Keywords
Splints - Orthognathic Surgery - Bibliometrics - Dentofacial deformities - 3D printing
- CAD/CAM
Introduction
Orthognathic surgery procedures involving the jaws require the use of surgical splints
(SS) for a more reliable stabilization of the movements performed in the operated
bone segments.[1] An acceptable method to guide the positioning of the bone bases and their respective
fixations involves the use of SS made of acrylic.[2]
Before internal fixation systems, it was necessary to maintain the maxillomandibular
block in the postoperative period to stabilize the planned final occlusion.[3] With the advent of these fixation systems, maintaining the SS in position started
to be indicated only as an adjunct tool in elastic therapy or in cases of segmental
maxilla surgery.[3]
[4]
[5]
[6]
Technological advances in the field of computing and the generation of three-dimensional
(3D) images have led to the creation of virtual planning protocols in orthognathic
surgery. This fact allowed a change of paradigms as to how to carry out the planning,
predictability, execution, and confection of the SS.[7] Hence, it is a topic of paramount importance, which encourages researchers to perform
future well-designed clinical trials, assessing the accuracy of virtual planning protocols
for soft-tissue outcomes in the midsagittal plane in comparison to digital profile
cephalogram-based traditional surgical planning.
In analytical research, bibliometrics is defined as the use of statistical methods
for the quantitative evaluation of academic literature.[8]
[9] The benefits of this type of analysis include the evaluation of researchers or scientific
publications, the study of the structure of an area of the scientific field, the identification
of important topics, the discovery of new developments, among others.[10]
[11]
[12]
[13]
The bibliometric study can also have a qualitative character, seeking to cover articles
in a certain area of knowledge. From this selection, we can address and generate a
scientific production. As a principle, this type of research considers both relevance
and methodological rigor.[14]
[15]
[16] A database of scientific articles is selected, and from the combination of keywords
and application of inclusion and exclusion criteria, an exploratory literature review
is performed to create categories of analysis of the studied subject.[14]
[15]
The two most widely used bases are Scopus and Web of Science. Any comparison between
them is hampered by the fact that both are in continuous development.[16]
There are no bibliometric studies related to the orthognathic surgery to date. Thus,
the present study was performed to answer the following research question: “What are
the most relevant bibliometric data of studies on the scientific field of orthognathic
surgery-related surgical splints over the years?”
Materials and Methods
Study Design, Search Strategy and Selection of Articles
This work is a descriptive bibliometric study, to evaluate research that addresses
the topic related to SS used in orthognathic surgery. The research was performed in
the Scopus database on May 9, 2020, with the search strategy TITLE-ABS-KEY (splint)
AND TITLE-ABS-KEY (orthognathic AND surgery). The studies found were exported to an
application used to select articles in systematic reviews (Rayyan, Qatar Computing
Research Institute, Doha, Qatar).[17]
The articles found in the search were evaluated by two examiners (DIOB and IFT) and,
later, by a third reviewer (AMBS). In case of inconsistency among the three mentioned,
a fourth expert reviewer on the subject (FSRC) was called in for evaluation.
Studies involving laboratory and clinical tests, observational studies, and clinical
trials that evaluated SS used in orthognathic surgery were included. Studies that
did not evaluate any characteristics related to the properties of the splints or did
not use them were excluded.
After selecting the articles, they were exported to the VOSviewer application (version
1.6.14) for the analysis of bibliometric data (article citations, places of publication,
co-citations, most cited authors, and the studies that showed the most significant
results). To this end, analytical maps were created based on the bibliographic and
textual data of the selected articles.
Results
We included articles published from 1975 to May 9, 2020. Three hundred and thirty-one
articles were found. These were exported to Rayyan software, where inclusion and exclusion
criteria were applied to titles and abstracts. At the end of the process, 76 references
were obtained and analyzed in the present bibliometric review.
The five most cited articles within the sample were as follows: Swennen et al with
205 citations, Aboul-Hosn Centenero and Hernández-Alfaro with 141 citations, Metzger
et al with 102 citations, Swennen et al with 90 citations, and Mavili et al with 85
citations.[18]
[19]
[20]
[21]
[22] All articles addressed the making of SS with 3D printing, and two of them also involved
virtual planning in orthognathic surgery ([Fig. 1]).[18]
[19]
[20]
[21]
[22]
Fig. 1 Analysis of the most cited documents in the selected literature.
