1
Q
what is Hanau’s quint?
A
- 5 factors important in the development of a balanced occlusion/articulation
1 condylar guidance angle
2 incisal guidance angle
3 orientation of occlusal plane
4 cuspal inclination
5 depth of compensating curve
2
Q
average condylar guidance angle
A
25-30º
3
Q
what is Christensen’s phenomenon?
A
if incisal guidance angle is 0º with a flat occlusal plane with cuspless teeth, the posterior teeth will disclude due to the 30º condylar guidance angle
4
Q
what is the incisal guidance angle usually set to and why?
A
- 0º
- if it matched condylar guidance with cuspless teeth = better aesthetics but extreme and tongue would not be able to stabilise the denture as occlusal plane would be 30º
- cuspal inclination used to compensate for incisal guidance angle
5
Q
what should the occlusal plane be parallel to (complete dentures)?
A
- ala-tragal/Camper’s plane posteriorly
- interpupillary line anteriorly
6
Q
what is the cusp angle?
A
angle between the slope of the cusp and the horizontal
7
Q
what is the effective cusp angle?
A
sum of cusp angle and angle of tilt of tooth
8
Q
why may you use a shallower cusp angle?
A
for older pts who those who bite together in many different ways (unreproducible) = less likely to destabilise denture
9
Q
what is a compensating curse and what is it for?
A
- curve of Spee, curve of Wilson
- changes the effective cusp angle without adjusting the form of the denture tooth
10
Q
define balanced occlusion and balanced articulation
A
- balanced occlusion = simultaneous contacts of upper and lower teeth on both sides and anterior and posterior aspects, static, preventing tipping or rotating or sliding of denture base in relation to supporting tissues
- balanced articulation = bilateral simultaneous contact of anterior and posterior teeth in excursive movements, dynamic
11
Q
when is balanced occlusion/articulation desirable and when can it not be achieved?
A
- desired with complete dentures (C/C)
- cannot be achieved with natural teeth present - occlusal interferences
12
Q
give a simple classification of articulators and when they would be used
A
1 non-adjustable: single unit restorations (conformative)
- hinge (class I)
- average value (class II) - also simple denture cases
2 semi-adjustable (class III): more extensive restorations (conformative or reorganised)
- ARCON (condyle part on lower arm)
- non-ARCON
3 fully adjustable (class IV): specialist, not often used due to skills and cost and time
13
Q
what is an articulator?
A
- mechanical instrument that represents the TMJ and jaws
- to which maxillary and mandibular casts can be attached to simulate some or all mandibular excursions
14
Q
what are the values of an average value articulator based on?
A
Bonwill’s triangle (equilateral triangle between condyles and lower incisors ~10cm)
15
Q
difference between semi-adjustable ARCON and non-ARCON articulators
A
ARCON = condyle part on lower arm = more anatomically correct to humans
16
Q
possible presenting complaints if there is an occlusal error in complete denture (8)
A
- instability, movement on function, tipping, difficulty chewing/speaking
- TMJ pain
- lack of retention (eg when swallowing)
- OVD too short = angular cheilitis with some medical conditions
- OVD too high = speech issues
- tongue/cheek/soft tissue trauma
- alveolar ridge pain on one side (uneven force)
- sliding of denture = pain on denture bearing area
17
Q
what is a facebow?
A
instrument used to record the spatial relationship of the maxillary arch to some anatomical reference point(s) and allow this to be transferred to an articulator
18
Q
how may single standing teeth +/or over-erupted teeth affect retention and stability of a denture? (3)
A
- posterior = may be clasped
- roots = overdenture abutment but prevents formation of complete border seal (decreased retention)
- over-erupted = increased OVD, instability if denture teeth not at the same level, cannot get balanced articulation
19
Q
why do we set ICP to coincide with the retruded jaw position (centric relation) with complete dentures?
