Intermediate Splint Research Articles

In-house CAD/CAM fabricated repositioning guide in maxillary repositioning after Le Fort I osteotomy

ObjectiveThis study aimed to compare the accuracy of two transferring methods, which are the intermediate splint made by computer-aided design (CAD)/computer-aided manufacturing (CAM) and the customized maxillary repositioning guide for orthognathic surgery. Materials and methodsPatient data regarding virtual surgical simulations were collected. For analyzing the accuracy, the postoperative cone-beam computed tomography and preoperative simulation data were superimposed. The x, y, and z coordinates were obtained at three landmarks in the maxillary dentition, and the linear and angular differences between the surgical simulation and the actual surgery were evaluated. ResultsThirty-three patients were included in this study, 16 in the splint group and 17 in the guide group. One coordinate in the guide group and nine in the splint group showed errors of >2 mm, with a statistically significant difference. There was no significant difference between the two groups in the three-dimensional error distance at each reference point. In most measurements, the interquartile range of the guide group showed a narrower distribution than that of the splint group. ConclusionIt is more advantageous to use a customized maxillary repositioning guide than an intermediate splint made via CAD/CAM to obtain an accuracy within the 2 mm discrepancy range.

Does the Sequence of Bimaxillary Orthognathic Surgery Affect Accuracy in Skeletal Class III Patients?

BackgroundIt is necessary to determine whether the sequence of maxillary and mandibular surgeries in bimaxillary orthognathic surgery affects the accuracy of surgical outcomes. PurposeThe study aimed to measure and compare the accuracy among patients who underwent maxilla-first versus mandible-first bimaxillary surgery to correct a class III skeletal pattern. Study designThis retrospective cohort study included consecutive patients treated by a single surgeon at one center using Le Fort I and bilateral sagittal split osteotomy surgery. Exclusions included patients scheduled for one-jaw or maxilla-segmental surgery and those with craniofacial syndromes, such as clefts. Predictor variableThe predictor variable was operative sequence for bimaxillary operations, divided into maxilla- or mandible-first groups. Outcome variableThe outcome variable was accuracy, measured using linear discrepancies between landmarks in the virtual plan and actual operative outcomes. The measurement of linear discrepancy that was closer to 0 was considered the more accurate result. CovariatesSex, age, maxilla sagittal rotation degree, amount of posterior maxilla impaction, mandibular autorotation (°), and intermediate splint thickness (mm) were the covariates. AnalysesStatistical analysis was performed using Student’s t-test and Pearson’s correlation, with statistical significance set at P < 0.05. ResultsThe sample comprised 60 patients with a mean age of 22.8 ± 3.7 years, of whom 36 (60%) were male. In the maxilla-first group, there were 30 subjects (60% male; mean age: 23.1 ± 4.2 years), with a mean mandibular autorotation of 0.41° (range: 0°–2.5°). The mandible-first group comprised 30 patients (60% male; mean age: 22.6 ± 3.3 years), with a mean mandibular autorotation of 5.46° (range: 1.9°–9.2°). The linear discrepancies for all landmarks did not significantly differ between mandible- and maxilla-first groups (P > 0.18). The mean 3D discrepancies for all landmarks in maxilla-first group was 1.23 ± 0.5 mm and 1.23 ± 0.33 mm in mandible-first group, with no significant difference observed between the groups (P > 0.98). The amount of mandibular autorotation for intermediate splint application showed no significant correlation with the linear discrepancies (P > 0.58). ConclusionsIn patients with skeletal class III malocclusion, mandible-first surgery in bimaxillary orthognathic surgery demonstrates accurate outcomes comparable to maxilla-first surgery.

Three-dimensional positioning of the maxilla using novel intermediate splints in maxilla-first orthognathic surgery for correction of skeletal class III deformity.

