2. Support In Complete Denture
Guided By-
Dr S.R Godbole
Dr Sweta Pisulkar
Dr Trupti Dahane
Presented By-
Rohit Ashok Mistry
JR- 1
Department Of Prosthodontics, Crown & Bridge
3. Content
• Introduction
• Definition
• Review Of Literature
• Aspects Of Complete Denture Support
• Snow shoe Effect
• Anatomic Considerations Maxillary and Mandibular arch
• Relief Areas
• Practical Considerations
• Impression making
• Occlusal Scheme
6. Definition
Support: The foundation area on which a dental prosthesis rests. With
respect to dental prostheses, the resistance to displacement away from
the basal tissue or underlying structures.
(According to GPT-9)
7. Review Of Literature
• Greene Brothers (1874) : introduced the muco-compressive
technique to record impression under pressure using modelling
compound
• Page H L (1938) : recommended that all the tissue must be recorded
at rest, was the proponent of mucostatic impression technique.
• Swenson (1947): tissue placement for equalization of pressure in order
to resist occlusal stress over the entire bearing area is desirable.
• Craddock (1951): coined the term “Pear Shaped Pads” and stated that
the retromolar pad is not a favourable denture bearing area.
8. • Maison (1955) : Maximum coverage and flange extension,
Equitably distribute the occlusal load over the greatest possible
area. Extend a well-defined periphery to within the limits of tissue
tolerance, to gain lateral denture stability and valve seal.
• Atwood (1962): Clinical joy over big ridges must be tempered with
the sober realization of the greater potential bone loss over the
years of future edentulousness.
• Van Scooter and Boucher(1965): described the histology of palate
in detail and gave reasons for its use as primary support area.
9. Aspect of Support
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
Support may be considered from two point of view
The Duration for which this relation ship is
maintained
Dentures must conform to the underlying tissue
10. How can this be achieved?
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
Perpendicular Forces Directed
Towards area which resist
remodelling under pressure
Using Impression Procedures
that provide extension and
functional loading of tissues
with varying resiliency
11. Friable tissue
Area covered without impingement
Resistant to resorption
Checklist to Effective Support
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
Area Available
Resistant to resorption
Effective
Support
Cover maximal surface
Select tissue which are resistant to resorption
Provide relief to tissue which have varying
resiliency
12. Snow Shoe Principle
• Given a Constant occlusal force, a broader denture bearing
area decreases the stress per unit area under the denture base,
decreases tissue displacement, and reduces denture base
movement
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
14. Anatomy of the supporting structures
Area of the denture bearing surface :
Maxilla- 24cm2
Mandible- 14cm2
Capability To Bear Force
Maxilla >Mandible
15. Nature of supporting tissue
• Soft Tissue characteristics
• Keratinized firmly bound mucosa
• Presence of resilient submucosa
• Presence of firmly bound connective tissue
• Hard Tissue Characteristics
• Bone resistant to resorption and remodelling
• Use of cortical bone in support of complete dentures
The choice of bone support is explained well by Wolff’s law of
remodelling and the pressure tension theory.
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
17. Mucosa types
Mucosa good for support Mucosa which needs relief
Horizontal slope of Palate, Buccal Shelf Area. Mid Palatine suture Area
18. Oral Mucous Membrane
Rhonda F. Jacob,Zarb,Prosthodontic treatment For Edentulous Patient, Bouchers 13th SA Ed
Contact and extension of the static intaglio
and cameo surface of the dentures is a
composite of the adjacent tissues at rest and
in function.
The Intaglio surface of the denture
comprises of two areas:
• Stress bearing (Supporting)
• Limiting areas
19. “Since the success of the complete denture depends
largely on the relation of the dentures to anatomic
structures which support and limit them, familiarity
with the location and character of these structures is
essential.”
