The efficacy and operative efficiency of CAD/CAM-guided mandibular reconstruction using a fibular free flap:
A systematic review

by Kendall Lynes, Biology

The aim of this review was to evaluate the impact of CAD/CAM surgical assistance on FFF mandibular reconstruction surgical techniques, and the patients involved. Furthermore, this review assesses whether CAD/CAM surgical involvement can improve the operative timing and postoperative symmetry of patients that underwent FFF mandibular reconstruction. A secondary evaluation determined whether CAD/CAM surgical effects improved the postoperative quality of life in affected patients. A digital search was conducted within the database, PubMed, where keywords regarding mandibular reconstruction were applied. Through PubMed, the selection of 12 studies according to the designated selection criteria was made. Eight studies included in this review compared surgical outcomes between a control group, individuals that underwent free-handed FFF mandibular reconstruction, and a CAD/CAM surgical group. The remaining four studies solely focused on the surgical outcomes of CAD/CAM-assisted surgery. General aspects of included studies are operation/ischemia time, varying postoperative mandibular measurements involving symmetry, and specific methods of CAD/CAM involvement. While only a portion of studies involved two study groups of comparison, all studies demonstrated two general conclusions. Fibular free flap mandibular reconstruction surgeries were both shorter and resulted in more precise facial symmetry when compared to traditional free-handed reconstruction. Additionally, CAD/CAM-assisted mandibular reconstruction may improve the patient’s quality of life through the improved post-surgical symmetry. However, further research is needed to assess the overall patient satisfaction regarding specific CAD/CAM involvement.

mandibular squamous cell carcinoma, computer-aided design/manufacturing (CAD/CAM)

Introduction

The human mandible has a variety of functions in speech, ingestion, and mastication. Because the mandible is the only moveable bone in the skull, it holds great importance in one’s day-to-day life (Vasković, 2023). Consequently, as the body ages, it also becomes susceptible to disease, which then calls for mandibular reconstruction. Mandibular reconstruction has been a well-known phenomenon in the world of medicine, because of ablative tumor removal or other kinds of trauma caused by oral diseases (Vincent & Hohman, 2023). Most individuals affected by various head and neck cancers, one being mandibular squamous cell carcinoma, typically undergo mandibular reconstruction. This in-depth procedure is performed by an experienced surgeon specializing in head and neck diseases/disorders (Vincent & Hohman, 2023). Even when mandibular reconstruction is performed by an experienced surgeon, the procedure presents a great challenge due to the complexity of mandible anatomy and function. Most reconstructive surgeries vary on the type of cancer/tumor impacting the patient, which affects the size of free flap used to replace the excised mandible (Vincent & Hohman, 2023). This variation of both tumor and free flap size poses much difficulty to any surgeon as each reconstructive surgery is different. This surgery may vary on the type of free flap used, the size of the free flap and the severity of the tumor. All these factors play a role in the operation time and fluidity that the surgical team works in. Furthermore, surgical facial alteration can create functional and aesthetic impairments for the affected individual if not performed with the highest quality (Tarsitano et al., 2015). Following mandibular reconstruction, a patient’s quality of life may be altered due to a slight change in facial appearance and function. Such changes may later affect their social interactions and psychological state. Over time, modifications to mandibular reconstruction have been made to improve the efficacy of the procedure and quality of life for the patient.

Since the late-20th century, one sophisticated method of reconstruction evolved with the use of vascularized free flap surgery. It takes the careful work of a two-surgeon team to perform a mandibular osteotomy and harvest a vascularized bone from a particular donor site (Zavattero et al., 2021). While donor sites are in the ribs, foot, iliac bone, scapula, and fibula, the fibula free flap represents a first-choice option for reconstruction due to its bone length and periosteal blood supply (Zavattero et al., 2021). Furthermore, with computed tomography (CT) scans and three-dimensional planning software, scientists and physicians have been able to plan bony reconstruction procedures virtually (Zavattero et al., 2021). Computer-aided design/computer-aided manufacturing (CAD/CAM) techniques have granted a plethora of optimized virtual surgical planning for complex free fibular flap (FFF) surgery. While this virtual system has been in use for decades, technological advancements have improved resolution and image quality using CT scans. These innovations grant surgeons further capabilities for preoperative planning to prevent postoperative error. Additionally, as this technology expands in scope and becomes more accessible for mandibular reconstruction, so too will the functionality for surgeons of different learning and/or training (Al-Sabahi et al., 2022). In contrast to CAD/CAM surgical assistance methods, the traditional free hand of mandibular reconstruction limited the scope of reconstructive success to surgeons of a certain specialty or background (Al-Sabahi et al., 2022). This limitation made FFF mandibular reconstruction less accessible to the public with the lack of specialists in this area (Al-Sabahi et al., 2022). Therefore, through CAD/CAM surgical assistance, reconstruction can take place with improved preparation and a cleaner delivery process through virtual surgical guidance.