Successful orthognathic surgery requires accurate transfer of the intraoperative surgical plan. This study aimed to (1) evaluate the surgical error of a novel intermediate splint in positioning the maxilla during maxilla-first orthognathic surgery and (2) determine factors influencing surgical error. This prospective study examined 83 patients who consecutively underwent Le Fort I osteotomy for correction of skeletal class III deformity using a novel intermediate splint and a bilateral sagittal split osteotomy. Surgical error was the outcome variable, measured as the difference in postoperative translational and rotational maxillary position from the virtual plan. Measures included asymmetry, need and amount for mandibular opening during fabrication of intermediate splints, and planned and achieved skeletal movement. Mean errors in translation for vertical, sagittal, and transversal dimensions were 1.0 ± 0.7mm, 1.0 ± 0.6mm, and 0.7 ± 0.6mm, respectively; degrees in rotation for yaw, roll, and pitch were 0.8 ± 0.6, 0.6 ± 0.4, and 1.6 ± 1.1, respectively. The transverse error was smaller than sagittal and vertical errors; error for pitch was larger than roll and yaw (both p < 0.001). Error for sagittal, transverse, and roll positioning was affected by the achieved skeletal movement (roll, p < 0.05; pitch and yaw, p < 0.001). Surgical error of pitch positioning was affected by planned and achieved skeletal movement (both p < 0.001). Using the novel intermediate splint when performing Le Fort I osteotomy allowed for accurate positioning of the maxilla. The novel intermediate splint for maxillary positioning can be reliably used in clinical routines.

Effect of offset on the precision of 3D-printed orthognathic surgical splints.

This study evaluated the effect of offset on the precision of three-dimensional (3D)-printed splints, proposing to optimize the splint design to compensate for systematic errors. 14 resin model sets were scanned and offset as a whole by given distances (0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40mm). Intermediate splints (ISs) and final splints (FSs) were generated from the non-offset and offset models and grouped correspondingly, named as splint type-offset value, IS-0.05, for instance. Dentitions occluded with the splint were scanned. Translational and rotational deviations of the lower dentition relative to the upper dentition were 3D measured. Deviations of ISs and FSs were more evident in the vertical and pitch dimensions, and were mostly acceptable in other dimensions. ISs with offset ≥ 0.05mm showed vertical deviations significantly below 1mm (P < 0.05) while ISs with 0.10- to 0.30-mm offsets had pitch rotations significantly lower than 1° (P < 0.05). The Pitch of IS-0.35 was significantly larger than ISs with 0.15- to 0.30-mm offsets (P < 0.05). Meanwhile, FSs fit better as the offset increased and FSs with offsets ≥ 0.15mm all had deviations significantly lower than 1mm (for translation) or 1° (for rotation) (P < 0.05). Offset affects the precision of 3D-printed splints. Moderate offset values of 0.10 to 0.30mm are recommendable for ISs. Offset values ≥ 0.15mm are recommended for FSs in cases with stable final occlusion. This study found the optimal offset ranges for 3D-printed ISs and FSs via a standardized protocol.

Are Virtually Designed 3D Printed Surgical Splints Accurate Enough for Maxillary Reposition as an Intermediate Orthognathic Surgical Guide.

The accuracy of the virtually-designed 3D-printed surgical splints requires investigation for the practical use of surgical plan in the operating room. This study aimed to compare the validity of the 3D-printed and the conventional intermediate splints and evaluate the outcomes after the surgical application of the 3D-printed splint compared with the predicted values. In this study, ten patients with dentofacial deformity were recruited. Participants were analyzed by the conventional surgical planning and virtual surgical planning. The intermediate surgical splints were created by the conventional and 3D-printing methods. Maxillary movements in 3 spatial directions were measured in an articulator after the application of both splints. Correlation and agreement between the two methods were tested by intraclass correlation coefficient (ICC). After the confirmation of 3D printed splint validity for each patient, the surgery was performed using 3D printed splints. It is assumed that ideally cephalometric prediction values are going to be obtained using conventional acrylic splints (gold standard). So, as a second objective, the outcome of the surgically-applied 3D-printed splint was evaluated and compared with the predicted values and finally analyzed by the paired t-test. Based on the observations, there was an excellent agreement between the virtually-designed 3D-printed and conventional intermediate surgical splints (ICC ranged between 0.83 and 0.99 for linear values). There was a good cumulative agreement of ICC greater than 0.80. Overall, the mean linear measurements were not different between conventional and 3D-printed splint on the articulator. Also, there were no significant differences between the linear and angular measurements of 2D-cephalometric prediction and postoperation values. The results showed cautiously the acceptable accuracy of the 3D-printed splints for several parameters in three spatial dimensions within the laboratory and clinical settings.

