Effect of retraction procedures on the periodontium in humans

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.

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.

A digitally designed and 3D printed individual tooth tray for taking subgingival impression of complete crown preparation

A digital technique for designing and fabricating an individual tooth tray used for taking subgingival impression of complete crown preparation was described. The digital model of required dentition region was obtained before performing crown preparation. An individual tooth tray with retention attachments was designed and printed with plastic material. After conducting crown preparation, the individual tooth tray loaded with the final impression material was placed onto the abutment to deliver the impression material subgingivally. A final overall impression was made with full arch stock tray to pick up the individual tooth tray with the accurate impression of abutment.

The Relationships Between Tooth-Supported Fixed Dental Prostheses and Restorations and the Periodontium

PURPOSE

To search the literature and to critically evaluate the findings on the periodontal outcomes of restorations and tooth-supported fixed prostheses.

MATERIALS AND METHODS

PubMed was searched according to a systematic methodology, previously reported, but updated to include a larger database. Filters applied were: Case reports, clinical trial, review, guideline, randomized controlled trial, meta-analysis, systematic reviews, and English. A narrative review was then synthesized to discuss periodontal outcomes related to restorations and tooth-supported fixed prostheses. Relevant data was organized into four sections: Direct restorations, indirect restorations, biologic width or supracrestal tissue attachment and tooth preparation/finish line design.

RESULTS

While increased gingival index, bleeding on probing, probing depth and clinical attachment loss have been associated with subgingival restorations, intracrevicular margins do not cause periodontal diseases. Inflammation and bone loss occur, for both direct and indirect restorations, only with large overhangs. Different restorative materials are associated with different clinical responses when placed in the gingival sulcus or within the epithelial and connective tissue attachments. When the connective tissue attachment is removed, histological changes occur causing its apical shift and subsequent re-establishment. Gingival displacement during impression procedures can cause gingival recession. Emergence profile can have a range of values, not associated with periodontal diseases. Periodontal response appears to be clinically not different when compared among different finish line designs.

CONCLUSIONS

Contemporary procedures and materials used for the placement and fabrication of tooth-supported restorations and fixed prostheses are compatible with periodontal health when adequate patient education and motivation in self-performed oral hygiene are present. Periodontal diagnostic criteria should be thoroughly reviewed before fixed restorative treatments are planned and executed.

Dental prostheses and tooth-related factors

OBJECTIVES

This narrative review summarizes the current evidence about the role that the fabrication and presence of dental prostheses and tooth-related factors have on the initiation and progression of gingivitis and periodontitis.

FINDINGS

Placement of restoration margins within the junctional epithelium and supracrestal connective tissue attachment can be associated with gingival inflammation and, potentially, recession. The presence of fixed prostheses finish lines within the gingival sulcus or the wearing of partial, removable dental prostheses does not cause gingivitis if patients are compliant with self-performed plaque control and periodic maintenance. However, hypersensitivity reactions to the prosthesis dental material can be present. Procedures adopted for the fabrication of dental restorations and fixed prostheses have the potential to cause traumatic loss of periodontal supporting tissues. Tooth anatomic factors, root abnormalities, and fractures can act as plaque-retentive factors and increase the likelihood of gingivitis and periodontitis.

CONCLUSIONS

Tooth anatomic factors, such as root abnormalities and fractures, and tooth relationships in the dental arch and with the opposing dentition can enhance plaque retention. Restoration margins located within the gingival sulcus do not cause gingivitis if patients are compliant with self-performed plaque control and periodic maintenance. Tooth-supported and/or tooth-retained restorations and their design, fabrication, delivery, and materials have often been associated with plaque retention and loss of attachment. Hypersensitivity reactions can occur to dental materials. Restoration margins placed within the junctional epithelium and supracrestal connective tissue attachment can be associated with inflammation and, potentially, recession. However, the evidence in several of the reviewed areas, especially related to the biologic mechanisms by which these factors affect the periodontium, is not conclusive. This highlights the need for additional well-controlled animal studies to elucidate biologic mechanisms, as well as longitudinal prospective human trials. Adequate periodontal assessment and treatment, appropriate instructions, and motivation in self-performed plaque control and compliance to maintenance protocols appear to be the most important factors to limit or avoid potential negative effects on the periodontium caused by fixed and removable prostheses.

Dental prostheses and tooth-related factors

OBJECTIVES

This narrative review summarizes the current evidence about the role that the fabrication and presence of dental prostheses and tooth-related factors have on the initiation and progression of gingivitis and periodontitis.

FINDINGS

Placement of restoration margins within the junctional epithelium and supracrestal connective tissue attachment can be associated with gingival inflammation and, potentially, recession. The presence of fixed prostheses finish lines within the gingival sulcus or the wearing of partial, removable dental prostheses does not cause gingivitis if patients are compliant with self-performed plaque control and periodic maintenance. However, hypersensitivity reactions to the prosthesis dental material can be present. Procedures adopted for the fabrication of dental restorations and fixed prostheses have the potential to cause traumatic loss of periodontal supporting tissues. Tooth anatomic factors, root abnormalities, and fractures can act as plaque-retentive factors and increase the likelihood of gingivitis and periodontitis.

