NEET MDS Synopsis
Finger Rests in Dental Instrumentation
PeriodontologyFinger Rests in Dental Instrumentation
Use of finger rests is essential for providing stability and control during
procedures. A proper finger rest allows for more precise movements and reduces
the risk of hand fatigue.
Importance of Finger Rests
Stabilization: Finger rests serve to stabilize the hand
and the instrument, providing a firm fulcrum that enhances control during
procedures.
Precision: A stable finger rest allows for more
accurate instrumentation, which is crucial for effective treatment and
patient safety.
Reduced Fatigue: By providing support, finger rests
help reduce hand and wrist fatigue, allowing the clinician to work more
comfortably for extended periods.
Types of Finger Rests
Conventional Finger Rest:
Description: The finger rest is established on the
tooth surfaces immediately adjacent to the working area.
Application: This is the most common type of finger
rest, providing direct support for the hand while working on a specific
tooth. It allows for precise movements and control during
instrumentation.
Cross Arch Finger Rest:
Description: The finger rest is established on the
tooth surfaces on the other side of the same arch.
Application: This technique is useful when working
on teeth that are not directly adjacent to the finger rest. It provides
stability while allowing access to the working area from a different
angle.
Opposite Arch Finger Rest:
Description: The finger rest is established on the
tooth surfaces of the opposite arch (e.g., using a mandibular arch
finger rest for instrumentation on the maxillary arch).
Application: This type of finger rest is
particularly beneficial when accessing the maxillary teeth from the
mandibular arch, providing a stable fulcrum while maintaining visibility
and access.
Finger on Finger Rest:
Description: The finger rest is established on the
index finger or thumb of the non-operating hand.
Application: This technique is often used in areas
where traditional finger rests are difficult to establish, such as in
the posterior regions of the mouth. It allows for flexibility and
adaptability in positioning.
Glycogen storage diseases (glycogenoses)
General Pathology
Glycogen storage diseases (glycogenoses)
1. Genetic transmission: autosomal recessive.
2. This group of diseases is characterized by a deficiency of a particular enzyme involved in either glycogen production or degradative pathways.
Diseases include:
on Gierke disease (type I)
(a) Deficient enzyme: glucose-6-phosphatase.
(b) Major organ affected by the buildup of glycogen: liver.
Pompe disease (type II)
(1) Deficient enzyme: α-glucosidase(acid maltase).
(2) Major organ affected by the buildup of glycogen: heart.
Cori disease (type III)
(1) Deficient enzyme: debranching enzyme (amylo-1,6-glucosidase).
(2) Organs affected by the buildup of glycogen: varies between the heart, liver, or skeletal muscle.
Brancher glycogenosis (type IV)
(1) Deficient enzyme: branching enzyme.
(2) Organs affected by the buildup of glycogen: liver, heart, skeletal muscle, and brain.
McArdle syndrome (type V)
(1) Deficient enzyme: muscle phosphorylase.
(2) Major organ affected by the buildup of glycogen: skeletal muscle.
INFARCTION
General Pathology
INFARCTION
Definition : a localized area of ischaemic necrosis in an organ infarcts may be:
Pale :as in
→ Arterial obstruction.
→ solid organs.
Red as in
→ Venous occlusion
→ Loose tissue.
Morphology
Gross: infarcts are usually wedge shaped the apex towards the occluded vessel They are
separated from the surrounding tissue by an hyperemic inflammatory zone
Microscopic:
- An area of coagulative necrosis with a rim of congested vessels and acute inflammatory infiltration of the tissue .
- The polymorphs ale later replaced by mononuclear cells and granulation tissue.
- With time, scar tissue replaces necrosed tissue.
Management and Treatment of Le Fort Fractures
Oral and Maxillofacial SurgeryManagement and Treatment of Le Fort Fractures
Le Fort fractures require careful assessment and management to restore facial
anatomy, function, and aesthetics. The treatment approach may vary depending on
the type and severity of the fracture.
Le Fort I Fracture
Initial Assessment:
Airway Management: Ensure the airway is patent,
especially if there is significant swelling or potential for airway
compromise.
Neurological Assessment: Evaluate for any signs of
neurological injury.
Treatment:
Non-Surgical Management:
Observation: In cases of non-displaced fractures,
close monitoring may be sufficient.
Pain Management: Analgesics to manage pain.
Surgical Management:
Open Reduction and Internal Fixation (ORIF):
Indicated for displaced fractures to restore occlusion and facial
symmetry.
Maxillomandibular Fixation (MMF): May be used
temporarily to stabilize the fracture during healing.
