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Distraction osteogenesis /certified fixed orthodontic courses by Indian dental academy


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Distraction osteogenesis /certified fixed orthodontic courses by Indian dental academy

  1. 1. DISTRACTION OSTEOGENESIS INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2.   Traditional orthognathic surgery and craniofacial reconstruction – advancement of osteotomized bone segments. Limitations – inability of soft tissues to be acutely stretched, large skeletal movements Degenerative changes, relapse and compromised function  Alternative gradual bone distraction known as distraction osteogenisis.
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  7. 7. Fibrocartilagenous tissue of soft callus Osteoblasts form hard callus cappilaries calcifies cartilage (hard callus) 3-4 months Remodelling- normal medullary canal
  10. 10. Distraction osteogenisis is a biologic process of new bone formation between the surfaces of bone segments that are gradually separated by incremental traction
  11. 11. I. Osteotomy of bone site with minimal periosteal stripping. II. Latency period: 3,5, or 7 days, depending on the surgical site. III. Distraction rate : 1.0 mm per day (0.5-2.0mm) IV. Distraction rhythm: continuous force application is best, yet device activation bid is more practical and allows for better pt compliance. V. Consolidation: until a cortical outline can be seen radiographically across the distraction gap, usually 6 weeks
  13. 13. i. Blood supply-overlying muscles, mucosa ii. Vector of distraction iii. Rate of distraction iv. Osteotomy location v. Muscle pull vi. Fibrous matrix-moulding vii. Latency period- more for small segments viii. Consolidation period
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  15. 15.  SYNDROMIC:- bilateral 1) treacher collins syndrome 2) cerebrocostomandibular sydm 3) mobius syndrome 4) arthromyodysplasia unilateral 1) hemifacial microsomia  NONSYNDROMIC:- bilateral 1) bilateral microsomia 2) post ankylosis 3) post infection 4) tessier-7-cleft unilateral 1) post traumatic 2) facial hemiatropy
  16. 16.     GRADE I:- hypo affects only the gonial angle. GRADE 2A:- the angle and the ascending ramus are affected. GRADE 2B:- hypo is more severe and affects the angle and ascending ramus, the later having a flat, rudimentary condyle. GRADE 3:- complete absence of the ramus and condyle
  18. 18. SURGICAL TECHNIQUE:   A 3cmm incission in the lateral vestibule- subperiosteal discection to expose the gonial angle and ascending ramus. The corticotomy is planed to preserve the nerve, the intramedullary vascularity and the tooth buds. The corticotomy begins in the retromolar area by cutting the medial and lateral buttress, then extended through the lateral aspect of the mand angle, cutting the entire cortex sparing the cancellous bone.
  19. 19.   Along the inferior aspect, it is extended widely around the angle, so that only 6 to 8mm of inner cortical bone remains intact to protect the nerve and the artery. The simultaneous increase in the vertical ramus height with new bone formation at the mand angle alows clockwise mand rotation during DO and consolidation that closely mimics growh.
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  21. 21.   The position of the pin placement determine the distraction vector. GRADE I:- the bone cuts extends obliquely from the post edge of the hypoplastic gonial angle to the retromolar area. Then the pins are placed perpendicular to the cut to obtain an oblique dist vector that produces larger bone elongation at the angle and less in the retromolar area
  22. 22.  GRADE 2A:- the DO must remodel and elongate the angle the inferior portion of the ascending ramus. The cut is placed obliquely to the junction of the angle and the ramus, and the pins must be inserted in an intermediate position between a vertical and oblique distraction vector.  GRADE 2B:- the cut is placed horizontally at the base of the ascending ramus and the pins must follow a vertical dist vector in order to obtain more elongation of the hypoplastic ascending ramus.
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  24. 24.      Two bicortical screws(2 to 3.5mm dia) are percutaneously introduced 3 to 5 mm in front of and behind the cut. Care must be taken to position the pins paralell to each other to facilitate their fixation to the device. The device is made of two hollow plates with a central hole to allow fixation to the pins. A metal screw connects the two plates. The screw hole in one plate is threaded, but not in the other, so that as the screw is turned , the distance between the plates can either be increased or decreased.
