This document discusses principles of removable partial denture design. It covers different types of partial denture support, including tooth-supported and tooth/tissue-supported designs. Key factors in partial denture design include distributing forces, controlling movement, selecting appropriate components, and considering the individual patient's anatomy and needs. Design elements like survey lines, clasps, connectors, and occlusal rests are discussed in terms of their effects on support and stress distribution. The document contrasts the biomechanical considerations between total tooth-supported versus distal extension partial dentures.
Fixed partial dentures transmit forces through the abutments to the periodontium. Failures are due to poor engineering, the use of improper materials, inadequate tooth preparation, and faulty fabrication. Of particular concern to prosthodontist is the selection of teeth for abutments. They must recognize the forces developed by the oral mechanism, and resistance.
Successful selection of abutments for fixed partial dentures requires sensitive diagnostic ability. Thorough knowledge of anatomy, ceramics, the chemistry and physics of dental materials, metallurgy, Periodontics, phonetics, physiology, radiology and the mechanics of oral function is fundamental.
Indian Dental Academy: will be one of the most relevant and exciting
training center with best faculty and flexible training programs
for dental professionals who wish to advance in their dental
practice,Offers certified courses in Dental
implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic
Dentistry, Periodontics and General Dentistry.
Fixed partial dentures transmit forces through the abutments to the periodontium. Failures are due to poor engineering, the use of improper materials, inadequate tooth preparation, and faulty fabrication. Of particular concern to prosthodontist is the selection of teeth for abutments. They must recognize the forces developed by the oral mechanism, and resistance.
Successful selection of abutments for fixed partial dentures requires sensitive diagnostic ability. Thorough knowledge of anatomy, ceramics, the chemistry and physics of dental materials, metallurgy, Periodontics, phonetics, physiology, radiology and the mechanics of oral function is fundamental.
Indian Dental Academy: will be one of the most relevant and exciting
training center with best faculty and flexible training programs
for dental professionals who wish to advance in their dental
practice,Offers certified courses in Dental
implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic
Dentistry, Periodontics and General Dentistry.
Failures in Fixed Partial Denture
(Prosthodontics FPD- Dental science)
Various types of failures in the fabrication of fixed partial denture
Dr.Sachin Sunny Otta
St.Gregorios Dental College,Kothamangalam,Ernakulam
this presentation has all the techniques in impression making in the fabrication of an RPD.
The presentation is available on request. Mail me at apurvathampi@gmail.com
The patient who requires a single denture opposing a natural or restored dentition challenges the clinician even more than the completely edentulous patient does. This is due to the biomechanical differences in the supporting tissues of the opposing arches. So a proper evaluation, correction of the existing factors and proper sequence of denture construction is necessary to give a more stable prosthesis.
2- b. Basic principles for designing Kennedy class II, III and IV Removable P...AmalKaddah1
1-a. Basic principles for designing the removable partial denture (class I partial denture design)
Introduction.
Objectives and Functions of RPD.
Factors that affect RPD design.
Basic principles for designing Kennedy class I partial denture.
2- b. Basic principles for designing Kennedy class II, III and IV Removable Partial Denture(RPD)
Failures in Fixed Partial Denture
(Prosthodontics FPD- Dental science)
Various types of failures in the fabrication of fixed partial denture
Dr.Sachin Sunny Otta
St.Gregorios Dental College,Kothamangalam,Ernakulam
this presentation has all the techniques in impression making in the fabrication of an RPD.
The presentation is available on request. Mail me at apurvathampi@gmail.com
The patient who requires a single denture opposing a natural or restored dentition challenges the clinician even more than the completely edentulous patient does. This is due to the biomechanical differences in the supporting tissues of the opposing arches. So a proper evaluation, correction of the existing factors and proper sequence of denture construction is necessary to give a more stable prosthesis.
2- b. Basic principles for designing Kennedy class II, III and IV Removable P...AmalKaddah1
1-a. Basic principles for designing the removable partial denture (class I partial denture design)
Introduction.
Objectives and Functions of RPD.
Factors that affect RPD design.
Basic principles for designing Kennedy class I partial denture.
