Lateral incisor deformity

Some people find that their teeth are very straight, but their lateral incisors are deformed. If the lateral incisor deformity does not affect chewing, there is no problem if you do not undergo correction. But sometimes, lateral incisor deformity will seriously affect our daily life. At this time, we need to correct the lateral incisor. So, how to correct deformed lateral incisors?

Diagnosis of An

Class II1 malocclusion; crowded dentition; mandibular retrusion; 12, 22 small teeth; individual teeth crossbite.

Correction goal

1. Establish a neutral occlusal relationship between canines and molars.

2. Establish a normal overbite and overjet relationship of the anterior teeth.

3. Relieve dental crowding, eliminate crossbite of individual teeth, and align the upper and lower teeth.

4. Correct the center line.

Correction plan

1. Full-mouth straight wire correction technology;

2. Orthodontic treatment: extract teeth 12, 22, 35, 45, use the extraction space to relieve crowding in the upper and lower jaws, align and level the dentition, retract the anterior teeth in the upper jaw, adjust the midline of the lower jaw, and adjust the molar relationship;

3. Anchor design: maxillary transverse palatal bar, mandibular lingual arch;

4. After the correction, positions 12 and 22 will be replaced by positions 13 and 23.

5. After the patient reaches adulthood, genioplasty surgery may be performed as appropriate.

Correction process

1. Orthodontic treatment was started after tooth extraction according to the treatment plan, using 0.022-inch (1 inch = 2.54 cm) straight wire brackets.

2. Adhesion anchorage device, first perform maxillary fixed correction, align the upper teeth with nickel-titanium round wire, and adjust the 13 and 23 shapes in batches. The treatment course is 3 months.

3. Replace the nickel-titanium square wire in the upper jaw to fully align and level the dentition; glue the mandibular bracket and use the nickel-titanium round wire to align the lower dentition in sequence. The treatment course is 4 months.

4. Maxillary stainless steel square wire, to retract the anterior teeth; mandibular 0.45-inch stainless steel round wire, to adjust the mandibular midline and move the posterior teeth mesially. The treatment course is 3 months.

5. Fine-tune the occlusal relationship. Class II traction was used between the jaws to adjust the molar relationship; box-shaped traction was used in the anterior teeth area to deepen the overbite relationship of the anterior teeth; occlusal interference was checked and the 14, 24 mesial marginal ridges and palatal cusps were adjusted. The treatment course is 5 months.

6. The upper and lower jaws are maintained with Hawley retainers. The total course of treatment is 15 months.

Correction results

After correction, the patient's bilateral molars and canines reached a neutral relationship, the overbite and overjet relationship of the anterior teeth was normal, the upper and lower teeth were arranged neatly, and the upper and lower midlines were centered and aligned. The post-treatment image, intraoral image, full-mouth curved cross-sectional film and lateral head film after treatment are shown in Figure 2, the overlapping cephalometric images before and after treatment are shown in Figure 3, and the cephalometric values ​​before and after treatment are shown in Table 1.

Correction experience

Malformed lateral incisors are common in clinical practice, and the treatment options are also diverse. Tooth extraction treatment, mesial movement to close the gap, or restorative treatment after opening the gap are all widely used in clinical practice. In this case, the deformed lateral incisors were extracted to preserve the natural dentition. After the correction, there was no restoration in the mouth, the teeth were neatly arranged, and the occlusion was good. But there are still some problems:

1. The maxillary canines replace the lateral incisors, etc., which destroys the traditional canine-protected occlusion. Alexander believes that when the canines are ground into lateral incisor shapes and the first pair of canines are moved close to the canine position, the patient will then have a functional occlusion. Both occlusal relationships can maintain the health of the dental system. However, moving the canines mesially to the lateral incisor position does change the original position and function of the maxillary teeth.

2. There is a bone depression between the maxillary central incisor and canine. Because the deformed lateral incisor is located on the palate side, a bone depression is caused between the canine and the central incisor (Figure 1 is the orthostatic occlusal image before correction). However, after the canine was moved mesially, bone remodeling occurred and the depression gradually became shallower (Fig. 2 Orthodontic occlusal image after correction). Five months after the correction, the depression continued to become shallower (Fig. 4).

3. The maxillary dental arch is pointed and round. After the canine replaces the lateral incisor, it is equivalent to bending from the distal end of the lateral incisor, so the dental arch shape tends to be pointed and round.

4. The chin is still retracted in profile. Although the patient's front teeth have achieved normal overbite and overjet after correction, the retrusion of the chin has not changed, which requires the patient to undergo genioplasty surgery in adulthood.

5. The front teeth area is not beautiful enough. Even though camouflage correction was adopted during the treatment process (starting to change the canine shape early, grinding in multiple times; coordinating the Bolton proportions of the anterior teeth, and performing appropriate interproximal deglazing), there is still a certain degree of impact on the aesthetics in terms of shape and size. In addition, under normal circumstances, the gingival margin of the anterior teeth should be lower than that of the lateral incisor, which is also difficult to achieve when replacing lateral incisors with canines.

6. Control of individual tooth torque. The preset torque for the canines on the straight wire appliance is a negative torque in the lingual direction of the crown, while the preset torque for the lateral incisors is a positive torque in the labial direction of the crown. After the canine replaces the lateral incisor, the torque of individual teeth should be added, but it still cannot achieve the normal crown-lip positive torque.

If the patient chooses to remove the maxillary first premolar, the maxillary teeth will remain in their original position and function, the anterior area will be more beautiful than it is now, and the dental arch will be oval in shape. However, the problem of chin retraction in profile cannot be solved. In addition, after the correction, the deformed lateral incisors need to be repaired with crowns.

Robertsson et al. believe that from the perspective of periodontal health, in order to avoid periodontal and temporomandibular joint problems caused by restoration, restorative treatment should be avoided as much as possible. In clinical work, how should we choose between extracting lateral incisors or bicuspids for such patients? The author believes that: First, we should consider the abnormalities of the malformed lateral incisors (position, size, shape, root and health, etc.). Secondly, consider the patient's aesthetic requirements, etc. Finally, in today's highly developed society and economy, doctor-patient communication is particularly important. We should inform patients and their families of the advantages and disadvantages of various treatment options and let them participate.

In short, there are many clinical treatments for deformed lateral incisors, and only by developing an individualized plan based on the patient's actual situation can the best effect be achieved.