Improve Your Partials: Simple Designs, Techniques and .... Sharifi... · Improve Your Partials:...

Improve Your Partials:Simple Designs, Techniques and Materials

M. Nader Sharifi, D.D.S., M.S.Annual Spring Meeting

Ontario Dental AssociationMay 12, 2012

© 2003 M. Nader Sharifi, D.D.S., M.S.

About Your Speaker:

M. Nader Sharifi, D.D.S., M.S. holds a certificate in prosthodontics and a masters degree in biomaterials fromNorthwestern University. He received his dental education at the University of Illinois. He has presentednumerous topics on implant dentistry since his graduation. His presentations on restorative dentistry andpatient care have earned him recognition from esteemed study groups, societies and associations nationwide.He is a former assistant professor at Northwestern University and former on-call consultant for Nobel Biocare.

Dr. Sharifi currently maintains a full-time private practice of adult general dentistry in Chicago’s downtownloop. As a five day a week wet gloved dentist, he is interested in ensuring time saving and cost effective care.In 1996 he was named to the American Dental Associations Speakers Bureau.

If you would like, you can reach Dr. Sharifi easiest via the internet. Please feel free to direct any questions or

comments at any time to his Email address at MNSDDSMS @ AOL.com.


I. Removable Partial Denture – Components

A. Guide Planes

B. Rest Seats

C. Major Connectors

D. Clasp Systems

II. Tooth Preparation for Guide Planes and Rest Seats

A. Guide Planes – Horizontal stop is secondary requirement of the remaining teeth in RPD design.

1. Indication for Guide Planes – Path of insertion, stability.2. Preparation of Guide Planes – Parallel sided burs.

B. Reason for Rest Preps – Vertical stop is primary requirement of the remaining tooth for RPD design.

1. Sharing of Forces With Existing Teeth2. Seating of Prosthesis3. Direction of Force Down Long Axis – Acute angles4. More than 180º encirclement

C. Cuspids

1. Cingulum (Chevron) Rest – Mountain Climber Hand Hold2. Finger Rest – No Vertical Stop3. Preparation – Enhance Cingulum with Parallel Sided Burs

D. Premolars and Molars

1. Occlusal Rest – Create an Acute Angle2. Preparation – Round Burs

E. Indirect Retention

1. Sharing of Forces With Existing Teeth2. Prevention of Saddle Area Lifting3. Fulcrum Selection –


a) Fulcrum line is made by combining the most distal REST SEATS.b) Perpendicular to Fulcrum Line and contralateral to edentulous area.c) Identify rest seats for indirect retention. It can be in use as a direct rest seat, but not the fulcrum.d) Kennedy Class IV is really a Class I turned around.

4. Reline Indicator

a) Need for Reline – Pressure on framework seats indirect retention and SHOULD seat saddle area. Ifpressure on saddle lifts rest, then a reline is necessary.

b) During reline apply pressure to framework only – Do not Bite!c) Adjust occlusion at delivery.

III. Major Connectors

A. Maxillary Connectors

1. Anterior Posterior Strap – Posterior missing teeth2. Anterior Posterior Bar – Retained torus3. U-Shaped Strap – Anterior missing teeth only4. Full Palate – Transitional prosthesis

B. Mandibular Connectors

1. Lingual Bar – Natural opposing arch2. Lingual Plate – Denture opposing (anterior open bite) or Floor of mouth within 8 mm of gingiva

IV. Clasp Design

A. Suprabulge Clasps – First contact above height of contour

1. Akers Clasp – Basic use (free-ends?)2. Ring Clasp – Tipped mandibular second molars3. Wrought Wire Clasp – Wrong side of fulcrum line, and splinting periodontally involved teeth4. Equipoise Clasp – Interproximal, ending at facial line angle

B. Infrabulge Clasps

1. I-Bar Clasp – Basic use except molars and frenums

2. T-Bar Clasp – Not recommended any longer


C. Comparison of Suprabulge and Infrabulge clasp systems

1. Retention – Pushing versus Pulling2. Clasp Arm Stress and Strain – Load and Clasp Tip on the Same Side of the Fulcrum3. Rotational Load on the Saddle – Proximity of Fulcrum (rest seat)

V. Removable Partial Prosthodontics Impression Techniques

A. Irreversible Hydrocolloid (Alginate) – Mucostatic Result

1. Canned Alginate – canned.

2. Syringable Alginate – Simple, inexpensive, quick to retake.

B. Rubber Base – For use with custom trays.

C. Hydrocast Reline Technique – Alternative to the Altered Cast (solution when Altered Cast doesn’t work)

1. Fabricate RPD in standard fashion from Syringable Alginate impression with one modification – Add threetimes the normal relief below the retention webbing in the saddles for the framework.