A Novel Orthognathic Surgery With a Half-Millimeter Accuracy for the Maxillary Positioning Using Prebent Plates and Computer-Aided Design and Manufacturing Osteotomy Guide.

This retrospective study aimed to assess the accuracy of prebent plates and computer-aided design and manufacturing osteotomy guide for orthognathic surgery. The prebent plates correspondent to the planning model were scanned with a 3-dimensional printed model for guide design and used for fixation. Forty-two patients who underwent bimaxillary orthognathic surgery using computer-aided design and manufacturing intermediate splint with the guide (guided group: 20 patients) or with conventional fixation under straight locking miniplates (SLMs) technique (SLM group: 20 patients) were analyzed. A deviation of the maxilla between the planned and postoperative positions was evaluated using computed tomography, which was taken 2 weeks before and 4 days after the surgery. The surgery time and the infraorbital nerve paranesthesia were also evaluated. The mean deviations in the mediolateral ( x ), anteroposterior ( y ), and vertical directions ( z ) were 0.25, 0.50, and 0.37mm, respectively, in the guided group, while that in the SLM group were 0.57, 0.52, and 0.82mm, respectively. There were significant differences in x and z coordinates ( P <0.001). No significant difference in the surgery duration and paranesthesia was seen, suggesting the present method offers a half-millimeter accuracy for the maxillary repositioning without increasing the risk of extending surgery duration and nerve complication.

Use of Submental Intubation in the Full-Face Makeover (Orthognathic Surgery, Facial Prosthesis Combined With Rhinoplasty).

Submental intubation is an intubation technique used for the management of airways in patients who suffered from complex maxillofacial trauma. Few studies focused on the role of submental intubation during Full-Face Makeover, like orthognathic surgery, facial prothesis, and rhinoplasty. Authors describe a case series of 5 patients who underwent to Full-Face Makeover with submental intubation to manage the airways. The authors started with the Le Fort I subspinal osteotomy. The maxillary repositioning was guided through a 3D printed intermediate splint in all cases (previously simulated with Dolphin software).Subsequentially, the bilateral sagittal split osteotomy was performed. The mandibular repositioning was guided through a 3D printed final splint. The genioplasty was performed with a horizontal osteotomy after a labial mucosa incision. After the genioplasty, the authors used the incision previously used for the Le Fort I osteotomy to bluntly dissect the tissues in order to insert a custom-made polyether ether ketone zygomatic prosthesis. Lastly, an open rhinoplasty was performed. All the surgery lasted a mean less 6 hours. The submental intubation was removed in the operating room, at the end of the surgery. The patients were then discharged from the hospital 2 days after the surgery in all cases. Submental intubation is a valid method for the airway management in maxillofacial trauma and can be extended in case of Full-Face Makeover like orthognathic surgery combined with rhinoplasty. The absence of nasal traumatism during surgery leads to a more accurate rhinoplasty, with a greater satisfaction for the patient.