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  27. 27.     Micrognathic pts:- present with bilateral hypoplasia that affects both the mand body and ascending ramus. Two corticotomies are done- one vertical in the mandibular body and the other horizontal in the ascending ramus. Three pins are used- a central pin at the mand angle between the two corticotomies, a second pin in the mand body and a third pin in the ascending ramus. One bidirectional device is used on each side, each device having two dist plates to allow independent elongation of each segment, with the central pin used as the fixed pivot for both devices. DANCING DISTRACTION
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  30. 30. DISTRACTION PROTOCOL a. Latency- 5 days b. Rate-app 1 mm/day c. Distraction period- 3-4 weeks d. Consolidation period- 6-8 weeks COMPLICATIONS I. Skin scars II. Inadequate distraction vector III. Prolonged consolidation period IV. Major malocclusion V. Device instability VI. Infection VII. Device failure VIII. Bone healing problem
  32. 32. PREDISTRACTION ORTHODONTICS  In absence of permanent teeth, orthodontic treatment is limited to arch coordination and rapid palatal expansion  Permanent teeth orthodontics involves maxillary expansion, leveling and aligning of dental arches, correcting dental compensation, and correcting dental midlines
  33. 33. SURGICAL TECHNIQUE:• A wedge shaped incission is made similar to bsso, so that the device is covered without placing mucosa under tension. • • The lateral surface of the mand is exposed subperiosteally from the emergence of the inferior alveolar nerve to the neck of the condyle. The anterior border of ramus is exposed to the base of the coronoid process using a v-shaped elevator, the posr border is exposed along the body and gonial angle to the neck of the condyle with a curved elevator.
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  35. 35.     The lateral osteotomy is done so that both cortices of the inferoposterior and anterosuperior borders are completely cut to facilitate a greenstick fracture. The intraoral distractor is then placed and the two post pins are inserted transbuccally into the pin fixation clamps. The minimal skin incission for screw placement is located ant to the distal camp, where cheek elasticity will allow placement of the two ant pins later in the same incission. The osteotomy is converted to a total osteotomy with an osteotome at the superior border.
  36. 36.    The anterior pins are then placed using the same transbuccal incission. The rods should be oriented in such a way so that they emerge through an incission in the submental area. The wound is closed covering the entire distractor and about ¾ of the shaft. DISTRACTION PROTOCOL 1. Latency- 4 days 2. Rate- twice a day at 1mm per day 3. Consolidation period- 3 to 4 weeks POST DISTRACTION ORTHODONTICS Decidious dentition- functional orthodontics Permanent dentition- occlusal corrections
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  39. 39. INDICATIONS 1. Young patients with unsuccessful functional appliance treatment. 2. Traditional orthognathic pts with severe deficiencies that increase relapse potential. PREDISTRACTION ORTHODONTICS includes correction of crowding/spacing, tip and torque correction, leveling of curve of spee, and arch alignment/ coordination.
  40. 40. SURGICAL TECHNIQUE  Procedure is almost similar to ramus distraction exepct for location of cuts.   Briefly subperiosteal exposure, incomplete osteotomy of the corpus, partial device fixation, osteotomy completion with separation forceps, and device fixation. It is important to leave space between device and bone to prevent the bone from impinging on the rod during activation. DEVICE ORIENTATION  The distractor must be placed to avoid or diminish the possibility of an anterior openbite. POSTDISTRACTION ORTHODONTICS  Intermaxillary elastics to close the anterior and lateral open bites
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  42. 42.  Ct images of the tmj prvide clearer images of bony detail, mr imaging allows visualization of the intraarticular soft tissues of the tmj. 1. Condylar morphology remained unchanged 2. Contours remained regular , with no post or lateral flattening 3. In some cases joint space altered, condyle minimally repositioned or laterally subluxated. 4. Moreover in some cases pretreatment of bilateral subluxation of the meniscus was corrected during distraction and the anatomic tmj relationships returned to normal.
