Transcript
GROWTH & DEVELOPMENT
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DR. KAPIL SAROHABDS, MDS
ORTHODONTICS AND DENTOFACIAL ORTHOPAEDICS
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Introduction :
• To know the normal growth and how it occurs.
• Difference between normal and abnormal growth.
• Timing of growth.
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Definition of Growth
• “Growth usually refers to an increase in size
and number” – Profitt
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Definition of Development“Development is a progress towards maturity” – Todd
“Development refers to all naturally occurring progressive, unidirectional, sequential changes in the life of an individual from it’s existence as a single cell to it’s elaboration as a multifunctional unit terminating in death” – Moyers
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Correlation between Growth & Development
• Growth is basically anatomic phenomenon and quantitative in nature
• Development is basically physiologic phenomenon and qualitative in nature
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Normal features of Growth & Development
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Differential Growth• Not all tissue systems of the body grow at the same rate• Scammon’s curvesDepicting differentialgrowth
- Neural tissue growth is completed by 6 – 7 years
- Lymphoid tissue growth is completed in late childhood and growth of genital tissues accelerates at the same time.
- General Body tissue follows S-Shaped curve.
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PROPORTION– Changes in overall body proportions – Changes in proportion of cranio-facial region
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Timing of Growth
• Largely under genetic control• Altered by environment• Sex related difference in timing of events
– Growth spurts– Dental calcification– Ossification of carpal bones
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Growth spurts
• Defined as periods of growth acceleration
• Sex-linked
– Normal spurts are• Infantile spurt – at 3 years age
• Juvenile spurt – 7-8 years (females); 8-10 years (males)
• Pubertal spurt – 10-11 years(females); 14-16 years (males)
• Growth modulation can be done
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Mechanisms of bone growth
• Modeling
• Remodeling
• Displacement
• Combination of remodeling & displacement
• Rotation
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MODELING
• Bone modeling involves
independent sites of resorption and
formation that change the size and
shape of a bone.
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Remodelling• A process involving deposition and
resorption occuring on opposite ends
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Functions of Remodelling1. Progressively change the size of whole bone
2. Sequentially relocate each component of the whole bone
3. Progressively change the shape of the bone to accommodate its various functions
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Displacement
• Refers to a shift in the position of the bone
• Two types– Primary displacement– Secondary displacement
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Combination of remodelling & displacement
• Both these mechanisms operate together and cause enlargement and movement of the bone
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Rotation• According to Enlow , growth rotation is due to
diagonally placed areas of deposition and resorption
• Two types– Remodelling rotations– Displacement rotations
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V’ - Principle• Deposition occurs on the inner side and
resorption on the outerside of the bones causing enlargement and displacement.
• The displacement is towards wide end of ‘V’• Examples
– Neck of the condyle– Palatal process of maxilla
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