1.3, 4.1, 6.1 Healing & repair, haemodynamic disorders

1.3 Cell biology
Molecular techniques to study DNA/RNA
1. Polymerase chain reaction (PCR)
2. Gel electrophoresis
3. In-situ hybridisation (ISH)
Molecular techniques to study protein
1. Enzyme-linked immunosorbent assay (ELISA)
2. Western blotting
3. Immunohistochemistry (IHC)
4. Immunofluorescence

4.1 Healing & Repair
3 types of cell regenerative capacity
1. Labile – Divide throughout life, constantly replaced e.g. epithelial cells
2. Stable – Divide when necessary e.g. Hepatocytes
3. Permanent – Divide only during fetal life e.g. Nerve cells
where are stem cells
1. Epidermis – adjacent to basement membrane in basal layer
2. Intestinal mucosa – bottom of crypts
1. The healing/regeneration process
1. Cells proliferate & spread out as a thin sheet until wound covered
2. Stop proliferating when they meet (contact inhibition)
3. Epidermis then built up from base
4. Covered by scab – layer of fibrin
The organisation/repair process
1. Granulation tissue forms (composed of capillary loops & myofibroblasts)
2. Dead tissue removed by neutrophil polymorphs and macrophages
3. Granulation tissue contraction (and accumulates collagen = scar forms)

1. Skin healing
1st intention – Incisions, close approximation of edges = fast healing
1. Edges joined by fibrin (scab_
2. Neovascularisation
3. Fibroblasts secrete collagen
2nd intention – tissue loss, not close approximation
1. Phagocytosis of debris
2. Granulation tissue fills defects
3. Epithelial regeneration to cover surface
Cytokines involved in healing/repair
1. Epidermal growth factor (EGF) – Epithelial regeneration
2. Vascular Endothelial growth factor (VEGF) – angiogenesis
3. Transforming growth factor beta (TGF-beta) – Control myofibroblasts and collagen formation
2. Gastric mucosal ulcers
1. Bleeding & fibrin covers surface
2. Phagocytosis of debris
3. Granulation tissue at base
4. Epithelial regeneration from ulcer edges
3. Bone fracture
1. haematoma – From ruptured vessels, debris removed
2. Callus – Woven bone (irregular)
3. Lamellar bone replaces woven bone
Factors affecting bone healing
1. Mobility – excess callus
2. Misalignment – Risk of degeneration
3. Interposed soft tissue – Risk of non-union
4. Liver
3 sources of cells for repair
1. Hepatocytes
2. Liver progenitor cells
3. Bone-marrow derived stem cells
5. Muscle
1. Cardiac & smooth = permanent cells (scar forms)
2. Vascular smooth muscle can form new vessels
-Voluntary muscle has limited regeneration by satellite cells
6. nerve
IAN damage
1. Mandible fractures
2. Lower 8’s
3. Rejection of neoplasms
3 types of peripheral nerve damage
1. Neurapraxia – Contusion, no loss of axon/endoneurium, recovery in days-weeks
2. Axonotmesis – lsos of axon contiuity, no endoneurium loss, 2-6 months, nerve dysfunction
3. Neurotmesis – Complete loss of continuity, poor prognosis
Nerve healing
1. Segmental demyelination – Myelin sheath dissolves in segments
2. Wallerian degeneration – Axons, myelin sheath, distal degen
3. Regeneration – New fibres grow down schwann cell tube
7. Alveolar socket
0 days – Clot retraction + clot stabilisation, fibrin cross linking
2 days – Clot lysis + Emigration of inflammatory cells
4 days – Granulation tissue grows into clot, macrophages demolish clot, gingival hyperplasia to cover clot
8 – Socket filled w granulation tissue + Epithelial migration complete
18 days – Woven bone formation around socket periphery
6 weeks – Woven bone beginning to remodel -> lamellar
8. Factors affecting wound healing
1. Age – Delayed healing e.g. angiogenesis, neutrophil, macrophage
2. Diabetes – Impaired wound healing, foot ulcers
3. Immunosuppression – increased susceptibility to infection
4. Alcoholism & smoking – decreased phagocytosis & neutrophil recruitment
5. Cushing’s syndrome/steroid therapy – interferes with granulation tissue formation

