Clinical effectiveness of mechanical-chemical tissue displacement 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 The gingiva was retracted on one of the abutments with impregnated retraction cord and on the other with diode laser.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.

Gingival displacement before impression making: A prospective, comparative randomized clinical trial

STATEMENT OF PROBLEM

Gingival displacement is used in prosthodontics to obtain an accurate impression. However, randomized clinical trials to analyze the performance of different gingival displacement products are lacking.

PURPOSE

The purpose of this prospective, comparative randomized clinical trial was to evaluate the clinical effectiveness of 3 gingival displacement techniques: Racegel cordless, Racegel with a cord, and Racestyptine with a cord.

MATERIAL AND METHODS

A prospective, multicenter randomized, open label, 3-arm parallel group study was carried out in private dental practices. Patients with prepared teeth with healthy gingiva were recruited to make impressions before and after gingival displacement, which were digitized. Lateral and vertical gingival displacements were measured with computer-aided 3-dimensional analysis performed by a single operator who was blinded to the technique and the patient. For mean lateral gingival displacement, each gingival displacement method was compared with a required clinical value of 200 µm with the Student t test. The comparison of means among the 3 groups was performed using an ANOVA. Periodontal indices were recorded immediately and 7 to 14 days after gingival displacement. The percentages were compared with the chi-squared test or the Fisher exact test (α=.05 for all tests).

RESULTS

Eighty-eight participants were enrolled. The mean lateral gingival displacement obtained by Racestyptine with a cord (253 ±59 µm, P<.001) and by Racegel with a cord (247 ±61 µm, P<.001) were significantly higher than 200 µm. Lateral displacement observed with Racegel cordless was 207 ±57 µm (P=.53). For vertical gingival displacement, no difference among the 3 techniques was found. The astringent effect of these products was confirmed by the absence of crevicular fluid or bleeding. No periodontal damage was observed immediately or 7-14 days after displacement.

CONCLUSIONS

The study showed that cord impregnated with Racestyptine and Racegel with or without a cord provided a sufficient sulcus opening before impression making in prosthodontics, consistent with the clinical requirements for lateral displacement.

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

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

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

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

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

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

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

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.

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.

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.

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.

Efficiency of Cordless Versus Cord Techniques of Gingival Retraction: A Systematic Review

PURPOSE

Primarily to assess the efficacy of cordless versus cord techniques in achieving hemostasis control and gingival displacement and their influence on gingival/periodontal health. In addition, subjective factors reported by the patient (pain, sensitivity, unpleasant taste, discomfort) and operator's experience to both techniques were analyzed.

MATERIALS AND METHODS

An electronic database search was conducted using five main databases ranging from publication year 1998 to December 2014 to identify any in vivo studies comparing cord and cordless gingival retraction techniques.

RESULTS

Seven potential studies were analyzed. Out of the four articles that reported achievement of hemostasis control, three compared patients treated by an epi-gingival finish line and concluded that paste techniques were more efficient in controlling bleeding. Five studies reported on the amount of sulcus dilatation, with contrasting evidence. Only one study reported an increased gingival displacement when paste systems were used. Two studies did not observe any significant difference, although two showed greater gingival displacement associated with cords, particularly in cases where the finish line was placed at a subgingival level. Of the four studies that assessed the influence of both techniques on the gingival/periodontal health, three noted less traumatic injury to soft tissues when gingival paste was used. A paste system, in general, was documented to be more comfortable to patients and user-friendly to the operator.

CONCLUSIONS

Because of heterogeneity of measurement variables across studies, this study precluded a meta-analytic approach. Although both techniques (cord/cordless) are reliable in achieving gingival retraction, some situations were identified wherein each of the techniques proved to be more efficient.

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).

A clinical comparison of cordless and conventional displacement systems regarding clinical performance and impression quality

STATEMENT OF PROBLEM

It is not clear whether newly introduced cordless displacement systems are better able to manage gingiva than conventional systems.

PURPOSE

The purpose of this in vivo study was to evaluate the gingival management ability of 4 different displacement methods with a standardized subgingival preparation finish line.

MATERIAL AND METHODS

The effects of 4 displacement techniques on gingival management and impression quality were evaluated by means of 6 evaluation criteria. A subgingival preparation finish line of between 1 and 2 mm was ensured, and the buccal aspects of 252 (n=63) teeth were clinically assessed for ease of application, time spent, bleeding, remnants, and dilatation. The complete reproduction of the preparation finish line and the bubble and void formations on polyether impressions were also evaluated. The data were statistically analyzed with the χ(2) test (α=.05). The Bonferroni correction was used to control Type I error for the pairwise comparison groups (α=.008).

