Evaluation of new gingival retraction agents

A Comparative Analysis of Post-Retraction Changes in Gingival Height after Conventional and Surgical Gingival Displacement: Rotary Curettage, Diode and Er:YAG Laser Troughing

The aim of the current article is to analyze and compare post-retraction gingival height changes resulting from six different types of gingival-displacement methods, encompassing both conventional and surgical approaches. The study involved a comparative analysis of 263 teeth (consisting of 128 front teeth, 69 premolars, and 66 molars) from 23 patients. For the investigation, three classic retraction methods were utilized, namely the single-cord technique, retraction paste Expasyl, and retraction paste Astringent. Additionally, three surgical techniques were employed, which included ceramic bur rotary curettage, Er:YAG laser troughing, and diode laser troughing. A randomized split-mouth design was implemented, and a significance level of 0.05 was used for the study. The recovery of the free gingival margin height was assessed on gypsum models that were scanned using an intraoral scanner during the first and second week after the retraction procedure. The results revealed that all retraction methods, except for ceramic bur rotary curettage, led to clinically insignificant levels of gingival recession. The article provides insights into the effectiveness and safety of various gingival-displacement techniques, highlighting that most methods tested in the study resulted in minimal or negligible gingival recession post-retraction.

Comparative Evaluation of the Clinical Efficacy of Four Different Gingival Retraction Systems: An In Vivo Study

Introduction: There are numerous gingival retraction systems available on the market. This study aimed to evaluate the clinical efficacy of four gingival retraction systems, namely, impregnated retraction cord, gingival retraction capsule, retraction paste, and polyvinyl acetate strips.

Methods: A total of 20 people were chosen for the study, and 100 specimens were collected. The specimens were classified into five groups based on the materials used for gingival displacement. On the first day, a baseline impression without gingival displacement was made. Afterward, impressions were made with any of the following four gingival retraction systems: impregnated retraction cord (SURE-Cord® Plus; Sure Dent Corporation, Jungwon-gu, South Korea), retraction capsule (3M ESPE astringent retraction paste capsule; 3M Corporation, St. Paul, MN), retraction paste (Traxodent® Hemodent® Paste Retraction System; Premier Dental Co., Plymouth Meeting, PA) and polyvinylacetate strips (Merocel; Merocel Co., Mystic, CT), with a 14-day interval between each system. The amount of gingival displacement was measured using an optical microscope as the distance from the tooth to the gingiva crest in a horizontal plane.

Results: All experimental groups had higher gingival displacement than the control group (P < 0.01). Among the experimental groups, polyvinyl acetate strips had the highest gingival displacement value (541.65 μm), followed by impregnated retraction cord (505.37 μm), retraction capsule (333.57 μm), and retraction paste (230.63 μm).

Conclusion: Within the limits of this in vivo study, significant differences in horizontal gingival displacement were discovered among the four evaluated systems. The horizontal displacement requirements of 200 μm were exceeded by all four systems. The maximum value for gingival displacement was found in polyvinyl acetate strips (Merocel), followed by impregnated retraction cord (SURE-Cord), and retraction capsule (3M ESPE), and the lowest value was found in retraction paste (Traxodent).

Conceptual Model for Using Imidazoline Derivative Solutions in Pulpal Management

Alpha-adrenergic agonists, such as the Imidazoline derivatives (ImDs) of oxymetazoline and xylometazoline, are highly effective hemostatic agents. ImDs have not been widely used in dentistry but their use in medicine, specifically in ophthalmology and otolaryngology, warrants consideration for pulpal hemostasis. This review presents dental healthcare professionals with an overview of ImDs in medicine. ImD solutions have the potential to be more effective and biocompatible than existing topical hemostatic compounds in pulpal management. Through a comprehensive analysis of the pharmacology of ImDs and the microphysiology of hemostasis regulation in oral tissues, a conceptual model of pulpal management by ImD solutions is presented.

