Diagnostic and treatment for lack of space of upper permanent lateral incisors in children: a case report

Barboza, Victória de Vassimon; Proença, Aline Costa Flexa Ribeiro; Fugita, Gisele Kimie; Negro, Bianca Del; Gimenez, Thais; Imparato, José Carlos Petorrossi

doi:10.1590/1981-86372025000520240047

ABSTRACT

Dental professionals caring for children play a crucial role in identifying dental and occlusal anomalies. They monitor the development of dentition and diagnose eruption deviations. Early diagnosis allows for timely intervention, if necessary, to ensure optimal outcomes. This case report described how interceptive orthodontics successfully erupted permanent lateral incisors lacking sufficient space. A 7-year-old patient, accompanied by her parents, presented with concerns regarding the delayed eruption of her upper permanent lateral incisors. Clinical examination revealed a right posterior crossbite, an ogival palate, and a lack of space for teeth 12 and 22. Additionally, the patient exhibited mouth breathing, a nasal voice, and an inability to achieve a lip seal. To address the transverse maxillary discrepancy, rapid maxillary expansion was performed using the Hyrax appliance. After three months of treatment, the lateral incisors began erupting. By the six-month mark, the teeth were successfully positioned, and the appliance was removed. Timely diagnosis of insufficient space for upper permanent lateral incisor eruption proved essential for successful, quick, and satisfactory intervention with interceptive orthodontics.

Indexing terms
Tooth eruption; Pediatric dentistry; Orthodontics, interceptive

RESUMO

Os profissionais que atendem crianças devem saber identificar anomalias dentárias e oclusais, acompanhar o desenvolvimento da dentição e diagnosticar corretamente desvios de erupção, para que quando necessário, a intervenção possa ser realizada no momento ideal. O objetivo desse estudo foi descrever por meio de um caso clínico como a ortodontia interceptora foi eficiente na erupção de incisivos laterais permanentes que se encontravam sem espaço para irromper. Paciente com 7 anos compareceu ao consultório odontológico acompanhada de seus pais queixando-se de demora para erupção dos incisivos laterais superiores permanentes. Ao exame clínico observou-se mordida cruzada posterior direita, palato ogival e falta de espaço para os dentes 12 e 22, além de respiração bucal, voz anasalada e falta de selamento labial. Foi realizada a expansão rápida da maxila com aparelho Hyrax para corrigir a discrepância transversal maxilar. Após 3 meses de tratamento, os incisivos laterais já iniciavam sua erupção. Passados 6 meses, os dentes estavam em suas posições e o aparelho foi removido. Conclui-se que o diagnóstico da falta de espaço para erupção dos incisivos laterais superiores permanentes, realizado na época correta, foi essencial para que a intervenção com a ortodontia interceptora fosse eficaz, rápida e satisfatória.

Termos de indexação
Erupção dentária; Odontopediatria; Ortodontia interceptora

INTRODUCTION

The lack of space for the eruption of the permanent teeth during mixed dentition is a common occurrence in dental practice. Dental professionals, particularly pediatric dentists and orthodontists, play a crucial role in diagnosing these cases. The professionals must be acquainted with different types of eruption disturbances [¹] once they may be associated with occlusal anomalies in pediatric patients [²].

Malocclusion can negatively impact tooth position, aesthetics, and function, and even lead to issues like chewing difficulties, mouth breathing, and phonation [³]. Therefore, monitoring the development of the dentition and diagnosing eruption deviations at an early stage is critical. This enables timely intervention to prevent undesirable consequences and promote normal development of the occlusion [⁴].

Among malocclusions, posterior crossbite presents clinically as atresia of the upper dental arch [⁵]. This affects an average of 18% of Brazilian children during the mixed dentition [⁶]. When diagnosed in the deciduous dentition, the risk of this condition persisting into the mixed dentition increases by 7.5 times [⁷].

Treating posterior crossbite requires identifying the underlying cause, as recurrence is likely if the factor persists [⁸]. Several factors can contribute to a posterior crossbite, including mouth breathing, early loss of primary teeth, lack of space in either arch, migration of permanent tooth buds and cleft palate [⁹].

Interceptive orthodontic treatments offer solutions such as rapid maxillary expansion (RME), which may use orthopedic appliances to expand the palatine suture [¹⁰]. The primary goal of disjunction is to perform the coordination of upper and lower dental arches, assisting the eruption of impacted or retained teeth [¹¹].

