View source for Association between posterior unilateral functional crossbite and asymmetrical spinal flexion: A prospective study

{{Versions 
 | en = Association between posterior unilateral functional crossbite and asymmetrical spinal flexion: A prospective study
 | it = Associazione tra crossbite funzionale unilaterale posteriore e flessione spinale asimmetrica: uno studio prospettico
 | fr = Association entre occlusion croisée fonctionnelle unilatérale postérieure et flexion vertébrale asymétrique : une étude prospective
 | de = Zusammenhang zwischen hinterem einseitigen funktionellen Kreuzbiss und asymmetrischer Wirbelsäulenflexion: Eine prospektive Studie
 | es = Asociación entre mordida cruzada funcional unilateral posterior y flexión espinal asimétrica: un estudio prospectivo
 | pt = <!-- portoghese -->
 | ru = <!-- russo -->
 | pl = <!-- polacco -->
 | fi = <!-- finlandese/suomi -->
 | ca = <!-- catalano -->
 | ja = <!-- giapponese -->
 }}

{{FR
 | Title = 
 | author1 = Maria Grazia Piancino 
 | author2 = Giada Matacena
 | author3 = Umberto Garagiola 
 | author4 = Farhad B. Naini
 | author5 = Alessandro Tortarolo
 | author6 = David Wertheimf
 | author7 = 
 | author8 = 
 | author9 = 
 | author10 =
 | Source = https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10011000/<!-- where this work comes from or where was it was retrieved (URL) -->
 | Original =  <!-- link to the original screenshot or PDF print from the retrieval -->
 | Date = 2023<!-- date of the original work, when the author/s published it (dd/mm/yyyy) -->
 | Journal = Heliyon
 | DOI =  10.1016/j.heliyon.2023.e14342
 | ISBN = 
 | PUBMED = https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10011000/
 | PMID = 36925534
 | PMCID = 10011000 
 | Pdfcopy = https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10011000/pdf/main.pdf<!-- eventual polished PDF document -->
 | License = CC BY
 }}Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy, via Nizza 230, 10126, Turin, Italy

Orthodontist, Private Practice, Turin, Italy

Department of Biomedical Surgical and Dental Sciences, Maxillo-facial and Odontostomatology Unit, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, University of Milan, Milan, Italy

Consultant Orthodontist, Kingston and St. George's, University Hospitals, NHS Foundation Trust, London, UK

Department of Surgical Sciences, Dental School, University of Turin, Turin, Italy

Faculty of Sciences, Engineering and Computing, Kingston University, Surrey, UK

Maria Grazia Piancino: ti.otinu@onicnaip.aizargairam; Giada Matacena: ti.oohay@anecatam.adaig; Umberto Garagiola: ti.iminu@aloigarag.otrebmu; Farhad B. Naini: ku.oc.oohay@inian.dahraf; Alessandro Tortarolo: ti.otinu@oloratrot.ordnassela; David Wertheim: ku.ca.notsgnik@miehtrew.d

∗Corresponding author. ti.otinu@onicnaip.aizargairam



=== Abstract ===
Unilateral posterior crossbite (UPC) with functional shift is a malocclusion that may have the potential to affect the masticatory function and the flexibility of the spine due to intrinsic occlusal, structural and functional asymmetries sustained by marked asymmetrical muscular activation.

'''Research question'''

To investigate whether the presence of UPC with functional shift is associated with reverse chewing pattern and altered spine flexion.

'''Methods'''

Patients with UPC and a control group of patients with normal occlusion were recorded when chewing soft and hard boluses using a Kinesiograph (Myotronics-Noromed Inc., USA) and spine alignment was assessed with an electronic inclinometer Spinal Mouse® system (Idiag AG, Switzerland).

'''Results'''

There were 87 children with UPC in the patients' group among whom 38, with median (IQR) age 8.0 (7.3–9.3) years, had measurements before and after treatment. The UPC patients showed a higher percentage of anomalous/reverse chewing patterns on the crossbite side compared with a control group (p < 0.001). Moreover, a clear difference was observed between left and right flexion angles of the spine in the patients’ group (p < 0.001 and p = 0.001, paired t-test) with the crossbite side being more flexible compared to the non-crossbite side. No such differences were seen in the control group, nor post-treatment for right and left crossbite (p = 0.44 and p = 0.15 respectively, paired t-test).

