Effect of retraction materials on gingival health: A histopathological study

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.

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

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

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

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

Effect of CAD-CAM tool deterioration on the trueness of ceramic restorations

STATEMENT OF PROBLEM

Tools will gradually deteriorate with repetitive milling. However, tool lifetime can vary depending on the type of milling machine, the hardness of the ceramic material, and the size of the restoration. Studies evaluating the effect of tool deterioration on the trueness of milled restorations are lacking.

PURPOSE

The purpose of this study was to evaluate the effect of tool deterioration on the trueness of milled restorations.

MATERIAL AND METHODS

A patient requiring a ceramic crown was recruited. Repetitive milling of zirconia crowns (inCoris TZI; Dentsply Sirona) with tungsten carbide rotary instruments and glass-ceramic crowns (VITABLOCS mark II; Vita Zahnfabrik) with diamond rotary instruments was performed by using a 5-axis milling machine (inLab MC X5; Dentsply Sirona) until the machine software indicated replacing the largest tool. The percentage of deterioration for the largest tool was recorded before each milling. The trueness for different crown areas was evaluated by using a 3-dimensional evaluation software (Geomagic Control X; 3D systems), and the crowns were clinically evaluated. The crowns were grouped into 4 quadrants as per the deterioration percentage. The Pearson correlation (r) between the deterioration percentage and trueness and linear contrast analysis (partial eta squared [η]) among the groups were performed.

RESULTS

Glass-ceramic crown areas had low correlation except for mesial (high, r=0.63, high, η=0.37) and distal (medium, r=0.42, high, η= 0.34) areas, whereas zirconia crowns had low correlation for inner and internal areas and medium to high correlation for mesial (r= -0.31, η=0.33), distal (r= -0.53, η=0.36), occlusal (r= -0.32, η=0.164), external (r= 0.69, η=0.52), and marginal (r= -0.44, η=0.19) areas. Zirconia crowns had excellent marginal fit and occlusal contact and light to excellent proximal contact, whereas glass-ceramic crowns had excellent marginal fit, minor to major occlusal correction, and heavy proximal contact.

CONCLUSIONS

The effect of tool deterioration on trueness depended on material type and crown area. Only proximal areas were affected in the glass-ceramic crowns, whereas external, proximal, occlusal, and marginal areas were affected in the zirconia crowns. Trueness did not necessarily reflect the clinical quality of the crown, as both crown types were clinically satisfactory. Although zirconia crowns were overmilled in comparison with the reference design and glass-ceramic crowns, they had better clinical quality.

Evaluation of alpha-adrenomimetic agents for gingival retraction: A randomized crossover clinical trial

Context

The displacement of the gingiva around the tooth allows proper access during preparation, precise impression taking, and cementation procedures that has a direct bearing on the health of the periodontium. Several methods and agents are used for this purpose.

Aims

The primary aim of the study was to clinically evaluate the efficacy of naphazoline as a gingival retraction agent. The secondary aim was to compare it with tetrahydrozoline and aluminum chloride.

Settings and Design

Fifteen patients participated in a randomized crossover clinical trial at the Army College of Dental Sciences, Secunderabad, Telangana, India.

Subjects and Methods

Preliminary maxillary impressions were made with irreversible hydrocolloid for all patients to fabricate custom trays. After that, baseline impressions and cast for control group measurements were prepared. Gingival displacement was carried out in the right maxillary central incisor for all, with retraction cord soaked in three agents, either, aluminum chloride, tetrahydrozoline, or naphazoline. These agents were used in all patients with a washout period of 14 days. Elastomeric monophase impressions and die stone casts were recorded for each group. The central incisors were sectioned, and gingival retraction was measured using a measuring stereomicroscope.

Statistical Analysis Used

The gingival displacement was statistically analyzed using one-way ANOVA and post hoc Bonferroni.

Results

Naphazoline had the highest retraction (138.160 μm) followed by tetrahydrozoline (136.039 μm) and aluminum chloride (130.759 μm).

