Virtual Analysis of Segmental Bimaxillary Surgery: A Validation Study.

PURPOSE: Three-dimensional (3D) assessment of orthognathic surgery is often time consuming, relies on manual re-identification of anatomical landmarks or is limited to non-segmental osteotomies. The purpose of the present study was to propose and validate an automated approach for 3D assessment of the accuracy and postoperative outcome of segmental bimaxillary surgery. METHODS: A semi-automatic approach was developed and validated for virtual surgical analysis (VSA) of segmental bimaxillary surgery using a pair of pre- and postoperative (2 weeks) cone-beam computerized tomography (CBCT) scans. The output of the VSA, the accuracy of the surgical outcome, was calculated as 3D translational and rotational differences between the planned and postoperative movements of the individual bone segments. To evaluate the reliability of the proposed VSA, intra-class correlation coefficients (ICC) were calculated at a 95% confidence interval on measurements of 2 observers. The VSA was deemed reliable if the ICC was excellent (> 0.80) and the absolute difference of the repeated intra- and inter-observer translational and rotational measurements were significantly lower (p < 0.05) than a hypothesized clinical relevant threshold of 1 voxel (0.45 mm) and 1 degree, respectively. RESULTS: A total of 10 subjects (6 male; 4 women; mean age 24.4 years) with skeletal class 2 and 3, who underwent segmental bimaxillary surgery, 3-piece Le Fort I, bilateral sagittal split osteotomy and genioplasty, were recruited. The intra- and inter-observer reliability was excellent, ICC range [0.96 - 1.00]. The range of the mean absolute difference of the repeated intra- and inter-observer translational and rotational measurements were [0.07 mm (0.05) - 0.20 mm (0.19)] and [0.11˚ (0.08) - 0.63˚ (0.42)], respectively. This was significantly lower than the hypothesized clinical relevant thresholds (P < .001). CONCLUSION: The validation showed that the VSA has excellent reliability for quantitative assessment of the postoperative outcome and accuracy of segmental bimaxillary surgery.

The effect of altered head and tongue posture on upper airway volume based on a validated upper airway analysis-An MRI pilot study.

OBJECTIVE: To determine the influence of altered head or tongue posture on upper airway (UA) volumes using MRI imaging based on a new objective and validated UA evaluation protocol. SETTING AND SAMPLE POPULATION: One supine CBCT and five sagittal MRI scans were obtained from ten subjects in different head and tongue positions: (a) supine neutral head position (NHP) with the tongue in a natural resting position with the tip of the tongue in contact with the lingual aspect of the lower incisors (TRP); (b) head extension with TRP; (c) head flexion with TRP; (d) NHP with the tip of the tongue in contact with the posterior edge of the hard palate (THP); and (e) NHP with the tip of the tongue in contact with the floor of the mouth in contact with the caruncula sublingualis. MATERIAL AND METHODS: Based on a validated CBCT UA analysis, the retropalatal, oropharyngeal and the corresponding total volumes were measured from each MRI scan. Wilcoxon signed-rank test was applied to determine the statistically significant difference in mean volume between the baseline head and tongue posture (NHP with TRP) and the other postures. RESULTS: Five females and five males with a mean age of 46.5 ± 13.7 years volunteered for this pilot study. UA volumes, particularly the oropharyngeal volume, increased significantly with head extension and NHP with THP and decreased significantly with head flexion. CONCLUSION: Altered head and tongue posture proved to affect UA volumes, thus representing confounding variables during three-dimensional radiographic image acquisition.

Orthognathic Surgery-Induced Fibrinolytic Shutdown Is Amplified by Tranexamic Acid.

