The goal of this clinical trial is to find the best gingival displacement method for taking impressions of artificial full crowns with subgingival margins. The main question it aims to answer is:

Which of the three common gingival displacement methods works best? Researchers will compare three methods: gingival retraction cord, gingival retraction paste, and gingival retraction cord + hemostatic gel, to see which is optimal.

Participants will:

Receive one of the three gingival displacement treatments during impression taking.

Fill out a VAS form to rate their pain.

The success and longevity of dental protheses largely depends on the health of periodontium. To fabricate restorations with well-adapted margins, accurate impressions are imperative. Nevertheless, obtaining accurate impressions is challenging when preparations have intentionally placed cervical margins in the gingival sulcus for esthetic or functional purposes. In such cases, gingival displacement is required to ensure that impression materials can penetrate the gingival sulcus and capture the fine details of the prepared abutment margins.

Gingival displacement is the process in which the marginal gingiva is temporarily deflected by external force, and the sulcus opens to facilitate the entry of impression materials. Its objective should be to facilitate obtaining an accurate impression of the tooth preparation without damaging the periodontium. Gingival displacement techniques can be classified into mechanical, chemical, and surgical categories, or into non-surgical and surgical categories. Non-surgical methods can be alternatively classified into retraction cord methods and non-cord methods.

Traditionally, retraction cords have been widely utilized for gingival displacement. However, the retraction cord technique is associated with several drawbacks. First, the pressure exerted by retraction cords can reach up to 5000 kPa, a magnitude that exceeds the recovery capacity of the epithelial attachment, which consequently impairs the integrity of the epithelial attachment. Second, the applied mechanical force may induce bleeding and soft tissue trauma, which can potentially result in subsequent gingival recession. Third, patients frequently report significant levels of discomfort or pain during the procedure. Despite these limitations, cord methods remain the most widely used technique in clinical settings today. Moreover, to address bleeding and crevicular fluid seepage, impregnated retraction cords containing hemostatic agents, vasoconstrictors, or astringents have been introduced into clinical practice.

On the other hand, non-cord methods and materials are gaining increasing acceptance among dental practitioners, with retraction paste being a prominent example. Retraction paste has attracted considerable attention due to its distinct advantages: ease of application, shorter operation time, reduced patient discomfort, no requirement for anesthesia, facilitation of a dry operating field, and minimized tissue trauma compared to retraction cords. Unfortunately, cordless methods also have inherent limitations, such as insufficient gingival sulcus exposure.

Numerous researchers have investigated various gingival displacement methods and materials to assess their efficacy and safety. Unfortunately, study results have been inconsistent or even contradictory, and no consensus has been reached regarding the most appropriate gingival displacement methods and materials. Existing evidence demonstrates that current displacement methods fail to meet clinical requirements, which has prompted the development of new materials, and medications for this purpose. To date, no satisfactory solutions have been identified. Furthermore, high-quality randomized clinical trials (RCTs) focusing on gingival displacement remain limited. The objective of this randomized controlled clinical trial (RCT) is to evaluate the efficacy of three gingival displacement methods. The null hypothesis was that the three methods would yield equivalent displacement effects.

In the present study the enrolled Patients will get different gingival displacement treatment and fill out the VAS form. The objective of the RCT study is to see which method is optimal for gingival displacement.

Inclusion Criteria:

• need for single crown restoration of maxillary anterior teeth, healthy periodontal status, and subgingival preparation margins on the buccal surface of the affected teeth.

Exclusion Criteria:

• requirement for more than one restoration, restoration in other dental quadrants, and supragingival preparation margins.