NEET MDS Synopsis
Modified Widman Flap
PeriodontologyModified Widman Flap Procedure
The modified Widman flap procedure is a surgical technique used in
periodontal therapy to treat periodontal pockets while preserving the
surrounding tissues and promoting healing. This lecture will discuss the
advantages and disadvantages of the modified Widman flap, its indications, and
the procedural steps involved.
Advantages of the Modified Widman Flap Procedure
Intimate Postoperative Adaptation:
The main advantage of the modified Widman flap procedure is the
ability to establish a close adaptation of healthy collagenous
connective tissues and normal epithelium to all tooth surfaces. This
promotes better healing and integration of tissues post-surgery
Feasibility for Bone Implantation:
The modified Widman flap procedure is advantageous over curettage,
particularly when the implantation of bone and other substances is
planned. This allows for better access and preparation of the surgical
site for grafting .
Conservation of Bone and Optimal Coverage:
Compared to conventional reverse bevel flap surgery, the modified
Widman flap conserves bone and provides optimal coverage of root
surfaces by soft tissues. This results in:
A more aesthetically pleasing outcome.
A favorable environment for oral hygiene.
Potentially less root sensitivity and reduced risk of root
caries.
More effective pocket closure compared to pocket elimination
procedures .
Minimized Gingival Recession:
When reattachment or minimal gingival recession is desired, the
modified Widman flap is preferred over subgingival curettage, making it
a suitable choice for treating deeper pockets (greater than 5 mm) and
other complex periodontal conditions.
Disadvantages of the Modified Widman Flap Procedure
Interproximal Architecture:
One apparent disadvantage is the potential for flat or concave
interproximal architecture immediately following the removal of the
surgical dressing, particularly in areas with interproximal bony
craters. This can affect the aesthetic outcome and may require further
management .
Indications for the Modified Widman Flap Procedure
Deep Pockets: Pockets greater than 5 mm, especially in
the anterior and buccal maxillary posterior regions.
Intrabony Pockets and Craters: Effective for treating
pockets with vertical bone loss.
Furcation Involvement: Suitable for managing
periodontal disease in multi-rooted teeth.
Bone Grafts: Facilitates the placement of bone grafts
during surgery.
Severe Root Sensitivity: Indicated when root
sensitivity is a significant concern.
Procedure Overview
Incisions and Flap Reflection:
Vertical Incisions: Made to access the periodontal
pocket.
Crevicular Incision: A horizontal incision along
the gingival margin.
Horizontal Incision: Undermines and removes the
collar of tissue around the teeth.
Conservative Debridement:
Flap is reflected just beyond the alveolar crest.
Careful removal of all plaque and calculus while preserving the root
surface.
Frequent sterile saline irrigation is used to maintain a clean
surgical field.
Preservation of Proximal Bone Surface:
The proximal bone surface is preserved and not curetted, allowing
for better healing and adaptation of the flap.
Exact flap adaptation is achieved with full coverage of the bone.
Suturing:
Suturing is aimed at achieving primary union of the proximal flap
projections, ensuring proper healing and tissue integration.
Postoperative Care
Antibiotic Ointment and Periodontal Dressing:
Traditionally, antibiotic ointment was applied over sutures, and a
periodontal dressing was placed. However, these practices are often omitted
today.
Current Recommendations: Patients are advised not to
disturb the surgical area and to use a chlorhexidine mouth rinse every 12
hours for effective plaque control and to promote healing.
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Neutrophil Disorders Associated with Periodontal Diseases
Neutrophils play a crucial role in the immune response, particularly in
combating infections, including those associated with periodontal diseases.
Various neutrophil disorders can significantly impact periodontal health,
leading to increased susceptibility to periodontal diseases. This lecture will
explore the relationship between neutrophil disorders and specific periodontal
diseases.
Neutrophil Disorders
Diabetes Mellitus
Description: A metabolic disorder characterized by
high blood sugar levels due to insulin resistance or deficiency.
Impact on Neutrophils: Diabetes can impair
neutrophil function, including chemotaxis, phagocytosis, and the
oxidative burst, leading to an increased risk of periodontal infections.
Papillon-Lefevre Syndrome
Description: A rare genetic disorder characterized
by palmoplantar keratoderma and severe periodontitis.
Impact on Neutrophils: Patients exhibit neutrophil
dysfunction, leading to early onset and rapid progression of periodontal
disease.