Current reviews of this topic address the latest procedures of mandibular reconstruction with CAD/CAM assistance, additionally drawing comparisons between various applications of CAD/CAM assistance. To date, research has consisted of studying the processes and accuracies of virtual surgical planning. This research involves the use of CT scans and three-dimensional surgical guides, coupled with its cost effectiveness. However, such research does not incorporate the psychological and personal impacts made on the individual patient. To illustrate these comparisons, most systematic reviews include images related to head and neck CT scans, intraoperative reconstruction, individual surgical guides and their composition, and pre- and postoperative facial appearance of the patient. One article from 2015 reviews the latest reconstructive practices, with a specific focus on the virtual planning process and the aid of customized titanium bony plates for free flap support (Tarsitano et al., 2015). Similarly, a second review, composed in 2020, focuses on the efficiency of virtual surgical planning (VSP) (Pucci et al., 2020). The writers draw comparisons to the counterpart free-hand surgical method and place an emphasis on the quality of scientific literature over computer-aided surgery (Pucci et al., 2020). While it is common for research to focus on the surgical benefits of CAD/CAM techniques and the prevention of mandibular defects, such research lacks a focus on the personal effects to the patient involving one form of free flap surgery. Personal effects include psychological state, facial functionality and aesthetic appearance through facial symmetry. 

By analyzing clinical studies and randomized controlled trials, the functional and aesthetic outcomes of FFF surgery with and without the use of CAD/CAM surgical techniques/guides will be compared. Additionally, the results of using CAD/CAM surgical methods before, during, and after surgery will be compared with surgery lacking any virtual planning. These comparisons will analyze the efficacy of mandibular reconstruction using a fibula free flap in present time. Therefore, this review will serve as a renewed assessment of the importance of CAD/CAM in FFF mandibular reconstruction, given that the most recent review was published in 2020. In doing so, it will draw specific attention to free flap reconstruction using only a fibula donor site. Hopefully, this review will demonstrate a trend of CAD/CAM techniques using clinical trials conducted from 2001 to 2024.

Methods

2.1 Eligibility Criteria

Because CAD/CAM varies in its use for both preoperative and intraoperative techniques, the comparisons of each source had to be noted for evaluation and uniformity. There was no specific preference for age, ethnicity, or sex within studies chosen. Studies that contained at least 20 participants were of the highest preference in the selection process; however, studies with less than the preferred count were also selected. Therefore, while sample size was considered in the selection of studies, a specific count was strictly enforced. All studies employed the use of a Computed Tomography (CT) Scan of the mandible, and some for the fibula, prior to surgery. CT scans aided in creating some form of a computer-generated, three-dimensional surgical cutting guide. If made clear in the research, the participants with mandibular squamous cell carcinoma prior to FFF surgery were preferred for a consistent treatment plan across studies. While it was not imperative that a source included the duration of recovery and/or its evaluation, this factor was highly favorable. Initially, sources that included two research groups, a control group and a CAD/CAM group, were sought out. The control group consisted of patients who underwent reconstructive surgery without CAD/CAM surgical assistance. The CAD/CAM group consisted of patients with some kind of computer-assisted technology involved in their reconstruction. Sources that did not include this list of information discussed above were not selected for research review.

