2020, Number 4
Severe crowding treatment without extractions with Damon® self-ligating system: case report
Full text
Language: English/Spanish [Versión en español]
References: 24
Page: 271-281
PDF size: 477.00 Kb.
ABSTRACT
Introduction: treatment planning for a class II malocclusion with severe crowding will be determined by clinical dentistry analysis, assessing the collateral effects on a force system and assessing their impact on the soft tissues. Objectives: maintain facial profile, uncross right side bite, eliminate crowding, establish class I canine and class I molar. Diagnosis and treatment plan: male patient, 13 years old, permanent dentition. Unilateral class II canine on the right side, severe crowding, right unilateral posterior crossbite. Placement of self-ligating appliances, bite turbo, initial class II elastics and palatal buttons for cross elastics. Results: the crossbite was corrected and class I canine was achieved while maintaining the patient's straight profile. Conclusion: this report shows that the correction of severe crowding and unilateral class II can be carried out without extractions, achieving an adequate functional and aesthetic result. Furthermore, it is possible to accomplish this correction taking advantage of the benefits provided by the self-ligating system.INTRODUCTION
Angle defined single-sided class II malocclusion as a relationship of unilateral class II1 and class I on the other side.2 Usually, we can observe a more distal unilateral position of the mandibular molar, while the maxillary molars could be in a correct position with respect to their contralateral or be mesialised.2,3 The aetiology of unilateral class II malocclusion with severe crowding is more related to a dentoalveolar origin (due to premature loss of deciduous teeth, trauma, agenesis, etc.). In smaller percentages it can be related to slight skeletal asymmetries, distal positions of the condyles in glenoid fossa, as well as problems of neuromuscular alterations.4 The prevalence of class II malocclusion is approximately 41% of all malocclusions, and within the class II group, unilateral malocclusion has a frequency of 25% with a 1:2 ratio between males and females, respectively.5
The treatment of these malocclusions is a challenge, as mentioned by several authors2,4 because of all the complications that can occur in each case. Treatment plans for class II malocclusion with severe crowding have focused on the patient's facial diagnosis and existing severity.6
It is necessary to assess the need for space to determine whether tooth extraction is required.7 In multiple case reports of unilateral class II cases, unilateral extraction has been one of the approaches of choice, however, the magnitude of the midline deviation, the magnitude of the class II canine and the Bolton discrepancy must be considered.5 Non-extractive treatments include the use of extra-oral appliances, functional and orthopaedic appliances, class II elastics, distalisation appliances, temporary anchorage devices and others.4-5,8-13
An alternative reported in various articles14-16 is the use of self-ligating bracket appliances, due to the advantages they offer, the best of which is that they generate reduced friction between the arches and the brackets.16,17 Due to the reduced friction, it is considered that they can achieve greater arch expansion with less incisor proclination, and facilitate the resolution of certain crowding, sometimes without the need for extractions.18
When planning treatment, three aspects should be taken into account that will greatly improve the quality of the results: selection of variable torques, disarticulate the occlusion with bite turbo and the use of light elastics from the early phases of treatment. The use of light elastics in combination with bite turbos has a positive impact on anteroposterior, vertical and transverse corrections.16
The purpose of this article is to show the anteroposterior and transverse control that was maintained in a unilateral severely crowded class II patient with right unilateral posterior crossbite, treated without extractions and with the biomechanics of the Damon® self-ligating system, using class II elastics, from the initial stage of treatment.
CLINICAL CASE
Male patient, 13 years 10 months old, with no relevant medical history, who attended the orthodontic clinic for consultation "I want to adjust my tooth". In the extraoral analysis, the patient presented a straight profile, incipient dolichofacial biotype, enlarged lower third, cheekbones without projection (Figure 1A). In the intraoral examination the patient presented permanent dentition, class II molar and class II canine on the right side, class I canine on the left, upper and lower tapered arch form, large and square teeth, upper midline deviation by 2 mm to the right, overjet 3 mm, overbite 2 mm (Figure 1B). In the analysis of models in the Bolton study, he presented maxillary excess of 3.2 mm, arch length discrepancy -6 mm superior and -2 mm inferior, with severe maxillary anterior crowding (Figure 2). In terms of functional diagnosis, the patient presented onychophagia, but no alterations in the temporomandibular joint.
Radiographically, the orthopantomography showed symmetrical mandibular branches, symmetrical condyles, healthy bone ridge levels, presence of third molar tooth germs in all four quadrants, crown-root ratio of 1:1 and conical roots (Figure 3A). In the lateral skull radiograph, Steiner cephalometry was drawn with Dolphin Imaging (software 9.0.00.19©1998-2004 Patterson Companies, Inc.), where a class I skeletal was observed, patent upper airways, straight profile and slightly retroclined lower incisors were observed (Figure 3B and Table 1).
The aim of the treatment was to maintain facial profile, uncross bite on the right side, eliminate crowding, establish class I canine and class I molar, achieve upper and lower oval arch form.
Alternative treatments:
- 1. Use of Damon® self-ligating appliances, using early elastics, without extractions, and taking advantage of transverse expansion with copper nickel titanium (CuNiTi) archwires to incorporate the canine into the arch.
- 2. Performing the extractions to obtain the necessary space to include the canine in the arch.
