An accurate impression is an essential procedure for fabricating indirect fixed restorations as well as ensuring the final success rate of the prostheses. 1, 2, 3 To achieve an accurate dental impression, management of gingival tissue is an important step, especially in challenging cases where the finish line is located equigingival or subgingival. 2, 3, 4, 5
To achieve an accurate result, the impression should have adequate thickness to prevent the tearing of the material once the impression is removed. This can be achieved by having a proper finish line and good gingival management. 1, 2, 6 Inaccurate impressions can cause several problems, such as misfitting of the final restoration, which might result in plaque accumulation. Plaque accumulation is the main causative factor for gingival inflammation and caries, which can result in the failure of the restoration or even the extraction of the tooth. 1, 4, 6 7, 8
Gingival displacement (GD) is defined as the deflection of the marginal gingiva away from a tooth. 3, 9 This creates lateral and vertical spaces that are primordial to expose subgingival margins and to ensure the presence of an adequate bulk of injected impression material in the expanded gingival crevice. A sulcular width of at least 0.2 mm is mandatory to prevent tearing of the impression materials. 10 Additionally, GD helps in controlling hemorrhage and achieving hemostasis to ensure proper isolation for hydrophobic impression materials as well as when placing adhesive restorations. 2,3 An ideal GD technique should retract the gingiva temporarily and atraumatically as much as possible while achieving adequate homeostasis. 2 Clinicians have been using different techniques for GD, such as mechanical, chemical, surgical, or a combination of the aforementioned.
The mechanical technique involves the use of retraction cords to displace gingival tissues. Retraction cords can either be used alone or in combination with hemostatic or vasoconstrictor agents to achieve hemostasis. 11, 12 Using gingival retraction cords along with specific hemostatic medicaments is considered one of the most widely used techniques to displace the gingiva. 6 On the other hand, retraction cords can sometimes cause gingival bleeding and discomfort to the patient in the absence of anesthesia and are considered time-consuming. 3, 11, 12 Furthermore, improper use of the retraction cord can lead to trauma and/or gingival recession, which can interfere with the outcome. 13, 14 Nevertheless, the placement of retraction cords represents an inexpensive, simple, and widely used technique for gingival displacement. 1, 4, 15, 16 Retraction cords comes in different forms; twisted, braided, and knitted. Depending on the clinical situation, it may be applied as a single- or double-cord technique.2
Retraction cords were made with hemostatic chemicals to help with hemostasis and to have a temporary local effect. Unfortunately, these chemical substances could react with some impression materials and cause unfavorable side effects such gingival irritability and discoloration. 11 It has been shown that the use of epinephrine as a GD medicament can cause significant systemic side effects. 2 17 Furthermore, epinephrine is contraindicated in patients with cardiovascular diseases such as hypertension, hyperthyroidism, and diabetes; therefore, it is not used routinely as a hemostatic medicament in dental clinics. 2 Other types of hemostatic agents like aluminum sulfate, aluminum potassium sulfate, aluminum chloride, and ferric sulfate are considered valuable alternative agents to be used instead of epinephrine. They are considered clinically safe as they do not cause significant systemic side effects. 2, 4, 17
Recently, chemical retraction techniques were introduced in an attempt to overcome the disadvantages of conventional retraction cords. 1, 11, 15 Retraction paste is considered a less traumatic technique to achieve satisfactory gingival displacement. 4, 12 Currently, many materials are present in the market; one widely used is Expasyl Paste (KerrCorp, Orange, CA), which consists of kaolin and aluminum chloride. The material depends on the hygroscopic expansion of kaolin that occurs upon contact with the crevicular fluid, combined with the hemostatic activity of aluminum chloride, the displacement of the gingiva occurs in 2–4 minutes according to the manufacturer.3 Magic Foam Cord (Coltene Whaledent AG, Altstatten, Switzerland) is another material that uses polyvinyl siloxane as an expanding medium in conjunction with the mechanical pressure exerted by Compre-Caps, to achieve gingival retraction. 15 Traxodent Hemodent Paste (Premier Dental Company, Plymouth Meeting, PA) is also comprised of 15% aluminum chloride topical paste along with cotton caps. 15 In summary, cordless techniques, while causing less discomfort to the patient, are considered less invasive and less time-consuming when compared to conventional retraction cords.4, 12 18 From another perspective, since retraction paste systems depend on their expansion property upon contact with crevicular fluids, they might not give enough displacement in cases of deep sulcus. 4, 12, 19 A randomized clinical trial investigated the GD using three different paste systems and reported a mean sulcular gingival width of (0.644 ± 0.22) in the Traxodent group, followed by the Expasyl group (0.590 ± 0.11), and the Magic Foam Cord group (0.528 ± 0.01). 20
Regardless of all the attempts to compare the efficiency of gingival cords and paste systems, it is still believed that there is no technique with a superior success rate, and the choice of technique depends on the clinician’s preference. 1, 4, 11, 13, 15 Reviewing the literature does not reveal any evidence concerning the knowledge and preference regarding mechanical GD methods among dentists. This study was conducted with the aim of evaluating the use of two different techniques among group of dental clinicians and the associated knowledge and technique preferences.