The document outlines treatment protocols for managing dental crowding, categorizing it into mild, moderate, and severe cases with specific guidelines on extraction and non-extraction strategies. It emphasizes the importance of anterior, posterior, vertical, and lateral dimensions in determining the appropriate treatment approach, particularly regarding the extraction of teeth and the impact on facial aesthetics. Additionally, it highlights the relationship between dental arch width and facial proportion in achieving optimal esthetic outcomes.

1. PROF DR HLA HLA YEE

2. Space discrepancies
(space deficiency)
 Up to 4mm
(mild crowding)
 5mm to 9mm
(moderate crowding)
Treatment Protocol
 Non-extraction
 Disking
 Expansion
(except for third molar)
 Non-extraction
 Expansion
or
 Extraction of some teeth
other than third molar

3.  10mm or more
(severe crowding)
 Extraction regardless
of what happen to
third molar at later
state

4. DECISION FOR EXTRACTION AND NON-EXTRACTION
Depends on :
Dimension of the dentition (or denture)
(1) Anterior dimension or boundaries
(2) Posterior dimension or limitation
(3) Vertical dimension
(4) Lateral or transverse dimension

5. (1) Anterior dimension or boundaries
 Tweed defined the anterior limit of the dentition.
(Anterior limit of the denture base and the correct
inclination of the mandibular incisors on the bony
base.)
 The Tweed cephalometric triangle is constructed.
 This triangle is based upon the Frankfort horizontal
plane , the mandibular plane and the axis of the
mandibular incisor.

6.  FMPA is 20 – 29 degree ----- FMIA should be 68 degree.
 FMPA is 20 degree or less ----- IMPA is 91 degree.
 FMPA is 30 degree or more ----- FMIA should be 65
degree.
 If FMPA is low , the mandibular incisor should not be
pushed forward from their original position if the muscular
balance is normal.
 Therefore , extractions are often necessary if the anterior limit
of the dentition is to be respected in the presence of significant
anterior crowding and / or protrusion.

7. FMPAA
FMIA
IMPA
FHP
MP
Long axis
of the
lower
incisor

10. (2) Posterior dimension or limitation
 The posterior dimension of the mouth is important to
note that when non-extraction treatment is touted ,
32 teeth must be maintained in the mouth.
 The extraction of third molar is a therapeutic decision .
 If a patient has to have third molar extracted , it is
extraction treatment , not non-extraction treatment.
 The non-extraction treatment cannot be performed if the
second molars are hopelessly impacted.

12. (3)Vertical dimension.
 If the vertical dimension is increased in the posterior area
of the mouth , a long face is created . There may be more
gingival display on smiling.
 Also , if the maxillary posterior teeth are driven distally
to correct Class II malocclusion , when no space is
available , there is a wedging open effect in the anterior
vertical dimension that creates a longer face .
 Every 1 mm of vertical expansion in molar area , a
1.3 mm increase in anterior facial height occurred .

13.  Patients who need extractions but who are treated without
them are very often expanded vertically , Point B drops down
and back , poor facial esthetic is the result.
 Except in patients with deep bites who have poor vertical
development , it is crucial to preserve the vertical dimension if
stability , as well as facial balance and harmony , are the
ultimate goals.

14. (4)Lateral dimension.
 Lateral expansion is touted in many circles.
 The downward and backward mandibular rotation that
took place on the non-extraction patient.
 The extraction patient expressed downward and forward
mandibular development.
 The lower lip eversion and soft tissue imbalance on the
non-extraction patient.
 The extraction patient has improved facial balance.
 The non-extraction patient was expanded anteriorly ,
posteriorly , vertically and laterally.

15. • Arch expansion can perform in patient with narrow maxillary
arch with wide buccal corridors .

16. A B
The width of the maxillary dental arch , as seen on smile , should be
proportional to the width of the mid-face .
A – a broad smile is appropriate for a face with relatively large width across
the zygomatic arches ,
B - a narrow smile is preferred when the face width is narrow.
- this patient was appropriately treated with maxillary premolar
extraction to prevent over-expansion during treatment.