The document discusses the tooth-tissue junction in removable partial dentures, describing Kratochvil's philosophy of extending the metal framework of the RPD to contact the entire proximal tooth surface to eliminate voids and prevent issues like food impaction and tissue hypertrophy. It also covers the design of various components of RPDs like proximal plates, minor connectors, major connectors, and denture base connectors.

1. The Tooth Tissue Junction
Ting Ling Chang,
Takahiro Ogawa
and
John Beumer III
Division of Advanced Prosthodontics,
Biomaterials and Hospital Dentistry
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2. RPI System
The Tooth Tissue Junction
(Kratochvil)
Mesial rest
Proximal
plate
Tooth
tissue
junction
“I” bar

3. The Tooth Tissue Junction
Kratochvil, 1963
Basic Problem of previous
designs
 Acrylicresin at the tooth
tissue junction
 Acrylicresin is porous and
harbors oral bacteria and
retains plague
 Space at tooth tissue
junction
 Impaction of food into the
space
 Hypertrophy of tissue into
the space (arrow)

4. Proximal plate
Definition
A plate of metal in contact with the proximal surface
(guide plane) of an abutment tooth.

5. Proximal Plates vs Guide Plane
Proximal Plate
(the portion of the Guide plane
RPD metal framework (Distal surface of
that engages the abutment tooth)
guide plane)

6. The Tooth Tissue Junction
Kratochvil, 1963
Basic Problem of previous
designs
 Acrylicresin at the tooth
tissue junction
 Acrylic
resin is porous and
harbors oral bacteria and
accumulation of plague
 Space at tooth tissue
junction
 Impaction of food into the
space
 Hypertrophy of tissue into
the space (arrow)

7. The Tooth Tissue Junction
Kratochvil RPD philosophy
Solution
 Extend the prosthesis so that it
contacts the entire proximal surface
of the abutment tooth, eliminating all
voids (ie. space)
 Contact the tooth and tissue junction
with metal

8. The Tooth Tissue Junction
Kratochvil RPD philosophy
Benefits
 Protect against food impaction
 Prevent tissue hypertrophy between the
tooth and prosthesis
 The metal surface is nonporous and does
not harbor oral bacteria
 Plaque adherence is reduced

9. The Tooth Tissue Junction
Proximal plates - Design
 It should extend 2 mm onto the
edentulous mucosa
 It should be fabricated of metal
2 mm
 The metal is easily cleaned and
does not harbor oral
microorganisms

10. Proximal Plates - Tooth Born RPD’s
Additional benefits - Bracing and Retention
 Restores and maintains arch integrity in tooth-borne
situations by anterior- posterior bracing action
 Enhances retention particularly when the proximal plates-
guide planes are relatively parallel to one another

11. Proximal plates
Additional Benefits – Restoration of arch integrity
 The proximal plate in this case between the cuspid and premolar
(arrow) helps restore the integrity of the dental arch, provides
reciprocation for the retainer and helps prevent food impaction
 The remaining teeth can therefore function as a unit in
withstanding occlusal and lateral forces by distributing these
forces more widely

12. Proximal plates
Additional Benefits – Restoration of arch integrity
The proximal plates restore the integrity of the dental arch. When lateral
forces are applied the united dental arch can better distribute and absorb
these forces

13. Proximal plates
Additional Benefits – Restoration of arch integrity
The proximal plates restore the integrity of the dental arch.
When occlusal and lateral forces are applied in the extension
zone the united dental arch can distribute these forces more
widely.

14. Proximal plates
Additional Benefits – Restoration of arch integrity
The proximal plates restore the integrity of the dental arch. When lateral
forces are applied the united dental arch can better distribute and absorb
these forces
Courtesy Dr. T Berg

15. Proximal plates
Additional Benefits – Restoration of arch integrity
The proximal plates restore the integrity of the dental arch.
When lateral and occlusal forces are applied in the edentulous
areas the united dental arch can better distribute and absorb
these forces
Courtesy Dr. T Berg

16. Proximal plates
Additional Benefits-Reciprocation
 Act with other minor connectors in reciprocation of opposite
retainers
 By extending the proximal plate around the lingual of the
molar the tooth is properly encircled and the retainer is
reciprocated

17. Proximal plate
Design - Posterior teeth
 Follow the curvature of the tooth
 Extend to the self cleansing area on the facial and
lingual side of the abutment

18. Proximal plate
Design - Anterior teeth
 Limitextension on the labial to enhance
esthetics

19. Minor connector
Definition
 The connecting link between the major connector or
base of the removable partial denture and the other
units of the prosthesis, such as the clasp assembly,
proximal plates occlusal rests, or cingulum rests

20. Minor connectors
Design criteria
 They should be rigid
 Minor Connectors to Rests - The vertical components extending to the
rests from the major connector should be at least 5.0 mm apart to reduce
food entrapment. Consider lingual plate if the space is insufficient.

