Computed vs. film-based radiographs' contour artifacts influence diagnosis of secondary caries.

To test local grey-scale changes on dental bitewing radiographs near filling margins for image acquisition. Forty approximal preparations in caries-free amalgam filled teeth and bitewing radiographs were acquired under standardized conditions applying four techniques. Film-based analog radiographs were digitized using flat-bed scanner (FDR). Phosphor-plate computed radiographs (PCR) were directly acquired by scanning VistaScan imaging plates. Image quality was tested using Preset Filter (PF) or manually applied IntraOral Fine Filter (IF) to enhance digital images. Local changes from digital imaging processing were assessed by comparing the margin-near (MN) and margin-far (MF) zone by a multivariate repeated measurements analysis. All images were acquired with 8-bit depth (256 shades). Dentine was displayed in 79 shades for FDR and 54 shades for PCR. PF or IF locally modify bitewing radiographs by darkening marginal dentine by 8 or 29 shades, respectively. The sharpest display of the margin (shades per pixel) from dentine to filling was found for IF (26.2), followed by FDR (23.2), PF (15.3) and PCR (8.3). Computed radiography with phosphor plates generate more homogeneous images compared to flatbed-digitized film-based radiographs. The filling margin was sharpest represented with the IF filter at the detriment of an artificial darkening of the dentine near the margin of the filling. Contour artifacts by filters have the potential to confound diagnosis of secondary caries. Algorithms and filters for sensor data processing, causing local changes above 2% of the dynamic range by non-continuous mathematical functions, should only be applied with caution, manually when diagnosing and reversibly.

A Comparative Assessment of Three Mandibular Retention Protocols: A Prospective Cohort Study.

PURPOSE: Fixed retainers have been advocated for the prevention of anterior mandibular crowding after orthodontic treatment. However, limited data is available to help clinicians choose a retention protocol that is acceptable in terms of stability, emergencies, and side effects in the long term. It was the aim of this study to assess survival and alignment stability of the 0.016" x 0.022" stainless steel wire compared to more common protocols. MATERIALS AND METHODS: Three different mandibular fixed retention protocols were compared in 600 consecutive patients: 1. 0.0215" multistrand wire (MW) with separate curing of resin and composite; 2. 0.016" x 0.022" stainless-steel wire with simultaneous curing of resin and composite (SS1C); and 3. 0.016" x 0.022" stainless-steel wire with separate curing of resin and composite (SS2C). The hazard rate for detachment across wire groups was assessed with a Cox frailty model. RESULTS: Incisor alignment was maintained with all retention wires. One incisor with unexpected torque change was observed in group MW. The average annual emergency rate was below 2% for all three protocols. Fewer emergency visits were found in patients with solid steel wires than with multistrand wires. Detachment of the wire is the most common cause of emergency visits with no difference between wire types. Multistrand wires were more often damaged than were solid steel wires. There was no evidence that direct application of the composite on the uncured primer influenced retainer adhesion to the enamel. CONCLUSIONS: The mandibular anterior teeth can be predictably stabilised with a 0.016" x 0.022" stainless steel wire..