Down�s Syndrome
Description: A genetic disorder caused by the
presence of an extra chromosome 21, leading to various developmental and
health issues.
Impact on Neutrophils: Individuals with Down�s
syndrome often have impaired neutrophil function, which contributes to
an increased prevalence of periodontal disease.
Chediak-Higashi Syndrome
Description: A rare genetic disorder characterized
by immunodeficiency, partial oculocutaneous albinism, and neurological
problems.
Impact on Neutrophils: This syndrome results in
defective neutrophil chemotaxis and phagocytosis, leading to increased
susceptibility to infections, including periodontal diseases.
Drug-Induced Agranulocytosis
Description: A condition characterized by a
dangerously low level of neutrophils due to certain medications.
Impact on Neutrophils: The reduction in neutrophil
count compromises the immune response, increasing the risk of
periodontal infections.
Cyclic Neutropenia
Description: A rare genetic disorder characterized
by recurrent episodes of neutropenia (low neutrophil count) occurring
every 21 days.
Impact on Neutrophils: During neutropenic episodes,
patients are at a heightened risk for infections, including periodontal
disease.
Dentin
Dental Anatomy
Dentin
Composition: 70% inorganic, 20% organic, 10% water by weight and 45%, 33%, and 22% in volume respectively
Hydroxyapatite crystals and collagen type I
Physical characteristics: Harder than bone and softer than enamel
Yellow in color in normal teeth
Radiographic appearance: More radiolucent than enamel
Primary (circumpulpal) dentin: forms most of the tooth
Mantle dentin: first dentin to form; forms the outline of dentin in the adult tooth
Predentin: lines the innermost portion of dentin (faces the pulp)
Secondary dentin: after root formation dentin continues to form, continuous to primary dentin but with structural irregularities
Tertiary dentin: reactive or reparative dentin; may or may not have characteristics of primary dentin; produced in the area of an external stimulus; osteodentin
Dentin is formed by cells called odontoblasts.
These cells derive from the ectomesenchyme and produce the organic matrix that will calcify and become the dentin.
Formation of dentin initiates formation of enamel.
The formation of dentin starts during late bell-stage in the area of the future cusp.
First coronal dentin and then root dentin.
Completion of dentin does not occur until about 18 months after eruption of primary and 2-3 years after eruption of permanent teeth.
The rate of dentin development varies.
The role of the internal (inner) dental (enamel) epithelium
Cuboidal - Columnar (reverse polarization)
Ectomesenchymal cells of the dental papilla become preodontoblasts - odontoblasts
Acellular zone disappears
Histologic features of dentin
Odontoblasts
Dentinal tubules
Extend through the entire thickness of dentin
S-shaped (primary curvatures) path in the crown, less S-shaped in the root, almost straight in the cervical aspect
Secondary curvatures
Tubular microbranches
Presence of fluid
Intratubular dentin
Dentin in the tubule that is hypermineralized
The term peritubular dentin should not be used
Sclerotic dentin
Dentinal tubules that are occluded with calcified material
Most likely a physiologic response
Reduction of permeability of dentin
Intertubular dentin
Dentin between the tubules
Interglobular dentin
Areas of unmineralized or hypomineralized dentin
The defect affects mineralization and not the architecture of dentin
Incremental lines
Lines of von Ebner: lines associated with 5-day rythmic pattern of dentin deposition
Contour lines of Owen: Originally described by Owen they result from a coincidence of the secondary curvatures between neighboring dentinal tubules.
Granular Layer of Tomes
Seen only in ground sections in the root area covered by cementum
Originally, they were thought to be areas of hypomineralization
They are true spaces obtained by sections going through the looped terminal portions dentinal tubules
DE junction :Scalloped area
Enamel tissue with incremental lines of Retzius and dentin tissue with parallel, curved dentinal tubules are in contact at the irregular dentino-enamel junction. The junction often has a scalloped-shaped morphology
DC junction Dentin Cemental Junction
Polycystic kidney disease
General Pathology
Polycystic kidney disease
Characterized by the formation of cysts and partial replacement of renal parenchyma.
Genetic transmission: autosomal dominant.
Clinical manifestations:
hypertension, hematuria, palpable renal masses, and progression to renal failure. Commonly associated with berry
aneurysms.
