INTRODUCTION
The occurrence of maxilla deformities together with respiratory problems, mainly nasal breathing difficulties, has attracted the attention of various researchers to the possibility of these events being correlated1-8.
According to Epker et al.1, some patients that need orthognathic surgeries have a coexistent nasal deformity that can have significant functional or esthetical implications. When there is concomitant nasal deformity, it is convenient for both the patient and the professional team to correct it together with the orthognathic repair.
Turvey & Hill6 described that maxillary osteotomy aim at improving esthetical and occlusion function, breathing, swallowing and speech. They reported that objective studies of the nasal cavity in candidates to orthognathic surgery of the maxilla have shown increase in nasal air resistance. They suggested that septal deviations and hypertrophic nasal turbinates could be treated at the same time as the maxillary surgery. These factors favor the dentofacial deformity repair and the elimination of the preexisting nasal obstruction.
The literature reveals innumerous studies reporting nasal obstruction relief after opening of midpalatal suture3, 9, 10. Other authors emphasized that in spite of the benefits in the nasal cavity resulting from rapid expansion of the maxilla, the procedure is not purely justified by providing improvement of the nasal function in subjects with respiratory difficulty unless the cause of the obstruction is located in the anterior-posterior portion of the nasal cavity, exactly where the region of smallest transversal section of the nose is located7, 8.
Of all classification methods of malocclusion, the Angle system11 is the most traditional one. It is based on anterior-posterior relations of the maxillas: class I - normal anterior-posterior relation of the maxilla; class II - there is distal relation of the mandible and maxilla; class III - there is mesial relation of the mandible and maxilla. Angle system does not take into consideration the discrepancies of the vertical or lateral plan, which can lead to non-observance of problems such as overbite and transversal deficiency of dental arches.
Crossbite is the term used to indicate abnormal buccal-lingual relation of the teeth. The most common crossbite is the one in which buccal cuspids of some upper teeth occlude lingually with the buccal cuspids of lower teeth. Posterior crossbite can be classified as dental, functional or skeletal. Dental crossbite involves only incorrect inclination of the teeth on the alveolar bone, and there is no abnormality in size or shape of the basal bone12, 13.
According to Epker et al.14, a transversal maxillo-mandibular discrepancy (maxilla transversal deficiency) is present when the teeth have disparity of arch width, placed in an anterior-posterior class I in cusp relation.
Andrade & Miguel15 examined school-aged children in Rio de Janeiro and found a prevalence of 15.4% of posterior crossbite. The difference between genders was not statistically significant. In the opinion of these authors, crossbite is not self-correctable with time and the tendency is that number of cases will increase as a result of aging.
The etiology of crossbite is not well clarified, reason why we found in the literature various hypothesis about the topic. The upper airway obstruction, with consequent mouth breathing, can be one of the causes. According to Moss's functional matrix theory, the normal air passage through the nasal fossa during breathing comprises a constant stimulus for the lateral growth of the maxilla and for lowering of the palatine vault. Other probable etiological factors include habits of pacifier and/or thumb suction, atypical tongue pressure, posture force produced in the dentofacial area, early loss or prolonged retention of deciduous teeth and lateral deficiency of maxilla, which is genetically determined. Congenital malformations of cleft lip and palate can cause crossbite, but the determining circumstances are different from the one discussed above2, 5, 10, 12, 13, 15-20.
It was attributed to the American author Angell, in 1860, raising the following polemical issue: the possibility of opening the midpalatal suture using orthodontic procedures2, 12, 13. Since it receives directly the pressure from the expander, the maxilla experiences the most sensitive alteration in the three spatial plans. Horizontally, the behavior of the maxilla is easily checked with the help of an occlusion radiograph film. Maxillae are separated at the level of the midpalatal suture, creating a triangular radioluscence with greater opening in the anterior region, where the resistance of facial structures is smaller. Frontally, the separation of the maxillae is also triangular, whose base is directed downwards and the rotation center is located close to the frontal-nasal suture. By decreasing order of magnitude of increase there is: transversal diameter at the dental crowns, alveolar arch, maxillary base and nasal cavity. As a consequence of this triangular opening of the maxillary plans horizontally and frontally, the maxilla is repositioned in the facial complex, displaced downwards and forwards. It is interesting to mention that these skeletal changes tend to reduce the skeletal maturity owing to greater rigidity of maxilla articulation with the face. Many times, upon reaching the skeletal maturity, the inclination of the teeth and the alveolar process are the only responses to quick expansion. Owing to this biological limitation, various types of maxillary osteotomy have been developed to be performed concomitantly with quick expansion apparatus, the so-called orthodontic-surgical expansion, intending to facilitate the lateral maxillary movement in adult patients13, 14, 21.
