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NEET MDS Synopsis - Lecture Notes
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📖 Orthodontics

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Late mandibular growth
Orthodontics

Late mandibular growth refers to the continued development and growth of the mandible (lower jaw) that occurs after the typical growth spurts associated with childhood and adolescence. While most of the significant growth of the mandible occurs during these early years, some individuals may experience additional growth in their late teens or early adulthood. Understanding the factors influencing late mandibular growth, its implications, and its relevance in orthodontics and dentistry is essential.

Factors Influencing Late Mandibular Growth

  1. Genetics:

    • Genetic factors play a significant role in determining the timing and extent of mandibular growth. Family history can provide insights into an individual's growth patterns.

  2. Hormonal Changes:

    • Hormonal fluctuations, particularly during puberty, can influence growth. Growth hormone, sex hormones (estrogen and testosterone), and other endocrine factors can affect the growth of the mandible.

  3. Functional Forces:

    • The forces exerted by the muscles of mastication, as well as functional activities such as chewing and speaking, can influence the growth and development of the mandible.

  4. Environmental Factors:

    • Nutritional status, overall health, and lifestyle factors can impact growth. Adequate nutrition is essential for optimal skeletal development.

  5. Orthodontic Treatment:

    • Orthodontic interventions can influence mandibular growth patterns. For example, the use of functional appliances may encourage forward growth of the mandible in growing patients.

Clinical Implications of Late Mandibular Growth

  1. Changes in Occlusion:

    • Late mandibular growth can lead to changes in the occlusal relationship between the upper and lower teeth. This may result in the development of malocclusions or changes in existing malocclusions.

  2. Facial Aesthetics:

    • Continued growth of the mandible can affect facial aesthetics, including the profile and overall balance of the face. This may be particularly relevant in individuals with a retrognathic (recessed) mandible or those seeking cosmetic improvements.

  3. Orthodontic Treatment Planning:

    • Understanding the potential for late mandibular growth is crucial for orthodontists when planning treatment. It may influence the timing of interventions and the choice of appliances used to guide growth.

  4. Surgical Considerations:

    • In some cases, late mandibular growth may necessitate surgical intervention, particularly in adults with significant skeletal discrepancies. Orthognathic surgery may be considered to correct jaw relationships and improve function and aesthetics.

Monitoring Late Mandibular Growth

  1. Clinical Evaluation:

    • Regular clinical evaluations, including assessments of occlusion, facial symmetry, and growth patterns, are essential for monitoring late mandibular growth.

  2. Radiographic Analysis:

    • Cephalometric radiographs can be used to assess changes in mandibular growth and its relationship to the craniofacial complex. This information can guide treatment decisions.

  3. Patient History:

    • Gathering a comprehensive patient history, including growth patterns and any previous orthodontic treatment, can provide valuable insights into late mandibular growth.
Ashley Howes Analysis of Tooth Crowding
Orthodontics

Ashley Howe’s Analysis of Tooth Crowding

Introduction

Today, we will discuss Ashley Howe’s analysis, which provides valuable insights into the causes of tooth crowding and the relationship between dental arch dimensions and tooth size. Howe’s work emphasizes the importance of arch width over arch length in understanding dental crowding.

Key Concepts

Tooth Crowding

  • Definition: Tooth crowding refers to the lack of space in the dental arch for all teeth to fit properly.
  • Howe’s Perspective: Howe posited that tooth crowding is primarily due to a deficiency in arch width rather than arch length.

Relationship Between Tooth Size and Arch Width

  • Howe identified a significant relationship between the total mesiodistal diameter of teeth anterior to the second permanent molar and the width of the dental arch in the first premolar region. This relationship is crucial for understanding how tooth size can impact arch dimensions and overall dental alignment.

Procedure for Analysis

To conduct Ashley Howe’s analysis, the following measurements must be obtained:

  1. Percentage of PMD to TTM
    PMD X 100
          TTM
  2. Percentage of PMBAW to TTM
    PMBAW X 100
        TTM

  3. Percentage of BAL to TTM: [ \text{Percentage of BAL} = \left( \frac{\text{BAL}}{\text{TTM}} \right) \times 100 ]

Where:

  • PMD = Total mesiodistal diameter of teeth anterior to the second permanent molar.
  • PMBAW = Premolar basal arch width.
  • BAL = Basal arch length.
  • TTM = Total tooth mesiodistal measurement.

Inferences from the Analysis

The results of the measurements can lead to several important inferences regarding treatment options for tooth crowding:

  1. If PMBAW > PMD:

    • This indicates that the basal arch is sufficient to allow for the expansion of the premolars. In this case, expansion may be a viable treatment option.

