Inferior Maxillary Repositioning Remains Stable 1 Year After Surgery but Entails a High Risk of Osteosynthesis Failure.

PURPOSE: Inferior maxillary repositioning has continued to be among the most unstable orthognathic procedures. The overall purpose of the present study was to measure skeletal stability after inferior maxillary repositioning. MATERIALS AND METHODS: We implemented a retrospective cohort study. The study cohort was derived from all orthognathic patients who had undergone treatment from January 2011 to December 2013 in Odense University Hospital. The inclusion criteria were orthognathic surgery with inferior maxillary repositioning in patients without maxillary segmentation or cleft lip/palate. The exclusion criteria were nonattendance at follow-up visits or requiring reoperation before the 1-year follow-up point. The primary predictor variable was the time from the 1-week follow-up examination to the 1-year follow-up examination. The primary outcome variable was maxillary skeletal movement. The other variables of interest were age, gender, preoperative occlusal relationship, maxillary movement obtained, and surgery type (mono- or bimaxillary procedure). Skeletal stability was measured at the centroid, anterior, and posterior nasal spines using the semiautomatic measurement technique. Skeletal stability was clinically defined as less than 2 mm of movement in any direction. The positive directions for the 3 axes were right, anterior, and superior. The data were analyzed using mixed model linear regression analysis and 1-sample t tests. RESULTS: A total of 17 patients were included in the present study (mean age, 28 years; female gender, 35%; bimaxillary surgery, 59%). Inferior maxillary repositioning was stable with less than 0.3 mm mean skeletal movement in any direction. Only 1 patient had experienced a relapse of more than 1 mm in the posterior direction; no movement exceeded 2 mm. However, 3 patients were excluded from the present analysis, because they had required reoperation during the first year after surgery for osteosynthesis failure. CONCLUSIONS: Inferior maxillary repositioning was stable during the first year after surgery; however, the complication rate was high (15%). Thus, this procedure might still benefit from the use of more rigid patient-specific printed plates to increase postoperative stability.

Contemporary Techniques in Orbital Reconstruction: A Review of the Literature and Report of a Case Combining Surgical Navigation, Computer-Aided Surgical Simulation, and a Patient-Specific Implant.

PURPOSE: Complex orbital fractures can be surgically challenging because the orbital cavity contains several vital anatomic structures and visibility is limited. We present a case in which computer-aided surgical simulation (CASS), surgical navigation (SN), and a patient-specific implant (PSI) were used. Furthermore, the reported data regarding this topic were systematically searched and investigated. PATIENTS AND METHODS: A patient with a complex, failed orbital reconstruction was referred to our department. Despite the use of advanced tools, including a preformed PSI using a 1:1 mirrored, individual 3-dimensional model, several challenges remained. A systematic search of the relevant databases, scientific journals, and bibliographies of the included reports was conducted. Clinical studies involving CASS and SN in the treatment of at least 5 patients reported between 2016 and 2018 were included. RESULTS: The final reconstruction was planned virtually, and a milled PSI was produced and implanted under guidance of SN. The clinical outcome was acceptable to the patient. The literature search showed that superior results can be obtained when CASS and SN are involved in the treatment regimen. The average technical accuracy for SN has been reported to be less than 1 mm, and volume restoration has been reported to be significantly superior to that achieved with traditional methods. CONCLUSIONS: New technological advancements such as CASS involving SN seem to improve the outcomes of orbital reconstruction, especially in complex cases. Furthermore, planning, execution, and evaluation will be facilitated. Real-time guidance can also be used as a training tool for novice surgeons; however, factors such as financial investments, challenges in implementation, and a steep learning curve must be considered.

Does Mandible-First Sequencing Increase Maxillary Surgical Accuracy in Bimaxillary Procedures?

