Periodontics and Prosthodontics Open Access

Keywords

Periodontal health; Gingival retraction; Gingival tissue; Dental prosthesis

Introduction

An accurate impression is obtained for the fabrication of fixed restorations only when the gingival tissue is managed properly. And this is especially true when the location of the finish line is at, or within, the gingival sulcus [1-4] or with restoration of cervical lesion because of its proximity to the gingival tissues [5].

The deflection of the marginal gingiva away from the tooth is the definition of gingival displacement. This procedure is performed to create sufficient space between the finish line of the preparation and the gingival tissue to allow for the placement of adequate amount of impression material into the expanded gingival crevice [6-9]. Gingival retraction is an important aspect of currant impression techniques in fixed prosthetic procedures [10]. Effective gingival retraction prior to taking an impression without damaging periodontal tissues is very important in longterm success of cast restorations [11].

This is especially important when using materials that do not displace the gingival tissues such as hydrophobic impression materials [12]. Gingival tissues usually return to their original position because of the gingival cuff elasticity and the rebound forces of the compressed adjacent attached gingiva [13]. Sulcular width is very crucial to the accuracy of the impression, it has been reported that approximately 0.15-0.2 mm is the significant Sulcular width for an Impressions without voids, tearing and high marginal accuracy [4,14-16].

Different types of retraction techniques are available such as; mechanical, chemical or surgical, and they are frequently used in combination. The most widely used method by 98% of the prosthodontists is the retraction cords they are mechanical form of retraction [17]. They are predictable, effective, and safe compared to rotary gingival curettage and electrosurgery [8,17]. Retraction cord offers a fast and inexpensive retraction method, using either a single-cord or a double-cord technique. To ensure a meticulous impression with adequate biological width, the double-cord technique is used where two cords of different sizes are used. The technique is safe and effective, given that the periodontal health is good. With the single-cord technique, a single retraction cord is placed in the sulcus [18].

The use of gingival retraction cord is technique-sensitive and requires expertise. Difficulty in placing the retraction cord has been reported in the literature, in addition to gingival bleeding, patient discomfort and root sensitivity [10]. And when inappropriately manipulated varying degrees of tissue trauma may result, it can lead to epithelial attachment damage and/or exacerbating gingival recession, bleeding and bone resorption [10,18-21]. Retraction cords can be used with haemostatic agents or without. Various haemostatic agents with varying degrees of safety and effectiveness are available such as aluminium potassium sulphate (Alum), aluminium chloride, epinephrine, zinc chloride, ferric sulphate and sympathomimetic amines.

Another type for mechanical retraction is the cordless retraction techniques. It has many claimed advantages, such as less time consuming; enhanced patient comfort in addition, is considered minimally invasive. An example is Expasyls (Kerr Corp., Orange, CA, USA). It is a paste-like retraction material. The main ingredients has haemostatic properties (aluminium chloride) and hygroscopic expansion (kaolin) when it comes into contact with the crevicular fluid, accordingly it provides mild displacement of the gingiva in about 2 min [22]. Another example is the Magic Foam Cords (Colte`ne Whaledent AG, Altstatten, Switzerland), which is an expanding poly vinyl siloxane material with the advantage of ease of application and the fast retraction of the sulcus without trauma to the gingiva and with shorter time of application compared to the retraction cord [23-25].

The effect of cordless techniques on the gingival and periodontal health is not well documented, as most of the studies are only demonstrations of their clinical use [26-28]. A study by Yang et al. reported no significant difference in achieving gingival deflection when they compared two cordless techniques: Expasyl and Korlex- GRs (Biotech-one, San-Chung, Taiwan) with Ultrapaks cords (Ultradent Products Inc., South Jordan, Utah), however they reported that Ultrapak was more painful and created more gingival recession than the cordless technique [29].

To the best of our knowledge, the effect of retraction cords techniques in comparisons to cordless retraction techniques on gingival health has not been evaluated in a systematic manner. Accordingly, the aim of this review is to collect and evaluate, in a systematic manner, available data on the post-operative effect of retraction cords on gingival tissue in patients with healthy gingiva compared to cordless techniques in respect to effect on gingival recession, parameters of gingival inflammation and patient comfort.

