৪৮তম স্পেশাল বিসিএস ডেন্টাল ⎯ মডেল টেস্ট [Archived]

The decreased arch Length is due to mesial drifting of permanent molars.

Primate spaces or Simian spaces or Anthropoid spaces are seep mesial to the maxillary canines and distal to the mandibular canines. The primate space of maxillary arch is also known as Baum's space. These spaces are utilized during early mesial shift of molars from end-on to class-I relation.

( Ref- Bhalaji)

Before attempting to close midline diastema, radiographs should be taken to rule out supernumerary teeth as the cause of diastema.

Accelerated development of mandible macroglossia,hypercementosis, early eruption of dentition are the featuresof Acromegaly
Underdeveloped maxilla
• Cleidocranial dysplasia
(Class III malocclusion)
• Craniofacial dysostosis
• Achondroplasia
• Down syndrome
Underdeveloped mandible
• Treacher Collins syndrome
(Class II malocclusion)
• Pierre Robin syndrome
Enlargement of maxilla
• "Leontiasis ossea" or a type of monostotic fibrous dysplasia.
Enlargement of mandible
• Acromegaly (Skeletal Class III)
Enlargement of both
• Pagets disease

Cleft lip and palate is the most common congenital defect of facial structures and the second most congenital defect in the entire spectrum of congenital deformities (first commonis clubfoot).

Competent
The lips are in slight contact when the
lips musculature is relaxed
Incompetent
Morphologically short lips which do not form a lip seal in relaxed state
Potentially incompetent 
Normal lips that fail to form a lip seal due  incompetent to proclined upper incisors or increased lips facial height
Everted lips
Hypertrophied lips with weak muscular
tonicity The lips are in slight contact when the
lips musculature is relaxed

Important Features Of Class II Division 2:
• Labially tipped upper lateral incisors
• Lingually inclined upper central incisors
• Deep anterior overbite
• Normal muscle activity
• Prominent malar process
• Abnormal backward path of closure (due to excessively
tipped central incisors)

Pseudo or habitual or postural class-III is produced by forward movement of the mandible during Jaw closure.
Pseudo class-III malocclusion is characterized by presence of occlusal prematurities resulting in habitual forward positioning of mandible.

Sagittal
Disto-occlusion and Mesic-occlusion
Transverse
Crossbite, buccal non occlusion, Lingual malocclusion
Vertical
Deep bite, open bite
Deep overbite anamolies are categorized into:
• Dentally supported and
• Gingivally supported

Optimal or minimal orthodontic 20-26 gms persq. cm. of rootforces (should be equivalent to capillary pressure)

Anterior open bite is not self-correcting orthodontic problem. It has to be intercepted and treated early. The treatment for open bite ranges from simple habit control procedures to complex surgical procedures.

[Bhalajhi 3rd ed 185)
Application of heavy forces will result in occlusion of blood vessels and the ligament is deprived of its nutritional supply leading to regressive changes called hyalinization.
In this case, the bone cannot resorb in the frontal portion. Rather bone resorption occurs in adjacent marrow spaces behind and above the hyalinized zones. This kind of resorption is called undermining or rearward resorption.

Reciprocal anchorage is the resistance offered by two malposed units when equal and opposite forces tends to move each unit towards a more normal occlusion
split expansion appliance and correction of cross bite by elastics are examples of reciprocal anchorage.

Phases of tooth movement:
Initial phase:
• Very rapid tooth movement over a short distance and
then stops.
• Tooth movement is between 0.4-0.9 mm
• Usually occurs in a week's time
Lag phase:
• Characterized by hyalinization in periodontal ligament.
• Little or no tooth movement occurs.
• Extends for 2-3 weeks but may at times be as long as 10
weeks.
Post Log:
• Hyalinized zone is removed, bone undergoes resorption.
• Tooth moves rapidly.

Crib appliance is placed palatal to the maxillary incisors. It should be worn at least for a 6 months period.

