Double-jaw Orthognathic Surgery Research Articles

Bilateral ultrasound-guided maxillary and mandibular combined nerves block reduces morphine consumption after double-jaw orthognathic surgery: a randomized controlled trial

BackgroundDouble-jaw surgeries are known to be painful and to require opioids. Maxillary (V2) and mandibular (V3) nerves block could provide adequate pain management with minimal opioid-related side effects. Our main...

Evaluation of patient satisfaction with pharyngeal airway changes after orthognathic surgery in patients with Class III skeletal anomalies.

The aims of our study were to determine the changes in the pharyngeal airway after treating patients with Class III malocclusion who received double jaw surgery, to determine the hard tissue and soft tissue parameters and the hyoid bone and tongue positions after surgery, to determine the changes to compare the pretreatment and post-treatment measurements of the patients in the double jaw group with the measurements of the control group patients, and to evaluate postoperative patient satisfaction. The study included thirty-two Class III adult patients that received double jaw surgery and twenty-five Class I patients. Cephalometric records were taken before treatment (T1) and after treatment (T2). After double jaw orthognathic surgery, there were statistically significant changes in all pharyngeal airway linear and areal parameters (p<0.001). There were significant superior and posterior movements of the tongue and hyoid bone post-surgery. The post-treatment analysis of the double jaw surgery group and control group were compared, with statistically significant differences in the mandibular dental parameters and pharyngeal airway measurements in patients in the double jaw surgery group. Despite the narrowings detected, high satisfaction scores were observed in the patient satisfaction questionnaire and the patients did not experience respiratory problems.

What Is the Accuracy of Bimaxillary Orthognathic Surgery Using Occlusally-Based Guides and Patient-Specific Fixation in Both Jaws? A Cohort Study and Discussion of Surgical Techniques

The development of advanced digital orthognathic surgical protocols requires investigation to determine the accuracy of surgical outcomes. This report's purpose is to quantify 3-dimensional linear discrepancies between simulated and actual results for double-jaw orthognathic surgery utilizing occlusally-based guides in conjunction with patient-specific fixation in both jaws. This retrospective cohort study assessed the accuracy of double-jaw orthognathic surgery, in all cases performed by 1 surgeon between May 2019 and January 2021, utilizing occlusally-based guides and patient-specific fixation plates in both maxillary and mandibular surgeries. The primary outcome was absolute linear discrepancy between virtually-planned and surgically-achieved maxillary and mandibular position in 3 dimensions. Secondary outcomes were relative (directional) discrepancy, to assess if protocols erred in 1 direction of each surgical axis. Sequencing of bimaxillary surgery, age, and sex were covariates. Absolute and relative linear differences at A-point, B-point, and pogonion were evaluated using t tests. Descriptive statistics were amassed, and results were analyzed to determine if discrepancies differed from a null hypothesis of 2-mm error. Forty-nine patients were enrolled, consisting of 25 males and 24 females with a mean age of 24.8years. Thirty-five single-piece and 14 multipiece LeFort I osteotomies, 49 bilateral sagittal splits, and 35 genioplasties were studied; there were 22 maxilla-first and 27 mandible-first surgeries. Mean A-point absolute discrepancies of 0.57 (95% confidence interval: 0.41-0.73), 0.37 (0.24-0.50), and 0.45 (0.33-0.57) mm were observed in horizontal, transverse, and vertical planes, respectively. B-point discrepancies were 1.15 (0.79-1.52), 0.62 (0.47-0.78), and 1.14 (0.91-1.38) mm. Pogonion discrepancies were 1.29 (0.86-1.73), 0.85 (0.64-1.06), and 1.24 (1.00-1.49) mm. All P values were <.001. Sequencing of bimaxillary surgery did not alter absolute differences (P=.2 to>.9) with A-point discrepancies consistently smaller than B-point and pogonion discrepancies regardless of sequencing. Mandible-first surgery was associated with posterior directional error; both sequences were associated with superior directional error at B-point and pogonion. Bimaxillary orthognathic surgery utilizing a patient-specific protocol in both jaws produces results highly reproducible to planned simulated surgery and accurate below a 2-mm hypothesis, with maxillary discrepancies approaching 0.5mm and mandibular discrepancies approaching 1mm.

