Writing a book on Prosthodontics was always one of our dreams and

with blessings of God, parents, teachers and wishes of colleagues and

students it seems to be fulfilled.

First we would like to extend our sincere and heartfelt gratitude to

our teachers who have been instrumental in shaping our thoughts at

various points of our career. Our sincere gratitude to all our teachers

during graduation and postgraduation, especially to our guides Dr

Mariette D’souza (Manipal) and Dr Sanjay Tewari (Rohtak). We are

grateful to our friends and colleagues whose support over the years

have encouraged and influenced our thinking.

We wish to express our love, gratitude and respect to our parents

who have always been pillars of strength and have motivated us

throughout our lives. A special hug to our children who have made

our life journey joyful.

A special measure of appreciation to our students over the years

who have inspired us to excel and make teaching fun filled and

exciting.

Finally, our sincere thanks to excellent editorial team of ELSEVIER

India, especially to Ms Nimisha Goswami, Mr Anand K Jha, Dr

Nabajyoti Kar for the expertise and enthusiasm shown towards this

project. We wish to also acknowledge the efforts of artist Mr R K

Majumdar.

SECTION I

Complete Dentures

OUTLINE

1. Introduction to edentulous state

2. Diagnosis and treatment planning for edentulous

patients

3. Mouth preparation of complete denture patients

4. Impressions in complete dentures

5. Articulators and facebows

6. Maxillomandibular relationship

7. Selection and arrangement of teeth

8. Concept of occlusion

9. Wax try-in and laboratory procedures

10. Insertion and troubleshooting in complete

denture prosthesis

11. Relining and rebasing

12. Single complete dentures and immediate

dentures

13. Overdentures

CHAPTER 1

Introduction to edentulous state

CHAPTER OUTLINE

Introduction, 2

Parts of Complete Denture, 3

Denture Surfaces, 3

Component Parts of Complete Denture, 3

Residual Ridge Resorption, 6

Pathology of RRR, 6

Pathogenesis, 6

Aetiology, 7

Treatment and Prevention, 7

Importance of Temporomandibular Joint in Complete Dentures, 7

Role of TMJ in Biomechanical Phase of the Prosthetic

Rehabilitation, 8

Importance of Patient Motivation and Patient Education, 9

Patient Motivation and Education, 9

Physiological Rest Position and its

Importance, 10

Morphological Changes Associated with

Edentulous State, 10

Soft Tissue Changes in Denture Patients, 11

Introduction

Loss of teeth in a patient results in psychological, aesthetic and

functional impairment. There is a need to restore and replace the

missing teeth and adjacent structures with artificial substitutes to

allow the patient to lead a normal life. Replacement of teeth and

adjacent structures is covered under specialized branch of complete

denture prosthodontics.

Definitions:

Complete denture prosthodontics is defined as ‘that body of

knowledge and skills pertaining to the restoration of the edentulous arch with

a removable dental prosthesis’. (GPT 8th Ed)

Complete denture prosthetics is defined as ‘the replacement of the

natural teeth in the arch and their associated parts by artificial substitutes’.

(GPT 8th Ed)

Complete denture is defined as ‘a removable dental prosthesis that

replaces the entire dentition and associated structures of the maxillae or

mandible’. (GPT 8th Ed)

Objectives of complete denture prosthetic care are as follows:

• To enable the patients to masticate food so as to get adequate

nutrition.

• To restore the aesthetics by preserving the normal appearance.

• To restore speech as distinctly as the breathing factors permit.

• To provide oral comfort and improve the patients’ sense of wellbeing.

• To educate the patients about the changes to be expected in the

supporting tissues.

• To convince them about the need for regular check-ups and

subsequent treatment.

Parts of complete denture

A complete denture has three surfaces and four component parts.

Denture surfaces (fig. 1-1)

Impression surface

This surface is in direct contact with the basal seat tissues and limiting

structures. It is a negative replica of the tissue surface of the jaw.

FIGURE 1-1 Denture surfaces: Impression surface (1),

polished surface (2), occlusal surface (3).

