Tissue displacement methods in fixed prosthodontics

Comparative evaluation of the effect of impregnated retraction cord versus laser on gingival attachment level and pain perception following retraction for subgingival margins - A prospective, split-mouth, controlled, clinical study

AIM

To evaluate and compare the effect of impregnated retraction cord vs Laser on gingival attachment level and pain perception following retraction for subgingival margins.

SETTINGS AND DESIGN

Many methods for achieving and measuring the amount of gingival retraction in fixed prosthodontic work have been advocated. Though the gingival attachment level is crucial in Periodontology, the literature available regarding the effect of these retraction methods on the same is scarce. Hence, this clinical study was designed to compare the pain perception and amount of gingival recession when impregnated cord and laser were used for retraction.

MATERIALS AND METHODS

In 40 subjects (age range of 20 to 40 years) with single missing maxillary incisor, the abutments were prepared with subgingival margins, to receive a full coverage metal-ceramic fixed dental prosthesis. The gingiva was retracted on one of the abutments with impregnated retraction cord and on the other with diode laser. Gingival attachment levels were compared at six sites per abutment using superimposition of digital scans, preoperative and four weeks after cementation of final prosthesis.

STATISTICAL ANALYSIS USED

Statistical analysis of the data for gingival recession was done using t-test. Pain perception was analysed with Chi-square test. Pain perception by patients following retraction was compared with VAS scale.

RESULTS

The average values of gingival recession on buccal side were 0.61 mm and 0.38 mm and on the palatal side were 0.58 mm and 0.35 mm for impregnated retraction cord and laser respectively. The P values of <0.01 indicated a highly significant difference between the two groups. Intragroup comparison did not show significant differences between various sites. Pain and discomfort produced by cord method was moderate in comparison with mild/no pain with diode laser and the difference was highly significant.Conclusion: Retraction cord produced more gingival recession than the diode laser, which was statistically highly significant on both buccal and palatal aspects of the teeth. Patients experience with diode laser technique was less painful in comparison with retraction cord method.

Contemporary concepts on periodontal complications from prosthetic and restorative therapies

The clinical outcome of every prosthetic and restorative procedure depends on the maintenance of a healthy periodontium. It is, therefore, important that the prosthodontist and restorative dentist cause no harm or permanent damage to the underlying hard and soft tissues when performing clinical procedures necessary to carry out the planned treatment. Several factors involved in these procedures have been described to have an impact on gingival health. For the present article, a selection of four of these factors are presented with the goal of evaluating the current trends and their influence on periodontal structures: (1) tooth preparation configuration and apical extension, (2) gingival tissue sulcular expansion/retraction, (3) prosthetic contours, and (4) prosthesis marginal adaptation and the consequences of excess cement remnants. Based on the available scientific evidence and clinical experience, recommendations for the practitioner are given.

A Novel Nontraumatic Gingival Retraction Method for a Single-Unit Crown Impression

Until now, there have been three traditional options for gingival retraction procedures, mechanical, chemicomechanical, and surgical methods, which have a degree of trauma that varies according to the clinical experience. The gingival tissue may be very delicate and susceptible to recession if too much trauma was applied. This article describes a novel nontraumatic gingival retraction method, without cords, chemicals, surgery, or any special equipment.

Gingival Displacement in the Vertical and Horizontal Dimension under the Condition of Mild Gingivitis-A Randomized Clinical Study

This randomized clinical study aimed at quantifying the gingival displacement performance in the vertical and horizontal directions of the 3M™ Astringent Retraction Paste (3M Oral Care, Seefeld, Germany) in comparison with the double-cord technique with aluminum chloride as an astringent. Afterward, any soft-tissue changes were assessed for 12 months. After inducing mild gingivitis, 18 probands received the intervention ‘cord’ and 22 probands received the intervention ‘paste’ at the palatal half of upper premolars prior to conventional impression making. The resulting plaster casts were digitized and analyzed for the vertical and horizontal gingival displacement, applying a newly developed computer-assisted methodology. The entire palatal half of the tooth was evaluated instead of only single sites. Under the condition of mild gingivitis, the gingival displacement performance was comparable for both techniques in the horizontal direction (width) and only somewhat better for the cord technique in the vertical direction (depth). The magnitude of displacement was in a similar range in both directions, with somewhat higher values in the vertical direction. The marginal gingiva height changes were of such low extent during the follow-up period of 12 months with only minimally higher values for the paste that they cannot be considered as clinically relevant recessions.

