Comparative study of gingival retraction methods

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 The gingiva was retracted on one of the abutments with impregnated retraction cord and on the other with diode laser.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.

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.

Cord Placement Model: An Instructional Guide for Preclinical Dental Students to Practice the Skill of Retraction Cord Placement

INTRODUCTION

Gingival displacement is essential for ideal margin exposure and improved direct or indirect restorative outcome. Recent literature found many dentists prefer using retraction cord. Some contraindications of other displacement methods make retraction cord displacement preferred. It is necessary to teach dental students appropriate cord placement while minimizing gingival trauma.

METHODS

We developed a stone model using prepared typodont teeth and simulated gingiva that was made of polyvinylsiloxane material. Twenty-three faculty and 143 D2 students were briefed on the instructional guide. After faculty demonstration, D2 students practiced for 10-15 minutes under observation. The following year, former D2 (now D3) and D4 students were asked for feedback on the instructional experience.

RESULTS

Fifty-six percent of faculty rated the model and instructional guide good to excellent, and 65% rated the student experience as good to excellent, with only one participant rating it poor. Seventy-eight percent of D3 students strongly agreed or agreed the exercise increased their understanding of the technique in placing cord on a patient. Furthermore, 94% of D4 students strongly agreed or agreed having this exercise in preclinical D2 year would have been helpful.

DISCUSSION

Use of retraction cord to deflect gingiva is still preferred by most dentists. Completing the cord placement exercise on a model helps prepare students to perform the procedure on a patient before arriving at the clinic. Survey comments such as "useful exercise" support use of this instructional model. Overall, faculty and D3 and D4 students felt the exercise was beneficial to use in preclinical education.

Evaluation of gingival displacement methods in terms of periodontal health at crown restorations produced by digital scan: 1-year clinical follow-up

The purpose of this clinical study was to compare the effects of the gingival displacement techniques of retraction cord, cordless paste system, and Er,Cr:YSGG laser troughing on the periodontal tissues around the crown restoration produced using a digital scan. This was analyzed by recording the probing depth (PD), plaque index, gingival index (GI), mobility, sensitivity, and bleeding on probing (BOP) index. This study included 60 mandibular 1^st molars from 52 participants (20 males and 32 females) requiring crown restoration. The margin lines of the crown preparations were placed 1 mm subgingivally. Based on the gingival displacement technique used, the patients were divided into three groups: retraction cord, cordless paste system, and Er,Cr:YSGG laser troughing. A digital scan of the prepared tooth was performed. Follow-up appointments were scheduled at five different times: 1^st day, 1^st month, 3^rd month, 6^th month, and 1^st year. Six periodontal indices were used to assess the periodontal health. The chi-square test was used to compare categorical variables depending on the groups. There was a significant difference in the PD, GI, and BOP index scores among the three techniques during the 1-year clinical monitoring (p < 0.001). The PD in the three zones of the buccal surface showed a significant increase with time in the retraction cord and cordless paste system groups (p < 0.001). The highest GI scores were observed in the retraction cord group on the 1^st day. The Er,Cr:YSGG laser troughing procedure produced lower PD, GI, and BOP index scores as compared to the retraction cord and cordless paste system procedures in the 1-year period.

The Relationships Between Tooth-Supported Fixed Dental Prostheses and Restorations and the Periodontium

PURPOSE

To search the literature and to critically evaluate the findings on the periodontal outcomes of restorations and tooth-supported fixed prostheses.

MATERIALS AND METHODS

PubMed was searched according to a systematic methodology, previously reported, but updated to include a larger database. Filters applied were: Case reports, clinical trial, review, guideline, randomized controlled trial, meta-analysis, systematic reviews, and English. A narrative review was then synthesized to discuss periodontal outcomes related to restorations and tooth-supported fixed prostheses. Relevant data was organized into four sections: Direct restorations, indirect restorations, biologic width or supracrestal tissue attachment and tooth preparation/finish line design.

