4th year Flashcards
4 aims of the emergency dental treatment of traumatised teeth
Relieve pain
Treat pulp exposure
Immobilise displaced teeth
Provide antiseptics/antibiotics to prevent infection
4 potential radiographs for traumatised patients and when they are indicated
Anterior occlusal
Intra-oral periapical: if suspected root fracture
OPT: if suspected fractured mandible
Soft tissue: if suspected presence of tooth fragment/foreign body
Define crown infractions
Incomplete fracture of enamel without loss of tooth structure
Define uncomplicated crown fracture
Enamel fracture or enamel/dentine fracture pulp not exposed
Define complicated crown fracture
Enamel and dentine fracture and pulp is exposed
Management of crown infractions
Monitor vitality, no treatment needed
2 managements of small uncomplicated crown fracture
Smooth if minimal
Etch, bond and composite
2 managements of large uncomplicated crown fracture
Etch bond and composite/bond tooth fragment
If close to pulp consider indirect pulp cap with calcium hydroxide (e.g. dycal) before restoring with composite or bonded tooth fragment
Method of rebonding a tooth fragment
Make sure tooth fragment is clean
Bevel fragment and tooth, etch, bond and use composite to bond fragment to tooth
Management of complicated crown fracture with small exposure (<2mm), < 24 hours since injury
Dycal, MTA or Biodentine pulp cap and restore with composite resin or rebond tooth fragment
Management of complicated crown fracture with big exposure, < 24 hours since injury
Partial pulpotomy (remove coronal 2mm), achieve haemostasis, cover with Dycal or Biodentine and restore with composite
Management of complicated crown fracture with big exposure, > 24 hours since injury
Extirpate pulp and carry out RCT
3 follow-up times for crown fracture
Review clinically and radiographically at
1 month
2 months
1 year
Define crown-root fracture
Fracture involving enamel, dentine, cementum and the root of the tooth
Emergency management of crown-root fracture
Twist flex wire and composite to splint fractured tooth to adjacent teeth to relieve pain on biting
3 management options for crown-root fracture
Remove fractured coronal fragment, restore tooth
Remove fractured coronal fragment and extrude root surgically or orthodontically and restore
Extraction in extensive crown-root fractures
Define root fracture
Fracture confined to the root of the tooth involving cementum, dentine, and the pulp
3 classifications of root fractures
Cervical 1/3
Middle 1/3
Apical 1/3
Management of root fracture
Reposition coronal fragment and splint non-rigidly for 10 days to stabilise position-can leave up to 4 weeks
Vitality testing and review at 3 weeks, 6 weeks, 3 months, 6 months
Management of root fracture with pulp necrosis
RCT of coronal fragment only
Dress with non-setting calcium hydroxide
Calcific barrier will form after 6-12 months, obturate with Gutta Percha
What percentages of root fractures become necrotic
25%
Define concussion injury
An injury to the tooth-supporting structures without increased mobility or displacement of the tooth, but with pain to percussion
Describe the process of a concussion injury
Impact causes haemorrhage and oedema of periodontal ligament
Define subluxation
No displacement but increased mobility clinically
Describe the process of a subluxation injury
Some periodontal ligament fibres are ruptured, tooth loosened
Management of concussion and subluxation injuries
Remove occlusal interferences
Soft diet
If tooth uncomfortable to bite on splint non-rigidly for < 2 weeks (usually 10-14 days)
Vitality test at time of injury, 1 month, 2 months
Define extrusion
Tooth displaced partially from socket as a result of periodontal ligament and pulp rupture
Define lateral luxation
Tooth displaced horizontally palatal/lingual causing contusion or fracture of alveolar socket walls
Management of extrusion
Reposition under LA
Splint non-rigidly for 2-3 weeks
Clinical radiographic review at 2-3 weeks
Management of lateral luxation
Repositioning under LA
Splint non-rigidly for 3 weeks
Clinical and radiographic review at 3 weeks
Define intrusion
Displacement of tooth into alveolar process
Describe the sound of an ankylosed tooth
High metallic tone as apex impacted into bone
Management of intrusion injury of tooth with immature root
Spontaneous re-eruption may be anticipated over several months
If after 10 days, no sign of movement, give LA and release tooth with forceps
Monitor pulpal healing with radiographs 3,4,6 weeks post-injury
