Toothbrush trauma usually occurs on:

# Toothbrush trauma (cervical abrasion) usually occurs on:
A. Centrals and laterals
B. Canines and premolars
C. Second and third molar
D. First and second molars

The correct answer is: B. Canines and premolars.

Toothbrush trauma (abrasion) usually occurs on teeth that are the most prominent in the dental arch.

Trauma from toothbrushing may result in the following:

• Recession of the marginal gingiva

• Lacerations of the soft tissues including the attached gingiva and the alveolar mucosa

• V-shaped notches in the cervical areas of teeth

• Gingival clefts: which are narrow grooves that extend from the crest of the gingiva to the attached gingiva

The location of the above alterations is frequently inversely related to the right or left handedness of the patient.

Gingival enlargement without destruction of the underlying periodontal tissues

# Which type of pocket is formed by gingival enlargement without destruction of the underlying periodontal tissues?
A. Gingival pocket
B. Periodontal pocket
C. Suprabony pocket
D. Infrabony pocket

The correct answer is A. Gingival pocket.

Deepening of the gingival sulcus may occur by coronal movement of the gingival margin, apical displacement of the gingival attachment, or a combination of the two processes.

Pockets can be classified as follows:

• Gingival pocket (pseudopocket): this type of pocket is formed by gingival enlargement without destruction of the underlying periodontal tissues. All gingival pockets are suprabony (the base of the pocket is coronal to the crest of the alveolar bone). The sulcus is deepened because of the increased bulk of the gingiva.

•Periodontal pocket: this type of pocket occurs with destruction of the supporting periodontal

tissues. Progressive pocket deepening leads to destruction of the supporting periodontal tissues and loosening and exfoliation of the teeth. 

Two types of periodontal pockets exist:

• Intrabony (infrabony, subcrestal, or intraalveolar): in which the bottom of the pocket is apical to the level of the adjacent alveolar bone

• Supra bony (supracrestal or supraalveolar): in which the bottom of the pocket is coronal to the underlying alveolar bone.

Source of mineralization for supragingival calculus

# The source of mineralization for supragingival calculus is:
A. Desquamated epithelial cells
B. Gingival crevicular fluid
C. Phosphatases formed by bacterial plaque
D. Saliva

The correct answer is D. Saliva.

Calculus is dental plaque that has undergone mineralization. It forms on the surfaces of

natural teeth and dental prostheses. Saliva is the source of mineralization for supragingival

calculus, whereas the serum transudate called gingival crevicular fluid furnishes the minerals

for subgingival calculus.

• Supragingival calculus: is located coronal to the gingival margin. ft is usually white or

pale yellow in color and is hard with a claylike consistency. It is easily removed by professional

cleaning. The two most common locations for supragingival calculus to develop are the buccal surfaces of the maxillary molars and the lingual surfaces of the mandibular anterior teeth. Saliva from the parotid gland flows over the facial surfaces of the maxillary molars through Stensen's duct, whereas the orifices of Wharton's duct and Bartholin's duct empty onto the lingual surfaces of the mandibular incisors from the submandibular and sublingual glands, respectively.

• Subgingival calculus: is located below the crest of the marginal gingiva. lt is typically hard and dense and frequently appears dark brown or greenish-black (due to exposure to gingival crevicular fluid) while being firmly attached to the tooth surface.

Bone composition

# Bone consists of:
A. Two-thirds organic matter and one-third inorganic matrix
B. One-third organic matter and two-thirds inorganic matrix
C. One-half organic matter and one-half inorganic matrix
D. Two-thirds inorganic matter and one-third organic matrix

The correct answer is D. Two thirds inorganic matter and one-third organic matrix.

Bone consists of two-thirds inorganic matter and one-third organic matrix. The inorganic matrix

is composed principally of the minerals calcium and phosphate, along with hydroxyl, carbonate, citrate, and trace amounts of other ions, such as sodium, magnesium, and fluoride. The mineral salts

are in the form of hydroxyapatite crystals and constitute approximately two-thirds of the bone

structure.

The organic matrix consists mainly of collagen type l (90%), with small amounts of noncollagenous

proteins such as osteocalcin, osteonectin, bone morphogenetic protein, phosphoproteins, and proteoglycans.