Effect of occlusal coverage depths on the precision of 3D-printed orthognathic surgical splints

BackgroundPrecise orthognathic surgical splints are important in surgical-orthodontic treatment. This study aimed to propose a standardized protocol for three-dimensional (3D)-printed splints and assess the precision of splints with different occlusal coverage on the dentition (occlusal coverage depth, OCD), thus optimizing the design of 3D-printed splints to minimize the seemingly unavoidable systematic errors.MethodsResin models in optimal occlusion from 19 patients were selected and scanned. Intermediate splints (ISs) and final splints (FSs) with 2-mm, 3-mm, 4-mm, and 5-mm OCDs were fabricated and grouped as IS-2, IS-3, IS-4, IS-5, FS-2, FS-3, FS-4, and FS-5, respectively. The dentitions were occluded with each splint and scanned as a whole to compare with the original occlusion. Translational and rotational deviations of the lower dentition and translational deviations of the landmarks were measured.ResultsFor vertical translation, the lower dentitions translated inferiorly to the upper dentition in most of the splints, and the translation increased as OCD got larger. Vertical translations of the dentitions in 89.47% of IS-2, 68.42% of IS-3, 42.11% of IS-4, 10.53% of IS-5, 94.74% of FS-2, 63.16% of FS-3, 26.32% of FS-4, and 21.05% of FS-5 splints were below 1 mm, respectively. For pitch rotation, the lower dentitions rotated inferiorly and posteriorly in most groups, and the rotation increased as OCD got larger. Pitch rotations of the dentitions in 100% of IS-2, 89.47% of IS-3, 57.89% of IS-4, 52.63% of IS-5, 100.00% of FS-2, 78.95% of FS-3, 52.63% of FS-4, and 47.37% of FS-5 splints were below 2°, respectively. On the other hand, the transversal and sagittal translations, roll and yaw rotations of most groups were clinically acceptable (translation < 1 mm and rotation < 2°). The deviations of ISs and FSs showed no statistical significance at all levels of coverage (P > 0.05).ConclusionsA protocol was proposed to generate 3D-printed ISs and FSs with normalized basal planes and standardized OCDs. Deviations of the ISs and FSs were more evident in the vertical dimension and pitch rotation and had a tendency to increase as the OCD got larger. ISs and FSs with both 2-mm and 3-mm OCD are recommendable regarding the precision relative to clinical acceptability. However, considering the fabrication, structural stability, and clinical application, ISs and FSs with 3-mm OCD are recommended for accurate fitting.

Comparison of the Accuracy of Maxillary Positioning With Interim Splints Versus Patient-Specific Guides and Plates in Executing a Virtual Bimaxillary Surgical Plan

An extension of digital technology is to provide patient-specific hardware to reposition the first jaw in a bimaxillary case without the use of an intermediate splint. The purpose of our study was to determine if there were significant differences in maxillary repositioning using interim splints versus patient-specific guides and implants (PSIs) in executing a bimaxillary virtual surgical plan (VSP). This is a retrospective cohort study of patients who underwent bimaxillary orthognathic surgery with interim splints or PSIs planned with VSP at our institution. The difference in maxillary positions from the VSP to the postoperative cone-beam computed tomography (CBCT) was evaluated in both groups. The primary predictor variable was the method by which the maxilla was repositioned (interim splint vs PSI). The primary outcome variable was the postoperative 3D position of the maxillary incisors and right and left first molars in the anteroposterior, transverse, and vertical dimensions. Differences in the planned and postoperative positions of the above landmarks in all three planes of space between the two groups were statistically analyzed. A total of 82 patients were included. 13 patients had their maxillae repositioned with an interim splint between the unoperated mandible and the mobile maxilla, and 69 patients had their maxilla repositioned using custom drill/cutting guides and a PSI. The mean difference between the planned and actual position of the maxilla in the PSI group was smaller than in the splint group. In the PSI group alone, vertical changes were accurate whether the maxilla was being superiorly or inferiorly repositioned. The use of a PSI provides more accurate maxillary repositioning during bimaxillary surgery than the use of an interim splint.

Surgical Accuracy of Positioning the Maxilla in Patients With Skeletal Class II Malocclusion Using Computer-Aided Design and Computer-Aided Manufacturing-Assisted Orthognathic Surgery.