Influence of the Gingival Condition on the Performance of Different Gingival Displacement Methods-A Randomized Clinical Study

This randomized clinical study examined the influence of the gingival condition—healthy versus mild inflammation—on sulcus representation and possible gingival recession for two gingival displacement procedures prior to conventional impression making. The interventions double cord technique or a kaolin paste containing aluminum chloride were applied to 40 probands. The opposite quadrant served as intrapersonal reference (split-mouth design). Precision impressions were then made. Extraoral digitization of the plaster models resulting from the reference impression prior to gingival displacement, the intervention impression and control impressions were the basis for the computer-aided three-dimensional analysis. After six months, a mild artificial gingivitis was induced, and the contralateral quadrant (cross-over design) was examined for the intervention. The gingivitis deteriorated the sulcus representation for the double cord technique group but did not affect the paste technique group. The gingival condition had no influence on the marginal gingiva height changes. The minor extent of those changes, which were measured up to six months after intervention at the palatal study site, were not considered to be in the clinically relevant range for gingival recession. For healthy gingiva, the cord technique showed superior sulcus representation compared to the paste technique. This advantage was lost to a great extent under the conditions of mild gingivitis.

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.

Update on Perio-Prosthodontics

Knowledge of the periodontal-restorative interface is critical in the fabrication of restorations that are functional and esthetic. Understanding biological principles allows the clinician to predict how the periodontium will respond to restorative therapy. Factors that influence the response to therapy in the periodontal-restorative interface are periodontal biotype, gingival architecture, alveolar crest position, gingival margin position, and gingival zenith.

Comparison of four cordless gingival displacement systems: A clinical study

STATEMENT OF PROBLEM

Although the conventional chemicomechanical cord technique is widely used, packing the cord into the sulcus may cause pain and bleeding. Cordless displacement techniques have been introduced, but a comparison of these systems is lacking.

PURPOSE

The purpose of this clinical study was to evaluate the efficiency and gingival response of 4 cordless gingival displacement systems.

MATERIAL AND METHODS

One hundred twenty teeth in 30 participants were allocated to 4 groups according to the material used: Tr (Traxodent; Premier Dental Products Co), Es (Expasyl; Acteon UK), Ez (Expazen; Acteon UK), and Mr (3M Retraction; 3M ESPE). Baseline measurements of periodontal indices and a digital scan were acquired. The cordless displacement pastes were applied according to the manufacturer's instructions. After removal, a second scan was acquired. Participants were recalled on the 2nd and 14th day to measure periodontal indices and for scans. Screenshots were superimposed to measure changes in the gingiva. Statistical differences among the different materials in achieving lingual and buccal vertical gingival displacement were tested using the related-samples Friedman 2-way ANOVA test by ranks at 3 time points such as immediate, at 2 days, and at 14 days (α=.05).

RESULTS

Immediate gingival displacement varied with the system used. For horizontal displacement, median values ranged between 150 μm (Tr) and 725 μm (Ez) for buccal displacement and between 93 μm (Tr) and 550 μm (Ez) for lingual displacement. Minimum and maximum displacements also varied and followed a similar trend, with Traxodent providing the lowest displacement. The plaque index and attachment level did not statistically differ before and after the treatment. The periodontal parameters were not statistically significant among the groups at all time intervals, except for the gingival index that increased for all the groups after 2 days.

CONCLUSIONS

Significant differences were found among the 4 tested systems in both vertical and horizontal gingival displacement. Expasyl, Expazen, and 3M Retraction exceeded the 200-μm requirements for horizontal displacement. Traxodent provided the least displacement in both vertical and horizontal dimensions.