2.2 Search Strategy

The research of CAD/CAM techniques involving mandibular reconstruction was first begun by a general search of one database, PubMed. The filters “Clinical Trial” and “Randomized Controlled Trial” were applied, with no specific limitation on publication date. No publication date was preferred to provide a selection of the best sources for application of CAD/CAM surgical techniques in real medical practice. “Mandibular reconstruction free flap” was also a search term applied to cater to specific free flap surgeries. Additionally, the research review topic was altered to include a comparison of CAD/CAM surgical techniques for FFF surgery in mandibular reconstruction. The publication date was adjusted to the earliest year possibly, with 1997 being the cutoff year for the second search made. Once this research pathway took root and all search result options had been thoroughly analyzed in content, the reference lists of sources deemed trustworthy were analyzed for additional research until enough sources were obtained.

2.3 Data Extraction 

The first round of searches involving the words “mandibular squamous cell carcinoma” yielded 32 articles from PubMed directly, but only four of these were used. While the initial objective was to review clinical trials specifically, most studies used were classified as “retrospective studies”. These studies occurred when surgical outcomes were assessed over a period of years, some recorded even after the patient had recovered (Ren et al., 2018; Toto et al., 2014; Metzler et al., 2014; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014; Brandão et al., 2016). The second round of searches covered “mandibular reconstruction free flap”, which resulted in the use of an additional two articles for review. Finally, the reference lists of presently chosen articles were analyzed, and seven additional articles were extracted from this process. Therefore, a total of 14 articles were derived from the data selection process; however, only 12 studies presented tabulated information (Ren et al., 2018; Al-Sabahi et al., 2022; Toto et al., 2014; Metzler et al., 2014; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014; Brandão et al., 2016; Zheng et al., 2012; Zavattero et al., 2021; Antony et al., 2011). Each source was analyzed for the specific involvement of CAD/CAM techniques, specifically between the control group and the CAD/CAM-assisted group. To perform a general analysis of the 12 studies, a table was made comparing the type of study, the mean age of the participants, the reason for reconstruction, sample size, and type of CAD/CAM assistance. Sources were organized into Mendeley software and brief notes were recorded for every source. Additionally, the number of postoperative measurements was closely analyzed, in conjunction with whether the study included a control group to compare later in the results. If listed in the sources, the follow-up period was also extracted as important data. Operation time, in minutes, was extracted to emphasize the efficiency of CAD/CAM use corresponding to each study. Therefore, the general aspects of each study, operation time, number of postoperative measurements, and the follow-up period were used to measure the effects of CAD/CAM usage in FFF mandibular reconstruction.

3. Results

3.1 Design of the Studies

Out of the 12 studies included in the review, eight of them included control groups (Ren et al., 2018; Al-Sabahi et al., 2022; Toto et al., 2014; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014; Muñoz Guerra et al., 2001). The control group included patients that underwent reconstruction involving pre-bent titanium reconstruction plates with no CAD/CAM involvement. The remaining four studies of importance only researched participants under a CAD/CAM experimental group, with no control group (Metzler et al., 2014; Brandão et al., 2016; Zheng et al., 2012; Zavattero et al., 2021). All retrospective studies were done at a single institution/hospital, and every study was an accumulation of surgeries over a period of years. The use of CAD/CAM techniques was generally uniform across the studies with a few differences. Differences consisted of preoperative CT scanning (Re et al., 2018; Al-Sabahi et al., 2022; Bartier et al., 2021; Zavattero et al., 2021) and the depth to which virtual surgery was performed (Ren et al., 2018; Metzler et al., 2014; Bartier et al., 2021; Zavattero et al., 2021). While all studies conducted a preoperative CT scan, only one study conducted an additional fibular CT scan (Muñoz Guerra et al., 2001). All studies employed virtual surgical planning (VSP) as a form of CAD/CAM assistance, while the components of the surgical guide, if stated, varied among the studies. The fibula was used as the donor site in at least a portion of every study while some studies used other donor sites in addition to the fibula in their research (Chen et al., 2023; Zheng et al., 2012). Across the studies, reasons for surgical reconstruction ranged from benign lesions to aggressive tumors or cancer. Amongst the sources used for this review, the study sizes range anywhere from five (Antony et al., 2011) to 57 (Toto et al., 2014) participants.