21. Minor connectors
Design criteria
 They should be rigid
 Minor Connectors to Rests - The vertical components
extending to the rests should be at least 4-5.0 mm apart
to reduce food entrapment. Consider lingual plate if the
space is insufficient
Courtesy Dr. A, Davodi

22. Major Connectors,
Definition:
 A rigid part of the partial denture casting that
unites the rests and other parts of the
prosthesis across the arch.
Maxillary
 Circular Anterior-Posterior Connectors
 Anterior palatal connectors
 Central palatal connectors
Mandibular
 Lingual bar
 Lingual plate

23. Maxillary Major Connectors
Criteria for selection
 Location of the edentulous areas
 The required amount of support
 The required degree of rigidity
 Patient preference
 Anticipated loss of natural teeth
 Location of the axis of rotation

24. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
Favored because they provide the best combination of
rigidity and minimum bulk.
Courtesy Dr. A, Davodi

25. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
The anterior portion of the connector is positioned
according to the treatment needs of the patient
 If the anterior teeth are to be replaced the connector
should extend into the anterior edentulous area
Courtesy Dr. GE King
Courtesy Dr. GE King

26. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
The anterior portion of the connector is positioned
according to the treatment needs of the patient
 In some patients the anterior portion is extended to contact the anterior
dentition to enhance bracing (resistance to lateral forces) and provide
support

27. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
The anterior portion of the connector is positioned
according to the treatment needs of the patient
 If the anterior teeth are to be replaced the connector should extend into
the anterior edentulous area
Courtesy Dr. GE King Courtesy Dr. GE King

28. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
The anterior portion of the connector is positioned
according to the treatment needs of the patient
 If the anterior teeth are to be replaced the connector should extend into
the anterior edentulous area
Courtesy Dr. GE King Courtesy Dr. GE King

29. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
The anterior portion of the connector is positioned
according to the treatment needs of the patient
 In some patients the anterior portion is extended to contact the anterior
dentition to enhance bracing (resistance to lateral forces)
 If the connector covers the lingual surfaces of the anterior teeth it must fit
precisely and be thinned to avoid food impaction and allow for
appropriate speech articulation.

30. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
When the anterior portion is extended to contact the anterior
dentition, as shown in this patient example, indirect retention is
provided the RPD.

31. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
 If anterior lingual coverage is not required the connector is designed
well away from the teeth
 The borders of the connector should terminate in the valleys of rugai
to minimize the junction between metal and mucosa.
Courtesy Dr. A, Davodi

32. Denture Base Connectors
Design Considerations
Position of the posterior bar of the connector
 Anterior to the vibrating line
 Should terminate adjacent but just short of the hamular notch region

33. Maxillary Major Connectors
Circular Anterior - Posterior Connectors
 The contours of the connector are thickest in the central portion of
the casting and taper smoothly into the mucosa at the margins
 Contour the anterior connector as a strap, not as a bar, for less
tongue annoyance/
Courtesy Dr. A, Davodi

34. Central Palatal Connectors
 These are used for the replacement of one or two teeth
unilaterally or bilaterally.
 Minimum width for rigidity is 8 mm
 The central portion must be thickened to at least 1.5 mm
to ensure rigidity.

35. Anterior Palatal Connectors
 Used in tooth borne RPD’s when anterior teeth are missing
 If the anterior palatal connector is used without the posterior component, a
significant increase in bulk and surface area coverage is required.
 When using this kind of connector rigidity is required and the central portion
of the connector needs to be at least 1.5 mm thick
Courtesy Dr. GE King Courtesy Dr. GE King

36. Anterior Palatal Connectors
 Used in tooth borne RPD’s when anterior teeth are missing
 If the anterior palatal connector is used without the posterior component,
a significant increase in bulk and surface area coverage is required.
 When using this kind of connector increased rigidity is required and the
central portion of the connector needs to be at least 1.5 mm thick
Courtesy Dr. T Berg

37. Anterior Palatal Connectors
 Used when a palatal torus precludes use of an anterior –
posterior palatal connector
 If the anterior palatal connector is used without the
posterior component, a significant increase in bulk and
surface area coverage is required.
 When using this kind of connector increased rigidity is
required and the central portion of the connector needs
to be at least 1.5 mm thick.
Courtesy Dr. T Berg Courtesy Dr. T Berg Courtesy Dr. T Berg

38. Anterior Palatal Connectors
 Used when a palatal torus precludes use of an anterior –
posterior palatal connector
 If the anterior palatal connector is used without the
posterior component, a significant increase in bulk and
surface area coverage is required.
 When using this kind of connector increased rigidity is
required and the central portion of the connector needs
to be at least 1.5 mm thick

39. Maxillary Major Connectors
Bead seal
 A light “V” shaped postdam at the
borders (arrows) of the major maxillary
connector, provides a dam, which
prevents accumulation of food debris
under the connectors.