Conclusions

Naphazoline, tetrahydrozoline, and aluminum chloride show a clinically and statistically significant amount of displacement when compared to control. Among the three agents, naphazoline showed maximum displacement and maybe a good alternative with fewer side effects.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL SIGNIFICANCE

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

In vitro effects of vasoconstrictive retraction agents on primary human gingival fibroblasts

The biological activity of chemical retraction/displacement agents in surrounding periodontal tissues is of unquestionable importance, but the activity of these agents has not been completely elucidated. In the present study, we aimed to evaluate the in vitro effects of vasoconstrictive retraction agents on primary human gingival fibroblasts (HGFs). A total of six commercial adrenergic solutions (0.05 and 0.01% HCl-epinephrine, two based on 0.05% HCl-tetrahydrozoline, 0.05% HCl-oxymetazoline, and 10% HCl-phenylephrine) and three experimental gel formulations (EG-1, EG-2, and EG-3) were used to treat primary HGFs. The biological effect of the retraction treatment on the expression of collagen types I and III was detected by performing immunocytochemical analysis. The generation of reactive oxygen species triggered by the retraction agents were evaluated by using the dichlorofluorescein (DCF) fluorescent probe. The effect of retraction agents on the expression of fibronectin was visualized by confocal laser scanning microscopy. According to the results, experimental retraction gels did not limit the expression of collagen types I and III. EG-3 even induced the synthesis of both types of collagen. The DCF assay indicated oxidative stress similar to the control cells for most of the selected retraction agents. Experimental gels did not cause degradation of the cellular shape and morphology of the primary HGFs. The proposed experimental retraction gels in the present study demonstrated higher biocompatibility with primary HGFs, suggesting their use as clinical vasoconstrictive agents for the application of gingival retraction with minimal damage to periodontal tissues.

Bleeding Index and Monocyte Chemoattractant Protein 1 as Gingival Inflammation Parameters after Chemical-Mechanical Retraction Procedure

OBJECTIVE

A widely used chemical-mechanical method of gingival retraction can cause gingival tissue damage. The aim of this study was to test the influence of the chemical-mechanical gingival retraction procedures on the gingival bleeding index (GBI) and the salivary concentration of monocyte chemoattractant protein 1 (MCP-1) as an indicator of inflammatory changes in the gingiva.

MATERIALS AND METHODS

The effects of 2 different retraction agents (aluminum chloride and ferric sulfate) were compared, particularly their tissue damaging effect during tooth preparation. Therefore, GBI values and the salivary concentration of MCP-1 were assessed during the chemical-mechanical method of gingival retraction in a homogenous group of respondents. The subjects (n = 60) were divided into 2 experimental groups (G1 and G2) regarding the need for tooth preparing and making artificial crowns. Each group was further divided into 2 subgroups (R1 and R2) according to the type of the gingival retraction agent used (aluminum chloride and ferric sulfate).

RESULTS

Compared to the values at the study start, a statistically significant increase in GBI and salivary MCP-1 (p < 0.001) 1 day after gingival retraction agent application was observed in both experimental groups. After 72 h, the values were lower than in the second observation period but still statistically significantly higher compared to the study start (p < 0.001), which indicated the reversibility of the tissue changes.

CONCLUSION

Higher values of the investigated parameters were observed in the group of subjects with prepared teeth, and clinical changes were more pronounced after the use of ferric sulfate.

Comparison of Gingival Retraction Materials Using a New Gingival Sulcus Model

PURPOSE

To investigate the pressure generated by different retraction materials using a novel gingival sulcus model.

MATERIALS AND METHODS

A gingival sulcus model was made using a polymer frame filled with silicon. A pressure sensor and a sulcus-fluid simulation were embedded into the silicon chamber to evaluate the pressure generated by different retraction materials. Six sizes of Ultrapak retraction cords (Ultradent, sizes #000 - 3), 4 retraction pastes (Expazen, Expasyl, Acteon, Access Edge, Traxodent) and 2 retraction gels (Sulcus Blue, Racegel) were analyzed. The mean and median pressure, interquartile range, and standard deviation (SD) of n = 10 repeated measurements were calculated. Statistical analysis was conducted by Kruskal-Wallis test for differences between the main groups of retraction materials, and Mann-Whitney U-test was performed to analyze differences between the single retraction materials.

