- Email: [email protected]
Surgically assisted rapid maxillary expansion: feasibility of not releasing the nasal septum
Int. J. Oral Maxillofac. Surg. 2013; 42: 321–325 http://dx.doi.org/10.1016/j.ijom.2012.09.021, available online at http://www.sciencedirect.com
Clinical Study Orthognathic Surgery
Surgically assisted rapid maxillary expansion: feasibility of not releasing the nasal septum
K. E. Reinbachera, J. Wallnera, M. Paua, M. Feichtingera, H. Ka¨rchera, F. Quehenbergerb, W. Zemannc a Department of Maxillofacial Surgery, Medical University of Graz, Austria; bInstitute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Austria; cDepartment of Maxillofacial Surgery, Medical University of Zurich, Switzerland
K. E. Reinbacher, J. Wallner, M. Pau, M. Feichtinger, H. Ka¨rcher, F. Quehenberger, W. Zemann: Surgically assisted rapid maxillary expansion: feasibility of not releasing the nasal septum. Int. J. Oral Maxillofac. Surg. 2013; 42: 321–325. # 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. Surgically assisted rapid maxillary expansion (SARME) is commonly used to correct maxillary transverse deficiency. The aim of this study was to analyse the need for intraoperative liberation of the nasal septum during the procedure. SARME was performed in 25 patients by combining a lateral osteotomy with an interradicular maxillary osteotomy. The deviation of the nasal septum after SARME was evaluated by comparing measurements between radiologically defined landmarks on pre- and postoperative computed tomographic images. Two defined angles (angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi; angle II, between maxillary plane and septum nasi) were measured based on four representative planes and septal movement was analysed. The mean changes in angles I (0.038 0.788) and II (0.258 1.048) did not differ significantly from zero (p = 0.87 and p = 0.24, respectively). Observed variations and displacements were considered to be acceptable because they were insignificant in every respect. Intranasal airway function was also examined pre- and postoperatively to evaluate any loss of ventilation. The described surgical technique is a successful method of maxillary segment distraction. The authors found no compelling reason to release the nasal septum in the context of SARME.
Surgically assisted rapid maxillary expansion (SARME) is a form of surgical distraction first described theoretically by Codivilla.1 It was introduced in 1938 as a combined surgical and orthodontic treatment. Today, SARME is considered to be a valid treatment for severe transversal maxillary discrepancy and dental crowding.2 Patients undergoing this procedure must be skeletally mature, present a certain 0901-5027/030321 + 05 $36.00/0
transverse maxillary hypoplasia, and/or have a failed orthodontic maxillary expansion.3 Thus, SARME is commonly used to correct skeletal maxillary transversal deficiency in cases of intermaxillary suture ossification and is a widely accepted surgical technique in patients older than 15 years with a transverse maxillary deficiency > 5 mm.4–6 Although SARME is a well-established treatment, no significant
Key words: Deviation; Maxillary transverse deficiency; Nasal septum; SARME; Surgically assisted rapid maxillary expansion.. Accepted for publication 26 September 2012 Available online 23 October 2012
consensus on surgical technique has been reached, apart from the use of minimally invasive and more invasive osteotomies.7 A wide variety of methods (e.g. osteotomy, structure release) and materials (e.g. boneor tooth–borne distractors) are used to correct transverse maxillary deficiencies.2,4 A minimal surgical approach is required to produce consistent and stable maxillary expansion in adults.8 The intermaxillary
# 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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suture and pterygomaxillary buttress offer the most resistance to maxillary expansion. Palatinal and lateral osteotomies are common and accepted SARME techniques because they produce stable maxillary expansion.2,9–12 Treatment of the nasal septum also varies; it is frequently released from its palatal base to avert septal deviation, septum side-shifting, and nasal airway changes.2 The aim of this study was to analyse the need for nasal septum liberation by surgical sectioning in the course of a SARME.
Materials and methods
This retrospective study included 25 patients treated in the Department of Oral and Maxillofacial Surgery (Graz, Austria). Inclusion criteria were: cross bite with transverse loss of distance of >5 mm, closed intermaxillary suture, age >16 years, and availability of complete records, including pre- and postoperative computed tomography (CT) scans. Syndromic patients and those with cleft lip and palate or cleft palate, severe asymmetry, and/or limited periodontal health were excluded.
