NEET MDS Synopsis
Tweed's Analysis
OrthodonticsTweed's Analysis
Tweed's analysis is a comprehensive cephalometric method developed by Dr.
Charles Tweed in the mid-20th century. It is primarily used in orthodontics to
evaluate the relationships between the skeletal and dental structures of the
face, particularly focusing on the position of the teeth and the skeletal bases.
Tweed's analysis is instrumental in diagnosing malocclusions and planning
orthodontic treatment.
Key Features of Tweed's Analysis
Reference Planes and Points:
Sella (S): The midpoint of the sella turcica, a
bony structure in the skull.
Nasion (N): The junction of the frontal and nasal
bones.
A Point (A): The deepest point on the maxillary
arch between the anterior nasal spine and the maxillary alveolar
process.
B Point (B): The deepest point on the mandibular
arch between the anterior nasal spine and the mandibular alveolar
process.
Menton (Me): The lowest point on the symphysis of
the mandible.
Gnathion (Gn): The midpoint between Menton and
Pogonion (the most anterior point on the chin).
Pogonion (Pog): The most anterior point on the
contour of the chin.
Go (Gonion): The midpoint of the contour of the
ramus and the body of the mandible.
Reference Lines:
SN Plane: A line drawn from Sella to Nasion,
representing the cranial base.
Mandibular Plane (MP): A line connecting Gonion
(Go) to Menton (Me), which represents the position of the mandible.
Facial Plane (FP): A line drawn from Gonion (Go) to
Menton (Me), used to assess the facial profile.
Key Measurements:
ANB Angle: The angle formed between the lines
connecting A Point to Nasion and B Point to Nasion. It indicates the
relationship between the maxilla and mandible.
Normal Range: Typically between 2° and 4°.
SN-MP Angle: The angle between the SN plane and the
mandibular plane (MP), which helps assess the vertical position of the
mandible.
Normal Range: Usually between 32° and 38°.
Wits Appraisal: The distance between the
perpendiculars dropped from points A and B to the occlusal plane. It
provides insight into the anteroposterior relationship of the dental
bases.
Interincisal Angle: The angle formed between the
long axes of the maxillary and mandibular incisors, which helps assess
the inclination of the incisors.
Tweed's Philosophy:
Tweed emphasized the importance of achieving a functional occlusion
and a harmonious facial profile. He believed that orthodontic treatment
should focus on the relationship between the dental and skeletal
structures to achieve optimal results.
Clinical Relevance
Diagnosis and Treatment Planning: Tweed's analysis
helps orthodontists diagnose skeletal discrepancies and plan appropriate
treatment strategies. It provides a clear understanding of the patient's
craniofacial relationships, which is essential for effective orthodontic
intervention.
Monitoring Treatment Progress: By comparing
pre-treatment and post-treatment cephalometric measurements, orthodontists
can evaluate the effectiveness of the treatment and make necessary
adjustments.
Predicting Treatment Outcomes: The analysis aids in
predicting the outcomes of orthodontic treatment by assessing the initial
skeletal and dental relationships.
Antidepressant Drugs
Pharmacology
Antidepressant Drugs
Drug treatment of depression is based on increasing serotonin (5-HT) or NE (or both) at synapses in selective tracts in the brain. This can be accomplished by different mechanisms.
Treatment takes several weeks to reach full clinical efficacy.
1. Tricyclic antidepressants (TCAs)
a. Amitriptyline
b. Desipramine
c. Doxepin
d. Imipramine
e. Protriptyline
2. Selective serotonin reuptake inhibitors (SSRIs)
a. Fluoxetine
b. Paroxetine
c. Sertraline
d. Fluvoxamine
e. Citalopram
3. Monoamine oxidase inhibitors (MAOIs)
a. Tranylcypromine
b. Phenelzine
4. Miscellaneous antidepressants
a. Bupropion
b. Maprotiline
c. Mirtazapine
d. Trazodone
e. St. John’s Wort
Antimania Drugs
These drugs are used to treat manic-depressive illness.
1. Lithium
2. Carbamazepine
3. Valproic acid
Mandibular Tori
Oral and Maxillofacial SurgeryMandibular Tori
Mandibular tori are bony growths that occur on the mandible,
typically on the lingual aspect of the alveolar ridge. While they are often
asymptomatic, there are specific indications for their removal, particularly
when they interfere with oral function or prosthetic rehabilitation.
Indications for Removal
Interference with Denture Construction:
Mandibular tori may obstruct the proper fitting of full or partial
dentures, necessitating their removal to ensure adequate retention and
comfort.
Ulceration and Slow Healing:
If the mucosal covering over the torus ulcerates and the wound
exhibits extremely slow healing, surgical intervention may be required
to promote healing and prevent further complications.
