Effect of finish line location and saliva contamination on the accuracy of crown finish line scanning.

PURPOSE: Intraoral scanners are used widely as an alternative to conventional impressions, but studies on the influence of finish line location and saliva contamination on scanning trueness are lacking. The purpose of this in vitro study was to evaluate the influence of finish line location and saliva contamination on the scanning trueness of crown finish lines. MATERIALS AND METHODS: Three ivorine teeth were prepared for all-ceramic crowns with finish lines placed equigingivally, 0.5 mm subgingivally, and 1.0 mm subgingivally. A single-cord technique was used for gingival retraction, and a total of 180 intraoral scans were made using two intraoral scanners (Emerald; Planmeca USA Inc., Hoffman Estates, IL, USA & Trios 3; 3Shape A/S, Copenhagen, Denmark). The prepared teeth were separated from the dentoform and scanned using the same intraoral scanners to create reference scans. All scans were imported to the design software (Dental System 2019; 3Shape A/S, Copenhagen, Denmark). After marking the finish lines of prepared teeth, intraoral scans were aligned to the reference scans for comparisons. Vertical and horizontal marginal discrepancies were measured at four different measuring points (buccal, lingual, mesial, and distal) and analyzed. Two-way ANOVA and Tukey HSD tests were used for statistical analysis (α = 0.05). RESULTS: The average vertical and horizontal discrepancies from various groups ranged from -33 to 440 µm. For both intraoral scanners, subgingival finish line groups showed greater vertical and horizontal discrepancies compared with equigingival finish line groups. Saliva contamination significantly increased both vertical and horizontal discrepancies for all finish line locations. The discrepancy increases due to saliva contamination were greater for the subgingival groups. CONCLUSIONS: Subgingival finish lines were not accurately captured using the intraoral scanners. The presence of saliva significantly reduced scanning trueness, and this was amplified when the finish lines were located subgingivally.

Addition Silicone Impressions in Fixed Prosthodontics: Clinical Standpoints.

Addition silicones have revolutionized the field of fixed prosthodontics because of their dimensional stability, sufficient tear strength and excellent detail reproduction. This review study aims to provide a detailed description of the essential variables to be taken into account during the process of making addition silicone impressions in fixed prosthodontics. These variables include the selection of appropriate tray type, size, and fabrication; the use of tray adhesive; gingival displacement techniques; manipulation of the impression material; the choice of the impression material's viscosity; impression techniques; and the proper insertion, removal, disinfection, and pouring of the cast. Additionally, this review aims to help doctors produce high-quality impressions by empowering them to critically assess the impressions to spot mistakes and motivating them to redo impressions that have serious problems before submitting them to the laboratory.

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.

Dentists' knowledge and preference regarding gingival displacement methods.

INTRODUCTION: An accurate impression is an essential procedure for fabricating indirect fixed restorations. To achieve a precise final impression, the management of gingival tissue is without doubt a crucial. AIM: To evaluate the use of different gingival displacement techniques among dental clinicians and to assess their associated knowledge and technique preferences. METHODS: A self-designed survey was created electronically and sent to a list of dentists. The survey was composed of multiple sections. Participants who stated that they do not use GD methods were asked to answer the survey questions based on their knowledge. Descriptive statistics were generated, andChi-square test was used to examine the association between the different variables. RESULTS: A total of 188 dentists participated in this study. The majority 144 (76.6%) use GD in their practice. When asked which technique yields a more accurate impression with lower incidence of repeating the impression, 93 (64.6%) reported retraction cord technique with a hemostatic agent results in a higher impression accuracy, while only 14 (9.7%) declared the retraction paste technique as being more accurate. CONCLUSION: The cordless GD technique is believed to be easier, faster, and less traumatic to the gingival tissues, nevertheless, the outcome of dental impressions is believed to be more predictable with the use of conventional retraction cords and hemostatic medicaments.

Contemporary concepts on periodontal complications from prosthetic and restorative therapies.

