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.
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
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 specifically deals with the maxillary and mandibular Major connectors used in a cast partial denture. it also mentions the uses, advantages and disadvantages of each,
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
This presentation specifically deals with the maxillary and mandibular Major connectors used in a cast partial denture. it also mentions the uses, advantages and disadvantages of each,
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 scope of fixed prosthodontics treatment can range from the restoration of a single tooth to the rehabilitation of the entire occlusion. Single teeth can be restored to full function, and improvement in
esthetics can be achieved. Missing teeth can be replaced with fixed prostheses that will improve patient comfort and masticatory ability, maintain the health and integrity of the dental arches, and, in many instances, elevate the patient’s self-image.
This presentation includes brief history, classification and definition of overdentures and explains in details about the various tooth supported overdentures. It explains about bar attachments, ball attachments, telecsopic dentures etc.
Description :
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
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Description :
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
Abutment /certified fixed orthodontic courses by Indian dental academy Indian dental academy
Description :
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
Description :
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
Diagnosis and treatment planning in implants/ cosmetic dentistry trainingIndian dental academy
Indian Dental Academy: will be one of the most relevant and exciting
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practice,Offers certified courses in Dental
implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic
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Diagnosis and treatment planning in implants / esthetic dentistry coursesIndian 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
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Diagnosis and treatment planning in implants 2. / dental implant courses by ...Indian dental academy
Description :
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
Diagnosis and treatment planning in implants 2./prosthodontic coursesIndian 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.for more details please visit
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Diagnosis and treatment planning in implants 2. /certified fixed orthodontic ...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: 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.
A teamwork of specialized dentists, general dentists, dental assistants, dental hygienists, and dental technicians is needed in providing good oral health services. A bad workman always blames his tools. It is mandatory that the associated dental personnel have adequate knowledge of the material science. This not only enables them to select and handle the appropriate materials for the given clinical situation, but also ensures optimal properties of the material.
Currently, complete dentures are mainly designed and fabricated using conventional methods, which involve a broad series of clinical and laboratory procedures.
Dentists may want to consider using an update of a unique complete denture technique that saves total chair time and, therefore, decreases cost.
It is possible to fabricate a complete denture with different techniques in minimal visit. These techniques has positive benefits saving a lot of time and materials for both the patient and the clinician.
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.
Fixed prosthodontic treatment can offer exceptional satisfaction for both patient and the dentist. Fixed Prosthodontics can transform an unhealthy, unattractive dentition with poor function into a comfortable, healthy occlusion capable of giving years of further service while greatly enhancing esthetics.
Nothing is more important in the construction of fixed partial dentures than an adequate diagnosis and a well-devised treatment plan. Although these two subjects are usually considered together. Astute dentists must recognize their subtle differences. Diagnosis is an evaluation of the condition of the patient when he presents for treatment. Treatment planning concerns the treatment procedures by which the dentist will restore the patient to an optimum state of dental health.
The human mandible can be related to the maxilla in several positions in the horizontal plane. Among these centric relation is a significant position, because of its usefulness in relating the dentulous and edentulous mandible to maxilla, where the teeth , muscles and temporomandibular joint function in harmony. It is a position of occluso-articular harmony.
Muscles of mastication are the group of muscles that help in movement of the mandible as during chewing and speech. We need to study these muscles as they control the opening & closing the mouth & their role in the equilibrium created within the mouth. They also play a role in the configuration of face.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Factory Supply Best Quality Pmk Oil CAS 28578–16–7 PMK Powder in Stockrebeccabio
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Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
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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.
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Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
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
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.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
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is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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
2. CONTENTS
1. Introduction
2. Diagnostic Casts
3. Radiographic Examination
4. Factors influencing Abutment selection:
a. Crown length
b. Crown Form
c. Crown – root Ratio
d. Periodontal ligament Area
e. Root Configuration
f. Root Proximities
3. f. Periodontal examination.
g. Long- Axis Relationship
h. Arch Form
i. Span Length
j. Unrestored Abutments
l. Endodontically Treated Abutments
m. Rigidity of Prosthesis
n. Margin Location
4. o. Occlusal Anatomy
p. Pontic Tissue Contact
q. Available Tooth Structure
r. Age of Patient
s. Vitality testing of the pulp
t. Long term Abutment Prognosis
5. 5. Special Problems
a. Pier Abutments
b. Tilted Molars Abutments
c. Canine replacement fixed partial denture
d. Abutments for Cantilever FPD.