-Edwards & Boucher
20. Stress Bearing Areas
Maxilla
• Primary
-Anterolateral slopes of hard palate
-Maxillary tuberosity
• Secondary
-Palatal Rugae
-Residual Alveolar Ridge
-Maxillary tuberosity
Mandible
• Primary
-Buccal Shelf Area
-Retromolar Pads
• Secondary
-Crest Of Alveolar Ridge
Rhonda F. Jacob,Zarb,Prosthodontic treatment For Edentulous Patient, Bouchers 13th SA Ed
23. Rationale
Thick Submucosa
Vertical forces are perpendicularly acting
Dense corticated bone
Fibres of buccinator lie horizontally to the area
Rhonda F. Jacob,Zarb,Prosthodontic treatment For Edentulous Patient, Bouchers 13th SA Ed
Primary stress bearing areas in mandible
24. Retromolar pads
Pear Shaped Pad
• Distal extent of keratinized
masticatory mucosa
• Formed by scaring of extracted 3rd
molar and its retromolar papilla.
• The pear-shaped pad area is
associated with muscle and/or
tendinous attachments of the
buccinator, superior constrictor, and
temporal muscles.
Retromolar pad
• Triangular soft pad of tissue at
distal end of lower ridge.
• Mucosa-composed of thin,
nonkeratinized epithelium Loose
alveolar tissue
• Submucosa-glandular tissue
• fibers –buccinator superior,
constrictor temporalis
muscle,pterygomandibular raphe
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
Primary stress bearing areas in mandible
25. H i s t o l o g i c a l D r a w i n g O f T h e R e t ro m o l a r P a d s
Boucher's prosthodontic treatment for edentulous patients 9th ed 1985.
27. Crest of Alveolar Ridge
• Presence of Cancellous bone
• Less Keratinized Mucosa
Boucher's prosthodontic treatment for edentulous patients 9th ed 1985.
Histological Drawing of the Lower
Residual Ridge Mucosa
28. The Remaining Anatomy
• The remaining anatomic regions of the mandible are not usually
essential in providing denture support.
• The less keratinized alveolar mucosa of the lingual and anterior labial
ridge slope lies directly over basal slope and does not tolerate pressure
well.
• The denture borders are extended in the movable soft tissue to effect
border seal and not to promote support.
• Genial tubercle- A possible area of support
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
29. Overview Of Mandible Support Areas
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
1˚- Primary
2˚- Secondary
R- Relief
N/C- Non-Contributing
31. The Hard and soft palate
DONALD E. VAN SCOTTER, THE NATURE OF Supporting TISSUES FOR COMPLETE DENTURES, JPD MARCH-APRIL 1965, 285-294
Primary stress bearing areas in mandible
32. Horizontal Slopes Of hard Palate
• Keratinized masticatory mucosa
• Distinct submucosal layer underlying the epithelium (except the mid-
palatine suture area)
• Cortical bone of the palatine processes resist resorptive changes
• Dense band of connective tissue in the mid palatine raphe region
In a flat or low palate the amount of spongy bone is greater than in a
high palate.
DONALD E. VAN SCOTTER, THE NATURE OF Supporting TISSUES FOR COMPLETE DENTURES, JPD MARCH-APRIL 1965, 285-
294
Primary stress bearing areas in mandible
33. Postero-lateral part
of hard palate
(Large quantity of
Glandular tissue)
Antero-lateral part of hard palate
(Large quantity of adipose tissue)
Mid- palatine suture
(thin submucosal
layer)
Region of Incisive Papilla
(shows nerves and
vessels)
Primary stress bearing areas in mandible
Boucher's prosthodontic treatment for edentulous patients 9th ed 1985.
34. Crest Of Alveolar Ridge
• Thick Keratinized Mucosa
• Firmly bound to the underlying
periosteum and bone
• The underlying bone is cancellous
and undergoes resorptive changes on
functional stress
Boucher's prosthodontic treatment for edentulous patients 9th ed 1985.
Submucosal layer sufficiently thick to
provide resiliency
36. Palatine Rugae
• Increased surface area
• Resistance to antero-posterior movement of the denture
• Acts as a secondary support area
37. Overview Of Maxillary Support Area
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
38. T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
Tissues that are susceptible to resorption.
Tissues that have thin mucosa overlying cortical bone.
Mucosa which contains underlying neurovascular bundle or sensitive structures.