CONCLUSIONS

Tooth anatomic factors, such as root abnormalities and fractures, and tooth relationships in the dental arch and with the opposing dentition can enhance plaque retention. Restoration margins located within the gingival sulcus do not cause gingivitis if patients are compliant with self-performed plaque control and periodic maintenance. Tooth-supported and/or tooth-retained restorations and their design, fabrication, delivery, and materials have often been associated with plaque retention and loss of attachment. Hypersensitivity reactions can occur to dental materials. Restoration margins placed within the junctional epithelium and supracrestal connective tissue attachment can be associated with inflammation and, potentially, recession. However, the evidence in several of the reviewed areas, especially related to the biologic mechanisms by which these factors affect the periodontium, is not conclusive. This highlights the need for additional well-controlled animal studies to elucidate biologic mechanisms, as well as longitudinal prospective human trials. Adequate periodontal assessment and treatment, appropriate instructions, and motivation in self-performed plaque control and compliance to maintenance protocols appear to be the most important factors to limit or avoid potential negative effects on the periodontium caused by fixed and removable prostheses.

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

Aim

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

Settings and Design

Comparative - In vivo study.

Material and Methods

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

Statistical Analysis used

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

Results

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

Conclusions

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

Update on Perio-Prosthodontics

Knowledge of the periodontal-restorative interface is critical in the fabrication of restorations that are functional and esthetic. Understanding biological principles allows the clinician to predict how the periodontium will respond to restorative therapy. Factors that influence the response to therapy in the periodontal-restorative interface are periodontal biotype, gingival architecture, alveolar crest position, gingival margin position, and gingival zenith.

Comparative evaluation of three gingival displacement materials for efficacy in tissue management and dimensional accuracy

Aim:

Displacement of gingiva is essential for obtaining accurate impressions for the fabrication of fixed prostheses, particularly when the finish line is at or within the gingival sulcus. Various newer impression materials have been introduced to achieve gingival displacement while recording the impressions. A comparative evaluation of these new gingival displacement materials was deemed necessary for efficacy in tissue management and dimensional accuracy.

Materials and Methods:

Ten individuals were selected according to the inclusion and exclusion criteria for gingival displacement using retraction cord impregnated with aluminum chloride and two polyvinyl siloxane impression materials (Aquasil and NoCord VPS impression system) according to Latin block design. Intraoral scanner and Vernier caliper were used to study and compare the dimensional accuracy of each die obtained following which the dies were sectioned and evaluated under optical microscope with image analyzer to measure the amount of gingival retraction.

Results and Conclusion:

Statistical analysis showed that the amount of gingival retraction obtained by using retraction cord impregnated with aluminum chloride as gingival retraction agent was maximum as compared to NoCord followed by Aquasil. All three gingival displacement techniques could produce gingival displacement >0.2 mm which is the optimum amount of retraction required for impression making. All the three materials are found to be dimensionally accurate.

Comparison of four cordless gingival displacement systems: A clinical study

STATEMENT OF PROBLEM

Although the conventional chemicomechanical cord technique is widely used, packing the cord into the sulcus may cause pain and bleeding. Cordless displacement techniques have been introduced, but a comparison of these systems is lacking.

PURPOSE

The purpose of this clinical study was to evaluate the efficiency and gingival response of 4 cordless gingival displacement systems.

MATERIAL AND METHODS

One hundred twenty teeth in 30 participants were allocated to 4 groups according to the material used: Tr (Traxodent; Premier Dental Products Co), Es (Expasyl; Acteon UK), Ez (Expazen; Acteon UK), and Mr (3M Retraction; 3M ESPE). Baseline measurements of periodontal indices and a digital scan were acquired. The cordless displacement pastes were applied according to the manufacturer's instructions. After removal, a second scan was acquired. Participants were recalled on the 2nd and 14th day to measure periodontal indices and for scans. Screenshots were superimposed to measure changes in the gingiva. Statistical differences among the different materials in achieving lingual and buccal vertical gingival displacement were tested using the related-samples Friedman 2-way ANOVA test by ranks at 3 time points such as immediate, at 2 days, and at 14 days (α=.05).

RESULTS

Immediate gingival displacement varied with the system used. For horizontal displacement, median values ranged between 150 μm (Tr) and 725 μm (Ez) for buccal displacement and between 93 μm (Tr) and 550 μm (Ez) for lingual displacement. Minimum and maximum displacements also varied and followed a similar trend, with Traxodent providing the lowest displacement. The plaque index and attachment level did not statistically differ before and after the treatment. The periodontal parameters were not statistically significant among the groups at all time intervals, except for the gingival index that increased for all the groups after 2 days.

CONCLUSIONS

Significant differences were found among the 4 tested systems in both vertical and horizontal gingival displacement. Expasyl, Expazen, and 3M Retraction exceeded the 200-μm requirements for horizontal displacement. Traxodent provided the least displacement in both vertical and horizontal dimensions.

