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Self-Learning, Self Assessment 2007 (March 01, 2007)

March 1, 2007
by Oral Health


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, 2007 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.

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QUESTION 9

The application of a hot pack to the skin of the face overlying the masseter muscle can

1. increase blood flow in the muscle.

2. decrease deoxygenated haemoglobin levels.

3. increase oxygen saturation levels.

4. increase heart rate.

A. 1, 2, 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All of the above

Rationale

Although it was always thought that the application of heat caused vasodilation and increased blood flow in deeper structures, it has been very difficult to prove. Recently non-invasive procedures have been developed which allow for measurement of total haemoglobin volume, deoxygenated haemoglobin volume, oxygenated haemoglobin volume and oxygen saturation levels. Using the masseter muscle, a study was conducted in two groups, one with the application of a hot pack heated to 55C and a control group with a sham application pack heated to 37C. Results showed that the blood flow only increased in the group with a hot pack heated to 55C. Total haemoglobin volume, oxygenated haemoglobin volume and oxygen saturation levels all increased significantly compared to the control group and the deoxygenated haemoglobin volume decreased significantly. There was no change in the heart rate in either group.

In temporomandibular disorders muscle pain due to fatigue is thought to be caused by a decrease in intramuscular blood flow. Therefore treatments that can improve blood flow are thought to be effective. Similarly in the management of infections, intraoral use of heat can help the resolution of the process by improving blood flow and bringing in the body’s defense mechanisms. As continuous heating may induce sweating and consequently vasoconstriction, local application of heat as therapy should be limited to 20 minute intervals.

REFERENCE

Okada, K., Yamaguchi, T., Minowa, K. et al: The influence of hot pack therapy on the blood flow in the masseter muscle. Journal of Oral Rehabilitation 32:480-486, 2005.

QUESTION 10

Non-caries induced dentin hypersensitivity at the cervical margin of teeth is a common problem. Which of the following treatments will give the best long-term result?

A. Varnish with stannous fluoride

B. Dentifrice with strontium chloride

C. Gluma desensitiser

D. One Step (one bottle bonding agent)

Rationale

Dentin hypersensitivity manifests as a short, sharp pain induced by thermal, tactile, chemical or air evaporative stimuli. Sensitive teeth have widely exposed dentin tubules and pain is attributed to the Brnnstrom hydrodynamic theory of dentinal fluid movement. A treatment concept of tubular occlusion is therefore logical, and all of the above agents work in this manner. Gels and varnishes with stannous or sodium fluoride and dentifrices with strontium chloride are effective in the short term. The bonding agent (One-Step) can cover the sensitive area, reduce tubule diameter and the resin layer formed will act as a mechanical barrier. However, gradual return of sensitivity is found, probably from loss of the resin layer. A recent study looked at long-term effects of Gluma Desensitiser and found that it was effective in sensitivity relief for at least 9 months after treatment. The gluteraldehyde content of the desensitizer precipitates the protein in the dentin tubules to a depth of 50 microns.

REFERENCE

Kakaboura, A., Rahiotis, C. , Thomaidis, S., et al. Clinical effectiveness of two agents on the treatment of cervical sensitivity. Am J Dent 18:291 -295, 2005.

QUESTION 11

Placement of posts in endodontically treated teeth will strengthen against fracture.

The main function of posts in endodontically treated teeth is to support a core if there is inadequate tooth substance left for a final restoration.

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

A recent review concluded that posts do not strengthen endodontically treated teeth. Instead it is believed that the preparation of the post space with further loss of tooth substance can weaken the tooth. Preservation of tooth structure to leave as much tooth dentin as possible is advocated and there should be a minimum of 1 mm of sound dentin around the post. An increase in post length with the diameter kept to a minimum will reduce shear stress and preserve root dentin.

Posts should only be used when there is insufficient tooth substance left for a final restoration, the function of the post being to retain a core for a coronal restoration. The most common core materials in current use are cast gold, amalgam, resin-based composite and glass ionomer cement. Gold and amalgam have high strength, low solubility and a coefficient of expansion similar to tooth substance. However, gold and amalgam are not esthetically pleasing especially for anterior tooth restorations. Resin based composite provides for this esthetic need and it has good strength and low solubility. However, polymerization shrinkage and incompatibility with ZOE in many root canal sealers can cause difficulties. Removal of residual sealer and incremental core build up using a condensable resin based composite can alleviate the problem. Glass ionomer cement is weak in tensile and compressive strength, has poor bonding to dentin and enamel and high solubility. It should, therefore, be avoided as a core build up material.

REFERENCES

1.Cheung, W.: A review of the management of endodontically treated teeth. JADA 136:611-619,2005

2.Fernandes, A.S., Sharat, S., Continho, I.: Factors determining post selection: A literature review. J Prosthet Dent. 90:556-562, 2003

QUESTION 12

Periodontitis is a potential risk factor for coronary heart disease (CHD).

Periodontitis is associated with an increased risk for stroke.

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

Periodontitis produces pathological periodontal pockets where bacterial infection persists and causes chronic inflammation serving as a reservoir for predominantly gram-negative bacteria. Although periodontitis is a potential risk factor for CHD, it has not been extensively evaluated in relation to cerebrovascular events (stroke) .An investigation of 6950 subjects over 13 years looked at whether elevated serum antibody levels to major periodontal pathogens were linked to stroke. For each case, two controls were matched for gender, age, municipality and disease status. The results of the study showed that chronic infection with A. actinomycetemcomitans and P. gingivalis is associated with an increased incidence of future stroke. Elevated serum IgA class antibody levels to A. actinomycetemcomitans were predictive of stroke. Elevated serum IgA class antibody levels to P. gingivalis were predictive of recurrent stroke among patients who had a previous history of stroke or CHD.

REFERENCE

Pussinen, P .J., Alfthan, G., Rissanen, H. et al: Antibodies to periodontal pathogens and stroke risk. Stroke 35:2020-2023, 2004.

Answers to SLSA Questions 5-8, February 2007 issue:

5. E

6. B

7. E

8. C


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