Surgical treatment
The same surgical treatment was performed in all patients by experienced senior surgeons (S.G., K.H., S.M., F. M., R.K.). In all 25 cases, SARME was performed under general anaesthesia by combining a lateral osteotomy through the zygomatic buttress from the piriform rim to the maxillopterygoid junction with an inter-radicular max-
Fig. 1. Haas-type expander13 used to distract maxillary segments.
illary osteotomy (sagittally between the roots of the central incisors). Distraction, activation period, and retention
A Haas-type expander13 (Fig. 1) was used to distract the hypoplastic maxillary segments. The bands of the Haas device were mounted on the first premolars and molars in all patients. Two days postoperatively, the patients began to activate the distractor twice per day (one turn in the morning, one in the evening; 1 mm/day) until achieving 3 mm over-expansion. The Haas device13 was kept in place for at least 12 weeks for retention. Radiological evaluation
The displacement or deviation of the nasal septum after SARME was evaluated by comparing defined landmarks on coronal
Fig. 2. Measurement of angles I and II using anatomic landmarks on CT images. Preoperative (left) and postoperative (right) examples drawn from 25 cases. Upper: angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi. Lower: angle II, between the maxillary plane and septum nasi.
CT scans (1.5 mm slices; Siemens, Erlangen, Germany). In all patients, CT images were acquired preoperatively to exclude the presence of inflammatory processes and 6–8 weeks postoperatively for three-dimensional planning of orthognathic or oral surgery. Measurements were taken between anatomical landmarks on CT images based on four representative maxillary planes that were drawn to define two angles (Fig. 2): angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi; and angle II, between the maxillary plane and septum nasi. Measurements of both angles were compared to assess septal deviation
Table 1. Statistical calculations of measured angles I and II. Variant 1
Variant 2
Mean diffa
I
Preop S Preop R Postop S Postop R Postop S (mean) Postop R (mean) Preop S (mean) Postop S (mean) Postop (all mean)
Preop S 2 Preop S 2 Postop S 2 Postop R 2 Preop S (mean) Preop R (mean) Preop R (mean) Postop R (mean) Preop (all mean)
II
Preop S Preop R Postop S Postop R Postop S (mean) Postop R (mean) Preop S (mean) Postop S (mean) Postop (all mean)
Preop S 2 Preop R 2 Postop S 2 Postop R 2 Preop S (mean) Preop R (mean) Preop R (mean) Postop R (mean) Preop (all mean)
Angle
p-Value
SDa
SEa
0.004 0.028 0.044 0.012 0.264 0.24 0.008 0.016 0.252
0.79 0.17 0.17 0.48 0.22 0.26 0.44 0.30 0.24
0.07 0.10 0.16 0.08 1.04 1.04 0.05 0.08 1.04
0.01 0.02 0.03 0.02 0.21 0.21 0.01 0.02 0.21
0 0 0.06 0 0.05 0 0.08 0.13 0.025
1.00 1.00 0.19 1.00 0.76 1.00 0.29 0.07 0.87
0.29 0.41 0.22 0.00 0.81 0.84 0.37 0.35 0.78
0.06 0.08 0.04 0.00 0.16 0.17 0.07 0.07 0.16
Pre- and postoperative measurements were performed twice (variants 1 and 2) by two authors (a senior surgeon (S) and a radiologist (R)). Preop, preoperative; postop, postoperative; mean diff, mean difference; SD, standard deviation; SE, standard error. a Given in degrees.
Feasibility of not releasing the nasal septum in SARME (Fig. 2). All pre- and postoperative measurements were taken twice (variants 1 and 2) by two observers (a senior surgeon (S) and a specialised radiologist (R); Table 1).
Clinical evaluation
Intranasal or nasal airway evaluation was performed by nasal endoscopy and clinical examination. Nasal endoscopy was indicated by preoperative information and performed postoperatively to detect any secondary effect of the intervention. The patients were also asked to report any change in nasal breathing or ventilation, or any loss of air during sleep.
