Comparative evaluation of three gingival displacement systems: an in-vivo study

OBJECTIVE

The study aimed to evaluate and compare gingival retraction in terms of lateral and vertical displacement with a magic foam cord, conventional retraction cord, and laser.

PATIENTS AND METHODS

This in-vivo experimental study was performed on 60 patients. Three different gingival retraction systems were used to evaluate the amount of vertical and lateral displacement. The study sample units were divided into three groups of 20 units each. Tooth preparation was done for a metal-ceramic restoration with a subgingival finish line. Gingival displacement was accomplished with a magic foam cord, conventional retraction, and laser. Vertical and Lateral displacement was measured by the distance from the finish line to the free gingival margin in pre and post-displacement casts with the help of a traveling microscope. Stereomicroscopic images of the impression of ×10 resolution were scanned into an image analyzer to measure the lateral displacement. The data analyzed using one-way ANOVA and Bonferroni test were used to determine the significant difference at the p<0.05 level.

RESULTS

Independent group analysis comparing the vertical and lateral displacement within each group showed a statistically significant difference (p<0.05) with mean maximum vertical and lateral displacement achieved by lasers (0.73 and 0.61) followed by magic foam (0.37 and 0.21) and least by retraction cord (0.21 and 0.13), respectively.

CONCLUSIONS

Laser provided the maximum lateral and vertical displacement of the gingival margins, followed by magic foam cord, and the least with conventional retraction, which was statistically significant.

Evaluation of Effectiveness of Three New Gingival Retraction Systems: A Comparative Study

AIM

To analyze the clinical effectiveness of three new gingival retraction systems: knitted retraction cord, expanding polyvinyl siloxane, and aluminium chloride containing paste.

MATERIALS AND METHODS

Twenty patients were enrolled with age-group of more than 18 years and who required fixed prosthesis with minimum of two abutments. A preliminary impression of the arch was made with a stock metal tray and irreversible hydrocolloid impression material. Group WR-impression without retraction, Group A-impression after retraction with gingival retraction cord, Group B-impression after retraction with expanding polyvinyl siloxane, and Group C-impression after retraction with aluminium chloride containing paste. A total of four impressions were made for each abutment tooth. Each impression was given a label 1WR, 1A, 1B, 1C-20WR, 20A, 20B, 20C: where 1 denoted the sample number. Comparison of the stereomicroscopic images was done using image analysis software. Time required from start of placement of gingival displacement agents till completion was recorded in seconds with the help of a stop clock.

RESULTS

The mean gingival retraction was found to be the highest for subjects of Group C followed by Group A, Group B, and Group WR. This difference was found to be statistically significant. Highly significant mean difference in time of placement was observed between Group A and Group B, between Group B and Group C, and between Group C and Group A.

CONCLUSION

The aluminium chloride containing paste was found effective in almost all the variables considered.

CLINICAL SIGNIFICANCE

The choice of particular gingival retraction system/technique is dependent upon the clinical variables and on operator's preference.

Efficacy of Different Gingival Displacement Materials in the Management of Gingival Sulcus Width: A Comparative Study

AIM

The aim of this study was to assess the effectiveness of different gingival displacement materials in the management of the width of the gingival sulcus.

MATERIALS AND METHODS

Totally, 60 participants who were aged 18 years and more were chosen for this study. The eligible participants were those who required fixed prosthesis with at least one abutment. A modified sectional tray was used to make impressions with elastomeric materials along with additional polysilicon using the double mix single impression technique. All participants were divided randomly into three experimental groups with each group having 20 participants as follows: group I-Expasyl, group II-Magic Foam Cord, and group III-Traxodent. Soon after retraction, impressions were made and assessed in a comparable manner to pre-retraction impressions. Image analysis software was used to measure the quantity of displacement of the gingiva, marked as the distance from the tooth to the gingival crest in the horizontal level under stereomicroscope.

RESULTS

The highest mean sulcular gingival width (0.644 ± 0.22) was found in Traxodent group followed by Expasyl group (0.590 ± 0.11) and Magic Foam Cord group (0.528 ± 0.01). A statistically significant difference (p<0.001) was found between the groups. Intergroup comparisons between the gingival displacement materials showed a statistically significant difference (p<0.05) between group II and group III.

CONCLUSION

The present study concluded that all three gingival displacement materials lead to gingival displacement, which is needed for impression making. Slightly more retraction was seen in the Traxodent group when compared to the Expasyl group and Magic Foam Cord group.

