Effect of rapid maxillary expansion on the dimension of the nasal cavity and on nasal air resistance

Effect of rapid maxillary expansion on the dimension of the nasal cavity and on nasal air resistance

International Journal of Pediatric Otorhinolaryngology (2006) 70, 1225—1230 www.elsevier.com/locate/ijporl Effect of rapid maxillary expansion on th...

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International Journal of Pediatric Otorhinolaryngology (2006) 70, 1225—1230

www.elsevier.com/locate/ijporl

Effect of rapid maxillary expansion on the dimension of the nasal cavity and on nasal air resistance Carla Enoki a, Fabiana Cardoso Pereira Valera b, Fernanda Campos Rosetti Lessa c, Ana Maria Elias d, Mirian Aiko N. Matsumoto c, Wilma Terezinha Anselmo-Lima b,* a

˜o Preto, Universidade de Sa ˜o Paulo, Department of Pathology, Faculdade de Medicina de Ribeira ˜o Preto, SP, Brazil Ribeira b Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Hospital das Clı´nicas, ˜o Preto, Universidade de Sa ˜o Paulo, Ribeira ˜o Preto, SP, Brazil Faculdade de Medicina de Ribeira c ˜o Preto, Department of Children’s Clinical Preventive Dentistry, Faculdade de Odontologia de Ribeira ˜o Paulo, Ribeira ˜o Preto, SP, Brazil Universidade de Sa d Department of Statistics, Faculty of Science and Letters of Araraquara/Araraquara Campus, ˜o Paulo, Brazil University of Sa Received 25 October 2005; received in revised form 29 December 2005; accepted 31 December 2005

KEYWORDS Acoustic rhinometry; Rhinomanometry; Nasofibroscopy; Minimal cross-sectional area; Nasal air resistance; Rapid maxillary expansion; Posterior crossbite

Summary Introduction: Atresia of the maxilla is a transverse skeletal dysplasia, possibly associated with respiratory problems. For its correction, rapid maxillary expansion is a feasible orthodontic process. Objective: To evaluate the effect of rapid maxillary expansion on the nasal cavity by acoustic rhinometry and computed rhinomanometry. Material and methods: Twenty-nine children of both sexes with oral and/or mixed breathing, ranging in age from 7 to 10 years and with mixed dentition were selected. The children had uni- or bilateral posterior crossbite involving deciduous canines and the first permanent molars and were not being submitted to any otorhinolaryngologic or orthodontic treatment. All subjects were submitted to rhinologic exams and orthodontic documentation at three different times, i.e., before expansion and immediately and 90 days after expansion. Results: There was no difference in the minimal cross-sectional area at the level of the valve and inferior nasal turbinate between the periods analyzed, but there was a statistically significant reduction in nasal resistance after expansion.

* Corresponding author. Tel.: +55 16 3602 2862; fax: +55 16 3602 2860. E-mail address: [email protected] (W.T. Anselmo-Lima). 0165-5876/$ — see front matter # 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijporl.2005.12.019

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C. Enoki et al. Conclusion: On the basis of the present results, we may conclude that rapid maxillary expansion may lessen the nasal resistance. Although there was no difference in nasal geometry. Thus, this procedure may improve nasal respiration, but cannot be indicated for this purpose by itself. # 2006 Elsevier Ireland Ltd. All rights reserved.

1. Introduction Rapid maxillary expansion is one of the techniques most frequently used for the correction of maxillary atresia, with the purpose of increasing the width of the dental arch and of the nasal cavity. Nasal obstruction influences the environmental conditions needed for normal growth of the nasomaxillary complex, leading to an increased vertical dimension of the face. Adequate breathing should be predominantly nasal in order to provide equilibrium in perioral muscles and the pressures and tensions of soft tissues influence the shape, size and apposition of the bone. Studies have suggested that palatine disjunction for the correction of posterior crossbite improves nasal breathing. However, few studies have correlated rapid maxillary expansion during the mixed dentition period with exams that evaluate nasal geometry and resistance.

2. Objectives The objective of the present study was to assess the effect of rapid maxillary expansion on the nasal cavity by acoustic rhinometry and computed rhinomanometry in patients with mixed dentition.

