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Use of mini-implants in orthognathic surgery
British Journal of Oral and Maxillofacial Surgery 45 (2007) 406–407
Short communication
Use of mini-implants in orthognathic surgery A.J. Gibbons ∗ , R.R.J. Cousley Oral and Maxillofacial and Orthodontic Units, Peterborough District Hospital, Thorpe Road, Peterborough PE3 6DA, UK Accepted 21 March 2006 Available online 5 May 2006
Abstract We report a case in which mini-implants were used for intraoperative maxillomandibular fixation and for postoperative elastic traction in the treatment of a 20-year-old woman with mandibular prognathism. © 2006 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Dental implants; Orthognathic surgery
Introduction The use of self-drilling inter-maxillary fixation (IMF) screws in the management of maxillofacial trauma is well established.1–3 They are easy and quick to use and reduce the operating time to achieve maxillomandibular fixation. They reduce the risk of needle stick-type injuries associated with using wires, and are relatively inexpensive. Conventional IMF is achieved using stainless steel wires and orthodontic fixed appliance hooks.4,5 Recently, specially modified bone screws have become available for orthodontic anchorage.6–10 These mini-implants are inserted monocortically and have enough stability to resist orthodontic traction. We report a case of a mandibular bilateral sagittal split setback osteotomy in which mini-implants were used for both temporary IMF and postoperative occlusal adjustments.
Case report A 20-year-old woman presented with a Class III malocclusion as a result of mandibular prognathism. She had previously had orthodontic camouflage and required presurgical decompensation of the lower incisors. The use of an upper ∗
Corresponding author. Tel.: +44 1733 874126; fax: +44 1733 875697. E-mail address: [email protected] (A.J. Gibbons).
fixed orthodontic appliance was contraindicated by the severe shortness of the roots of her upper incisors. She therefore had 7 months of preoperative orthodontics to align and procline her lower teeth for a mandibular set-back procedure. To assist intraoperative intermaxillary fixation (IMF), the combined orthodontic and surgical team decided to use mini-implants in the maxilla. The positions of the implants were planned using a maxillary working model and preoperative radiographs. Five sites for mini-implants, evenly distributed around the maxilla, were selected. The positions of the roots of the teeth were clearly identified, so that contact could be avoided. At operation, five self-drilling Aarhus vanadium alloy mini-implants (Medicon Instrumente, www.aarhus-miniimplant.com) were inserted transmucosally into the maxilla at the level of the attached and non-attached gingivae. These screws were 1.5–2.0 mm in diameter and their intraosseous lengths ranged from 5.4 to 8.7 mm. The mini-implants were inserted unicortically with a cruciform blade screwdriver. Bilateral sagittal split osteotomies were then made. The mandible was located into a Class I occlusion using an occlusal wafer and powerchain IMF applied between the maxillary mini-implants and the mandibular fixed appliance hooks (Fig. 1). After plating had been completed the IMF was released, the occlusion checked, and the wafer removed. At early postoperative review it was noted that the patient’s mandible and lower centre line were displaced by 2 mm to the right. The incisor relation was also tenuous. Light intermax-
0266-4356/$ – see front matter © 2006 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.bjoms.2006.03.012
A.J. Gibbons, R.R.J. Cousley / British Journal of Oral and Maxillofacial Surgery 45 (2007) 406–407
407
(Fig. 3) and reported minimal discomfort from the miniimplants and traction.
Discussion
Fig. 1. Orthodontic mini-implants that support intraoperative intermaxillary fixation.
Aarhus orthodontic mini-implants have all the advantages of self-drilling IMF screws. They allow operators to feel if they contact the roots of teeth before they can cause damage. The screws can then be placed at different sites.1 However, because mini-implants are smaller than IMF screws they are less likely to damage teeth on insertion. The size of these fixtures also means that they are more comfortable for patients than the bulky IMF screws. As no heat is generated during placement of mini-implants, loosening as a result of heat necrosis of bone does not occur. Mini-implants engage only the outer cortical plate and cancellous bone, but not the inner cortical plate. Our report shows that this can still give the screws adequate stability for IMF. They can also be used for postoperative orthodontic traction, provided that relatively light forces are used.
Acknowledgement Fig. 2. Immediate postoperative (left Class III and transverse) intermaxillary elastic traction.
