ICP Flashcards
What organisms causes acute ulcerative gingivitis?
Spirochaetes eg treponema
Fusobacterium
Where are oral obligate anaeobic bacteria found?
Root canal and pulp chambers infection
Abscess
Advanced periodontitis
Carious dentine
What is the most prevalent type of fungi in the mouth?
Candida albicans
Which bacteria are found on oral mucosal surfaces
Streptococcus salivarious
Which gram positive cocci are present as commensal flora in high numbers in saliva and on tongue
Facultative streptococci
Which bacteria forms black pigmented colonies on blood agar
Porphyromonas, prevotella - they are obligate anaerobic bacteria and comprise large prop of microflora in dental plaque. Rarely found in health. Isolated from subgingival sites.
What is caries
Loss of tooth substance by metabolically produced acids.
Common in pits, fissures.
What does statherin do
Binds to calcium phosphate to prevent it from precipitating out, therefore maintaining levels of calcium for remin of tooth and phosphate for buffering action.
What are the iatrogenic (drug) causes of xerostomia?
Aspirin- NSAIDS Diuretics eg furosemide Antihypertensive eg atenolol, clonidine. Antiepileptic eg phenytoin (grandmal) Antihistamine eg loratadine
Which autoimmune condition can cause xerostomia
Sjogrens syndrom - causes acinar destruction in salivary gland therefore reduced saliva production = higher risk of infections eg candidiasis and caries
What is a fissure sealant
Material placed in fissures and pits to PREVENT and ARREST development of caries.
It is a preventive * measure.
What materials are used for fissure sealant
Unfilled resin or filled - light/chemically cured.
GIC - when isolation is a problem eg partially erupted teeth in high caries risk child.
SR procedure
Clean - rubber cup, rotary brush, air abrasion
La - if multiple teeth need it, or if caries into dentine.
Rubber dam if la was used or other isolatuon.
Caries removal, minimal, use 330 tungsten carbide, make edj caries free.
Primer - hema containing - bonds to collagen via OH bonds, apply 15s n air dry 5s. Rub it in using microbrush.
Bond, sensitive to light, seals dentinal tubules, apply 15s n air3s, light cure 20s.,
Apply comp resin or flowable comp if cavity too small. Light cure. Check for defects using probe n remove excess.
Apply FS to remaining pits n fissures, occlusal palatal n buccal. 1/3 cuspal incline. Use microbrush. Cure 20s.
Check occlusion
Why is isolation needed for fissure sealant
Cuz the etched enamel is porous and may get contaminated with debris during procedure which will reduce n prevent resin tag formation of composite bond to the enamel.
When is a SR/PRR indicated
When diagnostic methods, visual inspection, and bitewing radiographs have shown that a stained fissure has progressed to a lesion just into dentine. (If has progressed more then will require conventional restoration)
Advantages of air abrasion (aluminium oxide/ sodium bicarbonate particles)
1) no vibrations therefore painless n noiseless
2) doesnt result in a smear layer during tooth prep
3) carious tissue removed without affecting healthy teeth
4) no post op sensitivity
5) no burning smell or micro fractures in teeth tht often occurs with drilling.
6) sealants and fillings bond better to tooth
What are the effects of cavity prep on dentine?
Produces vibrations which may cause shift in pulpal blood flow
Will cause pain due to presence of nerve endings in dentine tubules.
Will cause fluid shifts eg cut dentine causes outward fluid shift n collagen deposition forming a smear layer
Odontoblasts may get displaced into dentine tubules n will die, but if dentine is sterile then new odontoblasts can differentiate from stem cells in pulp.
What is enamel hypoplasia
enamel matrix formation is defective resulting in thinned, grooved, pitted enamel.
Wats hypomineralisation
Disturbance of calcification of enamel whereby it is weak n prone to breakdown. seen alongside hypoplasia but one predominates usually.
Why is calcium hydroxide bacteriostatic?
Cuz its alkaline ph11
Cuz it absorbs co2 which is a metabolic requirement of the obligate anaerobic bacteria that are present in dentine caries and pulpitis
Functions of PDLs
Sensory info
Dissipates masticatory forces therefore protecting the tooth.
Source of stem cells for new bone, cementum, other CT cell types.
What is a periodontal pocket (its different to gingival pocket)
A sulcus that has deepened due to loss of periodontal attachment, the resultant depth will be greater than the normal 3mm.