RESULTS

While increased gingival index, bleeding on probing, probing depth and clinical attachment loss have been associated with subgingival restorations, intracrevicular margins do not cause periodontal diseases. Inflammation and bone loss occur, for both direct and indirect restorations, only with large overhangs. Different restorative materials are associated with different clinical responses when placed in the gingival sulcus or within the epithelial and connective tissue attachments. When the connective tissue attachment is removed, histological changes occur causing its apical shift and subsequent re-establishment. Gingival displacement during impression procedures can cause gingival recession. Emergence profile can have a range of values, not associated with periodontal diseases. Periodontal response appears to be clinically not different when compared among different finish line designs.

CONCLUSIONS

Contemporary procedures and materials used for the placement and fabrication of tooth-supported restorations and fixed prostheses are compatible with periodontal health when adequate patient education and motivation in self-performed oral hygiene are present. Periodontal diagnostic criteria should be thoroughly reviewed before fixed restorative treatments are planned and executed.

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.

A randomized controlled clinical trial comparing the use of displacement cords and aluminum chloride paste

OBJECTIVES

This clinical study measured the change in opening and height of the displaced gingiva using paste and cord retraction materials for definitive impression making of natural teeth and assessed if they were comparable and clinically acceptable.

METHODS

Impressions of 4 maxilla premolars from 10 participants were taken using a split-mouth protocol. All participants were free of periodontal disease, had a thick biotype, a minimal of 3 mm height of keratinized gingival tissue and gingival sulci depths of 2 mm. The bleeding index (BI), gingival index (GI) plaque index (PI), sulcular depth, level of attachment and tooth sensitivity were recorded at baseline, just after retraction, at 24 hours and at 2 weeks. Impressions were poured in stone and then after initial analysis were cross-sectioned to allow measurements of the gingival height change and gap size to be recorded.

RESULTS

The paste produced a slightly smaller gap compared to the cord (0.041 mm less, P = .014) whilst the mean displacement for the cord was 0.282 mm and paste was 0.241 mm respectively. Gingival height with the paste was 0.047 mm lower than that achieved by the cord (P = .208).

CONCLUSIONS

Cord and paste retraction produced comparable clinically acceptable gingival gaps, with the cord producing statistically larger gap size.

CLINICAL SIGNIFICANCE

The cord and paste retraction materials produced comparable clinically acceptable gingival retraction.

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

Aim:

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

Materials and Methods:

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

Results and Conclusion:

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

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.

[Healing of the periimplant mucosal tissue injury after placing retraction cord subgingivally in beagle dogs]

OBJECTIVE

This work aims to observe the healing of periimplant mucosal tissue injury in beagle dogs after subgingival retraction cord placement by examining the gingival index (GI), quantity of gingival crevicular fluid (GCF), and the proinflammatory cytokine in the GCF.

METHODS

In eight beagle dogs, the fourth mandibular premolars on the left side were extracted (n=8); after two months of healing, bone-level implants were installed. A plaque control regimen was performed throughout the duration of the experiment. After three months, retraction cords were placed subgingivally for 5 min before the cement-retained implant-supported crowns were cemented. GI, GCF quantity, and levels of tumor necrosis factor-alpha (TNF-α) in GCF were assessed before application and on days 1, 3, 7, 14, 28, and 56 after application.

RESULTS

GI, quantity of GCF, and TNF-α were significantly increased on days 1, 3, and 7 compared with those at the baseline and on days 14, 28, and 56 (P<0.05), and no statistically significant differences were observed among those on days 14, 28, and 56 and the baseline (P>0.05).

CONCLUSIONS

Under the circumstances of good oral hygiene, acute injury caused by placing retraction cord subgingivally in periimplant mucosal tissue of bone-level implant is reversible. GI, the quantity of GCF, and TNF-α on day 14 return to the baseline levels.