The study aimed to describe, through a clinical case, how interceptive orthodontics successfully erupted two upper permanent lateral incisors that presented with insufficient space in the oral cavity.

CASE REPORT

A 7-year-old girl accompanied by her parents visited the dental clinic. The mother’s primary concern was the delayed eruption of permanent lateral incisors (teeth 12 and 22), since the primary lateral incisors (teeth 52 and 62) had already exfoliated. Additionally, the child exhibited bruxism, night snoring, and some breathing difficulties. She had previously seen otolaryngology, but the family was waiting for school vacations to schedule the adenoid surgery.

During the clinical examination, the patient presented with mouth breathing, a nasal voice, an inability to achieve a lip seal, and a lack of space for the eruption of teeth 12 and 22. Additionally, a right posterior crossbite and an ogival palate were observed (figure 1). Based on these findings, orthodontic documentation was requested. The panoramic radiograph (figure 2) confirmed the clinical observations.

Figure 1
Photographs of the orthodontic documentation. Lack of space for the eruption of teeth 12 and 22, deep ogival palate, unilateral right posterior crossbite, lack of lip seal, and facial characteristics suggestive of mouth breathing.

Figure 2
Initial panoramic radiograph showing the absence of eruption of teeth 12 and 22.

To initiate interceptive orthodontic treatment, the Hyrax expander appliance (figure 3A) was planned. The appliance featured bands cemented with self-curing glass ionomer cement (Riva Luting, SDI, Victoria - Australia) on the primary second molars (teeth 55 and 65) and extended to the permanent first molars (teeth 16 and 26). The activation protocol involved two-quarter turns in the morning and two-quarter turns in the evening, totaling one full turn per day for seven days. After this activation period, the patient returned for a follow-up appointment. Examination revealed an opening of the median palatine suture, with a diastema forming between teeth 11 and 21 (figure 3B). Although she experienced some discomfort in the palate area during expansion between the third and fourth day, pain medication was not necessary.

Figure 3
A) Hyrax device and screw activation key. B) Seven days after rapid maxillary expansion, the opening of the median palatal suture and the formation of a diastema between teeth 11 and 21 can be observed. C) One month after palatal disjunction, removal of the support clip of tooth 53 for better eruption of tooth 12. D) Removal of the support clip from tooth 63, three months after expansion, with eruption of teeth 12 and 22.

One month later, tooth 12 erupted. Consequently, the support clip for tooth 53 was removed (figure 3C) to avoid hindering its eruption. At the next appointment, after two months of treatment, tooth 22 also began erupting, prompting the removal of the clip-on tooth 63 (figure 3D). By the three-month mark, both lateral incisors were successfully positioned.

At the end of treatment, after six months, teeth 12 and 22 were positioned correctly, the posterior crossbite was corrected, and the appliance was removed (figure 4). This resulted in a good aesthetic outcome and functional stability. A new panoramic radiograph was performed to monitor the mixed dentition (figure 5). The patient continued to return to the dental office for preventive appointments and follow-ups (figure 6).

Figure 4
Removal of the expansion appliance with good aesthetic results and functional stability.

Figure 5
Final panoramic radiograph.

Figure 6
Post-treatment evaluation, during a preventive appointment four months after the appliance was removed.

This case report adheres to the CARE Guidelines [¹²]. The ethics committee of Faculdade São Leopoldo Mandic (6.821.308) approved the study, and both the guardian and the underage patient signed the Informed Consent Form.

DISCUSSION

Diagnosing a lack of space for permanent tooth eruption, early intervention and the patient’s cooperation is crucial for defining an effective treatment plan and satisfactory results. Early interventions aimed to correct the posterior crossbite allow the maxilla to develop properly, once the asymmetry caused by this type of malocclusion can become permanent [⁹]. When choosing the treatment approach, a dentist considers the patient’s age and the severity of the malocclusion [¹³]. This highlights the critical role of pediatric dentists in identifying these cases. They can educate families about malocclusion and its impact on oral functions such as breathing, sleeping, and chewing [¹⁴].

Interceptive orthodontics aims to address the issue before it progresses, allowing normal occlusion to develop. In this clinical case, the patient presented with mouth breathing, a nasal voice, posterior crossbite, lack of lip seal, lack of space for teeth 12 and 22 eruptions, and a deep ogival palate. Common examples of interception include removing retained primary teeth, correcting crossbites, and eliminating bad oral habits already developed [¹⁵].

