GERD is a digestive disorder that affects the ring of muscle between your Esophagus and stomach. This ring is called the lower esophageal sphincter.
Causes : in normal digestion, your LES opens to allow food into our stomach. Then it closes to stop food and acidic stomach juices from flowing back into your esophagus. GERD happens when the LES is weak or relaxes when it shouldn’t. This let’s the stomach’s contents flow up into the Esophagus.
Some doctors believe a hiatal hernia may weaken the LES and raise your chances of gastrophageal reflux. Hiatal hernia happens when the upper part of your stomach moves up into the chest through a small opening in the diaphragm.
Several other things can make it more likely that you’ll have GERD : being obese, pregnancy, delayed emptying of stomach (gastroparesis), diseases of connective tissue such as rheumatoid arthritis or lupus.
Symptoms : most common is heartburn, the burning or pain of heartburn can last as long as 2 hours. Besides pain, you may also have nausea, bad breath, trouble breathing, wearing away of tooth enamel, a lump in your throat.
Treatment – antacids : they neutralize acid in the Esophagus and stomach and stop heartburn.
Barrett’s Esophagus is a complication of GERD that is characterized by intestinal metaplasia within the esophageal squamous mucosa.
The greatest concern in Barrett Esophagus is that it confers an increased risk of esophageal adenocarcinoma.
Morphology – Barrett Esophagus can be recognised as one or several tongues or patches of red, velvety mucosa extending upward from the gastroesophageal junction
This metaplastic mucosa alternates with residual smooth, pale squamous mucosa and interferes with light brown columnar mucosa distally.
Goblet cells, which have distinct mucous vacoules that stain pale blue by H&E and impart the shape of a wine goblet to the remaining cytoplasm, define intestinal metaplasia and are necessary for diagnosis of Barrett Esophagus.
Clinical features – Barrett Esophagus can only be identified through endoscopy and biopsy, which are usually prompted by GERD symptoms
Treatment – endoscopic resection, which uses an endoscope to remove damaged cells to aid in the detection of dysplasia and cancer.
Radiofrequency ablation, which uses heat to remove abnormal Esophagus tissue.
After qualifying intermediate, we enthusiastically dream about our dental subjects but land up in the same boring physics of dental materials. Let us know why is it important to understand various properties…
Mechanical properties :
Stress – the force per unit area acting on millions of atoms or molecules in a given plane of material. Stress is the internal resistance of a material to an external load applied on that material.
Residual stress is caused within the material during the manufacturing process. Eg – during welding
Structural stress is produced in the structure during function. Eg – in abutments of fixed partial dentures
Pressure stress is induced in vessels containing pressurized materials. Eg – in dentures during processing under pressure and heat
Flow stress is produced when force of liquid strikes against the wall acting as load. Eg – molten metal alloy striking the walls of the mould during casting
Thermal stress is produced by material which is subjected to internal stress due to different temperatures causing varying expansions in the material. Eg – materials that undergo thermal stress such as inlay wax, soldering and welding alloys.
Fatigue stress is produced due to cyclic rotation of a material. Eg – rotatory instruments undergo rotational or cyclic fatigue.
Strain – it is defined as the change in length per unit original length and it may be elastic or plastic or a combination of both. Elastic strain is reversible i.e it disappears when force is removed. Plastic strain represents permanent deformation of the material which never recovers when the force is removed.
Young’s modulus : it is the stiffness of a material that is calculated as the ratio of the elastic stress to elastic strain i.e a stiff material will have a high modulus of elasticity while a flexible material will have a low modulus of elasticity.
Eg – principle of elastic recovery – burnishing of an open metal margin, where a dental abrasive stone is rotated against the metal margin to close the marginal gap as a result of elastic and plastic strain
Eg – impression material
The impression materials should have a low modulus of elasticity to enable it to be removed from the undercut areas in mouth. Modulus of elasticity should not be too low that the material cannot withstand tearing.
Hooke’s law : within the limits of elasticity the strain produced by a stress is proportional to the stress
Dentin is capable of sustainable significant plastic deformation under a compressive load before it fractures. Enamel – more stiffer and brittle than dentin. But dentin is more flexible and tougher.
Flexibility – defined as the flexural strain that occurs when the material is stressed to.its proportional limit. Materials used to fabricate dental appliances and restoratiots, a high value for the elastic limit is a necessary requirement. This is because the structure is expected to return to it’s origi al shape after it has been stressed and the force removed.