Management of intrusion injury of tooth with mature root
Spontaneous re-eruption is unpredictable/unlikely
Carry out immediate orthodontic extrusion over 2-3 weeks
Carry out RCT
What percentage of intruded teeth will exhibit root resorption
58-70%
How long does it take for ankylosis to occur following injury
5-10 years
Define avulsion
Total dislocation of tooth from socket
Define the most common injury in primary dentition and why it is most common
Avulsion as root development incomplete and periodontium is very resilient
2 features avulsion healing depends on
Length of extra-alveolar period
Storage of the tooth out of the socket
2 contraindications to avulsion re-implantation
Gross caries of tooth
Major loss of periodontal support
Management of avulsion injuries if out of mouth < 1 hour and stored in suitable medium (saliva, milk, saline)
Replant tooth with gentle finger pressure
Splint non-rigidly for 1 week
Antibiotic therapy
Management of avulsion injuries if out of mouth > 1 hour
Remove necrotic PDL
Extirpate the pulp at chairside and obturate with GP
Rinse root with saline and replant
Splint for 4 weeks
2 types of root resorption
Inflammatory (internal or external)
Replacement
Describe the radiographic appearance of external root resorption
Asymmetrical radiolucent shape of surface of root with intact root canal walls
Describe the radiographic appearance of internal root resorption
Ballooning of root canal with intact root surface
2 managements of inflammatory root resorption
Mechanical and chemical debridement, dress with hypocal, once cessation of resorption obturate
Extract tooth
Define ankylosis
Progressive resorption of tooth structure and its replacement with bone as part of continued bone remodelling
Define dental caries
Demineralisation and destruction of the organic substance of a tooth driven by the activity of plaque bacteria
4 factors required for dental caries
Microbial cariogenic bacteria
Dietary fermentable carbohydrates
Tooth environment
Time
What pH does demineralisation of tooth substance occur
Below 5.5
5 surfaces to particularly susceptible dental caries
Enamel pits and fissures
Enamel below contact points
Exposed root surfaces
Defective restoration margins
Adjacent to prostheses
5 caries protective factors
Good saliva flow
Well mineralised enamel
No exposed root surfaces
Fluoride
Antibacterials
3 systemic effects of fluoride during tooth formation
More rounded cusps
Shallow fissures
Less acid soluble enamel due to fluorapatite formation
3 topical effects of fluoride
Inhibits bacterial glycolysis and acid production
Prevents demineralisation
Encourages early caries remineralisation
Concentrations of available fluoride toothpastes
6+ years, low risk: 1450ppm (0.312%)
12+ years, high risk: 2800ppm (0.619%)
16+ years, high risk: 5000ppm (1.1%)
Concentrations of available fluoride toothpastes
10+ years, daily: 225ppm (0.05%)
10+ years, weekly: 920ppm (0.20%)
Concentration of fluoride varnish
22600ppm (2.26%), applied 2-4 times yearly
Concentration of Chlorhexidine products
0.06% mouthwash (twice daily)
0.2% mouth wash (weekly)
1% varnish
3 features of the mechanism of action of Chlorhexidine
Disrupts cell membranes
Inhibits plaque formation
Exhibits substantivity
2 features of Triclosan in toothpastes
Bacteriostatic
Broad spectrum
1 feature of Xylitol in sugar free gums
Reduces levels of Strep mutans
5 consequences of salivary gland hypofunction
Reduced remineralising action
Reduced buffering capacity
Reduced antibacterial action
Increased Candida growth
Risk of mucosal breakdown
2 salivary gland stimulants
Sugar-free gum and sweets
Pilocarpine pharmacological sialogogue
3 saliva replacements
Saliva Orthana
Biotene
BioXtra
4 stages of caries process
Early enamel caries
Active infected dentine caries
Affected dentine caries
Arrested caries
3 caries removal strategies
Complete
Selective one-step
Selective step-wise
Describe risk associated with complete caries removal
Higher risk of pulpal exposure
Describe the marginal caries clearance required for success of partial caries removal
1 – 2mm margin of hard sound dentine required to achieve sufficient peripheral seal
Reduction in pulp exposure seen with stepwise selective caries removal
55% fewer pulpal exposures
Describe the 5 stages of stepwise caries removal
Remove coronal caries from walls and dento-enamel junction before the floor
Ensure carious dentin over pulp is leathery but not soft
Cover leathery affected dentin with setting calcium hydroxide and restore with GIC
Leave 3 months for tertiary dentine formation