Evaluation of alpha-adrenomimetic agents for gingival retraction: A randomized crossover clinical trial

Context

The displacement of the gingiva around the tooth allows proper access during preparation, precise impression taking, and cementation procedures that has a direct bearing on the health of the periodontium. Several methods and agents are used for this purpose.

Aims

The primary aim of the study was to clinically evaluate the efficacy of naphazoline as a gingival retraction agent. The secondary aim was to compare it with tetrahydrozoline and aluminum chloride.

Settings and Design

Fifteen patients participated in a randomized crossover clinical trial at the Army College of Dental Sciences, Secunderabad, Telangana, India.

Subjects and Methods

Preliminary maxillary impressions were made with irreversible hydrocolloid for all patients to fabricate custom trays. After that, baseline impressions and cast for control group measurements were prepared. Gingival displacement was carried out in the right maxillary central incisor for all, with retraction cord soaked in three agents, either, aluminum chloride, tetrahydrozoline, or naphazoline. These agents were used in all patients with a washout period of 14 days. Elastomeric monophase impressions and die stone casts were recorded for each group. The central incisors were sectioned, and gingival retraction was measured using a measuring stereomicroscope.

Statistical Analysis Used

The gingival displacement was statistically analyzed using one-way ANOVA and post hoc Bonferroni.

Results

Naphazoline had the highest retraction (138.160 μm) followed by tetrahydrozoline (136.039 μm) and aluminum chloride (130.759 μm).

Conclusions

Naphazoline, tetrahydrozoline, and aluminum chloride show a clinically and statistically significant amount of displacement when compared to control. Among the three agents, naphazoline showed maximum displacement and maybe a good alternative with fewer side effects.

Comparative Evaluation of the Amount of Gingival Displacement Using Three Recent Gingival Retraction Systems - In vivo Study

Background:

Gingival retraction cord is the most commonly used gingival displacement material; however, it causes discomfort and produces damage to the periodontium. Various new gingival retraction materials have been introduced to overcome these problems. This in vivo study was conducted to compare the efficacy of three recent gingival displacement materials in achieving gingival tissue displacement.

Materials and Methods:

A total of 10 subjects was selected and 40 samples were made for the study. Samples were divided into four groups depending on the materials used for gingival displacement. The schedule for gingival displacement and impression making followed Latin block design. On day 1, baseline impression was made without gingival displacement. On day 2, day 22, and day 42 impressions were made after gingival displacement on intact maxillary right central incisor with any one of the three agents. The amount of gingival displacement was then measured as a distance from the tooth to the crest of the gingiva in a horizontal plane using stereomicroscope.

Results:

Statistical analysis was performed using one-way ANOVA test. The amount of gingival displacement obtained by all the experimental groups was more than the control group (P < 0.01). Among the experimental groups, astringent gingival retraction paste showed the highest value for gingival displacement (0.50 mm) followed by the stay-put retraction cord (0.48 mm), whereas expasyl (0.34 mm) showed the least value.

Conclusion:

Within the limitations of this in vivo study, astringent gingival retraction paste showed the highest value for gingival displacement followed by stay-put retraction cord whereas, expasyl showed the least value.

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.

Analysis of efficiency of photodynamic teeth bleaching with the use of photosensitizer chlorine e₆

Teeth whitening is one of the most sought-after procedures in aesthetic dentistry. Discolorites that are difficult to whiten, caused by dentin changes or enamel defects, can be eliminated by oxidizing the chromogens with chemical agents that penetrate to the enamel and dentin. In recent years, the method of photodynamic bleaching (PDB) is considered to be minimally invasive. It does not use hydrogen peroxide that leads to increased sensitivity of teeth, and is relatively effective over time. A convenient solution for PDB would be to use chlorin e6 as a photosensitizer, which has a high quantum yield of singlet oxygen generation, low phototoxicity, rapid elimination, on the one hand, and photobleaching capability, on the other. This paper presents quantitative data on the study of the effectiveness of PDB with chlorine e6: color change for 100 teeth after the procedure, chlorine e6 penetration into the tooth tissues, evaluation of the interstitial efficiency of the generation of singlet oxygen and photobleaching of chlorine e6 during laser exposure. It has been statistically established that for one PDB procedure, the tooth color saturation (C) varies on average by 0.5 tones on the VITA scale, and the lightness of color (L) in some cases increases by more than 10 units.