There are three ways to correct the transversal discrepancy: (1) orthodontic, using rapid maxilla expansion; (2) osteogenic distraction, formally called surgical assistance to rapid maxilla expansion, and (3) reconstructive orthognathic surgery14.
In adult patients, the use of expanders for significant increase of maxillary arch has been described as insufficient and the possibility of palatine expansion in adolescents in the final stages of growth and close to the age of 20 is questionable. In such situations, surgically assisted maxillary expansion has been advocated3, 4, 14, 22. The surgery is necessary because maxilla expansion does not happen spontaneously or can recur and in many occasions there are undesirable sequelae, such as pain, ulceration, excessive inclination of posterior teeth, gingival retraction and resorption of the alveoli in the vestibular aspect.
The incidence of septal deformities varies in different publication23-25. Gray & Brogan9 investigated 2,112 adult skulls and in only 21% of the cases the septum seemed to be centered.
Septal deformities were classified into areas 1, 2, 3, 4 and 5 according to the topography of the involved nasal cavity (Cottle classification)26: Area 1 (vestibular area) - region of the nasal vestibule; area 2 (area of basal valve) - region that corresponds to the limit between the upper and lower lateral cartilage; area 3 (attic area) - region behind and above the nasal valve, under the bones of the nose; area 4 (anterior concha area) - region corresponding to the cartilaginous and bone septum, opposite to the turbinates; area 5 (posterior concha area) - region located adjacent to the choana.
Intranasal examination using anterior rhinoscopy and indirect nasofibroscopy provide limited data over the most posterior segments and the lateral wall so the nasal cavity. Currently, telescopes for nasal endoscopy provide images with luminosity, clearness and high quality resolution, providing evident and undoubtedly advantages over conventional methods of exam27, 28.
The purposes of the present study were: 1 - to assess the occurrence of nasal obstruction complaints in patients who have skeletal posterior crossbite; 2 - to assess the occurrence of septum deformities in adult patients with skeletal posterior crossbite through nasal videofibroscopy; 3 - to check whether videofibroscopy assessment of the nasal cavity can help in the indication of nasal functional corrective surgery concomitant to surgically-assisted rapid maxilla expansion.
MATERIAL AND METHOD
We selected adult patients who had skeletal posterior crossbite (unilateral or bilateral). We studied 30 patients, being 14 male and 16 female subjects assessed between January 1999 and April 2000. The mean age of the studied group was 28.5 years, the minimum age was 16 and the maximum age was 49 years. We selected adult patients who had already completed maxilla-mandible and septal growth.
Patients were referred from dental surgeons, specialized in orthodontics for ENT assessment before dental treatment. The patients were candidates for orthodontic treatment with indication for surgically assisted rapid maxilla expansion.
We excluded from the sample patients that belonged to the following groups: previous and/or current orthodontic treatment, previous nasal surgery, previous facial fracture, patients with absence of teeth that hindered the diagnosis of posterior crossbite, and patients with cleft lip and/or palate.
Patients were submitted to complete clinical ENT examination and nasal videofibroscopy with flexible endoscope brand Machida, with 3.4 mm diameter. The exam was recorded in videotapes. The examiner, an otorhinolaryngologist, upon making the diagnosis by endoscopic vision, did not know further data of the patient. Septum deformities were classified into areas 1, 2, 3, 4, and 5 according to the topography of the involved nasal cavity (classification by Cottle-Rees).
RESULTS
Of the 30 assessed patients, 25 (83.3%) presented bilateral posterior crossbite and 5 (16.7%) presented unilateral crossbite. Seventeen patients (56.7%) reported nasal obstruction and 13 (43.3%) did not have respiratory complaints. Considering the patients with nasal obstruction, 58.8% presented bilateral complaint, being 41.2% with unilateral nasal obstruction. Of the 7 patients with unilateral obstructive complaint, in 5 of them the obstructed side was the same as the septal deformity detected in the nasofibroscopic exam and in only 2 of them the obstructed side was contralateral to the septal deformity.