6.1 Haemodynamic disorders
1. Vasovagal syncope sequence
1. Stress induced increase in catecholamines = decreased peripheral vascular resistance, tachycardia, sweating. Generalised warmth, nausea, palpitations
2. When blood pools in periphery = drop in arterial BP, cerebral blood flow, dizzy & weak
3. Compensatory mechanisms to lower BP = bradycardia, if too low = syncope
Management
1. Stop treatment
2. Supine
3. Check breathing
(If not – life support, 000)
4. Crush ammonia under nose, oxygen, monitor vitals, have pt escorted home, future anxiety control
2. Edema – Excess fluid in intercellular compartment of tissue
5 causes of edema
1. Increased hydrostatic pressure
2. Increased vascular permeability
3. Lymphathic obstruction
4. Sodium retention
5. Physiological
5 types of oedema pathogenesis
1. Normal = hydrostatic pressure forces water out arterial end
2. Inflammatory edema = Gaps between endothelial cells
3. Venous edema = increased venous pressure
4. Lymphatic edema – lymphatic obstruction = no water drainage
5. Hypoalbuminaemic edema – Low plasma albumin
3. Atherosclerotic lesions
1. Starts with fatty streaks
2. Mature plaques have central lipid core + fibrous cap (macrophages, lymphocytes, mast cells)
How do they form
1. Injury to endothelial cells
2. Inflammatory cells & lipids migrate to intima & form plaques
3. As it matures, macrophages die, spilling liquids into core
4 clinical manifestations of atherosclerosis
1. Narrowing (stenosis)
2. Atherothrombotic occlusion
3. Embolism
4. Ruptured abdominal atherosclerotic aneurysm
4. Calcifications
1. Dystrophic calcifications – local precipitations of calcium
e.g. Atheromatous plaques, fat necrosis
2. Psommoma bodies – Lamellated calcified bodies
3. Metastatic calcification – widespread hypercalcaemia
5. Thrombus
1. Virchow’s triad
1. Change in intima
2. Change in blood flow
3. Change in blood constituents
Venous thrombosis
1. Mostly in leg, because blood going to heart is reliant on calf contraction
2. Immobile elderly pts
3. Tender, swollen, red
Arterial thrombosis formation & effects
1. Athermoatous plaque deposit
2. Loss of endothelial cells
3. Platelet adhesion
4. Occlusion by multilayered thrombus
Cold, pale, painful
Sequelae of thrombi
1. Resolve
2. Organised into a scar
3. Recanalised -ingrowth of new vessels
4. Embolism – Thrombus breaks off into circulation
6. Infarcts
Red infarcts – occurs in previously congested tissues, venous occlusions, flow not re-established after previous infarcts
White infarcts – arterial occlusion in solid organs e.g. heart, kidney
7. Embolism
-Embolus is a mass able to lodge in vessel & block lumen
-95% in leg veins, some pelvic veins, some intracranial venous sinuses
8. Vascular insufficiency
6 types of vascular insufficiency
1. Atheroma – Plaques narrow lumen
2. Spasm – Smooth muscle contraction
3. External compression
4. Vasculitis
5. Steal – diversion of blood
6. Hyperviscosity
9. Shock
3 types of shock
1. Cardiogenic – low cardiac output from heart unable to pump sufficient blood
2. Hypovolemic- low blood volume e.g. wound
3. Septic – Microbial

9.1, 9.2, 10. Genetic disorders, SARS-CoV-2, Seminars.

9.1 Genetics & Developmental disorders
1. Definitions
1. Multiplicative – Increase in cell number by mitosis
2. Auxetic – Increase in cell size
3. Accretionary – Increase in intercellular tissue components
4. Differentiation – Cell develops functions different to parent cell
5. Morphogenesis – Development of organ shape & function
6. Induction – Control of differentiation of one type of cell by another
2. Establishment of phenotype
1. Gene expression controlled by ‘control genes’
2. Control genes encode protein
3. Control genes regulated by master control genes
4. Homeobox genes are proteins influencing morphogenesis
5. Epigenetic alteration in DNA structure, DNA methylation, Histone proteins
3. Factors affecting maintenance of a differentiated state
Differentiated state affected by:
1. Local alterations in positional information by control gene products
2. Migration ofcells mediated by paracrine/endocrine factors
Maintenance of differentated state by:
1. Interacting with extracellular environment
2. Epigenetic modification
4. Anomalies of organogenesis
1. Agenesis – organ failed to develop
2. Aplasia – Incomplete development
3. Atresia – Lumen failed to develop
4. Hypoplasia – Failure of organ size development
5. Ecopia – Small mature tissue area present in another tissue area
6. Choristoma – A mass of one or more tissues at an iappropriate site
7. Hamartoma – Mass of tissue derived from all 3 germ layers found at inappropriate site
5. Cleft palate & lip
1. Failure of 1st branchial arches to complete fusion
2. Normally in week 5, maxillary processes fuse w frontonasal process to form upper lip
3. Normally in week 9, maxillary processes form palatal processes which fuse w nasal septum
4. Failed fusion of palatal shelves = Small palatal process & failed midline epithelium seam formation
Associated defects – 1. Absent/malformed teeth, 2. Spinal/mental congenital defects
Dental aspects – Malocclusion
2. Hypodontia
3. Hypoplasia
4. Supernumeraries
5. High caries & gingivitis
Management – Prevent movement of 2 maxillary halves + feeding, speech & cosmetic management
5. Genetic disorders
-Single gene defects
1. By mutations – Point mutation, mutationsin coding sequence, frameshift mutation, trinucleotide repeat mutation
2. Mendelian disorders – Enzyme defects, Defects in receptors/cell transport (cystic fibrosis), Non-enzyme protein defects
-Chromosomal defects
1. Trisomy 21 (Down’s syndrome)
General signs – Flattened facial profile, Prominent epicanthic folds, short hands w transvers palmar crease
Dental implications – Class III malocclusions, Hypoplastic midface, Rapid + early onset periodontal disease
2. Trisomy 18, Trisomy 13, Klinefelter’s syndrome
-Complex multigenic disorders
6. Congenital anomalies
1. Derformation – Extrinsic physical force
2. Malformation – Intrinsic disturbance
3. Disruption – Extrinsic disturbance resulting in destruction of normally formed tissue
4. Syndrome – Combination of anomalies not explained by 1 change
5. Sequence – Combination of anomalies caused by 1 change
e.g. Fetal alcohol syndrome, Teratogen exposure
7. Genetic testing indications
Prenatal: mother old, ultrasound fetal anomaly, Family history
Older: Neurodegenerative disease, inherited cancer, disorder manifesting in older age