Remove GIC and remove affected caries to firm hard dentine then line and place definitive restoration
Reduction in pulp exposure seen with one step selective caries removal
77% fewer pulpal exposures
Describe 2 stages of one step selective caries removal
Place RMGIC liner over affected dentine
Placement of permanent restoration
Describe the reason for providing cuspal coverage
Directs occlusal forces internally to stop flexure and reduce risk of fracture in RCT posterior teeth
Describe a tooth indicated for cupsal coverage with an adhesive restoration
Tooth with only occlusal or <2 walls/cusps lost (<50% tooth)
Describe a tooth indicated for cupsal coverage with a crown/onlay
≥ 2 cusps/walls lost (>50% of tooth)
Describe the basic structure of enamel
Hydroxyapatite crystals arranged tightly in prisms
Describe the histopathology of enamel caries
Loss of enamel structure due to demineralisation and disintegration of enamel prisms
Describe the direction of progression of enamel caries at a contact point
Caries form a cone shaped with the apex towards DEJ and base towards the tooth surface
Describe the basic structure of dentine
Organic matrix of collagen and hydroxyapatite crystals, less mineralised than enamel
Describe the histopathology of dentine caries
Initial penetration of the dentine by caries causes dentinal sclerosis
Microorganisms penetrate the tubules following demineralisation and cause further destruction of dentine by demineralisation and proteolysis leading to formation of necrotic dentine
Describe the direction of progression of dentine caries at the DEJ
Caries form a triangular shape with the base at DEJ and the apex towards dentine
Describe the direction of progression of dentine caries at a fissure
Caries forms a triangular shape with the apex facing the surface of tooth and the base towards the DEJ and dentine
3 zones in caries progression
Zone of destruction with dentine decomposition, discolouration with severe breakdown of tooth structure
Zone of penetration
Zone of demineralisation/decalcification in deepest part in the lesion that is bacteria free
Describe the pulp dentine complex reaction to caries
As the lesion progresses closer to the pulp, the pulp begins to get inflamed will mounts a defence reaction with tubular sclerosis and lays down tertiary dentine
Describe the direction of progression of root caries
Caries spread laterally
Describe the rate of progression of root caries
Slower rate due to fewer dentinal tubules than in crown area
3 components of resin composite
Organic resin matrix
Inorganic filler
Coupling agent
4 indications for posterior composites
Class 1 and 2 cavities small/medium size
Tooth wear
Core build-up
Lab-made composite inlays and onlays
3 advantages of posterior composites
Conservation of tooth structure
Strengthens restored tooth
More aesthetic
4 disadvantages of posterior composites
Technique sensitive
Poorer longevity
Increased cost
Risk of secondary caries due to polymerisation shrinkage
Placement technique for composites
Incremental layering placement where composite is obliquely packed in layers
4 components of amalgam
Alloy containing mercury (3%), silver (67-74%), tin (25-28%), copper
4 advantages of amalgam
High compressive strength
Good longevity
Cost effective
Reduced microleakage
4 disadvantages of amalgam
Low tensile strength, weak in thin sections
Poor aesthetics
Does not adhere to tooth structure
High thermal conductivity
3 indications for amalgam
Large posterior restorations with high occlusal forces
Cavities where moisture control likely to be difficult
Core material
5 requirements of amalgam preparations
2mm occlusal-gingival thickness of amalgam
No unsupported enamel 90° cavosurface angle
Break proximal contacts
Adequate retention and resistance form
Flat occlusal floor
Describe bonded amalgam restorations
Technique of using adhesive to bond amalgam
to cavity
2 clinical indications for bonded amalgam cavities
Large multi-surface cavities
Amalgam repairs
3 advantages of bonded amalgam restorations
Increased amalgam retention
Conservation of tooth structure
Reduced microleakage
3 disadvantages of bonded amalgam restorations
Bond may breakdown over time
Uniform placement of bond on cavity walls is difficult
Longer chairside time
4 causes of amalgam failure
Recurrent caries (5-50%)
Marginal ditching
Excessive creep
Bulk fracture
3 contraindications to amalgams
Confirmed allergy to mercury
Pregnancy/breast feeding
Patients under 15 years
2 components of glass ionomer cements
Silicate glass powder
