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Nationwide survey of surgically assisted rapid maxillary expansion
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British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
Nationwide survey of surgically assisted rapid maxillary expansion James K. MacLaine ∗ , Ellie M. Thickett, Susan M. Power Orthodontic Department, Royal Bournemouth Hospital, Castle Lane East, Bournemouth, Dorset BH7 7DW, United Kingdom Accepted 10 July 2013 Available online 17 August 2013
Abstract We aimed to gather data on the current practice of surgically assisted rapid maxillary expansion (SARME) in the UK. Surveys were posted in the mail to all members of the British Association of Oral and Maxillofacial Surgeons (n = 379) and 166 (44%) responded. In the previous year 69 responders (42%) had done at least one SARME operation. The technique used by individual surgeons may be more experience-based than evidence-based, which leads to considerable variation. © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Surgically assisted rapid maxillary expansion; Surgically assisted rapid palatal expansion
Introduction Surgically assisted rapid maxillary expansion (SARME) is a technique that uses the concept of distraction osteogenesis to increase the transverse dimension of the maxilla in skeletally mature patients. It is indicated when the dental compensation provided solely by orthodontics is deemed insufficient to correct the discrepancy. The technique relies on strategic surgical releases followed by postoperative activation of an expander device. The basic principle has been known since the early twentieth century and Brown is credited with the first textbook description in 1938.1 In 1954 Heiss2 specified the midline splitting of the maxilla for orthodontic reasons. Historically there was an emphasis on the midpalatine suture as it was thought to be the logical point of resistance that had to be overcome when expanding. However, there is now a consensus that all the maxillofacial complex abutments are important, and together they are more important than the ∗
Corresponding author. Tel.: +44 02820732002. E-mail addresses: [email protected] (J.K. MacLaine), [email protected] (E.M. Thickett), [email protected] (S.M. Power).
midpalatine suture. This view (first suggested by Isaacson et al. in the 1960s3 ) did not achieve widespread acceptance until surgical experience led opinion in that direction in the 1970s and beyond. Unlike the distraction technique for long bones there is no consensus on a standard protocol for SARME. The main variables in technique that have been reported are the type of expander device, the number and distribution of surgical releases, the postoperative latency period, the rate of expansion, and over-correction. To obtain nationwide data on SARME techniques we did a mail-based survey of all members of the British Association of Oral and Maxillofacial Surgeons (BAOMS). We present our results and give an overview of some of the issues involved.
Method We sent a questionnaire to all members of the BAOMS. The Honourable Secretary of the association kindly agreed to provide the names and work addresses of all 379 members. To maximise the response rate, the survey was kept short and
0266-4356/$ – see front matter © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2013.07.002
842
J.K. MacLaine et al. / British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
Fig. 3. Latency period and number of surgeons. Fig. 1. Number of SARME operations in the previous year.
Discussion SARME workload
Fig. 2. Number and type of surgical transections (A = anterior, L = lateral, P = posterior, M = median).
The number of operations done by individual surgeons varied widely (Fig. 1). A small number of surgeons undertake a large number of SARME procedures, but 97 (58%) did none in the past year. There are undoubtedly many reasons for this but it is beyond the remit of this paper to speculate. Tooth-borne compared with bone-borne expanders
succinct, with one-word or tick box answers. The questions asked are shown in Appendix 1. A covering letter accompanied each questionnaire.
Results As a total of 166 questionnaires were returned (response rate of 44%), the survey was considered to be adequately representative. There were no correlations between the experience of the surgeon and any of the variables of the technique. The workload for SARME varies considerably and the number of operations done by individual surgeons is summarised in Fig. 1. There were no correlations between workload and variables of the technique. Regarding the type of expander, most respondents use a tooth-borne expander exclusively (n = 58/74, 78%), while 8/74 (11%) favour the bone-borne version. The remaining 8/74 (11%) use both. The number and type of surgical transections vary considerably (Fig. 2). Almost 70% (n = 52/74) of respondents do anterior, lateral, posterior, and median releases while 26% (n = 19/74) do not release posteriorly (the pterygoid junction). Of the 91% (n = 67/74) that do a median transection, 8 (12%) prefer paramedian releases to the traditional midline split. The latency period (time between the operation and first activation of the expansion device) varies between 0 and 7 days (Fig. 3). The rate of expansion is 1 mm/day for 69% (n = 51/74) of respondents, 0.5 mm/day for 27% (n = 20/74), and 0.25 mm/day for 4% (n = 3/74). Over-correction of the transverse discrepancy is favoured by 23% (n = 17/74) of surgeons, the most common amount being 2 mm or 20%.