A
condyle-dependent so reproducible
20
Q
what factors affect the rest position of the mandible? (4)
A
- posture (ideally upright, head unsupported)
- presence of lower denture (prevents relaxation)
- neuromuscular disorders (Parkinson’s, stroke, loss of proprioception) and medication (tranquilisers)
- stress
21
Q
7 features indicating involvement of lower 8 with IDC
A
- close proximity of lower third molar with IDC
- loss of cortication of the inferior dental canal (IDC)
- darkening of third molar roots or ‘banding’
- deviation of the IDC away from tooth roots
- localised narrowing of the IDC
- dilaceration of roots (excess curvature)
- narrowing of the third molar roots (apical area)
22
Q
indications for lower third molar extraction (7)
A
- recurrent episodes of pericoronitis
- unrestorable caries, or caries extending into the pulp
- untreatable PA pathology
- horizontal or mesioangular lower third molar causing disto-cervical caries in the lower second molar (to facilitate restorative treatment of 7)
- third molars with odontogenic cysts or tumors
- third molars impeding surgery (eg orthognathic or tumour removal)
- in the line of a mandibular fracture
23
Q
copy denture techniques (3)
A
- reline copy denture (direct)
- early wash/Dundee (indirect)
- late wash (indirect)
24
Q
pros and cons of copying complete dentures (3/3)
A
+:
- quicker, simplified occlusal registration techniques
- more acceptable for pt
- reproduces successful features
-:
- easy to increase OVD by accident
- changes to base/arch shape or appearance (eg diastemas, crossbites)
- mould production errors
25
describe the reline copy denture technique (indications, pros/cons, steps)
- direct technique for small changes (eg fit surface adaptation), spare dentures
- + = easy, technician can directly compare to existing denture
- - = pt without denture, skilled technician needed
1 wash impression, jaw reg (tech sets teeth)
2 wax try in (processed)
3 fit
4 review
26
describe the early wash copy denture technique (pros/cons, steps)
- most common method, uses wax replica (indirect)
- + = more base stability, easier to maintain OVD, pt keeps dentures, can use with open faced dentures
- - = risk of damaging cast with tightly fitting pour-cure acrylic and ridge form IV
1 2-part mould made from denture (wax/acrylic replica made)
2 adjust clinically, wash impression, jaw reg
3 wax try in
4 fit
5 review
27
describe the late wash copy denture technique (pros/cons, steps)
- + = pt keeps denture, fewer steps
- - = base is not completely stable (jaw relationship errors, movement/centreline shift on impression), not suitable for open faced
1 2-part mould, jaw reg (wax/acrylic replica made)
2 wax try in with careful wash impression/positioning
3 fit
4 review
28
ideal type of denture for lower edentulous arch (McGill consensus)
implant retained overdenture (two implants in canine region)
29
5 principles of crown preparation
- preservation of tooth structure
- retention and resistance form
- structural durability
- marginal integrity
- maintenance of periodontal health
30
ideal retention and resistance form for crown preps (3)
- TOC 6-10º
- height (3 or 4mm)
- height:width at least 0.4
31
pros and cons of addition-cured silicones as impression materials for edentulous pt (4/4)
+:
- dimensionally stable
- good surface detail
- various viscosities available
- elastic
-:
- hydrophobic (air blows)
- cannot be adjusted after set
- more expensive
- longer set
32
pros and cons ZOE as impression material for edentulous pt (5/4)
+:
- good surface detail, low viscosity
- quick setting (accelerated by heat/humidity)
- cheap, stable, good shelf life
- can be adjusted after taking
- good for gagging (thin layer)
-:
- flakes easily so not for undercut areas
- poor taste
- may cause burning/irritation esp if xerostomic, can be allergic to clove oil
- messy
33
describe mucostatic vs mucocompressive impression
- mucostatic = soft tissues not displaced by impression material (gain support from firm areas of arch, better retention)
- mucocompressive = displacement of soft tissues by impression material (better support)
34
three factors affecting displacement of tissues during impression taking
- viscosity of material
- pressure on seating
- spacing of tray
35
what features in the design of a denture may cause trauma to the denture bearing area? (6)
- overextension into sulci or deep undercuts
- not relieving tori or fraenal attachments
- damage or processing issues on fit surface (pearls, roughness)
- deep post dam
- occlusal faults
- poor fit
36
what conditions affecting the denture bearing areas may need treating before provision of (new) dentures? (6)
- denture-related stomatitis
- denture-induced hyperplasia
- enlarged tuberosities
- flabby ridge
- tori
- sharp residual ridges or sharp mylohyoid ridge
37
how do the upper and lower alveolar ridges resorb once teeth are removed? how should the denture teeth be placed relative to the ridge?