Statistical analysis
The study group consisted of 25 patients (12 males, 13 females) with a mean age of 30 (range 17–41) years. Variation in measurement was divided into systematic (mean) and random (standard deviation) components, and measurement errors were assumed to add up at the variance scale (law of error propagation). Systematic and random measurement components are given as means standard deviations. Measurement variation was categorised into three hierarchical variance components (inter-observer, intra-observer, displacement) by calculating the corresponding means as variances. The overall observer error was defined as the total of the inter- and intra-observer errors. Details of the calculations can be obtained from the corresponding author. Student’s one-sample t-test was used to evaluate systematic differences between observers or displacements before and after the operation. Analyses of variance between the mean measurements of two observers were used to test for non-zero random displacements. Following the limits of agreement presented by Bland and Altman,14,15 the limits of displacement were defined as systematic displacement 1.96 times the standard deviation of displacement measured once by a single observer. The authors expected that 95% of future displacements would occur between these limits. Systematic displacement was set to zero if the null hypothesis of zero displacement was not rejected. p < 0.05 was considered statistically significant. The R statistical software (ver. 2.13.216) was used to perform calculations. Scientific notation (e.g. 2e 5 = 0.00002) was used for very small p-values.
Results
The study group consisted of 25 patients (12 males, 13 females) with a mean age of 30 (range 17–41) years. No considerable problem other than swelling and haematoma occurred intra- or postoperatively. Haematoma did not require drainage. The majority of patients reported minimal postoperative pain. Radiological evaluation
Measurements are shown as statistical calculations in Table 1. Angle I was 0.088 1.338 preoperatively and 0.118 1.48 after the operation, based on the mean of two observers’ measurements. Neither the preoperative (p = 0.76) nor the postoperative (p = 0.71) angle differed significantly from 08. The mean change (0.038 0.788) did not differ significantly from zero (p = 0.87). No significant mean difference was found between observers (p = 0.095).
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The random measurement errors of angle I in standard deviations were 0.198 within and between 0.168. The overall observer error was 0.258. The random displacement caused by the operation was 0.758. The null hypothesis that there would be no random displacement was thus rejected (p = 2.7e 11). When observer error was added to the calculation, the random displacement was 0.838. The 95% limits of displacement were 08 1.638. Angle II was 91.28 5.88 preoperatively and 91.28 5.88 after the operation, based on the mean of two observers’ measurements. Neither the preoperative (p = 0.16) nor the postoperative (p = 0.11) angle differed significantly from 908. The mean change (0.258 1.048) did not differ significantly from zero (p = 0.24). No significant mean difference was found between observers (p = 0.086). The random measurement errors of angle II in standard deviations were
Table 2. Distribution of pre- and postoperative displacements of anatomic angles I and II, assuming a normal distribution.
The area under the curve gives the probability of observing a certain displacement. The solid line indicates the density of displacements without measurement errors. The dotted line indicates the density of displacements containing the measurement error of one observation by one observer. The horizontal line below the densities marks the 95% limits of displacement. Vertical tick marks denote displacement measurements from 25 patients. Upper: distribution of displacements (in degrees) of angle I measurements. Lower: distribution of displacements (in degrees) of angle II measurements; because the observer error was very low, the two densities are nearly superposed.
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0.0778 within and between 0.0358. The overall observer error was 0.0858. The random displacement caused by the operation was 1.0378. The null hypothesis that there would be no random displacement was thus rejected (p < 1e 16). When observer error was added to the calculation, the random displacement was 1.0448. The 95% limits of displacement were 2.058. Measurement distributions and displacements are shown in Table 2. Clinical investigation
During the first 6–8 weeks after surgical treatment, intranasal airway evaluation revealed no change in nasal breathing or ventilation, or reduction in the length or quality of sleep. Discussion