5 points characterising gingivitis
1) gingival oedema (therefore loss of contour)
2) hyperaemia (therefore bleeding and redness) - excess of blood supplying your gingiva
3) increased gcf flow and containing neutrophils
4) increased lymphocytes and plasma cells in the infiltrate indicate increased severity
5) reversible !
5 points characterising periodontitis
1) similar inflam infiltrate to chronic gingivitis
2) PDL and alveolar crestal bone is lost which may be follower by gingival recession
3) apical migration of junctional epithelium resulting in deeper pocketing more than 3mm
4) tooth mobility
5) irreversible
What are the periodontal indices
- pocket depths
- plaque levels
- attachment loss (cej to base of sulcus)
- bleeding scores
- radiographic bone loss
What is probing/pocket depth
Distance from gingival margin to base of sulcus.
What is attachment loss
Distance (mm) from cej to base of sulcus
What is periodontal disease
Inflammatory reaction to plaque at the gingival margin. Can be classed as gingivitis or periodontitis (periodontal tissues involvement)
What are local risk factors for oral conditions
Root exposure Misalignment of teeth Crowding Restorative margins partial dentures
Systemic risk factors
Diabetes Poor oral hygiene Immunodeficiency Nutritional deficit Smoking Obesity Stress Osteoporosis
Describe HA crystallite arrangement in a tooth.
Along the sides of the tooth the arrangement is less ordered.
Cuspal areas have greater crystallite alignment and order, the greatest alignment is seen in areas that are likely to contact cusps of opposing arch tooth
Fracture toughness - definition
Ability to resist brittle fracture in the presence of a crack.
In enamel the protein films + crystallite alignment contribute to its fracture toughness
What two types of behaviour does the protein sheath around enamel display
1) Polymer like - deforms under load
2) elastic - returns to initial form and position after load is removed cuz in that deformed position it is thermodynamically unstable.
Effect of restoration on mechanical properties of tooth
Decreased fracture resistance
Risk of crack propagation and fatigue failure occurring at tooth restoration interface due to high stresses from masticatory forces.
Where/how is porcelain used n wats the adv n disadv
Post alternative for comp- inlays n onlays (indirect restoration)
Adv = abrasion resistant + more durable + aesthetic
Disadv = wear of opposing tooth + adjustment and polishing is more diff.
What does anisotropic mean
When a physical property is different in different directions/locations of the tooth.
Remember:
Material = homogenous n isotropic
Enamel n dentine = anisotropic at microscopic level
Where is the stress location for non bonded restorations
At internal walls - tooth restoration interface
Where is the stress location for bonded restorations
At cusp tips like a normal tooth
Where will cracks occur in bonded n non bonded restoration
Bonded - within enamel in contact with opposing tooth
Non bonded - internal line angles and edj
Wats the optimised shape for reduced cusp tips for onlays/inlays
Perpendicular to the opposing load but not perpendicular to long axis of tooth.
Ideal restoration of a cavity:
No sharp edges or corners
Perfect contact between tooth and restoration
Base of cavity larger for retention
Stress is uniform n minimal at internal line angles.
Internal outline features:
90 degrees cavosurface angle
Lateral wall undercuts
Rounded pulpal line angles
0.5 mm into dentine (deciduous tooth restoration)
How wide shod the cavity isthmus be
1/3rd of width of occlusal table
Wat are the indications for SSC - 7
Special needs patient with reduced OH
2 or more carious surfaces
Extensive one surface caries
Developmental problems eg hypoplasia, AI,DI.
Fractured primary molar
Extensive tooth surface loss - erosion, attrition, abrasion
High caries risk patient
2 contraindications to ssc
If primary molar is close to exfoliation with more than half of root resorbed - seen on radiograph
Nickel allergy/sensitivity
Whats the Hall Technique
Method of managing carious molars in which decay is sealed under preformed metal crown (PMC) without any LA, caries removal or tooth prep.
