Validation of a fully automatic three-dimensional assessment of orthognathic surgery.

The aim of the present study was to propose and validate FAST3D: a fully automatic three-dimensional (3D) assessment of the surgical accuracy and the long-term skeletal stability of orthognathic surgery. To validate FAST3D, the agreement between FAST3D and a validated state-of-the-art semi-automatic method was calculated by intra-class correlation coefficients (ICC) at a 95 % confidence interval. A one-sided hypothesis test was performed to evaluate whether the absolute discrepancy between the measurements produced by the two methods was statistically significantly below a clinically relevant error margin of 0.5 mm. Ten subjects (six male, four female; mean age 24.4 years), class II and III, who underwent a combined three-piece Le Fort I osteotomy, bilateral sagittal split osteotomy and genioplasty, were included in the validation study. The agreement between the two methods was excellent for all measurements, ICC range (0.85-1.00), and fair for the rotational stability of the chin, ICC = 0.54. The absolute discrepancy for all measurements was statistically significantly lower than the clinical relevant error margin (p < 0.008). Within the limitations of the present validation study, FAST3D demonstrated to be reliable and may be adopted whenever appropriate in order to reduce the work load of the medical staff.

Health-related quality of life, jaw function and sleep-disordered breathing among patients with dentofacial deformity.

BACKGROUND AND OBJECTIVES: Patients with dentofacial deformity (DFD) requiring orthognathic treatment have poor aesthetics, jaw function and psychological well-being, which potentially affect the quality of life. This study aimed to investigate the health-related general, oral and orthognathic quality of life, jaw function and sleep-disordered breathing at different stages of orthognathic surgical treatment. METHODS: A total of 120 consecutive patients with DFD were recruited and grouped as pre-orthodontic treatment (group 1), pre-surgery (group 2), 4 months post-surgery (group 3), 24 months post-surgery (group 4) and in addition 30 controls without DFD (group 0). Outcomes were assessed using general health Short Form Survey (SF-36), Oral Health Impact (OHIP-14), Orthognathic Quality of Life Questionnaire (OQLQ), STOP-Bang and Jaw Function Limitation Scale (JFLS) questionnaires. In addition, presence or absence of pain was recorded. Data were tested with analysis of variance, Kruskal-Wallis test, Tukey post hoc test and structural equation modelling (SEM). RESULTS: Results revealed SF-36 (p = .814) and STOP-Bang (p = .143) total scores did not differ between control and treatment groups. In contrast, OHIP-14, OQLQ and JFLS total scores differed between groups (p = .001). Higher scores were observed in groups 1 (p = .001), 2 (p = .001) and 3 (p = .041) compared to group 0, indicating poor oral health in patients with DFD. Importantly, in group 4, oral health-related quality of life was better, and OHIP-14 (p = .936) and JFLS (p = .572) scores did not differ from controls. OQLQ scores of group 4 were significantly lower than group 1 (p = .001) but higher than group 0 (p = .013). SEM results revealed a significant negative associations of pain with JFLS and OQLQ; OHIP-14 with OQLQ; OHIP-14 with SF-36; and finally STOP-Bang with SF-36. Positive associations were observed between JFLS and OHIP-14; OHIP-14 and OQLQ. CONCLUSION: Oral health-related quality of life and jaw function appears to be improved 24 months after orthognathic surgery. Pain and limitation in jaw function had a negative association with health-related quality of life.

Associations between temporomandibular disorders, pain, jaw and masticatory function in dentofacial deformity patients: A cross-sectional study.

