The viability of the TMJ disc cell decreased significantly (P <0.0001) without glucose. With glucose present, the decrease in oxygen levels significantly increased viability (P <0.0001), while a decrease in glucose concentration significantly decreased viability (P <0.0001). With glucose present, decreased oxygen levels significantly reduced ATP production (P <0.0001) and matrix synthesis (P <0.0001). A decrease in glucose concentration significantly decreased collagen synthesis (P <0.0001). The interaction between glucose and oxygen was significant with respect to cell viability (P <0.0001), ATP production (P = 0.00015) and the synthesis of collagen (P = 0.0002) and proteoglycans (P <0.0001).
Although both glucose and oxygen are important, glucose is the limiting nutrient for the survival of the TMJ disc cells. At low oxygen levels, the production of ATP, collagen and proteoglycan is severely inhibited. These results suggest that there may be more pronounced nutrient gradients in the TMJ disc and it may be vulnerable to pathological events that impede the supply of nutrients.