Postoperative Care:
Follow-Up: Regular follow-up to monitor healing and
occlusion.
Oral Hygiene: Emphasize the importance of
maintaining oral hygiene to prevent infection.
Le Fort II Fracture
Initial Assessment:
Airway Management: Critical due to potential airway
compromise.
Neurological Assessment: Evaluate for any signs of
neurological injury.
Treatment:
Non-Surgical Management:
Observation: For non-displaced fractures, close
monitoring may be sufficient.
Pain Management: Analgesics to manage pain.
Surgical Management:
Open Reduction and Internal Fixation (ORIF):
Required for displaced fractures to restore occlusion and facial
symmetry.
Maxillomandibular Fixation (MMF): May be used to
stabilize the fracture during healing.
Postoperative Care:
Follow-Up: Regular follow-up to monitor healing and
occlusion.
Oral Hygiene: Emphasize the importance of
maintaining oral hygiene to prevent infection.
Le Fort III Fracture
Initial Assessment:
Airway Management: Critical due to potential airway
compromise and significant facial swelling.
Neurological Assessment: Evaluate for any signs of
neurological injury.
Treatment:
Non-Surgical Management:
Observation: In cases of non-displaced fractures,
close monitoring may be sufficient.
Pain Management: Analgesics to manage pain.
Surgical Management:
Open Reduction and Internal Fixation (ORIF):
Essential for restoring facial anatomy and occlusion. This may involve
complex reconstruction of the midface.
Maxillomandibular Fixation (MMF): Often used to
stabilize the fracture during healing.
Craniofacial Reconstruction: In cases of severe
displacement or associated injuries, additional reconstructive
procedures may be necessary.
Postoperative Care:
Follow-Up: Regular follow-up to monitor healing,
occlusion, and any complications.
Oral Hygiene: Emphasize the importance of
maintaining oral hygiene to prevent infection.
Physical Therapy: May be necessary to restore
function and mobility.
General Considerations for All Le Fort Fractures
Antibiotic Prophylaxis: Consideration for prophylactic
antibiotics to prevent infection, especially in open fractures.
Nutritional Support: Ensure adequate nutrition,
especially if oral intake is compromised.
Psychological Support: Address any psychological impact
of facial injuries, especially in pediatric patients.
Laminate Veneer
ProsthodonticsLaminate Veneer Technique
The laminate veneer technique is a popular cosmetic dental procedure that
enhances the esthetic appearance of teeth. This technique involves the
application of thin shells of porcelain or composite resin to the facial
surfaces of teeth, simulating the natural hue and appearance of healthy tooth
structure.
Advantages of Laminate Veneers
Esthetic Improvement:
Laminate veneers provide significant esthetic enhancement, allowing
for the restoration of teeth to a natural appearance.
When properly finished, these restorations closely mimic the color
and translucency of natural teeth.
Gingival Tolerance:
Laminate restorations are generally well tolerated by gingival
tissues, even if the contour of the veneers is slightly excessive.
Maintaining good oral hygiene is crucial, but studies have shown
that gingival health can be preserved around these restorations in
cooperative patients.
Preparation Technique
Intraenamel Preparation:
The preparation for laminate veneers involves the removal of 0.5 to
1 mm of facial enamel.
The preparation tapers to about 0.25 to 0.5 mm at the cervical
margin, ensuring a smooth transition and adequate bonding surface.
Cervical Margin:
The cervical margin should be finished in a well-defined chamfer
that is level with the crest of the gingival margin or positioned no
more than 0.5 mm subgingivally.
This careful placement helps to minimize the risk of gingival
irritation and enhances the esthetic outcome.
Incisal Margin:
The incisal margin may end just short of the incisal edge or may
include the entire incisal edge, terminating on the lingual surface.
It is advisable to avoid placing incisal margins where direct
incising forces occur, as this can compromise the integrity of the
veneer.
Bonded Porcelain Techniques
Significance:
Bonded porcelain techniques are highly valuable in cosmetic
dentistry, providing a strong and durable restoration that can withstand
the forces of mastication while enhancing the appearance of the teeth.
Application:
These techniques involve the use of adhesive bonding agents to
secure the veneers to the prepared tooth surface, ensuring a strong bond
and longevity of the restoration.
Biology of tooth movement
OrthodonticsBiology of tooth movement
1. Periodontal Ligament (PDL)
Structure: The PDL is a fibrous connective tissue that
surrounds the roots of teeth and connects them to the alveolar bone. It
contains various cells, including fibroblasts, osteoblasts, osteoclasts, and
immune cells.
