Splintless orthognathic surgery in edentulous patients—a pilot study

The aim of this pilot study was to evaluate the accuracy and predictability of a splintless treatment protocol for edentulous patients undergoing orthognathic surgery in four consecutive cases. All operations were virtually planned, followed by computer-aided design of individual osteotomy guides and patient-specific fixation implants, which were three-dimensionally printed in titanium. In order to evaluate the discrepancy between the planned and the achieved postoperative result, the postoperative outcome was compared to the virtual treatment plan. Rotational and translational movement and discrepancies with the planned movements were quantified for the maxilla; the advancement was quantified for the mandible. For the maxilla, there was a mean translation discrepancy of 0.6 mm. With regard to rotation, there was a mean discrepancy of 1.9°, 0.1°, and 0.4° for pitch, yaw, and roll, respectively. The mean discrepancy in translation of the mandible was 0.4 mm. The results of this pilot study indicate that the splintless treatment protocol for orthognathic surgery in edentulous patients presented here is accurate and predictable.     

Accuracy of mandible-independent maxillary repositioning using pre-bent locking plates: a pilot study

The double splint method is considered the gold standard for maxillary repositioning, but the procedure is lengthy and prone to error. Recent splintless methods have shown high repositioning accuracy; however, high costs and technical demands make them inaccessible to many patients. Therefore, a new cost-effective method of mandible-independent maxillary repositioning using pre-bent locking plates is proposed. Plates are bent on maxillary models in the planned position prior to surgery. The locations of the plate holes are replicated during surgery using osteotomy guides made from thermoplastic resin sheets. Pre-bent plates are subsequently fitted onto the maxilla, and plate holes are properly set to reposition the maxilla. The purpose of this study was to evaluate the accuracy of this method for maxillary repositioning and the reproducibility of the plate holes. Fifteen orthognathic surgery patients were evaluated retrospectively by superimposing preoperative simulations over their postoperative computed tomography models. The median deviations in maxillary repositioning and plate hole positioning between the preoperative plan and postoperative results were 0.43 mm (range 0–1.55 mm) and 0.33 mm (range 0–1.86 mm), respectively. There was no significant correlation between these deviations, suggesting that the method presented here allows highly accurate and reliable mandible-independent maxillary repositioning.     

Precision of orthognathic digital plan transfer using patient-specific cutting guides and osteosynthesis versus mixed analogue–digitally planned surgery: a randomized controlled clinical trial

Over the last decade, the accuracy of three-dimensional computer-assisted orthognathic surgery has been investigated extensively. The absence of high-quality controlled trials, limited number of studies overall, and methodological flaws have hindered its use in general clinical practice. The aim of this study was to assess the accuracy of computer-assisted orthognathic surgery compared to the classic occlusal wafers. Eighteen patients were randomly allocated to two groups: CAD/CAM splints and patient-specific osteosynthesis were used for maxillary positioning in group 1; occlusal wafers fabricated on a semi-adjustable articulator were used in group 2. Patients were assessed for linear and angular deviations of maxillary position from the virtual plan using cone beam computed tomography scans. The CAD/CAM group showed mean deviations of 0.26 mm vertically, 0.17 mm anteroposteriorly, and 0.07 mm mediolaterally, while the classic wafer group showed mean deviations of 1.45 mm vertically, 1.31 mm anteroposteriorly, and 0.71 mm mediolaterally. Statistical analysis showed that the proposed workflow provided a significantly more accurate plan transfer compared to classic occlusal wafers. Despite the statistical significance, the clinical significance was less appreciated. However, this new technology facilitated cases with skeletal asymmetry, reduced operating times, and allowed a trainee surgeon to perform the procedure with great accuracy and minimal time. The main limitation was the high cost.     