As to Angle classification, we detected predominance of neutral occlusion (class I = 22 - 73.3%). We diagnosed 7 patients with distal occlusion (class III), corresponding to 23.3% of the examined sample and only one patient with mesial occlusion (class II), which corresponded to 3.3% of the sample. We found 5 patients who presented anterior open bite, amounting to 16.7% of the total studied patients.
As to nasal septum fibroscopic exam, we detected the presence of septal deformity in 100% of the studied cases. In 22 patients (73.3%), we diagnosed septal deformity projecting to one side of the nasal cavity, and in 8 patients (26.7%), the septal deviation projected to both sides of the nasal cavity.
As to topographic diagnosis of septal deformity at nasofibroscopic exam, we detected the following occurrence, according to Cottle classification:
Right side
Area I - 6.7%
Area II - 46.7%
Area III - 50%
Area IV - 43.3%
Area V - 0%
Left side
Area I - 6.7%
Area II - 50%
Area III - 50%
Area IV - 53.3%
Area V - 3.3%
Considering the occurrence of septal deformity concomitantly on the right and/or left side, we detected:
Area I - 13.4%
Area II - 83.3%
Area III 90%
Area IV - 83.3%
Area V - 3.3%
DISCUSSION
The occurrence of septal deformity found in our study was of 100%. The predominance was with presence of septal deformities in Areas 3 (90%), 2 (83.3%), and 4 (83.3%) of Cottle. The impairment of area 1 occurred in 13.4% and in area 5 in 3.3% of the cases. This high occurrence of septal deformity, compared to other studies that investigated the prevalence of septal deformity, maybe can be explained by the method used in our assessment.
Blaugrund23 reported that septal deformity occurred in approximately 20% of the population and it was more frequent in adults than in children. Haapaniemi24 studied the occurrence of septal deformity in school children aged 6-15 years using anterior rhinoscopy and facial x-rays (occipital-mentonian incidence). The study included a total of 687 children. Clinical diagnosis of septal deformity was made in 9.5% of the children. Septal deviation was found in 21.2% of the examined radiographs. We used nasal videofibroscopy 27 in our study, a method that is more sensitive than anterior rhinoscopy and face x-rays, which were employed by other authors. The use of anterior rhinoscopy hinders the examination of the most posterior portions of the nasal septum, even when performed after vasoconstriction. We would like to point out the great incidence of septal deformities in area 4 of Cottle (83.3%), a region that is difficult to be assessed without telescopes25-27. The studied sample may have contributed to the high occurrence of septal deformity, because there are various studies correlating chronic nasal obstruction and posterior crossbite 11, 12, 15. Nasal respiratory function and its influence on the development of the craniofacial complex has been object of debate for over one century. Clinical observations and experimental evidence suggest that chronic mouth breathing during critical periods of development can cause problems in facial morphology. Posterior crossbite was frequently found in such studies5, 9, 16-20.
Since we excluded patients who had well documented history of facial trauma (that is, of nasal trauma as well), we could expect this fact to cause a reduction of the incidence of septal deformity in the group, since nasal trauma is one of the causes of septal deviation. However, we did not detect this interference in our study.
We can discuss the possibility of having maxilla transversal deficiency as the cause of abnormalities in the septal growth. We wonder whether a more deficient palate, which sometimes have a high position, could prevent vertical growth of the septum, forcing it to lateral displacement. Area 4 of Cottle coincides with the shock zone of nasal septum growth, as denominated by Sampaio & Caropreso28.
Many clinical studies reported improvement of nasal breathing, and even complete resolution of nasal obstruction, after maxilla expansion procedures3, 9, 10. The great majority states that the results were based on patients' report, and they lack objective data. Wertz8 stated that if the main purpose of opening the midpalatine suture is to improve the nasal permeability, it has no proper justification, unless the obstruction is located in the most anterior and most inferior portion of the nasal cavity.
