Which factor does NOT contribute to the supportive structure of the periodontal ligament?

The supportive structure of the periodontal ligament is primarily comprised of elements that provide strength, flexibility, and biochemical support to the tissues surrounding the teeth. Among the options provided, collagen fibers, various cell types, and elastic fibers are all essential components of the periodontal ligament.

Collagen fibers are particularly important as they form a strong network that anchors the teeth to the surrounding alveolar bone, helping to withstand the forces of chewing. Various cell types, including fibroblasts, osteoblasts, and immune cells, play critical roles in maintaining the health and functionality of the periodontal tissue. Elastic fibers contribute to the resilience of the periodontal ligament, enabling it to absorb the forces applied during mastication.

Calcium deposits, while important in overall bone health and formation, do not directly contribute to the structural makeup of the periodontal ligament itself. The periodontal ligament does contain some mineralization related to the attachment of the periodontal fibers, but it is not characterized by calcium deposits as a fundamental supportive structure. Thus, the absence of calcium deposits being a primary factor in the periodontal ligament structure makes it the correct answer to the question.