YIJOM-3037; No of Pages 3
Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx http://dx.doi.org/10.1016/j.ijom.2014.11.004, available online at http://www.sciencedirect.com
Technical Note Orthognathic Surgery
Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure
N. Nadjmi, S. Stevens, R. Van Erum Department of Cranio-Maxillofacial Surgery, GH MONICA Antwerp, University Hospital Antwerp (UA), Antwerp, Belgium
N. Nadjmi, S. Stevens, R. Van Erum: Mandibular midline distraction using a toothborne device and a minimally invasive surgical procedure. Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx. # 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Abstract. In this technical note we share our experience of mandibular midline distraction, a powerful tool in orthognathic surgery. The use of a tooth-borne distractor and a minimally invasive surgical procedure to perform the midline osteotomy is discussed.
In our population, retrognathism and transverse mandibular and maxillary deficiencies are not uncommon. Transverse skeletal hypoplasia is reflected in wide lateral vestibules, the so-called buccal corridors, severe anterior crowding, and tipping and impaction of the anterior teeth. Gunbay et al.1 stated that in orthodontic patients, an adequate sagittal and transverse mandibular dimension with an upright tooth position centrally in the bone, are important factors to obtain a stable occlusion without an increased risk of gingival recession. The surgical treatment of skeletal mandibular deficiency in the sagittal plane has been highly successful using conventional sagittal split procedures. In correcting transverse mandibular deficiencies, however, orthodontists have limited options. Since the mandibular symphysis fuses at the age of 1 year there is no skeletal 0901-5027/000001+03
widening. Therefore, orthodontic expansion of the mandibular arch is at high risk of relapse.2,3 The only alternatives for the orthodontist are tooth extractions and interproximal enamel reduction. Ilizarov described distraction osteogenesis in 1954, and ever since, this technique has gained increasing popularity. It was not until the 1990s that mandibular midline distraction was offered as a treatment option for correcting mandibular transverse hypoplasia.4,5 A novel, minimally invasive surgical approach to mandibular midline distraction in conjunction with the use of a toothborne distraction device is discussed. Technique Preoperative procedure
In order to avoid damage to the roots of the central incisors during the osteotomy, the
Key words: mandibular midline distraction; mandibular symphyseal distraction; trans-mandibular distraction; mandibular osteotomy.. Accepted for publication 5 November 2014
roots of these teeth are diverged using fixed appliances on the lower dentition. Very light wires (012–014) and an open coil spring are used. In the case of severe crowding, only the two central incisors, canines, and premolars are engaged with the wire. The orthodontist starts this preparative treatment approximately 3 months prior to surgery. At 2 weeks preoperatively, a custommade tooth-borne appliance (Hyrax-type distractor) is fabricated and cemented to the first premolars and first molars (MultiCure Glass Ionomer Band Cement, Unitek – 3M, Zwijndrecht, Belgium) (Fig. 1). When the orthodontist deems the patient to be ready for surgery, a cone beam computed tomography scan (CBCT) is done, allowing the surgeon to evaluate the anatomy of the jaw, the distance between the roots of the central incisors, and the presence and position of third molars,
# 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Nadjmi N, et al. Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.11.004
YIJOM-3037; No of Pages 3
2
Nadjmi et al. Discussion
Fig. 1. The custom-made tooth-borne distractor. Notice the anterior crowding and the open coil spring to diverge the central incisors.
which are usually removed during the same surgical procedure as the mandibular midline osteotomy.
