1. RRR means a reduction in residual ridge 
2. DOES NOT mean residual ridge resorption
3. chronic, progressive, and irreversible
4. Proportional to 
   1. Anatomic factors
   2. Bone resportion factors
   3. Force Factors
5. Inversely proportional to bone-forming factors and damping effect and time
6. The damping effect means the amount of force that can be absorbed without damaging the ridge.

1. Broad square ridges devoid of undercuts and bony abnormalities.
2. Definite cuspid eminences and alveolar tubercules; a broad palate with uniform depth of vault in the maxillary arch.
3. Broad buccal shelf and firm retromolar papillae in the mandibular arch.
4. A definite vestibular fornix, devoid of muscle attachments.
5. Frenum attachments high in the maxillary and low in the mandibular arches.
6. A clearly defined and well-developed lingual sulcus.
7. A lateral throat form that allows suitable extension into the retromylohyoid space.
8. A firm mucosal covering over the denture-bearing area.
9. Mucous membrane in the vestibule fornix and floor of the mouth which is loosely and movably attached for denture seal.
10. A gradually sloping palate with a passive reflection at the junction of the hard and soft palate.
11. A tongue normal in size, position, and function.
12. A normally related maxilla to mandible.
13. Good muscle tonus and coordination in mandibular movements.
14. Adequate inter-ridge space for the favourable placement of teeth
15. Saliva of suitable viscosity and quantity
16. Hard and soft tissues devoid of any signs of pathologic disorder.

Reference: Syllabus of Complete Denture By HEARTWELL – 4th edition

(WALLACE CLYDE DAVIS) 1866-1950

• This is a dental restoration supported by a dowel in the root canal over which a porcelain tube teeth is placed directly on the root face of the tooth.
• It is one type of dowel crown, which is detachable or called as the detached dowel type.
• It is cemented in position uniting the tooth, dowel and crown into one unit.

1. When excessive tooth decay has occurred, there will be discrepancy between the fit of the crown and root planes. The cast base is attached to the dowel.

2. Porcelain is fused and interposed between the crown and root planes.

1. Preparation if labial and lingual planes is done

2. A complete porcelain crown of proper mould, size amd shape is selected.

3. The dowel is fitted in the root canal.

4. A platinum ferrule (0.0005 inch thick) is adapted on the dowel extension.

Porcelain crown is placed over the dowel and ferrule.

The crown position, with adjacent teeth and alignment is verified and the crown is fitted to the dowel with sticky wax and removed.

• A platinum foil 0.0001 inch is burnished onto the root face of die and the crown, ferrule and dowel is seated on platinum foil.

• The gap between the porcelain crown and swaged platinum matrix is sealed with melted inlay wax and is removed.

• This is invested and burn out done to remove the inlay wax. The temperature of furnace is raised to 1093°C and medium-fusing porcelain is placed at the area where wax has burned out.

• Depending on the morphology, porcelain can be added and fired to form the correct contours. Excess porcelain is ground and glazed to complete the restoration.

Reference : Exam Preparatory Manual By Lovely M on Fixed Partial Dentures