<unk>  Shaw The term was coined by Sir Arthur Keith. It comes from the Latin taurus meaning "bull" and the Greek ὀδούς (odous), genitive singular ὀδόντος (odontos) meaning "tooth", to indicate the similarity of these teeth to those of hoofed/ungulates, or cud-chewing animals. Radiographic characteristics of<unk>  include: #lack of pulp chamber constriction at the cementoenamel junction (CEJ); #an enlarged pulp chamber that appears rectangular in shape; and #displacement of the pulp chamber floor toward the root apex, shortening the roots and root canals. Earlier classification systems considered only the apical displacement of the pulp chamber floor; whereas, later systems additionally consider the position of the pulp chamber in relation to the cemento-enamel junction and alveolar margin. Shaw 1928 One of the first attempts to classify<unk>  was made by C.J.Shaw. He used the apical displacement of the pulp chamber floor to classify<unk>  into four distinct categories: cynodont (normal), hypotaurodont, hypertaurodont, and mesotaurodont. Shifman & Chanannel 1978 Later, Shifman & Chanannel quantified the degree of<unk>  based on a mathematical formula relating the anatomical landmarks as shown in the figure above. The anatomical landmark ratio is calculated as shown below: Shiffman and ChanannelA: Lowest point of the roof of the pulp chamber. B: Highest point of the floor of the pulp chamber. C: Root apex. D: Cementoenamel junction (CEJ). Landmark ratio Where, A = the lowest point of the pulp chamber roof, B = the highest point of the pulp chamber roof, and C = the longest root’s apex. Using this formula, a tooth is a taurodont if the landmark ratio is ≥ 0.2 and the distance from the highest point of the pulp chamber floor (B) to the cemento-enamel junction (D) is ≥ 2.5 mm. The full classification system based on this formula are displayed in the table below: + Classification Landmark ratio Normal < 0.2 Hypo-taurodont ≥ 0.2 - 0.209 Meso-taurodont ≥ 0.3 - 0.399 Hyper-taurodont ≥ 0.4 - 0.75 It is important to note that historically, there has been professional debate regarding the taurodont classification systems as to: 1) how much displacement and/or morphologic change constitutes<unk> , 2) whether classification should be indexed stepwise or on a continuum, and 3) whether to include certain teeth in the occurrence of<unk> . For example, as premolars are narrow mesio-distally,<unk>  is hard to identify radiographically on premolars. Therefore, some researchers exclude premolars from their classification systems. Additionally, there has been criticism over the use of landmarks that undergo changes. For example, due to trauma or wear, tertiary dentin can be deposited which can then alter some measurements; thus, caution should be employed when diagnosing<unk>  in this case. Finally, as these measurements are dimensionally quite small, they are also subject to large relative error.
Taurodontism
Tourettism
Selective mutism
Tardive dysmentia
Akinetic mutism
Klismaphilia
Palilalia
Autism