Surgical intervention
For the comfort of the patient, the surgery is performed under general anaesthesia (nasotracheal intubation). The patient is placed in a supine position with the head placed in a horseshoe head rest, mounted on an operating table equipped with a trapezoidal extension plate, allowing the surgeon to sit close to the patient. Local anaesthetic is injected in the mental region (lidocaine 10 mg/ml + adrenaline 1/ 200,000). The facial skin is disinfected using 1% Hospital Antiseptic Concentrate and 70% ethanol. The patient is draped in a standard manner and the oral cavity is disinfected and rinsed (2% chlorhexidine digluconate solution). The surgeon is positioned behind the head of the patient and the lower lip mucosa is exposed by the assistants using a double skin hook and two retractors. A short vertical incision is made through the lower lip frenulum, inferior to the mucogingival junction (Fig. 2). A sharp incision is then made through the periosteum at the midline. A sub-periosteal dissection is then performed between the two mental muscles and a Freer retractor is placed over the
Fig. 3. The midline osteotomy is performed with an oscillating saw as high as possible interdentally.
symphysis at the mandibular midline, retracting the lower lip caudally. The mandibular midline osteotomy is performed with a 0.3-mm oscillating saw, starting at the mandibular border and continuing upward as high as possible interdentally (Fig. 3). The osteotomy is then finalized with a 4-mm chisel. The mobility of the mandibular halves is checked and the distractor is then activated by about 2 mm to make sure that there are no bony interferences. The distractor is then deactivated. The wound is closed in two layers: the periosteum and supra-periosteal tissues are sutured with a 4–0 resorbable monofilament suture and the mucosa is closed using a fine braided 6–0 absorbable suture (Fig. 4).
Postoperative procedure and distraction
Medication consisting of painkillers, an antiseptic mouthwash, and an antibiotic is prescribed for the first 5 postoperative days. The patient is discharged after 1 night in the hospital and is seen by the orthodontist 1 week after surgery to begin distraction. The distraction rate is 2 mm 0.25 mm per day.6 The distractor is then blocked by the application of composite cement to the distractor screw. Active orthodontic treatment is resumed after 8 weeks and the distractor is usually removed 5 months postoperatively.
In a systematic review, de Gijt et al.7 clearly described a higher incidence of irritation and gingivitis in bone-borne devices compared to dental-borne distractors. A possible downside to the use of a tooth-borne distractor might be the less proportionate vertical bony expansion. In theory, a proportionate widening with basal bone expansion could decrease longterm relapse.8 Overall, the results in the literature suggest a more proportionate vertical expansion created by bone-borne distractors.1,8,9 However, de Gijt et al.7 stated that most articles were of low statistical power and controversies remain. We have been using bone-borne devices since they were first introduced. Initially we used the trans-mandibular distractor of Mommaerts,10 and later on another boneborne symphyseal distractor. Due to significant patient discomfort and frequent device breakdown, bone-borne devices are no longer used in our centre. In the approach presented, the vertical incision through the lower lip frenulum leaves a short and inconspicuous scar in the midline. There is no need to transect the mental muscles in order to visualize the mandibular symphysis, as is the case in the placement of bone-borne devices. Further, in contrast to the bone-borne devices, the lingual positioned distraction device does not interfere with the normal lip-seal and proper function of the lower lip. These devices offer more comfort to the patient and are generally very well tolerated. A prospective study is currently being performed in our centre to evaluate the basal bone widening at the symphysis and its stability over time, possible periodontal changes, and the dental effects of the tooth-borne distractor, as well as the effects on the temporomandibular joint and patient satisfaction. In our observation, the combination of this minimally invasive approach and a tooth-borne device proved to be a highly effective and well-tolerated treatment modality in patients with severe transverse mandibular deficiency. Funding
No sources of funding. Competing interests
No competing interests.
Fig. 2. The vertical incision.
Fig. 4. Closing the mucosa with a fine braided 6–0 absorbable suture leaves an inconspicuous scar.
Ethical approval
Ethical approval was given by the Ethics Committee, AZ Monica, Antwerp Campus.
Please cite this article in press as: Nadjmi N, et al. Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.11.004
YIJOM-3037; No of Pages 3
Minimally invasive mandibular midline distraction Patient consent
Written informed consent was obtained from all patients. References 1. Gunbay T, Akay MC, Aras A, Gomel M. Effects of transmandibular symphyseal distraction on teeth, bone, and temporomandibular joint. J Oral Maxillofac Surg 2009;67:2254–65. 2. Little RM. Stability and relapse of mandibular anterior alignment: University of Washington studies. Semin Orthod 1999;5: 191–204. 3. Housley JA, Nanda RS, Currier GF, McCune DE. Stability of transverse expansion in the mandibular arch. Am J Orthod Dentofacial Orthop 2003;124:288–93. 4. Perrott DH, Berger R, Vargervik K, Kaban LB. Use of a skeletal distraction device to
5.
