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

Absorptive Capacity of Gingival Retraction Cords in Hemostatic Solutions: An In Vitro Study

Background and Objectives: Gingival retraction is a critical pre-impression procedure in fixed prosthodontics, crucial for exposing tooth margins and ensuring accurate impressions for restorations like crowns and bridges. This study aimed to evaluate the absorptive capacity of different gingival retraction cords. Materials and Methods: Ninety samples each of Ultrapak (Ultradent, South Jordan, UT, USA) #00, braided cord, coreless thread, and monofilament thread (totaling 270 samples) were immersed in 0.9% NaCl, 10% aluminum chloride, and 12.7% ferrous sulfate solutions for 120, 300, and 1200 s. The liquid absorption capacity was measured using a gravimetric method, and the data were analyzed using an F-test, setting the significance threshold at p < 0.05. Results: The results revealed statistically significant differences in absorption, particularly for aluminum chloride and ferric sulfate (p < 0.001). Ultrapak demonstrated the highest absorption, followed by the coreless cotton thread, while the monofilament thread absorbed the least, especially at 1200 s. Conclusions: These findings indicate that Ultrapak's superior absorption could enhance moisture control during procedures, highlighting the importance of selecting an appropriate retraction cord for optimal clinical outcomes. Further research is needed to confirm these findings in a clinical setting.

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 modified scan technique for multiple abutment teeth using the trim and lock function

OBJECTIVES

To describe a new protocol for digital scanning of multiple abutment teeth using the trim and lock software tools.

METHODS

A reverse workflow technique was used. Scanning was performed with the interim restoration in position. The abutment teeth were then trimmed from the scan. The retraction cord or interim restoration from either the first mesial or distal abutment tooth was removed and only that tooth was scanned, allowing the dentist to easily manage gingival displacement and keep the tooth dry from crevicular fluid and saliva. Consequently, the preparation margin remained visible and uncontaminated during the scan. The adjacent abutment teeth detected in the scan were deleted from it, and the scan was then locked using a tool of the scanning software. Next, the retraction cord or interim restoration of the next abutment tooth was removed, and only that tooth was scanned. The procedure was repeated until all prepared teeth were individually scanned.

RESULTS

The technique presented here facilitated the scanning of multiple abutment teeth in a simple and predictable way by utilizing the trim and lock surface tools of the scanning software and helped in avoiding closure of the gingival crevice.

CONCLUSIONS

Splitting the scan for a complex case with multiple abutment teeth allows reliable 3D acquisition of the finish line of each abutment tooth. Therefore, this technique simplifies the full-arch intraoral scanning process and can improve treatment efficiency.

CLINICAL SIGNIFICANCE

The trim and lock tool allows scanning of each prepared abutment tooth separately, transforming a full-arch impression into multiple single scans. This technique helps to easily manage gingival displacement and maintain an uncontaminated and dry preparation margin during the scan.

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

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

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.

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

Background:

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

Materials and Methods:

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

Results:

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

Conclusion:

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

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.

Efficacy of conventional cord versus cordless techniques for gingival displacement: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Unsatisfactory adaptation of restorations with subgingival margins can cause problems such as accumulation of biofilm, secondary caries, and inflammation of the periodontal tissue. Therefore, special attention should be given to gingival displacement and impression procedures to optimize marginal fit.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare gingival displacement with conventional cords and cordless techniques and determine the reliability of the measurement methodologies.

MATERIAL AND METHODS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and identified studies through September 2018. The studies were submitted to the Cochrane risk-of-bias assessment. The gingival displacement was evaluated by using the Review Manager Software.

RESULTS

Nine studies were selected, and the most common risks of bias were random sequence generation, blinding of outcome assessment, and absence of sample size calculation. Most of the studies reported obtaining a width greater than 0.2 mm.

CONCLUSIONS

The cord technique resulted in increased displacement when compared with the cordless technique. The evaluation of sulcular width with digital microscope images obtained from sectioned gypsum casts is an adequate and versatile experimental methodology for measuring displacement.