6. Questionable abutments
7. Summary & Conclusion
8. References
6. INTRODUCTION
• 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.
7. DEFINITION
• A tooth, a portion of a tooth, or that portion of a dental implant
that serves to support and/or retain a prosthesis.
(GPT 9)
8. DIAGNOSTIC CASTS
A life size reproduction of the parts of the oral cavity and or facial
structures for the purpose of study and treatment planning.
Articulated diagnostic casts are essential in planning fixed
prosthodontic treatment.
To accomplish their intended goal, they must be accurate
reproductions of the maxillary and mandibular arches made from
distortion free alginate impressions.
The diagnostic casts should be mounted on a semiadjustable
articulator with a face bow after bite registration.
9. RADIOGRAPHIC EXAMINATION
• Periapical and bitewing films are most important in selection of
abutment teeth. On occasion additional views, such as TMJ radiographs
for patients with TMJ dysfunction and panoramic radiograph can also be
useful.
• Radiographs provide information that cannot be determined clinically
and however are not a primary source of diagnostic information.
• An intraoral radiographic examination reveals:
• Remaining bone support
• Root number and morphology (long, short, slender, broad, bifurcated, fused,
dilacerated etc.) and root proximity.
• Quality of supporting bone, trabecular patterns and reactions to functional
changes.
• Width of periodontal ligament spaces and evidence of Trauma From Occlusion
10. • Areas of vertical and horizontal osseous resorption and furcation invasions
• Axial inclination of teeth(degree of non parallelism if present)
• Continuity and integrity of lamina dura.
• Pulpal morphology and previous endodontic treatment with or without post
and cores.
• Presence of apical disease, root resorption or root fractures.
• Retained root fragments, radiolucent areas, calcifications, foreign bodies or
impacted teeth.
• Presence of carious lesions, the condition of existing restorations, and
proximity of carious lesion to the pulp.
• Proximity of carious lesions and restorations to alveolar crest.
11. • The functional demand on the tissue of one person may be quite
different from those of another. The tissue response and tolerance
vary among individuals; therefore no two abutment teeth will
react exactly the same under similar conditions.
• An understanding of the favorable indications and reasonable
limitations of abutments for fixed partial dentures is essential.
12. FACTORS INFLUENCING ABUTMENT
SELECTION
• The choice and number of abutments are determined
by a combination of load- bearing ability of the
abutment teeth plus the forces and stresses to which
these will be subjected. The number of roots, their
shape, length, alignment, and bone height has a direct
relation to the load- bearing capacity of teeth. The
shorter, more tapered the root and lower the bone
level, the less satisfactory the tooth will be as an
abutment.
13. a. CROWN LENGTH
• Teeth must have adequate occlusocervical crown length to
achieve sufficient retention. Teeth with short clinical crowns often
do not provide satisfactory retention unless full – coverage
preparations are used or additional length is achieved through
periodontal surgery.
14. b. CROWN FORM
• Some teeth have tapered crown form, which interferes with
preparation parallelism, necessitating full coverage retainers to
improve their retentive and esthetic qualities.
Ex: include anterior teeth with poorly developed cingulam and
short proximal walls and mandibular premolars with poorly
developed lingual cusps and short proximal surfaces. Also, some
incisors poses very thin highly translucent incisal edges making
use of partial coverage retainers esthetically unacceptable.
15. c. CROWN – ROOT RATIO
Definition:
Physical relationship between the portion of tooth within
alveolar bone compared with the portion not within the
alveolar bone, as determined by radiograph. (GPT-8)
• This ratio is a measure of the length of tooth occlusal to the
alveolar crest of bone compared with length of root embedded
in bone.
• The optimum crown- root ratio for tooth to be utilized as a
fixed partial denture abutment is 2:3. A ratio of 1:1 is the
minimum ratio that is acceptable for a prospective abutment
under normal conditions (such as number of teeth being replaced,
tooth mobility and overall periodontal health is good)
16. Optimum C: R ratio is 2:3 A ratio of 1:1 is minimum
in FPD abutment that is acceptable
17. Biomechanical concept:
Represents Class I lever :
• Crown -> Effort arm. (E)
• Root ->Resistance arm. (R)
• Centre of rotation of tooth -> Middle of root that is embedded in
alveolar bone
Loss of alveolar bone: Chance of harmful lateral increases.