The expander of choice in most SARME cases is a toothborne device (n = 58/74, 78%), which extends across the palate and connects the buccal maxillary teeth. The rapid distraction expansion force is transmitted beyond the dental apparatus to the weakened maxillary sutures, which allows for expansion. Bone-borne devices are connected directly to the maxillary apparatus, usually in the palatal vault. Examples are the Trans-Palatal Distractor (TPD) (DB Orthodontics Ltd., Silsden, UK),4 the Magdeburg Palatal Distractor (KLS Martin, Tuttlingen, Germany), and the Rotterdam Palatal Distractor (KLS Martin, Tuttlingen, Germany).5 The supposed advantages of bone-borne distractors are fewer, if any, dental side effects, a greater mechanical advantage from the distraction force being closer to the centre of the maxilla, and a more stable result. However, in a randomised controlled trial that compared the Rotterdam Palatal Distractor with a tooth-borne device, Koudstaal et al.6 showed no difference between the devices for the above-mentioned issues. The disadvantages are the considerably higher cost, the mechanical complexity, and sensitivity to technique, which for most clinicians would tip the balance in favour of the tooth-borne expander. In our survey 78% (n = 58/74) of surgeons use only a tooth-borne expander, 11% (n = 8/74) use only a bone-borne expander, and 11% (n = 8/74) use both. Surgical transections Isaacson et al.,3 and Isaacson and Ingram7 showed that the main site of resistance is not the midpalatine suture, but the remaining maxillary articulations: anterior, lateral, and posterior. The distraction technique primarily involves the release
J.K. MacLaine et al. / British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
843
Fig. 4. Three-quarter view of the skull and palatal view showing the types of transection (anterior and lateral transections: purple line; posterior transection: blue line; median transection: pink line; paramedian transection: green line).
of them and of the midpalatine (median) suture. Anatomically, they are the piriform aperture (anterior), the zygomatic buttress (lateral), the pterygoid junction (posterior), and the midpalatine suture (median). Early techniques described the transection of all of them,8–10 but with the emphasis on reduced surgical morbidity it has been suggested that fewer supports are osteotomised: anterior, lateral, and median11 ; lateral and median12 ; anterior, posterior, and lateral13 ; and anterior and lateral.14 Although there is a trend towards fewer releases, there is no consensus. The types of transection are shown in Fig. 4. In addition, the traditional median transection is sometimes replaced by 2 paramedian osteotomies, which extend from the posterior palate to just posterior of the incisive canal (shown by the green line in Fig. 4). In our survey (Fig. 2) the dominant practice is to do more surgical releases not fewer; 70% (n = 52/74) transect all 4 areas of resistance, and 7 (9%) do not do a median release. Latency period Ilizarov recommends a latency period of 5 days for long bones to allow the first callus to form without consolidation.15 As far as SARME is concerned, most authors agree that a latency period is required, but it varies between 2 days and 2–3 weeks,4,5,11,14 and often is not mentioned at all.9,16–18 It is interesting to note that in our survey (Fig. 3) one quarter of respondents leave almost no latency period (zero or one day only), and roughly half wait between 5 and 7 days.
Over-correction The relative shortage of long-term follow-up studies with large enough numbers makes it difficult to find out the incidence of relapse. Long-term studies show average relapse rates of between 10% and 24% after follow-up of several years.11,19 Relapse is often mentioned but not quantified. Interestingly, several studies have shown comparable relapse between non-surgical (adolescent) rapid maxillary expansion groups and adult SARME groups after follow-up of several years.20,21 In our study roughly one quarter (n = 17/74) of respondents over-corrected the discrepancy, most commonly by 2 mm or 20%.
