rp Flashcards
th’ pbm
standing
facing villa
Pronunciation of words, especially sounds like what to observe?
- S: 1mm space between acrylic teeth/ record blocks
-F/ V: Observe contact between lower lip and upper record block - TH: Observe contact between tongue and upper record block
-P, B, M: Lips should lightly contact; if they don’t, OVD excessive
Discuss the factors that determine whether and edentulous space from 12 to 22 should be restored
with a fixed partial denture or a removable partial denture. There is no other edentulous space in the patient’s dentition.
6x
1 Patient factors – med hx, age, dexterity (ability to maintain OH)
2 General oral condition – active disease, caries risk, parafunction, periodontal
3 Area specific – Ridge form (siebert’s classification) -> need for augmentation -> predictable outcome? Span length
4 Abutment condition– Alignment, restoration, clinical crown height, periodontal support (bone, mobility, C:R ratio)
5 occlusion-deep/grp function
6 Others – time ,cost, operator skill
classify the partially edentulous arch
class I
class II
class IIII
class IV
I-bilateral free end saddle, posterior to natural teeth
II- unilateral FES
III- bounded saddle
IV- single edentulous area crossing midline -no modifications
denture classfication + Modifications
applegate rules 8 rules
Rule 1 Classification should follow (rather than precede) extraction.
Rule 2, 3, 4= If the 3rd molar is missing and not to be replaced, it is not considered in classification;
If the 3rd molar is present and is to be used as an abutment, it is considered in the classification.
Rule 5. Classification is always determined by the most posterior edentulous area.
Rule 6. In classes I to III, each extra bounded saddle is described as a modification Spaces
Rule 7 Extent of modification is not considered, only the number of additional edentulous areas.
Rule 8 Class 4 has no modifications
Surveying is a diagnostic procedure of 3x….. prior to….
req… to draw… indicating… in relation to
locating, delineating and appraising the contour and position of the teeth and alveolar bone prior to designing a removable prosthesis.
Requires dental surveyor to analyse the cast of a patient’s mouth and draw lines indicating undercut areas in relation to paths of insertion/removal of the dentures
guide planes help…
guide planes are…
guide the placement and removal of RPDs.
are parallel surfaces on **axial surfaces ** of abutments that must be prepared 2-3mm (or identified) so that they are also parallel the path of insertion=>obtain a single path of insertion for RPDs
Functions of Guide Planes:3x
1 Directional Guidance:
Ensures a singular path of insertion and removal.
Prevents strain on abutment teeth+prosthesis components during placement or removal.
2 Facilitates the effective action of reciprocal (counteracting), stabilizing, and retentive components of the denture.
Provides retention against dislodgment forces not parallel to the path of removal+ reduce clasp needed.
Offers stabilization against horizontal movements (rotation) of the denture.
3 Eliminates u/c: prevent large food traps between abutment teeth and denture components, enhancing esthetics, comfort and hygiene.
4 factors THAT DETERMINES PATH OF INSERTION GERI
1 Guide plane
2 Esthetics -> reduce display of base material
3 Retention->to make use of soft tissue U/C in anterior saddles by varying path of insertion from that of path of displacement
4 Interference -> need modification on tooth cm2
GERI
The disadvantage of having a vertical path
of insertion/removal is that it coincides
with…
then what?
solution?
path of displacement when denture wearer eats sticky foods.
o Retention will then depend entirely on clasps
o Solution? Retention of RPDs can be
obtained from extensions of denture base into undercuts by using an oblique path of insertion /removal
saddle is the part of the denture that covers….
function=2x
the alveolar ridges and carries artifical teeth.
Functional [support], retention by close fit +work with saliva [coh/adh forces]; and aesthetic roles of providing replacement for lost alveolar tissue.
why saliva important for retention of denture? 4x
Cohesive forces within saliva
Viscosity of saliva-thin/thick=if excessive viscosity, there will be discontinuity in the film (bubbles causing air to flow in more readily,seal affected)
Surface tension:closer the fit of the denture, stronger the retentive forces attributable to surface
tension
Closeness of adaptation to the oral mucosa -adhesion
reciprocator Opposes force exerted by the…during…and enhance efficiency of…
prevent…
Opposes force exerted by the clasp arm during seating and unseating of the prosthesis and enhance efficiency of retentive clasp
Prevents tooth movement laterally
eg- reciprocal arm/rigid connector
Indirect retainers- explain
CI; CII KClassification- DEB///LONG span CIV- gets dislodged, it tends to rotate about fulcrum lines/abutment
Hence, this rotational movement can be counteracted by indirect retainers -placed furtherest away from fulcrum.