6.
7.
8.
widen the mandible: a case report. J Oral Maxillofac Surg 1993;51:435–9. Guerrero CA, Bell WH, Contasti GI, Rodriguez AM. Mandibular widening by intraoral distraction osteogenesis. Br J Oral Maxillofac Surg 1997;35:383–92. Natu SS, Ali I, Alam S, Giri KY, Agarwal A, Kulkarni VA. The biology of distraction osteogenesis for correction of mandibular and craniomaxillofacial defects: a review. Dent Res J (Isfahan) 2014;11:16–26. de Gijt JP, Vervoorn K, Wolvius EB, Van der Wal KG, Koudstaal MJ. Mandibular midline distraction: a systematic review. J Craniomaxillofac Surg 2012;40:248–60. Del Santo Jr M, Guerrero CA, Buschang PH, English JD, Samchukov ML, Bell WH. Long-term skeletal and dental effects of mandibular symphyseal distraction osteogenesis. Am J Orthod Dentofacial Orthop 2000;118:485–93.
3
9. Iseri H, Malkoc S. Long-term skeletal effects of mandibular symphyseal distraction osteogenesis. An implant study. Eur J Orthod 2005;27:512–7. 10. Mommaerts MY. Bone anchored intraoral device for transmandibular distraction. Br J Oral Maxillofac Surg 2001;39:8–12.
Address: Nasser Nadjmi Department of Cranio-Maxillofacial Surgery AZ Monica Campus Antwerpen Harmoniestraat 68 2018 Antwerp Belgium Tel: +32 3 240 2611; Fax: +32 3 238 0489 E-mails: [email protected], [email protected]
Please cite this article in press as: Nadjmi N, et al. Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.11.004
Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx http://dx.doi.org/10.1016/j.ijom.2014.11.004, available online at http://www.sciencedirect.com
Technical Note Orthognathic Surgery
Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure
N. Nadjmi, S. Stevens, R. Van Erum Department of Cranio-Maxillofacial Surgery, GH MONICA Antwerp, University Hospital Antwerp (UA), Antwerp, Belgium
N. Nadjmi, S. Stevens, R. Van Erum: Mandibular midline distraction using a toothborne device and a minimally invasive surgical procedure. Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx. # 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Abstract. In this technical note we share our experience of mandibular midline distraction, a powerful tool in orthognathic surgery. The use of a tooth-borne distractor and a minimally invasive surgical procedure to perform the midline osteotomy is discussed.
In our population, retrognathism and transverse mandibular and maxillary deficiencies are not uncommon. Transverse skeletal hypoplasia is reflected in wide lateral vestibules, the so-called buccal corridors, severe anterior crowding, and tipping and impaction of the anterior teeth. Gunbay et al.1 stated that in orthodontic patients, an adequate sagittal and transverse mandibular dimension with an upright tooth position centrally in the bone, are important factors to obtain a stable occlusion without an increased risk of gingival recession. The surgical treatment of skeletal mandibular deficiency in the sagittal plane has been highly successful using conventional sagittal split procedures. In correcting transverse mandibular deficiencies, however, orthodontists have limited options. Since the mandibular symphysis fuses at the age of 1 year there is no skeletal 0901-5027/000001+03
widening. Therefore, orthodontic expansion of the mandibular arch is at high risk of relapse.2,3 The only alternatives for the orthodontist are tooth extractions and interproximal enamel reduction. Ilizarov described distraction osteogenesis in 1954, and ever since, this technique has gained increasing popularity. It was not until the 1990s that mandibular midline distraction was offered as a treatment option for correcting mandibular transverse hypoplasia.4,5 A novel, minimally invasive surgical approach to mandibular midline distraction in conjunction with the use of a toothborne distraction device is discussed. Technique Preoperative procedure
In order to avoid damage to the roots of the central incisors during the osteotomy, the