PURPOSE: Little is known of the systemic effects of oral and maxillofacial surgery on the hemostatic balance, including the biochemical effects of tranexamic acid (TXA), on fibrin clot lysis. The present study investigated the effects of orthognathic surgery on fibrin lysis, fibrin structure, and D-dimer and evaluated the effect of TXA on these fibrinolytic measures. MATERIALS AND METHODS: The present double-blind, controlled, and randomized, placebo study included patients referred to the Department of Oral and Maxillofacial Surgery at the University Hospital of Southern Denmark-Esbjerg from August 2014 through September 2016. The patients were elective and had a diagnosis of maxillary or mandibular deficiency, either excessive or asymmetric. All patients underwent bimaxillary orthognathic surgery (OS) with or without maxillary segmentation or additional genioplasty. The patients were blindly randomized to treatment with TXA or placebo. The primary predictor variable was OS. The secondary predictor variable was an intravenous dose of 1 g of TXA or equivalent placebo preoperatively. Blood samples were collected before surgery and 5 hours after the initiation of surgery. The primary outcome variable was lysis of fibrin. The fibrin structure properties and D-dimer were secondary outcome measures. The Mann-Whitney U test was used for the within-group comparisons. The Wilcoxon signed rank test was used for the between-group comparisons. RESULTS: The sample included 96 patients; 45 received placebo and 51 received TXA. Fibrin lysis decreased after OS (P < .001). The fibrinolytic shutdown decreased significantly more in the TXA group than in the placebo group (P < .001). OS altered the fibrin structure properties with comparable effects in the 2 groups. D-dimer increased postoperatively but significantly less so in the TXA group than in the control group (P < .001). CONCLUSIONS: OS is associated with fibrinolytic shutdown and alters fibrin structure properties, driving the hemostatic balance in a prothrombotic direction. The fibrinolytic shutdown is significantly amplified by TXA.

Two-Year Postoperative Upper Airway Cone-Beam Computed Tomographic Outcomes Based on a Verified Upper Airway Analysis Following Bimaxillary Orthognathic Surgery.

PURPOSE: Upper airway (UA) assessment after orthognathic surgery should rely on a verified method of UA analysis. Therefore, the authors applied a new validated UA evaluation method to determine the effect of bimaxillary surgery (BMS) on UA parameters and hyoid bone and epiglottis displacement evaluated immediately and 2 years after surgery. MATERIALS AND METHODS: A retrospective cohort study was implemented of patients without obstructive sleep apnea who had undergone BMS for maxillomandibular deficiencies. A new validated UA cone-beam computed tomographic (CBCT) analysis, based on stable anatomic landmarks, was applied to CBCT scans acquired before initiation of treatment (T0), immediately after surgery (T1), and 2 years postoperatively (T2). A quality assessment was performed before analysis. The primary predictor variable consisted of time points during treatment (T0, T1 and T2), and UA volumes, cross-sectional area (CSA), and hyoid bone and epiglottis displacement were the outcome variables. Descriptive statistics and t test were performed and the P value was set at .05. RESULTS: Fifty patients (16 men and 34 women) with a mean age of 25.7 ± 8.2 years at time of surgery were included. CBCT scans were acquired at T0 (20 ± 9 months before surgery), T1 (14 ± 2 days after surgery), and T2 (30 ± 6 months after surgery). Immediately after surgery (T1 vs T0), BMS resulted in a statistically relevant UA volume increase of 26%. At 2-year follow-up (T2 vs T0), UA volume showed a statistically relevant increase by 20%. CSA increased by approximately 26 and 19% (P < .001) at T1 versus T0 and T2 versus T0, respectively. Two years after surgery, epiglottis displacement was 2 mm (P < .001) and hyoid bone displacement was 3 mm (P < .001) in a cranial direction and hyoid bone anterior displacement measured 3 mm (P < .001). CONCLUSIONS: Based on an objective, standardized, and validated CBCT UA analysis, BMS was associated with increased UA volume and CSA measures evaluated immediately and 2 years after surgery.

The Effect of Tranexamic Acid and Gender on Intraoperative Bleeding in Orthognathic Surgery-A Randomized Controlled Trial.

