Top 100 cited systematic reviews and meta-analyses in the major journals of oral and maxillofacial surgery: a bibliometric analysis

The aim of this bibliometric research was to identify and analyze the top 100 cited systematic reviews in the field of oral and maxillofacial surgery in order to guide any professional level with interest in this topic and to map the current trends the field of oral and maxillofacial surgery. Using the Web of Science database without restrictions on publication year or language, a bibliometric analysis was performed for the five major journals of oral and maxillofacial surgery: International Journal of Oral and Maxillofacial Surgery (IJOMS), Journal of Oral and Maxillofacial Surgery (JOMS), Journal of Cranio-maxillofacial Surgery (JCMS), British Journal of Oral & Maxillofacial Surgery (BJOMS), and Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (Triple-O). The most top-cited systematic review was published in 2015 with a total of 200 citations on survival and success rates of dental implants, consistent with the finding that “pre- and peri-implant surgery and dental implantology,” and “craniomaxillofacial deformities and cosmetic surgery” were the most frequently cited topics (22% each). The majority of top cited papers were published in IJOMS (43%), followed by JOMS (34%), Triple-O (8%), JCMS(8%) and BJOMS(7%). The highest number of contributions was from the Netherlands, followed by Italy and USA. The outcome of this article can be used as a source of information and to guide not just researchers but also clinicians and students to which areas are trending in the field of oral and maxillofacial surgery, thus also having a large impact on the field of oral and maxillofacial surgery. However, this article cannot reflect the quality of the included systematic reviews.


Background
Decision making regarding all clinical decisions including choice of treatment is nowadays nationally and internationally based on evidence-based medicine in all fields of medicine such as dentistry and oral and maxillofacial surgery (OMFS) [1,2]. Randomized controlled trials (RCTs) have been considered the best and strongest study design to answer a specific clinical question, consequently being a guide to the decision making, described as an evidencebased approach. However, in most of the RCTs, a huge sample size is warranted to reach an outcome based on reliable statistics. Performing a RCT with a big sample size is a challenge for any researcher. Systematic reviews with meta-analysis allow combining data from individual RCTs in order to reach a more robust and reliable conclusion regarding a clinical question. Besides that, there are tools to evaluate the quality of RCTs, in order to be able to do recommendations about this specific clinical issue. Therefore, presently systematic reviews and meta-analysis are graded with the highest quality level study design [3]. Furthermore, studies have indicated that dentists often are either unable or unwilling to access or read primary evidence [4]. There are also indications that Cochrane systematic reviews are not as cited and popular as systematic reviews in high impact journals. This 1 3 finding is surprising since the Cochrane systematic reviews are commonly considered gold standard, but one explanation could be the reporting format that is difficult to read and also presented as boring [5]. Therefore, summaries of evidence such as systematic reviews and clinical guidelines could be an easy way to implement evidence-based dentistry in the clinical practice [6].
Another type of research, used to show what impact publications have, is called "bibliometrics." The first citation about bibliometrics was done by Pritchard in 1969 [7]. There are some publications on bibliometric analysis in the field of OMSF, but specified as facial trauma [8], oral cancer [9], and maxillofacial surgery [10]. The citation analysis is a type of bibliometrics which quantifies how many times a publication has been cited after its publication. This information can be efficient to use in order to evaluate what impact a publication has in a specific field, and therefore how important this publication is in that specific field. Thus, the more cited the publication is, the greater impact it has [11]. On the other hand, there are evidence indicating that errors in the cited "facts" can be perpetuated with repeated citations which can influence practice and policy negatively [12]. Furthermore, for dentists and clinicians already using evidence-based dentistry in their clinical practice, this analysis can be seen as an important tool to guide the clinicians to identify the publications with the greatest impact in their field of action, and thus use them as a guide in their decision making.
After the year 2000, there was a huge increase in the number of published systematic reviews in medicine and dentistry. Specifically, in the field of OMFS, an increase of published systematic reviews was observed after the year 2010. To our knowledge, there are no studies aiming to investigate the most-cited systematic reviews in the field of OMFS. Thus, after 10 years of worldwide research, it is imperative to know how the direction of the research in the field of OMFS, to see how the field of OMFS has been transformed and/or affected by investigating the bibliometrics of the systematic reviews, by ranking the most-cited systematic reviews in order to both provide the direction of the research in the field of OMFS, and also as a guidance for the clinicians regarding their acquisition of knowledge from a solid evidence-based aspect. The aim of this bibliometric research was therefore to identify and analyze the top 100 cited systematic reviews in the field of OMFS in order to guide any professional level with interest in this topic and to map the current trends the field OMFS.

