Academic Achievement in School-Aged Children with Single Suture Craniosynostosis Over Time.

Introduction: Children with single suture craniosynostosis (SSC) are at risk for neurocognitive problems. The reported magnitude of differences between children with SSC and their normative peers on standardized tests of academic and intellectual ability are small. Evaluation of real-world academic outcomes of these children and its impact on educational resources have not been conducted. Methods: A retrospective cohort study of academic outcomes of children with SSC was conducted using the data from Ontario's Education Quality and Accountability Office (EQAO) standardized provincial reading, writing and mathematics tests. The need for special education was identified by documentation of the child's need for an Identification, Placement, and Review Committee (IPRC). Results: Of 296 eligible children, 42 participated in the study. Half of the children had sagittal synostosis, while the remaining were 10 (24%) unicoronal, 9 (21%) metopic, and 2 (5%) lambdoid synostosis. Thirty-six (86%) underwent operative management. The EQAO scores of operated children with SSC met the provincial academic standards on the Grade 3 and 6 EQAO scores across the 3 academic subjects. Converted grade-matched EQAO scores decreased in reading and writing over time, while math improved. Of the 21 patients with special education data, one child required an IPRC in Grade 3, while an additional four (24%) required an IPRC in Grade 6. Conclusions: Operated children with SSC had average academic performance, however, their needs appeared to change over time. Future studies are needed to evaluate academic difficulties and special education needs as these children progress through grade school.

Introduction: Les enfants ayant une craniosynostose simple (CSS) sont à risque de troubles neurocognitifs. Selon les tests standardisés des capacités scolaires et intellectuelles, les enfants ayant une CSS présentent des différences légères par rapport à leurs homologues en bonne santé. Les résultats scolaires concrets de ces enfants n'ont pas été évalués, ni leurs répercussions sur les ressources pédagogiques. Méthodologie: Les chercheurs ont effectué une étude de cohorte rétrospective des résultats des enfants ayant une CSS aux examens de lecture, d'écriture et de mathématique au moyen des données provinciales standardisées de l'Office de la qualité et de la responsabilité en éducation de l'Ontario (OQRÉO). Les besoins en éducation spécialisée étaient indiqués par un avis du comité d'identification, de placement et de révision (CIPR) au dossier de l'enfant. Résultats: Des 296 enfants admissibles, 42 ont participé à l'étude. La moitié des enfants présentaient une synostose sagittale (scaphocéphalie), tandis que dix (24 %) avaient une synostose unicoronale, neuf (21 %), une synostose métopique (trigonocéphalie), et deux (5 %), une synostose lambdoïde. Au total, 36 (86 %) ont été opérés. Les scores de l'OQRÉO des enfants opérés à cause d'une CSS respectaient les normes scolaires provinciales pour la 3e et la 6e années dans les trois matières scolaires. Les scores de l'OQRÉO convertis en fonction du degré ont diminué en lecture et en écriture au fil du temps, mais se sont améliorés en mathématiques. Des 21 patients sur qui les chercheurs possédaient des données en éducation spécialisée, un enfant a eu besoin d'un avis du CIPR en 3e année, et quatre (24 %), en 6e année. Conclusions: Les enfants opérés à cause d'une CSS avaient une performance scolaire moyenne, mais leurs besoins semblaient évoluer au fil du temps. D'autres études devront être réalisées pour évaluer les problèmes scolaires et les besoins d'éducation spécialisée des enfants au primaire.

Catastrophic and Critical Intraoperative Events during Pediatric Craniofacial Surgery.