It is defined as ‘the portion of the denture surface that has its contour

determined by the impression’. (GPT 4th Ed)

Polished surface

This surface includes the external surface of the denture, i.e. the labial,

buccal, lingual and the palatal surfaces of the denture. This surface is

desired to be highly polished to facilitate plaque control.

It is defined as ‘that portion of the surface of the denture that extends in

an occlusal direction from the border of the denture and includes the palatal

surfaces. It is that part of the denture base that is usually polished, and it

includes the buccal and lingual surfaces of the teeth’. (GPT 4th Ed)

Occlusal surface

This surface consists of denture teeth which simulate the natural teeth

and cusps and act as sluiceways to aid in eating.

It is defined as ‘a surface of a posterior tooth or occlusal rim that is

intended to make contact with an opposing occlusal surface’. (GPT 1st Ed)

Component parts of complete denture (fig. 1-2)

Denture base

It is that part of the denture which rests directly over the oral tissues

and to which teeth are attached and which helps in mastication and

restoring natural appearance.

FIGURE 1-2 Parts of denture: Denture base (1), denture

flange (2), denture border (3), denture teeth (4).

It is defined as ‘that part of a denture that rests on the foundation tissues

and to which teeth are attached’. (GPT 8th Ed)

Purpose

• To transmit the forces acting on the denture to the basal seat tissues.

Wider the denture base, more is the retention and lesser are the

forces on the underlying tissues.

• Forms the foundation of the denture.

• Can be characterized to enhance aesthetics.

Denture base is commonly made of acrylic resin. However, metals

can also be used for constructing denture bases. Some of the

commonly used metals are gold and gold alloys (type IV), cobalt–

chromium and nickel–chromium.

Acrylic denture base

• It is the commonly used material to construct denture bases.

• It is supplied as monomer and polymer.

Advantages

• It is easy to fabricate and is economical.

• It is easily relined or rebased.

• It can be characterized to enhance aesthetics.

• It has adequate rigidity to resist functional forces.

Disadvantages

• It cannot be used in thin sections.

• Wear is faster as compared with metal base.

• Thermal conductivity is less.

• There are chances of acrylic warpage.

Metallic denture base

Metallic denture base is defined as ‘the metallic portion of a denture base

forming a part or the entire basal surface of the denture. It serves as a base for

the attachment of the resin portion of the denture base and the teeth’. (GPT

8th Ed)

Commonly used metals for denture base are type IV gold alloys,

cast chrome-based alloys and aluminium-based alloys (Fig. 1-3).

FIGURE 1-3 Metal base dentures.

Advantages

• High strength

• Increased accuracy

• Less chances of tissue change under the metal base

• Lesser porosity and, therefore, easy to clean

• Better thermal conductivity

• Less chances of deformation under function

Disadvantages

• High cost

• Difficult to reline or rebase

• Fabrication is time consuming and technique sensitive

Denture flange

It is defined as ‘that part of the denture base that extends from the cervical

ends of the teeth to the denture border’. (GPT 8th Ed)

In the upper denture, the denture flange includes the labial and the

buccal flanges, whereas in the lower denture, the denture flange

includes the labial, buccal and the lingual flanges, which is the vertical

extension along the lingual side of the alveololingual sulcus.

The labial flange provides the lip support, fullness and aesthetics. If

the labial flange is thick, it gives an artificial denture look to the

patient.

The buccal flange provides support to the cheeks and occupies the

buccal vestibule of the mouth. In the lower denture, it also transfers

the occlusal forces to the buccal shelf region, which is the primary

stress-bearing area in the mandible.

Lingual flange occupies the space adjacent to the tongue. It contacts

the floor of the mouth and provides the peripheral seal to aid in

retention of the denture. Overextended lingual flange may result in

loss of retention of the denture.

Denture border

It is defined as ‘the margin of the denture base at the junction of the

polished surface and the impression surface’. (GPT 8th Ed)

It is the peripheral border of the denture base at the facial, lingual

and the posterior portion. This part of the denture provides the

peripheral seal which aids in the retention and stability for the

denture. Overextended and underextended dentures result in the loss

of retention. Denture border should be smooth and well polished; any

sharp margins may irritate and injure the underlying soft tissues.