Key words: mandibular midline distraction; mandibular symphyseal distraction; trans-mandibular distraction; mandibular osteotomy.. Accepted for publication 5 November 2014
roots of these teeth are diverged using fixed appliances on the lower dentition. Very light wires (012–014) and an open coil spring are used. In the case of severe crowding, only the two central incisors, canines, and premolars are engaged with the wire. The orthodontist starts this preparative treatment approximately 3 months prior to surgery. At 2 weeks preoperatively, a custommade tooth-borne appliance (Hyrax-type distractor) is fabricated and cemented to the first premolars and first molars (MultiCure Glass Ionomer Band Cement, Unitek – 3M, Zwijndrecht, Belgium) (Fig. 1). When the orthodontist deems the patient to be ready for surgery, a cone beam computed tomography scan (CBCT) is done, allowing the surgeon to evaluate the anatomy of the jaw, the distance between the roots of the central incisors, and the presence and position of third molars,
# 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Nadjmi N, et al. Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.11.004
YIJOM-3037; No of Pages 3
2
Nadjmi et al. Discussion
Fig. 1. The custom-made tooth-borne distractor. Notice the anterior crowding and the open coil spring to diverge the central incisors.
which are usually removed during the same surgical procedure as the mandibular midline osteotomy.
Surgical intervention
For the comfort of the patient, the surgery is performed under general anaesthesia (nasotracheal intubation). The patient is placed in a supine position with the head placed in a horseshoe head rest, mounted on an operating table equipped with a trapezoidal extension plate, allowing the surgeon to sit close to the patient. Local anaesthetic is injected in the mental region (lidocaine 10 mg/ml + adrenaline 1/ 200,000). The facial skin is disinfected using 1% Hospital Antiseptic Concentrate and 70% ethanol. The patient is draped in a standard manner and the oral cavity is disinfected and rinsed (2% chlorhexidine digluconate solution). The surgeon is positioned behind the head of the patient and the lower lip mucosa is exposed by the assistants using a double skin hook and two retractors. A short vertical incision is made through the lower lip frenulum, inferior to the mucogingival junction (Fig. 2). A sharp incision is then made through the periosteum at the midline. A sub-periosteal dissection is then performed between the two mental muscles and a Freer retractor is placed over the
Fig. 3. The midline osteotomy is performed with an oscillating saw as high as possible interdentally.
symphysis at the mandibular midline, retracting the lower lip caudally. The mandibular midline osteotomy is performed with a 0.3-mm oscillating saw, starting at the mandibular border and continuing upward as high as possible interdentally (Fig. 3). The osteotomy is then finalized with a 4-mm chisel. The mobility of the mandibular halves is checked and the distractor is then activated by about 2 mm to make sure that there are no bony interferences. The distractor is then deactivated. The wound is closed in two layers: the periosteum and supra-periosteal tissues are sutured with a 4–0 resorbable monofilament suture and the mucosa is closed using a fine braided 6–0 absorbable suture (Fig. 4).
Postoperative procedure and distraction
Medication consisting of painkillers, an antiseptic mouthwash, and an antibiotic is prescribed for the first 5 postoperative days. The patient is discharged after 1 night in the hospital and is seen by the orthodontist 1 week after surgery to begin distraction. The distraction rate is 2 mm 0.25 mm per day.6 The distractor is then blocked by the application of composite cement to the distractor screw. Active orthodontic treatment is resumed after 8 weeks and the distractor is usually removed 5 months postoperatively.