Pediatric craniofacial surgery performed in tertiary care centers by dedicated teams is associated with high levels of safety and low rates of mortality. However, catastrophic and life-threatening events may occur as a result of surgical management of these complex patients. This study reviewed the incidence and acute outcomes of catastrophic and critical events during craniofacial surgery at a single high-volume center. Methods: The data reviewed included the operative procedures of two senior craniofacial surgeons over an 18-year period at a tertiary care pediatric craniofacial center. Catastrophic or critical intraoperative events were defined as events requiring the activation of an emergency code during surgery. The operative details and acute outcomes were reviewed and analyzed. Results: This study reviewed 7214 procedures performed between January 2002 and January 2019. There were 2072 (29%) cases classified as major craniofacial procedures (transcranial, mixed trans-and-extracranial, or major extracranial facial osteotomies), and code events occurred in 14 cases (0.67%; one in 148 patients): venous air embolism (n = 4), cardiac complications (n = 3), major hemorrhage (n = 3), trigeminocardiac reflex (n = 2), acute intracranial hypertension (n = 1), and acute airway obstruction (n = 1). Two cases (14%) experienced a critical event that was anesthesia-related. Cardiac arrest requiring compressions and/or defibrillation was necessary for eight patients. There were no mortalities. Surgery was curtailed in seven cases and successfully completed in seven patients. Conclusions: Catastrophic life-threatening events during pediatric craniofacial surgery are, fortunately, rare. In our institution, experienced teams in the management of catastrophic and critical intraoperative events during major pediatric craniofacial procedures resulted in no mortalities.

Further delineation of auriculocondylar syndrome based on 14 novel cases and reassessment of 25 published cases.

Auriculocondylar syndrome (ACS) is a rare craniofacial disorder characterized by mandibular hypoplasia and an auricular defect at the junction between the lobe and helix, known as a "Question Mark Ear" (QME). Several additional features, originating from the first and second branchial arches and other tissues, have also been reported. ACS is genetically heterogeneous with autosomal dominant and recessive modes of inheritance. The mutations identified to date are presumed to dysregulate the endothelin 1 signaling pathway. Here we describe 14 novel cases and reassess 25 published cases of ACS through a questionnaire for systematic data collection. All patients harbor mutation(s) in PLCB4, GNAI3, or EDN1. This series of patients contributes to the characterization of additional features occasionally associated with ACS such as respiratory, costal, neurodevelopmental, and genital anomalies, and provides management and monitoring recommendations.

Endoscopic Versus Open Total Vault Reconstruction of Sagittal Craniosynostosis.

Sagittal craniosynostosis is the most common form of congenital cranial deformity. Surgical interventions are performed either open or endoscopic. Advancements in minimally invasive surgery have enabled the development of the endoscopic suturectomy technique. This is contrasted to the traditional open cranial vault reconstruction. There is a paucity of data comparing the head shape changes from both techniques. This study aims to compare the morphological outcome of endoscopic suturectomy versus total cranial vault reconstruction. METHODS: This is a retrospective comparative study involving 55 cases of sagittal craniosynostosis, 37 of which has open total cranial vault reconstruction and 18 had endoscopic suturectomy procedure. Preoperative and postoperative 3D photographs of both groups were analyzed and compared. The change in correction between preoperative and postoperative state was measured against a crowd-driven standard for acceptable head shape. RESULTS: Total cranial vault had higher percentage change between pre and postoperative cranial index than endoscopic suturectomy (14.7% versus 7.7%, P = 0.003). However, both techniques were able to achieve the minimum standard of 70% correction (TCV 107.5%, ES 100.4%, P = 0.02). CONCLUSION: Total cranial vault and endoscopic suturectomy are effective in correcting scaphocephaly among children with sagittal craniosynostosis. Additionally, both techniques are able to achieve a percentage correction that exceeds the 70% benchmark established by the lay public.

Cranioorbital Morphology Caused by Coronal Ring Suture Synostosis.

BACKGROUND: Minor cranial sutural synostosis is currently regarded as a rare diagnosis. As clinical awareness grows, a greater number of cases are being documented. This study aims to describe the variants of unicoronal synostosis with regard to major and minor sutural involvement and secondary effects on cranial and orbital morphology. The information is aimed to improve clinical diagnosis and management. METHODS: A retrospective study was conducted collecting preoperative computed tomographic scans of patients diagnosed with unicoronal synostosis and listed for surgical interventions, identified from a craniofacial database. Within these patients, different synostotic variants were identified based on which suture was affected. Scans of normal pediatric skulls (trauma) were used for a control group. Computed tomographic scans were analyzed for sutural involvement, cranial base deflection, and ipsilateral and contralateral orbital height and width. One-way analysis of variance was used to detect differences between synostotic variants and controls. RESULTS: A total of 57 preoperative computed tomographic scans of patients with unicoronal synostosis were reviewed, in addition to 18 computed tomographic scans of normal skulls (control group). Four variants of unicoronal synostosis were identified: frontoparietal, frontosphenoidal, frontoparietal and frontosphenoidal, and frontosphenoidal and frontoparietal. The last two variants differ in their temporal involvement in the direction of sutural synostosis and ultimately cranial and orbital morphology. Three variants have been previously identified, but the fourth is presented for the first time. CONCLUSIONS: An understanding of the variants of unicoronal synostosis and their temporal relationships is integral for accurate clinical diagnosis and surgical correction. Recommendations for treatment are based on discrete changes in orbital morphology.

