The assessment of the finish line in prepared teeth after troughing using multiple methods
Michał Lubaś, Damian Korczyński
„Miludent” Private Dental Practice, Jaslo, Poland
Objectives
The adequate gingival retraction with the double cord technique is crucial for taking high quality prosthetic impressions. The study aimed to check does the use of a 980 nm diode laser in combination with the double cord technique increase the retraction efficiency compared to the conventional technique.
Materials and Methods
The number of 26 teeth were prepared for prosthetic crown reconstruction. One week after the teeth preparation, the gingiva was retracted, before taking the impression, using following three methods: the classic method of double cord technique (Group 1, n=26); gingival troughing (Group 2, n=26) with 980 nm diode laser (Smart m PRO, Lasotronix, Poland) at 4.0 W ton: 20 ms, toff: 80 ms; combination of the diode laser troughing and double cord technique (Group 3, n=26). Retraction was performed under local anesthesia with 40 mg adrenaline and 0.005 mg articaine hydrochloride (Septodont, France). The impressions were taken using the same impression technique and the same impression materials: A-silicone, Bisico S1, and S4 (Bisico, Germany). The casting models from class 4 dental stone were fabricated and digitally scanned with the laboratory scanner Medit Identica (Media, Korea) The visibility of the preparation margin for each impression technique were compared with a computer software (Blender Institute, Holland). The lengths of the visible fragments of the preparation margin around a single abutment were summed up and the percentage of the total tooth circumference was calculated for each impression technique separately.
Results
The best visibility of the preparation area (99,52% of the tooth circumference) was obtained using a combined technique (double cord technique and laser throughing). The lower percentage of visibility of the prepared tooth margin amounted to 93,67%, and 76,12% of the tooth circumference were obtained for the two retraction cords (Group 1) or the laser troughing alone (Group 2), respectively.
Conclusions
The additional application of 980 nm diode laser improved the prosthetic impression quality and the visibility of the preparation margin.