[Healing of the periimplant mucosal tissue injury after placing retraction cord subgingivally in beagle dogs]

OBJECTIVE

This work aims to observe the healing of periimplant mucosal tissue injury in beagle dogs after subgingival retraction cord placement by examining the gingival index (GI), quantity of gingival crevicular fluid (GCF), and the proinflammatory cytokine in the GCF.

METHODS

In eight beagle dogs, the fourth mandibular premolars on the left side were extracted (n=8); after two months of healing, bone-level implants were installed. A plaque control regimen was performed throughout the duration of the experiment. After three months, retraction cords were placed subgingivally for 5 min before the cement-retained implant-supported crowns were cemented. GI, GCF quantity, and levels of tumor necrosis factor-alpha (TNF-α) in GCF were assessed before application and on days 1, 3, 7, 14, 28, and 56 after application.

RESULTS

GI, quantity of GCF, and TNF-α were significantly increased on days 1, 3, and 7 compared with those at the baseline and on days 14, 28, and 56 (P<0.05), and no statistically significant differences were observed among those on days 14, 28, and 56 and the baseline (P>0.05).

CONCLUSIONS

Under the circumstances of good oral hygiene, acute injury caused by placing retraction cord subgingivally in periimplant mucosal tissue of bone-level implant is reversible. GI, the quantity of GCF, and TNF-α on day 14 return to the baseline levels.

A multicenter randomized, controlled clinical trial comparing the use of displacement cords, an aluminum chloride paste, and a combination of paste and cords for tissue displacement

STATEMENT OF PROBLEM

Gingival recession after soft tissue displacement for impression making in fixed prosthodontics may pose a problem for treatment success in the esthetic areas of the mouth. Knowledge about the soft tissue reaction of common gingival displacement methods is limited.

PURPOSE

The purpose of this clinical randomized controlled trial (RCT) was to evaluate changes in the marginal soft tissue height with 3 different gingival tissue displacement techniques for definitive impression making of natural teeth.

MATERIAL AND METHODS

A total of 67 individuals were randomized to 3 groups. In test group 1 (P; n=22), only aluminum chloride paste was used to displace the gingiva. In test group 2 (CP; n=23), a cord was inserted, and aluminum chloride paste was also used. In the control group (C; n=22), 2 cords were used to displace the gingiva (double-cord technique). Clinical measurements of the gingival position were made before treatment began and at 30 ±10 days after prosthesis delivery. Study casts were fabricated at different stages of the treatment, standardized photographs were made, and changes in the buccal gingival position were measured using graphics editing software. In addition, the participants' perception of the clinical procedure and the technicians' evaluation of the die preparation were recorded. One-way ANOVA models were applied to compare the response variables among the groups: (a) the position of the gingival margin (millimeters), (b) mean probing pocket depth (millimeters), (c) gingival thickness (millimeters), (d) amount of keratinized tissue (millimeters), and (e) mean changes in gingival margin height (millimeters). Unpaired t tests were also used to compare the mean values between groups. For comparisons between different categories, chi-square tests were performed (α=.05 for all tests).

RESULTS

In the period between impression and delivery, a minor gain in gingival height of 0.058 mm (±0.13 SD) for P and 0.013 mm (±1.19 SD) for CP. However, a minor gingival recession of 0.049 mm (±0.13 SD) was reported for group C. The results for all groups showed that 21% of abutment teeth gained >0.1 mm in gingival height, 58% had stable gingival height (0 ±0.10 mm), 21% showed minor gingival recession (0.1 to 0.5 mm), and no abutment teeth showed moderate or severe gingival recession (>0.5 mm). The incidence of minor gingival recession was 8% in group P, 23% in group CP, and 32% in group C (P=.015). Fifteen participants (24%) experienced some discomfort after the procedure. The differences between the groups were not significant (P>.05). The laboratory technicians found the definitive die preparation significantly more challenging for group P (visual analog scale [VAS], 79) and CP (VAS, 82) than group C (mean VAS, 93; P=.003).

CONCLUSIONS

Minor or moderate gingival recession (<1 mm) is more likely to occur when conventional cords are used during impression making. However, the laboratory technicians found the die preparation significantly less challenging when the double-cord technique was used than when impressions were made using the paste displacement technique.

Effect of gingival displacement cord and cordless systems on the closure, displacement, and inflammation of the gingival crevice

STATEMENT OF PROBLEM

The gingival sulcus should remain open long enough for the impression material to flow into it and completely fill the space provided by the gingival displacement. Impressions with less sulcal width have a higher incidence of voids, tearing of impression materials, and reduction in marginal accuracy.

PURPOSE

The purpose of this clinical study was to investigate the closure, gingival displacement, and gingival inflammation of the gingival crevice after the use of medicated gingival displacement cord and cordless systems.

