The Drilling Guiding Templates and Pre-Bent Titanium Plates Improves the Operation Accuracy of Orthognathic Surgery With Computer-Aided Design and Computer-Aided Manufacturing Occlusal Splints for Patients With Facial Asymmetry

Virtual surgical plan with custom surgical guide for orthognathic surgery: systematic review and meta-analysis

BACKGROUND

The shift from traditional two-dimensional (2D) planning to three-dimensional (3D) virtual surgical planning (VSP) has revolutionized orthognathic surgery, offering new levels of precision and control. VSP, combined with computer-aided design/computer-aided manufacturing (CAD/CAM) technology, enables the creation of patient-specific surgical guides and implants that translate preoperative plans into more precise surgical outcomes. This review examines the comparative accuracy and operative efficiency of VSP, especially when used with custom surgical guides, against conventional 2D planning in orthognathic surgery.

MAIN TEXT

The study systematically reviewed and analyzed published literature comparing the accuracy and operative time between VSP and conventional planning methods. The meta-analysis included clinical trials, controlled trials, and observational studies on patients undergoing orthognathic surgery, focusing on the degree of alignment between planned and postoperative bone positions and total surgery time. Results indicate that VSP consistently reduces discrepancies between planned and actual surgical outcomes, particularly when integrated with custom surgical guides. Additionally, while VSP demonstrated potential time-saving advantages over conventional planning, these differences were not statistically significant across studies, likely due to high variability among study protocols and designs.

CONCLUSIONS

VSP with custom surgical guides enhances surgical accuracy in orthognathic procedures, marking a significant advancement over traditional methods. However, the reduction in operative time was not conclusively significant, underscoring the need for further studies to evaluate time efficiency. These findings emphasize VSP's role in improving surgical precision, which holds substantial implications for future orthognathic surgical practices.

3-Dimensional accuracy of navigation-guided bimaxillary orthognathic surgery: A systematic review and meta-analysis

The transfer of a virtual orthognathic surgical plan to the patient still relies on the use of occlusal splints, which have limitations for vertical positioning of the maxilla. The use of real-time navigation has been proposed to enhance surgical accuracy. This systematic review (PROSPERO CRD42024497588) aimed to investigate if surgical navigation can improve the three-dimensional accuracy of orthognathic surgery. The inclusion criteria were orthognathic surgery, use of intra-operative navigation and quantitative assessment of surgical accuracy. The exclusion criteria were non-bimaxillary orthognathic surgeries, non-clinical studies, studies without post-operative 3D analysis and publications not in the English language. A search of PubMed, Embase and Cochrane Library generated 940 records, of which 12 were found relevant. Risk of bias was assessed done using the Joanna Briggs Institute Critical Appraisal Checklist Tool. Among the included studies, there were nine of observational character and three randomized control studies (RCTs). All studies demonstrated promising outcomes with reported good surgical accuracy within a 2 mm difference between the planned and post-surgical result. Meta-analysis of two RCTs was carried out and results were in favor of surgical navigation with a total odds ratio of 4.44 [2.11, 9.37] and an overall effect outcome of Z = 3.92 (p < 0.0001). Navigation was up to 0.60 mm more accurate than occlusal wafers only (p < 0.001). However, there were variations in the application of surgical navigation and methods of analysis, leading to a heterogenous data set. Future studies should focus on standardized protocols and analysis methods to further validate the use of surgical navigation in orthognathic surgery. Despite some limitations, surgical navigation shows potential as a valuable tool in improving the accuracy of orthognathic surgery.

Evaluation of the Effect of Pre-bent Z-shaped Titanium Plate on Narrowing of Zygomatic Arch in L-shaped Reduction Malarplasty

OBJECTIVE

Pre-bent titanium plates are widely used for internal fixation in L-shaped zygomatic reduction. The aim is to evaluate the effect of pre-bent Z-shaped titanium plate on the narrowing of the zygomatic arch in L-shaped reduction malarplasty.

METHODS

Thirty cosmetic female patients were selected and scanned using computed tomography (CT). The CT images of pre-operation (T1) and post-operation(T2) were re-established through MIMICS26.0 (Materialise). After the 2 images were registered based on the skull base, the narrowing distance (ZRN) at the posterior end of the free zygomatic arch, as well as the preoperative and postoperative cross-sectional dimensions of the zygomatic arch, were measured. The ZRN and the altitude of the pre-bent titanium plate (TA) were compared using an independent t test, and their correlation was also analyzed using the Pearson coefficient. The preoperative and postoperative longest diameter (L1) and shortest diameter (L2) of the posterior zygomatic arch were compared using a paired t test.