To evaluate the surgical accuracy of positioning the maxilla in patients with skeletal class II malocclusion using computer-aided design and computer-aided manufacturing (CAD/ CAM)-assisted orthognathic surgery. The samples consisted of 10 patients with skeletal class II malocclusion, whose cone-beam computed tomographys taken before and immediately after surgery were available and who underwent bimaxillary orthognathic surgery by a single surgeon using Le Fort I osteotomy and bilateral sagittal split ramus osteotomy at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital, Seoul, South Korea between January 2018 and December 2019. After virtual surgical planning was performed using the FACEGIDE system (Korea), surgical cutting guides, intermediate splints, and custom-made titanium mini-plates were fabricated using CAD/CAM technique. Using 8 landmarks (anterior nasal spine, point A, #16, #13, contact point between #11 and #21, #23, #26, posterior nasal spine), the mean differences between the virtually planned (Virtual) and actual postsurgical position of the maxilla (Actual) in the three-dimensional coordinates (ΔActual-Virtual) and their mean absolute deviations were investigated. The mean differences of 8 landmarks were 0.42 mm left side movement in the transverse coordinate, 0.15 mm forward movement in the sagittal coordinate and 0.10 mm downward movement in the vertical coordinate. Their mean absolute deviations were 0.98, 0.67, and 0.62 mm in the sagittal, vertical, and transverse coordinates, respectively. Since the mean difference was less than 0.5 mm and the range of error was less than 1.0 mm, CAD/CAM-assisted orthognathic surgery might have a high degree of surgical accuracy and clinical relevance in the positioning of the maxilla.

Robot-Assisted Maxillary Positioning in Orthognathic Surgery: A Feasibility and Accuracy Evaluation.

Several methods enabling independent repositioning of the maxilla have been introduced to reduce intraoperative errors inherent in the intermediate splint. However, the accuracy is still to be improved and a different approach without time-consuming laboratory process is needed, which can allow perioperative modification of unoptimized maxillary position. The purpose of this study is to assess the feasibility and accuracy of a robot arm combined with intraoperative image-guided navigation in orthognathic surgery. The experiments were performed on 12 full skull phantom models. After Le Fort I osteotomy, the maxillary segment was repositioned to a different target position using a robot arm and image-guided navigation and stabilized. Using the navigation and the postoperative computed tomography (CT) images, the achieved maxillary position was compared with the planned position. Although the maxilla showed mild displacement during the fixation, the mean absolute deviations from the target position were 0.16 mm, 0.18 mm, and 0.20 mm in medio-lateral, antero-posterior, and supero-inferior directions, respectively, in the intraoperative navigation. Compared with the target position using postoperative CT, the achieved maxillary position had a mean absolute deviation of less than 0.5 mm for all dimensions and the mean root mean square deviation was 0.79 mm. The results of this study suggest that the robot arm combined with the intraoperative image-guided navigation may have great potential for surgical plan transfer with the accurate repositioning of the maxilla in the orthognathic surgery.

One-splint versus two-splint technique in orthognathic surgery for class III asymmetry: comparison of patient-centred outcomes

ObjectivesTwo-jaw orthognathic surgery (OGS) is done using either the one-splint technique with free-hand positioning of the maxillomandibular complex or the two-splint technique with intermediate splints to position the maxilla. It is uncertain which technique achieves better outcomes. This study compares frontal soft tissue symmetry and subjective patient QoL between one-splint and two-splint techniques in skeletal Class III asymmetry patients undergoing OGS with three-dimensional surgical planning.Materials and methodsThis retrospective case-control study comprised 34 one-splint and 46 two-splint OGS patients. Frontal photographs and Orthognathic Quality of Life Questionnaire (OQLQ) were done pre- and post-treatment. Frontal soft tissue symmetry was analysed with the anthropometric Facial Symmetry Index. Measurements were compared with t-tests and chi-squared tests with p-value set at 0.05.ResultsThe groups differed in pre-treatment ANB and OQLQ scores. The two-splint group showed significant improvement in all symmetry measures. The one-splint group showed significant improvement in all symmetry measures except midface deviation, upper contour deviation and the Facial Contour Symmetry Index. Both groups showed significant improvement in OQLQ scores. There were no significant differences in post-treatment symmetry measurements and OQLQ scores between groups.ConclusionsAlthough two-splint technique may better improve contour symmetry, there were no significant differences in frontal soft tissue symmetry and QoL after OGS in skeletal Class III asymmetry with either one-splint or two-splint technique, with both techniques resulting in significant improvement.Clinical relevanceOne-splint and two-splint surgical techniques produce similar patient-centred outcomes in Class III asymmetry patients.