Evaluation of Long-term Outcomes of Facial Sensation following Cranial Vault Reconstruction for Craniosynostosis.

BACKGROUND: Cranial vault reshaping to correct craniosynostosis in infants may injure terminal branches of the trigeminal nerve, namely the supraorbital, supratrochlear, zygomaticofacial, and zygomaticotemporal nerves, especially if a fronto-orbital advancement is performed. Despite numerous studies demonstrating successful esthetic outcome after FOA, there are no long-term studies assessing facial sensation after possible damage to these nerves as the result of surgery. METHODS: A cross-sectional case-control research design was used to evaluate facial sensory threshold in the trigeminal branches after cranial vault reconstruction in children with isolated, nonsyndromic metopic, and unicoronal craniosynostosis, compared with those with sagittal craniosynostosis and age-matched nonaffected controls. Study participants were recruited from the Hospital for Sick Children between the ages of 6 and 18 years. Sensory outcome was determined using the Weinstein Enhanced Sensory Test, the Ten Test, and self-reported facial sensibility function questionnaire. RESULTS: The sensory outcomes of 28 patients and 16 controls were examined at an average age of 9.6 years and 10.3 years, respectively. No subjective or objective sensory deficit was noted in supraorbital, supratrochlear, zygomaticofacial, or zygomaticotemporal nerve distributions between groups. Qualitative reports of facial sensibility function indicated no difference in subjective sensation, protective sensation, or motor behavior between groups. CONCLUSIONS: These results suggest that while sensory nerve injury during routine FOA may occur, it does not result in a quantifiable nor clinically significant long-term sensory deficit threshold. Patients do not develop long-term neuropathic pain following surgical intervention.

Le Fort III in Syndromic Craniosynostosis: Cost Comparison of Distraction Osteogenesis Versus Single-Stage Internal Fixation Techniques.

PURPOSE: In syndromic craniosynostosis, the Le Fort III osteotomy is used to correct dental/skeletal imbalance, improve exorbitism, and increase the airway. The purpose of this study is to perform a cost comparison between the standard technique of single-stage rigid internal fixation and distraction osteogenesis (DO) in the Le Fort III osteotomy in this patient population. METHOD: Hospital cost accounting databases were queried for patients undergoing single-stage advancement (SS) or DO from 2007 to 2016. Nominal cost data were adjusted using the Bank of Canada Consumer Price Index. Reported costs represented the full length of stay for all utilization per patient. Demographic information and cost data for single-stage osteotomy and DO were compared. RESULTS: Total costs for single-stage (n = 8) were higher than distraction (n = 6; mean $CAD57 825 vs $38 268, P < .05). Intensive care unit (ICU) costs for single-stage were significantly higher than distraction (mean, $17 746 vs $5585, P < .005). Distraction cases had higher operating room (OR) costs than single stage, but the difference was not significant (mean, $12 540 vs $9696). Length of stay was significantly longer for SS patients (mean, 11 days vs 7 days, P < .05). CONCLUSIONS: This single-institution retrospective cost analysis indicates standard SS rigid internal fixation Le Fort III is more costly than DO. Despite higher OR costs, prolonged ICU and hospital stay was the primary reason behind this difference. This information may be of benefit when advocating for new technology perceived as high cost.

