To evaluate and compare the effect of translucent zirconia and lithium disilicate crown on IL- 6 and TNF- levels in gingival crevicular fluid GCF at various time intervals a split-mouth comparative pilot study.

Different crown materials have been known to affect the health of the periodontium.  Dental restorations are in close contact with the oral tissues, and although systemic side effects are rarely observed, yet local inflammatory reaction or hypersensitivity may be observed sometimes.  Gingival crevicular fluid (GCF) is a physiologic transudate present in a healthy gingival crevice in a small amount that increases during periodontal inflammation and becomes an inflammatory exudate.  It is a promising diagnostic and prognostic fluid with many advantages such as site-specific, non-invasiveness and contains a wide variety of microbial and host mediators like pro-inflammatory cytokines such as IL-1 b, IL-6, IL-8, TNF-α etc. Periodontal inflammation is characterized by well-orchestrated process of host defence through leukocyte recruitment and monocyte activation. These cells have been known to release pro-inflammatory mediators and cytokines (IL-1, IL-6, and Tumour necrosis factor alpha (TNF-α) in gingival crevicular fluid (GCF), that contribute to the inflammation.  TNF-α is responsible for activation of cytokines and initiates the process of inflammation. Macrophages and T-cells secrete TNF-α, which play an important role in early induction of periodontal inflammation.  Similarly, Interleukin-6 (IL-6) also activates localized immune cells and causes gingivitis and periodontal tissues destruction. Furthermore, TNF-α may synergistically stimulate human gingival fibroblasts to enhance IL6 secretion. Elevation of both IL-6 and TNF-α causes periodontal and gingival breakdown via disturbances in lipid metabolism of cells. Increased IL-6 levels are reported in periodontitis and a significant decrease in its level following periodontal therapy indicates its role as an early disease onset biomarker for periodontal inflammation has been established. Therefore, increased IL-6 and TNF-α in seen with early inflammatory conditions like marginal gingivitis and their levels further increases in periodontal breakdown. Translucent zirconia and lithium disilicate are indirect restorative materials that are commonly used because of their high aesthetic properties, mechanical properties, flexural strength, durability and biocompatibility.Therefore, this study has been designed to evaluate and compare the effect of translucent zirconia and lithium disilicate crown on gingival biomarkers (IL-6 and TNF- α) levels in gingival crevicular fluid (GCF) at various time intervals.