Randomized Controlled Clinical Trial to Assess the Utility of Computer-Aided Intraoperative Navigation in Bimaxillary Orthognathic Surgery.

Accurate application of the preoperative surgical plan in actual surgical settings is of paramount importance in orthognathic surgery. This randomized controlled clinical trial aimed to evaluate the accuracy of computer-aided intraoperative navigation (Ci-Navi) compared with that of conventional navigation methods in bimaxillary orthognathic surgery. Fifty-two patients were randomly divided into 2 groups. Group A (n = 26) patients underwent surgery assisted with Ci-Navi and group B (n = 26) patients underwent surgery assisted with conventional intraoperative navigation methods. During the operation, after LeFort I osteotomy, the mobile maxilla was repositioned to the designated position either using assistance from real-time Ci-Navi (group A) or using an intermediate splint (group B). Intra- and intergroup linear and angular differences between preoperative planning and postoperative outcomes were calculated. In group A, the overall mean linear difference was 0.79 mm (0.62 mm for the maxilla and 0.88 mm for the mandible) and the overall mean angular difference was 1.20°. In 23 cases, the difference from the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was less than 1 mm. In group B, the overall mean linear difference was 1.98 mm (1.76 mm for the maxilla and 2.02 mm for the mandible) and the overall mean angular difference was 2.08°. The difference from the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was less than 1 mm in 15 cases. This study demonstrates the utility of Ci-Navi is superior to the conventional methods in aiding the accurate repositioning of bony segments in bimaxillary orthognathic surgery.

Accuracy of splint vs splintless technique for virtually planned orthognathic surgery: A voxel-based three-dimensional analysis

PurposeThis study compared two transferring methods for virtually planned orthognathic surgery — the CAD/CAM intermediate splint and the customized surgical guide with fixation plates. MethodsThis was a prospective clinical study in which participants were consecutively recruited and underwent bimaxillary orthognathic surgery. They were divided into two groups based on the transferring method used. The pre- and postoperative CBCTs were aligned using voxel-based landmark-free registration, and the discrepancies for selected points were compared with the planned displacement of the virtually planned surgery. The maxilla and mandible were analyzed separately, and translation and rotation movements were considered. ResultsA total of 16 patients, divided into two groups of eight patients each, were included in this study. The splintless group was significantly more accurate for the translation movement along the x-axes for points A (p = 0.008; mean absolute error 0.527 ± 0.387 for the splint group and 0.137 ± 0.067 for the splintless group) and Ans (p = 0.045; mean absolute error 0.535 ± 0.446 for the splint group and 0.156 ± 0.002 for the splintless group). For the mandible there was a significant difference in accuracy along the x-axes for points B (p = 0.049; mean absolute errors 1.728 ± 1.181 and 0.697 ± 0.519 for the splint and splintless groups, respectively), LL3 (p = 0.049; mean absolute error 1.629 ± 0.912 and 0.851 ± 0.797 for the splint and splintless groups, respectively), LR3 (p = 0.049; mean absolute error 1.711 ± 0.906 and 0.844 ± 0.780 for the splint and splintless groups, respectively), with the splintless group being more accurate. For the rotation the splintless group was significantly more accurate along the y-axes (p = 0.04; mean absolute error 1.62 ± 0.78 and 0.49 ± 0.31 for the splint and splintless groups, respectively) and z-axes (p = 0.04; mean absolute error 0.63 ± 0.45 and 0.17 ± 0.05 for the splint and splintless groups, respectively) for the maxilla, while no significant difference was found for the mandible. ConclusionsOverall, the customized fixation plate system is more accurate than the intermediate CAD/CAM splint for transferring the virtual plan into the operation room.

