NEET MDS Synopsis
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
MANDIBULAR SECOND BICUSPID
Dental Anatomy
MANDIBULAR SECOND BICUSPID
Facial: From this aspect, the tooth somewhat resembles the first, but the buccal cusp is less pronounced. The tooth is larger than the first.
Lingual: Two significant variations are seen in this view. The most common is the three-cusp form which has two lingual cusps. The mesial of those is the larger of the two. The other form is the two-cusp for with a single lingual cusp. In that variant, the lingual cusp tip is shifted to the mesial.
Proximal: The buccal cusp is shorter than the first. The lingual cusp (or cusps) are much better developed than the first and give the lingual a full, well-developed profile.
Occlusal: The two or three cusp versions become clearly evident. In the three-cusp version, the developmental grooves present a distinctive 'Y' shape and have a central pit. In the two cusp version, a single developmental groove crosses the transverse ridge from mesial to distal
Contact Points; Height of Curvature: From the facial, the mesial contact is more occlusal than the distal contact.The distal marginal ridge is lower than the mesial marginal ridge
Root Surface:-The root of the tooth is single, that is usually larger than that of the first premolar
the lower second premolar is larger than the first, while the upper first premolar is just slightly larger than the upper second
There may be one or two lingual cusps
Complete Denture Occlusion
ProsthodonticsComplete Denture Occlusion
Complete denture occlusion is a critical aspect of prosthodontics, as it
affects the function, stability, and comfort of the dentures. There are three
primary types of occlusion used in complete dentures: Balanced Occlusion,
Monoplane Occlusion, and Lingualized Occlusion. Each type has its own
characteristics and applications.
Types of Complete Denture Occlusion
1. Balanced Occlusion
Definition: Balanced occlusion is characterized by
simultaneous contact of all opposing teeth in centric occlusion, providing
stability and even distribution of occlusal forces.
Key Features:
Three-Point Contact: While a three-point contact
(one anterior and two posterior) is a starting point, it is not
sufficient for true balanced occlusion. Instead, there should be
simultaneous contact of all teeth.
Minimal Occlusal Balance: For minimal occlusal
balance, there should be at least three points of contact on the
occlusal plane. The more points of contact, the better the balance.
Absence in Natural Dentition: Balanced occlusion is
not typically found in natural dentition; it is a concept specifically
applied to complete dentures to enhance stability during function.
Importance: This type of occlusion is particularly
important for patients with complete dentures, as it helps to minimize
tipping and movement of the dentures during chewing and speaking.
2. Monoplane Occlusion
Definition: Monoplane occlusion involves a flat
occlusal plane where the occlusal surfaces of the teeth are arranged in a
single plane.
Key Features:
Flat Occlusal Plane: The occlusal surfaces are
designed to be flat, which simplifies the occlusion and reduces the
complexity of the denture design.
Limited Interference: This type of occlusion
minimizes interferences during lateral and protrusive movements, making
it easier for patients to adapt to their dentures.
Applications: Monoplane occlusion is often used in
cases where the residual ridge is severely resorbed or in patients with
limited jaw movements.
3. Lingualized Occlusion
Definition: Lingualized occlusion is characterized by
the positioning of the maxillary posterior teeth in a way that they occlude
with the mandibular posterior teeth, with the buccal cusps of the mandibular
teeth being positioned more towards the buccal side.
Key Features:
Maxillary Teeth Positioning: The maxillary
posterior teeth are positioned more towards the center of the arch,
while the mandibular posterior teeth are positioned buccally.
Functional Balance: This arrangement allows for
better functional balance and stability during chewing, as the maxillary
teeth provide support to the mandibular teeth.
Advantages: Lingualized occlusion can enhance the
esthetics and function of complete dentures, particularly in patients with a
well-defined ridge.
Early Childhood Caries
Conservative DentistryEarly Childhood Caries (ECC) Classification
Early Childhood Caries (ECC) is a significant public health concern
characterized by the presence of carious lesions in young children. It is
classified into three types based on severity, affected teeth, and underlying
causes. Understanding these classifications helps in diagnosing, preventing, and
managing ECC effectively.
Type I ECC (Mild to Moderate)
A. Characteristics
Affected Teeth: Carious lesions primarily involve the
molars and incisors.
Age Group: Typically observed in children aged 2
to 5 years.
B. Causes
Dietary Factors: The primary cause is usually a
combination of cariogenic semisolid or solid foods, such as sugary snacks
and beverages.
Oral Hygiene: Lack of proper oral hygiene practices
contributes significantly to the development of caries.
Progression: As the cariogenic challenge persists, the
number of affected teeth tends to increase.
C. Clinical Implications
Management: Emphasis on improving oral hygiene
practices and dietary modifications can help control and reverse early
carious lesions.