We thank Mr. J.M. Robertson for his contribution to the management of this patient.
References
Fig. 3. Completed case with coinciding dental and facial centre lines.
illary elastic traction was placed between the mini-implants and the mandibular orthodontic hooks to correct this (Fig. 2). Within 2 months the occlusion had settled exactly into the planned Class I position, and the traction was stopped. The lower fixed appliance was debonded and the maxillary miniimplants removed without local anaesthetic. The patient was pleased with her postoperative occlusion and appearance
1. Gibbons AJ, Hodder SC. A self-drilling intermaxillary fixation screw. Br J Oral Maxillofac Surg 2003;41:48–9. 2. Gibbons AJ, Baden J, Dhariwal DK, Monaghan AM, Hodder SC. A drill-free bone screw for intermaxillary fixation in military casualties. JR Army Med Corps 2003;149:30–2. 3. Gibbons AJ, Evans MJ, Abdullakutty A, Grew NR. Arch bar support using self-drilling intermaxillary fixation screws. Br J Oral Maxillofac Surg 2005;43:364. 4. Bocca AP, Kittur MA, Gibbons AJ, Sugar AW. A new type of occlusal wafer for orthognathic surgery. Br J Oral Maxillofac Surg 2002;40:151–2. 5. Smith A. The use of orthodontic chain elastic for temporary intermaxillary fixation. Br J Oral Maxillofac Surg 1993;31:250–1. 6. Kanomi R. Mini-implant for orthodontic anchorage. J Clin Orthod 1997;31:763–7. 7. Costa A, Raffaini M, Melsen B. Miniscrews as orthodontic anchorage: a preliminary report. Int J Adult Orthod Orthognath Surg 1998;13:201–9. 8. Melsen B, Costa A. Immediate loading of implants used for orthodontic anchorage. Clin Orthod Res 2000;3:23–8. 9. Kyung HM, Park HS, Bae SM, Sung JH, Kim IB. Development of orthodontic micro-implants for intraoral anchorage. J Clin Orthod 2003;37:321–8. 10. Lin JCY, Liou EJW. A new bone screw for orthodontic anchorage. Clin Orthod 2003;37:676–81.
Short communication
Use of mini-implants in orthognathic surgery A.J. Gibbons ∗ , R.R.J. Cousley Oral and Maxillofacial and Orthodontic Units, Peterborough District Hospital, Thorpe Road, Peterborough PE3 6DA, UK Accepted 21 March 2006 Available online 5 May 2006
Abstract We report a case in which mini-implants were used for intraoperative maxillomandibular fixation and for postoperative elastic traction in the treatment of a 20-year-old woman with mandibular prognathism. © 2006 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Dental implants; Orthognathic surgery
Introduction The use of self-drilling inter-maxillary fixation (IMF) screws in the management of maxillofacial trauma is well established.1–3 They are easy and quick to use and reduce the operating time to achieve maxillomandibular fixation. They reduce the risk of needle stick-type injuries associated with using wires, and are relatively inexpensive. Conventional IMF is achieved using stainless steel wires and orthodontic fixed appliance hooks.4,5 Recently, specially modified bone screws have become available for orthodontic anchorage.6–10 These mini-implants are inserted monocortically and have enough stability to resist orthodontic traction. We report a case of a mandibular bilateral sagittal split setback osteotomy in which mini-implants were used for both temporary IMF and postoperative occlusal adjustments.
Case report A 20-year-old woman presented with a Class III malocclusion as a result of mandibular prognathism. She had previously had orthodontic camouflage and required presurgical decompensation of the lower incisors. The use of an upper ∗
Corresponding author. Tel.: +44 1733 874126; fax: +44 1733 875697. E-mail address: [email protected] (A.J. Gibbons).