RESULTS

Pressure (mean ± SD) generated by retraction cords increased with increasing size (48.26 ± 11.29 kPa, size #000 to 149.27 ± 28.75 kPa for #3). There was a significant difference between sizes (p < 0.01), except in #0 versus #1, and #2 versus #3. Retraction pastes generated pressures that ranged from 82.74 ± 29.29 kPa (Traxodent) to 524.35 ± 113.88 kPa (Expasyl). Retraction gels generated pressures from 38.96 ± 14.68 kPa (Racegel) to 95.15 ± 24.18 kPa (Sulcus Blue). Pressure generated by Expasyl was significantly higher than pressure generated by all other tested materials (p < 0.001).

CONCLUSION

Pressure generated by retraction pastes and gels depends on the consistency of the retraction material, while pressure generated by retraction cords increased with increasing size of cords. Expasyl was found to generate the highest pressure compared to all other retraction materials.

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.

Comparison of the Fit of Lithium Disilicate Crowns made from Conventional, Digital, or Conventional/Digital Techniques

PURPOSE

To evaluate the fit of single crowns fabricated using conventional, digital, or cast digitization methods.

MATERIALS AND METHODS

One subject with a peg-shaped maxillary lateral incisor was selected in this study. Tooth preparation for an all-ceramic crown was performed and 10 conventional poly(vinyl siloxane) impressions, and 10 digital impressions using an intraoral scanner were made. Each working cast was scanned using a laboratory scanner and an intraoral scanner. Four groups were tested Group 1: conventional impressions. Group 2: cast laboratory scans. Group 3: cast scans using intraoral scanner. Group 4: direct intraoral scans. For group 1, heat-pressed glass ceramic crowns (IPS e.max Press) were fabricated using casts produced from the conventional impressions. For groups 2-4, crowns were milled using ceramic blocks (IPS e.max CAD). Ten crowns were fabricated for each group. Marginal and internal gaps were measured using a replica technique. Replicas were sectioned mesiodistally and buccolingually and were observed under a stereomicroscope. Three measurements were selected for each cut: occlusal, axial, and marginal. Statistical analysis was performed using two-way ANOVA and Tukey HSD tests.

RESULTS

For each replica, 6 measurements were made for the mesiodistal and the same for the buccolingual cuts, producing 12 measurement points per crown (4 measurements for marginal, 4 for axial, 4 for occlusal), 120 measurements for each group (40 measurements for marginal, 40 for axial, 40 for occlusal), and 480 measurements in total. Two-way ANOVA revealed location to be a significant factor (p = 0.001). No significant differences among groups (p = 0.456), and no interactions between groups and locations (p = 0.221) were found. Means for the occlusal site were significantly larger than other sites in most group combinations, while the difference between the marginal and axial sites was not significant. No significant differences among groups were found for each measurement. The marginal gaps ranged from 125.46 ± 25.39 μm for group 3 to 135.59 ± 24.07 μm for group 4. The smallest axial mean was in group 1 (98.10 ± 18.77 μm), and the largest was 127.25 ± 19.79 μm in group 4. The smallest occlusal mean was in group 2 (166.53 ± 36.51 μm), and the largest occlusal mean was in group 3 (203.32 ± 80.24 μm).

CONCLUSIONS

Ceramic crowns, which were made using all-digital approach or cast digitization by a laboratory or intraoral scanner had comparable fit to those produced by conventional approach.

Comparative evaluation of three noninvasive gingival displacement systems: An in vivo study

Aim:

An attempt is made to investigate clinical efficacy of cord, paste system, and a strip gingival retractile materials. This study aims to evaluate and compare the gingival retraction efficacy of retraction strip along with conventional retraction cord and paste system.

Material and Methods:

This in vivo experimental study was carried out on 30 patients. Three different gingival retraction systems were used to evaluate the amount of vertical and lateral displacement.