CLINICAL SIGNIFICANCE

The success of fixed prosthodontic treatment depends upon precision and accuracy in every step involved in the procedure.One of the most vital stepsis making precise impressions in relation to dimensional accuracy, tear strength, etc. It is essential to have an adequate thickness of the impression material along the margins to avoid distortion. This objective can be achieved by acceptable gingival retraction.

Evaluation of Gingival Displacement with Aluminum Chloride and Naphazoline Hydrochloride: A Randomized Controlled Trial

The objective of this study was to evaluate the use of naphazoline hydrochloride in comparison with aluminum chloride for vertical gingival displacement. The inclusion criteria were: patients with a good general systemic condition; periodontal health; and thick gingival biotype. Moreover, the exclusion criteria were: smoking individuals; canine teeth or central incisors with carious lesions, abrasion, erosion, prosthetic abutments or unsatisfactory restorations; patients with periodontal disease; and users of continuous medication. 72 teeth were included and the Square Block Design was used to randomize the samples. Three measures were obtained from each tooth, and mean vertical gingival displacement was calculated. A descriptive analysis of the average displacement was performed. The normality test used was the Lilliefors' Test and for comparison between treatments, the Kruskal-Wallis Test was used. The Bartlett's Test for homogeneity of variances was used and a 5% (p ⟨ 0.05) significant level was considered. Thus, the Aluminum Chloride and Naphazoline Hydrochloride showed no statistically amount of gingival retraction than the control group (p = 0.3822). The average of gingival vertical displacement in all groups were less than 0,5 mm. The technique used did not allow any amount of horizontal displacement on obtained models.

Influence of gingival retraction paste versus cord on periodontal health: a systematic review and meta-analysis

OBJECTIVES

The effect of gingival retraction paste versus gingival retraction cord on periodontal tissue health is controversial. The aim of the present study was to evaluate the effect of gingival retraction paste versus gingival retraction cord on periodontal health by a systematic review and meta-analysis and to provide scientific guidelines for gingival retraction method selection in clinical work.

DATA SOURCES

The databases were systematically queried to collect studies exploring the effect of gingival retraction methods on periodontal tissue health in randomized controlled trials. Literature covering the period of January 1998 to April 2017 was extracted and the quality was assessed, followed by a random-effects meta-analysis with standardized mean differences and 95% confidence intervals. Eight studies met the inclusion criteria. The result of meta-analysis revealed that gingival retraction paste exhibited a less deleterious effect on the periodontal tissue compared with the gingival retraction cord technique measured by probing depth, Gingival Bleeding Index, and bleeding on probing (P < .05). However, no statistically significant differences were found in the measurements of Plaque Index, Gingival Index, and gingival recession between these two methods (P > .05).

CONCLUSIONS

Gingival retraction paste can work better than the gingival retraction cord method in protecting periodontal tissue health.

Hemostatic gingival retraction agents and their impact on prosthodontic treatment steps: A narrative review

The purpose of this topic review is to give a general overview of gingival retraction agents used during prosthodontic treatment, and the possible difficulties connected to them that may be faced by the dentist. Hemostatic agents are important for successful gingival retraction and in achieving hemostasis. However, these agents may show numerous negative effects on the prosthodontic treatment and oral tissues of which the practicing dentist must be aware, and which will be elucidated in this review. PubMed and Google Scholar databases were searched for publications up to and including 2017. The following key words were used in different combinations: "hemostatic agent," "astringent," "astringency," "epinephrine," "ferric sulfate," "aluminum chloride," "hemorrhage control," "soft tissue," "hard dental tissue," "self-etch adhesive," "total-etch adhesive," "bond strength," "impression," "gypsum," "plaster cast," and "dental cast." In the last three decades the hemostatic agents used by practicing dentists have changed from epinephrine towards astringents, with AlCl3 and Fe2(SO4)3 now the most popular. All of the currently known hemostatic agents cause some local, temporary gingival tissue damage, but only epinephrine is known to elicit negative systemic effects. Studies concerning the influence of hemostatic agents on impression materials show highly contradictory results regarding the possible polymerization-inhibiting properties of hemostatic agents, probably due to the lack of standardization of methodology. Hemostatic agents seem to alter the dentinal surface properties making it more resistant to acid etching. Therefore the relatively low acidity of self-etch adhesives when compared to total-etch systems may not be strong enough to sufficiently etch a more resistant dentinal surface, and consequently may result in lower adhesive bond strengths.

Clinical Assessment of Gingival Sulcus Width using Various Gingival Displacement Materials

AIM

This study aims to compare the clinical efficacy of three different gingival retraction systems on gingival sulcus width.