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.

Comparative evaluation of three noninvasive gingival displacement systems: An in vivo study

Aim:

An attempt is made to investigate clinical efficacy of cord, paste system, and a strip gingival retractile materials. This study aims to evaluate and compare the gingival retraction efficacy of retraction strip along with conventional retraction cord and paste system.

Material and Methods:

This in vivo experimental study was carried out on 30 patients. Three different gingival retraction systems were used to evaluate the amount of vertical and lateral displacement.

Based on selection criteria, 30 individuals requiring fixed dental prosthesis with respect to mandibular first molar were selected. Tooth preparation for metal ceramic restoration with subgingival finish line was performed. Gingival displacement was accomplished with ultrapak cord, merocel strip, and magic foam cord immediately, 7 and 14 days after the tooth preparation, respectively. The amount of gingival displacement in vertical and lateral directions was measured at mesiobuccal, midbuccal, and distobuccal regions of the prepared tooth. The vertical retraction was measured intraorally by using digital vernier caliper, and postgingival displacement impression was used to measure lateral gingival retraction. Stereomicroscopic images of impression under ×10 resolution were transferred to image analyzer to measure the lateral displacement. The obtained data analyzed in one-way ANOVA and Bonferroni test were used to determine the significant difference at P < 0.05 level.

Results:

ANOVA test showed the significant difference between the materials tested with respect to the mean vertical and lateral gingival retraction (P = 0.001). Multiple comparisons by Bonferroni test revealed a significant difference in vertical and lateral displacement among the materials tested.

Conclusions:

Merocel strip provided the maximum amount of vertical and lateral tissue displacement, followed by ultrapak cord and least with magic foam cord which was statistically significant.

Comparison between aluminum chloride and tetryzoline hydrochloride for control of vertical gingival displacement and crevicular fluid

Abstract Introduction The use of a gingival displacement cord with a gingival displacement substance is a common procedure for taking a quality impression of the cervical terminal in teeth for prosthetic purposes. Objective To evaluate whether the mechanical-chemical method with 0.05% tetryzoline hydrochloride or 25% aluminum chloride is capable of reducing crevicular fluid, and displacing a statistically significant larger quantity of gingival tissue vertically, compared with the mechanical method (without chemical substances). Material and method Ten patients were selected, and then No. 000 and 1 Ultrapak cords were randomly positioned on teeth 13, 21 and 23. Group I – cord with no chemical substance; Group II – cords impregnated with tetryzoline hydrochloride and Group III – cords impregnated with aluminum chloride. Using dental stone models, thirty images were captured with a camera coupled to a loupe to analyze the degree of gingival displacement. Crevicular fluid was quantified using a high-precision scale and individualized strips of absorbent paper for each tooth on which gingival displacement was performed. Result There was no statistical difference between the three groups relative to the amount of vertical gingival displacement (Anova, p=0.26). As regards reduction in crevicular fluid, there was no difference between the test and control groups (Wilcoxon and Friedman, p < 0.05). Conclusion The use of tetryzoline hydrochloride or aluminum chloride to impregnate the gingival displacement cord did not improve the quantity of vertical gingival displacement and did not reduce the amount of crevicular fluid.

