Effect of cement line on radiographic detection accuracy of abutment-prosthesis misfit.

STATEMENT OF PROBLEM: Proper prosthetic fit is essential to prevent biofilm accumulation and inflammatory reactions in the peri-implant region. Early detection of misfit at the abutment-prosthesis interface is critical, and periapical radiography has been widely used for this purpose during treatment. However, whether the presence of a cement line influences the accuracy of the radiographic detection of misfit at this interface remains unclear. PURPOSE: To evaluate the influence of a cement line on the detection of abutment-prosthesis misfit of different magnitudes using the bisecting-angle and paralleling periapical radiographic techniques. MATERIAL AND METHODS: A total of 320 periapical radiographs obtained by the bisecting-angle and paralleling techniques were used to analyze 50-, 100-, and 150-µm simulated misfits between the abutment and the prosthetic crown. Three dentists evaluated the images using a 5-point confidence scale (definitely present, probably present, uncertain, probably absent, and definitely absent). Diagnostic accuracy, assessed by the area under the receiver operating characteristic curve (Az), sensitivity, and specificity, were analyzed using Generalized Linear Models (α=.05). RESULTS: Sensitivity was higher in the cemented groups, particularly for 50 µm (0.87 versus 0.48; P<.001), whereas specificity was higher in the noncemented groups across all techniques and misfit magnitudes (P<.001). Az values were significantly influenced by radiographic technique (P=.005), cementation (P=.035), and misfit magnitude (P<.001), with significant interaction effects between cementation and both technique (P<.001) and magnitude (P=.002). CONCLUSIONS: The presence of a cement line increases sensitivity but reduces specificity, favoring the detection of misfit at the expense of a higher rate of false-positive findings.