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1. DIAGNOSIS & TREATMENT PLANNING
IN
LOW ANGLE CASES

2. CONTENTS
• Introduction
• Development of vertical problem
• Classification of growth patterns
• Bjorks seven signs – mandibular growth prediction
• Diagnosis of low angle cases
a.Clinical examination
B.Cephalometric evaluation
• Different treament modalities in low angle cases
• Conclusion
• References

3. Introdoction
• The most important prerequisite for facial balance is a normal
vertical dimension of the lower face.
• Before initiation of orthodontic therapy ,it is vital for the
clinician to clearly define the treatment goals related to the
vertical dimension of face .

4. Development of vertical problem
• Facial growth in relation to the cranial base proceeds along a
vector with variable amounts of horizontal and vertical
growth.
• Vertical growth increments at the facial sutures and the
maxillary and mandibular alveolar process exceeds the
condylar growth ,the mandible would rotate backwards
• Growth at the condyle exceeds the total vertical growth at the
facial sutures and alveolar processes the mandible would
rotate forward

7. Growth rotations

8. BJORK SOLOW AND
HOUSTON
PROFFIT
Rotation of
mandibular core
relative to cranial
base
Total
rotation
True rotation
Internal
rotation
Mandibular plane
relative to cranial
base
Matrix
rotation
Apparent
rotation
Total
rotation
Mandibular plane
relative to the core
of the mandible Intra matrix
rotation
Angular
remodeling of
lower border
External
rotation

9. Growth rotations
• According to the type of rotation and the centre of rotation the
growth of the mandible can be divided into
– Forward rotation
• Type I
• Type II
• Type III
– Backward rotation (less common)
• Type I
• Type II

10. CORCOR FACIAL HEIGHTFACIAL HEIGHT CAUSECAUSE
AnteriorAnterior PosteriorPosterior
Type IType I JointJoint DecreaseDecrease
AFH lowAFH low
angleangle
-- Occlusal imbalance dueOcclusal imbalance due
to loss of teeth /to loss of teeth /
powerful musculature.powerful musculature.
Type IIType II Inciscal edge ofInciscal edge of
the lowerthe lower
anterior teethanterior teeth
Normal AFHNormal AFH MarkedMarked
increasedincreased
PFHPFH
(i). Lowering at middle(i). Lowering at middle
cranial fossa, loweringcranial fossa, lowering
the condylar fossathe condylar fossa
(ii). Vertical growth at(ii). Vertical growth at
the mandibular condylethe mandibular condyle
Type IIIType III At the level ofAt the level of
premolarspremolars
DecreaseDecrease
AFH lowAFH low
angleangle
IncreaseIncrease
PFHPFH
In anamolous occlusionIn anamolous occlusion
of anterior e.g.of anterior e.g.
Increased overjet.Increased overjet.
FORWARD ROTATIONS

11. CORCOR CAUSECAUSE FACIALFACIAL
Type IType I TMJTMJ 1. Raising of bite by1. Raising of bite by
orthodontic meansorthodontic means
Increased AFHIncreased AFH
2. Flattening of cranial2. Flattening of cranial
basebase
3. Oxycephaly3. Oxycephaly
Decreased PFHDecreased PFH
Increased AFHIncreased AFH
Type IIType II Most distalMost distal
occluding molarsoccluding molars
Growth in the saggitalGrowth in the saggital
direction at thedirection at the
mandibular condyulesmandibular condyules
Basal open biteBasal open bite
BACKWARD ROTATIONS
Less frequent than forward rotations

12. 2. FACIAL PATTERNS :
SHORT FACE PATTERN
Excessive forward rotation of mandible during growth.
Short Anterior LFH
Horizontal palatal
plane
Square jaw
(Mandible)
Square gonial
angle
Low MPAlow angle and
crowding

13. Excessive forward rotation may be due to
• (i) Increase in internal mandibular rotation
• (ii) Decrease in external rotation

14. MUTUAL RELATIONSHIP BETWEEN ROTATING JAW
BASES
• Rotation of mandible decides the vertical proportions of the
face.
• Horizontal growers have a
– Short lower anterior facial height.
– Predisposed to having a deep bite

15. • According to Lavergne and Gasson the mutual rotation of
the upper and lower jaw can be of following 4 types
1. Convergent rotation.
 Severe low angle.
 Difficult to treat with a functional therapy.
1. Divergent jaw bases.
 Severe open bite.
 In severe cases orthognathic surgery is required.

