NEET MDS Synopsis
Classification of Cementum
PeriodontologyClassification of Cementum According to Schroeder
Cementum is a specialized calcified tissue that covers the roots of teeth and
plays a crucial role in periodontal health. According to Schroeder, cementum can
be classified into several distinct types based on its cellular composition and
structural characteristics. Understanding these classifications is essential for
dental professionals in diagnosing and treating periodontal conditions.
Classification of Cementum
Acellular Afibrillar Cementum:
Characteristics:
Contains neither cells nor collagen fibers.
Present in the coronal region of the tooth.
Thickness ranges from 1 µm to 15 µm.
Function:
This type of cementum is thought to play a role in the
attachment of the gingiva to the tooth surface.
Acellular Extrinsic Fiber Cementum:
Characteristics:
Lacks cells but contains closely packed bundles of Sharpey’s
fibers, which are collagen fibers that anchor the cementum to the
periodontal ligament.
Typically found in the cervical third of the roots.
Thickness ranges from 30 µm to 230 µm.
Function:
Provides strong attachment of the periodontal ligament to the
tooth, contributing to the stability of the tooth in its socket.
Cellular Mixed Stratified Cementum:
Characteristics:
Contains both extrinsic and intrinsic fibers and may contain
cells.
Found in the apical third of the roots, at the apices, and in
furcation areas.
Thickness ranges from 100 µm to 1000 µm.
Function:
This type of cementum is involved in the repair and adaptation
of the tooth root, especially in response to functional demands and
periodontal disease.
Cellular Intrinsic Fiber Cementum:
Characteristics:
Contains cells but no extrinsic collagen fibers.
Primarily fills resorption lacunae, which are areas where
cementum has been resorbed.
Function:
Plays a role in the repair of cementum and may be involved in
the response to periodontal disease.
Intermediate Cementum:
Characteristics:
A poorly defined zone located near the cementoenamel junction
(CEJ) of certain teeth.
Appears to contain cellular remnants of the Hertwig's epithelial
root sheath (HERS) embedded in a calcified ground substance.
Function:
Its exact role is not fully understood, but it may be involved
in the transition between enamel and cementum.
Clinical Significance
Importance of Cementum:
Understanding the different types of cementum is crucial for
diagnosing periodontal diseases and planning treatment strategies.
The presence of various types of cementum can influence the response
of periodontal tissues to disease and trauma.
Cementum in Periodontal Disease:
Changes in the thickness and composition of cementum can occur in
response to periodontal disease, affecting tooth stability and
attachment.
NEOPLASIA
General Pathology
NEOPLASIA
An abnormal. growth, in excess of and uncoordinated with normal tissues Which persists in the same excessive manner after cessation of the stimuli which evoked the change.
Tumours are broadly divided by their behaviors into 2 main groups, benign and malignant.
Features
Benign
Malignant
General
Rate of growth
Mode of growth
Slow
Expansile
Rapid
Infiltrative
Gross
Margins
Haemoeehage
Circumscribed often Encapsulated
Rare
III defined
Common
Microscopic
Arrangement
Cells
Nucleus
Mitosis
Resemble Parent Tissues
Regular and uniform in shape and size
Resembles parent Cells
Absent or scanty
Varying degrees of structural differentiation
Cellular pleomorphism
Hyper chromatic large and varying in shape and size
Numerous and abnormal
Through most tumours can be classified in the benign or malignant category . Some exhibits an intermediate behaviours.
CLASSIFICATION
Origin
Benign
Malignant
Epithelial
Surface epithelium
Glandular epithelium
Melanocytes
Papilloma
Adenoma
Naevus
Carcinoma
Adenoca cinoma
Melanocarcinoma(Melanoma)
Mesenchymal
Adipose tissue
Fibrous tissue
Smooth tissue
Striated muscle
Cartilage
Bone
Blood vessels
Lymphoid tissue
Lipoma
Fibroma
Leiomyoma
Rhabdomyoma
Chondroma
Osteoma
Angioma
Liposarcoma
Fibrosarcoma
Leimyosarcoma
Chondrosarcoma
Osteosarcoma
Angiosarcoma
Lymphoma
Some tumours can not be clearly categorized in the above table e.g.
