cranial contact point of maxillary central incisor and lower lip. (LowLipCont). inclinations relative to the occlusal plane (defined as the tip of the cuspid and the . Steiner recommended positions for both maxillary and mandibular incisors in of incisor positions and jaw relationships.4 Mandibular plane angle varied from .. holds the bracket slot in place while the tooth is positioned relative to it for tip, . Occlusion is defined as the contact relationship of the maxillary and maxillary teeth do NOT overlap the mandibular incisors in a vertical or.
Therefore, the treatment plan was to extract all four first bicuspids and close the spaces using sectional and closing-loop archwires with an.
No extraoral anchorage would be required. Facial esthetics were optimum for this skeletal pattern, and the teeth were positioned in the face according to the modified Steiner, Ricketts, and Radney analyses.
No jaw changes occurred in this non-growing patient Fig. Treatment time was 27 months.
The rule of thumb was accurate. Case 2 This mature year-old female had a skeletal pattern opposite to that of Case 1 Fig. She had a short lower face with a prominent soft-tissue chin. Her chief complaint was that her anterior teeth seemed protrusive when she smiled. She had a half-Class II malocclusion, a moderate overbite, and mild maxillary and mandibular arch-length discrepancies.
The mandibular incisors were 3mm anterior to NA and 2mm to APo. Treatment Planning Most orthodontists would treat this patient without extractions because of her facial features and the position of the mandibular incisors.
However, I knew that with no growth and my mechanics, her maxillary teeth would become more protrusive and produce a poor result. If the goal were to position the maxillary incisors at 5mm to NA--a 3mm retraction--the mandibular incisors would have to be retracted about 2mm to reach that goal.
Ordinarily, when mandibular second bicuspids are extracted, you can expect the posterior teeth to come forward about half the extraction space. This nets about 7. The anchorage afforded by maxillary posterior teeth is less than that of mandibular posterior teeth. Maxillary molar anchorage with first bicuspid extractions is about equal to that afforded by mandibular second bicuspid extractions. With reciprocal space closure, the molar relationship will not change. In this case, there was 1. Reciprocal space closure would have resulted in about 3mm of incisor retraction, a little more than desired.
Instead of using extraoral anchorage to correct the overjet, Class II elastics could be used to bring the mandibular posterior teeth forward 1mm or so and thus reach the goal. The treatment plan was to extract the maxillary first and mandibular second bicuspids and to correct the overjet with Class II elastics.
Uni-Twin brackets were used on the rest of the mandibular teeth. The maxillary anterior brackets were later replaced due to breakage. Results An excellent occlusion was achieved, with a beautiful smile in a beautiful face Fig. A and B points were each recontoured 1mm with the retraction of the incisors. Pogonion was at 6mm to NB, with a -2mm Holdaway difference. Treatment time was 21 months. Notice that the mandibular incisor and pogonion were both at 5mm to NB at the beginning of treatment, but at 4mm and 6mm, respectively, at the end of treatment.
Without a superimposition, the data indicate that the mandibular incisors were retracted 1mm and pogonion grew 1mm. In fact, that is not what happened. The incisors were retracted 2mm, B point was recontoured 1mm lingually, and pogonion didn't change Fig. Flattening of the mandibular plane angle, especially in low-angle cases like this one, can also lead to a misinterpretation of the raw data concerning incisor movement on the mandible and the growth of pogonion.
Rotation of the mandible rotates the mandibular incisor lingually and pogonion labially relative to NB, changing the Holdaway difference without an actual movement of the incisor on the mandible.
This contributes to the facial features observed in low-angle skeletal patterns see Case 5. Case 3 A year-old female presented with a partial Class III occlusion on the left side, a Class I molar relationship on the right side, the maxillary left lateral incisor in crossbite, and the maxillary and mandibular midlines shifted to the right Fig.
The maxillary right lateral incisor was severely rotated and in crossbite. The maxillary right canine had been extracted many years before. Both mandibular canines were blocked out of the arch, and the mandibular right lateral incisor overlapped the first bicuspid.
There was 15mm of crowding in the mandibular arch. Treatment Planning Cephalometrically, the teeth, jaws, and soft tissue were ideal, so the goal was to keep them there.
Extraction of the mandibular first bicuspids, which would yield a rule-of-thumb net 10mm of space, would require a 2. Additionally, and more troublesome, the man dibular right molar would come forward 2.
If only reciprocal mechanics were used, it would create a Class III molar relationship on the right side. If the maxillary left first bicuspid were extracted, a Class III molar relationship would result that could require surgery to resolve.
An alternative approach would be to extract mandibular canines instead of first bicuspids. Canine extractions net approximately 15mm. The entire extraction space can be used for incisor alignment and retraction, since the posterior teeth will not move forward at all. With no mesial movement of the mandibular buccal segments, the Class I relationship on the right side would be preserved. The canine space on the left side would provide adequate space to correct the mandibular midline, but would not leave space for the retraction of the anterior teeth.
