Which cellular structure is induced to grow during the development of a periapical cyst?

• A. Fibroblasts
• B. Epithelial cell rests of Malassez
• C. Odontoblasts
• D. Cementoblasts

Answer: (B)

In a periapical (radicular) cyst, the epithelial cell rests of Malassez in the periodontal ligament are induced to proliferate and form the cyst lining. These rests are remnants of Hertwig’s epithelial root sheath that sit dormant in the PDL until chronic inflammation from a necrotic pulp triggers their growth. The inflammatory milieu provides growth signals and cytokines that push these epithelial cells to multiply, creating an epithelial-lined cavity that expands and leads to bone resorption around the tooth apex. Other cell types listed—fibroblasts, odontoblasts, and cementoblasts—play roles in connective tissue, dentin formation, and cementum, respectively, but they do not form the cyst lining.