# Assessment of Negative Gingival Recession: A Critical Component of Periodontal Diagnosis
###### Abstract  
Accurate measurement of negative gingival recession (GR) is essential to accurately determine the clinical attachment loss, which leads to an accurate diagnosis and optimal therapy of periodontal disease. However, the accuracy of measuring the negative GR has been shown to be low and highly variable between examiners. The position of the gingiva margin in relation to the cemento-enamel junction (CEJ) varies among different stages of passive eruption. The amount of negative GR is about 2 mm on average at the mid-facial sites and ranges from 2 to 3.5 mm at interproximal sites in periodontally healthy patients. Some other clinical conditions may change the gingival dimension coronal to the CEJ, such as altered passive eruption and gingival enlargement. In addition to the traditional approach using a periodontal probe to assess the negative GR, nowadays dental ultrasound imaging may be able to assist in accurately measuring the amount of negative GR. This narrative review will discuss the existing evidence of the dimension of dentogingival tissue and the clinical assessment of negative GR using different clinical tools. negative gingival recession; clinical attachment loss; ultrasonography 202212701520222127015202212212  
(2) crevicular, and (3) subrevicular physiologic dimensions [6], which correspond to the oral, sulcular, and junctional epithelium with the underlying connective tissue, respectively. The biological interface between the gingiva and the tooth that forms the initial barrier to underlying tissues is known as the \"dentogingival junction\" (DGJ) [7]. The average dimension of sulcus depth, epithelial attachment, and the connective tissue attachment was reported to be 0.69 mm, 0.97 mm, and 1.07 mm, respectively [8]. Today, the latter two components forming a functional unit, is termed the \"supracrestal tissue attachment\" [9] which was previously known as the \"biologic width\". The apical migration of the DGJ after dentition completes the active phase of eruption is called passive eruption [10]. [PERSON] et al. described the changes that occur in the location of DGJ in relation to the CEj in four stages of passive eruption [8]. In stage I of the passive eruption, which represents a physiologically healthy state and usually occurs before 30 years old of age, the location of epithelial attachment (today called junctional epithelium) is entirely on the enamel with the most apical termination at the CEj. The average gingival dimension coronal to the CEj (negative GR) at stage I that comprises of sulcus depth and epithelial attachment is 2.15 mm and ranges from 0.28 to 6.34 mm [8]. Along with the apical shift of the dentogingival junction, which is considered a consequence of pathological periodontal destruction, the epithelial attachment is on the enamel and cementum at stage II and entirely located on the cementum at stage III until the epithelial attachment and gingival margin lie apical to the CEj at stage IV [8,11,12]. The length of the epithelial attachment decreases as one progresses from stage I to stage IV of passive eruption, as compared to a relatively constant sulcus depth and connective tissue attachment. The average gingival dimension coronal to the CEj (negative GR) is 1.29 mm (sulcus and part of epithelial attachment) and 0.6 mm (purely sulcus depth) at stages II and III, respectively. In stage IV and beyond, the gingival margin is at the level of or apical to the CEj (Figure 1, Table 1). The dimension described by [PERSON] et al. (stage I-III of passive eruption) is in accordance with the common understanding that the facial gingiva margin is approximately 0.5 to 2 mm coronal to the CEj. This was based on the observation of the distance from free gingiva margin to the free gingival groove and the latter corresponds to the bottom of the gingiva crevice (the base of the epithelial attachment) that is often located at CEj [13]. Figure 1: Four different stages of passive eruption.