EVALUATION OF THE USE OF BONE-BORNE CAD/CAM SURGICAL GUIDES IN ORTHOGNATHIC SURGERY CASES REQUIRING LE FORT I OSTEOTOMY

Background: Dentofacial deformities have many negative consequences in the form and function of head and neck region. It is estimated that in about 19% of orthodontic patients, orthognathic surgery is required along with the orthodontic procedure. The introduction of CAD/CAM technology in orthognathic surgery planning has facilitated the procedure and allowed for more predicted results. Aim of this study: The aim of the present study is to propose a new design of the intermediate stent that relates the mobilized maxilla to a fixed anatomical landmark in the skull which would allow for more accurate positioning of the maxilla during orthognathic surgery. Materials and methods: This study was conducted on sixteen patients who have been undergone Le Fort I osteotomy procedure. Eight of them were treated via a conventional stent while the other eight patients via a CAD/CAM bone-borne stent. Postoperative patient evaluation was performed by comparing the predicted and actual position postoperatively. This was done via 3D reconstruction CT scans. Results: Sixteen patients were recruited for the study (n=16), 5 males and 11 females, and were randomly allocated into two groups. Age ranged from 16 to 42 years with a mean of 24.31 ± 7.49. Pain evaluated by VAS was also found statistically insignificant between both groups using Independent samples t-test and Mann-Whitney U test (p < 0.05). Error of superimposition was found to be statistically significant between control group (0.317±0.22) and study group (0.870±0.23) using independent samples t-test (p < 0.05). Conclusion: The new intermediate splint design needs further modifications and refinement.

Accuracy of Splintless Maxillary Positioning in Orthognathic Surgery Using Patient-Specific Titanium Plates

Orthognathic surgery has traditionally been performed using stone model surgery. This process, with its multitude of laboratory steps, may be fraught with inaccuracies. Small errors in this process can get magnified downstream, resulting in altered maxillary and ultimately mandibular position and outcomes. With the advent of new technology, patient-specific maxillary cutting guides with predictive plate holes and 3D-printed plates have allowed surgeons to position the maxilla solely based on the patient-specific guide and plate. This eliminates the need for vertical reference markings, intermediate splints, and positioning the maxilla relative to the mandible. As this technology is relatively new, the goal of this study is to evaluate the accuracy of patient-specific surgical guides and plates in maxillary positioning at our institution.

Improving accuracy of the intermediate splint in substantial intermaxillary sagittal discrepancies using an extra anterior anchorage point: technical note.

Background To describe a technical feature that increases the stability of the intermediate splint in patients where bimaxillary surgery with great maxillary/mandibular advancements are planned. Material and Methods Prospective evaluation of the intermediate splint dental vertical penetration in patients undergoing bimaxillary surgery where great sagittal discrepancy occur in the anterior sector between the upper and lower jaws when the intermediate splint is placed by adding an extra intermaxillary fixation (IMF) screw (2x9 mm) placed between the central incisors of the maxilla and fixed to the most anterior aspect of the intermediate splint following the direction of the sagittal maxillo-mandibular discrepancy from January to September 2018. Results The postoperative evaluation comparing the accuracy of conventional fixation versus fixation with an extra anterior anchorage point through photographic assessment and intraoral digital scanner demonstrated better dental penetration, and therefore improved intermediate splint precision with the latter in all cases Conclusions Our results suggest that this is a simple and safe technique that can be easily reproduced and optimizes the outcomes by increasing the accuracy of translation of the planned surgical movements to the operating room. Key words:Orthognathic surgery, intermediate splint, accuracy, intermaxillary fixation, bone screw.