16. 3. Cranial rotation of both the bases.
 Horizontal growth pattern.
 Maxillary cranial rotation compensates for the
mandibular rotation.
 Normal overbite.
3. Caudal rotation of both bases.
 Vertical growth pattern.
 Maxillary caudal rotation compensates for the
mandibular rotation.
 Normal overbite.

17. Structural Signs of growth rotation
1. Condylar inclination.
2. Mandibular canal inclination.
3. Lower border of mandible (Antigonial notch).
4. Symphysis inclination.
5. Interincisal inclination.
6. Intermolar angle.
7. Lower face height.

18. Condylar inclination

19. Mandibular canal inclination.

20. Lower border of mandible
(Antigonial notch).

21. Symphysis inclination.

22. Interincisal inclination.
Intermolar angle.

23. Interincisal inclination.
Intermolar angle.

24. LOWER ANTERIOR FACIAL HEIGHT

25. DIAGNOSIS

26. The different diagnostic aids are
• Clinical examination
• Study models
• Cephalograms
• Photographs

27. CLINICAL EXAMINATION
• A) Extraoral examination
• B) Intraoral examination

28.  Short, square face and an edentulous
appearance.
 Maxillary incisors are hidden behind the upper
lip.
 The upper lip curves downward and the corners
of mouth are below the occlusal line
 Distinct skin folds are seen lateral to the oral
commissure.
VIKEN SASSOUNI:A CLASSIFICATION OF SKELETAL FACIAL TYPES:
AJO 1969 FEB VOLUME 55 NO.2 :109-23
Extra oral examination

29.  The posterior part of face appears wide because of prominent
mandibular angles.
 Large masseter muscles are attached to the laterally flared
gonial processes.
 the incisal edges of the maxillary anterior teeth are positioned
above the inferior margin of upper lip
 distinct chin button, which is made more apparent by a deep
mentolabial fold
 small gonial angles add to square appearance of the patients
face
VIKEN SASSOUNI:A CLASSIFICATION OF SKELETAL FACIAL TYPES:
AJO 1969 FEB VOLUME 55 NO.2 :109-23

30. Assessment of vertical height

31. B) Intraoral examination
• Absolute transverse maxillary excess.
• Mandibular overclosure
• Shorter dentoalveolar heights
• Deep overbite
• The maxillary arch is broad and the palatal vault is typically
flat.
• Maxillary buccal crossbites are commonly associated with
interdental spacing.
• Gingival recession with maxillary and / or mandibular incisors
is seen.
VIKEN SASSOUNI:A CLASSIFICATION OF SKELETAL FACIAL TYPES:
AJO 1969 FEB VOLUME 55 NO.2 :109-23

32. STUDY MODELS

33.  Study models show excessive overbite.
 Lower arch shows exaggerated curve of spee.
 Typically reverse curve or compensatory curve of maxillary
occlusal plane in cases of class II division 2 malocclusion.
 Palatal vault appears to be flat.
 Molars are in infraocclusion in true low angle cases.
 Incisors are supraerupted in pseudo low angle cases.
 Maxillary arch is wider.
 Sometimes teeth are in buccal cross bite.

34. PHOTOGRAPHS

36. FRONTAL VIEW
• In normal individual upper, middle and lower third of face are
proportional to each other but in low angle cases, the lower
third of face height is decreased.
• A study of the middle third of face shows broad nasal alar
bases and large nostrils.
• Full-face examination typically discloses that the patient has a
short, square shaped face and an edentulous appearance.
• The posterior part of face appears wide because of prominent
mandibular angle.

37. • The smile view shows maxillary incisors hidden behind the
upper lip.
• Frontal view shows curled or redundant lips.
• The upper lip curves downward and the corners of mouth are
below the occlusal line.
• Upper tooth to upper lip relationship is a vertical measurement
made in midline from the incisal edges of maxillary central
incisor to the most inferior portion of the upper lip. Usually
this distance is 2-5 mm. If the upper teeth are buried under the
upper lip, it indicates skeletal low angle.

38. • Interlabial distance is the vertical distance between the most
inferior portion of the upper and lower lip when the lips are
relaxed and the teeth are in centric relation. In normal
individual it is approximately 2mm.Decreased interlabial
distance or redundancy of the lips indicates low angle.

39. PROFILE VIEW
• 1. The lower third of face height is decreased.
• 2. Analysis of lower third of face reveals that nasolabial
angle is essentially normal or obtuse.
• 3. There is distinct chin button, which is made more
apparent by a deep mentolabial fold.
• 4. Lips are curled or redundant.