BACKGROUND AND OBJECTIVE: Patients with dentofacial deformity often present with impaired masticatory function, orofacial pain and temporomandibular disorders (TMD). This study investigates the relationship between TMD, pain, jaw and masticatory function at different stages of orthognathic surgical (OS) treatment. METHODS: A total of 120 OS patients were prospectively recruited and grouped as pre-orthodontic (group 1), pre-surgery (group 2), 4-month post-surgery (group 3), 24-month post-surgery (group 4), in addition to 30 controls (group 0). Outcomes were assessed using: Jaw Function Limitation Scale (JFLS), McGill pain questionnaire, DC/TMD instrument, voluntary maximum bite force (MVBF), and masticatory efficiency (ME) using two-coloured chewing gum. Data were analysed using structural equation modelling. RESULTS: The prevalence of non-painful TMD did not differ between groups (p = .827). However, the prevalence of painful TMD differed between groups (p = .001). Among the painful TMDs, the highest prevalence was observed for masseter myalgia in group 2 (p = .031), and importantly group 4 did not differ from group 0 (p = .948). The MPQ score was significantly higher in group 1 (p = .001) compared to group 0, and the JFLS score was significantly higher in groups 1, 2 and 3 compared to group 0. Notably, MPQ (p = .756) and JFLS (p = .572) scores in group 4 were not different from group 0. However, MVBF (p = .996) and ME (p = .991) did not differ between groups 1 and 4. The association of self-reported pain and jaw function with the masticatory function was observed in OS patients. CONCLUSION: OS was not associated with a negative impact on TMD. Jaw function and pain levels were similar to controls at the 24-month follow-up. The masticatory function was further affected by the surgery and seems to require a longer recovery time. Moreover, it was confirmed that pain and TMD were associated with limitations in jaw function and impacts on masticatory function.

A Semi-Automatic Approach for Holistic 3D Assessment of Temporomandibular Joint Changes.

The literature lacks a reliable holistic approach for the three-dimensional (3D) assessment of the temporomandibular joint (TMJ) including all three adaptive processes, which are believed to contribute to the position of the mandible: (1) adaptive condylar changes, (2) glenoid fossa changes, and (3) condylar positional changes within the fossa. Hence, the purpose of the present study was to propose and assess the reliability of a semi-automatic approach for a 3D assessment of the TMJ from cone-beam computed tomography (CBCT) following orthognathic surgery. The TMJs were 3D reconstructed from a pair of superimposed pre- and postoperative (two years) CBCT scans, and spatially divided into sub-regions. The changes in the TMJ were calculated and quantified by morphovolumetrical measurements. To evaluate the reliability, intra-class correlation coefficients (ICC) were calculated at a 95% confidence interval on the measurements of two observers. The approach was deemed reliable if the ICC was good (>0.60). Pre- and postoperative CBCT scans of ten subjects (nine female; one male; mean age 25.6 years) with class II malocclusion and maxillomandibular retrognathia, who underwent bimaxillary surgery, were assessed. The inter-observer reliability of the measurements on the sample of the twenty TMJs was good to excellent, ICC range (0.71-1.00). The range of the mean absolute difference of the repeated inter-observer condylar volumetric and distance measurements, glenoid fossa surface distance measurements, and change in minimum joint space distance measurements were (1.68% (1.58)-5.01% (3.85)), (0.09 mm (0.12)-0.25 mm (0.46)), (0.05 mm (0.05)-0.08 mm (0.06)) and (0.12 mm (0.09)-0.19 mm (0.18)), respectively. The proposed semi-automatic approach demonstrated good to excellent reliability for the holistic 3D assessment of the TMJ including all three adaptive processes.

Three-Dimensional Accuracy and Stability of Personalized Implants in Orthognathic Surgery: A Systematic Review and a Meta-Analysis.

This systematic review aimed to determine the accuracy/stability of patient-specific osteosynthesis (PSI) in orthognathic surgery according to three-dimensional (3D) outcome analysis and in comparison to conventional osteosynthesis and computer-aided designed and manufactured (CAD/CAM) splints or wafers. The PRISMA guidelines were followed and six academic databases and Google Scholar were searched. Records reporting 3D accuracy/stability measurements of bony segments fixated with PSI were included. Of 485 initial records, 21 met the eligibility (566 subjects), nine of which also qualified for a meta-analysis (164 subjects). Six studies had a high risk of bias (29%), and the rest were of low or moderate risk. Procedures comprised either single-piece or segmental Le Fort I and/or mandibular osteotomy and/or genioplasty. A stratified meta-analysis including 115 subjects with single-piece Le Fort I PSI showed that the largest absolute mean deviations were 0.5 mm antero-posteriorly and 0.65° in pitch. PSIs were up to 0.85 mm and 2.35° more accurate than conventional osteosynthesis with CAD/CAM splint or wafer (p < 0.0001). However, the clinical relevance of the improved accuracy has not been shown. The literature on PSI for multi-piece Le Fort I, mandibular osteotomies and genioplasty procedure is characterized by high methodological heterogeneity and a lack of randomized controlled trials. The literature is lacking on the 3D stability of bony segments fixated with PSI.

