age changes in maxilla pptx...............pptx

age changes in maxilla

1. AGE CHANGES IN MAXILLA

2. CONTENTS INTRODUCTION DEVELOPMENT OF MAXILLA POST NATAL GROWTH OF MAXILLA - DISPLACEMENT - GROWTH AT SUTURES -SURFACE REMODELLING AGE CHANGES IN MAXILLA - AT BIRTH - IN ADULTS - IN OLD AGE AGE RELATED ARCH WIDTH CHANGES IN MAXILLA MANAGEMENT REFERENCES

3. INTRODUCTION Maxilla is the 2 nd largest bone of the face. The 2 maxillae form the whole of the upper jaw. Each bone consists of a body & 4 processes - zygomatic - frontal - alveolar - palatine Each assists in forming the boundaries of three cavities - the roof of mouth - the floor and lateral wall of nose - the floor of the orbit

4. The body of maxilla is pyramidal in shape ,with its base directed medially at the nasal surface, and the apex directed laterally at the zygomatic process. It has four surfaces - superior or orbital - medial or nasal - anterior or facial -posterior or infratemporal

5. DEVELOPMENT OF MAXILLA The primary ossification centre appears for each maxilla in the 7 th week The secondary centers are at – zygomatic, nasopalatine and orbitonasal areas It lies in the angle formed by the infraorbital nerve and anterior superior alveolar nerve , above the part of the dental lamina from which the canine tooth germ develops The premaxilla begins to ossify from two centres in the latter part of the 7 th week Ossification spreads by : - bony trough formed for infraorbital nerve - palatine process

6. POST NATAL GROWTH OF MAXILLA Maxillary complex is attached to the cranial base it influences the development of this region. The growth of the maxilla is dependent on the spheno -occipital & spheno -ethmoidal synchondroses . The growth of the nasomaxillary complex is produced by the following mechanisms - displacement - growt h at sutures - surface remodelling

7. DISPLACEMENT Growth of the cranial base  passive / secondary displacement of nasomaxillary complex in downward & forward direction. As middle cranial fossa grows it moves the nasomaxillary complex to a more anterior  position Growt h of maxillary tuberosity  primary displacement in a forward direction , due to the enlargement of the bone itself.

8. GROWTH AT SUTURES Maxilla is related to cranium at least partially by the, - Frontomaxillary suture - Frontozygomatic suture - Zygomaticotemporal suture - Pterygogopalatine suture These sutures are all oblique & more or les parallel with each other. The growth in these areas would serve to move the maxilla downward & forward.

9. SURFACE REMODELING Remodeling occurs by bone deposition and resorption to bring about a) Increase in size b) Change in shape c) Change functional relationship Resorption occurs on lateral surface of the orbital rim , to compensate for this resorption there is bone deposition on the external surface of the lateral rim

10. Bone deposition occurs along the posterior margin of the maxillary tuberosity, lengthening of dental arch & enlargement of antero-posterior dimension of entire maxillary  body & helps to accommodate developing molars. Bone resorption on the lateral wall of the nose leads to an increase in the size of the nasal cavity

11. Bone resorption on floor of the nasal cavity compensated by deposition on palatal side, downward shift an increase in maxillary height The zygomatic bone moves in posterior direction , which is achieved by resorption on anterior surface & deposition on posterior surface

12. Increases the maxillary height & depth of palate THE EXPANDING “V” PRINCIPLE The growth movement & enlargement of the bones occur towards the wide end of “v” as a result of differential deposition & selective resorption Resorption – outer side of V Deposition – inner side of V

13. Post natal growth of maxilla Growth in height - vertical Growth in width - transverse Growth in length - A-P TRANSVERSE DIMENSION ( IN WIDTH ) - Growth in midpalatine suture - Remodelling at lateral surface of alveolar process

14. A-P DIMENSION (IN LENGTH) MAXILLARY PALATO – PRIMARY SECONDARY MAXILLARY SUTURE DISPLACEMENT TUBEROSITY

15. VERTICAL DIMENSION (IN HEIGHT) PALATAL REMODELLING ERUPTION OF TEETH PRIMARY DISPLACEMENT

16. AGE CHANGES IN MAXILLA - AT BIRTH Transverse and anteroposterior diameters > vertical diameter Frontal process is well marked. Body of bone consists of a little more than the alveolar process. The tooth socket is close to floor of orbit Maxillary sinus presents the appearance of a furrow on lateral wall of nose