Mixed tumours like fibroadenoma of the breast which is a neoplastic proliferation of both epithelial and mesenchmal tissues.
Teratomas which are tumours from germ cells (in the glands) and totipotent cells
(in extra gonodal sites like mediastinun, retroperitoneum and presacral region). These are composed of multiple tissues indicative of differentiation into the derivatives of the three germinal layers.
Hamartomas which are malformations consisting of a haphazard mass of tissue normally present at that site.
EMBOLISM
General Pathology
EMBOLISM
Definition: transportation of an abnormal mass of an abnormal mass of undissolved material from one part of circulation to another. The mass transported is called embolus.
Types
I .Thrombi and clots.
2. Gas or air.
3. Fat
4.Amniotic fluid.
5.Tumour
Thromboembolism
This is the commonest type of embolus and may be formed of the primary thrombus or more often of propagated clot region which is loosely attached.
Emboli from venous thrombi can result In impaction in the pulmonary arteries and result in sudden death.
Embolism from cardiac or arterial thrombi results in systemic embolism causing infraction and gangrene.
Gaseous
This occurs when gas is introduced into the circulation:
• Accidental opening of large veins during surgery.
• Mismanaged transfusion. .
As air is readily absorbed into blood only sudden introduction or large quantities of air produces effects
Caisson’s Disease bubbling of nitrogen from the blood during sudden decompression as seen during deep sea diving.
Fat Embolism
Causes
• Fractures especially of long bones and multiple
• Crush injuries.
Sites of impaction:
o Lungs.
o Systemic: causing -
→ petechial skin haemorrhages.
→ Embolism to brain leading to coma and death.
→ Conjunctival and retinal haemorrhages
Tumor Embolism.
Invasion of vascular channe1.s is a feature of malignant neoplasms and this leads to:
• Metastatic deposits,
• DlC
Desquamative Gingivitis
PeriodontologyDesquamative Gingivitis
Characteristics: Desquamative gingivitis is
characterized by intense erythema, desquamation, and ulceration of both free
and attached gingiva.
Associated Diseases:
Lichen Planus
Pemphigus
Pemphigoid
Linear IgA Disease
Chronic Ulcerative Stomatitis
Epidermolysis Bullosa
Systemic Lupus Erythematosus (SLE)
Dermatitis Herpetiformis
Physiologic anatomy of the respiratory system
PhysiologyRespiration occurs in three steps :
1- Mechanical ventilation : inhaling and exhaling of air between lungs and atmosphere.
2- Gas exchange : between pulmonary alveoli and pulmonary capillaries.
3- Transport of gases from the lung to the peripheral tissues , and from the peripheral tissues back to blood .
These steps are well regulated by neural and chemical regulation.
Respiratory tract is subdivided into upper and lower respiratory tract. The upper respiratory tract involves , nose , oropharynx and nasopharynx , while the lower respiratory tract involves larynx , trachea , bronchi ,and lungs .
Nose fulfills three important functions which are :
1. warming of inhaled air .
b. filtration of air .
c. humidification of air .
Pharynx is a muscular tube , which forms a passageway for air and food .During swallowing the epiglottis closes the larynx and the bolus of food falls in the esophagus .
Larynx is a respiratory organ that connects pharynx with trachea . It is composed of many cartilages and muscles and
vocal cords . Its role in respiration is limited to being a conductive passageway for air .
Trachea is a tube composed of C shaped cartilage rings from anterior side, and of muscle (trachealis muscle ) from its posterior side.The rings prevent trachea from collapsing during the inspiration.
From the trachea the bronchi are branched into right and left bronchus ( primary bronchi) , which enter the lung .Then they repeatedly branch into secondary and tertiary bronchi and then into terminal and respiratory broncholes.There are about 23 branching levels from the right and left bronchi to the respiratory bronchioles , the first upper 17 branching are considered as a part of the conductive zones , while the lower 6 are considered to be respiratory zone.
The cartilaginous component decreases gradually from the trachea to the bronchioles . Bronchioles are totally composed of smooth muscles ( no cartilage) . With each branching the diameter of bronchi get smaller , the smallest diameter of respiratory passageways is that of respiratory bronchiole.
Lungs are evolved by pleura . Pleura is composed of two layers : visceral and parietal .
