Gastroesophageal reflux disease (GERD)

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  • 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.
  • H2 blockers – cimetidine, famotidine
  • Proton pump inhibitors – dexlansoprazole, esomoprazole, Omeprazole, pantoprazole
  • Prokinetics – they elp to empty the stomach faster – include domperidone, metoclopramide
  • GERD complications – esophageal ulcer, esophageal stricture, Barrett’s Esophagus, lung problems such as chest congestion or aspiration, asthma, bronchitis or even pneumonia.

Source : Robbins and Cotran’s book of pathology

Barrett’s Esophagus

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  • 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.

Dentophysics (Part – 1)

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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 shaping dentistry

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  • 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.

Source : journal of dental economics

Nanodentistry

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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.

    dentifrobots

    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 :

    Nanocomposites :

    • 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
    • Advantages – increased hardness, improved flexural strength, decreased polymerization shrinkage, High polish retention

    Nanosolution (nanoadhesives) :

    • 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

    Dentifrices :

    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

    Dentition replacement therapy (major tooth repair) :

    Nanotechnology may utilize genetic engineering, tissue engineering and tissue regeneration initially, followed by growing whole new teeth in vitro and their iinstallation

    Nanotechnology will bring enormous changes in the field of dentistry when few challenges such as precise manufacture of nanoscale parts, financing and tactical concerns, social issues have overcome.

    Source : journal of international oral health