PURPOSE: In bimaxillary procedures, it is important to know how the chosen sequence affects the surgical outcome. The purpose of this study was to explore whether the theoretical advantages of using the mandible-first procedure were supported by clinical data. MATERIALS AND METHODS: The authors performed a retrospective investigation on a cohort compiled from 3 published retrospective studies. The sample was composed of patients treated at the Radboud University Nijmegen Medical Centre (Nijmegen, the Netherlands) from 2010 to 2014 and the Odense University Hospital (Odense, Denmark) from 2011 to 2015. The inclusion criterion was bimaxillary surgery without maxillary segmentation. The exclusion criterion was lack of a virtual surgical plan. The primary outcome variable was surgical accuracy, defined as the mean difference between the obtained outcome and the virtual surgical plan. The primary predictor variable was the comparison between mandible-first and maxilla-first sequencing. Secondary predictors were inferior maxillary repositioning and counterclockwise (CCW) rotation. The confounding variable was the virtually planned reposition. Results were analyzed by mixed-model regression encompassing all variables, followed by a detailed analysis of positive results using 2-sample t tests. RESULTS: Overall, 145 patients were included for analysis (98 women; mean age, 28 years). Operating on the mandible first notably influenced maxillary positioning and placed the maxilla 1.5 mm posterior and with 1.4° of CCW rotation compared with virtual surgical planning. The interaction of surgical sequence with maxillary rotation showed similar surgical accuracy between maxilla-first surgery with clockwise rotation and mandible-first surgery with CCW rotation. Inferior maxillary repositioning resulted in the maxilla being placed 1.7 mm (maxilla-first sequence) and 2.0 mm (mandible-first sequence) posterior to the planned position. CONCLUSION: Surgical accuracy was considerably influenced by sequencing in bimaxillary procedures. It remains important to know how the chosen sequence affects the surgical outcome so that the virtual surgical plan can be adjusted accordingly.

A 3-Dimensional Approach for Analysis in Orthognathic Surgery-Using Free Software for Voxel-Based Alignment and Semiautomatic Measurement.

PURPOSE: In orthognathic surgery, the repeatability of 3-dimensional (3D) measurements is limited by the need for manual reidentification of reference points, which can incorporate errors greater than 1 mm for every 4 repeated measurements. This report describes a semiautomatic approach to decrease the manual reidentification error. This study evaluated the repeatability of surgical outcome measurements using the semiautomatic approach. Furthermore, a step-by-step guide is provided to enable researchers and clinicians to perform the 3D analysis by themselves. MATERIALS AND METHODS: Evaluating surgical outcome consists of 2 parts. First, the scans are aligned at the anterior cranial base. Second, a semiautomatic approach is used to place 3 dental reference points at exactly the same sites of the pre- and postoperative maxilla. Because the maxilla is repositioned during surgery but otherwise unaltered, the reference points should be identical if the pre- and postoperative scans are aligned at the maxilla. Therefore, the authors propose the insertion of reference points on the preoperative scan and then repositioning a copy of the preoperative reference points relative to the postoperative scan. To align the reference points on the postoperative scan, the hard palate is used as a mutual maxillary reference structure. A reproducibility test was performed in 10 participants by analyzing the difference between repeated measurements. RESULTS: Repeated linear measurements differed by less than 0.1 mm along all 3 axes (standard deviations, <0.1 mm). The 2 largest differences between repeated measurements were 0.33 mm along the superoinferior axis and 0.29 along the anteroposterior axis. Repeated rotational measurements differed by less than 0.1° around all 3 axes (standard deviations, ≤0.1°). CONCLUSION: The semiautomatic approach showed excellent linear and angular repeatability. The algorithm can be implemented in the clinical evaluation of orthognathic surgical outcome and postoperative relapse.

Surgical Accuracy in Inferior Maxillary Reposition.

PURPOSE: Inferior maxillary repositioning is among the least stable and least predictable orthognathic procedures. The purpose of this study was to investigate whether posterior movement occurred with inferior maxillary repositioning and to analyze potential causes. MATERIALS AND METHODS: This retrospective observational study evaluated all consecutive patients treated at the Department of Oral and Maxillofacial Surgery of the Odense University Hospital (Odense, Denmark) with inferior maxillary repositioning from 2011 to 2013. The obtained repositioning was compared with the virtual surgical plan to determine surgical accuracy. Measurements were performed at 3 dental reference points. Linear and rotational measurements were performed along and around the right, anterior, and superior axes. Measurements were compared by paired t tests. Internal correlations and confounding variables were analyzed by mixed model regression analysis. RESULTS: Twenty patients were included for analysis. On average, the maxilla was positioned 1 mm posterior and 0.4 mm superior to the planned position. The virtual surgically planned reposition was statistically correlated with surgical accuracy. No other confounding variable influenced the outcome. CONCLUSION: The correlation between planned advancement and inferior repositioning suggests that inferior repositioning destabilizes the maxillary position and that a perioperative or early postoperative relapse occurs in response to the advancement. This immediate relapse of 1 mm should be considered in the virtual surgical plan to ensure that the maxilla is placed closer to the desired position. Thus, this procedure could still benefit from increased surgical precision and stability based on technologic advancements, such as positioning guides or printed patient-specific plates.

