NEET MDS Synopsis
Biologic Width
Conservative DentistryBiologic Width and Drilling Speeds
In restorative dentistry, understanding the concepts of biologic width and
the appropriate drilling speeds is essential for ensuring successful outcomes
and maintaining periodontal health.
1. Biologic Width
Definition
Biologic Width: The biologic width is the area of soft
tissue that exists between the crest of the alveolar bone and the gingival
margin. It is crucial for maintaining periodontal health and stability.
Dimensions: The biologic width is ideally approximately
3 mm wide and consists of:
1 mm of Connective Tissue: This layer provides
structural support and attachment to the tooth.
1 mm of Epithelial Attachment: This layer forms a
seal around the tooth, preventing the ingress of bacteria and other
irritants.
1 mm of Gingival Sulcus: This is the space between
the tooth and the gingiva, which is typically filled with gingival
crevicular fluid.
Importance
Periodontal Health: The integrity of the biologic width
is essential for the health of the periodontal attachment apparatus. If this
zone is compromised, it can lead to periodontal inflammation and other
complications.
Consequences of Violation
Increased Risk of Inflammation: If a restorative
procedure violates the biologic width (e.g., by placing a restoration too
close to the bone), there is a higher likelihood of periodontal
inflammation.
Apical Migration of Attachment: Violation of the
biologic width can cause the attachment apparatus to move apically, leading
to loss of attachment and potential periodontal disease.
2. Recommended Drilling Speeds
Drilling Speeds
Ultra Low Speed: The recommended speed for drilling
channels is between 300-500 rpm.
Low Speed: A speed of 1000 rpm is also considered low
speed for certain procedures.
Heat Generation
Minimal Heat Production: At these low speeds, very
little heat is generated during the drilling process. This is crucial for:
Preventing Thermal Damage: Low heat generation
reduces the risk of thermal damage to the tooth structure and
surrounding tissues.
Avoiding Pulpal Irritation: Excessive heat can lead
to pulpal irritation or necrosis, which can compromise the health of the
tooth.
Cooling Requirements
No Cooling Required: Because of the minimal heat
generated at these speeds, additional cooling with water or air is typically
not required. This simplifies the procedure and reduces the complexity of
the setup.
The Hard Palate
AnatomyThe Hard Palate
The anterior bony part of the palate is formed by the palatine process of the maxillae and the horizontal plates of the palatine bones.
Anteriorly and laterally, the hard palate is bounded by the alveolar processes and the gingivae.
Posteriorly, the hard palate is continuous with the soft palate.
The incisive foramen is the mouth of the incisive canal.
This foramen is located posterior to the maxillary central incisor teeth.
This foramen is the common opening for the right and left incisive canals.
The incisive canal and foramen transmit the nasopalatine nerve and the terminal branches of the sphenopalatine artery.
Medial to the third molar tooth, the greater palatine foramen pierces the lateral border of the bony palate.
The greater palatine vessels and nerve emerge from this foramen and run anteriorly into two grooves on the palate.
The lesser palatine foramen transmits the lesser palatine nerve and vessels.
This runs to the soft palate and adjacent structures.
Arrangement of Teeth in Complete Dentures
ProsthodonticsArrangement of Teeth in Complete Dentures
The arrangement of teeth in complete dentures is a critical aspect of
prosthodontics that affects both the function and aesthetics of the prosthesis.
The following five principal factors must be considered when arranging teeth for
complete dentures:
1. Position of the Arch
Definition: The position of the arch refers to the
spatial relationship of the maxillary and mandibular dental arches.
Considerations:
The relationship between the arches should be established based on
the patient's occlusal plane and the anatomical landmarks of the
residual ridges.
Proper positioning ensures that the dentures fit well and function
effectively during mastication and speech.
The arch position also influences the overall balance and stability
of the denture.
2. Contour of the Arch
Definition: The contour of the arch refers to the shape
and curvature of the dental arch.
Considerations:
The contour should mimic the natural curvature of the dental arch to
provide a comfortable fit and proper occlusion.
The arch contour affects the positioning of the teeth, ensuring that
they align properly with the opposing arch.
A well-contoured arch enhances the esthetics and function of the
denture, allowing for effective chewing and speaking.
3. Orientation of the Plane
Definition: The orientation of the plane refers to the
angulation of the occlusal plane in relation to the horizontal and vertical
planes.
Considerations:
The occlusal plane should be oriented to facilitate proper occlusion
and function, taking into account the patient's facial features and
anatomical landmarks.
The orientation affects the alignment of the teeth and their
relationship to the surrounding soft tissues.
Proper orientation helps in achieving balanced occlusion and
minimizes the risk of denture displacement during function.
4. Inclination of Occlusion
Definition: The inclination of occlusion refers to the
angulation of the occlusal surfaces of the teeth in relation to the vertical
axis.
Considerations:
The inclination should be designed to allow for proper
interdigitation of the teeth during occlusion.
It influences the distribution of occlusal forces and the overall
stability of the denture.
The inclination of occlusion should be adjusted based on the
patient's functional needs and the type of occlusion being utilized
(e.g., balanced, monoplane, or lingualized).
5. Positioning for Esthetics
Definition: Positioning for esthetics involves
arranging the teeth in a way that enhances the patient's facial appearance
and smile.
Considerations:
The arrangement should consider the patient's age, gender, and
facial features to create a natural and pleasing appearance.
The size, shape, and color of the teeth should be selected to match
the patient's natural dentition and facial characteristics.
Proper positioning for esthetics not only improves the appearance of
the dentures but also boosts the patient's confidence and satisfaction
with their prosthesis.