2- b. Basic principles for designing Kennedy class II, III and IV Removable Partial Denture(RPD)
Management of stresses in rpd / orthodontic course by indian dental academyIndian dental academy
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Stress breakers /certified fixed orthodontic courses by Indian dental academy Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
3- Basic principles for designing the removable partial denture Amal Kaddah
Clinical course of Partial Denture
3- Basic principles for designing the removable partial denture
a- Problems and General Principles Applied for Kennedy Class I
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Factory Supply Best Quality Pmk Oil CAS 28578–16–7 PMK Powder in Stockrebeccabio
Factory Supply Best Quality Pmk Oil CAS 28578–16–7 PMK Powder in Stock
Telegram: bmksupplier
signal: +85264872720
threema: TUD4A6YC
You can contact me on Telegram or Threema
Communicate promptly and reply
Free of customs clearance, Double Clearance 100% pass delivery to USA, Canada, Spain, Germany, Netherland, Poland, Italy, Sweden, UK, Czech Republic, Australia, Mexico, Russia, Ukraine, Kazakhstan.Door to door service
Hot Selling Organic intermediates
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
2. Introduction
Removable partial dentures by design are intended to be
placed into and removed from the mouth.
The forces occurring with removable prosthesis function
can be widely distributed and directed, and their effect can
be minimized by appropriate design of the removable
partial denture
3. The strategy of selecting component parts for a
partial denture to help control the movement of the
prosthesis under functional load has been
highlighted as a method to consider for logical
partial denture design.
The requirements for movement control are
generally functions of whether the prosthesis will
be tooth supported or tooth-tissue Supported.
4. Colonel Arthur H. Schmidt (1953) introduced 5
basic principles in designing of Removable Partial
Denture :-
1. Dentist must have a working knowledge of both the
mechanical and biological factors included in R.P.D
design and construction.
2. Any plan of restoration must be based on complete
examination and diagnosis of individual patient.
3. The dentist not the technician should correlate the
pertinent factors and recommend a proper plan of
treatment.
4. A R.P.D should restore form and function without
injury to the tissue.
5. A R.P.D is a form of treatment ,not a care.
5. Difference in Prosthesis support
All forces against fixed partial denture are directed down long axis of abutment
teeth (arrows).
Tooth-supported, or Class III, removable partial denture, like fixed partial denture, is
supported by abutments. Most forces against it are transmitted down long axis of abutment
teeth (arrows). However, limited movement, including a tendency to lift in function, is possible.
6. Of all partial dentures, an all-tooth-supported, or Class III,
partial denture can best resist forces because it, like the
fixed partial denture, is supported by abutment teeth
1 A, Kennedy Class I partially edentulous arch. Major support for denture bases must come from
residual ridges, tooth support from occlusal rests being effective only at anterior portion of each
base. B, Kennedy Class III, mod 1, partially edentulous arch, which provides total tooth support for
prosthesis. Removable partial denture made for this arch is totally supported by rests on properly
prepared occlusal rest seats on four abutment teeth.
Classes I, II, and IV removable partial dentures are
subjected to greater stresses because their support is a
combination of tooth and soft tissue
7. A removable partial
denture in the mouth can
perform the action of two
simple machines, the lever
and the inclined plane
If the lever rests against
its support and a weight is
applied at another point,
rotation or movement will
occur around the support.
The support is known as
the fulcrum, and
movement takes place
around the fulcrum.
8. There are three types of levers, first-, second-,
and third-class, and each magnifies or disguises
the force to a different degree
Top, first-class lever. Fulcrum is in center, resistance is at one end,
and effort, or force, is at opposite end. This is most efficient and
easily controlled lever.
Center, second-class lever with fulcrum at one end, effort at
opposite end, and resistance in center. This type is seen as indirect
retention in removable partial dentures.
Bottom, third-class lever with fulcrum at one end, resistance at
opposite, and effort in center. This class is not encountered in
partial dentures.
9. The inclined plane is the other simple machine to
be concerned with. Forces against the inclined
plane may result in deflection of that which is
applying the force or may result in movement to
the inclined plane. Neither of these results is
desirable.
It is in distal extension removable partial dentures
that the type of prosthesis controlling stress is
important.
The all tooth-supported partial denture is rarely
subjected to induced stresses, because leverage-
type forces are not involved and there are no
fulcrums around which the partial denture may
rotate. Inclined planes are also not a factor when
the partial denture is tooth supported.
