Invisalign

Invisalign or clear aligners are orthodontic devices that are transparent, plastic form of dental braces used to adjust teeth.

They are designed as follows :

  1. begins with taking X-rays and photographs for diagnostic purposes.
  2. Capturing patient’s bite, teeth and gums via bite registration and polyvinyl siloxane impressions or an intra-oral digital camera.
  3. Dental impressions are scanned in order to create a digital 3D representation of teeth.
  4. Technicians move the teeth to desired location with program which creates stages between current and desired tooth positions. Anywhere from 6 to 48 aligners may be needed. Each aligner moves teeth from 0.25 mm to 0.33 mm.
  5. The aligner are moulded using CAD-CAM software.
  6. The aligners are made from an elastic thermoplastic material that applies pressure to the teeth to move into aligner’s position.
  7. Patients that need a tooth rotated or pulled down may have a small tooth, coloured composite attachment bonded onto certain tooth.

Each aligner is intended to be worn an optimal 2 hrs a day for one to two weeks. On average, the treatment process takes 13.5 months although it varies based on complexity of planned teeth movements.

Cost of clear aligners in India ranges from 1,50,000-3,50,000.

Pros of invisalign :

  1. Comfort – it is physically comfortable to wear. Since there are no brackets or wires, one need not worry about getting any painful nicks or cuts in the mouth. Similar to mouth guard and lacks any sharp edges.
  2. More attractive – since it’s clear, doesn’t leave your mouth full of metal. Most people won’t even know you are wearing them.
  3. Can be removed – it can be removed for eating, brushing teeth and flossing. That is not something that cannot be done with braces. It allows you to eat food you want and practice better oral hygiene, which helps to lower your risk of developing gum disease while you go through the process of straightening teeth.
  4. Minimal maintenance – this requires minimum maintenance. They can get dingy over time when we wear them but you can freshen them by using a toothbrush dipped in a small amount of bleach and water. Scrubbing them for a minute will eliminate any stains.

Cons of invisalign :

  1. Expensive – this treatment is not covered by dental insurance, which means you can expect to pay anywhere from 1Lakh-4Lakh for them.
  2. Attachments – More and more attachments to go along with invisalign have become norm. The attachments are usually enamel ridges that stick to your teeth in a way that is similar to brackets that are included with standard braces. The attachments are used to click into aligners so that they fit better and can more effectively shift your teeth into better position. Attachments also make invisalign much more noticeable.
  3. Tooth discomfort – getting new invisalign aligner trays can be uncomfortable and even painful when you get fitted for a new set.
  4. Material inaccuracy – since the fitted plastic used in clear aligners is not as rigid as the metal used in traditional braces, sometimes the material needs to be compensated in the areas that require movement.

Alcohol & its effect on teeth

Quaffing and boozing have become common in almost all over the world. It does has a deleterious effect on liver but does it effect teeth too? Oh yes!!! it does has a role in effecting oral cavity in wide ways. Let us quickly go through it’s action.

  • Drinks high in alcohol like spirits can dry out mouth. Not only does this problem can cause bad breath, it also boosts chances of cavities. Saliva keeps teeth moist and helps to remove plaque and bacteria from the tooth’s surface. This effect is lost due to alcohol consumption hence providing space for commensals to become pathogens. Moreover, the sugar content in alcohols tremendously increase the risk of cavities and periodontitis because of sugars feeding bacteria.
  • Drying of mouth eventually leads to white tongue which is actually the inflammation of papillae and bacteria & dead cells trapped with them, causing a white film to cover the surface of the tongue. Bad breath along with black hairy tongue may be a sequelae to the condition.
  • Beer is acidic, which means that teeth are more likely to be stained by the dark barley and malts found in darker beers. The colour in beverages comes from chromogens. Chromogens attach to teeth enamel that has been compromised by acid in alcohol & stain teeth.
  • Adding citrus to an alcoholic beverage doesn’t make it healthier for teeth. Even a squeeze of lemon provides enough acid to eat away at tooth enamel.
  • Alcohol abuse is the “second most” common risk factor for oral cancer according to CDC. In addition, individuals who suffer from alcohol dependency tend to have higher plaque levels on their teeth and 3 times as likely to suffer from permanent tooth loss.
  • Recent research shows that alcohol and oral health may have even more far-reaching effects on overall health with periodontitis thought to play a major role in conditions such as premature birth and diabetes.

