Effect of image sharpening on radiographic image quality.

STATEMENT OF PROBLEM: The image sharpening algorithm, unsharp masking (USM), may cause artifacts that reduce the diagnostic value of digital images. It may create overshoot artifacts that can be misdiagnosed as pathosis or prosthesis misfit. The effect of this image sharpening and the extent of overshoot artifacts on image quality requires investigation. PURPOSE: The purpose of this in vitro study was to evaluate the effect of USM on digital dental radiographic quality and to demonstrate the extent of overshoot artifacts. MATERIAL AND METHODS: Three digital sensors (2 complementary metal-oxide-semiconductors and 1 photostimulable phosphor) were exposed using a digital dental quality assurance imaging phantom to evaluate contrast resolution, spatial resolution, and dynamic range. The 3 sensors were again exposed without the phantom to determine the degree of radiographic noise. Each image was sharpened and then highly sharpened. Overshoot was measured, and images were compared using the Friedman 2-way ANOVA analysis. RESULTS: Image sharpening significantly affected spatial resolution and noise. Conversely, dynamic range and contrast resolution were not significantly affected by image sharpening. Overshoot artifacts increased with image sharpening. CONCLUSIONS: Image sharpening improves visual image quality but significantly increases overshoot artifacts that adversely affect radiographic diagnosis. Data from this study indicate that image sharpening causes artifacts that could negatively affect accurate diagnosis.

A Protocol for Screw-Retrievable, Cement-Retained, Implant-Supported Fixed Partial Dentures.

Longevity of implant-supported fixed partial dentures (ISFPDs) may be associated with multiple clinical complications, irrespective of whether retention is achieved via screws or cement. While use of screws ensures ease of prosthesis retrievability and elimination of the inherently risky cementation process, more mechanical strains are induced in this design. A combined screw-retrievable and cement-retained ISFPD is designed to achieve the best passive fit and strain reduction while allowing complete excess cement removal and maintaining ease of retrievability. Moreover, this approach suggests better protection of the cement layer from oral environment degradation and offers scope for an alternative retention protocol. This paper outlines aspects of the clinical indications and fabrication of a screw-retrievable, cement-retained ISFPD. A diagnostic assessment method that provides tactile resistance guidance for selection is also proposed.

Diagnostic Classification and Design Considerations for Implant-Supported Fixed Partial Dentures and Screw Access Channel: The ABC/PBC and SAC Classifications.

Logical categorization of implant-supported fixed partial dentures (ISFPDs) based on implant angulation, abutment type, and screw access channel (SAC) design for screw-retained restoration is not available in the literature. This article proposes a simple classification system to describe implant angulations and prosthesis design affecting abutment selection (engaging or nonengaging) for ISFPDs. An additional classification that addresses screw access channel designs is also introduced. These classifications provide clear interpretation of clinical scenarios for ISFPD design consideration and a basis for categorization of future complications. The angulation-based and prosthetic-based classifications simplify communication regarding implant angulation and prosthesis design type for ISFPDs. The SAC classification assists in prosthetic design, factoring in function and esthetics when designing the screw access.