Pedodontics Nikhil Marwah, Vijay Prabha K
INDEX
×
Chapter Notes

Save Clear


Craniofacial Growth and DevelopmentCHAPTER 1

 
POSTNATAL GROWTH OF MAXILLA
zoom view
Fig. 1.1: Primary displacement
Primary displacement—Growth at maxillary tuberosity thus maxilla is pushed anteriorly.2
zoom view
Fig. 1.2: Secondary displacement
Secondary displacement—Growth of cranial base pushes the maxilla in downward and forward direction.
zoom view
Fig. 1.3: Remodeling
Surface remodeling
+ Deposition
− Resorption3
 
POSTNATAL GROWTH OF MANDIBLE
zoom view
Fig. 1.4: Ramal growth
Ramus—Resorption on anterior part and deposition on posterior.
zoom view
Fig. 1.5: Growth at body
Body of mandible—Lengthens posteriorly as former ramal bone changes into body.4
zoom view
Fig. 1.6: Tuberosity growth
Lingual tuberosity—Deposition on posterior facing surface.
zoom view
Fig. 1.7: Enlow's V. principle
Angle of mandible—Lingual: resorption on posterio-inferior aspect, deposition on antero-superior aspect.
Buccal: resorption on antero-superior aspect, deposition on posterio-superior aspect.5
zoom view
Fig. 1.8: Condylar growth
Condyle—Secondary bone growth6
 
CEPHALOCAUDAL GRADIENT OF GROWTH
zoom view
Fig. 1.9: Cephalocaudal growth
In fetal life at about 1/3rd month of intrauterine development, the head takes up almost 50 percent of total body length. The cranium is large relative to face and represents more than half of total head, whereas the limbs are still rudimentary and the trunk is underdeveloped. By the time of birth, the trunk and limbs have grown faster than head and face. So that the proportions of entire body devoted to head has decreased by 30 percent with the progressive reduction in relative size of head to about 12 percent the adult. There is more growth of lower limbs than upper limbs during postnatal life. This means there is an axis of increased growth extending from head towards feet. This is called cephalocaudal gradient of growth.7
 
SCAMMON'S CURVES FOR GROWTH
The body tissues namely lymphoid, general, genital and neural grow at different states at different times. This pattern is discerned by Scammon's curve.
zoom view
Fig. 1.10: Scammon's growth curve
 
Lymphoid Tissue
It increases rapidly in late childhood and reaches almost 200 percent of its adult size. By 18 years the lymphoid tissue undergoes involution to reach adult size.8
 
Neural Tissue
This grows very rapidly and reaches adult size by 6-7 years. Very little growth occurs after that.
 
Genital Tissue
This shows negligible growth until puberty. But, grows rapidly reaching puberty till adult level is achieved.
 
General Tissue
This consists of bones, muscles and other organ systems. These exhibit an ‘S’ shaped curve with rapid growth up to 2-3 years of age followed by a slow phase till about 10 years. Then the growth again enters rapid phase in the 10th year and continues till terminating about 18-20 years.9
 
GROWTH PREDICTION
zoom view
Fig. 1.11: Growth prediction of cranium, maxilla and mandible
 
Cranial Base Prediction
The cranial base is designated by a line joining the most anterior point of foramen magnum—Basion (Ba) with anterior point of frontonasal suture—Nasion (Na) as seen on the lateral Cephalometric radiograph. In a normal child cranial base will grow 2 mm/year. This is expressed by 1 mm forward growth of Nasion and 1 mm backward growth of Basion, both along the original cranial base line (red line).
 
Mandibular Growth Prediction
Condylar axis: This is defined as a line from a point on the Ba-N line midway between anterior and posterior borders of 10condylar neck (DC point), to the geometric center of mandibular ramus (Xi point). During 1 year of growth Xi point will grow downward along condylar axis by 1 mm (brown line).
Corpus axis: The length of body of mandible is defined by a line from Xi point to the anterior point on mandibular symphysis. Each year corpus axis grows 2 mm (green line).
 
Maxillary Growth Prediction
Point A on maxilla grows forward same as Nasion. Therefore the N-A angle remains the same during growth. Skeletal convexity of a patient is determined by the relationship between point A and facial plane (blue line).