A multicenter randomized, controlled clinical trial comparing the use of displacement cords, an aluminum chloride paste, and a combination of paste and cords for tissue displacement

STATEMENT OF PROBLEM

Gingival recession after soft tissue displacement for impression making in fixed prosthodontics may pose a problem for treatment success in the esthetic areas of the mouth. Knowledge about the soft tissue reaction of common gingival displacement methods is limited.

PURPOSE

The purpose of this clinical randomized controlled trial (RCT) was to evaluate changes in the marginal soft tissue height with 3 different gingival tissue displacement techniques for definitive impression making of natural teeth.

MATERIAL AND METHODS

A total of 67 individuals were randomized to 3 groups. In test group 1 (P; n=22), only aluminum chloride paste was used to displace the gingiva. In test group 2 (CP; n=23), a cord was inserted, and aluminum chloride paste was also used. In the control group (C; n=22), 2 cords were used to displace the gingiva (double-cord technique). Clinical measurements of the gingival position were made before treatment began and at 30 ±10 days after prosthesis delivery. Study casts were fabricated at different stages of the treatment, standardized photographs were made, and changes in the buccal gingival position were measured using graphics editing software. In addition, the participants' perception of the clinical procedure and the technicians' evaluation of the die preparation were recorded. One-way ANOVA models were applied to compare the response variables among the groups: (a) the position of the gingival margin (millimeters), (b) mean probing pocket depth (millimeters), (c) gingival thickness (millimeters), (d) amount of keratinized tissue (millimeters), and (e) mean changes in gingival margin height (millimeters). Unpaired t tests were also used to compare the mean values between groups. For comparisons between different categories, chi-square tests were performed (α=.05 for all tests).

RESULTS

In the period between impression and delivery, a minor gain in gingival height of 0.058 mm (±0.13 SD) for P and 0.013 mm (±1.19 SD) for CP. However, a minor gingival recession of 0.049 mm (±0.13 SD) was reported for group C. The results for all groups showed that 21% of abutment teeth gained >0.1 mm in gingival height, 58% had stable gingival height (0 ±0.10 mm), 21% showed minor gingival recession (0.1 to 0.5 mm), and no abutment teeth showed moderate or severe gingival recession (>0.5 mm). The incidence of minor gingival recession was 8% in group P, 23% in group CP, and 32% in group C (P=.015). Fifteen participants (24%) experienced some discomfort after the procedure. The differences between the groups were not significant (P>.05). The laboratory technicians found the definitive die preparation significantly more challenging for group P (visual analog scale [VAS], 79) and CP (VAS, 82) than group C (mean VAS, 93; P=.003).

CONCLUSIONS

Minor or moderate gingival recession (<1 mm) is more likely to occur when conventional cords are used during impression making. However, the laboratory technicians found the die preparation significantly less challenging when the double-cord technique was used than when impressions were made using the paste displacement technique.

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.

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 Impact of Expasyl® Gingival Retraction Paste on the Bond Strength of Self-etch and Total-etch Systems

OBJECTIVE

To evaluate the influence of Expasyl® gingival retraction paste on the shear bond strength of self-etch and total-etch adhesive systems.

MATERIALS AND METHODS

Twenty-four specimens of extracted, caries-free, sound human molars were used in this study. The molars were then cut vertically into halves through the buccal and lingual cusps. Forty-eight specimens were divided into four groups (total-etch, total-etch with Expasyl application, self-etch, self-etch with Expasyl application) and the shear bond strength was tested.

RESULTS

Expasyl significantly reduced the shear bond strength of the self-etch and total-etch adhesive systems. The self-etch system showed relatively lower performance compared with the total-etch adhesive system. The shear bond strength values of the total-etch adhesive without Expasyl showed the highest bond strength (21.48 ± 2.89), while the self-etching group adhesive treated with Expasyl showed the lowest shear bond strength value (14.89 ± 1.81).