In the maxillary arch, the left second bicuspid could be extracted instead of the first bicuspid. This would result in the maxillary canine moving back less and the maxillary molar moving forward more into a Class I occlusal relationship, without the need for Class III elastics.
Treatment was carried out with an Andrews-prescription. Arch length was maintained with stopped archwires during alignment of the upper and lower teeth, and all remaining spaces were then closed with closing-loop archwires Figs. Results An excellent occlusion was obtained with no appreciable change in the face or the anteroposterior position of the teeth Figs.
Treatment time was 19 months. While the cant of the incisors was practically the same in this case, the torque requirements were different because of the cant of the occlusal or archwire plane. The unusual decision to extract mandibular canines along with the maxillary left second bicuspid made this case quite simple and may have avoided jaw surgery. Case 4 This year-old female, not yet mature, had excellent facial balance, a Class I occlusion, an average skeletal pattern, and teeth ideally positioned on the jaws Fig.
All four canines were mildly crowded out of the arch. Treatment Planning My goal was to leave the teeth in their present positions. The mild crowding and forward tip of the canine roots favored the extraction of all four second bicuspids instead of a nonextraction approach.
The treatment plan was to progressively bond an Andrews-prescription. Results The patient grew considerably during the 22 months between cephalograms Fig. Nasion and the maxilla grew forward about 2mm, while the mandible grew forward about 5mm. The excess mandibular growth vs. The patient finished with the excellent facial features and balance that she had before treatment Fig.
She had an excellent occlusion with all four canines properly aligned. There was a 3mm Holdaway difference. Superimposing maxilla over maxilla Fig. The posterior teeth erupted more than the incisors and came forward about 5mm. This was more than normal because of the abnormal forward growth of the mandible. Anterior dental height increased by 5mm. Posterior dental height also increased by 5mm. Even though the incisors were retracted 1mm on the mandible, they moved forward relative to NA and remained the same relative to APo.
The teeth adjacent to the extraction sites were upright Fig. All measurements were slightly protrusive, even though teeth had been removed. Four years after treatment Fig. Case 5 This case illustrates treatment with an individualized Straight-Wire Appliance. She had a Class II, division 2 malocclusion with a deep overbite, tucked-under maxillary central incisors, and flared lateral incisors.
It has been said that this configuration locks the mandible distally, inhibiting normal mandibular growth. If so, however, why do most Class II, division 2 cases have large, prognathic mandibles like this patient? The maxillary right canine was blocked out, and the maxillary first molars were in crossbite. There was no crowding in the mandibular arch, but there was a deep curve of Spee. The maxillary central incisors had unusual crown-root angulations that contributed to the tucked-under appearance of the crowns.
The patient had little or no growth remaining. Treatment Planning The treatment plan was to leave the crowns of the maxillary central incisors in place and torque their roots lingually while torquing the maxillary lateral incisor roots labially. The mandibular incisors were to be moved forward to partially correct the overjet, and the curve of Spee was to be leveled to open the bite.
For non-surgical treatment of non-growing Class II, division 2 malocclusions, extract the maxillary first bicuspids and treat the mandibular arch nonextraction. In this case, the maxillary first bicuspids were extracted to provide space to correct the maxillary crowding and to torque the central incisor roots lingually without moving the crowns labially.
No mandibular teeth were extracted, and no extraoral anchorage was required. The Incisor Torque Template was used to establish torque goals Fig. The remaining maxillary brackets and tubes were Roth-prescription attachments bonded at standard heights. Roth-prescription brackets and tubes were bonded to the mandibular posterior teeth.
Brackets were positioned on the patient's models according to this prescription with the Slot Machine Fig. The Slot Machine holds the bracket slot in place while the tooth is positioned relative to it for tip, torque, rotation, and height. In the mandibular arch, an. No bends were placed in any of the wires, except at the maxillary left central incisor. Results The maxillary central incisor roots were torqued 5mm lingually; the crowns were elevated 2mm and retracted.
The lateral incisor roots were torqued in harmony with the central incisors and canines. The mandibular curve of Spee was completely leveled Fig. Leveling with continuous arches is supposed to open the bite, increasing lower face height by elevating the molars without depressing the incisors. Utility arches are supposed to open the bite by depressing the incisors without increasing lower face height.Carving the Maxillary Central Incisor
In my opinion, there is little difference between the two approaches. In growing patients, the lower face height generally increases more or less, depending on facial type; non-growing patients experience little or no increase in lower face height, regardless of facial type.
Analysis of Occlusion | Orthodontics: A Review | Continuing Education Course | mephistolessiveur.info
In this case, with continuous arches, the mandibular incisors were depressed 3mm and tipped forward 2mm, finishing at 0mm to APo, with a 0mm Holdaway difference Fig. There was little change in the drape of the soft tissues and, unfortunately, only a 1mm increase in lower face height. The maxillary central incisors were overcorrected to the level of the lateral incisors, and they rebounded to a normal height Fig.