3.2 CAD/CAM characteristics

In the eight studies that compared the surgical results between a CAD/CAM (experimental) group and a group with no CAD/CAM assistance (control), researchers compared a variety of CAD/CAM assistance methods. CAD/CAM assistance included virtual surgical simulation planning and pre-bent customized reconstruction plates through stereolithographic modeling. In addition, it included three-dimensional cutting guides fashioned from precise measurements of the fibula and mandible. Control groups solely included preoperative CT scans as a form of surgical planning, an aspect in common with the CAD/CAM group. Some studies covered more specific realms of CAD/CAM assistance in which plate components were broken down and explained in detail (Al-Sabahi et al., 2022; Chen et al., 2023; Craig et al., 2014; Zavattero et al., 2021; Muñoz Guerra et al., 2001). Other studies directed a greater focus on the surgical procedure itself and the steps of the process (Bartier et al., 2021; Zheng et al., 2012). No studies compared multiple types of CAD/CAM practice, and all studies kept the same forms of CAD/CAM use uniform throughout the study.

Table 1. General descriptive characteristics of included studies

Study ReferenceType of studyMean Age (Years)Reason for surgeryCAD/CAM UseSample Size
Zheng, et al., 2012Clinical Trial30Ameloblastoma, osteofibrous dysplasiaVirtual simulation, preoperatively prebent reconstruction plate, positioning template9
Toto, et al., 2014Retrospective Review61.6Invasive squamous cell carcinoma, sarcoma, odontogenic myxomas, osteoradionecrosisVirtual simulation, preoperatively prebent reconstruction plate, positioning template (not explicitly stated)57 
Metzler, et al., 2014Retrospective Analysis56.9Congenital mandibular hypoplasia, osteomyelitis, adenoid cystic carcinoma, myxoma, squamous cell carcinoma, gunshot woundPreoperative CT scans, printed stereolithographic modeling, cutting guides10
Zavattero et al., 2021Prospective multicenter case study44.9Tumor removal, osteoradionecrosisPatient-specific reconstruction plates, preoperative CT scans, virtual surgical planning47
Bartier et al., 2021Single-Center Retrospective Study55.9Oncologic, malformation, trauma, osteoradionecrosisVirtual surgery planning with cut guides (Materialise©)33
Ren et al., 2018Retrospective Study39.1Ameloblastoma, keratocystic odontogenic tumor, ossifying fibroma, SCC of gingiva3D virtual modeling, virtual surgical simulation30
Weitz et al., 2016Retrospective Study55.5Osteoradionecrosis, invasive squamous cell carcinoma, osteoradionecrosisVirtual surgical planning, virtual resection, prefabrication of titanium plates50
Chen et al., 2023Retrospective Study57.8Squamous cell carcinoma, oncocytoma, ameloblastomaHead and neck 3D modeling, simulated reconstruction, preoperatively bent plates20
Craig et al., 2014Retrospective Review50Head and neck cancerPreoperative 3D computer simulation, intraoperative guides, pre-contoured plates19
Al-Sabahi, 2022Randomized, Controlled Clinical Trial44.4Benign lesion, ameloblastoma, malignant tumors (squamous cell carcinoma)3D virtual models of craniofacial skeleton and bony fibula, interactive virtual surgical planning, mapped virtual resections/osteotomies22
Brandão et al., 2016Randomized Controlled Trial43.5Squamous cell carcinomaAcrylic resin surgical guides, mandibular casts in stainless steel stock trays, extraoral guides, 40
Antony et al., 2011Prospective Study45.2Ameloblastoma, squamous cell carcinomaVirtual surgical planning sessions, stereolithographic modeling5

Note: The year was grouped with the author’s name for each source to demonstrate the discoveries of the time the research was conducted, with 1997 the earliest search result year in Pubmed. The mean age of participants was taken across each study; meaning, if two mean ages were given for the experimental and control groups separately, the values were combined to calculate a new mean age value. The fibula was used as the donor site in all the studies, and only specific information involving FFF surgery from studies were included.