The clinical outcome of every prosthetic and restorative procedure depends on the maintenance of a healthy periodontium. It is, therefore, important that the prosthodontist and restorative dentist cause no harm or permanent damage to the underlying hard and soft tissues when performing clinical procedures necessary to carry out the planned treatment. Several factors involved in these procedures have been described to have an impact on gingival health. For the present article, a selection of four of these factors are presented with the goal of evaluating the current trends and their influence on periodontal structures: (1) tooth preparation configuration and apical extension, (2) gingival tissue sulcular expansion/retraction, (3) prosthetic contours, and (4) prosthesis marginal adaptation and the consequences of excess cement remnants. Based on the available scientific evidence and clinical experience, recommendations for the practitioner are given.

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

Introduction: Gingival displacement is essential for ideal margin exposure and improved direct or indirect restorative outcome. Recent literature found many dentists prefer using retraction cord. Some contraindications of other displacement methods make retraction cord displacement preferred. It is necessary to teach dental students appropriate cord placement while minimizing gingival trauma. Methods: We developed a stone model using prepared typodont teeth and simulated gingiva that was made of polyvinylsiloxane material. Twenty-three faculty and 143 D2 students were briefed on the instructional guide. After faculty demonstration, D2 students practiced for 10-15 minutes under observation. The following year, former D2 (now D3) and D4 students were asked for feedback on the instructional experience. Results: Fifty-six percent of faculty rated the model and instructional guide good to excellent, and 65% rated the student experience as good to excellent, with only one participant rating it poor. Seventy-eight percent of D3 students strongly agreed or agreed the exercise increased their understanding of the technique in placing cord on a patient. Furthermore, 94% of D4 students strongly agreed or agreed having this exercise in preclinical D2 year would have been helpful. Discussion: Use of retraction cord to deflect gingiva is still preferred by most dentists. Completing the cord placement exercise on a model helps prepare students to perform the procedure on a patient before arriving at the clinic. Survey comments such as "useful exercise" support use of this instructional model. Overall, faculty and D3 and D4 students felt the exercise was beneficial to use in preclinical education.

Oral lesions associated with daily use of snus, a moist smokeless tobacco product. A cross-sectional study among Norwegian adolescents.

OBJECTIVE: Use of snus, a moist, smokeless tobacco product, may lead to local changes in the oral mucous membrane in the area where the snus is placed. It can also cause irreversible gingival retraction. This cross-sectional study aimed to investigate the relationship between use of snus, oral mucosal lesions (snus induced lesions) and gingival retractions among adolescents in Norway. MATERIAL AND METHODS: All 18-20 years olds visiting public dental health clinics in the south-eastern region of Norway between October 2015 and December 2016 were invited to participate. All participants (n = 1363) filled in an electronic questionnaire before a clinical examination. Of these, 216 used snus daily. RESULTS: Snus induced lesions were observed in 79.2% of daily snus using participants. In adjusted regression analyses, the odds of having a more severe lesion as opposed to a less severe lesion were 1.12 times greater for each additional box of snus used in a month (p < .01). Women were 46% less likely to have a severe lesion than men (p = .03). Gingival retractions were observed in 18.4% of the participants. The odds for dental retraction were significantly higher by 34% for each year of snus use. CONCLUSIONS: Most of the adolescents using snus had snus induced lesions, whereas approximately one-fifth had gingival retractions. The severity of the lesion and gingival retraction increased with the amount of snus boxes used and the duration of the snus use, respectively.

Comparative analysis of tensile strength between three types of retraction cords.

INTRODUCTION: Gingival retraction is the withdrawal of the marginal gingiva away from the tooth. This procedure creates a space between the prepared tooth and the gingival tissues to catch more fine details of the impression material. The most common retraction device used in clinical practice is the retraction cord.

Estimation of cytokine levels in gingival crevicular fluid following the use of different gingival retraction systems in patients requiring fixed partial dentures - An original research.

