Retention behavior of double-crown attachments with zirconia primary and secondary crowns

详细信息    查看全文

• 作者：Franz Sebastian Schwindling ; ^{Sebastian.Schwindling@med.uni-heidelberg.de" class="auth_mail" title="E-mail the corresponding author} ; Thomas Stober ; Rainer Rustemeier ; Marc Schmitter ; Stefan Rues
• 关键词：Partial denture ; Permanent dental restoration ; Dental abutments ; Zirconium oxide ; Retention
• 刊名：Dental Materials
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：32
• 期：5
• 页码：695-702
• 全文大小：1578 K

文摘

To investigate whether adequate retention of zirconia conical crown (CC) attachments can be achieved, and to investigate their long-term retention.

Methods

Sixteen individual zirconia primary crowns were produced with convergence angles of 1° or 2° (eight of each). After determination of the convergence angles of the primary crowns, monolithic zirconia secondary crowns were manufactured. To evaluate the retention behavior of all-zirconia CC, the crowns were fitted with forces from F = 12.5–100 N. Force magnitudes during the loosening process (L) were then measured. L/F ratios were recorded and the coefficient of friction (μ₀) was calculated. Long-term retention was tested with up to 50,000 cycles of denture integration at a speed of 30 mms⁻¹ and a fitting force magnitude of 53 N.

Results

Even when primary crowns were manufactured with the utmost care, the real convergence angles were greater than the nominal angles of the standardized burs (1° and 2°) by 0.28° (SD 0.11°). Without mechanical aging, mean L/F was 0.632 (SD 0.038) for 1° samples and 0.526 (SD 0.022) for 2° samples, indicative of high retentive forces of up to 63.2% of the fitting forces. When all the test results were used, best-fitting curves gave μ₀ = 0.117 for new samples and μ₀ = 0.126 for samples after 50,000 integration cycles.

Significance

When the correct milling and sintering parameters are chosen, the retention behavior of zirconia CCs is adequate and stable. This innovative type of attachment is appealing because of the beneficial properties of zirconia and the efficient CAD/CAM-based manufacture.