New protocol for in-house management of computer assisted orthognathic surgery

The aim of this study was to evaluate retrospectively the accuracy of a protocol for completely in-house, computer-assisted, orthognathic surgery, generating resin printed intermediate surgical guides. A retrospective, observational study was made on a cohort of 15 patients treated consecutively from September 2017 to May 2019, who underwent bimaxillary orthognathic surgery planned with the same 3-dimensional program and whose surgical intermediate splints were obtained with the same all-in-house protocol. Virtual planned surgical movements were compared with the real surgical outcome. The differences were not significant for eight of the 12 variables considered. The p values, calculated with the Wilcoxon signed rank test, were evenly distributed and ranged from p=0.001 to p=0.820. Significant differences were reported in four measurements: angle between sella-nasion plane and a line connecting the incisal edge and the apex of the root of the most prominent incisor (U1-SN) (p=0.001), angle between Frankfort plane and a line connecting the incisal edge and the root apex of the most prominent upper incisor (p=0.008), dental midline discrepancies (p=0.006), and occlusal plane tilt (U1-FH) (p=0.001), basically due to intraoperative settings. The 3-dimensional resin printed surgical guides were shown to be a reliable alternative to the commercial ones and showed high rate of accuracy for most of the variables assessed. Four out of 12 of these showed significant errors, but two of them were only minimal discrepancies with no clinical implications.

The Accuracy of Maxillary Position Using a Computer-Aided Design/Computer-Aided Manufacturing Intermediate Splint Derived Via Surgical Simulation in Bimaxillary Orthognathic Surgery.

The purpose of this study was to assess the clinical interventions and the accuracy of maxillary reposition using a computer-aided design/computer-aided manufacturing (CAD/CAM) splint derived via surgical simulation. The retrospective study comprised 24 patients who underwent bimaxillary surgery. The patients were assigned to 1 of 2 groups by a way of maxillary repositioning. One group received conventional intermediate wafers and the other CAD/CAM wafers during Le Fort I osteotomy. We recorded operation time, blood loss, the operative accuracy. Accuracy was analyzed by 3-dimensional computed tomography images before and immediately after the operation. The evaluation points were the right maxillary first incisor (U1), the right maxillary second molar (M2-right), and the left maxillary second molar (M2-left). The 2 groups did not differ significantly in operation time and blood losses. The vertical axis of U1 data differed significantly between the 2 groups (P = 0.008). None of the horizontal, vertical, or anteroposterior axis of M2-right data differed significantly, and anteroposterior axis of M2-left data differed significantly (P = 0.0296). The CAD/CAM group 3-dimensional distance errors were less than those of the conventional group for all points. Placement of CAD/CAM splint allowed highly accurate repositioning; the accuracy exceeded that afforded by conventional model surgery using a facebow and articulator.

Comparison of the postoperative and follow-up accuracy of articulator model surgery and virtual surgical planning in skeletal class III patients.

The aim of this study was to evaluate the postoperative and follow-up accuracy of using an intermediate occlusal splint between articulator model surgery (AMS) and virtual surgical planning (VSP) in double-jaw operations. Thirty skeletal class III patients were randomly allocated to have AMS or VSP. In the AMS group surgical planning was done through conventional articulator model surgery, and an intermediate occlusal splint made of acrylic resin was used. In the VSP group the surgical simulation was done virtually, and the same intermediate splint was used in the software and then fabricated using rapid prototyping technology. Preoperatively, one week postoperatively, and 1∼2-years later we obtained follow-up cone-beam computed tomographic (CT) images of each patient. Absolute linear differences between planned and actual outcomes, as well as planned and follow-up outcomes, were evaluated. There was no significant difference in either postoperative accuracy or follow-up accuracy between the methods, and there was no significant difference in the rate of skeletal relapse. Planning transfer by intermediate splint might therefore be the dominant factor in the final inaccuracies. The potentially greater accuracy of VSP may be realised with the help of new positioning devices instead of an intermediate splint.