Conclusion Surgeons use several techniques for SARME and there are many variations. There are many different combinations of protocol and no. 2 studies are the same. This lack of cohesion may foster an approach based more on personal experience and biological theory than evidence, and more studies with long-term outcomes are needed to redress this. One particular area of interest is the latency period. In our survey, 25% of surgeons do not observe any latency period and it is likely that experience has shown that this achieves acceptable outcomes. We hope that the results of our survey will be of some interest to surgeons and orthodontists.
Expansion rate Reported rates vary from 0.25 mm12,17,18 to 1 mm/day6,9 and anywhere in between.4,16 If it is too fast one risks separation and non-union of the various bony bridgeheads. If it is too slow callus may consolidate and prevent further expansion. In our survey 69% (n = 51/74) of respondents expand at 1 mm/day, 27% (n = 20/74) at 0.5 mm/day, and 4% (n = 3/74) at 0.25 mm/day. Activation of long bones is generally recommended at 1 mm/day.15
Conflict of interest statement No conflict of interest.
Appendix 1. Questions on survey
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J.K. MacLaine et al. / British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
1) How many years have you been a consultant? 2) How many SARME operations would you undertake in a year? 3) Do you normally use a tooth-borne or bone-borne expander? 4) Please indicate which maxillary releases you routinely perform: Anterior (piriform aperture). Lateral (zygomatic buttress). Posterior (pterygoid junction). Median (mid-palatal suture). Other e.g. Paramedian (please specify). 5) Do you have a latency period before starting expansion, and if so, of what length? 6) What is your preferred rate of expansion (mm/day)? 7) Do you over-expand, and if so, by how much? 8) Any comments?
References 1. Brown GV. The surgery of oral and facial diseases and malformation. 4th ed. London: Kimpton; 1938. p. 507. 2. Heiss J. Ueber die chirugische Untersteutzung der Dehnung im komprimierten Oberkiefer. Deutsch Zahnaeszteblatt 1954;8:560. 3. Isaacson RJ, Wood JL, Ingram AH. Forces produced by rapid maxillary expansion. Part I. Design of the force measuring system. Angle Orthod 1964;34:256–60. 4. Mommaerts MY. Transpalatal distraction as a method of maxillary expansion. Br J Oral Maxillofac Surg 1999;37:268–72. 5. Koudstaal MJ, van der Wal KG, Wolvius EB, Schulten AJ. The Rotterdam Palatal Distractor: introduction of the new bone-borne device and report of the pilot study. Int J Oral Maxillofac Surg 2006;35:31–5. 6. Koudstaal MJ, Wolvius EB, Schulten AJ, Hop WC, van der Wal KG. Stability, tipping and relapse of bone borne versus tooth-borne surgically assisted rapid maxillary expansion: a prospective randomised patient trial. Int J Oral Maxillofac Surg 2009;38:308–15.
