NDAEB Preventive Dental Procedures 2 — Questions and Answers

Question 1: When applying dental sealants, what is the most critical factor that determines sealant retention on the tooth surface?

The brand of sealant material used
Complete isolation and dry field during application (Correct answer)
The patient's age at time of application
The color of the sealant material

Correct answer: Complete isolation and dry field during application

Moisture contamination is the primary cause of sealant failure. The etched enamel surface must remain completely dry during sealant application for proper bonding and long-term retention.

Dental sealant retention depends almost entirely on achieving and maintaining a dry, contamination-free enamel surface. The procedure involves: (1) cleaning the tooth surface (pumice or air abrasion), (2) isolating with cotton rolls or rubber dam, (3) acid etching for 15-30 seconds (creating microscopic enamel porosities), (4) rinsing for 15-20 seconds, (5) drying thoroughly (etched enamel should appear frosty white), (6) applying sealant into pits and fissures, and (7) light curing. If saliva contacts the etched surface at any point before sealant placement, the etch pattern is compromised and the surface must be re-etched. Studies show that sealants have a 90%+ retention rate at one year when properly placed with adequate isolation, but this drops dramatically with moisture contamination. The dental assistant's role in maintaining the dry field through effective suction and cotton roll management is critical to success.

Question 2: Which type of toothbrush bristle is recommended by the Canadian Dental Association for most patients?

Hard bristles for maximum plaque removal
Soft or extra-soft bristles (Correct answer)
Medium bristles as a compromise
Natural boar bristles for environmental sustainability

Correct answer: Soft or extra-soft bristles

The Canadian Dental Association recommends soft or extra-soft bristled toothbrushes for most patients, as they effectively remove plaque while minimizing the risk of gingival recession and enamel abrasion.

Soft or extra-soft bristled toothbrushes are recommended because they flex adequately to clean along the gumline and into the gingival sulcus without causing tissue trauma. Hard and medium bristles, especially when combined with aggressive horizontal brushing technique, can cause gingival recession (exposing root surfaces to caries and sensitivity), cervical abrasion lesions (notches at the gumline), and enamel wear. The recommended brushing technique is the modified Bass technique: bristles are angled 45 degrees toward the gumline, with short back-and-forth vibrating strokes followed by a rolling motion away from the gumline. The toothbrush should be replaced every 3-4 months or when bristles become frayed. Electric toothbrushes with oscillating-rotating heads have been shown to be more effective than manual brushing for many patients and are particularly beneficial for those with limited dexterity.

Question 3: A patient asks about the difference between dental prophylaxis and scaling and root planing. What is the key distinction?

There is no difference; they are the same procedure
Prophylaxis is a preventive cleaning for healthy patients; scaling and root planing is a therapeutic procedure for periodontal disease (Correct answer)
Prophylaxis uses only hand instruments while scaling uses ultrasonic devices
Prophylaxis is more expensive than scaling and root planing

Correct answer: Prophylaxis is a preventive cleaning for healthy patients; scaling and root planing is a therapeutic procedure for periodontal disease

Dental prophylaxis is a preventive cleaning performed on patients with healthy periodontium or gingivitis, while scaling and root planing (SRP) is a therapeutic procedure to treat periodontal disease by removing calculus and diseased tissue from root surfaces.

This distinction is clinically and legally important in Canadian dental practice. Prophylaxis (prophy) is performed on patients with generally healthy periodontium or mild gingivitis. It involves supragingival and minimal subgingival scaling to remove calculus and plaque, followed by polishing. It is a preventive procedure typically performed every 6-12 months. Scaling and root planing (SRP) is a non-surgical periodontal therapy for patients diagnosed with periodontal disease (4+ mm pocketing with bone loss). SRP involves meticulous subgingival instrumentation to remove calculus, bacterial toxins, and diseased cementum from root surfaces, usually performed by quadrant under local anaesthesia. SRP is often followed by re-evaluation at 4-6 weeks to assess healing. The dental assistant should understand this distinction when scheduling patients, preparing tray setups, and explaining procedures to patients.

Question 4: What is the recommended concentration of sodium fluoride in professional fluoride varnish used in Canadian dental practice?