Effect of contemporary retraction agents and cleaning with hydrogen peroxide on the polymerization of elastomeric impression materials

The aim of the study is to investigate the polymerization inhibition of elastomeric impression materials vinylpoly siloxane (VPS) and polyether (PE) when used in combination with retraction materials with and without subsequent cleaning with hydrogen peroxide (H₂O₂). Methods: Seven stainless steel specimens were fabricated. Four hundred and twenty impressions were made with three different elastomeric materials (140 each) as follows: group 1: VPS-Panasil; group 2: VPS-Express; group 3: PE-Monophase. Each material group was further subdivided into seven subgroups, based on use of no retraction material (control), three different retraction materials [Retraction capsule (RC3M), Dryz, Expasyl], and two cleaning techniques (water and H₂O₂). All subgroups included 20 impressions, which were made by a single operator using an automix gun. Evaluations were made using a visual scale by three calibrated examiners blindly and independently. Subjective categorization of the impressions were made as inhibited and uninhibited. Data were analyzed using Fisher's exact test and significance was set at p < 0.05. Results: Inhibited impressions were lower than uninhibited impressions among VPS materials (Panasil and Express); Panasil and Express showed comparable (p > 0.05) impression retardation. PE showed significantly higher inhibition compared to VPS materials (p < 0.05). Expasyl showed significantly higher polymerization inhibition than other retraction materials (p < 0.05). The use of H₂O₂ for cleaning showed significant reduction in polymerization inhibition than cleaning with water for Expasyl (p < 0.05). Conclusion: Overall contemporary retraction materials showed low potential for polymerization inhibition of elastomeric impression materials. Expasyl should be cleaned with H₂O₂ prior to impression making. However, Dryz and RC3M can show accurate impressions with water cleaning alone.

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

Aim

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

Settings and Design

Comparative - In vivo study.

Material and Methods

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

Statistical Analysis used

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

Results

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

Conclusions

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

Clinical acceptance of single-unit crowns and its association with impression and tissue displacement techniques: Findings from the National Dental Practice-Based Research Network

STATEMENT OF PROBLEM

The definitive impression for a single-unit crown involves many material and technique factors that may affect the success of the crown.

PURPOSE

The purpose of this prospective cohort study was to determine whether impression technique (tray selection), impression material, or tissue displacement technique are associated with the clinical acceptability of the crown (CAC).

MATERIAL AND METHODS

Dentists in the National Dental Practice-Based Research Network documented details of the preparation, impression, and delivery of 3730 consecutive single-unit crowns. Mixed-effects logistic regression analyses were performed to evaluate associations between impression techniques and materials and the CAC and to assess associations between the presence of a subgingival margin with the displacement technique and the outcome variables CAC and number of impressions required.

RESULTS

Of the 3730 crowns, 3589 (96.2%) were deemed clinically acceptable. A significant difference in the CAC was found with different impression techniques (P<.001) and different impression materials (P<.001). The percentage of the CAC for digital scans was 99.5%, 95.8% for dual-arch trays, 95.2% for quadrant trays, and 94.0% for complete-arch impression trays. Although no statistically significant difference was found in the CAC produced with dual-arch trays without both mesial and distal contacts, crowns fabricated under these conditions were less likely to achieve excellent occlusion. The percentage of the CAC for digital scans was 99.5%, 97.0% for polyether impressions, 95.5% for polyvinyl siloxane impressions, and 90.5% for other impression materials. Accounting for the location of the margin, the use of a dual-cord displacement technique was significantly associated with lower rates of requiring more than 1 impression (P=.015, odds ratio=1.43).

CONCLUSIONS

Dual-arch trays produced clinically acceptable crowns; however, if the prepared tooth was unbounded, the occlusal fit was more likely to have been compromised. Digital scans produced a slightly higher rate of CAC than conventional impression materials. The use of a dual-cord technique was associated with a decreased need to remake impressions when the margins were subgingival.

