Cytotoxic effects of gingival retraction cords on human gingival fibroblasts in vitro

In vitro effects of vasoconstrictive retraction agents on primary human gingival fibroblasts

The biological activity of chemical retraction/displacement agents in surrounding periodontal tissues is of unquestionable importance, but the activity of these agents has not been completely elucidated. In the present study, we aimed to evaluate the in vitro effects of vasoconstrictive retraction agents on primary human gingival fibroblasts (HGFs). A total of six commercial adrenergic solutions (0.05 and 0.01% HCl-epinephrine, two based on 0.05% HCl-tetrahydrozoline, 0.05% HCl-oxymetazoline, and 10% HCl-phenylephrine) and three experimental gel formulations (EG-1, EG-2, and EG-3) were used to treat primary HGFs. The biological effect of the retraction treatment on the expression of collagen types I and III was detected by performing immunocytochemical analysis. The generation of reactive oxygen species triggered by the retraction agents were evaluated by using the dichlorofluorescein (DCF) fluorescent probe. The effect of retraction agents on the expression of fibronectin was visualized by confocal laser scanning microscopy. According to the results, experimental retraction gels did not limit the expression of collagen types I and III. EG-3 even induced the synthesis of both types of collagen. The DCF assay indicated oxidative stress similar to the control cells for most of the selected retraction agents. Experimental gels did not cause degradation of the cellular shape and morphology of the primary HGFs. The proposed experimental retraction gels in the present study demonstrated higher biocompatibility with primary HGFs, suggesting their use as clinical vasoconstrictive agents for the application of gingival retraction with minimal damage to periodontal tissues.

Evaluation of cytotoxicity levels of poly vinyl ether silicone, polyether, and poly vinyl siloxane impression materials: An in vitro study

Aim:

To assess the cytotoxicity level of newly introduced poly vinyl ether silicone (PVES) compared to poly vinyl siloxane (PVS) and polyether (PE) elastomeric impression materials.

Settings and Design:

Comparative -Invitro study design.

Materials and Methods:

Mouse cell line NIH/3T3 was grown in Dulbecco's modified Eagle's medium. Samples of three elastomers were dissolved in dimethyl sulfoxide and were tested at various concentrations. Twenty-four well plates with NIH/3T3 cells with different concentrations of elastomeric solutions were incubated at 37°C. 3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide assay was performed on day 1, 3, and 7, with a time interval of 15 min, 30 min, 60 min, and 24^th h to estimate the cytotoxicity for all three elastomers.

Statistical Analysis Used:

Kruskal–Wallis ANOVA test and the period effect within the subjects, repeated-measure ANOVA was done using the Greenhouse–Geisser correction method.

Results:

The mean cell viability (survival rate) of NIH 3T3 cells at the concentrations tested was measured. A repeated-measure Kruskal–Wallis ANOVA determined the mean survival concentration on day 1, 3, and 7. PVES showed significant decrease in the survival rate on day 1 than PVS and PE, while PVS and PE had significant decrease in the survival rates of cells on day 3 and 7 which were statistically significant (P < 0.001).

Conclusion:

PVES shows early cytotoxic signs as compared to PVS and PE, and cell viability for PVS was the highest among all. When making impression with PVES and PE, it is always better to evaluate the impression and gingival sulcus carefully with magnification to prevent adverse reaction, if any material is left inadvertently for longer period of time.

The Direct Cytotoxic Effects of Different Hemostatic Agents on Human Gingival Fibroblasts

PURPOSE

To evaluate the cytotoxic effects of different hemostatic agents (including Expasyl) on human gingival fibroblasts (HGFs) in vitro.

MATERIALS AND METHODS

HGFs were cultured and exposed to either no medicament treatment or 1:200 dilution of six different hemostatic agents (Hemox-A, Hemodent, Astringedent, Vicostat, Expasyl, 3M ESPE) for 2, 5, 10 minutes, 1 hour, and 24 hours. Toxicity to HGFs was determined by lactate dehydrogenase activity (LDH) and colorimetric (WST-1) assays. Two-tailed t-test was used for statistical analyses with α level set at 0.05.

RESULTS

The group-by-time interactions were significant for the LDH and WST-1 assays (p < 0.001). Evaluation of the cytotoxic effect of different hemostatic agents at different incubation time intervals on the cell membrane damage revealed that Astringedent showed the highest cytotoxic effect on HGFs compared to other agents with regards to untreated negative control cells at all incubation time intervals (p < 0.001). On the other hand, Expasyl showed the least cytotoxic effect with significant differences at 5 minutes and 1 hour (p < 0.001) in comparison to other agents.

CONCLUSIONS

LDH and WST-1 assays of hemostatic agents showed significant cytotoxic effect on HGFs at different time intervals. The data suggest that the risk for permanent tissue damage might be less significant when Expasyl is used during final impression procedure compared to when Astringedent is used.

The influence of retraction agents on cytoskeleton reorganization and oxidative stress in primary human gingival fibroblasts (HGFs)

OBJECTIVE

Contemporary gingival retraction chemicals are not without disagreeable side-effects; there appears to be no best gingival retraction agent. The aim of this research was to select the most biocompatible retraction agents based on examination of the parameters of oxidative stress in fibroblasts derived from human primary cell culture.

DESIGN

In this in vitro study we evaluated parameters of oxidative stress after treatment with retraction agents. Visine, Afrin, Neosynephrin, Strazolin and Adrenaline were the commercial products studied as gingival retraction agents. Additionally we examined three experimental agents. We determined lipid peroxidation and protein damage and monitored changes in cellular cytoskeleton proteins. Proliferative and survival efficiency were also evaluated.

