This document discusses removable orthodontic appliances. It describes the three main components - active components that apply forces, retention components like clasps, and the baseplate framework. Common active components include springs, bows, screws, elastics and retractors. Retention is provided by various clasps that engage undercuts. Baseplates are typically made of acrylic and incorporate the other components. Removable appliances have advantages like less chair time and lower cost but also disadvantages like less control over multiple simultaneous movements and reliance on patient compliance.

1. DR ARUNESH VERMA

2. • INTRODUCTION
• COMPONENTS OF REMOVABLE APPLIANCES
• Active components
• Retentive components
• Base plate or framework
• ADVANTAGES OF REMOVABLE APPLIANCES
• DISADVANTAGES OF REMOVABLE APPLIANCES

3. REMOVABLE APPLIANCES
• Removable orthodontic appliances as the term suggest are
devices that can be inserted into and removed from the oral cavity
by the patient at will.
• These are useful in variety of situations but present the inherent
disadvantage of the treatment being in control of the patient.
• Also movement of teeth in all the three planes of space cannot be
carried out simultaneously.

4. • The removable orthodontic appliances are made up of three components:
• Force or active components: comprises of springs,screws,bows,retractors or
elastics.
• Fixation or retentive components: usually include clasps
• Baseplate or framework: can be made of cold cure or heat cure acrylic.

5. ACTIVE COMPONENTS
These constitute the components of the removable appliance which
apply forces to the teeth to bring about the desired tooth movement.
Active component include:
1.Springs
2.Bows
3.Screws
4.Elastics
5.Retractors

6. • A wide variety of springs are available for incorporating in the removable appliance.
• Based on the presence or absence of helix they can be classified as:
• 1. Simple
• 2.compound
• Based on the presence of loops or helix they can be classified as:
• 1. Helical springs
• 2.Looped springs
• Based on the nature of stability of the spring is classified as:
• 1.Self supported springs
• 2.Supported springs

7. Different types of springs
Finger springs
Coffin spring
T spring Z spring

8. • Bows are active components that are mostly used for incisor retraction. There are
various types of bows routinely used by orthodontist.
• Some of the most commonly used labial bows are:
SHORT LABIAL BOW LONG LABIAL BOW

9. Split labial bow for retraction of anteriors Split labial bow for closure of midline diastema
High labial bow with apron spring Fitted labial bow

10. Mill’s labial bow
Reverse labial
bow

11. • Screws are active components that are used to provide intermittent
forces in removable appliances. They can be used to bring about various
kind of tooth movements.
• Consist of a Rod with left and right hand threads at both ends and nut in
the centre which is turned for activation.
• The appliance is retained with Adams clasp on posterior teeth.
• A wide variety of tooth movements are possible based on the location of
screw, number of screws and location of the split in the plate.

12. Removable appliances incorporating
screws
For arch expansion
For distal movement
of teeth
For buccal movement
of teeth

13. • They are routinely used in conjunction with fixed appliances but can
provide the force component in removable appliances is suitable
circumstances.
• Can be used along with removable appliances for retraction of
anterior teeth.
• They are attached to the hook made in labial bow distal to canine.
• The disadvantages of such an appliance include the risk of the elastic
slipping gingivally and causing gingival trauma and the risk of arc
form getting flattened.

14. Removable
appliances using
elastics for anterior
retraction
Removable appliance used to
engage elastics from partially
erupted teeth

15. • These are springs that bring about distal movement of canines.
• They can be classified as:
• Based on their location:
• 1.Buccal -placed buccally
• 2.Palatal-placed palatally
• Based on design:
• 1. Helical canine retractor
• 2.Looped canine retractor
• Base on mode of action:
• 1.Push type
• 2.Pull type

16. Palatal canine retractor Helical canine retractor
U loop canine retractor

17. • These components helps to retain the appliance in place and resist displacement
due to the active components.
• Retention in a removable appliance is given for the following reasons:
• Active forces from bows, springs, screws and elastics can displace the
appliance and make it ill fitting.
• A loose fitting appliance is uncomfortable and if it is continually moving in
the mouth it can lead to metal fatigue and failure.
• Because of the above reasons patient compliance will be poor and
necessary tooth movement will not take place.
• Good fixation is required to minimise such problems.Adequate retention
is aided by wire components which are known as clasps.

18. • They are supposed to hold the teeth in such a manner so as to resist
the displacement of the appliance.
• A clasp engages undercut areas to aid in the retention of a removable
appliance.
• There are two types of undercuts:
• The proximal undercut -the Adams clasp and crozat
clasp make use of these undercuts.
• The cervical undercuts- circumferential and Jackson’s
class are examples of clasp that engages the cervical
undercuts.

19. Circumferential clasp also known as
three quarter clasp or C clasp
Designed to engage buccocervival
undercut
Jackson’s clasp also known as full
clasp or U clasp
Designed to engage buccocervical
undercut

20. Adams clasp
Single arrowhead adams
clasp Adams with J hook

21. Adams on incisors
Adams with helix

22. Schwarz clasp Crozat clasp
Ball end clasp Triangular clasp

23. • It forms a major part of the removable appliances. The material most
often used for baseplate is called cold cure or heat cure acrylic.
• Uses:
• It incorporates both the retentive and active component
into a single functional unit.
• It helps in anchorage and retention of the appliance in the
mouth.
• It helps resist unwanted drift during tooth movement.
• It distributes the forces from the active components over a
larger area.

24. • Modifications:
• Bite platforms, whether anterior or posterior can be
incorporated into the base plate.
Anterior bite plane Posterior bite plane

25. ADVANTAGES OF REMOVABLE
APPLIANCES
• The patient can continue with the routine oral hygiene procedures without
any hindrance the oral cavity as well as the appliance can we kept clean.
• Most forms of tipping movement can be carried out successfully.
• Appliance fabrication is done in the specialised labs hence the chair side
time for appliance delivery is considerably less as compare to fixed
appliances.
• These appliances are relatively cheap as compare to the fixed appliances.
• The time required by the clinicians to activate an appliance is less. This
allows the clinicians to see more patients in a lesser time .

26. DISADVANTAGES OF REMOVABLE
APPLIANCES
• Patient cooperation is the keyword in removable appliance
therapy.
• These appliances are capable of only certain types of
movements,they do not give three dimensional control over the
teeth to be moved.
• Multiple movements are difficult.
• Chance of appliance loss and/or breakage is more.

27. References
• Contemporary Orthodontics by William R. Proffit
• Orthodontics-Principles And Practice by Thomas
M. Graber
• Textbook of Orthodontics:Gurkeerat Singh