Once bone is formed, it grows by:

 # Once bone is formed, it grows by:

 A. Interstitial growth only

B. Appositional growth only

C. Both appositional and interstitial growth

D. Degenerative changes into bony structures

The correct answer is B. Appositional growth only.

Which is growth by the addition of new layers on those previously formed. Bone formation begins in the embryo where mesenchymal cells differentiate into either fibrous membrane or cartilage. 

This leads to two paths of bone development:

1. Intramembranous ossification is so called because it takes place in membranes of connective tissue. Osteoprogenitor cells in the membrane differentiate into osteoblasts: a collagen matrix is formed which undergoes ossification. Note: The maxilla and mandible as well as the cranial vault are forrmed this way.

2. Endochondral ossification is how the remainder of the skeleton forms and takes place within a hyaline cartilage model. Cartilage cells are replaced by bone cells (osteocytes replace chondrocytes), organic matrix is laid down and calcium and phosphate are deposited. This type of ossification is principally responsible for the formation of short and long bones. Note: The ethmoid, sphenoid, and occipital bones (bones of the cranial base) form this way.

The incisor overjet is increased for a class II case that is undergoing treatment. The reason is:

 # The incisor overjet is increased for a  class II case that is undergoing treatment. The reason is:

 A. Loss of anchorage

B. Arch collapse

C. Crowding in the lower arch

D. None of the above

The correct answer is A. Loss of anchorage.

Following are the features of anchorage loss in class II cases:

- Increase in overjet

- Molar relation  becoming more class II

- Normal canine relation without any change

Which of the following are typical and acceptable preventive and therapeutic measures for dealing with the periodontal problems during fixed appliance therapy?

 # Which of the following are typical and acceptable preventive and therapeutic measures for dealing with the periodontal problems during fixed appliance therapy?

 A. Elimination of gingivitis prior to placing orthodontic appliances

B. Home care instructions regarding the use of toothbrush and water pik during orthodontic treatment

C. Megavitamin therapy

D. Scaling and curettage immediately after appliance removal

The correct answer is A. Elimination of gingivitis prior to placing orthodontic appliances.

The mean value of visible plaque and visible inflammation showed significant increases during orthodontic treatment. Therefore, prior to orthodontic treatment, patients should have a high level of periodontal health and it should be maintained during the treatment period. Considering the relationship between orthodontic treatment and gingival health, patients, orthodontists and periodontists should cooperate during orthodontic treatment.

Reference: Boke F, Gazioglu C, Akkaya S, Akkaya M. Relationship between orthodontic treatment and gingival health: A retrospective study. Eur J Dent. 2014;8(3):373-380. doi:10.4103/1305-7456.137651

FDA approved locally delivered minocycline for subgingival placement is marketed under trade name:

 # FDA approved locally delivered minocycline for subgingival placement is marketed under trade name:

 A. Periochip

B. Atridox

C. Arestin

D. Elyzol

The correct answer is C. Arestin.

FDA has approved Arestin 2% Minocycline for subgingival placement as an adjunct to scaling and root planning.

Periochip: Chlorhexidine chip placed in the pocket for local drug delivery.

The recommended concentration of acidulated phosphate (APF) fluoride gel is:

 # The recommended concentration of acidulated phosphate (APF) fluoride gel is:

 A. 2%

B. 8%

C. 1.23%

D. 10%

The correct answer is C. 1.23%.

Brudevold's solution or APF solution is prepared by dissolving 20 gms of NaF in 1 Litre (2% NaF) of 0.1M phosphoric acid and to this 50% hydro fluoric acid is added to adjust the pH at 3.0 and fluoride ion concentration at 1.23% APF gel is prepared by adding gelling agents like methylcellulose and hydroxyl ethyl cellulose and the pH is adjusted between 4-5.

Duraphat is:

 # Duraphat is:

 A. Lacquer

B. Sodium Fluoride in varnish form

C. Stannous Fluoride

D. Sodium Fluoride 2%

The correct answer is B. Sodium fluoride in varnish form.

