The periodontium is the specialized tissues that both surround and support the teeth, maintaining them in the maxillary and mandibular bones.The periodontium is a complex structure composed of the gingiva, periodontal ligament (PDL), cementum, and alveolar bone (Figure 11-1). The primary functions of the periodontium are to allow the tooth to be attached to the bone and to provide a barrier for the underlying structures from the oral microflora.