RESULTS

The TA was 3.80±0.82 mm and the ZRN was 3.21±0.82 mm. The difference value was 0.59±0.41 mm, which was statistically significant. TA showed a strong correlation with ZRN (r=0.916, P=0.002). The L1 and L2 of the zygomatic arch root were slightly reduced postoperatively.

CONCLUSION

The pre-bent Z-shaped titanium plate does not completely correspond to the zygomatic arch narrowing distance in the actual application of L-shaped reduction malarplasty. However, it can control the narrowing distance of the zygomatic arch predictably, and achieve satisfactory surgical outcomes.

Accuracy and influencing factors of maxillary and mandibular repositioning using pre-bent locking plates: a prospective study

In-house repositioning methods based on three-dimensional (3D)-printing technology and the use of pre-bent plates has been gaining popularity in orthognathic surgery. However, there remains room for further improvement in methods and investigations on clinical factors that affect accuracy. This single-centre, prospective study included 34 patients and aimed to evaluate the accuracy and factors influencing maxillary and mandibular repositioning using pre-bent locking plates. The plates were manually pre-bent on the 3D-printed models of the planned position, and their hole positions were scanned and reproduced intraoperatively with osteotomy guides. The accuracy of repositioning and plate-hole positioning was calculated in three axes with the set landmarks. The following clinical factors that affect repositioning accuracy were also verified: deviation of the plate-hole positioning, amount of planned movement, and amount of simulated bony interference. The median deviations of the repositioning and hole positioning between the preoperative plan and postoperative results were 0.26 mm and 0.23 mm, respectively, in the maxilla, and 0.69 mm and 0.36 mm, respectively, in the mandible, suggesting that the method was highly accurate, and the repositioning concept based on the plate hole and form matching was more effective in the maxilla. Results of the correlation test suggest that large amounts of bony interference and plate-hole positioning errors in the up/down direction could reduce mandibular repositioning accuracy.

Surgical Guides and Prebent Titanium Improve the Planning for the Treatment of Dentofacial Deformities Secondary to Condylar Osteochondroma

PURPOSE

To investigate current Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) technologies applied in the treatment of dentofacial deformities secondary to condylar osteochondroma and introduce a modified method with additional pre-bent titanium miniplates to improve the accuracy of operation.

METHODS

Literature review about the application of CAD/CAM in the treatment of condylar osteochondroma and secondary dentofacial deformities was conducted. And 8 patients with condylar osteochondroma and secondary dentofacial deformities were treated by the CAD/CAM cutting and drilling surgical guides as well as pre-bent titanium miniplates. Pre- and post-operative 3D-cephalometric measurement were recorded and the difference between virtual simulation and postoperative modeling images was measured. Follow-up and radiographic examinations were performed.

RESULTS

A total of 17 studies (including 216 patients) about the application of CAD/CAM in the treatment of dentofacial deformities secondary to condylar osteochondroma have been reported since 2010, including the 8 present patients. In our study, all patients were satisfied with the surgical outcome, without obvious relapse or evidence of temporomandibular joint disorder or other complications during follow-up; all patients avoided condylar reconstruction and sagittal split of ramus osteotomy on the ipsilateral mandible side. Comparison between simulated plans and actual postoperative outcomes showed surgical simulation plan was accurately transferred to the actual surgery.

CONCLUSIONS

The application of CAD/CAM cutting and drilling guides as well as pre-bent titanium plates could achieve more accurate and favorable outcomes, improving the clinical planning and surgical execution for patients with condylar osteochondroma and secondary dentofacial deformities.