In a systematic review, de Gijt et al.7 clearly described a higher incidence of irritation and gingivitis in bone-borne devices compared to dental-borne distractors. A possible downside to the use of a tooth-borne distractor might be the less proportionate vertical bony expansion. In theory, a proportionate widening with basal bone expansion could decrease longterm relapse.8 Overall, the results in the literature suggest a more proportionate vertical expansion created by bone-borne distractors.1,8,9 However, de Gijt et al.7 stated that most articles were of low statistical power and controversies remain. We have been using bone-borne devices since they were first introduced. Initially we used the trans-mandibular distractor of Mommaerts,10 and later on another boneborne symphyseal distractor. Due to significant patient discomfort and frequent device breakdown, bone-borne devices are no longer used in our centre. In the approach presented, the vertical incision through the lower lip frenulum leaves a short and inconspicuous scar in the midline. There is no need to transect the mental muscles in order to visualize the mandibular symphysis, as is the case in the placement of bone-borne devices. Further, in contrast to the bone-borne devices, the lingual positioned distraction device does not interfere with the normal lip-seal and proper function of the lower lip. These devices offer more comfort to the patient and are generally very well tolerated. A prospective study is currently being performed in our centre to evaluate the basal bone widening at the symphysis and its stability over time, possible periodontal changes, and the dental effects of the tooth-borne distractor, as well as the effects on the temporomandibular joint and patient satisfaction. In our observation, the combination of this minimally invasive approach and a tooth-borne device proved to be a highly effective and well-tolerated treatment modality in patients with severe transverse mandibular deficiency. Funding
No sources of funding. Competing interests
No competing interests.
Fig. 2. The vertical incision.
Fig. 4. Closing the mucosa with a fine braided 6–0 absorbable suture leaves an inconspicuous scar.
Ethical approval
Ethical approval was given by the Ethics Committee, AZ Monica, Antwerp Campus.
Please cite this article in press as: Nadjmi N, et al. Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.11.004
YIJOM-3037; No of Pages 3
Minimally invasive mandibular midline distraction Patient consent
Written informed consent was obtained from all patients. References 1. Gunbay T, Akay MC, Aras A, Gomel M. Effects of transmandibular symphyseal distraction on teeth, bone, and temporomandibular joint. J Oral Maxillofac Surg 2009;67:2254–65. 2. Little RM. Stability and relapse of mandibular anterior alignment: University of Washington studies. Semin Orthod 1999;5: 191–204. 3. Housley JA, Nanda RS, Currier GF, McCune DE. Stability of transverse expansion in the mandibular arch. Am J Orthod Dentofacial Orthop 2003;124:288–93. 4. Perrott DH, Berger R, Vargervik K, Kaban LB. Use of a skeletal distraction device to
5.
6.
7.
8.
widen the mandible: a case report. J Oral Maxillofac Surg 1993;51:435–9. Guerrero CA, Bell WH, Contasti GI, Rodriguez AM. Mandibular widening by intraoral distraction osteogenesis. Br J Oral Maxillofac Surg 1997;35:383–92. Natu SS, Ali I, Alam S, Giri KY, Agarwal A, Kulkarni VA. The biology of distraction osteogenesis for correction of mandibular and craniomaxillofacial defects: a review. Dent Res J (Isfahan) 2014;11:16–26. de Gijt JP, Vervoorn K, Wolvius EB, Van der Wal KG, Koudstaal MJ. Mandibular midline distraction: a systematic review. J Craniomaxillofac Surg 2012;40:248–60. Del Santo Jr M, Guerrero CA, Buschang PH, English JD, Samchukov ML, Bell WH. Long-term skeletal and dental effects of mandibular symphyseal distraction osteogenesis. Am J Orthod Dentofacial Orthop 2000;118:485–93.
3
9. Iseri H, Malkoc S. Long-term skeletal effects of mandibular symphyseal distraction osteogenesis. An implant study. Eur J Orthod 2005;27:512–7. 10. Mommaerts MY. Bone anchored intraoral device for transmandibular distraction. Br J Oral Maxillofac Surg 2001;39:8–12.
Address: Nasser Nadjmi Department of Cranio-Maxillofacial Surgery AZ Monica Campus Antwerpen Harmoniestraat 68 2018 Antwerp Belgium Tel: +32 3 240 2611; Fax: +32 3 238 0489 E-mails: [email protected], [email protected]
Please cite this article in press as: Nadjmi N, et al. Mandibular midline distraction using a tooth-borne device and a minimally invasive surgical procedure, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.11.004