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.

Comparison of surface- and voxel-based registration on the mandibular ramus for long-term three-dimensional assessment of condylar remodelling following orthognathic surgery.

OBJECTIVES: The purpose of the present study was to validate and compare the accuracy and reliability of surface- and voxel-based registration on the mandibular rami for long-term three-dimensional (3D) evaluation of condylar remodelling following Orthognathic Surgery. METHODS: The mandible was 3D reconstructed from a pair of superimposed pre- and postoperative (two years) cone-beam computerized tomography scans and divided into the condyle, and 21 ramal regions. The accuracy of surface- and voxel-based registration was measured by the absolute mean surface distance of each region after alignment of the pre- and postoperative rami. To evaluate the reliability, mean absolute differences and intraclass correlation coefficients (ICC) were calculated at a 95% confidence interval on volumetric and surface distance measurements of two observers. Paired t-tests were applied to statistically evaluate whether the accuracy and reliability of surface- and voxel-based registration were significantly different (p < 0.05). RESULTS: A total of twenty subjects (sixteen female; four male; mean age 27.6 years) with class II malocclusion and maxillomandibular retrognathia, who underwent bimaxillary surgery, were included. Surface-based registration was more accurate and reliable than voxel-based registration on the mandibular ramus two years post-surgery (p < 0.05). The interobserver reliability of using surface-based registration was excellent, ICC range [0.82-1.00]. For voxel-based registration, the interobserver reliability ranged from poor to excellent [0.00-0.98]. The measurement error introduced by applying surface-based registration for assessment of condylar remodelling was considered clinical irrelevant (1.83% and 0.18 mm), while the measurement error introduced by voxel-based registration was considered clinical relevant (5.44% and 0.52 mm). CONCLUSIONS: Surface-based registration was proven more accurate and reliable compared to voxel-based registration on the mandibular ramus for long-term 3D assessment of condylar remodelling following Orthognathic Surgery. However, importantly, the performance difference may be caused by an inappropriate reference structure, proposed in the literature, and applied in this study.

Does the Glenoid Fossa Change Following Orthognathic Surgery?

PURPOSE: Glenoid fossa morphology may change following orthognathic surgery and may subsequently affect skeletal stability and functionality, however hardly documented. Hence, the purpose of this study was to evaluate the morphological change of the glenoid fossa 2 years after bimaxillary surgery. METHODS: A case series was performed including subjects diagnosed with maxillary and/or mandibular growth disturbances, who underwent bimaxillary surgery between March 2012 and November 2017 at the Department of Oral and Maxillofacial Surgery, University Hospital of Southern Denmark, Esbjerg, Denmark. The study variables were gender, age, and postoperative condylar resorption. Subjects were sampled evenly within subgroups with and without postoperative condylar resorption. The outcome variable, three-dimensional morphological change of the glenoid fossa, was calculated as surface distance in mm between superimposed preoperative and postoperative (2 years) cone-beam computed tomography scans, and the glenoid fossa was spatially divided into 4 regions. Evaluation of glenoid fossa changes of more than one voxel (>0.3 mm) and comparison of subjects with and without postoperative condylar resorption were performed by one-sample and unpaired t tests, respectively. RESULTS: Twenty subjects (16 women; 4 men; mean age = 27.6 years) with Class II malocclusion and maxillomandibular retrognathia were included. The glenoid fossa changes (0.36 mm) were significant (P = .021) and significantly larger in subjects with condylar resorption than in those without condylar resorption in the anterior-lateral (0.40 mm vs 0.27 mm, P = .021) and anterior-medial fossa region (0.48 mm vs 0.26 mm, P = .015). CONCLUSIONS: Significant morphological fossa changes were found 2 years after orthognathic surgery, and subjects with postoperative condylar resorption showed a significantly higher degree of morphological change in the anterior glenoid fossa than subjects without postoperative condylar resorption.