17. - IN ADULT The vertical diameter is the greatest due to developed alveolar process. Increase in size of sinus Maxillary sinus - with increasing age it expands - becomes more and more pneumatized down around maxillary teeth

18. EXPANSION OF MAXILLARY SINUS At birth - 7mm length - 4mm height - 4mm width Expands at rate of - 2mm vertically yearly - 3mm A-P yearly Expansion by - bone resorption - by tooth eruption ( as vacated bone become pneumatized)

19. As the maxillary bone develops , the sinuses cavities are formed and filled by air, a physiological process called pneumatization. The pneumatization itself causes the maxillary sinuses to expand into the adjacent anatomical structures ,being the alveolar process the anatomical region with the highest prevalence rate . Some studies have demonstrated the posterior teeth loss can also influence maxillary sinus pneumatization.

20. In such instance , the antral cavity may be near to the crest of the ridge. The roots of the maxillary second bicuspid, first molar , and second molar are the most frequently involved. If dental implant placement is planned in these cases, immediate implantation and/or immediate bone grafting should be considered to assist in preserving the 3 – dimensional bony architecture of the sinus floor at the extraction site.

21. - IN OLD AGE The bone reverts to some measure to its infantile condition as : - it’s height is diminished - after the loss of the teeth the alveolar process is resorbed

22. THE RESIDUAL ALVEOLAR RIDGE Following the loss or extraction of teeth, the empty socket fills clot and is gradually replaced with new bone. The bone round the socket margins also reorganizes. The mucoperiosteum gradually heals and covers the healing socket. The remodelling process results in a rounded ridge like structure known as the residual alveolar ridge . The residual alveolar ridge plays a very important role in the construction of complete denture.

23. AMOUNT AND RATE OF BONE RESORPTION According to boucher , During the first year after tooth extraction , the reduction in residual ridge height in the midsaggital plane is 2-3mm for maxilla 4-5 mm for mandible Annual rate of reduction in height 0.1 – 0.2 mm for mandible 4 times less in the maxillla

24. AGE RELATED ARCH WIDTH CHANGES IN MAXILLA Bishara et al. found that for maxillary arch , intercanine width increases between 3 and 13 years by 6mm but decreases by 1.7 mm between 13 and 45 years On the other hand , intermolar width increases by 2mm between 3 and 5 years and by 2.2mm between 8 and 13 years but decreases by 1mm by 45 years of age

25. MANAGEMENT PRE- PROSTHETIC SURGERY It aims at providing a good healthy surface for the insertion of the dentures It includes all the surgical procedures by virtue of which an ideal smooth , healthy U shaped ridge, without any unfavourable undercuts or bony growths and with sufficient vestibular depth is achieved

26. PROSTHETIC MANAGEMENT Impression techniques Denture base selection Implant supported prosthesis Immediate dentures Overdentures

27. IMPRESSION TECHNIQUE The main aim of the impression procedure is to gain maximum area of coverage. Selection of proper trays and the correct impression procedure is very essential for an accurate impression. SELECTIVE PRESSURE This technique makes it possible to confine the forces acting on the denture to the stress bearing areas. This helps in better withstanding the mechanical forces induced by denture wearing.

28. SELECTION OF DENTURE BASE For degenerative ridge patients there are three types of denture bases: Methyl methacrylate resin denture bases Cast metal bases Processed resilient , lined denture bases IMMEDIATE DENTURES Some authors claim that extraction followed by immediate dentures reduces the ridge resorption

29. OVERDENTURES Tooth supported overdentures help in improved stress distribution there by maintaining the integrity of residual ridge. The occlusal and parafunctional stresses are distributed through the abutment teeth A study was conducted with overdentures supported by canines and it was seen that the bone loss was 0.6mm where as 5mm in conventional complete dentures.

30. IMPLANT SUPPORTED PROSTHESIS Advantages offered by implant supported prosthesis. Maintenance of alveolar bone. Maintenance of occlusal vertical dimension. Height of alveolar bone is found to be maintained as long as the implant remains healthy. Increased stability , retention and phonetics. Maintenance of structure and function of muscles of mastication and facial expression. Efficiency to take up stress and strain.

31. REFERENCES Essentials of complete denture prosthodontics – Winkler , Sheldon – 2 nd Edition Bouchers Prosthodontic treatment for edentulous patients 12 th edition Orthodontics The art and Science S.I. Bhalajhi 7 th Edition Human osteology – A clinical orientation – Nafis Ahmad Faruqi – 3 rd Edition