Materials and Methods

Focused question

For patients with healthy gingiva, does retraction cord have a significant harmful effect on gingiva compared to cordless techniques in respect to the clinical parameters of gingival inflammation?

Search strategy

The following electronic databases sources were searched for appropriate articles that satisfied the study purpose from their earliest records to January 2013: the PubMed/MEDLINE, Science Direct, ISI Web of Science, the Cochrane library. This comprehensive search was designed to include any published articles that evaluated the effects on healthy gingiva by the retraction cords and/or cordless technique. To minimize the potential for reviewer bias, the screening was performed independently by two reviewers (NYA and MQR). Disagreement regarding the inclusion or exclusion of the retrieved articles was resolved by a discussion between reviewers until reaching a consensus.

The databases were searched using the following search format; Intervention. <([MeSH terms] retraction cords or Ultrapack or gingival retraction cord or Hemodent gingival retraction cord or Cordless gingival retraction techniques or Expasyl retraction material or Magic Foam Cord or Cordless retraction paste material and ([MeSH terms] gingival health or Gingival Crevicular fluid or Bleeding Index or Gingival Index or [text words] periodontal health> and Outcome. <([MeSH terms] recession or [MeSH terms] bleeding or [MeSH terms] Pocket depth or [MeSH terms] periodontal attachment loss or [MeSH terms] dental plaque index or [MeSH terms] periodontal pocket or [text words] gingival recession or [text words] patient discomfort or [text words] sulcus bleeding or clinical attachment level or bleeding on probing.

Study inclusion and exclusion criteria

Only Studies written in English language were selected by the two authors (NYA and MQR). The selection procedure was as the following; the articles were screened independently by title and abstract, then if the title contains the search key words, the article was selected. However, if the title has none of the key words, the abstract was then read to search for key words.

Articles selected for full text reading were articles that has no clear abstract, but the title seemed to be relevant, or if abstract was not available, but the title contained the key words. The two authors (MQR and NYA) read the selected full-text articles in detail and the articles that fulfilled all selection criteria were processed for data extraction. All reference lists of the selected studies were hand searched by the same authors for additional published work that could possibly meet the eligibility criteria of the review. The studies were analyzed according to the following inclusion criteria: the study 1) involved human adult patients (age ‡ 18 years) 2) clinical trials, prospective studies, and observational studies and 3) patients with healthy gingiva. Only studies that fulfilled all of the inclusion criteria were admitted to the second phase.

In the second phase, the preselected studies were submitted to the following exclusion criteria: 1) patients with systemic diseases, 2) a primary outcome of interest was not analyzed, and 3) insufficient information on the mode of therapy.

Outcome measures

Primary outcome of interest; to address the focused question, the primary outcomes of interest were the pre- and post intervention changes in sulcus depth and the effect on gingival recession.

Secondary outcomes of interest were changes in the gingival index (GI), and GCF levels and content. Adverse events, sensitivity and pain related to the intervention were evaluated as reported by authors.

Data extraction

Was performed by the two authors independently using specially designed data-extraction forms created by the author (NYA) based on quality and methodology checklist for systematic reviews and meta-analyses created by the National Institute for Health and Clinical Excellence [30]. Data on the following issues were extracted and recorded: 1) Title, and year of publication; 2) study design: clinical trial and /or observational study; 3) characteristics of participants: sample size, gender, age and systemic conditions; 4) methodological quality of trials: patient and defect selection bias, adequate inclusion criteria, statistical analysis, randomization selection, validity of conclusions, and clinical variables analyzed; 5) characteristics of interventions and follow ups (Table 1).

Table 1: Self-developed data collection table used to extract data from each article.

Quality appraisal

A quality and methodology checklist for systematic reviews and meta-analyses created by the National Institute for Health and Clinical Excellence [30] was used for every article selected (Table 2). The checklist items included the sample size calculations, randomization methods, inclusion and exclusion criteria, subject follow ups, presence of a comparable control group, presence of masking, and the appropriateness of statistical analysis.

Table 2: Quality assurance checklist by the national institute for health and clinical excellence (January 2009).