What is primary prevention + examples
Stopping disease starting in the first place by keeping teeth healthy
- fissure sealant
- f toothpaste
- brush twice daily 2mins n dont rinse
- 4 sugar attacks - limit intake n freq
Whats secondary prevention n examples
Detection n Limiting impact of disease at an early stage
Bitewing radiographs
Occlusal caries - restore/SR
Aproximal/smooth surface - if only in enamel then increase fluoride, reduce sugar, increase brushing
Whats tertiary prevention
Restoring the function of the tooth n preventing further development of disease
- all of secondary
- restore decayed tooth
- extract teeth with poor prognosis
What are the stages in periodontal disease progression
Health Initial lesion Early lesion - early G Established lesion - chronic G Advanced lesion - chronic P
What is MMP n give an example n where are they found in periodontitis
Matrix metalloproteinases
Eg collaginase
Found in high numbers in gcf in periodontitis
Explain function of RANKL and OPG in periodontitis
Cytokines plus bacterial factors increase expression of RANKL which then allows osteoclast formation and activity + decreased expression of OPG in osteoblasts resulting in decreased inhibition of osteoclast activity = imbalance in bone remodelling resulting in increased bone resorption
Describe periodontal probing
Holding the probe in gingival sulcus, parallel to tooth surface and keep in contact as you walk it around the circumference of tooth
Whats BPE for
Simple rapid screening for those at risk of periodontal disease.
Disadv of bpe
No distinction between true/false pockets
No detail about recession
Lack of detail within sextant
No detail abt furcation involvement
How much pressure is used when probing
20g
Define horizontal bone loss
When the bone level lost is equal interdentally
Define vertical/angular bone loss
One tooth has lost more bone than the adjacent tooth, hence alveolar crest is more apical to CEJ for one tooth than the other.
State the order or cariogenicity of sucrose, glucose, lactose, fructose
Sucrose> glucose> fructose> lactose
How can we compensate for xerostomia
Chlorhexidine gel - antibacterial
Topical F
Contraindications of fluoride varnish
Ulcerative gingivitis
Stomatitis
Contraindications of fissure sealant
Partially erupted
Caries present
No risk
Unable to isolate (?)
Whats the criteria for a moderate risk caries patient
1-2 lesions per year
Criteria for high risk caries patient
3+ lesions per year
Medically compromised
Social risk factors
Ortho treatment
What is parafunction
Use of a body part eg tongue/teeth in a way that isnt commonly used eg bruxisn
What is diagnosis
Identification of an illness based on signs and examination
Prognosis?
Prediction of most likely outcome of a disease
What enzyme breaks down ester LAs in blood.
Pseudocholinesterase
Name constituents of LA cartridge
LA Vasoconstrictor - adrenaline/felypressin Preservatives - uncommon in recent LAs Isotonic solution Reducing agent- prevents adrenaline from oxidising
Adv of adrenaline as vasoconstrictor
Vasoconstrictor
Reduces and controls blood flow, less bleeding, therefore increased visibility
Less systemic absorption, lower toxicity, can use higher doses
Prolonged duration of action
Disadv of adrenaline in LA
Increases cardiac output - increased HR and Stroke vol- can lead to arrhythmia
Decreases plasma potassium = arrythmia
Heat and light sensitivite - breaks down
Dont giv to unstable angina and uncontrolled arrythmia patients.
Contraindication of felypressin
Pregnancy - can induce labour.
Factors affecting infiltration anaesthesia duration
Use of vasoC
Volume
Concentration
What info is recorded after patient LA
Type of LA procedure Type of LA, voluMe, concentration Vasoc and conc Batch number Patient reaction
Reasons for nerve block use
Cortical bone too thick
Avoiding an area of infection
Wider area of anaesthesia needed
3 landmarks of dental block
Coronoid notch - ant border of ramus
Internal oblique ridge
Pterygomandibular raphe
What will not be anaesthetised by your ID block
Posterior molars gingiva- hence buccal nerve will b needed too potentially
Precautions for reducing risk of complications in LA
Use self aspirating syringe Use lowest effective volume of LA Inject slowly - 1ml over 30s, 2ml over 60s Medical/drug history Past dental experience Allergies Limit use of regional block eg IANB
What is syngenite formed from
Potassium sulphate reacting with water/hemihydrate in gymsum products.
Wat does potassium sulphate do in gypsum
Decreases setting time
Faster crystallisation
Decreases expansion
2% reduces reaction from 10mins to mins
Function of unreacted dihydrate in gypsum
Accelerator - additional nucleation sites for crystal growth = decreased setting time n working
Wats the difference in effect of NACL less than 20% and more than 20%.
<20 = accelerator. Provides additional crystallisation sites = decreases setting time. >20 = retarder, increases setting time by depositing crystals which prevent growth.