Duraphat 50 mg/mL Dental Suspension is to be applied by the dental professional and not for self medication by the patient. 1 mL suspension contains 50 mg sodium fluoride (5% w/v), equivalent to 22,600 ppm fluoride ion (22.6 mg of fluoride) in an alcoholic solution of natural resins.

Recommended dosage for single application:

For primary teeth: up to 0.25 mL (= 5.65 mg fluoride)

For mixed dentition: up to 0.40 mL (= 9.04 mg fluoride)

For permanent dentition: up to 0.75 mL (= 16.95 mg fluoride)

For caries prevention: the application is usually repeated every 6 months but more frequent

applications (every 3 months) may be made.

For hypersensitivity: 2 or 3 applications should be made within a few days.

The patient should not brush the teeth or chew food for 4 hours after treatment.

Method of administration: For dental use.

Contraindications

• Hypersensitivity to any ingredients of Duraphat.
• Ulcerative gingivitis.
• Stomatitis.
• Bronchial asthma.

Special warnings and precautions for use

Application of Duraphat 50 mg/mL Dental Suspension to the whole dentition should not be carried out on an empty stomach. On the day when Duraphat has been applied, no high dose fluoride preparations, such as fluoride gels, should be used. The administration of fluoride supplements should be suspended for several days after applying Duraphat. Prolonged daily ingestion of excessive fluoride may result in varying degrees of fluorosis.

Interaction with other medicines and other forms of interaction

The presence of alcohol (33.8% v/v) in the Duraphat formula should be considered.

Fertility, pregnancy and lactation

As this product contains 33.8% v/v of ethanol (each dose contains up to 0.2 g of alcohol), it is recommended to avoid its use in pregnant women and during lactation.

Undesirable effects

Gastrointestinal disorders: Very rare (<1/10,000): Stomatitis, gingivitis ulcerative, retching, oedema mouth and nausea may occur in sensitive (allergic) individuals

- if necessary, the dental suspension layer can easily be removed from the mouth by brushing and rinsing.

Skin and subcutaneous tissue disorders: Very rare (<1/10,000): Irritation in sensitive individuals, angioedema

Immune System Disorders: Not known (cannot be estimated from the available data)

Hypersensitivity. Respiratory, thoracic and mediastinal disorders: Very rare/Isolated report (<1/10,000): Asthma

Overdose: Accidental ingestion of large amounts of fluoride may result in acute burning in the mouth and sore tongue. Nausea, vomiting and diarrhoea may soon occur after ingestion (within 30 minutes) and are accompanied by salivation, haematemesis, and epigastric cramping abdominal pain. These symptoms may persist for 24 hours. If less than 5 mg fluoride/kg body weight has been ingested, give calcium (eg milk) orally to relieve gastrointestinal symptoms and observe for medical assistance. For accidental ingestion of more than 15 mg fluoride/kg body weight, admit immediately to a hospital facility. 

A malocclusion is characterized by protrusion of maxilla, labioversion of maxillary incisors deep overbite and overjet. These are typical characteristic of which malocclusion?

 # A malocclusion is characterized by protrusion of maxilla, labioversion of maxillary incisors deep overbite and overjet. These are typical characteristic of which malocclusion?

 A. Class I

B. Class II Div 1

C. Class II Div 2

D. Class III

The correct answer is B. Class II Div 1.

Class I Incisor Relationship

Lower incisal edges occlude with or lie immediately below the cingulum plateau of the upper incisors.

Class II Incisor Relationship

The lower incisal edge lies posterior to the cingulum plateau of the upper incisors.

Class II Division 1 Incisor Relationship : The upper central incisors are proclined or of average inclination. There is an increase in overjet.

Class II Division 2 Incisor Relationship : The upper central incisors are retroclined. The overjet is usually minimal but may be increased.

Class III Incisor Relationship: The lower incisal edges lies anterior to the cingulum plateau of the upper incisor.