10. The distal extension partial denture, on the other
hand, is subjected to rotation around three
principal fulcrums
Horizontal fulcrum line passing
between two principal abutment
teeth controls rotational motion
of denture toward or away from
supporting ridge.
Second rotational fulcrum
extends from occlusal rest on
terminal abutment posteriorly
along crest of residual ridge. This
fulcrum controls rocking, or side-
to-side, movement that takes
place over crest of ridge. In a
Class I arch there are two such
fulcrums.
11. Third fulcrum is vertical and is located in mid-line lingual to anterior
teeth. It controls movement of denture in horizontal plane.
12. Robert B Potter , Ralph C Appleby, and Cliffton D Adams (1967) :
Certain important biomechanical principles apply to the design of
all R.P.D, these are :-
A modified T bar or I bar engaging the distobuccal retentive area
results in action similar to second class lever, when downward
pressure is applied to partial denture, the clasp tip will also have
downward movement thereby minimizing lateral stress on the
abutment tooth.
Extra coronal retainers change the contour of abutment teeth.
Lingual and palatal major connectors must be rigid to transmit
lateral stresses to other parts of the partial denture
13. Differentiation between two main types of
Removable Partial Denture
It is clear that two distinctly different types of removable
partial dentures exist.
Certain points of difference are present between the Kennedy
Class I and Class II types of partial dentures on the one hand
and the Class III type of partial denture on the other.
1. The first consideration is the manner in which each is
supported. The Class I type and the distal extension side of
the Class II type derive their primary support from the tissue
underlying the base and secondary support from the
abutment teeth
The Class III type derives all of its support from the
abutment teeth
14. 2- Second, for reasons directly related to the
manner of support, the method of impression
registration and jaw record required for each
type will vary.
3- Third, the need for some kind of indirect
retention exists in the distal extension type of
partial denture, whereas in the tooth-supported,
Class III type there is no extension base to lift
away from the supporting tissue because of the
action of sticky foods and movement of the
tissue of the mouth against borders of the
denture.
4- Fourth, the manner in which the distal extension
type of partial denture is supported often
necessitates the use of a base material that can
be relined to compensate for tissue changes.
15. Differences in Support
The distal extension partial denture derives its major support from
the residual ridge with its fibrous connective tissue covering. The
length and contour of the residual ridge notably influence the
amount of available support and stability
A, The longer the edentulous area
covered by the denture base, the greater
the potential lever action on the abutment
teeth.
B, Flat ridge will provide good support,
poor stability.
C, Sharp spiny ridge will provide poor
support, poor to fair stability.
D, Displaceable tissue on ridge will
provide poor support and poor stability.
16. Impression Registration
An impression registration for the fabrication of a
partial denture must fulfill the following two
requirements:
The anatomic form and the relationship of the
remaining teeth in the dental arch and the
surrounding soft tissue must be recorded accurately
so that the denture will not exert pressure on those
structures beyond their physiological limits.
The elastic impression
materials,such as irreversible hydrocolloid (alginate),
mercaptan rubber base (Thiokol), silicone impression
materials (both condensation and addition reaction),
and the polyethers
17. The supporting form of the soft tissue underlying
the distal extension base of the partial denture
should be recorded so that firm areas are used as
primary stress-bearing areas and readily
displaceable tissues are not overloaded.
No single impression material can satisfactorily
fulfill both of the previously mentioned
requirements.
Recording the anatomic form of both teeth and
supporting tissue will result in inadequate support
for the distal extension base.
This is because the cast will not represent the
optimum coordinating forms, which necessitates
that the ridge be related to the teeth in a
supportive form.
18. Differences in Clasp Design
A fifth point of difference between the
two main types of removable partial
dentures lies in their requirements for
direct retention
19. The tooth-supported partial denture, being totally
supported by abutment teeth, is retained and stabilized
by a clasp at each end of each edentulous space
The only requirement of such clasps is
that they flex sufficiently during placement and removal of the
denture to pass over the height of contour of the teeth in
approaching or escaping from an undercut area,
Cast retentive arms are generally used for this purpose. These may
be either of the circumferential type, arising from the body of the
clasp and approaching the undercut from an occlusal direction, or
of the bar type, arising from the base of the denture and
approaching the undercut area from a gingival direction.