Aqueous solution of polyacrylic acid
4 advantages of glass ionomer cements
Tooth coloured
Moisture tolerant
Chemical bond to enamel and dentine
Fluoride release
3 disadvantages of glass ionomer cements
Low fracture toughness
Low flexural strength
Low wear resistance
Describe the mechanism of adhesion to tooth substrate of a glass-ionomer cement
No separate bonding agent needed
Ionic bond formed between calcium in the enamel/ dentine and carboxyl ions in the GI
Describe the mechanism of fluoride release of a glass-ionomer cement
High initial release followed by rapid reduction
Fluoride varnishes may replenish GI fl supply for re-release
Describe the setting reaction of glass-ionomer cement
An acid-base reaction
3 advantages of adhesive techniques
Good retention and stability
Reduced microleakage
More conservative
Describe the mechanism behind enamel bonding
Bond to surface irregularities created by etching allows resin tags to interlock with the enamel surface
Describe the mechanism behind dentine bonding
Requires primer and bond after etching to bond with collagen in dentine
Describe wet dentine bonding
Dentine surface should be kept moist but not wet after etching as over-dried dentine leads to the collagen collapse
Describe the smear layer
Layer covering the dentinal tubules, composed of
cut dentine debris and bacteria produced byinstrumentation that reduces dentine permeability
3 advantages of etch and rinse (2 or 3 bottle)
High bond strength
Predictable
Good long-term data
3 disadvantages of etch and rinse (2 or 3 bottle)
Extra step
Potential to over-etch dentine
Degree of ‘wetness’ important
4 advantages of self-etch (2 or 1 bottle)
No need to etch with phosphoric acid
No rinsing
Reduction in post-op sensitivity
Not so technique-sensitive
3 disadvantages of self-etch (2 or 1 bottle)
Enamel requires preparation
Lower bond strengths, but sufficient in most situations
May inhibit set of dual-cure composites
6 advantages of shaping and polishing restorations
Minimise plaque accumulation around margins
Minimise surface staining by tea, coffee and red wine etc on rough surfaces
Minimise surface roughness which may predispose to corrosion in the long-term
Maximise aesthetics of the restoration
Harmonise the restoration with the occlusion
Removal of the oxygen inhibition layer
Define the oxygen inhibition layer
Soft, sticky, uncured layer that forms after light curing composite as oxygen in the air interferes with the polymerisation reaction
Define toothwear
Surface loss of dental hard tissues from causes other than dental caries, trauma or as a result of developmental disorders
Define physiological toothwear
Natural toothwear that occurs due to aging
Define pathological toothwear
Rate of wear is greater than that expected for the patient’s age
Define attrition
Loss of tooth substance by means of friction caused tooth or restoration contact during function
Clinical features of attrition and where it is commonly seen
Sharp, well-defined, interdigitating areas of tooth
Commonly of incisal edges in anterior teeth
Define abrasion
Loss of tooth tissue by means of friction caused by contact of the tooth with an exogenous agent to the mouth
Clinical features of abrasion and where it is commonly seen
V-shaped notching buccal cervical aspect anterior teeth
Commonly on canines / premolars
Define abfraction
Loss of cervical tooth tissue in areas of stress concentration
Clinical features of abfraction
Wedge shaped defects with sharp rims cervical aspect of teeth
Define erosion
Loss of dental hard tissue as a result of a chemical process not involving bacteria
Clinical features of erosion
Smooth concave enamel / dentine and cupped lesions
Common site of extrinsic erosion
Labial surfaces of anterior and posterior teeth
Common site of intrinsic erosion
Palatal surfaces
3 extrinsic causes of tooth erosion
Citrus fruits
Vinegar
Carbonated drinks
2 intrinsic causes of tooth erosion
GORD
Eating disorders
Define BEWE
Basic erosive wear examination that records the most severely affected tooth in each sextant
3 treatment options for localised toothwear
Traditional prosthodontics
Traditional restorations
Dahl concept
Describe the Dahl concept
Build-up teeth to replace missing tissue lost through wear and leave high restorations
Over time teeth adjust through a combination of intrusion (40%) / over-eruption (60%)
3 clinical contraindications to the Dahl concept
Gross Class III malocclusions
Lack of eruptive potential
TMD
3 intervention managements for tooth erosion