Dental Impression Materials and Techniques

Dental impression making is the process of creating a negative form of the teeth and oral tissues, into which gypsum or other die materials can be processed to create working analogues. Contemporary dentistry generates new information every year and digital dentistry is becoming established and influential. Although dentists should stay abreast of new technologies, some of the conventional materials and time-tested techniques remain widely used. It is important to review the impression-making process to ensure that practitioners have up-to-date information about how to safely and effectively capture the exact form of the oral tissues to provide optimal patient management.

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.

The quality of fixed prosthodontic impressions: An assessment of crown and bridge impressions received at commercial laboratories

BACKGROUND

The authors evaluated and quantified clinically detectable errors commonly seen in impressions sent to commercial laboratories and determined possible relationships between finish line errors and other factors involved.

METHODS

The authors visited 3 large and 1 small commercial dental laboratories over a 12-month period. Three calibrated examiners evaluated the impressions. The examiners evaluated all impressions for errors by using ×2.5 magnification loupes under ambient room lighting without the aid of additional illumination.

RESULTS

The authors evaluated 1,157 impressions; 86% of the examined impressions had at least 1 detectable error, and 55% of the noted errors were critical errors pertaining to the finish line. The largest single error categories evaluated were tissue over the finish line (49.09%), lack of unprepared stops in dual-arch impressions (25.63%), pressure of the tray on the soft tissue (25.06%), and void at the finish line (24.38%). The factors blood on the impression (odds ratio, 2.31; P < .001) and tray type (odds ratio, 1.68; P < .001) were associated significantly with finish line errors.

CONCLUSIONS

Marginal discrepancies made up the largest category of error noted in impressions evaluated. The authors noted an increase in errors at the finish line with dual-arch impression techniques and in the presence of blood.

PRACTICAL IMPLICATIONS

Dentists have ethical, moral, and legal obligations bestowed on them by the profession and need to evaluate critically the work they send to laboratories. The authors strongly recommend an improvement in technique and reviewing of all impressions and working casts.

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.

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.

Preimpression troughing with the diode laser: A preliminary study

STATEMENT OF PROBLEM

The mechanical-chemical technique and the use of a laser are methods for displacing the gingiva to make an accurate impression of the preparation for a complete crown. The tissue needs to be displaced and the hemorrhage controlled to capture the prepared finishing line in the impression. The degree of undesirable gingival recession after these displacement techniques is unknown.

PURPOSE

The purpose of this pilot clinical study was to clinically monitor and compare the regeneration of the gingival tissue by using 2 methods of gingival displacement in the same participant: the mechanical-chemical technique with double cords impregnated with aluminum chloride and the 810 nm diode laser (Odyssey; Ivoclar Vivadent AG).

MATERIAL AND METHODS

A total of 6 participants needing 2 crowns on natural teeth were included in this study. At the first visit, the teeth were prepared with a 0.5-mm subgingival finishing line and interim crowns were fabricated. One of the teeth was randomly assigned to the double cord technique with 2 (# 000 and # 1) impregnated 5% aluminum chloride cords and the other to the 810 nm diode laser. An adjacent tooth served as a control. A device was made that would function as a fixed reference point for the measurements at different time intervals. A notch was created on the device to position the digital ruler between the occlusal notch and the free gingival margin to measure the distances. The measurements were recorded for each patient before displacement of the gingiva and at the time of cementation of the definitive crowns. The patients were followed at 1 week, 3 weeks, and 8 weeks after cementation of the definitive crowns.

RESULTS

The amount of recession with the cord impregnated with aluminum chloride was 0.26 mm 8 weeks after cementation of the definitive crowns with a range between 0.00 mm and 0.72 mm. The diode laser showed an average recession of 0.27 mm with a range between 0.01 mm and 0.68 mm.

CONCLUSIONS

This study found an average loss of gingival height of 0.26 mm for the double cord technique and 0.27 mm for the laser. The amount of recession was considered not clinically significant.

Effect of gingival displacement cord and cordless systems on the closure, displacement, and inflammation of the gingival crevice

STATEMENT OF PROBLEM

The gingival sulcus should remain open long enough for the impression material to flow into it and completely fill the space provided by the gingival displacement. Impressions with less sulcal width have a higher incidence of voids, tearing of impression materials, and reduction in marginal accuracy.

