Final answer:
The wave formation in hair during a permanent wave is maintained by using a reducing agent to temporarily break disulfide bonds, followed by applying an oxidizing agent to reform these bonds, fixing the hair into the new shape.
Step-by-step explanation:
The wave formation in the hair during a permanent waving process is held by the application of a reducing agent, which allows the breaking of the disulfide bonds in the hair's keratin structure. Once the hair is wrapped around rollers to achieve the desired shape, an oxidizing agent, commonly a diluted solution of hydrogen peroxide, is applied. This neutralizer causes the broken disulfide bonds to reform, fixing the hair into its new position. These new bonds stabilize the shape of the hair until it naturally grows out or is otherwise treated.