Interference with Speech and Deglutition:
Large tori that impede normal speech or swallowing may warrant
removal to improve the patient's quality of life and functional
abilities.
Surgical Technique
Incision Placement:
The incision should be made on the crest of the ridge if
the patient is edentulous (without teeth). This approach allows for
better access to the torus while minimizing trauma to surrounding
tissues.
If there are teeth present in the area, the incision should be made
along the gingival margin. This helps to preserve the
integrity of the gingival tissue and maintain aesthetics.
Avoiding Direct Incision Over the Torus:
It is crucial not to make the incision directly over the torus.
Incising over the torus can lead to:
Status Line: Leaving a visible line on the
traumatized bone, which can affect aesthetics and function.
Thin Mucosa: The mucosa over the torus is
generally very thin, and an incision through it can result in
dehiscence (wound separation) and exposure of the underlying bone,
complicating healing.
Surgical Procedure:
After making the appropriate incision, the mucosal flap is elevated
to expose the underlying bone.
The torus is then carefully removed using appropriate surgical
instruments, ensuring minimal trauma to surrounding tissues.
Hemostasis is achieved, and the mucosal flap is repositioned and
sutured back into place.
Postoperative Care:
Patients may experience discomfort and swelling following the
procedure, which can be managed with analgesics.
Instructions for oral hygiene and dietary modifications may be
provided to promote healing and prevent complications.
Follow-Up:
Regular follow-up appointments are necessary to monitor healing and
assess for any potential complications, such as infection or delayed
healing.
BONES OF THE SKULL
Orthodontics
BONES OF THE SKULL
A) Bones of the cranial base:
A) Fontal (1)
B) Ethmoid (1)
C) Sphenoid (1)
D) Occipital (1)
B) Bones of the cranial vault:
1. Parietal (2)
2. Temporal (2)
C) Bones of the face:
Maxilla (2)
Mandible (1)
Nasal bone (2)
Lacrimal bone (2)
Zygomatic bone (2)
Palatine bone(2)
Infra nasal concha (2)
FUSION BETWEEN BONES
1. Syndesmosis: Membranous or ligamentus eg. Sutural point.
2. Synostosis: Bony union eg. symphysis menti.
3. Synchondrosis: Cartilaginous eg. sphenoccipital, spheno-ethmoidal.
GROWTH OF THE SKULL:
A) Cranium: 1. Base 2. Vault
B) Face: 1. Upper face 2.Lower face
CRANIAL BASE:
Cranial base grows at different cartilaginous suture. The cranial base may be divided into 3 areas.
1. The posterior part which extends from the occiput to the salatercica. The most important growth site spheno-occipital synchondrosis is situated here. It is active throughout the growing period and does not close until early adult life.
2. The middle portion extends from sella to foramen cecum and the sutural growth spheno-ethmoidal synchondrosis is situated here. The exact time of closing is not known but probably at the age of 7 years.
3. The anterior part is from foramen cecum and grows by surface deposition of bone in the frontal region and simultaneous development of frontal sinus.
CRANIAL VAULT:
The cranial vault grows as the brain grows. It is accelerated at infant. The growth is complete by 90% by the end of 5th year. At birth the sutures are wide sufficiently and become approximated during the 1st 2 years of life.
The development and extension of frontal sinus takes place particularly at the age of puberty and there is deposition of bone on the surfaces of cranial bone.
Piezosurgery
Oral and Maxillofacial SurgeryPiezosurgery
Piezosurgery is an advanced surgical technique that utilizes
ultrasonic vibrations to cut bone and other hard tissues with precision. This
method has gained popularity in oral and maxillofacial surgery due to its
ability to minimize trauma to surrounding soft tissues, enhance surgical
accuracy, and improve patient outcomes. Below is a detailed overview of the
principles, advantages, applications, and specific uses of piezosurgery in oral
surgery.
Principles of Piezosurgery
Ultrasonic Technology: Piezosurgery employs ultrasonic
waves to create high-frequency vibrations in specially designed surgical
tips. These vibrations allow for precise cutting of bone while preserving
adjacent soft tissues.
Selective Cutting: The ultrasonic frequency is tuned to
selectively cut mineralized tissues (like bone) without affecting softer
tissues (like nerves and blood vessels). This selectivity reduces the risk
of complications and enhances healing.
Advantages of Piezosurgery
Strength and Durability of Tips:
Piezosurgery tips are made from high-quality materials that are
strong and resistant to fracture. This durability allows for extended
use without the need for frequent replacements, making them
cost-effective in the long run.
Access to Difficult Areas:
The design of piezosurgery tips allows them to reach challenging
anatomical areas that may be difficult to access with traditional
surgical instruments. This is particularly beneficial in complex
procedures involving the mandible and maxilla.