MATERIAL AND METHODS

Gingival sulcus closure was studied in 40 participants. They were divided into 4 groups: 2 cord (Ultrapack, SilTrax AS) and 2 cordless (Expasyl, Traxodent Hemodent paste) methods. The labial surfaces of the maxillary right and left central incisors were evaluated. Gingival sulcus was photographed every 20 seconds from 0 to 180 seconds after the removal of the cord or cordless system. The bleeding index (BI) and gingival index (GI) were measured at day 0, day 1, and day 7. The width of the sulcal orifice was measured at the mid-buccal (MB) and transitional line angle (TLA) on a digital image, using computer software (Photoshop version 7.0; Adobe). Data were analyzed with ANOVA, Tukey honest significant difference (HSD), Kruskal-Wallis, and Mann-Whitney U tests (α=.05).

RESULTS

All groups showed a sulcal width greater than 0.22 mm up to 60 seconds after the removal of the displacement materials at the MB and up to 40 seconds at the TLA. Among all groups, Expasyl showed the fastest closure. Gingival displacement in the MB area for the cord group was greater than for the cordless groups. GI and BI indices were larger for the cord group than for the cordless group at days 0 and 1.

CONCLUSIONS

At up to 60 seconds, the cord and cordless techniques were equally effective. The cord group showed a greater amount of displacement than the cordless group. However, the cordless materials showed reduced frequency of changes to the gingival index.

Periodontal response to two different subgingival restorative margin designs: a 12-month randomized clinical trial

OBJECTIVES

Subgingival margin placement is sometimes required due to different reasons and is often associated with adverse periodontal reactions. The purpose of this study was to determine if a single restoration with subgingival margin on a tooth, in the maxillary anterior zone, would affect its periodontal soft tissue parameters, and whether or not a deep chamfer preparation has a different influence in the periodontium when compared to a feather edge preparation.

MATERIAL AND METHODS

Plaque and gingival indexes, periodontal probing depth, bleeding on probing, and patient's biotype were registered. One hundred six teeth were prepared with a deep chamfer, while 94 were prepared with a feather edge finishing line. Twelve months after the restoration delivery, the same parameters were evaluated. Repeated measure one-way analysis of variance (ANOVA) (α = 0.05) was used.

RESULTS

A statistically significant difference between the baseline and the 12-month follow-up is present in regard to plaque index, gingival index, and periodontal probing depth, but no statistically significant difference between chamfer and feather edge finishing lines. There is a statistically significant difference between the baseline and the 12-month follow-up in regard to bleeding on probing. Feather edge preparation presents significantly more bleeding on probing and less gingival recession than the chamfer.

CONCLUSIONS

Subgingival margins do influence the periodontal soft tissue response. Statistically significant difference exists between feather edge and chamfer finishing lines in regard to bleeding on probing and gingival recession.

CLINICAL RELEVANCE

Subgingival margins should be carefully selected, especially when feather edge finishing line is utilized.

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.

Evaluation of a novel compule-based gingival retraction system in UK general dental practices

Twelve members were selected at random from the PREP panel, a group of UK-based dentists who are prepared to carry out research in their practices. A questionnaire was designed to determine the views of the participants, who were asked to use the retraction paste capsules where clinically indicated. They were asked to return the questionnaire after 8 weeks and the information contained therein was collated and presented mainly on visual analogue scales (VAS). A total of 160 impressions were taken using the Astringent Retraction Paste (3M ESPE, Seefeld, Germany) plus use in the placement of 25 restorations. Of evaluators, 83% (n = 10) agreed that Astringent Retraction Paste was a suitable product for gingival retraction and 75% (n = 9) agreed that it had good haemostatic properties. Overall dispensing and handling of the paste was rated as 4.9 on a VAS scale where 1 = Inconvenient and 5 = Convenient. The viscosity of the paste was rated as 3.6 on a VAS where 1 = too thin and 5 = too thick. Good scores were achieved across all criteria for the product. Clinical Relevance: Practitioners may wish to be aware of a novel compule-based gingival retraction system.

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.

Efficacy of two gingival retraction systems on lateral gingival displacement: A prospective clinical study

PURPOSE

Gingival management is a substantive procedure in fixed dental prosthesis treatment. Various new retraction cord systems are available and used. This study aimed to compare the efficacy of a new retraction cord (Stay-Put, Coltene Whaledent AG) and a conventional retraction cord (Ultrapak, Ultradent Products Inc., South Jordan, Utah) on lateral gingival displacement in continuation with the treatment protocol of the subjects fixed dental prosthesis for various partial edentulous conditions requiring fixed dental prosthesis.

METHOD

Thirty subjects were selected who needed bilateral fixed dental restoration. In selected subjects both gingival retraction cords were placed bilaterally buccolingually by simple randomization method. After removing the cords, impressions were made and undamaged definitive casts were retrieved. The abutment teeth were sectioned buccolingually at the buccal ridge followed by decimal measurement of the width (in millimeter) of the retracted gingival sulcus, under a traveling microscope.

RESULTS

Data was analyzed using SPSS version. Paired "t" test was used to compare the difference between the displaced gingival width in two retraction group (p > 0.05).

CONCLUSION

Although mean gingival retraction in Stay-Put system (0.528 ± 0.12 mm) was higher as compared to that in Ultrapak (0.487 ± 0.10 mm), the difference between the two systems (0.041 ± 0.11) was not significant statistically (p = 0.057).