A semi-automatic approach for longitudinal 3D upper airway analysis using voxel-based registration.

OBJECTIVES: To propose and validate a reliable semi-automatic approach for three-dimensional (3D) analysis of the upper airway (UA) based on voxel-based registration (VBR). METHODS: Post-operative cone beam computed tomography (CBCT) scans of 10 orthognathic surgery patients were superimposed to the pre-operative CBCT scans by VBR using the anterior cranial base as reference. Anatomic landmarks were used to automatically cut the UA and calculate volumes and cross-sectional areas (CSA). The 3D analysis was performed by two observers twice, at an interval of two weeks. Intraclass correlations and Bland-Altman plots were used to quantify the measurement error and reliability of the method. The relative Dahlberg error was calculated and compared with a similar method based on landmark re-identification and manual measurements. RESULTS: Intraclass correlation coefficient (ICC) showed excellent intra- and inter-observer reliability (ICC ≥ 0.995). Bland-Altman plots showed good observer agreement, low bias and no systematic errors. The relative Dahlberg error ranged between 0.51 and 4.30% for volume and 0.24 and 2.90% for CSA. This was lower when compared with a similar, manual method. Voxel-based registration introduced 0.05-1.44% method error. CONCLUSIONS: The proposed method was shown to have excellent reliability and high observer agreement. The method is feasible for longitudinal clinical trials on large cohorts due to being semi-automatic.

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.

A Novel Quality Register Study and Review of Implant Treatment of Patients with Dental Agenesis.

PURPOSE: (1) To present a Danish quality register (AMETO) concerning dental implant treatment for dental agenesis, assess its indicators and standards, and compare them with those acknowledged and outlined by the Institute of Medicine (IoM), World Health Organization (WHO), and Organization for Economic Cooperation and Development (OECD), classified as the quality domains efficiency, effectiveness, patient-centered care, timely care, safety, and equitability; and (2) to perform a systematic literature search and review to verify whether any quality register exists according to the six quality domains. MATERIALS AND METHODS: (1) The AMETO register is comprised of 16 process and result indicators and standards, which were compared to the six quality domains outlined by the IoM and WHO. (2) A systematic literature search was carried out using the search engines PubMed, Embase, CINAHL, Web of Science, and SveMed+. The included articles were assessed for quality indicators and standards to determine whether they conformed to the six quality domains. RESULTS: AMETO indicators and standards conformed to the quality domains outlined by the IoM. A search of "(dental agenesis) AND (dental implants)" yielded a total of 381 publications, of which 27 were included for qualitative synthesis. A search on quality indicators and dental agenesis registries yielded no results. Due to considerable heterogeneity in the reported quality indicators related to effectiveness, patient-centered care, and safety, a meta-analysis could not be conducted. CONCLUSION: AMETO conforms to the quality domains described by the IoM, WHO, and OECD. Few studies have investigated dental implant treatment of dental agenesis. Moreover, no published quality register for dental implant treatment currently exists.

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.

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.

Accuracy and reproducibility of the DAVID SLS-2 scanner in three-dimensional facial imaging.

PURPOSE: A prospective study was performed to test the accuracy and reproducibility of the DAVID-SLS-2 scanner (SLS-2) [DAVID Vision Systems GmbH], compared to the validated 3dMDtrio scanner (3dMD) [3dMD, LLC, Atlanta, GA, USA]. MATERIALS AND METHODS: The accuracy of the SLS-2 was determined through multiple scans of a mannequin face model using both scanners. The reproducibility of a protocol for achieving consistent three-dimensional (3D) face scans in live subjects was carried out using the SLS-2. A precision of ≤1 mm was considered clinically significant. RESULTS: The mannequin face model was reproduced with no significant errors in the SLS-2 compared to the 3dMDtrio, with normally distributed data (mean = 0.002 mm; SD = 0.01 mm). In live subjects, the forehead, midface, chin and general face region showed mean errors and SD <0.24 mm and <1 mm, respectively. In the neck area, the data were not found to be normally distributed (mean = -1.6 mm; SD = 2.1 mm). CONCLUSION: Structured light scanning may be used for acquiring 3D face scans in live subjects in a radiation-free and reproducible manner, provided that the head of the subject is positioned in the same posture for each scan. Special care is recommended in positioning the head in the sagittal plane during scanning.