9.2 SARS-COV-2
1. Pathogenesis
1. SARS-CoV-2 S-protein binds to ACE2 receptor
2. TMPRSS2 on host cell cleaves ACE2 receptor which allows virus to bind to cell membrane
3. Virus binds, enters cell via endocytosis
4. Virus releases RNA & hijacks cell machinery to replicate
Early stage
1. Bronchial epithelial cells, pneumocytes, capillary endothelial cells infected
2. Inflamatory signalling molcules released (TNF-alpha, IL1, IL6)
3. Recruitment of macrophages, T-lymphocytes, neutrophils
Late stage
1. Continued inflammatory response = Alveolar interstitital thickening, vascular permeability
3 Features of SARS-CoV-2 pathogenesis
1. Severe endothelial injury
2. Widespread vascular thrombosis w microangiopathy
3. New vessel growth by existing vessels splitting into 2
2. Why do only 20% of hosts develop severe symptoms
1. Exacerbated inflammatory response from transition innate -> adaptive immunity
2. Autoantibodies for type I interferons
3. Comorbidities (diabetes, cardio)
4. Maturity of ACE2 receptors (age)
3. Histiologic features of fatal covid infection
1. Diffuse alveolar damage
2. Mononuclear inflammatory by lymphocytes
3. Exudative & proliferative phase of alveolar damage
4. Atypical pneumocytes w/ large/multiple nuclei
4. Fatal outcomes + Oral manifestations
1. Pulmonary hypertension
2. Activation of coagulation facors
3. Microthrombi formation
4. Thrombotic arterial complications (ischaemic stroke)
5. Viral sepsis
Oral manifestations
1. Mucosal ulcerations
2. Vesicles
3. Petechiae
4. Erythematous plaques

Path seminars
1. COPD + Asthma
Aetiology
– COPD – Pollution/cigarette smoke + host factors
-Asthma – Triggers (exercise, inhaled) + host factors
Pathogenesis
– COPD – Direct/indirect effects of pollution/smoke on respiratory tract
-Asthma – Tpe I hypersensitivity reaction (allergen reacts w IgE bound to mast cells)
Clinical features
-COPD – Chronic cough, dyspnea, sputum production
-Asthma – Wheeze, cough, chest tightening
2. Diabetes mellitus
Aetiology
-Type I – Genetic + Environmental (social mixing, viral infection)
-Type II – Age, obesity, diet, lack of exercise
pathogenesis
-Type I – Autoimmune destruction of beta cells in pancreas (which secrete insulin)
-Type II – Failed feedback loops between insulin action & secretion
Clinical features
-Fatigue, neuropathy, delayed wound healing
3. Atherosclerosis
Aetiology
-Elevated LDLs, diabetes, obesity
Pathogenesis
-1. Fatty streak formation, 2. Atheroma formation, 3. Atheroma disruption
Clinical features
-Depends on artery affected
(coronary artery) arrhythmias, transient ischaemic symptoms
(Carotid artery) dizziness, stroke
4. Hypertension
Aetiology
-Genetic, environmental, behavioural
-Secondary hypertension caused by underlying systemic condition
Pathogenesis
-Sympathetic nervous system
-Renin-angiotensin-aldosterone actiation
-Endothelial dysfunction
Clinical presentaiton
-High BP, but usually asymptomatic
(If severe) Vision problems, headaches, shortness of breath
5. Stroke
Aetiology
-Hypertension, old age, family history
Pathogenesis
-Infarction -> ischaemic stroke
(Lumen close from atheroscloersis, thrombosis, embolus)
-or Haemorrhagic pathogensis
(From hypertension, aneurysms)
Clinical presentation
-Facial drooping, arm weakness, speech difficulty

7.1, 7.2, 8.1 Neoplasia I, II, General pathology of infectious disease

7.1 Neoplasia I
1. Tumours, neoplasms, components
1. Tumour – Abnormal swelling
2. Neoplasm – Lesion resulting from abnormal growth of cells even when stimulus absent
Components of tumours & neoplasms – neoplastic cells + Stroma (CT framework that provides support & nutrition to neoplastic cells)
2. Characteristics – Benign & malignant
1. Slow growth, rapid growth
2. Resembles normal tissue, Poor resemblance
3. Non-invasive, invasive
4. Never metastasises, Frequent metastases
5. Rare ulceration/necrosis, Frequent ulceration/necrosis
3. Clinical effects of benign & malignant
1. Pressure on adjacent tissues, pressure on adjacent tissues
2. Obstruction of flow, obstruction of flow
3. Production of hormone, production of hormone
4. Anxiety, anxiety & pain
5. Transformation into malignancy – Cancer cachexia (weight loss), Metastases
4. Names of Benign & malignant
Benign – Papilloma, Adenoma + Chondroma, Fibroma, Cystadenoma
Malignant – Carcinoma (epithelium), sarcoma (mesenchyme), Adenocarcinoma (gland/duct) + Melanoma, Lymphoma, Mesothelioma, Seminoma
5. Differentiation, Anaplasia Dysplasia
1. Differentiation – Extent to which neoplasms result parent cells
2. Anaplasia – Lack of differentiation -> sign of malignancy
3. Dysplasia – Loss of cell uniformity & architecture (“pre-malignancy)
6. Dysplasia in oral epithelium
1. Loss of uniformity – Variation in cell size/shape | Abnormal mitotic figures
2. Loss of architecture – Increased number of mitotic figures | Superficial mitotic figures | Loss of epithelial cell adhesion
7. Classes of carcinogens
1. Chemicals – Tobacco smoke, aromatic hydrocarbons
2. Viruses – HPV, epstein barr, Hep B&C
3. Radiation
4. Exogenous hormones
5. Microbes
8. Host factors in carcinogenesis
1. Race
2. Diet
3. Constitutional factors (sex/age/race)
4. Premalignant lesions
5. Transplacental exposure
9. 6 Major pathogens in odontogenic infections
1. Strep milleri
2. Peptostreptococcus
3. Other anaerobic streptococci
4. Prevotella species
5. Porphyromonas species
6. Fusobacterium species

