Effect of metal artefact reduction level on the assessment of dental implant positioning by cone-beam computed tomography.

OBJECTIVES: This study evaluated the effect of metal artefact reduction (MAR) level and tube current on the assessment of dental implant positioning relative to the mandibular canal (MC) through cone-beam computed tomography (CBCT). METHODS: Titanium dental implants were placed in dried mandibles at 0.5-mm superior to the MC (group 1/n = 8) and 0.5-mm inside the MC with perforation of the cortex (group 2/n = 10). CBCT scans were obtained with different levels of MAR (off, medium, and high) and 2 tube currents (4 and 8 mA). Four examiners analysed the images and scored the contact between the implant and the MC using a 5-point scale. Sensitivity, specificity, area under receiver operating characteristic curve (ROC), and frequency of scores were calculated. Data were compared with analysis of variance 2-way and Tukey's test and scores with Chi-square test. RESULTS: Specificity and area under ROC curve decreased significantly when MAR level was high compared with MAR-medium and MAR-off. The frequency of score 3 (inconclusive) was the highest, and scores 1 and 5 (definitely no contact and definitely contact, respectively) were the lowest with MAR-high, regardless of the tube current. When MAR was off, there were higher frequencies of scores 1 and 5. CONCLUSIONS: The level of MAR influences the assessment of the relationship between the dental implant and the MC. MAR-high led to lower diagnostic accuracy compared with MAR-medium and off. ADVANCES IN KNOWLEDGE: This article shows that high level of MAR can interfere in the diagnostic of dental implant positioning relative to the MC, decreasing its accuracy.

Digital photography vs. clinical assessment of resin composite restorations.

PURPOSE: To compare direct clinical and indirect digital photographic assessment of resin composite restorations. Ninety-two posterior resin composite restorations were classified using World Dental Federation (FDI) criteria by two different clinical examiners (C1 and C2). In the same appointment of clinical assessment, intraoral high-quality digital photographs were taken and posteriorly two different digital examiners (D1 and D2) classified the images of each restoration. Restorations of each patient were assessed once by C1 and C2 independently. D1 and D2 assessed the digital images from different locations and in different time. Data were analyzed using the Cohen's kappa coefficient, Kruskal-Wallis non-parametric test and Dunn's multiple shared test, with 95% confidence. Agreement levels varied from very good (0.81-1.00) to fair (0.21-0.40). Statistically significant differences (p < 0.05) between assessments were found for surface lustre, staining, color match and translucency, esthetic anatomical form, fracture of material and retention and marginal adaptation. The classification of the resin composite restorations varied significantly according to clinical or high-quality digital photographic assessments. Overall, clinical assessment detected more demand for repair or replacement.