In vitro kinetic study of absorbency of retraction cords

A comparative evaluation of amount of gingival displacement produced by four different gingival displacement agents - An in vivo study

Aim

The aim of this study was to compare and evaluate the efficacy of ViscoStat clear, Vasozine, and Racegel (with and without cord) with respect to the amount of lateral gingival displacement produced by them.

Settings and Design

Comparative - In vivo study.

Material and Methods

Thirty consented volunteers were selected in the age group of 18-22 years. Maxillary right first premolar and lateral incisor and maxillary left central incisor and canine were selected for each individual. A composite resin standard reference point was made two millimeters below the gingival margin on the midsection of the labial surface of each tooth. By simple random sampling, the agents (ViscoStat clear, Vasozine, and Racegel with cord and Racegel without cord) were used for gingival displacement on each of the selected teeth. Pre- and postgingival displacement impressions were made with medium-body polyvinyl siloxane impression material. Three-millimeter thick buccolingual slice sections were obtained of the models and measured under a stereo microscope (×20 magnification), and the amount of displacement was calculated.

Statistical Analysis used

The Kruskal-Wallis test and the Mann-Whitney U-test were used for comparison between the amounts of gingival displacement produced by them.

Results

Mean displacement produced (in mm²) by Racegel with cord, tetrahydrozoline, ViscoStat clear, and Racegel is 0.2256, 0.2158, 0.2069, and 0.1414, respectively.

Conclusions

The largest mean gingival displacement was produced by Racegel with cord (0.2256 mm²) and lowest by Racegel without cord (0.1414 mm²). There was no significant statistical difference in the amount of gingival displacement produced between the four agents.

Evaluation of antioxidant and antimutagenic activities of aluminum chloride

Purpose:

Hemostatic agents are used to control hemorrhage and the gingival crevicular fluid for dental applications. In this study; the antimutagenic and antioxidant activities of aluminum chloride (AlCl3), a topical hemostatic agent used especially in the fields of dermatology and dentistry, were determined. To our knowledge, this is the first study that investigates these properties.

Materials and methods:

The antioxidant activity was determined by DPPH free radical scavenging and β-carotene-linoleic acid bleaching assays. The antimutagenic activity was evaluated with the Ames Salmonella/ microsome mutagenicity test using Salmonella typhimurium TA98 and TA100 strains.

Results:

The total antioxidant activity of AlCl3, determined by β-carotene bleaching assay was found to be 25.59 ± 2.55% and the DPPH scavenging activity of AlCl3 was determined as 17.49 ± 3.07%. AlCl3 showed not any mutagenicity at the tested concentrations by the AMES test used S. typhimurium TA98 and TA100. This drug demonstrated antimutagenic effects at the test concentrations and the strongest antimutagenic activity was observed on 1.25 mg·mL-1/plate concentration of AlCl3.

Conclusion:

AlCl3 showed potent antimutagenic and antioxidant activities and these properties are significant for dentistry and dermatology.

Comparative evaluation of three gingival displacement materials for efficacy in tissue management and dimensional accuracy

Aim:

Displacement of gingiva is essential for obtaining accurate impressions for the fabrication of fixed prostheses, particularly when the finish line is at or within the gingival sulcus. Various newer impression materials have been introduced to achieve gingival displacement while recording the impressions. A comparative evaluation of these new gingival displacement materials was deemed necessary for efficacy in tissue management and dimensional accuracy.

Materials and Methods:

Ten individuals were selected according to the inclusion and exclusion criteria for gingival displacement using retraction cord impregnated with aluminum chloride and two polyvinyl siloxane impression materials (Aquasil and NoCord VPS impression system) according to Latin block design. Intraoral scanner and Vernier caliper were used to study and compare the dimensional accuracy of each die obtained following which the dies were sectioned and evaluated under optical microscope with image analyzer to measure the amount of gingival retraction.

Results and Conclusion:

Statistical analysis showed that the amount of gingival retraction obtained by using retraction cord impregnated with aluminum chloride as gingival retraction agent was maximum as compared to NoCord followed by Aquasil. All three gingival displacement techniques could produce gingival displacement >0.2 mm which is the optimum amount of retraction required for impression making. All the three materials are found to be dimensionally accurate.

Evaluation of Fluid Absorbency of Retraction Cords after Immersing in Two Retraction Medicaments - An In-vitro Study

INTRODUCTION

Dry retraction cords help to displace the gingiva and also to absorb the gingival crevicular fluid and saliva to maintain a dry field. When used along with medicaments whether these medicaments help to improve the absorption of fluid or affect the fluid absorption by decreasing the efficiency of the retraction cord is unknown.

AIM

The aim of the study was to know the effect of various medicaments on the fluid absorbency of the retraction cords and also, to know whether the thickness of the retraction cords influences it's fluid absorbency.

MATERIALS AND METHODS

A total of 90 samples of 5cm length retraction cords were taken. Cords were divided into 30 samples for each cord thickness of 0, 1 and 2. Of these 30 samples, 10 samples were used to measure dry weight (Group I), 10 samples were immersed in 15.5% ferric sulfate (Group II) and remaining 10 samples were immersed in 10% aluminium chloride (Group III) for a period of 20 minutes. The excess medicament was removed by blotting paper. Initial weight was recorded. Following this, five cords from each group were immersed in plasma solution and remaining in artificial saliva for 10 minutes. Then these were taken out and measured. The amount of the fluid absorbed was determined by subtracting the weight before fluid immersion (weight after immersion in test medicament) from the weight after fluid immersion (weight after immersion in plasma or artificial saliva). The study was analyzed through one-way ANOVA and Bonferroni post-hoc comparisons for pair wise differences.