3. Material and methods The study is a prospective longitudinal study and was conducted on 29 white patients of both sexes with oral or mixed breathing, ranging in age from 7 to 10 years. They all had mixed dentition, with unior bilateral posterior crossbite involving deciduous canines and molars and the first permanent molars. The otorhinolaryngologic diagnosis of oral breathing was made at the Service of Pediatric Rhinosinusology of the Discipline of Otorhinolaryngology, University Hospital, Faculty of Medicine of Ribeira ˜o Preto, USP. All the patients were submitted to clinical history and exam (with anterior rhinoscopy and nasofibroscopy), acoustic rhinometry and rhimomanometry. The last two exams were carried out using the SR 2000 apparatus of Rhinometrics (Denmark), and nasal adaptors for children were

used. These exams were performed without previous vasoconstriction so that we could evaluate the response of nasal mucosa to the bony expansion. In acoustic rhinometry, the patients were instructed not to breathe during the measurements until a minimum of three valuable curves were obtained [1]. The exams were recorded on a rhinogram, with separate measurements presented on the right and on the left side. The distance was correlated to the minimal cross-sectional area (MCA), expressed in mm. The following measurements were made: MCA 1–—at the level of the nasal valve, with a distance of 0—22 mm from the adaptor; MCA 2–—at the level of the inferior turbinate, with a distance of 22—54 mm from the adaptor. For rhinomanometry, the patients were oriented to breathe through their nose, and the nasal resistance was evaluated at 150 Pa, as stated by Clement et al [2], during both inspiration and expiration. Three measures were obtained. Nasofibroscopy was performed in every patient in order to determine the pathological respiratory changes, such as hypertrophy of the inferior and middle turbinates, pharyngeal tonsils hypertrophy, nasal tumors, and septal deviations. This exam was performed after acoustic rhinometry and rhinomanometry so that vasoconstriction (used routinely for this exam in our service) and the passage of the tube through the nose would not impair the determinations made in the two other exams. These exams were obtained before (T1), immediately after (T2) and 90 days after (T3) rapid maxillary expansion.

3.1. Orthodontic procedures Rapid maxillary expansion is indicated in orthodontics for the purpose to correct maxillary atresia. It provides an orthopedic movement of maxillary bones, opening of median palatine suture and increasing the transversal width of maxilla. The most important sites of resistance to the expansion are in adjacent structures of maxilla with craniofacial complex, particularly in zygomatic and sphenoid bones. Thus, the separation of maxillary bones becomes in a triangular form, with the basis towards the lips, and is higher anteriorly than posteriorly.

Effect of rapid maxillary expansion on the dimension Complete orthodontic documentation (lateral and posteroanterior cephalometric radiographs, study models, extraoral front and profile photographs, and intraoral photographs) was obtained at T1, T2 and T3. After analysis of the initial documentation and the planning of orthodontic treatment, tooth- and mucosa-supported orthodontic braces — Haas disjunctor — were mounted [3] for the correction of uni- or bilateral crossbite. The braces were installed and activated according to the principles presented by Haas [3].

3.2. Statistical analysis The data obtained by acoustic rhinometry, computed rhinomanometry and nasofibroscopy were tabulated and analyzed statistically. The Hotteling T2 test was used to compare the mean values of each variable at the three time points in the study in order to test the following hypotheses: H0: mt1 = mt2 = mt3 H1: some mti 6¼ mtj for i 6¼ j where mti is the mean for the variable j at time i. The use of this test is justified by the fact that the mean values of a variable at the different time points may be correlated (repeated measures). This study was submitted to IRB and approved, under the local number 2003.1.25.58.0.

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4. Results 4.1. Nasofibroscopy Anterior nasofibroscopy revealed that the inferior nasal turbinates were normal in 7 patients and enlarged in 22. Among the latter patients, the inferior turbinates were hyperemic in 2, pale in 18, and colored in 2. The exams of the nasal septa revealed that 16 were centered and 13 had deviation. Among the patients as a whole, 2 had been submitted to total adenoidectomy, 18 had 10—40% obstruction of the cavum, 6 had 50% obstruction, and 5 had 60—90% obstruction.

4.2. Cephalometry The cephalometric measure corresponding to the bony nasal distance in posteroanterior X-ray demonstrated a significant higher distance after rapid maxillary expansion (T1 = 24.91 versus T2 = 26.21, p < 0.001); this expansion was maintained stable 90 days after orthodontic correction (T3 = 26.38 versus T2 = 26.21, NS p).