RESULTS

Oxidative changes included by evaluated retraction agents were at the lowest level in the case of the experimental gels. Also cytoskeleton observations suggest that the experimental agents did not degrade the cellular structure of human gingival fibroblasts (HGFs).

CONCLUSIONS

The current study was performed because of a need to project new nontoxic and save retraction agents for peridontological therapeutic usage. We suggest that the new investigational gels are most biocompatible with periodontal tissues and can be applied as new vasoconstrictor chemical retraction agents.

Gingival displacement for impression making in fixed prosthodontics: contemporary principles, materials, and techniques

The clinical success and longevity of indirect restorations depend on the careful and accurate completion of several procedures. One of the challenging procedures is management of the gingival tissues and gingival esthetics. The goal for management of gingival tissues and gingival esthetics is to maintain the normal appearance of healthy gingival. Achieving this goal requires optimal health before treatment and minimal trauma during treatment. The best way of optimizing health and minimizing trauma is to avoid contacting the gingiva with restorative materials.

Effect of Burow's solution on the guinea pig inner ear

OBJECTIVES

We examined the changes in the inner ear hair cells following intratympanic injection of Burow's solution.

METHODS

Thirty-one albino guinea pigs with a normal Preyer's reflex were used. Burow's solution was applied and allowed to remain on the round window membrane for 30 minutes (30-minute group), 1 hour (1-hour group), or 2 hours (2-hour group). Seven days later, the left temporal bone was removed. Auditory brain stem responses were recorded at 4, 8, and 20 kHz before application of Burow's solution and again immediately before decapitation. The cochlea and utricle were dissected, stained with rhodamine-phalloidin, and examined under a fluorescence microscope.

RESULTS

The postoperative auditory brain stem response thresholds at 20 kHz in the 1-hour group and those at 8 and 20 kHz in the 2-hour group were increased significantly compared to the baseline thresholds. Surface preparations of the organ of Corti revealed no hair cell loss in the 30-minute group, loss of outer hair cells in the lower half of the basal turn in half of the animals in the 1-hour group, and loss of outer hair cells in the basal turn in almost all animals in the 2-hour group. In the 2-hour group, the microthin sections of the round window membrane showed degeneration of the outer epithelium.

CONCLUSIONS

The retention of Burow's solution on the round window membrane for 2 hours induces degeneration of the outer epithelium and damage to the cochlear outer hair cells.

Cytotoxic Evaluation of Elastomeric Dental Impression Materials on a Permanent Mouse Cell Line and on a Primary Human Gingival Fibroblast Culture

The need for clinically relevant in vitro tests of dental materials is widely recognized. Nearly all dental impression materials are introduced into the mouth just after mixing and allowed to set in contact with the oral tissues. Under these conditions, the materials may be toxic to cells or may sensitize the tissues. The aim of the present study is to evaluate the potential cytotoxicity of new preparations of elastomeric dental impression materials: A) four vinylpolysiloxanes: Elite H-D Putty and Elite H-D Light Body (Zhermack, Badia Polesine, Rovigo, Italy); Express Putty and Express Light Body (3M ESPE AG Seefeld, Germany) and B) two polyethers: Impregum Penta and Permadyne Penta L (3M ESPE AG Seefeld, Germany). The cytotoxicity of these impression materials were examined using two different cell lines: Balb/c 3T3 (permanent cell line) and human gingival fibroblasts (primary cell line) and their effects were studied by indirect and direct tests. The direct tests are performed by placing one sample of the impression materials in the centre of the Petri dishes at the time of the seeding of cells. The cell growth was evaluated at the 12th and 24th hours by cell number. The indirect tests were performed by incubating a square of 1 cm diameter impression material in 5 mL of medium at 37 °C for 24 hours (“eluates”). Subconfluent cultures are incubated with “eluates” for 24 hours. The MTT-formazan production is the method used for measuring the cell viability. The results indicate that: a) polyether materials are cytotoxic under both experimental conditions; b) among vinylpolysiloxanes, only Express Light Body (3M ESPE AG Seefeld, Germany) induces clear inhibition of cellular viability of Balb/c 3T3 evaluated by direct and indirect tests and c) the primary cell line is less sensitive to the toxic effect than the permanent cell line.

Iatrogenic trauma to oral tissues

BACKGROUND

Iatrogenic trauma can be defined as any trauma that has been induced by the dentist's activity, manner, or therapy. The aim of this article is to present traumatic oral tissue lesions of iatrogenic origin.

METHODS

Thirteen cases of chemical (due to ferric sulfate and formocresol), physical (due to orthodontic wires and appliances), and thermal (due to electrosurgery) injuries to the oral tissues are reported.

RESULTS

Chemical, physical, and thermal injuries in the oral, gingival, or palatinal mucosa of iatrogenic origin can exhibit various clinical features. The management of traumatic injuries is dependent on the severity of the involvement in the periodontal tissues. While, in most cases, the elimination of the offending agent and symptomatic therapy were sufficient, in severe cases, or when the injury resulted in permanent defects, periodontal surgery and regenerative therapy may be necessary.

CONCLUSIONS

The skill, experience, and up-to-date knowledge of dentists are the main factors to prevent possible iatrogenic traumas. Although "To err is human," careful practice is very important for the principle "Primum non nocere" ("First do no harm").