Single most important factor in producing cariogenic plaque

# The single most important factor in producing cariogenic plaque is:
A. High amount of glucose exposure
B. High frequency of glucose exposure
C. High amount of sucrose exposure
D. High frequency of sucrose exposure

The correct answer is: D. High frequency of sucrose exposure.

High-frequency exposure to fermentable carbohydrates such as sucrose may be the most important factor in producing cariogenic biofilm and ultimately caries lesions. Frequent ingestion of fermentable carbohydrates begins a series of changes in the local tooth environment, essentially changing the composition of the biofilm, thus favoring the growth of highly acidogenic bacteria that eventually leads to caries lesion formation. In contrast, when ingestion of fermentable carbohydrates is severely restricted or absent, biofilm growth typically does not lead to caries lesions.

Sucrose in particular allows the formation of extracellular polysaccharides, which render the biofilm viscous and sticky. Because the eventual metabolic product of cariogenic diet is acid, in addition to caries lesions the exposure to acidity from other sources (e.g., dried fruits, fruit drinks, or other acidic foods and drinks) also may result in dental erosion.

Liquid system of glass ionomer restorative material

# The liquid system of glass ionomer restorative material is essentially:
A. Polyalkanoic acid
B. Phosphoric acid
C. Polyacrylic-itaconic acid
D. Hydrochloric acid

The correct answer is C. Polyacrylic-itaconic acid.

COMPOSITION OF GLASS IONOMER CEMENTS

Powder/liquid materials

Powder -  Sodium aluminosilicate glass with about 20% CaF and other minor additives

Liquid - Aqueous solution of acrylic acid/itaconic acid copolymer or Aqueous solution of maleic acid polymer or maleic/acrylic copolymer and Tartaric acid in some products to control setting characteristics

Powder/water materials

Powder - Glass (as above) + vacuum-dried polyacid (acrylic, maleic or copolymers)

Liquid - Manufacturers supply a dropper bottle which the operator fills with water or The manufacturer supplies a dilute aqueous solution of tartaric acid

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.

Boundary of attached gingiva

# Which one describes the boundaries that define the attached gingiva?
A. From the gingival margin to the interdental groove
B. From the free gingival groove to the gingival margin
C. From the mucogingival junction to the free gingival groove
D. From the epithelial attachment to the cementoenamel junction

The correct answer is: C. From the mucogingival junction to the free gingival groove.

In an adult, normal gingiva covers the alveolar bone and tooth root to a level just coronal to the CEJ. The gingiva is divided anatomically into marginal, attached, and interdental areas.

- Marginal or unattached gingiva: is the terminal edge or border of the gingiva surrounding the

teeth in collar- like fashion. In about 50% of cases, it is demarcated from the adjacent attached gingiva by a shallow linear depression, the free gingival groove. Usually about 1 mm wide, the marginal gingiva fonns the soft tissue wall of the gingival sulcus.

- Attached gingiva: is continuous with the marginal gingiva. It is firm , resilient, and tightly bound

to the underlying periosteum of alveolar bone. The fac ial aspect of the attached gingiva extends to

the re latively loose and movable alveolar mucosa and is demarcated by the mucogingival junction.

" Stippling" of the attached gingiva refers to the irregular surface texture of the attached gingiva, similar to the surface of an orange peel. Stippl ing occurs at the intersection of epithelial ridges that causes the depression and the interspersing of connective tissue papillae between these intersections giving rise to the small bumps.