Comparison of three different types of splints and templates for maxilla repositioning in bimaxillary orthognathic surgery: a randomized controlled trial

The selection and implementation of a plan for maxillary surgery is of the utmost importance in achieving the desired outcome for the patient undergoing two-jaw orthognathic surgery. Some splint-based and splintless methods, accompanied by computer-assisted techniques, are helpful in improving surgical plan implementation. However, randomized controlled trials focused on this procedure are lacking. This study included 61 patients who underwent bimaxillary surgeries. The patients were randomly assigned to a conventional resin occlusal splint (CROS) group, a digital occlusal splint (DOS) group, or a digital templates (DT) group, in a 1:1:1 ratio. The mean linear distance between the planned and actual postoperative positions of eight selected points on the surfaces of the maxillary teeth was selected as the outcome measure. The distance was significantly smaller in the DT group (1.17 ± 0.66 mm) when compared to both the CROS group (2.55 ± 0.95 mm, P < 0.05) and DOS group (2.15 ± 1.12 mm, P < 0.05). However, the difference between the CROS group and DOS group was not statistically significant. These findings indicate that using digital templates results in the best performance in transferring the surgical plan to the operation environment as compared to the other two types of splints. This suggests that the application of digital templates could provide a reliable treatment option.     

Accuracy of fit analysis of the patient-specific Groningen temporomandibular joint prosthesis

Total joint replacement (TJR) with a prosthesis can be indicated for patients with severe temporomandibular joint (TMJ) dysfunction. Surgical accuracy is necessary for correct translation of the preoperatively predicted functional outcome, wear, and biomechanical behaviour of the patient-specific TMJ-TJR prosthesis. This study describes the first clinical applications of the patient-specific TMJ-TJR prosthesis according to the Groningen principles (G-TMJ-TJR), which was developed and validated in a prior human cadaver test study. The aim of this study was to validate the accuracy of placement of the patient-specific G-TMJ-TJR in the clinical setting. It was hypothesized that a virtual surgical plan (VSP) combined with guided placement of the patient-specific G-TMJ-TJR would be performed as predictably and accurately as in the prior cadaver series. All patients who received a VSP-based patient-specific G-TMJ-TJR between December 2017 and March 2020 were included in this study. The accuracy analysis was based on postoperative cone beam computed tomography (CBCT) data. All 11 prostheses could be inserted using routine pre-auricular and retromandibular surgical approaches. Analysis of the VSPs and postoperative CBCTs showed an average three-dimensional deviation of 1.07 mm (standard deviation 0.46 mm, range 0.33–1.91 mm) for all of the fossa and mandibular components. The patient-specific G-TMJ-TJR can be applied predictably and accurately in a clinical setting.     

Does a learning curve exist for accuracy in three-dimensional planning for maxillary positioning in bimaxillary orthognathic surgery?

The purpose of this study was to investigate the influence of time, and experience, on the accuracy of maxillary repositioning in bimaxillary orthognathic surgery performed using virtual surgical planning (VSP). Patients who had undergone bimaxillary orthognathic surgery were reviewed. Maxillary position on pre- and postoperative computed tomography scans was compared. The patients were divided into groups according to the year in which VSP was performed and surgery completed. Linear distances between upper jaw reference landmarks were measured in all three planes of space to determine accuracy between the preoperative VSP and the surgical outcome at various time points. One hundred subjects met the eligibility criteria for assessment and were allocated to groups: 2013 (n = 10), 2014 (n = 17), 2015 (n = 39), 2016 (n = 20), and 2017 (n = 14). Overall, the results demonstrated improved precision in maxillary position over the years, with more accurate results in patients who underwent surgery in 2015, 2016, and 2017. Mean linear differences between planned and obtained results demonstrated more accurate results in the horizontal direction, followed by transverse and vertical directions. An overall average difference within 1 mm was observed for 51.3% of the measurements included in the sample group. Time, and surgeon experience, can influence the accuracy of maxillary positioning in bimaxillary orthognathic surgery.     