'''Significance'''

This study suggests an association between UPC, asymmetrical chewing patterns and asymmetrical flexion of the spine. These results may help improve understanding of any association between dental malocclusions and spine posture and hence aid diagnosis and treatment strategies.

'''Keywords:''' Musculoskeletal physiological phenomena, Posture, Spine, Mastication, Chewing, Malocclusion, Crossbite

=== Introduction ===
{{Bookind2}}The relationship between dental occlusion/malocclusion and body flexibility, range of motion (ROM) and posture is still a controversial topic. Even though past review papers did not find enough evidence in support of this association, <ref>Perinetti G. Dental occlusion and body posture: no detectable correlation. Gait Posture. 2006;24(2):165–168</ref><ref>Manfredini D., Castroflorio T., Perinetti G., Guarda-Nardini L. Dental occlusion, body posture and temporomandibular disorders: where we are now and where we are heading for. J. Oral Rehabil. 2012;39(6):463–471.</ref><ref>Gomes Lde C., Horta K.O., Gonçalves J.R., Santos-Pinto A.D. Systematic review: craniocervical posture and craniofacial morphology. Eur. J. Orthod. 2014;36(1):55–66.</ref> a few studies have shown that patients with posterior crossbite may have an increased risk of developing spine asymmetries <ref>O'Byrn B.L., Sadowsky C., Schneider B., BeGole E.A. An evaluation of mandibular asymmetry in adults with unilateral posterior crossbite. Am. J. Orthod. Dentofacial Orthop. 1995;107(4):394–400.</ref><ref>Lippold C., Danesh G., Hoppe G., Drerup B., Hackenberg L. Sagittal spinal posture in relation to craniofacial morphology. Angle Orthod. 2006;76(4):625–631. </ref><ref>Korbmacher H., Koch L., Eggers-Stroeder G., Kahl-Nieke B. Associations between orthopaedic disturbances and unilateral crossbite in children with asymmetry of the upper cervical spine. Eur. J. Orthod. 2007;29(1):100–104.</ref><ref>Hong J.Y., W Suh S., N Modi H., Yang J.H., Hwang Y.C., Lee D.Y., Hur C.Y., Park Y.H. Correlation between facial asymmetry, shoulder imbalance, and adolescent idiopathic scoliosis. Orthopedics. 2011;34(6):187.</ref><ref>Primozic J., Perinetti G., Zhurov A., Richmond S., Ovsenik M., Antolic V., Primozic J. Three-dimensional assessment of back symmetry in subjects with unilateral functional crossbite during the pre-pubertal growth phase: a controlled study. Eur. J. Orthod. 2019;41:250–257.</ref>and the influence of occlusion on the cervical spine has been substantiated.<ref>Michelotti A., Manzo P., Farella M., Martin R. [Occlusion and posture: is there evidence of correlation?] Minerva Stomatol. 1999;48(11):525–534.</ref> However, a recent systematic review concluded that there was no clear evidence of a causal relationship between spinal deformities and malocclusions<ref>Langella F., Fusini F., Rossi G., Villafañe J.H., Migliaccio N., Donzelli S., Berjano P. Spinal deformity and malocclusion association is not supported by high-quality studies: results from a systematic review of the literature. Eur. Spine J. 2019;28(7):1638–1651.</ref> and underlined the limited extent of the literature to date. On the other hand, even though the results are not directly translatable to humans, three interesting animal studies,<ref>D'Attilio M., Filippi M.R., Femminella B., Festa F., Tecco S. The influence of an experimentally-induced malocclusion on vertebral alignment in rats: a controlled pilot study. Cranio. 2005;23(2):119–129.</ref><ref>Ramirez-Yanez G.O., Mehta L., Mehta N.R. The effect of dental occlusal disturbances on the curvature of the vertebral spine in rats. Cranio. 2015;33(3):217–227. </ref><ref>D'Attilio M., Cesaretti G., Viganò P., Alí Apaza Alccayhuaman K., Botticelli D., Ricardo Silva E., Porfirio X.S. Effects of induced malocclusion on vertebral alignment in rats: a controlled study by CBCTs. Animals (Basel) 2021;11(10):2808.</ref> showed the role of an induced malocclusion on scoliotic irreversible curve degeneration. Also, the demonstration of possible associations of standard orthodontic therapies, such as rapid palatal expansion, on the worsening of scoliotic curves casts a shadow of concern that requires objective scientific clarification.<ref>Piancino M.G., MacDonald F., Laponte I., Cannavale R., Crincoli V., Dalmasso P. Juvenile/adolescent idiopathic scoliosis and rapid palatal expansion. A pilot study. Children. 2021;8(5):362. </ref>