Patient-Specific Printed Plates Improve Surgical Accuracy In Vitro.

PURPOSE: It remains unclear to what extent patient-specific printed plates can improve surgical outcomes in orthognathic procedures. This study aimed to quantify the surgical accuracy of patient-specific printed plates in vitro and to compare the results with patients' actual surgical outcomes. PATIENTS AND METHODS: This in vitro study enrolled 20 postoperative orthognathic surgical patients, all treated with inferior maxillary repositioning. The preoperative midfaces were re-created in a 3-dimensionally printed model. The osteotomy and screw holes were placed at prespecified positions using a 3-dimensional guide. The dental segment was repositioned by means of the patient-specific plates. The primary outcome was the mean reposition at 3 dental reference points. The primary predictor variable was the obtained surgical reposition in vitro compared with the virtual surgical plan. Confounding variables were gender, age, occlusion, and bimaxillary surgery. The secondary outcome was surgical accuracy, and the secondary predictor was the in vitro outcomes versus the patients' surgical outcomes. Surgical accuracy was defined as the difference between the obtained reposition and the virtual surgical plan on a continuous scale. The differences were recorded in 3 dimensions according to the positive value of the 3 axes: right, anterior, and posterior. The results were analyzed using mixed-model regression and 1-sample t tests. RESULTS: In the 20 patients (age, 18 to 64 years; 40% of patients were women), the mean planned reposition was 2.9 mm anterior and 1.8 mm inferior. In all models, the osteotomy edge was rounded off to position the plate in the predetermined position. Overall, the maxilla was positioned 0.5 mm anterior and 0.3 mm inferior to the planned position using patient-specific plates. CONCLUSIONS: The patient-specific plates positioned the maxilla in close approximation to the planned position without surgically relevant differences. The osteotomy edge must be carefully inspected for interference with the patient-specific plates to avoid displacement of the planned maxillary repositioning.

Surgical Navigation: A Systematic Review of Indications, Treatments, and Outcomes in Oral and Maxillofacial Surgery.

PURPOSE: This systematic review investigates the most common indications, treatments, and outcomes of surgical navigation (SN) published from 2010 to 2015. The evolution of SN and its application in oral and maxillofacial surgery have rapidly developed over recent years, and therapeutic indications are discussed. MATERIALS AND METHODS: A systematic search in relevant electronic databases, journals, and bibliographies of the included articles was carried out. Clinical studies with 5 or more patients published between 2010 and 2015 were included. Traumatology, orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal were the areas of interests. RESULTS: The search generated 13 articles dealing with traumatology; 5, 6, 2, and 0 studies were found that dealt with the topics of orthognathic surgery, cancer and reconstruction surgery, skull-base surgery, and foreign body removal, respectively. The average technical system accuracy and intraoperative precision reported were less than 1 mm and 1 to 2 mm, respectively. In general, SN is reported to be a useful tool for surgical planning, execution, evaluation, and research. The largest numbers of studies and patients were identified in the field of traumatology. Treatment of complex orbital fractures was considerably improved by the use of SN compared with traditionally treated control groups. CONCLUSIONS: SN seems to be a very promising addition to the surgical toolkit. Planning details of the surgical procedure in a 3-dimensional virtual environment and execution with real-time guidance can significantly improve precision. Among factors to be considered are the financial investments necessary and the learning curve.

Surgical Splint Design Influences Transverse Expansion in Segmental Maxillary Osteotomies.