Relief Areas
39. Practical Consideration
• Impression making
• Occlusion
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
40. Impression making
Theories Pressure less Group (mucostatic)
Richardson
Pressure Group (Greene
Brothers)
Mucocompressive
Selective Pressure Group
(Boucher’s)
Properties
Theory based on Mucostatic theory (based on
Pascal’s law) sets out to record the
mucosa in its static (supported by
underlying basal bone),
undisturbed form
This concept seeks to subject the
tissues to a continuous pressure
Based on the fact that there are
variation in displaceability of
supporting tissue and thus the
need for selective pressure
HOW? Use of mucostatic impression
material (impression plaster)
Use of impression compound,
waxes and soft liners
altering the spacer thickness and
hence material thickness
Questions
raised?
Such an impression will not cover
enough area as no border moulding
(Depends on the intimate contact
and short range forces)
conducive to resorptive changes
Displacement of Dentures
in tissues attempt to return to
their original form
Thickness of spacer and
impression material does not
gurantee selective pressure
Control over finger pressure
Occlusal load distribution
Shefali Singla, Complete denture impression techniques: Evidence-based or philosophical, Indian J Dent Res, 18(3), 2007
41. Questioning Selective Impression Technique
1. Can we alter the pressure by simply changing the thickness of spacer/
impression material in a loaded tray?
Bone reacts to the slight distortion caused by pressure in the form of elastic forces
which resist compression.
2. Can we control the Finger pressure, thereby choosing a particular area of
the basal seat to receive excess load?
The finger pressure cannot be controlled.
3. Can the load received at occlusal surfaces be selectively distributed or does
it get transferred uniformly over the seat?
It gets distributed throughout the denture bearing area
Shefali Singla, Complete denture impression techniques: Evidence-based or philosophical, Indian J Dent Res, 18(3), 2007
42. Spacer Designs and Support
Boucher’s Design
J J Sharry’s Design
Rudd, Morrow, Rhodes Design
Jain AR, Dhanraj M (2016) A Clinical Review of Spacer Design for Conventional Complete Denture. Biol Med (Aligarh)
43. Studies on Occlusal Schemes
• AN in-vitro study compared the pressure values on the supporting tissue
using three different posterior occlusal schemes: Balanced occlusion,
lingualized occlusion, and monoplane occlusion in simulated dentures.
Monoplane < Completely Balanced < Lingualized Occlusion
Madalli P, Murali CR, Subhas S, Garg S, Shahi P, Parasher P. Effect of occlusal scheme on the pressure distribution of complete denture supporting tissues: An
in vitro study. J Int Oral Health 2015;7 (Suppl 2):68-73.
44. • FRANK, conducted a study to determine the effect of tray
modifications & selection of impression materials on pressures exerted
on the denture supporting tissues .
Conclusion:
More pressures were measured at the crest of the ridge than on the palate
when no relief was used.
Use of escape vents or relief was equally effective in decreasing pressures
& equalizing the pressures on the ridge crest ,palatal area.
T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete denture retention, stability, and support, PART 3, JPD Jan 1983
45. Morbidity Associated with complete denture
• Residual Ridge Resorption
• Denture Stomatitis
• Flabby Tissue (Maxilla 24% mandible 5%)
• Combination Syndrome
• Denture Irritation Hyperplasia (5%)
• Traumatic Ulcer (7%)
• Temporomandibular Joint Disorders
Gunnar E. Carlsson, Clinical morbidity and sequelae of treatment with complete dentures, (J Prosthet Dent 1997;79:17-23.)
46. Summary
• Support is one of the essential requirement in fabrication of complete
denture.
• The knowledge of denture supporting tissue is important is fabricating
a denture which has good longevity
• Various methods, technique are to be used in order to achieve
maximum support.
• Dentists must base their technique on an understanding of biologic
aspects of the relationship between the denture base and the supporting
tissue.
47. References
• T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete
denture retention, stability, and support, PART 1, JPD jan 1983
• T. E. Jacobson& A. J. Krol, A contemporary review of the factors involved in complete
denture retention, stability, and support, PART 3, JPD jan 1983.
• Shefali singla, complete denture impression techniques: evidence-based or philosophical,
indian j dent res, 18(3), 2007
• Jain AR, dhanraj M (2016) A clinical review of spacer design for conventional complete
denture. Biol med (aligarh)
• Boucher's prosthodontic treatment for edentulous patients 9th ed 1985.
