The SLSA program is based on current, referenced literature and consists of 40 questions, answers, rationales and references. Answers appear in the following issue at the end of each quiz.
Dentists who complete the 15 question quiz in the November, 2006 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.
QUESTION 21
A daily rinse of 15 ml 0.2% sodium fluoride will reduce cervical caries incidence significantly.
Root caries is localized destruction of dentine and cementum with S. mutans in higher numbers than lactobacili.
A. The first statement is true, the second is false.
B. The first statement is false, the second is true.
C. Both statements are true.
D. Both statements are false.
Rationale
Root caries is a localized destruction of dentin and cementum in which lactobacilli are found in higher numbers than S. mutans. Lesions can be found at the cemento-enamel junction or confined entirely to the exposed root surface, especially in the elderly where gingival recession, a common finding, makes the root vulnerable.
Although depletion of saliva increases the risk to caries, aging per se has no significant effect on salivary secretion. Many medical problems of the elderly are managed with drugs which induce xerostomia, with caries as a secondary effect. Also, on exposed root surfaces, a higher plaque index with poor oral hygiene predisposes to increased root caries.
Caries progression or reversal is determined by the balance between protective and pathological factors. Fluoride, a key agent in battling caries, works primarily in root caries by the topical mechanisms of mineralization, enhancement of remineralization and inhibition of bacterial enzymes. Although chlorhexidine mouthwashes have been claimed effective in countering the bacterial challenge of root caries, a recent study comparing chlorhexidine mouthwash with that of fluoride rinses over a two-year period showed that although chlorhexidine reduces lactobacilli and S. mutans in older mouths it would appear to decrease in effectiveness over time. However, a daily rinse of 15 ml of 0.2% NaFl gave a significant reduction in caries incidence over the two-year test period.
REFERENCES
1.Wyatt, C.C.L., MacEntee, M.I. Caries management for institutionalized elders using fluoride and chlorhexidine mouthrinses, Community Dent. Oral Epidemiol. 32:322-328, 2004
2.Featherstone, J.D.B. The science and practice of caries prevention. ADA Council on Scientific Affairs. JADA 131:887-889, 2000.
QUESTION 22
Problems relating to natural teeth with overdentures are
1. periodontal disease.
2. caries.
3. tooth fracture.
4. alveolar bone loss.
A. 1, 2, 3D. 4 only
B. 1 and 3E. All of the above
C. 2 and 4
Rationale
With overdentures using natural teeth, a recent study has shown that the rate of loss of abutment teeth over a 20-year period was 20%. The majority of loss occurred over the first 10 years, with periodontal disease the main cause and caries the next. Maintaining adequate hygiene is an essential, both for control of caries and periodontal bone loss. Another identified problem was vertical root fractures of overdenture abutments, especially in the maxilla where abutments were opposed by natural teeth. It is recommended that thimble crowns be placed on abutment teeth to reduce the risk of vertical fractures. More fractures occurred in men than women.
The study also showed that preservation of the health of overdenture teeth requires the use of a high concentration of fluoride gel (5000 ppm) daily. Plaque should be removed effectively and recall appointments should be at least on an annual basis.
REFERENCE
Ettinger, R.L., Qian, F. Abutment tooth loss in patients with overdentures. JADA 135:739-746, 2004.
QUESTION 23
Beta blockers, when taken systemically,
1. inhibit calculus formation.
2. alter salivary composition.
3. increase the risk of cervical caries.
4. reduce salivary flow.
A. 1, 2, 3D. 4 only
B. 1 and 3E. All of the above
C. 2 and 4
Rationale
Studies have shown that beta-blocker medication has an inhibitory effect on calculus formation and on re-formation after a prophylaxis. It would seem that diuretics have similar abilities. The mechanism involved is thought to relate to the drug being excreted into the saliva affecting the rate of crystallization of the physicochemical mechanism of calculus formation. An added feature of beta-blockers taken systemically is their ability to increase the risk of cervical caries, especially on exposed root surfaces. The mechanism associated with this is uncertain. The flow of saliva was not altered. Patients taking beta-blockers should therefore be screened regularly for cervical caries.
REFERENCE
Seymour, R.A., Preshaw, P.M., Thomason, J.M., et al. Cardiovascular diseases and periodontology. J Clin Periodontol 30:279-292, 2003.
QUESTION 24
Prior to radiotherapy, teeth located within the radiation fields should be carefully evaluated.
Radiotherapy-treated patients are more susceptible to fungal and bacterial infections.
A. The first statement is true, the second is false.
B. The first statement is false, the second is true.
C. Both statements are true.
D. Both statements are false.
Rationale
All teeth, but especially those located within the radiation fields, should be carefully evaluated prior to beginning radiation therapy for malignant disease of the head and neck.
Criteria used for dental extractions prior to radiation therapy are not universally accepted and are subject to clinical judgement, but factors that must be considered are the overall condition of the patient’s mouth (caries, periapical status, inflammatory periapical abnormalities), past dental care, current oral hygiene, the urgency of cancer treatment, the planned therapy (radiation fields and dose) and the prognosis for the patient (cure or palliation). For patients who show poor oral hygiene and evidence of dental neglect, extraction is the treatment of choice. The following are generally accepted as criteria for preradiotherapy extractions:
* Gross caries (non-restorable teeth)
* Active periapical disease (symptomatic teeth)
* Moderate to severe periodontal disease
* Lack of opposing teeth (compromised hygiene)
* Partial impaction or incomplete eruption
* Extensive periapical lesions (if not chronic or well localized)
Dry mouth (xerostomia) is a common and significant consequence of head and neck radiotherapy. Because of decreased saliva, patients are more susceptible to rampant caries, periodontal disease, fungal and bacterial infections. Systemic sialogogues may stimulate salivary flow if some residual functional gland tissue exists, as will sugarless gums and lozenges. Substances containing sugars or acids, e.g., lemons, to stimulate flow must be avoided as teeth will demineralize. Patients should apply a 1.1% neutral sodium fluoride gel daily (for at least five minutes) in a custom-fitted vinyl tray to prevent demineralization and caries, and must be instructed to maintain excellent oral hygiene.
REFERENCES
1.Epstein, J.B., Stevenson-Moore, P. Periodontal disease and periodontal management in patients with cancer. Oral Oncol 37:613-619, 2001.
2.Hancock, P.J. Epstein, J. Sadler, G.R. Oral and dental management related to radiation therapy for head and neck cancer. J Can Dent Assoc 69:585-590, 2003.
Answers to the May 2006 SLSA Questions
17. A
18. B
19. A
20. C