3.3 Participant Characteristics

Table 1 shows participant characteristics which include the ailment contributing to mandibular reconstruction and the average age of the participants within the study. Sex of the participant was not accounted for in all sources; therefore, this information was not included. The age of participants was included with the mean age taken across each study. Across the studies, the overall mean age was 48.7 years. Only two of the selected studies contained an average age below 40 years (Zavattero et al., 2021; Mukherji et al., 2000). The rest of the studies selected included mean ages above 40 years, with four studies containing a mean age between 40 and 50 years (Tarsitano et al., 2015; Al-Sabahi et al., 2022; Brandão et al., 2016; Antony et al., 2011), and the remaining six studies containing a mean age between 50 and 61 years (Toto et al., 2014; Metzler et al., 2014; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014). In all the studies, mandibular reconstruction was conducted to treat some form of cancer or functional issue of the mandible. Each study had specific reasons for surgery. Squamous cell carcinoma and osteoradionecrosis were among the most defects listed. Additionally, other defects included ameloblastoma (Ren et al., 2018; Chen et al., 2023; Brandão et al., 2016; Zheng et al., 2012; Muñoz Guerra et al., 2001) and varying other tumors (Ren et al., 2018; Toto et al., 2014; Metzler et al., 2014; Bartier et al., 2021; Chen et al., 2023; Zavattero et al., 2021; Muñoz Guerra et al., 2001). 

Table 2. Synthesis of the operation times under CAD/CAM involvement versus no CAD/CAM involvement across notable studies

Study ReferenceMean Operation Time (min)
CAD/CAM GroupControl Group
Zheng et al., 2012N/AN/A
Toto et al., 2014615N/A
Metzler et al., 2014N/AN/A
Zavattero et al., 2021N/AN/A
Bartier et al., 2021510 ± 66480 ± 120
Ren et al., 2018332.4 ± 30.0392.4 ± 42.0
Weitz et al., 2016140 ± 43174 ± 85
Chen et al., 2023726.5 ± 89.1757.3 ± 84.1
Craig et al., 2014N/AN/A
Al Sabahi et al., 2022562.9 ± 51.2663.6 ± 53.4
Brandão et al., 2016N/AN/A
Antony et al., 2011N/AN/A

Note: Continuous data reported as mean ± standard deviation. Some studies expressed the operation time in hours, which was then converted to values in minutes for overall simplicity [4,5,11].

3.4 CAD/CAM Effects

Table 2 shows the effects of CAD/CAM technology during mandibular reconstruction. If listed in the selected study, the mean operation time was included under its corresponding group (CAD/CAM or control) (Ren et al., 2018; Al-Sabahi et al., 2022; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023). One aspect of CAD/CAM usage is that it would create a more efficient use of time and improve the overall surgical process. Only operation time following arterial anastomosis was reported for one study (Weitz et al., 2016). This modification caused this operation time to be significantly less in both the CAD/CAM group and the control group, however it was still listed to draw comparisons. Only one study included in the table did not include a control group, but operation time was still reported (Toto et al., 2014).

Table 3. A demonstration of postoperative management involving the follow-up period across studies.

Study ReferenceFollow-Up Period (weeks)
CAD/CAM GroupControl Group
Zheng, et al., 201212-24N/A
Toto, et al., 2014N/AN/A
Metzler, et al., 20141N/A
Zavattero et al., 20211-5N/A
Bartier et al., 20218.0 ± 3.549.5 ± 29.5
Ren et al., 20182626
Weitz et al., 20162424
Chen et al., 20237.0-97.07.0-97.0
Craig et al., 2014N/AN/A
Al-Sabahi et al., 20221313
Brandão et al., 201617-7817-78
Antony et al., 201141-62N/A

Note: Continuous data reported as mean ± standard deviation. A single number demonstrates a period up to n weeks, where n = the single number in the corresponding study. A range of numbers demonstrates varying durations of follow-up times, pulled across the numerous trials studied within its corresponding study.

3.5 Quality of Life (QoL) effects

According to Table 3, an aspect of the participant quality of life from selected studies was assessed in this review by the period (weeks) it took researchers to follow up and conduct symmetrical evaluations. The broader the range of the follow-up period, the more likely that a better QoL resulted for the corresponding participants. During this follow-up period, patients were subject to follow-up scanning, symmetrical analysis, and physical recovery assessed by the oncologist. In every study, about a one-week period was set for participants to recover from surgery before CT scans were conducted at various week periods following surgery. Out of the selected studies, four studies listed did not involve a control group in their research. However, these studies included a follow-up period; therefore, it was included in Table 3 (Metzler et al., 2014; Brandão et al., 2016; Zheng et al., 2012; Zavattero et al., 2021). Some studies stated the follow-up period in units of months, but this was converted to units of weeks for simplicity of understanding (Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Brandão et al., 2016). One source only mentioned a follow-up period after the first week of recovery with no further discussion of its significance (Metzler et al., 2014). There was no significant difference in follow-up period between the CAD/CAM group and the control group (Ren et al., 2018; Al-Sabahi et al., 2022; Weitz et al., 2016; Chen et al., 2023; Brandão et al., 2016) except for one study (Bartier et al., 2021). Only one study demonstrated a notable difference in follow-up period across the two groups, in which the control group was subject to a longer follow-up period when compared to the CAD/CAM group (Bartier et al., 2021). Additionally, another aspect of the participant QoL was assessed according to the accuracy of the results using CAD/CAM technology in mandibular reconstruction (Table 4). The smaller the postoperative measurements ranged from the preoperative values determined the level of accuracy obtained from CAD/CAM usage. 