PURPOSE

The purpose of this clinical study was to investigate the closure, gingival displacement, and gingival inflammation of the gingival crevice after the use of medicated gingival displacement cord and cordless systems.

MATERIAL AND METHODS

Gingival sulcus closure was studied in 40 participants. They were divided into 4 groups: 2 cord (Ultrapack, SilTrax AS) and 2 cordless (Expasyl, Traxodent Hemodent paste) methods. The labial surfaces of the maxillary right and left central incisors were evaluated. Gingival sulcus was photographed every 20 seconds from 0 to 180 seconds after the removal of the cord or cordless system. The bleeding index (BI) and gingival index (GI) were measured at day 0, day 1, and day 7. The width of the sulcal orifice was measured at the mid-buccal (MB) and transitional line angle (TLA) on a digital image, using computer software (Photoshop version 7.0; Adobe). Data were analyzed with ANOVA, Tukey honest significant difference (HSD), Kruskal-Wallis, and Mann-Whitney U tests (α=.05).

RESULTS

All groups showed a sulcal width greater than 0.22 mm up to 60 seconds after the removal of the displacement materials at the MB and up to 40 seconds at the TLA. Among all groups, Expasyl showed the fastest closure. Gingival displacement in the MB area for the cord group was greater than for the cordless groups. GI and BI indices were larger for the cord group than for the cordless group at days 0 and 1.

CONCLUSIONS

At up to 60 seconds, the cord and cordless techniques were equally effective. The cord group showed a greater amount of displacement than the cordless group. However, the cordless materials showed reduced frequency of changes to the gingival index.

A. Iatrogenic Damage to the Periodontium Caused by Fixed Prosthodontic Treatment Procedures

Missing teeth should be replaced as soon as possible to maintain arch integrity and thereby avoid both morphologic and functional derangements in the occlusion. Otherwise, changes occur that upset the masticatory system, such as extrusion of the teeth opposing the edentulous areas along with their alveolar housing, their supporting tissues and ultimately the maxillary sinus. Concurrently with extrusion, shifting of the interproximal contacts and migration of the adjacent teeth occur, thereby impairing function and causing disharmony. Good oral health cannot be achieved when changes in tooth position alter the coronal contour and occlusion interfering with mutual support, which encourages food impaction and retention, further leading to osseous defects.

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).

Efficacy of an Anesthetic Gel in the Reduction of Pain During Impression Making

Introduction

Gingival tissue displacement can be an uncomfortable procedure, often performed without injectable local anesthesia. The present study evaluated the efficacy of an anesthetic gel in reducing pain during this procedure.

Material and Methods

Thirty patients undergoing definitive dental impression, for fabricating full-coverage restorations, were evaluated for pain perception on displacement of the surrounding gingival tissues. All the participants were randomly divided into two groups. Five minutes before the insertion of the displacement cord, the anesthetic gel, a mixture of 5% lidocaine and 5% prilocaine, was applied in the sulcus of test group patients. Each patient was asked to complete the Visual Analogue Scale (VAS) and the Verbal Rating Scale (VRS).

Results

In the two scales considered, test group patients showed a statistically significant pain reduction (VAS p=0.0002, VRS p=0.01054) compared to control group patients.

Conclusions

Within the limitations of this study, a clinically significant efficacy of the anesthetic gel was noticed during gingival displacement procedures.

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.

Comparative Study on the Efficacy of Gingival Retraction using Polyvinyl Acetate Strips and Conventional Retraction Cord - An in Vivo Study

STATEMENT OF PROBLEM

A new material is proposed in dentistry in the form of strips for producing gingival retraction. The clinical efficacy of the material remains untested.

PURPOSE OF THE STUDY

This study aimed to determine whether the polyvinyl acetate strips are able to effectively displace the gingival tissues in comparison with the conventional retraction cord.

MATERIAL AND METHODS

Complete metal ceramic preparation with supra-gingival margin was performed in fourteen maxillary incisors and gingival retraction was done using Merocel strips and conventional retraction cords alternatively in 2 weeks time interval. The amount of displacement was compared using a digital vernier caliper of 0.01mm accuracy. RESULTS were analyzed statistically using Paired students t-test.

