Fig.3 simple braces (so-called loop spring).  The simple braces have several parts.  The first is the band (B) that seats over #3.  Two wires (*, **) holds the tooth #5 in place.  Between the band and wires is a loop (red arrowhead).  The latter has function of spring.  Once the loop (red arrowhead) is squashed, the wire with single * will slide along the wire with ** and be pushed against #5.  Since the molar tooth (#3) is bigger and stronger than the premolar (#5), the latter will be pushed forward (blue arrowhead) and become straight, back to original article