Describe setting reaction of gypsum hemihydrate (alpha/beta)
Add water to hemi, dissolves (has low solubility) and reacts to form dihydrate plus releases heat (exothermic). Dihydrate has even lower solubility and is unstable therefore precipitates out to form stable crystals. Unchanged dihydrate in the original powder acts as crystallisation nuclei for growth. When the crystals interlock they expand and leads to setting of stone/plaster.
What is the effect of providing crystallisation nuclei for dihydrate crystal growth on the setting time
Faster/shorter setting time
Effect of spatulation on expansion and setting time
Provides more crystallisation nuclei = more crystal growth and interlocking = faster setting time but also more expansion
Agar and alginate setting reactions - which one is chemical and which one is physical
Alginate = chemical Agar = physical hence reversible
State components of alginate powder
Sodium/potassium alginate
Diataceous earth = filler (strength) - 70% of powder
Calcium sulphate cross linking Agent
Sodium phosphate or sodium carbonate as retarder
Ph controllers: sodium silicofluoride, magnesium oxide, sodium fluorotitinate.
Adv of alginate
Cheap
Reliable
Good setting behaviour - once setting reaction begins it is completely quickly so minimising impression taking time
Sodium phosphate inhibits set initially so enough time to mix n seat tray in mouth
Disadv of alginate
Dimensional stability poor
Water loss (air) = shrinkage
Has to be covered in damp cloth n sealed in a air tight bag - maintain relative humidity
Immersion in water = swells at first, then shrinks as water soluble salts are eluted
Disinfection for prolonged period of time causes dimensional changes
Poor tear strength
Doesnt adhere well to tray hence need adhesive/mechanical locking features in tray
Components of agar
Agar Borates - strengthens gel Potassium sulphate - accelerator Thixotropic material - filler Water
Disadv of agar
Cast up immediately cuz loses water by syneresis (swells). Also absorbs water (imbibition) so swells.
Poor tear strength
Viscoelastic
Adv of agar
Once set up easy to use
Cheap
Good surface detail due to setting property
Records finer details
What does the liquid component of gic contain
Phosphoric acid 50%
Tartaric acid 10%
Function of tartaric acid in gic
Increases working time by forming complexes with calcium and aluminium ions and only releases them once the acid is partially neutralised, leading to a rapid set.
Which ions are released in dissolution of ion leachable glass in gic
Ca
Al
Na
F
Wat are the three stages of gic setting reaction
Dissolution
Gelation
Maturation
Effect of water on gic
Early water exposure causes dissolution of the reactive ions
Dehydration causes loss of water needed for setting reaction
Protect gic, polish after 24hours
Describe adhesion n the chemical bonds between GIC and tooth surface
Chelation between calcium in hydroxapatite and COO- group in PAA.
Hydrogen bond between collagen amino groups and COOH
Ion exchange occurs resulting in an ion rich interfacial layer
Effect of titanium dioxide in cermet
Added for colour
State components of Compomer
Acidic monomer - functional groups from composite and gic Hydrophilic monomer CMQ- photoinitiator Filler - strontium glass - source of F Ion leachable glass Stabilisers increase shelf life
Benefits of bonding agent
Reduced marginal leakage
Reduced pulp sensitivity
Reinforces weak tooth structure
Conservation of tooth since you dont need mechanical retention
Aesthetics
Required to retain the restorative in the cavity cuz tooth is hydrophilic and restoration is hydrophobic
Effects of acid etch technique
Increases surface area and roughness for bonding
Opens inner prismatic area for miromechanical bonding via resin tags
Increases surface energy as removes enamel pellicle and surface enamel for improved wetting
Wats the smear layer
When dentine is cut, it causes an outward fluid shift, resulting in a layer of collagen and broken HAP crystals, and debris and may contain bacteria from caries.
