Ridge = Soft tissue + bone
• Residual ridge resorption is a life long process. Residual ridge resorption is maximum upto 3 to 6 months and after that it tappers off.
Alveolar bone :- defined as a bony portion of maxilla and mandible held by the fibres of PDL.
Bone ( Dynamic Process)
Depending on the type of bone the resorption pattern varies like for spongy bone replaced 3-4 yrs and compact bone replaced 10yrs
Which is the process coupled that is bone deposition by osteoblast and bone resorption by osteoclast.
• Residual ridge resorption pattern varies in different individual
According to American college of prosthodontics
Based on bone ht
Type 1 :- residual bone height 21 mm
Type 2 :- residual bone height 16mm
Type 3:- residual bone height 11 – 13mm
Type 4 :- residual bone height 10mm
Type 1 is having good prognosis and type 4 is having poor prognosis that means it’s difficult to gain stability , retention and support
Epidemiology of residual ridge resorption
•It occurs world wide . RRR is accelerated in 1st 6 months with more loss in mandible than maxilla.
• After menopause that is due to harmonal disturbances osteoblastic activity is very less and it’s dominated by osteoclastic activity
” RESORPTION OF MANDIBLE >>>> RESORPTION OF MAXILLA
Direction of bone resorption :-
• Maxilla resorbs upwards and inwards ( centripetal) to become progressively small
• Mandible resorbs outwards and progressively wider
Etiology of residual ridge resorption :-
• Anatomical factors that is quality and quantity of bone of residual ridge RRR is directly proportional to anatomical factors
• Metabolic process :- RRR is directly proportional to bone resorption factors and inversely proportional to formation factors
• Mechanical factors :- If there is excess stimulus or no stimulus resorption takes place
Consequences of residual ridge resorption :-
– loss of sulcus width and depth
– Displacement of muscle attachment to the ridge
– loss of vertical dimension of occlusion. Reduction of lower facial height
– Increase in relative prognathism. Changes in inter alveolar relation. Change in the location of mental foramen.
– Prevention of loss of natural tooth. Change in the design of denture like impression technique by using minimal pressure impression and selective pressure impression techniques.
• Provide adequate relief on relief are areas. Avoidance of inclined planes. Centralization of occlusal contacts to increase stability and maximise compressive forces
• Adequate interocclusal distance that is by providing enough free way space . Occlusal table should be narrow .
Source :- Deepak nallaswamy and rangarajan.