Interrupted force

• Force levels decline to zero between
activations.
• Both continuous and interrupted forces
can be produced by fixed appliances that
are constantly prese

Dewel's method is most commonly used method. In this
method the deciduous canines are extracted first at the
age of 8-9 years. A year later the deciduous first molars
are extracted so that the eruption of first premolars is
accelerated. This is followed by extraction of erupting
first premolars to permit the permanent canines to erupt
in their place.((, D, 4)
• In modified Dewel's technique, the first premolars
are enucleated at the time of extraction of the first
deciduous molars. This is frequently necessary in the
mandibular arch where the canines often erupt before
first premolars.
• Tweed's method, Nance method - D, 4, C.
• In Nance method, deciduous first molars are extracted around 8 years of age. This is followed by extraction of  first premolars and deciduous canines.

Indications of serial extraction
• Skeletal class-I
• Flaring of teeth due to Crowding (AIIMS-09}
• Localized gingival recession in lower anterior region
• Ectopic eruption of teeth
• Unilateral or bilateral premature loss of deciduous
canines with midline shift.
• Space discrepancy should be at least 5 mm in all the four
quadrants (extraction case of carey's or arch perimeter
analysis)
• No skeletal discrepancy should be present.

Used for correction of deep bite Anterior bite plane is used.
• It should provide a clearance of 2-3 mm between upper and lower posterior teeth
to provide space for supra eruption.

When a force is applied, there is stretching of the periodontal fibres on the tension side with raised vascualarity. This raised vascularity causes mobilization of fibroblasts and osteoblasts into that area, which form osteoid. This lightly calcified bone in due course of time matures to form woven bone.

Adams clasp with a single arrow head is indicated in a partially erupted tooth. The single arrowhead usuallyengages the mesioproximal undercut of the partially eruptedtooth, which is usually, is the last erupted molar.

If the primary 2nd molar is Lost before the eruption of permanent 1st molar
• Distal shoe space maintainer
 • Fixed form of distal shoe space
the eruption of maintainer is known as Rocher's or intra alveolar appliance.

Serial extraction is a procedure of interceptive orthodontics

In Band and loop type of space maintainer, the tooth distal to the extraction space is banded and a loop of stainlesssteel wire is soldered to with its mesial end touching the tooth mesial to the extraction space.
he main disadvantage of band and loop space maintainer is that it cannot prevent supra eruption of the tooth in the opposite arch. The crown is used preference to the bandwhen the abutment tooth is highly carious, exhibiting
hypoplasia or pulpotomized.

Thumb/Finger sucking one of the most important factors in producing and maintaining malocclusion. It begins at birth and outgrown
by 3-4 years.

[Bhalaji 4th ed 451]
Catalans or Lower anterior inclined plane appliance is used to treat cross bites. The inclined plane has a 45° angulation,
which forces the maxillary teeth in cross bite to a more labial position. It is teeth supported functional appliance. Expansion screw and Derichsweiler are expansion appliances.

[Bhalajhi 3rd ed 361]
Herbst appliance is a rigid fixed functional appliance. Jasper
jumper is a flexible fixed functional appliance.

An inclined plane appliance is a removable dental appliance used to correct malocclusion, particularly Class II malocclusion and anterior crossbites. It works by guiding the mandible forward and redirecting jaw growth, often by altering the way the teeth fit together.  


Orthodontic Applications:
Correcting Class II Malocclusion:
Inclined planes are frequently used to treat Class II malocclusion, where the upper teeth are positioned too far forward relative to the lower teeth.  
Reducing Overjet:
They can help decrease the overjet (the horizontal distance between the upper and lower front teeth) by encouraging the mandible to move forward.  
Correcting Anterior Crossbite:
Inclined planes can be used to correct anterior crossbite (where lower front teeth are positioned in front of the upper front teeth).  
Myofunctional Therapy:
In some cases, they can be used to enhance mandibular growth and redirect jaw growth, acting as a myofunctional appliance.  
Retention:
Inclined planes can also be used as retention devices after other orthodontic treatments to maintain the corrected position of the teeth and jaws.  
How it Works:
The appliance typically has a sloping surface (the inclined plane) that interacts with the teeth, guiding the lower jaw forward when the patient bites down.  
This can involve guiding the mandible forward during swallowing and redirecting mandibular growth.  
By eliminating the anterior incisal contact, it can also prevent further extrusion of the upper and lower anterior teeth.  
Other Uses:
Simple Machine:
In a broader sense, an inclined plane is a simple machine that allows heavy objects to be moved uphill with less force than lifting them directly.  
Aircraft Evacuation Slides:
In a non-medical context, aircraft evacuation slides are a practical example of an inclined plane, allowing for the safe and rapid descent of passengers from a plane.  
Ramps and Loading:
Ramps used for loading trucks or for pedestrian access are also examples of inclined planes.  
 