There are instances where a large strain or deformation may be needed with a moderate or slight stress such as in an orthodontic appliance. Here a spring is often bent a considerable distance under the influence of a small stress. In yhis case, the structure is said to possess the property of flexibility.
Resilience – the amount of energy absorbed within a unit volume of a structure when it is stressed to its proportional limit. When a dental restoration is deformed during mastication, it absorbs energy. If induced stress is not greater than proportional limit, the restoration is not permanently deformed i.e only elastic energy is stored in it. So restorative material should exhibit a moderately high elastic modulus and relatively low resilience.
Proportional limit – defined as the magnitude of elastic stress above which plastic deformation occurs. Below the proportional limit, there is no permanent deformation in a structure. Materials like cobalt/chromium alloy which has high proportional limit is widely used for the fabrication of connectors because they can withstand high stresses without permanent deformation.
Yield strength – defined as the stress at which a test specimen exhibits a specific amount of plastic strain. It is a property often used to describe the stress at which the material begins to function in a plastic manner. In the process of shaping an orthodontic appliance or adjusting the clasp of a removable partial denture it is necessary to apply a stress into the structure in excess of yield strength of the material is to be permanently bent or adapted.
Flexural strength – defined as the force per unit area at the instant of fracture in a test specimen subjected to flexural loading. Also known as modulus of rupture. Most prosthesis and restoration fractures develop progressively over many stress cycles after initiation of a crack from a critical flaw and subsequently by propagation of the crack until a sudden, unexpected fracture occurs.
Conclusion – while designing a dental appliance or a restorative material, it should have adequate mechanical properties to withstand the stress and strain caused by the forces of mastication. All the methods must be employed to minimize stress concentration so that the restorative material or the appliance is in harmony with the different types of forces occuring in the oral cavity.
Source : Phillip’s and Craig’s restorative dental materials
Artificial intelligence refers to the stimulation of human intelligence in machines that are programmed to think like humans and mimic their actions.
On the other hand, artificial general intelligence (AGI) is probably what we are thinking of when we hear AI. AGI isn’t quite developed yet. AI, however, is very much present and growing in every industry, from consumer technology to health care
How is AI currently used in dentistry?
In dentistry, AI is being used for different applications. First, AI is currently being used for voice commands, such as with DEXvoice by Simplifeye and DEXIS (software platforms).
Phrases such as “Alexa, show me the bitewings of number 19” will soon be uttered in dental practices around the country.
Through machine learning, MMG Fusion’s chairfill ( software designed to help dental practices fill holes in the schedule) retrieves data from a dentist’s record and analyzes it. Chairfill can find the most profitable dentistry not yet provided, communicate with patients directly, and even book patients appointments. It does all of this without human involvement.
Scientists are already using AI in caries detection. One company utilising AI in this way is Dentistry.ai. Its algorithm is designed to take a large data set of radiographs and recognise patterns within that data. As a result, it hepls practitioners more accurately to identify carious lesions.
The founders of Dentistry.ai predict that AI will be tightly woven into the fabric of how dentistry is done.
The primary llimitationsto AI are insufficient data and inaccurate data. This means that clinicians today should focus on collecting the data now to be able to use it fully in the future. If we can do that, we can continue to provide greater care to our patients.
Advancement in technology led to its usage in various fields and it helped build new devices that were not possible 10 or 20 years ago and made most of the jobs easier.
Such advancements include application of nanotechnology in dentistry, also known as nanodentistry, allows for treatment possibilities in restorative dentistry, orthodontics and periodontics.
Within restorative dentistry, nanorobots can be used in cavity preparation, restoration, and even dentition renaturalization.
Due to their size, nanobots work at the atomic, cellular, and molecular level to perform major tasks and help dentists in managing complicated cases at the microscopic level with ease and precision.
Bottom-up Approaches :
Local Nanoanaesthesia –
A colloidal suspension containing millions of anesthetic dental nanorobots would be used to induce local anaesthesia. Deposited on the gingival tissue, the nanorobots would reach the dentin and move toward the pulp via dentin tubules guided by a nanocomputer under the control of dentist. On reaching pulp, the analgesic robots may close down all sensation in tooth. When the treatment procedure is done, the nanorobots may be ordered to re-establish all sensations and to exit from the tooth
Tooth repositioning :
All the periodontal tissues, namely the gingiva, periodontal ligament, cementum and alveolar bone, may be directed by orthodontic nanorobots leading to Swift and pain-free corrective movements
Nanorobotic dentifrice (Dentifrobots):
Toothpastes or mouthwashes could contain the dentifrobots which would then survey all gingival surfaces regularly.