Interim restoration technique for gingival displacement with a feather-edge preparation design and digital scan

A straightforward and time-efficient technique is presented for recording digital scans in single- and multiple-unit tooth abutments with feather-edge finish lines. The margins of the interim restoration should be precise and sufficiently deep in the sulcus so that the tissues can be properly displaced. Definitive intraoral scans should be made approximately 3 to 4 weeks after the tooth (or teeth) has been prepared to allow healing of the soft tissues. The interim restoration is first removed and then reseated after removing cement residue. First, a scan is made with the interim restoration in place. The abutment tooth or teeth are then erased from the original digital file, the interim restoration is removed again, and a new scan enclosing only the abutment tooth is made.

Minimum intervention management of diastema closure using cordless displacement system and laminate veneers: A 2-year follow-up

This case report presents a minimally invasive diastema treatment using cordless gingival displacement system allowing a very conservative intervention. A 32-year-old female patient who presented with diastema in her upper front teeth opted for a treatment using laminate veneers to ensure achieving adequate tooth proportion and gingival levels. Having a displacement material that exerts excessive pressure during the displacement process can lead to disruption of the junctional epithelium and damage to periodontal tissues. This case report focuses on the effectiveness of the use of a minimally invasive method of gingival management. Two-year follow-up no infiltration, sensitivities, or fractures were detected on teeth, and indirect restorations, the purposed treatment allowed a quick, effective, and durable resolution for diastema.

Dental Impression Materials and Techniques

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

The Direct Cytotoxic Effects of Different Hemostatic Agents on Human Gingival Fibroblasts

PURPOSE

To evaluate the cytotoxic effects of different hemostatic agents (including Expasyl) on human gingival fibroblasts (HGFs) in vitro.

MATERIALS AND METHODS

HGFs were cultured and exposed to either no medicament treatment or 1:200 dilution of six different hemostatic agents (Hemox-A, Hemodent, Astringedent, Vicostat, Expasyl, 3M ESPE) for 2, 5, 10 minutes, 1 hour, and 24 hours. Toxicity to HGFs was determined by lactate dehydrogenase activity (LDH) and colorimetric (WST-1) assays. Two-tailed t-test was used for statistical analyses with α level set at 0.05.

RESULTS

The group-by-time interactions were significant for the LDH and WST-1 assays (p < 0.001). Evaluation of the cytotoxic effect of different hemostatic agents at different incubation time intervals on the cell membrane damage revealed that Astringedent showed the highest cytotoxic effect on HGFs compared to other agents with regards to untreated negative control cells at all incubation time intervals (p < 0.001). On the other hand, Expasyl showed the least cytotoxic effect with significant differences at 5 minutes and 1 hour (p < 0.001) in comparison to other agents.

CONCLUSIONS

LDH and WST-1 assays of hemostatic agents showed significant cytotoxic effect on HGFs at different time intervals. The data suggest that the risk for permanent tissue damage might be less significant when Expasyl is used during final impression procedure compared to when Astringedent is used.

Moldagem em prótese fixa: confecção do casquete de moldagem

O objetivo do artigo foi descrever a técnica de confecção de uma moldeira individual para moldagem de preparo total para coroa, também conhecida como casquete de moldagem, além de discutir fatores e princípios envolvidos no tema. Na presente técnica, é obtido um modelo de gesso da região do preparo e um alívio em cera é realizado em suas paredes axiais. Após a aplicação de um isolante, o casquete é confeccionado utilizando pó e líquido de resina acrílica ativada quimicamente indicada para confecção de restaurações provisórias. A resina acrílica é aplicada na região cervical utilizando um pincel, e em seguida, o restante do preparo é preenchido. Após finalizado o corpo do casquete, a área de retenção é criada (chapéu do casquete), a face vestibular é demarcada, e realizado acabamento e polimento.

Impression evaluation and laboratory use for single-unit crowns: Findings from The National Dental Practice-Based Research Network

BACKGROUND

Objectives were to determine the likelihood that a clinician accepts an impression for a single-unit crown and document crown remake rates.

METHODS

The authors developed a questionnaire that asked dentists about techniques used to fabricate single-unit crowns. The authors showed dentists photographs of 4 impressions and asked them to accept or reject each impression. The authors correlated answers with dentist and practice characteristics. Other questions pertained to laboratory use and crown remake rates.