  2. If PMD > PMBAW:

    • This scenario can lead to three possible treatment options:
      1. Contraindicated for Expansion: Expansion may not be advisable.
      2. Move Teeth Distally: Consideration for distal movement of teeth to create space.
      3. Extract Some Teeth: Extraction may be necessary to alleviate crowding.

  3. If PMBAW X 100 / TTM:

    • Less than 37%: Extraction is likely required.
    • 44%: This is considered an ideal case where extraction is not necessary.
    • Between 37% and 44%: This is a borderline case where extraction may or may not be required, necessitating further evaluation.

BONES OF THE SKULL 

Orthodontics

BONES OF THE SKULL  

A) Bones of the cranial base: 

    A)  Fontal  (1) 
    B)  Ethmoid  (1)      
    C)  Sphenoid (1)  
    D)  Occipital  (1)
    
B) Bones of the cranial vault: 
 
       1. Parietal (2)          
       2. Temporal (2) 
       
C) Bones of the face:
  
        Maxilla (2) 
        Mandible (1) 
        Nasal bone (2) 
        Lacrimal bone (2) 
        Zygomatic bone (2) 
        Palatine bone(2) 
        Infra nasal concha (2)  

FUSION BETWEEN BONES 

1. Syndesmosis: Membranous or ligamentus eg. Sutural point. 
2. Synostosis: Bony union eg. symphysis menti. 
3. Synchondrosis: Cartilaginous eg. sphenoccipital, spheno-ethmoidal. 

GROWTH OF THE SKULL: 
          A)     Cranium: 1. Base   2. Vault   
          B)     Face:  1. Upper face 2.Lower face  

CRANIAL BASE: 

Cranial base grows at different cartilaginous suture. The cranial base may be divided into 3 areas.  

1. The posterior part which extends from the occiput to the salatercica. The most important growth site spheno-occipital synchondrosis is situated here. It is active throughout the growing period and does not close until early adult life.  

2. The middle portion extends from sella to foramen cecum and the sutural growth spheno-ethmoidal synchondrosis is situated here. The exact time of closing is not known but probably at the age of 7 years. 

3. The anterior part is from foramen cecum and grows by surface deposition of bone in the frontal region and simultaneous development of frontal sinus. 

CRANIAL VAULT:  

The cranial vault grows as the brain grows. It is accelerated at infant. The growth is complete by 90% by the end of 5th year. At birth the sutures are wide sufficiently and become approximated during the 1st 2 years of life. 

The development and extension of frontal sinus takes place particularly at the age of puberty and there is deposition of bone on the surfaces of cranial bone. 
 

Frankel appliance
Orthodontics

Frankel appliance is a functional orthodontic device designed to guide facial growth and correct malocclusions. There are four main types: Frankel I (for Class I and Class II Division 1 malocclusions), Frankel II (for Class II Division 2), Frankel III (for Class III malocclusions), and Frankel IV (for specific cases requiring unique adjustments). Each type addresses different dental and skeletal relationships.

The Frankel appliance is a removable orthodontic device that plays a crucial role in the treatment of various malocclusions. It is designed to influence the growth of the jaw and dental arches by modifying muscle function and promoting proper alignment of teeth.

Types of Frankel Appliances

  1. Frankel I:

    • Indications: Primarily used for Class I and Class II Division 1 malocclusions.
    • Function: Helps in correcting overjet and improving dental alignment.

  2. Frankel II:

    • Indications: Specifically designed for Class II Division 2 malocclusions.
    • Function: Aims to reposition the maxilla and improve the relationship between the upper and lower teeth.

  3. Frankel III:

    • Indications: Used for Class III malocclusions.
    • Function: Encourages forward positioning of the maxilla and helps in correcting the skeletal relationship.

  4. Frankel IV:

    • Indications: Suitable for open bites and bimaxillary protrusions.
    • Function: Focuses on creating space and improving the occlusion by addressing specific dental and skeletal issues.

Key Features of Frankel Appliances

  • Myofunctional Design: The appliance is designed to utilize the forces generated by muscle function to guide the growth of the dental arches.

  • Removable: Patients can take the appliance out for cleaning and during meals, which enhances comfort and hygiene.

  • Custom Fit: Each appliance is tailored to the individual patient's dental anatomy, ensuring effective treatment.

Treatment Goals

  • Facial Balance: The primary goal of using a Frankel appliance is to achieve facial harmony and balance by correcting malocclusions.

  • Functional Improvement: It promotes the establishment of normal muscle function, which is essential for long-term dental health.

  • Arch Development: The appliance aids in the development of the dental arches, providing adequate space for the eruption of permanent teeth.