A new simple three-dimensional method to characterize upper airway in orthognathic surgery patient.

OBJECTIVES: To develop and validate a new reproducible 3D upper airway analysis based on skeletal structures not involved in the modification, which occur during orthognathic surgery. METHODS: From retrospective cohort of orthognathic surgically treated patients, pre- and postsurgical CBCT-scans of 10 post-pubertal patients were randomly selected. Two operators identified the landmarks, calculated the airway volumes, cross sections and linear measurements on the 10 scans twice at two different time intervals. Statistical analysis included test for normal distribution, technical error measurements, and intra- and inter-observers reliability. RESULTS: Intra- and inter-observer reliability was excellent for volumes and cross sections. The entire data sets exhibited normal distribution. Technical error of measurements showed an error in the range of 1.6 to 10.2% for volume, 1.6 to 12.2% for cross-sectional measurements, and 0.3 to 2.5% for linear measurements. No systematic errors were detected. CONCLUSIONS: This new proposed definition of upper airway boundaries was shown to be technical feasible and tested to be reliable in measuring upper airway in patients undergoing orthognathic surgery.

Synchrotron radiation µCT and histology evaluation of bone-to-implant contact.

The purpose of this study was to evaluate bone-to-implant contact (BIC) in two-dimensional (2D) histology compared to high-resolution three-dimensional (3D) synchrotron radiation micro computed tomography (SR micro-CT). High spatial resolution, excellent signal-to-noise ratio, and contrast establish SR micro-CT as the leading imaging modality for hard X-ray microtomography. Using SR micro-CT at voxel size 5 µm in an experimental goat mandible model, no statistically significant difference was found between the different treatment modalities nor between recipient and reconstructed bone. The histological evaluation showed a statistically significant difference between BIC in reconstructed and recipient bone (p < 0.0001). Further, no statistically significant difference was found between the different treatment modalities which we found was due to large variation and subsequently due to low power. Comparing histology and SR micro-CT evaluation a bias of 5.2% was found in reconstructed area, and 15.3% in recipient bone. We conclude that for evaluation of BIC with histology and SR micro-CT, SR micro-CT cannot be proven more precise than histology for evaluation of BIC, however, with this SR micro-CT method, one histologic bone section is comparable to the 3D evaluation. Further, the two methods complement each other with knowledge on BIC in 2D and 3D.

Intermaxillary Fixation Screw Morbidity in Treatment of Mandibular Fractures-A Retrospective Study.

PURPOSE: The aim of the present retrospective study was to investigate the morbidity of screws used for intermaxillary fixation (IMF) in the treatment of mandibular fractures. A review of the published data was also performed for a comparison of outcomes. Our hypothesis was that the use of screws for IMF of mandibular fractures would result in minimal morbidity. MATERIALS AND METHODS: Patients treated for mandibular fractures from 2007 to 2013, using screws for IMF, using the international diagnosis code for mandibular fracture, DS026, were anonymously selected (Department of Oral and Maxillofacial Surgery, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark). The fracture type, radiographic findings, treatment modality, screw type and number, and root damage were recorded. For the outcome comparison, a review of the published data regarding iatrogenic dental root damage caused by screw fixation was performed in May 2015. RESULTS: A total of 156 patients had undergone IMF with screws. The total number of screws was 793. The incidence of root lesions was 0.25% centrally and 0.88% peripherally. The incidence of screw loss was 0.13% and that of screw loosening was 1.89%. In the review, 737 related reports were identified in a search of PubMed and the Cochrane Library. Of these, 25 were considered suitable for inclusion. A lack of valid evidence resulted in a descriptive analysis, because a meta-analysis of the data was not possible. CONCLUSIONS: The results of the present retrospective study have shown that the use of screws is a valid choice for IMF in mandibular fracture treatment with minimal morbidity. The 793 screws used for IMF resulted in a negligible amount of central and peripheral tooth root trauma.

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.

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.