Sealing of adhesive systems in ferric sulfate-contaminated dentinal margins in class V composite resin restorations

Background. Hemostatic agents are applied to prepare an isolated bleeding-free condition during dental treatments and can influence adhesive restorations. This study evaluated the effect of a hemostatic agent (ViscoStat) on microleakage of contaminated dentinal margin of class V composite resin restorations with three adhesives. Methods. Sixty freshly extracted human molars were selected and class V cavities (3×3×1.5 mm) were prepared on buccal and lingual surfaces. Gingival margins of the cavities were placed below the cementoenamel junction. The teeth were divided into six groups randomly. The adhesives were Excite, AdheSE and AdheSE One. In three groups, the gingival walls of the cavities were contaminated with ViscoStat and then rinsed. The cavities were restored with composite resin and light-cured. After storage in distilled water (37°C) for 24 hours and polishing, the samples were thermocycled and sealed with nail varnish. Then they were stored in 1% basic fuchsin for 24 hours, rinsed and mounted in self-cured acryl resin, followed by sectioning buccolingually. Dye penetration was observed under a stereomicroscope and scored. Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests. P<0.05 was set as the level of significance. Results. Only in the Excite group, contamination did not have adverse effects on dentin microleakage (P > 0.05). In the contaminated groups, Excite had significantly less microleakage than the others (P = 0.003). AdheSE and AdheSE One did not exhibit significant difference in microleakage (P > 0.05). Conclusion. ViscoStat hemostatic agent increased dentinal microleakage in AdheSE and AdheSE One adhesives with no effect on Excite.

Effect of various chemical agents used in gingival retraction systems on smear layer: Scanning electron microscope study

Background:

Chemical agents used for gingival retraction affects the smear layer.

Aim:

To determine the effect of three different chemical agents used for gingival retraction systems on smear layer.

Materials and Methods:

Four human premolars were prepared using air-rotor with air-water spray to receive full crown restoration. Three of them were treated with 21.3% aluminum chloride for 10 min, 0.05% oxymetazoline hydrochloride for 10 min, and expasyl for 2 min, respectively. One sample was left untreated. Then, the tooth specimens were rinsed with tap water to remove any residue of test materials. All the samples (treated and untreated) were processed by scanning electron microscope (SEM). Processed samples were examined under SEM at ×2400 to evaluate the effect of chemical agents on smear layer.

Results:

SEM examination revealed that 0.05% oxymetazoline hydrochloride for 10 min produced no alteration to smear layer followed by minimum alteration by expasyl for 2 min and complete removal of smear layer with etching of dentin with 21.3% aluminum chloride for 10 min.

Conclusion:

0.05% oxymetazoline hydrochloride and expasyl are kind to smear layer.

Comparative clinical efficacy evaluation of three gingival displacement systems

AIM

We compared the clinical efficacy of three gingival displacement systems to accurately record intra-crevicular margins of tooth preparation.

MATERIALS AND METHODS

One mechanical (magic foam cord) and two chemico-mechanical (expasyl paste and retraction cord impregnated with 15% aluminum chloride) gingival displacement systems were used. This study was conducted on the maxillary central incisors of 20 patients (20-60 years old) requiring full coverage restoration. All the three gingival displacement systems were tested in three sessions at an interval of 14 days in same order. The casts were sectioned and viewed under an optical microscope, followed by quantitative measurements of the width of the pre and postretracted sulci.

RESULTS

All the three displacement systems produced highly significant horizontal gingival displacement. Retraction cord soaked in 15% aluminum chloride produced maximum displacement (0.74 mm), followed by expasyl paste (0.48 mm) whereas magic foam cord produced the least displacement (0.41 mm).

CONCLUSIONS

Gingival displacement shown by each displacement system was found to be more than the accepted value necessary for elastomeric impression accuracy (0.2 mm) to record intra-crevicular margins of tooth preparation.

Comparative evaluation of the amount of gingival displacement produced by three different gingival retraction systems: An in vivo study

Statement of Problem:

Tetrahydrozoline has been introduced as new gingival retraction agent but its clinical efficacy with widely used conventional retraction agents has not been tested.

