Type of primary occlusion

Mesial step- Distal surface of the lower second molar is more mesial to that of the upper second molar.

Distal step- Distal surface of the lower second molar is more distal to that of the upper second molar.

Step facing mesial side

Step facing distal side

M D

M D

Flush terminal plane- Distal surface of the upper and lower second molar are in a straight plane (flush) and therefore situated on the same vertical plane.

Absence of a step.

M D

Types of primary canine relation

The cusp tip of the maxillary canine is in the embrasure between the mandibular canine and the mandibular first molar

The cusp tip of the maxillary canine is in the embrasure between the mandibular canine and the mandibular lateral incisorMD

MD

The maxillary canine is distal to the embrasure between the mandibular canine and the mandibular first molar

An in between status can occur in the canine relationship in the primary and permanent dentitions; this is referred to an end-to-end relationships

MD

Carey’s analysis

• Used to assess the difference between the space available for the teeth in the dental arch and the space required for accommodating the teeth.

• If the space required is less than the space available , spacing results.

• If the space required is more than the space available , crowding results.

Method

1. Determination of arch length - measured using a 0.012 inch soft round brass wire - The wire is adapted to the model of the mandibular

arch so that one end engages first permanent lower molar near the marginal ridge.

- The wire is next passed over the buccal cusps of the premolars , then over the normal cuspal position of the cuspid , then over the anterior teeth at ridge center and finally around the same course on the opposite side, ending in mesio buccal line angle of lower first permanent molar of the other side.

• The wire is cut at this point and straightened and the length is recorded.

- in case of proclined anteriors, the brass wire is passed along the cingulum of the anterior teeth

- in case of retroclined anteriors, the brass wire is passed labial to the anterior teeth

- in case of well aligned anterior teeth, the wire is passed over the incisal edges of the anterior teeth.

Determination of arch width/ total tooth material (TTM)

• Determined by measuring the mesio-distal width of teeth anterior to the first permanent molars (incisors, canines and premolars) at the maximum contour using bow divider

• Determination of the discrepancy refers to the difference between the arch length and total tooth material

Inference

• Non extraction case if the discrepancy is 2.5 mm or less, it indicates minimal tooth

material excess, which can be managed by proximal stripping

• Extraction of second premolar if the discrepancy is 2.5-5mm, second premolar may need to

be extracted

• Extraction of first molar if the discrepancy is more than 5mm then extraction of first

molar is advised.

Pont’s analysis

• Pont in 1909 proposed that the measurement of four maxillary incisors will automatically establish the width of arch in the premolar and molar regions.

• It helps in- - determining whether the dental arch is narrow or

wide - determining the need for the lateral arch expansion - determining how much expansion is possible at the

premolar and molar region

Determination of sum of incisors• Mesio distal width of 4 maxillary incisors is measured

and values summed up• This is called sum of incisors (SI).

Determination of measured premolar value(MPV)• width of arch in the premolar region from the distal

pit of one upper first premolar to the distal pit of the first premolar on the opposite side is measured- Measured Premolar Value

• Determination of measured molar value(MMV) - width of the arch in the molar region from the

mesial pit of one upper first molar to the mesial pit of the opposite side first molar is measured – Measured Molar Value

• Determination of the calculated premolar value (CPV)

Expected arch width = SI * 100 / 80

• Determination of calculated molar value(CMV) Expected arch width = SI * 100/ 64

• Inference if the measured value is less than the calculated

value, then expansion is indicated.

Amount of expansion in premolar region = CPV – MPV

Amount of expansion in molar region = CMV – MMV

Ashley Howe’s analysis• Determination of Total Tooth Material (TTM) - mesio distal width of all the teeth mesial to the second

permanent molar is measured with the help of bow divider and all the values are summed up.

• Determination of Premolar dimension (PMD) - determined from the tip of buccal cusp of left first permanent

premolar to the right first permanent premolar in the same arch.

• Determination of Premolar Basal Arch Width (PMBAW) - measured from left canine fossa to the right canine fossa

If the canine fossa is not clearly distinguishable , the measurements are made from a point that is 8mm apical the crest of the interdental papilla distal to the canine.

PMBAW % = PMBAW * 100/ TTM

• Inference - expansion of an arch is possible if PMBAW > PMD

- expansion is not possible, if PMBAW is less than PMD

PMBAW% Inference

44 or more Treatment by non extraction

37-44 Borderline cases

37 or less Need for extraction

Linder Hath Index• Modification of Pont’s analysis

Formula for CPV (calculated premolar value)

CPV= SI * 100/85

Formula for CMV (calculated molar value)

CMV = SI * 100/64

Korkhaus Analysis

• Similar to pont’s analysis & uses Linder Hath’s formula to determine the ideal arch width in premolar and molar regions.

• Uses an additional parameter, a measurement made from the midpoint of the interpremolar line to the point between the two maxillary central incisors

• Korkhaus advocated that for a given width of upper incisors, a specific value of the distance between the midpoint of interpremolar line to the point between two maxillary incisors should exist.

• An increase in this measurement is seen in case of upper anterior proclination and this value is decreased in case of anterior retroclination.