SARME is a widely accepted and useful method for the correction of maxillary transverse deficiency in maxillofacial surgery.17,18 This surgical technique is possible when performed as a minimally invasive method (osteotomy of the lateral maxillary wall) and achieves stability comparable to that of more invasive osteotomies.4 The results of the present study indicate no need for the often-performed additional release of the nasal septum from its palatal base to avoid septal side-shifting.3 The observed palatal expansion of 5–11 mm represents most clinical cases. Greater expansion obviously increases the risk of clinically relevant nasal septum deviation, but it is rarely performed; liberation of the nasal septum may be indicated only in such rare circumstances. No significant difference was observed between pre- and postoperative CT-based measurements of septal positioning: angles I and II and mean changes in angles did not differ significantly from zero preor postoperatively, and no significant mean difference was found between observers’ measurements. The null hypothesis that there would be no random displacement can be rejected. The small amount of septal movement may have been caused by insufficient skeletal expansion, but enlargement of the transverse palatal dimension (e.g. by dental tipping) would have no effect on the nasal septum. Zemann et al.19 analysed dentoalveolar changes following SARME and concluded that the amount of dental tipping was minimal compared with the amount of skeletal movement. Schwarz et al.20 reported that nasal septum sectioning to prevent septal deviation by surgical
maxillary expansion is not warranted; they found no significant change in the position of the nasal septum postoperatively.20 Similarly, Seeberger et al.18 found no significant septal deviation. The surgical technique described here (osteotomy of the lateral maxillary wall combined with inter-radicular maxillary osteotomy) has no influence on septal deviation or movement. The authors found no compelling reason to release the nasal septum intraoperatively. SARME has been shown to improve nasal parameters and successfully treat nasal airway resistance, nasal septum deviation, and obstructive sleep apnea.18,21–25 Patients showed no loss of air function in terms of nasal ventilation after undergoing SARME.26 Additionally, volumetric analysis has revealed increased nasal airways after surgical maxillary expansion.27 This finding is in accord with postoperative clinical findings in the present study (clinical examination, upper airway endoscopy, comparison of preand postoperative CT scans, patients’ comments on changes in nasal breathing, nasal ventilation, or loss of air during sleep). The observed variations and displacements were considered to be acceptable because they were insignificant in every respect. In conclusion, SARME is an appropriate method for the correction of transverse maxillary deficiency. The surgical technique of lateral osteotomy combined with inter-radicular maxillary osteotomy successfully distracts the maxillary segments. In the context of SARME, the authors found no compelling reason to release the nasal septum, as very low degrees of septal deviation or side-shifting occurred. SARME does not obstruct nasal airways, diminish nasal parameters, or cause any loss of nasal ventilation postoperatively.
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Competing interests
All authors declare that they have no conflict of interest. Funding
None.
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Ethical approval
Not required.
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References
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1. Codivilla A. On the means of lengthening, in the lower limbs, the muscles and tissues
which are shortened through deformity. Am J Orthop Surg 1905;2:353. Corega C, Corega M, Ba˘ciut¸ M, Vaida L, Wangerin K, Bran S. Bimaxillary distraction osteogenesis: an effective approach for the transverse jaw discrepancies in adults. Chirurgia (Bucur) 2010;105(4):571–5. Koudstaal MJ, Poort LJ, van der Wahl KGH, Wolvius EB, Prahl-Anderson B, Schulten AJM. Surgically assisted maxillary expansion (SARME): a review of literature. Int J Oral Maxillofac Surg 2005;34:709–14. Anttila A, Finne K, Keski-Nisula K, Somppi M, Panula K, Peltoma¨ki T. Feasibility and long-term stability of surgically assisted rapid maxillary expansion with lateral osteotomy. Europ J Orthodont 2004;26:391–5. Bailey LJ, White RP, Proffit WR, Turvey TA. Segmental LeFort I osteotomy for management of transverse maxillary deficiency. J Oral Maxillofac Surg 1997;55:728–31. Betts NJ, Vanarsdall RL, Barber HD, Higgins-Barber K, Fonseca RJ. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthod Orthognath Surg 1995;10:75–96. Verstraaten J, Kuijpers-Jagtman AM, Mommaerts MY, Berge SJ, Nada RM, Schols JGJH. A systematic review of the effects of the bone-borne surgical assisted rapid maxillary expansion. J Craniomaxillofac Surg 2010;38:166–74. Pogrel MA, Kaban LB, Vargervik K, Baumrind S. Surgically assisted rapid maxillary expansion in adults. Int J Adult Orthodont Orthognath Surg 1992;7:37–41. Lehman JA, Haas AJ, Haas DG. Surgical orthodontic correction of transverse maxillary deficiency: a simplified approach. Plast Reconstr Surg 1984;73:62–6. Glassman AS, Nahigan SJ, Medway JM, Aronowitz HI. Conservative surgical orthodontic adult rapid maxillary expansion: sixteen cases. Am J Orthod 1984;86:207–13. MacIntosh RB. Total alveolar osteotomy. J Oral Maxillofac Surg 1974;2:210–8. Timms DJ, Vero D. The relationship of rapid maxillary expansion to surgery with special reference to midpalatal synostosis. Brit J Oral Surg 1981;19:180–96. Haas AJ. Rapid expansion of the maxillary dental arch and nasal cavity by opening the suture. Angle Orthod midpalatal 1961;31:73–90. Altman DG, Bland JM. Measurement in medicine: the analysis of method comparison studies. Statistician 1983;32:307–17. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;327(8476):307–10. Ihaka R, Gentleman R. A language for data analysis and graphics. J Comput Graph Stat 1996;5(3):299–314. Han UA, Kim Y, Park JU. Three-dimensional finite element analysis of stress distribution and displacement of the maxilla
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following surgically assisted rapid maxillary expansion. J Craniomaxillofac Surg 2009;37:145–54. Seeberger R, Kater W, Schulte-Geers M, Thiele OC, Davids R, Hofele CH, et al. Surgically assisted rapid maxillary expansion: effects on the nasal airways and nasal septum. HNO 2010;58:806–11. Zemann W, Schanbacher M, Feichtinger M, Linecker A, Ka¨rcher H. Dentoalveolar changes after surgically assisted maxillary expansion: a three-dimensional evaluation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107:36–42. Schwarz GM, Thrash WJ, Byrd DL, Jacobs JD. Tomographic assessment of nasal septal changes following surgical-orthodontic rapid maxillary expansion. Am J Orthod 1985;87(1):39–45. Altug-Atac AT, Atac MS, Kurt G, Karasud HA. Changes in nasal structures orthopaedic
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and surgically assisted rapid maxillary expansion. Int J Oral Maxillofac Surg 2010;39:129–35. Babacan H, Sokucu O, Doruk C, Ay S. Rapid maxillary expansion and surgically assisted rapid maxillary expansion effects on nasal volume. Angle Orthod 2006;76:66–71. Cistulli PA, Palmisano RG, Poole MD. Treatment of obstructive sleep apnea syndrome by rapid maxillary expansion. Sleep 1998;21:831–5. Gray LP. Septal deformity malocclusion and rapid maxillary expansion. Orthodondist 1972;4:2–14. Hershey HG, Stewart BL, Warren DW. Changes in nasal airway resistance associated with rapid maxillary expansion. Am J Orthod 1976;69:274–84. Baraldi CE, Pretto SM, Puricelli E. Evaluation of SARME using acoustic rhinometry
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and postero-anterior cephalometry. Int J Oral Maxillofac Surg 2007;36:305–9. 27. Basciftci FA, Mutlu N, Karaman AI, Malkoc S, Ku¨c¸u¨kkolbasi H. Does the timing and method of rapid maxillary expansion have an effect on changes in nasal dimensions. Angle Orthod 2002;72(2): 118–23.
Address: Kunt E. Reinbacher Department of Oral and Maxillofacial Surgery Medical University of Graz Auenbruggerplatz 5 A-8010 Graz Austria Tel: +43 316 385 80719 E-mail: [email protected]
Clinical Study Orthognathic Surgery
Surgically assisted rapid maxillary expansion: feasibility of not releasing the nasal septum
K. E. Reinbachera, J. Wallnera, M. Paua, M. Feichtingera, H. Ka¨rchera, F. Quehenbergerb, W. Zemannc a Department of Maxillofacial Surgery, Medical University of Graz, Austria; bInstitute for Medical Informatics, Statistics and Documentation, Medical University of Graz, Austria; cDepartment of Maxillofacial Surgery, Medical University of Zurich, Switzerland
K. E. Reinbacher, J. Wallner, M. Pau, M. Feichtinger, H. Ka¨rcher, F. Quehenberger, W. Zemann: Surgically assisted rapid maxillary expansion: feasibility of not releasing the nasal septum. Int. J. Oral Maxillofac. Surg. 2013; 42: 321–325. # 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. Surgically assisted rapid maxillary expansion (SARME) is commonly used to correct maxillary transverse deficiency. The aim of this study was to analyse the need for intraoperative liberation of the nasal septum during the procedure. SARME was performed in 25 patients by combining a lateral osteotomy with an interradicular maxillary osteotomy. The deviation of the nasal septum after SARME was evaluated by comparing measurements between radiologically defined landmarks on pre- and postoperative computed tomographic images. Two defined angles (angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi; angle II, between maxillary plane and septum nasi) were measured based on four representative planes and septal movement was analysed. The mean changes in angles I (0.038 0.788) and II (0.258 1.048) did not differ significantly from zero (p = 0.87 and p = 0.24, respectively). Observed variations and displacements were considered to be acceptable because they were insignificant in every respect. Intranasal airway function was also examined pre- and postoperatively to evaluate any loss of ventilation. The described surgical technique is a successful method of maxillary segment distraction. The authors found no compelling reason to release the nasal septum in the context of SARME.
