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.

Dental Water irrigation devices

# Water irrigation devices (oral irrigators) have been shown to:
A. Eliminate plaque
B. Clean nonadherent bacteria and debris from the oral cavity more effectively than toothbrushes and mouth rinses.
C. Disinfect pockets for up to 12 hours
D. Prevent calculus formation

The correct answer is B. Clean nonadherent bacteria and debris from the oral cavity more effectively than toothbrushes and mouth rinses.

Oral irrigators for daily home use by patients work by directing a high-pressure, steady or pulsating stream of water through a nozzle to the tooth surfaces. Most often, a device with a built-in pump generates the pressure. Oral irrigators clean nonadherent bacteria and debris from the oral cavity more effectively than toothbrushes and mouth rinses.

When used as adjuncts to toothbrushing, these devices can have a beneficial effect on periodontal

health by reducing the accumulation of plaque and calculus and decreasing inflammation and pocket depth.

Oral irrigation has been shown to disrupt and detoxify subgingival plaque and can be useful in delivering antimicrobial agents into periodontal pockets. Note: Daily supragingival irrigation with a dilute antiseptic, chlorhexidine, for 6 months resulted in significant reductions in bleeding and gingivitis compared with water irrigation and ch1orhexidine rinse controls. Irrigation with water alone also reduced gingivitis significantly, but not as much as the dilute chlorhexidine.

Important: Oral irrigators may be contraindicated in patients requiring antibiotic premedication

prior to dental treatment since these devices have the potential for causing bacteremia. The patient's physician should be consulted.

Remember: The pathology associated with gingivitis is completely reversible with the

removal of plaque and the resolution of the inflammation.

In implantology, countersinking means:

# In implantology, "countersinking" refers to the process of:
A. Flaring or enlarging the coronal end of the osteotomy
B. Reversing the engine to remove the implant
C. Placing the implant in a counterclockwise rotation
D. Torquing the abutment to place

The correct answer is A. Flaring or enlarging the coronal end of the osteotomy.

As one of the final steps in the creation of the osteotomy to receive the implant body, a special bur is activated and inserted into the occlusal end of the osteotomy in order to increase the diameter of the opening slightly or to otherwise shape it. This step is referred to as "countersinking." Countersinking the implant osteotomy is called for by some manufacturers to compensate for very dense cortical bone or to prepare the bone for a particular implant shape (e.g., a flared implant shape at the coronal end).

Another of the final steps in the creation of the osteotomy is to place a threaded bur into the osteotomy so as to create a spiral groove on the wall of the osteotomy. This groove is placed so as to receive and guide the threads on the side of the implant during surgical placement and thus minimize the torque required and to minimize heat. This process of creating the groove on the inside of the osteotomy wall is referred to as "tapping" the osteotomy.

All of the burs used to create the osteotomy are used at relatively slow speeds (r.p.m.) to prevent injury to the bone, especially overheating of the bone. Also, water or saline irrigation is used to cool the burs and the bone during drilling.