Considering these factors, interceptive orthodontics was implemented using the Hyrax expander to correct the crossbite, to achieve sufficient space for teeth 12 and 22 eruptions, and to perform maxillary disjunction. As previously described, orthopedic appliances used for RME are fixed and can be tooth-supported; e.g, the Hyrax-type expander or tooth-mucosupported; e.g, the Haas-type expander [⁸].

In this case, the Hyrax expander was chosen due to its tooth-supported design, which avoids an acrylic plate on the palate, promoting easier hygiene for the patient [¹⁶]. This choice was made because the tooth-mucosupported anchorage was not necessary due to the unilateral posterior crossbite. Additionally, the patient already had speech difficulties and limited manual dexterity to perform an appropriate oral hygiene.

The prescribed protocol involves activating the expander one full turn per day, two-quarter turns in the morning and two in the evening, for a duration varying between one and two weeks, depending on the severity of the maxillary atresia. This is why the term “rapid maxillary expansion” is used.

Following activation, a passive phase follows. During this time, the appliance remains in place to allow ossification of the palatine suture [⁸].

Research suggests that RME is particularly beneficial for children. Not only does it correct malocclusion, but it can also reduce sleep-disordered breathing, reducing the frequence of nocturnal bruxism in the medium and short term [¹⁴], and improving their quality of life [¹⁸]. According to the parent’s report, the patient experienced reduced snoring and a significant improvement in nocturnal bruxism.

The treatment in young patients promotes long-term changes in the maxillary structures and surrounding areas. Treatment after this growth period often only affects the positioning of the teeth within the jawbone [¹⁷]. This justifies the choice of treatment for this seven-year-old patient with mixed dentition and a posterior crossbite.

RME significantly impacts the nasomaxillary complex, which aims to correct the transverse maxillary discrepancy [¹⁸]. This is achieved by widening the maxilla by opening the mid-palate and perimaxillary sutures [¹⁹]. Consequently, a diastema between the upper central incisors was promptly created such as the necessary space for the eruption of the patient’s lateral incisors, which were previously unable to erupt due to the unilateral posterior crossbite and palate atresia.

One lateral incisor erupted after one month, and both after three months. This three-month assessment following active maxillary expansion is standard in RME protocols and represents the end of the expansion stabilization period [²⁰]. Furthermore, it also represents the required period to achieve the complete maxillary suture bone neoformation.

Regarding post-expansion retention, research suggests that six months may be sufficient to prevent relapse or minor changes [²¹]. In this case, the appliance was removed after six months of treatment, when the lateral incisors were positioned correctly, and the posterior crossbite was corrected.

The stability of the posterior crossbite correction in the mixed dentition long-term is favorable [²²].

CONCLUSION

In conclusion, timely diagnosis of insufficient space for upper permanent lateral incisor eruption was critical for the success of interceptive orthodontics. This approach resulted in a quick and satisfactory outcome, avoiding more invasive and complex treatments. Utilizing the Hyrax expander appliance, the patient achieved a complete mixed dentition with a corrected posterior crossbite and all teeth in the proper position within six months. This treatment provided not only aesthetic benefits but also improved function and phonation.

How to cite this article

Barboza VV, Proença ALCFR, Fugita GK, Negro B, Gimenez T, Imparato JCP. Diagnostic and treatment for lack of space of upper permanent lateral incisors in children: a case report. RGO, Rev Gaúch Odontol. 2025;73:e20250005. http://dx.doi.org/10.1590/1981-86372025000520240047