Purpose:

The study was designed to clinically evaluate efficacy of newer retraction agent tetrahydrozoline with two widely used retraction systems i.e., Expasyl retraction system and medicated retraction cords on basis of amount of gingival retraction.

Materials and Methods:

30 subjects were selected according to inclusion and exclusion criteria. Maxillary Impressions were made with irreversible hydrocolloid for all subjects. Tray material was used for making the special tray. Latin Block Design was Used in the Study to avoid tissue fatigue. Retraction was done with aluminium chloride; Tetrahydrozoline and Expasyl according to Latin block design. Impressions were poured with die stone. Casts were retrieved and sections were made with die cutter. 3 mm thin slices were obtained. Each slice was used to measure the amount of retraction under stereomicroscope under 20x and images were transferred to image analyser.

Results:

The amount of gingival retraction obtained by using aluminium chloride as gingival retraction agent was maximum (148238.33 μm²) compared to tetrahydrozoline (140737.87 μm²) and Expasyl (67784.90 μm²).

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.

Clinical evaluation of three new gingival retraction systems: a research report

The purpose of this study was to evaluate the clinical efficacy of 3 new gingival retraction systems; Stay-put, Magic foam cord and expasyl, on the basis of their relative ease of handling, time taken for placement, hemorrhage control and the amount of gingival retraction. Thirty subjects were selected requiring fixed prosthesis. The 3 gingival retraction systems were used on the prepared abutments randomly. The time taken for placement of each retraction system was recorded. The vertical gingival retraction was measured before and after retraction using flexible measuring strip with 0.5 mm grading. The horizontal retraction was measured on polyether impressions made before the retraction and after retraction. Based on the results, magic foam cord retraction system can be considered more effective gingival retraction system among the three retraction systems used in the study.

Internalized discoloration of dentin under porcelain crowns: a clinical report

This clinical report describes the situation of a patient who was concerned about the appearance of porcelain crowns that were placed on the maxillary incisors 4 years prior. The mechanicochemical gingival retraction technique combining the use of ferric sulfate and knitted retraction cord is described as a possible etiology of internalized discoloration of the dentin in this situation. The hypothesis is explained by the high acidity of gingival retraction fluids (GRFs) and the high affinity of iron for hard tooth tissues, resulting in an interaction with bacterial byproducts and precipitation of insoluble ferric sulfide in the porous demineralized dentin. A prospective clinical trial is warranted to track the effects of GRFs on tooth structure. This article describes the treatment of internalized discoloration of dentin under porcelain crowns.

Effect of conventional and experimental gingival retraction solutions on the tensile strength and inhibition of polymerization of four types of impression materials

In the present study, two types of tests (tensile strength test and polymerization inhibition test) were performed to evaluate the physical and chemical properties of four impression materials [a polysulfide (Permlastic), a polyether (Impregum), a condensation silicone (Xantopren) and a polyvinylsiloxane (Aquasil)] when polymerized in contact with of one conventional (Hemostop) and two experimental (Vislin and Afrin) gingival retraction solutions. For the tensile strength test, the impression materials were mixed and packed into a steel plate with perforations that had residues of the gingival retraction solutions. After polymerization, the specimens were tested in tensile strength in a universal testing machine. For the polymerization inhibition test, specimens were obtained after taking impressions from a matrix with perforations that contained 1 drop of the gingival retraction solutions. Two independent examiners decided on whether or not impression material remnants remained unpolymerized, indicating interference of the chemical solutions. Based on the analysis of the results of both tests, the following conclusions were reached: 1. The tensile strength of the polysulfide decreased after contact with Hemostop and Afrin. 2. None of the chemical solutions inhibited the polymerization of the polysulfide; 3. The polyether presented lower tensile strength after polymerization in contact with the three gingival retraction agents; 4. The polyether had its polymerization inhibited only by Hemostop; 5. None of the chemical solutions affected the tensile strength of the condensation silicone; 6. Only Hemostop inhibited the polymerization of the condensation silicone; 7. The polyvinylsiloxane specimens polymerized in contact with Hemostop had significantly lower tensile strength; 8. Neither of the chemical solutions (Afrin and Vislin) affected the tensile strength of the polyvinylsiloxane and the condensation silicone; 9. Results of the tensile strength and polymerization inhibition tests suggest that Vislin can be used as substance of gingival retraction without affecting the tested properties of four impression materials.