Based on selection criteria, 30 individuals requiring fixed dental prosthesis with respect to mandibular first molar were selected. Tooth preparation for metal ceramic restoration with subgingival finish line was performed. Gingival displacement was accomplished with ultrapak cord, merocel strip, and magic foam cord immediately, 7 and 14 days after the tooth preparation, respectively. The amount of gingival displacement in vertical and lateral directions was measured at mesiobuccal, midbuccal, and distobuccal regions of the prepared tooth. The vertical retraction was measured intraorally by using digital vernier caliper, and postgingival displacement impression was used to measure lateral gingival retraction. Stereomicroscopic images of impression under ×10 resolution were transferred to image analyzer to measure the lateral displacement. The obtained data analyzed in one-way ANOVA and Bonferroni test were used to determine the significant difference at P < 0.05 level.

Results:

ANOVA test showed the significant difference between the materials tested with respect to the mean vertical and lateral gingival retraction (P = 0.001). Multiple comparisons by Bonferroni test revealed a significant difference in vertical and lateral displacement among the materials tested.

Conclusions:

Merocel strip provided the maximum amount of vertical and lateral tissue displacement, followed by ultrapak cord and least with magic foam cord which was statistically significant.

Comparison between aluminum chloride and tetryzoline hydrochloride for control of vertical gingival displacement and crevicular fluid

Abstract Introduction The use of a gingival displacement cord with a gingival displacement substance is a common procedure for taking a quality impression of the cervical terminal in teeth for prosthetic purposes. Objective To evaluate whether the mechanical-chemical method with 0.05% tetryzoline hydrochloride or 25% aluminum chloride is capable of reducing crevicular fluid, and displacing a statistically significant larger quantity of gingival tissue vertically, compared with the mechanical method (without chemical substances). Material and method Ten patients were selected, and then No. 000 and 1 Ultrapak cords were randomly positioned on teeth 13, 21 and 23. Group I – cord with no chemical substance; Group II – cords impregnated with tetryzoline hydrochloride and Group III – cords impregnated with aluminum chloride. Using dental stone models, thirty images were captured with a camera coupled to a loupe to analyze the degree of gingival displacement. Crevicular fluid was quantified using a high-precision scale and individualized strips of absorbent paper for each tooth on which gingival displacement was performed. Result There was no statistical difference between the three groups relative to the amount of vertical gingival displacement (Anova, p=0.26). As regards reduction in crevicular fluid, there was no difference between the test and control groups (Wilcoxon and Friedman, p < 0.05). Conclusion The use of tetryzoline hydrochloride or aluminum chloride to impregnate the gingival displacement cord did not improve the quantity of vertical gingival displacement and did not reduce the amount of crevicular fluid.

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.

Acute periodontal lesions

This review provides updates on acute conditions affecting the periodontal tissues, including abscesses in the periodontium, necrotizing periodontal diseases and other acute conditions that cause gingival lesions with acute presentation, such as infectious processes not associated with oral bacterial biofilms, mucocutaneous disorders and traumatic and allergic lesions. A periodontal abscess is clinically important because it is a relatively frequent dental emergency, it can compromise the periodontal prognosis of the affected tooth and bacteria within the abscess can spread and cause infections in other body sites. Different types of abscesses have been identified, mainly classified by their etiology, and there are clear differences between those affecting a pre-existing periodontal pocket and those affecting healthy sites. Therapy for this acute condition consists of drainage and tissue debridement, while an evaluation of the need for systemic antimicrobial therapy will be made for each case, based on local and systemic factors. The definitive treatment of the pre-existing condition should be accomplished after the acute phase is controlled. Necrotizing periodontal diseases present three typical clinical features: papilla necrosis, gingival bleeding and pain. Although the prevalence of these diseases is not high, their importance is clear because they represent the most severe conditions associated with the dental biofilm, with very rapid tissue destruction. In addition to bacteria, the etiology of necrotizing periodontal disease includes numerous factors that alter the host response and predispose to these diseases, namely HIV infection, malnutrition, stress or tobacco smoking. The treatment consists of superficial debridement, careful mechanical oral hygiene, rinsing with chlorhexidine and daily re-evaluation. Systemic antimicrobials may be used adjunctively in severe cases or in nonresponding conditions, being the first option metronidazole. Once the acute disease is under control, definitive treatment should be provided, including appropriate therapy for the pre-existing gingivitis or periodontitis. Among other acute conditions affecting the periodontal tissues, but not caused by the microorganisms present in oral biofilms, infectious diseases, mucocutaneous diseases and traumatic or allergic lesions can be listed. In most cases, the gingival involvement is not severe; however, these conditions are common and may prompt an emergency dental visit. These conditions may have the appearance of an erythematous lesion, which is sometimes erosive. Erosive lesions may be the direct result of trauma or a consequence of the breaking of vesicles and bullae. A proper differential diagnosis is important for adequate management of the case.