PURPOSE: In segmental maxillary procedures, it is imperative to obtain as much of the planned expansion as possible. Lack of obtained expansion, in addition to late relapse after splint removal, can result in relapse of the posterior crossbite. This study investigated the influence of 2 surgical splint designs on achieving the planned transverse expansion in bimaxillary surgery with segmental maxillary procedures. MATERIALS AND METHODS: Forty-two participants were included in a retrospective observational study. All participants had completed virtually planned bimaxillary surgery with 3-piece maxillary segmentation. The primary outcome variable was the transverse expansion obtained, measured as the expansion between the maxillary first molars on preoperative and postoperative cone-beam computed tomograms. The postoperative scan was performed 1 week after surgery with the splint still in place. To test measurement reliability, all measurements were performed twice by the same observer. The primary predictor variable was the planned expansion according to the virtual surgical plan. The primary covariate with influence on the obtained expansion was the surgical splint design. Other covariates of interest included patient age, patient gender, and surgeon. Descriptive and bivariate statistics were performed using Student t tests and linear regression analysis. RESULTS: Measurements showed high reliability, with an intraclass correlation coefficient of 0.99 and Bland-Altman plots without systematic errors. The obtained expansion was statistically different from the planned expansion (mean, -0.77 mm; standard deviation, 0.83). Surgical splint design meaningfully influenced transverse expansion: 77% of the planned expansion was obtained with high palatal coverage, whereas 50% was obtained with low palatal coverage. No other covariates influenced the expansion obtained. CONCLUSION: Not all the planned expansion is obtained during segmental bimaxillary surgery. Use of rigid surgical splints with high palatal coverage considerably improves the amount of expansion obtained and is recommended for segmental maxillary procedures.

Changes in Upper Airway Volume Following Orthognathic Surgery.

Reduced volume of the internal skeletal dimensions of the face is 1 of the main causes of obstructive sleep apnea, and attention to patients' airways is necessary when planning orthognathic treatment. This study aims to describe changes in upper airway volume following virtually planned orthognathic surgery.A retrospective pilot study was designed with 30 randomly selected patients (10 men and 20 women, aged 23.1 ±â€Š6.8 years, molar-relations: 15 neutral, 8 distal, and 7 mesial). Cone-beam computed tomography scans were performed before surgery and 1 week following surgery. The authors did total upper airway volume measurements and obtained 1-mm slices at vertical levels in the velo-, oro-, and hypopharynx and at the smallest visible cross-section.Measurements before and after surgery were compared using Student t test.After orthognathic surgery, the minimum cross-sectional area at the vertical level increased from 83 mm ±â€Š33 before surgery to 102 mm ±â€Š36 after surgery (P = 0.019). In patients with neutral and distal occlusions, the minimum cross-sectional slice volume increased in 87% but in only 57% with mesial occlusion.The present findings suggest that orthognathic surgery increases upper airway volume parameters, but a few patients have continued impairment of the airways following orthognathic surgery. Further studies are needed to confirm an individual surgical planning approach that potentially could bring the minimum cross sectional area out of the risk zone.

Accuracy and stability of the condyle position after orthognathic surgery: A retrospective study.

The purpose of this study was to evaluate the accuracy and stability of condylar positioning in patients treated with bimaxillary procedures compared with patients treated with maxillary procedures alone. All patients had undergone treatment at Odense University Hospital and were treated with inferior maxillary procedures. The primary outcome was changes in condyle position and the primary predictor variable was time: pre-operative (T0) measurements to 1-week post-operative (T1) and 1-year post-operative (T2) measurements. Condyle movement was measured using dual voxel-based alignment. Sixteen patients were included. Seven patients underwent solitary maxillary procedure and 9 patients bimaxillary procedure. Bimaxillary procedures overall showed a condyle positional change in pitch from T0 to T1 and T1 to T2 compared to maxillary procedures alone. Condylar translation was stable despite large differences in positioning. Compared to solitary maxillary procedures, bimaxillary procedures showed a statistically significant anterocranial rotation at 1-week follow-up movement (3.95° vs. -0.95°; SD 3,74 vs 1,05; P value = 0.000) and an additional statistically significant anterocranial movement at 1 year after surgery (4.89° vs 0.60°; SD 3,82 vs 0,92; P value = 0.000). In conclusion a need for greater anterocranial stability of the sagittal split osteotomy than that provided by 3 bicortically fixated screws alone might be indicated.

Novel Developments in the Treatment of Multiple Myeloma-Associated Bone Disease.