PURPOSE: The purpose of this randomized trial was to measure the effect of intravenously administered tranexamic acid (TXA) on intraoperative blood loss (IOB) in patients undergoing bimaxillary orthognathic surgery (OS). MATERIALS AND METHODS: The authors designed and implemented a double-blinded placebo-controlled trial composed of patients eligible for OS at the Hospital of South West Denmark (Esbjerg, Denmark) from August 2014 through September 2016. The primary predictor variable was a single intravenous dose of TXA 1 g administered preoperatively or an equivalent saline placebo. The primary outcome was IOB determined by milliliters of blood in the suction canister and gauzes deducted from the volume of saline used intraoperatively. RESULTS: The study population consisted of 96 patients. The TXA group (n = 51) and the placebo group (n = 45) showed a median IOB of 275 and 403 mL (P = .005), respectively. A significant effect of TXA was detected in women (median IOB, 153 mL [96 to 233 mL] in TXA group vs 329 mL [185 to 582 mL] in placebo group; P < .001), whereas no significant effect of TXA on IOB was detected in men (median IOB, 367 mL [275 to 472 mL] in TXA group vs 429 mL [275 to 655 mL] in placebo group; P = .23). No correlations were found between IOB and procedure length, procedure type, or hematologic markers (platelets, hemoglobin, and hematocrit). CONCLUSION: In contrast to other studies, this double-blinded randomized controlled trial found a hemostatic effect of TXA in women and none in men who underwent bimaxillary OS. To focus on the specific effect of TXA in men, future studies should include larger male samples.

Prevention of Bleeding in Orthognathic Surgery--A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

PURPOSE: The objective of the present study was to evaluate the efficacy of hemostatic adjuncts on intraoperative blood loss (IOB) in orthognathic surgery (OS) detected by randomized controlled trials (RCTs) of the highest quality. MATERIALS AND METHODS: A search of the Medline, Cochrane, Embase, and Web of Science databases was performed in January 2015, and the risk of bias was assessed using the Jadad and Delphi scales. The predictor variable was the hemostatic measures, and the main outcome variable was the total IOB volume. The secondary outcome variables were the hemoglobin and hematocrit and operating time. This review is registered at PROSPERO (CRD42014014840). RESULTS: Eleven trials were included for review. The individual trials demonstrated the effects on IOB from hypotensive anesthetic regimens, the use of aprotinin, and the herbal medicine Yunnan Baiyao. Six studies of tranexamic acid (TXA), with 288 patients, were suitable for a meta-analysis of continuous data. TXA reduced IOB by an average of 171 mL (95% confidence interval [CI] -230 to -112; P < .00001). Its topical use yielded similarly significant results (mean difference -197, 95% CI -319 to -76; P < .001). A subgroup analysis showed a decreased operating time in the TXA groups by an average of 15 minutes (mean difference -14.78, 95% CI -22.21 to -7.35; P < .0001). CONCLUSIONS: Efficient hemostatic adjuncts exist for OS. Our meta-analysis showed that TXA significantly reduces IOB by an average of one third, regardless of whether it was given intravenously (IV) or applied topically. Additional RCTs are needed to confirm the effect of topical TXA in OS, and larger studies of intravenous administration are needed before any routine recommendations. No hemostatic effect of hypotensive anesthesia was found, mainly owing to imprecise descriptions of the blinding procedures. Transparent and uniform trial reporting is thus encouraged in future studies.

Can Preoperative Sex-Related Differences in Hemostatic Parameters Predict Bleeding in Orthognathic Surgery?

PURPOSE: Bleeding volume in orthognathic surgery (OS) varies considerably, although OS comprises standardized procedures and the patient population consists of young healthy individuals. The aim of this prospective cohort study was to investigate the influence of preoperative sex-related differences in hemostatic parameters on intraoperative bleeding (IOB) volume in OS. MATERIALS AND METHODS: Patients scheduled for routine OS in our department in Esbjerg, Denmark, were included as study patients in this short-term cohort study. The primary predictor variable was patient sex, and the primary outcome variable was IOB volume measured in milliliters. Secondary outcome variables included preoperative measures of hematologic variables, thromboelastography, fibrinogen concentration, D-dimer concentration, prothrombin fragment 1+2 (F1+2) concentration, and type of osteotomy. Data analyses included the χ(2) test, Mann-Whitney U test, Pearson product moment correlation analysis, and analysis of covariance for analyses of dichotomous variables, comparison between sex, correlations between IOB volume and secondary predictors, and adjustment for confounders, respectively. RESULTS: Forty-one consecutive patients undergoing bimaxillary OS were included and subsequently grouped according to sex (26 men and 15 women). The main finding was that male patients bled twice as much as female patients on average (400 mL [interquartile range, 300 to 500 mL] vs 200 mL [interquartile range, 63 to 288 mL]; P = .001). Age and preoperative measures of thromboelastography, fibrinogen concentration, D-dimer concentration, and F1+2 concentration were significantly associated with sex (P = .001, P = .002, P = .007, and P = .014, respectively). The significant association between sex and IOB volume disappeared when adjusted for these confounders (P = .18). CONCLUSIONS: Preoperative sex-related increases in measures of fibrin turnover predict IOB volume in bimaxillary OS, with women displaying a significantly lower IOB volume than men.