- upper = 2.5-3mm height, resorbs buccal TO palatal (smaller arch)
-- teeth buccal to ridge
- lower = 9-10mm if severe, FASTER, resorbs lingual TO buccal (wider arch)
-- anteriors placed more labial, posteriors over ridge or lingual
38
extraoral biometric guides for placement of denture teeth (5)
- upper occlusal plane parallel with interpupillary line
- posterior occlusal table parallel to Camper’s line (ala-tragus)
- midline of teeth = midline of face
- tips of canines = alae of nose
- nose width = 4x centrals' width
39
intraoral biometric guides for placement of maxillary denture teeth (3)
- incisive papilla - labial of centrals should be 8-10mm anterior, canine tips should be in line with back
- palatal cusps over centre of posterior mandibular ridge
- teeth placed buccal to residual ridge
40
intraoral biometric guides for placement of mandibular denture teeth (3)
- occlusal level = lower edge of RMP, at or below maximum convexity of tongue
- centre of alveolar ridge = central fossae
- anterior teeth placed labial to ridge, no further anterior than relaxed labial sulcus
41
how is retention obtained for complete dentures? (6)
- soft tissue undercuts with displaceable mucosa
- cohesion-adhesion of saliva (surface tension, negative pressure)
- close base adaptation
- overdenture precision attachments
- peripheral seal
- oral musculature and tonue
42
define support, retention and stability for complete dentures
- support = resistance of the denture (to horizontal or rotational forces) towards the tissues along the POI
- retention = resistance of the denture away from the tissues along the POI
- stability = resistance of the denture to horizontal and rotational forces created during function
43
landmarks on an upper edentulous impression and their significance (10)
- labial and buccal frenums (for relief)
- labial and buccal sulci (periphery)
- alveolar ridge (tooth placement, posterior ridge for primary support)
- incisive papilla (tooth placement)
- rugae (secondary support)
- midpalatine raphe if cleft palate or tori
- vault of hard palate (primary support)
- vibrating line (part of soft palate that has limited movement during function and movable part)
- fovea palatinae (indicates junction between hard and soft palate, should not be encroached upon)
- maxillary tuberosities and hamular notches (posterior border)
44
landmarks on an lower edentulous impression and their significance (12)
- labial, lingual and buccal frenums (for relief)
- labial, lingual and buccal sulci (periphery)
- raised FOM (prevents displacement during function)
- alveolar ridge (tooth placement, posterior for primary support)
- buccal shelf (support)
- external oblique ridge (do not encroach)
- retromylohyoid fossa (stability, divergent flanges), AKA lingual pouch
- mylohyoid ridge
- retromolar pad and pear shaped pad (occlusal level, support)
- pterygomandibular raphe (do not encroach)
- tori (lingual premolar region)
- genial tubercles (genioglossus)
45
where should the posterior border of the complete upper denture lie? (2)
- anterior to fovea palatini (prevent obstruction of fluid secretion)
- extend into hamular notches (retention)
46
how to manage dentures with palatal tori?
- relieve tori
- change major connector design
- surgical removal
47
what is the point of the post dam on an upper complete denture?
