Dental Anatomy and Terminology

Anatomy of the tooth and surrounding tissues

Enamel: This is the hard, calcified substance that makes the surface of a crown of a tooth.

Dentin: This is the calcified tissue that forms the major part of a tooth. In the crown of the tooth, the dentine is covered by enamel. The pulp
chamber of the tooth is surrounded by dentine.

Pulp: This is the organ at the centre of a tooth that contains blood vessels, connective and neural tissue, and cells that produce dentine-odontoblast. Blood vessels and neural tissue enter the tooth from the apex of the root.

Gingiva: This is the marginal part of the gum that surrounds the tooth where it emerges from the deeper, supporting tissues.

Periodontal ligament: This is the ligament that connects a tooth, by its root, to the supporting bone.

Cementum: This is the calcified tissue on the surface of the root of a tooth, which provides attachment for the periodontal ligament.

Fissure: It is a naturally occurring crevice in the enamel.

Crown: This is the part of the tooth that is visible and is above the gingival margin.

Root: This is the part of the tooth below the gingival margin; it is connected through cementum on its surface and the fibres of the periodontal ligament to the supporting bone.

Dental numbering system

There are numerous dental numbering systems to identify teeth and their maturity. The most commonly used system in Australia is the Federation Dentaire Internationale (FDI) system (see Figures). When communicating with a dentist, identify which numbering system is being used.

The FDI numbering system divides the mouth into quadrants. The first number indicates the quadrant and whether it is a primary or secondary tooth. The second number indicates the tooth; tooth numbering begins at the central incisor and counts backward to the molars.

Using the FDI numbering system, for adults, the quadrants are numbered as:

1. patient’s upper right is quadrant 1 
2. patient’s upper left is quadrant 2 
3. patient’s lower left is quadrant 3 
4. patient’s lower right is quadrant 4

For primary teeth in children, the quadrants are numbered as:

1. patient’s upper right is quadrant 5 
2. patient’s upper left is quadrant 6 
3. patient’s lower left is quadrant 7 
4. patient’s lower right is quadrant 8

Quick MCQ Test: 

Upcoming (Please check regularly to avail Free MCQ).

Ref: Therapeutic Guidelines 2019

Face bow

Face bow-for Whip mix Arcon articulator

Face bow is a device that is used to transfer the relationship of upper jaw to the temporomandibular joint and the skull. The use of face bow are as follows:

1. in full mouth rehabilitation
2. when you want to give accurate crown and bridges 
3. when you need to alter VDO
4.  for diagnostic mounting
5. for the correction of the occlusion
6.  when you want to use inter-occlusal records except when you are making tooth supported prosthesis or a single tooth restoration
7.  when you are using cusp form teeth
8.  when you need balanced occlusion
9. when you want to do a gnathological study

Face bow for Hanau Non-Arcon Articulator

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Dens in Dente

Dens invaginatus, dens in dente or tooth with in a tooth is a rare developmental anomaly. In it, the lingual pit is extended deep in to the crown or root, in later instance causing pulpitis. It is mostly seen in the maxillary lateral incisors but may be found in any anterior tooth.

Dens in Dente-lateral incisors

The cause of dens in dente in not known but role of genetic factor can not be established. In early stage, it can be treated by filling or endodontic treatment, if pulp is involved.

A. showing Type I Dens Invaginatus in lateral incisors. Note- periapical cyst. B. Type II dens invaginatus in second premolar and C. Type III dens invaginatus in mandibular canine. [1]

Ref: 

1. https://www.omicsonline.org/scientific-reports/srep147.php

Hypertension

The 2017 ACC/AHA guideline for high BP in adults provides four BP categories based on the average of two or more in-office readings on 2 or more occasions:

• Normal: Lower than 120 mm Hg systolic BP (SBP) and 80 mm Hg diastolic BP (DBP).
• Elevated: 120–129 mm Hg SBP and lower than 80 mm Hg DBP.
• Stage 1 hypertension: 130–139 mm Hg SBP or 80–89 mm Hg DBP.
• Stage 2 hypertension: Higher than or equal to 140 mm Hg SBP or 90 mm Hg DBP.

Ameloblastoma

Ameloblastoma is a rare head and neck tumor with an estimated annual incidence of 0.5 per million population. They constitute 1% of tumors and cysts involving the jaws and accounts for approximately 10% of the odontogenic tumors. Ameloblastomas are originated from the epithelial lining of odontogenic cysts, enamel organ or dental lamina, stratified epithelium of oral cavity or displaced epithelial remnants. They are primarily seen in adults during the third and fourth decade of life with no gender preference and more frequently located in the mandible (80%), especially in the angle and ascending ramus [1].

Even though they are benign and slow-growing lesions, ameloblastomas exhibit locally destructive behavior with a high recurrence rate. Thus, most relapses (50% and even over 80%) occur during the first 5 years after the primary surgery. The major contributing factor for recurrence seems to be the inadequate initial surgical procedure rather than the histological type [1].

Radiographic Features

Radiographically, ameloblastoma typically forms round, cyst-like, radiolucent area with well-defined margins. The smallest lesions appear unilocular; whereas larger ameloblastoma may comprise a few large clustered cysts, giving 'soap-bubble’ or 'multilocular appearance' or  ‘honeycomb’ appearance (Fig 1) Expansion of the lesion may be on both, lingual and buccal side.

Fig. 1. Ameloblastoma: multilocular appearance

Differential Diagnosis

Other multilocular lesions that may mimic ameloblastoma radiologically include odontogenic keratocyst, giant-cell granuloma and odontogenic myxoma. Ameloblastoma with a single bony cavity simulate many types of cyst and tumour radiographically.

Treatment

The surgical options for ameloblastoma vary from simple enucleation (with or without bony curettage) to radical excision.