Gingival retraction is essential to get a dry and debris free field, which enables the impression material to flow into the gingival sulcus and record the area apical to the finish line. Effective gingival retraction without damaging periodontal tissue is extremely important. Objective: To comparatively evaluate the amount of inflammation, as assessed by TNF-α in GCF induced by three different gingival retraction techniques. Methods: Ten patients with a minimum of three teeth that required biomechanical preparation for fixed prostheses and acceptable oral hygiene with no periodontal pathology were included. The patients each received an oral prophylaxis. After a washout period of 10 days patients with gingival index scores of 0 or 1 were included. Measurements of TNF-α was done at baseline, after 30 min, after 7 days and after 28 days using ELISA test kit specific to TNF-α. Results: The sample population for whom Magic Foam cord was used showed a massive reduction in the amount of TNF -α, from 78% at 7 days to 18.6% at 28 days. There was a reduction in the percentage of TNF -α produced in the samples where normal knitted cord was used and for those where Expasyl was used from 95% to 64.2% and from 70% to 48.3% respectively. Conclusion: Maximum amount of inflammatory response was seen with plain knitted gingival retraction cord. This was followed by Expasyl gingival retraction system and the least amount of inflammatory cytokine was recorded with Magic Foam retraction cord.

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

INTRODUCTION: There are numerous gingival retraction systems available on the market. This study aimed to evaluate the clinical efficacy of four gingival retraction systems, namely, impregnated retraction cord, gingival retraction capsule, retraction paste, and polyvinyl acetate strips. METHODS: A total of 20 people were chosen for the study, and 100 specimens were collected. The specimens were classified into five groups based on the materials used for gingival displacement. On the first day, a baseline impression without gingival displacement was made. Afterward, impressions were made with any of the following four gingival retraction systems: impregnated retraction cord (SURE-Cord® Plus; Sure Dent Corporation, Jungwon-gu, South Korea), retraction capsule (3M ESPE astringent retraction paste capsule; 3M Corporation, St. Paul, MN), retraction paste (Traxodent® Hemodent® Paste Retraction System; Premier Dental Co., Plymouth Meeting, PA) and polyvinylacetate strips (Merocel; Merocel Co., Mystic, CT), with a 14-day interval between each system. The amount of gingival displacement was measured using an optical microscope as the distance from the tooth to the gingiva crest in a horizontal plane. RESULTS:  All experimental groups had higher gingival displacement than the control group (P < 0.01). Among the experimental groups, polyvinyl acetate strips had the highest gingival displacement value (541.65 µm), followed by impregnated retraction cord (505.37 µm), retraction capsule (333.57 µm), and retraction paste (230.63 µm). CONCLUSION:  Within the limits of this in vivo study, significant differences in horizontal gingival displacement were discovered among the four evaluated systems. The horizontal displacement requirements of 200 µm were exceeded by all four systems. The maximum value for gingival displacement was found in polyvinyl acetate strips (Merocel), followed by impregnated retraction cord (SURE-Cord), and retraction capsule (3M ESPE), and the lowest value was found in retraction paste (Traxodent).

Effectiveness of local and topical anesthesia during gingival retraction / Eficácia da anestesia local e tópica durante a retração gingival

Objective: To compare the effectiveness of local and topical anesthesia during gingival retraction in prepared abutment teeth. Material and Methods: 72 patients desiring full mouth rehabilitation or bilateral fixed partial denture in the same arch were selected based on the inclusion criteria framed and were randomly allocated into Groups A and B of 36 each. Patients in Group A received gingival retraction with topical anesthesia and Group B received gingival retraction with infiltration anesthesia. All the patients were tested for pain, discomfort and bleeding during gingival retraction. Results: There was no significant difference in pain, discomfort and gingival bleeding (P >.05) during gingival retraction using topical and local anesthetic agents. Conclusion: Topical anesthesia was equally effective as infiltration anesthesia in managing the pain, discomfort and bleeding during gingival retraction by cord packing in prepared abutment teeth. (AU)

Objetivo: Comparar a eficácia da anestesia local e tópica durante a retração gengival previa a moldagem em dentes pilares preparados. Material e Métodos: Foram selecionados 72 pacientes indicados para reabilitação bucal total ou prótese parcial fixa bilateral na mesma arcada com base nos critérios de inclusão formulados e alocados aleatoriamente nos Grupos A e B com 36 pacientes cada. Os pacientes do Grupo A receberam retração gengival com anestesia tópica e no Grupo B receberam retração gengival com anestesia infiltrativa. Todos os pacientes foram testados para dor, desconforto e sangramento durante o procedimento. Resultados: Não houve diferença significativa na dor, desconforto e sangramento gengival (P>. 05) durante a retração gengival com anestésicos tópicos e locais. Conclusão: A anestesia tópica foi tão eficaz quanto a anestesia de infiltração no controle da dor, desconforto e sangramento durante a retração gengival com fio retrator gengival em dentes pilares preparados.(AU)

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.