7. Isaacson RJ, Ingram AH. Forces produced by rapid maxillary expansion. Part II. Forces present during treatment. Angle Orthod 1964;34: 261–70. 8. Kennedy III JW, Bell WH, Kimbrough OL, James WB. Osteotomy as an adjunct to rapid maxillary expansion. Am J Orthod 1976;70: 123–37. 9. Kraut RA. Surgically assisted rapid maxillary expansion by opening the midpalatal suture. J Oral Maxillofac Surg 1984;42:651–5. 10. Bell WH, Jacobs JD. Surgical-orthodontic correction of horizontal maxillary deficiency. J Oral Surg 1979;37:897–902. 11. Bays RA, Greco JM. Surgically assisted rapid palatal expansion: an outpatient technique with long-term stability. J Oral Maxillofac Surg 1992;50:110–5. 12. Pogrel MA, Kaban LB, Vargervik K, Baumrind S. Surgically assisted rapid maxillary expansion in adults. Int J Adult Orthodon Orthognath Surg 1992;7:37–41. 13. Messer EJ, Bollinger TE, Keller JJ. Surgical–mechanical maxillary expansion. Quintessence Int Dent Dig 1979;10:13–6. 14. Glassman AS, Nahigian SJ, Medway JM, Aronowitz HI. Conservative surgical orthodontic adult rapid palatal expansion: sixteen cases. Am J Orthod 1984;86:207–13. 15. Ilizarov GA. Clinical applications of the tension-stress effect for limb lengthening. Clin Orthop Relat Res 1990;250:8–26. 16. Anttila A, Finne K, Keski-Nisula K, Somppi M, Panula K, Peltomäki T. Feasibility and long-term stability of surgically assisted rapid maxillary expansion with lateral osteotomy. Eur J Orthod 2004;26:391–5. 17. Schimming R, Feller KU, Herzmann K, Eckelt U. Surgical and orthodontic rapid palatal expansion in adults using Glassman’s technique: retrospective study. Br J Oral Maxillofac Surg 2000;38:66–9. 18. Mossaz CF, Byloff FK, Richter M. Unilateral and bilateral corticotomies for correction of maxillary transverse discrepancies. Eur J Orthod 1992;14:110–6. 19. Chamberland S, Proffit WR. Short-term and long-term stability of surgically assisted rapid palatal expansion revisited. Am J Orthod Dentofacial Orthop 2011;139:815–22. 20. Berger JL, Pangrazio-Kulbersh V, Borgula T, Kaczynski R. Stability of orthopedic and surgically assisted rapid palatal expansion over time. Am J Orthod Dentofacial Orthop 1998;114:638–45. 21. Kurt G, Altuq-Atac¸ AJ, Atac¸ MS, Karasud HA. Stability of surgically assisted rapid maxillary expansion and orthopedic maxillary expansion after 3 years’ follow-up. Angle Orthod 2010;80:425–31.
British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
Nationwide survey of surgically assisted rapid maxillary expansion James K. MacLaine ∗ , Ellie M. Thickett, Susan M. Power Orthodontic Department, Royal Bournemouth Hospital, Castle Lane East, Bournemouth, Dorset BH7 7DW, United Kingdom Accepted 10 July 2013 Available online 17 August 2013
Abstract We aimed to gather data on the current practice of surgically assisted rapid maxillary expansion (SARME) in the UK. Surveys were posted in the mail to all members of the British Association of Oral and Maxillofacial Surgeons (n = 379) and 166 (44%) responded. In the previous year 69 responders (42%) had done at least one SARME operation. The technique used by individual surgeons may be more experience-based than evidence-based, which leads to considerable variation. © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Surgically assisted rapid maxillary expansion; Surgically assisted rapid palatal expansion
Introduction Surgically assisted rapid maxillary expansion (SARME) is a technique that uses the concept of distraction osteogenesis to increase the transverse dimension of the maxilla in skeletally mature patients. It is indicated when the dental compensation provided solely by orthodontics is deemed insufficient to correct the discrepancy. The technique relies on strategic surgical releases followed by postoperative activation of an expander device. The basic principle has been known since the early twentieth century and Brown is credited with the first textbook description in 1938.1 In 1954 Heiss2 specified the midline splitting of the maxilla for orthodontic reasons. Historically there was an emphasis on the midpalatine suture as it was thought to be the logical point of resistance that had to be overcome when expanding. However, there is now a consensus that all the maxillofacial complex abutments are important, and together they are more important than the ∗
Corresponding author. Tel.: +44 02820732002. E-mail addresses: [email protected] (J.K. MacLaine), [email protected] (E.M. Thickett), [email protected] (S.M. Power).
midpalatine suture. This view (first suggested by Isaacson et al. in the 1960s3 ) did not achieve widespread acceptance until surgical experience led opinion in that direction in the 1970s and beyond. Unlike the distraction technique for long bones there is no consensus on a standard protocol for SARME. The main variables in technique that have been reported are the type of expander device, the number and distribution of surgical releases, the postoperative latency period, the rate of expansion, and over-correction. To obtain nationwide data on SARME techniques we did a mail-based survey of all members of the British Association of Oral and Maxillofacial Surgeons (BAOMS). We present our results and give an overview of some of the issues involved.