RESULTS

When immersed in medicaments, there is a significant difference in absorption of fluids (artificial saliva and plasma) between the untreated dry cord and cord treated with 15.5% ferric sulfate (p<0.05). But, there was no significant difference in fluid absorption between the dry untreated cord and cord treated with 10% aluminum chloride and between cords treated with 15.5% ferric sulfate and 10% aluminum chloride.

CONCLUSION

Ferric sulfate (15.5%) is a better medicament for absorption of fluid.

Comparison of the effect of different medicaments on surface reproduction of two commercially available Polyvinyl Siloxane impression materials - An Invitro Study

Objective:To determine the effect of different retraction cord medicaments on surface detail reproduction of polyvinyl siloxane impression materials and compare this effect on any two brands of commercially available polyvinyl siloxane impression materials. Material and methods: Four stainless steel dies were made according to ADA specification no.19. Three dies were treated with aluminium chloride (5%), ferric sulphate (13.3%) and epinephrine (0.1%) while the fourth one was left untreated to serve as control. Two impression materials (Dentsply and 3M ESPE) were used. Results: All the three medicaments adversely affected the surface detail reproduction of both the brands of the polyvinyl siloxane impression materials. These effects were statistically significant as compared to untreated control. The impressions of 3M ESPE brand have shown better surface detail reproduction as compared to Dentsply impression material. Conclusion: Surface detail reproduction of the polyvinyl siloxane impression materials is adversely affected by the retraction cord medicaments. The presence of moisture or any traces of the medicaments should be removed from the tooth surface to provide a dry field for the correct reproduction of the surface detail of these materials.

Key words:Polyvinyl Siloxane, retraction cord medicaments, surface detail reproduction.

The Effect of Tooth-preparation Cleansing Protocol on the Bond Strength of Self-adhesive Resin Cement to Dentin Contaminated with a Hemostatic Agent

After contamination with hemostatic agents, tooth-preparation cleansing protocols using either particle abrasion with low-pressure aluminum oxide particles or phosphoric acid-etching restored bond strengths to pre-contamination levels for a self-adhesive resin cement.

Gingival retraction techniques for implants versus teeth: current status

BACKGROUND

The authors reviewed and compared gingival retraction techniques used for implants and teeth.

TYPES OF STUDIES REVIEWED

The authors searched the literature using article databases Ovid MEDLINE up to May 2008, PubMED and Google Scholar (advanced search) and the following search terms: gingival retraction, implant abutment, impressions, cement-retained implant restoration, impression coping, peri-implant tissue, emergence profile and tissue conditioning.

RESULTS

The authors found insufficient evidence relating to gingival displacement techniques for impression making for implant dentistry. Gingival retraction techniques and materials are designed primarily for peridental applications; the authors considered their relevance to peri-implant applications and determined that further research and new product development are needed.

CLINICAL IMPLICATIONS

The use of injectable materials that form an expanding matrix to provide gingival retraction offers effective exposure of preparation finish lines and is suitable for conventional impression-making methods or computer-aided design/computer-aided manufacturing digital impressions in many situations. There are, however, limitations with any retraction technique, including injectable matrices, for situations in which clinicians place deep implants.

Dose-related effects of epinephrine on human gingival blood flow and crevicular fluid production used as a soaking solution for chemo-mechanical tissue retraction

STATEMENT OF PROBLEM

Epinephrine is a frequently used agent for impregnation of the retraction cord. Removal of retraction cord from the gingival sulcus has been shown to elicit a hyperemic response that could be prevented by epinephrine. However, the epinephrine may cause local or systemic adverse effects in the circulation.

PURPOSE

The aim of this study was to identify the effective concentration of epinephrine that may prevent the hyperemic response and consequently keep the crevicular fluid production low after cord removal without local or systemic side effects.

MATERIAL AND METHODS

Seventeen healthy human subjects had their crevicular fluid volume and gingival blood flow measured by Periotron and laser Doppler flowmetry, respectively, before and after cord removal at the left maxillary central incisor. The right maxillary incisor served as the control. Retraction cords were presoaked in physiological saline or various concentrations (0.001%, 0.01%, and 0.1% w/v) of epinephrine solution. Double repeated-measures analysis of variance with the Fisher Least Significant Difference post hoc test was used to statistically evaluate the blood flow values (mean +/- SE, alpha=.05), and the Wilcoxon matched pair test was used for crevicular fluid values, given as median (25-75 percentile, alpha=.01).

RESULTS

In the saline group, cord removal resulted in elevated blood flow (140% +/- 11%, P<.001) and crevicular fluid production (300% (130%-470%), P<.05). After cord removal in the 0.01% and 0.1% epinephrine groups, blood flow remained low for the measured period (43%-70%, P<.05). The crevicular fluid production transiently increased in the 0.01% epinephrine group (170% (140%-380%), P<.001), but then returned to baseline level and remained low as for the 0.1% group. No systemic vascular effect was detected in any groups.

CONCLUSION

The prolonged increase in crevicular fluid production and hyperemic response after cord removal can be prevented by application of 0.01% epinephrine solution without systematic changes.