Tooth Development Lecture 2 PDF

Tooth development Lecture 2 By Dr/ Waleed Mohamed Shaker Lecturer of oral biology, South Valley University B.D.S. Cairo University MD, PhD of oral biology, Suez Canal University  CAP Stage...

Tooth development Lecture 2 By Dr/ Waleed Mohamed Shaker Lecturer of oral biology, South Valley University B.D.S. Cairo University MD, PhD of oral biology, Suez Canal University  CAP Stage Enamel Cord Cell free zone But I am sure that they will disappear before enamel formation ( they are temporary structures ) Enamel Knot Condensation of cells of I.E.E  4-BELL STAGE It is characterized by continuation of the proliferation, differentiation and morphogenesis processes  4-BELL STAGE The connection of dental organ to the dental lamina is elongated forming a lateral dental lamina  4-Bell Stage 1- The inner dental epith. elongate 2-Their nucleus move away from the basement membrane 3-They differentiate into preameloblast. 4-Preameloblasts induce differentiation of the outer cells of the dental papilla into odontoblasts.  4-BELL STAGE At 11-12 WIU DENTAL LAMINA PROPER SR SI LDL Cervical ODE loop IDE 4- BELL STAGE Dental Sac Inner Enamel Epithelium Odontoblasts 4-BELL STAGE SI SR DP OB IDE  4-BELL STAGE Lingual extension of the dental lamina is called the successional lamina. It gives the permanent successors  SUCCESSIONAL LAMINA DENTAL LAMINA PROPER SUCCESSIONAL LAMINA SUCCESSOR PRIMORDIUM Dental Organ LATERAL DENTAL LAMINA 5-Apposition and Maturation Stage STRATUM INTER. STELLATE RETICULUM PRE- AMELOBLAST. PREDENTIN ODONTOBLASTS  5-Apposition and Maturation Stage *Formation of Preameloblasts **Formation of odontoblasts & dentin matrix ***Formation of ameloblasts, DEJ and Enamel matrix  INDUCTION & RECIPROCAL INDUCTION  Induction Reciprocal Induction AMELOBLAST IEE Enamel matrix IEE Dentine Dentine D.P Odontoblast Rule no 1 : IEE + D.P = Rule no 2 : IEE + Dentin odontoblasts = the IEE appear becomes inside the Ameloblast D.P  Dentin Matrix Formation Odontoblasts differentiation Early dentin formation 5-Apposition and Maturation Stage OUTER DENTAL EPITHELIUM CAPILLARY LOOP AB ENAMEL SI DENTIN SR PREDENTIN 5-Apposition and Maturation Stage E D AB PD SR OB PULP SI ASG  FUNCTIONS OF THE ENAMEL ORGAN 1- OUTER ENAMEL EPITHELIUM. a -Active transport of materials specially, after hard dental tissues formation. b- protective barrier for the rest of the enamel organ during enamel formation.  FUNCTIONS OF THE ENAMEL ORGAN 2- STELLATE RETICULUM. a-Act as a buffer against physical forces. b- It acts as a store house for the nutritive materials. c- It keeps room for the developing enamel.  FUNCTIONS OF THE ENAMEL ORGAN 3- STRUTUM INTERMEDIUM a- It control fluid diffusion into and out of the ameloblasts. b- It contains alkaline phosphatase enzyme needed for mineralization. c- These cells plus the IDE form a single functional unit responsible for enamel formation. FUNCTIONS OF THE ENAMEL ORGAN (cont.) 4- INNER ENAMEL EPITHELIUM. Morphology Organizing Nutritive Root formation. Enamel matrix Reduced enamel epithelium. Primary enamel cuticle  FUNCTIONS OF THE ENAMEL ORGAN 1- CERVICAL LOOP. a –At this point, the cells continue to divide until the crown attain its full size. b- It gives rise to the epithelial component during root formation.  FUNCTIONS OF THE DENTAL PAPILLA AND DENTAL SAC Dentin The Dental Papilla PULP Cementum, The Dental Sac Periodontal Ligament Alveolar Bone Proper  FUNCTIONS OF THE DENTAL LAMINA 1- Initiation Of The Entire Deciduous Dentition ( 2 MIU). 2- Initiation Of The Permanent Successors ( 5 MIU. For Central Incisors, 10 M. Of Age For Second Premolars). 3- Initiation Of The Permanent Molars ( First Molar 4 MIU., Second Molar 1 Year, Third Molar 4 Years)  SERRES’ PEARLS It is thus evident that the activity of the dental lamina extends over a period of about five years and disintegrates completely or remains as epithelial rests of Serres.  STAGES OF ODONTOGENESIS 1- INTIATION-STAGE 2- BUD-STAGE. 3- CAP-STAGE. 4- BELL-STAGE 5-APPOSITION  Transitory structures 1-Enamel Knot: 1- It may play a role in the formation of crown pattern by outlining central fissure 2- It may represent an important signaling centre during tooth development  Transitory structures 2- Enamel cord/ Enamel septum 1- It may play a role in the transformation of cap to bell stage 2- It may represent the origin of stratum intermesdium cells  Transitory structures 3-Enamel niche The tooth germ appeared that it has a double attachment to the oral epithelium by two separate strands. It is created because the dental lamina is a sheet contain a concavity filled with connective tissue.  GUESS THE STAGE ! ODE EK SR DS CL The process of root development takes place once the enamel and dentin reach the future CEJ  Root Formation Cervical loop Hertwig’s epith. root sheath Odontoblast differentiation Dentin formation Disintegration of root sheath Cementoblast differentiation Cervical loop Hertwig’s epith. root sheath  Odontoblast differentiation Dentin formation Disintegration of root sheath Cementoblast differentiation  EPITHELIAL DIAPHRAGM ASG  E EPITHELIAL PD AB DIAPHRAGM D Histological structure SI SR OB ODE DP DF  SINGLE ROOT FORMATION image ASG MULTI-ROOTED TOOTH  Tongue Like Extensions Epithelial diaphragm  Epithelial diaphragm  MULTI-ROOTED TOOTH ASG CLINICAL CONSIDERATIONS ENAMEL PEARL CONCRESCENCE DILACERATION FLEXION  TOOTH DEVELOPMENT  ROOT FORMATION ASG Complete  The permanent molars develop from a........................of the dental lamina. The fourth stage of odontogensis is called the............................. -In the bell stage, the connection of dental organ to the dental lamina is elongated forming a.....................................  True or false -the first layer of dentin appears in early bell stage ( ) -The lateral D.L disintegrate in the advanced bell stage.( ) -Stratum intermedium starts to appear in the late bell stage ( ) -Development of teeth starts at 5-6 M.I.U ( ) -The late bell stage started by formation of first layer of cementum ( )