fixed orthodontic appliance was contraindicated by the severe shortness of the roots of her upper incisors. She therefore had 7 months of preoperative orthodontics to align and procline her lower teeth for a mandibular set-back procedure. To assist intraoperative intermaxillary fixation (IMF), the combined orthodontic and surgical team decided to use mini-implants in the maxilla. The positions of the implants were planned using a maxillary working model and preoperative radiographs. Five sites for mini-implants, evenly distributed around the maxilla, were selected. The positions of the roots of the teeth were clearly identified, so that contact could be avoided. At operation, five self-drilling Aarhus vanadium alloy mini-implants (Medicon Instrumente, www.aarhus-miniimplant.com) were inserted transmucosally into the maxilla at the level of the attached and non-attached gingivae. These screws were 1.5–2.0 mm in diameter and their intraosseous lengths ranged from 5.4 to 8.7 mm. The mini-implants were inserted unicortically with a cruciform blade screwdriver. Bilateral sagittal split osteotomies were then made. The mandible was located into a Class I occlusion using an occlusal wafer and powerchain IMF applied between the maxillary mini-implants and the mandibular fixed appliance hooks (Fig. 1). After plating had been completed the IMF was released, the occlusion checked, and the wafer removed. At early postoperative review it was noted that the patient’s mandible and lower centre line were displaced by 2 mm to the right. The incisor relation was also tenuous. Light intermax-
0266-4356/$ – see front matter © 2006 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.bjoms.2006.03.012
A.J. Gibbons, R.R.J. Cousley / British Journal of Oral and Maxillofacial Surgery 45 (2007) 406–407
407
(Fig. 3) and reported minimal discomfort from the miniimplants and traction.
Discussion
Fig. 1. Orthodontic mini-implants that support intraoperative intermaxillary fixation.
Aarhus orthodontic mini-implants have all the advantages of self-drilling IMF screws. They allow operators to feel if they contact the roots of teeth before they can cause damage. The screws can then be placed at different sites.1 However, because mini-implants are smaller than IMF screws they are less likely to damage teeth on insertion. The size of these fixtures also means that they are more comfortable for patients than the bulky IMF screws. As no heat is generated during placement of mini-implants, loosening as a result of heat necrosis of bone does not occur. Mini-implants engage only the outer cortical plate and cancellous bone, but not the inner cortical plate. Our report shows that this can still give the screws adequate stability for IMF. They can also be used for postoperative orthodontic traction, provided that relatively light forces are used.
Acknowledgement Fig. 2. Immediate postoperative (left Class III and transverse) intermaxillary elastic traction.
We thank Mr. J.M. Robertson for his contribution to the management of this patient.
References
Fig. 3. Completed case with coinciding dental and facial centre lines.
illary elastic traction was placed between the mini-implants and the mandibular orthodontic hooks to correct this (Fig. 2). Within 2 months the occlusion had settled exactly into the planned Class I position, and the traction was stopped. The lower fixed appliance was debonded and the maxillary miniimplants removed without local anaesthetic. The patient was pleased with her postoperative occlusion and appearance
1. Gibbons AJ, Hodder SC. A self-drilling intermaxillary fixation screw. Br J Oral Maxillofac Surg 2003;41:48–9. 2. Gibbons AJ, Baden J, Dhariwal DK, Monaghan AM, Hodder SC. A drill-free bone screw for intermaxillary fixation in military casualties. JR Army Med Corps 2003;149:30–2. 3. Gibbons AJ, Evans MJ, Abdullakutty A, Grew NR. Arch bar support using self-drilling intermaxillary fixation screws. Br J Oral Maxillofac Surg 2005;43:364. 4. Bocca AP, Kittur MA, Gibbons AJ, Sugar AW. A new type of occlusal wafer for orthognathic surgery. Br J Oral Maxillofac Surg 2002;40:151–2. 5. Smith A. The use of orthodontic chain elastic for temporary intermaxillary fixation. Br J Oral Maxillofac Surg 1993;31:250–1. 6. Kanomi R. Mini-implant for orthodontic anchorage. J Clin Orthod 1997;31:763–7. 7. Costa A, Raffaini M, Melsen B. Miniscrews as orthodontic anchorage: a preliminary report. Int J Adult Orthod Orthognath Surg 1998;13:201–9. 8. Melsen B, Costa A. Immediate loading of implants used for orthodontic anchorage. Clin Orthod Res 2000;3:23–8. 9. Kyung HM, Park HS, Bae SM, Sung JH, Kim IB. Development of orthodontic micro-implants for intraoral anchorage. J Clin Orthod 2003;37:321–8. 10. Lin JCY, Liou EJW. A new bone screw for orthodontic anchorage. Clin Orthod 2003;37:676–81.