Accuracy of maxillary repositioning surgery using CAD/CAM customized surgical guides and fixation plates

The advent of three-dimensional imaging and computer-aided surgical simulation (CASS) have brought about a paradigm shift in surgical planning. The aim of this study was to assess the accuracy of maxillary repositioning surgery using computer-aided design and manufacturing (CAD/CAM) customized titanium surgical guides and fixation plates. Thirty consecutive adult patients, 13 male and 17 female, with a mean age of 29.2 years and 25.5 years, respectively, requiring Le Fort I maxillary osteotomy, with or without simultaneous mandibular surgery, were evaluated retrospectively. All orthognathic surgeries were performed by one experienced surgeon. The pre-surgical and post-surgical volumetric imaging were superimposed to assess the linear and angular differences between the planned and actual positions of the maxilla following surgery. With the use of the CAD/CAM titanium surgical guides and fixation plates, all surgical movements were within 2 mm and 4° of the planned movements, which is considered clinically insignificant. The overall root mean square error between the planned and actual surgical movements was 0.38 mm in the transverse dimension, 0.64 mm in the anteroposterior dimension, and 0.55 mm in the vertical dimension. In regard to the centroid of the maxilla, the absolute angular difference of the maxillary centroid was 1.06° in pitch, 0.47° in roll, and 0.49° in yaw. Maxillary repositioning surgery can be performed with high accuracy using CAD/CAM titanium surgical guides and fixation plates.     

Accuracy of analytic model planning in bimaxillary surgery

The purpose of this study was to assess our method of analytic model planning in achieving a planned maxillary advancement for the correction of a dentofacial deformity. A consecutive series of 20 patients who underwent bimaxillary orthognathic surgery, at a minimum, were included in the study group. For each study subject, consistent analytic model planning with splint fabrication was used to establish the desired horizontal repositioning of the maxilla. Using preoperative and 5-week postoperative lateral cephalometric radiographs, an analysis was designed to assess the difference between the planned and actual advancement of the maxilla. The average difference between the planned and actual 5-week postsurgical advancement of the maxilla was 0.6 mm (range 0.2–1.0, P > 0.05). There was a strong correlation between the two data sets (R = 0.96). The results of the study indicate that the described method of analytic model planning is reliable (within 1 mm) in achieving the planned level of maxillary advancement in bimaxillary orthognathic procedures.     

Assessment of condylar changes after orthognathic surgery using computed tomography regional superimposition

This study aimed to investigate the effects of bimaxillary advancement orthognathic surgery on the condylar remodeling of the temporomandibular joint (TMJ) using voxel-based regional superimposition of cone-beam computed tomography (CBCT).In this retrospective study, the sample comprised 56 condyles from 28 healthy patients (aged from 16 to 50 years) with mandibular retrognathism treated with bimaxillary advancement. CBCT scans were taken preoperatively and at 14.3 ± 4.2 months postoperatively. The scans at the two time points were superimposed using regional voxel-based registration to assess condylar changes in the follow-up period. The linear alterations were measured in six different areas of each condyle to determine the pattern of condylar remodeling.Although no significant correlation was observed between changes in condylar surfaces, bone resorption occurred predominantly in the posterior and superior regions, while bone formation was predominantly on the anterior surface. Medial and lateral surfaces presented fewer bone changes. The overall bone changes were smaller than 1 mm bilaterally in 21 patients (75%) and, considering each condyle individually, were smaller than 1 mm in 48 condyles (85.7%).The results suggested that mild condylar remodeling in healthy patients is a common finding after orthognathic surgery. Future studies may clarify the mechanisms involved in the remodeling and help to understand the reasons for the remodeling pattern.     

Accuracy of maxillary repositioning in two-jaw surgery with conventional articulator model surgery versus virtual model surgery

The purpose of this study was to compare the accuracy of maxillary repositioning using the recently introduced computerized virtual model surgery (VMS) with conventional articulator model surgery (AMS). Forty-two patients who had undergone bimaxillary surgery were investigated retrospectively in this study. The patients were divided into two groups: conventional AMS (n = 23) and VMS (n = 19) for intermediate splint fabrication in maxillary positioning. Planned surgical movements and actual postsurgical changes of the lateral and frontal cephalometric measurements were compared. Although variations from the planned surgical movements were relatively small, both methods had statistically significant errors in some of the linear measurements. Both groups had a similar range of errors. The overall absolute mean discrepancy between the planned and actual surgical movements for the linear measurements was 1.17 mm (0–3.6 mm) in AMS and 0.95 mm (0–3.2 mm) in VMS. Of the total measurements, measurements reflecting a surgical discrepancy of more than 2 mm or 2° comprised 12.0% of the cases in AMS and 7.9% in VMS. The surgical accuracy of maxillary positioning with VMS was comparable to conventional AMS. Because VMS has the definitive advantage of eliminating the complex laboratory step and shortening the laboratory time, this can be accepted as an alternative to AMS.     