The selected studies were conducted in the following 25 countries: Germany (n = 16), United States (n = 15), Belgium (n = 8), Switzerland (n = 7), China (n = 7), Taiwan (n = 5), United Kingdom (n = 4), France (n = 3), Japan (n = 3), South Korea (n = 3), Spain (n = 2), Austria (n = 2), Canada (n = 2), Brazil (n = 2), Portugal (n = 1), Italy (n = 1), Thailand (n = 1), Hongkong (n = 1), West Germany (n = 1), Australia (n = 1), Denmark (n = 1), England (n = 1), and Turkey (n = 1). The two countries that present more work, Germany and the United States, had
their main publications between the years 2010 and 2012 ([Fig. 2]).
Fig. 2 Analysis of the countries most cited in the selected literature.
The most cited citations within the 1,139 references that are in the 76 selected articles
were as follows: Gateno et al (n = 8), Zinser et al (n = 7), and Xia et al (n = 7). They were all related within the cluster with equivalent strength ([Fig. 3]).
Fig. 3 Analysis of the most referenced co-citations in the selected literature.
The most referenced authors were as follows: Gateno et al (n = 125), Teichgraeber et al (n = 97), Xia et al (n = 89), Schutyser et al (n = 43), and Zinser et al (n = 43). All of these were related within the cluster, however Gateno et al, Teichgraeber
et al, and Xia et al, presented the greatest strengths of the connections ([Fig. 4]).
Fig. 4 Analysis of the most cited authors in the selected literature.
The analysis of databased on titles and abstracts led to the identification of the
most common terms. Of the 1,724 terms, 22 had a minimum number of 10 occurrences.
For each of the 22 terms, a relevance score was calculated. Based on this score, the
most relevant terms were selected. The standard for choosing these terms was 60% relevant.
Therefore, 13 terms were selected: orthognathic surgery (n = 55), splint (n = 49), planning (n = 45), patient (n = 41), study (n = 36), computer (n = 29), model (n = 23), surgical splint (n = 21), model of surgery (n = 17), CAD/CAM (n = 16), time (n = 16), case (n = 16), and surgeon (n = 11), distributed in three clusters ([Fig. 5]). The greatest relevance was observed in orthognathic surgery (1.84), splint (1.27),
and planning (1.36).
Fig. 5 Analysis of the most cited words in the selected literature.
[Fig. 5] illustrates a network visualization of the terms used in the present search strategy.
Circles represent keywords, and their colors represent specific years (blue = 2011;
green = 2013; yellow = 2015); lines represent the distance between words, and the
closer two words are located to each other, the stronger their relatedness. In 2011,
the circles with higher weights were related to the terms “splint,” “orthognathic
surgery,” “model surgery,” and “time.” The year 2013 is represented by the color green,
in which surgical planning is geared to the patient and not model surgery. Meanwhile,
yellow, the color of which represents 2015, was the time when studies focused on computer
and computer-aided design (CAD)/computer-aided manufacturing (CAM) technology. Thus,
demonstrating a chronological order of research aimed at orthognathic surgery and
its technological evolution.
Discussion
The articles most cited in the studies are by Gateno et al, Xia et al, and Zinser
et al.[23]
[24]
[25] These authors are the precursors of virtual planning and SS obtained from 3D technologies
for orthognathic surgery.[23]
[25] For this reason, citation rates are high among these and many other articles. When
studying orthognathic surgery, these research works are the most commonly used as
references. These studies justify why, in contemporary times, plaster model surgery
and the manufacture of conventional SS are being less used. Despite being a relatively
new advent, it is already common in this type of procedure, due to its precision and
reproducibility.[7]
[19]
[26]
[27]
[28]
The study by Gateno et al[23] demonstrated a positive result of stereolithographic splints, generated using CAD/CAM,
thereby obtaining a high degree of precision. No differences were observed between
SS made conventionally and those made in a 3D system. Both the conventional method
and those obtained from the stereolithography (STL) file showed the same precision.
