Preparation for RPD /certified fixed orthodontic courses by Indian dental academy

MOUTH PREPARATION FOR
REMOVABLE PARTIAL
DENTURES

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DEFINITION

Mouth preparations are identified as those
procedures that are accomplished to prepare the
mouth for reception of prosthesis.

RENNER BOUCHER

More specifically they are the procedures that
change or modify existing oral structures of
conditions to
Facilitate placement and removal of prosthesis
Facilitate its efficient physiologic function
Enhance its long term success

Mouth preparation follows preliminary diagnosis and
development of tentative treatment plan.


Classification


Mouth preparation

Prosthodontic procedures

Non prosthodontic
procedures

Procedures related to
Occlusion


Restorative dentistry
(fixed partial dentures)


Preparation of abutment
teeth



Oral surgery
Orthodontics
Periodontics
Endodontics


OBJECTIVES
 Establishing

state of health in supporting and
contiguous tissues
 Eliminating interferences or obstructions
 Establishing acceptable occlusal plane
 Alteration of natural tooth form for requirements
of form and function of prosthesis


PLANNING MOUTH PREPARATIONS









Examination of patient
Examination of oral structures
Complete radiographic survey
Mounted diagnostic casts
Evaluating diagnostic data
Surveying diagnostic cast
Designing removable partial denture
Recording mouth preparations

RECORDING MOUTH PREPARATIONS


Executed in a red
pencil



Teeth to be extracted
are marked with X




Outlining areas of
bony ,soft tissues
recontouring and
alteration of tooth
structures with closely
spaced parallel lines
or shade with a red
pencil

PREPARED FORM


ADVANTAGES OF CHARTING MOUTH
PREPARATIONS







Ensures completeness
Serves as quick and convenient record of
mouth preparations to be accomplished to
prepare patient for reception of removable
partial denture
Serves as a road map when properly prepared
Serves as a legal record
Ensures execution of procedures in proper
sequence

TERM










ABBREVATION

Survey line
Guiding plane
Interference
Occlusal rest
Incisal rest
Incisal hook rest
Cingulum rest
Facial
Lingual

SL
GP
INT
OR
IR
IHR
CR
F
L

TERM








ABBREVATION

Mesial
Distal
Line angle
Raise survey line
Lower survey line
Reduce cusp tip
Selectively grind

M
D
LA
RSL
LSL
RCT
SG

TIME INTERVAL




Endodontic surgery ,periodontal surgery and
oral surgery should be planned so that they can
be completed during same time frame
Longer the interval more complete the healing
and more stable denture bearing area


SEQUENCE OF PROCEDURES TO
BE FOLLOWED DURING MOUTH
PREPARATIONS







Oral surgical preparation
Periodontal preparation
Orthodontic considerations
Endodontic therapy
Restorative dentistry
Preparation of abutment teeth

ORAL SURGICAL PREPARATION



Extraction of teeth that
may be detrimental to
design of partial denture


RETAINED ROOTS




Located adjacent to
abutment teeth
contributes to
progression of
periodontal disease
Removal is
considered when
associated with
pathologic finding

IMPACTED TEETH


Removal is
considered when
associated with
pathologic condition


TISSUE REACTIONS TO WEARING
OF PROSTHESIS
PALATAL PAPILLARY
HYPER PLASIA
 Poorly fitting prosthesis worn
for prolonged periods
 Inadequate oral hygiene
 Inadequate prosthesis
hygiene
TREATMENT
 Tissue rest
 Tissue conditioners
 surgery

EPULIS FISSURATUM






Ill fitting prosthesis

TREATMENT
Removal of irritation
Tissue conditioners
surgery


DENTURE STOMATITIS








Trauma from occlusion
Ill fitting prosthesis
Poor oral hygiene
Continuous wearing of
prosthesis
TREATMENT
Tissue rest
Tissue conditioning

CYSTS AND ODONTOGENIC
TUMOURS






Panoramic radiographs
are recommended
Periapical radiographs
are recommended for
suspicious area to
confirm diagnosis
Biopsy for microscopic
study