The type of malocclusion that may have the potential to influence spinal curvatures due to intrinsic asymmetry is unilateral posterior crossbite (UPC) with functional shift, which is defined as an irregular bucco-lingual or bucco-palatal relationship between opposing teeth, resulting in a lateral displacement of the mandible in order to achieve maximum intercuspation of the dentition during functions.<ref>Daskalogiannakis J., Ross R.B., Tompson B.D. The mandibular catch-up growth controversy in Pierre Robin sequence. Am. J. Orthod. Dentofacial Orthop. 2001;120(3):280–285.</ref> The prevalence of posterior crossbite varies from 8 to 20% depending on the population and the research protocol,<ref>Thilander B., Lennartsson B. A study of children with unilateral posterior crossbite, treated and untreated, in the deciduous dentition - occlusal and skeletal characteristics of significance in predicting the long-term outcome. J. Orofac. Orthop. 2002;63(5):371–383.</ref><ref>Harrison J.E., Ashby D. Orthodontic treatment for posterior crossbites, cochrane database syst. Rev. 1. Cochrane Database Syst. Rev. 8 (2014) CD000979. 2001:CD000979.</ref> with more than half being UPC. The presence of posterior crossbite is associated with reduced maxillary growth: depending on the degree of transverse discrepancy between the upper and lower jaws, unilateral or bilateral posterior crossbite may be expressed. Interestingly, the presence of UPC has been associated with dento-alveolar compensation on the non-crossbite side, whereas no significant dento-alveolar compensation was shown in bilateral posterior crossbite (BPC).<ref>Miner R.M., Al Qabandi S., Rigali P.H., Will L.A. Cone-beam computed tomography transverse analysis. Part I: normative data. Am. J. Orthod. Dentofacial Orthop. 2012;142(3):300–307.</ref> UPC was also shown to have a significant impact on masticatory function, establishing anomalous reverse chewing patterns during chewing on the crossbite side.<ref name=":0">Piancino M.G., Comino E., Talpone F., Vallelonga T., Frongia G., Bracco P. Reverse-sequencing chewing patterns evaluation in anterior versus posterior unilateral crossbite patients. Eur. J. Orthod. 2012;34(5):536–541.</ref><ref name=":1">Piancino M.G., Falla D., Merlo A., Vallelonga T., de Biase C., Dalessandri D., Debernardi C. Effects of therapy on masseter activity and chewing kinematics in patients with unilateral posterior crossbite. Arch. Oral Biol. 2016;67:61–67</ref><ref>Ferrario V.F., Piancino M.G., Dellavia C., Castroflorio T., Sforza C., Bracco P. Quantitative analysis of the variability of unilateral chewing movements in young adults. Cranio. 2006;24(4):274–282.</ref><ref>Troelstrup B., Moller E. Electromyography of the temporalis and masseter muscles in children with unilateral cross-bite. Scand. J. Dent. Res. 1970;78(5):425–430. </ref><ref>Ingervall B., Thilander B. Activity of temporal and masseter muscles in children with a lateral forced bite. Angle Orthod. 1975;45(4):249–258.</ref><ref>Michler L., Bakke M., Møller E. Graphic assessment of natural mandibular movements. J. Craniomandib. Disord. 1987;1(2):97–114.</ref><ref>Alarcón J.A., Martín C., Palma J. Effect of unilateral posterior crossbite on the electromyographic activity of human masticatory muscles. Am. J. Orthod. Dentofacial Orthop. 2000;118(3):328–334.</ref> Reverse chewing cycles (also known as reverse-sequencing patterns) occur when the direction of the closing trace is inverted: they are characterized by an abnormal, narrow kinematic pattern in the frontal plane, with possible cross-over of the opening and closing tracings, as well as limited lateral displacement of the mandible.<ref>Lewin A. Quintessence; Berlin: 1985. Electrognathographics. An Atlas for Diagnostic Procedures and Interpretation.</ref><ref>Ben-Bassat Y., Yaffe A., Brin I., Freeman J., Ehrlich Y. Functional and morphological-occlusal aspects in children treated for unilateral posterior cross-bite. Eur. J. Orthod. 1993;15(1):57–63.</ref><ref>Brin I., Ben-Bassat Y., Blustein Y., Ehrlich J., Hochman N., Marmary Y., Yaffe A. Skeletal and functional effects of treatment for unilateral posterior crossbite. Am. J. Orthod. Dentofacial Orthop. 1996 Feb;109(2):173–179</ref><ref name=":2">Pinto A.S., Buschang P.H., Throckmorton G.S., Chen P. Morphological and positional asymmetries of young children with functional unilateral posterior crossbite. Am. J. Orthod. Dentofacial Orthop. 2001;120(5):513–520.</ref><ref>Throckmorton G.S., Buschang B.H., Hayasaki H., Phelan T. The effects of chewing rates on mandibular kinematics. J. Oral Rehabil. 2001;28(4):328–334. </ref><ref>Saitoh I., Hayasaki H., Iwase Y., Nakata M. Improvement in jaw motion following treatment of unilateral crossbite in a child with primary dentition: a case report. Cranio. 2002;20(2):129–134</ref><ref>Piancino M.G., Talpone F., Dalmasso P., Debernardi C., Lewin A., Bracco P. Reverse-sequencing chewing patterns before and after treatment of children with a unilateral posterior crossbite. Eur. J. Orthod. 2006;28(5):480–484.</ref><ref>ever E., Marion L., Ovsenik M. Relationship between masticatory cycle morphology and unilateral crossbite in the primary dentition. Eur. J. Orthod. 2011;33(6):620–627.</ref> The result is a serious asymmetry of the masticatory function. Such functional asymmetry is sustained by marked asymmetrical muscular activation between sides<ref name=":3">Piancino M.G., Farina D., Talpone F., Merlo A., Bracco P. Muscular activation during reverse and non-reverse chewing cycles in unilateral posterior crossbite. Eur. J. Oral Sci. 2009;117(2):122–128</ref> which, if not corrected with adequate early therapy, may induce asymmetrical basal growth.<ref name=":2" /><ref>Lam P.H., Sadowsky C., Omerza F. Mandibular asymmetry and condylar position in children with unilateral posterior crossbite. Am. J. Orthod. Dentofacial Orthop. 1999;115(5):569–575</ref> It is therefore of interest to investigate the relationship between masticatory asymmetry in UPC and asymmetrical flexion of the spine.