Method We sent a questionnaire to all members of the BAOMS. The Honourable Secretary of the association kindly agreed to provide the names and work addresses of all 379 members. To maximise the response rate, the survey was kept short and
0266-4356/$ – see front matter © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2013.07.002
842
J.K. MacLaine et al. / British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
Fig. 3. Latency period and number of surgeons. Fig. 1. Number of SARME operations in the previous year.
Discussion SARME workload
Fig. 2. Number and type of surgical transections (A = anterior, L = lateral, P = posterior, M = median).
The number of operations done by individual surgeons varied widely (Fig. 1). A small number of surgeons undertake a large number of SARME procedures, but 97 (58%) did none in the past year. There are undoubtedly many reasons for this but it is beyond the remit of this paper to speculate. Tooth-borne compared with bone-borne expanders
succinct, with one-word or tick box answers. The questions asked are shown in Appendix 1. A covering letter accompanied each questionnaire.
Results As a total of 166 questionnaires were returned (response rate of 44%), the survey was considered to be adequately representative. There were no correlations between the experience of the surgeon and any of the variables of the technique. The workload for SARME varies considerably and the number of operations done by individual surgeons is summarised in Fig. 1. There were no correlations between workload and variables of the technique. Regarding the type of expander, most respondents use a tooth-borne expander exclusively (n = 58/74, 78%), while 8/74 (11%) favour the bone-borne version. The remaining 8/74 (11%) use both. The number and type of surgical transections vary considerably (Fig. 2). Almost 70% (n = 52/74) of respondents do anterior, lateral, posterior, and median releases while 26% (n = 19/74) do not release posteriorly (the pterygoid junction). Of the 91% (n = 67/74) that do a median transection, 8 (12%) prefer paramedian releases to the traditional midline split. The latency period (time between the operation and first activation of the expansion device) varies between 0 and 7 days (Fig. 3). The rate of expansion is 1 mm/day for 69% (n = 51/74) of respondents, 0.5 mm/day for 27% (n = 20/74), and 0.25 mm/day for 4% (n = 3/74). Over-correction of the transverse discrepancy is favoured by 23% (n = 17/74) of surgeons, the most common amount being 2 mm or 20%.
The expander of choice in most SARME cases is a toothborne device (n = 58/74, 78%), which extends across the palate and connects the buccal maxillary teeth. The rapid distraction expansion force is transmitted beyond the dental apparatus to the weakened maxillary sutures, which allows for expansion. Bone-borne devices are connected directly to the maxillary apparatus, usually in the palatal vault. Examples are the Trans-Palatal Distractor (TPD) (DB Orthodontics Ltd., Silsden, UK),4 the Magdeburg Palatal Distractor (KLS Martin, Tuttlingen, Germany), and the Rotterdam Palatal Distractor (KLS Martin, Tuttlingen, Germany).5 The supposed advantages of bone-borne distractors are fewer, if any, dental side effects, a greater mechanical advantage from the distraction force being closer to the centre of the maxilla, and a more stable result. However, in a randomised controlled trial that compared the Rotterdam Palatal Distractor with a tooth-borne device, Koudstaal et al.6 showed no difference between the devices for the above-mentioned issues. The disadvantages are the considerably higher cost, the mechanical complexity, and sensitivity to technique, which for most clinicians would tip the balance in favour of the tooth-borne expander. In our survey 78% (n = 58/74) of surgeons use only a tooth-borne expander, 11% (n = 8/74) use only a bone-borne expander, and 11% (n = 8/74) use both. Surgical transections Isaacson et al.,3 and Isaacson and Ingram7 showed that the main site of resistance is not the midpalatine suture, but the remaining maxillary articulations: anterior, lateral, and posterior. The distraction technique primarily involves the release
J.K. MacLaine et al. / British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
843
Fig. 4. Three-quarter view of the skull and palatal view showing the types of transection (anterior and lateral transections: purple line; posterior transection: blue line; median transection: pink line; paramedian transection: green line).