How can we avoid such deleterious effects?? Well!! here are few tips :

  • You can keep discoloration at bay by munching on food while drinking and then chewing gum once you are done consuming. This will bathe your mouth in saliva & bring your pH back to normal.
  • Alternate drinks with water to rinse teeth of any sugars or citrus, drink through a straw to concentrate the beverage, take extra care to brush and floss your teeth regularly.
  • Have a regular dental checkup in every 6 months to ensure your enamel is intact.
  • There is no such healthy drink but if you choose to imbibe, there are some drinks that are better choice than others, still with moderation. These drinks are:
    • Light beer : high water content and low acidity levels, safer option for teeth. Bonus points if you choose a light colored beer.
    • Gin and tonic : both liquids in this beverage are clear, no risk for teeth staining and contain low acidity levels.
    • Brut champagne : low sugar content, drinks that are drier like this particular type of champagne are less likely to cause problems in our mouth.

References : wcdentalarts.com, deltadentalins.com, covingtondentalcenter.com

Myths and facts about dentistry

We often come across few advices which are actually misconceptions among people. Let us see what are those myths and find out the actual facts to spread right knowledge about dentistry.

Myth 1 : Brushing harder cleans better

Fact : absolutely not!! It’s a misapprehension that plaque can be removed by brushing harder. Applying too much pressure may slowly erode enamel, which cannot repair itself once it suffers significant damage. One may experience increased sensitivity and a heightened risk of cavities due to such activity. Brushing too hard can cause the gum tissue to shrink back (gum recession). So brush in a soft and right way.

Myth 2 : White teeth are healthy teeth

Fact : one can have pearly white teeth and still have gum infections or cavities. Likewise one can have perfectly healthy teeth which are off white, yellowish or even brownish. Enamel is on the surface of every tooth and it has a natural hue of white. However, the underlying dentin layer has a slightly yellowish colour. This yellowish hue shows through the enamel in almost everyone.

Myth 3 : If one has no oral health concerns, there’s no need for an exam.

Fact : definitely not!! Here are six reasons as to why one must visit a dentist once in every six months.

Reason 1 : oral cancer is an extremely serious disease that manifests itself in various ways. Without knowing the signs of its early onset, oral cancer is often not diagnoses and can quickly progress and can become life threatening. Dentist is highly trained to recognise these signs and with regular checkup the likelihood of catching oral cancer in time is dramatically high.

Reason 2 : Even with the most diligent tooth brushes and flosses, there are small areas in the mouth that are missed by a regular brushing and flossing. Regular dental cleaning remove tartar from eroding teeth or cleaning holes in them, which is how cavities are created.

Reason 3 : Regular dental cleanings are essential in catching and addressing gingivitis before it gets out of hand. “Better to hold a tooth in mouth rather than replacing the lost ones by a veneer or implant”.

Reason 4 : There are many bad habits that can have a negative impact on our oral health, some of which one may not even realize are causing issues. Some of them include chewing ice, biting nails, clenching jaw, grinding teeth, eating particularly sticky or hard sweets, brushing too hard, drinking cofee and red wine and ofcourse smoking. A regular checkup can help in can identify oral damages caused by these which one may have not noticed.

Reason 5 : A crucial part of visiting dentist is getting one’s teeth and jaw bone x-rayed. X-ray images allow dental professionals to see what is happening beneath the surfaces of your mouth and can find, diagnose issues that may be invisible to naked eye. Like impacted tooth, bone decay, swelling, cysts or tumours.

Reason 6 : In addition to checking mouth, gums and tongue for signs of oral cancer, dentist will also check one’s neck, jaw and lymph nodes located just below jaw line for any swellings or lumps or other abnormalities.

Myth 4 : Teeth cleaning / scaling and polishing will abradd the enamel and cause sensitivity issues.

Fact : Cleaning safely remove the plaque and bacteria that builds up over time on the teeth and gums. They don’t damage enamel on the teeth. Infacf, if teeth are not cleaned regularly, inflammation can occur and this can lead to gum disease sue ro the bacteria residing in the plaques.

Myth 5 : Braces are only meant for the younger.

