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, 2001 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 29
Disinfection of water lines will inhibit bacterial growth in the biofilm and effluent for up to
A. 2 days
B. 5 days
C. 10 days
D. 15 days
E. 20 days
Rationale
Although recommendations to flush all waterlines for two minutes or more at the start of a clinic day and before each patient visit will reduce numbers of bacteria from the waterlines by 96-98%, this nevertheless, does not dislodge biofilm which is a perfect medium for bacterial colonization. Flushing merely washes off bacteria which reside on the surface of the biofilm.
A recent investigation with disinfectant compounds has found that disinfection of waterlines will inhibit bacterial growth in the biofilm and effluent for up to 15 days. Common microbes rapidly recolonize because of the presence of the biofilm matrix. Daily treatment of waterlines with the disinfectants will be effective in keeping bacteria within the lines below cultivable levels, but the disinfectants will not disrupt the biofilm matrix and rapid recolonization occurs when disinfectant treatment is discontinued. However, the disinfectants will prevent pathogen transmission from the biofilm, and it is the pathogenic bacteria, which are of concern in crossinfection.
REFERENCES
1.Meiller, T.F., DePaola, L.G., Kelley, J.I., et al. Dental unit waterlines: biofilms, disinfection and recurrence. JADA 130:65-72, 1999.
2.Roberts, H.W., Karpay, R.I., and Mills, S.E. Dental unit waterline antimicrobial agents’ effect on dentine bond strength. JADA 131:179-183, 2000.
3.Barbeau, J., Gauthier, C., Payment P. Biofilms, infectious agents, and dental unit waterlines: a review. Can J Microbiol 44:1019-28, 1998.
QUESTION 30
In the management of conditioned dentine for an adhesive restoration, a primer will
1. saturate the dentine with hydrophilic monomers.
2. seal the dentinal tubules.
3. cause hybridization of the dentine.
4. prevent postoperative sensitivity.
A. 1, 2, 3
B. 1 and 3
C. 2 and 4
D. 4 only
E. All of the above
Rationale
Dessication of dentine causes postoperative sensitivity. The successful outcome of adhesive restorations is dependent upon the application technique and this in turn relies on the understanding of the solvent used in the primer. Three types of solvents are identified to dissolve the primer hydrophilic monomers: water, alcohol, and acetone. The purpose of the primer is to saturate with hydrophilic monomers the demineralized zone of dentine caused by acid etching. In addition, the primer plugs the dentinal tubules with the monomers. If not completely saturated, postoperative sensitivity is likely to result and therefore underpriming must be avoided. The primer should replace the mineral removed from the dentine by acid conditioning and cause a layer of “plastic” to form, i.e., hybridization.
To apply a primer correctly, the clinician must select an application method which best suits the primer’s solvent. Water-based primers by reducing the possibilities of dentine dehydration, are the least technique-sensitive. Alcohol-based primers are next, and acetone-based primers have the highest risk of overdrying the dentine.
To avoid postoperative sensitivity due to dehydration, after the matrix is placed for a restoration, you should
confine the acid etchant to and within the cavo surface margins
wash off the acid
withdraw excess moisture with high volume suction — do not blow air into the cavity
apply primer and inspect for a surface sheen which indicates that the tubules have been plugged by plastic (hybridized).
reapply primer if surface sheen is not apparent.
REFERENCE
1.Jackson, R., Soll, J. The importance of technique in eliminating postoperative sensitivity. Oral Health, July 71-75, 1999.
QUESTION 31
Biologic width is related to the connective tissue attachment.
Management of gingivitis must precede the preparation of an anterior full crown.
A. The first statement is true, the second is false
B. The second statement is true, the first is false.
C. Both statements are true.
D. Both statements are false.
Rationale
Biologic width describes location and dimension of the connective tissue attachment. Donovan (1998) states that, at the time of margin placement and impression taking, one of the most important factors in predictability of result is to ensure that the gingival tissues are free of any inflammation. It is essential that, in tooth preparation, as little damage as possible to gingival tissue occurs. Gentle pre-packing of the gingival sulcus with retraction cord prior to margin cutting will prevent such injury.
Magne (1999) supported this technique with retraction cord using minimal pressure and trauma to respect the biological width of the periodontium. Well-adapted and contoured provisional restorations between visits are further demanded in the soft tissue care.
REFERENCES
1.Donovan, T.E., Cho, G.C. Soft tissue management with metal-ceramic and all ceramic restorations. J Calif Dent Assoc 26(2): 107-112. 1998.
2.Magne, P., Magne, M., Belser, U. The esthetic width in fixed prosthodontics. Oral Health, Nov. 25-38. 1999.
QUESTION 32
Uprighting a tipped molar will
1. lead to favourable coronal positioning
2. reduce a mesial bony defect
3. improve the connective tissue attachment
4. decrease a furcation lesion
A. 1, 2, 3
B. 1 and 3
C. 2 and 4
D. 4 only
E. All of the above
Rationale
A recent review (1999) confirms that extrusive movement of a tooth with one- or two-wall bony pockets will lead not only to a more favourable positioning of the crown of the tooth, but also to more favourable coronal positioning of the connective tissue attachment, with resultant shallowing of the bony defect. Such movement and benefits are seen in uprighting tipped molars. When a furcation involvement is present, such extrusive orthodontic movement tends to increase the periodontal problem.
REFERENCE
1.Saunders, N.L. Evidence-based care in orthodontics and periodontics: a review of the literature. JADA. 130: 521-527, 1999.
Answers for July 2001 SLSA questions:
25. E 26. C 27. E 28. C