  43. 43. DISTRACTION BONE GRAFTS As early as 4 years Min puberty Less invasive More invasive No external site morbidity Donor site morbidity Soft tissues also lengthened No soft tissue lengthining Less risk of relapse More risk of relapse Less failure of device More risk of failure of graft No –ve impact on tmj Negative impact on tmj observed Less neurosensory disturbances Neurosensory dist inevitable No limit for bone lengthining Limited lengthining possible
  44. 44. INDICATIONS  Transport distraction involves creating a transport disk in the bone stump, adjacent to a discontinuity defect or resection site. SURGICAL TECHNIQUE  An extraoral submandibular incission below the inferior mandibular border is performed.    Lateral border of the mandible is exposed using with minimal periosteal stripping on the buccal cortex and no periosteal stripping on the lingual side. A corticotomy is created through the lateral and inferior aspects of the mand approximately 15mm proximal to the distal end of the proximal bone stump. The alveolar ridge is cut using a fine chisel taking care to avoid perforating the gingival tissues.
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  46. 46.     A small bone plate can be placed to allow completion of distractor pin placement. The transport device is then applied using bicortical pin fixation. To avoid a significant scar, the pins are placed through individual stab incisions rather than through the submandibular incision. The device is then attached to the pins, verifying the vector and trajectory of the planned transport segment. Closure of the surgical site is done in layers.
  47. 47. DISTRACTION PROTOCOL 1. Latency period- adults- 5 days, children-3 to 5 days, in pts with compromised blood supply7 to 10 days. 2. Rate- 0.5 mm twice a day, in compromised pts 0.25mm twice a day 3. Consolidation period- 6 to 8 weeks
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  50. 50. CONCEPT    During the process of bone transport the leading edge of the transport disk becomes enveloped with a fibrocartilagenous cap. In mand corpus recon, this cap is removed to allow osseous continuity between transport disk and docking site. It cap is not removed, then a pseudoarticulation develops. This concept is used to create a neocondyle.
  51. 51. SURGICAL TECHNIQUE     Once the bony or osseous ankylosis is released, a transport , a transport disk is created by placing a reverse Losteotomy from the sigmoid notch to approximately 10mm above the mand angle. Then the device should be oriented in a vertical vector( parallel to the post border of the mand) to elongate the post ramus and increase post vertical height, when indicated. For pts with bony ankylosis , a gap arthroplasty is performed as usual and no muscle flap or intervening fascia is placed in the gap site. If the pt is at risk for heterotrophic bone formation, then the gap site may be packed with an autogenous fat graft. Care should be taken to shape the neofossa to an anatomic configuration.
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  53. 53. DISTRACTION PROTOCOL 1. Latency period-5 days 2. Rate- 0.5mm twice per day 3. Consolidation period- until a cortical outline is visible radiographically, pt symptoms such as increased pressure in the joint region felt. 4. Pt should undergo active physical therapy(mouth opening excercises), this allows for the functional remodeling of the transport segment to become a neocondyle.
  54. 54.    For bilateral cases, attention must be paid to the occlusion as an openbite may be present due to condylar resorption or created surgically as the ankylosis is released. Temporalis muscle stripping is done to counteract the strong muscle pull. Occlusion must be controlled with orthodontic appliances and intermaxillary elastics.
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  57. 57.  The lack of hard and soft tissues in the cleft deformities lends them to treatment by distraction osteogenisis. ALVEOLAR CLEFTS    Reconstruction of the alveolar clefts can be performed by creating an osteotomy in the posterior maxilla and horizontally advancing the segment anteriorly to close the clefted alveolus. The power of bone transport is that both bone and gingival tissues are generated. The arch can be alligned orthodontically after distraction.
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  59. 59.   If the premaxillary segment is missing, the local tissues can be used to create a neo alveolus. Simple distraction devices can be made by modifying existing orthodontic appliances.
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  61. 61.    A pt with velopharyngeal insuffiency can also be treated by transport distraction osteogenisis. After speech therapy, if valopharyngeal insuffiency persists and a pharyngeal flap is being contemplated, the pt may be alternatively treated by distracting the hard palate and its associated palatal soft tissue posteriorly. When adequete bone stock is present, a palatal osteotomy is created and the distractor is placed across and anterior to the bone cut.
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  64. 64. INDICATIONS  Moderate to severe dentoalveolar bimaxillary protrusion or anterior crowding with maximum anchorage requirement, severe classII division I malocclusions, and mild to moderate skeletal class III malocclusion.  The tech was primarily designed for adults who required short treatment times and maximum anchorage control. CONCEPT The rcr tech consists of surgically undermining the interseptal bone distal to the canine followed by rapid tooth movement into the previously extracted first premolar socket.