20. In the combination tooth- and tissue-supported
removable partial dentures,
because of this tissue
ward movement, those elements of a clasp that
lie in an undercut area mesial to the fulcrum for a
distal extension (as is often seen with a distal
rest) must be able to flex sufficiently to dissipate
stresses that otherwise would be transmitted
directly to the abutment tooth as leverage
21. SURVEY LINES
A survey line is a line produced on a cast by a surveyor marking
the greatest prominent of contour in relation to the planned path
of placement of a restoration. (GPT 7)
The survey line marks the height of contour of the tooth.
Blatterfein divided the buccal and lingual surfaces in to two
halves and described them as the near zone , the area which is
closer to the edentulous space and the far zone , the area away
from the edentulous space. The proximal surface can also be
described in the same manner.
Survey lines can be classified as:
HIGH SURVEY LINE
MEDIUM SURVEY LINE
LOW SURVEY LINE
DIAGONAL SURVEY LINE
22. HIGH SURVEY LINE PASSES FROM THE OCCLUSAL
THIRD IN THE NEAR ZONE TO THE OCCLUSAL THIRD
IN THE FAR ZONE.UNDERCUT WILL BE DEEP-
A WROUGHT WIRE CLASP WHICH IS MORE FLEXIBLE
SHOULD BE USED.
MEDIUM SURVEY LINE PASSES FROM THE
OCCLUSAL THIRD IN THE NEAR ZONE TO THE
MIDDLE THIRD IN THE FAR ZONE. AKER’S OR
ROACH CLASP IS USED.
LOW SURVEY LINE IS CLOSER TO
THE CERVICAL THIRD OF THE
TOOTH IN BOTH NEAR AND FAR
ZONE. A MODIFIED T- CLASP IS
USED.
DIAGONAL SURVEY LINE RUNS FROM OCCLUSAL
THIRD IN THE NEAR ZONE TO CERVICAL THIRD OF
FAR ZONE.A REVERSE CIRCLET CLASP IS USED.
23. Clasp Design
Circumferential Cast Clasp
The conventional circumferential cast clasp originating from a
distal occlusal rest on the terminal abutment tooth and
engaging a mesio buccal retentive undercut should not be used
on a distal extension removable partial denture.
The terminal of this clasp reacts to movement of the denture
base toward the tissue by placing a distal tipping, or torquing,
force on the abutment tooth
This particular force is the most destructive force a retentive
clasp can exert. This clasping concept must be avoided at all
costs.
24. The reverse circlet, a cast circumferential clasp that
approaches a distobuccal undercut from the mesial
surface of a terminal abutment tooth, is acceptable
The effect on the abutment tooth is reversed from that
of the conventional circumferential clasp.
As an occlusal load is applied to the denture base, the
retentive terminal moves further gingivally into the
undercut area and loses contact with the abutment
tooth. In this manner torque is not transmitted to the
abutment tooth
A reverse circlet clasp, approaching a
distobuccal undercut from mesial occlusal
surface, may be acceptable for a distal
extension partial denture. As denture base
moves toward the tissue, retentive clasp tip
will tend to move into an area of greater
undercut (arrow). This action releases
torquing forces that can damage an
abutment tooth
25. Vertical Projection, or Bar, Clasp
The vertical projection, or bar, clasp is used on the terminal
abutment tooth on a distal extension partial denture when the
retentive undercut is located on the distobuccal surface.
It is never indicated when the tooth has a mesiobuccal undercut.
The bar clasp functions in a manner similar to the reverse
circumferential clasp.
As the denture base is loaded toward the tissue, the retentive tip
of the T clasp rotates gingivally to release the stress being
transmitted to the abutment tooth
The vertical projection T Clasp releases
torsional stress on terminal abutment
tooth. This releasing action is accomplished
when retentive clasp tip rotates gingivally
into a greater undercut as tissueward
forces are applied to denture base
(arrows). Rotation takes place around
distal occlusal rest.
26. One school of thought on the philosophy of removable partial
denture design has advocated omitting the distal occlusal rest from
the terminal abutment in favor of a mesial rest when a bar clasp is
used.
advantage claimed for moving the occlusal rest more anteriorly is
that the lever arm (the distance from the rest to the denture base)
is increased, which causes the force directed toward the residual
ridge to be more vertical and thus better tolerated by the ridge
One advantage claimed for eliminating distal occlusal
rest (A) and placing a mesial rest more anteriorly
(B) is that lever arm, represented by distance from
rest to denture base, is increased.