Dental durability and cosmetics :
Nanostructured composites can be included with sapphire 12 or diamond to reduce their brittleness which are used to enhance the toughness and appearance of teeth.
Diagnosis of oral cancer :
Nanoscale cantilevers : elastic beams used to attach with cancer linked molecules
Nanopores : small holes that enable DNA passage one strand at a time, this making DNA sequencing highly efficient
Nanotubes : carbon rods that can detect affected genes and also localise their location
Quantum dots : these glow very brightly in UV light. They attach to proteins associated with cancer cells, this localizing tumours
A nanoshell is a tiny bead like structure with superficial metal layers which may imbibe selective wavelengths of radiations and lead to large amounts of heat production. This results in specific devastation of the tumour cells, sparing the normal cells.
Dental nanomaterials – anodentistry as top-down approach :
Nanofillers are minute particles, igher proportions can be achieved, and result in distinctive physical, mechanical and optical properties.
One nanocomposite system has three different types of fillers : non agglomerated discrete silica nanoparticles, barium glass and prepolymerized filler
Nanosolutions are constituted by dispersible nanoparticles, which are then used as a component in bonding agents.
Advantages – higher dentin and enamel bond strength, high stress absorption, longer shelf life, durable marginal seal, flouride release
Impression materials :
Traditional vinylpolysiloxanes have incorporated Nanofillers which produce a distinctive material with improved flow, enhanced hydrophilic properties and superior detail precision.
Nano-composite denture teeth :
Porcelain teeth are highly wear resistant but are brittle, acrylic on the other hand undergo undue wear. Nanocomposite denture teeth are made of PMMA and homogenously distributed Nanofillers
Advantages – excellent polishing ability and stain resistant, superb esthetics, enhanced wear resistance and surface hardness
These are mainly made of nanosized hydroxyapatite molecules. They will result in protective shell on tooth surface and may even repair damaged areas. Microbrite dentifrice has microhydrin which breaks down the organic food particles
Prosthetic implants :
Nanotechnology would aid in the development of surfaces with definite topography and chemical composition leading to predicable tissue integration. Tissue differentiation into definite lineage will accurately determine the nature of peri implant tissues. Eg- nanotite, nano-coatef implant
Nano sterilizing solution :
A new sterilizing solution following nanoemulsion concept has been developed by Gandly Enterprises Inc Florida. Nanosized oil droplets attack and destroy the pathogens. Eg – eco tru disinfectant
Acromegalic Gigantism: it is a rare condition with symptoms of both acromegaly and gigantism.
Cushing’s disease : it is a hormonal disorder caused by high levels of the hormone cortisol in your body. It’s also known as hypercortisolism.
Causes : most common cause is related to medications called glucocorticoids, one can also get the disease from injectable steroids, such as repeated shots for joint pain, bursitis, back pain
Symptoms – buffalo hump, rounded and rosy face, thinning skin, acne, being very tired, kidney stones, sleep problems
Treatment : surgery, hormone replacement medications, life style changes
Hypoactivity of anterior pituitary gland:
Dwarfism : it is a pituitary disorder in children characterized by stunted growth
Causes : reduction of GH secretion in infancy or early childhood due to deficiency of GHRH from hypothalamus or somatomedin C, atrophy or degeneration of acidophilic cells in the anterior pituitary, achondroplasia
Signs : stunted skeletal growth, head becomes slightly larger in relation to the body, reproductive function is not affected, mental activity is normal
treatment : corrective surgeries, surgery to widen spinal cord, extended limb lengthening
Acromicria : it is characterized by the atrophy of the extremities of the body
Causes : deficiency of GH releasing hormone from hypothalamus, tumour of chromophobes, panhypopituitarism (reduction in secretion of all hormones of anterior pituitary gland)
Signs : atrophy and thinning of extremities of body, hypothyroidism, person becomes lethargic and obese
Simmonds’ disease : it is also called pituitary cachexia
Cause : occurs mostly in panhypopituitarism
Symptoms : rapidly developing senile decay, loss of hair over body and loss of teeth, skin on face becomes dry and wrinkled
Hyperactivity of posterior pituitary gland:
Syndrome of inappropriate hypersecretion of antidiuretic hormone : it is characterized by loss of sodium through urine duebto hypersecretion of ADH
Cause : due to cerebral tumours, lung tumours and lung cancers
Signs and symptoms : loss of appetite, weight loss, nausea and vomiting, headache, muscle weakness, spasm, cramps
Hypoactivity of posterior pituitary gland:
Diabetes inspidus : it is characterized by excess excretion of water through urine
Cause : deficiency of ADH which occurs due to lesion or degeneration of supra optic and paraventricular nuclei of hypothalamus, atrophy of posterior pituitary
Signs : polyuria, polydypsia (intake of excess water) and dehydration
Toothbrushes have been in existence since thousands of years and have become an indispensable part of our life. Earlier it used to be in the form of chew stick format but over time, different formats of tooth brushes emerged such as tree twigs, bird feathers and porcupine quills.