Intraoperative blood loss during orthognathic surgery is predicted by thromboelastography.

PURPOSE: The aim of this prospective study was to evaluate the predictive value of the viscoelastic properties of whole blood samples collected preoperatively in relation to intraoperative blood loss in patients subjected to orthognathic surgery. MATERIALS AND METHODS: Forty-one consecutive patients underwent simultaneous mandibular and maxillary osteotomy. Whole blood samples were collected preoperatively. The intraoperative blood loss volume was precisely estimated. The viscoelastic properties of whole blood samples were evaluated by thromboelastography (TEG), a global method that addresses the complex interplay among coagulation factors, blood platelets, and components of the fibrinolytic system. Blood platelet count, activated partial thromboplastin time, prothrombin time, plasma fibrinogen concentration, and D-dimer concentration were determined by routine methods. RESULTS: Patients were separated into 2 groups according to their intraoperative bleeding volume (≤ 400 mL and >400 mL). No significant associations were observed between routine coagulation tests and intraoperative bleeding volume. The TEG results for the groups were compared. Significant associations were observed between intraoperative blood loss and the clot formation time, maximum clot firmness, and α angle, whereas bleeding volume was not related to the fibrinolytic resistance of the blood clot. An α angle exceeding 67° predicted with 95% certainty a blood loss of 400 mL or less. CONCLUSIONS: We conclude that intraoperative bleeding volume in patients subjected to orthognathic surgery can be predicted by means of preoperative TEG analysis. TEG results provide optimization of patient safety and can be used for the evaluation of bleeding risk.

Pharyngeal airway changes five years after bimaxillary surgery - A retrospective study.

The aim of this study was to retrospectively evaluate pharyngeal airway (PA) changes after bimaxillary surgery (BMS). Preoperative, immediate- and 5-year postoperative cone-beam computed tomography images of subjects who underwent BMS were assessed. The primary outcome variable was the PA volume. The secondary outcome variables were the retropalatal and oropharyngeal volumes, cross-sectional area, minimal hydraulic diameter, soft tissue, skeletal movements and sleep-disordered breathing (SDB). A total of 50 patients were included, 33 female and 17 male, with a mean age of 26.5 years. A significant increase in the PA volume was seen immediately after surgery (40%), and this increase was still present at 5-year follow-up (34%) (P < 0.001). A linear mixed model regression analysis revealed that a mandibular advancement of ≥5 mm (P = 0.025) and every 1-mm upward movement of epiglottis (P = 0.016) was associated with a volume increase of the oropharyngeal compartment. Moreover, ≥5-mm upward movement of hyoid bone (P = 0.034) and every 1-mm increase in minimal hydraulic diameter (P < 0.001) correlated with an increase of the PA volume. A total of 30 subjects reported improvement in the SDB at 5-year follow-up. This study demonstrated that BMS led to an increase in PA dimensions in non-OSA patients, and these changes were still present at 5-year follow-up. BMS seemed to induce clinical improvement in SDB.

[Treatment of patients with obstructive sleep apnoea syndrome].