Type II ECC (Moderate to Severe)
A. Characteristics
Affected Teeth: Labio-lingual carious lesions primarily
affect the maxillary incisors, with or without molar caries, depending on
the child's age.
Age Group: Typically seen soon after the first tooth
erupts.
B. Causes
Feeding Practices: Common causes include inappropriate
use of feeding bottles, at-will breastfeeding, or a combination of both.
Oral Hygiene: Poor oral hygiene practices exacerbate
the condition.
Progression: If not controlled, Type II ECC can
progress to more advanced stages of caries.
C. Clinical Implications
Intervention: Early intervention is crucial, including
education on proper feeding practices and oral hygiene to prevent further
carious development.
Type III ECC (Severe)
A. Characteristics
Affected Teeth: Carious lesions involve almost all
teeth, including the mandibular incisors.
Age Group: Usually observed in children aged 3
to 5 years.
B. Causes
Multifactorial: The etiology is a combination of
various factors, including poor oral hygiene, dietary habits, and possibly
socio-economic factors.
Rampant Nature: This type of ECC is rampant and can
affect immune tooth surfaces, leading to extensive decay.
C. Clinical Implications
Management: Requires comprehensive dental treatment,
including restorative procedures and possibly extractions. Education on
preventive measures and regular dental visits are essential to manage and
prevent recurrence.
Sampling methods in Public Health Dentistry
Public Health DentistrySampling methods are crucial in public health dentistry as they enable
researchers and practitioners to draw conclusions about the oral health of a
population based on a smaller, more manageable subset of individuals. This
approach is cost-effective, time-saving, and statistically valid. Here are the
most commonly used sampling methods in public health dentistry with their
applications:
1. Simple Random Sampling: This is the most basic form of
probability sampling, where each individual in the population has an equal
chance of being selected. It involves the random selection of subjects from a
complete list of all individuals (sampling frame). This method is applied when
the population is homogeneous and the sample is expected to be representative of
the entire population.
It is useful in studies that aim to determine prevalence of dental caries or
periodontal disease in a community, assess the effectiveness of oral health
programs, or evaluate the need for dental services.
2. Stratified Random Sampling: This technique involves dividing
the population into strata (subgroups) based on relevant characteristics such as
age, gender, socioeconomic status, or geographic location. Random samples are
then drawn from each stratum. This method ensures that the sample is more
representative of the population by reducing sampling error.
It is often used when the population is heterogeneous, and there is a
need to analyze the data separately for each subgroup to understand the impact
of different variables on oral health.
Applications:
Oral Health Disparities: Stratified sampling can be
used to ensure representation from different socioeconomic groups when
studying access to dental care.
Age-Specific Studies: In research focusing on pediatric
dental health, stratified sampling can help ensure that children from
various age groups are adequately represented.
3. Cluster Sampling: In this method, the population is divided
into clusters (e.g., schools, neighborhoods, or dental clinics) and a random
sample of clusters is selected. All individuals within the chosen clusters are
included in the study. This approach is useful when the population is widely
dispersed, and it reduces travel and data collection costs. It is often applied
in community-based dental health surveys and epidemiological studies.
Applications:
School-Based Dental Programs: Cluster sampling can be
used to select schools within a district to assess the oral health status of
children, where entire schools are chosen rather than individual students.
Community Health Initiatives: In evaluating the
effectiveness of community dental health programs, clusters (e.g.,
neighborhoods) can be selected to represent the population.
4. Systematic Sampling: This technique involves selecting every
nth individual from the sampling frame, where n is the sampling interval. It is
a probability sampling method that can be used when the population has some
order or pattern. For instance, in a school-based dental health survey, students
from every third grade might be chosen to participate.
This method is efficient for large populations and can be representative if
the sampling interval is appropriate.
Applications:
Community Health Assessments: Systematic sampling can
be used to select households for surveys on oral hygiene practices, where
every 10th household is chosen from a list of all households in a
neighborhood.
Patient Records Review: In retrospective studies,
systematic sampling can be applied to select patient records at regular
intervals to assess treatment outcomes.
5. Multi-stage Sampling: This is a combination of different
sampling methods where the population is divided into smaller and smaller
clusters in each stage. It is particularly useful for large-scale studies where
the population is not easily accessible or when the study requires detailed data
from various levels (e.g., national to local levels).
For example, in a multi-stage design, a random sample of states might
be selected in the first stage, followed by random samples of counties within
those states, and then schools within the selected counties.
Applications in Public Dental Health:
National Oral Health Surveys: Researchers may first
randomly select states or regions (clusters) and then randomly select dental
clinics or households within those regions to assess the prevalence of
dental diseases or access to dental care.