OBJECTIFS: En cas de craniosynostose syndromique, l'ostéotomie de Le Fort III permet de corriger un déséquilibre dentaire et squelettique, d'améliorer l'exophtalmie et de mieux ouvrir les voies respiratoires. La présente étude vise à comparer les coûts de la technique standard de fixation interne rigide en une étape à la distraction osseuse (DO) au sein de la population de patients en cas d'ostéotomie de Le Fort III. MÉTHODOLOGIE: Les chercheurs ont fouillé les bases de données comptables des coûts hospitaliers pour les patients qui avaient subi un avancement en une étape (AUÉ) ou une DO entre 2007 et 2016. Ils ont rajusté les données sur les coûts nominaux à l'aide de l'indice des prix à la consommation de la Banque du Canada. Les coûts déclarés représentaient la durée totale de tous les séjours hospitaliers par patient. Ils ont comparé l'information démographique et les données sur les coûts de l'ostéotomie en une étape à la DO. RÉSULTATS: Les coûts totaux de l'AUÉ (n = 8) étaient plus élevés que ceux de la DO (n = 6) (moyenne de 57 825 $ CA par rapport à 38 268 $, P < 0,05). Les coûts de l'unité de soins intensifs (USI) pour les AUÉ étaient considérablement plus élevés que la ceux de la DO (moyenne de 17 746 $ par rapport à 5 585 $, P < 0,005). Les cas de DO s'associent à un rapport de cotes des coûts plus élevé que l'AUÉ, mais la différence n'était pas significative (moyenne de 12 540 $ par rapport à 9 696 $). Le séjour hospitalier était considérablement plus long pour les patients subissant un AUÉ (moyenne de 11 jours par rapport à sept jours, P < 0,05). CONCLUSIONS: D'après la présente analyse rétrospective des coûts dans un seul établissement, la fixation interne rigide de l'AUÉ standard de Le Fort III est plus coûteuse que la DO. Malgré des coûts plus élevés en salle opératoire, un séjour prolongé à l'USI et à l'hôpital est la principale raison de cette différence. Cette information peut être utile pour défendre les nouvelles technologies qui sont perçues comme coûteuses.

Modeling the Effect of Relative Humidity on Adsorption Dynamics of Volatile Organic Compound onto Activated Carbon.

A two-dimensional heterogeneous mathematical model was developed and validated to study the effect of relative humidity on volatile organic compound (VOC) adsorption onto activated carbon. The dynamic adsorption model consists of the macroscopic mass, momentum, and energy conservation equations and includes a multicomponent adsorption isotherm to predict the competitive adsorption equilibria between VOC and water vapor, which is described by an extended Manes method. Experimental verifications show that the model predicted the breakthrough profiles during competitive adsorption of the studied VOCs (2-propanol, acetone, n-butanol, toluene, 1,2,4-trimethylbenzene) at relative humidity range 0-95% with an overall mean relative absolute error (MRAE) of 11.8% for dry (0% RH) conditions and 17.2% for humid (55 and 95% RH) conditions, and normalized root-mean-square error (NRMSE) of 5.5 and 8.4% for dry and humid conditions, respectively. Sensitivity analysis was also conducted to test the robustness of the model in accounting for the impact of relative humidity on VOC adsorption by varying the adsorption temperature. Good agreement was observed between the experimental and simulated results with an overall MRAE of 12.4 and 7.1% for the breakthrough profiles and adsorption capacity, respectively. The model can be used to quantify the impact of carrier gas relative humidity during adsorption of contaminants from gas streams, which is useful when optimizing adsorber design and operating conditions.

Comparing Cephalic Index and Midsagittal Vector Analysis in Assessing Morphology in Sagittal Synostosis: A CT-Based Morphometric Analysis.

