1 SUBMITTED 17 NOV 22 1 REVISIONS REQ. 13 FEB & 4 APR 23; REVISIONS RECD. 6 MAR & 8 APR 23 2 ACCEPTED 11 APR 23 3 ONLINE-FIRST: MAY 2023 4 DOI: https://doi.org/10.18295/squmj.5.2023.025 5 6 Interim use of Hyrax Screw Assembly for Single-Step Closure of Small 7 Alveolar Cleft Prior to Anterior Maxillary Distraction Osteogenesis 8 A technical note 9 Sonal Mishra,1 *Harpreet Singh,2 Dhirendra Srivastava,1 Poonam Sharma2 10 11 Departments of 1Oral & Maxillofacial Surgery and 2Orthodontics & Dentofacial 12 Orthopedics, ESIC Dental College and Hospital, New Delhi, India 13 *Corresponding Author’s e-mail: drhpreet_mamc04@yahoo.co.in 14 15 Abstract 16 Anterior maxillary distraction osteogenesis (AMDO) is often used for correction of maxillary 17 retrognathia in select cleft lip and palate cases. Restoration of alveolar arch continuity is 18 desirable prior to initiation of AMDO in these cleft maxillary deformities. However, AMDO 19 is technically difficult in a patient with coexisting alveolar cleft where there is a discontinuity 20 of the defect that presents a challenge in terms of adequate vector control of movement of 21 anterior segment and potential risk of tipping of teeth which already have compromised 22 anchorage/bone support on the cleft side. Treatment process becomes further challenging 23 when ongoing management is compounded by failed previous alveolar cleft grafting 24 procedures along with the patient’s reluctance to undergo further grafting of alveolar clefts. 25 Herein, we report a technical note demonstrating a novel application of the modification of 26 the hyrax screw wherein an initially fully opened Hyrax screw was utilized as an interim 27 assembly for accomplishing single-step closure of small alveolar cleft prior to 28 commencement of anterior maxillary distraction osteogenesis. This technique may prove to 29 be feasible for patients presenting with alveolar cleft defects of smaller widths of up to 5 mm 30 and relatively well-aligned upper arches. 31 Keywords: Alveolar Cleft; AMDO; Hyrax Screw; Single-Step Closure. 32 33 2 Introduction 34 Maxillary hypoplasia and retrusion represent a significant component of Class III deformity 35 in most patients with cleft lip and palate. Inspite of being widely adopted technique for one-36 stage correction of maxillary retrusion in cleft patients,1 Le Fort I osteotomy technique is 37 associated with higher relapse rates and may lead to emergence of velopharyngeal 38 insufficiency and hypernasality of voice, especially with advancements greater than 10 39 mm.2,3 On the other hand, by virtue of offering sufficient time for overcoming the tension on 40 the palatal scar and for regeneration of the membranous bone along with coverage of 41 adequate soft tissue, distraction osteogenesis (DO) results in better skeletal stability when 42 compared to conventional Le Fort I orthognathic surgery.4,5 However, when extraoral or 43 intraoral distraction is performed at a Le Fort I level, the risk of velopharyngeal insufficiency 44 and speech impairment has been shown to be similar to the risk observed in conventional Le 45 Fort I advancement surgery.6 46 47 To overcome this potential disadvantage, tooth borne distraction of the anterior maxilla using 48 anterior maxillary distraction osteogenesis (AMDO) has proven to be a feasible and stable 49 modality,6 while also offering alveolar bone space for correction of tooth malalignment and 50 without hampering speech.1 Rao Janardhan et al7 reported successful utilization of tooth-51 borne distraction device for advancement of the anterior maxilla with no worsening of 52 speech. Promising results with the use of hyrax distractor (for anteroposterior maxillary 53 advancement) in terms of its efficacy, patient's satisfaction, and stability have also been 54 demonstrated in literature.8 However, AMDO is difficult in a patient with alveolar cleft 55 where there is a discontinuity of the defect that presents difficulty in terms of vector control 56 of movement of anterior segment and the probable risk of tipping of teeth which already have 57 compromised anchorage/bone support on the cleft side. The present manuscript describes the 58 novel application of the modification of the hyrax screw wherein a conventional Hyrax screw 59 after being fully opened was utilized as an interim assembly for accomplishing single-step 60 closure of small alveolar cleft of up to 5 mm prior to commencement of anterior maxillary 61 distraction osteogenesis. 