The aetiology of<unk>  is somewhat contentious, however, simply put it is multifactorial, with influences being both genetic and environmental.<unk>  is already present in one of the Skhul and Qafzeh hominin fossils and other prehistoric human skulls. There are three generally accepted causative factors of<unk> : * Skeletal factors – the size, shape and relative positions of the upper and lower jaws. Variations can be caused by environmental or behavioral factors such as muscles of mastication, nocturnal mouth breathing, and cleft lip and cleft palate. * Muscle factors – the form and function of the muscles that surround the teeth. This could be impacted by habits such as finger sucking, nail biting, pacifier and tongue thrusting * Dental factors – size of the teeth in relation to the jaw, early loss of teeth could result in spacing or mesial migration causing crowding, abnormal eruption path or timings, extra teeth (supernumeraries), or too few teeth (hypodontia) There is not one single cause of<unk> , and when planning orthodontic treatment it is often helpful to consider the above factors and the impact they have played on<unk> . These can also be influenced by oral habits and pressure resulting in<unk> . Behavioral and dental factors In the active skeletal growth, mouthbreathing, finger sucking, thumb sucking, pacifier sucking, onychophagia (nail biting), dermatophagia, pen biting, pencil biting, abnormal posture, deglutition disorders and other habits greatly influence the development of the face and dental arches. Pacifier sucking habits are also correlated with otitis media. Dental caries, periapical inflammation and tooth loss in the deciduous teeth can alter the correct permanent teeth eruptions. Primary vs. secondary dentition<unk>  can occur in primary and secondary dentition. In primary dentition<unk>  is caused by: *Underdevelopment of the dentoalvelor tissue. *Over development of bones around the mouth. *Cleft lip and palate. *Overcrowding of teeth. *Abnormal development and growth of teeth. In secondary dentition<unk>  is caused by: *Periodontal disease. *Overeruption of teeth. *Premature and congenital loss of missing teeth.
Malocclusion
Splenosis
Venous leak
Inspissation
Needle remover
Defecation
Anaplasia
Subluxation