 

retention appliances in dentistry should ideally be both retentive and passive. This means they should effectively hold the teeth in their new position (retentive) without actively moving them (passive)

[Bhalajhi 3"' ed 248/M.S. Rani 3rd ed 247)
Rapid palatal expansion should be carried out prior to ossification of midpalatal suture i.e., before a broad range of ossification time table i.e., between 15 - 27 years.

Extrusive movements ideally would produce no areas of compression within the PDL. They produce only tension.

Bodily movement or translation.   70 - 120gms
Tipping, rotation,... ....................  .. 35 - 60gms
Normal orthopedic forces.............> 400 gms

The most common unfavourable sequel of serial extraction is deepening of bite. Uprighting of incisors and early Loss of posterior teeth may result in deep bite. A simple palatal bite plate may correct this proble
Advantages of serial extractions
• Naturally induced movement and alignment of seriously
crowded anterior teeth.
• Improved health of investing tissues.
• Improved psychologic state and better patient
compliance as a result of improve alignment.
• Makes later comprehensive orthodontic treatment easier
and quicker, it reduces the duration of multibonded fixed
treatment.
• Less potential iatrogenic damage.
• Cost is minimal.
• It is often within the range of general practitioners.
Disadvantages of serial extractions
• The most common unfavorable sequel of serial extraction
procedure is deepening of overbite, due to uprighting or
lingual tilting of incisors.
• Treatment time is prolonged as this is carried out in
stages spread over 2-3 years.
• It requires the patient to visit the dentist often, thus
patient co-operation is needed.
• Improper timing of extraction may leads to delay
eruption of secondary teeth.
• If the procedures are not carried out properly, there is a
risk of arch length reducing by mesial migration of the
buccal segment. Thus a poorly executed serial extraction
program can be worse than none at all.

[Bhalajhi 3rd ed 249]
The opening of mid-palatal suture is fan shaped or triangular with maximum opening at the incisor region and gradually diminishes towards posterior part of palate.

The first reaction that takes place when an orthodontist attempts active tooth movement with a removable appliance is formation of Pressure and tension zones in the periodontal
ligament

Reciprocal anchorage
 • Closure of midline diastema by moving two
central incisors each other.
 • The use of crossbite elastics.
 • Arch expansion using a fixed or removable
appliance. Eg: Quad helix, hyrax, jack screw, etc.

Disadvantages of serial extractions
• The most common unfavorable sequel of serial extraction
procedure is deepening of overbite, due to uprighting or
lingual tilting of incisors.
• Treatment time is prolonged as this is carried out in stages spread over 2-3 years.
• It requires the patient to visit the dentist often, thus
patient co-operation is needed.
• Improper timing of extraction may leads to delay
eruption of secondary teeth.
• If the procedures are not carried out properly, there is a
risk of arch length reducing by mesial migration of the
buccal segment. Thus a poorly executed serial extraction
program can be worse than none at all.
Advantages of serial extractions
• Naturally induced movement and alignment of seriously
crowded anterior teeth.
• Improved health of investing tissues.
• Improved psychologic state and better patient
compliance as a result of improve alignment.
• Makes later comprehensive orthodontic treatment easier
and quicker, it reduces the duration of multibonded fixed
treatment.
• Less potential iatrogenic damage.
• Cost is minimal.
• It is often within the range of general practitioners.
64. 'D' [Proffit 5th ed 464 last paragraph]

Type of movement.... Centre of rotation is at
Bodily movement........ Infinity
Torquing movement.... Incisal edge
Intrusion & extrusion.... Outside the tooth
Uncontrolled tipping...... Near centre o

