Oral Health Group
Feature

Self Learning Assessments

September 1, 2001
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, 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 33

Which of the following cements has the highest retention value?

A. Adhesive resinC. Polycarboxylate

B. Glass ionomerD. Zinc oxyphosphate

Rationale

A recent study which examined the retention values of the above demonstrated, in descending order, adhesive resin (highest value), glass ionomer, zinc oxyphosphate and polycarboxylate.

Retention of crowns and bridges is affected by film thickness of the luting agent, which in turn is influenced by the seating force as well as the mixing technique. Dynamic seating methods are recommended over static methods of loading when placing the restoration. Ultrasonic vibration also can improve the seating method, but care must be taken not to prolong such action.

Of the four cements listed, polycarboxylate is the most soluble and the least retentive. Polycarboxylates are, however, biocompatible and readily bond chemically to natural tooth substance.

An ideal luting agent should be biocompatible, inhibit plaque, and resist microleakage. It should also be impervious to oral fluids, have low shrinkage, and offer good adhesive retention.

REFERENCES

1.Jones, D.W. Dental cements: a further update. J Can Dent Assoc 64:788-789. 1998.

2.Rosenstiel, S.F., Land, M.F., Crispin, B.J. Dental luting agents: a review of the current literature. J Prosthet Dent 80:280-301. 1998.

QUESTION 34

Using guided tissue regeneration as the treatment modality, in which of the following would you expect favourable results?

1.A two-wall intrabony defect.

2.A three-wall intrabony defect.

3.A Class II furcation.

4.A Class III furcation.

A.1, 2, 3D.4 only

B.1 and 3E.All of the above.

C.2 and 4

Rationale

Research indicates that Class II furcations and two or three walled vertical interproximal and circumferential intrabony defects will provide predictably good results. However, Class III furcations have not yielded satisfactory results by this method.

Guided tissue regeneration (GTR) is a technique introduced in 1986 by Nyman. The aim of the technique is to allow regeneration of fibroblastic attachment to the tooth root and to induce osteoblastic reformation of the bony socket while at the same time preventing downgrowth of epithelial cells from the crevice and attached gingiva. The size of the bony defect does not contraindicate treatment. Thorough access, debridement, and removal of toxic non-vital root cementum is a prerequisite. This may include the use of citric acid treatment of the root. Since fibroblast and osteoblast regeneration take up to six weeks for the reformation of new periodontal membrane and alveolar bone, Goretex membranes must remain in place as a barrier to epithelial cell invasion for approximately 6-8 weeks. During this time, the patient must refrain from mechanical hygiene methods to keep the area plaque free. Instead, Peridex mouthrinses two to three times a day are advocated, along with antibiotic coverage for three weeks, e.g., doxycycline 100 mg qid. After six to eight weeks, the area is reentered surgically, the Goretex membranes removed carefully, and the flaps closed.

A recent study (1999) demonstrated the effectiveness of this method of treatment on abutment teeth required for fixed partial dentures. The study follow-up of 4-8 years showed evidence of one third more bone support and reduced pocket depth as well as improved clinical attachment.

In a study comparing resorbable and non-resorbable membranes (1997), no significant differences could be demonstrated in the treatment results of vertical intrabony defects. It should be noted, however, that in a more recent study (1999), adverse effects consistent with a foreign body reaction were observed in patients treated with resorbable GTR devices.

REFERENCES:

1.Cortellini, P., Stalpers, G., Pini Prato, G. et al. Long term clinical outcomes of abutments treated with guided tissue regeneration. J Prosthet Dent 81:305-311, 1999.

2.Weltman, R., Trejo, P.M., Morrison, E. et al. Assessment of guided tissue regeneration procedures in intrabony defects with bioabsorbable and non-resorbable barriers. J Periodontol 68:582-591, 1997.

3.Tatakis, N.D., Trombelli, L. Adverse effects associated with a bioabsorbable guided tissue regeneration device in the treatment of human gingival recession defects. A Clinicopathologic case report. J Periodontol 70:532-547, 1999.

QUESTION 35

Which of the following are properties of resin-modified glass ionomer cements (RMGIC)?

1.Ability to bond chemically to the tooth.

2.Suppression of bacterial growth.

3.A coefficient of thermal expansion equivalent to tooth substance.

4.Increased pulpal sensitivity compared to amalgam.

A.1, 2, 3

B.1 and 3

C.2 and 4

D.4 only

E.All of the above

Rationale

Glass ionomer cements have properties excellent for restorative care, including a coefficient of thermal expansion similar to that of natural tooth structure. They bond both physically and chemically to enamel and dentin and can release fluoride. They have been shown to reduce bacteria at restoration sites, and have demonstrated ability to promote increased fluoride uptake in adjacent tooth structure.

A recent study of Class II restorations compared resin-modified glass ionomer cements to conventional amalgam. At six-month, one-year, two-year, and three-year recalls, restorations were examined. Statistically, no differences were shown between the materials with respect to fracture or sensitivity. There was, however, less demineralization at the cavity margins in the teeth restored with RMGIC.

Another study of Class II restorations comparing composite resins, fluoridated and non-fluoridated, with RMGIC, has shown that the surfaces of teeth adjacent to the RMGIC were less demineralized.

REFERENCE

1.Donly, K.J., Segura, A., Kanellis, M., et al. Clinical performance and caries inhibition of resin-modified glass ionomer cement and amalgam restorations. JADA 130:1459-1466, 1999.

2.Donly, K.J., Segura, A., Wefel, J.S., et al. Evaluating the effects of fluoride-releasing dental materials on adjacent interproximal caries. JADA 130:817-825, 1999.

3.Oral Care Report, Vol. 9 No. 3. Ed. C.W. Douglass, 1999.

QUESTION 36

Crowding of mandibular incisor teeth can result from

1. increased arch length.

2. retrusion of incisors.

3. impacted third molars.

4. growth changes in adolescents.

A. 1, 2, 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All of the above

Rationale

A recent conference of the American Association of Oral and Maxillofacial Surgeons came to some interesting conclusions.

Crowding of incisors is multifactorial. Decreased arch length, tooth size and shape, retrusion of incisors, as well as growth changes in adolescents are all potential causes. There is no evidence that incisor crowding is caused by third molars.

REFERENCE

1.Bishara, S.E. Third molars: A dilemma! Or is it? Am J Orthod Dentofacial Orthop 115:628-633, 1999.

2.Oral Care Report, Vol. 9 No. 3. Ed. C.W. Douglass, 1999.

Answers for August 2001 SLSA questions:

29. D 30. E 31. C 32. A