Fact : getting braces may be a little easier or go a little faster during adolescence but adults from all walks of life should know that age is just a number when it comes to receiving and benefiting from orthodontic treatment. Adults count for 20% of orthodontic patients according to AAO statistics. Although harder bone rissue can mean a longer, more involved treatment process for adults with braces, the right orthodontic treatment plan is usually all it takes to straighten teeth, improve bite alignment, make oral hygiene easier and create a perfect smile at any age.

Myth 6 : There is no need to wear retainers after orthodontic treatment.

Fact : oh yes!! You need to wear those retainers given by your dentists for atleast 9 months and then dropping down to nightly wear after that. Going a year without retainer means that your teeth will have continued to move back to their original position and may even be crooked. The solution may be to restart treatment with braces. Isn’t it better to have retainers in their place rather than spending again on braces?!!

Myth 7 : Dental treatment costs a fortune.

Fact : the only reason one has ro spend so much on a dental treatment is because he/she didn’t take care of their teeth as much as they should have. Neglect, or rathee, result of neglect is always costlier than the the routine dental appointment that pops up in one’s calender twice a year. Moreover, the dental equipment are costlier too because of which a normal dentist demands more which is actually normal compared to what he invests.

Myth 8 : A fast prosthodontist is a good prosthodontist.

Fact : you are mistaken. Fast is not always good. A prosthodontist offers specialized treatment that cannot be rushed. It’s important that they take their time to make sure the job is done right the first time. While dentists may want to keep their patients moving, a prosthodontist takes his time and does what is best for the patient.

Myth 9 : I’m better off with my natural teeth or no teeth.

Fact : ofcourse natural teeth are always preferable. However, if one has lost one or few teeth to injury, disease or decay, a dental implant is truly the next best thing. The tooth that opposes the site of missing tooth may start to grow out from its position because it no longer has the opposing tooth to resist it. One may experience increased sensitivity and other issues around this super-erupted tooth.

References : 123dentist.com, reeseortho.com

HOLISTIC SPICES

India is the world’s largest producer, consumer and exporter of spices. We use spices in culinary art to impart taste but do you know that these spices also aid in maintaining oral health? Let us quickly go through few of them and spice up our knowledge!!

Turmeric :

  • Acts as a pit and fissure sealant (forms a mechanical barrier between tooth and oral environment).
  • It also detects the plaque adhered to the tooth surface.
  • Applying a paste made from 1 TSP of turmeric with 1/2 tsp of salt and 1/2 tsp of mustard oil provides relief from gingivitis and periodontitis.

Ginger :

  • As a sialogogue to promote salivation.
  • For treatment of toothache and gingivitis.
  • Ginger extracts can be used in treatment of oral candidiasis (ethanol extract of ginger was effective on Candida albicans at concentrations of 1:5).
  • It has antimicrobial effect against Lactobacillus & to an extent against Streptococcus mutans.

Black pepper :

  • For treatment of oral abscesses, tooth decay and tooth aches.
  • Brushing with a herbal toothpaste containing black pepper showed a significant reduction in the gingival bleeding, salivary anaerobic bacteria count and overall improvement in oral hygiene.

Cardamom :

  • To treat infection of teeth and gums.
  • The extract of cardamom exhibits broad spectrum antimicrobial activity against Streptococcus mutans, Propionibacterium, Pytyriosporum ovale, Trichophyton mentagrophytes, microorganisms that cause dental caries, acne, dandruff.

Cinnamon :

  • It possesses a strong anti-candidal effect at concentrations of 25 to 50 mg/l.
  • It also increases the salivary pH and flow.
  • Studies also showed that it has high activity against Streptococcus mutans and decreased the viable count.

Clove :

  • Extract of clove inhibits the growth of periodontal oral pathogens, including Porphyromonas gingivalis & Prevotella intermedia.
  • Eugenol has a scavenging effect – helps to prevent cell and tissue damage that could lead to disease, also acts as an enzyme activator and this property is effectively used in treating toothaches.

Fenugreek :

  • Astringent, demulcent, carminative, stomachic, diuretic, emmenagogue, emollient, expectorant
  • An infusion of Fenugreek leaves is used as gargle for recurrent mouth ulcers.

Nutmeg :

  • Routine teeth cleaning with Jaiphal powder benefits dental and gum problems.
  • It has an effect on different types of oral sores and anti-inflammatory activity and antimicrobial properties.
  • It can be incorporated in floss, wedges and root canal irrigants.

