Accuracy of a CAD/CAM surgical template for mandibular distraction: a preliminary study

Applications of three-dimensional imaging techniques in craniomaxillofacial surgery: A literature review

Three-dimensional (3D) imaging technologies are increasingly used in craniomaxillofacial (CMF) surgery, especially to enable clinicians to get an effective approach and obtain better treatment results during different preoperative and postoperative phases, namely during image acquisition and diagnosis, virtual surgical planning (VSP), actual surgery, and treatment outcome assessment. The article presents an overview of 3D imaging technologies used in the aforementioned phases of the most common CMF surgery. We searched for relevant studies on 3D imaging applications in CMF surgery published over the past 10 years in the PubMed, ProQuest (Medline), Web of Science, Science Direct, Clinical Key, and Embase databases. A total of 2094 articles were found, of which 712 were relevant. An additional 26 manually searched articles were included in the analysis. The findings of the review demonstrated that 3D imaging technology is becoming increasingly popular in clinical practice and an essential tool for plastic surgeons. This review provides information that will help researchers and clinicians consider the use of 3D imaging techniques in CMF surgery to improve the quality of surgical procedures and achieve satisfactory treatment outcomes.

A Proposal for the Classification of Temporomandibular Joint Disc Deformity in Hemifacial Microsomia

Hemifacial microsomia (HFM) is the second most common congenital craniofacial disease and has a wide spectrum of symptoms. The classic diagnostic criterion for hemifacial microsomia is the OMENS system, which was later refined to the OMENS+ system to include more anomalies. We analyzed the data of 103 HFM patients with magnetic resonance imaging (MRI) for temporomandibular joint (TMJ) discs. The TMJ disc classification was defined into four types: D0 for normal disc size and shape; D1 for disc malformation with adequate length to cover the (reconstructed) condyle; D2 for disc malformation with inadequate length to cover the (reconstructed) condyle; and D3 for no obvious presence of a disc. Additionally, this disc classification was positively correlated with the mandible classification (correlation coefficient: 0.614, p < 0.01), ear classification (correlation coefficient: 0.242, p < 0.05), soft tissue classification (correlation coefficient: 0.291, p < 0.01), and facial cleft classification (correlation coefficient: 0.320, p < 0.01). In this study, an OMENS+D diagnostic criterion is proposed, confirming the conjecture that the development of the mandibular ramus, ear, soft tissue, and TMJ disc, as homologous and adjacent tissues, is affected to a similar degree in HFM patients.

How accurate is computer-assisted mandible gunshot wound management by patient-specific distraction device? Preoperative planning versus postoperative outcomes

Gunshot wounds of the lower face are a challenge for the surgeon. Customized distraction osteogenesis (DO) is a well-established procedure for managing facial gunshot wounds. However, differences between the preoperative planning and postoperative outcomes are often noted. This multi-centre, retrospective study was performed to analyse the differences between the planning and outcomes for the lower third of the face, in patients undergoing the computer-assisted repair of mandible gunshot wounds using patient-specific distraction devices. Different planes and points were defined, and two distances (anteroposterior and intercondylar lengths) and an angle (inter-mandible body angle) were measured on the preoperative planning models and the postoperative models obtained from the computed tomography data. Twelve patient cases that met the study eligibility criteria were included. A significant difference between the planning and postoperative outcome was found for the anteroposterior length (6.6 mm shorter than the preoperative planning; P = 0.003). The differences in intercondylar length (P = 0.116) and inter-mandible body angle (P = 0.121) were not significant. This study revealed a difference between the planning and outcomes. Various factors such as scar tissue and muscle forces limit distraction and therefore lead to under-correction with insufficient projection.

Preliminary study of the accuracy and safety of robot-assisted mandibular distraction osteogenesis with electromagnetic navigation in hemifacial microsomia using rabbit models