• Crown portion (effort arm) : Increase.
• Root portion (resistance arm) : Decrease.
• Centre of rotation moves apically.
E=1 R=2
18. d. PDL AREA AND SURFACE AREA
• This is an important point in the assessment of abutment’s
suitability from a periodontal standpoint.
Root surface area or the area of periodontal ligament attachment of
the root to the bone
Large teeth Greater surface area Better ability to bear
added stress.
Periodontal disease Loss of supporting bone Lesser
capacity to serve as
abutment.
19. • Tylman in 1970 stated that 2 abutment teeth could support 2
pontics.
• ANTE suggested in 1926 that it was unwise to provide a FPD
when the root surface area of the abutment was less than the root
surface area of the teeth being replaced; this has been adopted
and reinforced by other authors (Johnston, Dykema) in 1971 as
ANTE’s LAW. This rule was based on the engineering principles
used for designing bridges
• ANTE’s LAW – Irwin H. Ante (Toronto, Ontario Canada)
Is an eponym in FPD Prosthodontics for the observation
that the combined pericemental area of all abutment teeth
supporting a FPD should be equal to or greater in
pericemental area than the tooth or teeth being replaced
20. Combined root surface area of II
premolar& II molar (A2p+A2m) is
greater than that of I molar being
replaced (A1m)
Combined root surface area of I
premolar and II molar (A1p+A2m) is
approx. equal to that of the teeth
being replaced (A2p+A1m)
The combined root surface area
of the canine & the second
molar is exceeded by that of
the teeth to be replaced. A fixed
partial denture would be a poor
risk in this situation
22. • Factors Modifying ANTE’s LAW
Condition Existing Probable modification in ANTE’s LAW
1. Bone loss from periodontal disease Increase the number of abutments.
2. Mesial or distal tipping or changes in axial
inclination.
Increase the number of abutments.
3. Migration (bodily movement)of abutment
teeth decreasing M-D length of
edentulous area.
Decrease the number of abutments used (less
pericemental support required)
4. Less than favorable opposing arch
relationship producing increased occlusal
load.
Increase the number of abutments used for
support.
5. Endodontically restored abutment teeth
with root resections.
Increase the number of abutments
6. Arch form situations creating greater
leverage factors.
Increase the number of abutments.
7. Tooth mobility created after osseous
surgery.
Increase the number of abutments(splinting
procedure)
23. e. ROOT CONFIGURATION
Roots that are broader
labiolinguallly than they are
mesiodistally are preferable to
roots that are round in cross –
section.
Multirooted posterior teeth
with widely separated roots will
offer better periodontal support
than roots that are short
converge,
24. • A tooth with conical roots can be used as an abutment if all other
factors are optimal.
• Irregularly shaped, multiple, divergent roots offer better
prognosis.
• A well aligned tooth will provide better support than a tilted one.
Alignment can be improved with orthodontic treatment.
25. f. ROOT PROXIMITIES
• There must be adequate clearance between the roots of
proposed abutments to permit the development of physiologic
embrasures in completed prosthesis.
• Malpositioned anterior teeth and the mesiobuccal roots of
maxillary molars often present unfavorable root proximities
where desired embrasure form is not possible.
• Solution to root proximity: Selective extraction or root
resection procedures
26. g. PERIODONTAL DISEASE
• Healthy periodontal tissue is prerequisite for all fixed
restorations.
• Abutment with bone loss needs careful assessment:
• Conical shape of roots: with 1/3rd of root length exposed, ½ of the
supporting are is lost.
• Lengthened clinical crown leads to greater leverage force.
• Successful fixed prosthesis with severely reduced periodontal
support, is assured when periodontal tissues have been returned
to excellent health, and long term maintenance has been ensured,
otherwise results will be disastrous.
27. • Periodontal assessment
An examination of the periodontal tissues should be made. The
aim is to provide a basic screening of the tissues and to obtain an
indication of the treatment requirements of the patient.
• Mobility
• Recession
• Pocket
• Furcation
28. h. LONG AXIS RELATIONSHIP
• The architecture of periodontal ligament is such that forces are
withstood best when they are directed along the long axis of the
tooth.
• A severely inclined tooth will not withstand forces as well as one
that is erect.