Methods
Using the methodology outlined in the bibliometric analysis of top 100 cited paper in a previous study [13], the authors performed a bibliometric analysis of the top 100 most highly cited systematic reviews. The five top journals in the specific field of oral and maxillofacial surgery with impact factor above 1.0 which publishes systematic reviews frequently were chosen (International Journal of Oral and Maxillofacial Surgery (IJOMS), Journal of Oral and Maxillofacial Surgery (JOMS), Journal of Cranio-maxillofacial Surgery (JCMS), British Journal of Oral & Maxillofacial Surgery (BJOMS), and Oral Surgery Oral medicine Oral pathology Oral radiology (TRIPLEO). A search was performed on October 29, 2020, using the Clarivate Analytics' Web of Science database and there was no restriction on the publication year or the language of the manuscripts. The search strategy was "systematic review" OR "systematic reviews" OR "metaanalysis" OR "meta-analyses." The results were organized in descending order of citation count.
After the search the Clarivate Analytics' Web of Science database, the 100 most-cited articles were stratified in categories based on the content. Ten categories could be found in the stratification process and they were as follows: dentoalveolar surgery, pre-implant surgery and dental implantology, traumatology, craniomaxillofacial deformities and cosmetic surgery, osteonecrosis of the jaws, pathology, reconstructive surgery, temporomandibular joint (TMJ), basic science research, and emerging technologies.
The most-cited articles were analyzed regarding the following information retrieved from the Clarivate Analytics' Web of Science database: number of citations, publication year, journals, authors, number of authors, methodological design (systematic review or systematic review with metaanalysis), article field (dentoalveolar surgery, pre-implant surgery and dental implantology, traumatology, craniomaxillofacial deformities and cosmetic surgery, osteonecrosis of the jaws, pathology, reconstructive surgery, temporomandibular joint (TMJ), basic science research, and emerging technologies), contributing institution and country. The country of origin and contributing institution of the article was defined by the address provided for the corresponding author. When the paper presented, the same citation number the most recent was best ranked.
Number of articles and citations per article were graphed using the Statistical Package for the Social Sciences software (SPSS version 22.0).

Results
The initial search identified 771 articles. The 100 top-cited systematic reviews on the OMFS field are listed by rank order based on the number of citations in Table 1. From a total of 100 systematic reviews only 37 presented metaanalyses. The number of authors ranged between one and 16 (mean 4.12 ± 2.31).
These articles have been cited a combined total of 5107 times. The top-cited article was published in 2015 with a total of 200 citations [14], but only 7 articles reached to 100 citations (Table 1). Based on the distribution of the 100 articles over the years and their citations per publication, the years 2000 followed by 2006 and 2007 were the most productive years (Fig. 1). The earliest systematic review included in this bibliometric analysis was published in 2000 by Lee et al. [15], in JOMS and has been cited 98 times, while the most recently was published in 2018 by Starch-Jensen et al. [16] in the IJOMS and has been cited 33 times. Figure 2 illustrates the distribution of the 100 articles over the years.
The fields "pre-and peri-implant surgery and dental implantology," as well as "craniomaxillofacial deformities and cosmetic surgery" were the most frequently cited topics (22% each) in the top 100 list (Fig. 3). The first field has a total of 1334 citations while the second topic has a total of 1162 citations.
There were 25 different countries of origin and 83 institutions responsible for the highly cited systematic reviews. The leading countries were the Netherlands and Italy with 12 manuscripts each, followed by the USA with 10 articles (Fig. 4).
Overall, IJOMS was responsible for 2481 citations, JOMS for 1684, TRIPLEO for 380 citations, JCMFS for 307, and BJOMS for 255. The mean citation rate per published review followed the same pattern with IJOMS having a mean citation rate of 57.7 citations per review, JOMS 49.5 citations per review, TRIPLEO 47.5 citations per review, JCMFS 38.4 citations per review, and BJOMS 31.9 citations per review. Most of the manuscripts were published in the IJOMS and JOMS (Fig. 5).