Surgically assisted rapid maxillary expansion (SARME) is a form of surgical distraction first described theoretically by Codivilla.1 It was introduced in 1938 as a combined surgical and orthodontic treatment. Today, SARME is considered to be a valid treatment for severe transversal maxillary discrepancy and dental crowding.2 Patients undergoing this procedure must be skeletally mature, present a certain 0901-5027/030321 + 05 $36.00/0
transverse maxillary hypoplasia, and/or have a failed orthodontic maxillary expansion.3 Thus, SARME is commonly used to correct skeletal maxillary transversal deficiency in cases of intermaxillary suture ossification and is a widely accepted surgical technique in patients older than 15 years with a transverse maxillary deficiency > 5 mm.4–6 Although SARME is a well-established treatment, no significant
Key words: Deviation; Maxillary transverse deficiency; Nasal septum; SARME; Surgically assisted rapid maxillary expansion.. Accepted for publication 26 September 2012 Available online 23 October 2012
consensus on surgical technique has been reached, apart from the use of minimally invasive and more invasive osteotomies.7 A wide variety of methods (e.g. osteotomy, structure release) and materials (e.g. boneor tooth–borne distractors) are used to correct transverse maxillary deficiencies.2,4 A minimal surgical approach is required to produce consistent and stable maxillary expansion in adults.8 The intermaxillary
# 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
322
Reinbacher et al.
suture and pterygomaxillary buttress offer the most resistance to maxillary expansion. Palatinal and lateral osteotomies are common and accepted SARME techniques because they produce stable maxillary expansion.2,9–12 Treatment of the nasal septum also varies; it is frequently released from its palatal base to avert septal deviation, septum side-shifting, and nasal airway changes.2 The aim of this study was to analyse the need for nasal septum liberation by surgical sectioning in the course of a SARME.
Materials and methods
This retrospective study included 25 patients treated in the Department of Oral and Maxillofacial Surgery (Graz, Austria). Inclusion criteria were: cross bite with transverse loss of distance of >5 mm, closed intermaxillary suture, age >16 years, and availability of complete records, including pre- and postoperative computed tomography (CT) scans. Syndromic patients and those with cleft lip and palate or cleft palate, severe asymmetry, and/or limited periodontal health were excluded.
Surgical treatment
The same surgical treatment was performed in all patients by experienced senior surgeons (S.G., K.H., S.M., F. M., R.K.). In all 25 cases, SARME was performed under general anaesthesia by combining a lateral osteotomy through the zygomatic buttress from the piriform rim to the maxillopterygoid junction with an inter-radicular max-
Fig. 1. Haas-type expander13 used to distract maxillary segments.
illary osteotomy (sagittally between the roots of the central incisors). Distraction, activation period, and retention
A Haas-type expander13 (Fig. 1) was used to distract the hypoplastic maxillary segments. The bands of the Haas device were mounted on the first premolars and molars in all patients. Two days postoperatively, the patients began to activate the distractor twice per day (one turn in the morning, one in the evening; 1 mm/day) until achieving 3 mm over-expansion. The Haas device13 was kept in place for at least 12 weeks for retention. Radiological evaluation
The displacement or deviation of the nasal septum after SARME was evaluated by comparing defined landmarks on coronal
Fig. 2. Measurement of angles I and II using anatomic landmarks on CT images. Preoperative (left) and postoperative (right) examples drawn from 25 cases. Upper: angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi. Lower: angle II, between the maxillary plane and septum nasi.