• Inclined tooth as abutment: Shorter edentulous span with less
occlusal force.
• Common path of insertion for all retainers:
Conventional FPD: Less then 25° inclination.
Resin-bonded FPD: Less then 15° inclination mesio-distally and
same plane facio-lingually.
Evaluation: Diagnostic casts with a dental surveyor.
Radiographs.
29. i. ARCH FORM
• When pontics lie outside the interabutment axis line, the pontics
act as a lever arm, which can produce a torquing movement.
Common problem in replacing all four maxillary incisors.
• Solution:
Additional retention in opposite direction from the lever arm and at a
distance from the inter-abutment axis equal to the length of the lever
arm.
The first premolars sometimes are used as secondary abutments for a
maxillary four pontic canine-to-canine FPD
30. AB- fulcrum line
FG- the distance the pontics extend
anteriorly to fulcrum line.
CD – counterbalancing retention by
including the I premolars as abutments
31. j. SPAN LENGTH
• In addition to the increased load placed on the periodontal ligament by a
long span fixed partial denture, longer spans are less rigid.
• Bending or deflection varies directly with the cube of the length and
inversely with the cube of the occlusogingival thickness of the pontic.
• Compared with a fixed partial denture having a single tooth pontic span,
a two tooth pontic span will bend 8 times as much. A three tooth pontic
will bend 27 times as much as a single pontic.
32. Disadvantages of Longer pontic span:
Potential for producing more torquing forces abutment.
Less rigidity
33. • To minimize flexing caused by long and/or thin spans:
• Pontic designs with a greater occluso-gingival dimension
• The prosthesis may also be fabricated of an alloy with higher yield
strength, such as nickel-chromium
• Double abutment
Retainers on secondary abutments must be at least as retentive as the
retainers on the primary abutments. As the retainer on secondary
abutments will be placed in tension when the pontic flexes, with
primary abutment acting as fulcrum.
34. k. UNRESTORED ABUTMENTS
• An unrestored, caries free tooth is an ideal abutment. It can be
prepared conservatively for a strong retentive restoration with
optimum esthetics.
• In an adult patient, an unrestored tooth can be safely prepared
without affecting the pulp as long as the design and technique of
tooth preparation are wisely chosen.
35. l. ENDODONTICALLY TREATED ABUTMENTS
• Teeth in which the pulpal health is doubtful should be
endodontically treated before initiating fixed prosthesis.
• Although a direct pulp caps maybe acceptable, risk for a simple
amalgam or composite resin, a conventional endodontic
treatment is normally preferred for cast restorations, especially
where the later need for endodontic treatment would jeopardize
the overall success of treatment.
• Such endodontically treated teeth serve well as abutment with
post and core foundation for retention and strength. Sometimes
its better to remove badly damaged tooth rather than attempting
endodontic treatment.
• Can not be selected for cantilever FPD.
36. m. RIGIDITY
• The lack of sufficient rigidity in a fixed prosthesis is a frequent
cause of failure. Rigidity is obtained by use of the proper
materials arranged in the correct shape form and thickness in
regard to the forces acting upon them.
• Excessive occlusal forces cause loosening of prosthesis through
flexure or can induce ceramic fracture. The force can also cause
tooth mobility, particularly in presence of decreased bone
support.
• Flexure can cause damage to the abutments and may result in
eventual loosening of the retainers, and fatigue of the metal. The
induced stresses must not exceed the yield strength of the alloy.
37. n. MARGIN LOCATION
• Sound tooth enamel cannot be improved biologically or
esthetically. Therefore when conditions permit, margins of
restorations should be kept away from the gingival tissues. The
most accurate margin for any restorative material irritates the
gingiva when it is extended beneath the free margin.
38. o. OCCLUSAL ANATOMY
• Natures own anatomy and contour should be recreated in all
restorations.
• Has an indirect influence on the loads transmitted.
• Ridges and grooves increase the sharpness and shearing action of
teeth and reduce friction between opposing surfaces by keeping
the contacting area to minimum.
• Permits the most efficient mastication of food, thus reducing the
load transmitted.
• Attrited teeth need more muscular power and longer and more
masticatory strokes in order to chew food enough.
39. Factors affecting occlusal forces:
Degree of muscular activity.
Habits such as bruxism.
Number of teeth being replaced.
Leverage on the bridge.
