Study Flashcards
border moulding:
- on tray borders
- in secondary impression
- first ensure correct border extension
- incrementally add greenstick compound
- to obtain peripheral seal between the mucosa and the denture
- to record sulcus depth and width accurately
- both for CD and RPD
- for RPD is done in the mandibular anterior lingual sulcus and free end saddles bc we aim full extension of the flange -> to allow major connector fabrication in abutment teeth and gingival approaching clasps
-custom tray with ZOE
RPD Design steps:
mark teeth to be replaced POI support - rests/saddles retention - clasps stability - bracing arms major connector indirect retention undercuts modify if needed
RPD construction steps:
examine primary impression study casts occlusal rims and wax bases preliminary JRR mount primary casts on articulator survey primary casts RPD design custom trays tooth preps secondary impression working casts metal framework fabrication metal framework insertion definitive JRR mount secondary casts tooth mould and shade tooth setup trial insertion finish placement
CD construction steps:
examine
primary impression
- to create the study casts
- mucostatic tech
- to record all tissues and sulci
- with stock tray
study/diagnostic casts
- for diagnosis
- to study the occlusion
- to fabricate the custom trays
custom trays
-to carry out 2ry impressions with border molding
secondary impressions
- to carry out border moulding to achieve peripheral seal
- mucocompressive tech
- ZOE
- with custom tray
working casts
-to create denture base which are stable, well supported and retentive
permanent denture base
- to ensure early that they are R,S,S
- to carry out JRR
occlusal wax rims
-to carry out JRR
JRR
- to find OVD, FWS and occlusal plane
- to find the position of the mandible relative to maxilla -record the H maxillomandibular relationship in RP of mandible at the selected OVD
mount casts on articulator (using facebow record)
tooth mould and shade
tooth setup
trial insertion
placement
check record
- to assess the occlusion
- carry out any occlusal adjustments
- to confirm the OVD
JRR =
= any positional relationship of the mandible relative to the maxilla
-vertical, horizontal or lateral (ex: CR, MIP, RP)
For ICP cases: MIP
For non-ICP cases: RP
Perforations on custom tray:
reason:
material:
- so that there is no detachment of impression material during impression removal
- for alginate only
tissue stops on the rims of custom tray fabrication:
- to have adequate space b/w tray and teeth, so that when loading the material we will know where to stop
- to repeat position of tray as many times we want
- to do border molding
why do we prepare teeth?
to ensure V loading
to avoid H forces
to avoid occlusal interferences
fitting surface of tray
non-fitting surface of tray
fitting surface of tray -> rough -> to enhance material retention during tray removal
non-fitting surface of tray -> smooth -> to avoid gag reflex
alginate vs silicone:
alginate:
ADV: non-toxic, cheap, pleasant taste, hydrophilic, elastic
DISADV: less surface detail, low tear strength, low dimensional stability
silicone:
ADV: high tear strength, high dimensional stability, high dimensional accuracy
DISADV: expensive, if undercuts then it locks
RPD lab prescription:
patient and student names type of RPD (acrylic or metal) material (PMMA or CoCr) teeth to be replaced design components (rests, clasps, major connector, bracing arms) tooth mold and shade confirm disinfection date and time work is required (1 day before app)
Trial insertion purpose:
occlusion, aesthetics, flanges waxing, gumline, polished surfaces
RPD
Finishing purpose:
check if the laboratory didn’t overtrim or overpolished the borders in free end saddles (no sharp edges)
Placement purpose:
comfort first thing to assess -> pressure indicating paste
then occlusion
then ensure placement/removal, satisfactory retention, support, stability and correct occlusion and aesthetics
CD
permanent base: (instead of temporary base)
ADV:
DISADV:
ADV:
- all adjustments are carried out on the permanent base at an early stage
- support, stability and retention can be assessed early on so there is time for corrections
- JRR is much easier
- at placement the denture base and borders will hardly need any adjustment