62 63 Methods 64 Case Description 65 An 18-year-old female patient with an operated left cleft lip and palate presented seeking 66 treatment for correction of mid face retrusion. Case history was indicative of two previous 67 3 alveolar cleft grafting surgeries at ages of 11 years and 15 years, respectively, at another 68 institution. The cleft was present between maxillary right central incisor (11) and left canine 69 (23) and was 5 mm wide at the level of the cementoenamel junction/ cervical margin of the 70 adjoining teeth. Reverse overjet of 11 mm was noticed (Fig. 1a, b, c & d). The upper 71 dentition was relatively well-aligned. There was scarring at the sites of surgery in the palate, 72 alveolus and lip. 73 74 The patient as well as her parents declined for any further grafting of the alveolar cleft. In 75 order to correct the alveolar discontinuity prior to maxillary advancement, closure of this 76 small alveolar cleft as well as osteotomy cuts for AMDO were planned in a single step. The 77 treatment protocol was approved by the Institutional Ethical Committee and patient gave 78 informed consent and acceptance about the treatment protocol. 79 80 Description of technique 81 Following preparation of the models in die-stone, proposed vertical osteotomy cuts were 82 made on both sides between the premolar and molar on the cast. A 9 mm Hyrax expansion 83 screw (Leonne, Italy) (pitch = 1 mm) was fully opened, and its arms were adapted at the 84 labial aspect of the anterior teeth with its body positioned between 11 and 23. The appliance 85 was acrylized in self-cure polymerizing resin at the labial, occlusal, and lingual aspects, and 86 subsequently finished, polished and tried-in for passive fit (Fig 2a, b). 87 88 Intraoperatively, the osteotomy was performed as follows: Under general anesthesia with oral 89 endotracheal intubation, a maxillary vestibular incision was made from first molar to first 90 molar. A mucoperiosteal flap was reflected to expose the maxilla. A horizonal osteotomy cut 91 parallel to the occlusal plane was made on both sides 5mm above the level of the root apices 92 from the lateral nasal rim to the distraction site between the premolars and molars. Lateral 93 nasal osteotomies were performed whilst protecting the nasal mucosa. The nasal septum was 94 detached by using a guarded septal osteotome. Vertical osteotomy/interdental cuts were made 95 in the buccal cortex between the second premolar and first molar (Fig. 3a). The palatal 96 osteotomy was executed gently under tactile guidance with curved osteotome while taking 97 care not to damage the palatal mucoperiosteum. 98 99 After confirming the completion of osteotomy, the acrylized Hyrax assembly was seated 100 passively over the segment anterior to the osteotomy cuts, and the screw was closed with the 101 4 key till approximation was achieved by mesial movement and docking of two bony segments 102 towards the cleft between teeth 11 and 23 (Fig.3b). As the bony segments from both sides 103 closely approximated towards each other in an evenly controlled vector (without over-riding 104 of segments), the closure of the cleft was visualized. Bone chips produced during osteotomy 105 were placed in the region of the residual cleft site. A 1.5 mm titanium straight plate was 106 adapted on both bony segments across the cleft and fixed with monocortical screws ensuring 107 that the anterior maxilla remained as one single unit (Fig. 3c), in preparation for facilitating 108 AMDO for correction of cleft maxillary retrognathia. The interim Hyrax assembly was 109 removed following closure using a 3-0 Vicryl suture. Thereafter, a three-part tooth-borne 110 bonded Hyrax distractor assembly (with 90° orientation for anteroposterior movement) 111 oriented parallel to mid palatine plane was cemented. Gap created at the area of the two 112 vertical osteotomies was utilized for anterior maxillary distraction at a rate of 1 mm per day 113 as follows (Fig. 3d): After a latency period of 5 days, AMDO was