Table 4. A comparison of the symmetrical success following reconstruction across studies

Study ReferenceNumber of Postoperative MeasurementsUse of ControlFavorable Symmetrical Results
Zheng et al., 2012N/ANoYes
Toto et al., 2014N/AYesYes
Metzler et al., 20147NoYes
Zavattero et al., 2021368NoYes
Bartier et al., 202112YesYes
Ren et al., 20188YesYes
Weitz et al., 2016173YesYes
Chen et al., 202310YesYes
Craig et al., 201412YesYes
Al Sabahi et al., 202220YesYes
Brandão et al., 201616YesYes
Antony et al., 2011N/ANoYes

3.6 Outcome Measurement

Table 4 shows the comparisons between the outcome measurements of surgeries involving CAD/CAM assistance based on the specific information presented in each study. Favorable symmetrical results were indicated if the outcome measurements closely resembled the preoperative measurements. This resemblance ensured the patient appeared the same after reconstruction as they did prior to reconstruction using a three-dimensional CT scan of the mandible. Researchers used measurements from virtual surgical simulations to compare them to the postoperative measurements obtained through constructed CAD/CAM guides. This was an additional way of estimating the productivity of CAD/CAM involvement, especially when compared to the counterpart control group. There was no specific cut-off value to determine whether symmetrical results were achieved. “Yes” or “no” was used to indicate symmetrical favorability according to the various forms of postoperative measurements taken across studies. Additionally, the number of postoperative measurements was included, where 368 measurements taken was the highest number (Pucci et al., 2020) and seven measurements taken was the lowest number (Metzler et al., 2014). If a control group was included in the study, indicated by “yes” in the third column of the table, the number of postoperative measurements was the total amount compiled from both groups (Ren et al., 2018; Al-Sabahi et al., 2022; Toto et al., 2014; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014; Muñoz Guerra et al., 2001).

3.7 Limitations of the Studies

There were specific limitations to each selected study; however, a few notable ones to consider amongst the majority are as follows. Not all studies included control groups in addition to CAD/CAM-assisted groups. A smaller number of control groups may contribute to less impact when determining the true efficacy of CAD/CAM technologies in mandibular reconstruction (Metzler et al., 2014; Brandão et al., 2016; Zheng et al., 2012; Zavattero et al., 2021). Additionally, every study included small population sizes of participants, ranging anywhere from two participants recorded in depth (Zheng et al., 2012) to nearly 50 participants in both groups total. When explicitly stated, the measurements of accuracy and success varied greatly between each selected study due to the different experimental environments these studies were performed in. This deviation in millimeter differences of mandibular landmarks could possibly contribute to a false understanding of CAD/CAM effects. Because no uniform value was reported in every selected study, the true outcome of CAD/CAM techniques on mandibular reconstruction may be hindered. Finally, some studies involved the exclusion of some participants from the research due to death or lack of reconnection following surgery for a postoperative CT scan, among other reasons (Ren et al., 2018; Al-Sabahi et al., 2022; Metzler et al., 2014; Bartier et al., 2021; Chen et al., 2023).