Orthognathic treatment with maxillary and mandibular anterior segmental osteotomy

This case report presents a case that underwent orthognathic treatment with anterior segmental osteotomies on both jaws. The patient was a 26-year-old female with maxillary protrusion, lip incompetence with an everted vermilion border. The overbite was +1.0 mm, overjet +1.0 mm. The pre-surgical orthodontic treatment included the extraction of the four first premolars and a multi-bracket treatment was started. After 12 months of pre-surgical orthodontic treatment, both the anterior maxillary and the anterior mandibular segments were retracted surgically by 5.5 mm. The total treatment period was 18 months. An anterior segmental osteotomy can induce the remarkable structural changes for bimaxillary lip protrusion patients.     

One-year assessment of surgical outcomes in Class III patients using cone beam computed tomography

The purpose of this study was to apply a novel method to evaluate surgical outcomes at 1 year after orthognathic surgery for Class III patients undergoing two different surgical protocols. Fifty patients divided equally into two groups (maxillary advancement only and combined with mandibular setback) had cone beam computed tomography (CBCT) scans taken pre-surgery, at splint removal, and at 1-year post-surgery. An automatic cranial base superimposition method was used to register, and shape correspondence was applied to assess, the overall changes between pre-surgery and splint removal (surgical changes) and between splint removal and 1-year post-surgery at the end of orthodontic treatment (post-surgical adaptations). Post-surgical maxillary adaptations were exactly the same for both groups, with 52% of the patients having changes >2 mm. Approximately half of the post-surgical changes in the maxilla for both groups were vertical. The two-jaw group showed significantly greater surgical and post-surgical changes in the ramus, chin, and most of the condylar surfaces (P < 0.05). Post-surgical adaptation on the anterior part of the chin was also more significant in the two-jaw group (P < 0.05). Regardless of the type of surgery, marked post-surgical adaptations were observed in the regions evaluated, which explain the adequate maxillary–mandibular relationship at 1-year post-surgery on average, with individual variability.     

Three-dimensional facial volume analysis using algorithm-based personalized aesthetic templates

Three-dimensional stereophotogrammetry is commonly used to assess volumetric changes after facial procedures. A lack of clear landmarks in aesthetic regions complicates the reproduction of selected areas in sequential images. A three-dimensional volumetric analysis was developed based on a personalized aesthetic template. The accuracy and reproducibility of this method were assessed. Six female volunteers were photographed using the 3dMDtrio system according to a clinical protocol, twice at baseline (T1) and twice after 1 year (T2). A styrofoam head was used as control. A standardized aesthetic template was morphed over the baseline images of the volunteers using a coherent point drift algorithm. The resulting personalized template was projected over all sequential images to assess surface area differences, volume differences, and root mean square errors. In 12 well-defined aesthetic areas, mean average surface area and volume differences between the two T1 images ranged from −7.6 mm² to 10.1 mm² and −0.11 cm³ to 0.13 cm³, respectively. T1 root mean square errors ranged between 0.24 mm and 0.62 mm (standard deviation 0.18–0.73 mm). Comparable differences were found between the T2 images. An increase in volume between T1 and T2 was only observed for volunteers who gained in body weight. Personalized aesthetic templates are an accurate and reproducible method to assess changes in aesthetic areas.     