Corriander seeds :

  • It shows anti-cariogenic property
  • These seeds increase the pH of the saliva which, in turn, will counteract the effect of the acids produced by bacteria and this neutralize them.
  • It is effective against Bacillus cereus.

Holy basil :

  • Useful in pyorrhea and other gum disorders.
  • Chewing its leaves helps clear ulcers and infections of the mouth.
  • As a mouthwash, it is useful against bad breath and for maintaining healthy gums.

Rosemary :

  • Has power to inhibit the formation of dental biofilm by reducing the adherence of pathogens to dental surfaces, thereby avoiding the pathologies caused by it’s formation.

Herbs such as green tea (prevents dental caries, gum diseases and also prevents halitosis), neem (antimicrobial, antioxidant, prevents dental caries and oral infections), sage (antibacterial,antiviral, antifungal), thyme (antiseptic,antifungal) and peppermint leaf (in low concentrations produces cooling sensation, in higher concentrations produces local anaesthesia and irritation; chewing leaf makes a very effective reliever to dental pain) also get added to the list of those help in maintaining dental hygiene.

Source : ncbi.nlm.nih.gov

Botulinum toxin

  • Botulinum toxin also called “miracle poison” is one of the most poisonous biological substances known. It is a neurotoxin produced by bacterium Clostridium botulinum.
  • Cl. botulinum elaborates eight antigenically distinguishable exotoxins (A,B,C1,C2,D,EF&G). Type A is the most potent toxin followed by types B and F.

How does Botox work?

Intramuscular administration of botulinum toxin acts at neuromuscular junction to cause muscle paralysis by inhibiting the release of acetylcholine from presynaptic motor neurons. Botulinum toxin acts at four different sites in the body : The neuromuscular junction, autonomic ganglia, postganglionic parasympathetic nerve endings and postganglionic sympathetic nerve endings that release acetylcholine.

Applications of botulinum toxin in maxillofacial region :

Cosmetic applications :

  • Facial wrinkles : forehead rhitids are managed by injecting 10-20 U of BTA injected at least 1cm above the orbital rim
  • Lateral canthal lines known as “crow’s feet” are generally managed by superficial injections of 8-16 U of BTA into lateral orbicularis oculi.
  • Eyebrow lift can be managed by BTA injections.

Temporalis and masseter muscle hypertrophy : This hypertrophy is generally associated with clenching or other parafunctional use of the jaws. The results of BT use in such cases appears to be effective in treating chronic facial pain associated with masticatory hyperactivity.

Lip flip : fast and easy procedure that takes just 30 minutes, leaving lips looking full and soft. Botox injections around the lips relax those muscles, allowing the lip to roll slightly outward. This reveals more of the lip surface, making them look larger

Gummy smile : Botox is injected in the area between upper lip and nose to temporarily freeze the muscles that contract or elevate smile which allows to smile without showing gums.

Dropping corners of the mouth : Hyperactivity of depressor anguli oris can lead to dropping of the corner of the mouth. The site of injection is on the trajectory of nasolabial fold to the jaw line.

Therapeutic applications :

  • Temporomandibular disorders (TMD) : TMDs may be myofascial (those related to muscles themselves) or arthrogenic (those related to TMJ). BTA has been found to be effective in resolving pain and tenderness in TMDs. The diverse group of TMDs those likely to be benefited by injection of BT includes : bruxism and clenching, OMDs, myofascial pain, trismus, headaches, hypermobility
  • Sialorrhea and salivary secretory disorders : injection of BTA into the parotid and submandibular glands is effective in controlling drooling. BTA injections have also been shown to be effective in managing gustatory sweating (Frey’s syndrome)
  • Implantology – BT has been postulated to be therapeutically beneficial by allowing unimpeded osseointegration of implants. Stress due to any excessive functional force or any parafunctional habit may cause implant failure. Thus injecting BTA relaxes the masticatory muscles, sparing the implant leading to unimpeded osseointegration.
  • Denture wearers : BTA is usedin patients struggling in getting used to a new set of dentures due to irregular and uncoordinated muscle activity, especially who have been edentulous for a long period of time by providing muscle relaxation.
  • Adjunct to orthodontic treatment and to prevent relapse : in some cases, relapse following an orthodontic correction may occur in patients with strong muscle activity such as that of mentalis muscle. BTA can be used during treatment to reduce the intensity of muscle contractions and muscles can be slowly & gradually trained post treatment to a more physiologic movement.