Adequacy of bone support.
Results of excessive occlusal forces:
Loosening of prosthesis through flexure.
Ceramic fracture.
Tooth mobility (In presence of decreased bone support).
40. Replacement strategies:
Buccolingual width of pontic should harmonize with
buccolingual dimension of natural unmutilated teeth, and
recreate the normal buccal and lingual form to the height of
contour.
The total meso-distal width of the cusps of abutment should be
equal or exceed that of pontics.
41. p. PONTIC TISSUE CONTACT
• The tissue contacting the surfaces on the pontic should be
convex, smooth and free of porosity. The area of contact should
be minimal, free of pressure and thought of as having saliva
contact rather than tissue contact.
42. q. AVAILABLE TOOTH STRUCTURE
• The size, number and location of carious lesions or restorations in
tooth affect whether full or partial coverage retainers are
indicated.
• Extensive defective restorations or fractures require intentional
endodontic therapy or post and core fabrication to provide a
sufficiently retentive and resistant form to the preparations.
• Crown lengthening maybe indicated to expose sound tooth
coronal to biologic width when caries, restorations fractures are
in proximity to alveolar crest.
43. r. AGE
• Fixed Partial Denture is usually contraindicated adolescents ,
Because:
• Teeth are not fully erupted.
• Excessively large pulp horns.
Treatment options:
Space maintainer: Holds abutment and opposing teeth in
position.
Minimal tooth reduction: Prosthesis considered temporary
and remade when pulp size permits.
44. s. VITALITY TESTING OF THE PULP
• Vitality of the tooth may be tested using either electrical or
thermal stimulation. Electrical testing will require a charge to be
applied to the tooth. The charge is generated by a machine and
the patient becomes part of the circuit when the tip is applied to
the tooth.
• Thermal stimulation may be through either cold or heat, but cold
stimulation is preferred. This is done using a ice stick or a pledget
of cotton wool soaked in ethyl chloride, which will give a quick
response. However, a more intense cold stimulus can be provided
by use of dry ice.
• This way the prospective abutment teeth are tested for pulp
vitality, if pulp in non- vital it should be endodontically treated
before using as abutment for a FPD
45. t. LONG TERM ABUTMENT PROGNOSIS
• When there is some question of the ability of remaining supporting
structures to accept additional occlusal forces, the bilateral bracing
afforded by a removable prosthesis may be advantageous.
• Also a tooth with sufficient loss of periodontal support and
questionable long term prognosis may be best treated with a
removable prosthesis.
Overloading of abutments:
• The ability of abutment teeth to accept applied forces without
drifting or becoming mobile must be estimated and has a direct
influence on prosthodontic treatment plan.
• These forces are severe during Parafunctional grinding and clenching
and need to be eliminated during restoration of damaged dentition.
46. SPECIAL PROBLEMS
• PIER ABUTMENTS/ INTERMEDIATE ABUTMENTS
Definition:
A natural tooth located between terminal abutments that serve to
support a fixed or removable partial denture.
47. Completely rigid restoration: Contraindicated..
1. Physiologic tooth movement:
Faciolingual 56 to 108μm.
Intrusion 28μm.
Independent in direction and magnitude:
Tendency for prosthesis to flex.
Stress concentration around abutments.
2. Arch position of abutment:
Forces transmitted to terminal retainers as a result of middle
abutment acting as a fulcrum, causes failure of weaker retainer.
3. Disparity in retentive capacity:
Retention: Smaller anterior tooth < Larger posterior tooth.
Dislodgement of anterior retainer
48. • The use of a non-rigid connector has been recommended to
reduce this hazard. It Broken stress mechanical union of retainer
and pontic.
• key way : Distal contours of pier a abutment
• Key: Mesial side of the distal pontic
49. Advantages:
• Movement prevents the transfer of stress from segment being
loaded to the rest of the FPD.
• Transfers shear stress to supporting bone rather then
concentrating it in connector.
• Minimize mesio-distal torquing while permitting them to move
independently.
Disadvantages:
• Not preferred in teeth with decreased periodontal attachment.
• Supraeruption of key and posterior unit when opposed by RPD
or no teeth and anterior three unit by natural teeth.
50. • TILTED MOLARS ABUTMETS
• Discrepancy in long axis of molar and premolar makes it
impossible to achieve common path of insertion.
