2020, Number 1
Anterior open bite correction of skeletal class III malocclusion. Case report
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ABSTRACT
Introduction: Open bite is a lack of vertical overlap between both incisors. This type of vertical problem can be due to various environmental factors or certain habits. Case presentation: 15-year-old female patient who reported discomfort with the appearance of her teeth. She presented a dental anterior open bite, convex profile, a normocephalic facial biotype, class I molar and class II canine relations bilaterally, and a class III skeletal malocclusion due to maxillary hypoplasia, compensated skeletally by vertical growth of the mandible. Extraction of the upper and lower first premolars was performed, followed by cementation of fixed appliance MBT 0.022", the alignment stage began with round nitinol archwires in 0.014" and 0.016" size, and then levelling with a 0.019" × 0.025" nitinol archwire. The gap closure was done with active tie back on the lower side with a 0.019" × 0.025" arch. In the upper, on the left side with a tie back and on the right side with a closing loop. Interproximal reduction (stripping) was performed and intermaxillary elastics were used. Results: After one year and 10 months of treatment results were obtained. The most significant changes were obtained in IMPA and Wits appraisal. Conclusion: Open bite will always be a difficult challenge for the orthodontist, the key to success lies in the diagnosis and aetiology.INTRODUCTION
Open bite is a lack of vertical overlap between the two incisors and is quantified by measuring the gap between the two incisors. This type of vertical problem can be due to various environmental factors or habits.1 This dentofacial alteration can be caused by an abnormal growth pattern, finger habit, airway obstruction or tongue malposition.2 The prevalence ranges from 1.5 to 11% and although it is a small percentage, the demand for treatment of this type of malocclusion is very common, with approximately 17% of orthodontically treated patients presenting with anterior open bite.3
The main problems presented by these patients are decreased dental aesthetics, eating problems, involuntary spitting when speaking, wear of the molar cusps and also self-esteem problems. Orthodontists have recognized that anterior open bite is difficult to treat and tends to relapse post-treatment.4 It was reported that more than 35% of patients treated with conventional orthodontics had a relapse of 3 mm or more at 10 years of retention.5
There are two types of open bite, the dental type and the skeletal type. The dental type is characterized by occurrence in the anterior region, from canine to canine, and is associated with a normal craniofacial pattern, pro-inclined incisors, lack of eruption of the anterior teeth, infantile swallowing and, thumb or finger sucking habits. The skeletal type presents normal eruption of the anterior teeth, downward rotation of the mandible, excessive eruption of the posterior teeth, cephalometrically an excessive anterior facial height can be observed and it is also associated with digital sucking habits and atypical swallowing.1
The contact between premolars is the ideal reference point for the occlusal plane and this will help to obtain a successful and stable treatment.6
Open bite is a difficult problem to treat and recurrence is a factor to consider as it occurs in a high percentage. Several authors describe different types of treatment to correct this problem, such as the use of spurs, myofunctional therapy, aligners, occlusal adjustment, zygomatic anchorage, molar intrusion with mini-implants and multiloop arches.4,7-13
Over eruption of molars was reported in patients with open bite compared to patients with adequate overbite, proinclination of upper incisors and retroinclination of lower incisors in class III patients.14
Satisfactory open bite correction with molar intrusion was also observed, but 0.5 to 1.5 mm of reeruption of these teeth was likely to occur.15
One treatment option is the extraction of the upper and lower first molars in order to decrease the vertical dimension and increase the anterior facial height.16
We present the case of a normocephalic skeletal class III patient with anterior open bite, who was treated with upper and lower first premolar extractions.
CLINICAL CASE
Diagnosis and treatment plan. A 15-year-old female patient, with no relevant medical history, comes to the Orthodontic Clinic of the Autonomous University of Guadalajara and the reason for her consultation is that she does not like the appearance of her teeth.
In the anthropometric analysis we found that the patient is euriprosopic with a convex profile, the upper third diminished, the buccal width coincides with the inter-iris distance, asymmetrical smile, labial competence, straight nose and forehead, lower lip slightly in front of the aesthetic facial line, short cervicomental distance and depressed molars as shown in Figure 1A.
Within the intraoral analysis we found a more marked anterior open bite on the right side, irregular gingival margins, non-coincident dental midlines and the lower one deviated with respect to the upper one by 2 mm to the right, overjet and overbite of -4 mm and 3 mm respectively, right and left class I molar and bilateral class II canine relationship, oval upper arch with severe crowding in the anterior sector, dental organ #22 in crossbite, oval lower arch with slight crowding and a Spee's curve of 1 mm as shown in Figures 1B and 2.
The panoramic radiography shows the presence of a supernumerary tooth inside the mandibular bone on the left side between the second premolar and the first molar, which will be removed when the treatment is completed; slight root parallelism, presence of tooth germs of the upper and lower third molars as shown in Figure 3A. In the lateral skull (Figure 3B) the Steiner cephalometric analysis was used, giving an ANB of 5o and GoGn-SN of 45o and a Wits of -6 mm. With the data obtained, the patient was diagnosed as class III due to maxillary hypoplasia compensated skeletally by vertical growth of the mandible as shown in Table 1.