Source : ncbi.nlm.nih.gov

Emprethin and tooth jwellery

Lumineers : also called Da Vinci veneers, emprethin, empress veneers are thin porcelain material, custom made for the patient and applied with a permanent bonding agent to the tooth.

Main difference between conventional veneers and Lumineers is very thin thickness of Lumineers, like ultra thin and material of construction which is called cerinate porcelain which is very strong one and much thinner than the traditional veneers. Their thickness is comparable to contact lenses.

Advantages :

  • Painless
  • Conservation of tooth structure as very little enamel is removed
  • Elimination of post operative sensitivity
  • Ease of impression
  • Bonding to enamel
  • Longer lasting restoration due to enamel bonding
  • Higher level of acceptance by patients
  • Easy to clean and maintain

Disadvantages :

  • Bulky apperance
  • Periodontal problems due to over contouring of the veneers
  • Difficult to mask severe staining and discoloration with thin veneers.
  • Teeth width being restored cannot be altered significantly.

Indications :

  • Minor color changes
  • Masking mild to moderate tooth discoloration. Eg: enamel hypoplasia, enamel hypocalcification, tetracycline staining, teeth with enamel malformations
  • Closing diastemas
  • Restoring chipped or cracked teeth
  • Reshaping peg shaped and undersized teeth
  • Correcting minor misalignments and rotations of anterior teeth
  • Worn and adolescent dentition

Contraindications :

  • Severe discolorations or darkly stained teeth
  • Protruding teeth or crowding that will require some reduction to achieve better esthetics
  • If teeth are significantly broken down or compromised
  • Large class IV defects

Lumineers need no tooth structure removal, thus bonded directly on the tooth surface (minimally invasive technique). Lumineers bind directly to the surface tooth making it a conservative cosmetic approach. They are very durable, 10 years or longer with good oral hygiene.

Tooth jwellery : it is an adornment that is set on the labial aspect of the teeth. A little diamond or precious metal appeal can be bonded to a tooth and it can either be there temporarily or can be kept going as long as one needs it.

A tooth jwellery applied on a natural tooth will absolutely continue to remain for 6 months upto a couple of years. These are just 0.4 mm or 0.9 mm thick and 1.8 mm to 3 mm wide, hence patient gets used to this new addition in a couple of days after the application. The presence of jewel won’t have any effect on routine dental cleanliness and hygiene measures.

Source : topnotchdentalclinic.com

Dentophysics (Part – 3)

Optical properties :

Colour : the colour of dental restorative materials is most commonly measured in reflected light using a colour measuring instrument or a visual method.

Colour measuring instruments

  • Spectrophotometers are amongst the most accurate, useful and flexible instruments for overall colour matching in dentistry. They measure the amount of light energy reflected from an object at 1-25 nm intervals along the visible spectrum
  • Colorimeters measure tristimulus (relating to values giving the amounts of the three colored lights red, green and blue that when combined additively produce a match for the colour being considered) values and filter light in red, green and blue areas of the visible spectrum.

Visual method : A popular system for the visual determination of colour is the Munsell colour system. A large set of colour tabs is used to determine the colour.

  • Value (lightness) is determined first by selection of a tab that most nearly corresponds with the lightness or darkness of the colour.
  • Chroma is determined next with tabs that are close to the measured value but are of increasing saturation of colour.
  • The hue of the colour is determined last by matching with colour tabs of the value and chroma already determined.

Transparence, translucence and opacity:

Opacity is the property of the materials that prevents the passage of light. Translucency is the property of substances that permits the passage of light but disperses the light, so objects cannot be seen through the material. Some translucent materials in dentistry are ceramics, resin composites and acrylics. Transparent materials allow the passage of light so little distortion takes place and objects may be clearly seen through them.

Teeth and oral tissue are translucent and allow passage of some of the incident light. In some individuals, the enamel may be translucent or in rare circumstances transparent.

Flourescence : It is the emission of luminous energy by a material when a beam of light is shone on it. The wavelength of the emitted light is usually longer than that of exciting radiation.

