indication and steps of activator construction is presented

1. Presented by:
Prof. Dr. Maher Abd El Salam Fouda

2. A Class II Division 1 case indicated for treatment
with activator

4. 1- Extraoral examination
- Retrognathic profile
- Patient is asked to
protrude the
mandible, to give a
simulation of how
the facial
appearance would
be if mandibular
growth occurred.

5. 2- Impressions
It’s important to ensure
a good impression in
the lower lingual
sulcus area

6. 3- Study casts

8. 4- Intraoral Examination

10. 5- Radiographs

15. Assessment of overjet
Overjet < 11 mm

16. Assessment of ANB angle
ANB +2 - +6

17. Assessment using Wits
appraisal
Wits appraisal
-1mm to + 4.5 mm

19. The Andresen type
activator is a tooth-
borne passive
appliance that opens
the bite and the
mandible is
advanced for Class
II correction

20. The activator consists
of a single block of
plastic constructed
so that lingual
flanges on lower
cause the mandible
to be positioned
forward

21. Mandibular incisors are capped so that forward
movement is resisted while the mandibular posterior
teeth are free to erupt

22. Steps of construction
A piece of wax of
approximate 6 x 8
cm dimensions is
warmed in hot water
and folded over to
make a soft roll

23. Register the bite with
the mandible in a
protruded position

24. Alternatively, bite may
be registered by
means of exacto bite

25. The indentations in the
wax form the lower
teeth should be 2 or
3 mm deep

26. The impressions are
poured in stone and
carefully mounted
on a plane line
articulator, ensuring
that the bite is
correct

27. The labial bow of 0.8
mm wire is
reinforced with
stainless steel
tubing where it will
enter the baseplate

28. The tags of the labial
bow are turned
down at right angles
to the palate

29. The softened roll of
wax is placed just
below the occlusal
surfaces of the teeth
and pressed firmly
into the
embrassures
between the teeth
and spread onto the
palate

30. The upper and lower
baseplates are
waxed
Incisal edges of
mandibular anteriors
are capped with a
thin layer of wax

31. The completed waxed
up activator

32. The appliance
embedded in the
deep half of the flask

33. The finished appliance

34. For the average angle cases, the acrylic can be left
untrimmed to restrict eruption of the lower molars.

35. In low angle cases, acrylic trimming is done to allow
eruption of posterior teeth

36. It is possible to grind
grooves into the
acrylic adjacent to
upper molars and
premolars, so that
they are guided in
a distal and buccal
direction during
eruption, and this
can help to
maintain good
lateral arch
coordination as the
overjet reduces.

37. Buccal movement of a
molar tooth by
means of a pad of
rubber pulled into an
undercut hole in the
baseplate

39. Skel Activator
Acrylic base is from the
mesial part of the
canines to the distal
end of the molars
both acrylic parts of
the upper and lower
jaw are connected.

40. Woodside Activator
The mandible is advanced
for correction of Class II
Maxillary posterior teeth
are prevented from
erupting by acrylic shelf
but mandibular
posterior teeth are
free to erupt
The appliance has a
displacement spring on
upper first molars

41. Teuscher Activator
Used in conjunction
with headgear to
maintain upper
molar position.
Upper torquing springs
are also featured in
this appliance.

42. LSU Activator
Maxillary first molars
should have bands
with headgear tubes
in order to give the
ball-end “C” clasp a
positive lock around
the tubes

43. Hamilton expansion
Activator
The mandible is
advanced and the
maxillary arch is
expanded by the use
of expansion screws.
The lower posterior
area is void of acrylic
to allow for eruption.

44. Case Report
11 year old male

45. Uncrowded Class II
division 1
malocclusion with an
overjet of 11.5 mm,
and an upper
midline diastema of
1.5 mm, with a
minor left-side
crossbite

47. SNA 86º
SNB 82°
ANB 4°
Wits +4 mm
MM 21°
U1 to Max plane 138°
L1 to Mand plane 94°

49. Andresen was
constructed using a
wax bite with the
mandible protruded
approximately 8 mm
It was worn for 10
months
The lower molars and
second premolars
were free to erupt.

50. 10 months later
The overjet was
reduced from 11.5
mm to 3.5 mm using
only the Andresen
appliance for 10
months
The molars and
premolars were in
Class I relationship

52. Thank you