3D printing pens are often used to create beautiful, fun works of art, as well as for educational purposes, but they have also been found to be useful for medical applications. A trio of researchers from KM Shah Dental College and Hospital published an article, “3D printing pen: a new accessory for indirect bondingAbout their work using a 3D printing pen to create partial and complete transfer trays for indirect bonding of orthodontic brackets, which takes much less chair time than direct bonding.
“The main disadvantage of indirect bonding is incomplete penetration of the curing light through the transfer trays, resulting in failure of the bonding of the brackets,” the researchers explained. “The main goal in clinical settings is to minimize the time spent in the chair. This indirect bonding technique reduces chair time, is economical, uses minimal armament, and provides adequate light penetration and precision.
Indirect orthodontic bonding first appeared in the 1970s, and oddly enough, caramel candy, which is water soluble, was used at the time as an adhesive for brackets. We have obviously come a long way, moving on to thermosetting composites, tacky wax and soluble wallpaper paste, until the tray transfer system was developed in the 1990s.
“Read and O’Brien (15) and Read and Pearson (16) suggested the use of a transparent thermoplastic sheet for the transfer of trays in order to make the indirect bonding technique compatible with the photopolymerizable composite,” wrote the researchers.
Although faster for the patient and more accurate, indirect binding has its own issues, including increased lab time, the need for an additional set of impressions, and weaker bracket bonds, due to ‘incomplete curing of the composite due to partial light penetration. This is why the researchers wanted to see if they could use a 3D printing pen to improve the process, as well as the popular biodegradable polymer PLA, which is good for making the transfer tray due to its transparency and ease. rigidity.
The team selected five consenting orthodontic patients and made alginate impressions of their upper and lower arches and cast casts of them, which were then marked for the ideal bracket placement according to the MBT prescription before having a layer of bonding agent applied and photopolymerized. The brackets were added and light-cured again, after adding another layer of bonding agent for stability. A 3Doodler PRO, set at 210 ° C and maximum flow, was used to help make the transfer trays in MatterHackers PRO PLA.
“The tip of the 3D printing pen was held close to the supports; the molten PLA has been projected in such a way that three edges of the bracket, i.e. mesial, distal and gingival, remain free of PLA; however, it engaged the slot of the bracket and extended over the occlusal and palatal surfaces of the tooth. After the transfer tray was fabricated, the brackets were dislodged from the study model using boning forceps, keeping the PLA tray intact, ”the team explained.
The researchers then transferred the 3D printed tray, with the brackets inside, to the mouth, and light-cured it after determining the fit was good. A straight probe was used to remove the tray from the brackets, any PLA that broke in the slot in the bracket was removed with a heated probe, and a tungsten carbide bur completed the process, used to remove any resin residual on “the incisal edge of the support.” Of the five study participants, only three total bracket failures were observed.
The team found no other studies in which the brackets were attached to the study models using a bonding agent as an adhesive. It is a highly biocompatible material which was also unaffected by the heat of molten PLA.
“In this case, we used a bonding agent as an adhesive to secure the brackets to the study models, as it can be applied effortlessly over the base of the bracket and a layer over the plaster. It also forms a very fine interface between the base of the bracket and the study model, thus increasing the precision of the expression of the bracket prescription ”, they explained.
While the 3D printed PLA platen took longer to fabricate than a vacuum formed thermoplastic platen, it fitted better and offered good rigidity, in addition to being easier to fabricate and fit. handling, more clinician-friendly, resulted in fewer chairside corrections, was easier to remove from the mouth, and offered three surfaces for curing and “optimal bond strength.” Additionally, when the researchers compared their 3D printed tray to other indirect bonding methods, they found that the allowed them to remove flash – a major component of plaque buildup – from the brackets bases.
A previous study found that the average time required for the laboratory and clinical steps for indirect bonding of brackets was almost 39 minutes, while it took just under 30 minutes for direct bonding of brackets. In this study, it took 18.44 minutes for the bonding agent and 3D printing pen lab procedures, and 11.86 minutes for the clinical procedures, for a total of 30.3 minutes, just between the average times for direct and indirect bonding of brackets using conventional methods.
The researchers assessed bracket failure for all five patients every four weeks for a year, and concluded that the use of a 3D printing pen, PLA, and a bonding agent to make trays full or partial indirect binding is “a precise and easy to use tool. , an economical and reliable method that reduces the time spent in the chair.
“A 3D printing pen and PLA were used to make transfer trays for indirect bonding, which gave us advantages such as ease of handling, immense control over the flow of materials and parts of the support and molding to cover with PLA, cost-effectiveness and transparency. This method does not require any expensive equipment and the materials used are easily transportable, ”the team concluded.