Osteolytic bone disease is present in about 80% of patients with multiple myeloma at the time of diagnosis. Managing bone disease in patients with multiple myeloma is a challenge and requires a multi-faceted treatment approach with medication, surgery, and radiation. The established treatments with intravenous or subcutaneous antiresorptives can cause debilitating adverse events for patients, mainly osteonecrosis of the jaw, which, traditionally, has been difficult to manage. Now, oral surgery is recommended and proven successful in 60-85% of patients. Patients with spinal involvement may benefit from surgery in the form of vertebroplasty and kyphoplasty for pain relief, improved mobility, and reestablished sagittal balance, as well as the restoration of vertebral height. These procedures are considered safe, but the full therapeutic impact needs to be investigated further. Ixazomib, the first oral proteasome inhibitor, increases osteoblast differentiation, and recently published preliminary results in patients treated with Ixazomib maintenance have promisingly shown increased trabecular volume caused by prolonged bone formation activity. Other novel potential treatment strategies are discussed as well.

Patient-specific 3D printed plates improve stability of Le Fort 1 osteotomies in vitro.

PURPOSE: Selective laser melting used to manufacture patient-specific 3D-printed (PSP) plates is a delicate process, which may introduce weakened areas in the plates, with risk of fracture. This in vitro study's purpose was to test the ability of PSP plates to stabilize Le Fort I osteotomies compared with manually adapted stock plates. The study's objectives were to measure the force needed to compress the osteotomy and evaluate whether the PSP plates would break during compression. MATERIALS AND METHODS: This controlled in vitro study evaluated the maxillary stability using the clinical data from 7 patients. The virtually planned maxillary reposition was 3D-printed in 2 copies, and the osteotomy gap was fixated by either PSP plates or stock plates. The models were compressed until the Le Fort I osteotomy gap was eliminated. The primary outcome was the force needed to compress the model. The primary predictor variable was a comparison between PSP and stock plates. Secondary outcome measurements were the slope of elastic modulus, yield point, and force needed for 2 mm compression. Statistical testing was performed by Wilcoxon signed-rank test with significance level at P ≤ 0.05. RESULTS: The PSP plates performed better than stock plates in all outcome measurements. None of the plates broke during compression despite forces of more than 4000 N. The first point of failure in PSP plates was the first screw cranial to the osteotomy. In comparison, the first point of failure in stock plates was in the plates' bend at the osteotomy. CONCLUSION: In this in vitro setup, the Le Fort I osteotomies fixated with PSP plates were more stable than the osteotomies fixated with conventional stock plates. No adverse effects occurred during testing of PSP plates; thus, PSP plates seem to be a safe alternative to stock plates and may even be preferable.

Synovial Cysts in the Temporomandibular Joint: a Case Report and Critical Review of the Literature.

BACKGROUND: Synovial cysts of the temporomandibular joint are rare and treatment is based on consensus from cases reporting unilateral successful outcomes. A patient with a synovial cyst is presented, treated with successful surgical excision of the cyst, but without remission of joint symptoms. Furthermore, the case is supplemented by a critical, literature review. METHODS: This case report deals with a patient with a synovial cyst that presented with temporomandibular joint (TMJ) pain and reduced mouth opening. Magnetic resonance imaging verified a TMJ cyst. RESULTS: Surgical excision removed the synovial cyst, and the patient was followed-up for 4 years, with no recurrence of the cyst. Despite successful excision of the cyst, the symptoms did not subside, and the patient is still in treatment. The critical, literature review found 23 case reports describing 24 synovial cysts. In addition, 4 cases were included as their synovial cysts were erroneously described as ganglion cysts. In 4 cases, histological diagnosis could not be confirmed, and they were excluded. All cases described treatment by surgical excision without recurrence. The reported median follow-up was 10 months and postoperative TMJ symptoms were rarely examined or described. CONCLUSIONS: The temporomandibular joint symptoms may persist despite successful removal of the synovial cyst. Furthermore, the 4 identified synovial cysts, mislabelled as ganglion cysts, represents almost a quarter of the cases of the reported synovial cysts. Correct labelling and reporting of synovial cysts are still imperative to describe the diverse aspects of treatment outcomes following surgical excision.