REFERENCES

¹ Meade MJ, Dreyer CW. Eruption disturbances in the mixed dentition: orthodontic considerations for primary dental care. Aust Dent J. 2022; 67 Suppl 1(Suppl 1):S14-S23. https://doi.org/10.1111/adj.12931
» https://doi.org/10.1111/adj.12931
² Tavares ARF, Estrela CRA, Lazari-Carvalho PC. Interceptive orthodontics in the treatment of bilateral posterior crossbite and anterior open bite: case report. Rev Odontol Bras Central 2019; 28(87): 248-251. https://doi.org/10.36065/robrac.v28i87.1384
» https://doi.org/10.36065/robrac.v28i87.1384
³ Kurol J. Early treatment of tooth-eruption disturbances. Am J Orthod Dentofacial Orthop. Jun 2002; 121(6):588-91. https://doi.org/10.1590/pboci.2020.069
» https://doi.org/10.1590/pboci.2020.069
⁴ Assis WC, JP, Silva YS, Brito FR, Nunes LA, Ribeiro IJS et al. Factors associated with malocclusion in preschool children in a Brazilian small town. Pesq Bras Odontopediatria Clín Integr. 2020;20:1-12. https://doi.org/10.1590/pboci.2020.069
» https://doi.org/10.1590/pboci.2020.069
⁵ Capelozza Filho L, Silva Filho OG. Rapid jaw expansion: general considerations and clinical application. Part I. Dental Press J Orthod. 1997;16(4):197-202.
⁶ Silva Filho OG, Freitas SF, Cavassan AO. Prevalence of normal occlusion and malocclusion in schoolchildren in the city of Bauru (São Paulo). Part I: sagittal relationship. Rev Odontol Univ. 1990; 4(2):130-7.
⁷ Góis EG, Vale MP, Paiva SM, Abreu MH, Serra-Negra JM, Pordeus IA. Incidence of malocclusion between primary and mixed dentitions among Brazilian children. A 5-year longitudinal study. Angle Orthod. 2012;82(3):495-500. https://doi.org/10.2319/033011-230.1
» https://doi.org/10.2319/033011-230.1
⁸ Silva Filho OG, Garib DG, Lara TS. Interceptive orthodontics: two-phase treatment protocol. São Paulo: Artes Médicas; 2013.
⁹ Locks A, Weissheimer A, Ritter DE, Ribeiro GLU, Menezes LM, Derech CD et al. Posterior crossbite: a more didactic classification. R Dental PressOrthodon Orthop Facial. 2008;13(2):146-158. https://doi.org/10.1590/S1415-54192008000200017
» https://doi.org/10.1590/S1415-54192008000200017
¹⁰ Bezerra BM, Araujo PPB, Pascoal CEB, Roberto FB, Barroso GNGN, Pereira GOF. Rapid maxillary expansion using hyrax. Rev ft. 2023;120:21. https://doi.org/10.5281/zenodo.7757985
» https://doi.org/10.5281/zenodo.7757985
¹¹ Fabrini FF, Gonçalves KJ, Dalmagro Filho L. Rapid maxillary expansion, without surgical assistance, using Hyrax. Arq Ciênc Saúde Unipar. 2006;10(3):177-180.
¹² Gagnier JJ, Kienle G, Altman DG, Moher D, Sox H, Riley D, CARE Group. The CARE guidelines: consensus-based clinical case reporting guideline development. BMJ Case Rep. 2013; 2(5):38-43. https://doi.org/10.1136/bcr-2013-201554
» https://doi.org/10.1136/bcr-2013-201554
¹³ Souza B, Mucheli E, Herd JL. Mordida cruzada posterior na dentadura decídua e mista: uma revisão bibliográfica. Rev Rede Cuidados em Saúde. 2017;10(1):1-10.
¹⁴ Paglia L. Interceptive orthodontics: awareness and prevention is the first cure. Eur J Paediatr Dent. 2023;24(1):5. https://doi.org/10.23804/ejpd.2023.24.01.01
» https://doi.org/10.23804/ejpd.2023.24.01.01
¹⁵ Gomes GV, Strelow TAT, Almeida AS. Ortodontia preventiva e interceptativa e suas contribuições para um bom desenvolvimento da oclusão do paciente em fase de dentição decídua e/ou mista: um estudo teórico. J Business Techn. 2020;14(2):74-86.
¹⁶ Martins et al. Disjuntores maxilares Haas e Hyrax: revisão integrativa de literatura. Braz J Development. 2023;9(1):1412-1428. https://doi.org/10.34117/bjdv9n1-098
» https://doi.org/10.34117/bjdv9n1-098
¹⁷ Bacetti T, Franchi L, Cameron CG, McNamara Jr JA. Treatment timing for rapid maxillary expansion. Angle Orthod. 2001 Oct;71(5):343-50. https://doi.org/10.1043/0003-3219(2001)071<0343:TTFRME>2.0.CO;2
» https://doi.org/10.1043/0003-3219(2001)071<0343:TTFRME>2.0.CO;2
¹⁸ Ponte MBM, Rodrigues HPO, Vieira LVM, Freitas ABE. Effects of rapid maxillary expansion in children with obstructive sleep apnea: a literature review. In: Anais da XXV Jornada Acadêmica de Odontologia (JAO); Universidade de Fortaleza (UNIFOR). Fortaleza/Ceará/BR. 2022
¹⁹ Bucci R, Rongo R, Zunino B. et al. Effect of orthopedic and functional orthodontic treatment in children with obstructive sleep apnea: a systematic review and meta-analysis. Sleep Med Ver. 2023;67:101730. https://doi.org/10.1016/j.smrv.2022.101730
» https://doi.org/10.1016/j.smrv.2022.101730
²⁰ Santana DM, Nogueira VS, Lima AS, Fernandes LP, Weber SA. The effect of rapid maxillary expansion in children: a meta-analysis. Braz J Otorhinolaryngol. 2022;88(6):907-916. https://doi.org/10.1016/j.bjorl.2020.12.017
» https://doi.org/10.1016/j.bjorl.2020.12.017
²¹ Costa JG, Galindo TM, Mattos CT, Cury-Saramago AA. Retention period after treatment of posterior crossbite with maxillary expansion: a systematic review. Dental Press J Orthod. 2017;22(2):35-44. https://doi.org/10.1590/2177-6709.22.2.035-044.oar
» https://doi.org/10.1590/2177-6709.22.2.035-044.oar
²² Petrén S, Bjerklin K, Bondemark L. Stability of unilateral posterior crossbite correction in the mixed dentition: a randomized clinical trial with a 3-year follow-up. Am J Orthod Dentofacial Orthop. 2011 Jan;139(1):e73-81. https://doi.org/10.1016/j.ajodo.2010.06.018.
» https://doi.org/10.1016/j.ajodo.2010.06.018

