Gurkan Goktug’s research while affiliated with Boston University and other places

Precision attachments have been used for many years to retain removable partial dentures (RPDs). Common reasons for a failed attachment-retained RPD are fracture of the framework, fracture of the roots or teeth, and irretrievable decrease of retention. When an RPD framework major connector has been fractured, it should be remade. This article describes a technique to remake a fractured mandibular RPD using cast round profile attachment analogs without the need for replacement of the fixed partial denture.

Abstract The most frequent mechanical complications of the bar-implant-retained overdentures are loosening of the bar screws and the need to reactivate the retentive clips. This article describes a technique to construct a new maxillary overdenture to a non-retrievable round-profile implant connecting bar with two distally placed attachments. The retainer round-profile bar was non-retrievable due to a worn retaining screw head. Attachment transfer analogs are utilized to transfer the position of the attachments to the master cast. The technique allows the clinician to construct new overdentures without the need for removal of the implant connecting bar and reduced chair- side time, treatment cost and increased patient-satisfaction are the major advantages of the technique.

Color matching between a restoration and natural teeth is a common clinical problem. Despite careful shade selection, color of the restoration may be affected by fabrication procedures. The purpose of this study was to determine the color changes of an all-ceramic restoration with 2 different veneering porcelain shades after repeated firings. Twenty disc-shaped ceramic specimens, 4 mm in diameter with a 1-mm core thickness and 2 different veneering porcelain shades (A1, A3), were fabricated from a zirconia-based porcelain (DC-Zirkon) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed for the specimens, and color differences (DeltaE) were determined using a spectrophotometer. Repeated measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Tukey HSD test and paired 2-tailed tests were performed for multiple comparisons (alpha=.05). The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.001) and the veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and veneering porcelain shade for L* (P=.003) and b* (P=.042) values, but not for the a* value (P=.82). An increase in the number of firings of the specimens with both A1 and A3 veneering porcelain shades produced an increase in the L* value, resulting in lighter specimens (P<.001). For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in more green specimens (P=.002). The b* value did not change after repeated firings (P=.09) for the A1 veneering porcelain shade; however, it increased for the A3 veneering porcelain shade, which resulted in more yellow specimens (P=.001). The color of the all-ceramic specimens with different veneering porcelain shades is influenced by repeated firings. However, color changes that occurred are clinically acceptable.

Misaligned implants may affect the esthetic, phonetic, and functional results and challenge the restorative dentist. Proper attachment selection is important considering the patient-related circumstances. This article presents a case where a change in prosthetic attachments was required because implant inclination diminished overdenture retention and stability. The treatment involved an alternative implant and soft-tissue impression technique.

It can be difficult to achieve superior esthetics in implant-supported fixed partial dentures (FPDs). Zirconia ceramics with high flexural strength and esthetic can be treatment options for implant-supported FPDs. This article describes a simple and reliable method to fabricate a retrievable cemented implant-supported zirconia FPD.