Figure 1. The alveolar process and regions/locations for indentation testing. (a) Schematic of bucco-lingual section of mesial root of a premolar and its alveolar process. The alveolar process is divided into 3 regions—coronal, middle, and apical—along the root length of the tooth. Each third is numbered 1 through 6, with 1 being the coronal region on the buccal side and 6 being the coronal region of the lingual side (for the mandibular alveolar process) or the palatal side (for the maxillary alveolar process). Dark lines near (< 200 µm) the periodontal ligament indicate the location of indents in alveolar bone proper (also know as alveolar bone/cribriform plate, bundle bone); stippled boxes indicate approximate locations of indents in cortical bone. (b) Photomicrograph of the alveolar process and surrounding dental structures in the coronal region. Two rectangular boxes indicate approximate sites for making 5 indentations in bone. The box on the left is closer to the periodontal ligament and indicates the location of indents in alveolar bone proper. The box on the right indicates the center of the osteonal cortical bone. This photomicrograph clearly depicts differences in bone morphology and heterogeneity in the alveolar process. Bar indicates 100 µm.