EXOSTOSIS AND UNDERCUTS


Prevents proper
extension of denture



Undercuts are minimized
by changing path of
insertion



Surgical correction


TORI


Surgical removal is
considered when it is so
large interfering with
design of prosthesis



Mucosa over tori is thin


FRENA








Maxillary labial frenum
Problems while replacing
anterior teeth
Mandibular frenum
Compromise rigidity and
placement of major
connectors
frenectomy


WHITE, RED AND ULCERATIVE
LESIONS

Biopsy for
Microscopic study



PERIODONTAL PREPARATION





Thorough examination of periodontium
Complete periodontal charting
Radiographs to evaluate periodontal destruction


PERIODONTAL DISEASES THAT
REQUIRE TREATMENT







Pocket depths in excess of 3mm
Furcation involvement
Gingivitis
Potential abutment teeth with less than 2mm of
attached gingiva
Pulling of frena on attached gingiva

TREATMENT PLANNING
There are three phases






PHASE 1: INITIAL DISEASE CONTROL
THERAPY
PHASE 2: DEFINITIVE PERIODONTAL
SURGERY
PHASE 3: RECALL MAINTAINENCE

INITIAL DISEASE CONTROL
THERAPY








Oral hygiene instructions
Scaling and root planing
Elimination of local irritating factors other than
calculus
Elimination of gross occlusal interferences
Splinting
Use of night guard

ELIMINATION OF GROSS
OCCLUSAL INTERFERENCES






Selective grinding is
indicated when
associated with
pathologic condition
Deflective contacts in
centric path of closure
are removed
Balancing or nonchewing
side interferences should
be removed



Occlusal equilibriation done priorly on diagnostic cast
serves as a blueprint for selective grinding in mouth


SPLINTING






Short length
Periodontally weakened teeth
Excessive taper of single root
Unfavourable crown root ratio


REMOVABLE SPLINTING



Indicated in patients in
fourth ,fifth and sixth
decades of life having
major medical problems


FIXED SPLINTING


Indicated when an
individual teeth or two
adjoining teeth may have
lost some periodontal
support as a result of
local conditions



Accomplished with full or
partial coverage crowns

NIGHT GUARD







Removable acrylic resin
splint
Eliminates deleterious
effects of nocturnal
clenching and grinding
Act as a temporary splint
Used when abutment
teeth has been
unopposed for an
extended period

DEFINITIVE PERIODONTAL
SURGERY
GINGIVECTOMY



Eliminates supra bony pockets
Pocket depth confined to band of attached gingiva


PERIODONTAL FLAP
SURGERY





To perform osseous recontouring for
Pocket elimination
Crown lengthening


MUCOGINGIVAL SURGICAL
PROCEDURES


Indicated when abutment teeth for removable partial
denture lacks adequate attached gingiva



Abutment teeth requires root coverage to facilitate
partial denture construction and maintenance


RECALL MAINTAINENCE



Patients with previous moderate to severe periodontitis
3 to 4 months


ORTHODONTIC CONSIDERATIONS


Extrusion



Mesial drifting



Rotated teeth


CORRECTION OF OCCLUSAL PLANE


DISCREPENCIES IN
OCCLUSAL PLANE IS
DUE TO



Super erupted teeth



Infra erupted teeth




Tipped molars



Mesially drifted teeth




Malrelationship of jaws


TREATMENT


Enameloplasty



Onlay



crowns




Coping



Surgical repositioning of
one or both jaws to
correct malrelationship


ENDODONTIC THERAPY



Tooth with pulpal involvement and root end pathology
are candidates for endodontic therapy


Treated Pulpless Teeth
Criteria to be followed to use them as
abutment





Canals have been filled to apex with what appears
radio graphically to be well condensed filling material
No radioluscency at apex
Tooth has been clinically asymptomatic since therapy
was accomplished

ABUTMENT TOOTH WITH PULPITIS
ENDODONTIC TREATMENT SHOULD BE
CONSIDERED





Abutment tooth healthy from standpoint
Favorable crown root ratio
Prosthesis itself is satisfactory
When mouth is in state of good health


