Page 85 - IJB-9-2

International Journal of Bioprinting Steam-sterilized and degradable FFF-printed PLA/PHA surgical guides

1. Introduction blends of PLA and PHA are not commonly used in dental
or medical 3D printing applications. PLA is an aliphatic
Following the use of three-dimensional (3D) printing linear poly(α-ester) or α-hydroxyalkanoic polyester that is
in the medical field in the 1990s, health-care sector has acid-derived and produced through fermentation from
[13]
rapidly moved toward a highly individualized approach to renewable resources such as starch or sugar. It has modest
treating patients. In surgery, this trend is characterized by mechanical and thermal characteristics, which is why it
the fabrication of patient-specific and mostly 3D-printed is often copolymerized or blended with other polymers.
aids and implantable devices. Additive manufacturing is a PHAs are polyesters of 3-, 4-, 5-, and 6- hydroxycarboxylic
process which offers the possibility to produce objects in a or hydoxyacids and originates from microorganisms,
[13]
digital fabrication workflow. The devices generated may be which produce this polymer for energy storage under
divided into three main categories: (i) Pre-surgical tools, restrictive nutrient conditions . Since it is naturally
[15]
[1]
(ii) intrasurgical tools, and (iii) implants . At present, some produced by soil bacteria, degradation begins when the
of the possible applications include individualized joint polymer is exposed to similar bacteria . Both polymers
[12]
prosthesis, spine stabilization, individual osteosynthesis, are produced from renewable natural resources; therefore,
and reconstructions or surgical accessories such as drilling the combination of PLA and PHA is expected to be
or cutting guides [2-10] . Even the combination of a printed completely biodegradable .
[13]
surgical guide and a printed dental implant with a modified
surface could be possible . Using fused filament fabrication (FFF) in combination
[11]
with PLA/PHA filaments could overcome the
The development of new materials and manufacturing aforementioned environmental problems because the
techniques will further expand the scope of possible material is biodegradable and can be recycled and
[18]
applications for such individualized devices in the possibly used in a second 3D printing process . Beneath
[19]
future. The evolution from traditional substractive those recycling capabilities, acquisition costs for both, the
manufacturing to 3D printing helped reduce the amount printer and the printing material, are comparably low .
[20]
of waste produced [12] . However, an increasing usage of
polymers is accompanied by more wastages. Considering Nowadays, a digital workflow is an integral part of
current developments regarding overconsumption of implant dentistry. Computer-assisted implant surgery
plastic products, climate change, and the constantly sets the link between virtual planning and surgery, and a
growing population, it is important to address this digitally planned implant placement has been shown to
problem in advance and find appropriate solutions. The be significantly more accurate than freehand placement.
harmful impact of plastic waste on human health and A high level of accuracy of the surgical guide is needed for
the ecosystem is considered the driving forces for the the protection of vital structures and a better interaction
[21]
development of biodegradable natural based polymers [13] . between the surgeon and the prosthodontist .
Biodegradability refers to a degradation process elicited The accuracy of the surgical guide depends on a
by the action of naturally occurring microorganisms. multitude of factors, such as planning, fabrication, and
The degree of biodegradability of a material depends post-processing steps. As implant surgery is an invasive
mainly on the chemical structure of its components, procedure, contamination with microorganism could lead
rather than its the origin like corn starch [14] . Plastics can to an infection and consecutively to a poor outcome .
[21]
be classified into fossil-based and non-biodegradable or Therefore, accurate transfer of virtual surgical planning to
biodegradable plastics as well as natural-based and non- the actual medical situation as well as structural stability
biodegradable or biodegradable plastics [15] . after further processing steps, such as steam sterilization,
Regarding the regularly used resins for vat is important in ensuring a material to be usable for
polymerization in the dental and medical field, in application in patients.
addition to the hazardous processing materials, the In the previous studies, we showed that PLA/PHA is
printed objects could also give rise to the environmental a promising material that show high level of resistance to
problem. Nowadays, those resins can only be used once steam sterilization, which is characterized by minimum
and are difficult to recycle, and most often, they are not dimensional changes demonstrated by the non-degradable
biodegradable. Nevertheless, many studies in the recent materials. In the present study, we aimed to compare,
years focus on the environmentally friendlier materials for the first time, the accuracy of FFF-printed PLA/PHA
that are biocompatible and biodegradable for vat surgical guides and material jetted guides of a commercially
polymerization, although they are not available for use in available material in fully guided dental implant placement
most of the printers today [16,17] . Except for manufacturing before and after steam sterilization. The whole workflow is
of training models, biodegradable materials such as shown in Figure 1.

Volume 9 Issue 2 (2023) 77 https://doi.org/10.18063/ijb.v9i2.655