May form smear plugs within tubules
True or false: dentine tubules contain tissue fluid
True :)
What type of reaction removes the smear layer/ enamel pellicle
Acid/base between the acid n tooth
Wat is the depth of demin in enamel n dentine with acid etch
30micrometres for E
4 micrometres for D
What is the coupling agent/primer in dentine composed of
HEMA - bi functional moleule, dissolved in a solvent ethanol/acetone which displace water
Why is microfilled resin added on top of unfilled resin which has forned resin tags in enamel
Cuz, if we are bonding to enamel, it means the lesion must be very superficial eg abrasion lesions, hence youll need microfilled composites on top since they have good surface finish and dont need to have mechanical strength etc
What are the layers in the hybrid zone
Dentine - coupling agent/primer - bond - composite filling
How far does hybrid layer go into dentine tubules
100 micrometee
True/false: hybrid layer involves strong micromechanical bonds - tag formation
True
Wat are the two types of bonding in dentine
Micromechanical
Entanglement
What is the effect of tryglycerides in base paste of polyether/impregum
Increases intrinsic viscosity
When pressure applied the material viscosity decreases, when pressure removed viscosity increases again
What is modification that occured to produce impregum penta soft
Reduced filler and ratio of high n low viscosity plasticiser
= easier removal, improved taste, better handling
What is the effect of unreacted Si-H bonds in addition silicones
They react with water in plaster to release H2 = porosity
Importance of pain
Warns of impending danage/actual damage
Escape motivation n preventive action - motivates ppl to make a change
Alarms others abt the threat n danger
Care and empathy induced for others
Wats allodynia
pain due to a stimulus that doesnt normally cause pain
Hyperalgesia
Increased response to a stimulus whivh normally causes pain
Dysaesthesia
Unpleasant sensation - evoked/spontaneous
Paraesthesia
Abnormal sensation - not unpleasant though- spont/evoked
Analgesia
Absence of pain in response to stimulus which would’ve normally caused pain
Hypoalgesia
Reduced pain in response to a normally painful stimulus
Neuralgia
Pain in distrib of nerves
Neuropathic pain
Pain caused by primary lesion/dysfunction in NS
Wats pain
Unpleasant sensory n emotional experience due to actual or potential tissue damage
Which teeth do we normally fissure seal in high risk patients
Permanent molars
Contraindications of fluoride
Stomatitis
Ulcerative gingivitis
Allergy
3 main methods of caries prevention
Diet analysis
Appropriate flourides
Fissure sealant
OH regimen - brushing etc
Wats the criteria for high risk patients
New carious lesiobs - 3/4 a yr, illness, physically compromised,
Salivary flow
Plaque control
High sugar diet
Social factors?
Wat is the name of dust free alginate
Triethanolamine alginate
Why does comp shrink during setting
Cuz the dimethacrylstes have two double bonds which open up to form the polymers, leading to shrinkage
Filler advantages in comp
Reduces polym shrinkage n thermal expansion Increased comp strength Radiopacity Aesthetics Increased youngs modulus
Adv of hybrid comp
Better surface finish than conventional but less than microfilled.
Better wear resistance
Higher packing density whilst having smaller particle size
Disadv of hybrid comp
Surface roughness over time- probs why u get discolouration cuz debris n stains can attach
What are the two functional groups on the silane coupling agent
-OCH3 (methoxy group) bonds to OH on filler (hydrophillic) = condensation reaction.
Methacrylate group C double bond to C bonds to methacrylate in organic resin (hydrophobic)
Wat functional group swap occurs wen silane coupling agent is acid treated
Methoxy och3 group to OH
Hence water released in condensation reaction with filler
Wats degree of conversion
% ofmonomer converted to polymer
Double bonds to single
Wats dresslers syndrome
A type of pericarditis due to an immune system respobse after damage to heart tissue/pericardium
Wat is the benefit of resistance form n retention form
Prevent displacement of restoration and frscture of R plus tooth structure under occlusal forces
Factors contributing to resistance form
Unsupported enamel (not supported by underlying dentine hence fractures)
Cavity wall angles - parallel to long axis of tooth
Internal line angles need to be rounded
Depth of pulpal n axial wall sufficient ti support restoration
Type of material being used - isit brittle
Wats the cavosurface angle
Angle between wall of cavity and surface of tooth
Factors affecting amalgam resistance to fracture
Thickness (>2mm)
90 degree cavosurface angle
Box like preparation form - uniform amalgam thickness
Rounded axiopulpal line angles in class2 prep
Retention form
Resistance form