- at placement excessive trimming of base and borders can be avoided
DISADV:
-extra work for lab and extra costs
CD
occlusal wax rims measurements:
upper jaw:
labially to extend 7-8 mm anterior to center of incisive papilla
doesn’t extend beyond M2
height: 10 mm anteriorly, slopping down 0.8 posteriorly
width: M 8-10 mm, P 5-7 mm, I 3-4 mm
lower jaw:
extends slightly anterior to the crest anteriorly (on the crest of the ridge)
doesn’t extend beyond M2
height: 2/3rds of retromolar pad posteriorly, slopping up to 8-10 mm anteriorly
width: M 8-10 mm, P 5-7 mm, I 3-4 mm (same)
JRR steps:
- maxillary rim placed inside the mouth
- > occlusal plane based on aesthetics and anteroposterior position based on lip support
- > angle between columella and philtrum 90 degrees
- > laterally the wax rim should be parallel to ala-tragal line
- > Fox bite plane to help establish occlusal plane
-measure the RVD
- mandibular rim placed inside the mouth
- > ensure even contact
-measure OVD
- measure freeway space (should be 2-4 mm)
- > RVD-OVD
- > 2 dots placed with a skin marker and measure with dividers and ruler
- > if not enough space for FWS start reducing from mandibular rim
JRR:
- retention grooves
- vaseline on one of the two rims
- registration material (ZOE/wax/PVS)
- mark canine tip
- RP
components for:
support:
stability:
retention:
indirect retention:
support: rests, saddles, mucosa, base
stability: bracing arms, flange, minor connector, base, sufficient height and width of alveolar ridge
retention: saliva, clasps, correct border extension, good base adaptation, sufficient border seal
indirect retention: flange, cingulum bars
Anatomical structures of maxilla and mandible:
maxilla:
labial sulcus - labial frenum, orbicularis oris m
buccal sulcus - buccal frenum, buccinator m
incisive papilla - position of incisors, canines and midline
palatine raphe
palatal gingival remnant - palatal tooth surfaces
vibrating line - posterior palatal border
hamular notch - tensor veli palatine, coronoid process, masseter m
mandible:
- labial sulcus - labial frenum, orbicularis oris m, mentalis m
- buccal sulcus - buccal frenum, buccal shelf, buccinator m, mental foramen
- retromolar pad - masseteric m
- anterior lingual sulcus - lingual frenum, genioglossus m
- posterior lingual sulcus -mylohyoid m, retromylohyoid fossa
review appointment for:
RPD or CD:
immediate dentures:
RPD or CD: 1 week after placement
immediate dentures: next day
then review after 6m
why immediate dentures cannot be considered a predictable tx option:
/
limitations of immediate dentures:
- JRR may be incorrect due to condition of remaining teeth
- presence of deep soft tissue undercuts
- placed while the patient is under LA effect
- placed in patients who haven’t accepted the fact that they are edentulous
- can be their first denture wearing experience and can also be a negative one
- impression procedures are suboptimal
Immediate denture construction steps:
examine primary impressions study casts survey IPD design custom trays secondary impressions working casts record base and occlusal rims JRR mount casts on articulator tooth mold and shade tooth setup trial finish placement
main concerns with Kennedy Class:
1:
2:
3:
4:
1:
free end saddles support
-especially on the mandible
-prevent saddles movement towards tissues
-wider residual ridge coverage
-rpi clasp system (protects abutment tooth from pulling forces)
2:
free end saddles support and RPD extension
-cross arch stabilization needed
-consider implants
-avoid unilateral design so that patient doesn’t swallow/inhale it
3: occlusal interferences and RPD extension -cross arch stabilization needed -consider implants -avoid unilateral design so that patient doesn't swallow/inhale it
4:
POI, aesthetics, type of major connector, black triangles, big enough denture so that patient doesn’t swallow/inhale it
-labial flange needed (posterior tilt and then rotating posterior denture part)
-clasps placed on molars, not on anteriors
Semi-adjustable articulator:
- easier to understand mandibular movements
- facilitates CD construction
- allows more adjustments
- accepts facebow transfer
- works for both fixed and removable
how can a RPD cause damage to the remaining teeth?