INTRODUCTION: Assessment of cranial dysmorphism in sagittal synostosis is often subjective but objective measures can be applied. These include cephalic index (CI) and midsagittal vector analysis (MSVA). OBJECTIVE: To assess discriminant validity, construct validity, and responsiveness of CI and MSVA measured from computed tomography (CT) in patients with sagittal synostosis. METHODS: Patients with nonsyndromic isolated sagittal synostosis with complete preoperative (n = 30) and postoperative (n = 13) CT data were included. Age-matched control group (n = 24) comprised of normocephalic patients who underwent CT for reasons related to trauma. OUTCOME MEASURES: Retrospective CT evaluation of CI and MSVA was conducted and correlated with a dysmorphism numeric rating scale (D-NRS) that measured surgeon-rated severity of sagittal synostosis. Responsiveness of CI and MSVA was evaluated using dysmorphism global rating of change (D-GRC). RESULTS: Thirty patients with sagittal synostosis were demographically similar to 24 normocephalic patients. The difference in CI and MSVA was statistically significant between normocephalic and scaphocephalic patients. Cephalic index had a good correlation with D-NRS (r = -0.665, ρ = -0.667), but not with MSVA (r = 0.250, ρ = 0.203). Change in CI (r = 0.738, ρ = 0.657) was well correlated with D-GRC, but not with MSVA (r = -0.409, ρ = -0.301). CONCLUSION: Cephalic index appears to quantify the severity of sagittal synostosis better than MSVA. Cephalic index also has better responsiveness than MSVA to measure a reduction in severity of disease; however, MSVA is a better descriptive craniometric measurement. Midsagittal vector analysis was able to quantify the shift in morphology in sagittal synostosis following surgical treatment.

Custom CAD/CAM implants for complex craniofacial reconstruction in children: Our experience based on 136 cases✰.

BACKGROUND: CAD-CAM patient-specific implants offer cerebral protection and improved facial balance without the disadvantages of autologous bone grafting such as donor site morbidity and unpredictable resorption. Several alloplastic materials are available, but titanium, polymethylmethacrylate (PMMA), and polyetheretherketone (PEEK) are the current popular choices. We reviewed our experience of applying different alloplastic CAD-CAM materials in the reconstruction of complex pediatric craniofacial deformities. METHODS: A retrospective review was performed of all pediatric patients who underwent a complex inlay or onlay implant craniofacial reconstruction using CAD-CAM PEEK, PMMA, or titanium implants at a single institution. Demographics, cost, operative time, complications, and outcomes were assessed. RESULTS: Between 2003 and 2014, 136 patients (69 male; 67 female; mean age 11.5 years (3-22 years); mean follow-up 30 months) had custom patient-specific craniofacial reconstruction with PEEK (n = 72), PMMA (n = 42), and titanium (n = 22) implants (inlay = 93; onlay = 43). Indications included congenital anomalies (26.5%), decompressive craniectomies (25.0%), craniofacial syndromes (25.7%), tumor defects (14.0%), and post-trauma (6.6%). Implant cost varied significantly for PEEK ($7703 CAD) and PMMA ($8328 CAD) compared with that for titanium ($11,980 CAD) (p < 0.0005). Six patients (4.4%) required surgery due to infection consisting of irrigation and antibiotic administration with successful implant salvage in three patients. All infections occurred in the PEEK group. Five patients (3.7%) ultimately had implants removed due to infection (n = 3), late exposure (titanium; n = 1), or late fracture (PMMA; n = 1). CONCLUSIONS: CAD-CAM alloplast reconstruction in the management of complex pediatric craniofacial deformities is effective although expensive. Implant infection does not always require explantation. A reconstruction algorithm is presented.

A systematic review of endoscopic versus open treatment of craniosynostosis. Part 2: the nonsagittal single sutures.

OBJECTIVE: Despite increasing adoption of endoscopic techniques for repair of nonsagittal single-suture craniosynostosis, the efficacy and safety of the procedure relative to established open approaches are unknown. In this systematic review the authors aimed to directly compare open surgical and endoscope-assisted techniques for the treatment of metopic, unilateral coronal, and lambdoid craniosynostosis, with an emphasis on quantitative reported outcomes. METHODS: A literature search was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant articles were identified from 3 electronic databases (MEDLINE, EMBASE, and CENTRAL [Cochrane Central Register of Controlled Trials]) from their inception to August 2017. The quality of methodology and bias risk were assessed using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies. RESULTS: Of 316 screened records, 7 studies were included in a qualitative synthesis of the evidence, of which none were eligible for meta-analysis. These reported on 111 unique patients with metopic, 65 with unilateral coronal, and 12 with lambdoid craniosynostosis. For all suture types, 100 (53%) children underwent endoscope-assisted craniosynostosis surgery and 32 (47%) patients underwent open repair. These studies all suggest that blood loss, transfusion rate, operating time, and length of hospital stay were superior for endoscopically treated children. Although potentially comparable or better cosmetic outcomes are reported, the paucity of evidence and considerable variability in outcomes preclude meaningful conclusions. CONCLUSIONS: Limited data comparing open and endoscopic treatments for metopic, unilateral coronal, and lambdoid synostosis suggest a benefit for endoscopic techniques with respect to blood loss, transfusion, length of stay, and operating time. This report highlights shortcomings in evidence and gaps in knowledge regarding endoscopic repair of nonsagittal single-suture craniosynostosis, emphasizing the need for further matched-control studies.