Minimized Trauma:
The ultrasonic cutting action produces less heat and vibration
compared to traditional rotary instruments, which helps to preserve the
integrity of surrounding soft tissues and reduces postoperative pain and
swelling.
Enhanced Precision:
The ability to perform precise cuts allows for better control during
surgical procedures, leading to improved outcomes and reduced
complications.
Reduced Blood Loss:
The selective cutting action minimizes damage to blood vessels,
resulting in less bleeding during surgery.
Applications in Oral Surgery
Piezosurgery has a variety of applications in oral and maxillofacial surgery,
including:
Osteotomies:
LeFort I Osteotomy: Piezosurgery is particularly
useful in performing pterygoid disjunction during LeFort I osteotomy.
The ability to precisely cut bone in the pterygoid region allows for
better access and alignment during maxillary repositioning.
Intraoral Vertical Ramus Osteotomy (IVRO): The
lower border cut at the lateral surface of the ramus can be performed
with piezosurgery, allowing for precise osteotomy while minimizing
trauma to surrounding structures.
Inferior Alveolar Nerve Lateralization:
Piezosurgery can be used to carefully lateralize the inferior alveolar
nerve during procedures such as bone grafting or implant placement,
reducing the risk of nerve injury.
Bone Grafting:
Piezosurgery is effective in harvesting bone grafts from donor
sites, as it allows for precise cuts and minimal damage to surrounding
tissues. This is particularly important in procedures requiring
autogenous bone grafts.
Implant Placement:
The technique can be used to prepare the bone for dental implants,
allowing for precise osteotomy and reducing the risk of complications
associated with traditional drilling methods.
Sinus Lift Procedures:
Piezosurgery is beneficial in sinus lift procedures, where precise
bone cutting is required to elevate the sinus membrane without damaging
it.
Tumor Resection:
The precision of piezosurgery makes it suitable for resecting tumors
in the jaw while preserving surrounding healthy tissue.
FACIAL MUSCLES SPECIFIC IN EMOTIONAL EXPRESSION
Anatomy
Muscle
Emotion
Epicranius
Surprise
Orbicularisoculi
Squinting
Orbicularisoris
Pouting
Nasalis
Smelling
Zygomaticus
Smiling
Buccinator
Chewing
Mentalis
Doubt
Triangularis
Sadness
Platysma
Sadness
Masseter
Chewing
Temporalis
Sternness
Pterygoid
Conternation
Genioglossus and Styloglossus
Swallowing, Speaking, Chewing
OCCLUSION AND DENTAL DEVELOPMENT-Stages-Mixed Dentition Period
Dental Anatomy
Mixed Dentition Period.
-Begins with the eruption of the first permanent molars distal to the second deciduous molars. These are the first teeth to emerge and they initially articulate in an 'end-on' (one on top of the other) relationship.
-On occasion, the permanent incisors spread out due to spacing. In the older literature, is called by the 'ugly duckling stage.' With the eruption of the permanent canines, the spaces often will close.
-Between ages 6 and 7 years of age there are:
20 deciduous teeth
4 first permanent molars
28 permanent tooth buds in various states of development
Food Poisoning
Social and Preventive Medicine
Food Poisoning
Common pathogens attributed to food poisoning include Norovirus, Salmonella, Clostridium perfringens, Campylobacter jejuni, Staphylococcus aureus, and Escherichia coli.
Incubation periods depend on the cause, and range from a few hours to days. The clinical presentation associated with food poisoning varies, but typical symptoms include diarrhea, nausea, vomiting, and abdominal cramping.
Staphylococcal food poisoning
Pathogen: Staphylococcus aureus
Gram-positive bacterium
Some strains produce heat-stable enterotoxins that cause staphylococcal food poisoning.
Transmission: ingestion of preformed toxins in contaminated food
Characteristics
Typically involves a short latency period; resolution of symptoms after 24–48 hours
Bacteria proliferate in inadequately refrigerated food (canned meats, mayonnaise/potato salad, custards).
Incubation period: 1–4 hours
Clinical findings: nausea, vomiting, abdominal discomfort, diarrhea
Bacillus cereus infection
Pathogen: Bacillus cereus, a heat-stable, spore-forming bacterium that produces two different enterotoxins
Transmission: The bacterium grows in heated food that cools down too slowly or is improperly refrigerated. Reheated rice is a common source of infection.
Incubation period and clinical findings
Enterotoxin I (emetic form): 30 min to 6 h after ingestion → nausea and vomiting
Enterotoxin II (diarrheal form): 6–15 h after ingestion → watery diarrhea for 24–48 h
Food poisoning from reheated rice - (B. cereus).