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Springs in Orthodontics
Orthodontics

Springs in Orthodontics

 Springs are essential components of removable orthodontic appliances, playing a crucial role in facilitating tooth movement. Understanding the mechanics of springs, their classifications, and their applications is vital for effective orthodontic treatment.

  •  Springs are active components of removable orthodontic appliances that deliver forces to teeth and/or skeletal structures, inducing changes in their positions.
  • Mechanics of Tooth Movement: To achieve effective tooth movement, it is essential to apply light and continuous forces. Heavy forces can lead to damage to the periodontium, root resorption, and other complications.

Components of a Removable Appliance

A removable orthodontic appliance typically consists of three main components:

  1. Baseplate: The foundation that holds the appliance together and provides stability.
  2. Active Components: These include springs, clasps, and other elements that exert forces on the teeth.
  3. Retention Components: These ensure that the appliance remains in place during treatment.

Springs as Active Components

Springs are integral to the active components of removable appliances. They are designed to exert specific forces on the teeth to achieve desired movements.

Components of a Spring

  • Wire Material: Springs are typically made from stainless steel or other resilient materials that can withstand repeated deformation.
  • Shape and Design: The design of the spring influences its force delivery and stability.

Classification of Springs

Springs can be classified based on various criteria:

1. Based on the Presence or Absence of Helix

  • Simple Springs: These springs do not have a helix and are typically used for straightforward tooth movements.
  • Compound Springs: These springs incorporate a helix, allowing for more complex movements and force applications.

2. Based on the Presence of Loop or Helix

  • Helical Springs: These springs feature a helical design, which provides a continuous force over a range of motion.
  • Looped Springs: These springs have a looped design, which can be used for specific tooth movements and adjustments.

3. Based on the Nature of Stability

  • Self-Supported Springs: Made from thicker gauge wire, these springs can support themselves and maintain their shape during use.
  • Supported Springs: Constructed from thinner gauge wire, these springs lack adequate stability and are often encased in a metallic tube to provide additional support.

Applications of Springs in Orthodontics

  • Space Maintenance: Springs can be used to maintain space in the dental arch during the eruption of permanent teeth.
  • Tooth Movement: Springs are employed to move teeth into desired positions, such as correcting crowding or aligning teeth.
  • Retention: Springs can also be used in retainers to maintain the position of teeth after orthodontic treatment.

SEQUENCE OF ERUPTION OF DECIDUOUS TEETH

Orthodontics

SEQUENCE OF ERUPTION OF DECIDUOUS TEETH

Upper/Lower   A B D C E 

SEQUENCE OF ERUPTION OF PERMAMENT TEETH 

Upper:   6 1 2 4 3 5 7           Lower:    6 1 2 3 4 5 7   
      
or       6 1 2 4 5 3 7              or  6 1 2 4 3 5 7 
 

ANTHROPOID SPACE / PRIMATE SPACE / SIMIEN’S SPACE  

The space mesial to upper deciduous canine and distal to lower deciduous  canine is characteristically found in primates and hence it is called primate space.  

INCISOR LIABILITY 

When the permanent central incisor erupt, these teeth use up specially all the spaces found in the normal dentition. With the eruption of permanent lateral incisor the space situation becomes tight. In the maxillary arch it is just enough to accommodate but in mandibular arch there is an average 1.6 mm less space available. This difference between the space present and space required is known as incisor liability. 
These conditions overcome by;  

      1. This is a transient condition and extra space comes from slight increase in arch width.   
      2. Slight labial positioning of central and lateral incisor. 
      3. Distal shift of permanent canine.        

      
LEE WAY SPACE (OF NANCE)  

The combined mesiodistal width of the permanent canines and pre molars is usually less that of the deciduous canines and molars. This space is 
called leeway space of Nance.     

Measurement of lee way space: 
 
Is greater in the mandibular arch than in the maxillary arch  It is about 1.8mm [0.9mm on each side of the arch] in the maxillary arch. 
And about 3.4mm [1.7 mm on side of the arch] in the mandibular arch. 
 
Importance:  

 This lee way space allows the mesial movement of lower molar there by correcting flush terminal plane.     
 LWS can be measure with the help of cephalometry.    

FLUSH TERMINAL PLANE (TERMINAL PLANE RELATIONSHIP) 

Mandibular 2nd deciduous molar is usually wider mesio-distally then the maxillary 2nd deciduous molar. This leads to the development of flush terminal plane which falls along the distal surface of upper and lower 2nd deciduous molar. This develops into class I molar relationship. 

Distal step relationship leads to class 2 relationship.
Mesial step relationship mostly leads to class 3 relationship.  

FEATURE OF IDEAL OCCLUSION IN PRIMARY DENTITION 

1. Spacing of anterior teeth. 
2. Primate space is present. 
3. Flush terminal plane is found. 
4. Almost vertical inclination of anterior teeth. 
5. Overbite and overjet varies.  

UGLY DUCKLING STAGE  

Definition:  
Stage of a transient or self correcting malocclusion is seen sometimes is called ugly duck ling stage. 
 
Occurring site: Maxillary incisor region 

Occuring age: 8-9 years of age.  

This situation is seen during the eruption of the permanent canines. As the developing p.c. they displace the roots of lateral incisor mesially this results is transmitting of the force on to the roots of the central incisors which also gets displaced mesially. A resultant distal divergence of the crowns of the two central incisors causes midline spacing.  

This portion of teeth at this stage is compared to that of ugly walk of the duckling and hence it is called Ugly Duckling Stage. 