A systematic review and meta-analysis of endoscopic versus open treatment of craniosynostosis. Part 1: the sagittal suture.

OBJECTIVE: In this systematic review and meta-analysis the authors aimed to directly compare open surgical and endoscope-assisted techniques for the treatment of sagittal craniosynostosis, focusing on the outcomes of blood loss, transfusion rate, length of stay, operating time, complication rate, cost, and cosmetic outcome. METHODS: A literature search was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant articles were identified from 3 electronic databases (MEDLINE, EMBASE, and CENTRAL [Cochrane Central Register of Controlled Trials]) from their inception to August 2017. The quality of methodology and bias risk were assessed using the Effective Public Health Practice Project Quality Assessment Tool for Quantitative Studies. Effect estimates between groups were calculated as standardized mean differences with 95% CIs. Random and fixed effects models were used to estimate the overall effect. RESULTS: Of 316 screened records, 10 met the inclusion criteria, of which 3 were included in the meta-analysis. These studies reported on 303 patients treated endoscopically and 385 patients treated with open surgery. Endoscopic surgery was associated with lower estimated blood loss (p < 0.001), shorter length of stay (p < 0.001), and shorter operating time (p < 0.001). From the literature review of the 10 studies, transfusion rates for endoscopic procedures were consistently lower, with significant differences in 4 of 6 studies; the cost was lower, with differences ranging from $11,603 to $31,744 in 3 of 3 studies; and the cosmetic outcomes were equivocal (p > 0.05) in 3 of 3 studies. Finally, endoscopic techniques demonstrated complication rates similar to or lower than those of open surgery in 8 of 8 studies. CONCLUSIONS: Endoscopic procedures are associated with lower estimated blood loss, operating time, and days in hospital. Future long-term prospective registries may establish advantages with respect to complications and cost, with equivalent cosmetic outcomes. Larger studies evaluating patient- or parent-reported satisfaction and optimal timing of intervention as well as heterogeneity in outcomes are indicated.

Bilateral Malar Reconstruction Using Patient-Specific Polyether Ether Ketone Implants in Treacher-Collins Syndrome Patients With Absent Zygomas.

The authors performed bilateral malar reconstruction using polyether ether ketone implants in 3 patients with Treacher-Collins syndrome with absent, as opposed to hypoplastic, zygomata. These patient-specific implants were fabricated using computed-aided design software reformatted from three-dimensional bony preoperative computed tomography images. The first time the authors performed this procedure the implant compressed the globe resulting in temporary anisocoria that was quickly recognized intraoperatively. The implant was immediately removed and the patient made a full-recovery with no ocular disturbance. The computer-aided design and manufacturing process was adjusted to include periorbital soft-tissue boundaries to aid in contouring the new implants. The same patient, and 2 further patients, subsequently underwent malar reconstruction using this soft tissue periorbital boundary fabrication process with an additional 2 mm relief removed from the implant's orbital surface. These subsequent procedures were performed without complication and with pleasing aesthetic results. The authors describe their experience and the salutary lessons learnt.

The role of beaded activated carbon's surface oxygen groups on irreversible adsorption of organic vapors.