Community Health Assessments: In a large city,
researchers might select neighborhoods as the first stage and then sample
residents within those neighborhoods to evaluate oral health behaviors and
access to dental services.
Program Evaluation: Multi-stage sampling can be used to
evaluate the effectiveness of community dental health programs by selecting
specific program sites and then sampling participants from those sites.
6. Convenience Sampling: Although not a probability sampling method,
convenience sampling is often used in public health dentistry due to practical
constraints. It involves selecting individuals who are readily available and
willing to participate. While this method may introduce bias, it is useful for
pilot studies, exploratory research, or when the goal is to obtain preliminary
data quickly and inexpensively. It is important to be cautious when generalizing
findings from convenience samples to the broader population.
Applications:
Pilot Studies: Convenience sampling can be used in
preliminary studies to gather initial data on dental health behaviors among
easily accessible groups, such as dental clinic patients.
Focus Groups: In qualitative research, convenience
sampling may be used to gather opinions from dental patients who are readily
available for discussion.
7. Quota Sampling: This is a non-probability sampling method
where the researcher sets quotas for specific characteristics of the population
(e.g., age, gender) and then recruits individuals to meet those quotas. It is
often used in surveys where it is crucial to have a representative sample
regarding certain demographic variables.
However, it may not be as statistically robust as probability sampling
methods and can introduce bias if the quotas are not met correctly.
Applications in Public Dental Health:
Targeted Surveys: Researchers can use quota sampling to
ensure that specific demographic groups (e.g., children, elderly, low-income
individuals) are adequately represented in surveys assessing oral health
knowledge and behaviors.
Program Evaluation: In evaluating community dental
health programs, quota sampling can help ensure that participants reflect
the diversity of the target population, allowing for a more comprehensive
understanding of program impact.
Focus Groups: Quota sampling can be used to assemble
focus groups for qualitative research, ensuring that participants represent
various perspectives based on predetermined characteristics relevant to the
study.
8. Purposive (Judgmental) ampling: In this approach,
participants are selected based on specific criteria that the researcher
believes are important for the study. This method is useful for studies that
require in-depth understanding, such as qualitative research or when studying a
rare condition. It is essential to ensure that the sample is diverse enough to
provide a comprehensive perspective.
Applications:
Expert Interviews: In studies exploring dental policy
or public health initiatives, purposive sampling can be used to select key
informants, such as dental professionals or public health officials.
Targeted Health Interventions: When studying specific
populations (e.g., individuals with disabilities), purposive sampling
ensures that the sample includes individuals who meet the criteria.
9. Snowball Sampling: This is a non-probability method where
initial participants are selected based on the researcher's judgment and then
asked to refer others with similar characteristics. It is often used in studies
involving hard-to-reach populations, such as those with rare oral conditions or
specific behaviors.
While it can provide valuable insights, the sample may not be representative
of the broader population.
Applications :
Studying Marginalized Groups: Researchers can use
snowball sampling to identify and recruit individuals from marginalized
communities (e.g., homeless individuals, low-income families) to assess
their oral health needs and barriers to accessing dental care.
Behavioral Research: In studies examining specific
behaviors (e.g., smoking and oral health), initial participants can help
identify others who share similar characteristics or experiences,
facilitating data collection from a relevant population.
Qualitative Research: Snowball sampling can be
effective in qualitative studies exploring the experiences of individuals
with specific dental conditions or those participating in community dental
health programs.
10. Time-Space Sampling: This technique is used to study
populations that are not fixed in place, such as patients attending a dental
clinic during specific hours. Researchers select random times and days and then
include all patients who visit the clinic during those times in the sample.
This method can be useful for assessing the representativeness of
clinic-based studies.
Applications
Mobile Populations: Researchers can use time-space
sampling to assess the oral health of populations that may not have a fixed
residence, such as migrant workers or individuals living in temporary
housing.
Event-Based Sampling: Public health campaigns or dental
health fairs can be used as time-space sampling points to recruit
participants for surveys on oral health behaviors and access to care.
Community Outreach: Time-space sampling can help
identify individuals attending community events or clinics to gather data on
their oral health status and service utilization.
The choice of sampling method in public health dentistry depends on the research
question, the population's characteristics, the available resources, and the
desired level of generalizability. Probability sampling methods are generally
preferred for their scientific rigor, but non-probability methods may be
necessary under certain circumstances. It is essential to justify the chosen
method and consider its limitations when interpreting the results.