Results

Search results

The search strategy identified 85 potentially eligible articles of which 47 articles were excluded after the titles and/or abstracts were reviewed. Subsequently, the full texts of the remaining articles that were considered potentially relevant were screened. From the 38 articles, 33 of them did not meet the criteria of eligibility. Therefore, 5 articles were finally included.

Reasons for exclusion of full-text articles include the following: 1) Gingival retraction cord is not a variable in the study; 2) the effects of the retraction material was not measured clinically; 3) Review articles and case reports; 4) Presence of a contradictory factor.

Analysis of included studies

Description: The five studies included in this review are presented in Tables 3 and 4, it included 4 randomized clinical trials (RCT) [11,29,31,32] and 1 [33] Pilot clinical studies. These 5 studies were performed in 5 different countries (Iran, Taiwan, Germany, Jordan, and Turkey) and were published from 2000 to 2012.

Table 3: Description of all the included studies.

Table 4: Intervention and outcome of the included studies.

From these five studies the following was reported; Yang et al. [29], compared 3 material (Epinephrine-impregnated cord (Ultrapak1), Injection-type material with 15% A1C13 (Expasyl) and Injectiontype material with 0% A1C13 (Korlex-GR). They reported that there is a significant increase in the sulcus width >0.2 mm after retraction by all the 3 materials also there is significant gingival recession (p<0.05) however, Ultrapak 1^® produced the greatest amount of recession and was also significantly more painful compared to the other 2 materials (p<0.05). Also Wöstmann et al. [31], reported that there is increase in the crevicular fluid flow when pure cotton retraction cords were used, however with the use of both chemo-mechanical and chemical retraction cords a significant reduction in the crevicular fluid was observed. Another study by Al Hamad et al. [32] also compared Ultrapack knitted non-impregnated retraction cord with Magic foam cord and Expasyl, and they reported that except for the GI, the periodontal parameters were not statistically significant among the groups at all time intervals, which was increased for all groups after 1 day. The highest was in Expasyl. After 7 days, the GI returned to a nonsignificant level compared with baseline except for Expasyl, which was still significant. Expasyl induced sensitivity in four subjects. Ultrapak only induced bleeding during and after retraction. And they concluded that all techniques caused a temporary gingival inflammation; the greatest was in Expasyl, which also showed slower recovery and that cordless technique did not induce bleeding during or after retraction. However in 2009, Kazemi et al. [11], when compared Plain cord (Ultrapack knitted RC#1 Ultradent) pre-saturated with 15% aluminum chloride solution to Expasyl paste reported that the mean width of the retracted sulcus in the pre-saturated cord group was greater than Expasyl paste group and that the mean gingival recession in the cord group was significantly greater than Expasly paste group. Also the inflammation score was significantly higher in the cord group compared to the paste group, in 7^th day and 14th day. And they concluded that the gingival retraction with Expasyl paste method caused less injury to gingival tissues than impregnated cord. In 2012, Bet al. [33] When they compared the effect of gingival retraction cord pre-saturated with potassium-aluminumsulfate to Expasyl paste and Korlex-GR paste retraction materials suggested that on a periodontaly healthy subjects the well fitted fixed dental prosthesis and its procedures has no negative effect on the periodontal tissue health.

Population: Three of the included studies were conducted in university hospitals and one in dental practice. One study failed to mention the location of the study. Sample sizes ranged from 8 to 60 subjects, however one study used number of teeth (340 prepared teeth) regardless of the number of patients. All participants were healthy patients.

Age of participants: The age of the participants was (>20 years old). However, one study failed to report any information on the age of the participants [31]. 4 studies reported age ranges [11,29,32,33]. One studies reported age range of 21-48 years old [11], a study reported 28-72 years [33], and two studies reported 25-29 years [29,32].

Duration: The majority of the studies included were short-term clinical studies, which either finished after sampling or lasted one month. In one study impressions were made before retraction, immediately after retraction, and 14 days after retraction [29], in the another study 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 [32], however, in Kazemi [11] study the widths of gingival sulcus were measured by a jig in 4 phases, 0, 7, 14 and 28 days. The gingival index was evaluated in the 4 phases as well. The Gingival crevicular fluid (GCF) samples were collected before starting the fixed dental prosthesis treatment and repeated on days 2, 3, 7 and first month after cementation. In the study by Tolga [33], the Gingival Crevicular fluid flow was measured before and directly after the removal of the individual retraction material [31].