This study aimed to investigate the accuracy and safety of mandibular osteotomy and distraction device positioning in distraction osteogenesis assisted by an electromagnetic navigation surgical robot. Twelve New Zealand white rabbits were randomly divided into two groups after computed tomography. The control group underwent a procedure based on the preoperative three-dimensional design and clinical experience. Animals in experimental group underwent a procedure with robotic assistance after registration. The accuracies of osteotomy and distraction device positioning were analysed based on distance and angular errors. The change in ramus length after a 1 cm-extension of the distraction device was for assessing distraction effect. The preparation, operative and osteotomy times, intraoperative bleeding, and teeth injury were used for safety assessment. In the experimental group, the distance (t = 2.591, p = 0.011) and angular (t = 4.276, p = 0.002) errors of osteotomy plane, and the errors in distraction device position (t = 3.222, p = 0.009) and direction (t = 4.697, p = 0.001) were lower; the distraction effect was better (t = 4.096, p = 0.002). There was no significant difference in the osteotomy time and bleeding; however, the overall operative and preparation times were increased in the experimental group, with a reduced rate of teeth damage. Robot-assisted mandibular distraction osteogenesis with electromagnetic navigation in craniofacial microsomia is feasible, safe, significantly improves surgical precision.

Application of Three-Dimensional Digital Technology in Orthodontics: The State of the Art

Three-dimensional technologies are one of the most recent and relevant advancements in the field of Dentistry. These systems, including intraoral scans, 3D imaging exams (CAT scan, CBCT and MRI), CAD/CAM 3D printing devices and 3D computer software, have enabled clinicians to greatly improve patient care along with reducing treatment planning time. The present descriptive study aims to explore possible applications of 3D technologies during the diagnosis, treatment plan, case monitoring and result assessment in orthodontics. The overall upgrade provided by these technologies can improve the clinicians’ workflow and effectiveness by simplifying conventional techniques considered to be especially arduous.

Comparison in clinical performance of surgical guides for mandibular surgery and temporomandibular joint implants fabricated by additive manufacturing techniques

Additive manufacturing (AM) offers great design freedom that enables objects with desired unique and complex geometry and topology to be readily and cost-effectively fabricated. The overall benefits of AM are well known, such as increased material and resource efficiency, enhanced design and production flexibility, the ability to create porous structures and on-demand manufacturing. When AM is applied to medical devices, these benefits are naturally assumed. However, hard clinical evidence collected from clinical trials and studies seems to be lacking and, as a result, systematic assessment is yet difficult. In the present work, we have reviewed 23 studies on the clinical use of AM patient-specific surgical guides (PSGs) for the mandible surgeries (n = 17) and temporomandibular joint (TMJ) patient-specific implants (PSIs) (n = 6) with respect to expected clinical outcomes. It is concluded that the data published on these AM medical devices are often lacking in comprehensive evaluation of clinical outcomes. A complete set of clinical data, including those on time management, costs, clinical outcomes, range of motion, accuracy of the placement with respect to the pre-operative planning, and extra complications, as well as manufacturing data are needed to demonstrate the real benefits gained from applying AM to these medical devices and to satisfy regulatory requirements.

Development of a novel mandibular distraction osteogenesis simulator using Computer Aided Design and 3D printing

INTRODUCTION

Micrognathia, a component of Robin Sequence, can cause glossoptosis, failure of palatal fusion, and critical obstruction of the airway. Mandibular distraction osteogenesis (MDO) is at times offered to anteriorly translate the mandible and tongue, relieving airway obstruction. MDO is an intricate reconstructive procedure that may be ideal for teaching using a high-fidelity educational simulator, allowing early hands-on experience in a zero-risk environment.

OBJECTIVES

To design a novel, low-cost, high-fidelity neonatal MDO simulator that can be used for trainee education and refinement of surgical technique.

METHODS

A novel MDO simulator was developed using additive manufacturing techniques. Three experts in MDO surgery completed a 20-item survey, rating the simulator's physical attributes, the realism of experience, the simulator's value, its relevance to practice and the surgeon's ability to perform tasks on a 4-point Likert scale.

RESULTS

Computer Aided Design (CAD) and 3D printing allowed for the production of a realistic surgical simulator that emulates important aspects of MDO surgery. This preliminary evaluation indicated adequate means across the five domains relevant to the simulator's fidelity and usability (M = 3.33 to 3.75) out of a maximum of 4 points. Lowest rated items were consistent with expert comments allowing future refinement on subsequent iterations. Consumable material costs per model were $9.39 USD.

CONCLUSIONS

The MDO model demonstrated adequate fidelity and holds promise as a skill-development tool for surgeons in training. Further studies are planned to determine its utility as a training and assessment tool.