initiated by turning the 114 screw of the distractor assembly by half a turn (0.5 mm) every 12 hours, resulting to a total of 115 one full turn every day i.e. 1mm/day. The screw was activated for 13 days, thereby 116 amounting to a total correction of 13 mm. After completion of distraction, the central portion 117 of the distractor assembly was sealed with composite resin and retained through a 118 consolidation period of 4 months to allow for the mineralization and corticalization of the 119 newly formed bone tissue prior to removal of distractor assembly. Postoperatively, the 120 recovery period was uneventful with no detection of any relapse and complications. 121 122 Favourable results of the technique showing postoperative approximation of the bone in the 123 cleft site and satisfactory improvement in esthetics along with good bone regeneration at the 124 area of distraction are demonstrated through Figure 4a-4c. Alveolar space with good, 125 regenerated bone quality and implants placed bilaterally in the distracted bone are evident by 126 IOPA radiographs (Fig. 4d). 127 128 Ethical approval to report this case was obtained from the Institutional Research Ethics 129 Committee. Written informed consent was obtained from the patient for her information and 130 images to be published in this article. 131 132 https://www.sciencedirect.com/topics/medicine-and-dentistry/informed-consent 5 Discussion 133 Premaxillary/ anterior maxillary and alveolar distraction osteogenesis (DO) have been widely 134 used for management of severe midfacial retrusion including anterior crossbite in cleft lip and 135 palate patients.9-11 136 137 Restoration of alveolar arch continuity is desirable prior to initiation of AMDO in cleft 138 maxillary deformities. Restoration of large alveolar cleft defects by alveolar distraction 139 osteogenesis utilizing intraoral tooth-borne distractor has been successfully reported in 140 literature.1,9 The tooth-borne trifocal distraction appliance involving the use of two Hyrax-141 screws has also been described for the controlled closure of a large alveolar cleft.12 In cases 142 of small alveolar clefts with enhanced chances of graft survival, bone grafting is an ideal 143 option for the closure of cleft defects in order to achieve arch continuity, stabilise the 144 maxillary segments, eliminate oronasal fistulae, optimise nasal morphology through nasal 145 alar cartilage support, and finalize implant placement.13 However, before commencement of 146 AMDO, waiting time of at least 3-6 months is recommended for stabilization of graft. 147 Challenge is usually encountered when some patients with history of previously failed 148 alveolar bone grafting surgeries refuse to undergo another grafting procedure. 149 150 The conventional application of the Hyrax screw for closure of large alveolar clefts 151 (activation of the appliance by opening the screw) has been widely documented in 152 literature.9,12 The majority of these applications involving Hyrax screw and fan-shaped screw 153 entail opening of the screws to facilitate approximation of the alveolar segments towards each 154 other.8,12,14 On the other hand, the current technical note describes the novel application of the 155 modification of the hyrax screw wherein a conventional Hyrax screw after being fully opened 156 was utilized as an interim assembly for accomplishing single-step closure of small alveolar 157 cleft of up to 5 mm prior to commencement of anterior maxillary distraction osteogenesis. 158 The present interim tooth-borne Hyrax screw assembly facilitated controlled mobilization, 159 docking and evenly close approximation of the bony segments (without over-riding of 160 segments) towards the defect. This assembly enabled more precise bony movements while 161 simultaneously maintaining bone to bone contact and stabilization of the osseous segments in 162 the intended position during fixation, thereby aiding in accomplishing the anatomic objective 163 in a single step. 164 165 6 Thus, based on the principle of patient-centred outcome and in accordance with patient’s 166 wishes, this technique involving the use of interim tooth-borne Hyrax screw assembly is 167 suitable for clinical application in patients who are