4. Discussion

4.1 Summary of Main Results, Overall Completeness, and Applicability of Evidence 

A total of 12 selected studies were reviewed for their evaluations of mandibular reconstruction surgeries using CAD/CAM techniques. Amongst these 12 sources, a total of 327 participants were studied, with sample sizes that ranged anywhere from 5 to 65 participants. The earliest study included dates back 13 years to 2011 (Brandão et al., 2016), and the latest study took place in 2023 (Chen et al., 2023). Therefore, the included studies represent an accumulation of findings from recent and older studies, to illustrating the development of mandibular reconstruction techniques and technology over time. With the studies spanning longer than 10 years, the development of CAD/CAM surgical assistance can also be observed. While the earliest study in this review is just over 10 years old, this can be seen as relatively recent in the grand scheme of mandibular reconstruction research. Eight of the 12 studies included the surgical procedure and outcomes of a control group, in addition to the experimental group using CAD/CAM assistance (Ren et al., 2018; Al-Sabahi et al., 2022; Toto et al., 2014; Bartier et al., 2021; Weitz et el., 2016; Chen et al., 2023; Craig et al., 2014; Muñoz Guerra et al., 2001). The remaining four studies only included an experimental group (Metzler et al., 2014; Brandão et al., 2016; Zheng et al., 2012; Zavaterro et al., 2021). Eight studies generated specific postoperative measurements, later compared to the preoperative CT scan dimensions (Ren et al., 2018; Al-Sabahi et al., 2022; Metzler et al., 2014; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014; Zavattero et al., 2021) to denote surgical success. The smaller the deviation between preoperative facial dimensions/angles and postoperative results, the more successful the surgery and the CAD/CAM techniques employed. The study of dimensions from a surgical control group was seen more favorable in the results collection process for this review. If a study included pre- and post-surgical dimensions for the control, it allowed for raw comparisons to the dimensions of the CAD/CAM group.

Whether a control was included, all studies resulted in symmetrical success following FFF mandibular reconstruction with CAD/CAM techniques (Table 4). Because symmetry was determined through the analysis of postoperative measurements, the more postoperative measurements likely contributed to a more accurate symmetry evaluation. While some sources did not explicitly state the number of postoperative measurements made (Toto et al., 2014; Zheng et al., 2012; Antony et al., 2011), sources with a CAD/CAM group and a control group made more measurements than those without a control (Ren et al., 2018; Al-Sabahi et al., 2022; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014; Muñoz Guerra et al., 2001). One exception to this was the study with the most postoperative measurements (Zavattero et al., 2021). Additionally, a higher quality of life was determined according to both the frequency of the follow-up period and the indication of symmetrical results. Overall, if the patient received extensive care and attention through consecutive follow-up appointments, they were more likely to have a higher quality of life. Through more follow-up attention, the patient’s needs were more likely to be met. Sources that demonstrated a large range of follow-up appointments, beginning early post-operation (one week), produced more favorable results for this review (Ren et al., 2018; Al-Sabahi et al., 2022; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Zavattero et al., 2021; Antony et al., 2011; Muñoz Guerra et al., 2001). However, because not every study compared follow-up periods between two study groups, a higher QoL in patients of the CAD/CAM group cannot be concluded based on follow-up period. Regardless, it can be concluded that patients in the CAD/CAM group likely experienced a higher QoL with less post-surgical symmetrical deviation (Table 4). CAD/CAM effects were also addressed by analyzing the operation time for each study. According to Table 2, four of the studies proved that mandibular reconstruction with CAD/CAM techniques shortened the surgical time overall when compared to a group without CAD/CAM (Ren et al., 2018; Al-Sabahi et al., 2022; Weitz et al., 2016; Chen et al., 2023). Out of the six studies that stated operation times, only one recorded a longer operation time with CAD/CAM when compared to the control. However, one outlier this does not discredit most studies from Table 4 that confirmed the hypothesis (Bartier et al., 2021). Therefore, it is reasonable to note that CAD/CAM surgical use results in quicker surgical reconstruction.