40. CEPHALOMETRIC VARIABLES

45. Mean value is 128±70

47. Divided into upper and lower by occlusal plane

48. TREATMENT PLANNING

49. • Patients with upward and forward growth of the mandibular
condyle often have reduced anterior face height; if they
develop a malocclusion, it is nearly always characterized by a
deep bite.

50. Classification
A) Developmental deep bite
1) Skeletal deep bite
--- horizontal growth pattern
2) Dento alveolar deep bite
--- supra occluded incisors
--- > inter occlusal clearance
(functionally a pseudo deep over bite)

51. B) Acquired Deep Bite
1) Lateral Tongue Thrust
Infra Occluded Posterior Teeth
Deep bite e.g. class II div 2
2) Early loss of Deciduous Teeth
Tipped Contiguous Teeth
Acquired Secondary Deep Over Bite
3) Wearing of Occlusal Surface
or Tooth abrasion
Acquired secondary over biteAcquired secondary over bite

52. MORPHOLOGY OF DEEP BITE
DEEP BITE
DENTO ALVEOLAR SKELETAL
(GROWTH PATTERN AVG TO VERTICAL) ( GROWTH PATTERN HORIZONTAL)
INFRA OCCLUDED MOLAR SUPRA ERUPTED INCISORS 1) ANT FACE HT
1- MOLARS PARTIALLY 1- INCISORS BEYOND 2) POST FACE HT
ERUPTED FUNCTIONAL OCC PLANE 3) INTER OCC CLR
2- INTER OCCLUSAL SPACE 2- FULLY ERUPTED MOLARS 4) II HORIZONTAL
3- LATERAL TONGUE THRUST 3- CURVE OF SPEE CEPH PLANES
4- DISTANCE B/W MAX,MAND 4- INTER OCC SPACE &

53. Characteristic findings of Deepbite:
Dentoalveolar Deep Overbite:
The growth pattern usually is average or tends toward the
vertical. The deep overbite caused by the infraocclusion
of molars has the following symptoms:
1. The molars are partially erupted.
2. The interocclusal space is large.
3. A lateral tongue posture and thrust are present.
4. The distances between the maxillary and mandibular
basal planes and occlusal plane are short.

54. The deep overbite caused by over eruption of the
incisors has the following characteristics:
1. The incisal margins of the incisors extend beyond
the functional occlusal plane.
2. The molars are fully erupted.
3. The curve of Spee (compensating curve) is
excessive.
4. The interocclusal space is small.

55. Skeletal Deep Overbite
• Horizontal type of growth pattern.
• The AFH is short, particularly the lower facial third,
whereas the posterior facial height is long.
• Ratio of U/L anterior facial height is reduced in the
skeletal deep overbite to a ratio of 2:2.5 or 2:2.8
(normal- 2:3).
• The horizontal cephalometric planes (sella-nasion,
palatal, occlusal, and mandibular) are approximately
parallel to each other.

56. • The interocclusal clearance is usually small.
• An extreme horizontal growth pattern can be at least
partially compensated by an up and forward inclination
of the maxillary base (anteinclination).
• On the other hand, the combination of a horizontal
growth pattern with a down and forward inclination
(retroclination) of the maxillary base results in a more
severe skeletal deep overbite.

57. Planning Treatment in
different age groups

58. Treatment planning in primary dentition
• An excessive overbite is seen in the primary
dentition, it is likely to have a skeletal basis with the
presence of developing class ii malocclusions.
• Activator type appliance may he used to direct
differential alveolar growth, reduce the interocclusal
distance, and improve skeletal morphology

59. Treatment planning for mixed dentition
• If the skeletal bases are class I with normal incisor angulation,
it is better to wait and watch till the eruption of the posterior
teeth which results in resolution of deep bite.
• In non skeletal deep bites a utility arch that incorporates molar
and incisor teeth can be used during the mixed dentition to
intrude, tip, or reposition both molars and incisors.

60. • Early childhood is the best time to treat complex deep bite.
• Functional jaw orthopedic appliances can then guide the
eruption of the permanent dentition upper molars.
• Deepbites with anterior vertical maxillary excess showing
gummy smiles can be intercepted by high pull headgears.