The Effects of Orthognathic Surgery on Periodontal Status

Background: The aim of this study was to investigate the effects of orthognathic surgery on periodontium in the 3rd and 6th months after the operation. Methods: In a total of 10 orthognathic surgery patients (7 females, 3 males, mean age 23.2 ± 4.83), full mouth clinical periodontal measurements as plaque index (PI), gingival index (GI), probing depth (PD), bleeding on probing (BOP), clinical attachment level (CAL), and mobility (M) were performed before the surgical procedure (T0) at 6 sites (mesio-buccal, mid-buccal, disto-buccal, mesio-lingual, mid-lingual, and disto-lingual) of all teeth except the third molars. Six of these patients underwent double jaw orthognathic surgery, 2 patients sagittal split osteotomy, and 2 patients Lefort 1 surgery. The same full mouth clinical periodontal measurements were repeated in the 3rd (T1) and 6th (T2) months after surgery. Results: There was no statistically significant difference between the T0 and T1 and T2 values in any of the parameters (PI, GI, PD, BOP, CAL, and M) at any of the regions measured (maxillary teeth, mandibular teeth, or full mouth). Conclusion: Within the limits of this study, it has been observed that orthognathic surgical treatments do not have a significant effect on periodontal status.

How much should incisors be decompensated? periodontal bone defects during presurgical orthodontic treatment in class III double-jaw orthognathic surgery patients

IntroductionThe aims of this study were to evaluate periodontal bone defects around the lower and upper incisors and to identify changes in the buccolingual inclination of the incisors during orthodontic decompensation in skeletal Class III orthognathic surgery patients. Materials and MethodsThe sample consisted of 26 adults with skeletal Class III deformity who had undergone presurgical orthodontic treatment and orthognathic surgery. Lateral cephalograms obtained before orthodontic treatment and before surgery were used to determine the inclination and position changes of the incisors. Cephalometric measurements were taken using Dolphin Imaging 11.95. Three-dimensional images were generated from cone-beam computed tomography (CBCT) scans prior to surgery and used to detect periodontal bone defects, including fenestration (F) and dehiscence (D). ResultsIntraclass correlation coefficients (ICC) were determined and the measurements showed high reproducibility. The cephalometric data showed normal distribution and there were no differences between genders in terms of cephalometric changes, dehiscence, fenestration, or coexistent (D-F/DF) formation. The patients presented maxillary incisor retroclination and mandibular incisor proclination, which was consistent with the tooth decompensation. CBCT assessment was performed for a total of 208 teeth; while 81 upper and 94 lower incisors had D-F/DF formation, 23 upper and 10 lower incisors were healthy. Statistically significant correlations were not found between the inclination degree of the incisors and D-F/DF formation. ConclusionsDecompensation of incisors during presurgical orthodontic treatment increases the risk of periodontal defects. There is no linear relationship between the increase in the inclination degrees of incisors and D-F/DF formation.

Ortognatik Cerrahi Hastalarında Postoperatif Doğruluğun ve Nüks Miktarının Değerlendirilmesi: Olgu Kontrol Araştırması

Objective: The success of orthognatic surgery depends on careful physical examination, correct diagnosis and good treatment planning. The aim of this study was to determine the accuracy of presurgical orthognatic planning and postoperative outcomes in single jaw or double jaw orthognathic surgery cases operated on in the Tokat Gaziosmanpaşa University Dentistry Faculty Department of Oral and Maxillofacial Surgery. Material and Methods: A total of 34 Class III patients were grouped in the form of bimaxillary osteotomy (Group 1), single jaw mandibular osteotomy with mandibular set-back (Group 2) and single jaw maxillary osteotomy with maxillary advancement (Group 3). Orthodontic analysis and measurements were performed on preoperative (T0), immediate postoperative (T1), 6 months (T2) and 12 months (T3) lateral cephalometric radiographs. Results: Based on multivariate analyses, there was no statistically significant difference in any of the groups between our T1-T0 values (p>0.05), with the exception of the distance of the ANS point from the vertical reference point (p=0.004). To evaluate the recurrence rates, the values between the T2- T1 and the T3-T1 periods were examined, and were not found to be statistically significant. However in Group 1, T3-T1 differences with regard to VR-ANS (p=0.003) and VR-L1 (p=0.033) showed a statistically significant recurrence. Conclusion: This study showed that the orthognathic surgical plan resulting from the methods we used were transferred to the surgery correctly. In addition, besides the postoperative orthodontic treatment, our techniques for fixation and osteotomy were effective in reducing the potential for relapse.

