In some circumstances it may be desired to have fastener 100 remain permanently in the body, without any substantial degradation over time; in this event, fastener 100 may be formed out of materials such as polypropylene, Hytrel (R) copolyester, or homopolymer polyesters, e.g. polyethylene terephthalate or polybutylene terephthalate, or nylon, or polyethylene, or polycarbonate, or acrylonitrile bu