2. At delivery, hollow grind the saddle area and fill with Microseal impression material. This will hold VDO.3. Seat in the mouth for ten minutes holding the framework in place – do not let the patient bite, nor apply

pressure to the saddle areas. Remove and use sharp scissors to trim excess.4. Check centric and eccentric occlusion.5. Trim Microseal to be 2 mm short of the base extension. Fill with Hydrocast and seat.6. Have the patient read aloud for ten minutes then grossly trim excess with a hot knife.7. Reseat and have the patient wear for 24 hours straight – including meals and bedtime.8. At next day appointment make a pick-up alginate impression and pour a model. Send cast to the lab for a lab

processed reline. Redeliver when ready.


Product List

1. Attachments - VKS vertical or horizontal attachment. Bredent USA, Miami, FL; 800-328-3965.2. Attachments - Stern G/L and ERA attachment. SternGold-Implamed.3. Compound for border molding impression trays - Green Stick Compound. Kerr, Romulus, MI; 800-537-

7123.4. Denture Teeth - Antaris/Postaris. Ivoclar, 800-533-6825.5. Denture Teeth - Physiodens. Vita; 800-828-3839.6. Denture Teeth - Trublend. Dentsply; 800-877-0020.7. Denture Teeth - Enigma. Leach and Dillon Products; 800-535-2633.8. Denture Teeth - Myerson Lingualized Integration Teeth. Austenol; Chicago, IL; 800-621-0381.9. Denture Tooth Selection Face Shield - Trubyte Tooth Indicator. Dentsply; 800-877-0020.10. Fox Plane - For Leveling Occlusal Plane. Dentsply; 800-877-0020.11. Functional Impression Material - Hydrocast. Kay See Dental, Kansas City, MO; 800-842-8844.12. Functional Impression Material - holds VDO for functional impressions – Microseal. AMCO

International; 800-523-074013. Impression Material - System 1 & 2 Alginate. Ivoclar; 800-344-5457.14. Occlude - Marking RPD frameworks. Pascal Co. 800-426-8051.15. Occlusal Indicator Wax - For Occlusal Adjustments and Delivery of Dentures. Kerr, Romulus, MI; 800-

537-7123.16. Pressure Indicating Paste - For Post Delivery Adjustments of Denture Sore Spots. Order from your dental

supplier.17. Reline Material - New Truliner. Bosworth Dental, Skokie, IL 708-679-340018. Rubber base impression material (light and medium) - Permlastic. Kerr, Romulus, MI; 800-537-7123.

M. Nader Sharifi, D.D.S., M.S.

Case I: Mandibular Kennedy Class II

Missing #20, 30, 31; #20 Restored with Cantilever Bridge #19=20;#28 DO amalgam with recurrent decay; #29 Periapical Path;Perio Condition: Gingivitis; Opposing Arch: Natural Dentition.

Combining the Art...

& Science of Dentistry© 2007 M. Nader Sharifi, D.D.S., M.S.

Notes:


Case II: Maxillary Kennedy Class III, Division 1

Missing #3, 14; No Restorations; Perio Condition:Generalized Recession with Gingivitis; Opposing: Class I RPD

Desires to show no clasps in the premolar region.



Notes:


Case III: Maxillary Kennedy Class II Division 2

Missing #2-3, 5, 14; Congenitally Missing #7, 10; Supraeruption #4, 13;Anterior Diastemas; Palatal Torus; Opposing Dentition: Mixed, Natural;Perio Condition: Mild Perio.



Notes:


Case I: Kennedy Class II



Tooth Guide Plane Rest Clasp Undercut

MaterialMajor ConnectorRetention WebbingTissue StopsOpposing Arch


Case II: Kennedy Class III, Division 1






Case III: Kennedy Class II, Division 2





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