Function: The PDL plays a crucial role in transmitting
forces applied to the teeth and facilitating tooth movement. It also
provides sensory feedback and helps maintain the health of the surrounding
tissues.
2. Mechanotransduction
Mechanotransduction is the process by which cells convert mechanical
stimuli into biochemical signals. When a force is applied to a tooth, the
PDL experiences compression and tension, leading to changes in cellular
activity.
Cellular Response: The application of force causes
deformation of the PDL, which activates mechanoreceptors on the surface of
PDL cells. This activation triggers a cascade of biochemical events,
including the release of signaling molecules such as cytokines and growth
factors.
3. Bone Remodeling
Osteoclasts and Osteoblasts: The biological response to
mechanical forces involves the coordinated activity of osteoclasts (cells
that resorb bone) and osteoblasts (cells that form new bone).
Compression Side: On the side of the tooth where
pressure is applied, osteoclasts are activated, leading to bone
resorption. This allows the tooth to move in the direction of the
applied force.
Tension Side: On the opposite side, where tension
is created, osteoblasts are stimulated to deposit new bone, anchoring
the tooth in its new position.
Bone Remodeling Cycle: The process of bone remodeling
is dynamic and involves the continuous resorption and formation of bone.
This cycle is influenced by the magnitude, duration, and direction of the
applied forces.
4. Inflammatory Response
Role of Cytokines: The application of orthodontic
forces induces a localized inflammatory response in the PDL. This response
is characterized by the release of pro-inflammatory cytokines (e.g.,
interleukins, tumor necrosis factor-alpha) that promote the activity of
osteoclasts and osteoblasts.
Healing Process: The inflammatory response is essential
for initiating the remodeling process, but excessive inflammation can lead
to complications such as root resorption or delayed tooth movement.
5. Vascular and Neural Changes
Blood Supply: The PDL has a rich blood supply that is
crucial for delivering nutrients and oxygen to the cells involved in tooth
movement. The application of forces can alter blood flow, affecting the
metabolic activity of PDL cells.
Nerve Endings: The PDL contains sensory nerve endings
that provide feedback about the position and movement of teeth. This sensory
input is important for the regulation of forces applied during orthodontic
treatment.
6. Factors Influencing Tooth Movement
Magnitude and Duration of Forces: The amount and
duration of force applied to a tooth significantly influence the biological
response and the rate of tooth movement. Light, continuous forces are
generally more effective and less damaging than heavy, intermittent forces.
Age and Biological Variability: The biological response
to orthodontic forces can vary with age, as younger individuals tend to have
more active remodeling processes. Other factors, such as genetics, hormonal
status, and overall health, can also affect tooth movement.
Condensers/pluggers
Conservative DentistryCondensers/pluggers are instruments used to deliver the forces of compaction
to the underlying restorative material. There are
several methods for the application of these forces:
1.
Hand pressure: use of this method alone is contraindicated
except in a few situations like adapting the first piece of gold to
the convenience or point angles and where the line of force will not permit
use of other methods. Powdered golds are also
known to be better condensed with hand pressure. Small condenser points of
0.5 mm in diameter are generally
recommended as they do not require very high forces for their manipulation.
2.
Hand malleting: Condensation by hand malleting is a team work
in which the operator directs the condenser and moves it
over the surface, while the assistant provides rhythmic blows from the
mallet. Long handled condensers and leather faced
mallets (50 gms in weight) are used for this purpose. The technique allows
greater control and the condensers can be
changed rapidly when required. However, with the introduction of mechanical
malleting, use of this method has decreased
considerably.
3.
Automatic hand malleting: This method utilizes a spring loaded
instrument that delivers the desired force once the spiral
spring is released. (Disadvantage is that the blow descends very rapidly even
before full pressure has been exerted on the
condenser point.
4.
Electric malleting (McShirley electromallet): This instrument
accommodates various shapes of con-denser points and has a
mallet in the handle itself which remains dormant until wished by the
operator to function. The intensity or amplitude
generated can vary from 0.2 ounces to 15 pounds and the frequency can range
from 360-3600 cycles/minute.
5.
Pneumatic malleting (Hollenback condenser): This is the most
recent and satisfactory method first developed by
Dr. George M. Hollenback. Pneumatic mallets consist of vibrating nit
condensers and detachable tips run by
compressed air. The air is carried through a thin rubber tubing attached to
the hand piece. Controlling the air
pressure by a rheostat nit allows adjusting the frequency and amplitude of
condensation strokes. The construction
of the handpiece is such that the blow does not fall until pressure is placed
on the condenser point. This continues
until released. Pneumatic mallets are available with both straight and angled
for handpieces.
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.