MATERIALS AND METHODS

Study was conducted on prepared right or left maxillary central incisor for 45 subjects. Totally, 15 patients were randomly allocated in three gingival displacement groups, i.e., group I (retraction cord impregnated with aluminum chloride), group II (magic foam), and group III (laser). The pre- and postdisplacement impressions were made with addition silicone material using two-stage double mix technique.

RESULTS

There was no difference between the groups at baseline. Group III produced more displacement (mean value 0.48 ± 0.101 mm) than group II (mean value 0.31 ± 0.09 mm) and group I (mean value 0.44 ± 0.11 mm), and this was statistically significant.

CONCLUSION

Laser gingival displacement system was found to be effective among the three retraction systems. Choice of gingival displacement system is based on clinical situation and choice of operator.

CLINICAL SIGNIFICANCE

The retraction groups in the study created greater amount of gingival retraction than the least sulcus width required for the elastomeric impression material and so are clinically useful.

To cord or not to cord? That is still a question

Data sourcesA broad computerised search with similar key terms was performed in different databases that included: Ovid Medline, Thomson's ISI Web of Science, PubMed, Science Direct, EMBASE and the Cochrane Library. Grey literature, dissertations, abstracts and theses were searched too. Reference lists of the selected articles were hand-searched.Study selectionThe inclusion criteria included in vivo randomised clinical trials and quasi-randomised clinical trials using gingival retraction techniques with and without cord. Studies were included if they examined the primary outcome from the review: efficiency of haemostasis control, the amount of gingival displacement and the influence of the techniques on gingival/periodontal health. Secondary outcomes accepted for the review included subjective factors reported by the patient such as pain, sensitivity, unpleasant taste and discomfort and operator's experience with both techniques. Non-English papers, clinical reports, animals studies or in vitro studies were excluded.Data extraction and synthesisTwo authors independently searched and screened the articles. Disagreements were resolved by discussion. A third reviewer participated in the eligibility of the studies. The risk of bias was assessed using the Cochrane Collaboration tool. Due to the heterogeneity of measurement variables across the studies and the differences among the studies, a meta-analysis was not performed. A narrative assessment was performed for the outcomes: moisture/bleeding control, gingival displacement, gingival/periodontal health and the subjective outcomes.ResultsFrom the initial search that retrieved 1,342 articles, 19 potential relevant full-text articles were considered for the review. Seven studies were selected for the systematic review. Four randomised clinical trials were included. Sample size ranged from eight to 252 participants per study. Five studies were conducted on patients requiring any indirect fixed restorations on prepared teeth. Two studies were done on unprepared teeth. In all studies, participants were in good health, had a healthy gingival condition and a sound periodontal status.ConclusionsBoth techniques are reliable in achieving gingival retraction. The review supports the observation that gingival retraction paste can more effectively help to achieve a dry field and at the same time be less injurious to soft tissues, however its ability to displace gingival tissues, compared to retraction cord, was compromising. Rather than considering the cost of material or the individual preference of the operator, choosing the right technique to maximise clinical efficiency should be based on scientific evidence. It seems that impregnated gingival cords are more effective on thick gingival tissue whereas paste is more effective when minimal retraction is required for haemostasis control, preservation of the gingiva and less tissue displacement.

[Application of animal models in gingival retraction experimental curriculum]

PURPOSE

To introduce a teaching method for gingival retraction, and evaluate its efficacy for implementation into experimental curricula.

METHODS

First, two kinds of animal models using pigs and cows (below 6 months of age) were established. Twenty-two experienced prosthodontists were then asked to apply gingival retraction on each animal model and evaluate the biofidelity of the 2 models' dento-gingival environment. The data was analyzed with SPSS19.0 software package for paired t test.Then, eighty pre-internship students were randomly divided into 2 groups. Besides the traditional teaching (lecture-based teaching), the experimental group (group A) also had access to skill training (using animal models to practice gingival retraction), while the control group (group B) only used the traditional teaching modality. All students' performance in gingival retraction and impression taking were evaluated in their internship. The data was analyzed with SPSS19.0 software package for Chi-square test.

RESULTS

Both pig and cow's dento-gingival environment were similar to that of human being, and there was no significant difference between the two models'biofidelities (P>0.05). In addition, both the effect of gingival retraction and the quality of impression in group A were significantly better than those in group B (P<0.05).

CONCLUSIONS

Compared with the traditional strategy,practising gingival retraction on animal models can offer greater opportunities for skill development,and be implemented for a wider range of applications.