The objective of this study is to determine the contribution of surface oxygen groups to irreversible adsorption (aka heel formation) during cyclic adsorption/regeneration of organic vapors commonly found in industrial systems, including vehicle-painting operations. For this purpose, three chemically modified activated carbon samples, including two oxygen-deficient (hydrogen-treated and heat-treated) and one oxygen-rich sample (nitric acid-treated) were prepared. The samples were tested for 5 adsorption/regeneration cycles using a mixture of nine organic compounds. For the different samples, mass balance cumulative heel was 14 and 20% higher for oxygen functionalized and hydrogen-treated samples, respectively, relative to heat-treated sample. Thermal analysis results showed heel formation due to physisorption for the oxygen-deficient samples, and weakened physisorption combined with chemisorption for the oxygen-rich sample. Chemisorption was attributed to consumption of surface oxygen groups by adsorbed species, resulting in formation of high boiling point oxidation byproducts or bonding between the adsorbates and the surface groups. Pore size distributions indicated that different pore sizes contributed to heel formation - narrow micropores (<7Å) in the oxygen-deficient samples and midsize micropores (7-12Å) in the oxygen-rich sample. The results from this study help explain the heel formation mechanism and how it relates to chemically tailored adsorbent materials.

The role of beaded activated carbon's pore size distribution on heel formation during cyclic adsorption/desorption of organic vapors.

The effect of activated carbon's pore size distribution (PSD) on heel formation during adsorption of organic vapors was investigated. Five commercially available beaded activated carbons (BAC) with varying PSDs (30-88% microporous) were investigated. Virgin samples had similar elemental compositions but different PSDs, which allowed for isolating the contribution of carbon's microporosity to heel formation. Heel formation was linearly correlated (R(2)=0.91) with BAC micropore volume; heel for the BAC with the lowest micropore volume was 20% lower than the BAC with the highest micropore volume. Meanwhile, first cycle adsorption capacities and breakthrough times correlated linearly (R(2)=0.87 and 0.93, respectively) with BAC total pore volume. Micropore volume reduction for all BACs confirmed that heel accumulation takes place in the highest energy pores. Overall, these results show that a greater portion of adsorbed species are converted into heel on highly microporous adsorbents due to higher share of high energy adsorption sites in their structure. This differs from mesoporous adsorbents (low microporosity) in which large pores contribute to adsorption but not to heel formation, resulting in longer adsorbent lifetime. Thus, activated carbon with high adsorption capacity and high mesopore fraction is particularly desirable for organic vapor application involving extended adsorption/regeneration cycling.

Optimization of Cranio-Orbital Remodeling: Application of a Mathematical Model.

Cranio-orbital remodeling aims to correct the dysmorphic skull associated with craniosynostosis. Traditionally, the skull is reconstructed into a shape that is subjectively normal according to the surgeon's perception. We present a novel technique using a mathematical algorithm to define the optimal location for bony osteotomies and to objectively reshape the fronto-orbital bar into an ideal normal skull contour. Using pre-operative computed tomography images, the abnormal skull contour at the frontal-orbital region was obtained for infants planned to undergo cranio-orbital remodeling. The ideal skull shape was derived from an age- and sex-matched normative skull library. For each patient, the mathematical technique of dynamic programming (DP) was applied to compare the abnormal and ideal skull shapes. The DP algorithm identifies the optimal location of osteotomy sites and calculates the objective difference in surface area remaining between the normative and dysmorphic skull shape for each solution applied. By selecting the optimal solution with minimal objective difference, the surgeon is guided to reproducibly recreate the normal skull contour with defined osteotomies. The DP algorithm was applied in 13 cases of cranio-orbital remodeling. Five female and 8 male infants with a mean age of 11 months were treated for craniosynostosis classified as metopic (n = 7), unicoronal (n = 4), or bicoronal (n = 2). The mean OR time was 190.2  min (SD 33.6), mean estimated blood loss 244  cc (SD 147.6), and 10 infants required blood transfusions. Compared with a historical crania-orbital remodeling group treated without application of the algorithm, there was no significant difference in OR time, estimated blood loss, or transfusion rate. This novel technique enables the craniofacial surgeon to objectively reshape the fronto-orbital bar and reproducibly reconstruct a skull shape resembling that of normal infants.

Using microwave heating to improve the desorption efficiency of high molecular weight VOC from beaded activated carbon.