7.2 Neoplasia II
1. Hallmarks of cancer
1. Self-sufficiency in growth signals – Gain in function of CDK-4& cylin-D (more cell proliferation) + Loss of function in CDKI (less inhibition of cell proliferation)
2. Insensitivity to growth-inhibiting signals – Mutation in one of the key cell regulators (p16, RB, CDK4, cyclin D). p53 also often mutated
3. Altered cell metabolism – High glucose uptake & fermentation
4. Evasion of cell death – Cancer cells overexpress anti-apoptotic genes (BCL-2, BCL-XL)
5. Unlimited replicative potential – Cancer cells reactivate telomerase
6. Sustained angiogenesis
7. Invasion & metastases
8. Evasion of immune surveillance
2. Enabling characteristics of malignancy
1. Genomic instability + 2. Tumour-promoting inflammation
3. Mechanisms of viral carcinogenesis
1. Oncogenic DNA virus
2. Acute-transforming RNA retrovirus
3. Slow-transforming oncogene
4. Genetic abnormalities in tumours
Tumour suppressor genes
1. 2-hit hypothesis – 1. Inheritence of defective allele of tumour-suppressor gene + 2. Acquired mutation loss of function of normal allele
2. Caretaker genes – repair DNA damage, Gatekeeper genes – Promote death of cells with damaged DNA (e.g. p53, RB)
-Oncogenes – genes that drive the neoplastic behaviour of cells
1. 5 groups of oncogenes
1. Growth factors
2. Growth factor receptors
3. Signalling mediator with tyrosine kinase activity
4. Signalling mediator with nucleotide binding activity
5. Nuclear binding transcription
Detection of oncogene expression
1. Presence of more oncoprotein
2. Increased mRNA transcripts of oncogene
3. Increased copies of oncogene in genome
Oncogenes activated by
1. Mutation
2. Overproduction of oncoprotein
-Epigenetic contribution to tumours
1. Gene silencing
2. Gene up/downregulation from histone modification
3. Interference with gene transcription by microRNA
4. Copy number changes

8.1 General pathology of infectious disease
0. Mechanisms of microbial pathogenesis
1. Enter/contact host cell = death of infected cell
2. Toxins = Kill cells or produce enzymes that degrade components
3. Induce host immune response = Further tissue damage
1. Prions
-Abnormal form of host protein
-Disease occurs when PrP undergoes conformational change that confers resistance to proteases
e.g. Kuru, Creutzfeld-Jakob, BSE
2. Viruses
-Can cause transient illness – influence
-Can cause chronic persistent illness – Hep B
-Can cause neoplastic transformation e.g. HPV
Determinants of viral effects/tropism influenced by
1. Host receptors for viruses
2. Specificity of transcription factors
3. Physical characteristics of tissues
Mechanisms of viral injury
1. Direct cytopathic effects
2. Anti-viral immune response
3. Transformation of infected cells
3. Bacteria
Mechanisms of bacterial injury
1. Adherence – Adhesins help bacteria adhere to cell e.g. Pili on N. gonorrhoea
2. Invasion
3. Toxin production (Endotoxin – An LPS that is a component of the outer bacterial membrane
(Exotoxin – secreted product that causes damage e.g. Enzymes, A-B toxins, Secreted proteins)
Bacteria can also take forms that increase virulence
1. Bacteriophage/plasmids
2. Biofilm
3. Quorum sensing
4. Fungi
-Superficial/deep infections
-Opportunistic/endemic species
5. Protozoa
-Single celled eukaryotes
1. Entamoeba histiolytica in contaminated food/water
2. Bloodborne protozoa by insects e.g. Leishmania
3. Uncooked meat w/ cysts e.g. Toxoplasma gondii
6. Helminths
1. Parasitic worms
1. Round worms
2. Tapeworms
3. Fluke
7. Ectoparasites
-Insects e.g. Fleas
-Arachnids e.g. ticks
8. Routes of microbial entry
1. Skin break (HIV needle stick
2. Inhalation – Influenza virus
3. Ingestion – Salmonella
4. Sexual transmission – HPV
9. Transmission of microbes
1. Horizontal transmission (between unconnected people)
Skin, Oral secretions, Respiratory secretions, blood, urine
2. Vertical transmission (between mother & baby via breastfeeding or pre childbirth)
10. Evasion of microbes
1. Antigenic variation
2. Modification of surface proteins
3. Overcoming antibodies & complement
4. Resist phagocytosis
5. Decreased T-cell recognition
11. Harmful effects of host immune response
1. Granulomatous inflammation
2. T-cell mediated inflammation
3. Innate immune inflammation
4. Humoral immunity
5. Chronic inflammatory disease
6. Cancer
12. Inflammatory responses to infection
1. Suppuration
2. Mononuclear/granulomatous
3. Cytopathic
4. Necrosis
5. Chronic inflammation/scarring

2, 3.1, 3.2. Cell adaptations, Acute inflammation, chronic inflammation

2. Cell adaptations
1. Cell adaptations
1. Hypertrophy – Increase in cell size (Muscle in athletes, prostate)
2. Hyperplasia – Increase in cell number (Bone marrow in high altitudes, psoriasis)
3. Atrophy – Decrease in cell size/number (post-menstrual uterus, immobile limb/no blood supply)
4. Metaplasia – Transformation one mature cell type to another (Smokers trachea – Pseudostratified columnar -> stratified squamous, barrett’s oesophagus – reflux squamous -> columnar)
2. Causes & targets of cell injury
Causes 1. Chemical, 2. Biological, 3. Glucose/oxygen deprivation
Targets 1. Cell/organelle membrane, 2. Metabolic processes, 3. DNA/proteins
3. Mechanisms of cell injury
1. Ischemia – Reduced blood flow
2. Hypoxia – Reduced oxygen supply
3. ROS
4. Ionising radiation
4. Reversible injury
-Hydropic degeneration – swelling, more eosinophilic
-Fatty change – presence of triglyceride-containing vacuoles
5. Autophagy – Digestion of cell’s own components as a survival mechanism e.g. starvation
6. Apoptosis vs necrosis
1. Cell shrinkage, cell swelling
2. Plasma membrane intact, plasma membrane disrupted
3. Cell contents intact, cell contents digested, may spill out
4. No adjacent inflammation, frequent adjacent inflammation
5. Often physiological, sometimes pathologic vs invariably pathologic
Apoptosis causes
1. Physiologic – Embryogenesis, turnover of highly proliferative cells, left over leukocytes after immune response
2. Pathologic – UV damage, infections
Apoptosis mechanisms
1. Intrinsic (mitochondrial)
-Pro-apoptotic genes (BAK/BAX)
-mitochondrial cell membrane permeable
-Cytochrome c leaks into cytoplasm
-Caspase activation
-Apoptotic enzyme activation
2. Extrinsic (Death receptor)
-When T-cells recognise the death receptor (Fas/TNF)
-Caspase activation
Macroscopic patterns of necrosis
1. Coagulative
-In most solid organs
-Tissue is initially preserved
-Characteristic of infarction
2. Liquefactive
-Brain infection & infarction
-Site replaced by cyst
3. Caseous necrosis
-Characteristic of tuberculosis infection
4. Fat necrosis
-Released fat & calcium results in soapy white chalks