  65. 65. PRESURGICAL ORTHODONTICS  Canine distraction must be performed before ossification of the first premolar socket, so it should be completed prior to extraction.   The 1st molar band should include a triple tube on the buccal surface. The anchor units are the first molars and 2nd premolars bilaterally. SURGICAL TECHINIQUE  Immediately after the extraction of the 1st premolar, the interseptal bone distal to the canines is undermined and reduced in thickness.
  66. 66.     Because the 1st premolar socket depth is always less than that of the canine, the bone located distal to the canine root apex would resist tooth movement during distraction. Therefore the 1st premolar extraction socket must be extended to the same depth as canine socket. The interseptal bone is reduced to a thickness of 1 to 1.5mm. The final step is to undermine the margins of the interseptal bone distal to canine so that it can be broken during distraction. In order to do this, a bur is used to make two vertical grooves from from the inferior to the superior aspect of the socket on both the mesiobuccal and mesiolingual line angles of the extraction socket.
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  68. 68. DISTRACTION PROTOCOL      One pair of intraoral distraction devices is placed on the teeth. At the same time, a continuous ss archwire is placed from the 1st molar to the 1st molar. The device is used to deliver the force and the archwire is the base wire on which the canine is distracted distally. Activation of the canine retraction device is begun the day of insertion and continues until the canines have been distracted into the desired position. It is activated twice per day(0.35mm/turn), once in morning and once in night because max cell proliferation in the PDL occurs late in the evening and early in the morning. COMPLICATIONS:- root resorption, tooth tipping alveolar bone fracture.
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  72. 72. INDICATIONS 1. Unilateral cleft lip and palate 2. Bilateral cleft lip and palate 3. Unilateral cleft palate 4. Mandibular prognatism 5. Nasomaxillary dysplasia PRESURGICAL ORTHODONTICS  This include skeletal and dentoalveolar expansion of the maxilla, alignment of the permanent incisors in the cleft area in some pts or bonegrafting at 8 to 10years of age in other cases.
  73. 73.   The day before surgery a modified quad-helix appliance was placed in the palate. In order to maintain maxillary expansion during distraction, an extra transverse arch is fixed to both premolar bands, which have vestibular hooks attached for elastic wear. SURGICAL TECHNIQUE   Two 3-4cm long incissions are made in the maxillary vestibule, leaving 2cm of intact mucosa between the two incisions. Subperiosteal dissection is performed from the piriform fossae to the lateral maxillary buttress on each side to expose the anterior and lateral aspects of the maxilla to the level of the infraorbital nerve.
  74. 74.      Dissection on the nasal floor is limited to the lateral part only. The septal base and the cleft remain intact The osteotomy is performed above the roots of the canines and molar tooth buds as seen in the radiographs. Osteotomy of the anterior maxillary surface must maintain the integrity of the maxillar antral mucoperiosteum for vascularity. The osteotomy extends into the maxillary butress, but pterygomaxillary disjunction is not performed.
  75. 75. DISTRACTION PROTOCOL 1. Latency- 5 days 2. Distraction forces are initiated using the previously cemented intraoral appliance and a face mask supported by the forehead and chin. 3. Two elastics per side are attached from the vestibular hooks in the canine region to a bar on the face mask. 4. The initial force delivered by elastic is 900gm, which is applied by wearing facemask for 16-18hrs per day. 5. By applying distraction force, an advancement of 2-3mm is achieved per week, distraction period is complete in 3-4 weeks 6. Once the maxilla is advanced to a satisfactory classII molar relationship, the amount of force is decreased to one elastic per side(450gm) for another two months(consolidation period)
  76. 76. DISTRACTION VECTORS  Maxillary deficiency may be vertical, sagittal, or transverse.    We three different orientations of maxillary distraction vectors:- anterosuperior, anterior, and anteroinferior. Commonly used is anterior, in which the horizontal vector must be paralell to the desired occlusal plane in order to minimize the development of an anterior open bite. An anteroinferior vector can be used to decrease the vertical height of the maxilla. This is accomplished by altering the position of the bar on the facemask in order to change the direction of elastics.
