Oral Health Group

Self Learning Assessment 2005 (April 01, 2005)

April 1, 2005
by Oral Health

The SLSA program is based on current, referenced literature and consists of 40 questions, answers, rationales and references. Answers appear at the end of each quiz.

Dentists who complete the 15 question quiz in the November, 2005 issue of Oral Health may be eligible to receive continuing education points. The names and license numbers of all who complete the quiz will be forwarded to their respective provincial licensing authorities.



Nightguard vital bleaching of teeth using 10 percent carbamide peroxide can

1. remove intrinsic and extrinsic stains from teeth.

2. cause pulpal sensitivity.

3. alter the mineral content of the enamel.

4. decrease the microhardness of the enamel.

A. 1, 2, 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All of the above


Evaluations of home bleaching with 10 percent carbamide peroxide in a nightguard over a 14-day period have shown increased sensitivity of the teeth, which was transient. No adverse effects were detected on the gingiva or the periodontium. Although pulpal sensitivity of teeth can occur, the problem can be offset by use of a 5 percent solution of potassium nitrate applied to the teeth prior to the whitening process.

Tooth bleaching is an efficient, safe and effective method for removal of most intrinsic and extrinsic stains. In the presence of saliva, 10 percent carbamide peroxide releases 3 percent hydrogen peroxide and 7 percent urea. Hydrogen peroxide becomes ionized and free radicals diffuse through the interprismatic substance of the enamel to convert pigmented carbon rings to chains which are lighter in colour. If higher concentrations of carbamide peroxide are used, the whitening process speeds up. However, the acidic property of the bleaching agents causes changes in the mineral content of the enamel and the higher the concentration the greater the change. With the 10 percent carbamide peroxide, an initial decrease in enamel microhardness is recorded, followed by an increase due to remineralization from saliva.

A further study on tooth whitening has shown that ultraviolet light, halogen light or laser will augment the effect of the peroxide agent, increasing the speed of the bleaching process.


1.Basting, R.T., Rodriguez, A.L., Serra, M.C. The effects of seven carbamide peroxide bleaching agents on enamel microhardness over time. JADA 134:1355-1342, 2003.

2.Tavares, M., Stultz, J., Newman, M., et al. Light augments tooth whitening with peroxide. JADA 134:167-175, 2003.

3.Goodland, R., Gilchrist, H., Place, L. Tooth whitening: a cosmetic dentistry bonanza, Part I. Oral Health, April 76-95 2004.


In the endodontic treatment of a maxillary lateral incisor, you have enlarged the canal to the diameter of a No. 40 instrument. For best biochemical cleansing of the apical area, you would flush the canal with

A. 3% hydrogen peroxide using an end venting irrigation needle.

B. 1.25% sodium hypochlorite (NaOCl) with an end venting irrigation needle.

C. 5.25% NaOCl with a side venting irrigation needle.

D. ethyl alcohol followed by 5.25% NaOCl heated to 60C with a side venting irrigation needle.


The use of overproof ethyl alcohol enhances the penetration of the follow-up irrigants to penetrate both the root canal system and the dentinal tubules. It is further shown that deeper penetration of the canal system results from use of side venting irrigation needles with diameters as small as 0.032 inch.

End venting irrigation needles, on the other hand, have a reputation for injecting solutions under pressure, resulting in pain, edema and haematoma following extrusion of NaOCl into the soft tissues.

Hydrogen peroxide as an irrigant has been long out of favour. It does not deal with organic debris in the manner of NaOCl, which removes pulpal remnants, debris and predentin. Furthermore, chlorine derivatives disinfect and are bactericidal against Gram-negative bacteria.

Although 2 percent chlorhexidine will remove debris and disinfect as well as 1.25 percent NaOCl, recent work shows that 5.25 percent NaOCl is best, especially when heated to 60-70EC prior to use, as this enhances the chemical activity.


1.Serota, K.S., Nahmias, Y., Barnett, F., et al. Predictable endodontic success: the apical control zone. Oral Health. Oct:75-89, 2003.

2.Wolcott, J. Single visit vs. Multiple visit endodontics. Which is best? Compendium 23:232-234, 2002.


Recurrent Herpes Simplex Labialis may be triggered by

1. illness.

2. psychological stress.

3. exposure to sun.

4. physical trauma.

A. 1, 2, 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All of the above


Recurrences of herpetic simplex labialis (HSL), manifesting as cold sores, can continue throughout life. After primary infection with herpes simplex virus 1, the virus ascends the sensory nerve axons and establishes chronic latent infection in various neural ganglia (trigeminal, facial and vagus), as well as in tissues such as the epithelium of the lips. The dormant virus awaits a “trigger” to reactivate it. Triggers may include exposure to sun, psychological stress, onset of menses, illness and trauma, e.g., dental treatment. Some patients experience prodromal symptoms, such as burning, tingling, itching at the site where the lesion later occurs, whereas in others the lesion occurs immediately after the trigger. Currently available therapies have not been particularly effective in reducing symptoms or promoting healing once the lesion has formed.

For adults with established lesions, systemic or topical agents are recommended. Acyclovir 400mg twice daily, or Famciclovir 500mg three times daily can be prescribed. Topical agents such as 5 percent Acyclovir cream five times daily or one percent Penciclovir cream every two hours may be used alone or in conjunction with the systemic agent. Where dental treatment is the trigger, you should prescribe, 24 hours before treatment, Acyclovir 400mg twice daily, or Famciclovir 500mg twice daily.


1.Spruance, S.L., Nett, R., Marbury, T., et al. Acyclovir cream for the treatment of herpes simplex labialis: results of two randomized, double-blind, vehicle-controlled, multicenter clinical trials. Antimicrob Agents Chemother; 46(7) 2238-43, 2002.

2.Raborn, G.W., Grace, M.G.A. Recurrent herpes simplex labialis: selected therapeutic options. J Can Dent Assoc. 69:498-503, 2003.


Packable composites

1. provide tighter interproximal contacts than conventional composites.

2. have all the clinical properties of amalgam.

3. are quicker to use than conventional composites.

4. are high density resin-based.

A. 1, 2, 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All of the above


Success with use of resin-based composite restorative materials has been challenged because of the difficulty in bonding to a dentin surface with a “wet” tubular structure. Introduction of the total etch technique plus newer developments of dentin adhesive chemistry have improved bonding strengths and resistance to almost match enamel bonding. New adhesives also allow two approaches for the clinician to deal with the dentin smear layer either the total etch or the self-etch technique. The self-etch method reduces the steps and does not remove the smear layer. It is argued this method reduces the tendency to post-operative sensitivity. However, over a six-month test period, no difference between either method was detected.

Packable or high-density resin-based composites have been developed to give the clinician some of the properties of amalgam for restorations in posterior teeth of the Class II type. Although argument is made that faster placement and tighter interproximal contacts can be made in restorations with t
he packable material, a twelve-month study did not support this. Physical properties of wear resistance, hardness, fracture resistance and general strength, as well as polymerisation shrinkage, were equivalent to conventional resin-based composites.


1.Perdigo, J. Geraldeli, S., Hodges, J.S. Total-etch versus self-etch adhesive: effect on post-operative sensitivity. JADA 134:1621-1629, 2003.

2.Yip, K. H.K., Poon, B.K.M., Chu, F.C.S., et al. Clinical evaluation of packable and conventional hybrid resin-based composites for posterior restorations in permanent teeth. JADA. 134:1581-1589, 2003.


Answers to the March 2005 SLSA Quiz

9. A

10. C

11. A

12. A

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