Evaluation of efficacy of different gingival displacement materials on gingival sulcus width

AIM

The purpose of the present in vivo study was to measure the efficacy of different gingival displacement materials in achieving gingival tissue displacement and to compare the efficacy of Expasyl displacement paste (Pierre Rolland, France) and gingival displacement cord for gingival displacement.

MATERIALS AND METHODS

Sixteen subjects were included in the study. Premolars were prepared to receive full veneer crown, gingival displacement was carried using gingival retraction cord and gingival displacement paste. Impression of the gingival sulcus was made. Sulcus width after displacement was measured under magnification.

RESULTS

The mean displacement value of sulcus width was 0.21 ± 0.01 mm for the gingival retraction cord and 0.26 ± 0.02 mm for the gingival displacement paste. 'F' test was used for statistical analysis. Difference among the two test agents was statistically significant (p < 0.01).

CONCLUSION

Gingival displacement paste showed better response in achieving horizontal displacement of the gingival sulcus than gingival retraction cord.

CLINICAL SIGNIFICANCE

Gingival displacement helps in recording the unprepared tooth surface adjacent to the finish line in the impression being made, thereby helping a better marginal adaptation and emergence profile in the extracoronal restoration.

Effect of retraction materials on gingival health: A histopathological study

Background:

Gingival retraction methods are used in dentistry for impressions of subgingival crown margins, such as, mechanical, chemical, chemicomechanical, and surgical. These methods may injure the gingival sulcular epithelium. Hence, the present study is carried out to evaluate the effect of different retraction materials, such as, Expasyl, Magic Foam Cord, and impregnated retraction cord on the gingival sulcular epithelium.

Materials and Methods:

This study included 30 cases of bilateral premolar extraction patients with Loe and Silness gingival index zero. Retraction materials were kept in the dry, isolated labial gingival sulcus for the required time. The retraction materials were removed by rinsing with water. Retracted gingiva of 2 – 3 mm from the gingival margin along with the tooth was extracted and the decalcified sections were microscopically studied. Data analysis: Data were analyzed by applying the chi-square test.

Results:

This study showed better results with retraction paste as compared to the retraction cord, and there was a significant association between retraction materials and the relative degree of injury to the sulcular epithelium.

Conclusion:

There is a significant association between retraction materials and gingival sulcular epithelium. It can be stated that impregnated retraction cord, may be used commonly but it needs proper tissue manipulation and is technique sensitive. Newly advanced material in the form of retraction paste like Expasyl or Magic Foam Cord was found to be better than cord as assessed histologically, it respects periodontium.

A clinical study on the effects of cordless and conventional retraction techniques on the gingival and periodontal health

AIM

To investigate the influence of two cordless techniques on the periodontium in comparison with conventional cords.

MATERIAL AND METHODS

Dental students (n=60) with healthy gingival conditions were recruited - an expanding poly vinyl siloxane material (Magic Foam Cord), a paste-like material (Expasyl), and a conventional retraction cord (Ultrapak) were applied on the buccal aspects of three premolars of each subject. Probing depth, clinical attachment level, gingival index (GI), plaque index, mobility, bleeding, and sensitivity were assessed at baseline, and at 1 and 7 days after application. Data were analysed using Kruskal-Wallis and Mann-Whittney tests (alpha=0.05).

RESULTS

The periodontal parameters were not statistically significant among the groups at all time intervals except for the GI, which was increased for all groups after 1 day. The highest was in Expasyl (p=0.011). After 7 days, the GI returned to a non-significant level compared with baseline except for Expasyl, which was still significant (p=0.044). Expasyl induced sensitivity in four subjects. Bleeding was only induced by Ultrapak in 28.3% and 26.7% during and after retraction, respectively.

CONCLUSIONS

All techniques caused a temporary gingival inflammation; the greatest was in Expasyl, which also showed slower recovery. Cordless techniques did not induce bleeding during or after retraction.

Gingival retraction techniques for implants versus teeth: current status

BACKGROUND

The authors reviewed and compared gingival retraction techniques used for implants and teeth.

TYPES OF STUDIES REVIEWED

The authors searched the literature using article databases Ovid MEDLINE up to May 2008, PubMED and Google Scholar (advanced search) and the following search terms: gingival retraction, implant abutment, impressions, cement-retained implant restoration, impression coping, peri-implant tissue, emergence profile and tissue conditioning.

RESULTS

The authors found insufficient evidence relating to gingival displacement techniques for impression making for implant dentistry. Gingival retraction techniques and materials are designed primarily for peridental applications; the authors considered their relevance to peri-implant applications and determined that further research and new product development are needed.

CLINICAL IMPLICATIONS

The use of injectable materials that form an expanding matrix to provide gingival retraction offers effective exposure of preparation finish lines and is suitable for conventional impression-making methods or computer-aided design/computer-aided manufacturing digital impressions in many situations. There are, however, limitations with any retraction technique, including injectable matrices, for situations in which clinicians place deep implants.

