Lec: Treatment of class I malocclusion Class I occlusion can be defined by Angles, classification as the mesiobuccal cusp of the upper 1 st permanent molar occlude with the developmental groove of the lower 1 st molar. According to certain criteria, class I occlusion can be subdivided into: 1))Normal class I occlusion: Meaning the molar relation is class I and there is no tilted and/or malposed tooth or teeth. Also the antero-posterior occlusal relationship is (normal) class I and there is normal overbite and overjet. Moreover, there is normal transverse as well as vertical relationship between the archs, adding to that the lower incisor, s edges occlude at the (cingulum) middle third of the palatal surface of the upper incisors and the upper canine located between the lower canine and 1 st permanent premolar. 2)) Class I malocclusion: here the molar relation, similar to the 1 st type, also is class I (the antero-posterior occlusal relationship is normal) but there is a discrepancy either within the arches and/or in the transverse or vertical relationship between the arches. a. Crowding and irregularities of teeth. b. Spacing of teeth. c. Localized malposition. d. Discrepancy in the transverse relation (crossbite). e. Increase overbite and anterior openbite. Aims of class I malocclusion treatment: o To improve esthetic of the patient. o To improve function of the teeth and the jaw. o To improve good oral hygiene and subsequently less carious lesion.
crowding ORTHODONTICS Treatment of malocclusion Assist.Lec.Kasem A.Abeas Etiology of class I malocclusion i. Skeletal factor. (usually Class I) ii. Soft tissue factor. (favourable) iii. Dental factor. (main aetiological influences) Treatment of class I malocclusion: 1))) crowding and irregularities of teeth: It is associated with increased tooth size and decrease in arch length (hereditary cause), but can also associated with premature loss or delay shedding of the predecessor teeth which later on will lead to tilting; displacement or drifting of teeth into space created (environmental cause). Treatment of crowding usually is depend on the: a. Site of the b. Degree of the c. Position of the The common site of crowding in the upper arch: i. Lateral incisors which crowded labially or palatally. ii. Canines which is either buccaly or palatally displaced. iii. 2 nd premolars crowded palatally. iv. 2 nd and 3 rd molars may be buccally displaced. The common site of crowding in the lower arch: i. Lateral incisors mostly are crowded lingually. ii. Canines buccaly crowded. iii. 2 nd premolars lingually crowded. iv. 2 nd and 3 rd molars may be displaced mesioangular or impacted. Treatment of crowding: In growing subject, spontaneous relief of crowding after the extraction of deciduous dentition neighboring to the displaced tooth like in case of upper and lower incisors crowding by extraction of the primary canines and spontaneous improvement occurs in the 1 st six months after the extraction. If not occurs; otherwise, after 1 year active tooth movement by removable or fixed orthodontic appliances.
Or we can relief the crowding by creation of space by any method of space creation according to the degree of crowding, which are: a) Interproximal stripping b) Arch expansion c) Molar distalization d) Proclination of incisors e) Extraction f) All of the above In case of buccally or palatally displced canine by the extraction of upper or lower 1 st premolar according to the position of the canine in the arch and use either fixed or removable appliance. While in case of 2 nd premolar crowding, by alignment into the arch if its mildly displaced or by extraction of 1 st premolar (if it is badly carious) using active orthodontic appliances; otherwise, specially if the 2 nd premolar is completely excluded from the dental arch, by extraction of it. Clinical note: extraction of teeth in very mild crowding may result in residual spacing of the arches unless fixed appliances can be used for tooth movement. In more sever crowding, however, spontaneous space closure may be beneficial but may not allow relief of irregularity without the use of passive or active appliances. Whether adequate spontaneous movement occurs will depend on the position of individual teeth particularly their apical position and rotation. The simple irregularities of the upper arch can be treated with removable appliances, malposition of teeth requiring apical or bodily (controlled) movement needs to be carried out with fixed appliances. While special attention should be given in treatment of lower arch crowding since removable appliances are generally less satisfactory in the lower arch and we have to plan treatment in the lower arch 1 st then build the upper arch accordingly. Late lower incisor crowding: In most individuals intercanine width increases up to around 12 to 13 years of age, and this is followed by a very gradual diminution throughout adult life. This reduction in intercanine width results in an increase of any pre-existing lower labial crowding.
The aetiology of late lower incisor crowding is recognized as being multifactorial: o Forward growth of the mandible when maxillary growth has slowed, together with soft tissue pressures, which result in a reduction in lower arch perimeter and labial segment crowding. o Soft tissue maturation. o Mesial migration of the posterior teeth owing to forces of occlusion. o The presence of an erupting third molar pushes the dentition anteriorly, i.e. the third molar plays an active role. 2))) Spacing of teeth: a. Generalized spacing: Accept, restorative aproach, fixed appliance. b. Hypodontia(mild, moderate, sever): Fixed appliance + prosthesis. c. Diastema: Fixed appliance+ Frenectomy (before, during, after). d. Proclination of teeth: Removable or fixed appliance. Treatment of spaces depend on a good communication between the orthodontist and the prosthodontist as space closed and addition of synthetic teeth is required. 3))) Localized malposition: Diverse contributing factors could be result in the development of tooth displacement. It can be occurs as a result of abnormal position of the tooth germ: canines and 2 nd premolars are the most commonly affected teeth or as a result of crowding (lack of space): Appear to affect those teeth that erupt last in a segment? Treatment depend on the general state of the dental arch whether it is crowded or spaced and the etiological factor. 4))) Crossbite: It is a discrepancy in the transverse (buccolingual ) relationship between the arches. It described in terms of the position of the lower teeth relative to the upper teeth. It can be unilateral or bilateral crossbite which can be corrected by arch expansion using either removable or fixed appliance (hyrex) to open the midpalatal suture.
5))) Increased overbite (deepbite): It is a discrepancy in the verical relationship of the dental arches which is mostly associated with reduction in the vertical dimension. It have different types according to the bite depth and gingival trauma. It can be corrected by using simple anterior bite planes (removable appliance) to disclude buccal segment teeth and encourage their overeruption subsequently. While in case of incisors, angulation needs to be corrected to achieve optimal interincisal angle, a fixed appliance is required to produce torquing movement. 6))) Open bite: Most of the openbite cases resulted from bad habit are resolved spontaneously as the habit stop during the early stages of growth, otherwise it can persist to adult time. However, when vertical movement of the incisors and/or molars is required, Fixed appliance is the best choice in most cases. Bimaxillary proclination Bimaxillary proclination is the term used to describe occlusions where both the upper and lower incisors are proclined. Bimaxillary proclination is seen more commonly (considered normal) in some racial groups (Negroid). It is Mostly associated with class I malocclusion (i.e. the incisor relation is class I). As aresult, the overjet is increased due to the angulation of the incisors. Also it is mostly associated with lip (seperation, strain, protrusion). The treatment is very difficult due to the action of the tongue and it give a high risk of relapse ( poor prognosis) unless prolong retention is required. It is necessary to treat such malocclusion by a specialist and the patient have a good muscle tone with competent lips which likely to retain the corrected incisor position after the appliance removal. Post treatment retention: Relapse encompasses the return following treatment of the original features of the malocclusion as well as long-term growth and soft tissue changes. This depend on: Severity of the case. Type of tooth movement. Type of treatment. Types of retention: 1)) Removable retention. 2)) Fixed retention.