Matching in case-control studies is a technique used to reduce bias by selecting control subjects who are similar to cases (individuals with the outcome of interest) based on specific characteristics, such as age, sex, or other relevant factors. This ensures that the groups being compared (cases and controls) are more comparable, which helps to isolate the effect of the exposure being studied.  
Purpose of Matching:

1.Reduce Confounding:
Matching helps control for confounding variables, which are factors that can distort the true relationship between the exposure and the outcome.  
 2. Study Efficiency:
By making the groups more comparable, matching can improve the efficiency of statistical analysis and reduce the sample size needed.  
3.Improve Comparability:
Matching ensures that the groups being compared are similar in terms of certain characteristics, making the results more reliable.  

Types of Matching:

Individual Matching:
Each case is paired with one or more controls who are identical (or very similar) on the matching variables.  
Frequency Matching:
Controls are selected to have the same distribution of the matching variables as the cases.  
Examples of Matching Variables:
Age: Ensuring cases and controls are within the same age range.  
Sex: Matching based on male or female.  
Race/Ethnicity: Matching based on race or ethnicity, particularly when these factors are related to the outcome or exposure.  
Socioeconomic Status: Matching based on income, education, or occupation.  
Geographic Location: Matching based on where the individuals live.

Interviewer bias in RCT research refers to systematic errors introduced by the interviewer's influence on participants' responses or data collection, potentially distorting the results. This bias can arise from the interviewer's expectations, behaviors, or even their physical characteristics, leading to either inaccurate responses from participants or biased interpretation of those responses.

Descriptive research aims to describe the characteristics of a population or phenomenon. In this type of research, hypotheses are formulated to guide the investigation and help in understanding the specific aspects of the subject being studied. A descriptive research hypothesis is a statement about the characteristics of the population or phenomenon being studied, often focusing on what, where, when, or how something occurs. It doesn't try to explain why something happens (that's analytical research), but rather describes the existing state of affairs

Double-blind study is a research method where neither the participants nor the researchers know who is receiving the treatment or placebo until the study is completed. This approach minimizes bias and increases the reliability of the study results.

A transport host, also known as a paratenic host, is an organism that harbors a parasite but is not essential for the parasite's life cycle. The parasite doesn't undergo further development or replication while in the transport host. Essentially, it acts as a temporary "carrier" moving the parasite towards its next, more suitable host.

prevalence refers to the proportion of a population that has a specific characteristic or condition (like a disease or trait) at a specific point in time. It essentially measures how common something is within a defined group. Prevalence is different from incidence, which measures the rate of new occurrences of a condition over a specific period.

Case-control studies are a valuable research method for investigating rare diseases. They are particularly useful because they start with individuals who already have the disease (cases) and compare them to a control group without the disease. This approach allows researchers to efficiently study potential risk factors for the rare condition, even when it's difficult to find enough affected individuals for other types of studies.

cross-sectional study is an observational research method that analyzes data from a population at a specific point in time. It's used to assess the prevalence of certain traits, conditions, or behaviors within a group, without manipulating any variables. Essentially, it provides a snapshot of the population at that moment, making it useful for understanding current trends and characteristics.

The World Health Organization (WHO) Pathfinder survey utilizes specific age groups to assess oral health, particularly dental caries, across different stages of life. The recommended index ages for a Pathfinder survey are 5 years (for primary teeth), and 12, 15, 35-44, and 65-74 years (for permanent teeth).

The Concentration fluoride in community water fluoridation is about 0. 7 to 1.2 Ppm and the recommended concentration of fluoride in school water fluoridation is 3.5 to 4.5 PPm. (The currently recommended level is 4.5 to 6.3 PPm F) This upward adjustment of fluoride is to compensated for the reduced water in take by the child.

Type of flouridation system> Component used
Saturater system> 4% NaF saturated solution
Dry feeder system>NaF or silicofluoride (most
popular)
Solution feeder system >Hydrofluosilicic acid

In some studies, sealants have been purposively placed over small, overt initial carious lesions. When compare with control teeth, many of the sealed teeth have been
diagnosed as sound after 3 to 5 years. This is due to theseal that does not permit the movement of fluids or tracer isotopes between the sealant and the tooth.