Continuous positive airway pressure (CPAP) is an effective treatment modality for patients with obstructive sleep apnoea syndrome (OSAS). Surgical treatment of OSAS can include functional nasal surgery, uvulopalatopharyngoplasty, transoral robotic surgery, maxillo-mandibular advancement (MMA) and bariatric surgery. MMA should be considered in patients with moderate to severe OSAS, if CPAP treatment is ineffective or not tolerated, as well in patients with failure of previous sleep surgery or in patients with severe dentofacial anomalies. In this review, we stress, that multidisciplinary management between sleep medicine clinicians and surgeons is crucial.

Long-term radiographic assessment of titanium implants installed in maxillary areas grafted with autogenous bone blocks using two predefined sets of success criteria.

PURPOSE: Assess the radiographic peri-implant bone loss of implants installed in maxillary areas grafted with autogenous bone and classify the long-term (at least >4 ≤ 6 years) implant success according to two predefined sets of criteria. MATERIAL AND METHODS: Sixty patients had full maxillary alveolar reconstructions using autogenous bone grafts (iliac crest), and 369 titanium implants were installed. The follow-up protocol was 5 (>4 ≤ 6) years; thereafter only patients who presented significant peri-implant bone loss were followed up to 12 years. The radiographic peri-implant bone level was assessed on panoramic radiographs in relation to the baseline and used to classify the long-term success of the implants according to the predefined success criteria presented by Albrektsson and coworkers (ALB; 1986) and the Pisa Consensus Conference (PCC; 2007). RESULTS: Fifteen implants were lost over the 12-year follow-up period (two up to >4 ≤ 6 years). Mean radiographic peri-implant bone loss was 2.7 mm at the >4 ≤ 6 years control and 4.2 mm after >11 ≤ 12 years. Different success criteria resulted in different types of prevalence of implants classified as "failures." At >4 ≤ 6 years, 48% of the implants would be "failures" according to ALB, while according to the PCC, only 0.8% would be "failures" and 18.1% would be classified as "compromised survival" and 44.8% as "satisfactory survival." CONCLUSIONS: Mean peri-implant bone loss of implants installed in maxillary areas grafted with autogenous bone blocks was 2.7 mm after >4 ≤ 6 years, and two implants were lost during this period. The use of different success criteria significantly altered the prevalence of implants classified as "failure."

Long term follow-up of titanium implants installed in block-grafted areas: A systematic review.

BACKGROUND: An enduring clinical question concerns the outcome (ie, success) of implants placed in areas grafted with block-grafts. OBJECTIVE: To undertake a systematic review of the literature on the long term results (≥5 years) of implants placed in maxillofacial areas grafted with any type of osseous block-grafts in two-stage surgeries. Further, the review addresses how available success criteria were used within the studies. MATERIALS AND METHODS: The MEDLINE (PubMed) and EMBASE bibliographic databases were searched up to March 2017 for studies evaluating the long term results of implants placed in grafted areas. The search strategy was restricted to English language publications using combined terms which referred to the treatment method (implants placed in areas grafted with bone blocks), and follow-up characteristics (≥5 years and assessment of at least one parameter related to implant success criteria). To qualify for inclusion, studies should present outcome measurements indicating the success (or at least the survival) of the implants. RESULTS: The search strategy yielded 17 studies, which were included in this systematic review. These studies presented survival rates ranging from 88.7% (after 15 years follow-up) to 98.7% (after 5 years follow-up). Five studies presented data based on predefined success criteria with success rates ranging from 86.8% to 100%. In these studies, the term "success" was often not properly defined. CONCLUSION: The long term survival (≥5 years) of implants placed into block-grafted areas in two-stage surgeries was not lower than 75%, while success rates ranged from 86.8% to 100%. Although it was possible to identify published success criteria for implant follow-up, there is no broad consensus on how to report implant success in a consistent manner.

Effect of Head and Tongue Posture on the Pharyngeal Airway Dimensions and Morphology in Three-Dimensional Imaging: a Systematic Review.

