Surface roughness after manual and semi-automated-finishing of provisional resins

Objectives: Surfaces of dental restorations have to be smooth to prevent bacterial adhesion. This applies also to temporary crown and bridge materials (TCBM). However, little information is currently available about surface finishing of TCBM. Besides, comparisons between available studies are complicated, due to non standardized treatment procedures. It was therefore the purpose of this study to develop a semi automated set up to control speed, direction, machining time and grinding pressure of the finishing procedure and to compare it to manual finishing. Methods: Three different TCBM (Protemp™ 4/3 M Espe, USA, Luxatemp Automix Solar/DMG, Germany and Dentalon Plus/Heraeus Kulzer, Germany) were used to produce an overall of sixty planar specimens (10 mm diameter and 5 mm thickness). Thirty specimens were treated manually and thirty mechanically with three different consecutive finishing procedures (tungsten carbide cutter, acrylic polisher and polishing brush). After every single treatment step surface roughness (Rz) were assessed with a profilometer (MicroProf®/Fries Research Technology, Germany). Changes in surface roughness were calculated and subjected to a multivariate analysis of variance (p≤0.05). Results: The analysis showed that there was no significant difference between manual and semi automated surface finishing (Mean ± SD)(manual:Rz 5.12±1.03µm/ auto:Rz 4.99±1.10µm). Dentalon Plus exhibit the lowest surface roughness after multistep surface treatment (manual:Rz 1.01±0.19µm /auto:Rz 1.09±0.34µm). The highest surface roughness values in multi step treatment were determined for Protemp™ 4 (manual:Rz 2.91±0.6µm /auto:Rz 2.66±0.61µm). Conclusion: Within the limitations of the study it can be concluded that the developed semi automated finishing procedure is a viable means to standardize the surface preparation in TCBM for study purposes. Even more, the developed semi automated technique delivered results that were comparable to manual finishing in patients.