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Ct analysis of the position and corse of /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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  • 1. CT ANALYSIS OF THE POSITION AND COURSE OF MANDIBULAR CANAL relevance to sagittal split ramus osteotomy INDIAN ACADEMY DENTAL Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • 2. A IM OF THE STUDY Is to investigate the position and course of the mandibular canal through the mandibular ramus using ct imaging and to relate the findings to performing sagittal split ramus osteotomies. www.indiandentalacademy.com
  • 3. INTRODUCTION  The sagittal split ramus osteotomy is now widely used to correct jaw deformities.  In this tech the mandibular ramus is split on both sides in the sagittal plane and the distal fragment is moved forward and backward.  Due to the position and course of mandibular canal, the IAN is at great risk of injury during ssro. incidence:- immediate post www.indiandentalacademy.com ranges from 49%-100% op sensory impairment
  • 4. PATIENTS AND METHODS   The subjects for this study included skeletal class 3 patients with symetry A Transaxial ct scan with a slice thickness of 2mm,scan time 7s,120kv,140ma/s was done. 35 pts Age 15-34 yrs (mean age 23 yrs) MALES-12 www.indiandentalacademy.com FEMALES-23
  • 5. CT LOCATIONS IN each pt 4 ct scans were made at 4 standardized locations.  MF-MANDIBULAR FORAMEN-In a plane at the bottom point of the foramen.  MA-MANDIBULAR ANGLE-Point where a line drawn from posterior point of the second molar intersects the mandibular canal.  MP-MIDPOINT-At an intermediate between MF and MA.  MB-MANDIBULAR BODY-At a point close to where a perpendicular line drawn from the center of the second molar intersects the inframandibular margin and mandibular canal. www.indiandentalacademy.com
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  • 7. MEASUREMENTS AT EACH POINT  Total thickeness of the mandible through the center of mandibular canal.  Diameter of the inner mandibular canal.  Narrowest portion of the bone marrow space between the outer mandibular canal and both the lateral and medial cortical bone of the ramus. www.indiandentalacademy.com
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  • 9. RESULTS www.indiandentalacademy.com
  • 10. Thickness of the mandible increased from mandibular foramen to the mandibular body. 14 12 10 8 TCK MN 6 4 2 0 MF MP MA www.indiandentalacademy.com MB
  • 11. DIAMETER OF THE INNER MANDIBULAR CANAL (ALMOST SAME) 3 2 DIA MC 1 0 MF MP MA MB www.indiandentalacademy.com
  • 12. WIDTH OF BONE MARROW-SIGNIFICANT DIFFERENCES NOTED BETWEEN MP AND MB ON BUCCAL SIDE,AND BETWEEN MF,MA AND MB ON LINGUAL SIDE. 4 3.5 3 2.5 BUCCAL LINGUAL 2 1.5 1 0.5 0 MF MP MA www.indiandentalacademy.com MB
  • 13. Classification of the mandibular canal position within the bone marrow space.    SEPARETE TYPE-with bone marrow space visible255/280(91.1%). CONTACT TYPE-with outer surface of the canal and inner surface of the buccal cortical bone in contact17/280(6.1%). FUSION TYPE-with outer cortical plate of the canal not evident-8/280(2.9%). www.indiandentalacademy.com
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  • 15. Course of mandibular canal  Most frequently encountered case was one in which the bone marrow space between mandibular canal and the inner surface of the lateral cortex was present,this type presents less risk of injury to the nerve during surgery.  The contact or fusion type anatomy was detected at various sites from MF and MA areas.7 rami had contact at MP. www.indiandentalacademy.com
  • 16.  3 rami contact at MA(4.3%).  3 rami at MF+MP+MA(4.3%).  1 ramus at MF+MP(1.4%).  1 ramus at MP+MA(1.4%).  Only 1 ramus showed no marrow space at MA+MB areas. www.indiandentalacademy.com
  • 17. DISCUSSION The greatest bone marrow space is found at first and second molar areas. In 22.9%(16/70)rami had contact or fusion type of mandibular canal and in many cases it was observed from mandibular foramen to the mandibular angle. Results suggest that a vertical cut of the buccal side of the mandible performed just anterior to the mandibular angle may be advantageous. www.indiandentalacademy.com
  • 18. Even if a vertical cut is made at the safest site with careful splitting, the inferior alveolar neurovascular bundle may be encountered or impaired in individuals with fusion type mandibular canal. Various techniques can be used for tretment of mandibular prognathism mainly intraoral vertical ramus osteotomy(IVRO), SSRO, and inverted L osteotomy. With respect to neurologic damage it seems logical that IVRO or ILRO would be preferable to SSRO. www.indiandentalacademy.com