CONCLUSION

From the observations of this in vitro study, it can be concluded that the use of Expasyl® gingival retraction system can negatively affect bond strength of adhesives. The total-etch system showed better compatibility to the Expasyl gingival retraction system than the self-etch.

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.

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.

Effect of retraction materials on gingival health: A histopathological study

Background:

Gingival retraction methods are used in dentistry for impressions of subgingival crown margins, such as, mechanical, chemical, chemicomechanical, and surgical. These methods may injure the gingival sulcular epithelium. Hence, the present study is carried out to evaluate the effect of different retraction materials, such as, Expasyl, Magic Foam Cord, and impregnated retraction cord on the gingival sulcular epithelium.

Materials and Methods:

This study included 30 cases of bilateral premolar extraction patients with Loe and Silness gingival index zero. Retraction materials were kept in the dry, isolated labial gingival sulcus for the required time. The retraction materials were removed by rinsing with water. Retracted gingiva of 2 – 3 mm from the gingival margin along with the tooth was extracted and the decalcified sections were microscopically studied. Data analysis: Data were analyzed by applying the chi-square test.

Results:

This study showed better results with retraction paste as compared to the retraction cord, and there was a significant association between retraction materials and the relative degree of injury to the sulcular epithelium.

Conclusion:

There is a significant association between retraction materials and gingival sulcular epithelium. It can be stated that impregnated retraction cord, may be used commonly but it needs proper tissue manipulation and is technique sensitive. Newly advanced material in the form of retraction paste like Expasyl or Magic Foam Cord was found to be better than cord as assessed histologically, it respects periodontium.

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.

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.

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.

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.

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.

Iatrogenic trauma to oral tissues

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Traumatic Lesions of the Gingiva: A Case Series

BACKGROUND

The most recent classification of periodontal diseases includes a new section on traumatic gingival lesions. Traumatic lesions of the gingiva are thought to be highly prevalent, yet the periodontal literature contains few references on the topic. The purpose of this article is to present a broad spectrum of traumatic gingival lesions of iatrogenic, accidental, and factitious origin.

METHODS

Twelve clinical cases were selected to document chemical (due to aspirin, snuff, and peroxide), physical (due to malocclusion, flossing, removable partial denture, oral piercing, and self-inflicted trauma), and thermal (due to overheated ultrasonic scaler, hot food, and ice) injury to the gingiva.

RESULTS

Chemical, physical, and thermal gingival injuries of iatrogenic, accidental, or factitious origin can have a variety of presentations with overlapping clinical features. Although the appearance and associated symptoms of a gingival lesion may be suggestive of a particular traumatic etiology, useful or confirmatory diagnostic information is often discovered through careful history-taking. The management of gingival injuries typically requires elimination of the insult and symptomatic therapy. If permanent gingival defects resulted from the injury, periodontal plastic surgery may be necessary.

CONCLUSIONS

A variety of chemical, physical, and thermal injuries may involve the gingiva. Accidental and iatrogenic injuries are often acute and self-limiting, while factitious injuries tend to be more chronic in nature.

Effect of different crown contours on periodontal health in dogs. Clinical results

OBJECTIVES

The aim of this study is to evaluate clinically the effect of different crown contours on the periodontium in beagle dogs.

METHODS

One month after commencing oral hygiene procedures the second and third premolars in three quadrants of four adult beagle dogs were prepared for receiving crowns. The unprepared second and third premolars in one quadrant served as controls. Crowns with three different emergence profiles (normal (=tooth) contour, 30 degrees and 50 degrees over-contour) were cemented where one quadrant received the same treatment. Clinical parameters were recorded on all four sites (mesial, buccal, distal and lingual) of test and control teeth at baseline, after 3 and 5 months. During the entire study period, professional oral hygiene was performed seven times a week.