Retention = retention in cavity therefore prevents dislodgement due to forces in the long axis of tooth Resistance = resisting fracture (tooth n restoration)
A restoration has failed if…
Secondary caries in dentine Residual caries Pulpal nevrosis Appearance unacceptable to patient - marginal staining, discolouration, contracts to normal darknening of tooth, desire for white fillings Microleakage causing sensitivity n pain Fracture of R or T Dislodgement of restoration
Symptoms of secondary caries
Usually none or might be similar to pulpitis
Discolouration
Signs of secondary/recirrent caries
Loss of vitality on sensibility test - hot/cold/electrical
May or may not see periradicular change (space in between roots i think
4 factors affecting failure of restoration
Patient - diet,plaque,saliva/xerostomia,poor oral hygiene
Operator- didnt promote prevention, check occlusion, inappropriate restoration/liner/ base, left infected dentine, pulp exposure, failure to seal all dentinal tubules, heat/pressure
Material factors - fracture/corossion/wear/staining
3 types of auxiliary retention
Vertical grooves
Angled coves (like a curved slot)
Horizontal slots
Make using rosehead bur/330
5 ways of improving comp restoration
Ensure tooth is clean - pumice
Acid etch only area u need to n wash thoroughly
Dry thoroughly
Rub in the primer n bond to improve penetration
Small increments
Centre of light beam on area needing to be cured
Wats tribology
Study of wear
3 reasons for intervening in toothwear cases
Loss of function
Altered appearance
Sensitivity/pain
6 types of non carious tooth surface loss
Attrition Abrasion Abfraction Erosion Trauma Iatrogenic
Define abrasion
Wear of tooth due to friction if exogenous material forced over tooth surface
Attrition
Wear caused by endogenous material eg microfine enamel prisms caught between two opposing tooth surfaces
Tooth to tooth
Tooth to dental material
Parafunction makes it worse like grinding
Erosion
Acid dissolution
Wat does erosion lesions look like
Cusps might be cupped in enamel edge/cusp tips
Smooth n round polished lesions
Wats abfraction
Forces that are transmitted from cusp tip to thin cervical enamel causing it to fracture n wear away
Wat are iatrogenic causing of tooth wear
Bur effects on a tooth
Or polishing tooth
Wat would you ask your patient in medical history if u see erosion
Heart burn
GIT disease - hiatus hernia, peptic ulcer
Eating disorders - bulimea
Pregnancy - morning sickness
Diet:
Carbonated drinks
Bare fruit or juice
Herbal/fruit tea
Wat advice would you give to patient after they vomit/regurgitate
Dont brush you teeth
Use fluorie mouth rinse
Since acid plus abrasive in tooth pase = more tooth surface loss
Who is most likelt to have attrition
Ppl suffering from high stress
- bruxism/clenching
- pain over masseter n temporalis muscles of mastication
Appearance of attrition
Loss of cusp tips in molars n underlying dentine may be exposed
Incisal upper n lower edges thin n may chip
Wats perimolysis
A rim of enamel left on tooth after erosiob
Appearance of abrasion lesion
Cervical margin where enamel is thin n less regular prisms
Wats pica
Compulsive eating of non foods
4 ways of monitoring wearc
Study casts - taken anually to see speed of wear
Wear indices - scoring level of wear
Photographs
Direct measurement - williams probe to measure height of teeth n record in notes
Describe Cognitive Behavioural Therapy
Targets psycological aspect of pain
relaxation techniques
Most effective for deppression n highly stressed ppl
Wat method do u use to diagnose approximal caries in posterior teeth
Fibre optic transillumination
How does transillumination help us identify carious lesion
Caries lesions have lower index of transmitted light therefore appear as a dark shadow which follows the outline of decay in dentine
Wat colour is active uncavitated lesion
White with maybe matt surface
Colour of inactive caries lesion
Brown, shiny/glossy surface
Can you see uncavitated lesions on a radiograph
No
Why does the tooth surfafe need to be clean n dry
To detect micro cavities
Wats the significance of age and pulpal repair mechanism
Ageing leads to compromised reparative dentinogenesis - depleted progenitor cell recruitment
Wat does a positive tooth sensibility test mean
Pulp is vital
What can u use to control bleeding of pulp during direct pulp capping
Saline water or sodium hypochlorite
Wat is the condensation pressire for amalgam fillings
3-5kg
Wat is simple amalgam
Without pins/auxiliary retention
Wat is complex amalgam
Augmented by pins/auxiliary retention.
Wats the reason for making smooth flat cavity floor and rounded internal line angles
Provides better surface to condense amalgam into and minimuses internal stress points
Whats galvanic shock
Aluminium in oral cavity contacts amalgam causing small electric currents felt as shocks
Does calculus cause periodontal disease
No, it Acts as a surface for plaque to bind to