This increase in length makes rotational action
caused by up-and-down movement of denture base
in function more vertical.
A vertical force is better tolerated by ridge than is a
horizontal oblique force.
27. Combination Clasp
When a mesiobuccal undercut exists on an abutment
tooth adjacent to a distal extension edentulous ridge,
the combination clasp can be employed to reduce the
stress transmitted to the abutment tooth.
Wrought alloy wire, by virtue of its internal structure,
is more flexible than a cast clasp.
It can flex in any spatial plane, whereas a cast clasp
flexes in the horizontal plane only.
The wrought wire retentive arm has a stress-breaking
action that can absorb torsional stress in both the
vertical and horizontal planes.
28. ESSENTIALS OF PARTIAL DENTURE
DESIGN
To develop the design, it is first necessary to determine how the
partial denture is to be supported
In an entirely tooth-supported partial denture the potential
support an abutment tooth can provide, consideration should be
given to:
(1) periodontal health
(2) crown and root morphologies
(3) crown-to-root ratio
(4) bone index area (how the tooth has responded to previous
stress)
(5) location of the tooth in the arch
(6) relationship of the tooth to other support units (length of
edentulous span)
(7) the opposing dentition.
29. In a tooth- and tissue-supported partial
denture consideration must be given to:
(1) the quality of the residual ridge, which includes
contour, quality of the supporting bone and quality
of the supporting mucosa
(2) the extent to which the residual ridge will be
covered by the denture base
(3) the type and accuracy of the impression
registration;
(4) the accuracy of the denture base;
(5) the design characteristics of the component
parts of the partial denture framework
(6) the anticipated occlusal load.
30. The second step in systematically developing the
design for any removable partial denture is to
connect the tooth and tissue support units
Major connectors must be rigid so that forces
applied to any portion of the denture can be
effectively distributed to the supporting
structures.
Minor connectors arising from the major
connector make it possible to transfer functional
stress to each abutment tooth through its
connection to the corresponding rest and also to
transfer the effect of the retainers, rests, and
stabilizing components to the remainder of the
denture and throughout the dental arch
31. The third step is to determine how the removable
partial denture is to be retained.
Retention is accomplished by mechanical
retaining elements (clasps), The key to selecting
a successful clasp design for any given situation
is to choose one that will:
(1) avoid direct transmission of tipping or
torquing forces to the abutment
(2) accommodate the basic principles of clasp
design
(3) provide retention against reasonable
dislodging forces
(4) be compatible with undercut location, tissue
contour, and esthetic desires of the patient.
32. The fourth step is to connect the
retention units to the support units. If
direct and indirect retainers are to
function as designed, each must be
rigidly attached to the major connector.
The fifth and last step in this systematic
approach to design is to outline and
join the edentulous area to the already
established design components.
33. Controlling Stress by Design
Considerations
Forces of Adhesion and Cohesion
To secure the maximum
possible retention through the use of the forces
of adhesion and cohesion, the denture base
should cover the maximum area of available
support and must be accurately adapted to the
underlying mucosa
To enhance quality of
retention through
adhesion and cohesion,
denture base (arrows]
must fit edentulous ridge
accurately and must
cover maximum area of
available support
34. Frictional Control
The partial denture should be designed so that
guide planes are created on as many teeth as
possible
Term guiding plane is defined as two or more
parallel, vertical surfaces of abutment teeth, so
shaped to direct a prosthesis during placement
and removal.
. Development of guide planes on
proximal surfaces of teeth adjacent
to edentulous spaces will increase
retention of partial denture by
frictional contact. These guide planes
may be created in enamel surfaces
35. Quadrilateral Configuration
The quadrilateral configuration is indicated most
often for Class III arches particularly when there is a
modification space on the opposite side of the arch.
A retentive clasp should be positioned on each
abutment tooth adjacent to the edentulous spaces.
This results in the denture being confined within the
outline of the four clasps, and leverage on the
denture is effectively neutralized.
36. Tripod Configuration
Tripod clasping is used primarily for Class II
arches. If there is a modification space on the
dentulous side, the teeth anterior and posterior
to the space are clasped to bring about the tripod
configuration.