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 clinical efficacy evaluation of three gingival displacement systems

AIM

We compared the clinical efficacy of three gingival displacement systems to accurately record intra-crevicular margins of tooth preparation.

MATERIALS AND METHODS

One mechanical (magic foam cord) and two chemico-mechanical (expasyl paste and retraction cord impregnated with 15% aluminum chloride) gingival displacement systems were used. This study was conducted on the maxillary central incisors of 20 patients (20-60 years old) requiring full coverage restoration. All the three gingival displacement systems were tested in three sessions at an interval of 14 days in same order. The casts were sectioned and viewed under an optical microscope, followed by quantitative measurements of the width of the pre and postretracted sulci.

RESULTS

All the three displacement systems produced highly significant horizontal gingival displacement. Retraction cord soaked in 15% aluminum chloride produced maximum displacement (0.74 mm), followed by expasyl paste (0.48 mm) whereas magic foam cord produced the least displacement (0.41 mm).

CONCLUSIONS

Gingival displacement shown by each displacement system was found to be more than the accepted value necessary for elastomeric impression accuracy (0.2 mm) to record intra-crevicular margins of tooth preparation.

Comparative evaluation of the amount of gingival displacement produced by three different gingival retraction systems: An in vivo study

Statement of Problem:

Tetrahydrozoline has been introduced as new gingival retraction agent but its clinical efficacy with widely used conventional retraction agents has not been tested.

Purpose:

The study was designed to clinically evaluate efficacy of newer retraction agent tetrahydrozoline with two widely used retraction systems i.e., Expasyl retraction system and medicated retraction cords on basis of amount of gingival retraction.

Materials and Methods:

30 subjects were selected according to inclusion and exclusion criteria. Maxillary Impressions were made with irreversible hydrocolloid for all subjects. Tray material was used for making the special tray. Latin Block Design was Used in the Study to avoid tissue fatigue. Retraction was done with aluminium chloride; Tetrahydrozoline and Expasyl according to Latin block design. Impressions were poured with die stone. Casts were retrieved and sections were made with die cutter. 3 mm thin slices were obtained. Each slice was used to measure the amount of retraction under stereomicroscope under 20x and images were transferred to image analyser.

Results:

The amount of gingival retraction obtained by using aluminium chloride as gingival retraction agent was maximum (148238.33 μm²) compared to tetrahydrozoline (140737.87 μm²) and Expasyl (67784.90 μm²).

High-frequency ultrasound as an option for scanning of prepared teeth: an in vitro study

Because of its ability to non-invasively capture hard structures behind soft tissue, high-frequency ultrasound (HFUS)-assisted microscanning could be a patient-friendly and promising alternative for digitization of prepared teeth. However, intra-oral HFUS microscanners for taking digital impressions of prepared teeth are still not available in the clinical setting. Because working range, scanner size, scanning time, surface reconstruction accuracy and costs are major factors in such a system, our overall objective is to minimize hardware efforts and costs while maintaining the accuracy of the surface-reconstructed tooth model in the range 50 μm. In the work described here, we investigated the accuracy of tooth impression taking using a single-element HFUS microscanner with only three translational degrees of freedom under the restriction that only one occlusal scan is performed per tooth. As in favor of time and scanning efforts the data density is expected to be low, the surface reconstruction process is linked to a model-based surface reconstruction approach using a thin spline robust point matching algorithm to fill data gaps. A priori knowledge for the model is generated based on the original HFUS measurement data. Three artificial teeth and one human molar were prepared and scanned using an extra-oral HFUS laboratory microscanner that was built to test and evaluate different scanning setups. A scanner with three translational degrees of freedom was used to scan the teeth from an occlusal direction. After application of the proposed thin-spline robust point matching algorithm-based reconstruction approach, reconstruction accuracy was assessed by comparing the casts with a control group scanned with an extra-oral laser-scanning system. The mean difference between the reconstructed casts and the optical control group was in the range 14-53 μm. The standard deviation was between 21 and 52 μm. This let us assume that the suggested approach can help to decrease hardware efforts while maintaining the robustness of the 3-D surface reconstruction process for future HFUS-based intra-oral scanners.