RESULTS

The statistical analysis of the data revealed that both the conventional retraction cord and the Merocel strip produce significant retraction. Among both the materials, Merocel proved to be significantly more effective.

CONCLUSION

Merocel strip produces more gingival displacement than the conventional retraction cord.

Efficacy of two gingival retraction systems on lateral gingival displacement: A prospective clinical study

PURPOSE

Gingival management is a substantive procedure in fixed dental prosthesis treatment. Various new retraction cord systems are available and used. This study aimed to compare the efficacy of a new retraction cord (Stay-Put, Coltene Whaledent AG) and a conventional retraction cord (Ultrapak, Ultradent Products Inc., South Jordan, Utah) on lateral gingival displacement in continuation with the treatment protocol of the subjects fixed dental prosthesis for various partial edentulous conditions requiring fixed dental prosthesis.

METHOD

Thirty subjects were selected who needed bilateral fixed dental restoration. In selected subjects both gingival retraction cords were placed bilaterally buccolingually by simple randomization method. After removing the cords, impressions were made and undamaged definitive casts were retrieved. The abutment teeth were sectioned buccolingually at the buccal ridge followed by decimal measurement of the width (in millimeter) of the retracted gingival sulcus, under a traveling microscope.

RESULTS

Data was analyzed using SPSS version. Paired "t" test was used to compare the difference between the displaced gingival width in two retraction group (p > 0.05).

CONCLUSION

Although mean gingival retraction in Stay-Put system (0.528 ± 0.12 mm) was higher as compared to that in Ultrapak (0.487 ± 0.10 mm), the difference between the two systems (0.041 ± 0.11) was not significant statistically (p = 0.057).

Evaluation of efficacy of different gingival displacement materials on gingival sulcus width

AIM

The purpose of the present in vivo study was to measure the efficacy of different gingival displacement materials in achieving gingival tissue displacement and to compare the efficacy of Expasyl displacement paste (Pierre Rolland, France) and gingival displacement cord for gingival displacement.

MATERIALS AND METHODS

Sixteen subjects were included in the study. Premolars were prepared to receive full veneer crown, gingival displacement was carried using gingival retraction cord and gingival displacement paste. Impression of the gingival sulcus was made. Sulcus width after displacement was measured under magnification.

RESULTS

The mean displacement value of sulcus width was 0.21 ± 0.01 mm for the gingival retraction cord and 0.26 ± 0.02 mm for the gingival displacement paste. 'F' test was used for statistical analysis. Difference among the two test agents was statistically significant (p < 0.01).

CONCLUSION

Gingival displacement paste showed better response in achieving horizontal displacement of the gingival sulcus than gingival retraction cord.

CLINICAL SIGNIFICANCE

Gingival displacement helps in recording the unprepared tooth surface adjacent to the finish line in the impression being made, thereby helping a better marginal adaptation and emergence profile in the extracoronal restoration.

A clinical study on the effects of cordless and conventional retraction techniques on the gingival and periodontal health

AIM

To investigate the influence of two cordless techniques on the periodontium in comparison with conventional cords.

MATERIAL AND METHODS

Dental students (n=60) with healthy gingival conditions were recruited - an expanding poly vinyl siloxane material (Magic Foam Cord), a paste-like material (Expasyl), and a conventional retraction cord (Ultrapak) were applied on the buccal aspects of three premolars of each subject. Probing depth, clinical attachment level, gingival index (GI), plaque index, mobility, bleeding, and sensitivity were assessed at baseline, and at 1 and 7 days after application. Data were analysed using Kruskal-Wallis and Mann-Whittney tests (alpha=0.05).

RESULTS

The periodontal parameters were not statistically significant among the groups at all time intervals except for the GI, which was increased for all groups after 1 day. The highest was in Expasyl (p=0.011). After 7 days, the GI returned to a non-significant level compared with baseline except for Expasyl, which was still significant (p=0.044). Expasyl induced sensitivity in four subjects. Bleeding was only induced by Ultrapak in 28.3% and 26.7% during and after retraction, respectively.

