There are many types of cross bites, numerous etiologies, several philosophies of treatment, as well as, the most appropriate time to treat this debilitating functional, dento-skeletal, and sometimes cosmetically disfiguring malocclusion. Cross bites can cause, or contribute to the following maladies, if not corrected i.e. nasal airway obstruction, compulsive mouth breathing, chronic sleep apnea, opened-mouth posture, severe maxillary crowding, impacted canines, asymmetrical growth and development of teeth and jaws, chronic cheek and tongue biting leading to leukoplakia and precarcinogenic mucosa later in life, speech impediments, severe bruxing and clenching, masticatory inefficiency, premature attrition, dental recession, idiopathic and spontaneous tooth movement, excessive secretions of hydrochloride acid, gastric juice and bile, in conjunction with reverse peristalsis, ulcerations, and halitosis (irritable bowel syndrome), malnutrition, temporomandibular joint dysfunction, associated with headaches, ear aches, neck and shoulder pain, loss of hearing, vertigo, tinnitus, meniscus subluxation (lockjaw), TMJ crepitus distorted/asymmrtical smiles and physiognomy, and last but not least, condylar osteoarthritic degeneration. During the growing phase i.e. mixed dentition, to, and including puberty (approximately 7 to 14 years of age) on both males and females, we use only 016” expanded maxillary arch wire, in conjunction with ¼ inch, 6 ounce cross elastics on one, or both sides, depending upon whether we are dealing with a unilateral bilateral cross bite. If it’s a unilateral cross bite we use a straight vertical 1/8 inch, 4 ounce elastic on the non cross bite side in conjunction with the 1/4”, 6 ounce elastic on the cross bite side. We have not had to use any other kind of expansion appliance in over 25 years. After puberty (approximately 14 years of age) when I believe the mid-palatial suture has closed, I will create a 2mm space between the mx 2’s and 3’s, and have the oral and maxillofacial surgeon perform the expansion in the OR, under conscious sedation, which takes approximately 45 minutes. Usually the 8’s are surgically removed at the same time, which takes approximately 20 more minutes. Post-surgically we maintain the stability of the cross bite correction with the technique, as above with elastics for 10 weeks. If the cross bite was the only problem, we remove the fixed appliances (braces) and insert an Essix (Biostar) retainer, on the same day, to be worn full-time for 2 weeks, and then at night time, on a decreasing scale, over 3 years, decreasing at the rate of one night every 6 months, until down to 0. I have never had a problem, to date, using this approach. I hope these suggestions will be of some assistance to those of you who are still struggling with the diagnosis, timing, and treatment of that most challenging of malocclusions, the “cross bite”.