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.   

Camouflage in orthodontics refers to the strategic use of orthodontic treatment to mask or disguise underlying skeletal discrepancies, particularly in cases where surgical intervention may not be feasible or desired by the patient. This approach aims to improve dental alignment and occlusion while minimizing the appearance of skeletal issues, such as Class II or Class III malocclusions.

Key Concepts of Camouflage in Orthodontics

1. Objective:

   • The primary goal of camouflage is to create a more aesthetically pleasing smile and functional occlusion without addressing the underlying skeletal relationship directly. This is particularly useful for patients who may not want to undergo orthognathic surgery.

2. Indications:

   • Camouflage is often indicated for:
     • Class II Malocclusion: Where the lower jaw is positioned further back than the upper jaw.
     • Class III Malocclusion: Where the lower jaw is positioned further forward than the upper jaw.
     • Mild to Moderate Skeletal Discrepancies: Cases where the skeletal relationship is not severe enough to warrant surgical correction.

3. Mechanisms:

   • Tooth Movement: Camouflage typically involves moving the teeth into positions that improve the occlusion and facial aesthetics. This may include:
     • Proclination of Upper Incisors: In Class II cases, the upper incisors may be tilted forward to improve the appearance of the bite.
     • Retroclination of Lower Incisors: In Class III cases, the lower incisors may be tilted backward to help achieve a better occlusal relationship.
   • Use of Elastics: Orthodontic elastics can be employed to help correct the bite and improve the overall alignment of the teeth.

4. Treatment Planning:

   • A thorough assessment of the patient's dental and skeletal relationships is essential. This includes:
     • Cephalometric Analysis: To evaluate the skeletal relationships and determine the extent of camouflage needed.
     • Clinical Examination: To assess the dental alignment, occlusion, and any functional issues.
     • Patient Preferences: Understanding the patient's goals and preferences regarding treatment options.

Advantages of Camouflage

1. Non-Surgical Option: Camouflage provides a way to improve dental alignment and aesthetics without the need for surgical intervention, making it appealing to many patients.
2. Shorter Treatment Time: In some cases, camouflage can lead to shorter treatment times compared to surgical options.
3. Improved Aesthetics: By enhancing the appearance of the smile and occlusion, camouflage can significantly boost a patient's confidence and satisfaction.

Limitations of Camouflage

1. Not a Permanent Solution: While camouflage can improve aesthetics and function, it does not address the underlying skeletal discrepancies, which may lead to long-term issues.
2. Potential for Relapse: Without proper retention, there is a risk that the teeth may shift back to their original positions after treatment.
3. Functional Complications: In some cases, camouflage may not fully resolve functional issues related to the bite, leading to potential discomfort or wear on the teeth.

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.

Types of Forces in Tooth Movement

1. Light Forces:

   •  Forces that are gentle and continuous, typically in the range of 50-100 grams.
   • Effect: Light forces are ideal for orthodontic tooth movement as they promote biological responses without causing damage to the periodontal ligament or surrounding bone.
   • Examples: Springs, elastics, and aligners.

2. Heavy Forces:

   •  Forces that exceed the threshold of light forces, often greater than 200 grams.
   • Effect: Heavy forces can lead to rapid tooth movement but may cause damage to the periodontal tissues, including root resorption and loss of anchorage.
   • Examples: Certain types of fixed appliances or excessive activation of springs.

3. Continuous Forces:

   •  Forces that are applied consistently over time.
   • Effect: Continuous forces are essential for effective tooth movement, as they maintain the pressure-tension balance in the periodontal ligament.
   • Examples: Archwires in fixed appliances or continuous elastic bands.

4. Intermittent Forces:

   •  Forces that are applied in a pulsed or periodic manner.
   • Effect: Intermittent forces can be effective in certain situations but may not provide the same level of predictability in tooth movement as continuous forces.
   • Examples: Temporary anchorage devices (TADs) that are activated periodically.

5. Directional Forces:

   •  Forces applied in specific directions to achieve desired tooth movement.
   • Effect: The direction of the force is critical in determining the type of movement (e.g., tipping, bodily movement, rotation) that occurs.
   • Examples: Using springs or elastics to move teeth mesially, distally, buccally, or lingually.

Headgear is an extraoral orthodontic appliance used to correct dental and skeletal discrepancies, particularly in growing patients. It is designed to apply forces to the teeth and jaws to achieve specific orthodontic goals, such as correcting overbites, underbites, and crossbites, as well as guiding the growth of the maxilla (upper jaw) and mandible (lower jaw). Below is an overview of headgear, its types, mechanisms of action, indications, advantages, and limitations.

Types of Headgear

1. Class II Headgear:

   • Description: This type is used primarily to correct Class II malocclusions, where the upper teeth are positioned too far forward relative to the lower teeth.
   • Mechanism: It typically consists of a facebow that attaches to the maxillary molars and is anchored to a neck strap or a forehead strap. The appliance applies a backward force to the maxilla, helping to reposition it and/or retract the upper incisors.

