The first purpose of this study was to investigate the relationship between the lowest cervical point and the interdental gingival midpoint (IGM) line in the maxillary anterior region. After marking the lowest cervical points and the mesial and distal interdental gingival midpoints on study models of 77 patients, the shortest distances from the IGM lines that connect both interdental gingival midpoints to the lowest cervical points were measured on silicone impressions. The findings showed that the average position of the lowest cervical points in the central incisors coincides with the IGM line. This position is located 0.24 mm palatally in the lateral incisors, and in the canines 0.3 mm facially from the IGM line. The second purpose of the study was to verify the IGM line concept in cervical line management through some clinical cases. In a thick-flat biotype case using a clinical crown lengthening procedure, the lowest cervical points were adjacent to the IGM lines following long-term coronal gingival growth. In a short-term observation of a thin-scalloped biotype case, untouched facial gingiva increased following interdental gingival augmentation. In a case of Miller class 1 gingival recession, a coronally advanced flap combined with the roll technique was performed based on the IGM line concept. According to the results obtained from this study and these cases, it seems that the IGM line could become a diagnostic standard in cervical line management in periodontal plastic surgery.