  • 19. THE ANATOMICAL LOCATION OF MANDIBULAR CANAL; ITS RELATIONSHIP TO SAGITTAL RAMUS OSTEOTOMY BY RAJCHEL J ELLIS III E int j adult orthod orthognath surg 1986 vol 1 She reported on the anatomical bucco lingual location of the mandibular canal using dried mandibles of adult asians of unknown sex. They sectioned the dry mandibles at five locations perpendicular to the sagittal plane of the body of the mandible. RESULTS:-she concluded that the greatest distance between the cortical plate and the canal was at the level of 1st and 2nd molars while the smallest distance was at the 3rd molar. www.indiandentalacademy.com
  • 20. RELATIONSHIP OF THE MANDIBULAR CANAL TO THE LATERAL CORTEX OF THE MANDIBULAR RAMUS AS A FACTOR IN DEVELOPMENT OF NEURO SENSORY DISTURBANCE AFTER BILATERAL SAGITAL SPLIT RAMUS OSTEOTOMY BY YAMAMOTO R,OHNO K,MICHI K J ORAL MAXILLOFAC SURG 2002; VOL 60 www.indiandentalacademy.com
  • 21. Purpose:- this study evaluated the location of the mandibular canal canal in the ramus of mandible before the bilateral sagittal split ramus osteotomy and examined its relationship with the postoperative sensory disturbance. Patients and methods:- 20 pts undergoing ssro. The plane containig the lowest point of the mandibular foramen 22mm below it was observed on a transaxial cts acquired with a 2mm slice thickness and a slice interval of 2mm. The relationship between the distance from the mandibular canal to the external cortical bone and neurosensory disturbance in the lower lip or mentum more than one year after one year after surgery was evaluated. www.indiandentalacademy.com
  • 22. RESULTS:-THE MANDIBULAR CANAL CAME INTO CONTACT WITH THE EXTERNAL CORTICAL PLATE ON 10 SIDES(25%) AND NEUROSENSORY DISTURBANCE OCCURRED ON ALL THESE SIDES. In all these cases the vertical extent of contact ranged from 2 to 18mm(average 10.6+_4.9 mm) In 30 sides(75%) showed no contact between canal and cortical plate of bone. The neurosensory disturbance usually presented one year after surgery and occurred in all cases with bone marrow thickness of 0.8mm or less. CONCLUSION:-the increased risk of NS disturbance occurred when there is a contact between canal and external cortical plate should be considered www.indiandentalacademy.com during SSRO.
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  • 24. TECHNICAL MODIFICATION OF SSRO BY FUN-CHEE L Oral surg oral med oral pathal 1992 vol 74 www.indiandentalacademy.com
  • 25. INSTRUMENTATION:- instruments needed are broad chisel,measuring 2 cm wide 4mm thick with a curved handle and T shaped bone cleaver. TECHNIQUE:-adequate removal of cortical bone along the osteotomy lines until the cancellous layer is reached is an impotant requisite to achieving a successful and predictable SSRO. The only area where cortical bone is not weakend by cutting instrument is inferior body of the ramus and posterior part of the body of the mandible. Attention is needed here. www.indiandentalacademy.com
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  • 27. The rationale of using a curved monobivel instrument is to direct cleaving edge of the instrument towards the buccal cortex and to create a plane of cleavage buccal to the inferior dental canal. The broad width ensures sufficient separation of the buccal and lingual cortices for inspection of the inferior dental neurovascular bundle after the split has been initiated superiorly. The use of ‘T’ shaped cleaver at the anterosuperior corner of the proximal segment with one limb of the “T” in the osteotomy line and other resting on the buccal cortex of the distal segment is found to be useful because the force is distributed and hence the chance of fracture at a particular preassure point is reduced. www.indiandentalacademy.com
  • 28. Edging the cleaver along the anterior border of the proximal segment towards the lower border ensures a gradual splitting to occur. This process simultaneously redistributes the force to the different parts of the bone and guides the plane of split. The last remaining area of the bone adherence is the inferior border. Hence the “T” shaped cleaver is used to edge along the inferior border and prying at the same time to complete the split. Because the cleaver is kept below the inferior dental neurovascular bundle, therefore there is no danger of www.indiandentalacademy.com injury to structure during this procedure.
  • 29. The author believe that a deliberate attempt to effect the split as close to the buccal cotex as possible and to keep a watchful eye on the inferior dental canal during instrumentation is an important factor. RESULTS:- author succeeded in all the cases except in four cases where the canal came into contact with the external cortical bone. www.indiandentalacademy.com
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  • 31. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com