Nutrition is an important factor, influencing the general health and tissue tolerance of orthodontic patients at many levels. While orthodontists will rarely see frank manifestations of nutritional deficiencies, it should be recognized that sub optimal levels of certain nutrients are common and have an effect on the biologic responses of the tissues influenced by orthodontic treatment. To optimize patient's physiologic response to orthodontic treatment, it may be beneficial to provide dietary guidance to orthodontic patients in choosing soft food diets. This includes obtaining nutrition history, evaluating the diet, educating the patient about diet components important for oral health, motivating the patient to improve diet and follow up to support patient's effort to change food behaviors. this book give a complete insight to importance of diet and nutrition in field of orthodontics.