RESULTS

Statistically significant differences were found for all criteria among the groups (P<.05). The nonimpregnated displacement cord group was the least effective group in terms of bleeding and impression quality (P<.008). The aluminum chloride impregnated cord group and the displacement paste with cap group were found to be comparable in terms of remnants, dilatation, and impression quality (P>.008). The retraction cap with paste group showed better results for ease of application, time spent, and bleeding than the aluminum chloride impregnated cord group (P<.008). Although the group with aluminum chloride impregnated cord, displacement paste, and cap showed better results for dilatation, it was time consuming and difficult (P<.008).

CONCLUSIONS

Except for the nonimpregnated cord group, all of the groups were comparable and clinically useful, with perfect or acceptable impression qualities.

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.

Clinical success rates for polyether crown impressions when mixed dynamically and statically

The purpose of this study is to compare success rates of dual-viscosity impressions for two types of mixing techniques of the polyether elastomeric impression material. Additionally, influencing parameters on the success rates should be evaluated. The expectation was that there would be no difference between the success rates for the two mixing techniques. Two centres enrolled 290 subjects (727 teeth) into the trial. Patients were randomized for the two types of mixing techniques. One step, dual-viscosity impressions were made with either statically mixed Impregum Soft tray material (SAM) or dynamically mixed Impregum Penta H DuoSoft (DMM). Low viscosity Impregum Garant L DuoSoft was used for both groups. Gingival displacement involved the use of two braided cords. Full-arch trays were used exclusively. Both critical defects and operator errors were assessed for the first impression taken by trained dentists. The primary outcome was impression success. For comparison of the two mixing techniques, the odds ratio for success and the corresponding one-sided 95% confidence interval was calculated by a logistic regression model. To account for the dependence between several teeth within one patient, the method of general estimating equations was used. The overall impression success rate was 35.4%. Both mixing techniques showed equal success rates indicated by an OR of 1.0 and a lower limit of the one-sided 95% confidence interval of 0.71. Using this result to develop the corresponding interval for the difference, it could be shown that the success rate using SAM was at most 8.2% lower than that when using DMM with a probability of 95%. Multivariate logistic regression analysis of other potential influencing factors showed position of finish line (p = 0.008, supra compared to mixed), blood coagulation disorder (p = 0.021) and the level of training of the clinician (student vs dentist, p=0.008) to have an independent influence on the success rate. Dynamic mechanical mixing and the new static mixing of polyether tray material showed nearly equal success rates in the study even though success rates were comparatively low (DMM, 35.3%; SAM, 35.4%).

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.

Current concepts in gingival displacement

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

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.

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

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

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 new gingival retraction impression system for a one-stage root-form implant

Displacement of soft tissue adjacent to an implant abutment is arduous. Currently, gingival retraction cord is used before making an impression for cement-retained implant restoration. This article presents a new impression system for a cementable abutment/implant. The advantages of a cement-retained implant crown are described. This system provides efficient and accurate impressions.

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.

Root planing following short-term pocket distention

This study evaluated the effectiveness of root planing following short-term pocket distention. Seventy-five single-rooted teeth with probing depths > or = 5 mm and < or = 10 mm were selected. The teeth were randomly divided into three treatment groups. In groups 1 and 2 a gingival retraction cord (aluminum sulfate-impregnated in group 1 and non-impregnated cord in group 2) was packed subgingivally for 30 minutes. Following removal of the cord, the teeth were scaled and root planed. In group 3 the teeth were root planed only. Following instrumentation, the teeth were extracted and examined under a stereomicroscope. The residual calculus on the root surface of each tooth was measured using a computerized image analysis system. The quantities were compared using a two-way ANOVA and Chi-square test. The results showed that 46.3% of all root surfaces had detectable residual calculus and that the mean percentage of residual calculus per root surface was 4.41% following root planing. Forty percent of the root surfaces in group 1 had residual calculus, 38.0% in group 2, and 61.0% in group 3. There was a statistically significant difference (P < 0.01) between groups 1 and 2 compared to group 3. The mean calculus per root surface for groups 1, 2, and 3 was 3.03%, 3.04%, and 7.15%, respectively. Significant differences (P < 0.005) were found between groups 1 and 2 compared to group 3. These results indicate that subgingival calculus removal in deep pockets is enhanced with short-term pocket distention, and that there is no added benefit to having aluminum sulfate present in the retraction cord.

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.

Epinephrine absorption from commercial gingival retraction cords in clinical patients

Absorption of epinephrine from commercial gingival retraction cords was measured in vivo under clinical conditions. The amount of epinephrine absorbed was estimated by measurement with fluorospectrophotometry of the amount of dl-epinephrine remaining in the cords after they were removed and subtracting this value from the dl-epinephrine concentration in matching control cords. All cords lost substantial amounts of epinephrine while in the sulcus, with individual losses ranging from 64% to 94%. An average 71 micrograms of l-epinephrine was absorbed per inch of two-ply cord, and extreme variability in the dl-epinephrine concentration for individual segments of commercial cord was noted. In addition, the cords did not contain the concentration of epinephrine (500 micrograms/inch) listed on the package label but instead had a mean dl-epinephrine concentration of 225.5 micrograms/inch.

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.

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.