Edited by

Assistant editor:
Luciana Butini Oliveira

Publication Dates

Publication in this collection
31 Mar 2025
Date of issue
2025

History

Received
31 July 2024
Accepted
14 Nov 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

[1] ¹ Meade MJ, Dreyer CW. Eruption disturbances in the mixed dentition: orthodontic considerations for primary dental care. Aust Dent J. 2022; 67 Suppl 1(Suppl 1):S14-S23. https://doi.org/10.1111/adj.12931
» https://doi.org/10.1111/adj.12931

[2] ² Tavares ARF, Estrela CRA, Lazari-Carvalho PC. Interceptive orthodontics in the treatment of bilateral posterior crossbite and anterior open bite: case report. Rev Odontol Bras Central 2019; 28(87): 248-251. https://doi.org/10.36065/robrac.v28i87.1384
» https://doi.org/10.36065/robrac.v28i87.1384

[3] ³ Kurol J. Early treatment of tooth-eruption disturbances. Am J Orthod Dentofacial Orthop. Jun 2002; 121(6):588-91. https://doi.org/10.1590/pboci.2020.069
» https://doi.org/10.1590/pboci.2020.069

[4] ⁴ Assis WC, JP, Silva YS, Brito FR, Nunes LA, Ribeiro IJS et al. Factors associated with malocclusion in preschool children in a Brazilian small town. Pesq Bras Odontopediatria Clín Integr. 2020;20:1-12. https://doi.org/10.1590/pboci.2020.069
» https://doi.org/10.1590/pboci.2020.069

[5] ⁵ Capelozza Filho L, Silva Filho OG. Rapid jaw expansion: general considerations and clinical application. Part I. Dental Press J Orthod. 1997;16(4):197-202.

[6] ⁶ Silva Filho OG, Freitas SF, Cavassan AO. Prevalence of normal occlusion and malocclusion in schoolchildren in the city of Bauru (São Paulo). Part I: sagittal relationship. Rev Odontol Univ. 1990; 4(2):130-7.

[7] ⁷ Góis EG, Vale MP, Paiva SM, Abreu MH, Serra-Negra JM, Pordeus IA. Incidence of malocclusion between primary and mixed dentitions among Brazilian children. A 5-year longitudinal study. Angle Orthod. 2012;82(3):495-500. https://doi.org/10.2319/033011-230.1
» https://doi.org/10.2319/033011-230.1

[8] ⁸ Silva Filho OG, Garib DG, Lara TS. Interceptive orthodontics: two-phase treatment protocol. São Paulo: Artes Médicas; 2013.