[Laboratory evaluation of retraction cords properties]

The aim of the study was the investigation of the effect of two factors on the diameter changings of different types of retraction cords. Using an optical microscope MBS-10 (x10) the diameter of the different retraction cords was measured. The measurement also was performed after tension and after wetting cords with distilled water. The cords diameter decreased after their tension and increased after wetting. The degree of diameter changes depends on the kind of cords weaving. Braided cords "00" and "1" sizes diameter after it tension decreased at 31% and 37%, knitted cords under tension changed the diameter at 53% and 48%, correspondingly. Cords features after wetting also varied. Wetting of the braided cords with distilled water did not lead to significant diameter changes while wetting of knitted cords increases their diameter at 13% (00) and 15% (1).

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.

Rubber dam isolation--key to success in diastema closure technique with direct composite resin

The use of direct composite resin for diastema closure has technique advantages, including that the restorative procedure can be carried out in one appointment at a reasonable cost and without the removal of sound tooth structure. The use of a rubber dam for closing diastemas with composite resin is of paramount importance as it prevents moisture contamination and ensures increased gingival retraction compared to other techniques. This provides better access to the cervical area of the tooth, facilitating proper placement of resin to recreate the natural anatomical contours and contact point. Thus, there is a more natural adaptation of the restoration to the gingival tissue, avoiding a space between the papilla and the restored tooth. To illustrate the advantages of this technique, two diastema closure cases are presented using direct composite resin with rubber dam isolation.

Performance of fast-setting impression materials in the reproduction of subgingival tooth surfaces without soft tissue retraction

PURPOSE

Fast-setting impression materials may be prone to inaccuracies due to accidental divergence from the recommended mixing protocol. This prospective randomized clinical trial aimed to assess three-dimensional (3D) deviations in the reproduction of subgingival tooth surfaces and to determine the effect of either following or purposely diverging from the recommended mixing procedure for a fast-setting addition-curing silicone (AS) and fast-setting polyether (PE).

MATERIALS AND METHODS

After three impressions each were taken from 96 participants, sawcut gypsum casts were fabricated with a standardized procedure and then optically digitized. Data were assessed with a computer-aided 3D analysis.

RESULTS

For AS impressions, multivariate analysis of variance revealed a significant influence of the individual tooth and the degree to which the recommended mixing protocol was violated. For PE impressions, the ambient air temperature and individual tooth showed significant effects, while divergence from the recommended mixing protocol was not of significance.

CONCLUSIONS

The fast-setting PE material was not affected by changes in the recommended mixing protocol. For the two fast-setting materials examined, no divergences from the recommended mixing protocol of less than 2 minutes led to failures in the reproduction of the subgingival tooth surfaces.

One abutment-one time versus a provisional abutment in immediately loaded post-extractive single implants: a 1-year follow-up of a multicentre randomised controlled trial

PURPOSE

To compare immediately loaded post-extractive single implants using a definitive abutment versus provisional abutment later replaced by custom-made abutment.

MATERIALS AND METHODS

In two private clinics, 28 patients in need of one single post-extractive implant in the maxilla or mandible from the left second premolar to the right second premolar area were randomised shortly before tooth extraction to provisional abutment (PA) and definitive abutment (DA) groups. Three patients had to be excluded for buccal wall fracture after tooth extraction. In the PA group, implants were immediately restored using a platform-switched provisional titanium abutment and definitive platform-switched titanium abutments were used in the DA group. In both groups, a non-occluding provisional single crown was provided. Implants were definitively restored after 4 months. In the PA group, the abutment was removed and the impression was made directly on the implant platform. In the DA group an impression of the abutment was made using a retraction cord. Outcome measures were: implant failures; complications; and marginal peri-implant bone level changes. Patients were followed up to 1 year after loading.

RESULTS

Twelve patients were randomised to the DA group and 13 patients to the PA group. At the 12-month follow-up, no implant failed. One biological complication occurred in the DA group and one mechanical complication occurred in the PA group. All complications were successfully treated. One year after loading, implants in the DA group lost an average of 0.11 mm (SD: 0.06) of periimplant bone and implants in PA group about 0.58 mm (SD: 0.11). At the 12-month follow-up, there was a statistically significant difference in bone level change between groups (mean difference: 0.48 mm, CI 95% 0.40; 0.55, P < 0.0001).

