Abstract: Provided is a game that relies on virtual synthesis of compounds based on building blocks for these compounds, such as the elements of the periodic table.

Abstract: Orthodontic brackets comprise a bracket body having a single centrally-disposed pair of gingivally-occlusially extending tie wings that protrude labially from the body and are embraced by a ligating loop to hold the bracket on the cooperating arch wire that passes through the arch wire slot, the slot thereby being of dual depth across the width of the bracket. The parts of the loop alongside the tie wings close the labial side of the slot but cannot engage a wire in the slot of smaller lingual-labial dimension than the slot, so that sliding friction between the wire and bracket is minimized. Such single central wings can be relatively wide in a small bracket, making it especially suited for production from ceramic materials. Another embodiment intended for manufacture from metal employs two mesially-distally spaced pairs of headed posts in place of the tie wings, each pair extending respectively from the gingival and the occlusal surface of the bracket body.