CONCLUSIONS

All techniques caused a temporary gingival inflammation; the greatest was in Expasyl, which also showed slower recovery. Cordless techniques did not induce bleeding during or after retraction.

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.

Effect of different retraction and impression techniques on the marginal fit of crowns

OBJECTIVES

Periodontal conditions in restored teeth are strongly influenced by the marginal fit of the restoration which is closely related to the quality of the impression. However, the influence of the retraction and impression technique on the outcome of the impression has only sparsely been investigated. Thus, it was the objective of this study to compare the marginal fit in fixed restorations using two modes of gingival retraction and two different impression techniques in an animal model.

METHODS

To simulate clinical conditions, 6 teeth in each of 10 lower jaws of freshly slaughtered cows were prepared with subgingival finish lines. Two different retraction techniques were used to expose the finish line: retraction cords containing epinephrine (Surgident) and electro-surgery were applied contra-laterally at 3 teeth per quadrant. Two impressions per jaw were taken in a two-step putty-wash technique (TPW) and a one-step putty-wash technique (OPW), respectively. On the casts, measurement copings were fabricated and seated on the extracted original tooth. In each coping the marginal discrepancy was assessed at 8 reference marks. Since the data was normally distributed, results were subjected to parametric statistics (T-test; p=0.05).

RESULTS

Overall marginal discrepancies ranged between 0 and 200 microm. There was a small but not significant difference between electro-surgery and the retraction cords whereas TPW produced significantly better results than OPW (p<0.05).

CONCLUSIONS

Within the limits of the study it can be concluded that the use of gingival retraction cords as well as electro-surgery lead to acceptable results. The difference between TPW and OPW concerning the marginal discrepancies can be regarded as clinically insignificant.

The effect of gingival retraction procedures on periodontal indices and crevicular fluid cytokine levels: a pilot study

PURPOSE

The purpose of this study was to examine the effects of placement of retraction cord subgingivally upon periodontal indices including plaque index (PI), gingival index (GI), pocket depth (PD), bleeding on probing (BOP), and attachment level (AL), as well as gingival crevicular fluid (GCF) and TNF-alpha levels.

METHODS

Ten teeth in 6 patients who were periodontally healthy were selected. These teeth had pocket depths of 3 mm or less, no evidence of significant loss of attachment, BOP, or plaque accumulation. The patients each received an oral prophylaxis. The following week, baseline measurements of periodontal indices and TNF-alpha were taken and the retraction cord was placed for 15 minutes. Following removal, the patients were dismissed. The periodontal indices measured included PI, GI, PD, BOP, and AL. In addition, the levels of TNF-alpha in GCF, were investigated. These measurements were made before gingival retraction as a baseline and on the 1st, 3rd, 7th, 14th, and 28th days post retraction.

RESULTS

A repeated measures ANOVA showed that TNF-alpha levels in GCF were significantly increased at all five intervals after gingival retraction compared to the baseline. The mean TNF-alpha level peaked at Day 1 (0.90 +/- 0.62), then declined at Days 3 (0.53 +/- 0.16), 7 (0.43 +/- 0.08), 14 (0.47 +/- 0.10), and 28 (0.43 +/- 0.08) but was still elevated 54% above baseline at Day 28, p < 0.01. The GI was significantly elevated at Day 1 (0.9 +/- 0.49), p < 0.01; Day 3 (0.53 +/- 0.32); and Day 7 (0.33 +/- 0.33), p < 0.05. Unlike TNF-alpha, GI recovered to the baseline by day 14. Other periodontal parameters, PI, PD, BOP, and AL were not significantly altered by the gingival retraction procedure.

CONCLUSION

This pilot study supports the previous research that gingival retraction causes an acute injury that heals clinically in 2 weeks as is indicated by the GI. It also provides the first evidence that gingival retraction results in an elevation of the proinflammatory cytokine, TNF-alpha, in GCF.

SEM–EDX study of prepared human dentine surfaces exposed to gingival retraction fluids

OBJECTIVES

To evaluate the effects of gingival retraction fluids (GRF) on prepared dentine surfaces, and to test the null-hypothesis that prior exposure of dentine surfaces for prolonged period to any of the fluids evaluated does not influence acid-etching of the exposed surfaces.

