The invention relates to the use of a thermal reversible gel, such as a
copolymer composition, as a biological filler or
implant. The gel has a semi-
solid form at body temperature, but upon cooling to a temperature below a threshold level, the gel is liquefied and can be re-shaped, re-sized, manipulated or removed from the body. The gel may be used as a
subcutaneous implant, a biological filler, joint or tissue spacer, for
wrinkle filling or other cosmetic implants, as a soft-
tissue replacement for
reconstructive surgery, or as a barrier within the lumen of a
biological structure, such as a
blood vessel. The
implant may be used to provide reversible birth control by providing, for example, a reversible barrier to the
cervix or a reversible blockage of the lumen of the
vas deferens.