Early treatment of Class III incisor relationship using the chincap appliance.
Occlusion is defined as the contact relationship of the maxillary and Class II, division 1: Upper incisors are tilted outwards, creating significant. A. Class II division 1 malocclusion describes this relationship when the maxillary central incisors are proclined or normally inclined and the overjet is increased. Eur J Orthod. Oct;15(5) Early treatment of Class III incisor relationship using the chincap appliance. Allen RA(1), Connolly IH, Richardson A .
Extraction of a lower incisor is contraindicated in the following clinical situations: Excessive overjet that would be worsened by the extraction. A deep bite that would be further deepened by closure of the extraction space. A triangular lower incisor whose extraction could result in a loss of gingival papilla between the remaining incisors. A space requirement of less than 3mm, which would be better managed by interproximal enamel reduction than by extraction.
A lower-anterior tooth-size discrepancy in which extraction of a lower incisor could create a mandibular deficiency, making it difficult to obtain an ideal anterior occlusion. High insertion of the lower labial frenum, which could lead to gingival recession of a tooth moved into this region. Kokich and Shapiro strongly advocated the use of a diagnostic setup in lower-incisor-extraction cases to predict the precise occlusal result. Case 1 A year-old female presented with the chief complaints of irregular front teeth and an inability to bite in the front because the lower teeth were ahead of the upper teeth.
Clinical examination showed a Class III incisor relationship on a Class III skeletal base, with average lower-anterior facial height and a deficient Frankfort-mandibular plane angle Fig. The overjet was -2mm to the upper left lateral incisor; the overbite was reduced but incomplete, with an anterior open bite measuring 2mm at its worst point.
We noted mild upper and moderate lower crowding, a lower midline shift to the left, and a bilateral buccal crossbite tendency. The panoramic x-ray demonstrated proper alveolar bone levels and root morphology, along with the presence of all permanent teeth except for the lower left lateral incisor, which had previously been extracted.
Cephalometric analysis confirmed a Class III skeletal base with normally inclined upper incisors and retroclined lower incisors Table 1. Because the patient did not want to wear visible appliances, treatment was planned with the Invisalign system. Space would be created in the upper arch by proclination of the upper incisors and a modest amount of expansion. Extraction of the lower right central incisor, which was the most proclined and had the least satisfactory gingival contour of the remaining incisors, would provide space for relief of the lower crowding, while the incisor relationship would be corrected by minor retroclination.
Occlusion and malocclusion
The objective was to maintain the Class III molar relationships and improve the overbite, accepting a lower midline discrepancy. Polyvinyl siloxane PVS impressions and a silicone bite registration were sent to Align Technology for the creation of pretreatment and projected end-of-treatment ClinChecks Fig.
We asked for slower staging to reduce the rate of tooth movement by half, to. Invisalign attachments are designed to provide 3D control of various tooth movements Table 2.
In this case, to promote space closure and prevent tipping, vertical rectangular attachments 5mm high, 2mm wide, 1mm thick were bonded to the lower left central and right lateral incisors, and optimized rotation attachments were bonded to the upper canines Fig.
Optimized rotation attachments were placed on the lower canines to provide a more acute activation angle between the aligner and the surface area of the attachments Fig. Because the upper right central incisor, upper right lateral incisors, and upper left lateral incisor were lingually tipped compared to the upper left central incisor, optimized extrusion attachments were bonded to these teeth for. This ClinCheck programming would help close the anterior open bite and improve the smile line and incisor display.
Beveled vertical rectangular attachments 5mm high, 2mm wide, 1. A series of 29 aligners was fabricated, and the patient was instructed to wear each pair at least 20 hours a day for two weeks Fig. Activation angle of optimized attachments.
After eight months of treatment. To promote root uprighting, sequential staging was performed on the teeth on either side of the extraction space were moved by the first three to four aligners, using the rest of the arch as anchorage, before the remaining teeth were repositioned. The Invisalign pontic system was used as a visual substitute for the extracted incisor Fig.
A bonding adhesive is applied to the inner surface of the aligner tray and let dry for 60 seconds before the tooth-colored PVS pontic is positioned in the aligner and allowed to set for five minutes. In the final stages, as the lower-incisor extraction space was closed, the pontic was omitted. Toward the end of treatment, composite buttons were bonded to the upper first molars and lower canines, and the aligner trays were modified for attachment of Class III elastics for finishing.
Three refinement aligners were required.
incisor relationship - oi
After a total 16 months of treatment, upper and lower fixed retainers were bonded, and vacuum-formed retainers were delivered to be worn at night. The arches were well aligned, with positive overjet and improved overbite Fig. Patient after 16 months of treatment. A good esthetic result was achieved after closure of the lower-incisor extraction space. The panoramic radiograph confirmed bodily tooth movement, with the roots of the remaining lower incisors almost completely parallel. A periapical radiograph showed no apical pathology of the lower right lateral incisor, as was suggested by the panoramic x-ray.
Case 2 A year-old male presented with the chief complaint of irregular front teeth and an almost edge-to-edge bite. Clinically, he demonstrated a Class III incisor relationship on a Class I skeletal base, with average lower-anterior facial height and a normal Frankfort-mandibular plane angle Fig. Superimposition of cephalometric tracings. The overjet was 1. The upper arch was moderately crowded, with a mesiolabially rotated left lateral incisor; the lower arch was mildly crowded, with proclined incisors and a left first premolar in buccal crossbite.
The lower posterior dentition had been extensively restored. Such skeletal disharmonies often distort sufferer's face shape, severely affect aesthetics of the face, and may be coupled with mastication or speech problems.
Most skeletal malocclusions can only be treated by orthognathic surgery.
However, there are also other conditions, e. Many authors have tried to modify or replace Angle's classification. This has resulted in many subtypes and new systems see section below: Review of Angle's system of classes. Angle's classification method[ edit ] Class I with severe crowding and labially erupted canines Class II molar relationship Edward Anglewho is considered the father of modern orthodontics, was the first to classify malocclusion.
He based his classifications on the relative position of the maxillary first molar. The teeth should all fit on a line of occlusion which, in the upper arch, is a smooth curve through the central fossae of the posterior teeth and cingulum of the canines and incisors, and in the lower arch, is a smooth curve through the buccal cusps of the posterior teeth and incisal edges of the anterior teeth. Any variations from this resulted in malocclusion types.
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It is also possible to have different classes of malocclusion on left and right sides. Neutrocclusion Here the molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have problems like spacing, crowding, over or under eruption, etc.
Distocclusion retrognathismoverjet, overbite In this situation, the mesiobuccal cusp of the upper first molar is not aligned with the mesiobuccal groove of the lower first molar. Instead it is anterior to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars.
There are two subtypes: Class II Division 1: The molar relationships are like that of Class II and the anterior teeth are protruded.
Class II Division 2: The molar relationships are Class II but the central are retroclined and the lateral teeth are seen overlapping the centrals. Mesiocclusion prognathismAnterior crossbitenegative overjet, underbite In this case the upper molars are placed not in the mesiobuccal groove but posteriorly to it. The mesiobuccal cusp of the maxillary first molar lies posteriorly to the mesiobuccal groove of the mandibular first molar.