Notes on Residual ridge resorption for basic understanding and also useful for NEET MDS exam.

 Before going into impression techniques and jaw relation, you should know some points about surfaces, residual ridges and stress bearing areas.

Surfaces of complete denture:

3 surfaces

Impression surface-Intaglio surface

Fit of denture depends on accuracy of this surface.

Contributes to retention, stability, and support of the denture.

Polished surface-cameo surface

External surface of denture without the teeth.

Should correspond to the contours of lips, cheek and tongue.

Contributes to retention and stability of denture.

Occlusal surface- 

Aids in mastication and directs forces of mastication to the supporting tissues.

Contributes to stability of denture. 

Residual ridge resorption:

The diminishing quantity and quality of residual ridge after teeth removed (GPT8).

Reduction of volume and size of residual alveolar process of mandible and maxilla.

Atwood classified progression of residual ridge resorption as follows:

Order 1: Pre-extraction

Order 2: Post extraction

Order 3: High, well rounded

Order 4: Knife-edged

Order 5: Low, well-rounded

Order 6: Depressed.

Generally, women show more resorption than men.

During first year of extraction- 2-3mm reduction seen in maxilla, 4-5mm for mandible.

After this the intensity will get reduced.

Annually, Mandible shows 0.1-0.2mm resorption, four times more than edentulous maxilla.

Pattern of maxillary ridge resorption is centripetal i.e., upward and palatal direction.

Resorption of mandible anterior ridge occurs in downward(vertical) and lingual direction.

For mandibular posterior ridge- centrifugal direction i.e., downward (vertical) and buccal direction.

The main ratio of anterior maxillary residual ridge resorption to anterior mandibular ridge resorption is 1:4.

Factors affecting RRR:

Treatment:

• Maintenance phase comprising of relining and rebasing the dentures is essential throughout the life of a CD patient.
• Overdentures help in minimizing ridge resorption and contribute towards enhanced retention, stability, support of prosthesis along with preservation of proprioception. Clinicians must try to retain residual root whenever possible.
• A severely resorbed ridge may require vestibuloplasty, but prosthetic rehabilitation with osseointergrated implants is the best solution to prevent this process and preserve the bone.
  
  
  

Points to remember:

1. Extreme bone resorption results in the mental foramen opening directly at the crest of residual bone process. Pressure from the denture against the mental nerve and over thin sharp bone will cause pain.

2. Round ridge with parallel sides provides good support and good stability.

3. Patients with large tongues often experience poor lower denture stability.

4. Thick pasty saliva is due to reflex sympathetic stimulation of salivary glands and watery saliva is due parasympathetic stimulation.

5. Excessive amount of thick ropy saliva and lack of saliva decreases the denture retention.

6. Epulis fissuratum is soft tissue reaction that appears in the sulcular region due to over extension of the denture flanges. Treated by shortening and smoothening the denture border.

7. Papillary hyperplasia results from candidal infection and improper relief of the palatal area in complete dentures. Small lesions are treated by curettage and large lesions are treated by split thickness supraperiosteal excision.

8. Treatment of choice for bilateral soft tissue tuberosity undercut is removal of tissue undercut on one side so that the undercut on other side helps in retention.

9. Treatment of choice for bilateral bony tuberosity undercuts is removal of both the undercuts such that no bony undercut exists.

10. All mandibular tori should be excised because the mucosa over the tori is more prone to irritation due to constant movement of the denture during mastication.

11. Maxillary tori should be removed if it- 

• Extends to posterior palatal seal region.
• Interferes with speech.
• Causes poor denture stability.

12. Mandibular lingual tori mostly occur in premolar region.

13. Soft flabby tissue is undesirable because it affects the stability of denture. If not excessive, it can be managed by suitable impression procedures, in extreme cases it should be removed surgically.

14. 33% of edentulous moths have retained root tips.