This design is not as effective as the quadrilateral
configuration, but is most effective in neutralizing
leverage in the Class II situation.
37. Bilateral Configuration
most removable partial dentures fall into the
bilateral distal extension group, or Class I
the single retentive clasp on each side of the arch
should be located near the center of the dental
arch or denture bearing area.
In the bilateral configuration the clasps exert
little neutralizing effect on the leverage-induced
stresses generated by the denture base.
38. MAJOR AND MINOR CONNECTORS
Major connectors : The part of the partial
removable denture prosthesis that joins the
components of one side of the arch to those on
the opposite side.(GPT7)
Major connectors should be rigid necessary to
provide proper distribution of forces to and
from the supporting components
Minor connectors : The connecting link between
the major connector or base of a partial
removable denture prosthesis and the other
units of the prosthesis such as the clasp
assembly , indirect retainers ,occlusal rests or
cingulum rests. (GPT 7)
39. Major Connector
In the mandibular arch the lingual plate
major connector that is properly supported
by rests can aid in the distribution of
functional stresses to the remaining teeth
Major connector, in this case anterior
lingual plate, can help control functional
stresses on remaining teeth. By contacting
a number of teeth, major connector
reduces amount of force transmitted to
each tooth. Major connector must be
supported by rests at each end of anterior
span
In the maxillary arch the use of a
broad palatal major connector that
contacts several of the remaining
natural teeth through lingual plating
can distribute stress over a large
area
40. Minor Connector
The most intimate tooth-to-partial denture contact
takes place between the minor connector joining
the clasp assembly to the major connector and the
guiding planes on the abutment tooth surfaces
This close metal-to-enamel contact serves two
purposes:-
1. First, it offers horizontal stability to the partial
denture against lateral forces on the prosthesis.
The tooth with its supporting bone helps dissipate
these displacing stresses,
2. Second, through the contact of the minor
connector and the abutment tooth, the tooth
receives stabilization against lateral stresses.
41. DIRECT RETAINERS FOR TOOTH-
SUPPORTED PARTIAL DENTURES
DIRECT RETAINER : is that component of a partial
removable dental prosthesis used to retain and
prevent dislodgement, consisting of a clasp
assemble and precision attachment. (GPT 7)
Clasp assembly:
The part of the removable dental prosthesis that acts
as a direct retainer and or a stabilizer for a
prosthesis by partially encompassing or
contacting an abutment tooth.(GPT 7)
Precision attachment :
An interlocking device ,one component of which is
fixed to an abutment or abutments and the other
is integrated to a removable dental prosthesis in
order to stabilize and/or to retain it. (GPT 7)
KEY AND KEYWAYS
42. functions:
A. To retain the prosthesis against reasonable dislodging forces
without damage to the abutment teeth and
B. To aid in resisting any tendency of the denture to be displaced in a
horizontal plane.
The prosthesis cannot move tissueward as the rest supports the
retentive components of the clasp assembly.
There should be no movement away from the tissue and therefore
no rotation about a fulcrum because a direct retainer secures the
retentive component.
Intracoronal (frictional) retainers are ideal for tooth-supported
restorations and offer esthetic advantages that are not possible
with extracoronal (clasp) retainers.
DALBO EXTRACORONAL ATTACHMENT
43. The clasp retainer must not impinge on
gingival tissue and must not exert
excessive torque on the abutment tooth
during placement and removal.
It must be located the least distance into
the tooth undercut for adequate retention,
and it must be designed with a minimum of
bulk and tooth contact.
The bar clasp arm should be used only
when the area for retention lies close to
the gingival margin of the tooth.
With an excessive tissue undercut, re
contouring the abutment and using some
type of circumferential direct retainer is
advisable.
Circumferential clasp
Occlusal view of bar clasp
44. DIRECT RETAINERS FOR DISTAL
EXTENSION PARTIAL DENTURES
The retainer should retain the
prosthesis, and also be able to flex
or disengage when the denture base
moves tissueward under function.
Thus the retainer may act as a
stress-breaker.
The clasp arm must be freely
flexible in any direction, as dictated
by the stresses applied.
Round, tapered clasp forms offer
advantages of greater and more
universal flexibility, less tooth
contact, and better esthetics.
45. Allison. G. James (1955) :-
Explained stress breakers which automatically return the saddle
to rest position following displacement.