The treatment began by placing self-ligating Damon® system slot 0.022" brackets, with upper and lower tubes on first and second molars, posterior bite turbos and palatal buttons on dental organs #14, #15 and #16.
Without including the upper right canine to the archwire, a coil spring was placed from lateral to right premolar, the archwire used at the first appointment was a CuNiTi 0.016" for three months (Figure 4). Alignment proceeded with a 0.018" upper CuNiTi archwire and early ¼ 2.5 oz elastics were placed from upper canine to canine and lower premolar with a class II vector.
The canine was then incorporated into the arch and placed in a 0.014" CuNiTi archwire. Once incorporated into the arch, it was moved to a 0.018" CuNiTi archwire and continued with the use of light weight class II vector elastics ¼ 2.5 oz. CuNiTi.
Three months later, a 0.014" × 0.025" CuNiTi upper and 0.018" CuNiTi lower archwire was placed (three months). Then, the archwire was changed to a 0.018" × 0.025" CuNiTi upper and lower archwire, and a button was placed on the upper right first molar for the use of cross elastic to the lower right first molar 3/16 4.5 oz (Figure 5). After three months the bite turbos were removed and 0.018" × 0.025" steel upper and lower archwires were placed (Figure 6). Finally, the appliances were removed and a fixed lower retainer and upper essix retainer were placed.
RESULTS
The treatment objectives were achieved: the posterior bite was uncrossed on the right side; class I canine, class I molar, and both upper and lower ovoid arch form were established; and the patient's facial profile was maintained (Figure 7). The radiograph showed good root parallelism (Figure 8A), and the superimposition of final lateral skull radiograph, showed a better anteroposterior relationship (Table 1, Figure 8B and C).
DISCUSSION
The use of light force mechanics produces a more biologically stable result, considering that keeping the teeth within an "optimal force zone" allows the lips to be able to control the position of the incisors. This results in the arch form aligning, taking the path of least resistance, i.e. posterior expansion, and resulting in a wider arch form.16 Birnie18 mentions that being able to combine these factors allows treatment to be carried out without the need for extractions. Some studies have evaluated the transverse changes with the use of high-tech archwires such as CuNiTi, and when using a self-ligating system, they show significant transverse development in the premolar and first molar areas. This is how the necessary space is obtained to alleviate crowding greater than 4 mm, without the need for extractions.19,20 In our case, we observed the success of the treatment, obtaining an arch length discrepancy of -6 mm superior, managing to incorporate the canine into the arch and also establishing a correct class I canine.
Atik and Ciger20 compared 16 women treated with self-ligating appliances against a group of 17 women in which a Quad-Helix was used together with conventional appliances in the maxillary arch. A very similar expansion was observed in both groups, characterised by a vestibular dental inclination due to the shape of the arches. In our patient, we were able to have full transverse control, as he had a posterior crossbite, without the use of any additional appliances.
For the treatment of our patient's unilateral class II, according to the diagnosis of the origin of the asymmetry (dentoalveolar or skeletal), we are inclined to choose the option of no extractions, taking into account the type of profile and the labial position.
The literature indicates that21,22 class II elastics, the use of sliding jigs, micro-implants, and segmented arches, among others, have been shown to be a good option with favourable results for unilateral class II treatment. Our report demonstrates the correction of class II with the sole use of early elastics with light forces. According to Janson et al.,23 class II elastics are effective for the correction of class II malocclusions, because the effects of their use are mostly dentoalveolar. Furthermore, they lead to lingual inclination, retrusion and extrusion of the upper incisors, and vice versa with the mandibular incisors; as well as mesialisation and extrusion of the mandibular molars. However, they conclude that no attention has been paid to the effect on the soft tissues. In our case, there was no marked extrusion of the upper incisor and no gingival smile, as one might think might occur.
With respect to the soft tissues, Janson et al24 compared cephalometrics to observe changes in the treatment with premolar extractions and observed that a retraction of the upper lip and an opening of the nasolabial angle occurred. The initial profile of our patient and the effects of extractions on the soft tissues were important factors in considering treatment without extractions.
CONCLUSIONS
This report suggests that the correction of unilateral class II dental malocclusion with severe crowding can be resolved without the need for extractions. An adequate functional and aesthetic result was achieved, fulfilling the treatment objectives proposed at the beginning, correcting the unilateral posterior crossbite, and achieving class I canine and class I molar with the use of elastics and the implementation of self-ligating appliances without extractions. It is possible to carry out this correction knowing the benefits of a frictionless system, good patient cooperation, taking into account the biomechanics used to be able to control both the reaction to the force applied, and all the stages of the treatment.
REFERENCES
AFFILIATIONS
1 Alumno de la Especialidad en Ortodoncia. Departamento de Clínicas Odontológicas Integrales. Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. México.
2 Egresada de la Especialidad en Ortodoncia. Departamento de Clínicas Odontológicas Integrales. Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. México.
3 Profesor de la Especialidad en Ortodoncia. Departamento de Clínicas Odontológicas Integrales. Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. México.
CORRESPONDENCE
Carlos Orozco Varela. E-mail: carlosorozcovare@hotmail.comReceived: Julio 2021. Accepted: Febrero 2022.