A double-blind randomised clinical trial of two techniques for gingival displacement

Knowledge about security and the potential damage originated by the gingival displacement techniques has not been described through randomised clinical studies. This crossover, double-blind, randomised clinical trial evaluated clinical and immunological factors related to conventional and cordless gingival displacement (GD) techniques, and patients' perceptions in 12 subjects with the employment of 2 GD techniques: conventional (gingival cord + 25% AlCl3 astringent gel) and cordless (15% AlCl3 astringent-based paste). In each subject, two anterior teeth were treated and a 10-day wash-out period separated the two treatments. Periodontal indices were evaluated before (baseline) and 1 and 10 days after GD. Interleukin 1β, interleukin 6 and tumour necrosis factor α concentrations in gingival crevicular fluid were measured before and 1 day after GD. Subjective parameters (pain, unpleasant taste and stress) were also evaluated. Data were analysed by one-way repeated-measures analysis of variance and Tukey's test (immunological factors), the Friedman test (periodontal parameters) and Fisher's exact or chi-squared test (subjective parameters), with a significance level of 95%. Gingival bleeding index, probing depth and plaque index values did not differ significantly between groups at any timepoint. Neither technique resulted in worse periodontal indices. Both techniques yielded similar results for pain and unpleasant taste, but conventional GD was significantly more stressful than cordless GD for volunteers. Both treatments significantly increased mean concentrations of the three cytokines, with the conventional technique producing the highest cytokine levels. Cordless GD is less stressful for patients and results in lower post-treatment levels of inflammatory cytokines compared with conventional GD.

The influence of retraction agents on cytoskeleton reorganization and oxidative stress in primary human gingival fibroblasts (HGFs)

OBJECTIVE

Contemporary gingival retraction chemicals are not without disagreeable side-effects; there appears to be no best gingival retraction agent. The aim of this research was to select the most biocompatible retraction agents based on examination of the parameters of oxidative stress in fibroblasts derived from human primary cell culture.

DESIGN

In this in vitro study we evaluated parameters of oxidative stress after treatment with retraction agents. Visine, Afrin, Neosynephrin, Strazolin and Adrenaline were the commercial products studied as gingival retraction agents. Additionally we examined three experimental agents. We determined lipid peroxidation and protein damage and monitored changes in cellular cytoskeleton proteins. Proliferative and survival efficiency were also evaluated.

RESULTS

Oxidative changes included by evaluated retraction agents were at the lowest level in the case of the experimental gels. Also cytoskeleton observations suggest that the experimental agents did not degrade the cellular structure of human gingival fibroblasts (HGFs).

CONCLUSIONS

The current study was performed because of a need to project new nontoxic and save retraction agents for peridontological therapeutic usage. We suggest that the new investigational gels are most biocompatible with periodontal tissues and can be applied as new vasoconstrictor chemical retraction agents.

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.

A review on common chemical hemostatic agents in restorative dentistry

Control of hemorrhage is one of the challenging situations dentists confront during deep cavity preparation and before impressions or cementation of restorations. For the best bond and least contamination it is necessary to be familiar with the hemostatic agents available on the market and to be able to choose the appropriate one for specific situations. This review tries to introduce the commercially available hemostatic agents, discusses their components and their specific features. The most common chemical agents that are widely used in restorative and prosthodontic dentistry according to their components and mechanism of action as well as their special uses are introduced. PubMed and Google Scholar were searched for studies involving gingival retraction and hemostatic agents from 1970 to 2013. Key search words including: "gingival retraction techniques, impression technique, hemostasis and astringent" were searched. Based on the information available in the literature, in order to achieve better results with impression taking and using resin bonding techniques, common hemostatic agents might be recommended before or during acid etching; they should be rinsed off properly and it is recommended that they be used with etch-and-rinse adhesive systems.

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.