CT ANALYSIS OF
THE POSITION AND
COURSE OF
MANDIBULAR
CANAL
relevance to sagittal
split ramus osteotomy

INDIAN
ACADEMY

DE...
A IM OF THE STUDY
Is to investigate the position and course of the
mandibular canal through the mandibular ramus
using ct ...
INTRODUCTION


The sagittal split ramus osteotomy is now widely used to
correct jaw deformities.



In this tech the man...
PATIENTS AND METHODS




The subjects for this
study included skeletal
class 3 patients with
symetry
A Transaxial ct sca...
CT
LOCATIONS
IN each pt 4 ct scans were made at 4 standardized
locations.
 MF-MANDIBULAR FORAMEN-In a plane at the bottom...
www.indiandentalacademy.com
MEASUREMENTS AT EACH POINT
 Total thickeness of the mandible through the

center of mandibular canal.
 Diameter of the i...
www.indiandentalacademy.com
RESULTS

www.indiandentalacademy.com
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...
DIAMETER OF THE INNER MANDIBULAR
CANAL (ALMOST SAME)
3

2
DIA MC
1

0

MF

MP

MA

MB

www.indiandentalacademy.com
WIDTH OF BONE MARROW-SIGNIFICANT DIFFERENCES NOTED
BETWEEN MP AND MB ON BUCCAL SIDE,AND BETWEEN MF,MA AND MB ON
LINGUAL SI...
Classification of the mandibular canal
position within the bone marrow space.





SEPARETE TYPE-with bone marrow space...
www.indiandentalacademy.com
Course of mandibular canal


Most frequently encountered case was one
in which the bone marrow space between
mandibular c...


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%).



O...
DISCUSSION
The greatest bone marrow space is found at
first and second molar areas.
In 22.9%(16/70)rami had contact or fus...
Even if a vertical cut is made at the safest site with
careful splitting, the inferior alveolar neurovascular
bundle may b...
THE ANATOMICAL LOCATION OF MANDIBULAR CANAL; ITS
RELATIONSHIP TO SAGITTAL RAMUS OSTEOTOMY BY
RAJCHEL J ELLIS III E
int j a...
RELATIONSHIP OF THE
MANDIBULAR CANAL TO THE
LATERAL CORTEX OF THE
MANDIBULAR RAMUS AS A FACTOR
IN DEVELOPMENT OF NEURO
SEN...
Purpose:- this study evaluated the location of the mandibular
canal canal in the ramus of mandible before the bilateral
sa...
RESULTS:-THE MANDIBULAR CANAL CAME INTO
CONTACT WITH THE EXTERNAL CORTICAL PLATE ON
10 SIDES(25%) AND NEUROSENSORY DISTURB...
www.indiandentalacademy.com
TECHNICAL
MODIFICATION OF
SSRO
BY
FUN-CHEE L
Oral surg oral med oral pathal 1992 vol 74
www.indiandentalacademy.com
INSTRUMENTATION:- instruments needed are
broad chisel,measuring 2 cm wide 4mm thick with a
curved handle and T shaped bone...
www.indiandentalacademy.com
The rationale of using a curved monobivel instrument is to
direct cleaving edge of the instrument towards the buccal
corte...
Edging the cleaver along the anterior border of the
proximal segment towards the lower border ensures
a gradual splitting ...
The author believe that a deliberate attempt to
effect the split as close to the buccal cotex as
possible and to keep a wa...
www.indiandentalacademy.com
Thank you
For more details please visit
www.indiandentalacademy.com

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

  1. 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. 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. 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. 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. 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
  6. 6. www.indiandentalacademy.com
  7. 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
  8. 8. www.indiandentalacademy.com
  9. 9. RESULTS www.indiandentalacademy.com
  10. 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. 11. DIAMETER OF THE INNER MANDIBULAR CANAL (ALMOST SAME) 3 2 DIA MC 1 0 MF MP MA MB www.indiandentalacademy.com
  12. 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. 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
  14. 14. www.indiandentalacademy.com
  15. 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. 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. 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. 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. 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. 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. 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. 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.
  23. 23. www.indiandentalacademy.com
  24. 24. TECHNICAL MODIFICATION OF SSRO BY FUN-CHEE L Oral surg oral med oral pathal 1992 vol 74 www.indiandentalacademy.com
  25. 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
  26. 26. www.indiandentalacademy.com
  27. 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. 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. 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
  30. 30. www.indiandentalacademy.com
  31. 31. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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