infancy-ID 185284.txt

• -Malocclusion publiation 1890s
• -1st clear definition of normal occlusion
• -Upper 1st molars are the key
• -MB cusp of upper 1st molar occludes in buccal groove of lower 1st

Molars normal, but malposed teeth

Lower molar distally positioned relative to the upper

Lower molar mesially positioned relative to the upper

• 1. Hypertrophy- increase in cell size
• 2. Hyperplasia- increase in cell number
• 3. Secretion of extracellular material- tissue mass increases

• 1. Occurs throughout the tissue
• 2. Ocurs in Soft tissues
• 3. occurs in uncalcified cartilage

• 1. Occurs only on tissue surfaces
• 2. Occurs in hard tissues
• 3. Occurs in calcified tissues

• 1. No structural precursor
• 2. Secretion of bone matrix directly within connective tissues
• 3. In cranial vault, maxilla, and mandible

• 1. Cartilaginous precursor
• 2. Replacement of cartilage with centers of ossification
• 3. In axial and appendicular skeleton, cranial base

• -The chondrocranium begins to develop, from the nasal capsule to the occipital region
• -Before ossification, chondrocranium can undergo interstitial growth. Afterwards, bone is only added by apposition

• The cranial vault, maxilla, and mandible arise from intramembranous ossification
• -additional bone can only be added by apposition

Interstitial activity for bone can only occur in the soft tissues of the periosteum

• The mandible ossifies independently and adjacent to Meckel's cartilage. 
• -remnants of Meckel's form two middle ear ossicles
• -Meckel's perichondrium becomes the sphenomandibular ligament

• The condylar cartilage arises independently as secondary cartilage.
• -it is initially separated from the body of the mandible, and fuses during fetal life
• -increase in tissue mass at the condyle proceeds via the cartilaginous precursor, but additional bulk increase is appositional

Both endochondral and intramembranous ossification contribute to the origin of the mandible.

• Remodeling is the balance of apposition and resorption
• -think of the sand dune relative to desert floor

Relocation is movement of a component part of boneas a result of remodeling

• Displacement/translation is the movement of a whole bone as a response to remodeling
• -think of the balloons moving away from each other

• The cranial base is endochondral in origin
• -up to young adulthood, cartilage layer between each bone of the cranial base is preserved, allowing growth between the bones via a cartilaginous precursor
• -The cranial base bones increase in mass through ossification and proliferation of cartilage in the synchondroses

• No. All of its growth is in the sutures or the periosteum
• -in the sutures, there is apposition in an upward and backward direction.
• -this causes downward and forward displacement of the maxilla

• Resorptive remodeling occurs on the anterior maxillary surface.
• -apposition occurs on the posterior surfaces, and resorption occurs anteriorly to prevent the maxilla from moving forward too far

• The palate remodels with apposition on the palatal surface and resorption on the nasal surface.
• -the result is a net downward translation

• 1.Apposition of bone at the sutures (downward/forward displacement)
• 2. Apposition of bone at maxillary tuberosity (increase arch depth)
• 3. Apposition of bone at the palatal surface (relocate palate downward)

• 1.Resorption at the anterior maxillary surface
• -maintains position of the anterior surface
• 2. Resorption of the nasal cavity floor
• -relocates the palate downward

• 1. Large resorption on the anterior surface of the ramus
• 2. Apposition on the posterior surface of the ramus
• 3. Upward/backward increase in condylar mass through endochondral-like remodeling process

The growth in mass in the mandible is predominantly upward and backward, but the mandible is displaced downward and forward due to the consistent articulation of the condyle with the glenoid fossa

• 1. Endochondral bone growth at the condyle
• -displaces mandible downward and forward
• 2. Apposition at the posterior border, resorption of anterior border of ramus
• -relocates ramus posteriorly
• -displaces mandible downward and forward