3.1 Acute inflammation
1. 5 signs of inflammation
1. Dolor (pain)
2. Calor (Heat)
3. Rubor (redness)
4. Tumor (swelling)
5. Loss of function
2. 5 causes of acute inflammation
1. Microbes
2. Hypersensitivity
3. Physical agents
4. Chemical
5. Tissue necrosis
3. Acute inflammation process
1. Change in vessel calibre – Arteriolar walls form pre-capillary sphincters + Vasodilation
2. Increased vascular permeability – Capillary hydrostatic pressure increase + Escape of plasma proteins into extravascular space
3. Formation of cellular exudate
a. Margination of neutrophils (flow closer to vessel periphery)
b. Adhesion of neutrophils to endothelium
c. Emigration (neutrophils migrate between gaps in endothelial cells)
d. Migrate into adventitia
4. Chemotaxis of neutrophils to site of injury

Role of macrophages in acute – Secrete il-1, TNF alpha
Role of lymphatics – Drain edema, antigens carried to nodes for recognition
Role of neutrophils – Phagocytosis & intracellular killing
4. Chemical mediators in acute inflammation
1. Histamine
2. Chemokines
3. Prostaglandins
4. Leukotriens
3 Plasma derived mediators
1. Proteases
2. Kinins
3. Complements
5. Effects of acute inflammation
Good
1. Delivery of nutrients & oxygen
2. Fibrin formation
3. Stimulation of immune response
4. Toxin dilution
5. Transport of drugs
Bad
1. Digestioin of normal tissues
2. Swelling e.g. airway
3. Inappropriate immune response e.g type 1
6. Appearance of acute inflammation
-Serous, fibrinous, suppurative
7. Acute inflammation sequelae
1. Resolution (Phagocytosis of bacteria, fibrinolysis, phagocytosis of debris, disappearance of vascular dilation)
2. Suppuration
3. Repair & organisation
4. Fibrosis
5. Chronic inflammation
Factors leading to resolution
1. Minimal cell death & tissue damage
2. Organ/tissue has regenerative capacity
3. Rapid destruction of casual agent
4. Good vascular drainage
8. Systemic effects of both acute & chronic
1. Pyrexia
2. Weight loss
3. Haematological changes
4. Amyloidosis
5. Malaise, nausea

3.2 Chronic inflammation
1. 4 causes of chronic inflammation
1. Resistance of pathogen to phagocytosis e.g. Tuberculosis
2. Exogenous materials e.g. implanted prostheses
3. Autoimmune disease e.g. Rheumatoid arthritis
4.Granulomatous disease e.g. Crohn’s
2. Macroscopic appearances of chronic inflammation
1. Chronic ulcer
2. Chronic abscess
3. Thickening of hollow viscus wall
4. Granulomatous inflammation
5. Fibrosis
3. Microscopic appearance of chronic
1. lymphocytes, macrophages (because they live longer than neutrophils), plasma cells
2. Granuloma (collection of epitheloid histiocytes)
4. Causes of granulomatous disease
1. Bacteria, fungi, parasites
2. Materials that resist digestion
3. Drugs
4. Beryllium
5. Unknown e.g. Crohn’s

5.1, 5.2, 5.3 – Hypersensitivity, Organ rejection/autoimmune, immune deficiency

Type I – IgE-mediated hypersensitivity. Immediate, within minutes
What happens:
1. Sensitisation – Exposure to antigen bridges Fc receptors for IgE. This triggers mast cells to release mediators
2. Release of preformed mediators
-Histamines – Vasodilation, vascular permeability, smooth muscle contraction, mucus secretion
-Chemokines – Attract neutrophils & eosinophils
-Proteases – Tissue damage, kinin generation, activation of complements
Release of newly formed mediators
-Prostaglandins – Intense bronchospasm & mucus secretion
-Leucotrienes – 1000x more active than histamine
3. Additionally for asthma/eczema
-Activation of sensitised T-cells (Th2 subset)
-IL-4, IL-5, IL-13 release

Types of Type I
1. Atopic – Inherited overproduction of IgE antibodies against common environmental allergen
-Allergic rhinitis, asthma, eczema
2. Anaphylaxis – Generalised mast cell & basophil degranulation
-Peanuts, Latex, penicillin
3. Anaphylactoid – Similar to anaphylaxis but not IgE mediated
-Radiographic contrast media, anaesthetics

Type II – IgG, IgM mediated. Antibodies react to cell-bound antigens = phagocytosis/lysis of target cell
Types & Examples
1. Antibodies formed against drugs/metabolites results in cell destruction (bystander lysis)
-Haemolytic anaemia (Antibodies formed against RBCs)
-Thrombocytopaenic purpura (Antibodies formed against platelets)
2. Antibodies formed against normal cell functioning sites e.g. hormone receptors
-Graves disease (antibodies formed against TSH)
-Pemphigus vulgaris (antibodies formed against intercellular adhesion cells)
-Type II diabetes (antibodies formed against insulin receptors)

