1- Timing of growth spurts Time Female Male prenatal Immediately before birth Immediately before birth Postnatal a- infantile 1 -3 years very active in 1st year and 1st few months – 25cm /year 1 – 3 years very active in 1st year and 1st few months 25cm /year b- mixed dentition 7-9 year 6cm /year 8 -11 year 6cm /year c- pubertal spurt 11 – 13 year 8 -12 cm/ year 14 -16 year 8 -12cm /year Growth spurts: certain periods where sudden accelerate of growth occurs 2- Change in craniofacial by age Site 1 -5 year 5 –10 year 10 – 20year Cranium 85% 11% 4% Maxilla 45% 20% 35% Mandible 40% 25% 35% 3- Changes in dental arch Maxillary: Intercanine width will increase by 6mm from 3 – 13 year Inter-molar width will increase by 2mm from 3 – 5 year and 2mm from 10 -13 year Mandibular: Intercanine width will increase by 3 – 7mm from 3 – 13 year Intermolar width will increase by 1- 5mm from 3 – 5 years And: 1mm from 8 13 years = median diastema should not be closed before the cusp tip of canine passed beyond the apical 1/3 of lateral incisor 4- Maxillary 1st permanent molars width increase significantly more than lower arch due to: a- Lower erupted tipped in lingual direction b- Both lower 6 move mesially due to late mesial shift assuming diameter along convergent dental arch 5- Ugly duckling stage (Broadbent phenomenon): Upper right and left canine pass on the distolabial surface of U2 right and left which leading to fan shape of upper central incisors. a- Canine passing against their apices b- The width at the base of the nose has not yet attained its proper dimension 6- Incisor liability: (Warren Mayne) The difference in size between deciduous and permanent incisors Permanent incisors are large in size by 7mm in upper arch and 6mm in lower arch this difference called liability which is corrected by: a- Interdental spacing in deciduous teeth: 4mm in U, 3mm in L b- More labial inclination in lower incisors: 2mm c- Primate space: mesial to U3 and distal to L3 d- Increase intercanine width: 3mm 7- Changes in arch length: Decreased by eruption of deciduous dentition---- then Increased by eruption of incisors permanent ------ then Decreased by molar eruption and mesial shift 8- Mandibular angle: Decreased by age: 170 degree at birth ------- to 124 degree in adult Due to forward movement of mandible and action of elevating muscles 9- Pre-dental stage: a- Retrognathic gum pad corrected with forward growth of mandible b- Anterior open bite: corrected by eruption of deciduous anterior teeth c- Simple hinge movement only corrected by eruption of incisors and molars d- Infantile swallowing: corrected at end of 1st year when children are fed solid food 10- In primary dentition stage: a- Anterior deep bite corrected by eruption of primary molars and attrition of anterior teeth b- Flush terminal plane: corrected to Class I molars by late mesial shift c- Anterior s