Between the two layers of pleura , there is a pleural cavity , filled with a fluid that decrease the friction between the visceral and parietal pleura.
Respiratory muscles : There are two group of respiratory muscles:
1. Inspiratory muscles : diaphragm and external intercostal muscle ( contract during quiet breathing ) , and accessory inspiratory muscles : scaleni , sternocleidomastoid , internal pectoral muscle , and others( contract during forceful inspiration).
2. Expiratory muscles : internal intercostal muscles , and abdominal muscles ( contract during forceful expiration)
Stationary Relationship
Dental Anatomy
Stationary Relationship
a) .Centric Relation is the most superior relationship of the condyle of the mandible to the articular fossa of the temporal bone as determined by the bones ligaments. and muscles of the temporomandibular joint; in an ideal dentition it is the same as centric occlusion.
(b) Canines may also be used to confirm the molar relationships to classify occlusion when molars are missing; a class I canine relationship shows the cusp tip of the maxillary canine facial to the mesiobuccal cusp of the first permanent molar
c) Second primary molars are used to classify the occlusion in a primary dentition
(d) In a mixed dentition the first permanent molars will erupt into a normal occlusion if there is a terminal step between the distal surfaces of maxillarv and mandibular second primary molars; if these surfaces are flush, a terminal plane exists and the first permanent molars will first erupt into an end-to-end relationship until there is a shifting of space or exfoliation of the second primary molar
Herpetic Gingivostomatitis
PedodonticsHerpetic Gingivostomatitis
Herpetic gingivostomatitis is an infection of the oral cavity caused by the
herpes simplex virus (HSV), primarily HSV type 1. It is characterized by
inflammation of the gingiva and oral mucosa, and it is most commonly seen in
children.
Etiology and Transmission
Causative Agent: Herpes simplex virus (HSV).
Transmission: The virus is communicated through
personal contact, particularly via saliva. Common routes include:
Direct contact with an infected individual.
Transmission from mother to child, especially during the neonatal
period.
Epidemiology
Prevalence: Studies indicate that antibodies to HSV are
present in 40-90% of individuals across different populations, suggesting
widespread exposure to the virus.
Age of Onset:
The incidence of primary herpes simplex infection increases after 6
months of age, peaking between 2 to 5 years.
Infants under 6 months are typically protected by maternal
antibodies.
Clinical Presentation
Incubation Period: 3 to 5 days following exposure to
the virus.
Symptoms:
General Symptoms: Fever, headache, malaise, and
oral pain.
Oral Symptoms:
Initial presentation includes acute herpetic gingivostomatitis,
with the gingiva appearing red, edematous, and inflamed.
After 1-2 days, small vesicles develop on the oral mucosa, which
subsequently rupture, leading to painful ulcers with diameters of
1-3 mm.
Course of the Disease
Self-Limiting Nature: The primary herpes simplex
infection is usually self-limiting, with recovery typically occurring within
10 days.
Complications: In severe cases, complications may
arise, necessitating hospitalization or antiviral treatment.
Treatment
Supportive Care:
Pain management with analgesics for fever and discomfort.
Ensuring adequate hydration through fluid intake.
Topical anesthetic ointments may be used to facilitate eating and
reduce pain.
Severe Cases:
Hospitalization may be required for severe symptoms or
complications.
Antiviral agents (e.g., acyclovir) may be administered in severe
cases or for immunocompromised patients.
Recurrence of Herpetic Infections
Reactivation: Recurrent herpes simplex infections are
due to the reactivation of HSV, which remains dormant in nerve tissue after
the primary infection.
Triggers for Reactivation:
Mucosal injuries (e.g., from dental treatment).
Environmental factors (e.g., sunlight exposure, citrus fruits).
Location of Recurrence: Recurrent infections typically
occur at the same site as the initial infection, commonly manifesting as
herpes labialis (cold sores).
Applications of the Henderson-Hasselbalch equation
Biochemistry
Applications of the Henderson-Hasselbalch equation
• Calculate the ratio of CB to WA, if pH is given
• Calculate the pH, if ratio of CB to WA is known
• Calculate the pH of a weak acid solution of known concentration
• Determine the pKa of a WA-CB pair
• Calculate change in pH when strong base is added to a solution of weak acid. This is represented in a titration curve
• Calculate the pI