## 4 Results
### Numerical Evaluation of the Motors  
The proposed image processing approach combined with the defined experimental scenario and camera configurations can precisely account the movement of the assessed motors. The text file containing the positions of the red dot and the center of the disc is valuable as input data for any algorithm, since they also express a temporal significance row by row. For the implemented algorithm, the computation of angular distances (engaging and disengaging angles) and RPM is performed and displayed as an output, along with the graphical exhibition of the visual module as presented in Figure 4. In this context, the results for three popular reciprocating motors are presented and discussed in this subsection.  
With the introduction of the reciprocating motion, the need for new electric motors appeared. Nowadays, there are several commercially available dedicated motors to perform the reciprocating movement that can be classified into three types: closed motors, closed-but-adjustable motors and open motors. The closed motors are devices that only execute previously recorded reciprocating movements and do not allow update or modification of their kinematics. The closed-but-adjustable devices perform only recorded reciprocating movements registered in their libraries but, through an update, can be upgraded to new kinematics following well-defined rules. Finally, the open motors can be partially or totally programmed to operate in different movements by setting clockwise and counter-clockwise angles, torque and speed. For these groups of motors, while closed and closed-but-adjustable motors offer a reciprocating movement in which the cutting is in a counterclockwise direction, completing a total rotation after three consecutive cycles (in opposition to continuous rotation motors in clockwise direction), the open motors allow more flexibility when defining the way the motors will operate, although proper configuration may be a complex and time consuming task.  
In this defined scenario, three popular endodontic reciprocating motors were assessed. The first of them, VDW.COLD\({}^{\text{\textregistered}}\)RECIPROC\({}^{\text{\textregistered}}\)(VDW Gold) is a popular closed-but-adjustable endodontic all-in-one motor that bundles other services such as a precise length determination tool for the tooth's root being treated (for canal preparation), being suitable for preparation in traditional rotary (only one rotation direction) and reciprocating mode. The second motor, VDW.CONNECT Drive\({}^{\text{\textregistered}}\)(VDW Connect) is a closed-but-adjustable cordless motor for canal treatment for both continuous rotation and reciprocating movement. The third assessed motor is the Woodpecker\({}^{\text{\textregistered}}\)Ai-Motor, a open cordless reciprocating motor that promises to deliver the same services and performance of other popular motors, while being cheaper.  
The same acrylic disc with a red dot was attached on each of the assessed reciprocating motors, with the support of a contra-angle. Then, the same camera setting and positioning was adopted, as defined in the assessment scenario setting. For the group of generated images, the proposed method was applied resulting in the computation of the desired parameters. Table 1 presents the achieved results after the execution of the proposed method.