Non-invasive devices can be used to evaluate spine posture in children with crossbite without scoliosis or spine pathologies of orthopedic interest.<ref>Piancino M.G., Dalmasso P., Borello F., Cinnella P., Crincoli V., Garagiola U., de Biase C., Tonni I., Matacena G., Deregibus A. Thoracic-lumbar-sacral spine sagittal alignment and cranio-mandibular morphology in adolescents. J. Electromyogr. Kinesiol. 2019;48:169–175.</ref> The position and the movement of vertebrae can be accurately imaged with roentgenography (spinal column radiograph), which is the gold standard diagnostic investigation when orthopedic treatment is required. However, the use of X-ray imaging in such studies should be avoided, particularly in children, in view of the radiation exposure with such techniques. A computer-aided device (Spinal Mouse®, Idiag, Voletswil, Switzerland) has been developed to measure the lumbar, thoracic, and sacral spinal curvature with range of motion in the sagittal and frontal planes thus avoiding X-ray imaging, using bone anatomical reference points. The Spinal Mouse is a wheeled electronic inclinometer with accelerometer; the device is directed along a bone anatomical landmark, i.e. vertebral spinous processes and registers distance and changes of spinal movement and inclination.<ref>Mannion A.F., Knecht K., Balaban G., Dvorak J., Grob D. A new skin-surface device for measuring the curvature and global and segmental ranges of motion of the spine: reliability of measurements and comparison with data reviewed from the literature. Eur. Spine J. 2004;13(2):122–136. </ref> The Spinal Mouse system has been shown to have good intra-rater and inter-rater reliability<ref>Kellis E., Adamou G., Tzilios G., Emmanouilidou M. Reliability of spinal range of motion in healthy boys using a skin-surface device. J. Manip. Physiol. Ther. 2008;31(8):570–576</ref> and can help in the evaluation of motion capability and symmetry.