- allows formation of posterior palatal seal
- aids retention
- prevents food trapping in posterior region (gagging, retention issues)
48
define overdenture
removable dental prosthesis covering and resting on one or more remaining natural teeth/roots +/or implants
49
why preserve roots of teeth in overdentures? (5)
- preserve bone height for stability
- improve support for denture
- improve retention with attachments or tissue undercuts
- tactile/proprioceptive feedback
- psychological benefit
50
disadvantages of preserving tooth roots for overdentures (6)
- lower canines = lose stabilising feature
- upper canine eminences too deep to engage with flange
- RCT of abutment (time, cost)
- teeth provide better stability than roots usually (unless precision attachments)
- increased risk of denture base fracture (thinner acrylic)
- maintenance (increased perio and caries risk)
51
factors affecting suitability of a tooth to be used as overdenture abutment (5)
- perio = at least 50% of root within bone, pocketing ≤2mm, no inflammation
- number and location in arch - ideally bilateral, symmetrical, canines best
- integrity of tooth structure
- suitability for RCT if needed
- depth of bony undercut (shallow ideally)
52
maintenance following overdenture creation (4)
- reinforce OHI, denture hygiene
- regular topical fluoride (TP, FV)
- temporary or permanent relining (alveolar resorption)
- replacement of precision attachments as needed
53
complications of implant-retained lower overdenture (8)
- denture fracture
- implant fracture
- wear/corrosion of retention elements
- fracture of retention elements
- abutment fracture
- abutment screw loosening or fracture
- attachment screw loosening or fracture
- gingival hyperplasia
54
define immediate denture
denture inserted immediately after removal of natural teeth
55
why bother making immediate dentures? (3)
- aesthetic - lip and tissue support, face height maintenance
- prevent excessive speech and mastication changes
- protective splint - aids haemostasis and protects sensitive extraction sites from irritation during healing
56
disadvantages of immediate dentures (5)
- often cannot have try in stage
- short term solution
- significant maintenance required after insertion, eg reline, denture hygiene
- usually less than optimum retention
- increased cost of treatment as two sets of dentures required
57
what are the features that may be seen when anterior mandibular natural teeth oppose an upper edentulous arch? (5)
- fibrous change of upper anterior ridge (flabby ridge)
- overgrowth of tuberosities
- papillary hyperplasia of hard palate
- extrusion of mandibular anterior teeth
- loss of alveolar bone beneath a lower RPD
(combination syndrome is NOT a real syndrome)
58
components of an implant (3)
- fixture
- abutment
- restoration
59
describe the shortened dental arch concept (what, why)
- minimum of 20 teeth, premolar to premolar in both arches
- gives enough teeth to satisfy appearance and function needs of some pts
- free-end saddle dentures poorly tolerated, easier to maintain OH on anterior teeth
60
define relining (denture)
addition of material to the fitting surface of a denture base
61
indications and contraindications of denture reline (4/5)
- indications:
-- loss of retention, instability
-- food trapping
-- abused mucosa
-- maintain function of temporary denture
- Contraindications:
-- worn out dentures
-- loss of VD >7mm
-- significant mucosal inflammation
-- poor aesthetics
-- functional issues
62
define rebasing (denture)
partial or complete removal and replacement of denture base
63
indications and contraindications of denture rebase (6/4)
- indications:
-- warped bases
-- base constantly fracturing along a line of weakness
-- immediate denture after 3-6 months
-- diabetic pt complaining of continuous poor retention and stability due to bone resorption
-- cannot bear construction of new dentures
-- economic considerations
- contraindications:
-- severely resorbed ridge (just make new denture)
-- aesthetically unacceptable denture
-- flabby ridge
-- functional issues
64
stages of a treatment plan generally (5)
1 acute
2 stabilisation, prevention
3 reassessment
4 restorative/rehabilitation
5 maintenance
65
template for periodontitis diagnosis
- generalised/localised
- periodontitis
- stage
- grade
- currently stable/unstable/in remission
- risk factors
66
difference between generalised and localised periodontitis
generalised = ≥30% of teeth involved
(localised = <30%)
67
staging of periodontitis
- stage 1 = 0-15% bone loss or <2mm attachment loss from CEJ
- stage 2 = 15-33% (coronal third)
- stage 3 = 33-66% (mid third)
- stage 4 = >66% (apical third)
68
grading of periodontitis
- % bone loss divided by age
- grade A = <0.5
- grade B = 0.5-1
- grade C = >1
69
difference between currently stable/unstable/in remission periodontitis
- stable = <10% BoP, PPD ≤4mm with no BoP at 4mm sites
- in remission = ≥10% BoP (PPD ≤4mm with no BoP at 4mm sites)
- unstable = PPD ≥5mm or ≥4mm with BoP
other bds5 things
flashcards
Decks in class (5)
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