Discussion
In the field of (dental)medicine, as in the other fields of science, the scientists strive to reach out with their research findings. In other words, they wish that their findings both can be used to affect decisions, and also to guide the readers in their decision making [12]. Articles reaching more than 100 citations are considered classic, i.e., having a great impact [17]. However, to analyze and understand if the conducted research has any impact or affects decision making one has to analyze how and if the articles do reach out, and what impact they have in their research filed [17]. To do that scientometrics, which is bibliometry in the field of science, is frequently used. This study used citation analysis [18], to identify the publications that have had the greatest impact in the field of OMFS. Although the field of OMFS is very wide, with diverse conditions and treatments, the main finding of this citation analysis indicates that there were only 7 systematic reviews that reached to 100 citations in the field of OMFS, among the included journals. This is in line with previous studies indicating that less than 10% of the published articles reaches up to the status of classic articles [19][20][21].
Among the classic articles, the top-cited article was an Italian systematic review on longitudinal studies about the evaluation of survival and success rates of dental implants [14], published in 2015 but already up in 200 citations. Among top three, there was one more systematic review on dental implants also from Italy focusing on different alveolar bone augmentation procedures for implant placement [22], published in 2014 and has now reached 124 citations. It is not surprising that systematic reviews upon dental treatments are top ranked since dental implant surgery is the vast most common surgical procedure next to tooth extractions, in contrast to orthognathic surgery, tumors [23].
The second most cited was also a European (from the Netherlands) systematic review on three-dimensional image fusion processes for planning and evaluating orthodontics and orthognathic surgery, published in 2011 having 131 citations. All top-three systematic reviews were published in IJOMS, which is the top journal in the field of OMFS, being ranked in the second quartile (QR2), Clarivate Analytics' Web of Science database. It has been shown that the journal impact factor answers for 59% of the variation in the number of citations [24]. Therefore, it is not at surprising finding since most authors are interested in publishing papers in journals with high impact factors, which also is considered an indication of high quality papers [25,26]. Just outside top-three systematic reviews, this citation analysis could show that systematic reviews upon osteoradionecrosis from Hong Kong (112 citations) [27] and Malaysia (100 citations) [28], as well as osteonecrosis from Germany (104 citations) [29]. The same fields were also dominating the rest of the most highly cited systematic reviews.
It has previously been reported that the majority of the top-ranked, top-cited publications are produced in nations with better economic rankings [21,30]. This was also found in this citation analysis indicating that most of the systematic reviews in the field of OMFS are produced in Europe and the USA, as well as Hong Kong, with Italy as the most successful country.   One interesting factor is t hat t he top-ranked systematic reviews are all published after the year 2010, however not sur pr ising since only 14 out of the 100 top-cited were published in the decade 2000-2010. One common criticism on citation analysis reports is that the outcome is affected by the impact of time [19]. This was, however, not the case in this report on the field of OMFS. In accordance with our results, previous studies have indicated that there are just a few citations the first years, with a peak of citations just before an article age of 10 years [31].
Another aspect to consider is that citation analysis only can be used to assess the impact the specific article has on its field by quantifying its recognition, the importance as well as the popularity of the topic, and also perhaps how common or severe a condition might be, but it cannot reflect the quality of the content in the article [25,26]. Therefore, it is of great importance to use the outcome of this article as a source of information not just for researchers but also for clinicians and students, regarding which areas and to guide readers at any professional level with interest in this field to which areas are trending, thus also having a large impact on the field of OMFS. However, although scientists wish that their research findings can be used to affect decisions, and to guide the clinicians in their decision making [12], one also has to take into consideration that this is not the case in dentistry. It has recently been shown that although the majority of dentists are aware of the term and meaning of evidence-based dentistry, they do not necessarily seem to apply evidence-based dentistry in their practice [6]. This could be seen as a drawback regarding evidencebased dentistry in clinical practice. Therefore, clear, easy-to-read summaries of evidence such as systematic reviews and clinical guidelines could be an easy way to implement evidence-based dentistry in the clinical practice [6].
There are some limitations that could be considered. One is that this article only evaluated the five top journals in the specific field of OMFS with impact factor above 1.0. This could consequently result in that many other excellent review articles concerning the field of OMFS but published in other journals, i.e., in other languages or from other fields of dentistry/medicine are lacking. However, as shown in this analysis the included articles were from entire world, but the majority of the most cited were from countries with better economic rankings [21,30]. Furthermore, this article could also show that most of the most-cited papers were in journals with higher impact factors, which was not surprising since most authors are interested in publishing papers in journals with high impact factors which also is considered as an indication of high quality papers [25,26]. Thus, the frame used in this study only including the five top journals in the specific field of OMFS with impact factor above 1.0 can still be a good indicator for the current trends in the field of OMFS and a useful guide for In conclusion, in the field of OMFS for the years following the year of 2000, the majority of the top-cited systematic reviews are published after the year of 2010 in nations with better economic rankings. Furthermore, the most-cited systematic reviews were on dental implant Fig. 3 Topics covered among the 100 most-cited systematic reviews on oral and maxillofacial surgery Fig. 4 Country of author's institute for 100 most-cited systematic reviews surgery, which might not be so surprising since it is the vast most common surgical procedure next to tooth extractions.