METHODS

The investigation was carried out using SEM and energy-dispersive X-ray analysis (EDX). The GRF studied were Hemodent (HMDT), Astringedent (AST) and Ultradent buffered 25% Aluminium Chloride (ULTB). Longitudinal sections of 220-grit ground dentine surfaces were exposed to GRF for 0.5-, 1-, 2- and 5-min (n=4 each). Another group of samples was produced by 20s application of 35% phosphoric acid (PA) on GRF-pretreated dentine. Control samples were not exposed to GRF. Differences in etching effect-a function of the Ca-contents detected by EDX, were analysed using Friedman's and Wilcoxon's rank test (P<0.05).

RESULTS

The SEM demonstrated the presence of a relatively non-porous amorphous dentine matrix, but many of the dentine tubule orifices remained occluded. Granular precipitates, which remained even after acid-etching, were noted on surfaces exposed to Hemodent for 5 min. Characteristic crystal growth was observed on surfaces exposed to Astringedent for 1- or 2-min prior to acid-etching. The EDX data demonstrated that there were differences in resulting Ca-content; ULTB >AST>HMDT>ULTB+PA>HMDT+PA>AST+PA>PA, but AST and HMDT were not significantly different.

CONCLUSIONS

The exposure of dentine prepared surfaces to these three GRF altered its morphology and reduced the dentine's susceptibility to acid-etching, thus the null-hypothesis is rejected.

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

The objective of this study was to determine the cytocompatibility of three different extracts of gingival retraction cords and to compare the cytotoxic effect of these materials on human gingival fibroblasts. Gingival retraction cords impregnated with aluminium sulphate (Gingi-Aid), dl-adrenaline HCl (Gingi-Pak) and non-drug-impregnated cord (Gingi-Plain) were eluted with culture medium for 10 min and 24 h. Cytotoxicity was judged using a tetrazolium bromide reduction assay. Our data demonstrated that gingival retraction cords applied alone almost completely inhibited cell viability (P < 0.05). In addition, the results also showed that the eluates from aluminium sulphate-impregnated cord, dl-adrenaline HCl-impregnated cord and non-drug-impregnated cord were cytotoxic to primary human gingival fibroblast cultures (P < 0.05). The cell viability of incubation of gingival fibroblasts containing 10-min eluates of aluminium sulphate, dl-adrenaline HCl and non-drug-impregnated cord was 61, 21 and 70%, respectively. The cell viability of incubation of gingival fibroblasts containing 24 h eluates of aluminium sulphate, dl-adrenaline HCl and non-drug-impregnated cord was 68, 58 and 72%, respectively. It was found that dl-adrenaline HCl-impregnated gingival retraction cord was the most toxic gingival retraction cord among the materials tested in all cultures (P < 0.05). The cytotoxicity decreased in an order of dl-adrenaline HCl-impregnated cord > aluminium sulphate-impregnated cord > non-drug-impregnated cord. The extent or degree of the cytotoxicity depended on the materials tested. Gingival retraction cords have significant potential for gingival toxicity. Careful management of gingiva retraction cords would lower the risk of potential gingival tissue damage during clinical application procedure and thus increase the success of prosthodontic procedures.

In vitro kinetic study of absorbency of retraction cords

STATEMENT OF PROBLEM

The soaking time required for liquid uptake by retraction cords is a crucial factor in the successful gingival retraction procedure.

PURPOSE

The aim of this investigation was to determine the optimal soaking time for 3 retraction cords of different thickness to ensure adequate uptake of the hemostatic solution.

MATERIAL AND METHODS

Braided ULTRAPAC retraction cords of 3 different thicknesses (No. 00, No. 0, and No. 1) with identical lengths (35 mm) were used. The capability of the cords to absorb liquids was measured by a gravimetric method. Different sulcus retraction solutions (epinephrine, aluminum chloride, and ferric sulfate) were tested, with physiological saline solution used as the control. The cords were soaked for various time intervals (2 seconds; 1, 5, and 60 minutes; and 24 hours) in the medicament solutions at room temperature. Immediately before immersion, air inclusions that may have inhibited the inner moistening of the cords were manually pressed out. In each of the 4 treatment groups, 75 pieces of cord were tested by determining the grams of fluid absorbed by grams of dry cord (gram/gram). Before the cord was weighed, excess fluid accumulating on the outer surface of the cord was removed by filter paper saturated in the corresponding test solution. The data were analyzed by F test analysis, and P<.05 was regarded as significant.