Fully-customized distraction assembly for maxillofacial distraction osteogenesis: a novel device and its experimental accuracy verification

Background

A new distraction osteogenesis assembly system comprising a fully customized CAD/CAM-based fixation unit and ready-made distraction unit was developed. The aim of this study was to introduce our new distraction system and to evaluate its accuracy level in a sampled mandibular distraction osteogenesis.

Methods

Our system consists of a fully customized CAD/CAM-based fixation plate unit with two plates for each moving and anchoring part, and a ready-made distraction unit with attachment slots for fixation plates. The experimental distractions were performed on 3D-printed mandibles for one control and two experimental groups (N = 10 for each group). All groups had reference bars on the chin region and teeth to measure distraction accuracy. The control group had the classical ready-made distraction system, and experimental groups 1 and 2 were fitted with our new distraction assembly using a different distractor-positioning guide design. All distracted experimental mandibles were scanned by CT imaging, then superimposed on a 3D simulation to get their discrepancy levels.

Results

The measured 3D distances between the reference landmarks of the surgical simulations and the experimental surgeries for the three groups were significantly different (p < 0.0001) by statistical analysis. The errors were greater in the control group (with a total average of 19.18 ± 3.73 mm in 3D distance between the simulated and actual reference points) than those in the two experimental groups (with an average of 3.68 ± 1.41 mm for group 1 and 3.07 ± 1.39 mm for group 2). The customized distraction assembly with 3D-printed bone plate units in group 1 and 2, however, did not show any significant differences between simulated and actual distances (p > 0.999).

Conclusion

Our newly-developed distraction assembly system with CAD/CAM plate for the distraction osteogenesis of the mandible produced a greater level of accuracy than that of a conventional distraction device. The system appears to address existing shortcomings of conventional distraction devices, including inaccuracy in vector-controlled movement of the system. However, it also needs to be further developed to address the requirements and anatomical characteristics of specific regions.

Development and surgical application of a custom implant that enables a vertical vector of mandibular distraction

Hemifacial microsomia is a congenital malformation that involves the underdevelopment of the mandible and the ear leading to facial asymmetry. Distraction osteogenesis is the gold standard surgical procedure for severe cases of hemifacial microsomia in which two sectioned bone parts are lengthened gradually to promote bony infill. The final shape of the bone depends on the position of the distractor and the vector of distraction. This article presents a complex clinical case of a 7-year-old patient with severe hemifacial microsomia that required distraction to correct mandibular asymmetry. Digital technology was applied to virtually plan the surgery pre-operatively. Optimal symmetrisation required a vertical vector of distraction that none of the 'off-the-shelf' distractors could provide. Consequently, a three-dimensional printed titanium implant was designed as a spacer to be attached to the inferior plate of a standard distractor, allowing the achievement of a vertical vector. By adding the spacer, the inferior footplate of the distractor was not directly fixed to bone and the vector of distraction was not dictated by the anatomical contour of the patient but by the shape of the spacer. Surgical guides were created to translate the virtual plan to the operating room. The guides prevented potential damage to tooth buds and the inferior alveolar nerve. This article describes the three-dimensional computer-aided design and additive manufacture of the custom devices that delivered the following: (1) symmetrisation of the mandible after distraction surgery without manipulation of the healthy side of the mandible; (2) a feasible and safer surgical solution; and (3) an innovative method that enables a wider range of vectors of distraction, bringing new prospects to the treatment of distraction osteogenesis in the future.

Accuracy of a new custom-made bone-supported osteotomy and repositioning guide system for reconstruction of the mandibular ramus using costochondral grafts: a preliminary study

Mandibular reconstruction in patients with hemifacial microsomia is still challenging. In this study we have introduced a costochondral graft (CCG) for reconstruction of the mandibular ramus, and reported a bone-supported osteotomy and repositioning guide system for transfer of a virtual plan. Fourteen young children with Pruzansky type III hemifacial microsomia were included and treated with CCG to reconstruct the ramus. We first made 3-dimensional models for virtual planning and simulation, with calculations for both the position and direction of the CCG, to achieve optimal morphology. We did an osteotomy and manufactured them using a 3-dimensional printing technique. Accuracy was evaluated by comparing the plan with the postoperative outcomes. The largest linear root-mean-square deviation (RMSD) between the planned and the postoperative CCG was 4.41mm in the anteroposterior direction, while the largest angle RMSD was 19.25° in the horizontal plane. We suggest that the accuracy of this new custom-made guide system is clinically acceptable for transferring the position and direction of the CCG.