2. Class III Headgear:

   • Description: Used to correct Class III malocclusions, where the lower teeth are positioned too far forward relative to the upper teeth.
   • Mechanism: This type of headgear may use a reverse-pull face mask that applies forward and upward forces to the maxilla, encouraging its growth and improving the relationship between the upper and lower jaws.

3. Cervical Headgear:

   • Description: This type is used to control the growth of the maxilla and is often used in conjunction with other orthodontic appliances.
   • Mechanism: It consists of a neck strap that connects to a facebow, applying forces to the maxilla to restrict its forward growth while allowing the mandible to grow.

4. High-Pull Headgear:

   • Description: This type is used to control the vertical growth of the maxilla and is often used in cases with deep overbites.
   • Mechanism: It features a head strap that connects to the facebow and applies upward and backward forces to the maxilla.

Mechanism of Action

• Force Application: Headgear applies extraoral forces to the teeth and jaws, influencing their position and growth. The forces can be directed to:
  • Restrict maxillary growth: In Class II cases, headgear can help prevent the maxilla from growing too far forward.
  • Promote maxillary growth: In Class III cases, headgear can encourage forward growth of the maxilla.
  • Reposition teeth: By applying forces to the molars, headgear can help align the dental arches and improve occlusion.

Indications for Use

• Class II Malocclusion: To correct overbites and improve the relationship between the upper and lower teeth.
• Class III Malocclusion: To promote the growth of the maxilla and improve the occlusal relationship.
• Crowding: To create space for teeth by retracting the upper incisors.
• Facial Aesthetics: To improve the overall facial profile and aesthetics by modifying jaw relationships.

Advantages of Headgear

1. Non-Surgical Option: Provides a way to correct skeletal discrepancies without the need for surgical intervention.
2. Effective for Growth Modification: Particularly useful in growing patients, as it can influence the growth of the jaws.
3. Improves Aesthetics: Can enhance facial aesthetics by correcting jaw relationships and improving the smile.

Limitations of Headgear

1. Patient Compliance: The effectiveness of headgear relies heavily on patient compliance. Patients must wear the appliance as prescribed (often 12-14 hours a day) for optimal results.
2. Discomfort: Patients may experience discomfort or soreness when first using headgear, which can affect compliance.
3. Adjustment Period: It may take time for patients to adjust to wearing headgear, and they may need guidance on how to use it properly.
4. Limited Effectiveness in Adults: While headgear is effective in growing patients, its effectiveness may be limited in adults due to the maturity of the skeletal structures.

Edgewise Technique

• The Edgewise Technique is based on the use of brackets that have a slot (or edge) into which an archwire is placed. This design allows for precise control of tooth movement in multiple dimensions (buccal-lingual, mesial-distal, and vertical).

1. Mechanics:

   • The technique utilizes a combination of archwires, brackets, and ligatures to apply forces to the teeth. The archwire is engaged in the bracket slots, and adjustments to the wire can be made to achieve desired tooth movements.

Components of the Edgewise Technique

1. Brackets:

   • Edgewise Brackets: These brackets have a vertical slot that allows the archwire to be positioned at different angles, providing control over the movement of the teeth. They can be made of metal or ceramic materials.
   • Slot Size: Common slot sizes include 0.022 inches and 0.018 inches, with the choice depending on the specific treatment goals.

2. Archwires:

   • Archwires are made from various materials (stainless steel, nickel-titanium, etc.) and come in different shapes and sizes. They provide the primary force for tooth movement and can be adjusted throughout treatment to achieve desired results.

3. Ligatures:

   • Ligatures are used to hold the archwire in place within the bracket slots. They can be elastic or metal, and their selection can affect the friction and force applied to the teeth.

4. Auxiliary Components:

   • Additional components such as springs, elastics, and separators may be used to enhance the mechanics of the Edgewise system and facilitate specific tooth movements.

Advantages of the Edgewise Technique

1. Precision:

   • The Edgewise Technique allows for precise control of tooth movement in all three dimensions, making it suitable for complex cases.

2. Versatility:

   • It can be used to treat a wide range of malocclusions, including crowding, spacing, overbites, underbites, and crossbites.

3. Effective Force Application:

   • The design of the brackets and the use of archwires enable the application of light, continuous forces, which are more effective and comfortable for patients.

4. Predictable Outcomes:

   • The technique is based on established principles of biomechanics, leading to predictable and consistent treatment outcomes.

Applications of the Edgewise Technique

• Comprehensive Orthodontic Treatment: The Edgewise Technique is commonly used for full orthodontic treatment in both children and adults.
• Complex Malocclusions: It is particularly effective for treating complex cases that require detailed tooth movement and alignment.
• Retention: After active treatment, the Edgewise system can be used in conjunction with retainers to maintain the corrected positions of the teeth.