SU Dental Anatomy DA1 Chronology PDF

Prof. Somaya Mostafa Dental Anatomy Faculty of Dentistry sinaiuniversity.net S.M.S. Discuss the form and function of the different types of primary and permanent teeth. Intended Learning Outcomes After this topic, the student should be able to: 1- Knowledge of the dental terminology and tooth...

Prof. Somaya Mostafa Dental Anatomy Faculty of Dentistry sinaiuniversity.net S.M.S. Discuss the form and function of the different types of primary and permanent teeth. Intended Learning Outcomes After this topic, the student should be able to: 1- Knowledge of the dental terminology and tooth identification systems that they will use throughout their career. 2- Familiar with the form and function of the different types of primary and permanent teeth. 3. Knowlege eruption dates and sequence of eruption of primary and permanent teeth 4-Estimate the age of person or a specimen according to the choronology of teeth and the anatomy of the mandible. 5-Describe individual tooth morphology and related structures as well as its functions Lecture Outlines • Elevations and depression • • • • • • Upper central and upper lateral incisor Lower central and lower lateral incisor Permanent canines Permanent premolars Mandibule at different ages Compensatory curves IN THE NAME OF ALLAH THE MOST GRACIOUS THE MOST MERCIFUL Teeth At Different Ages Deciduous Teeth • E.O. appear from 7-9 w.i.u. • Decid. Teeth calcification begins before birth (4-6 m.i.u.). • The 1st permanent molars begin calcif. At birth. • Eruption: movement of developing tooth from the bony crypt to appear in the oral cavity (when crown and cervical 1/3 : 1/2 of the root are completed). • Sequence of eruption: A - B - D - C - E. • Mand. tooth precede the max. one of the same type. • By age of 2 yrs all the decid. teeth almost erupted • Root formation of decid. teeth = eruption + nearly 1 yr for inc. and 1.5 yr for canines and molars. • Shedding: resorption of decid. root (by odontoclasts) due to pressure performed by the eruptive movement of its successor till the decid. tooth exfoliated to be replaced by this successor. • Shedding date = eruption date of successor. Chronology Of Deciduous Teeth Permanent Teeth • E. O. appear from 4 m.i.u. (1st M) to 4yrs (3rd M). • Sequence of eruption: 6 - 1 - 2 - 3 - 4 - 5 - 7 - 8 (in mandible). • 6 - 1 - 2 - 4 - 5 - 3 - 7 - 8 (in maxilla) • Crown completed = 3 yrs before eruption. • Root formation = eruption + 3 yrs. • Date of eruption of permanent incisors is almost the same as decid. inc. but in years. • Premolars start calcification between 1 ½ : 2 ½ yrs. • First, second, and third molars erupt at ages of 6, 12, and 18 yrs, respectively. • At early dates of eruption X-ray examination to the jaws can help to know the condition of the teeth before eruption. Chronology Of Permanent Teeth  No erupted teeth.  X-ray examination reveals the the different amount of calcified teeth structures.  The roof of the bony crypts are widely opened at birth so that these calcified parts may fall out of the dried specimen.  Nearly after 15 days the edges of the bony crypts have grown and formed roofs (tooth parts will not drop out). At birth At birth • • • • • • A More than ½ of crown is formed B Half of crown is formed C Just cusp tip is formed D Occlusal surface is formed(united cusps) E Seperate cusps are formed 6 ML cusp only is formed Beg. Of calcification……..at birth………Date of eruption A 4MIU……………………9 M………………..6M 5M + 6M = 11 M 11 M is needed for formation of crown and 1/3 root At birth About 1/2 crown is formed 1 2 3 4 Beg. Of calcification……..at birth………Date of eruption B 4.5MIU.......................... 9M......................... 7M 4.5M + 7M = 11.5M So at birth less than ½ of crown is formed C 5MIU...............................9M..........................16M 4M + 16M = 20 M So at birth just cusp tip is formed Beg. Of calcification……..at birth………Date of eruption D 5MIU.........................9M........................12M 4M + 12M= 16M So at birth occlusal surface is formed E 6MIU...........................9M...............................20M 3M + 20 M = 23M So at birth seperate cusps are formed 6 months Deciduous teeth • • • • • A Starts to erupt with 1/3 of root is formed. B The crown and small portion of the root is formed. C 2/3 of the crown is formed. D More than 2/3 of the crown is formed. E Less than 2/3 of the crown is formed. 6 months 6 months Permanent teeth     1 2 3 6 Incisal 1/3 is formed. Incisal 1/3 is formed. Tip of the cusp is formed. Separate cusps is formed. 3 years • Deciduous teeth All are erupted with fully formed roots. ( Teeth are in occlusion). Permanent teeth 1. More than 2/3 of the crown is formed. 2. Less than 2/3 of the crown is formed. 3. More than 1/3 crown is formed. 4. About 1/3 crown is formed. 5. Small part of the crown is formed. 6. Crown is completed. 7. Crown begins to calcify so separate cusps are formed. 3 years 6 years • Deciduous teeth • A shows root resorption and may be shedded and replaced by 1. • B and D show different amount of root resorption. • C and E don’t show any root resorption. • • • • • Permanent teeth 1 may be erupted and has 1/3 of its root is formed. 2 has less than 1/3 of its root is formed. 3 , 4 , and 5 have their crowns may be completed. 6 is erupted with 1/3 of its root is formed. 7 years 7 years 7 years 7-8 years 9 years • Deciduous teeth All the incisors are shedded While in molars most of their roots show resorption(shedding of E at 10 yr). • Permanent teeth 1. Is erupted and its root is completed. 2. Is erupted and most of its root is formed but not completed. 3. May be erupted with 1/3 of its root (may erupt at 12 yr). 4., 5 not yet erupted and less than 1/3 of their roots are formed. 6 Is erupted and its root are completed. 7 Shows crown completion and small part of its roots is formed. 8 Begins to be calcified ( calcified separate cusps are shown). 10 years 10-11 years 12 years • Deciduous teeth All are shedded and if any deciduous tooth remains after this age it is consider to be retained deciduous tooth. Permanent teeth All are erupted(except the 8). All have completed roots (except 7 which has 1/3 of its roots is formed). 12 years More than15 years References: List of References 1. Course Material: 2. Essential Books (Textbooks) Reference 1: Reference 2: Reference 3: 3.Periodicals, Web Sites, etc. THANK YOU For any questions feel free to contact me by e-mail [email protected] Prof. Somaya Mosatafa Dental Anatomy