Introduction

Class III malocclusions may manifest with various combinations of skeletal and dentoalveolar components. Most class III malocclusions are associated with underlying skeletal relationships [1, 2]. The following are some of the commonly seen skeletal features, A short or retrognathic maxilla, long or prognanthic mandible and combination of the above, this due to rapid and lack of early control growth of mandible during pre-adolescence to end up with skeletal class III malocclusions, class III malocclusions are said to have a very strong genetic base [3]. Diagnostic procedure should help in determining the type of class III malocclusion i.e. dental or skeletal, true or pseudo. The clinical diagnosis should include observation of the path of closure. In addition, study models, radiographs, frontal and lateral cephalometric should be also taken. The ANB angle is normal. In case of skeletal class III malocclusions, the lateral cephalometric gives us valuable information in its diagnosis. These patients often exhibit a smaller than normal SNA and a larger SNB angle and exhibit a negative ANB [4].

This report the case of a patient with skeletal and dental class III malocclusion, reverse overjet and overbite who did not accept a combination of orthognathic surgery and orthodontic therapy which is considered the gold standard treatment in such a case. Based on the patient’s request, the patient was treated with clear aligners to achieve dental compensation by applying the sequential distalization protocol of the lower arch teeth. At the end of the treatment, an improvement of the overbite, overjet, crossbite and class III molars was achieved with retroclination of the lower incisors to correction and improve upper and Lower jaws relationship pattern and we have had good results using clear aligner.

Recently, the demand from orthodontic patients for clear aligners instead of traditional braces has increased, and the reason behind this is the more aesthetic and more comfort [5].

Case report: An extract from the medical history of a patient from iOrtho Center Moscow. Diagnosis: A 28-year-old patient had skeletal and dental class III malocclusion, anterior and posterior crossbite and revers overjet, moderate crowding in both jaws, traumatic occlusion. This produced not only functional and aesthetic alterations but also occlusal trauma and incisor wearing.

In the image (Fig. 1, a) shows midline shifting and facial aesthetic midline landmarks not on same way, the center point of chin GN located left of the descending vertical line, and according to upper central incisors the vertical midline located on the ¹/₃ of upper right central incisor, also the smile arc of upper incisor edges not parallel to lower lips.

Fig. 1. Midline shifting and misalignment of facial aesthetic landmarks (a), Lip positioning and facial profile assessment based on the Ricketts line (b).

According to aesthetic standards, the Ricketts line suggests that the upper lip should be approximately 4 millimeters behind the line, while the lower lip should be about 2 millimeters behind it (Fig. 1, b).

This picture reveals two defects: the first is the lower lip touching the Ricketts line, indicating a protrusion of the lower anterior teeth or mandibular prognathism; the second is a concave facial profile, which is also indicative of Class III malocclusion [6].

Pretreatment facial and lateral photographs with smile shows forward protruded posture of the lower lip due to mandibular prognathism, asymmetrical smile arc due to midline shifting and mild concave facial profile (Fig. 2) [7].

Fig. 2. Pretreatment photographs.

a — facial view, b — lateral view showing mandibular prognathism and asymmetrical smile arc, c — corner view.

Pretreatment photographs show protrusion of mandibular arch with overjet –1.2, crowding on the upper right segments, misalignment of teeth with irregular gingival margins line, cross bite on 1.2, 1.4, 1.5—4.7—3.5, Thus posterior cross bite occurs as a result of luck of co-ordination in the lateral dimension between the upper and lower arches, midline shifting (Fig. 3) [8, 9].

Fig. 3. Pretreatment photographs showing (a) mandibular arch protrusion, (b) crowding, misalignment, and posterior crossbite.

Treatment goals:

1. Correction of the class 3 malocclusion and improve interincisal relationship by the segmental distalization of lower segments using clear aligner and the anchorage devices.

2. Correction of the cross bite.

3. Correction midline shift.

4. Correction of the smile arc.

The orthodontic compensatory treatment plan was as follows (Fig. 4):

Fig. 4. Treatment plane, the patient was offered two treatment options and the second one was chosen by the patient.

1. After presenting more than one option to the patient regarding teeth extraction we decided to extract 3rd four molars 1.8, 2.8, 3.8, 4.8 to gain the required space for mandibular set back. Considering the limits of the relationship between incisors, canines, and molars, to achieve a class 1 relationship between both jaws.

2. Expansion of upper and lower posrerior teeth to relieve crowding in the early stages of treatment.

3. Precision cuts and button cutouts, buttons cutouts are requested in first upper molars and precision cuts in lower canines, elastics from upper 6 to lower 3 will create a mesial force on the entire maxillary arch and a distal force on the mandibular arch.

4. Expansion of the upper and lower dentition to get rid of the crowding and cross bite together.

5. Sequential Distalization of the lower teeth, preformed by using of microscrew in the retromolar zone (a larger amount of distalization was performed on the lower right quadrant, the reason is to correct midline left shifting of lower segments)

6. Retraction of the lower anterior dentition.

7. Correction of the curve of spee by controlling the vertical movement (intrusive and extrusive) of anterior and posterior teeth.

8. Improving the position of the cosmetic canter of the lower jaw.

9. Light short triangle and box elastics were used to rectify the posterior segments relationships.

10. Retention.

Results

The treatment was completed after one year and eight months. The results typically appear 9—12 months after retainer as a complementary phase to the treatment. It’s worth noting that the results were excellent and exactly as planned. we got a class 1 molars and canine relationships (Fig. 5), regular gingival line, positive overjet and overbite, without any anterior and posterior cross bite, normal curve of spee range about 2 mm.