Denture teeth

Denture teeth form the occlusal surface of the denture; these provide

aesthetics, enable the patient to chew and aid in speech. These are

usually made of acrylic resin or porcelain.

Classification

On the basis of tooth morphology, denture teeth can be classified as

follows (Fig. 1-4):

• Nonanatomic teeth

• Semi-anatomic teeth

• Anatomic teeth

On the basis of type of the material used, these can be classified as

follows:

• Acrylic teeth

• Porcelain teeth

• Gold occlusal

• Acrylic resin with amalgam stops

• Acrylic teeth with metal inserts

• Interpenetrating polymer network (IPN) resin teeth

FIGURE 1-4 (A) Anatomic tooth. (B) Semi-anatomic tooth.

(C) Nonanatomic tooth.

Residual ridge resorption

Residual ridge resorption (RRR) is defined as ‘a term used for

diminishing quantity and quality of the residual ridge after the teeth are

removed’. (GPT 8th Ed)

RRR is considered as the chronic, progressive, irreversible and

cumulative oral disease. It is described under the following headings.

Pathology of RRR

Basically, the ridge resorbs and decreases in size under the

mucoperiosteum.

• Although there is primary localized loss of bone, sometimes this loss

may be accompanied by redundant tissues.

• Maxilla resorbs vertically and palatally in the anterior region and

vertically and medially in the posterior region.The maxillary ridge

becomes progressively smaller and the incisive foramen comes

nearer to the crest of the ridge as the resorption progresses.

• Mandible resorbs vertically and lingually in the anterior region and

vertically and laterally in the posterior region. Mandibular ridge

appears progressively wider on resorption. Progressive resorption

of the maxillary and mandibular ridges makes the maxilla narrower

and the mandible wider.

Atwood’s classification of the form of residual ridge (1963) (Fig. 1-5):

• Order I: Pre-extraction

• Order II: Postextraction

• Order III: High, well rounded

• Order IV: Knife edge

• Order V: Low, well rounded

• Order VI: Depressed

FIGURE 1-5 Atwood’s classification of residual ridge: Order

(I): pre-extraction; order (II): postextraction; order (III): high,

well rounded; order (IV): knife edge; order (V): low, well

rounded; order (VI): depressed.

Pathogenesis

• After the extraction of the teeth, the empty sockets are filled with

blood to form blood clot. During healing, a new bone is laid down.

The residual ridge changes in shape and size at varying rates in

different individuals and in same individual at different times. RRR

progresses slowly over a longer period of time resulting in reduced

residual ridge.

• A. Tallgren (1972), D.A. Atwood and W.A. Coy (1971) found that the

mean ratio of the anterior maxillary RRR to the anterior mandibular

RRR was 1:4.

Aetiology

RRR is a multifactorial biomechanical disease resulting from the

following factors:

Anatomical factors:

RRR varies with the quantity and quality of the bone

of the residual ridge.

• RRR a-anatomic factors: More the bone, more are

the chances for resorption, but the rate at which it

may resorb may vary.

Metabolic factors:

• RRR is a localized loss of bone on the crest of

residual ridge and certain local and systemic factors

may influence the rate of resorption.

• Local factors are endotoxin, osteoclast activating

factor, prostaglandins, heparin, trauma, etc.

• Systemic factors may influence the balance between

the bone formation and bone resorption.

Mechanical factors:

• Remodelling of the bone is influenced by the force

factor.

• The amount, frequency, duration, direction, area

and the damping effect of the underlying tissue

influence ridge resorption.

• RRR a-force:

• RRR may increase in a patient with parafunctional

habits such as clenching and grinding of teeth.

• The amount of force applied may be affected

inversely by the damping effect or energy

absorption.

• Damping effect takes place in the mucoperiosteum

which is viscoelastic in nature.

• Energy absorbing quality may influence the rate of

RRR.