40. Complete Palatal Coverage
Indications
 Used when maximal mucosal bearing surface
coverage is desired
 Extension base RPD’s where abutments are not
ideally positioned or are otherwise compromised
 Posterior resin area enables relining
Courtesy Dr. T Berg
Courtesy Dr. T Berg Courtesy Dr. T Berg

41. Major Connectors - Mandible
Two types available
 Lingual bar
 Lingual plate
Courtesy Dr. A, Davodi
The choice depends on two factors
The anatomic space available
The periodontal condition of the remaining teeth

42. Major Connectors - Mandible
Lingual bar
 Preferred design
 Less food impaction
 Simple with minimal tissue contact
 Less plaque accumulation

43. Lingual Bar
Design Criteria
 The bar should be 4mm in height
and 2mm thick in order to provide Gingival
Crest
appropriate rigidity
 The superior portion of the bar 3 mm
should be positioned at least 3mm
away from the gingival crest. 4 mm
 Sufficient space (7-8 mm) must be
available between the floor of the
mouth (lingual frenum) in its
elevated position and the gingival
margins around the dentition.

44. Lingual Bar
Design Criteria
 Therefore the minimum amount of space between the floor of
mouth and lingual frenum and the gingival crest required to
fabricate a lingual bar of sufficient rigidity is 7-8 mm
 The space available is best determined clinically with a
periodontal probe
 The patient is instructed to elevate the tongue-floor of mouth and the
measurement is made
3 mm
3-4
mm

45. Major Connector Design-Mandible
 If a lingual bar extends posteriorly it should be at least 3-4mm
away from the gingival margin to minimize food impaction
 If insufficient space is available posteriorly a lingual plate
should be used
4 mm
3-4 mm

46. Major Connectors - Mandible
Lingual plate
 Used when floor mouth contours are insufficient to
accommodate a lingual bar
 Used to stabilize periodontally compromised teeth
Courtesy Dr. A, Davodi

47. Major Connectors - Mandible
Lingual plate
 Additional Benefits
 Provides additional bracing
 Enables replacement of anterior teeth
Courtesy Dr. A, Davodi

48. Major Connectors - Mandible
Lingual plate
 Additional Benefits
 Provides additional bracing
Courtesy Dr. A, Davodi

49. Denture Base Connectors
Definition
 That part of the framework to which the
acrylic resin of the denture base is
connected
Function
 Retain the acrylic resin of the denture
base
 Metal embrasure keeps resin away from
abutment (arrow)

50. Denture Base Connectors
Function
 Retain the acrylic resin of the
denture base
 Provide strength to maintain rigidity
throughout the prosthesis
Note: Simple bars are rigid, easy to
fabricate. Avoid meshwork

51. Denture Base Connectors
Design Considerations - Mandible
 Placement is dependent upon:
 The space between the opposing dental arches
 The position of the denture teeth
 In the mandible the connectors should be positioned on the
crest and on the lingual side of the alveolar ridge
 Design- Establish a positive finish line between the acrylic
resin of the denture base and the metal portion of the RPD
framework.
Courtesy Dr. A, Davodi

52. Denture Base Connectors
Design Considerations
 There should be 1 mm of space between the tissue
surface of the connector and the tissue surface (arrow)
to allow for sufficient thickness of acrylic resin
 If the resin is thinner than 1mm it tends to fracture along the
finish line and become separated from the metal framework

53. Denture Base Connectors
Design Considerations
 The junctional area between the major connector and the
acrylic resin of the denture base must have sufficient bulk for
strength in order to prevent fracture in this region
 It should be fan-shaped in the junctional area to provide
sufficient bulk for strength

54. Denture Base Connectors
Design Considerations
 In the maxilla, there is often very little space between the
tuberosity and the opposing retromolar pad of the mandible
 Therefore the connectors are designed away from this region
as shown (arrows)

55. Denture Base Connectors
Design Considerations
 The connectors are not placed on the facial-buccal portion of
the ridge, because they will interfere with the placement of the
denture teeth
 Junctions between the acrylic resin and metal casting (finish
lines) require bulk and must be made at 90 degree angle

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