- plaque accumulation resulting in caries and perio disease
- creating occlusal interferences which may cause excessive wear of opposing teeth
- transferring H forces to abutment teeth
- causing crown fracture if occlusal rests are not designed correctly
- damage of mucosa, non-abutment teeth and ridge if RPD design is incorrect
steps done in the lab - examples:
fabrication of custom trays
fabrication of metal framework
tooth set up
finishing
Relining:
indication:
how to assess clinically:
indication:
- loss of support of free end saddles
- food trapping
- patient reported discomfort
- aesthetics
-assess what happens if you press the free end saddle
tooth preps:
- thin layer on enamel
- no LA needed
-guide planes:
done to establish POI and avoid path of withdrawal
3 mm height
remove < 0,5 mm and follow tooth circumference
for reciprocation
why do we prepare rest seats on teeth?
- to avoid food trapping
- to avoid occlusal interferences
- to avoid H forces
- to achieve the most favorable distribution of occlusal forces
major connectors:
maxillary:
mandibular:
maxillary
- palatal strap (single or anterior/posterior)
- > single: K class iii
- > anterior/posterior: all K classes
- > rigid, little interference w/ tongue
- palatal plate
- > covers more than half of the plate
- u-shaped (for torus)
- palatal bar
mandibular
- lingual bar
- > hygienic, good aesthetics, no interference w/ tongue
- > needs 7-8mm height, issues w/ tooth additions
- lingual plate
- > needs less than 7-8 mm height, easier future teeth additions
- > not as hygienic, visible, interference w/ tongue
- sublingual bar
- cingulum bar
- lingual bar with cingulum bar
- labial bar
- > for retroclined teeth
What will happen if the free end saddle is not well supported?
- The RPD will ‘sink’ towards the tissues
- Denture teeth will not be in occlusion any more
- Pain and discomfort
- Increased rate of residual ridge resorption
- Tilting forces applied on distal abutment tooth
- Excessive forces applied on the other teeth
- Anterior components of the RPD will tend to ‘lift’ away from the tissues
- Further damage soft and hard tissues
study cast vs working casts:
study casts:
- primary
- diagnostic reasons and tx planning
- dental stone III
working casts:
- secondary
- metal framework fabrication
- dental stone IV
primary impression steps:
- stock tray
- modify tray with wax
- adhesive
- putty (only on edentulous areas)
- place in mouth
- cut 2-3 mm when out of mouth to create space for alginate
- adhesive
- alginate
- place in mouth
RPD:
JRR:
preliminary:
Vs
definitive:
preliminary JRR:
- to mount the primary/study casts
- before tx plan finished
- occlusal wax rims with record bases
- to check whether and how we can fabricate an RPD
Vs
definitive JRR:
- to mount the secondary/working casts
- occlusal wax rims with metal framework instead of record bases
- to set up the artificial teeth
- during RPD fabrication
surveyor =
paralleling instrument for prosthesis reconstruction
-for abutment teeth and associated structures position
custom tray:
- needed instead of stock tray due to specific material thickness
- if locked is easy to be cut in half instead of using a stock tray
- you can reduce potential errors in depth and sulcus during impression by controlling extension and shape of tray borders
- for border molding
check record:
OVD confirmation
JRR confirmation
occlusal adjustments - premature interferences
dentures left overnight:
bacterial overgrowth bone loss cracks -> soaked in liquid all night colds/illnesses due to bacteria gum inflammation looser dentures bone resorption -vely affects saliva -> denture stomatitis
‘My dentures are loose’ may refer to:
- Lack of effective border seal
- Lack of close contact between denture bearing tissues and denture base
- Underextension
- Overextension
- Lack of stability
- Lack of support
- Premature occlusal contacts
‘I can’t eat with these dentures’ may refer to:
- Lack of support
- Lack of stability
- Pain due to overextension
- Pain due to premature occlusal contacts
- Insufficient interdigitation
- Significantly reduced OVD
- Increased OVD
- Incorrect occlusal plane level
‘These dentures don’t look right’ may refer to:
- Incorrect anterior tooth setup vertically, e.g. maxillary anterior teeth set up too high or too low
- Incorrect anterior tooth setup horizontally, e.g. maxillary anterior teeth set up too far labially or palatally
- Incorrect tooth mould
- Incorrect tooth shade
- Asymmetrical tooth setup
- Midline mismatch
- Incorrect occlusal plane orientation
- Excessive labial flange thickness
- Insufficient lip support
- Overextension of the mandibular buccal flange
‘My dentures are too big’ may refer to:
- Excessive OVD -> decreased FWS - megalo stoma
- Excessive denture base thickness
- Excessive polished surfaces thickness
- Overextension
- Incorrect tooth mould (size) -> poli megala dontia
for severe gagging reflex patients:
- choice of trays that don’t extend excessively
- choice of impression materials that don’t easily flow backwards
- choice of the right amount of this material so you don’t end up with excess flowing backwards.