Let us know about the different type of toothbrushes available in today’s market
The most common form of toothbrush available in our homes is manual toothbrush.
Bristles available for this type of toothbrush are soft, medium or hard bristled. Most dentists advice soft bristled brush but other two help in removal of more plaque but that may wear away the enamel if brushed too hard
Round or square shaped headed toothbrushes are available but diamond shaped head is more convenient to rach the back and sides of molars
Toothbrush handle design includes straight, contra-angle, non-slip grip and flexible types.
An electric toothbrush performs rotations of its bristles and cleans hard to reach places. Some even have timers to help you brush more effectively. It has been discovered that compared to a manual brush, the multi-directional power brush might reduce the incidence of gingivitis and plaque.
Electric toothbrushes are further divided into three types depending on speed of its movements – standard power toothbrushes
Sonic toothbrush is powered toothbrush that is fast enough to produce a hum in the audible frequency
Ultrasonic toothbrush is a powered toothbrush which is faster than the sonic toothbrush
Also called interproximal brush used for cleaning between teeth and between the wires and dental braces and teeth
it is used specifically to clean along the gumline adjacent to the teeth.
A sulcabrush is ideal for cleaning specific difficult-to-reach areas, such as between crowns, bridgework and crowded teeth.
It is a small round brush head compromising of Seven tufts of tightly packed soft nylon bristles, trimmed so the bristles in the center can reach deeper into small spaces.
It is a miniature plastic molded toothbrush which can be placed inside the mouth.
They are generally used by travellers
It is usually available in different flavours such as mint or bubble gum
These are toothbrushes made out of biodegradable substances such as wooden handles, bristles of bamboo or pig bristles and replaceable heads
Atherosclerosis is characterized by intimal lesions called atheromas that protrude into vessel lumens.
An atheromatous plaque consists of a raised lesion with a soft, yellow, grumous core of lipid (mainly cholesterol and cholesterol esterscocered by a white fibrous cap.
Major risk factors for atherosclerosis:
Non modifiable factors –
Age : atherosclerosis is typically progressive, it does not usually manifest clinically until middle age or later
Gender : premenopausal women are relatively protected aginst atherosclerosis compared to age-matched men. After menopause, however, the incidence of atherosclerosis related diseases increases and at older ages actually exceeds that of men
Genetics : family history is theost significant independent risk factor for atherosclerosis. The well established familial predisposition to atherosclerosis is usually multifactorial, relating to inheritance of various genetic polymorphisms and hypertension or diabetes
Modifiable risk factors :
Hyperlipidemia : and more specifically hypercholesterolemia is a major risk factor for atherosclerosis, hypercholesterolemia is sufficient to stimulate lesion development. LDL cholesterol is the form of cholesterol that is delivered to peripheral tissues. In contrast, HDL mobilizes cholesterol from tissue and transports it to the liver for excretion in the bile.
Hypertension : it is the most important cause of left ventricular hypertrophy and hence the latter is also related to IHD
Cigarette smoking : the increased risk and severity of atherosclerosis in smokers is due to reduced level of HDL, deranged coagulation system and accumulation of carbon monoxide in the blood that produces carboxyhemoglobin and eventually hypoxia in arterial wall favouring atherosclerosis.
Diabetes mellitus : the incidence of atherosclerosis is twice as high in diabetics as in non diabetics. There is also an increased fold of strokes and a 100-fold increased risk of atherosclerosis induced gangrene of the lower extremities.
