C-Factor impact and class II direct restoration success: 1 year analysis using complex digitally improved research model

Abstract

To verify the potential impact of the C-factor and its subcomponents on the clinical success of Class II direct composite restorations by using a complex digitally-improved research model. During caries treatment 64 Class II cavities were prepared among patients of University Dental Clinic (Uzhhorod National University, Ukraine). Each prepared cavity was scanned by Medit i500 intraoral scanner (MEDIT corp., Seoul, Korea). The second scanning procedure was provided after direct composite restoration placement with its further contouring, polishing and occlusal correction. Obtained pairs of *.stl-files were imported into Autodesk Meshmixer software (Autodesk Inc., San Rafael, CA, USA), and pair-wised analyzed in means of exact cavity volume, the surface area of the cavity walls, width, length, and height of each cavity, exact filling volume, objectified C-factor value. Mean 1-year success rate for Class II restoration by the USPHS criteria was 90.71±4.27%, while no statistically significant correlation was registered between C-factor value (C=2) and registered level of composite direct restoration success (р > 0.05). Meanwhile, the statistical association was established (р < 0.05), when the C-factor was objectified as the ratio of absolute surfaces’ areas (Cmean=2.71±0.54) based on obtained digital scans. Geometrical subcomponents of C-factors, such as depth of cavity (р < 0.05) and restoration volume (р < 0.05) also demonstrated statistically augumented relations with clinical success of fillings after 1-year of monitoring. Digitally-improved research model helped to establish the clinically valuable level of inter-relations between C-factor subcomponents and success of direct composite Class II restorations, while the analog investigational approach has not supported prominent evidence regarding such interdependence.