Basic principle involved is that portion of appliance directly
attached to the abutment teeth, the anterior part of palatal
casting shall be rigid, and with minimum motion possible allowed
between it and the abutment.
The saddles will be attached to this rigid portion by a narrow
isthmus in the saddle casting as close as feasible to the midline of
the palatal appliance.
46. INDIRECT RETAINERS
Indirect retainers :are the components of the partial
removable dental prosthesis that assists the
direct retainers in preventing displacement of
the distal extension denture by functioning
through lever action on the opposite side of the
fulcrum line when the denture base moves away
from the tissues in pure rotation around the
fulcrum line. (GPT 7)
It must be placed as far anterior from the
fulcrum line.
It must be placed on a rest seat prepared on an
abutment tooth that is capable of withstanding
the forces placed on it.
48. Indirect retainer cannot function
effectively on an inclined tooth surface,
nor on a single weak incisor tooth
,either a canine or premolar tooth
should be used for the support of an
indirect retainer.
Function :
A. Restrict movement of a distal extension
base away from the basal seat tissue.
B. Support for major connectors.
49. ADDITIONAL CONSIDERATIONS
INFLUENCING DESIGN
Use of a Splint Bar for Denture Support
when the edentulous span is too large to ensure
adequate support from the adjacent teeth,
An anterior splint bar may be attached to the
adjacent abutment teeth in such a manner that fixed
splinting of the abutment teeth results, with a
smooth, contoured bar resting lightly on the gingival
tissue to support the removable partial denture
A, Splint bar attached to double
abutments on either side of
arch.
. B and C, Denture framework
designed to fit and be supported
by splint bar.
50. Lower canines and lateral incisors splinted together with splint
bar. Longevity of these teeth is greatly enhanced by splinting,
and enhanced stability of the removable partial denture is
provided.
Tissue surfaces are minimally contacted by rounded form of
lower portion of bar. Anterior and posterior slopes of splint bar
must be compatible with path of placement of denture.
51. Internal Clip Attachment
The internal clip attachment differs from the
splint bar in that the internal clip attachment
provides both support and retention from the
connecting bar
Canines have been endodontically
treated and are splinted together with
round, straight connecting bar, slightly
elevated from residual ridge. Retaining
left molar as abutment will
immeasurably contribute to stability of
removable partial denture.
B, Tissue surface of completed
mandibular restoration containing
internal clip attachment.
52. Overlay Abutment as Support for a Denture
Base
Every consideration should be directed to
preventing the need for a distal extension
removable partial denture.
In many instances it is possible to salvage the
roots and a portion of the crown of a badly
broken-down molar through endodontic
treatment.
53. Use of a Component Partial to Gain
Support
A component partial is a removable partial
denture in which the framework is designed and
fabricated in separate parts. The tooth support
and tissue supported components are individually
fabricated, and the two are joined with a high
impact acrylic resin to become a single, rigid
functioning unit
A, Design of component part removable
partial denture.
B, Tooth support component individually
fabricated and fit to the master cast.
C, Tissue support component individually
fabricated and fit to the master cast.
D, Tooth and tissue support components
assembled on cast.
E, Components joined with high-impact
resin.
54. EXAMPLES OF SYSTEMATIC APPROACH
TO DESIGN
Class III Removable Partial Denture
Removable partial denture in maxillary Class III,
Mod 1 arch. Design consists of single palatal
connecting a single tooth space to a 2-tooth space.
The impression for such modification spaces does
not require tissues to be captured in a supportive
form. A palatal strap major connector is less bulky
and for most patients would be more comfortable
than a thicker bar design.
55. Kennedy Class II Removable Partial
Dentures
The Kennedy Class II partial denture actually
may be a combination of both tissue-supported
and tooth supported restorations. The distal
extension base must have adequate tissue
support, whereas tooth-supported bases
elsewhere in the arch may be made to fit the
anatomic form of the underlying ridge
56. Bibliography
Stewart : Clinical Removable Partial
Prosthodontics,second edition ,Ishiyaku
European American publishers.
Carr, McGivney, Brown: McCracken’s
Removable Partial Prosthodontics, eleventh
edition ,Mosby publishers.
Applegate : Essentials of Removable Partial
Denture Prosthesis., saunders Company.