The Influence of Hemostatic Agents and Cordless Gingival Retraction Materials on Smear Layer: An Ex vivo Scanning Electron Microscope Analysis.

CONTEXT: Cordless gingival retraction materials are now routinely used method for gingival retraction. Although evidence-based information is available on the effect of gingival displacement cord and cordless system on the effectiveness of displacement and the periodontal health, there is a lack of literature regarding the effect of cordless retraction agents on enamel and dentin substrates. AIM: The purpose of this investigation was to analyze the changes on the smear layer induced by the hemostatic agent and cordless retraction material at scanning electron microscopic level. MATERIALS AND METHODS: Ferric sulfate (15.5% m/v), expasyl, and magic foam cord were evaluated. Buccal surfaces of 16 recently extracted mandibular premolars were prepared for metal-ceramic crowns, and four teeth each were exposed to ferric sulfate solution, expasyl, and magic foam cord, respectively, for 5 min. Teeth in the control group were exposed to distilled water. The assessment of changes was performed using a scanning electron microscope (SEM). RESULTS: SEM exhibited smear layer covering the dentin and occluding the dentinal tubules in the control group. Exposure to ferric sulfate caused the opening of few of the dentinal tubules whereas expasyl caused the partial removal of smear layer with dentinal plugs partially occluding the openings of most of the dentinal tubules. The specimens treated with magic foam exhibited a smear layer similar to the control group. CONCLUSIONS: The smear layer was affected most with ferric sulfate solution, followed by expasyl and magic foam cord. Magic foam cord did not affect the smear layer.

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.

Influence of Photodynamic therapy and different gingival retraction agents on bond integrity of composite to dentin.

AIM: The present study was undertaken to evaluate the influence of gingival retraction agents (Expasyl and Viscostat) and different conditioning methods (Total-etch, Self-etch, and PDT) on bond integrity of composite to dentin. MATERIAL AND METHODS: One hundred and eighty, third molars were collected cleaned and disinfected in thymol solution. The specimens were rooted vertically up to cementoenamel junction within polyvinyl cylinders (PVC). Based on gingival retraction materials samples were divided into three groups (n = 60). Group A: dentin applied with Expasyl; Group B: Viscostat was applied on dentin and Group C: Control. Dentin surface was treated with different surface conditioners. Etch and rinse, PDT MBP, and Two-step self-etch. A bonding agent was applied and composite buildup was done. Samples were placed in the universal testing machine for SBS. Bond failure was assessed using a stereomicroscope. Analysis of variance (ANOVA) and Tukey's post hoc test compared the means and standard deviations (SD) after SBS testing (p = 0.05). RESULTS: The highest score of bond strength was exhibited by group C1 (21.14 ±â€¯1.05 MPa-Etch & rinse + Tetric-N- Bond) whereas group C2 (12.15 ±â€¯0.28 -PDT MBPS + Tetric-N-Bond, No treatment group) demonstrated the lowest SBS. Based on the application of haemostatic agent, bond values among subgroups A1 (18.75 ±â€¯1.05 MPa - Expasyl + Etch & rinse + Tetric-N-bond) and B1 (17.84 ±â€¯0.11 MPa -Viscostat + Etch & rinse + Tetric-N-Bond) was comparable (p>0.05). Based on the conditioning methods, bond scores among groups C1 (21.14 ±â€¯1.05 MPa -Etch & rinse + Tetric-N- Bond) and C3 (19.05 ±â€¯1.28 MPa -Clearfill SE) were comparable (p >0.05). CONCLUSION: Viscostat and Expasyl result in compromised bond integrity of composite restoration to dentin in etch and rinse and self-etch group compared to no treatment group. However, the pre-application of Viscostat and Expasyl on dentin conditioned with PDT improved bond integrity of composite resin.

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 1st 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: 1st day, 1st month, 3rd month, 6th month, and 1st 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 1st 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.

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.

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.

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.

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.