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.

Current concepts in gingival displacement

Gingival displacement is an important procedure with fabricating indirect restorations. Gingival displacement is relatively simple and effective when dealing with healthy gingival tissues and when margins are properly placed a short distance into the sulcus. Several techniques have proven to be relatively predictable, safe,and efficacious. No scientific evidence has established the superiority of one technique over the others, so the choice of technique depends on the presenting clinical situation and operator preference.

Crowns and other extra-coronal restorations: impression materials and technique

Well-fitting indirect restorations can only be made if there are accurate models of the oral tissues available, made from high quality impressions. Waiting for an impression to set may be more stressful for the dentist than the patient. Should the impression need to be repeated there is the embarrassment of having to explain this to the patient, the cost implications of material and time wasted and the aggravation of running late for the next appointment. Yet, if a 'Nelsonian' eye is turned to a defective impression we can only expect a substandard restoration in return.

Electron microscopic analysis of the effects of chemical retraction agents on cultured rat keratinocytes

STATEMENT OF PROBLEM

Chemical retraction agents used in fixed prosthodontics for temporary displacement of free gingival tissue before impression making can cause injury to the gingival tissue cells.

PURPOSE

This study evaluated changes in cultured rat keratinocytes treated with 2 chemical agents used for gingival retraction. Treated cultures were compared with untreated cultures.

MATERIAL AND METHODS

Keratinocytes of rat gingiva were grown in a specific medium for 10 days. After treating 1 group of specimens with 0.05% tetrahydrozoline and another group with 25% aluminum chloride, both for 10 minutes, the cultured cells were examined with scanning and transmission electron microscopy and compared with control specimens.

RESULTS

Twenty-five percent aluminum chloride produced a significantly greater extent of cellular damage than 0.05% tetrahydrozoline, which caused only mild changes in the cultured cells.

CONCLUSION

On the basis of the morphologic and ultrastructural changes in primary cell cultures of rat keratinocytes observed in this study, it was concluded that 25% aluminum chloride was significantly more aggressive than 0.05% tetrahydrozoline.

Clinical trial of gingival retraction cords

STATEMENT OF PROBLEM

A wide spectrum of different gingival retraction cords is used, while the relative clinical efficacy of these cords remains undocumented.

PURPOSE

This study aimed to determine whether clinicians were able to identify differences in clinical performance among 3 types of gingival retraction cords.

METHODS AND MATERIAL

Dental students and faculty members ranked pairs or series of cords according to 6 criteria for clinical performance, with a blind experimental study design. Cords differed in consistency (knitted or twined) and impregnation (8% dl-epinephrine HCl, 0.5 mg/in or 25% aluminum sulfate, 0.5 mg/in).

RESULTS

Knitted cords were ranked better than twined cords (P =.03). Cords containing epinephrine performed no better clinically than aluminum sulfate cords (P >.05).

CONCLUSION

Clinicians were unable to detect any clinical advantages of using epinephrine impregnated gingival retraction cords compared with aluminum sulfate cords.

Cardiovascular responses in patients and dentists during dental treatment

Changes in mean heart rate and in mean systolic and diastolic blood pressure are induced by both the patient's anticipation of scheduled treatment and the actual dental treatment. Most of these changes are within the normal physiological variations, but significant changes are observed before administration of a local anaesthetic, during subgingival debridement and during extractions. Individual changes in heart rate and blood pressure are affected by age, gender, hypertension and previous dental experience. Pain also plays an important role in the cardiovascular response during dental treatment, which stresses the need for adequate analgesia. For this purpose, local anaesthetics with low concentrations of epinephrine seem preferable. They induce less pronounced cardiovascular responses than local anaesthetics with higher concentrations of epinephrine or without epinephrine. The changes in heart rate and blood pressure that occur in the dentist during the treatment are also discussed.