Fluorides. School water fluoridation refers to the adjustment of fluoride concentration of a school's water supply to provide maximum cariostatic effect for the developing dentition and prevent dental caries. The recommended fluoride concentration is usually 3- 4.5ppm.

In cross-sectional, cohort and case control studies individual is the unit of study.

The fluorosis tends to be greater in permanent teeth than primary teeth because of-
• Placenta acts as partial barrier i.e, placenta acts
as regulator of fluoride especially when the
concentration of fluoride reaching fetus is greater
than maternal levels.
• Much of mineralization of primary teeth occurs before
birth.
• Period of enamel formation for primary teeth is shorter
than for permanent teeth.
• Enamel of primary teeth is thinner than that of
permanent teeth.

Sealants mainly act by physical obstruction of pits and grooves.This prevents the penetration of fermentable carbohydrates and so the remaining bacteria cannot produce acid.

Fluoride distribution is not uniform across the thickness of enamel. The accumulation of fluoride by enamel seems largely restricted to the surface region and the fluoride concentration is therefore always relatively high at theenamel surface compared with the interior. Fluorideconcentration also varies systematically from place to place
in the tooth surface and the pattern changes with age.In newly erupted teeth ( anterior teeth) surface fluorideconcentrations were found to be the highest in the first formed enamel near the incisal edge and decreased steeply towards the more recently formed cervical region. In older teeth, this pattern is inverted due to wear.

ART (Atruamatic Restorative Treatment) is a procedure basedon removing carious tooth tissues using hand instrumentsalone and restoring the cavity with an adhesive restorative
material. In ART, the technique used for restoring the cavity with GIC is "Press finger technique

Secondary prevention are self examinations,  perodic screening,  pulp capping,  preventive  resin restoration. 

The quantity of saliva secreted normally is 700-800 ml/day.In conditions like "salivary gland aplasia "and "xerostomia",.The salivary flow is entirely lacking and the result will be rampant form of dental caries

Peter 4th ed 383/ 5th ed 605)
• In normal distribution, the curve of distribution of a given character is more or less symmetrical. It is bell-shaped.
• In normal distribution, Mean = Mode = Median
• The shape of normal distribution depends on mean,
standard deviation and the number and nature of
observation. Total area of this bell-shaped curve is one

Nominal scale data
The information is divided into some
definite qualitative basis.
Eg:
• Male/ female
• White/ black
• Urban / Sub-urban / Rural
• Age
• Socioeconomic  status

In research methodology, a cluster refers to a naturally occurring group within a larger population that is used as a unit for sampling in research studies. Cluster sampling is a probability sampling technique where the population is divided into these clusters, and then a random sample of clusters is selected. All individuals or units within the chosen clusters are then included in the sample.

A histogram is a type of bar graph used specifically for continuous data. It shows the frequency distribution of a dataset.
Although the bars look like a bar diagram, they touch each other because the data is continuous.
A frequency polygon is similar to a histogram, but it uses lines connecting the midpoints of the histogram's bars.

A sample is a part of a population, called the 'Universe' orreference (or) parent population. 'Sampling frame' is thetotal of the elements of the survey population, redefined according to certain specifications. It consists of sampling
units, which are individual entitles that form the focus ofthe study. One of the ideal requirement of the sample is representativeness i.e., each and every member of the sample should represent the parent population.

Information is expressed in ordinal or rank order relations. Eg:
• Olympic medals
• Ranking of medical students
b) For example, Ramu is taller than Ravi scale data and Ravi taller than Vijay, we know something. The information gives the difference in quality but not quantity. No conclusion can be drawn about whether the height difference between Ramu and
Ravi is same as the difference betweenRavi and Vijay.

In areas where vitamin A deficiency is prevalent, routine vitamin A supplementation for young children (6-59 months) is a recommended public health intervention, and it can be viewed as a form of primordial prevention because it targets the underlying cause of potential health problems before they manifest. By ensuring adequate vitamin A levels, it aims to prevent the development of vitamin A deficiency and its associated consequences, such as increased morbidity and mortality

Primary data is the original data that has been compiled for a specific purpose and has not been collated or merged with other. It is collected afresh and for the first time and thus happens to be original in characters.

