2024 IACCP Master Question Bank questions and Answers

2024 IACCP Master Question Bank questions and Answers a) Name 3 types of bone cell and describe their functions. (3 marks) 1. osteoblast - secretes new bone 2. osteocytes - maintain bone/bone cells that are embedded in bone secreted by osteoblasts 3. osteoclasts - resorb bone/bone resorption a) Draw and label a diagram of a monosynaptic reflex. (6 marks) (b) How does the muscle spindle maintain its sensitivity to stretch? (4 marks) All tendon reflexes are known as monosynaptic reflexes because of this direct connection of the afferent with the motor neurone The muscle spindle projects to motor neurones in the same muscle. In normal life the monosynaptic reflex helps to keep a muscle at a fixed length despite varying loads . γ (gamma) motor neurones adjust the sensitivity of muscle spindles so that they can respond to small extensions from a range of resting lengths. When the brain activates the a motor neurones , it also activates the g motor neurones. This is called α−γ linkage . α−γ linkage keeps the spindle sensitive to stretch even at different absolute lengths of muscle a) List FIVE desirable properties of a restorative filling material and briefly describe each one. (5 marks) There are slightly different desirable properties for a restorative filling material depending on whether it is for anterior teeth or for posterior teeth. For anterior teeth , it is desirable to: Colour match Be natural looking in different light conditions It is not so important for an anterior restorative material to have hugely high compressive strengths Conversely for posterior teeth: It is desirable that the material has high compressive strength to be able to last and not breakdown under the high biting forces Aesthetics are not the main priority for posterior fillings, as they are not so visible. OR Biocompatible – the material must be bioinert and bioactive Chemically resistant – does not react or react minimally with chemicals and is durable against changes in pH Dimensionally stable – Does not change in shape Minimal thermal conductivity – carry little or no thermal energy Minimal electrical conductivity – carry little or no electrical current b) Describe the hazards of monomers/polymers. (5 marks) 2 MARK ANSWER Monomers do not undergo 100% polymerisation . Unreacted materials can reach the oral cavity of the patient and cause irritation . Residual monomers can cause irritation to skin, allergic dermatitis and asthma 5 MARK ANSWER Hazards of monomers/polymers include: During the polymerisation process, not all the monomers may be incorporated into the material, leaving residual monomers that can cause issues such as irritation, allergic dermatitis . This is especially important if it is a free radical polymersation process, since free radicals can be very dangerous to human cells . The patient may have an allergic reaction to the monomer/polymer Over time the polymer may leach monomers into the systemic circulation, causing adverse reactions in the body The polymer might be carcinogenic and cause a localised carconima in the oral cavity where thr material was placed The patient can have a dermatoses If there is a volatile methylmethacrylate monomer , it could cause the patient/dentist/technician respiratory problems such as asthma Why doesn’t blood clot in a normal blood vessel? In a normal vessel, the blood doesn’t clot because the epithelial cell lining of the vessel acts as a protective layer preventing the underlying collagen fibrils from being exposed to circulating clotting factors . The blood will begin to form a clot when the vessel wall is damaged and exposed collagen fibrils and TIssue Factor are exposed to clotting factors in the blood. Describe the role of platelets in clotting and the effects of aspirin on clotting. In clotting, platelets, which are small ciruclating cell fragments that have many platelet receptors on their cell wall and will bind to collagen fibrils, and then begin to aggregate with other platelets that get activated . Platelets are essential for haemostasis , they contain 2 types of vesicles: the dense core granules which contain ADP, ATP, serotonin and calcium ions , and the alpha granules which contain vWF, fibrinogen and factor V Aspirin is an anti -platelet drug that acts to destroy cyclo -oxygenase enzyme in platelets, and prevents production of thromboxane A2. TXA2 needed for vasocontriction and platelet release. How are glass formed and how does cooling rate affects properties? (5 marks Glasses are formed when a high viscosity melt is cooled rapidly above a critical rate. The crystalline structure does not have time to form. Glasses are in a metastable state - As they cool their viscosity increases, until they become rigid solids They are sometimes called "supercooled liquids". Glass transformation (transition) point (Tg) depends on cooling rate. Glasses are formed when the cooling rate is above a critical rate. At Tg high viscosity restricts mobility of molecules, cannot move quickly enou gh to pack closer together (shrinkage rate lower) Glass has 3 different bits: Former, intermediate, and modifier Give example of former and modifier and the affect a modifier has on properties (5 marks) Oxide glass composition comprises up to 3 different types of oxide: Former, Intermediate, Modifier. An example of a former is: SiO2 An example of a modifier is: K2O, CaO Glass modifiers disrupts the 3 -D network, they reduce connectivity (breaks bonds), reduce the viscosity and fusing (softening) temperature and increases the coefficient of thermal expansion a) Define stroke volume Cardiac Output is the product of: Stroke Volume x Heart Rate Stroke volume is determined by the venous return , which is controlled by blood volume (this is controlled by the kidney primarily). It is the volume of blood that the left ventricle pumps out to pass around the body with each contraction. Name the 2 pumps involved in venous return and describe how they work The skeletal muscle pump is a physiological mechanism by which the veins (which are surrounded by skeletal muscle) get pressed through contraction of the surrounding skeletal muscle which forces the blood in one direction, back towards the right atrium . The lower valve prevents back flux. During relaxation back flux prevent by valves. Veins refill from capillaries The second pump is the Respiratory pump - Intrathoracic pressure decreases during inspiration and abdominal pressure increase, squeezing local abdominal veins, allowing thoracic veins to expand and increase blood flow towards the right atrium. c) Define preload and after load and describe factors affecting preload Preload is the volume of blood filling within the ventricles prior to ventricular contraction , and the afterload is any blood residually remaining within the ventricles after they have contracted , because not all the blood is ejected. Preload is affected by the venous BP, by venous return 3 types of dentinogenesis (8 marks) Dentinogenesis is the process of dentine formation: Primary dentinogenesis is the formation of dentine prior to the eruption of the tooth Secondary dentinogenesis is the formation of dentine taking place from when eruption of the teeth occurs ; structurally it forms dentine similar to that from primary dentinogenesis but with fewer dentinal tubules Tertiary dentinogenesis is the formation of dentine in response to an external stimulus (eg. carries/attrition), it is structurally different to primary/secondary dentine and has a protective role . What is pre -dentine and what is mantle dentine? (2 marks) PREDENTINE: Predentine is the innermost layer which is unmineralised , it is where new dentine is being deposited throughout life MANTLE DENTINE: This is the first -formed layer of dentine in the crown region of the tooth Describe the different types of dentinogenesis. (8 marks) Primary Dentin : Forms before tooth eruption . Becomes translucent with age and can be used in forensic dentistry to age patient Secondary Dentin : Forms after tooth eruption . Has similar structure to primary dentin ( fewer tubules than primary dentin ). Reduces pulp chamber and root canal size over time . Tertiary Dentin : Forms in response to external stimuli (e.g. caries). It has a role of protecting the teeth. Can be reactionary dentin or reparative dentin. Sclerotic Dentin: