The most common mandibular surgical osteotomy to advance the mandible is:

 # The most common mandibular surgical osteotomy to advance the mandible is ____. 

A. Le Fort I osteotomy 

B. Segmental maxillary osteotomy 

C. Bilateral sagittal split osteotomy 

D. Intraoral vertical ramus osteotomy 

The correct answer is C. Bilateral sagittal split osteotomy.

Bilateral sagittal split osteotomy (BSSO) is one of the most commonly performed and versatile mandibular procedures. It can be used for backward or forward correction of the mandible in isolation or in combination with a maxillary osteotomy. It is usually performed while the patient is under general anaesthesia. It was originally described by Trauner and Obwegeser in 1957. The procedure has since undergone numerous modifications, including those by Dalpont, Hunsuck, Bell and Epker.

Even when there are large advancements, bone grafting is rarely required because of the long bony interface between the two fragments. Indications for BSSO include mandibular advancement, setback and correction of asymmetry. It is contraindicated in ramus hypoplasia, narrow lateral to medial ramus thickness and severe asymmetries.

Ref: An Introduction to Oral and Maxillofacial Surgery SECOND EDITION, David A. Mitchell, Page 306

Distraction osteogenesis is preferred over a traditional osteotomy:

 # Distraction osteogenesis is preferred over a traditional osteotomy: 

A. When a large advancement is needed 

B. When a small advancement is needed 

C. When exacted interdigitation of the occlusion is needed 

D. When the treatment needs to be done in a very short period of time 

The correct answer is A.  When a large advancement is needed.

Distraction osteogenesis is preferred over traditional osteotomies when large skeletal movements are required and the associated soft tissue cannot adapt to the acute changes and stretching that results. Larger movements may be at increased risk of some relapse; this is particularly true in a patient with a cleft palate, where there is significant soft tissue scarring from previous surgeries.

At which of the following locations are perikymata usually found?

 # At which of the following locations are perikymata usually found?

a. Cervix of the crown.

b. Apex of the root.

c. Cusp tips.

d. Deposited throughout the crown.

The correct answer is A. Cervix of the crown.

Perikymata are transverse, wave-like grooves, believed to be the external manifestations of the striae of Retzius. They are continuous around a tooth and usually lie parallel to each other and to the cementoenamel junction. Ordinarily there are about 30 perikymata per millimeter in the region of the cementoenamel junction, and their concentration gradually decreases to about 10 per millimeter near the occlusal or incisal edge of a surface. Their course usually is fairly regular, but in the cervical region it may be quite irregular. The terms perikymata and imbrication lines are used without distinction to the surface structures of ridges or grooves. To avoid confusion in the usage of these terms it has been suggested that the terms perikymata or imbrication lines be suffixed by the words ridge or crest to denote elevations and the terms groove or furrow to denote depressions, as for example, perikymata ridge.

Reference: Orban's 13th Edition Page no 58

Bones that are small, irregularly shaped, and found along sutures are called

 # Bones that are small, irregularly shaped, and found along sutures are called 

a. Parietal. 

b. Wormian. 

c. Temporal. 

d. Zygomatic. 

The correct answer is B. Wormian bone.

Wormian bones, also known as intrasutural bones or sutural bones, are extra bone pieces that can occur within a suture (joint) in the skull. These are irregular isolated bones that can appear in addition to the usual centres of ossification of the skull and, although unusual, are not rare. They occur most frequently in the course of the lambdoid suture, which is more tortuous than other sutures. They are also occasionally seen within the sagittal and coronal sutures. A large wormian bone at lambda is often called an Inca bone (Os Incae), due to the relatively high frequency of occurrence in Peruvian mummies. Another specific Wormian bone, the pterion ossicle, sometimes exists between the sphenoidal angle of the parietal bone and the great wing of the sphenoid bone. They tend to vary in size and can be found on either side of the skull. Usually, not more than several are found in a single individual, but more than one hundred have been once found in the skull of a hydrocephalic adult.

Wormian bones are a marker for some diseases and important in the primary diagnosis of brittle bone disease: osteogenesis imperfecta.

Wormian bones may also be seen in:

• Pycnodysostosis
• Osteogenesis imperfecta
• Rickets
• "Kinky-hair" Menke's syndrome
• Cleidocranial dysostosis
• Hypothyroidism and hypophosphatasia
• Otopalatodigital syndrome
• Primary acro-osteolysis
• Down syndrome

Which certification is required for dentists that provide general anesthesia?

 # Which certification is required for dentists that provide general anesthesia? 

a. Basic life support (BLS). 

b. Emergency medical training (EMT). 

c. Cardiopulmonary resuscitation (CPR). 

d. Advanced cardiac life support (ACLS). 

The correct answer is D. Advanced cardiac life support (ACLS).

Dentists that provide general anesthesia must be certifed in ACLS for their licensure; BLS certifcation is inadequate. Many states mandate, and the current standard of care necessitates, certifcation in ACLS training for dentists providing general anesthesia. 

ACLS:

For healthcare professionals who either direct or participate in the management of cardiopulmonary arrest or other cardiovascular emergencies and for personnel in emergency response

What does this course teach?

• Basic life support skills, including effective chest compressions, use of a bag-mask device, and use of an AED
• Recognition and early management of respiratory and cardiac arrest
• Recognition and early management of peri-arrest conditions such as symptomatic bradycardia
• Airway management
• Related pharmacology
• Management of ACS and stroke
• Effective communication as a member and leader of a resuscitation team

Which of the following is a property of biofilms and is of clinical signifcance?

 Which of the following is a property of biofilms and is of clinical signifcance?

a. Facilitate stain formation.

b. Increase sensitivity to antibiotics.

c. Extremely tolerant of antimicrobial agents.

d. Enhance the development of halitosis.

The correct answer is C. Extremely tolerant of antimicrobial agents.

The term biofilm describes relatively undefinable microbial community associated with a tooth surface or any other hard non-shedding material. Biofilms are ubiquitous and are found in oral cavity, the bottom of boats and docks, inside pipes, rocks in streams, catheters, hip and voice prosthesis and contact lenses.

Biofilm bacteria exhibit stronger resistance (1000 to 1500 times) to biocides and antimicrobial agents than do their planktonic counterpart. Following hypothesis may help to explain the increased resistance to antimicrobials.

1. The exopolysaccharide of the biofilm matrix may inhibit the diffusion of antimicrobial agents.

2. The physiological differences among biofilm bacteria leave only a part of biofilm bacteria susceptible to growth dependent antibiotics.

3. The genetic changes occurring in transition from planktonic to biofilm bacteria make the biofilm bacteria insensitive to various biocides and antimicrobial agents.

4. Slower rate of growth of organisms due the nutrient limitation may also contribute to the resistance to antimicrobial agents by biofilm bacteria. 

5. Extracellular enzymes such as β–lactamase, formaldehyde dehydrogenase become concentrated in extracellular matrix, thus inactivating some antibiotics.

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Herpes simplex type 1 virus can be transmitted in dentistry by which of the following?

 # Herpes simplex type 1 virus can be transmitted in dentistry by which of the following? 

a. Sharps injury. 

b. Contact with skin. 

c. Inhalation of infected droplets. 

d. Contact of infected material with skin or eyes 

The correct answer is D. Contact of infected material with skin or eyes.

It is estimated that out of the 80 known herpes viruses, at least eight are known to infect human beings. The herpes viruses that are known to cause infection in humans are herpes simplex virus (HSV 1 and 2), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpes virus 6 (HHV-6), human herpes virus 7 (HHV-7) and human herpes virus 8 (HHV-8). These viruses are usually transmitted from host to host by direct contact or through saliva and genital secretions. Herpes viruses are shed in the saliva of asymptomatic hosts.