Instruction on reducing frequency and severity of acid attacks
Provision of fluoride to enhance resistance to acid attack
Provision of mechanical protection to teeth
4 treatment options for generalised toothwear
Hard acrylic stabilisation splint
Direct restorations
Indirect restorations
Surgical crown lengthening with osseous re-contouring
2 indications for surgical crown lengthening
No loss of OVD
Limited inter-occlusal space
Define occlusion
Static contact between one or more of the lower teeth and one or more upper teeth
Define articulation
Dynamic, gliding contact between one for more lower teeth and one for more upper teeth
4 requirements for occlusal stability
Sufficient number of posterior contacts to maintain OVD
Occlusal stops for all teeth
Contact points
Cuspal locking
Define intercuspal position
Occlusal position in which the greatest number of contact occur between the upper and lower teeth
3 problems caused by occlusal instability
Fracture or wear of teeth/restorations
Mobility of teeth
Temporo-mandibular joint dysfunction
Describe the ideal occlusal scheme
Posterior teeth prevent excessive contact force on the anterior teeth in ICP
Aterior teeth disengage the posterior teeth in all mandibular excursive movement
Describe the conformative approach to restorations
Aims to leave the occlusion with no additional interferences and the occlusion stable
3 indications for reorganisation of the occlusal scheme
Unstable ICP
Complete dentures
Protecting and restoring a worn dentition
Describe 4 features of ideal impressions
Sufficient impression detail
Good blend with heavy and light body
Strong bond between material and tray
No tooth contact with the tray
Give 5 impression errors
Lack of impression detail
Voids on the prep margin
Tearing at the prep margin
Tray tooth contact
Delamination
4 causes of lack of impression detail
Impression material at wrong temperature
Saliva/blood around the prep
Inadequate retraction of gingival sulcus
Excessive working time
4 causes of inhibited or slow setting impression material
Contamination with latex gloves
Residues from temporary cements
Inadequate mix
Incompatible light and heavy body materials
3 causes of voids on the prep margin
Air trapped in light-bodied syringe
Inadequate coverage of margins with light-bodied material
Blood and saliva contamination around the prep
3 causes of tearing at the margin
Expired impression material
Inadequate mix
Insufficient retraction
2 causes of tray tooth contact
Insufficient impression material
Incorrect size of tray used
3 causes of delamination
Long working time
Impression material stored at elevated temperature
Light body and heavy body materials incompatible
2 causes of poor bond of impression to tray
Incompatible tray adhesive used
Inadequate drying time
2 gingival retraction options
Gingival retraction cord
Retraction paste
Define gingivoplasty
Reshaping of gum tissue around teeth
Define gingivectomy
Surgical removal of gum tissue or gingiva
4 indications for gingival electrosurgery
Lengthen the crown of a tooth
Gain adequate access to sub gingival caries
Remove localised hyperplastic fibrous gingiva
Control localised bleeding when recording impressions for crown and bridgework
2 contraindications to gingival electrosurgery
Very narrow width of attached gingiva present
Large amounts of tissue require removal
Define extrinsic discolouration and 2 common causes
Pigment molecules deposited on tooth surface within pellicle
Smoking and diet
Define intrinsic discolouration and 2 common causes
Pigment molecules deposited within bulk of the tooth
Systemic or genetic
4 risks of tooth whitening
Sensitivity
Gingival irritation
Altered taste sensitivity
White spots
3 potential causes of discolouration of non-vital teeth
Breakdown of blood pigments within non-vital teeth
Medications and materials used during root canal treatment
Coronal leakage of amalgam restorations
2 requirements prior to non-vital bleaching
Good root canal treatment with intact coronal seal
No radiographic/clinical evidence of disease
Describe the walking bleach technique for non-vital teeth
Sodium perborate and water delivered internally and sealed with temporary filling
Evaluated after 1 week
Describe the inside-outside technique for non-vital teeth
10% Carbamide peroxide delivered
Internally with dispensing syringe
Externally with whitening tray
Describe night guard vital bleaching
At home tray delivery in soft tray, 1mm thickness with scalloped edges
10% Carbamide peroxide gel (2-4 hrs) or Hydrogen Peroxide (30-60 mins)
