Objective: Oscillating ultrasonic instruments were basically used to finish marginal preparation, while they produce more rough surfaces, unlike the regular surfaces produced by the rotating diamond instruments. This study aims to investigate the change of dentin roughness after etching using two different preparation tools: diamond bur and diamond ultrasonic tip.
Materials and Methods: Two groups of dentin surfaces related to extracted premolars were considered: the first group consisted from 13 surfaces prepared with a Rotating Diamond Bur (RB-P), the second group consisted of 13 surfaces prepared with oscillating tip (O-P). For all surfaces, the roughness were measured using an optical profilometer microscope once after preparation and thereafter etching with phosphoric acid (35%) for 20 seconds. Two samples were imaged under scanning electronic microscope SEM only after the preparation.
Surface roughness RMS, Developed Interfacial Area Ration (Sdr) and Surface Development were compared using 1-way ANOVA test, Kruskal-Wallis and ANOVA for Ranks test, respectively.
Results & Discussion: Preparation with oscillating tip produced the highest value of roughness (O-P: 3.22 ± 0.73), while there was difference in roughness after the etching procedure (E_O-P: 2.27 ± 0.262) at P_value = 0.046 < 0.05. The etching procedure did not result a valuable change in the roughness in the Rotating Bur Preparation group before (RB-P: 2.72 ± 0.41) and after etching (E_RB-P: 2.39 ± 0.42) at P_value = 0.514 > 0.05. SEM images shows more irregular surface with deeper grooves on the dentinal surface in the O-P group. The highest value of Sdr is associated with the O-P group (0.71± 0.14) resulting the best adhesion.
Conclusion: Etching the dentin surface with phosphoric acid affected the roughness. The effect was more noticeable when the surface is prepared with oscillating ultra-sonic tip. The choice of the preparation tool should depend only which tool is the least traumatic instrument for the marginal periodontal tissues.
Roughness; Dentin; Rotating bur; Oscillating ultra-sonic tip; Optic 3d profilometer; Etching; adhesion; Sdr.