61. 61
Functionalappliances for
correctionof Deepbite

62. 62
• Functional appliances used for correction
of deepbite include
1.Activator
2.Bionator
3.Frankel appliance
4.Twin block

63. Activator
• Two movements are seen with
activator therapy
1. Extrusion
2. Intrusion
• Activator provides limited
intrusion
• Extrusion of molars can be
facilitated by loading the
lingual surfaces of these teeth
above the area of greatest
convexity in the maxilla or
below this area in the
mandible 63

64. When the deep overbite is due to infraocclussion of the
posterior teeth, the interocclusal clearance is large
and hence the construction bite is made high or
moderate accroding to thee size of the freeway
space.
64

65. Bionator
• Developed by Balters
• Method of trimming is
similar to activator except
1. To allow extrusion of the
posterior teeth some
acrylic is always left
interdentally at the level
of the occlusal plane
forming the so called
tooth bed
65

66. 2. The acrylic projections
between the teeth are
left untouched or
replaced with self cure
acrylic- they exert a
distalising influence on
the permanent first
molars
3. The occlusal surfaces
of the bionator are
trimmed to facilitate
transverse movement
66

67. Twin block
67

68. Frankel appliance
• Used for correction of class II div 2 is FR II
• Abnormal perioral muscle function has an ability to exert a
deforming action that prevents optimal growth and
development.
• Frankel appliance has buccal sheilds and lip pads that the
prevent the deforming muscle action in the dentoalveolar
region both during deglutation and at rest.
• Frankel is indicated in the mixed dentition with short lower
anterior facial height ,deep overbite and abnormal
activity,leading to bite opening and facial esthetics.
68

69. 69
Deepbite correction using
orthopeDic appliances

70. Cervical pull head gear
• It is the most common headgear used in patients
with decreased vertical dimension
• The force is exerted below the occlusal plane
producing both extrusive and distalising effects
• This type of traction is used when molar extrusion
is a desirable treatment outcome
• When used in conjunction with intrusive arch it
generates a moment opposite of the moment
generated by the intrusion arch and prevents
mesial movement of the roots of the molar
70

71. 71

72. Treatment planning for early permanent
dentition
• In class II div I growing patients intrusion or prevention of
excessive eruption of the lower incisors is achieved by
leveling out an excessive curve of Spee with the continuous
arch wire mechanics from molar to incisors.
• In the absence of growth, absolute intrusion is required and
segmented arch mechanics must be used to achieve this .
Eruption of the first molars can be aided by the use of a flat
maxillary bite plane or a monobloc and the incisors depressed
with utility archwire.

73. • METHODS OF DEEP BITE CORRECTION
• Deep overbite can be corrected by following
methods.
• Intrusion of anterior teeth
• Extrusion of posterior teeth
• Combination of both.
• Proclination of incisors.

74. EXTRUSION OF POSTERIOR TEETH
• Extrusion of posterior teeth is commonly indicated in patients
with decreased lower anterior face height.
• It is also indicated in true deep bite cases.
• If the incisal edges of the maxillary anterior teeth are
positioned above the inferior margin of upper lip, in these
cases extrusion of posterior teeth is indicated.
• Extrusion of molars of an average of 1mm results in 2 to 2.5
mm of bite opening.

75. • This is probably the most common and easiest, although not
always the best method to correct the deep overbites.
• Extrusion of posteriors can be done by myofunctional
appliances, removable appliances and fixed appliance therapy.
• Extrusion of posterior teeth in growing patients is stable but in
adults, it may result in relapse.

76. METHODS OF POSTERIOR EXTRUSION
• The posterior teeth can usually be leveled about several
centers of rotation, depending on the amount of required arch
length..
• 1. Tip-back mechanism.
• 2. Base arch mechanism.
• 3. 0.016-inch distal extension.
• 4. Parallel eruption of the buccal segment

77. Tip - Back Mechanism
1. In growing patients with a forward growth rotation.
2. For a deep curve of Spee in the lower arch.
3. For a deep overbite.
4. For slight arch length inadequacy (1 to 2 mm per
side).
5. For a steepened natural plane of occlusion.
INDICATIONS:

78. The tip-back mechanism consists of
1. 0.036-inch lingual arch.
2. 0.018 x 0.025 inch anterior segment, which
can sometimes be left long, distal to the cuspids.
3. Buccal stabilizing segments (BSS) of 0.018
x 0.025 inch from (ideally) 7-4,
4. 0.018x0.025 inch tip back spring

79. With the correct use of this tip-back mechanism, one will
notice that
1. The C Rot
is placed distally, somewhere around the
distal root of the second molar.
2. There is eruption and rotation of the buccal segments.
3. There is increased arch length distal to the canines (1 to
2 mm).
4. The second molar is often buried.
5. With the hook placed distal to the CRes
of the anterior
segment, the roots of the lower anterior segment often come
forward, which is good, if one is flattening the plane of
occlusion.
6. There is no flaring of the anterior teeth, because the
hook is made to slide freely along the anterior segment wire.