Ref: 

1. Medina A, Velasco Martinez I, McIntyre B, Chandran R. Ameloblastoma: clinical presentation, multidisciplinary management and outcome. Case Reports Plast Surg Hand Surg. 2021;8(1):27-36. Published 2021 Feb 22. doi:10.1080/23320885.2021.1886854

Supernumerary Teeth

Extra numbers of teeth are known as supernumerary teeth. When they are present in the anterior maxilla in midline, they are known as mesiodens. When the extra teeth are present in the molar region as fourth molar, they are known as paramolar teeth. The anterior midline of the maxilla is the most common site whereas the maxillary molar area is the second most common site for supernumerary teeth.

Supernumerary tooth-mesiodens in anterior mandible in midline [1]

Radiograph showing mesiodens in anterior maxilla [1]

The investigation involves routine blood examination and IOPA or OPG radiographs. Depending on the anticipated level of difficulty of the surgery, additional investigations may be advised.

Treatment involves surgical extraction.

Ref:

1. Oral pathology clinical pathologic correlation, Regezi, Sciubba, Jordan 4th Ed Saunders

Oral Candidiasis

Oral candidiasis is a fungal disease that is caused by Candida albicans. It looks like a white  or creamy plaque or patch that can be wiped off with the help of a cotton swab or a tooth brush leaving a red base.

Gingival thrush

It occurs due to disturbance in the oral microflora due to antibiotics, corticosteroid, Xerostomia , immune defects especially in HIV infection, immunosuppressant, leukaemia or lymphomas and diabetes. It rarely occurs in a healthy individuals except in neonates.

Chronic mucocutaneous candidosis: note the wide adherent plaque.

Gram stain smear shows the Candida albicans hyphae. It should be differentiated from Koplik's spot or Fordyce's granules.

The treatment involves treating the cause. Antifungal agents, for example, nystatin oral suspension or pastilles, amphotericin lozenges, or miconazole gel or tablets or fluconazole tablets can be given.

Ref:

1. Oral diseases 2nd Ed. Crispian Scully, Roderick A. Cawson Churchill Livingstone

Malocclusion

MALOCCLUSION

Proposed by Edward H. Angle in 1890, the Angle Classifications are based on the relationship of the buccal groove of the mandibular first permanent molar and the mesiobuccal cusp of the maxillary first permanent molar. This classification is considered to be one of the most commonly used as its easy to use.

Bleeding Disorder

 Bleeding disorders: dental considerations

Acquired or congenital bleeding disorders of dental treatment concern include haemophilia, von Willebrand disease, other factor deficiencies and thrombocytopenia. Some systemic conditions also interfere with haemostasis, such as kidney, liver and bone marrow disorders.

Patients with bleeding disorders should be managed in a specialist setting, with appropriate consultation with the patient’s specialist or multidisciplinary team.

Bleeding Disorders

1. haemophilia

2. von Willebrand disease

3. Other factor deficiencies 

4. thrombocytopenia

Causes

Bleeding disorder may be due to defect in platelet activation, function and contact activation.  It may also be due to defect in clotting proteins or antithrombin function. 

The commonest caused of bleeding disorder are 

1. warfarin
2. von Willebrand disease

3. aspirin

Warfarin is the commonest anticoagulant that interferes by preventing the production of clotting factors by blocking vitamin K.

von Willebrand disease is the most common inherited bleeding disorder.

Aspirin is the less commonly used drug for pain and more used in long term for its impairing ability for platelet function. One tablet of aspirin renders the platelet non-functional for almost one week. It is to be noted that it rarely causes significant post-operative bleeding.

How to confirm bleeding disorder of a patient

The single most important evaluation part is an adequate history since screening tests for bleeding disorders do not always detect mild defects. A history suggestive of a bleeding tendency must be taken seriously. History of previous dental extraction or tonsillectomy provide a useful guide. Physical examination is also necessary and for conformation of diagnosis, laboratory test are needed.

An accurate diagnosis is essential for replacement therapy, if needed and enable other management protocols to be followed.

The dentist must place special emphasis on the following that are suggestive of bleeding disorder:

1. deep haemorrhage into  muscles, joints or skin (bruising)-suggests a clotting defect
2. bleeding from or into skin or mucosae-suggests purpura
3. most congenital bleeding disorders of significance become apparent in childhood
4. however, mild haemophilia might escape the history part until the adult life if the child and the parents have managed well and avoided the injuries. A mild haemophiliac might give a history of mild oozing from an extraction socket for 2-3 weeks despite all local measures such as pressure pack and suturing etc
5. history of blood transfusion or hospitalization might clearly give the idea of bleeding disorder in the same as a history of bleeding in a blood relative
6. history of drugs such as anticoagulant, certain herbal products, systemic disease, for example, cirrhosis, HIV and kidney diseases can also impair platelet function 

Congestive Heart Failure

Congestive heart failure or heart failure occurs when the heart muscle weakens and doesn't pump enough blood as it should. When this happens, blood often backs up and fluid can build up in the lungs, causing shortness of breath.

Certain heart conditions, for example, coronary artery disease or high blood pressure, gradually leave the heart too weak or stiff to fill and pump blood properly. 

Signs and symptoms of congestive heart failure 

• Shortness of breath with activity or when lying down
• Fatigue and weakness
• Swelling in the legs, ankles and feet
• Rapid or irregular heartbeat
• Reduced ability to exercise
• Persistent cough or wheezing with white or pink blood-tinged mucus
• Swelling of the belly area (abdomen)
• Very rapid weight gain from fluid build-up
• Nausea and lack of appetite
• Difficulty concentrating or decreased alertness
• Chest pain if heart failure is caused by a heart attack