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, 2009 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 9
A combination of daily tooth brushing and an antimicrobial mouthrinse results in a higher interproximal plaque reduction than daily brushing and flossing.
A combination of daily tooth brushing and flossing is the best way to reduce interproximal plaque.
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
Dental floss is only used by a small portion of the population on a daily basis. Therefore, an easy alternative is needed. Such an alternative could be a mouthrinse with antimicrobial activity for daily use. A study was conducted to evaluate the efficacy of two mouthrinses in reducing interdental plaque and gingivitis compared to dental floss. Inclusion criteria were such that no subjects with good oral hygiene under normal conditions were included in the study. Subjects were randomly assigned to four groups: 1) brushing and rinsing (0.06% chlorhexidine and 0.025% fluoride); 2) brushing and rinsing (0.1% cetylpyridiniumchloride and 0.025% fluoride; 3) tooth brushing and flossing; 4) toothbrushing only. At baseline, the modified proximal plaque index (MPPI) and papillary bleeding index (PBI) were recorded. Thereafter, subjects had to brush with a silica based toothpaste in the usual manner over an eight week period. Additionally, test groups had to rinse once a day or floss once daily. After four and eight weeks, indices were recorded again and improvements calculated. Reductions for all indices were found in all groups.
However, with respect to the MPPI, mouthrinse groups performed better than the control and floss groups and this was statistically significant. The PBI showed no difference between the groups. The results showed that in combination with tooth brushing, daily use of a mouthrinse can result in a higher interproximal plaque reduction than daily flossing.
REFERENCE
1. Zimmer, S., Kolbe, C., Kaiser, G. et al. Clinical efficacy of flossing versus use of antimicrobialrinses. JPeriodontol 77:1380-1385,2006.
QUESTION 10
In endodontics, an electronic apex locator is contraindicated for use in a patient with an implanted cardiac pacemaker.
Use of an electronic apex locator will cause interference with an implanted defibrillator.
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
Manufacturers of electric pulp testers and electronic apex locators warn against the use of these devices in patients with implanted cardiac pacemakers. Such warnings are based on speculation of potential risk of electromagnetic interference rather than on scientific evidence. A study was conducted on patients with implanted cardiac pacemakers and implanted cardioverter/defibrillators to determine the effects of these devices. Patients had continuous electrocardiogram monitoring and device interrogation to detect interferences.
Pacemakers correct bradycardia or abnormal heart rate by stimulating (pacing) the heart. Defibrillators function to correct cardiac arrhythmias and many of these have incorporated pacing functions that allow them to treat patients with both bradycardias and tachycardias.
Evaluation of the electrocardiograms of each patient in the study failed to show any abnormalities in pacing during testing. The investigators concluded that both devices are safe.
REFERENCE
1. Wilson, B. L., Broberg, C., Baumgartner, JC et al. Safety of electronic apex locators and pulp testers in patients with implanted cardiac pacemakers or caridioverter/defibrillators. JOE 32 : 847 -852, 2006.
QUESTION 11
When compared to a rapid injection, a slow administration of an inferior alveolar nerve block
1. is more comfortable.
2. results in faster onset of anesthesia.
3. produces less tissue damage.
4. produces more effective anesthesia.
A. 1, 2, 3
B. 1 and 3
C. 2 and 4
D. 4 only
E. All of the above.
Rationale
Many factors can influence the success of an inferior alveolar nerve block. A randomized double blind crossover design study was carried out to compare the efficacy of slow and rapid nerve block in securing pulpal anesthesia in the mandibular teeth. After negative aspiration 2 ml of 2% lidocaine with 1 : 80,000 epinephrine was given, either slowly over 60 seconds or rapidly over 15 seconds. To blind the patient to the procedure, the needle remained in place for 45 seconds before depositing the solution in the case of rapid injection. Pulp sensitivity was determined with an electric pulp tester using the first molar, first or second premolar and lateral incisor. Pulp testing was then repeated every two minutes for the first 10 minutes and then at 5 minute intervals for 45 minutes post injection. Comfort of injection, onset of pulpal anesthesia and depth of anesthesia were assessed. Results showed that there was less discomfort associated with a slow injection which was statistically significant. Slow injection produced more episodes of no pulp response than rapid injection in first molars, premolars and lateral incisors. The onset of pulpal anesthesia was faster in molars and premolars compared to lateral incisors although no difference was found between molars and premolars. Dentists should be aware that slow injection results in less tissue damage, faster onset of anesthesia, deeper anesthesia and is more comfortable for the patient.
REFERENCE
1. Kanaa, M. D., Meechan, J. G., Corbett, I. P. et al. Speed of injection influences efficacy of inferior alveolar nerve blocks: a double-blind randomized control trial in volunteers. JOE 32 : 919 -922, 2006.
QUESTION 12
When applied to a prepared cavity for a composite resin restoration 2% chlorhexidine solution results in
1. bacteriocidal action.
2. a reduction in post operative pain.
3. delayed degradation of the hybrid layer.
4. improved bond strength.
A. 1, 2, 3
B. 1 and 3
C. 2 and 4
D. 4 only
E. All of the above.
Rationale
Discomfort or pain after restorative treatment has been attributed to the proliferation of bacteria in the space between dentine and the restorative material. 2% chlorhexidine solution by antimicrobial action reduces the bacterial content and therefore post operative pain. It should be noted that adhesion to dentine by hydrophilic resins occurs through infiltration and polymerization of the resin within the “collagen mesh” exposed by acid decalcification. This forms the so called “hybrid layer.” Such adhesion degrades over time. The degradation is initiated by metalloproteinase enzymes (MPP) found in the saliva and dentine. Chlorhexidine acts as an inhibitor of MPP activity. A recent study has also shown that 2% chlorhexidine digluconate (Bisco cavity cleanser) applied after acid etching reduces the rate of degradation of the hybrid layer. No improvement in bond strength was observed after chlorhexidine treatment and further work is in progress.
REFERENCE
1. Brackett, W. W., Tay, F. R., Brackett, M. G. et al. The effect of chlorhexidine on dentin hybrid layers in vivo. Operative Dentistry 32, 107-111, 2007.
Answers to the February 2009 SLSA questions:
5. E
6. A
7. D
8. C
