TRAJECTORIES OF FORCE by DR BEJOY P.U , MALABAR DENTAL COLLEGE

1. Growth & Development of
Nasomaxillary Complex
DR. BEJOY P.U
PROF & HOD
MALABAR DENTAL COLLEGE
& RESEARCH CENTER

2. Stress trajectories of force
Maxillary rotations
Clinical Implications of G & D of
Nasomaxillary Complex
Growth & Development of
Nasomaxillary Complex

3. Stress Trajectories of Force
“Function can influence the overall pattern and
relationship of the structures”.
Effect of function on bone was first noted in femur .

4. In 1867 an anatomist named Meyer with the
help of the mathematician Culmann
propounded Trajectorial theory of Bone
formation.
Julius Wolff –1870
“Trabecular alignment in the bone was
primarily due to functional forces”.
ROUX-Law of transformation of bone.
Stress Trajectories of Force

5. Stress Trajectories of Force
A change in the intensity and direction of
these forces would produce a change in the
internal architecture and external form of
the bone.
Change in the functional forces produce
measurable changes in bony architecture.

6. Stress Trajectories of Force
Benninghoff made an exhaustive study of
the architecture of the cranial &facial
skeleton and so called “Stress Trajectories”
or “Lines of force” evolved.

7. 3 main vertical pillars of stress trajectories
can be seen in the nasomaxillary region.
a.Canine pillar
b. Zygomatic pillar.
c.Pterygoid pillar

8. Maxillary rotations
Implant studies of jaw rotations were
mainly carried out by Bjork & Skeiller in
1960’s
Tantalum metallic pins were used
Rotations are classified into
Internal
Rotation
External
Rotation

9. Maxillary rotations
Lateral implants:4yrs of age
-inserted laterally in the zygomatic
process of the maxilla.
 Anterior implants:10-11yrs of age
-inserted below the anterior nasal
spine.

10. Lateral View

11. MAXILLARY ROTATIONS
1. Transverse Plane
2. Vertical Plane

12. Maxillary rotations
Transverse mutual rotation of the two
maxilla:-

13. Maxillary rotations
Increase in width of the midpalatal suture is
not same between anterior and posterior
regions.As a result the two maxillae rotate
in relation to each other in transverse plane.

14. VERTICAL ROTATION

15. Maxillary rotations
Vertical rotation of the maxillary
complex:-.
-Downward and forward displacement of
maxilla during growth are associated with
vertical rotation
Bjork & Skeiller.

17. “Interaction between Jaw growth & Tooth
eruption.”
Translocation
True Eruption

18. Clinical Implications of Maxillary
Growth.
Cessation of growth of maxilla is in the
following order:-
-Transverse direction
-Anteroposterior plane
-Vertical direction.

19. Transverse Growth of Maxilla
Growth in width is the first one to drop to
the adult levels [by onset of puberty].
Deficiency in the transverse growth of
maxilla causes decrease in the width of
palate leading to crossbite.

20. Crossbites
Skeletal Dental

21. .
Circummaxillary sutures.
RAPID MAXILLARY EXPANSION
1. Nasomaxillary Suture
2. Frontomaxillary Suture
3. Zygomaticomaxillary Suture
4. Lacrimomaxillary Suture
5. Ethmoidomaxillary Suture
6. Vomeromaxillary Suture

22. Structure of the suture at different ages:
Infancy
Juvenile
Adulthood

23. Activation of RME.
Upto 15yrs of age 1800 (2 turns daily)
15-20yrs. of age 1800 (4 turns daily)
Over 20yrs. 900 (2 turns daily)

24. How much to Expand?
Palatal cusps of upper maxillary teeth
should occlude with the lingual inclines of
the buccal cusps of the lower mandibular
teeth.

25. Effects of RME:-
-Midpalatal suture opens anteroinferiorly.
-Midline diastema.
-Buccal flaring of posteriors.

26. Frontal View

27. Ideal patients for RME treatment.
 Full cusp cross bite with a skeletal
component
 Some degree of dental as well as skeletal
constriction initially
 No pre-existing dental expansion.

28. Nasal hump & paranasal swelling.
Pain.
Buccal tipping of posteriors.
Root resorption.
Adverse effects of RME:-

30. Rapid maxillary expansion Vs slow expansion

31. Dental cross bites are corrected by
-Quad helix
-W arch
-Arch wire

32. Anteroposterior growth of maxilla.
Maxillary excess:-For restriction of
maxillary growth in growing individuals
appliances like
1.Headgear
2.Functional appliances

34. Cervical head gear:
used in patients with horizontal growth
pattern with reduced lower facial height.
Types of Head Gears:-

35. Types of head gear’s
Occipital pull Head gear:-
Used in long face patients
with high mandibular
plane angle.

36. Functional Appliances
They are of two types:-
-Removable
-Fixed Appliances.

37. Removable Appliances:
Activator Bionator
Twin Block

38. Fixed Appliances:-
Herbst Appliance
Jasper Jumper

39. Dental camouflage can be done for mild to
moderate skeletal problems.
For adult patients where growth is no longer
present surgical correction should be done.

40. Maxillary Deficiency:-Growth
modulation in sagittal plane can be
done by
1.face mask
2.reverse functional appliances.

41. Face mask Therapy
Delaire Facemask

42. Face mask Therapy
Petit Face mask

45. Twin Block
Reverse Functional appliances:
Functional Regulator

46. Vertical excess of maxilla can be controlled
by inhibiting the descent of maxilla and
eruption of posterior teeth.
Vertical growth of maxilla

47. Frequent respiratory Nasal Septal Contracted
Swollen Nasal
Mucosa Reduced Nasal Decrease in
Enlarged breathing Nasal width
adenoids
Mouth breathing
Lowered Extended
tongue position head posture
Lowered Mandibular
Posture
infection deviation Maxillary arch

48. Hierarchy of effectiveness in long-face class II
treatment
HP headgear to functional appliance
ht Bite blocks on functional appliance
High-pull headgear to maxillary splint
High-pull headgear to molars.

49. -Highpull headgear to a maxillary splint

50. Highpull headgear to a functional appliance.

51. Functional appliance with increased
height of the bite blocks

52. Bibliography:-
Contemporary orthodontics
-William Proffit
Orthodontic principles &practice
-T.M.Graber
Essentials of facial growth
- Enlow
Factors affecting the growth of mid face
- James Mc Namara
Rapid maxillary expansion
- Donald J. Timms