Self-etching primers are the latest addition to the armamentarium of an orthodontist. Their main advantage is that they reduce the number of steps required in the bonding of orthodontic brackets. However, their low ph was a cause of concern. This book describes a study undertaken to see the effects of ph of self-etchant on shear bond strength of orthodontic brackets. These shear bond strengths were also compared to those obtained with a conventional 3-step bonding system. It was found that self-etching primers not only reduce the chair time in an orthodontist's clinic but also reduce the amount of enamel lost during etching. The bond strength achieved was less than that of the conventional bonding system but was acceptable for orthodontic purposes. Thus self-etching primers are an important and useful invention for simplifying the most critical step in orthodontic clinic- bonding.