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  79. 79. CASE STUDY: A 17 yr old male pt with complete unilateral cleft lip and palate and a classIII deformity.  He also had boderline velopharyngeal incompetence that developed after multiple surgeries. SURGICAL TECHNIQUE  The max advancement was performed in a standard foshion.   Under direct visualization, the max fracture was completed and followed by a transverse osteotomy through the palatine bones and partially through the suture joining the maxillary and palatine bones. The intraoral 12mm dist device was fixed to the palate in an AP direction with 4 screws.
  80. 80.   On the nasal side, the two posterior screws were fixed to a plate, which converted the two bone hemiplates into one segment. The third screw was placed in the plate superoinferiorly using a dental implant handpiece. DISTRACTION PROTOCOL  Imm after completing surgery, the pt developed severe velopharyngeal incompetence which was predicted.  After completing 12mm of distraction( themax amount allowed by the distraction rod), the pt still had incompetence.
  81. 81.   The distraction device was disengaged ant in the palate, closed, and retracted more post by screws without changing the position of the post arms. An additional 8 mm of dist was performed to achieve a total of 20mm of device activation.
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  84. 84. Case study :  A 28yr old female presented with short face syndrome charecterized by 10mm of vertical maxillary deficiency and a class I occlusion SURGICAL TECHNIQUE:  A maxillary vestibular incision made from the second bicuspid on one side to the second bicuspid on the other   Total exposure of maxillary anterior wall and the nasal floor was achieved by sub periosteal dissection A leefort I osteotomy was performed , followed by positioning of the intermaxillary splint.
  85. 85.    two vertical distractors (one per side ) were carefully adapted and attached to the bone superior and inferior to the planned osteotomy by screws parallel to each other and to the acrylic splint lines The distractors were then removed and bone division was completed with manual soft tissue stretching to fully moblize the maxilla The distractors were then reapplied , followed by 1mm of initial acute distraction and wound closure DISTRACTION PROTOCOL:  Latency – 5days   Vertical distraction was initiated at 1mm/day for 12 days untill 20% of over correction was achieved,this is done to allow for relapse after device removal Consolidation – 10 wks
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  88. 88. INDICATIONS:  hemifacial microsomia with severe occlusal cant SURGICAL TECHNIQUE: MAXILLARY OSTEOTOMY:  An inncision is made in the upper buccal sulcus adjacent to first molars , then periosteum is elevated from the pyriform aperture to the malar area   The nasal mucoperiosteum is then elevated along the lateral maxillary wall and the nasal floor to the anterior nasal spine    Osteotomy is performed from the pyriform fossa laterally . The osteotomy is completed posteriorly with an 8mm chisel pterygomaxillary disjunction is completed via a curved osteotomy that extends laterally to the pterygoid fossa and the maxilla is slightly moblised
  89. 89. MANDIBULAR OSTEOTOMY:  After the maxillary osteotomy, a 5-7cm incision is made in the inferior buccal sulcus of the affected mandible     A periosteum is elevated on the lateral aspect of the mandible , exposing the inferior part of the ascending ramus and the gonial angle A subperiosteal tunnel is then made on the medial side of the mandible posteriorly to the alveolar ridge towards the posterior edge A corticotomy is performed on the lateral side of the mandible posterior to the alveolar ridge towards the gonial Completion of the bone division is confirmed by the bone segment mobilisation
  90. 90. DISTRACTION DEVICE APPLICATION:  Two bicortical fixation pins are introduced percutaneously , one in each bone segment, anterior and posterior to the osteotomy   The posiution of the screws is one of the most important parameters that determine sthe vector of the distraction Depending upon the grade of mandibular deformity ( PRUZANSKY Grade I, or 2A , or 2B) the vector of distraction should be approximatly 45,60,90 degrees to the horizontal plane respectively
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  93. 93. DISTRACTION PROTOCOL:  latency-5days    Intermaxillary fixation is applied and distraction is initiated at a rate of 1mm/day till facial symmetry is achieved Consolidation – 6-8wks Through out the treatment, IMF can be removed for short periods to allow the patient to eat or brush there teeth.
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  95. 95. REGENERATE DISORDERS AXIAL DEVIATIONS SOFT TISSUE OVER STRETCHING Hypotrophic regenerate sagittal Blood vessels Hypertrophic regenerate coronal Peripheral nerves Regenerate fracture horizontal Skeletal muscles Adjacent joints skin
  96. 96. Leader in continuing dental education