Type III – Deposition/formation of immune complexes which results in
-Complement activation
-Platelet aggregation
-Neutrophil attraction
-Local inflammation
Occurs in:
1. Persistent antigen exposure
2. Abnormal host immune reponse
3. Local defects
Examples
1. Post-streptococcal glomerulonephritis
-10-12 days after strep throat
-IgG & C3 immune complex deposition in glomerular basement membrane
2. Systematic Lupus erythematosus (SLE)
-Own nuclear antigens attacked
-Results in nephritis, skin lesions, arthritis (butterfly rash)

Type IV – Delayed hypersensitivity, mediated by T-lymphocytes. 2-3 days
What happens:
1. Sensitisation
-T-lymphocytes react with antigen
-Release IL-2,, interferon-alpha, TH1-cytokines
2. Delayed reaction (2-3 days)
-Local inflammation with T-lymphocytes, macrophages, eosinophils
Examples :
1. Contact dermatitis – small, reactive molecules that aren’t immunogenic by themselves
Pathogenesis – Induction phase – Langerhans cells binds the hapten-carrier protein complex & presents it to T-lymphocytes
-Elicitation phase – Effector T-cells migrate to skin & release cytokines & induce skin inflammation
-Patch testing – Reaction site inspected after 2-4 days for inflammation & induraiton
2. Tuberculin reaction e.g. Mantoux test
-Purified protein derivative of mycobacterium tuberculosis
-Not immune = no reaction
-Immune = Inflammation & induration after 2-3 days
3. Normal immune response to mycobacterium tuberculosis & leprae (is delayed hypersensitivity)
-If no hypersensitivity response, person develops tuberculosis or leprosy

5.2 Autoimmunity
1. Autoimmune vs autoimmune disease
Autoimmune – An immune response against self-antigens
Autoimmune disease – Tissue damge or disturbed physiological function from an autoimmune response
2. Criteria that autoimmune response causes disease
1. Demonstrate reactivity to self-antigen
2. Isolate this self antigen
3. Induce reactivity by immunisation in animal
4. Show similar pathological change as humans in this immunised animal
3. Organ specific vs non-organ specific
Organ specific – Autoantibody may target cell surface or intracellular molecule
Non-organ specific – Slef-antigen widely distributed in the body
4. Epidemiology of autoimmune disease
-3% of poopulation, more common in women, peak onset 15-65 y/o
-MS, rheumatoid arthritis, Type I diabetes
5. Aetiology of autoimmune disease
1. Genetic – Some single gene-defects in apoptosis, usually multiple genes. Strongest association w/ alleles of MHC
2. Environmental – 1. Hormones (females – oestrogens peak onset), 2. Infection (molecular mimicry), 3. Drugs (structural similarity to self), 4. UV radiation (can modify self-antigens)
6. Tissue damage mechanisms in autoimmune disease
Mediated by
-Autobody or immune complexes
-CD4+ T-cell mediated activation of macrophages or cytotoxic -T cells
– Combination
7. Sjogren syndrome – CD4+ T-cell reaction against unknown antigen in ductal epithelial cells of exocrine cells
8. Treatment of autoimmune disease – Replacement of organ function / Suppression of autoimmune response

Organ Transplant
1. Definitions
-Haloptype – A group of genes in an individual inherited from a single parent
-Allel – Alternative form of a gene
-Allogenic grafting – Between genetically different people
-Autologous grafting – From one part of a person’s body to another
-Xenogenic grafting – Between species
2. MHC
-Human antigens are called HLA (Human Leucocyte antigens)
-In humans they are encoded by a segment of chromosome 6 called MHC
-HLA system is extremely polymorphic (multiple alleles at each locus)
-MHC 1 – most nucleated cells
-MHC 2 – Expression normally restricted to antigen-presenting cells
-MHC 3 – Constitute early complement proteins C2 & C4
3. Pathogenesis of graft rejection
1. Afferent phase – MHC molecules on dendritic cells of donor are recognised by recipient CD4+ T cells
2. Effector phase – CD4+ T-cells enter graft & recruit effector cells, responsible for tissue damage (Macrophages, NK cells, B-lymphocytes, CD8+ T-cells)
-Most important cytokines in graft rejection are IL-2, interferon-alpha
-Critical parts that need to be attacked for rejection to occur are endothelium & parenchymal cells of the organ
4. Kidney graft rejection types
1. Hyperacute rejection
-Minutes-hours, must be removed
-Circulating cytotoxic antibody reacts with MHC class I antigens in donor kidney
-Acivation of complement = influx in polymorphonuclear leucocytes, platelet aggregation, obstruction of vessels = ischaemia = infarction = decreased renal function = anuria
2. Acute rejection
-Few days-weeks, immunosuppressive therapy reverses kidney damage
-Acute rejection associated with increased expression of MHC class I & II antigens in graft & early infiltration of CD8+ T cells
-Results in mononuclear infiltrate in renal cortex & necrosis in arterial walls
3. Chronic rejection
-Months-years, slow progressive renal failure & hypertension
-Does not respond to imunosuppressive therapy
-Histologically 1. Thickening of glomerular basement membrane
2. Hyalinisation of glomeruli
3. Interstitial fibrosis
4. Proliferation of endothelial cells
5. Complications of immunosuppresion
1. Increased susceptibility to infections (viral & fungal)
2. Recurrence of original disease
3. Increased incidence of malignancies (e.g. lymphoma of kaposi sarcoma)
6. Graft vs host & oral complications
1.haemopoietic stem cell transplant from bone marrow only chance to treat:
Aplastic anaemia, leukemia, immunodeficiency disorders, inborn errors of metabolism
1. Complications of HSCT are failure of graft, infection, GVHD
2. GvHD occurs in allogenic bone marrow transplants 7-14 days after transplant
3. Oral manifestations of GvHD are
1. Lichenoid lesions, ulcerations
2. Salivary gland dysfunction
3. Oral sclerosis, trismus