[9] ⁹ Locks A, Weissheimer A, Ritter DE, Ribeiro GLU, Menezes LM, Derech CD et al. Posterior crossbite: a more didactic classification. R Dental PressOrthodon Orthop Facial. 2008;13(2):146-158. https://doi.org/10.1590/S1415-54192008000200017
» https://doi.org/10.1590/S1415-54192008000200017

[10] ¹⁰ Bezerra BM, Araujo PPB, Pascoal CEB, Roberto FB, Barroso GNGN, Pereira GOF. Rapid maxillary expansion using hyrax. Rev ft. 2023;120:21. https://doi.org/10.5281/zenodo.7757985
» https://doi.org/10.5281/zenodo.7757985

[11] ¹¹ Fabrini FF, Gonçalves KJ, Dalmagro Filho L. Rapid maxillary expansion, without surgical assistance, using Hyrax. Arq Ciênc Saúde Unipar. 2006;10(3):177-180.

[12] ¹² Gagnier JJ, Kienle G, Altman DG, Moher D, Sox H, Riley D, CARE Group. The CARE guidelines: consensus-based clinical case reporting guideline development. BMJ Case Rep. 2013; 2(5):38-43. https://doi.org/10.1136/bcr-2013-201554
» https://doi.org/10.1136/bcr-2013-201554

[13] ¹³ Souza B, Mucheli E, Herd JL. Mordida cruzada posterior na dentadura decídua e mista: uma revisão bibliográfica. Rev Rede Cuidados em Saúde. 2017;10(1):1-10.

[14] ¹⁴ Paglia L. Interceptive orthodontics: awareness and prevention is the first cure. Eur J Paediatr Dent. 2023;24(1):5. https://doi.org/10.23804/ejpd.2023.24.01.01
» https://doi.org/10.23804/ejpd.2023.24.01.01

[15] ¹⁵ Gomes GV, Strelow TAT, Almeida AS. Ortodontia preventiva e interceptativa e suas contribuições para um bom desenvolvimento da oclusão do paciente em fase de dentição decídua e/ou mista: um estudo teórico. J Business Techn. 2020;14(2):74-86.

[16] ¹⁶ Martins et al. Disjuntores maxilares Haas e Hyrax: revisão integrativa de literatura. Braz J Development. 2023;9(1):1412-1428. https://doi.org/10.34117/bjdv9n1-098
» https://doi.org/10.34117/bjdv9n1-098

[17] ¹⁷ Bacetti T, Franchi L, Cameron CG, McNamara Jr JA. Treatment timing for rapid maxillary expansion. Angle Orthod. 2001 Oct;71(5):343-50. https://doi.org/10.1043/0003-3219(2001)071<0343:TTFRME>2.0.CO;2
» https://doi.org/10.1043/0003-3219(2001)071<0343:TTFRME>2.0.CO;2

[18] ¹⁸ Ponte MBM, Rodrigues HPO, Vieira LVM, Freitas ABE. Effects of rapid maxillary expansion in children with obstructive sleep apnea: a literature review. In: Anais da XXV Jornada Acadêmica de Odontologia (JAO); Universidade de Fortaleza (UNIFOR). Fortaleza/Ceará/BR. 2022

[19] ¹⁹ Bucci R, Rongo R, Zunino B. et al. Effect of orthopedic and functional orthodontic treatment in children with obstructive sleep apnea: a systematic review and meta-analysis. Sleep Med Ver. 2023;67:101730. https://doi.org/10.1016/j.smrv.2022.101730
» https://doi.org/10.1016/j.smrv.2022.101730

[20] ²⁰ Santana DM, Nogueira VS, Lima AS, Fernandes LP, Weber SA. The effect of rapid maxillary expansion in children: a meta-analysis. Braz J Otorhinolaryngol. 2022;88(6):907-916. https://doi.org/10.1016/j.bjorl.2020.12.017
» https://doi.org/10.1016/j.bjorl.2020.12.017

[21] ²¹ Costa JG, Galindo TM, Mattos CT, Cury-Saramago AA. Retention period after treatment of posterior crossbite with maxillary expansion: a systematic review. Dental Press J Orthod. 2017;22(2):35-44. https://doi.org/10.1590/2177-6709.22.2.035-044.oar
» https://doi.org/10.1590/2177-6709.22.2.035-044.oar

[22] ²² Petrén S, Bjerklin K, Bondemark L. Stability of unilateral posterior crossbite correction in the mixed dentition: a randomized clinical trial with a 3-year follow-up. Am J Orthod Dentofacial Orthop. 2011 Jan;139(1):e73-81. https://doi.org/10.1016/j.ajodo.2010.06.018.
» https://doi.org/10.1016/j.ajodo.2010.06.018