4.3. Acoustic rhinometry The means and standard deviation of each acoustic rhinometry variable, MCA 1 and MCA 2, as well as the result of the test of equality of the means, are listed

Table 1 Mean values and standard deviations of acoustic rhinometry before orthodontic treatment and immediately and 90 days after treatment, calculated F-value and value of the Hotteling T2 test for equality of the means Measurement

Time

Mean

Standard deviation

F2,27

Test value

MCA-1

T1 T2 T3

0.987 1.006 0.973

0.191 0.182 0.196

0.596

0.558

MCA-2

T1 T2 T3

0.732 0.780 0.763

0.223 0.200 0.248

1.025

0.372

Table 2 Mean values and standard deviations of inspiration and expiration before orthodontic treatment and immediately and 90 days after treatment, calculated F-value and value of the Hotteling T2 test for equality of the means Measurements

Time

Mean

Standard deviation

F2,27

Test value

Inspiration

T1 T2 T3

3.368 2.859 2.231

1.226 1.460 0.763

11.570

<0.001

Expiration

T1 T2 T3

2.675 2.271 1.828

0.943 1.365 0.599

10.064

0.000

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C. Enoki et al.

Table 3 Mean values and standard deviations of the differences in the respiratory measurements of the same variable between two times and value of the Bonferroni multiple comparison test Measurement

Times

Mean value of the differences

Standard error

Test value

Inspiration

T1—T2 T1—T3 * T2—T3

0.509 1.136 0.628

0.368 0.261 0.266

0.535 <0.001 0.076

Expiration

T1—T2 T1—T3 * T2—T3

0.404 0.846s 0.442

0.310 0.201 0.239

0.612 0.001 0.225

*

The mean value of the differences was significant at the 0.05 level.

in Table 1. There was no statistically significant difference between the measurements obtained at the three time points of the study. There was no difference in minimal cross-sectional area at the level of the nasal valve and of the inferior turbinate after rapid maxillary expansion.

4.4. Computed rhinomanometry The mean values, the standard deviations and the tests for equality of the means at the three time points of the study regarding the results of rhinomanometry are presented in Table 2. For the variables for which the hypothesis of equality of the means was rejected, multiple comparison of the means was performed by the Bonferroni test (Table 3). The results demonstrated that mean inspiration and expiration resistance lowered progressively and reached statistical difference between T1 and T3.

5. Discussion Oral breathing is not physiological, being present only when nasal breathing is deficient. Respiratory obstruction and its effects on the development of malocclusion and on facial growth continue to be debated after almost one century of controversy [4]. Totally oral breathing is seldom detected; rather, what is observed is mixed breathing with a predominance of oral breathing [5]. Acoustic rhinometry and computed rhinomanometry are the most specific and objective methods currently used to assess nasal patency [6], while CT and MRI are too costly for routine use. The diagnosis of respiratory obstruction is made upon adequate anamnesis and clinical and imaging exams. However, the limit between nasal and oral breathing is difficult to be established [7]. In the present study, children with uni- or bilateral posterior crossbite and with oral and/or mixed breathing were selected on the basis of both otorhinolaryngo-

logical and orthodontic clinical examination and anamnesis. A definitive diagnosis of oral breathing was made by an otorhinolaryngologist on the basis of history, physical examination and complementary exams such as acoustic rhinomanometry, computed rhinomanometry and nasofibroscopy. Nasal obstruction may result be partial or total. Turbinate hypertrophy is among the most important etiologic factors of oral breathing [8,9]. The association of inferior turbinate hypertrophy with pharyngeal tonsils hypertrophy has been considered to be the most common cause of respiratory obstruction in children [10—12]. In the present study, the obstructive factors of highest incidence observed by nasofibroscopy were inferior turbinate hypertrophy (22 patients), followed by pharyngeal tonsil hypertrophy (16 patients) and septal deviation (13 patients). The children seldom presented more than one factor leading to oral breathing. The use of a topical nasal decongestant is advocated in order to reduce the effects of the nasal mucosa cycle during the exams. In our study we did not use a nasal decongestant at any of the periods analyzed because we opted to evaluate the bony expansion of the nasal fossae in the frontal radiographs, while its effect on the nasal mucosa by acoustic rhinometry and rhinomanometry. We selected children with uni- or bilateral posterior crossbite, which needed to use the Haas disjunctor braces for the correction of this malocclusion. The use of these braces is indicated in orthodontics with the specific objective of promoting orthopedic maxillary expansion to correct the posterior crossbite. During this procedure, weekly monitoring of the activations was performed to avoid excessive expansion, which may provoke vestibular crossbite (Brodie syndrome), an even more severe and complex malocclusion. Several studies have dealt with nasal area and resistance based on the results obtained with rapid maxillary expansion. However, there are differences in the methods used by various investigators. Warren et al. [13,14] studied a sample of 16 children aged

