Chapter I: Introduction
Types of Partial Denture:
Temporary acrylic plate or transitory denture Permanent cast partial denture In temporary; support is by muco-periosteum & retention is by wrought iron clasp. Permanent is a bio-mechanical appliance Restoration of lost teeth Rehabilitation of lost thing Restoration of aesthetic Creation & maintenance of proper oral hygiene Maintenance of state of health Equal distraction of forces to remaining tissue.
The appliance needs minimum cutting of remaining tissue Stresses should be distributed equally to the denture so that it can withstand the stresses of mastication The design of the denture should be such that it can be easily inserted & removed by the pt.
It consists of: Saddle area Means of Retention Means of Support Connectors
Saddle area: Is that part of the partial denture which overlies on ridge & carry teeth. Saddle area has 2 subdivisions: Conventional Saddles Gum fit Saddles Conventional saddles cross the alveolar ridge to the depth of labio-buccal sulcus while gum fit finishes of at the cervical area.Indications of gum fit saddle: 1. Gum fit are used for anterior teeth because the colour of the acrylic may differ from gum so, for aesthetic purposes especially when the number of missing teeth is less. 2. In the bulbous ridge, because deep undercuts do not allow insertion & removal of partial denture 3.Procline pre-maxialla or bulging anterior segment. 4. Procline Premaxialla or bulging anterior segment
KENNEDY Classification of partial denture or (Kennedy APPLEGATE Classification):Kennedy class I: Is a bilateral free end saddle i.e all the remaining natural teeth are anterior to a bilateral edentulous situation.
Kennedy class II: Is a unilateral free-end saddle i.e the remaining teeth of either left or right side are anterior to the edentulous situation.
Kennedys class III: (Kennedy apple gate): An Edentulous area bounded by teeth; but the teeth in the posterior segment are unable to assume total support for the required prosthesis.
Class IV: Is bounded anterior segment
Kennedys apple gate Class V: Edentulous situation bounded by teeth (anterior & posterior to it0, but teeth anterior to it is not suitable for abutment surface while the posterior bounded is suitable.
Kennedy apple gate Class VI: Edentulous situation where the boundary teeth are capable of providing adequate support.
Other Classification of Partial Dentures: Another method of dividing P.D into basic types is consider the
manner in which the pressure is applied to the occlusal surfaces of the teeth, & in this:
Tooth-borne: It is a type which has a small projection called occlusal rest. Which are placed on the occlusal surfaces of natural teeth so that the vertical masticatory loading is transmitted via the teeth bearing the rest & not via the mucosa underlying the denture. Tissue-borne: Is one in which the vertical load is received directly by the mucosa with out any resistance from the natural teeth. Tooth & Tissue borne: Is one in which the vertical loading is transmitted partly by the teeth & partly by the mucosa
Chapter 2: Means of Retention
Retention is achieved depending on the principle of tensile
friction. i.e (if a metal is displaced & it tries to come back to the normal area due to stress or force, This friction is known as tensile friction) This tensile friction should be within the physiological limits of that particular tooth otherwise the tooth will damage. This tensile friction is controlled by: Extending the wire more into the undercuts By selecting a suitable metal alloy. E.g. silver-copper alloy gets
tarnish but silver, copper & palladium alloy is good to resist tarnishing., chromiumcobalt alloy are very hard. When the undercut is less deep we select harder alloy. By the diameter of the wire, more the diameter of the wire more will be friction & vice-versa
Surveyor: Objects of Survey are: 1, To not down & locate areas of undercuts 2, To measure the depth of undercuts 3, To devise ways & means to utilize the favourable undercuts & avoid unfavourable undercuts:
How to reduce under cut depth?? By: Changing the path of insertion Selective grinding of the natural tooth but dentine should not be exposed By filling Inlay or onlay Crowning of the tooth If all these fails go for extraction 4, Design of the partial denture i.e. the 4 parts of it: Saddle area (edentulous areas) Means of Retention (Infra bulge area) Means of Support (Supra bulge area) Connecting areas. 5, To determine the path of insertion & path or removal of partial denture.