OBJECTIVES: Natural head position is recommended to be optimal at cone-beam computed tomography acquisition. For standardization purposes in control of treatment outcome, it is clinically relevant to discuss, if a change of posture from natural head position may have an effect on the pharyngeal airway dimensions and morphology, during computed tomography, cone-beam computed tomography or magnetic resonance imaging acquisition. This was the aim of the present literature review study for purposes of valid evidence, which was hypothesized, to be present. MATERIAL AND METHODS: This systematic literature review has been registered in PROSPERO database with following number: CRD42015024567. A systematic literature search performed in PubMed, Embase and Cochrane was carried out in order to evaluate if the effect of human head or tongue posture has an effect on upper airway dimensions and morphology in CT, CBCT or MRI. Study quality assessment was performed. Predictor variable was head and tongue posture. Endpoints were numerical values of upper airway dimensions and morphology. RESULTS: Overall 1344 articles (Embase 1063, PubMed 269, and Cochrane 12) resulted in four included publications. Quality assessments revealed poor quality and low-level evidence by 46 - 67% of the maximum achievable score. Heterogeneous methodology made a meta-analysis impossible, consequently a narrative synthesis was performed. CONCLUSIONS: Limited, poor quality and low evidence level literature is available on the effect of head posture on upper airway dimensions and morphology in three-dimensional imaging. Valid evidence requires a standardized method of head and tongue posture during image acquisition in future studies.

Reconstruction of irradiated mandible after segmental resection of osteoradionecrosis-a technique employing a microvascular latissimus dorsi flap and subsequent particulate iliac bone grafting.

The fibula osteocutaneous flap has revolutionized the options of mandibular segmental defect bridging in osteoradionecrosis (ORN). In selected cases, however, the fibula flap is not an option because of atherosclerosis or other features that compromise the vascularity of the lower leg and foot. The aim of this study is to present an alternative method of mandibular segmental reconstruction employing a latissimus dorsi (LD) flap and subsequent particulate iliac free bone graft reconstruction. In 15 patients with ORN, a mandibular segmental defect was bridged with a reconstruction plate, and the defect site was primed with a LD musculocutaneous flap wrapped around the reconstruction plate to bring in vascularized tissue and optimize healing conditions for a subsequent particulate iliac free bone graft reconstruction. The management of defect closure was successful in all 15 patients. Twelve patients had a subsequent bone grafting from the posterior ileum for repair of defects up to 14 cm length. Three patients had no bone graft for various reasons. In three patients dental rehabilitation was achieved with implant supported prosthodontic appliances. Ten patients met the success criteria of uneventful graft healing with restitution of osseous continuity, mandibular height, symmetry and function, and avoidance of reconstruction plate fracture.

Refractive change during hyperbaric oxygen therapy. A clinical trial including ultrasound oculometry.

PURPOSE: To record changes in refraction and refractive parameters associated with a standard hyperbaric oxygen treatment protocol consisting of a 95 min session at > 95% oxygen at 2.5 atmospheres (ATA) given daily Monday to Friday, to a total of 30 sessions. PATIENTS AND METHODS: Seventeen of the 26 patients included were able to attend for ophthalmic assessment at time zero (to) and after 20 treatments (t20). Thirteen patients also had a post-treatment follow-up. Most patients were being treated for osteoradionecrosis after radiotherapy of ENT cancers, and drop-outs for the eye exam were common. Refraction was determined subjectively and by refractometry, before and after tropicamide 1% eyedrops. Refractive parameters were assessed by keratometry and by A-scan axial ultrasound measurement. RESULTS: Results are given for the 17 patients with to and t20 assessments. The induced refractive change ranged from 0 to 1.5 D. When observed, refractive changes were myopic in nature. The shift averaged 0.58 D according to the refractometer and 0.49 D as subjectively assessed, with corresponding median change values being 0.62 and 0.39 D. The differences between 0 D and these values, although small, were statistically highly significant. CONCLUSIONS: The refractive changes associated with hyperbaric oxygen therapy were smaller than the literature had led us to expect. No significant change in axial eye length measurements was found, and keratometry readings reflected only minimal change, although this was statistically significant on a 0.05 level. Therefore it is most likely that lens changes, whether in internal refractive indices or curvatures, accounted for the transitory shift towards more myopic/less hyperopic values.