Described by Broad bent. In this stage children tend to look ugly. Parents are often apprehensive during this stage and consult the dentist.  

Corrects by itself, when canines erupt and the pressure is transferred from the roots to the coronal area of the incisor.  
IMPORTANCE OF 1ST MOLAR
 
1. It is the key tooth to occlusion. 
2.  Angle’s classification is based on this tooth. 
3.  It is the tooth of choice for anchorage. 
4.  Supports occlusion in a vertical direction. 
5.  Loss of this tooth leads to migration of other tooth. 
6.  Helps in opening the bite.   

Biology of tooth movement
Orthodontics

Biology of tooth movement

1. Periodontal Ligament (PDL)

  • Structure: The PDL is a fibrous connective tissue that surrounds the roots of teeth and connects them to the alveolar bone. It contains various cells, including fibroblasts, osteoblasts, osteoclasts, and immune cells.
  • Function: The PDL plays a crucial role in transmitting forces applied to the teeth and facilitating tooth movement. It also provides sensory feedback and helps maintain the health of the surrounding tissues.

2. Mechanotransduction

  • Mechanotransduction is the process by which cells convert mechanical stimuli into biochemical signals. When a force is applied to a tooth, the PDL experiences compression and tension, leading to changes in cellular activity.
  • Cellular Response: The application of force causes deformation of the PDL, which activates mechanoreceptors on the surface of PDL cells. This activation triggers a cascade of biochemical events, including the release of signaling molecules such as cytokines and growth factors.

3. Bone Remodeling

  • Osteoclasts and Osteoblasts: The biological response to mechanical forces involves the coordinated activity of osteoclasts (cells that resorb bone) and osteoblasts (cells that form new bone).
    • Compression Side: On the side of the tooth where pressure is applied, osteoclasts are activated, leading to bone resorption. This allows the tooth to move in the direction of the applied force.
    • Tension Side: On the opposite side, where tension is created, osteoblasts are stimulated to deposit new bone, anchoring the tooth in its new position.
  • Bone Remodeling Cycle: The process of bone remodeling is dynamic and involves the continuous resorption and formation of bone. This cycle is influenced by the magnitude, duration, and direction of the applied forces.

4. Inflammatory Response

  • Role of Cytokines: The application of orthodontic forces induces a localized inflammatory response in the PDL. This response is characterized by the release of pro-inflammatory cytokines (e.g., interleukins, tumor necrosis factor-alpha) that promote the activity of osteoclasts and osteoblasts.
  • Healing Process: The inflammatory response is essential for initiating the remodeling process, but excessive inflammation can lead to complications such as root resorption or delayed tooth movement.

5. Vascular and Neural Changes

  • Blood Supply: The PDL has a rich blood supply that is crucial for delivering nutrients and oxygen to the cells involved in tooth movement. The application of forces can alter blood flow, affecting the metabolic activity of PDL cells.
  • Nerve Endings: The PDL contains sensory nerve endings that provide feedback about the position and movement of teeth. This sensory input is important for the regulation of forces applied during orthodontic treatment.

6. Factors Influencing Tooth Movement

  • Magnitude and Duration of Forces: The amount and duration of force applied to a tooth significantly influence the biological response and the rate of tooth movement. Light, continuous forces are generally more effective and less damaging than heavy, intermittent forces.
  • Age and Biological Variability: The biological response to orthodontic forces can vary with age, as younger individuals tend to have more active remodeling processes. Other factors, such as genetics, hormonal status, and overall health, can also affect tooth movement.
Catalan's Appliance
Orthodontics

Catalan's Appliance

Catalan's appliance, also known as the Catalan appliance or lower inclined bite plane, is an orthodontic device primarily used to correct anterior crossbites and manage dental arch relationships. It is particularly effective in growing children and adolescents, as it helps to guide the development of the dental arches and improve occlusion.

Indications for Use

  1. Anterior Crossbite:

    • The primary indication for Catalan's appliance is to correct anterior crossbites, where the upper front teeth are positioned behind the lower front teeth when the jaws are closed.

  2. Space Management:

    • It can be used to create space in the dental arch, especially when there is crowding or insufficient space for the eruption of permanent teeth.

  3. Guiding Eruption:

    • The appliance helps guide the eruption of the permanent teeth into a more favorable position, promoting proper alignment.

  4. Facilitating Growth:

    • It can assist in the growth of the maxilla and mandible, helping to achieve a more balanced facial profile.

Design and Features

  • Components:

    • The Catalan's appliance typically consists of:
      • Acrylic Base: A custom-fitted acrylic base that covers the lower anterior teeth.
      • Inclined Plane: An inclined plane is incorporated into the appliance, which helps to reposition the anterior teeth by providing a surface for the teeth to occlude against.
      • Retention Mechanism: The appliance is retained in the mouth using clasps or other anchorage methods to ensure stability during treatment.

  • Customization:

    • The appliance is custom-made for each patient based on their specific dental anatomy and treatment needs. This ensures a proper fit and effective function.

Mechanism of Action

  • Correction of Crossbite:

    • The inclined plane of the Catalan's appliance exerts forces on the anterior teeth, encouraging them to move into a more favorable position. This helps to correct the crossbite by allowing the maxillary incisors to move forward relative to the mandibular incisors.

  • Space Creation:

    • By repositioning the anterior teeth, the appliance can create additional space in the dental arch, facilitating the eruption of permanent teeth and improving overall alignment.

  • Guiding Eruption:

    • The appliance helps guide the eruption of the permanent teeth by maintaining proper arch form and preventing unwanted movements of the teeth.