The adjustments made to the splints obtained from STL files were the same as for the
conventionally made splints.[23]
[29]
[30]
[31]
[32]
[33]
Thus, it is concluded that both ways of obtaining different SS are viable for use
in orthognathic surgery. With the recent development of the 3D system in surgical
planning technology, it is possible to carry out the entire planning of the surgery
and the preparation of the splints in a computational environment, thus facilitating
the process for the maxillofacial surgeon. Also, there is the possibility of better
predictability of the final result.[23]
[29]
[30]
[31]
[32]
[33]
Many unwanted outcomes are the result of poor planning. Thus, with the need to improve
the surgical planning of craniomaxillofacial deformities, a 3D computer-assisted surgical
simulation system (CASS) was developed. In this system, it is possible to perform
the surgery virtually and create a prediction of the outcome in the patient. In addition
to two-dimensional (2D) and 3D measurements, the software is also capable of performing
volumetric measurements.[32]
The results of the study by Xia et al showed that the CASS method had a lower cost
in terms of the surgeon's time, patient's time, and material costs.[24]
[34]
[35]
[36] Also, he reported that the program encounters difficulty in establishing the maximum
intercuspation (MI) function on the computer. It is almost impossible to be sure that
what is being observed on the computer screen is, in fact, the representation of the
best real alignment. To ensure that the final digital occlusion is in correct MI,
plaster models that are physically positioned in the final occlusion must be digitized.
Xia et al pointed out several problems associated with the traditional planning system,
thus justifying that the best option for orthognathic surgeries in virtual planning.
In the conventional method, the analysis of facial photographs had to be done two-dimensionally.
However, by virtue of advances in computing, it is now possible to perform these analyzes
in a 3D way.[24]
Despite this, some measures are generally difficult to interpret, since those that
are in 3D are translated directly (expanded) into the original 2D form. Another problem
with 3D cephalometry is the uncertainty of how angles are constructed by planes.[24]
The complete production of surgical splints on 3D printers is often less time consuming.
Personalized splints reduce the duration of surgery, anesthesia time, and costs. Thus,
direct communication with prosthetist is possible, allowing quick changes if necessary.[36]
There are technical limitations regarding the use of 3D printing. There is a learning
curve for developing proficiency, using software planning, which is offset by increased
surgical predictability and reduced time, making this a worthwhile investment for
planning surgeries.[36]
The 3D printing technique presents a higher dose of radiation due to radiographic
examinations. However, if the number of tests is reduced, there will also be a decrease
in exposure as well as in the time spent. This is possible due to the cone-beam CT
technique, which has a reduced dose of radiation and better quality images.[34]
A great advantage of virtual methods is the reduction of time spent on surgical planning.
Despite being a higher value process, compared with the conventional technique, the
investment in software is of great value, as the number of patients undergoing treatment
increases and the cost is compensated. Besides, the 3D technique has better predictability.[34]
On the other hand, for general planning, the 3D technique is the one that demands
the most time, as the steps are time-consuming, since they involve a more advanced
cephalometric system, heavier data files, and a segmentation process with an added
dimension.[34]
However, in the study by Resnick et al, virtual surgical planning was cheaper and
less time consuming than in the standard form for all types of cases analyzed.[35] The greatest differences in time and cost were seen concerning the asymmetry, as
it is difficult to quantify this inequality in 2D and the increased complexity of
the surgical model for these cases, compared with the ease of viewing and altering
3D images in virtual planning.
By eliminating facial arch transfer, there is a significant reduction in the surgeon's
time compared with the traditional planning method. After the patient's CT is completed,
the preparation of the computer data, including the digitalization of the dental model,
segmentation of CT images, 3D model reconstruction, skull model creation, digitization
of the markings, and virtual osteotomies, are completed by a centralized service.[24]
Zinser et al developed and patented (WO 2008/031562) CAD/CAM for the manufacture of
multiple surgical splints for orthognathic surgery.[25] The benefits of this technique are that it allows the direct operating room sharing
of virtual surgical plans, in addition to being easy to use, relatively inexpensive,
and clinically efficient.
The use of CAD/CAM technology provided a precise and clinically acceptable transfer
from preoperative planning to the surgical environment, comparing favorably with the
variations reported in conventional clinical protocols that incorporate cephalometric
analysis, face transfer to semi-adjustable articulator, and model surgery plasterboard.[25]
Virtual planning, using CAD/CAM technology or CASS methods, requires the use of specific
equipment that has a cost associated with its acquisition. However, considering that
it is a durable equipment, this has its cost reduced throughout the time of use.[25]
[35] The authors of the present study suppose that CASS may be better because of less
time spent by the various professionals which may actually be more cost-effective.
Conclusion
Advances in orthognathic surgery have allowed surgical planning to be more patient-oriented
and more individualized. Besides, contemporary studies are more related to technology
using computers as well as the advent of SS manufactured using the CAD/CAM system,
which is currently the best option of choice for surgeons, due to its high level of
accuracy, its low cost, its better predictability of results, and its fast processing.