CT scans (1.5 mm slices; Siemens, Erlangen, Germany). In all patients, CT images were acquired preoperatively to exclude the presence of inflammatory processes and 6–8 weeks postoperatively for three-dimensional planning of orthognathic or oral surgery. Measurements were taken between anatomical landmarks on CT images based on four representative maxillary planes that were drawn to define two angles (Fig. 2): angle I, between crista galli-symphysis mandibulae and crista galli-septum nasi; and angle II, between the maxillary plane and septum nasi. Measurements of both angles were compared to assess septal deviation
Table 1. Statistical calculations of measured angles I and II. Variant 1
Variant 2
Mean diffa
I
Preop S Preop R Postop S Postop R Postop S (mean) Postop R (mean) Preop S (mean) Postop S (mean) Postop (all mean)
Preop S 2 Preop S 2 Postop S 2 Postop R 2 Preop S (mean) Preop R (mean) Preop R (mean) Postop R (mean) Preop (all mean)
II
Preop S Preop R Postop S Postop R Postop S (mean) Postop R (mean) Preop S (mean) Postop S (mean) Postop (all mean)
Preop S 2 Preop R 2 Postop S 2 Postop R 2 Preop S (mean) Preop R (mean) Preop R (mean) Postop R (mean) Preop (all mean)
Angle
p-Value
SDa
SEa
0.004 0.028 0.044 0.012 0.264 0.24 0.008 0.016 0.252
0.79 0.17 0.17 0.48 0.22 0.26 0.44 0.30 0.24
0.07 0.10 0.16 0.08 1.04 1.04 0.05 0.08 1.04
0.01 0.02 0.03 0.02 0.21 0.21 0.01 0.02 0.21
0 0 0.06 0 0.05 0 0.08 0.13 0.025
1.00 1.00 0.19 1.00 0.76 1.00 0.29 0.07 0.87
0.29 0.41 0.22 0.00 0.81 0.84 0.37 0.35 0.78
0.06 0.08 0.04 0.00 0.16 0.17 0.07 0.07 0.16
Pre- and postoperative measurements were performed twice (variants 1 and 2) by two authors (a senior surgeon (S) and a radiologist (R)). Preop, preoperative; postop, postoperative; mean diff, mean difference; SD, standard deviation; SE, standard error. a Given in degrees.
Feasibility of not releasing the nasal septum in SARME (Fig. 2). All pre- and postoperative measurements were taken twice (variants 1 and 2) by two observers (a senior surgeon (S) and a specialised radiologist (R); Table 1).
Clinical evaluation
Intranasal or nasal airway evaluation was performed by nasal endoscopy and clinical examination. Nasal endoscopy was indicated by preoperative information and performed postoperatively to detect any secondary effect of the intervention. The patients were also asked to report any change in nasal breathing or ventilation, or any loss of air during sleep.
Statistical analysis
The study group consisted of 25 patients (12 males, 13 females) with a mean age of 30 (range 17–41) years. Variation in measurement was divided into systematic (mean) and random (standard deviation) components, and measurement errors were assumed to add up at the variance scale (law of error propagation). Systematic and random measurement components are given as means standard deviations. Measurement variation was categorised into three hierarchical variance components (inter-observer, intra-observer, displacement) by calculating the corresponding means as variances. The overall observer error was defined as the total of the inter- and intra-observer errors. Details of the calculations can be obtained from the corresponding author. Student’s one-sample t-test was used to evaluate systematic differences between observers or displacements before and after the operation. Analyses of variance between the mean measurements of two observers were used to test for non-zero random displacements. Following the limits of agreement presented by Bland and Altman,14,15 the limits of displacement were defined as systematic displacement 1.96 times the standard deviation of displacement measured once by a single observer. The authors expected that 95% of future displacements would occur between these limits. Systematic displacement was set to zero if the null hypothesis of zero displacement was not rejected. p < 0.05 was considered statistically significant. The R statistical software (ver. 2.13.216) was used to perform calculations. Scientific notation (e.g. 2e 5 = 0.00002) was used for very small p-values.
Results
The study group consisted of 25 patients (12 males, 13 females) with a mean age of 30 (range 17–41) years. No considerable problem other than swelling and haematoma occurred intra- or postoperatively. Haematoma did not require drainage. The majority of patients reported minimal postoperative pain. Radiological evaluation
Measurements are shown as statistical calculations in Table 1. Angle I was 0.088 1.338 preoperatively and 0.118 1.48 after the operation, based on the mean of two observers’ measurements. Neither the preoperative (p = 0.76) nor the postoperative (p = 0.71) angle differed significantly from 08. The mean change (0.038 0.788) did not differ significantly from zero (p = 0.87). No significant mean difference was found between observers (p = 0.095).
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The random measurement errors of angle I in standard deviations were 0.198 within and between 0.168. The overall observer error was 0.258. The random displacement caused by the operation was 0.758. The null hypothesis that there would be no random displacement was thus rejected (p = 2.7e 11). When observer error was added to the calculation, the random displacement was 0.838. The 95% limits of displacement were 08 1.638. Angle II was 91.28 5.88 preoperatively and 91.28 5.88 after the operation, based on the mean of two observers’ measurements. Neither the preoperative (p = 0.16) nor the postoperative (p = 0.11) angle differed significantly from 908. The mean change (0.258 1.048) did not differ significantly from zero (p = 0.24). No significant mean difference was found between observers (p = 0.086). The random measurement errors of angle II in standard deviations were
Table 2. Distribution of pre- and postoperative displacements of anatomic angles I and II, assuming a normal distribution.