• Donald e. Van scotter, The nature of supporting tissues for complete dentures, jpd march-
april 1965, 285-294
• Rhonda f. Jacob,zarb,prosthodontic treatment for edentulous patient, bouchers 13th SA ed
• Gunnar E. Carlsson, Clinical morbidity and sequelae of treatment with complete dentures,
(J Prosthet Dent 1997;79:17-23.)
Retention-Complete denture retention is the resistance to displacement of denture base away from the ridge
Stability- it is the resistance to horizontal and rotational forces preventing lateral or anterio-posterior shunting of denture base
Support- denture support is the resistance to vertical movement of the denture base towards the ridge.
Although the broad, high ridge may have a greater potential bone loss, the
rate of vertical bone loss may actually be slower than that of a small ridge because
there is more bone to be resorbed per unit of time and because the rate of resorption
also depends on the density of the bone.
The denture must conform to the underlying tissue so that the occlusal surface can correctly oppose on eanother at the time of insertion
It is vital that this is maintained for a period of duration
The reason why retention and stability aids support
Cover Maximal surface.
Choose tissue which resist resorption
Establish form contact to the tissues which are resistant to resorption
Compensate for tissues which are friable under function and to maintain harmonious occlusal relation ship
After determining the outline for of the total denture bearing area, one must study the nature of the supporting tissue contained within the border
The nature of supporting tissue, it can be discussed under the heading which have been mentioned that is the soft and the hard tissue..or another way is to go from the most superficial layer to the deepest….
Keratin is a scleroprotein which is produced by epithelium on maturation, it renders the epithelial layer strength and resiliency. The submucosa which is present underneath the mucosa provides with cushioning effect this effect is magnified on [resence of submucosal structures like salivary gland. In some areas of the masticatory mucosa there is absence of submucosa and thus the mucosa is firmly bound to the periosteum by mean od thick bands of connective tissue. These bands of connective tissue prevent the direct pressure on the underlying bone and thus is a beneficial feature.
The hard tissues which are underlying the denture bearing area must be relatively resistant to resorption and remodelling, although presence of few natural teeth helps in conserving the amount of bone. It is important to minimize pressure in areas which are prone to resorption in order to preserve the ridge in good health in completely edentulous patients.
The use of cortical bone in support of complete denture permits the prosthesis to maintain its recorded relationship to the edentulous
ridge over a longer period of time.
The bottom line being that firm keratinized mucosa bound to underlying cortical bone with a variable zone of connective tissue is nd associated with muscle attachment provides ideal bearing area
On the left there is mucosa which has a thick submucosal layer, the thick submucosa is more efficient in beating the stress exerted by the dentures, on the other side there is representation of mucosa covering the mid-palatine raphe area where less or negligible amount of submucosa may be present. Other regions which require relief on account of its histological nature is the fovea palatine, nasopalatine area due to nasopalatine nerves and vessels. A detailed discussion of the mucosal consideration is to follow further.
When it comes to denture fabrication the mucosa which maximum contributes to support is the masticatory mucosa with the exception of parts of soft palate and parts of mucogingival junction which establishes the seal
Boundaries and Extent-
Area between the mandibular buccal frenum and the anterior edge of the masseter muscle.
Medially- crest of the ridge
Laterally- bony external oblique ridge
Distally- retromolar pads
The buccinator fibres attach horizontally along the bony oblique ridge. As the resorption of the ridge occurs, the buccal shelf area does not resorb because of its muscle attachment on its posterior and lateral borders. The shelf is dense and cortical and lies at a right angle to vertical occlusal forces and is therefore a primary stress bearing area
Clinicians must recognize the differences between the pear-shaped pad and the retromolar pad based on anatomic location and
histologic composition. Frequently, the entire area of the distal ridge crest is referred to as retromolar pad. This leads to confusion in determining the mandibular
denture extension.