potential candidates for AMDO and also 168 presenting with small alveolar interdental clefts (of up to 5 mm) that persist even after 169 previous alveolar bone grafting surgeries. The advantages of this technique are the possibility 170 of achieving arch continuity in the same operation by evenly controlled mesial movements of 171 the bony segments towards each other, thus obviating the need for additional alveolar bone 172 grafting surgery and preventing creation of any extraoral wound, making such therapy 173 feasible especially for patients with small alveolar cleft defects of up to 5 mm. Simplicity of 174 the design, ease of fabrication and exclusive tooth-borne usage minimizes the invasiveness of 175 the procedure. 176 177 Limitations in generalizing the innovation: This technique cannot not be employed in large 178 alveolar cleft defects wherein significant bone segment movements may be associated with 179 significant relapse. Compromised periodontal support and advanced interdental bone loss are 180 contraindications to the use of this approach. 181 182 Conclusion 183 In view of the promising results of this approach, this procedure may prove to be feasible for 184 patients presenting with alveolar cleft defects of smaller widths and relatively well-aligned 185 upper arches. Large sample size studies involving different populations with long-term 186 follow-up are necessary to validate the current approach for routine use. 187 188 Conflict of Interest 189 The authors declare no conflicts of interest. 190 191 Funding 192 No funding was received for this research. 193 194 Authors’ Contribution 195 SM, HS and DS were responsible for the study conception and design and treatment of the 196 patient. HS and SM contributed to the literature search and drafting the article. SM, HS, DS 197 and PS contributed to the final editing and critical revision of the article. All authors have 198 7 made substantive contribution to this manuscript, and all have reviewed the final paper prior 199 to its submission. 200 201 References 202 1. Terbish M, Choi HY, Park YC, Yi CK, Cha JY. Premaxillary Distraction Osteogenesis Using 203 an Intraoral Appliance for Unilateral Cleft Lip and Palate: Case Report. Cleft Palate Craniofac 204 J 2015;52:e95-e102. https://doi.org/10.1597/14-105. 205 2. Cheung LK, Chua HD. A meta-analysis of cleft maxillary osteotomy and distraction 206 osteogenesis. Int J Oral Maxillofac Surg 2006;35:14-24. 207 https://doi.org/10.1016/j.ijom.2005.06.008. 208 3. Janulewicz J, Costello BJ, Buckley MJ, Ford MD, Close J, Gassner R. The effects of Le Fort 209 I osteotomies on velopharyngeal and speech functions in cleft patients. J Oral Maxillofac Surg 210 2004;62:308-14. https://doi.org/10.1016/j.joms.2003.08.014. 211 4. Kim JH, Lee IH, Lee SM, Yang BE, Park IY. 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Cleft Palate Craniofac J. 2015;52:614-7. https://doi.org/10.1597/13-058. 244 245 246 Figure 1: Pretreatment extraoral and intraoral photographs showing a cleft palate on the left 247 side and alveolar cleft between 11 and 23: (a) Frontal photograph (b) Profile photograph (c) 248 Intraoral occlusal view (d) Axial view. 249 250 251 https://doi.org/10.1597/15-335 https://doi.org/10.1597/15-335 9 252 Figure 2: Marking of osteotomy cuts site and acrylized appliance with Hyrax screw in fully 253 opened position: (a) Palatal view of the appliance (b) Front view of the appliance 254 255 256 Figure 3: (a) Intraoperative photograph showing placement of osteotomy cuts, (b) 257 Intraoperative photograph showing appliance in seated position and closure of screw assembly 258 with key, (c) Approximation accomplished by mesial movement and docking of bony segments 259 towards the interdental alveolar cleft between teeth 11 and 23, (d) Occlusal radiograph taken 260 intraoperatively before commencement of AMDO 261 262 10 263 Figure 4: Treatment results: (a) favourable frontal esthetics after completion of AMDO, (b) 264 improved profile esthetics after completion of AMDO, (c) Immediate post-distraction occlusal 265 view after removal of distractor appliance, (d) IOPA x-rays showing good bone regeneration 266 and implants placed bilaterally in the distracted bone between second premolar and first molar 267