Antihypertensives drugs -RENIN-ANGIOTENSIN SYSTEM INHIBITORS
Pharmacology
RENIN-ANGIOTENSIN SYSTEM INHIBITORS
The actions of Angiotensin II include an increase in blood pressure and a stimulation of the secretion of aldosterone (a hormone from the adrenal cortex) that promotes sodium retention. By preventing the formation of angiotensin II, blood pressure will be reduced. This is the strategy for development of inhibitors. Useful inhibitors of the renin-angiotensin system are the Angiotensin Converting Enzyme Inhibitors
First line treatment for: Hypertension , Congestive heart failure [CHF]
ACE-Inhibitor’s MOA (Angiotensin Converting Enzyme Inhibitors)
Renin-Angiotensin Aldosterone System:
. Renin & Angiotensin = vasoconstrictor
. constricts blood vessels & increases BP
. increases SVR or afterload
. ACE Inhibitors blocks these effects decreasing SVR & afterload
. Aldosterone = secreted from adrenal glands
. cause sodium & water reabsorption
. increase blood volume
. increase preload
. ACE I blocks this and decreases preload
Types
Class I: captopril
Class II (prodrug) : e.g., ramipril, enalapril, perindopril
Class III ( water soluble) : lisinopril.
Mechanism of Action
Inhibition of circulating and tissue angiotensin- converting enzyme.
Increased formation of bradykinin and vasodilatory prostaglandins.
Decreased secretion of aldosterone; help sodium excretion.
Advantages
- Reduction of cardiovascular morbidity and mortality in patients with atherosclerotic vascular disease, diabetes, and heart failure.
- Favorable metabolic profile.
- Improvement in glucose tolerance and insulin resistance.
- Renal glomerular protection effect especially in diabetes mellitus.
- Do not adversely affect quality of life.
Indications
- Diabetes mellitus, particularly with nephropathy.
- Congestive heart failure.
- Following myocardial infraction.
Side Effects
- Cough (10 - 30%): a dry irritant cough with tickling sensation in the throat.
- Skin rash (6%).
- Postural hypotension in salt depleted or blood volume depleted patients.
- Angioedema (0.2%) : life threatening.
- Renal failure: rare, high risk with bilateral renal artery stenosis.
- Hyperkalaemia
- Teratogenicity.
Considerations
- Contraindications include bilateral renal artery stenosis, pregnancy, known allergy, and hyperkalaemia.
- High serum creatinine (> 3 mg/dl) is an indication for careful monitoring of renal function, and potassium. Benefits can still be obtained in spite of renal insufficiency.
- A slight stable increase in serum creatinine after the introduction of ACE inhibitors does not limit use.
- ACE-I are more effective when combined with diuretics and moderate salt restriction.
ACE inhibitors drugs
Captopril 50-150 mg
Enalapril 2.5-40 mg
Lisinopril 10-40 mg
Ramipril 2.5-20 mg
Perindopril 2-8 mg
Angiotensin Receptor Blocker
Losartan 25-100 mg
Candesartan 4-32 mg
Telmisartan 20-80 mg
Mechanism of action
They act by blocking type I angiotensin II receptors generally, producing more blockade of the renin -angiotensin - aldosterone axis.
Advantages
• Similar metabolic profile to that of ACE-I.
• Renal protection.
• They do not produce cough.
Indications
Patients with a compelling indication for ACE-I and who can not tolerate them because of cough or allergic reactions.
Proper Pin Placement in Amalgam Restorations
Conservative DentistryProper Pin Placement in Amalgam Restorations
Principles of Pin Placement
Strength Maintenance: Proper pin placement does not
reduce the strength of amalgam restorations. The goal is to maintain the
strength of the restoration regardless of the clinical problem, tooth size,
or available space for pins.
Single Unit Restoration: In modern amalgam
preparations, it is essential to secure the restoration and the tooth as a
single unit. This is particularly important when significant tooth structure
has been lost.
Considerations for Cusp Replacement
Cusp Replacement: If the mesiofacial wall is replaced,
the mesiofacial cusp must also be replaced to ensure proper occlusal
function and distribution of forces.
Force Distribution: It is crucial to recognize that
forces of occlusal loading must be distributed over a large area. If the
distofacial cusp were replaced with a pin, there would be a tendency for the
restoration to rotate around the mesial pins, potentially leading to
displacement or failure of the restoration.
Impression Materials - Manipulation
Dental Materials
Manipulation
Mixing
o P/L types mixed in bowl (plaster and alginate)
o Thermoplastic materials not mixed (compound and agar-agar)
o Paste/paste types hand mixed on pad (zinc oxide-eugenol, polysulfide rubber, silicone rubber, polyether rubber. and poly-vinylsiloxane)
o Paste/paste mixed through a nozzle on an auto-mixing gun (poly-vinylsiloxane)
Placement
o Mixed material carried in tray to mouth (full arch tray, quadrant tray. or triple tray)
o Materials set in mouth more quickly because of higher temperature
Removal - rapid removal of impression encourages deformation to take place elastically rather than permanently (elastic deformation requires about 20 minutes)
Cleaning and disinfection of impressions