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CATEGORY LINICAL

preadolescent and adolescent periods. Apart from the e ects of dental disease, which can result in major occlusal changes if teeth are lost, there is a gradual and progressive loss in arch length as age increases, particularly in the lower arch of females. e stability of incisor correction will depend in part on whether a positive overbite can be achieved at the end of treatment. Stability will also depend on future adolescent growth. Based on studies, the majority of ado lescent pre-orthodontic patients, regardless of gender, present with some disc displace ment. e clinician needs to assess the TMJ, and in case of joint sounds, present any pa thology. Often clicks occur in the absence of any pain or signs of progression. 4. Soft-tissue and facial aesthetics With good documentation of tooth lip relationships, the orthodontist subsequently can make any appropriate adaptations in appliance placement or make a decision on the need for di erential growth or dental eruption modi cation of the maxilla/mandible in the adolescent years. Lip incompetence is common in preadolescent children and competence increases with age due to vertical growth of the soft tissues, especially in males. Mini-aesthetics e positioning of the upper lip during social smile u e nal position of the upper lip during smile and the amount of gingival display can be quite variable, depending on the patient’s age. u Clinical impacts on judging whether the adolescent has a gummy smile that will improve with time or whether orthodontic treatment should be

directed to increase incisor display. u In both the adolescent and the adult, opening a deep overbite with maxillary incisor intrusion is, in general, a procedure that has a negative e ect on the maturation and aging of the smile. u In adolescents and young adults, 3 to 4 mm of the maxillary incisor should be displayed at rest. Upper incisor display decreases as the upper lip grows with age. u e height of the central part of the upper lip trails behind that of the lower face in childhood but catches up after adolescence. Lip thickness increases during childhood and adolescence, reaches a maximum towards the end of the adolescent growth spurt, and then decreases in the late teens. Incisor height tends to be more variable than incisor width because of the variability of soft tissuebiotypes and, in theadolescent, stages of active and passive eruption. e age of the patient is a factor in crown height because of the rate of apical migration in the adolescent. Width is a critical part of smile display in that the proportion of the teeth to each other is an important factor in the smile. e ideal ratio, however, should be 8:10 of width to height. Micro-aesthetics Incisor height/width ratio

Interdental gap

Age of the patient In an adolescent patient, mandibular growth can be utilized to reduce an increased overjet, especially during the pubertal growth spurt. Example: Lower facial height increase in the adolescent may be improved through modi cation of growth, dental eruption, or both. Rate of tooth movement During tooth movement, changes in the periodontium occur, depending on magnitude, direction and duration of the force applied, as well as the age of the orthodontically-treated patient. e tissue response to orthodontic forces is considerably slower in older individuals than in children and adolescents. Gianelly (AO 1994) notes that crowding can be easily treated with a non-extraction approach in at least 85% of all patients when treatment is started in the late mixed dentition. It is also suggested that at least 90% of all growing patients can be treated in only one phase of treatment in the late mixed dentition. 3. Occlusal and functional Based on a longitudinal study of individuals who have not undergone orthodontic treatment, the dentition does not remain static throughout life. Generally, the dental arches in males grow larger and for longer than in females during both the

Height to width ratio of tooth

Nasal Anatomy Orthodontic treatment plans and mech anics can dramatically a ect the way the nose ts the face. In addition, nasal growth in the adolescent can produce changes that diminish the aesthetic result as the patient matures. e orthodontist needs to understand nasal anatomy and the treatment of nasal deformities well enough to be comfortable with discussions of

Maxillary incisor display

AUSTRALASIAN DENTIST 49