Dental Anatomy Lecture Notes - Nile Valley University

Nile Valley University Faculty of Oral and Dental Medicine Oral Biology Department Dental anatomy and morphology 1 DDA 111 Mandible at different ages  The coronoid The sigmoid notch Alveolar...

Nile Valley University Faculty of Oral and Dental Medicine Oral Biology Department Dental anatomy and morphology 1 DDA 111 Mandible at different ages  The coronoid The sigmoid notch Alveolar The condyle process The ramus body The mental foramen The mandibular angle  Mandible at birth Symphysis menti Mental foramen The body of the mandible: 1- It is too small. 2- Consists of two separate halves that unite at the midline by fibrous tissue (the area of union is called symphisis menti) 3- Contains the deciduous and permanent tooth germs 4- No teeth are erupted at that age. The mandibular canal runs near the lower border of the mandible. The mental foramen opens below the crypt of lower D.  The ramus of the mandible at birth The sigmoid notch The coronoid process is shallow present at higher level The condyle is present at than the condyle one line with the upper border of the mandible. Mandibular angle is 170° Mandible at 3 years (after the eruption of all deciduous teeth) The two halves of mandible become joined at the symphysis menti area from below upwards by bone at the end of 1st or at the beginning of 2nd year. The body of the mandible 1- Elongates especially behind mental foramen to accommodate for the developing permanent molars tooth germs. E 2- Increase in height by the growth of the alveolar bony socket which, accompany the eruption of all the +++++ deciduous teeth.  The ramus of the mandible at 3 years old Coronoid process Condyloid process 1- Mandibular angle becomes 140°. 2- The condyle is at a lower level than the coronoid process. 3- The sigmoid notch becomes deeper than at birth. 4-The mental foramen is below the socket of the deciduous lower first molar (D). Mandible at 6 years (mixed dentition period) *Mixed dentition period starts to occur by the eruption of the 1st permanent molar. **Bone remodeling adds to the growth of the mandible. *** Remodeling means that there are areas of bone resorption accompanied by bone deposition. E 6 ++ ++ +++++  At 6 years D E 6 Mental foramen opens nearly Mandibular angle is nearly as in adult.. midway between upper and. lower border of the mandibular body. Mandibular canal is situated little above the lower border of the mandible.  Mandible at adult age 4 5 6 7 Appearance of mental protuberance, which gives the characteristic, chin appearance of the adult. The mandible increases in length and height due to the eruption of the permanent teeth and growth of their alveolar process.  The sigmoid notch The mandibular canal becomes deeper. * runs parallel to the lower border of the mandible. At adult age * present at the midway between upper and The condyle present lower borders. at a higher level than 4 5 that of the coronoid process. The mental foramen *present below the socket of lower 5 or lower 4 and in some cases below and in-between The mandibular angle becomes 110°-120°.◦ both sockets. *present at the midway between upper and lower borders.  Mandible in old age **The mandible is reduced in size. **Following the loss of teeth Resorption of the alveolar bone The individual tries to bring the upper and lower jaws near to each other The mandibular canal and the during mastication. As a result of mental foramen are close to muscular action. the upper border of the body The condylar head is more or less of mandible. bent backward till it becomes at a lower level than the coronoid process. The sigmoid notch is shallower than in adult. The ramus is oblique in direction with an increase in the mandibular angle (140°). At birth At 3 years D E At adult age At 6 years 4 D E 6 4 5 6 7 In old age