RESULTS

The Plaque Index increased for the 30 degrees and 50 degrees over-contour groups, although no statistically significant differences could be observed. For the normal contour and control group minor changes occurred. Similar results could be depicted for the Gingival Index. The changes regarding the variables Plaque and Gingival Index were correlated to the Gingival Crevicular Fluid Flow. Here, significant differences for the Gingival Crevicular Flow were observed between the treatment groups and over the treatment period for the 30 and 50 degrees over-contour groups. Only slight differences for this parameter were observed in and between the control and normal contour groups. In the control group, the Pocket Probing depth remained stable during the entire study but increased in the crowned treatment groups over time. At 3 and 5 months the probing depth was significant greater in the 30 degrees and 50 degrees over-contour groups compared to the control group. There was a higher loss of clinical attachment levels for the test groups than for the control group. There were statistically significant differences at each timepoint between groups and also within groups except for the control group.

CONCLUSIONS

Within the limits of this study it can be concluded that over-contoured subgingival crowns seem to affect clinical periodontal health only slightly in dogs over 5 months when an intensive oral hygiene regimen is executed.

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.

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.

Current methods of finish-line exposure by practicing prosthodontists

PURPOSE

The purpose of this study was to survey members of The American College of Prosthodontists to evaluate current methods of finish-line exposure. In addition, frequency of use of epinephrine compounds and observed side effects were assessed.

MATERIALS AND METHODS

A questionnaire was mailed to the 2,436 members of The American College of Prosthodontists. Group differences were evaluated using chi 2 analysis.

RESULTS

Completed questionnaires were returned by 1,246 prosthodontists, which is a return rate of 51%. Ninety-eight percent of respondent prosthodontists use retraction cord, and 48% use a double-cord technique. Plain cord is the most commonly used cord (44%), followed by aluminum chloride-impregnated cord (18%), and epinephrine-impregnated cord (14%). Nine hundred one respondents (81%) soak the cord before placing it in the gingival sulcus. The most common medicament for soaking the cords is buffered aluminum chloride (55%). Side effects to epinephrine were reported by 387 respondents (33%), with the most common side effect reported being increased pulse rate, followed by anxiety. Approximately one quarter (24%) of the prosthodontists surveyed had observed side effects to chemical agents other than epinephrine.

CONCLUSIONS

Prosthodontists throughout the country use many different techniques and agents to expose finish lines. No statistically significant differences (p > .05) were found between year of specialty training completion groups with respect to retraction cord use. Copper bands are used significantly more frequently (p < .05) in the northwest region of the United States than elsewhere.

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.

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.

Electrosurgery--a biological approach

Electrosurgery has been used in dentistry for more than 50 years. Both opponents and advocates of electrosurgery have presented a variety of clinical studies in favour of their respective opinions, which are discussed in the following review. In some studies, wounds created by electrosurgical techniques were observed through the healing stages, in comparison to those following incision by a surgical blade, with no significant difference being discovered. Other studies reported that the histologic response of oral connective tissue to electrosurgery was adverse in some animal and human models. However, neither of these groups used methods that allowed documentation or control of operating variables. A critical evaluation of controlled clinical studies shows that adverse responses of (connective) tissue, epithelium, bone, cementum, and periodontal attachment are related to an excessive lateral heat production during the procedure. With electrosurgery, the clinician can control the inherent variables. Waveform, frequency, size of the electrode, time of contact and cooling periods are some of those considered to be of importance in the studies. On the basis of the research reports, clinical guidelines have been developed to give practical advice to the clinician using electrosurgery. Providing that these safeguards are adhered to, scientific evidence supports the biological compatibility of electrosurgery for intraoral surgical procedures.

Tissue displacement methods in fixed prosthodontics

The various methods to accomplish gingival displacement have been described. The techniques have been noted and their relative advantages and disadvantages summarized. The practicing dentist can use this review to make better informed decisions regarding the method he or she chooses for the treatment of a particular patient.

Tissue retraction for esthetic ceramometal crowns

The placement of subgingival margins in ceramometal restorations has been discussed. A method of visualizing the attachment and managing the gingival tissues during tooth preparation has been presented.