Direct Retainers
what is it and Purpose:
Clasps attached to abutment teeth or parts to secure a removable partial denture (RPD) in place.
Function: Provides resistance to dislodgment in an occlusal direction, keeping the RPD stable against forces that attempt to move it away from the ridge.
Examples of Direct Retainers
Clasps: C-clasps and roaches.
Guide Planes:
Soft Tissue Undercuts (Flanges)
Denture Base Surface (Cohesion Adhesion)
Muscular Control wearer to aid retention.
Springs
Precision Attachments
Magnets
implants
TYPES OF FORCES ACTING ON RPD
i VERTICAL
ii HORIZONTAL
ii rotational
what resist it?
resist VERTICAL -towards alv ridge = Support
resist forces move it away from ridge= retention
Lateral or anterior-posterior-BRACING/stability
rotational-IR
denture design - think of
oSCARR
outline saddle, SUPPPORT-Occ rest; Connector, and retain -clasp, and reciprocate
denture design within… zone- where is this space?
neutral zone (space bet tongue & cheeks where opposing muscular forces are in balance)
base extension shld …
if considerable resorption anteriorly?…
1 max coverage to distribute forces over larger area
2 Labial flange -> if considerable resorption has occurred, if not gum fit-better esthetics
Components that provide support
- Rests
- Denture base and flanges
- Major connectors
support [RPD] classified as
Defined as…
- Tooth supported
- Mucosa supported
- Tooth and mucosa supported
resistance of the denture base against forces directed towards the ridge.
bracing vs reciprocating
bracing:-
1 Resistance to horizontal components (of masticatory forces) tends to displace denture in antero-posterior and lateral directions
Only occurs when denture is fully seated
reciprocator -Opposes force exerted by the clasp arm during seating and unseating of the prosthesis and enhance efficiency of retentive clasp
Prevents tooth movement laterally-similarities.
Discuss this harmful effects 6x of removable partial dentures
and the ways in which these may be minimized.
1effects on ging, infl of mucosa - ROUGHcm2, localized pa, lack support,
2 tooth mobility when leverage ON exisitng tooth- FESweaken abut,
3 denture caries,
4 food trap-Candida,
5 acc. bone resorption - OVD mismatch
6 overextended flange-ulceration;
proper design, freq recall
Denture Base Material Choice— Cobalt-Chrome (CoCr) versus Acrylic:
Factors Influencing Denture Base Material Choice 9x
1 Time:
Lifespan: Is the denture transitional or definitive?
Construction Time: CoCr takes longer to construct.
2 Cost:
Expense: CoCr is generally > expensive than acrylic.
3 Support: Mucosal borne dentures are usually made of acrylic.
4 Retention:
Limitations: Acrylic base plates have a limit to the number of connectors that can be incorporated without compromising strength.
5 Weight & Bulk:
Material Thickness: Metal alloy (CoCr) can be cast thinner than acrylic while maintaining strength and rigidity.
6 Desirability: Thinner material is preferable in areas requiring maximum space, like under the tongue.
7 Tissue Health:
Gingival Relief: CoCr may require more gingival relief than acrylic.
Oral Hygiene: CoCr is inherently cleaner than acrylic, which tends to accumulate mucinous deposits containing food particles.
8 Thermal Conductivity:
Temperature Transmission: CoCr transmits temperature changes to underlying tissues, helping maintain health of those tissues.
9 Accuracy & Permanence of Form:
Form Maintenance: CoCr maintains its form better in the oral environment, being < prone to distortion compared to acrylic.
Adjustments: CoCr is more difficult to adjust and reline than acrylic.
6x Adv and 4x limitations of Co-Cr
- Advantages and Limitations
Advantages:
CoCr dentures provide better support, less bulk, superior cleanliness, and more accurate form maintenance and last longer
Better thermal conductivity which helps with tissue health.
Limitations:
Higher cost, time* and complexity in manufacturing.