Incomplete regeneration of activated carbon loaded with organic compounds results in heel build-up that reduces the useful life of the adsorbent. In this study, microwave heating was tested as a regeneration method for beaded activated carbon (BAC) loaded with n-dodecane, a high molecular weight volatile organic compound. Energy consumption and desorption efficiency for microwave-heating regeneration were compared with conductive-heating regeneration. The minimum energy needed to completely regenerate the adsorbent (100% desorption efficiency) using microwave regeneration was 6% of that needed with conductive heating regeneration, owing to more rapid heating rates and lower heat loss. Analyses of adsorbent pore size distribution and surface chemistry confirmed that neither heating method altered the physical/chemical properties of the BAC. Additionally, gas chromatography (with flame ionization detector) confirmed that neither regeneration method detectably altered the adsorbate composition during desorption. By demonstrating improvements in energy consumption and desorption efficiency and showing stable adsorbate and adsorbent properties, this paper suggests that microwave heating is an attractive method for activated carbon regeneration particularly when high-affinity VOC adsorbates are present.

Is Linear Advancement Related to Relapse in Unilateral Cleft Lip and Palate Orthognathic Surgery?

OBJECTIVE: To investigate the stability of major versus minor Le Fort I maxillary advancements in unilateral cleft lip and palate (UCLP) patients. DESIGN: A retrospective longitudinal study was undertaken on 30 nonsyndromic UCLP patients treated with the same protocol at The Hospital for Sick Children, Toronto, Canada. Patients were grouped into major and minor movement groups based on planned surgical advancement. Standard lateral cephalometric radiographs were taken preoperatively (T1), immediately postoperatively (T2), and at least 1 year postoperatively (T3). Skeletal and dental variables were measured using cephalometric analysis. Stability was compared between groups using repeated-measures analysis of variance. Linear regression analysis was used to assess the relationship between advancement and relapse for the entire study population. RESULTS: A mean maxillary advancement of 9.8 mm and 4.9 mm was seen for the major (n = 10) and minor (n = 20) movement groups, respectively. The mean skeletal horizontal relapse was 1.8 mm (18%) for the major advancement group and 1.5 mm (31%) for the minor advancement group. There was no significant difference in skeletal horizontal relapse between the groups (P > .05). The correlation coefficient (r) between linear horizontal advancement and relapse was calculated to be .31 (P > .05). Dental horizontal relapse was not significant for either the major or minor groups, and no significant difference was found between the groups (P > .05). CONCLUSION: Skeletal and dental relapse was found to be unrelated to the amount of maxillary linear advancement using conventional Le Fort I osteotomies in UCLP.

Single versus segmental maxillary osteotomies and long-term stability in unilateral cleft lip and palate related malocclusion.

PURPOSE: To investigate the stability of single-piece versus segmental (2-piece) maxillary advancement in patients with unilateral cleft lip and palate (UCLP) treated using conventional Le Fort I orthognathic surgery. PATIENTS AND METHODS: A retrospective study was undertaken in 30 patients with nonsyndromic UCLP treated with the same surgical and orthodontic protocol from 2002 through 2011. Standard lateral cephalometric radiographs were taken preoperatively, immediately postoperatively, and at least 1 year postoperatively. Patients were divided into single-piece and segmental Le Fort I groups based on planned surgical movement. Postoperative movements were compared between groups using repeated measures analysis of variance. RESULTS: The mean skeletal horizontal advancement was 7.3 and 7.5 mm in the single-piece and segmental groups, respectively. The skeletal horizontal relapse was 1.3 mm (18%) for the single-piece group and 1.9 mm (25%) for the segmental group. The skeletal surgical extrusion was 2.7 mm for the 2 groups. The skeletal vertical relapse was 0.6 mm (22%) and 1.5 mm (56%) for the single-piece and segmental groups, respectively. The mean dental horizontal postoperative movement was an advancement of 0.4 mm for the single-piece group and a relapse of 0.2 mm (3%) for the segmental group. The mean dental vertical relapse was 0.1 mm (4%) for the single-piece group and 0.3 mm (11%) for the segmental group. There was no statistically significant difference in relapse between the single-piece and segmental groups for all movements (P>.05). CONCLUSION: Skeletal and dental relapse was similar between single-piece and segmental maxillary advancements using conventional Le Fort I orthognathic surgery in patients with UCLP.