CONCLUSIONS

Within the limits of this study, the non-removal of abutments placed at the time of surgery resulted in the maintenance of 0.5 mm more bone levels around immediately restored postextractive single implants than repeated abutment removal, although this amount of bone maintenance may not have a clinical impact. Conflicts of interest notification: Dr Tommaso Grandi and Dr Paolo Guazzi serve as consultants for JDentalCare. This study was completely self-financed and no funding was sought or obtained, not even in the form of free materials.

A novel technique to record crown and bridge impressions consistently

Achieving accurate impressions of crown and bridge preparations remains a challenge for practicing dentists despite numerous material and technique advances. Precise material placement around the prepared tooth, proper management of soft tissue, and timely dispensing of both wash and tray materials are among the difficulties. As demonstrated in two cases presented, a new pneumatic impression device has been developed as a means of enabling clinicians to create precision impressions more easily, without the need for retraction cord or retraction paste.

A three-die cast technique for duplicating free gingival form in zirconia crowns: two case reports

This report describes a duplication technique of free gingival form from a provisional restoration to a zirconia crown. Three die casts were manufactured from a silicone impression with an acrylic resin ring tray. The first die cast was for the zirconia framework, the second for the provisionalized transfer coping, and the third for relining the provisional restoration. A free gingival impression was taken using a provisionalized transfer coping, and a soft gingival cast was manufactured. The depth of free gingival transparency was measured using a zirconia shade plate. Then, the zirconia framework was customized to allow for subgingival porcelain space. This technique seems to contribute to the clinical-laboratory interface in computer-aided design/computer-assisted manufacture restorations.

Cytotoxic potential of vasoconstrictor experimental gingival retraction agents: in vitro study on primary human gingival fibroblasts

The aim of this in vitro study was to evaluate the cytotoxic effects of the vasoconstrictor experimental gingival retraction agents (VEGRAs) in a dynamic setting. The strong cytotoxic effects of the astringent-based conventional gingival retraction agents (ACGRAs) on human gingival fibroblasts (HGFs) in vitro was our motivation to evaluate the biocompatibility of the vasoconstrictor-based experimental gingival retraction agents (VEGRAs) for the selected minimally invasive chemical agent. These agents were used to create three self-made retraction gels. Human gingival fibroblasts (HGFs) were treated with two groups of retraction agents: 1) three α- and β-adrenergic agents (VEGRA-αβ-s) based on 0.1%, 0.01% and 0.05% HCl-epinephrine, and 2) seven α-adrenergic agents (VEGRA-α-s), including two commercially available 0.05% HCl-tetrahydrozoline solutions, one 0.05% HCl-oxymetazoline solution, 10% HCl-phenylephrine solution, and three new self-made experimental 0.05% HCl-tetrahydro zoline-based gels. The methyl thiazolyl tetrazolium (MTT) colorimetric assay was performed to determine the oxidoreductive mitochondrial function after 3, 5, 10 min and 24 h of incubation. The cytotoxic effect, measured by cell viability lower than the 50% threshold, was not observed at any time period, even 24 h after application of 0.05% HCl-tetrahydrozolinebased self-manufactured retraction gels. High cell viability values of human gingival fibroblasts after the treatment with the three self-made 0.05% HCl-tetrahydrozoline- based gels may serve as a basis for further studies aimed at selecting the best retraction agents biocompatible with gingival margin tissues.

[Three-dimensional model analysis of the gingival sulcus width from different retraction time]

OBJECTIVE

To explore the effect of gingival retraction time on the gingival sulcus width in different gingival areas, using three-dimensional (3D) model analysis.

METHODS

Forty-six premolars from 10 volunteers were included, gingival retraction cords were applied on the buccal sulcus for three times, and the retraction time was 5, 10 and 15 minutes respectively. The least interval between two retraction procedures was 2 weeks. Impressions and stone models were made before and after gingival retraction. 3D data of the models were acquired by a 3D line laser scanner. Models were superimposed and tooth coordinate was set up with special software. Sulcus widths from different retraction time and different gingival areas were measured and compared.

RESULTS

Sulcus widths between retraction of 5 and 10 minutes were significantly different at midbuccal and transitional line angle (TLA) gingival areas. At TLA areas, sulcus widths between retraction of 10 and 15 minutes were also statistically different, but the difference was not significant when compared with that of 5 and 10 minutes. Sulcus widths at midbuccal areas were significantly greater than that at TLA areas for all three retraction time.

CONCLUSION

Before making impressions, gingival retraction time of single-cord mechanical technique should be at least 10 minutes. For different gingival areas, the enlargement of gingival sulcus from gingival retraction and the optimal retraction time were different. 3D model analysis could be used as a new objective method to evaluate gingival retraction effect from different retraction time.