RESULTS

The response rate was 83% (1,777 of 2,132 eligible dentists). Of the 4 impressions evaluated, 3 received consistent responses, with 85% agreement. One impression was more equivocal; 52% accepted the impression. The likelihood of accepting an impression was associated significantly with the clinician's sex, race, ethnicity, and practice busyness. Clinicians produced 18 crowns per month on average, and 9% used in-office milling. Most dentists (59%) reported a remake rate of less than 2%, whereas 17% reported a remake rate greater than 4%. Lower remake rates were associated significantly with more experienced clinicians, optical impressions, and not using dual-arch trays.

CONCLUSIONS

Although dentists were largely consistent in their evaluation of impressions (> 85%), nonclinical factors were associated with whether an impression was accepted or rejected. Lower crown remake rates were associated with more experienced clinicians, optical impressions, and not using dual-arch trays.

PRACTICAL IMPLICATIONS

These results provide a snapshot of clinical care considerations among a diverse group of dentists. Clinicians can compare their own remake rates and impression evaluation techniques with those in this sample when developing best practice protocols.

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.

Impression Techniques Used for Single-Unit Crowns: Findings from the National Dental Practice-Based Research Network

PURPOSE

To: (1) determine which impression and gingival displacement techniques practitioners use for single-unit crowns on natural teeth; and (2) test whether certain dentist and practice characteristics are significantly associated with the use of these techniques.

MATERIALS AND METHODS

Dentists participating in the National Dental Practice-Based Research Network were eligible for this survey study. The study used a questionnaire developed by clinicians, statisticians, laboratory technicians, and survey experts. The questionnaire was pretested via cognitive interviewing with a regionally diverse group of practitioners. The survey included questions regarding gingival displacement and impression techniques. Survey responses were compared by dentist and practice characteristics using ANOVA.

RESULTS

The response rate was 1777 of 2132 eligible dentists (83%). Regarding gingival displacement, most clinicians reported using either a single cord (35%) or dual cord (35%) technique. About 16% of respondents preferred an injectable retraction technique. For making impressions, the most frequently used techniques and materials are: poly(vinyl siloxane), 77%; polyether, 12%; optical/digital, 9%. A dental auxiliary or assistant made the final impression 2% of the time. Regarding dual-arch impression trays, 23% of practitioners report they typically use a metal frame tray, 60% use a plastic frame, and 16% do not use a dual-arch tray. Clinicians using optical impression techniques were more likely to be private practice owners or associates.

CONCLUSIONS

This study documents current techniques for gingival displacement and making impressions for crowns. Certain dentist and practice characteristics are significantly associated with these techniques.

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.

Gingival displacement: Survey results of dentists' practice procedures

STATEMENT OF PROBLEM

A high percentage of fixed prosthodontic restorations require a subgingival margin placement, which requires the practice of gingival displacement or a deflection procedure to replicate the margins in impression.

PURPOSE

The purpose of this study was to learn the different gingival displacement techniques that are currently used by dentists in their practice and to compare the current concepts of gingival displacement with previously published articles.

MATERIALS AND METHODS

A survey of questions pertaining to gingival deflection methods was distributed as part of continuing education (CE) course material to dentists attending CE meetings in 7 states in the U.S. and 1 Canadian province. Question topics included initial patient assessment procedures, gingival displacement methods, dentist's knowledge and assessment of systemic manifestations, and brand names of materials used.

RESULTS

Ninety-four percent of the participants were general practitioners with 24.11 ± 12.5 years of experience. Ninety-two percent used gingival displacement cords, while 20.2% used a soft tissue laser and 32% used electrosurgery as an adjunct. Sixty percent of the dentists used displacement cords impregnated with a medicament. Of the preimpregnated cords, 29% were impregnated with epinephrine, 13% with aluminum chloride, and 18% with aluminum potassium sulfate.

CONCLUSION

The study showed a steady decrease compared with results of previously published articles in the use of epinephrine as a gingival deflection medicament.