pain only during removal/insertion of denture:
insufficient relief from undercuts
localized pain/discomfort:
due to poor impression technique
posterior overextension:
difficulty in swallowing
generalized pain/discomfort:
underextended denture base
increased OVD
lip biting: Vs cheek biting: Vs tongue biting:
lip biting:
- insufficient lip support
- decreased OVD
- insufficient overjet
- upper anteriors set too palatally
cheek biting:
-posterior teeth placed too palatally
tongue biting:
- posterior teeth placed too lingually
- occlusal plane set too low
8 common reasons an RPD would suddenly become unretentive after years of it being successful:
- periodontal condition of abutment teeth
- fracture of clasps
- resorption of alveolar ridge
- denture stomatitis
- allergic reactions causing irritation of the tissues
- xerostomia (medications)
- broken rests providing indirect retention
- teeth loss
4 ways to confirm the OVD in CD clinically:
- check record
- phonetics
- incisors height measurement
- previous photographs
- patient relaxation
mucostatic technique:
mucocompressive technique:
selective-mucocompressive technique:
mucostatic technique:
-primary impressions of RPD or CD
mucocompressive technique:
- records an impression with all tissues in function
- in CD 2ry impression
selective-mucocompressive technique:
- records an impression with some tissues in function and others at rest
- in RPD 2ry impression
- you select where you will have space (1 sheet for mucosa and 2 sheets for teeth)
bracing arm:
clasps:
bracing arm:
above undercut
clasps:
below undercut
polished surfaces affect:
retention and stability
speech considerations: bilabial: labiodental: linguodental: linguoalveolar: linguopalatal and linguovelar:
bilabial: lips
labiodental: lips and teeth
linguodental: tongue and teeth
linguoalveolar: tongue and anterior palate
linguopalatal and linguovelar: tongue and palate
increased OVD:
Vs
decreased OVD:
increased OVD:
- lack of FWS
- decreased stability
- loss of retention in function
- dentures look too big as well as teeth
- lips unable to seal
- difficulty eating and swallowing
- PAIN along the periphery or on ridge crest
- pain worsens as the day progresses
Vs
decreased OVD:
- excess FWS
- stability, support and retention not directly affected
- cheek/lips/tongue biting
- insufficient lip support
- muscular tenderness (tired pt)
- eating difficulty
SOS
a patient comes with a CD done from a different dentist complaining they are loose - what are you going to evaluate?
let the patient tell you the problem - most important interview history IOE EOE dentures in situ dentures out of mouth
- when did dentures become loose
- are they loose all the time
- did they become loose gradually or suddenly
- on both sides
- specific sounds produced
may refer to:
- lack of border seal
- lack of contact b//w denture base and denture bearing tissues
- underextension
- overextension
- lack of support
- lack of stability
- premature occlusal contacts
SOS
you did a CD to a patient and reports a problem.
what are you going to check?
occlusion -> any occlusal interferences
frenum -> not to displace the denture or be overextended
undercuts -> if pain upon removal/insertion
cheeks -> if teeth placed too palatally
polishing surfaces -> if pain upon on mouth opening due to excessive thickness
Regardless the case we need to check:
- retention, stability, support
- fitting surface of base
- check the border extension
- occlusion
- speech
SOS
RPD
survey steps:
survey cast
tilt -> find poi, minimize black triangle, avoid interferences, maximize retention
- visual assessment
- initial survey: horizontal
- tilting the cast: anteriorly or posteriorly
- final survey at selected tilt: ensure undercuts present both at tilted and horizontal positions
- mark the selected tilt