Dose-related effects of epinephrine on human gingival blood flow and crevicular fluid production used as a soaking solution for chemo-mechanical tissue retraction

STATEMENT OF PROBLEM

Epinephrine is a frequently used agent for impregnation of the retraction cord. Removal of retraction cord from the gingival sulcus has been shown to elicit a hyperemic response that could be prevented by epinephrine. However, the epinephrine may cause local or systemic adverse effects in the circulation.

PURPOSE

The aim of this study was to identify the effective concentration of epinephrine that may prevent the hyperemic response and consequently keep the crevicular fluid production low after cord removal without local or systemic side effects.

MATERIAL AND METHODS

Seventeen healthy human subjects had their crevicular fluid volume and gingival blood flow measured by Periotron and laser Doppler flowmetry, respectively, before and after cord removal at the left maxillary central incisor. The right maxillary incisor served as the control. Retraction cords were presoaked in physiological saline or various concentrations (0.001%, 0.01%, and 0.1% w/v) of epinephrine solution. Double repeated-measures analysis of variance with the Fisher Least Significant Difference post hoc test was used to statistically evaluate the blood flow values (mean +/- SE, alpha=.05), and the Wilcoxon matched pair test was used for crevicular fluid values, given as median (25-75 percentile, alpha=.01).

RESULTS

In the saline group, cord removal resulted in elevated blood flow (140% +/- 11%, P<.001) and crevicular fluid production (300% (130%-470%), P<.05). After cord removal in the 0.01% and 0.1% epinephrine groups, blood flow remained low for the measured period (43%-70%, P<.05). The crevicular fluid production transiently increased in the 0.01% epinephrine group (170% (140%-380%), P<.001), but then returned to baseline level and remained low as for the 0.1% group. No systemic vascular effect was detected in any groups.

CONCLUSION

The prolonged increase in crevicular fluid production and hyperemic response after cord removal can be prevented by application of 0.01% epinephrine solution without systematic changes.

The effect of gingival retraction procedures on periodontal indices and crevicular fluid cytokine levels: a pilot study

PURPOSE

The purpose of this study was to examine the effects of placement of retraction cord subgingivally upon periodontal indices including plaque index (PI), gingival index (GI), pocket depth (PD), bleeding on probing (BOP), and attachment level (AL), as well as gingival crevicular fluid (GCF) and TNF-alpha levels.

METHODS

Ten teeth in 6 patients who were periodontally healthy were selected. These teeth had pocket depths of 3 mm or less, no evidence of significant loss of attachment, BOP, or plaque accumulation. The patients each received an oral prophylaxis. The following week, baseline measurements of periodontal indices and TNF-alpha were taken and the retraction cord was placed for 15 minutes. Following removal, the patients were dismissed. The periodontal indices measured included PI, GI, PD, BOP, and AL. In addition, the levels of TNF-alpha in GCF, were investigated. These measurements were made before gingival retraction as a baseline and on the 1st, 3rd, 7th, 14th, and 28th days post retraction.

RESULTS

A repeated measures ANOVA showed that TNF-alpha levels in GCF were significantly increased at all five intervals after gingival retraction compared to the baseline. The mean TNF-alpha level peaked at Day 1 (0.90 +/- 0.62), then declined at Days 3 (0.53 +/- 0.16), 7 (0.43 +/- 0.08), 14 (0.47 +/- 0.10), and 28 (0.43 +/- 0.08) but was still elevated 54% above baseline at Day 28, p < 0.01. The GI was significantly elevated at Day 1 (0.9 +/- 0.49), p < 0.01; Day 3 (0.53 +/- 0.32); and Day 7 (0.33 +/- 0.33), p < 0.05. Unlike TNF-alpha, GI recovered to the baseline by day 14. Other periodontal parameters, PI, PD, BOP, and AL were not significantly altered by the gingival retraction procedure.

CONCLUSION

This pilot study supports the previous research that gingival retraction causes an acute injury that heals clinically in 2 weeks as is indicated by the GI. It also provides the first evidence that gingival retraction results in an elevation of the proinflammatory cytokine, TNF-alpha, in GCF.

Cytotoxic effects of gingival retraction cords on human gingival fibroblasts in vitro