of them and of the midpalatine (median) suture. Anatomically, they are the piriform aperture (anterior), the zygomatic buttress (lateral), the pterygoid junction (posterior), and the midpalatine suture (median). Early techniques described the transection of all of them,8–10 but with the emphasis on reduced surgical morbidity it has been suggested that fewer supports are osteotomised: anterior, lateral, and median11 ; lateral and median12 ; anterior, posterior, and lateral13 ; and anterior and lateral.14 Although there is a trend towards fewer releases, there is no consensus. The types of transection are shown in Fig. 4. In addition, the traditional median transection is sometimes replaced by 2 paramedian osteotomies, which extend from the posterior palate to just posterior of the incisive canal (shown by the green line in Fig. 4). In our survey (Fig. 2) the dominant practice is to do more surgical releases not fewer; 70% (n = 52/74) transect all 4 areas of resistance, and 7 (9%) do not do a median release. Latency period Ilizarov recommends a latency period of 5 days for long bones to allow the first callus to form without consolidation.15 As far as SARME is concerned, most authors agree that a latency period is required, but it varies between 2 days and 2–3 weeks,4,5,11,14 and often is not mentioned at all.9,16–18 It is interesting to note that in our survey (Fig. 3) one quarter of respondents leave almost no latency period (zero or one day only), and roughly half wait between 5 and 7 days.
Over-correction The relative shortage of long-term follow-up studies with large enough numbers makes it difficult to find out the incidence of relapse. Long-term studies show average relapse rates of between 10% and 24% after follow-up of several years.11,19 Relapse is often mentioned but not quantified. Interestingly, several studies have shown comparable relapse between non-surgical (adolescent) rapid maxillary expansion groups and adult SARME groups after follow-up of several years.20,21 In our study roughly one quarter (n = 17/74) of respondents over-corrected the discrepancy, most commonly by 2 mm or 20%.
Conclusion Surgeons use several techniques for SARME and there are many variations. There are many different combinations of protocol and no. 2 studies are the same. This lack of cohesion may foster an approach based more on personal experience and biological theory than evidence, and more studies with long-term outcomes are needed to redress this. One particular area of interest is the latency period. In our survey, 25% of surgeons do not observe any latency period and it is likely that experience has shown that this achieves acceptable outcomes. We hope that the results of our survey will be of some interest to surgeons and orthodontists.
Expansion rate Reported rates vary from 0.25 mm12,17,18 to 1 mm/day6,9 and anywhere in between.4,16 If it is too fast one risks separation and non-union of the various bony bridgeheads. If it is too slow callus may consolidate and prevent further expansion. In our survey 69% (n = 51/74) of respondents expand at 1 mm/day, 27% (n = 20/74) at 0.5 mm/day, and 4% (n = 3/74) at 0.25 mm/day. Activation of long bones is generally recommended at 1 mm/day.15
Conflict of interest statement No conflict of interest.
Appendix 1. Questions on survey
844
J.K. MacLaine et al. / British Journal of Oral and Maxillofacial Surgery 51 (2013) 841–844
1) How many years have you been a consultant? 2) How many SARME operations would you undertake in a year? 3) Do you normally use a tooth-borne or bone-borne expander? 4) Please indicate which maxillary releases you routinely perform: Anterior (piriform aperture). Lateral (zygomatic buttress). Posterior (pterygoid junction). Median (mid-palatal suture). Other e.g. Paramedian (please specify). 5) Do you have a latency period before starting expansion, and if so, of what length? 6) What is your preferred rate of expansion (mm/day)? 7) Do you over-expand, and if so, by how much? 8) Any comments?