Drugs and oral disorders

This chapter affirms that drugs and medicaments may have a profound effect on the periodontal structures. In some instances, such as drug-induced melanosis, the effect may be insignificant to the health of the patient. In other circumstances, drug-induced disorders may initiate painful, destructive disease processes that will not be successfully managed unless the causal role of drugs is recognized and altered. Finally, the clinician must remain aware of the contribution of drug-induced xerostomia and smoking to increased susceptibility to dental and periodontal diseases.

A scanning electron microscopic study of tooth surface changes induced by tannic acid

STATEMENT OF PROBLEM

Exposing the tooth structure to chemicals used in displacing the gingival tissue is inevitable.

PURPOSE

This study was undertaken to microscopically examine the effect of tannic acid on the prepared dentin surface.

MATERIAL AND METHODS

Forty recently extracted intact human teeth were mounted for buccal surface preparation. Teeth were equally divided into 10 groups. One group was kept as a control and the other teeth received a topical application of 15%, 20%, and 25% aqueous tannic acid solutions each for 5, 10, and 15 minutes at room temperature. All samples were washed, air-dried, then prepared for scanning electron microscopic examination. Two different areas in the cervical region were randomly selected and examined under magnifications of x1000 and x2000, then photographed. The assessment of the changes was performed qualitatively.

RESULTS

The results showed an incomplete removal of the smear layer in all experimental samples. The astringent action of the tannic acid solution on both the smear layer and the surface peritubular dentin around the orifices of dentinal tubules had contributed to their constriction. The degree of constriction of the orifices of dentinal tubules increased as higher concentrations of tannic acid solutions were used and as the application time was further increased at each concentration.

CONCLUSION

The tannic acid had an incomplete action on the removal of the smear layer. It also seemed to have an astringent action on both the smear layer and the peritubular dentin.

Smear layer instability caused by hemostatic agents

The effect of hemostatic agents, other than a 15.5% Fe2(SO4)3 solution, on prepared tooth structure is unknown. The purpose of this study was to (1) compare the effect of six commonly used hemostatic solutions and two nondental astringents on the dentinal smear layer and (2) determine whether different responses caused by product and/or time could be established. Standardized dentinal smear layers were exposed to eight astringent solutions for 30, 120, and 300 seconds (n = 6). A total of 144 SEM photographs at x2400 magnification were ranked according to predetermined criteria for five categories of smear layer removal and etching of underlying tooth structure. There were significant differences (p < 0.001) caused by the solution, exposure time, and their interaction. Greatest smear layer removal was observed with 21.3% AlCl3-6 hydrate, 8% racemic epinephrine HCl, and 15.5% Fe2(SO4)3 solutions at longer exposures. These caused significantly more removal than did almost pH neutral tetrahydrozoline or oxymetazoline (p < 0.05).

Cardiovascular responses induced by dental treatment

Changes in mean heart rate and mean systolic and diastolic blood pressure are induced in both the patient's anticipation of scheduled treatment and the actual dental treatment itself. Significant changes have been observed before application of a local anesthetic, during restorative treatment, during extractions, and when epinephrine-impregnated retraction cords were used. These cardiovascular responses may vary according to the local anesthetic used and the choice of vasoconstrictor. The individual changes in heart rate and blood pressure are affected by pain and such individual factors as age, gender, hypertension, dental experience, and psychological responses. Although for the most part the cardiovascular changes induced by dental treatment are limited and within the normal physiological variation, this review stresses the importance of eliminating pain and minimizing patient anxiety.