Influence of pH and calcium on growth and attachment of human fibroblasts in vitro.

Human embryonic diploid lung fibroblasts (HEDL fibroblasts) and periodontal ligament fibroblasts (PDL fibroblasts) were cultured in media at fixed pH levels ranging between 7.2 and 8.4 and fixed calcium concentrations ranging between < or = 100 microM and 20 mM in an attempt to mimic the effects of calcium hydroxide on vital cell functions such as attachment and growth. PDL fibroblasts appeared to be more susceptible to changes in pH and calcium concentration than HEDL fibroblasts. At pH levels above 7.8, both attachment and growth decreased significantly. Growth was influenced more by changes in pH and calcium concentration than was attachment. The results help explain why intracanal application of calcium hydroxide through its high pH may impair periodontal healing in areas on the root surface where the cementum has been damaged by either trauma or periodontal treatment, thus allowing the medicament access to the root surface.