The objective of this study was to determine the cytocompatibility of three different extracts of gingival retraction cords and to compare the cytotoxic effect of these materials on human gingival fibroblasts. Gingival retraction cords impregnated with aluminium sulphate (Gingi-Aid), dl-adrenaline HCl (Gingi-Pak) and non-drug-impregnated cord (Gingi-Plain) were eluted with culture medium for 10 min and 24 h. Cytotoxicity was judged using a tetrazolium bromide reduction assay. Our data demonstrated that gingival retraction cords applied alone almost completely inhibited cell viability (P < 0.05). In addition, the results also showed that the eluates from aluminium sulphate-impregnated cord, dl-adrenaline HCl-impregnated cord and non-drug-impregnated cord were cytotoxic to primary human gingival fibroblast cultures (P < 0.05). The cell viability of incubation of gingival fibroblasts containing 10-min eluates of aluminium sulphate, dl-adrenaline HCl and non-drug-impregnated cord was 61, 21 and 70%, respectively. The cell viability of incubation of gingival fibroblasts containing 24 h eluates of aluminium sulphate, dl-adrenaline HCl and non-drug-impregnated cord was 68, 58 and 72%, respectively. It was found that dl-adrenaline HCl-impregnated gingival retraction cord was the most toxic gingival retraction cord among the materials tested in all cultures (P < 0.05). The cytotoxicity decreased in an order of dl-adrenaline HCl-impregnated cord > aluminium sulphate-impregnated cord > non-drug-impregnated cord. The extent or degree of the cytotoxicity depended on the materials tested. Gingival retraction cords have significant potential for gingival toxicity. Careful management of gingiva retraction cords would lower the risk of potential gingival tissue damage during clinical application procedure and thus increase the success of prosthodontic procedures.

Effect of different crown contours on periodontal health in dogs. Clinical results

OBJECTIVES

The aim of this study is to evaluate clinically the effect of different crown contours on the periodontium in beagle dogs.

METHODS

One month after commencing oral hygiene procedures the second and third premolars in three quadrants of four adult beagle dogs were prepared for receiving crowns. The unprepared second and third premolars in one quadrant served as controls. Crowns with three different emergence profiles (normal (=tooth) contour, 30 degrees and 50 degrees over-contour) were cemented where one quadrant received the same treatment. Clinical parameters were recorded on all four sites (mesial, buccal, distal and lingual) of test and control teeth at baseline, after 3 and 5 months. During the entire study period, professional oral hygiene was performed seven times a week.

RESULTS

The Plaque Index increased for the 30 degrees and 50 degrees over-contour groups, although no statistically significant differences could be observed. For the normal contour and control group minor changes occurred. Similar results could be depicted for the Gingival Index. The changes regarding the variables Plaque and Gingival Index were correlated to the Gingival Crevicular Fluid Flow. Here, significant differences for the Gingival Crevicular Flow were observed between the treatment groups and over the treatment period for the 30 and 50 degrees over-contour groups. Only slight differences for this parameter were observed in and between the control and normal contour groups. In the control group, the Pocket Probing depth remained stable during the entire study but increased in the crowned treatment groups over time. At 3 and 5 months the probing depth was significant greater in the 30 degrees and 50 degrees over-contour groups compared to the control group. There was a higher loss of clinical attachment levels for the test groups than for the control group. There were statistically significant differences at each timepoint between groups and also within groups except for the control group.

CONCLUSIONS

Within the limits of this study it can be concluded that over-contoured subgingival crowns seem to affect clinical periodontal health only slightly in dogs over 5 months when an intensive oral hygiene regimen is executed.

Electron microscopic analysis of the effects of chemical retraction agents on cultured rat keratinocytes

STATEMENT OF PROBLEM

Chemical retraction agents used in fixed prosthodontics for temporary displacement of free gingival tissue before impression making can cause injury to the gingival tissue cells.

PURPOSE

This study evaluated changes in cultured rat keratinocytes treated with 2 chemical agents used for gingival retraction. Treated cultures were compared with untreated cultures.

MATERIAL AND METHODS

Keratinocytes of rat gingiva were grown in a specific medium for 10 days. After treating 1 group of specimens with 0.05% tetrahydrozoline and another group with 25% aluminum chloride, both for 10 minutes, the cultured cells were examined with scanning and transmission electron microscopy and compared with control specimens.

RESULTS

Twenty-five percent aluminum chloride produced a significantly greater extent of cellular damage than 0.05% tetrahydrozoline, which caused only mild changes in the cultured cells.

CONCLUSION

On the basis of the morphologic and ultrastructural changes in primary cell cultures of rat keratinocytes observed in this study, it was concluded that 25% aluminum chloride was significantly more aggressive than 0.05% tetrahydrozoline.

Clinical trial of gingival retraction cords

STATEMENT OF PROBLEM

A wide spectrum of different gingival retraction cords is used, while the relative clinical efficacy of these cords remains undocumented.

PURPOSE

This study aimed to determine whether clinicians were able to identify differences in clinical performance among 3 types of gingival retraction cords.

METHODS AND MATERIAL

Dental students and faculty members ranked pairs or series of cords according to 6 criteria for clinical performance, with a blind experimental study design. Cords differed in consistency (knitted or twined) and impregnation (8% dl-epinephrine HCl, 0.5 mg/in or 25% aluminum sulfate, 0.5 mg/in).

RESULTS

Knitted cords were ranked better than twined cords (P =.03). Cords containing epinephrine performed no better clinically than aluminum sulfate cords (P >.05).

CONCLUSION

Clinicians were unable to detect any clinical advantages of using epinephrine impregnated gingival retraction cords compared with aluminum sulfate cords.