Quality analysis: Most included studies in the review presented a proper sample-size calculation that were reported and confirmed except in 1 study [31]. Randomization methods were considered possibly adequate in 4 studies [1,29,31-33], and clearly adequate in one study [11]. In the other hand, all studies compared their experimental results to a control group in a clearly adequate method [11,29,31-33]. In addition, appropriate statistical analyses were done in all included studies. Quality characteristics of each study are presented in Table 5.

Table 5: Quality evaluation of all the studies.

Discussion

Systematic reviews have rapidly gained an important place in supporting clinical decision-making in medicine; however, dentistry has been somewhat slower to adopt this approach. The objective of a systematic review is to present a complete and modern assessment of research using transparent methods while intending to reduce bias. If such situations are met, there should be greater certainty in the conclusions of the appraisal than in other summaries of clinical evidence.

Effective gingival retraction prior to taking an impression without injuring the periodontal tissues is very significant in the longterm success of cast restorations. The gingival crevice normally is about 2 mm in depth accordingly, it should be treated with care, thus, a conservative approach should be used to expose the tooth margins and control bleeding, and in the same time do not cause detachment or injury of the tissue. Different techniques have been used for this purpose [17]. Gingival retraction techniques have been classified as mechanical, chemical, surgical or a combination. The most widely used technique of gingival displacement is a chemomechanical technique, saturating the gingival retraction cords with specific hemostatic medicaments [4].

The available data on the post-operative effect of retraction cords on gingival tissue in patients with healthy gingiva compared to cordless techniques in respect to effect on gingival recession, parameters of gingival inflammation and patient comfort are very limited and after a thorough revision of the literature only 5 articles addressed this issue in a comparative matter.

Although Yang et al. [29], reported that there is a significant increase in the sulcus width >0.2 mm after retraction by the three materials (Ultrapak1), (Expasyl) and (Korlex-GR) with significant gingival recession, however, they reported that the Ultrapak 1^® produced the greatest amount of recession and was also significantly more painful compared to the other 2 materials. This was also true in the report by Kazemi et al. [11], When they compared (Ultrapack knitted RC#1 Ultradent) pre-saturated with 15% aluminum chloride solution to Expasyl paste where they found that the mean width of the retracted sulcus, the mean gingival recession and the inflammation score was significantly higher in the pre-saturated cord group compared to the paste group. However, on the contrary Wöstmann et al. [31], reported that there is increase in the crevicular fluid flow only when pure cotton retraction cords were used, but with the use of both chemo-mechanical and chemical retraction cords a significant reduction in the crevicular fluid was observed. Also, Al Hamad et al. [32] when compared Ultrapack knitted non-impregnated retraction cord with Magic foam cord and Expasyl, reported that GI only increased for all groups after 1 day and Expasyl was the highest. However the GI returned to a non-significant level after 7 days compared with baseline except for Expasyl.

Accordingly, although some previous histological studies [17,20,21] demonstrated that placement of the pre-saturated cord with various retraction medicaments caused a different degree of gingival inflammation, and other clinical studies found that gingival retraction with plain cord, produced acute injury [10,31]. However, all of these studies has reported either that the histological appearance has returned to its normal condition in 3-24 days or that the clinical picture has returned to it’s normal condition in 2 weeks as indicated by the gingival index and/or GCF.

In conclusion, cordless retraction techniques in comparison to pre-saturated cord are associated with less gingival recession and inflammation although both can provide good gingival retraction. It should be also clear that although most of the retraction techniques can produce some type of gingival inflammation nevertheless, it is temporary in nature and tissue will return it is healthy condition especially if the biological width was not violated and the patients has a healthy periodontium to start with.

Author Contributions

As this is a systematic review all authors had contributed equally in reaching to the concept of the research, analysis, interpretation, critical revision of the article, approval of the articles included. Summarization of the articles was equally distributed as well. In writing the manuscript all authors participated equally in each part of the manuscript.

Conflict of Interest

The authors declare that they have no conflicts of interest.

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