References 1. Brown GV. The surgery of oral and facial diseases and malformation. 4th ed. London: Kimpton; 1938. p. 507. 2. Heiss J. Ueber die chirugische Untersteutzung der Dehnung im komprimierten Oberkiefer. Deutsch Zahnaeszteblatt 1954;8:560. 3. Isaacson RJ, Wood JL, Ingram AH. Forces produced by rapid maxillary expansion. Part I. Design of the force measuring system. Angle Orthod 1964;34:256–60. 4. Mommaerts MY. Transpalatal distraction as a method of maxillary expansion. Br J Oral Maxillofac Surg 1999;37:268–72. 5. Koudstaal MJ, van der Wal KG, Wolvius EB, Schulten AJ. The Rotterdam Palatal Distractor: introduction of the new bone-borne device and report of the pilot study. Int J Oral Maxillofac Surg 2006;35:31–5. 6. Koudstaal MJ, Wolvius EB, Schulten AJ, Hop WC, van der Wal KG. Stability, tipping and relapse of bone borne versus tooth-borne surgically assisted rapid maxillary expansion: a prospective randomised patient trial. Int J Oral Maxillofac Surg 2009;38:308–15.
7. Isaacson RJ, Ingram AH. Forces produced by rapid maxillary expansion. Part II. Forces present during treatment. Angle Orthod 1964;34: 261–70. 8. Kennedy III JW, Bell WH, Kimbrough OL, James WB. Osteotomy as an adjunct to rapid maxillary expansion. Am J Orthod 1976;70: 123–37. 9. Kraut RA. Surgically assisted rapid maxillary expansion by opening the midpalatal suture. J Oral Maxillofac Surg 1984;42:651–5. 10. Bell WH, Jacobs JD. Surgical-orthodontic correction of horizontal maxillary deficiency. J Oral Surg 1979;37:897–902. 11. Bays RA, Greco JM. Surgically assisted rapid palatal expansion: an outpatient technique with long-term stability. J Oral Maxillofac Surg 1992;50:110–5. 12. Pogrel MA, Kaban LB, Vargervik K, Baumrind S. Surgically assisted rapid maxillary expansion in adults. Int J Adult Orthodon Orthognath Surg 1992;7:37–41. 13. Messer EJ, Bollinger TE, Keller JJ. Surgical–mechanical maxillary expansion. Quintessence Int Dent Dig 1979;10:13–6. 14. Glassman AS, Nahigian SJ, Medway JM, Aronowitz HI. Conservative surgical orthodontic adult rapid palatal expansion: sixteen cases. Am J Orthod 1984;86:207–13. 15. Ilizarov GA. Clinical applications of the tension-stress effect for limb lengthening. Clin Orthop Relat Res 1990;250:8–26. 16. Anttila A, Finne K, Keski-Nisula K, Somppi M, Panula K, Peltomäki T. Feasibility and long-term stability of surgically assisted rapid maxillary expansion with lateral osteotomy. Eur J Orthod 2004;26:391–5. 17. Schimming R, Feller KU, Herzmann K, Eckelt U. Surgical and orthodontic rapid palatal expansion in adults using Glassman’s technique: retrospective study. Br J Oral Maxillofac Surg 2000;38:66–9. 18. Mossaz CF, Byloff FK, Richter M. Unilateral and bilateral corticotomies for correction of maxillary transverse discrepancies. Eur J Orthod 1992;14:110–6. 19. Chamberland S, Proffit WR. Short-term and long-term stability of surgically assisted rapid palatal expansion revisited. Am J Orthod Dentofacial Orthop 2011;139:815–22. 20. Berger JL, Pangrazio-Kulbersh V, Borgula T, Kaczynski R. Stability of orthopedic and surgically assisted rapid palatal expansion over time. Am J Orthod Dentofacial Orthop 1998;114:638–45. 21. Kurt G, Altuq-Atac¸ AJ, Atac¸ MS, Karasud HA. Stability of surgically assisted rapid maxillary expansion and orthopedic maxillary expansion after 3 years’ follow-up. Angle Orthod 2010;80:425–31.