The area under the curve gives the probability of observing a certain displacement. The solid line indicates the density of displacements without measurement errors. The dotted line indicates the density of displacements containing the measurement error of one observation by one observer. The horizontal line below the densities marks the 95% limits of displacement. Vertical tick marks denote displacement measurements from 25 patients. Upper: distribution of displacements (in degrees) of angle I measurements. Lower: distribution of displacements (in degrees) of angle II measurements; because the observer error was very low, the two densities are nearly superposed.
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0.0778 within and between 0.0358. The overall observer error was 0.0858. The random displacement caused by the operation was 1.0378. The null hypothesis that there would be no random displacement was thus rejected (p < 1e 16). When observer error was added to the calculation, the random displacement was 1.0448. The 95% limits of displacement were 2.058. Measurement distributions and displacements are shown in Table 2. Clinical investigation
During the first 6–8 weeks after surgical treatment, intranasal airway evaluation revealed no change in nasal breathing or ventilation, or reduction in the length or quality of sleep. Discussion
SARME is a widely accepted and useful method for the correction of maxillary transverse deficiency in maxillofacial surgery.17,18 This surgical technique is possible when performed as a minimally invasive method (osteotomy of the lateral maxillary wall) and achieves stability comparable to that of more invasive osteotomies.4 The results of the present study indicate no need for the often-performed additional release of the nasal septum from its palatal base to avoid septal side-shifting.3 The observed palatal expansion of 5–11 mm represents most clinical cases. Greater expansion obviously increases the risk of clinically relevant nasal septum deviation, but it is rarely performed; liberation of the nasal septum may be indicated only in such rare circumstances. No significant difference was observed between pre- and postoperative CT-based measurements of septal positioning: angles I and II and mean changes in angles did not differ significantly from zero preor postoperatively, and no significant mean difference was found between observers’ measurements. The null hypothesis that there would be no random displacement can be rejected. The small amount of septal movement may have been caused by insufficient skeletal expansion, but enlargement of the transverse palatal dimension (e.g. by dental tipping) would have no effect on the nasal septum. Zemann et al.19 analysed dentoalveolar changes following SARME and concluded that the amount of dental tipping was minimal compared with the amount of skeletal movement. Schwarz et al.20 reported that nasal septum sectioning to prevent septal deviation by surgical
maxillary expansion is not warranted; they found no significant change in the position of the nasal septum postoperatively.20 Similarly, Seeberger et al.18 found no significant septal deviation. The surgical technique described here (osteotomy of the lateral maxillary wall combined with inter-radicular maxillary osteotomy) has no influence on septal deviation or movement. The authors found no compelling reason to release the nasal septum intraoperatively. SARME has been shown to improve nasal parameters and successfully treat nasal airway resistance, nasal septum deviation, and obstructive sleep apnea.18,21–25 Patients showed no loss of air function in terms of nasal ventilation after undergoing SARME.26 Additionally, volumetric analysis has revealed increased nasal airways after surgical maxillary expansion.27 This finding is in accord with postoperative clinical findings in the present study (clinical examination, upper airway endoscopy, comparison of preand postoperative CT scans, patients’ comments on changes in nasal breathing, nasal ventilation, or loss of air during sleep). The observed variations and displacements were considered to be acceptable because they were insignificant in every respect. In conclusion, SARME is an appropriate method for the correction of transverse maxillary deficiency. The surgical technique of lateral osteotomy combined with inter-radicular maxillary osteotomy successfully distracts the maxillary segments. In the context of SARME, the authors found no compelling reason to release the nasal septum, as very low degrees of septal deviation or side-shifting occurred. SARME does not obstruct nasal airways, diminish nasal parameters, or cause any loss of nasal ventilation postoperatively.
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Competing interests
All authors declare that they have no conflict of interest. Funding
None.
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Ethical approval
Not required.
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Address: Kunt E. Reinbacher Department of Oral and Maxillofacial Surgery Medical University of Graz Auenbruggerplatz 5 A-8010 Graz Austria Tel: +43 316 385 80719 E-mail: [email protected]