Intramembranous ossification
Anatomy
Intramembranous ossification
Flat bones develop in this way (bones of the skull)
This type of bone development takes place in mesenchymal tissue
Mesenchymal cells condense to form a primary ossification centre (blastema)
Some of the condensed mesenchymal cells change to osteoprogenitor cells
Osteoprogenitor cells change into osteoblasts which start to deposit bone
As the osteoblasts deposit bone some of them become trapped in lacunae in the bone and then change into osteocytes
Osteoblasts lie on the surface of the newly formed bone
As more and more bone is deposited more and more osteocytes are formed from mesenchymal cells
The bone that is formed is called a spicule
This process takes place in many places simultaneously
The spicules fuse to form trabeculae
Blood vessels grow into the spaces between the trabeculae
Mesenchymal cells in the spaces give rise to hemopoetic tissue
This type of bone development forms the first phase in endochondral development
It is also responsible for the growth of short bones and the thickening of long bones
Primary Bone Healing and Rigid Fixation
Oral and Maxillofacial SurgeryPrimary Bone Healing and Rigid Fixation
Primary bone healing is a process that occurs when bony
fragments are compressed against each other, allowing for direct healing without
the formation of a callus. This type of healing is characterized by the
migration of osteocytes across the fracture line and is facilitated by rigid
fixation techniques. Below is a detailed overview of the concept of primary bone
healing, the mechanisms involved, and examples of rigid fixation methods.
Concept of Compression
Compression of Bony Fragments: In primary bone healing,
the bony fragments are tightly compressed against each other. This
compression is crucial as it allows for the direct contact of the bone
surfaces, which is necessary for the healing process.
Osteocyte Migration: Under conditions of compression,
osteocytes (the bone cells responsible for maintaining bone tissue) can
migrate across the fracture line. This migration is essential for the
healing process, as it facilitates the integration of the bone fragments.
Characteristics of Primary Bone Healing
Absence of Callus Formation: Unlike secondary bone
healing, which involves the formation of a callus (a soft tissue bridge that
eventually hardens into bone), primary bone healing occurs without callus
formation. This is due to the rigid fixation that prevents movement between
the fragments.
Haversian Remodeling: The healing process in primary
bone healing involves Haversian remodeling, where the bone is remodeled
along the lines of stress. This process allows for the restoration of the
bone's structural integrity and strength.
Requirements for Primary Healing:
Absolute Immobilization: Rigid fixation must
provide sufficient stability to prevent any movement (interfragmentary
mobility) between the osseous fragments during the healing period.
Minimal Gap: There should be minimal distance (gap)
between the fragments to facilitate direct contact and healing.
Examples of Rigid Fixation in the Mandible
Lag Screws: The use of two lag screws across a fracture
provides strong compression and stability, allowing for primary bone
healing.
Bone Plates:
Reconstruction Bone Plates: These plates are
applied with at least three screws on each side of the fracture to
ensure adequate fixation and stability.
Compression Plates: A large compression plate can
be used across the fracture to maintain rigid fixation and prevent
movement.
Proper Application: When these fixation methods are
properly applied, they create a stable environment that is conducive to
primary bone healing. The rigidity of the fixation prevents interfragmentary
mobility, which is essential for the peculiar type of bone healing that
occurs without callus formation.
Buspirone
Pharmacology
Buspirone
1. Short half-life (2–4 hours).
2. Relieves anxiety.
3. Does not act as an anticonvulsant.
4. Is not a good muscle relaxant.
5. Minimum abuse potential.
Sterilization
Conservative DentistrySterilization in Dental Practice
Sterilization is a critical process in dental practice, ensuring that all
forms of life, including the most resistant bacterial spores, are eliminated
from instruments that come into contact with mucosa or penetrate oral tissues.
This guide outlines the accepted methods of sterilization, their requirements,
and the importance of biological monitoring to ensure effectiveness.
Sterilization: The process of killing all forms of
life, including bacterial spores, to ensure that instruments are free from
any viable microorganisms. This is essential for preventing infections and
maintaining patient safety.
Accepted Methods of Sterilization
There are four primary methods of sterilization commonly used in dental
practices:
A. Steam Pressure Sterilization (Autoclave)
Description: Utilizes steam under pressure to achieve
high temperatures that kill microorganisms.
Requirements:
Temperature: Typically operates at 121-134�C
(250-273�F).
Time: Sterilization cycles usually last from 15 to
30 minutes, depending on the load.
Packaging: Instruments must be properly packaged to
allow steam penetration.
