A simple method for measuring thickness of gingiva and labial bone of mandibular incisors

Objective: Thin supporting tissues may cause gingival recessions and esthetic problems in the anterior area. The objectives of this study were to present a simple and reliable radiographic technique to measure thickness of alveolar bone labial to mandibular incisors, and to establish a possible correlation of bone thickness with its tissue biotype. Method and Materials: A metal strip was placed over the gingiva of the mandibular incisor axis, and a perpendicular occlusal radiograph was taken of 51 patients. Patients in routine orthodontic practice before any orthodontic treatment was started were distributed into three groups according to their periodontal biotype (A1, thin with 2 mm keratinized gingiva; A2, thin with > 2 mm; and B, thick with wide zone of keratinized gingiva), as described by Müller and Eger.1 Radiographs were scanned and thickness of gingival tissue and of bone at two levels (at the bone crest and at 3 mm below the bone crest) was measured to the nearest 0.1 mm. Measurements of soft tissue and bone thickness were compared and correlated. Results: Groups A2 and B showed a significant difference in bone thickness at the bone crest. Correlation of bone and gingival thickness was only found in gingival biotype B at 3 mm below the bone crest level only (R = 0.290; P .001). No other correlation between bone and gingival thickness was observed in any group. Conclusions: The radiographic technique proposed in this study is a simple and reliable method for calibrating the amount of buccal bone in the mandibular anterior area. It is a cheap and fast diagnostic tool that may help determine the amount of buccal bone and gingival thickness, and therefore avoid excessive radiation to patients. Groups A2 and B showed a significant difference in bone thickness at the bone crest. Although not significant, group A1 showed the lowest values of bone and gingival thickness, whereas group B showed the highest bone and gingival thickness. A clear correlation between thickness of bone and gingiva 3 mm below the cementoenamel junction was found in group B. Keywords: diagnosis, gingival recession, gingival thickness, oral hygiene