RESTORATIVE DENTISTRY







Integrated with endodontic treatment
Crowns
Inlays
Onlays
Restoration of carious lesions
Replacement of defective restorations


PREPARATION OF ABUTMENT
TEETH
OBJECTIVES





Directs stress along long axis of tooth
Eliminating interference by recon touring of teeth
Creating retention by simple alteration procedures
Allows placement and removal of prosthesis without
having it transmitting wedging types of stress against
teeth with which it comes in contact

CLASSIFICATION OF ABUTMENT
TEETH






Abutment teeth that require only minor modifications to
their coronal portions
Abutment teeth that are to have restorations other than
complete coverage crowns
Abutment teeth that are to have crowns


SEQUENCE




Preparation of guiding planes
Modification of tooth contours
Rest seat preparation


PREPARATION OF GUIDING
PLANES




Diagnostic cast mounted on
surveying table at the tilt at
which design of removable
denture was drawn should be
placed on table in front of
patient
Hand piece with appropriate
diamond instrument in place
positioned over cast to
visualize relationship of hand
piece and diamond
instrument and can be
duplicated in patients mouth



Cylindrical diamond point
is used for guide plane
preparation



Gentle light sweeping
stroke from buccal line
angle to lingual line angle




Flat surface created
should be 2-4mm in
occluso gingival height



Reduction should follow
curvature of proximal
surface




All prepared tooth
surfaces must be
polished with
carborandum
impregnated rubber
wheel or points


ABUTMENT TOOTH ADJACENT TO
DISTAL EXTENSION EDENTULOUS
SPACES






Occluso gingival height
reduced to 1.5-2mm
Permits partial denture to
Rotate Slightly around
distal occlusal rest as
downward force occurs
on artificial teeth
Avoids torquing forces on
abutment teeth


LINGUAL SURFACES


Provides maximum
resistance to lateral
stresses



Occlusogingival height
should be 2-4mm


ANTERIOR ABUTMENT TEETH


Provides parallelism, ensures stabilization



Minimize wedging action between teeth



Increase retention through frictional resistance



Decrease undesirable space between denture and
abutment teeth


ENAMELOPLASTY TO CHANGE
HEIGHT OF CONTOUR


Height of contour is changed to provide better
positions for clasp arms or lingual plating

Retentive clasp arm



Located at junction of gingival and middle third
Enhances esthetic quality of clasps and provides
mechanical advantage









In maxillary arch molars and premolars if unsupported
tend to tip buccally
Height of contour will be near occlusal surface on facial
side
Amount of correction depends upon thickness of
enamel
If dentin is exposed placement of restoration is
considered




In mandibular arch premolars and molars unsupported
tip lingually



Problem with positioning of reciprocal clasps and
lingual plating


ENAMELOPLASTY TO MODIFY
RETENTIVE UNDERCUTS


Successful only when
buccal and lingual
surfaces of tooth are
nearly vertical



created in form of gentle
depression



dimpling



Prepared by using a small
round end tapered
diamond stone



End of stone is moved in
an antero posterior
direction near line angle
of tooth



Depression should be
4mm in mesio distal
length and 2mm in
occluso gingival height

PREPARATION OF REST SEAT
OCCLUSAL REST




Outline form of occlusal
rest is triangular with
base of triangle at
marginal ridge and apex
towards centre of tooth
Apex of triangle and
external margins of
preparation should be
rounded







Extension of rest seat
preparation should vary
from 1/3 to ½ the
mesiodistal diameter of
tooth
Buccolingual extent
should be half the
distance between buccal
and lingual cusp tips
Floor must be spoon
shaped





Angle formed by
inclination of floor of rest
and vertical projection of
proximal surface of tooth
must be less than 90
degrees
PREPARATION
First channel of correct
depth and desired outline
of preparation is created
by small round diamond
stone