Relationship between dental crowding,skeletal base lengths,and dentofacial measurements

ObjectivesThe objectives of this study were to study the correlation between dental crowding, skeletal base lengths, and dentofacial measurements.Materials and methodsPretreatment dental casts and lateral cephalograms of randomly selected 45 Class I orthodontic cases divided into two groups according to the severity of mandibular crowding were evaluated. Group 1 comprised 15 patients with mandibular crowding less than 3 mm while group 2 comprised 30 patients with mandibular crowding of 3 mm or more. Maxillary and mandibular dental crowding and dentofacial measurements were compared between the two groups. For correlations the whole sample was combined to a single group where crowding was used as a continuous variable.ResultsThe only significant difference (p = 0.000) between the two groups was in the amount of dental crowding in the lower arch. Direct moderate correlation (r = 0.45; p = 0.002) between maxillary crowding and mandibular crowding, direct high correlation (r = 0.68; p = 0.000) between maxillary base length (Co-A) and mandibular base length (Co-Gn) and also direct high correlation (r = 0.74; p = 0.000) between maxillary base position (SNA angle) and mandibular base position (SNB angle) were detected. Correlation between maxillary incisor position and facial vertical dimension measured by the MP to SN angle showed inverse moderate correlation. Correlation between mandibular incisor position and the anteroposterior jaw relationship measured by the ANB angle showed direct moderate correlation.ConclusionsResults showed the presence of correlation between the skeletal dimensions and the absence of correlation between dental crowding and the same measurements. Results suggest that dental crowding is independent of the skeletal measurements.     

Orthognathic treatment case after severe root resorption in the early treatment stage

This article presents an orthognathic treatment case after severe apical root resorption of maxillary anterior teeth using anterior segmental osteotomy.This case involved a 20-year-old female with the chief complaint of maxillary protruding and irregularly aligned mandibular anterior teeth. Her medical history showed no allergies or medical problems. The overbite was +3.0 mm, and the overjet +3.0 mm. After extraction of the four first premolars, a multi-bracket treatment was started. A severe root resorption of the maxillary anterior teeth was found 12 months after active treatment. The maxillary anterior segmental osteotomy was chosen as the compensatory treatment. The total treatment period was 2 years and 7 months. The post-retention panoramic radiograph showed no developmental root resorption.     

Precise control of maxillary multidirectional movement in Le Fort I osteotomy using a surgical guiding device

We introduced a surgical protocol to achieve accurate maxillary multidirectional movement in Le Fort I osteotomies. This comprised a way of controlling precision and a guiding device together with prebent titanium plates. We evaluated the protocol using a semiautomated 3-dimensional assessment in 22 patients with maxillary multidirectional movement (movement in three or more of six directions). Operations were all done between October 2015 and April 2017 by the same surgeon, who followed the protocol strictly. To evaluate the accuracy, we measured the deviation of the orientation of landmarks and of the upper dentition. All cases were followed up for at least a year. They all involved maxillary movement in at least three directions, and nine involved movement in six. The guiding device was used intraoperatively in all cases. Vertical deviation of the segments of bone was often detected during removal of bone, and sagittal deviation in three cases, but we found no transverse deviations. The assessment of accuracy showed that the mediolateral, anteroposterior, and superoinferior translations of landmarks were all less than 1 mm, with mean values of 0.29, 0.43, and 0.39 mm, respectively. The pitch, roll, and yaw of the upper dentition were also less than 1°, with mean values of 0.60°, 0.35°, 0.36°, respectively. The proposed protocol allowed accurate reposition of the maxilla with multidirectional movement during Le Fort I osteotomy.     

Magnetic resonance imaging for three-dimensional printing of the bony orbit: is clinical use imminent?

The aim of this study was to examine the accuracy of three dimensionally (3D) printed models of the bony orbit derived from magnetic resonance imaging (MRI) for the purpose of preoperative plate bending in the setting of orbital blowout fracture. Retrospective computed tomography (CT) and MRI data from patients with suspected orbital fractures were used. Virtual models were manually generated and analysed for spatial accuracy of the fracture margins. 3D-printed models were produced and orbital fan plates bent by a single operator. The plates were then digitized and analysed for spatial discrepancy using reverse engineering software. Seven orbital blowout fractures were evident in six orbits. Analysis of the virtual models revealed high congruence between blowout fracture margins on CT and MRI (n = 7, average deviation 0.85 mm). Three zygomaticomaxillary complex fractures were seen, for which MRI did not demonstrate the same accuracy. For plates bent to the 3D-printed models of blowout fractures (n = 6), no significant difference was found between those bent to CT versus those bent to MRI when compared for average surface and average border deviation (Wilcoxon signed rank test). Orbital blowout fractures can be defined on MRI with clinically acceptable accuracy. 3D printing of orbital biomodels from MRI for bending reconstructive plates is an acceptable and accurate technique.     

