19 AGO 2020

19 AGO 2020 · BONE FORMATION / OSSIFICATION :- INTRAMEMBRANEOUS- within membrane  Ossification takes place in the membranes of connective tissue.  Cells in the membrane differentiate into osteoblasts,  A collagen matrix is formed, which undergoes ossification  So basically, these bone is formed from collagen matrix.  Mostly flat Bones: maxilla, majority of mandible & cranial vault* ENDOCHONDRAL – within cartilage  Bone formation takes place From within a hyaline cartilage  Cartilage cells are replaced by bone cells,ie. osteocytes replace chondrocytes.  short and long bones are formed this way  ethmoid, sphenoid, occipital (synchondrosis of bones of cranial base*)  Some part of mandible (condylar head region)  MANDIBLE BONE FORMATION IS BY BOTH endochondral + intramembraneous

19 AGO 2020 · BONE GROWTH  Don’t confuse bone growth with bone formation above  Growth of bone is by apposition — layer by layer deposition  Whereas cartilage growth is by two ways one is appositional and other is interstitial method, which is how mandibular condyle grows.  Mandible growth starts at 6th wk of IUL & completes at 12-13 years  Individual — 1st bone to ossify — clavicle— entire body  1st bone to ossify in head — mandible -2nd bone to ossify overall  Maxilla growth starts after mandible but completes earlier than mandible Start (6th wk of IUL)----- (MANDIBLE) --------------finish (12-13 years) -----------------START -------------------FINISH------------------------- -------------------------------MAXILLA----------------------------------- MANDIBLE  Primary cartilage of mandible — Meckel’s cartilage but it does not individually induce or contribute to mandibles growth  Secondary cartilage — condylar cartilage  This cartilage contributes to its growth*  Direction of growth — anterior and inferiorly  Direction of apposition @ condylar — posteriorly and superiorly  V shape principle- is shown by the mandibular growth MAXILLA  Formed entirely by intramembranous ossification  Growth is by apposition at sutures and surface remodelling  Direction of growth/migration – downward and forward  Direction of apposition – downward at alveolar area and at tuberosity area  MAXILLA IN A NUTSHELL: o Increases in height by continuous growth at alveolar bone o Increases in width by mid-palatine suture o Increases in depth by apposition at anterior region and tuberosity

19 AGO 2020 · SCAMMON’S GROWTH CURVE — GROWTH SPURTS 4 GROWTH SPURTS 1. JUST BEFORE OR AT BIRTH - Most rapid growth in human occur during pre-natal period 2. 1 YEAR AFTER BIRTH 3. PRE-PUBERTAL [GIRLS 5-6YEARS., BOYS 6-8 YEARS] 4. PUBERTY [GIRLS 10-12, BOYS 12-14] Mandibular growth coincides with 4th growth sprout ie; pubertal growth A. Neural — Brain a. At birth 50% b. At 4-6 years — 95% c. So below this age, ie around 3 yrs child will not be able to differentiate colours, tell his name and so. d. Complete at 15 years age — 100% B. Genital a. Begins at 12 years b. Complete at 18 years C. Lymphoid / immunity a. At peak — 200% — 12 years b. Complete — 100% — 18 years ∴ immunity is highest in children

19 AGO 2020 · BONE JOINTS  SYNOSTOSIS Bone formed b/w two bone junction  SYNCHONDROSIS Cartilage formed at the junction of two bones Eg. Spheno-occipital synchondrosis  SYNDESMOSIS Ligament formed at the junction of two bones Eg: stylohyoid PAIRED & UNPAIRED BONES Total no. of bones in skull :-  At birth — 45 bones  Later — 22 bones * Unpaired bones in skull :- A. Frontal [FACE OF SUHAIRA EPPO VIDARUM MACHA?] B. Occipital C. Sphenoid D. Ethmoid E. Vomer F. mandible REST ALL ARE PAIRED

19 AGO 2020 · DEVELOPMENT OF OCCLUSION  GUM PADS  0-6 months of age  Anterior open bite  So such complaint of open mouth by mother at this age o Rx — self correcting anomaly ! (SCA)  NATAL TOOTH – tooth present at birth  NEONATAL TOOTH — tooth formed within 15 – 30 days.  Most common — mandibular (anterior) central incisor  Syndrome — Rege fede syndrome  Inability to suck milk —  Nutritional deficiency  Lower part of tongue irritation.  ALVEOLAR RIDGE Transverse grooves — it divides the gum pad into 10 segments for future eruption of the teeth. CALCIFICATION DATES  1st calcification seen at 14 weeks of IUL, max sinus develops  12th week – mandible  6-10weeks- palate  4-6 weeks- lip  In pedo root formation completes 1year after eruption  As a general rule, o four teeth erupt for every six months of life, o mandibular teeth erupt before maxillary teeth, o teeth erupt sooner in females than males. o During primary dentition, the tooth buds of permanent teeth develop below the primary teeth, close to the palate or tongue. Tooth bud is always — lingual / palatal and inferiorly placed.

19 AGO 2020 · PEDO TEETH  Smallest — mandibular L1  First erupting — mandibular C1  Largest tooth — mandibular 2nd M PERMANENT TEETH  Smallest — mandibular CI  Largest — maxillary 1st M  First erupting — mandibular CI SPACES  In primary teeth — physiologic space  It is self correcting anomaly  Midline Diastema  Maxillary 1.7mm — mesial to C  Mandibular 1.5mm — distal to C  They are known as Primate space or Anthropoid space or Simmian space. SELF CORRECTING ANOMALIES o Anterior deep bite — 6 months age anomaly o (SCA) — Self correcting as posterior teeth erupts o (self – correcting anomaly)

19 AGO 2020 · DECIDUOUS OCCLUSIONS :- PRIMARY 2ND MOLARS FLUSH TERMINAL PLANE (SCA)  Most Commonly seen occlusion*  Straight line occlusion EDGE TO EDGE OR END ON Crowded , Improper jaw growth CLASS I OCCLUSION Mesiobuccal cusp of maxillary 1st M in the mandibular mesiobuccal groove Usually a flush terminal will end up in class 1 itself Self – correcting anomaly MESIAL STEP OCCLUSION  Ideal Occlusion CLASS III – When space is utilized CLASS I – If space not utilized DISTAL STEP OCCLUSION CLASS I – If space is utilized CLASS II- if space is not utilized  MIXED DENTITION :- o Started #6 eruption of mandibular 1st Molars o Finishes #3 eruption of maxillary C or #5 eruption of mandibular 2nd PM

19 AGO 2020 · PERMANENT SEQUENCE OF ERUPTION MAXILLA 6 1 2 4 5 3 7 MANDIBLE 6 1 2 3 4 5 7  1st permanent tooth — mandibular 1st M  1st successor tooth — mandibular CI  Last successor tooth — max C *** OR mandibular 2nd PM

19 AGO 2020 · STAGES OF MIXED DENTITION :- FIRST TRANSITION STAGE [ 6 – 8 ]  Erupting — C1, L1, 1st Molars  Anomaly — anterior open bite o — retrognathic mandible (12-14) o — ∴ transient class 2  At 8.5yrs old, there will be equal no of primary and permanent teeth in the mouth,  Centrals, laterals and 1st molars-permanent  Canines, 1st molar, 2nd molar-primary  Incisal Liability o Maxilla — 7mm o Mandible — 5mm  ∴ avg I L = 6 mm  How is I L Obtained: o utilising the physiologic spaces o proclination of anterior o increase in the inter – canine width