Fig. 5. Intraoral photographs after treatment.

a — frontal view showing the midline shifting has been corrected; b — right lateral view class 1 molars and canine relationship; c — left lateral view.

There is an improvement in the cosmetic center of the mandible and correction of the inclination of the occlusal plane (Fig. 6).

Fig. 6. Frontal view before treatment (a) and showing an improvement in the mandibular cosmetic center and correction of inclination of occlusal plane (b).

The convexity angle of the face after treatment is in the range from 165 degree to 175 degree, which is typical for physiological occlusion (Fig. 7).

Fig. 7. Patient’s profile before treatment (a) and after treatment (b), the convexity angle of the face after treatment is in the range from 165 degree to 175 degree, which is typical for physiological occlusion.

The lower lip after treatment recedes 1mm from the E-line, which is typical for the harmonious position of the lower lip. In the end, class 1 relationship was achieved in both jaws. The number of aligners used to treat this patient included the following:

— There were 39 pairs of main aligners. Additional 16 pairs (Fig. 8).

Fig. 8. Intraoral photographs during the ordering of additional aligners maxillary arch form (a), mandibular arch form (b).

— 24-hour class III elastics were worn on the first set of aligners.

Discussion and treatments tips

The aim of this study is to clarify the extent of the impact of clear aligner on the treatment of such cases that are not considered simple. Many dentists around the world are now moving towards developing their practical skills and interest in 3D technology and using clear aligners. The reason behind this is the increasing demand for it by patients in recent years, in addition to the ease of dealing with this technology if the dentist is interested and has experience and competence [10]. But on the other hand, there are many dentists who do not want to delve into this technology or engage in the digital world of dentistry, which is growing very quickly. The reason is that this group of dentists say, in their opinion, that there is not enough time to learn how to deal with this technology, but in fact they spend a lot of time inside the clinic with traditional braces [5]. The second group says that clear braces only treat simple cases. This last reason is what prompted me to share this case which is not very difficult but also not simple. Skeletal and dental class III malocclusion, reverse overjet — 1.2, anterior and posterior cross bite, mild crowding, midline shift of lower segments [7]. Finally, all these defects have been corrected using clear aligner with sequential distalization of lower segments.

— Lower distalization is predictable up to 2 mm.

— It is necessary to extract third lower molars before distalizing the lower arch. This, as happens with class II when extracting upper wisdom teeth, takes advantage of the rapid acceleratory phenomenon to speed up distalization.

— The best approach is to take the scan/impressions after extracting the third lower molars: that way the distal surface of the second lower molar will be completely registered and therefore covered by the aligner.

— Full-time wearing of elastic from upper first molars to lower canines will be necessary from the beginning of lower distalization.

— In cases of lower distalization of 3 mm or more, a microscrew in the retromolar zone will be necessary [11—13].

Posterior crossbites in this case were caused by functional lateral shift of the mandible. When it comes to treating transverse problems with Invisalign clear aligners, it is important to remember that correction of dental cross bites is more predictable than skeletal cross bites [14—16]. Check treatment plan follows sound orthodontic principles that will help you achieve predictable cross-bite correction in the right cases and avoid frustration in those patients where correction is less predictable. The use of cross elastics and 2mm of expansion over treatment will increase the predictability of correction of transverse dimension problems, reduce the number of case refinements, and help achieve excellent results on a consistent basis [15].

When we want to resolve crowding in a patient, we only have a limited number of options to choose from. Those options are as follows; expansion, which lateral widening of the posterior teeth, proclination, which refers to labial movement of the upper and lower incisors, interproximal reduction (IPR), extraction of a tooth or several teeth. The crowding section of the ClinCheck list helps guide you through the thought process to resolve the crowding problem [17]. In cases that present with crowding these four methods are the only four options for resolution. We must select one or more of these methods to resolve crowding.

Conclusion

Clear aligners can be an effective treatment option for Class III malocclusions, and they must be carefully selected by a specialist. A comprehensive clinical diagnosis of the patient, a thorough understanding of the Invisalign system and its management, as well as the associated appliances, and precise definition of treatment goals are all important steps that must be carefully considered during orthodontic treatment.

Participation of authors:

Concept and design of the study — Mohammed H.H., Loktionova M.V., Kazaryan A.F., Kheygetyan A.V.,

Chekalina T.L.

Data collection and processing — Mohammed H.H., Loktionova M.V., Kazaryan A.F., Heigetyan A.V., Chekalina T.L.

Text writing — Mohammed H.H., Bagatelia Z.T., Salman I.J., Ivanova N.D.

Editing — Mohammed H.H., Bagatelia Z.T., Salman I.J, Ivanova N.D.

Участие авторов:

Концепция и дизайн исследования — Мохаммед Х.Х., Локтионова М.В., Казарян А.Ф., Хейгетян А.В., Чекалина Т.Л.

Сбор и обработка материала — Мохаммед Х.Х., Локтионова М.В., Казарян А.Ф., Хейгетян А.В., Чекалина Т.Л.

Написание текста — Мохаммед Х.Х., Салман И.Дж., Багателия З.Т., Иванова Н.Д.

Редактирование — Мохаммед Х.Х., Салман И.Дж., Багателия З.Т., Иванова Н.Д.

Авторы заявляют об отсутствии конфликта интересов.