• 3rd molar tipped with tilted 2nd molar prevents complete
seating of FPD
51. ADJUSTMENT FOR TILTED MOLAR:
If the encroachment is slight, the problem can be remedied by
restoring or recontouring the mesial surface of the third molar
with an overtapered preparation on the second molar.
If the tilting is severe, other corrective measure will have to be
followed. The treatment of choice is uprighting of the molar by
orthodontic treatment.
A proximal half crown can be used as a retainer on the distal
abutment.
52. • CANINE REPLACEMENT FIXED PARTIAL DENTURE
This is a problem because often the canine lies outside the
interabutment axis. The abutments are the lateral incisor, usually
the weakest in the entire arch and the first premolar, the weakest
posterior tooth. A FPD replacing maxillary canine is subjected to
more stress than that replacing a mandibular canine since forces
are transmitted outward on the maxillary arch.
So the support from secondary abutments will have to be
considered.
Edentulous spaces created by the loss of canine and any
contiguous teeth is best restored with Implants.
53. • ABUTMENT SELECTION FOR CANTILEVER FPD
Cantilever FPD is one that has an abutment or abutments at one
end only, with the other end of the pontic remaining unattached.
This is a potentially destructive design with the lever arm created
by the pontic.
Abutment teeth for cantilever FPDs should be evaluated for
lengthy roots with a favourable configuration, good crown root
ratios and long clinical crowns.
Generally, cantilever FPDs should replace only one tooth and have
at least 2 abutments.
54. QUESTIONABLE ABUTMENTS
• CLASSIFICATION
• General Disorder:
Mineralization
Amelogenesis Imperfecta.
Dentinogenesis Imperfecta.
Hypocalcification.
Ectodermal Dysplasia.
Discolouration due to drugs like Tetracycline.
Flouridosis.
Internal resorption .
57. • TREATMENT STRATEGY:
Abutment with generalized mineral disturbance:
• Full coverage restoration.
• Success depends on supporting tissue response.
Congenital and growth deformities:
1st line of treatment:
• Orthodontics.
• Interceptive periodontics.
• Restorative dentistry.
58. Malposed teeth:
• Judicious tooth reduction.
• Orthodontics for minor tooth movement: Requires periodic occlusal
adjustments.
• Telescopic crowns
Occlusal plane correction: Supra-erupted teeth
• Intentional RCT.
• Reduction to satisfactory occlusal plane.
• Tooth preparation to receive retainer.
• Construction of opposing prosthesis.
59. Polycarious tooth: No contraindication.
• DMF >3
• Clinical approach to uncontrolled caries:
• Caries control program.
• Endodontic and periodontic consultation.
• Cast metal restoration where indicated after amalgum restoration.
• Recall visits strictly maintained.
60. Periodontally involved teeth:
• Review the reason for the condition.
• Periodontal treatment before caries control.
• Loss of periodontal support: Splinting may compensate.
Mobility:
• Due to Primary TFO: Occlusal correction.
• Due to Secondary TFO: Splinting.
Furcation involvement: ( Class III)
• Open and closed root debridment.
• Filling the furca with polymeric ZOE cement or GTR.
• Root amputation and hemisection.
61. SUMMARY AND CONCLUSION
In the above discussion various guides have been
suggested for selection and construction of fixed
partial dentures that should withstand the forces of
oral function with maximum service. Abutments bear
the stresses of mastication and the choice of abutment
influences the prognosis of treatment.
In a concluding note the importance of selecting a
suitable abutment for a fixed partial denture cannot be
overemphasized. It forms the preliminary treatment
planning for fixed partial dentures whose proper
selection and preparation aids in long term durability
of the restoration.
62. REFERENCES
Shillingburg. Fundamentals of Fixed prosthodontics. 3rd ed.
Tylman’s Theory and practice of fixed prosthodontics. 8th ed.
Rosenstiel, Land, Fujimoto. Contemporary Fixed prosthodontics.
3rd ed.
Jhonston’s modern practice in fixed prosthodontics. 4th ed.
Colin R. Cowell. Inlays, crown and bridges. A clinical handbook.
4th ed.
Glossary of Prosthodontic Terms. JPD 2005;94.
Crown root ratio : Its significance in restorative dentistry. JPD
1979;42.
The prosthodontic concept of crown-to-root ratio: A review of the
literature. JPD 2005;93.