Gingival sulcus in the context of Toothbrush

In dentistry, dental calculus or tartar is a form of hardened dental plaque. It is caused by precipitation of minerals from saliva and gingival crevicular fluid (GCF) in plaque on the teeth. This process of precipitation kills the bacterial cells within dental plaque, but the rough and hardened surface that is formed provides an ideal surface for further plaque formation. This leads to calculus buildup, which compromises the health of the gingiva (gums). Calculus can form both along the gumline, where it is referred to as supragingival ('above the gum'), and within the narrow sulcus that exists between the teeth and the gingiva, where it is referred to as subgingival ('below the gum').

Calculus formation is associated with a number of clinical manifestations, including bad breath, receding gums and chronically inflamed gingiva. Brushing and flossing can remove plaque from which calculus forms; however, once formed, calculus is too hard (firmly attached) to be removed with a toothbrush. Calculus buildup can be removed with ultrasonic tools or dental hand instruments (such as a periodontal scaler).

In dentistry, the crown is the visible part of the tooth above the gingival margin and is an essential component of dental anatomy. Covered by enamel, the crown plays a crucial role in cutting, tearing, and grinding food. Its shape and structure vary depending on the type and function of the tooth (incisors, canines, premolars, or molars), and differ between primary dentition and permanent dentition. The crown also contributes to facial aesthetics, speech, and oral health.

In biological morphology and anatomy, a sulcus (pl. sulci) is a furrow or fissure (Latin: fissura; pl. fissurae). It may be a groove, natural division, deep furrow, elongated cleft, or tear in the surface of a limb or an organ, most notably on the surface of the brain, but also in the lungs, certain muscles (including the heart), as well as in bones and elsewhere. Many sulci are the product of a surface fold or junction, such as in the gums, where they fold around the neck of the tooth.

In invertebrate zoology, a sulcus is a fold, groove, or boundary, especially at the edges of sclerites or between segments.

A cusp is a pointed, projecting, or elevated feature. In animals, it is usually used to refer to raised points on the crowns of teeth.The concept is also used with regard to the leaflets of the four heart valves. The mitral valve, which has two cusps, is also known as the bicuspid valve, and the tricuspid valve has three cusps.