81. The force values used are calculated on the basis that between 3,500 and 4,000
g-mm is required to erupt and rotate the buccal segments optimally. This is a
moment of a force; the force can be calculated by knowing the distance from
the CRes
of the lower buccal segment (mesial to the lower first molar root for a
four -tooth segment ) to the point of attachment on the anterior segment:
3,500
____ = F
L
where L = the distance from the CRes
of the buccal segment to the point of
attachment on the anterior segment. The force can be adjusted using the
Dontrix tension gauge.

82. Base Arch Mechanism
The main difference between this applicance and the previous tip-
back mechanism is in the location of the center of rotations.
The force system is nearly identical to that of the tip-back spring, except for the
fact that there is no anterior hook free to slide anteroposteriorly; with the base
arch tied back securely as , the CRot
is moved mesially to somewhere close to
the mesial root of the first molar.

83. 1. Eruption and a negative rotation of the buccal segment
(flattening of the plane of occlusion).
2. No increase in arch length.
3. That the roots of the buccal segment move forward.
4. That second molars sometimes appear to be buried
(remember the negative moment

84. 0.016-inch Distal Extension
1. In order to use this appliance, there should be
Good growth increments remaining, since
the appliance is eruptive.
2. A significant second-order discrepancy
between the canines and the incisors;i.e., the
incisors should be higher than the canines.
3. Minimal arch length required (2 to 3 mm per
side).
4. A deep curve of Spee.
5. Extraction of teeth, usually the first premolars

85. •The appliance itself consists of 0.018 x 0.025 inch base
arch.0.016-inch distal extension.
•Immediately mesial to the canine bracket a vertical loop is
placed and immediately distal to the canine bracket a helix is
placed.
• The distal extension can be adjusted to lie over the tie-wings
of the second premolar bracket, or can be hooked over the
buccal segment wire.
•.0.036-inch lingual arch.

87. Parallel Eruption of the Buccal Segment
• Parallel eruption of the buccal segment is used in the
upper jaw only.
• Using a cervical headgear with its long outer bow bent
high (about 60 degrees), a negative moment is provided by
bringing the outer bow down to the line of action of the
headgear straps .
• Once engaged, the line of action of the force times the
perpendicular distance away from the CRes
of the upper jaw
produces a positive moment.
• Both moments tend to cancel each other out, and one is
left with a purely extrusive force to the buccal segments .

89. Removable appliances
• Maxillary acrylic bite plate or anterior bite plane:
• With this appliance in the mouth during the
mandibular closing movement, the mandibular
• incisors come in contact with the acrylic platform,
• which causes a disocclusion of the posterior teeth.

91. CONCLUSION

92. • The ability of an orthodontist to predict future mandibular
growth would greatly aid in the diagnosis and treatment
planning.
• Better therapeutic decisions could be made regarding timing
and length of the treatment, appliance selection, extraction
pattern and possible need for surgery.
• And with it’s knowledge therapy could be truly tailored to the
individual with the possibility of obtaining optimal results in
shorter period of time.

93. BIBLIOGRAPHY

94. • Essentials of facial growth – D.H. Enlow.
• Contemporary orthodontics – W.R. Proffit.
• Handbook of orthodontics – R.E. Moyers.
• Textbook of clinical orthodontics: ASHOK KARAD
• Dentofacial orthopaedics with functional appliances -Thomas
M.Graber, Thomas Rakosi, Alexandrer G.Petrovic
• The Rotation Of The Mandible Resulting From Growth: Its
Implications In Orthodontic Treatment - F. F. SchSome effects
of mandibular growth on the dental occlusion and profile –
R.J. Isaacson et.al., AO, April 1977, pg. 97-106.

95. • Prediction of mandibular growth rotation – A. Bjork, AJO, June
1969, pg. 585-599.
• The puzzle of growth rotation – J.M.H. Dibbets, AJO, June 1985,
pg. 473-480.
• Prediction of mandibular growth rotation evaluated from a
longitudinal implant sample – Bjork, Skieller and Hansen, AJO,
Nov 1984, pg. 359-370
• The puzzle of growth rotation. J.M.H.Dibbets –AJO-DO June 1985
,87,6;473-480.
• Patterns of vertical growth in the face:(AM J ORTHOD
DENTOFAC ORTHOP 1988;93:103-16.)

96. • Mandibular rotation and enlargement. J.M.H.Dibbets.AJO-
DO July 1990,29-32.
• Diagnosis of the Vertical Dimension:(Semin Orthod 2002;8:
120-129,)
• The vertical dimension,the low angle patient: WJO Volume 6:
number 2:2005