• Maxillary residual ridge is broader, flatter and has

increased cancellous bone than mandible and,

therefore, has greater damping effect.

Treatment and prevention

The goal is to reduce the amount of force on the ridge and, therefore,

to reduce the RRR. It can be accomplished by the following:

• Broad area coverage

• Reduced number of teeth

• Reduced buccolingual width of the teeth

• Use of anatomic teeth

• Centralization of occlusal contact

• Avoidance of inclined planes

• Provision of adequate tongue space

• Adequate interocclusal space

Importance of temporomandibular joint

in complete dentures

Temporomandibular joint (TMJ) is a complex synovial joint in which

mandible articulates bilaterally to the cranium. It is a

ginglymoarthrodial joint which is capable of making hinge and

gliding movement (Fig. 1-6).

FIGURE 1-6 Anatomic components of temporomandibular

joint (TMJ): Head of condyle (1), articular disc (2), articular

eminence (3), superior joint cavity (4), inferior joint cavity (5),

retrodiscal (6), superior lateral pterygoid muscle (7), inferior

lateral pterygoid muscle (8).

TMJ is formed by the mandibular condyle fitting into the

mandibular fossa of the temporal bone. Separating these two bones

from direct articulation is the articular disc. This disc serves as the

nonossified bone that permits the complex movement of the joints. In

the sagittal plane, the disc is divided into three regions (intermediate,

anterior and posterior zones) according to the thickness. The hinge

movement occurs between the condyle and the articular disc and the

gliding movement occurs between the disc and the articular eminence

of the temporal bone.

Each of the joints can simultaneously act separately but not

completely without the influence of the other joint. Unlike the other

joints, TMJ is not composed of the hyaline cartilage. The articular

surfaces and the middle or intermediate portion of the articular disc

are made of nonvascular, nerve-free, dense fibrous connective tissues.

The intermediate portion of the articular disc is the load-bearing area.

The articular disc is thicker both anterior and posterior to the

intermediate zone.

Role of TMJ in biomechanical phase of

the prosthetic rehabilitation

Studies show that the condyles are stress-bearing structures, and the

continuous positioning of the disc on the articular surface throughout

the normal movements suggests that the intermediate zone of the disc

must assume pressure during function. In the normal position, the

articular surface of the condyle is located on the intermediate zone of

the disc, bordered by the thicker anterior and posterior regions. As

mentioned earlier, the intermediate zone of the disc is the loadbearing area. The innervated posterior band protects the joint by

sensory feedback and provides a biomechanically stable relationship.

As the articular eminence is an inclined plane, the condyle disc

assembly should be stabilized on this slope by the muscular activity

unless it is in the position of biomechanical equilibrium. The lateral

pterygoid muscle plays an important role in determining the position

of the condyle disc assembly on the eminence at any given movement.

The fibres of the TM ligaments are oriented in appropriate directions

to limit posterior movement of the mandible. A posterior force tends

to pivot the condyle superoanteriorly because of the restriction by this

ligament.

In a dentulous patient, the physiological relation between the

condyles, disc and their glenoid fossa is maintained during maximal

occlusal contacts and movements guided by the occlusal elements.

This occurs in the centric relation position.

• Centric relation is the most superior position of the mandibular

condyles with the intermediate zone of the disc in contact with the

articular surface of the condyle and the articular eminence. This

position is consistent with the functional bearing capacity of the

posterior slope of the eminence, the adaptation of the intermediate

zone of the disc and the biomechanical stability of the joint resulting

from the shape of its components.

• In an edentulous patient, the pathological or adaptive changes of

TMJ occur over a period of time. Centric relation position coincides

with the reproducible posterior hinge position of the mandible and

should be recorded with accuracy in the edentulous patient.

• Centric relation is considered as an essential relationship in any

prosthodontic rehabilitation.

• The occlusion of the complete denture patient should harmonize

with the primitive unconditioned reflex of the patient swallowing.

• It is observed that unconscious swallowing occurs when the

mandible is at or near the centric relation position.

• If the occlusion in a complete denture patient does not coincide with

the centric relation, morphological changes can occur in TMJ.