Lower the marginal ridge
at either buccal or lingual
extent of rest seat to
continue inward towards
centre of tooth and to
return to marginal ridge
Island of enamel remains
with in outline form can
be removed and shaped
Deepest portion of rest
seat is towards centre of
tooth preparation raises
gradually towards
marginal ridge









Adequacy of occlusal rest seats can be checked before
impression of master cast is made by
Visual inspection
Direct tactile contact
By making imprints in red utility wax
By making impression to create a diagnostic cast


IN NEW GOLD RESTORATION


Placed in wax pattern
after establishment of
guiding planes



Depression is added in
prepared tooth to
accommodate depth of
occlusal rest


IN AMALGAM RESTORATIONS






Less desirable as amalgam alloy tends to flow under
constant pressure
Rest seats are prepared using no.4 round bur
Care must be taken not to weaken proximal portion of
amalgam restoration


REST SEAT PREPARATION FOR
EMBRASSURE CLASP







Preparation extends over
occlusal embrasure of
two approximating
posterior teeth from
mesial fossa of one tooth
to distal fossa of other
tooth
Small round diamond
stone is used to establish
out line form for normal
occlusal rest in each of
approximating fossa
contact point between
teeth should not be
broken





Same round diamond
stone is used to carry
buccal and lingual
extension of occlusal
rests over buccal and
lingual embrasures
Cylindrical diamond
stone is held horizontally
from buccal surfaces of
teeth pointing towards
lingual surface





Stone is held against
distal incline of buccal
cusp of one tooth and
mesial incline of buccal
cusp of other tooth to
create occlusal
clearance
Preparation should be
1.5-2mm wide and 11.5mm deep as it
passes over buccal and
lingual embrasures

LINGUAL REST SEAT


Outline form is half-moon
shaped



Forms a smooth curve
from one marginal ridge
to other crossing centre
of tooth incisally to
cingulum
Rest seat is v shaped








Labial incline of lingual surface of tooth forms one wall
of v shaped notch other starts from top of cingulum
and inclines linguo gingivally towards centre of tooth
to meet other wall of preparation
Lingual rest is prepared in enamel of surface of
anterior tooth if it is sound and with prominent
cingulum




Mandibular canines are
poor candidates for
placing lingual rests

preparation




Using cylinder diamond
cut should be made low
on one marginal ridge
pass over cingulum and
pass gingivally to contact
opposite marginal ridge
Rest seat must be
gingival to contact level
of opposing tooth

INCISAL REST SEAT


Least desirable rests on
anterior teeth



Used only on enamel
surface



Usually placed near
incisal angles of canine


PREPARATION




Small safe side diamond
disk is held parallel to
path of insertion
First cut is made
vertically 1.5-2mm deep
in form of notch and 23mm inside proximal
angle of tooth





Small flame shaped diamond
point is used to complete
preparation
Enamel wall created by disk
towards centre of tooth must
be rounded



Base of notch is also rounded



Groove that results after
notch has been completely
rounded must be carried
slightly onto labial surface
and partway down to lingual
surface as an indentation

ABUTMENT TEETH PREPARATIONS
USING CONSERVATIVE
RESTORATIONS




When inlay is restoration of choice proximal and
occlusal surface that support minor connectors and
occlusal rests require modification in restoration
Buccal and lingual proximal margins must be extended
well beyond line angles of tooth






Axial wall is carved to
confirm with external
proximal curvature of
tooth
Gingival seat should be
placed where it can be
easily accessed to
maintain good oral
hygiene

ABUTMENT PREPARATIONS USING
CROWNS
Crowns may be in the form of





Three quarter crowns
Complete coverage cast crowns
Porcelain veneer crowns
Ideal restoration for partial denture abutment is
complete coverage crown


CONTOURING WAX PATTERNS


REFINING CAST RESTORATIONS


LEDGES ON ABUTMENT CROWNS


SHAPING VENEER CROWNS


If veneer is porcelain shaping must precede glazing



If veneer is resin it must precede final polishing


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Preparation for RPD /certified fixed orthodontic courses by Indian dental academy

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