During the examination it was observed that the upper right central incisor was well above the occlusal plane, which led us to think that it was possibly ankylosed, however, the patient had not reported any type of digital sucking habit. The patient's parents were informed of the findings, as if the tooth did not move during treatment, it would have to be extracted and would need to be assessed for the placement of an implant or fixed prosthesis.
Treatment goals. Close the open bite, uncross the dental organ #22, coordination of both arches, maintain class I molar on both sides and achieve class I canine right and left.
Treatment plan. Consisted of extraction of the upper and lower first premolars, MBT slot 0.022" appliance. Alignment and levelling phase, space closure, occlusion detailing and final retention (upper and lower removable).
Treatment progression. We started with the extraction of the upper and lower first premolars, then the conventional metal brackets MBT slot 0.022" were cemented to start the alignment and levelling phase.
After four months of treatment the levelling of both arches was completed with a 0.019" × 0.025" nitinol arch in both arches, and at this point we proceeded to begin space closure with 0.019" × 0.025" stainless steel archwires and crimpable clasps with passive lace backs. After another month of treatment, the arch was activated with an elastic chain. All spaces were closed except the upper right quadrant.
The closure of the right side was performed with a closing arch with a 0.017" × 0.025" loop, as we had problems with the active tie back to perform the closure. Posterior disoccluders were placed to unblock the occlusion. Month by month the loop was activated until the closure was completed as shown in Figure 4.
After the missing space was closed, the posterior disoccluders were removed and interproximal stripping was performed with sandpaper between dental organs #15 and #13; this was done to achieve a better engagement of the class I canine. This procedure was carried out for three months and then an intermaxillary elastic was placed with a class II vector on the same side. In the finishing phase, vertical elastics were placed to complete the treatment as shown in Figure 5.
RESULTS
Extraorally there was a decrease in the projection of the upper lip which helped to improve the facial profile and the most significant changes were intraoral. The open bite was closed with excellent aesthetic results, the class I molar relationship was maintained, the class I canine relationship was achieved with its respective canine guide and an overjet and overbite of 2 mm (Figure 6). The total treatment time was one year and 10 months uninterrupted, finishing the case with the open bite corrected, with a class I molar and canine relationship, and canine guidance established (Figure 7A). Cephalometrically the most significant changes were in the upper incisors which were retroinclined by 8 mm, while the IMPA was 88o and the Wits by -1 mm (Table 1), Figure 7B and the overlay in Figure 8 show the patient's dental and skeletal changes. It should be noted that the patient showed an improvement in her self-esteem; at the beginning she was serious and as she saw how her appearance was improving, she showed a more positive attitude and arrived with a very noticeable enthusiasm to her control appointments. At the end of the treatment, the patient was referred to the maxillofacial surgery service for extraction of the supernumerary tooth and third molars.
DISCUSSION
To close an open bite, the literature mentions that intrusion of molars by means of mini implants is a good treatment option;12,15 in this case, intrusion was not a procedure to be followed as the patient was normocephalic and class III was not to be shown much more. It was therefore decided to extract the first premolars so that the change would only be of a dental nature. The changes were observed in the position of the upper and lower incisors, especially in the retroinclination of the upper incisors. The new position of the incisors allowed us to close the bite and obtain a much more harmonious facial profile.
McLaughlin, Benett and Trevisi mention that in class III patients the IMPA is stable between 80o to 85o,17 and in our case we obtained an IMPA of 88o similar to that found by Arriola-Guillen and Flores-Mir, where they report a retroinclination of the lower incisor in class III patients of up to 10o or more degrees.14
We had difficulty in the space closure stage of the right upper quadrant, for this reason we opted to use an archwire with a tear drop loop to eliminate friction and make the closure freer.18
CONCLUSION
The approach and treatment of open bite is complicated, however, we achieved the desired objectives, we were able to close the anterior open bite, and a correct occlusion with its respective canine guidance was obtained. With the extraction of the premolars we managed to reduce the dental protrusion and gave the patient a better facial harmony that allowed her to have greater self-confidence. Retention is vital to prevent relapse and emphasis needs to be placed on patients' attendance at follow-up appointments. Open bite will always be a difficult challenge for the orthodontist, the key to success in correcting the problem lies in the diagnosis and aetiology of the problem, with these elements in mind an ideal treatment plan can be proposed and the success rate will be much higher.
REFERENCES
AFFILIATIONS
1 Especialidad de Ortodoncia. Universidad Autónoma de Guadalajara. México.
2 Departamento de Clínicas Odontológicas Integrales. Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. México.
CORRESPONDENCE
Jacqueline Adelina Rodríguez-Chávez. E-mail: jacqueline.rchavez@academicos.udg.mxReceived: Enero 2020. Accepted: Abril 2020.