Pathogenesis of atherosclerosis :
Endothelial injury – endothelial loss due to any kind of injury results in intimal thickening.
The etiological culprits contributing to endothelial cell dysfunction in early atherosclerosis include hypertension, hyperlipidemia, toxins from cigarette smoke, homocysteine and even infectious agents
Hemodynamic disturbances – plaques tend to occur at Ostia of existing vessels, branch points, and along the posterior wall of the abdominal aorta, where there are disturbed flow patterns
Lipids – the dominant lipids in atheromatous plaques are cholesterol and cholesterol esters. Chronic hypercholesterolemia can directly impair endothelial cell function by increasing local oxygen free radical production; oxygen free radicals can injure tissues and accelerate nitric oxide decay, reducing its vasodulator activity
Inflammation – monocytes transform into macrophages and avidly engulf lipoproteins including oxidised LDL . Activated macrophages produce reactive oxygen species that aggrevate LDL oxidation and elaborate growth factors that drive smooth muscle cell proliferation
Infection – herpes virus, cytomegalovirus, Chlamydia pneumoniae have all been detected in Atherosclerotic plaques but not in normal arteries.
Smooth muscle cell proliferation – initial smooth muscle cell proliferation and ECM deposition convert a fatty streak, the earliest lesion into a mature atheroma and contribute to progressive growth of atherosclerotic lesions
Morphological features of atherosclerosis:
Fatty streaks and dots : they may be the precursor lesions of atheromatous plaques and are prominent in aorta and major arteries
Gelatinous lesions : they develop in the intima of the aorta and may also be the precursora of plaques
Atheromatous plaques : a fully developed atheromatous lesion is called atheromatous plaque. Most often and severely affected is the abdominal aorta. Grossly they are white to yellowish white lesions varying in diameter from 1-2 cm. Microscopically, superficial luminal part of fibrous cap is covered by endothelium, and is composed of smooth muscle xells; cellular area under the fibrous cap is composed of mixture of macrophages, foam cells, lymphocytes; deeper central soft core consists of extracellular lipid material, cholesterol clefts,fibrin; in oldrr and more advanced lesions, the collagen in the fibrous cap may be dense and hyalinised
Complicated plaques – various pathologic changes that occur in fully developed atheromatous plaques are called the complicated lesions. Calcification, ulceration, thrombosis, hemorrhage , aneurysm formation are the complications
Source : Robbins and Cotran’s book of pathology and Harsh Mohan’s textbook of pathology
Angina pectoris (literally heart pain) is characterized by paroxysmal and usually recurrent attacks of substernal or precordial chest discomfort caused by transient myocardial ischemia.
The three overlapping patterns of angina pectoris : 1. Stable or typical angina 2. Prinzmetal variant angina 3. Unstable or crescendo angina
Stable angina :
It is the most common form and is also called typical angina pectoris
Cause : an imbalance in coronary perfusion (due to chronic stenosing coronary atherosclerosis) relative to myocardial demand, such as that produced by physical activity, emotional excitement or any other cause of increased workload.
Typical angina pectoris is usually relieved by rest or administering nitroglycerin (a vasodilator that increases perfusion)
Pharmacology – nitroglycerin is the drug of choice, administered sublingually with an initial dose of 0.5 mg, which usually relieves pain in 2-3 minutes.
Prinzmetal variant angina :
It is an uncommon form of episodic myocardial ischemia
Cause : coronary artery spasm
It is unrelated to physical activity, heart rate or blood pressure
Pharmacology – episodes of coronary vasospasm are treated with nitrates; for prophylaxis, nitrates and calcium channel blockers (Amlodipine, nifedipine and diltiazem) are effective.
Unstable or Crescendo angina :
It refers to a pattern of increasingly frequent pain of prolonged duratio, that is precipitated by progressively lower levels of physical activity or that even occurs at rest
Cause : mostly by disruption of an atherosclerotic plaque with superimposed partial thrombosis and possibly embolization or vasospasm (or both)
Unstable angina thus serves as a warning that an acute MI may be imminent; indeed, this syndrome is sometimes referred to as preinfarction angina.
Pharmacology – it requires treatment with multiple drugs – antiplatelet drugs, anticoagulants, nitrates, beta blockers, CCBs and statins