5.3 Immune deficiency
1. Immune deficiency
-Is a defect in the immune system which is primary (intrinsic defect) or secondary to underlying condition
-Presents as SPUR: Suppurative, Persistent, Unusual, Recurrent infections
2. Types of deficiencies
1. Primary antibody deficiency
2. Primary cell-mediated deficiency
3. Primary defects in phagocyte function (quantitative/qualitative)
4. Primary complement deficiency
3. 6 clinical features of immune deficiency disease
1. Recurrent & prolonged infections
2. Clinical features can be minimal despite severe infection
3. Poor response to antibiotics
4. Commonly staphylococcal
5. Involve skin & mucous membranes
6. Complicated by suppurative lympadenopathy
4. Chronic granulomatous disease
-From failure to produce high concentrations of toxic oxygen radicals during the respiratory burst accompanying phagocyte activation
-Chronic granulomatous disease typically presents in 0-3 months as severe skin sepsis caused by S. aureus/ C. albicans
-Complications – hepatic abscess, regional lymphadenopathy, osteomyelitis
-Abscesses & giant cell granulomas

AIDS – caused by HIV type I & II
5. 3 modes of transmission of HIV
1. Sexual intercourse
2. Sharing contaminated needles (needle stick injury)
3. Vertical transmission from mother -> child via breastfeeding/ pre-childbirth
6. Clinical spectrtum of HIV infection
Stage 1 – Transient, acute glandular fever-like smyptoms. In 10-20% of patients after events of infection
2. Asymptomatic
3. Asymptomatic persistent generalised lymphadenopathy (2 or more extra-inguinal nodes enlarged for more than 3 months)
Stage 4. Unexplained lymphadenopathy, diarrhoea, night sweats, systemic symptoms
-Opportunistic infections & tumours (candida)
7. Oral manifestations associated with HIV
1. Candiosis
2. Hairy leukoplakia
3. Kaposi sarcoma
4. Perio
5. NUP & NUG
8. Treatment of HIV – HAART (highly active anti-retroviral therapy) to control viral replication & limit progression of immune deficiency

2. Resin-Dentine bonding + misc

13. Degradation
Resin degradation
1. Absorption of water into resin results in resin degradation by plasticisation
2. Covalent bonds between polymers are disrupted when water is present
3. Results in leaching out of resin material and reduction in long-term bond strength
4. Partially-cured adhesives exhibit increased water absorption, further compromising CR-adhesive bond
5. Resin/collagen hydrolysis may degrade hybrid layer = Loss of resin from inter-fibrillar spaces and disorganisation of collagen fibrils = weaker resin-dentine bond
Degradation of Hybrid Layer
1. Hybrid layer is 70% resin + residual solvent and 30% collagen
2. Approx 70% of collagen in hybrid layer disappeared within 4 years. 35-70% bond strength lost within 12-14 months
3. Hybrid layer degradation due to enzymes in dentine & saliva (Matrix metalloproteinases MMPs + Cysteine cathepsins)
4. MMPs are bound in dentine and are exposed by acid etching
5. Enzymes activate after etching, causing collagen fibril unwinding (degradation)
6. Chlorhexidine most promising way to stabilise collagen (because enzyme inhibitor)
7. But CHX is soluble in water and can leach out of the interface over time

14. Substrate (dentine) variables affecting resin-dentine bond
1. Over-dry dentine surface – Collage fibril collapse & stick together, preventing primer and adhesive infiltration. Poor hybrid layer development
2. Over-wet dentine surface – Prevents complete infiltration of primer & adhesive (high volume suction adequate to remove moisture)
3. Excessively deep etching (>15-20s) – Demineralised intertubular dentine. If demin >2-3um, incomplete infiltration of primer & adhesive, leaving fluid at base of hybrid layer
4. Depth of cavity wall – Bonding more predictable to ‘superficial dentine’ cavity wall because of less proportion of dentine tubules present
5. Carious dentine – Bonding compromised in zones of carious dentine due to unpredictable presence of sclerotic & demin dentine
6. Sclerotic dentine – Common on worn lower anteriors/exposed root surfaces. Research recommends mechanical removal of sclerotic dentine surface OR etch 2x as long

1. Posterior Composites

  1. Dr G Christensen (2016) – “The larger the posterior composite, the shorter the longevity”
    1. The purpose of this comment is to emphasise caution in the use of direct composites, and the limitations of options in larger restorations
    Suggestion for patients with Class II restorative needs
    1. Small Class II preps (proximal only / 1/4 distance cusp-tip to cusp-tip at isthmus)
    -Directly placed CR with good technique can provide “Acceptable longevity, optimum aesthetics and tooth conservation”
    2. Medium Class II preps (1/3 cusp-tip to cusp-tip at isthmus)
    -Directly placed CR is viable choice with well-informed, co-operative patient
    -Time involved is often double the small CR, fee does not reflect extra time which can lead to cut corners
    -Tooth-coloured ceramic inlays are very good but expensive (usually 4-5x cost of CR)
    3. Large Class II preps (Over 1/2 cusp-tip to cusp-tip at isthmus)
    -If restored with CR, they will not serve for long in most situations (amalgam would have greater longevity)
    -Patients need to be informed of this
  2. Posterior composite proximal wear
    1. Tooth type and location has little influence on extent of proximal wear
    2. Proximal wear can result in a soft/absent contact, resulting in food impaction and caries
  3. Caries under Posterior composites
    1. The concern is with lack of adequate care and excessive haste in placement
    2. Posterior composites are considerably more technique sensitive than amalgam, so small mistakes or shortcuts can result in failure of restoration (Leinfelder, 1994)
    Rapid spread of caries under posterior composites
    1. 1,748 restorations evaluated at 7 years. The risk of secondary caries under composite restorations was 3.5x greater than in amalgams (Bernardo et al., 2007)
    2. Caries activity, location and type of restorative material has influence on amount & variety of bacteria (Splieth et al., 2003)
    3. Microbial variety difference – More strains of all types found under CR
    4. Similar ratios of aerobic-anaerobic flora, but more lactobacilli under failed CR
    5. Up to 8x more bacteria under failed CR (especially anaerobic rods)
    Conclusions
    1. CRs fail rapidly, therefore posterior CRs must be periodically checked to allow early caries detection and timely repair
    2. Inadequate CR placement may promote growth of cariogenic, obligate anaerobic and potentially pulpopathogenic bacteria
  4. Clinicians Report June 2018 – Epidemic of cervical caries and gaps in Class II CR restos
    3 Main causes
    1. Uncured resin at cervical margin – Could be due to excess adhesive (in resin-dentine bonding) or due to inadequate depth of cure
    2. Gaps/lack of margin integrity – Failure to place CR onto gingival margin
    3. Caries remaining at cervical margin – Haste/greed, did not remove all caries
    Gaps result in
    1. Post-op sensitivity, discomfort and pain – Because dentine tubules unsealed
    2. Caries associated with failed CR – Leakage
    3. Further loss of sound tooth structure – Because we have to replace the CR
  5. Key goals in incremental CR placement
    1. Minimise number of increments and time
    2. Seal the margins by optimising adaptation
    3. Protect/preserve previously placed increments
    4. Fill the remaining space to optimise cure
    5. Preserve margin-region enamel
    6. Restore contour (on buccal for aesthetics) and simple form (on occlusal for function)
  6. C-factor
    1. Configuration factor = Number of bonded surfaces / Number of unbonded surfaces
    2. C-factor used to provide a quick method to identify the likely interface stress between tooth and resin material
    3. Protocols designed to provide a low C-factor are likely to enhance adaptation
    4. Identifying high C-factor for a restoration, indicates need for protocols to control the effects of polymerisation contraction
    e.g.
    -High C-factor means consider reducing amount of CR in increment (So CR extends on fewer surfaces) and
    -Manage vulnerable interface so that C-factor approaches 1
  7. Managing polymerisation contraction of posterior composites
    1. Apply 1st increment to most vulnerable interface
    2. Apply first increment to one surface only
    3. Optimise adaptation to cavity walls by purposeful direction of curing light
    1. Robinson, 1987
    2. Goetsch, 1989
    3. Verslius and Douglas, 1996
    4. Engle, 1992
  8. 5 ways of achieving Rapid and Effective placement of a posterior composite
    1. Non-sticky composite
    2. Small increments (VERY small increments for ‘sealing’ increments – rapid, easily controlled, no excess)
    3. Filling the space – Larger quantities (can be with dispenser) according to depth of cure of the composite
    4. Use the best instrument for each task (No lubricants on instruments – messy)
    5. Control the CR, neat work
  9. Light curing concerns + Steps to optimise curing of posterior composites
    1. Heat generation – Dependent on time/distance from pulp (LED – 1000-1500 units vs QTH 400-600 units)
    2. Reduced time of cure – May compromise polymerisation
    3. Shortened pre-gelation time – More stress at interface with tooth
    4. Distance from CR or RMGI – Is gingival component fully cured? Loss of intensity with increasing distance
    5. Focal areas of polymerisation – uneven curing
    6. Strong recommendation to use GIC instead of RMGI for proximal portion of open sandwich due to less depth of cure in RMGI (opacity)
    Steps to optimise curing
    1. Light positioned as close as possible without touching (less than 3mm away)
    2. Stabilise & keep tip of light curing unit directly over restoration during cure
    3. Assistant – Hold light & shield, Dentist – Steady light tip at optimum angle/position
    4. Use radiometer regularly (weekly) to check intensity
  10. Use of bulk fill composites
    1. Combined technique with regular CR -> Increments placed using regular CR, remaining space filled with bulk fill
    2. High volumetric shrinkage
    3. Low modulus of elasticity/rigidity
    4. Further investigation needed to see if bulk fill CRs can perform as well as regular CRs in terms of polymerisation contraction (for margin sealing)
    Initial promotion
    1. Initially focussed on depth of cure “Placement in 5 seconds with 5mm Depth of Cure”
    2. But depth of cure was never the reason that incremental placement was used over bulk
    3. Incremental placement provides better sealing & less cusp deformation
  11. Flowables are the duct tape of dentistry
    1. Flowables have lower filler loading, lower viscosity
    2. Enhance the likelihood of leakage at margins, cause caries in proximal boxes, generally abused material
    3. 3-6% polymerisation contraction compared with 1.6-2.4% in regular CR
    4. Less rigid than regular CR
    5. Greatest thermal dimensional change (out of all materials)
    Recommendations
    6. Use flowables conservatively
    7. Don’t use in areas of high stress/occlusal loading
    8. Most common use is as a liner beneath CR, but most clinicians prefer RMGI anyway due to direct bonding to dentine & F- release
  12. Open sandwich restos
    1. Radiopaque GI restores to just gingival of contact region
    2. GI provides better seal if the margins is on root surface/very thin enamel
    3. Indications – Tooth coloured aesthetics required / Gingival wall on root surface or thin enamel
    4. Problems – GI is placed in the most inaccessable area
    Studies
    1. GI can be placed up to just short of contact region, but should not extend into the contact due to potential wear
    2. Open sandwich restos have less demin in adjacent tooth structure, more marginal discolouration, and slight concavity/loss of GI near gingival margin
    3. Slight concavity/loss of GI due to failure to adequately cure RMGI, abrasion (interdental brushes), or dissolution from early exposure to gingival fluid
    4. If RMGI is used for proximal portion, increments of less than 1.5mm (lower depth of cure because opacity) or use an auto-cured GIC