Pear Shaped Pad(term was first given by craddocl)-
The deep and superficial tendons of the temporal muscles insert medially and laterally in the mandible at the posterior border of the pear-shaped pad. Such muscle attachments and the overlying, firmly bound masticatory mucosa provide a stress-bearing region that is relativelyresistant to resorptive changes. If the mandibular denture is short of this region, there will be more rapid resorption of the distal alveolar ridge and a resulting settling of the denture base posteriorly
The retromolar pad is a triangular pad of tissue at the distal end of the residual ridge. According to Jacobson the retromolar pad is not a favourable denture bearing area . The junction of the pear shaped and retromolar pad demarcates the distal border of a properly extended mandibular complete denture.
Histologic drawing shows the submucosal layer to be adequate thickness and firmly attached to the ridge. However bone that forms crest of lower ridge is cancellous, or spongy in nature , there fore this part cannot ve used for primary support
The genial tubercle can be used as a support if thick mucosa is present over the area, patients who have undergone vestibuloplasty procedure with split thickness graft have favourable mucosa overlying the genial tubercle area
Relative importance of various anatomic regions of mandible in providing denture support. Primary support areas must include the buccal shef areas and the pear shaped pads. Ridge crest and areas of genial tubercle may be treated as secondary support areas. lingual and labial areas are non-contributing.
Add a note on RUGAE
The figure on right shows the drawing of mucosa of the hard and soft palate
Figure on the right shows stress bearing areas of the maxillary arch
Resiliency of the submucosal layer acts as a cushion for the functional stresses transmitted to the mucosa
The dense connective tissue band which traverses in the mid-palatine region adheres the mucosa to the underlying periosteum, there must be relief in this area as to avoid undue pressure and creation of fulcrum at this area
Rapid resorption involving the anterior maxillary ridge beneath a complete denture opposed by mandibular anterior natural dentition is frequently seethe forces must be controlled and minimized by proper design and technique
Tuberosities are considered secondary stress bearing areas as these are firm swellings do provide stability to the denture and prevent its rotational movement or any horizontal forces unseating the dentures
anatomic fold or wrinkled usually used in the plural sense; the irregular fibrous connective
tissue ridges located in the anterior third of the hard palate.
Irregular elevations or rugae extend anterolaterally from the palatine raphe.
According to Lund, the rugae are not simple elevations of the mucous membrane,
but contain as their base a connective tissue nucleus called “ruga nucleus.” This
consists of a tissue of embryonic character, rich in cells and interwoven with very
delicate connective tissue fibers. The disappearance of the rugae in later life is
apparently due to the decrease of submucous adipose tissue, rather than shrinkage
of the ruga nucleus. 21 The rugae may have a mechanical function during the suckling
age, but are rudimentary in man, probably because of the soft nature of his
food.
Say Something About FOVEA PALATINi
In patients with thick ropy saliva, the fovea palatinae should be left uncovered or else the thick saliva flowing between the tissue and the denture can increase the hydrostatic pressure and displace the denture.
The two most important steps which will help in acquiring maximum support during complete denture fabrication is impression making and occlusal schemes
Boucher CO (1951) A critical analysis of mid-century impression
techniques for complete dentures. J Prosthet Dent 1(4):472–491
Can we alter the pressure by simply changing the
thickness of spacer / impression material
Can we control the finger pressure, thereby choosing a
particular area of the basal seat to receive excess load?
Can the load received at occlusal surfaces be selectively
distributed or does it get transferred uniformly over the
seat?
The physics behind providing spacer clearly takes into account that pressure be excreted on the areas where the trays are in contact with the base directly(primary stress bearing area), but the question is the stress bearing area also has some compressibility and resiliency and it would be an underestimation that the pressure applied on the tray does not affect these tissues.
The pressure applied by the finger is not controlled…there may be delivery of force which compresses the tissue overall or none at all
Eventually after the fabrication of a denture base during function. the occlusal stress
Sharry, based on minimal-pressure technique, recommends adaptation of a layer of base-plate wax over the whole area outlined for tray (even in PPS area)
Boucher, based on selective-pressure technique, advocated the placement of 1 mm base-plate wax on the entire basal seat area except posterior palatal seal (PPS) area.
Morrow, Rudd, and Rhoads, based on minimal-pressure technique, recommend blocking out undercut areas with wax and then
Though the sequale of ill fitting denture is multifactorial but the ultimate effect is reflected in the tissues that support the denture and the TMJ.