Generally, natural tooth structure also absorbs light of wavelengths which are too short to be visible to the human eye. The energy that the tooth absorbs is converted to light with larger wavelengths in which case the tooth actually becomes a light source. This phenomenon is called flourescence.

In UV light a natural tooth emits a weak whitish-blue flourescence. This should be taking into account when selecting restoratives. If restorative material do not offer this property, they will look dark in UV light and the restored tooth will stand out against the other teeth in the mouth eg. in some stage shows and discotheques.

Metamerism : The appearance of an object depends on the type of light by which the object is viewed. Objects that appear to be colour matched under one type of light may appear very different under another light source. This phenomenon is called metamerism. Hence, selecting a shade of tooth must be done under two different sources of light.

Radiological properties :

Radiopacity may be defined as the quality of a material to obstruct the passage of radiant energy, such as X rays. Thus the materials that inhibit the passage of electromagnetic radiation are called radiopaque. Those that allow radiation to pass more freely are called radiolucent.

Manufacturers add certain elements in many dental materials in order to make them radiopaque. Commonly used elements are heavy metal glasses and metal oxides (zirconium dioxide and ytterbium oxide). Pure polymers like acrylic resins and BISGMA are radiolucent. Composites, ceramics and metals are radiopaque, with metals showing the highest radiopacity. Within the tooth, enamel is more radiopaque than dentin. If the radiopacity of a material is too low, it will not be visible. Generally, a restorative material should have radiopacity slightly greater than that of enamel in order to present a contrast. Radiopacity increases with increase in thickness of a material. Aluminum is used as a standard to measure radiopacity.

Use of magnets in dentistry : they have been used for various applications in orthodontics and prosthodontics. They can be placed within prostheses without being obtrusive.

  • In orthodontics : their main use has been for tooth movement
  • In prosthodontics : they are primarily used as retentive aids in maxillofacial prosthesis and in tooth and implant supported.

source : craig’s and manapalli textbook of restorative materials

Odontogenic infection

Odontogenic infection is an infection that originates within a tooth or in the closely surrounding tissues. The term is derived from Greek words “odonto” meaning “tooth” and “genic” meaning “birth”.

Odontogenic infection has plagued human kkind for as long as the human species has existed. Generally, in the orofacial region, most bacterial infections involve either a disturbance of normal flora or a displacement of the normal organisms to the site, where they are usually not seen.

Routes of odontogenic infection :

  • By direct continuity through tissues
  • By lymphatics to the regional nodes
  • By bloodstream

Causes of odontogenic infection :

  1. Dental caries : plaque on tooth surface above the gingival margin consists of acidogenic and aciduric bacteria which cause dental caries and may invade the pulp, infection eventually spreading to the alveolar process.
  2. Deep fillings : if the seal between the tooth enamel and the filling breaks down, food particles and decay causing bacteria can work their way under the filling. Additional decay develops in the tooth. Decay that is left untreated can progress to infect the dental pulp and may cause an abscessed tooth.
  3. Failed root canal treatment : if there is an extended delay between root canal procedure and crown placement, bacteria can re-enter the tooth. Additionally, a crown can suffer a crack or other damage long after the procedure is complete. This damage allows new bacteria to enter the tooth and create decay.
  4. Pericoronitis and periodontal diseases

Odontogenic infections are usually polymicrobial involving both strict anaerobes and facultative bacteria within unique ecosystems of the dental plaque and gingival crevice.

The most prevalent anaerobic bacteria include gram positive cocci such as Peptostreptococcus sp., and gram negative rods such as Bacterioids sp., Fusobacterium sp. The most prevalent aerobes are facultative gram positive such as Streptococcus mutans and Streptococcus viridans. Facultative gram negative bacilli and Staphylococcus aureus are uncommon in immunocompetent hosts but may be more important in immunocompromised patients.