Assessment of changes in muscle activity using electromyography in patients undergoing orthognathic surgery

The aim of the present clinical trial study is to evaluate the effect of double jaw orthognathic surgery (OGS) on electromyographic activity of the masseter, anterior temporal, digastric, and sternocleidomastoid muscles in skeletal Class III patients. This prospective study included 10 patients who underwent Lefort 1 osteotomy of the maxilla and genioplasty of the mandible to correct skeletal dental class III malocclusion and presurgical and postsurgical EMG data were analyzed and compared. The participants underwent bilateral surface electromyography activity evaluation with a focus on the masseter, anterior temporalis, digastric and sternocleidomastoid muscles. Recordings were made each during 3 jaw positions: clench, resting and swallowing positions. The pre-surgical EMG data were compared with the post-surgical EMG data taken after 1 month to evaluate any changes in muscle activity. A significant increase in the average EMG activity after an orthognathic corrective surgery was observed. There were no significant postoperative changes in the EMG potentials of the anterior temporalis and masseter bilateral balance in the pre-op and post-op clench positions. Significant muscle posturing was observed in the post-op resting position with bilateral masseter, sternocleidomastoid, and right temporalis values&gt;2mcv with mandible and rest.

Accuracy of 3 Soft Tissue Prediction Methods After Double-Jaw Orthognathic Surgery in Class III Patients.

We aimed to evaluate the accuracy and validity of conventional manual prediction method (CM) and 2-dimensional and 3-dimensional (3D) soft tissue prediction methods for Class III bimaxillary orthognathic surgery patients. Twenty skeletal Class III patients were included in this study. Soft tissue prediction was achieved with a traditional manual technique, 2-dimensional software (Dolphin Imaging, version 11.5), and 3-dimensional software (SimPlant Master, version 16.0) on preoperative lateral cephalometric radiographs and cone beam computurized tomography (CBCT) images and then compared with postoperative lateral cephalometric radiographs obtained at least 6 months after surgery (mean, 11.5 ± 6.77 months). Forty-eight measurements were done to determine the reliability of the methods. All prediction methods have limited postsurgery prediction accuracy for the subnasal upper lip area. Most of the differences were not more than 3 mm for all study groups, except the 3D software, which predicted the upper lip area to be, on average, 3.08 ± 1.38 mm further back (P < 0.001). Although the conventional method predicted 20 of 48 measurements similar to the final results, the poorest predictions were found at the nasal and labiomental areas (P < 0.001). Two-dimensional software predicted 23 of 48 measurements very close to the final results but made significantly different predictions for the nasolabial and labiomental angles, labrale superius point, and the chin area. The 3D method predicted, especially the upper lip area, to be significantly and clinically incorrect, and its soft tissue prediction was insufficient compared with the other 2 methods. The 3D software needs to be updated, especially in evaluating soft tissue A point and upper lip changes after surgery.

Impact of orthognathic surgery on the prevalence of dehiscence in Class II and Class III surgical-orthodontic patients.

The objectives were to evaluate and compare the presence of bone dehiscence before and after orthognathic surgery. In this retrospective study, 90 cone-beam computed tomography (CBCT) scans from 45 patients were evaluated. Class II (n = 23) and Class III (n = 22) orthodontic patients who were being prepared for orthognathic surgery were measured. CBCT scans were obtained about 30 days prior to (T0) and 6 months after (T1) double jaw orthognathic surgery. The distance between the cemento-enamel junction (CEJ) and the alveolar bone crest was assessed at the buccal and lingual surfaces of all teeth, on both sides and arches, except for the second premolars and the second and third molars. A total of 1332 sites were measured for Class II (644) and Class III (688) patients. The software used was OsiriX (version 3.3 32-bit). Data were compared with Wilcoxon and McNemar tests at the 5% level. Bone dehiscence before surgery was present in 26% and 15% of the Class II and III groups, respectively. The presence of dehiscence increased to 31% in the Class II and 20% in the Class III patients after surgery (P < .05). The prevalence of dehiscence increased slightly in Class II and Class III surgical-orthodontic patients after orthognathic surgery. Temporary vascular supply reduction and oral hygiene difficulties may explain these results; however, more studies are needed.