Warren et al.7 studied the correlation between rapid maxilla expansion, surgical expansion of maxilla, nasal cavity dimension and nasal airflow. The data of such study support the idea that rapid maxilla expansion reduces the nasal airflow resistance and improves nasal breathing. They consider that both procedures - orthodontic expansion and surgical expansion - affect the nasal valve, which presents the smallest section area and provides the greatest resistance to nasal airflow during breathing. They assume that maxilla constriction produces a narrow nasal valve and they believe that maxilla expansion improves nasal airflow by increasing the width of ala and nasal valve. They concluded in the study, based on rhinomanometric data, that despite the reduction of nasal airflow resistance in patients with posterior crossbite submitted to rapid maxilla expansion, a great percentage of the patients would presumably remain mouth breathers, unless nasal surgery was also performed.
Various authors pointed out that rapid maxilla expansion causes an enlargement of the nasal floor, more on the anterior region than on the posterior region and more on the inferior than on the superior region of the nasal cavity2, 6, 7, 12, 13. We believe that the septal deformities that are more likely to be impacted by rapid maxilla expansion, causing reduction of nasal airflow resistance and improvement of nasal obstruction, are those deviations located in Areas 1 and 2 of Cottle, the most anterior regions of the nasal cavity. In our study, we noticed that only in 5 patients (16.7% of the cases) areas 4 and 5 were not affected by septal deformities. In only 2 patients, areas 1 and 2 were solely impaired.
In order to conduct orthodontic-surgical treatment in rapid maxilla expansion, the surgical procedure can be performed under general or local anesthesia, depending on the experience and preference of the professional. The ambulatory procedure has the advantage of being cheaper to the patient, since it does not require hospitalization4. However, as to local anesthesia, less experienced surgeons can face problems with excessive bleeding and the risk of inappropriate expansion21, 22. Epker et al.14 advocated surgically-assisted rapid maxilla expansion under general anesthesia, conducting the classical osteotomy of Le Fort I, associated with medial osteotomy of anterior nasal spine and palate.
If we consider the performance of maxilla disjunction under general anesthesia and the patient has ENT examination with indication for functional endonasal endoscopic surgery for nasal obstruction, based on our results, we believe that both procedures can be performed concomitantly. Joint surgery (maxillo-facial and ENT) imply reduction of expenses by the patient because it does not require two consecutive hospitalizations. Moreover, maxilla orthognathic surgery and nasal surgery can be performed in the same surgical act gaining time and possibly adding more stability of the orthodontic treatment1, 5. Therefore, it is important to conduct systematic assessments through nasofibroscopy of nose physiology and anatomy in patients who have maxilla deficiency and indication for surgically-assisted rapid orthodontic expansion of maxilla. Therefore, when there is suspected or documented inappropriate nasal function, involving mainly the nasal septum or turbinate, the possibility of integrating the surgical treatment by maxillo-facial surgeon and otorhinolaryngologist should be considered.
CONCLUSIONS
1. The presence of skeletal posterior crossbite in adult patients does not necessarily imply nasal obstruction.
2. It is important to use nasofibroscopy in the diagnosis of septal deformity in adult patients with skeletal posterior crossbite.
3. Adult patients with skeletal posterior crossbite in which surgically-assisted rapid maxilla expansion has been planned and the patient present damage of the nasal function at the cost of the septal deformity, the performance of the two procedures - maxilla osteotomy and septoplasty - on the same operative act should be considered.
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1 Master in Otorhinolaryngology, Medical School, University of São Paulo - Ribeirão Preto - SP, Professor, Discipline of Oral and Maxillo-Facial Surgery, Dental School, UNIC and UNIVAG - MT.
2 Ph.D., Professor, Discipline of Otorhinolaryngology, Medical School, University of São Paulo - Ribeirão Preto - SP.
Address correspondence to: Faculdade de Medicina de Ribeirão Preto USP - Av. Bandeirantes, 3900 Ribeirão Preto - SP Brazil 14049-900 - Tel (55 16) 602-3000 Fax (55 16) 602-2860
E-mail: ramancio@fmrp.usp.br/ betononaes@terra.com.br
Study presented at 35º Congresso Brasileiro de Otorrinolaringologia, held in Natal-RN, on October 16-20, 2000.
Article submitted on February 16, 2001. Article accepted on August 15, 2002
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