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CONCEPTS OF RPICONCEPTS OF RPI
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
www...
INTRODUCTION
www.indiandentalacademy.com
 RPI is a modified I-bar retainer system.
 It was devised by Krol in 1973.
 All the components of the I-bar assembly we...
 Principle of Krol’s design was
 “stress control with minimal tooth and gingival
coverage”
His concept is intended to m...
RR - REST
PP - PROXIMAL PLATE
II - I-BAR
www.indiandentalacademy.com
MODIFICATION OF EACH COMPONENT
OF THE I-BAR RETAINER REQUIRED TO
FORM A RPI SYSTEM
†Mesial rest modification
†Proximal pla...
Mesial rest preparationMesial rest preparation:
In molars the mesial rest extends only into
triangular fossa.
The canine...
Proximal plate modifications:Proximal plate modifications:
 One of the major disadvantages of the I-bar
denture was the e...
 Design modification I ::
The proximal plate is
designed to extend along the
entire length of the proximal
surface of the...
 Bar clasp assembly in which
guiding plane (GP) and proximal
plate (PP) extend entire length of
proximal tooth surface.
...
 Design modification II :Design modification II :
 The proximal plate is
designed to extend from the
marginal ridge to t...
 Bar clasp assembly in which
guiding plane (GP) and
proximal plate (PP) Extends
from marginal ridge to
junction of middle...
 Design modificationDesign modification
III :III :
 † The proximal plate is
designed to contact just
about 1mm of the gi...
 Bar clasp assembly in which
proximal plate (PP) contacts
approximately 1 mm of gingival
portion of guiding plane (GP).
...
I-bar modification:I-bar modification:
† The tip of the I-bar is
modified to have a pod shape
in order to allow more tooth...
ADVANTAGES :
 Minimal tooth coverage.
 Hence these dentures are easy to maintain
www.indiandentalacademy.com
RPARPA System
R - Rest
P - Proximal Plate
A -Aker’s clasp
www.indiandentalacademy.com
R P AR P A
 This is a modification of the
RPI retainer, again devised by
Krol in 1976.
 The I-bar in the RPI system
coul...
Advantages :
 Easier to grasp for removal of prosthesis .
 It can be used in case of large tissue
undercuts, high frenum...
 Successful use of the system requires
careful analysis of each component for
the function that it provides and
thoughtfu...
 Mc Cracken’s Removable partial denture prosthodontics. 11th edition,
2004.
 Stewart, Rudd and Kuebker – Clinical Remova...
THANK YOUTHANK YOU
For more details please visit
www.indiandentalacademy.com
www.indiandentalacademy.com
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Concepts of rpi/ dentistry dental implants

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Concepts of rpi/ dentistry dental implants

  1. 1. CONCEPTS OF RPICONCEPTS OF RPI INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. INTRODUCTION www.indiandentalacademy.com
  3. 3.  RPI is a modified I-bar retainer system.  It was devised by Krol in 1973.  All the components of the I-bar assembly were modified significantly to fulfill Krol’s design. www.indiandentalacademy.com
  4. 4.  Principle of Krol’s design was  “stress control with minimal tooth and gingival coverage” His concept is intended to minimize plaque accumulations that may endanger the health of teeth and their vesting structures. www.indiandentalacademy.com
  5. 5. RR - REST PP - PROXIMAL PLATE II - I-BAR www.indiandentalacademy.com
  6. 6. MODIFICATION OF EACH COMPONENT OF THE I-BAR RETAINER REQUIRED TO FORM A RPI SYSTEM †Mesial rest modification †Proximal plate modification - Modification I - Modification II - Modification II †I-bar modification www.indiandentalacademy.com
  7. 7. Mesial rest preparationMesial rest preparation: In molars the mesial rest extends only into triangular fossa. The canine rests are circular, concave depressions prepared on the mesial marginal ridge. It does not cover the entire marginal ridge. www.indiandentalacademy.com
  8. 8. Proximal plate modifications:Proximal plate modifications:  One of the major disadvantages of the I-bar denture was the excessive tooth contact produced by the extra long proximal plate.  Krol introduced three modifications to the proximal plate. They are - Design modification I - Design modification II - Design modification III www.indiandentalacademy.com
