, MSX2 and OCN with increasing time of exposure to the tricalcium silicate cements, while ALP showed peak downregulation at day 7. For Western blotting, OSX, OPN, MSX2 and OCN showed increased downregulation with increased exposure time to the tested cements. Alkaline phosphatase enzyme levels generally declined after day 7. Based on these results, it is concluded that tricalcium silicate cements do not induce osteogenic differentiation of hBM-MSCs in vitro.

Ability of new obturation materials to improve the seal of the root canal system: a review

New obturation biomaterials have been introduced over the past decade to improve the seal of the root canal system. However, it is not clear whether they have really produced a three-dimensional impervious seal that is important for reducing diseases associated with root canal treatment. A review of the literature was performed to identify models that have been employed for evaluating the seal of the root canal system. In vitro and in vivo models are not totally adept at quantifying the seal of root canals obturated with classic materials. Thus, one has to resort to clinical outcomes to examine whether there are real benefits associated with the use of recently introduced materials for obturating root canals. However, there is no simple answer because endodontic treatment outcomes are influenced by a host of other predictors that are more likely to take precedence over the influence of obturation materials. From the perspective of clinical performance, classic root filling materials have stood the test of time. Because many of the recently introduced materials are so new, there is not enough evidence yet to support their ability to improve clinical performance. This emphasizes the need to translate anecdotal information into clinically relevant research data on new biomaterials.

Biosmart materials: breaking new ground in dentistry

By definition and general agreement, smart materials are materials that have properties which may be altered in a controlled fashion by stimuli, such as stress, temperature, moisture, pH, and electric or magnetic fields. There are numerous types of smart materials, some of which are already common. Examples include piezoelectric materials, which produce a voltage when stress is applied or vice versa, shape memory alloys or shape memory polymers which are thermoresponsive, and pH sensitive polymers which swell or shrink as a response to change in pH. Thus, smart materials respond to stimuli by altering one or more of their properties. Smart behaviour occurs when a material can sense some stimulus from its environment and react to it in a useful, reliable, reproducible, and usually reversible manner. These properties have a beneficial application in various fields including dentistry. Shape memory alloys, zirconia, and smartseal are examples of materials exhibiting a smart behavior in dentistry. There is a strong trend in material science to develop and apply these intelligent materials. These materials would potentially allow new and groundbreaking dental therapies with a significantly enhanced clinical outcome of treatments.

In vitro biocompatibility and oxidative stress profiles of different hydraulic calcium silicate cements

INTRODUCTION

MTA Plus is a new calcium silicate cement with unknown cytotoxicity characteristics. The objectives of this study were to examine the effect of MTA Plus on the viability, apoptosis/necrosis profile, and oxidative stress levels of rat odontoblast-like cells.

METHODS

MDPC-23 cells were exposed to gray and white MTA Plus (GMTAP, WMTAP), gray and white ProRoot MTA (GMTA, WMTA) cements, or their eluents. The cells were evaluated for (1) cell viability by using XTT assay, (2) apoptosis/necrosis by using flow cytometry and confocal laser scanning microscopy, and (3) oxidative stress by measuring reactive oxygen species.

RESULTS

XTT assay showed that all test cements exhibited marked initial cytotoxicity that decreased with time. By the end of the third week, GMTAP and GMTA were comparable to untreated cells (negative control) in terms of cell viability, whereas WMTAP and WMTA were significantly lower than the untreated cells. Apoptosis/necrosis profiles of cells exposed to WMTAP and GMTAP were not significantly different from untreated cells, whereas cells exposed to WMTA and GMTA showed significantly less viable cells. All experimental groups exhibited reduction of intracellular reactive oxygen species formation compared with untreated cells, although cells exposed to WMTA were not significantly different from untreated cells.

CONCLUSIONS

Both the gray and white versions of MTA Plus possess negligible in vitro cytotoxic risks that are time and dilution dependent. They enrich the spectrum of hydraulic calcium silicate cements currently available to clinicians for endodontic applications.