Surveyor has 3 Parts: 1, Horizontal plate form 2, Vertical standard 3, Surveying table
Clasp has 4 parts 1, Body 2, Retaining arm 3, Reciprocating arm 4, Occlusal extension or occlusal rest Body lies on the proximal surface of the tooth near the saddle
area Retaining arm: it arises from the body & engage the undercut & provide retention. The reciprocating area is on lingual side or buccal side which remain above the guide line The occlusal rest which extend to to the occlusal surface; but it should not interfere with occlusion so, that whether the surface can be utilized? ; otherwise slight grinding on the occlusal depth but it should be within the enamel limits.
Indications of clasps: 1, Bars clasps are indicated when the undercut are very deep, because they are more resilient. 2, If the undercut is available on the buccal surface of the proximal end away from the vacant space, conventional circumferential clasp is the ideal clasp. 3, if the undercut is not deep enough & similar undercut is available on the remote proximal end on lingual surface; average circumferential clasp may be given. 4, If undercut is located close to the vacant space, back action clasp is given 5, Single body mesiodistal clasp can be given on canine; they can be conventional type or average. 6, split body mesiodistal clasp & embrasure clasps are selected to
contact the free end saddle of the opposite side. split circumferential clasp can be given.
7, When there is vacant space on both sides of the abutment tooth, a
1, Conventional circumferential clasp
2, Average circumferential clasp 3, Back action clasp 4, Mesiodistal clasp
5, Embrasure Clasps 6, Split circumferential clasp
T bar is given on bicuspid
L bar I bar C bar
U bar Combination of C & I
Chapter 3: Steps in the procedure of P.D
Steps for the procedure of a partial denture normally involve the following: Examination & evaluation of partially edentulous Pt. Study model impression Study model & this involve: Initial diagnosis Initial Examination Diagnosis Oral Rehabiliation: This may consist of: Creation of orodental hygiene e.g. scaling Operative & conservative measures Axial anatomy may be modified to get rid of undesirable undercuts Inlay, onlay, or crowining If all fails go for extraction Master model impression & model surveying (i.e. design of P.D) Duplication & construction of the wax pattern Casting procedure Maxillomandibular relations Arrangement of the teeth & trial Processing & insertion Charge your fees
Chapter 4: Evaluation of the Pt.
Identification: The same as C.DMental Classification: Philosophical Exacting Antagonistic Passive General systemic status
Examination of the Patient: General Examination: In which we see Size & shape of the face & jaw Muscular development Muscle tone Face form Colour of skin, eyes & hair
Visual examination to identify the oral condition
in health & disease; in this we justify. Condition of occlusion. Radiographic Examination to know.
Chapter 5: Design of Partial Denture
Examination of the oral condition gives us some information
about the design but to know definitely the exact shape & form of the denture that would be suitable for a particular mouth we have to study carefully the curves & contours of the study models. Retention primarily depends upon those parts which involve the infra buldge area or undercuts on axial surfaces of the teeth. The undercuts can only be involve up to certain extent so that the stresses exerted upon the teeth during insertion & removal are within the physiological limits of tolerance of the periodontia. For this purpose curves & contours of all axial surfaces of the teeth that come in contact with the denture have to be studied; The procedure of studying it is called surveying.
Retention is one of the basic requirement of partial denture.
Surveying is carried out with the following objectives: 1, To note down & locate areas of undercuts 2, To measure the depth of the undercut
3, To devise ways & means to utilize desirable
undercuts & get rid of undesirable undercuts. 4, To determine the path of insertion & removal of denture. 5, To design the saddle areas, means of retention, the means of support & connectors.
Chapter 6: Duplication of (Master) Models
Master models have to be duplicated to make the working model. The various procedures are carried out on the working model & the master model is used for reference. If the working model is spoiled or gets distorted during various functional procedures, the master model can again be duplicated to get a working model, Any of the duplicating material can be used for this purpose, The material may have an alginate base, colloid base or an agar base. The alginate base is not very popular because it