Dr .Imtiaz Ahmed B.D.S , F.C.P.S , M-Orth (Edin)

HEAD OF ORTHODONTIC DEPARTMENTSUPERVISOR , FCPS,MDS POST GRADUATE PROGRAMDIKHIOUSDOW UNIVERSITY OF HEALTH SCIENCES

Why do we assess growth?

To determine optimum time for treatment (growth modification and surgery)

to determine the amount of growth left to determine type of growth

Principles of Tissue Growth

Hypertrophy hyperplasia increased production of

extracellular matrix (cell independent)

Bone, muscle and soft tissue growth All are dependent on each other to some

degree Growth of mineralized tissues = can be done

in the surface only (periosteum)= surface apposition of bone

Growth of the soft and cartilaginous tissues = interstitial growth

Growth of Cartilage/ Endochondral Ossification

Long bones Epiphyseal plate

contains dividing cartilaginous cells

Rate of growth and maturation of cells need to be equal for growth to occur

Proliferating cartilage

Epiphyseal plate

Growth of the Maxilla

Growth of maxilla are produced by two basic mechanism

Passive displacement : created by growth of cranial base that pushes the maxilla forward

Active growth : growth itself occurs in maxilla.

Growth of the Maxilla

Remodeling of the palatal vault moves it in the same direction as it is being translated

bone is removed from the floor of the nose and added to the roof of the mouth

Growth of the Maxilla

On the anterior surface, bone is removed, partially cancelling the forward translation. As the vault moves downward, the same process of bone remodeling also widens it.

Growth of the Maxilla

Growth of the surrounding soft tissues translates the maxilla downward and forward, opening spaces in the sutures where bone is added.

Growth of the Maxilla

Midpalatal suture is opened until teenage years. Apposition of bone in the molar area accounts

for space for the third molars.

Growth of the Maxilla

Summary:growth of the maxilla

occurs in 2 ways: by apposition of bone in

the sutures that connect the maxilla to the cranial base

by surface remodeling.

Growth of the Mandible

Remodeling is done by resorption in the anterior part of the ramus and deposition in the posterior part of the ramus

Gonial angle changes after little muscle activity.

Transverse dimension is mainly due to growth at posterior border in an expanding V pattern.

Growth of the Mandible

Overall growth direction results in a downward and forward displacement with most of growth occurring in the ramus.

The two rami also diverge outward from below to above so that additive growth at coronoid notch , coronoid process &condyle also increses the superior inter-ramus dimension.

Alveolar process of mandible grows upward & outward on an expanding arc. This permit dental arc to accommodate the larger permanent teeth.

Growth of the Mandible

Mandibular symphysis is closed by age of 1 year. Late mandibular growth: can occur in the late teenage years or adulthood most often seen in asians and males can cause incisor crowding when there is a tight

occlusion (overbite/overjet)

When things go wrong

Congenital craniofacial malformations: cleft lip/palate, syndromes (Apert, Crouzon, etc..), craniosynostosis

Non-syndromic craniosynostosis Trauma Ankylosis Juvenile rheumatoid arthritis

When things go wrong

Blow to one side of the mandible may fracture the condylar process on the opposite side

pull of the lateral pterygoid muscle distracts the condylar fragment including all the cartilage = resorption occurs

Trauma

ROTATIONAL CHANGES OF JAWS

ROTATIONAL CHANGES OF JAWS

MANDIBULAR ROTATION WITH RESPECT WITH CRANIAL BASE

NORMAL MANDIBULAR ROTATION PATTERN

JAW ROTATION IN LONG FACE PATTERN

JAW ROTATION IN SHORT FACE PATTERN

JAW ROTATION IN MAXILLA