NBDHE Test Dental Hygiene MCQ 1 — Questions and Answers
Question 1: Which type of tooth deposit is considered the primary etiologic factor in periodontal disease?
- Calculus (tartar)
- Dental plaque biofilm (Correct answer)
- Food debris
- Extrinsic stain
Correct answer: Dental plaque biofilm
Dental plaque biofilm is the primary etiologic factor in periodontal disease because it harbors the pathogenic bacteria that trigger the host inflammatory response leading to tissue destruction. Calculus is a secondary factor that retains plaque but is not itself the initiating agent.
Question 2: When exposing a periapical radiograph using the paralleling technique, the image receptor should be placed:
- Against the teeth being radiographed
- Parallel to the long axis of the tooth with a beam directed perpendicular to both (Correct answer)
- At a 45-degree angle to the occlusal plane
- As close to the lingual surface as possible without a holder
Correct answer: Parallel to the long axis of the tooth with a beam directed perpendicular to both
The paralleling technique requires the image receptor to be parallel to the long axis of the tooth, with the central ray directed perpendicular to both the tooth and the receptor. This minimizes geometric distortion and produces the most dimensionally accurate image.
Question 3: A patient asks how long they should brush their teeth. The evidence-based recommendation for toothbrushing time is:
- 30 seconds
- 1 minute
- 2 minutes (Correct answer)
- 5 minutes
Correct answer: 2 minutes
Two minutes is the evidence-based recommended brushing time endorsed by the American Dental Association. Studies show most people brush for less than one minute, which is insufficient for thorough plaque removal from all tooth surfaces.
Question 4: Which instrument is specifically designed for root planing and is characterized by a rounded back and toe?
- Sickle scaler
- Universal curette
- Area-specific curette (Correct answer)
- Hoe scaler
Correct answer: Area-specific curette
Area-specific curettes (Gracey curettes) are designed specifically for root planing with a rounded back and toe that allow safe adaptation to root surfaces without trauma to soft tissue. Their offset blade angle makes them ideal for subgingival instrumentation at specific tooth surfaces.
Question 5: Fluoride works primarily to prevent dental caries by:
- Killing all bacteria in the oral cavity
- Incorporating into the hydroxyapatite crystal structure to form fluorapatite, which is more acid resistant (Correct answer)
- Neutralizing dietary acids immediately after ingestion
- Increasing saliva flow to buffer acids
Correct answer: Incorporating into the hydroxyapatite crystal structure to form fluorapatite, which is more acid resistant
Fluoride prevents caries mainly by incorporating into tooth enamel during remineralization, forming fluorapatite, which is significantly more resistant to acid dissolution than the original hydroxyapatite. It also has some antibacterial properties and can enhance remineralization, but structural incorporation is its primary mechanism.
Question 6: During patient assessment, a probing depth of 4–6 mm with bleeding on probing and radiographic bone loss is classified as:
- Gingivitis
- Healthy periodontium
- Periodontitis (Correct answer)
- Necrotizing periodontal disease
Correct answer: Periodontitis
Periodontitis is characterized by probing depths exceeding 3 mm accompanied by clinical attachment loss, radiographic bone loss, and bleeding on probing. Gingivitis involves inflammation without attachment or bone loss, while a healthy periodontium shows neither inflammation nor bone loss.
NBDHE Test Dental Hygiene MCQ 1
Which type of tooth deposit is considered the primary etiologic factor in periodontal disease?