Precision of maxillary repositioning during orthognathic surgery: A prospective study

The purpose of this study was to evaluate the accuracy of surgical splints and an external reference point to reposition the maxilla during orthognathic surgery. Before surgery, a radiological marker was inserted inside the orthodontic bracket of the first right maxillary molar. A surgical splint was utilized to reposition the maxilla in the sagittal and coronal planes after the osteotomy. The vertical position was established by measuring the distance between a Kirschner wire inserted at bony nasion and the orthodontic wire. Preoperative and postoperative cephalometric radiographs were obtained and manually traced. The radiological marker and the tip of the right maxillary incisor were used as specific landmarks. Their displacement on the pre- and postoperative radiographs was measured. The actual surgical movement of the maxilla was compared to the initial surgical planning. 23 patients met the inclusion criteria to participate in the study. The mean difference between the planned and executed movements of the maxilla was 0.1 mm (p = 0.71). The difference was not statistically significant for any given movements of the maxilla. The use of surgical splints made from model surgery combined with an external reference point at bony nasion is accurate methods for repositioning the maxilla during orthognathic surgery.     

Can an entry-level 3D printer create high-quality anatomical models? Accuracy assessment of mandibular models printed by a desktop 3D printer and a professional device

This study was performed to determine whether an in-house printed mandible model is sufficiently accurate for daily clinical practice. Ten example mandible models were produced with a desktop 3D printer (fused filament fabrication, FFF) and compared with 10 equivalent mandible models fabricated using a professional-grade 3D printer (selective laser sintering, SLS). To determine the precision of the printed models, each model was scanned with an optical scanner. Subsequently, every model was compared to its original standard tessellation language (STL) file and to its corresponding analogue. Mean ± standard deviation and median (interquartile range) differences were calculated. Overall these were −0.019 ± 0.219 mm and −0.007 (−0.129 to 0.107) mm for all 10 pairs. Furthermore, correlation of all printed models to their original STL files showed a high level of accuracy. Comparison of the SLS models with their STL files revealed a mean difference of −0.036 ± 0.114 mm and median difference of −0.028 (−0.093 to 0.030) mm. Comparison of the FFF models with their STL files yielded a mean difference of −0.055 ± 0.227 mm and median difference of −0.022 (−0.153 to 0.065) mm. The study findings confirm that in-house 3D printed mandible models are economically favourable as well as suitable substitutes for professional-grade models, in particular considering the geometric aspects.     

Improvement in accuracy of maxillary repositioning of Le Fort I osteotomy with Orthopilot™ Navigation System: evaluation of 30 patients

Traditional model surgery with facebow transfer is not very accurate. We aimed to demonstrate that the Orthopilot™ Navigation System improves the accuracy of maxillary repositioning during Le Fort I osteotomy. Thirty patients underwent Le Fort I osteotomy alone or associated to sagittal split osteotomy. The maxilla positioning was done in two phases. First, the maxilla was positioned with the traditional occlusal splint, the position (“without Orthopilot™”) was recorded by the Orthopilot™. In the second phase, the Orthopilot™ was used to improve positioning; and the final position (“with Orthopilot™”) was recorded, after osteosynthesis. Positioning data were compared with planned data. Positioning data with and without the Orthopilot™ were also compared. Accuracy was classified in distinct classes with three major criteria (conformity, non-conformity, failure) according to the discrepancies. Conformity rate was significantly greater with the Orthopilot™ (2 without the Orthopilot™ compared with 8 with the Orthopilot™; p = 0.01). The failure rate was significantly lower with the Orthopilot™ (18 without Orthopilot™ compared with 7 with the Orthopilot™; p = 0.002). Dispersions of discrepancies were usually lower in all directions with the Orthopilot™. Navigation reduced the risk of discrepancy without cancelling it, especially when large movements are planned. The Orthopilot™ therefore improved the accuracy of traditional occlusal splint during Le Fort I osteotomy.