Proteinases play a key rôle in the physiological degradation and remodelling of the periodontal tissues. The rôle of these enzymes in tissue remodelling remodelling in connection with the insertion of dental endosseous implants has not been elucidated. Therefore, the aim of the present study was to identify the eventual presence of collagenase, gelatinase and elastase activities in periimplant sulcus fluid (PISF) of osseointegrated implants. Gelatinolytic activity in the samples was studied with gelatin-zymograms. Collagenase activity and its susceptibility to tetracycline-inhibition were monitored with SDS-polyacrylamide gel electrophoresis and laser densitometry, and elastase activity with synthetic substrate. Low activities of elastase and collagenase were detected in both PISF of osseointegrated implant patients and gingival crevicular fluid (GCF) of the control patients whereas significantly higher activities were detected in GCF of adult periodontitis patients. Also the profiles of gelatinases were similar in PISF of osseointegrated implant patients and GCF of the controls, but differed from the profile of active gelatinases present in GCF of adult periodontitis patients. The similar activities/characteristics of these proteinases in both periimplant sulcus fluid of healthy dental implants and GCF of healthy natural teeth suggest that they comprise the major proteinases for both periodontal and periimplant tissue remodelling or destruction.

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The potential uses of enamel bonding sealants and composite filling materials in increasing the retentive form of abutment teeth and covering the preparations for the occlusal supports of partial prostheses were studied in laboratory conditions. The materials tested were Nuva and Concise sealants and composite resins. Extracted permanent human molars, premolars and canines were inserted into acrylic blocks, two teeth in each block. An unretentive clasp framework was made on every test block. A retention prominence was built up separately of sealants and of composite materials occlusally to the tip of each clasp arm. The bond strength and wear resistance of the materials was tested in a device designed for this study. The bond of the prominences was very good, only two out of 114 prominences loosened. The retention gained with prominences was, on average, 18 N measured by the force needed for removal. The decrease in the total retention of the four clasp arms was measured by the force needed to remove the clasp framework. The total retention of the prominences made of Nuva and Concise sealants after 5000 removals was 53 and 50% of the original, when long, flexible clasp arms were used. The corresponding figures for composite resins were 56 and 59%. Short rigid clasp arms caused a distinctly faster abrasion. The prominences made of sealants, in particular, were abraded rapidly, one-fifth of retention being left after 3000 removals.

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