The Impact of Retraction Cords on the Gingival Margin Level.

The Impact of Retraction Cords Used in Fixed Prosthodontics on the Gingival Margin Level in Humans: A Clinical Study.

The purpose of this study is to examine the relationship between placing specific retraction cord for different periods of time and the post-operative gingival margin level in humans. Determining the amount of immediate reversible and delayed irreversible gingival recession (vertical gingival retraction) that might happen after placing a retraction cord around a natural tooth in healthy humans. It also aims to investigate the impact of mechanical and chemo-mechanical gingival retraction on periodontal health.

Dental impression is the communication tool between the dentist and the dental technician during the fabrication of fixed dental prosthesis, capturing a precise impression of the prepared tooth and the finish line is mandatory to ensure the perfect fitting of the final prosthesis. Atraumatic gingival displacement is performed to provide sufficient both lateral and vertical space between the finish line and the gingival tissue that will allow recording adequate amount of unprepared tooth structure with the least distortion of impression material as well as minimal damage to attachment apparatus of the tooth as maintaining a healthy periodontium is an important factor in the survival of any fixed prosthesis. The gingival recession that might happen after soft tissue displacement may jeopardize treatment success in esthetic areas of the mouth. Knowledge about the soft tissue reaction to one of the most common gingival displacement methods (retraction cords) is critical yet limited. Also, there is a gap in knowledge about the safety of retraction cords when used for multiple teeth preparations and would then be left in the sulcus for an extended amount of time, as well as the potential harm they can do in terms of persistent gingival recession. The purpose of this study is to examine the relationship between placing specific retraction cords for different periods of time and the post-operative gingival margin level in humans. Determining the amount of immediate reversible and delayed irreversible gingival recession (vertical gingival retraction) that might happen after placing a retraction cord around a natural tooth in healthy humans. It also aims to investigate the impact of mechanical and chemo-mechanical gingival retraction on periodontal health. This clinical study is expected to be useful for dental clinicians who use retraction cords during restorative procedures (cervical composite restorations) or for fixed prostheses; awareness about the amount of transient and permanent gingival recession that could occur is important to avoid undesirable effects such as esthetic issues and/or sensitivity.

Non impregnated gingival retraction cord will be placed around the prepared tooth and left for less than 10 minutes.

Non impregnated gingival retraction cord will be placed around the prepared tooth and left for more than 10 minutes.

Impregnated gingival retraction cord will be placed around the prepared tooth and left for less than 10 minutes.

Impregnated gingival retraction cord will be placed around the prepared tooth and left for more than 10 minutes.

lower first molar will be prepared for full coverage restoration, plain retraction cord will be placed in the sulcus just before impression recording (less than 10 minutes).

the preparation of the lower first molar for full coverage restoration will be initiated - occlusal reduction, contact points breaking, and preparation with the roughest bur- then a plain retraction cord will be placed and kept in the sulcus until finishing the preparation and impression recording which will take more than 10 minutes.

lower first molar will be prepared for full coverage restoration, Aluminum chloride-impregnated retraction cord will be placed in the sulcus just before impression recording (less than 10 minutes).

the preparation of the lower first molar for full coverage restoration will be initiated - occlusal reduction, contact points breaking, and preparation with the roughest bur- then an Aluminum chloride-impregnated retraction cord will be placed and kept in the sulcus until finishing the preparation and impression recording which will take more than 10 minutes.

The amount of reversible and irreversible gingival recession (vertical gingival retraction) that might occur in healthy humans after placing retraction cords around prepared teeth for different periods of time. This will be measured after recording multiple digital intraoral scans pre-operative, 1 week, and 4 weeks post-operative using Medit i-700 then they will be superimposed using Medit Design tool (previously known as Medit compare) to track the vertical location of the gingival margin.

The impact on periodontal health will be measured by recording the periodontal indices pre-operative, 1-week, and 4 weeks post-operative by a single-blinded periodontist.

Inclusion Criteria: Age of 18-50 years Systemically healthy no history of medical disease Volunteers should have a lower first molar indicated for full coverage restoration, of healthy periodontium with an antagonist tooth and proximal contacts. Gingival index score 0,1 Plaque index score 0,1 Probing depth ≤3 mm No bleeding on probing. Exclusion Criteria: Gingival and periodontal disease Pregnancy and lactation History of systemic diseases such as hypertension, diabetes mellitus, HIV, bone metabolic disorders, radiation therapy, and cancer. History of prolonged use of steroids/immunosuppressive agents/aspirin/anticoagulant/other medications. Heavy Smoking. Deleterious habits. Teeth with high scalloped margins, keratinized tissue less than 2 mm, fibrotic gingival tissue, gingival recession, pocket formation deeper than 3mm. Teeth with thick flat gingival phenotype. Teeth with Sub-gingival caries or restoration at the buccal surface.

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Einarsdottir ER, Lang NP, Aspelund T, Pjetursson BE. 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. J Prosthet Dent. 2018 Jan;119(1):82-88. doi: 10.1016/j.prosdent.2017.03.010. Epub 2017 May 5.