RESULTS

In each group, regardless of the cord type (No. 00, No. 0, or No. 1) or medicament solutions tested, the amount of fluid absorbed increased with the soaking time, but to different extents. A logarithmic relationship in a linear plot between the amount of fluid absorbed and the soaking time was demonstrated. The relationship established offered an exact determination of both the rate and the saturation level of liquid uptake. The rate of liquid uptake calculated from the saturation equations exhibited significant correlation with the cord thickness (P<.05). The saturation levels of the solutions did not show correlation with the cord thickness (P>.30).

CONCLUSION

Within the limitations of this study, the results indicated that 20 minutes of soaking time was necessary for saturation of the cords before use, provided that air trapped within the cords was removed. In addition to the soaking time, the saturation of the cords with the solutions largely depended on the wetting of the cords.

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.

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.

Tissue management with a new gingival retraction material: a preliminary clinical report

A new retraction material (Merocel) was evaluated in a clinical trial with 10 selected abutments. Each selected abutment required an anterior single unit. A comparison of probing attachment level, bleeding on probing, and plaque index demonstrated highly successful periodontal maintenance. The main advantage of Merocel retraction material is that it is capable of innocuously expanding the gingival sulcus. This preliminary study suggested that a Merocel strip was a predictable retraction material in conjunction with impression procedures. The material was also evaluated by scanning electron microscopy and demonstrated promise in this investigation. The Merocel strip shows potential for other applications, but limitations of this material indicated that evolution of atraumatic gingival retraction should continue.

Disturbance of the dentinal smear layer by acidic hemostatic agents

The pH of nine commonly used hemostatic agents was measured. Three measurements were recorded for each solution, and values ranged from 0.7 to 2.0. The effect of exposure to one hemostatic material, ferric sulfate solution (Fe2(SO4)3), on the dentinal smear layer was investigated. Prepared extracted teeth were exposed for periods ranging from 30 seconds to 5 minutes to an acidic ferric sulfate-based hemostatic agent. A smear layer was clearly demonstrated on a control specimen; however, the dentinal smear layer was rapidly removed by exposure to the hemostatic agent, and peritubular dentin was lost after prolonged exposure.

Evaluation of new gingival retraction agents

Current gingival retraction agents are not without undesirable side-effects; there appears to be no ideal gingival retraction agent. Several sympathomimetic amines, capable of producing local vasoconstriction with minimal systemic side-effects, are available as non-prescription nasal decongestants and eye washes. The purpose of this study was to evaluate the efficacy of three of these agents for gingival tissue displacement. Mongrel dogs were used as experimental subjects, in which pulse rate and blood pressure were monitored electronically. Visine (tetrahydrozoline HCl, 0.05%), Afrin (oxymetazoline, 0.05%), and Neosynephrine (phenylephrine HCl, 0.25%) were the commercial products studied as gingival retraction agents. Plain, untreated cord was used as a mechanical control, and as a vehicle for the three experimental agents. Commercially available cords impregnated with both racemic epinephrine (8%) and alum were also used as standard retraction agents with which the test solutions were compared. Visine and Afrin produced tissue displacement greater than that of any of the other agents; Neosynephrine, epinephrine, and alum were more effective than the untreated mechanical control. Cardiovascular changes included a slight increase in systolic pressure in the Neosynephrine group, and a slightly lower mean arterial pressure and pulse rate in all three experimental groups.

Fluid absorbency of retraction cords after soaking in aluminum chloride solution

Soaking retraction cord in an aluminum chloride solution before placing into gingival sulci does not lessen the cord's ability to absorb fluid. Black silk suture is clinically ineffective and should be replaced with a dark, size 0 impregnated retraction cord.