Clinical Evaluation of Digital Dental Articulation for One-Piece Maxillary Surgery

Methods for digital dental alignment are not readily available to automatically articulate the upper and lower jaw models. The purpose of the present study was to assess the accuracy of our newly developed 3-stage automatic digital articulation approach by comparing it with the reference standard of orthodontist-articulated occlusion. Thirty pairs of stone dental models from double-jaw orthognathic surgery patients who had undergone 1-piece Le Fort I osteotomy were used. Two experienced orthodontists manually articulated the models to their perceived final occlusion for surgery. Each pair of models was then scanned twice-while in the orthodontist-determined occlusion and again with the upper and lower models separated and positioned randomly. The separately scanned models were automatically articulated to the final occlusion using our 3-stage algorithm, resulting in an algorithm-articulated occlusion (experimental group). The models scanned together represented the manually articulated occlusion (control group). A qualitative evaluation was completed using a 3-point categorical scale by the same orthodontists, who were unaware of the methods used to articulate the models. A quantitative evaluation was also completed to determine whether any differences were present in the midline, canine, and molar relationships between the algorithm-determined and manually articulated occlusions using repeated measures analysis of variance (ANOVA). Finally, the mean±standard deviation values were computed to determine the differences between the 2 methods. The results of the qualitative evaluation revealed that all the algorithm-articulated occlusions were as good as the manually articulated ones. The results of the repeated measures ANOVA found no statistically significant differences between the 2 methods [F(1,28)=0.03; P=.87]. The mean differences between the 2 methods were all within 0.2mm. The results of our study have demonstrated that dental models can be accurately, reliably, and automatically articulated using our 3-stage algorithm approach, meeting the reference standard of orthodontist-articulated occlusion.

Assessment of mandibular bony healing, mandibular condyle and angulus after orthognathic surgery using fractal dimension method.

This study aims to compare the trabeculation changes in the bone structure observed at the mandibular osteotomy line and the mandibular condyle in patients after single and double-jaw orthognathic surgery. The study included 38 patients (23 female, 15 male) who underwent mandibular surgery with bilateral sagittal split ramus osteotomy technique. The patients were divided into two groups according to their surgical operation: single-jaw (bilateral sagittal split ramus osteotomy) or double-jaw (Le Fort I osteotomy and bilateral sagittal split ramus osteotomy) surgery. Trabecular changes seen in mandibular osteotomy lines, mandibular condyle and mandibular angulus were evaluated on panoramic radiographs of patients (preoperative, postoperative 2nd day, postoperative 3rd month and 12th month) using fractal analysis method. Fractal dimension analysis was calculated by box counting method. No statistically significant difference was found between the fractal analysis values in the mandibular condyle and angulus region preoperatively, postoperative 2nd day, postoperative 3rd month and postoperative 12th month in the single jaw group. There was no statistically significant difference between the fractal analysis values in the mandibular condyle and angulus region preoperatively, postoperative 2nd day, postoperative 3rd month and postoperative 12th month in the double jaw group. A significant difference was found in fractal analysis values in osteotomy lines in both groups. The lowest value was found on the 2nd postoperative day and reached the preoperative values in the 3rd and 12th months postoperatively. Fractal analysis values didn't show significant difference between the single, double-jaw groups in all periods. This result suggests that the fractal analysis method can be used to evaluate trabeculation in the bone healing process of the osteotomy lines and indirectly affected areas in the postoperative period after orthognathic surgery.

Accuracy of three-dimensional planning in maxillary repositioning in double-jaw orthognathic surgery: how far along are we? a retrospective analysis of 100 patients

Accuracy of three-dimensional planning in maxillary repositioning in double-jaw orthognathic surgery: how far along are we? a retrospective analysis of 100 patients

Comparison of academic and nonacademic surgeons in treatment planning for CIII borderline case