4.2 Quality of the Evidence (Heterogeneity and Limitations of the Studies) 

Across the studies, there was a large amount of heterogeneity due to the various uses of CAD/CAM technology, symmetrical measurements, and postoperative management. Despite the variation in forms of measurement, as displayed in the results, the quality of the evidence was strong for all listed preoperative versus postoperative comparisons (Ren et al., 2018; Toto et al., 2014; Metzler et al., 2014; Bartier et al., 2021; Weitz et al., 2016; Chen et al., 2023; Craig et al., 2014; Muñoz Guerra et al., 2001). Varying methods of recording symmetrical success contributed to some inconsistencies amongst the results. For instance, one study may have taken 12 postoperative measurements across two study groups (Bartier et al., 2021), while another study may have taken 368 postoperative measurements across a CAD/CAM group only (Zavattero et al., 2021). However, these inconsistencies did not affect the broad assumption that CAD/CAM techniques are more efficient and accurate than free-hand methods. Additionally, the lack of both a control and experimental research group contributed to the general heterogeneity of the review. In doing so, the lack of two groups also decreased the quality of the comparative results. Not all studies emphasized the follow-up period (Toto et al., 2014; Craig et al., 2014; Muñoz Guerra et al., 2001) and the operation time (Metzler et al., 2014; Craig et al., 2014; Brandão et al., 2016; Zheng et al., 2012; Zavattero et al., 2021; Antony et al., 2011; Muñoz Guerra et al., 2001) within their research. This difference led to less data present to reinforce the experimental question which affected the quality of the results. The presence of smaller sample sizes (Ren et al., 2018; Metzler et al., 2014; Brandão et al., 2016; Zheng et al., 2012; Antony et al., 2011), various reasons for surgery, and various mean ages required more thorough comparisons across studies. Contrastingly, they could also present a deeper comparison of CAD/CAM use’s effect on specific mandibular osteotomies/reconstructions.

4.3 Future Research 

Future research should focus on specific kinds of CAD/CAM use and the impact it could have on specific mandibular deformities. Ideally, a study could isolate one method of CAD/CAM paired with a uniform diagnosis (squamous cell carcinoma, ameloblastoma, osteoradionecrosis, etc.). This described change could lead to more definitive conclusions about optimal CAD/CAM techniques catered to a single diagnosis. Additionally, certain deformities could be grouped to one geographical region or population of individuals. More specific grouping could demonstrate how CAD/CAM-assisted mandibular reconstruction can affect a population/demographic of people in furthering its research. More studies that emphasize operation time and/or symmetrical distances across a large study population would contribute valuable information to the research of CAD/CAM techniques in medicine. The use of CAD/CAM assistance in surgery is a growing application of medicine. Further research would increase the value of CAD/CAM assistance in any surgical field, not limited to mandibular reconstruction.

4.4 Potential Biases and Limitations in the Review Process 

This review may be subject to potential biases and limitations due to the use of only one database for source information, PubMed. Furthermore, the utilization of citation lists from selected sources for additional source information may have also presented selection bias. By pulling sources from a previously selected source the generalizability of findings was reduced. The heterogeneity present amongst the selected studies may have presented interpretation bias as the review aimed to find a common factor between each of the 12 studies. A thorough analysis of each source, was taken to ensure the most accurate conclusion and oppose biases. 

4.5 Agreements and Disagreements with Other Studies or Reviews 

The discussed findings agree with the general conclusion that CAD/CAM surgical techniques result in a more efficient and accurate procedure of mandibular reconstruction. It is evident that most research may not address the secondary effect of CAD/CAM techniques on the patient’s quality of life. However, a reasonable conclusion can be made through the postoperative management and symmetrical success illustrated in said studies. All studies/reviews on the surgical involvement of CAD/CAM contribute some form of symmetrical evaluation to prove surgical success. On the other hand, various pairings of CAD/CAM usage each provide successful surgical results amongst different studies. Therefore, not one set of CAD/CAM techniques have been proven to be the best method of assistance. Overall, this review confirms the idea that mandibular reconstruction is more efficient and accurate when CAD/CAM assistance is used, as opposed to the less efficient and difficult freehand method.

4.6 Conclusion

The findings of this systematic review conclude that CAD/CAM surgical involvement in mandibular reconstruction provides two things. Firstly, it provides a more efficient method of surgery, and secondly, it provides better symmetrical results. Successful usage of CAD/CAM in surgery also concludes that the patient is left with a higher quality of life when compared to surgery without CAD/CAM. Despite alternative methods of symmetrical evaluation and attention to operation time, the evidence indicates that CAD/CAM surgical methods produce favorable symmetrical facial measurements and shorter durations of operation/ischemia. The benefits of CAD/CAM can only be confirmed when compared to an alternative surgical control group. Regarding future research, studies that focus on CAD/CAM surgical techniques in specific demographic regions would potentially impact a greater understanding of CAD/CAM’s involvement in surgery and medicine.

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Acknowledgements: Dr. Holly Gallagher

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