Ridge augmentation-The new field of computerized guided surgery: A technical note for minimal-invasive bone splitting

Different instrumentation procedures of the alveolar ridge expansion technique (ARST) with or without Guided Bone Regeneration have proven to be effective for successful implant placement in cases of alveolar bone width between 3mm and 6mm. Conventional bone splitting techniques require flap arising. This technical note demonstrates a method for flapless guided bone splitting. For this purpose, a newly developed surgical guide with internal irrigation channels was used. Using CAD-CAM additive technology, a narrow slot along the field of interest and a pin of a cooling pipe was designed and implemented in a surgical guide template. The bone split was performed flapless through the surgical guide while the cooling pipe was connected to it. During surgery, the piezo-driven instrument was moved within that slot, and the irrigation solution was directly rinsing it at point of entry through the irrigation channel. This procedure was performed on a 3.3 mm wide alveolar ridge achieving over 3 mm of bone gain. The described method combines several positive aspects. The micro-invasive flapless surgical procedure might improve postoperative healing. Additionally, sufficient cooling of the bone might lead to less thermal affection of bone cells and less resorption of the cortical bone. However, systematic studies are needed to confirm the observations of the presented case report.

Use of modified 3D digital surgical guides in the treatment of complex mandibular fractures

The objective of this study was to evaluate the use of 3D modified digital surgical guide plates combined with preformed titanium plates in the treatment of complex mandibular fractures. Patients with complex mandibular fractures were randomized into three groups. Group A was treated with a combination of 3D modified digital surgical guide plates and preformed titanium plates, Group B was treated with preformed titanium plates only, and Group C was treated conventionally. The key design point of the guide plates is the "slot" structure, which is crucial for accurately locating the preformed titanium plate. Clinical outcomes, including facial symmetry, surgical accuracy, and maximum deviation were quantitatively assessed postoperatively. Twenty-two patients were recruited for this study, eight for Group A, six for Group B, and eight for Group C. Group A exhibited better postoperative clinical outcomes. Among three groups, significant improvements were found in Group A for facial symmetry (S1 [0.74 ± 0.17 mm, P < 0.001], S2 [0.86 ± 0.21 mm, P = 0.004], S3 [0.92 ± 0.26 mm, P < 0.001], S4 [0.32 ± 0.09 mm, P < 0.001], S5 [0.47 ± 0.16 mm, P = 0.042], S6 [0.35 ± 0.04 mm, P = 0.001], S10 [0.50 ± 0.31 mm, P = 0.048], S11 [0.97 ± 0.29 mm, P = 0.018]) and surgical accuracy (T1 [R, 0.56 ± 0.18 mm, P = 0.021], T1 [L, 0.60 ± 0.30 mm, P = 0.022], T2 [L, 0.76 ± 0.21 mm, P = 0.006], T4 [R, 0.37 ± 0.15 mm, P < 0.001], T4 [L, 0.40 ± 0.15 mm, P = 0.001], T8 [R, 0.40 ± 0.15 mm, P = 0.007], T8 [L, 0.31 ± 0.29 mm, P = 0.001], T9 [L, 0.51 ± 0.33 mm, P = 0.042], T10 [R, 0.58 ± 0.28 mm, P = 0.049], T10 [L, 0.53 ± 0.34 mm, P = 0.046], T11 [R, 0.54 ± 0.13 mm, P = 0.021], T12 [0.45 ± 0.16 mm, P = 0.003]). The ideal postoperative effect was found in Group A with maximum deviation analysis. 3D printed modified digital surgical guide plates can effectively improve treatment outcomes in complex mandibular fractures.

Deformation Assessment of the Manually Pre-bent Titanium Miniplates in Orthognathic Surgery With Finite Element Analysis

This study summarized the literature regarding the application of pre-bent titanium miniplates in orthognathic surgery and evaluated the extra deformation of the manually pre-bent titanium miniplates via finite element analysis for acquiring higher surgical accuracy. The literature was reviewed with a chart. Three models of titanium miniplates with different thicknesses (1.0 mm, 0.8 mm, 0.6 mm) were created using COMSOL Multiphysics software for biomechanical behavior analysis. The 3 models were virtually bent into 5 angles (15 degree, 30 degree, 45 degree, 60 degree, 80 degree). respectively to simulate the preoperative virtual bending, then to simulate the practical manual bending via finite element analysis. The stresses and displacements of these models were recorded. The models from virtual bending simulation and manual bending simulation were registered to analyze the deviations. The results showed that the maximum stress and the displacement deviations between the virtual bending models and the manual bending models increased with the thickness and bending angle of the pre-bent miniplate models. To improve the surgical accuracy, measures should be applied to the manually pre-bent titanium miniplates to reduce the extra deformation when the plate being thicker and the bending angle being larger.