  9. 9.  Design modification I :: The proximal plate is designed to extend along the entire length of the proximal surface of the abutment with a minimum tissue relief. www.indiandentalacademy.com
  10. 10.  Bar clasp assembly in which guiding plane (GP) and proximal plate (PP) extend entire length of proximal tooth surface.  Physiologic relief is required to prevent impingement of gingival tissues during function.  Extending proximal plate to contact greater surface area of guide plane direct functional forces in horizontal direction, thus tooth (teeth) are loaded more than edentulous ridge www.indiandentalacademy.com
  11. 11.  Design modification II :Design modification II :  The proximal plate is designed to extend from the marginal ridge to the junction between the middle and cervical third of the tooth.  Where as in I-bar retainer the proximal plate extends about 2mm across the tooth tissue junction. www.indiandentalacademy.com
  12. 12.  Bar clasp assembly in which guiding plane (GP) and proximal plate (PP) Extends from marginal ridge to junction of middle and gingival thirds of proximal tooth surface.  The decrease in amount of surface area contact of proximal plate on guiding plane more evenly distributes functional force between tooth and edentulous ridge. www.indiandentalacademy.com
  13. 13.  Design modificationDesign modification III :III :  † The proximal plate is designed to contact just about 1mm of the gingival third of the guiding plane of the abutment tooth.  † The purpose of reducing the length of the proximal plate is to improve the gingival health. www.indiandentalacademy.com
  14. 14.  Bar clasp assembly in which proximal plate (PP) contacts approximately 1 mm of gingival portion of guiding plane (GP).  During function, proximal plate and I – bar clasp arm are designed to move in mesiogingival direction, disengaging tooth. Lack of sustained contact between proximal plate and guiding plane distributes more functional force to edentulous ridge www.indiandentalacademy.com
  15. 15. I-bar modification:I-bar modification: † The tip of the I-bar is modified to have a pod shape in order to allow more tooth contact. † It is placed more mesially so that it shifts towards the mesial embrassure space under occlusal load and increases reciprocation. † The I-bar is designed to compensate for the decreased encirclement, {tooth contact}, provided by the proximal plate and mesial rest. www.indiandentalacademy.com
  16. 16. ADVANTAGES :  Minimal tooth coverage.  Hence these dentures are easy to maintain www.indiandentalacademy.com
  17. 17. RPARPA System R - Rest P - Proximal Plate A -Aker’s clasp www.indiandentalacademy.com
  18. 18. R P AR P A  This is a modification of the RPI retainer, again devised by Krol in 1976.  The I-bar in the RPI system could not be used for patients with soft tissue undercuts and high frenal attachments.  In such cases the I-bar of the RPI retainer is replaced with an Aker’s {circumferential} clasp to form the RPA retainer. Frontal view Occlusal viewwww.indiandentalacademy.com
  19. 19. Advantages :  Easier to grasp for removal of prosthesis .  It can be used in case of large tissue undercuts, high frenum etc.  Indicated when bar clasp is contraindicated and desirable undercuts is located in gingival 3rd of tooth away from distal extension area. www.indiandentalacademy.com
  20. 20.  Successful use of the system requires careful analysis of each component for the function that it provides and thoughtful execution of the system in the abutment preparation. www.indiandentalacademy.com
  21. 21.  Mc Cracken’s Removable partial denture prosthodontics. 11th edition, 2004.  Stewart, Rudd and Kuebker – Clinical Removable partial prosthodontics- third edition  Stewart, Rudd and Kuebker: Clinical Removable denture prosthodontics. 2nd edition, 2001.  Davenport, Basker and Heath :A color atlas of removable partial dentures, 1st edition, 1980.  McCrackens ,Removable partial prosthodontics, 8th edition.   www.indiandentalacademy.com
  22. 22. THANK YOUTHANK YOU For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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