This is the first study that concurrently investigates shockwave and laser lithotripsy on human and artificial stones. Before using a super-hard plaster in this study, artificial stones made of materials such as the plaster of Paris and Begostone were already used in lithotripsy research [12, 13]. However, their acoustic and physical properties have not been fully characterized yet. The super-hard plaster used in this study is easily obtainable. It is the strongest dental plaster. It has the advantage of being stable, with a low expansion rate and a smooth surface due to its refined manufacturing process, which can minimize the formation of bubbles.

While some lithotriptors have been introduced to the market, there have been instances where hard stones remain unfragmented. When the laser is set at the same energy and frequency and irradiated for the same duration, hard stones produced at a mixing ratio of 15:3 with a lower moisture content are hardly fragmented, while soft stones formed at a mixing ratio of 15:12 with a higher moisture content are easily fragmented [14]. Recognizing the necessity of representing hard stones, we aimed to create and validate artificial stones capable of mimicking hard stones, which could be utilized alongside ESWL and laser lithotripsy. In particular, since stones tend to exhibit greater hardness at their core than at the surface, evaluating the fragmentation efficacy of lithotriptors on hard components is crucial for their assessment. Stones form when minerals precipitate and become saturated in the urinary tract, resulting in the formation of microscopic particles that nucleate and aggregate from the center, leading to growth [6]. Therefore, this study focused on obtaining pure COM stones, either 100% or 95%, from human subjects, aiming to compare and analyze them. The fragmentation capacity of less dense stones must be studied. Still, suppose one can effectively break harder stones, it may be more crucial to devise a protocol that can reduce the energy requirement, thereby fragmenting less dense stones to a consistent level. Such settings pose no clinical concerns as long as the lithotriptor provides a stable energy output.

Previous studies have examined the feasibility of artificial stones made from Begostone in ESWL and laser treatments separately. Using BEGO stones, the efficacy and safety of high-frequency shock wave lithotripsy have been measured in a porcine model [15] and the lithotripsy efficacy of thulium Fiber Laser has been evaluated by assessing variations in laser settings using a kidney phantom [16]. This study demonstrates the possibility of creating artificial stones for testing and validating both ESWL and laser treatments simultaneously using only a mixture of plaster and water. Depending exclusively on compressive strength measurements, using a push-pull gauge to evaluate the feasibility of laser fragmentation may not provide accurate assessments of the density or hardness of stones. Therefore, utilizing Vickers hardness tests or densitometry methods is a more suitable methodology [11]. A noteworthy observation was the correlation between results of transverse and longitudinal wave speed analysis for assessing the feasibility of ESWL and outcomes of laser fragmentation results. Therefore, to evaluate lithotriptor performance, two protocols could be employed: one involving the production of very hard stones with a low moisture content ratio of 15:3 and the other aimed at creating softer stones by increasing the moisture content to a ratio of 15:6. Testing the lithotriptor with these two protocols would be appropriate.

While not presented in this study’s findings, the inconsistency observed in the measured stone density at 10 mm and 15 mm was a crucial aspect in the fabrication of artificial stones. This inconsistency was attributed to irregular air bubble formation during preparation, which could disrupt stones’ homogeneity. Larger sizes may lead to inconsistent results in stone characteristic measurements in the fabrication of artificial stones. To minimize the presence of bubbles, artificial stones should be manufactured to a thickness of approximately 5 mm. A degassing chamber is imperative.

The primary limitation of this study was the limited number of stone fragmentation experiments and physical characteristics assessment. However, excluding 10 mm and 15 mm stones from the analysis yielded consistent results, highlighting the importance of establishing a protocol for creating 5 mm stones and performing degassing. The second limitation of this paper was its inability to delineate the manufacturing methods of artificial stones for each constituent in detail.