Major symptoms of odontogenic infections :

  • Antecedent toothache
  • Facial swelling and pain
  • Fever and chill
  • Halitosis
  • Bleeding gums with minor trauma

Prominent physical findings include :

  • Dental plaques, tooth decay, gingivitis or periodontal pockets
  • Facial or neck swelling and tenderness
  • Inability to open the jaw
  • Difficulty in swallowing
  • Dyspnea with inspiratory stridor (high pitched wheezing sound caused by disrupted airflow)

Imaging studies :

  • Orthopantomogram or AP radiograph of teeth to assess periapical abscess or advanced periodontal disease
  • CT of face and neck to assess source and extension of orofacial space infection

Complications :

  • Deep facial space infections
  • Osteomyelitis of the jaws
  • Cavernous sinus thrombosis
  • Hematogenous dissemination
  • Association of poor health with cardiovascular diseases

Clinical manifestations of specific odontogenic orofacial space infections :

  • If pus perforates through either the maxillary or mandibular buccal plate inside the attachment of the buccinator muscle, infection will be intraoral; if the perforation is outside this muscle attachment, infection will be extraoral
  • When a mandibular infection perforates lingually, it presents in the sublingual space if the apices of the involved teeth lie above the attachment of the mylohyoid muscle.
  • Other superficial odontogenic orofacial space infection include the buccal, submental, masticator, canine and infratemporal spaces.

Treatment :

In normal host :

  • Penicillin G + metronidazole
  • Ampicillin – sulbactam
  • Clindamycin
  • Doxycycline
  • Moxifloxacin

In immunocompromised host :

  • Cefotaxime or ceftrioxime or cefepime each + metronidazole

Source : ncbi.nlm.nih.gov

Aneurysm

Aneurysm is one of the most common words we see in our pathology books. Every year in India, around 76,000-200,000 cases of cerebral aneurysms are reported to have occurred. An estimated 6.5 million people in the United States have an unruptured brain aneurysm, or 1 in 50 people. The Centre for Disease Control and Prevention (CDC) states that aortic aneurysms contribute to over 25,000 deaths each year in United States. Let’s see what the word actually means and it’s related causes.

The word “aneurysm” comes from the Greek word “aneurysma” meaning “a widening”.

An aneurysm refers to a weakening of an artery wall that creates a bulge, or distension of the artery.

Types of aneurysms :

Aneurysms are classified by their location in the body. The arteries of the brain and the heart are the two most common sites of a serious aneurysm.

The bulge can take two main shapes:

  • Fusiform aneurysms bulge all sides of a blood vessel
  • Saccular aneurysms bulge only on one side

Aortic aneurysm : the aorta is the large artery that begins at the left ventricle of the heart and passes through the chest and abdominal cavities. The most common aneurysm of the aorta is an abdominal aortic aneurysm (AAA). Less commonly, a thoracic aortic aneurysm (TAA) can affect the part of aorta running through the chest.

Cerebral aneurysm : aneurysms of the arteries that supply the brain with blood are known as intracranial aneurysms. Ruptured cerebral aneurysms are the most common cause of a type of stroke known as “subarachnoid hemorrhage”.

Peripheral aneurysm : an aneurysm can also occur in a peripheral artery. Peripheral arteries are less likely to rupture than aortic aneurysms. Types of peripheral aneurysm include:

  • Popliteal aneurysm : this happens behind the knee. It is the most common peripheral aneurysm
  • Splenic artery aneurysm : this type of aneurysm occurs near the spleen
  • Mesenteric artery aneurysm : this affects the artery that transports blood to intestines
  • Femoral artery aneurysm : the femoral artery is in the groin
  • Carotid artery aneurysm : this occurs in the neck
  • Visceral aneurysm : this is the bulge of arteries that supply blood to the bowel or kidneys

Cause of aneurysm : aortic dissection is one identifiable cause of an aortic aneurysm. The arterial wall has three layers. Blood can burst through a tear in the weakened wall of the artery, splitting these layers. It can then fill the cavity surrounding the heart. Dissection leads to compression. Compression prevents blood from returning to the heart. This is also known as a pericardial tamponade.

Risk factors : smoking tobacco, hypertension or high blood pressure, poor diet, inactive lifestyle, obesity

Symptoms : most aneurysms are clinically silent. Symptoms donot usually occur unless an aneurysm ruptures. Rapidly growing abdominal aneurysms are sometimes associated with symptoms. Some people with abdominal aneurysms report abdominal pain, lower back pain, or a pulsating sensation in the abdomen. Similarly, thoracic aneurysms can affect nearby nerves and other blood vessels causing swallowing and breathing difficulties, and pain in the jaw, chest and upper back.