The advantages of an individualized appliance should be obvious. It is almost as easy to plan and fabricate an individualized appliance as it is to fabricate a standard appliance. The mesiodistal and labiopalatal measurements for maxillary permanent lateral incisor mm are shown in Table 4.
Labial aspect It is trapezoidal in shape with the shortest uneven side toward the cervix. The contact area is located farther cervically in the incisal third, quite near its junction with the middle third. The distoincisal angle is noticeably more rounded than its central incisor counterpart, and also more rounded than its own mesioincisal angle.
It exhibits the greatest rounding of any incisor. The number and prominence of mamelons is variable, but two are the most common finding.
The root apex is inclined distal to midline. It is narrow mesiodistally than that of maxillary central and usually as long as or somewhat longer than that of the central. Surface anatomy The labial surface itself is more convex both mesiodistally and incisocervically than the maxillary central. Labial developmental grooves, and imbrication lines are often present, similar to those of the central incisor but are less prominent. Labial aspect of maxillary permanent lateral incisor.
Palatal aspect It is trapezoidal in shape with the smallest uneven side toward the cervix. Surface anatomy The mesial and distal marginal ridges, as well as the cingulum, are relatively more prominent, and the palatal fossa is deeper, when compared to the same structures of the central incisor. A palatocervical groove is a more common finding in maxillary lateral incisors than in central incisors.
A palatal pit, near the center of this groove, is also more common, and when present, is a potential site for caries. The palatocervical groove usually originates in the palatal pit and extends cervically, and slightly distally, onto the cingulum.
Palatal aspect of maxillary permanent lateral incisor. Geometric outline It is triangular in shape with the wide base at the cervix and narrow apex at the incisal tip. The incisal tip is on one line with the root apex. Surface anatomy The crown is shorter, and the labiopalatal measurement of the crown is smaller. The contact area is also similar in shape to the contact of the central incisor.
Mesial aspect of maxillary permanent lateral incisor. Surface anatomy The distal surface is smaller and more convex in all dimensions than the mesial surface. The contact area is shorter and not as incisally placed, when compared to the mesial contact.
Distal aspect of maxillary permanent lateral incisor. Incisal aspect In incisal view, this tooth resembles the central incisor to varying degrees. The tooth is narrower mesiodistally than the maxillary central incisor; however, it is nearly as thick labiopalatally. The incisal outline is more rounded labially and palatally than the central incisor. Incisal aspect of maxillary permanent lateral incisor.
Mesiodistal section The pulp cavity nearly follows the external shape of the tooth. When viewed from the labial aspect of the tooth, the pulp horns appear to be blunted.
The pulp chamber and root canal taper evenly and gradually toward the root apex. In the apical portion, the root often shows a significant curvature.
Labiopalatal section The anatomical feature is almost identical to that of the central incisor. Generally, the pulp cavity of the lateral incisor closely resembles the outline form of the crown and the root.
The pulp projections are usually well developed and prominent. In the incisal region, the pulp chamber is narrow, and at the cervical level of the tooth it may become very wide. When the cervical enlargement of the pulp chamber is lacking, the root canal tapers slightly to the apical constriction at the root tip. Many of the apical foramina exit on the labial or palatal aspect of the root. Cervical cross section The cervical cross section shows the pulp chamber to be centered within the root.
The root form of this tooth shows a large variation in shape. The outline form of this tooth may be triangular, oval or round. The pulp chamber generally follows the outline form of the root, but secondary dentin may narrow the canal significantly [ 9 ] see Figure Pulp cavity for the mesiodistal, labiopalatal, midroot and cervical sections of maxillary permanent lateral incisor.
Tooth sockets The second socket from the midline is that of the lateral incisor. It is generally conical and egg-shaped, or ovoid, with the widest portion to the labial. It is smaller on cross section, although it is often deeper than the central alveolus.
Sometimes, it is curved at the upper extremity [ 10 ]. Occlusion The upper lateral incisors are usually located labially to the mandibular teeth when the mouth is closed.
The upper lateral incisor occludes with the distolabial half of the mandibular lateral and with the mesiolabial inclined plane of the mandibular canine [ 11 ]. Variation The incisal portion of the cingulum may exhibit a tubercle. Palatocervical fissure may extend all the way onto the root surface from the adjacent cingulum.
Distorted crowns and unusual root curvatures are more commonly seen than with any other incisor.
Permanent Maxillary and Mandibular Incisors
A diminutive peg-shaped crown form, which is relatively common, and is due to a lack of development of the mesial and distal portions of the crown. Maxillary laterals sometimes are congenitally missing, that is, tooth buds do not form.
The palatal pit of the maxillary lateral may be the entrance site where enamel and dentin have become invaginated in the tooth's pulp cavity, due to a developmental aberrancy called dens in dente [ 1 ]. Permanent mandibular central incisor 5.