Tissue management with a new gingival retraction material: a preliminary clinical report

A new retraction material (Merocel) was evaluated in a clinical trial with 10 selected abutments. Each selected abutment required an anterior single unit. A comparison of probing attachment level, bleeding on probing, and plaque index demonstrated highly successful periodontal maintenance. The main advantage of Merocel retraction material is that it is capable of innocuously expanding the gingival sulcus. This preliminary study suggested that a Merocel strip was a predictable retraction material in conjunction with impression procedures. The material was also evaluated by scanning electron microscopy and demonstrated promise in this investigation. The Merocel strip shows potential for other applications, but limitations of this material indicated that evolution of atraumatic gingival retraction should continue.

A method to position replacement dies accurately on a fixed partial denture master working cast

Impressions are often remade because of insufficient detail in one of many preparations. These impressions may be salvaged with a replacement die procedure. Some transfer or replacement die procedures fail to position the dies accurately; other procedures involve many steps in the fabrication of copings. This article describes a method that quickly and accurately positions a replacement die in a fixed partial denture master working cast.

A procedure for making fixed prosthodontic impressions with the use of preformed crown shells

Void-free impressions of tooth preparations for fixed prosthodontics are essential for accurately fitting restorations; however, commonly used impression methods are arduous and time-consuming. A procedure has been developed in which an impression is made in a preformed temporary crown shell for each tooth preparation and then a final over impression is made. The result is an atraumatic and uncomplicated complete-arch impression that incorporates an accurate impression of each prepared tooth.

Nontraumatic final impressions for fixed partial dentures

A nontraumatic, nonretraction impression technique is presented which uses the fabrication of an acrylic resin shell from an interocclusal wax impression. A crucial step in the procedure is obtaining the complete finish line of the preparation within the resin. This tray, which is filled with an elastomeric impression material, is combined with a triple tray of the same material to provide all the necessary relationships to construct a crown or coping. This procedure is especially efficient for multiple abutments during fixed partial denture construction.

Periodontics and prosthodontics: goals, objectives, and clinical reality

Prosthodontics and periodontics are collaborative disciplines. A successful prosthesis depends on a healthy periodontal environment, and periodontal health depends on the continued integrity of the prosthodontic restoration. To facilitate this collaboration, prosthodontists should not only appreciate the periodontic implications of gingival displacement procedures and tooth preparation, but should be knowledgeable about the types of gingival tissues, osseous topography, occlusal effects, and their implications for abutment choice. Working as a team, the periodontist can identify for the prosthodontist a patient's periodontal strengths and limitations. In that way, the prosthodontist can then assume responsibility for a given treatment plan based on a mutual understanding of the critical factors involved.

Dies with resin copings for accurate registrations

A simple, accurate, and reliable technique is available for use when individual dies are made for fixed partial denture construction. Resin copings are used to record the spatial relationship between abutments, create occlusal registrations, verify the dimensional accuracy of the dies, test the path of insertion of the prosthesis, and visualize the marginal adaptation of the retainers. The resin copings are compatible with any elastic impression material selected for the pickup impression.

Electrosurgery--a biological approach

Electrosurgery has been used in dentistry for more than 50 years. Both opponents and advocates of electrosurgery have presented a variety of clinical studies in favour of their respective opinions, which are discussed in the following review. In some studies, wounds created by electrosurgical techniques were observed through the healing stages, in comparison to those following incision by a surgical blade, with no significant difference being discovered. Other studies reported that the histologic response of oral connective tissue to electrosurgery was adverse in some animal and human models. However, neither of these groups used methods that allowed documentation or control of operating variables. A critical evaluation of controlled clinical studies shows that adverse responses of (connective) tissue, epithelium, bone, cementum, and periodontal attachment are related to an excessive lateral heat production during the procedure. With electrosurgery, the clinician can control the inherent variables. Waveform, frequency, size of the electrode, time of contact and cooling periods are some of those considered to be of importance in the studies. On the basis of the research reports, clinical guidelines have been developed to give practical advice to the clinician using electrosurgery. Providing that these safeguards are adhered to, scientific evidence supports the biological compatibility of electrosurgery for intraoral surgical procedures.

Tissue displacement methods in fixed prosthodontics

The various methods to accomplish gingival displacement have been described. The techniques have been noted and their relative advantages and disadvantages summarized. The practicing dentist can use this review to make better informed decisions regarding the method he or she chooses for the treatment of a particular patient.

Comparative study of gingival retraction methods

The effects of electrosurgery, retraction cord, and the rotary gingival curettage technique were tested clinically and histologically in dogs. Postoperative periods analyzed ranged from 6 hours to 14 days. All methods induced some kind of minor damage. Recession of clinical magnitude was induced only by rotary gingival curettage. Apical migration of the junctional epithelium was not seen.

A comparison of gingival inflammation related to retraction cords

Potassium aluminum sulfate, aluminum chloride, and 8% racemic epinephrine did not demonstrate practical differences, although potassium aluminum sulfate produced fewer inflammatory changes than the other agents. 2. It appears that factors other than the chemical agent (e.g., physiologic differences in patients) may play a role in the amount of gingival inflammation induced. 3. Additional studies using a larger sample size and an untreated control site should be undertaken.