B. Chemical Vapor Pressure Sterilization (Chemiclave)
Description: Involves the use of chemical vapors (such
as formaldehyde) under pressure to sterilize instruments.
Requirements:
Temperature: Operates at approximately 132�C
(270�F).
Time: Sterilization cycles typically last about 20
minutes.
Packaging: Instruments should be packaged to allow
vapor penetration.
C. Dry Heat Sterilization (Dryclave)
Description: Uses hot air to sterilize instruments,
effectively killing microorganisms through prolonged exposure to high
temperatures.
Requirements:
Temperature: Commonly operates at 160-180�C
(320-356�F).
Time: Sterilization cycles can last from 1 to 2
hours, depending on the temperature.
Packaging: Instruments must be packaged to prevent
contamination after sterilization.
D. Ethylene Oxide (EtO) Sterilization
Description: Utilizes ethylene oxide gas to sterilize
heat-sensitive instruments and materials.
Requirements:
Temperature: Typically operates at low temperatures
(around 37-63�C or 98.6-145�F).
Time: Sterilization cycles can take several hours,
including aeration time.
Packaging: Instruments must be packaged in
materials that allow gas penetration.
Considerations for Choosing Sterilization Equipment
When selecting sterilization equipment, dental practices must consider
several factors:
Patient Load: The number of patients treated daily will
influence the size and capacity of the sterilizer.
Turnaround Time: The time required for instrument reuse
should align with the sterilization cycle time.
Instrument Inventory: The variety and quantity of
instruments will determine the type and size of sterilizer needed.
Instrument Quality: The materials and construction of
instruments may affect their compatibility with certain sterilization
methods.
Biological Monitoring
A. Importance of Biological Monitoring
Biological Monitoring Strips: These strips contain
spores calibrated to be killed when sterilization conditions are met. They
serve as a reliable weekly monitor of sterilization effectiveness.
B. Process
Testing: After sterilization, the strips are sent to a
licensed reference laboratory for testing.
Documentation: Dentists receive independent
documentation of monitoring frequency and sterilization effectiveness.
Failure Response: In the event of a sterilization
failure, laboratory personnel provide immediate expert consultation to help
resolve the issue.
INVESTING
Dental Materials
INVESTING
Mixing investment with distilled water is done according to the manufacturers ratio in a clean dry bowl without entrapment of the air into the mix.
Mixing methods:
a. Hand mixing and the use of the vibrator to remove air bubbles.
b. Vacuum mixing- This is the better method because it removes air bubbles as well as gases that are produced and thus produces a smoother mix.
Methods of investing:
a. Hand investing
b. Vacuum investing
Hand investing:
First the mixed investment is applied on all the surfaces of the pattern with a soft brush. Blow off any excess investment gently, thus leaving a thin film of investment over the pattern, then apply again.
Then the coated pattern can be invested by two methods;
1. Placing the pattern in the ring first and then filling the ring full with investment.
2. Filling the ring with the investment first and then force the pattern through into it.
Vacuum investing :
Vacuum investing unit: This consists of the chamber of small cubic capacity from which air can be evacuated quickly and in which casting ring can be placed.
Evacuation of air can be done by electrically or water driven vacuum pump.
Procedure:
The ring filled with investment is placed in the vacuum chamber. Air entry tube is closed. Then the vacuum is applied. The investment will rise with froth vigorously for about 10-15 sec and then settles back. This indicates that air has been extracted from the ring. The pressure is now restored to atmospheric by opening the air entry tap gradually at first and then more rapidly as the investment settles back around the pattern. Then the ring is removed from the chamber and the investment is allowed to set. Modern investing unit does both mixing and investing under vacuum and is considered better than hand mixing and pouring.
Then there are two alternatives to be followed depending upon what type of expansion is to be achieved in order to compensate for metal shrinkage. They are:
1. If hygroscopic expansion of the investment is to be achieved then immediately immerse the filled ring in water at the temperature of 37C.
Or “under controlled water adding technique”. A soft flexible rubber ring is used instead of usual lined metal ring. Pattern is invested as usual. Then specified amount of water is added on top of the investment in the rubber ring and the investment is allowed to set at room temperature. In this way only enough water is added to the investment to provide the desired expansion.
2. If thermal expansion of the investment is to be achieved, then investment is allowed to set by placing the ring on the bench for 1 hour or as recommended by the manufacturer.