The aim of this study is to investigate whether the presence of unilateral posterior crossbite with functional shift is associated with reverse chewing pattern and degree of spine flexibility in children with the malocclusion. The null hypothesis (H0) for this study is that unilateral posterior crossbite is not associated with reverse chewing pattern and degree of spine flexibility.

=== Materials and methods ===
Patients with unilateral posterior crossbite and a control group of patients with normal occlusion, referred to the Orthodontic Department, Dental School, University of Turin, Italy were consecutively selected from April 2017 through July 2021. Before entering this prospective study, patients and their parents were informed about the aims of the study and the procedures, and the parents signed an informed consent to permit participation. The study was approved by the Institutional Review Board of the University Hospital “Health and Science Complex Turin-Italy” n. CS/246, in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for research involving humans. This study has been planned following the STROBE protocol.

=== Subjects ===
The inclusion criteria for the Patients Group were unilateral posterior crossbite (UPC) of two or more posterior teeth with lateral displacement/functional shift, mixed dentition and age less than 14 years for the first study assessment. The exclusion criteria were the presence of previous orthodontic therapy, erupting teeth, caries, dental pain, orthopedic trauma or impairments, back pain, signs or symptoms of dental or myofascial disorders, motor or neurological problems, diabetes and/or celiac disease, spine pathologies, congenital and hereditary pathologies. The Control Group (CG) was carefully selected for normal occlusion without crossbite. Participants were selected on the basis of occlusal diagnosis, performed by an experienced Orthodontist (MPG) by analyzing model casts.

All participants underwent the following sequence of investigations, before treatment (T0) and after treatment (T1)

# clinical and orthodontic examination
# intra- and extra-oral photograph
# model cast
# recording of chewing patterns
# recording of spinal flexion with the Spinal Mouse

The measurements and examinations were conducted in the morning in a dedicated quiet room. The two operators taking Spinal Mouse measurements and masticatory patterns had more than eight years of experience in the use of the instruments; they were unaware of the whether the patient was in the case or control group as well as the purpose of the study. All included patients received functional treatment with the removable appliance Function Generating Bite.<ref name=":1" /> The appliance was individually manufactured in acrylic resin and stainless steel, with metallic bite planes made of special resilient steel positioned between the upper and lower dental arches. The action of these bite planes results in mandibular disengagement, levelling of the occlusal plane and prevention of dental prematurities during orthodontic tooth movement. The appliance was designed and activated according to each patient's orthodontic needs.

=== Kinematic analysis – chewing patterns recording ===
Mandibular motion was tracked using a Kinesiograph (K7–I; Myotronics, Tukwila, WA, USA) that measures jaw movements with an accuracy of 0.1 mm. Multiple Hall effect sensors mounted in an array of weight 113 g were used to track the motion of a tiny magnet attached at the lower interincisor point.<ref>Jankelson B. Measurement accuracy of the mandibular kinesiograph - a computerized study. J. Prosthet. Dent. 1980;44(6):656–666.</ref> The Kinesiograph was interfaced with a computer for data storage and subsequent analysis. The kinematic analysis was carried out separately with a soft and a hard bolus. Recording procedure and signal analysis (Fig. 1) were performed following a standardized, previously published method.<ref name=":0" /><ref name=":1" /><ref name=":3" />