Effect of rapid maxillary expansion on the dimension 10—14 years who were submitted to rapid maxillary expansion with the Haas disjunctor and to radiographic or cephalometric rhinometry before and one year after orthodontic correction. Marchioro and Martins [15] evaluated 27 children aged 6—11 years submitted to the Haas disjunctor, modified, and Bicakci et al. [16] studied 29 patients treated with a disjunctor and an occlusal splint. Both groups used acoustic rhinometry at the same time points as used in the present study, although they also used a nasal decongestant before the nasal exams. The authors reported an increase in the minimal cross-sectional area in all cases after rapid maxillary expansion. However, in the present study we did not detect significant differences in minimal cross-sectional area, neither in the region of the nasal valve nor in the inferior turbinate at the three time points studied. Regarding rhinomanometry, Hartgerink et al. [19] evaluated a sample of 38 patients aged 7.5—22.3 years treated with a Haas disjunctor or an occlusal splint by rhinomanometry at the same time points as used in the present study, but also using a nasal decongestant. Hershey et al. [20] studied 17 patients aged 11—14 years treated with a Haas disjunctor, and Timms [22] evaluated 26 patients aged 10—19 years, with and without the use of a nasal decongestant and with rhinomanometry before and after expansion in both series. All investigators detected a reduction in nasal resistance after expansion. In agreement with these authors, the results of the present study showed that mean nasal resistance during inspiration (inspiration = 2.231 lm/cm H2O) and expiration (expiration = 1.828 lm/cm H2O) were significantly lower after treatment than before treatment (inspiration = 3.368 lm/cm H2O and expiration = 2.675 lm/cm H2O). On the other hand, Paiva et al. [23], in a study of 25 children aged 5—10 years treated with a Biederman-type expander and a nasal decongestant, did not detect significant differences in nasal resistance before and after rapid maxillary expansion. Warren et al. [13,14] and Hartgerink et al. [19], respectively, observed that 30 and 35% of the patients submitted to maxillary expansion did not show a change in nasal resistance, indicating that orthodontic treatment does not interfere with breathing. This divergence in literature results may be attributed to the type of expander used for orthodontic correction and to individual patient variation, since part of this response may be due to edema of the nasal mucosa, to nasal polyps, mucosal hyperplasia, allergic rhinitis, and infection. In our study, all patients were evaluated by an otorhinolaryngologist using nasofibroscopy, an exam not used in other

1229 studies. This exam was performed in order to exclude from our sample patients with nasal polyps and infections. All the patients were evaluated before exams, and while with acute nasal diseases, their exam was postponed to a week. The equipment was calibrated before the measurements for each patient, and the noninvasive adaptors were used in order to reduce the risk of distortion of the nasal valve. All the patients were instructed to stop breathing during the measurements of acoustic rhinometry, and to breathe through the nose during the rhinomanometrty in order to reduce variability. Even so, there may be random and/or systemic errors inherent to the technique of acoustic rhinometry whose coefficient of variation is 5%, possibly affecting the results [17,18]. The divergences in the results may also be related to the lack of use of nasal decongestant, which might suggest that, even though there is a bony opening in nasal fossae, the mucosa might respond with edema, and the mucosal effect is less evident than the bony one. The present findings suggest opening of the median palatine suture with rapid maxillary expansion leads to increased nasal bone width and lateralization of the turbinates in relation to the septum. However, we believe that in our study there was partial compensation of the mucosa of the inferior turbinates with edema, which did not demonstrate the real increase in minimal cross-sectional area, but did lessened the nasal resistance during the whole period analyzed. In the present study we detected an increase in the bony dimension of the nasal cavity and a significant improvement of breathing due to decrease nasal resistance, although there was no significant difference in MCA of nasal valve or inferior turbinate. Expansion should be indicated and used by the orthodontist for the purpose of correction of uni- or bilateral posterior crossbite, and may also benefit patients with respiratory difficulties. Even though, the results of the present study do not support the execution of rapid maxillary expansion merely in order to provide benefits for the nasal function of individuals with respiratory difficulties, since mucosal benefits were much smaller than bony ones. However, further studies are needed in order to verify the hypothesis of the action of maxillary expansion on the nasal mucosa.

6. Conclusion On the basis of the present results, we may conclude that there were no differences in the minimal cross-

1230 sectional area at the level of the nasal valve and inferior turbinate between the three times tested in the investigation. However, there was a progressive lessening of nasal resistance during this period. We may conclude that the mucosal benefits of rapid maxillary expansion are not so evident as the bony ones. Thus, this procedure may improve nasal respiration, but cannot be indicated only for this purpose.

C. Enoki et al.

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