The effect of adding chlorhexidine on the compressive strength of provisional crown made of three-dimensional printed polymethyl methacrylate

Abstract

Background/Aims: making temporary crowns are an essential part of prosthodontic treatments. As a fact that using digital technology is increasing and there are few studies on the mechanical properties of temporary crowns printed with PMMA and mechanical behavior of these resins were not studied in presence of antimicrobial agents, these study was executed with purpose of evaluating the effect of adding chlorhexidine on the compressive strength of provisional crown made of three-dimensional printed polymethyl-methacrylate.

Method/Materials: In this in vitro study, 22 temporary crowns were made using special resin on second premolar of maxilla with 3D printer. For making standard samples, an intact second premolar of maxilla was scanned with pre-operative model way, till the external surface of temporary crown were made exactly upon it. Then putty index was made using compressive silicone for preparing the tooth for making full coverage crown by a prosthodontist. At the next level, the prepared tooth scanned and the files were aligned with the exact size of unprepared premolar. Then files transferred to software to complete designing stages. Material used in this study was PMMA. after finishing the design, files were transferred to 3D printer. Temporary crowns were printed in two groups of chlorhexidine 2% weight resin DETAX and simple resin DETAX. Prepared tooth molded with compressive silicone and metal cast was made. Samples were tested in universal testing machine(Hounsfield H5K5).samples were locating on metak casts and force with the speed of 1mm/min applied on the central fissure of temporary crown with a round chisel with diameter of 3mm and force were recorded when the crown was spliced. Average and standard deviations were analyzed using SPSS 26 and T-test. The significant level of this study was P<0.05 .

Results: The average compressive strength of crowns with antimicrobial agent was 49/2 Kg/cm2, however the average compressive strength of crowns without antimicrobial agent was 48/6 Kg/cm2. Results showed that there is no significant statistical difference between using antimicrobial agents and not using them in temporary crowns made with 3D printer (P>0.05).

Conclusion: The results of this study showed that chlorhexidine has no significant effect on the compressive strength of temporary crowns made with PMMA and can be used as a safe agent in disinfecting these crowns.