Objectives In borderline class III malocclusions, the patients can be successfully treated by the orthodontic or surgical modalities, however; there is no consensus about the method with the best results regarding functional and esthetic parameters. The present study aimed to assess the treatment plans provided by academic and non-academic surgeons regarding borderline class III patients.Methods In this cross-sectional descriptive study, diagnostic records of 20 borderline class III patients were assessed by 8 academic and 8 non-academic surgeons. The treatment plans suggested by the surgeons for patients were compared with the standard treatment plan based on case presentation. The data were analyzed by paired t-test, Wilcoxon test, Kappa coefficient, independent t-test and Chi-square test.Results No significant differences were found between academic and non-academic orthodontists when suggesting orthodontic treatment (p=0.54), orthognathic surgery (p=0.1), single or double jaw orthognathic surgery (p=0.68) and the treatment plans in total (p=0.78) when compared with the standard treatment plan. The mean rate of agreement between the standard treatment plan and the academic and non-academic surgeons’ treatment plan for borderline class III patients was 75.0%±17.41% and 80.0%±17.73% for the orthodontic treatment plan, 80.0%±7.56% and 80.0%±17.73% for the surgical treatment plan, 70.55%±9.4% and 68.61%±9.08% for single or double jaw orthognathic surgery treatment plan, and 79.83%±7.76% and 80.63%±9.79% for the treatment plans in total, respectively.Conclusion Academic and non-academic surgeons both showed higher agreements with the standard treatment plan when suggesting orthodontic and orthognathic surgery treatment plans for borderline class III patients.

Residents' journal review

Residents' journal review

Is Counterclockwise Rotation With Double Jaw Orthognathic Surgery Stable in the Long-Term in Hyperdivergent Class III Patients?

To evaluate the long-term postsurgical stability of counterclockwise rotation of the occlusal plane (OP) in double-jaw orthognathic surgery in patients with hyperdivergent Class III malocclusion. This retrospective cohort study evaluated the postsurgical stability of orthognathic surgery in patients with skeletal Class III malocclusion and counterclockwise rotation of the maxillomandibular complex with an OP change of at least -2°. Patients were evaluated with lateral cephalometric analysis before surgery, immediately after surgery, and at longest follow-up. The primary predictor variable was the change in angle of the OP and the Frankfort horizontal (FH) after surgery. The primary outcome variable was stability of the OP at longest follow-up. Other study variables were age, gender, and the following cephalometric measurements: mandibular plane angle; gonial angle; angle formed by the sella, nasion, and B point; maxillary height; angle of the palatal plane to the line connecting the sella and nasion; and distances of the posterior nasal spine and A point to the FH and of the A point to the vertical line passing from the nasion. The Mann-Whitney U test was used to compare stability between groups because the variables were not normally distributed. Bonferroni correction was used to evaluate Pvalues. The χ2 test and Fisher exact test, where appropriate, were used to compare the proportions of groups. A P value less than .05 was accepted as statistically significant. The sample was composed of 15 adult patients (mean age at surgery, 23.5yr; 40% men). The median duration of follow-up was 48months (interquartile range, 36 to 60months). The groups had similar demographic properties and similar surgical changes. Ten patients showed very stable results with an OP-FH change no greater than 1°. Four patients showed unstable results with an OP-FH change of 2.25±0.5° during the follow-up period. The change in the mandibular plane angle was notable between patients with stability and those with instability, which was the variable most affected by relapse of the OP. This study found long-term postsurgical skeletal stability of counterclockwise rotation of the OP during double-jaw orthognathic surgery in patients with high angle Class III malocclusion after a median follow-up of 48months.

Dentoskeletal parameters related to visual perception of facial asymmetry in patients with skeletal class III malocclusion after orthognathic surgery

The purpose of the study is to explore the critical parameters determining the visual perception of postoperative facial symmetry. This study retrospectively included 24 patients with skeletal class III malocclusion and double-jaw orthognathic surgery (OgS). The patients were classified according to the outcome of subjective visual perception scores (SVPS) based on the postoperative frontal images by 10 orthodontists: symmetrical surgical outcome (S group, n=12) and facial asymmetry after surgery (A group, n=12). The 3D dentofacial measurements from cone beam computed tomography, were compared between the S and A groups. The relationship of all variables in all patients with the SVPS was explored by Spearman correlation coefficient. Significant differences were observed in the midline parameters in the mandible, the B point, gnathion and menton, and the mandibular border axis as well as in the discrepancy of the chin morphology between the two groups (P<0.05). The findings demonstrated that the midline parameter deviation, shape of the mandibular border, and the contour of menton morphology play the major role in the visual perceptions of postoperative asymmetry.