DISINFECTION AND STERILIZATION
General Microbiology
DISINFECTION AND STERILIZATION
• Sterilization is the best destruction or com removal_of all forms of micro organisms.
• Disinfection is the destruction of many microorganisms but usually the b spores.
• Antisepsis is the destruction or inhibition of microorganisms in living tissues thereby limiting or preventing the harmful effect of infection.
• Astatic Agent would only inhibit the growth of microorganisms (bacteriostatic, fungistatic, sporostatic).
• Acidal agent would kill the microorganism (bactericidal. virucidal, fungicidal)
• Sterilants are the chemicals which under controlled conditions can kill sporinQ bacteria.
Dental Calculus
Periodontology
Dental Calculus
Dental calculus, also known as tartar, is a hard deposit that forms on teeth
due to the mineralization of dental plaque. Understanding the composition and
crystal forms of calculus is essential for dental professionals in diagnosing
and managing periodontal disease.
Crystal Forms in Dental Calculus
Common Crystal Forms:
Dental calculus typically contains two or more crystal forms. The
most frequently detected forms include:
Hydroxyapatite:
This is the primary mineral component of both enamel and
calculus, constituting a significant portion of the calculus
sample.
Hydroxyapatite is a crystalline structure that provides
strength and stability to the calculus.
Octacalcium Phosphate:
Detected in a high percentage of supragingival calculus
samples (97% to 100%).
This form is also a significant contributor to the bulk of
calculus.
Other Crystal Forms:
Brushite:
More commonly found in the mandibular anterior region of the
mouth.
Brushite is a less stable form of calcium phosphate and may
indicate a younger calculus deposit.
Magnesium Whitlockite:
Typically found in the posterior areas of the mouth.
This form may be associated with older calculus deposits and can
indicate changes in the mineral composition over time.
Variation with Age:
The incidence and types of crystal forms present in calculus can
vary with the age of the deposit.
Younger calculus deposits may have a higher proportion of brushite,
while older deposits may show a predominance of hydroxyapatite and
magnesium whitlockite.
Clinical Significance
Understanding Calculus Formation:
Knowledge of the crystal forms in calculus can help dental
professionals understand the mineralization process and the conditions
under which calculus forms.
Implications for Treatment:
The composition of calculus can influence treatment strategies. For
example, older calculus deposits may be more difficult to remove due to
their hardness and mineral content.
Assessment of Periodontal Health:
The presence and type of calculus can provide insights into a
patient’s oral hygiene practices and periodontal health. Regular
monitoring and removal of calculus are essential for preventing
periodontal disease.
Research and Development:
Understanding the mineral composition of calculus can aid in the
development of new dental materials and treatments aimed at preventing
calculus formation and promoting oral health.
Amphotericin B
Pharmacology
Amphotericin B
Main use is in systemic fungal infections (e.g. in immunocompromised patients), and in visceral leishmaniasis. Aspergillosis, cryptococcus infections (e.g. meningitis) and candidiasis are treated with amphotericin B. It is also used empirically in febrile immunocompromised patients who do not respond to broad-spectrum antibiotics.
MOA:
As with other polyene antifungals, amphotericin B associates with ergosterol, a membrane chemical of fungi, forming a pore that leads to K+ leakage and fungal cell death
Side effects: nephrotoxicity (kidney damage) , headache, vomiting, convulsions and fever
The side-effects are much milder when amphotericin B is delivered in liposomes
PDL Injection
Oral and Maxillofacial SurgeryIndications for PDL Injection
Primary Indications:
Localized Anesthesia: Effective for one or two
mandibular teeth in a quadrant.
Isolated Teeth Treatment: Useful for treating
isolated teeth in both mandibular quadrants, avoiding the need for
bilateral inferior alveolar nerve blocks.
Pediatric Dentistry: Minimizes the risk of
self-inflicted injuries due to residual soft tissue anesthesia.
Contraindications for Nerve Blocks: Safe
alternative for patients with conditions like hemophilia where nerve
blocks may pose risks.
Diagnostic Aid: Can assist in the localization
of mandibular pain.
Advantages:
Reduced risk of complications associated with nerve blocks.
Faster onset of anesthesia for localized procedures.
Contraindications and Complications of PDL Injection
Contraindications:
Infection or Severe Inflammation: Risks
associated with injecting into infected or inflamed tissues.
Presence of Primary Teeth: Discuss the findings
by Brannstrom and associates regarding enamel hypoplasia or
hypomineralization in permanent teeth following PDL injections in
primary dentition.
Complications:
Potential for discomfort or pain at the injection site.
Risk of damage to surrounding structures if not administered
correctly.
Discussion of the rare but serious complications associated with
PDL injections.
Management of Complications:
Strategies for minimizing risks and managing complications if
they arise.
Water Acid Bases & Buffers
Biochemistry
Keq, Kw and pH
As H2O is the medium of biological systems one must consider the role of this molecule in the dissociation of ions from biological molecules. Water is essentially a neutral molecule but will ionize to a small degree. This can be described by a simple equilibrium equation:
H2O <-------> H+ + OH-
This equilibrium can be calculated as for any reaction:
Keq = [H+][OH-]/[H2O]
Since the concentration of H2O is very high (55.5M) relative to that of the [H+] and [OH-], consideration of it is generally removed from the equation by multiplying both sides by 55.5 yielding a new term, Kw:
Kw = [H+][OH-]
This term is referred to as the ion product. In pure water, to which no acids or bases have been added:
Kw = 1 x 10-14 M2
As Kw is constant, if one considers the case of pure water to which no acids or bases have been added:
[H+] = [OH-] = 1 x 10-7 M
This term can be reduced to reflect the hydrogen ion concentration of any solution. This is termed the pH, where:
pH = -log[H+]