Types of communication:
1. One way and two way communication
a) One way communication (Didactic): Flow of
information is one way. 
b) Two way communication (Socratic/dilectic)
2. Verbal and non-verbal communication
Verbal communication is the traditional way by word of mouth, non-verbal communication involves a whole range of bodily movements and facial expressions like smile, raising eye brows, frowning.
3. Formal and informal communication
Formal communication follows lines of authority, whereas informal communication is conversing with friends or colleagues.

Bias in research refers to systematic errors that can distort research findings, leading to inaccurate or misleading conclusions. It can occur at any stage of the research process, from study design to data analysis and interpretation, and can affect both qualitative and quantitative studies. Bias can significantly impact the validity and reliability of research outcomes.

The major ethical principles are:
a) To do no harm (non malificience)
b) To do good (beneficience)
c) Respect for persons (autonomy and informed consent)
d) Veracity or truthfulness
e) Confidentiality

Autonomy is the principle that dictates that health care professionals respect the patient's right to make decisions concerning the treatment plan. Patients should not be bystanders in their treatment they are active participants. Informed consent, which is "voluntary", "comprehending" and "confidential" is an essential component of a patient's right to autonomy.

The Declaration of Helsinki is a statement of ethical principles for medical research involving human subjects, developed by the World Medical Association (WMA), first published in 1964. It is considered a cornerstone document in the field of research ethics.  
Here's a breakdown of its key aspects:
Purpose:
The Declaration aims to guide physicians and other participants in medical research involving human subjects.
It emphasizes the ethical considerations that must be addressed in medical research.
It seeks to ensure the well-being of research participants takes precedence over the interests of science and society.  
Key Principles:
Informed Consent:
Participants must be fully informed about the research, including potential risks and benefits, and voluntarily agree to participate.  
Beneficence and Non-maleficence:
Research should aim to maximize potential benefits and minimize potential harms to participants.  
Respect for Persons:
Research should respect the autonomy and dignity of all individuals involved.  
Justice:
The benefits and burdens of research should be distributed fairly among different populations.  
Scientific Validity:
Research must be scientifically sound and conducted by qualified individuals.  
Review by an Independent Committee:
Research protocols should be reviewed by an independent ethics committee.  
Protection of Vulnerable Groups:
Special consideration should be given to the protection of vulnerable populations, such as children, the elderly, and those with diminished capacity.  
Transparency and Accountability:
Researchers should be transparent about their methods and findings and accountable for their actions. 

Aiding and abetting generally involves helping someone else commit a crime, or encouraging them to commit a crime.

Informed consent—the Nuremberg Code identifies
four attributes of consent without which it is not considered valid. It is voluntary, legally competent, informed and comprehending. Consent should
not be obtained by bribery or misinformation.

Autonomy—the primary way to respect individuals is to abide by their choices whether or not others believe these choices to be wise or beneficial. It dictates that health care professionals respect the patient’s right to make decisions concerning the treatment plan.

A dentist can be held liable for a tort, which is a civil wrong, if they breach their duty of care to a patient, causing injury. This often involves negligence, where a dentist fails to meet the standard of care expected of a reasonably prudent dentist, leading to harm. Examples include failing to diagnose a condition, performing a procedure incorrectly, or failing to obtain informed consent. 

On April 7, the world observes World Health Day as a way to raise awareness of important health challenges and motivate group efforts to address them. To increase awareness and drive worldwide action, the day is dedicated to a certain health issue each year. It highlights the necessity of international collaboration in addressing health issues and acts as a reminder of the significance of good health for general well-being.

An express term of a contract is a provision that is explicitly stated and agreed upon by the parties involved, either verbally or in writing, outlining the specific obligations and expectations within the agreement.

Informed consent—the Nuremberg Code identifies
four attributes of consent without which it is not considered valid. It is voluntary, legally competent, informed and comprehending. Consent should
not be obtained by bribery or misinformation.

Informed consent—the
Nuremberg Code identifies
four attributes of consent with-
out which it is not considered
valid. It is voluntary, legally
competent, informed and com-
prehending. Consent should
not be obtained by bribery or
misinformation