Effect of orthognathic surgery on masticatory performance and muscle activity in skeletal Class III patients

Objective: To evaluate the effect of double jaw orthognathic surgery (OGS) on masticatory performance and electromyographic activity of the masseter and anterior temporal muscles in skeletal Class III patients.Methods: Individuals were instructed to chew standardized round tablets of silicone impression material. The cumulative weight percentage was calculated using sieve analysis. The bilateral surface electromyographic activity of the muscles was evaluated. Following the orthodontic treatment, a stabilization splint was fabricated. Patients were instructed to wear it full-time until the surgical procedure occurred. Recordings were performed before the splint application (T0), after the splint application (T1), 1 month after the OGS (T2), and 6–8 months after the OGS (T3).Results: Median particle size of the chewed silicone material did not differ from T0 to T1 with the use of an occlusal splint (p > 0.05). However, it decreased from 9.46 to 6.92 cm from T2 to T3. From T0 to T3, a statistically significant decrease was found, following the surgical intervention (p < 0.01). A significant decrease in masticatory muscle activity was also observed during the relaxation test from T0 to T3, at which time it reached the control group value.Discussion: OGS enhanced masticatory function by improving occlusion in individuals with a dentofacial deformity.

Computer-assisted surgical planning and simulation for unilateral condylar benign lesions causing facial asymmetry

The purpose of this study was to investigate the best surgical sequence for the treatment of unilateral condylar benign lesions causing facial asymmetry by applying computer-assisted surgical planning and simulation. Computed tomography (CT) data from 12 patients whose maxillary cant was corrected by maintaining the vertical position of the central incisors and equally intruding the long side of the maxilla and extruding the short side were analyzed by ProPlan CMF 1.4 software (Materialise Medical, Leuven, Belgium). Condylectomy and double jaw orthognathic surgery with 2 different surgical sequences were simulated: 1) maxillary LeFort I osteotomy first (MaxF), then condylectomy, followed by bilateral sagittal split ramus osteotomy (BSSO); and 2) mandible first (ManF), beginning with condylectomy, then BSSO, and lastly LeFort I osteotomy. The greatest space between the maxillary and mandibular first molar in the interim positions was measured virtually to compare the 2 surgical sequences. The vertical distance between the upper and lower teeth of ManF patients was significantly smaller than that of MaxF patients (mean 2.99mm, P<.001). When occlusal cants are corrected by equally intruding one side and extruding the other side of the maxillary dentition, the interim position is more conducive to sequencing corrective surgery by performing condylectomy, then BSSO, followed by Le Fort I osteotomy.

Effects of oral clonidine premedication on hemodynamic status in bimaxillary orthognathic surgery: A double-blind randomized clinical trial.

Controlled hypotension during a surgical procedure is a way to decrease blood pressure and subsequently to improve the field of operation. Clonidine is an antihypertensive agent used for induced hypotension. Correction of maxillomandibular discrepancies may necessitate performing osteotomy on both jaws in many cases. Bimaxillary orthognathic surgery is a procedure that is associated with significant blood loss. A total of 30 participants who were candidates for double-jaw orthognathic surgery were classified into two groups with equal numbers. In one group, 300μg oral clonidine premedication was administered 90min before the operation, and in the other group a placebo with the same condition as in the first group. Mean arterial pressure (MAP) and heart rate at 10min intervals, operation time, blood loss, and surgeon satisfaction were measured. A total of 10 men and 5 women with a mean age of 22.9±2.9 years in the study group and 13 men and 2 women with a mean age of 22.1±2.1 years in the control group were evaluated. The MAP was significantly lower in the clonidine group (P<0.001). Intraoperative bleeding was 508.67±46.2mL in the placebo group and 287.33±72.06mL in the clonidine group, and the difference was statistically significant (P<0.05). Significant differences were observed in operation time (P<0.05) and surgeon satisfaction (P<0.001). The authors of this study suggest clonidine premedication in bimaxillary orthognathic surgery. Hemodynamic stability, bleeding control, decrease of operative time, and enhancement of surgical results are advantages of this method.

Algorithm for planning a double-jaw orthognathic surgery using a computer-aided surgical simulation (CASS) protocol. Part 1: planning sequence

The success of craniomaxillofacial (CMF) surgery depends not only on the surgical techniques, but also on an accurate surgical plan. The adoption of computer-aided surgical simulation (CASS) has created a paradigm shift in surgical planning. However, planning an orthognathic operation using CASS differs fundamentally from planning using traditional methods. With this in mind, the Surgical Planning Laboratory of Houston Methodist Research Institute has developed a CASS protocol designed specifically for orthognathic surgery. The purpose of this article is to present an algorithm using virtual tools for planning a double-jaw orthognathic operation. This paper will serve as an operation manual for surgeons wanting to incorporate CASS into their clinical practice.