The Ashley-Howe model analysis is a method used in orthodontics to assess the relationship of the dental arches and the position of the teeth, particularly in the context of planning orthodontic treatment. This analysis is particularly useful for evaluating the transverse dimension of the dental arches and understanding how the maxilla (upper jaw) and mandible (lower jaw) relate to each other.

Measurement Parameters:

• The analysis involves measuring specific distances and angles on dental casts or models. Key measurements may include:
  • Intercanine Width: The distance between the cusp tips of the canines.
  • Interpremolar Width: The distance between the cusp tips of the first premolars.
  • Intermolar Width: The distance between the cusp tips of the first molars.
• These measurements help in determining the transverse relationships of the dental arches.

Classification:

• The results of the Ashley-Howe analysis can help classify the dental arch relationships into different categories, such as:
  • Normal: Where the measurements fall within the expected range.
  • Narrowed: Indicating a constricted arch that may require expansion.
  • Widened: Indicating a broader arch that may need to be reduced or managed differently.

Clinical Application:

• The Ashley-Howe model analysis is particularly useful in treatment planning for orthodontic cases involving:
  • Crossbites: Where the upper teeth are positioned inside the lower teeth.
  • Crowding: Where there is insufficient space for teeth to erupt properly.
  • Expansion Needs: Determining if a patient requires arch expansion to correct transverse discrepancies.

Treatment Implications:

• Based on the analysis, orthodontists can decide on appropriate treatment modalities, which may include:
  • Orthodontic Appliances: Such as expanders to widen the arch.
  • Extraction: In cases of severe crowding or when space needs to be created.
  • Comprehensive Orthodontic Treatment: To align the teeth and improve occlusion.

Gingival group of fibers 
Principal fibers of the periodontal ligament rearranges themselves quite rapidly to the position in about 4 weeks.The supra-alveolar gingival fiber take as much as 40 weeks to rearrange around the new position and thus predispose to relapse.

Intermaxillary anchorage or Baker's Anchorage. This type of anchorage involves using elastics from one jaw to the other, in the form of either Class 2 elastics (moving upper teeth back) where lower molar teeth serve as anchors, or Class 3 elastics (moving lower teeth back) where upper molars serve as anchors.

Intramaxillary anchorage is also used in the form of E-chain, when elastics are used from the back molar teeth to the front teeth in the same jaw to move teeth back of the mouth.

The mandible is ossified in the fibrous membrane covering the outer surfaces of Meckel’s cartilages.

These cartilages form the cartilaginous bar of the mandibular arch, and are two in number, a right and a left.

Ossification takes place in the membrane covering the outer surface of the ventral end of Meckel’s cartilage , and each half of the bone is formed from a single center which appears, near the mental foramen, about the sixth week of fetal life.

By the tenth week the portion of Meckel’s cartilage which lies below and behind the incisor teeth is surrounded and invaded by the membrane bone

· Linder Harth index: This analysis is very similar to Pont’s analysis except that a new formula has been proposed to determine the calculated premolar and molar value. 

· Korkhaus analysis: This analysis is also very similar to Pont’s analysis it makes use of Linder Harth’s formula to determine the ideal arch width in the premolar and molar region.
 In addition this analysis utilizes a measurement made from the midpoint of the inter-premolar line to a point in between the two maxillary incisors. 
 
· Bolton’s analysis: The Bolton’s analysis helps in determining disproportion in size between maxillary and mandibular teeth. 

1. Angle Classification:

   • The Angle classification system, developed by Edward Angle, is a widely used method for categorizing malocclusions based on the relationship of the first molars and the canines.

2. Class III Malocclusion:

   • In Angle Class III malocclusion, the lower first molar is positioned more mesially (toward the midline) relative to the upper first molar. This means that when the first molars are in occlusion, the lower first molar is ahead of the upper first molar.

3. Clinical Implications:

   • Class III malocclusion is often associated with a prognathic mandible (where the lower jaw is positioned forward) or a retruded maxilla (where the upper jaw is positioned backward). This can lead to various functional and aesthetic concerns, including difficulties with biting and chewing, as well as facial profile changes.

Elgiloy (Cobalt-Chromium) alloy is supplied in a softer state and can be heat hardened.

After hardening heat treatment, the softest elgiloy becomes equivalent to regular stainless steel.