Difficulties in adjustment and relining after fitting.
altered cast technique
anatomic imp (sectioned off) and joined functional imp for the DEB
eg of mucosal support 3x
full palatal coverage
or spoon denture or every denture
fx of rest 9x
loah chun fai man boob is REally enormous [in october]
-load transmission through longitudinal axis of tooth
-avoid Cervical impingement
- avoid Food trap
-maintain clasp-tooth rshp in proper position
-bracing and IR
-Provide positive Reference seats in rebasing procedures
-prevent Extrusion of unopposed tooth
[improve occl] contacts
why need prepare rest seat prep 7x
red. Prominence
prevent interference
prevent tooth migration
more Vertical loading
more efficient support
improve the fit
aid in self cleansing
Borders of connector should be more … from gingival margin for maxilla,
for mandible
> 6mm-Mx
> 3mm-Md
5x Flexibility of clasps is dependent on design
1 Cross sectional shape of clasp: A round section clasp will flex equally in all directions, whereas a
half round clasp will flex more readily in the horizontal than in the vertical plane
2 Thickness: If the thickness is reduced by half, flexibility is increased by 8x
3 Length of clasp arm
o The longer the clasp arm, the more flexible.
4 Material used for clasp
o Co-cr more rigid than wrought wire
5 Design of clasp: Depth of undercut engaged
and Direction of approach of clasp
RPA clasp similar to the RPI clasp except that in place of the I bar a …. arises from…
indications-2x
design of RPA CI in FES is when …. originate from … rest and engage in …. u/c
circumferential clasp arm arises from the proximal
plate.
Indications: Buccal vestibule insufficient depth, buccal tissue undercuts too great
NOTE:
Conventional cast C clasp that originates from disto‐occlusal rest and engages mesio‐facial undercut should not be used on FES
MM Rshp the positional …
The positional relationship between the mandible and maxilla
OVD: Establishing a occl- vertical dimension
CR: Establishing a reproducible horizontal relationship with the mandible
*These two components are interdependent; one cannot be changed without changing the other
Resting VD distance between
distance between the maxilla and mandible when
mandible is in its physiologic/habitual rest position
pt sit comfortably in the upright position with the condyles in a neutral unstrained position in the glenoid fossa
LONG centric
intercuspal contact area; mandible occludes into centric relation or slightly anterior to it without varying the vertical dimension of occlusion
Condylar inclination
The angle at which the condyle descends along the articular eminences in the sagittal plane
Bennett’s Shift
Bodily lateral movement of the mandible towards the working side during lateral excursion
teeth arrangement for DENTURE
// to …line
…. +… at occlusal plane
…1-2mm above occl plane
midline…
Parallel to alar tragal line
Parallel to inter-pupillary line
o Canines and incisors at the occlusal plane
o Laterals 1-2mm above occlusal plane
midline- centre of face
if tooth is too….. from path of insertion, add CR if unfavourable U/C because….
SOLUTION? 2x
if tooth is too divergent from path of insertion, CR will be grossly overcontoured+ unhygienic
Changing path of insertion or uprighting the
tooth orthodontically may be preferable
REASONs for overdenture 3x
- Maintenance of alveolar bone-allows fabrication of more stable; retentive dentures ensures comfort
- Sensory feedback
a. Tactile sensitivity discrimination
-improved control of appliance - Reduction of psychological trauma
Relines most common using
repair using…2x
Kool liner
cold cure autopolymerizing resin
TYPES OF MANDIBULAR CONNECTORS 5
- Lingual plate
- Lingual bar
- Sublingual bar
- Continuous bar
- Labial bar
TYPES OF Max CONNECTORS
- horse shoe
- A-P palatal bar/strap
- Ring
- Palatal plate
5 Mid palatal bar/strap
PPS
soft tissues along the junction of the hard and soft palate on which pressure within the physiological limits of the tissues can be applied by a denture to aid in retention.
bn ant and post vibrating line
ant vibrating line
Refers to the …. located at the junction of
the …..
Never a straight line due to
…..
imaginary line located at the junction of the attached tissues overlying the hard palate& the movable tissues of the immediately adj soft
palate.
Projection of the posterior nasal spine.
Posterior vibrating line Refers to the:
imaginary line at the junction of the aponeurosis of the tensor veli palatini muscle and muscular portion of the soft palate
Represents the demarcation b/n the soft palate that has limited or shallow movement during function and the remainder of the soft palate that is markedly displaced during functional movements.