0.05% (225 ppm F)
1.1% (5,000 ppm F)
5% (22,600 ppm F) (Correct answer)
0.2% (900 ppm F)

Correct answer: 5% (22,600 ppm F)

Professional fluoride varnish contains 5% sodium fluoride, delivering 22,600 ppm fluoride. This high concentration is safe because the varnish sets on the tooth surface and releases fluoride slowly over hours.

Fluoride products used in dentistry come in various concentrations for different applications. Professional fluoride varnish (5% NaF = 22,600 ppm F) is the highest concentration used and is applied by dental professionals. It adheres to the tooth surface and releases fluoride slowly, making it effective and safe despite the high concentration. Other concentrations include: prescription home-use toothpaste (1.1% NaF = 5,000 ppm), in-office fluoride tray treatment (1.23% APF = 12,300 ppm), daily-use fluoride rinse (0.05% NaF = 225 ppm), and weekly fluoride rinse (0.2% NaF = 900 ppm). Regular over-the-counter toothpaste contains 0.243% NaF (1,100 ppm). The dental assistant should understand these concentrations when discussing home care recommendations with patients and when preparing professional fluoride applications. Fluoride varnish has become the preferred professional application method in Canada due to its ease of use, reduced risk of ingestion, and strong evidence base for caries prevention.

Question 5: During patient education about interdental cleaning, when should the dental assistant recommend interdental brushes over traditional dental floss?

Never; dental floss is always superior
When the patient has open interdental spaces, dental implants, orthodontic appliances, or bridges (Correct answer)
Only for patients over 65 years of age
Only when the patient refuses to floss

Correct answer: When the patient has open interdental spaces, dental implants, orthodontic appliances, or bridges

Interdental brushes are more effective than floss for patients with open embrasure spaces, around implants, under bridge pontics, and with orthodontic brackets, as they provide better surface contact in these situations.

Current evidence, including systematic reviews cited by the Canadian Dental Association, shows that interdental brushes are at least as effective as floss for plaque removal and may be superior in many situations. They are specifically recommended for: (1) patients with open interdental embrasures (common in periodontal patients with bone loss), where floss slides through without contacting tooth surfaces; (2) around dental implants, where the wider embrasure space and need to clean the abutment surface favor a brush; (3) under fixed bridge pontics, where a brush can access the tissue surface; (4) with orthodontic brackets and wires, where threading floss is impractical. The correct size must be selected - the brush should fit snugly without force. For patients with tight, healthy contacts and no open spaces, traditional floss remains appropriate. The dental assistant plays a key role in assessing each patient's interdental anatomy and recommending the most effective cleaning tool.

Question 6: What is the primary mechanism by which fluoride prevents dental caries?

It kills all bacteria in the oral cavity
It enhances remineralization by incorporating into the tooth structure as fluorapatite, which is more acid-resistant than hydroxyapatite (Correct answer)
It whitens teeth, making stains less visible
It increases saliva production

Correct answer: It enhances remineralization by incorporating into the tooth structure as fluorapatite, which is more acid-resistant than hydroxyapatite

Fluoride's primary caries-preventive mechanism is enhancing remineralization. When fluoride is present during remineralization, it incorporates into the enamel crystal structure as fluorapatite, which is more resistant to acid dissolution than the original hydroxyapatite.

Fluoride prevents caries through three main mechanisms: (1) Enhancement of remineralization: When fluoride ions are present in saliva during the remineralization process, they incorporate into the repaired enamel crystal as fluorapatite [Ca10(PO4)6F2], which has a lower critical pH (~4.5) than hydroxyapatite (~5.5), making the repaired enamel more acid-resistant. (2) Inhibition of demineralization: Fluoride adsorbed onto the enamel surface reduces the rate of mineral dissolution during acid attacks. (3) Antibacterial effects: At higher concentrations, fluoride inhibits bacterial metabolism by interfering with the enzyme enolase in the glycolytic pathway, reducing acid production by cariogenic bacteria. The remineralization enhancement is considered the most important mechanism, which is why topical fluoride exposure (toothpaste, rinses, professional applications) is more effective than systemic fluoride for caries prevention in erupted teeth.

NDAEB Preventive Dental Procedures 2

When applying dental sealants, what is the most critical factor that determines sealant retention on the tooth surface?