Complications : thromboembolism, severe chest or back pain, angina, a sudden extreme headache

Diagnosis : an MRI scan can identify an aneurysm that has not yet ruptured. CT scans are usually preferred for ruptured aneurysms

Treatment : a ruptured aneurysm needs emergency surgery. Without immediate repair, patients have a low chance of survival.

A large or growing aortic aneurysm is more likely to need surgery. There are two options for surgery

  • Open surgery to fit a synthetic or stent graft
  • Endovascular stent graft surgery

In the Endovascular surgery, the surgeon accesses the blood vessels through a small incision near the hip. Stent graft surgery inserts an endovascular graft through this incision through a catheter. The graft is then positioned in the aorta to seal off the aneurysm.

In the open AAA repair, a large incision is made in the abdomen to expose the aorta. A graft can then be applied to repair the aneurysm.

Source : medicalnewstoday.com

Dentophysics (part 2)

Thermal properties

The arrangement of atoms and molecules in materials is influenced by the temperature; as a result, thermal techniques are important in understanding the properties of dental materials

Thermal conductivity : thermal conductivity of a substance is the quantity of heat in calories or joules per second passing through a body 1cm thick with a cross section of 1 sq.cm when the temperature difference is 1°C.

Eg – a large amalgam filling or gold crown in proximity to the pulp may cause the patient discomfort when hot or cold foods produce temperature changes, this effect is mitigated when adequate tooth tissue remains or cavity liners are placed between the tooth and filling for insulation.

Specific heat : specific heat of a substance is the quantity of heat needed to raise the temperature of 1g of the substance by 1°C.

Eg – during the melting and casting process, the specific heat of the metal or alloy is important because of the total amount of heat that must be applied to the mass to raise the temperature to the melting point.

Thermal diffusivity : it is a measure of transient heat flow and is defined as the thermal conductivity, divided by the product of the specific heat, times the density.

Eg- for a gold crown or a dental amalgam, the low specific heat combined with the high thermal conductivity creates a thermal shock more readily than normal tooth structure does.

Coefficient of thermal expansion : the change in length per unit length of a material for a 1°C change in temperature is called the linear coefficient of thermal expansion.

Although the coefficient is a material constant, it doesn’t remain constant over wide temperature ranges. For eg, the linear coefficient of thermal expansion of a dental wax may be an average value of 300×10-6/°C upto 40°C, whereas it may have an average value of 500×10-6/°C from 40-50°C.

The coefficient of thermal expansion of a polymer changes as the polymer goes from a glassy state to a softer, rubbery material. This change in the coefficient corresponds to the glass transition temperature.

It is obvious that with the reduction in temperature, there is a contraction of a substance as much as of expansion tht occured during heating. Accordingly, tooth structure and restortive materials expand when warmed by hot food or beverages and contract when exposed to cold substances. Such expansions and contractions may break the marginal seal of a filling in tooth particularly when the difference between coefficient of thermal expansion of tooth and restorative material is too large.

Electrical properties

The ability of a material to conduct an electric current may be stated as conductivity or conversely as the specific resistance or resistivity. The conductivity by materials used to replace tooth tissues is of concern in restorative dentistry.

Dielectric constant : a material that provides electrical insulation is known as dielectric. The dielectric constant of a dental cement generally decreases as the material hardens. This decrease reflects a change from a paste that is relatively ionic and polar to one that is less.

Electromotive force : the electromotive series is a listing of electrode potentials of metals according to the order of their decreasing tendency to oxidise in solution. Those metals with a large negative electrode potential are more resistant to tarnish than those with a high positive electrode potential.

Galvanism : the presence of metallic restorations in the mouth may cause a phenomenon called galvnic action where saliva or bone fluids like electrolytes make up an electric cell.

Corrosion : the corrosion of gamma, gamma 1, gamma 2 phases in amalgam has been studied by electrochemical analysis. The dental amalgam specimens become pitted at the boundaries between the phases or in gamma 2 phase. The addition of copper to amalgam alloys to form copper-tin compounds during hardening has improved the resistance of amalgam to chloride and galvanic corrosion.

Tarnish : the process of steam sterilization of surgical instruments has long presented a serious problem of tenish and corrosion. Many non metallic materials such as cements and composites have shown a tendency to discolor in service because the colored substances penetrate the materials and continue chemical reactions in the composites.

Source : Craig’s textbook of restorative materials