Max Zinser

Computer-assisted orthognathic surgery: feasibility study using multiple CAD/CAM surgical splints

OBJECTIVE We present a virtual planning protocol incorporating a patented 3-surgical splint technique for orthognathic surgery. The purpose of this investigation was to demonstrate the feasibility and validity of the method in vivo. MATERIALS AND METHODS The protocol consisted of (1) computed tomography (CT) or cone-beam computed tomography (CBCT) maxillofacial imaging, optical scan of articulated dental study models, segmentation, and fusion; (2) diagnosis and virtual treatment planning; (3) computed-assisted design and manufacture (CAD/CAM) of the surgical splints; and (4) intraoperative surgical transfer. Validation of the accuracy of the technique was investigated by applying the protocol to 8 adult class III patients treated with bimaxillary osteotomies. The virtual plan was compared with the postoperative surgical result using image fusion of CT/CBCT dataset by analysis of measurements between hard and soft tissue landmarks relative to reference planes. RESULTS The virtual planning approach showed clinically acceptable precision for the position of the maxilla (<0.23 mm) and condyle (<0.19 mm), marginal precision for the mandible (<0.33 mm), and low precision for the soft tissue (<2.52 mm). CONCLUSIONS Virtual diagnosis, planning, and use of a patented CAD/CAM surgical splint technique provides a reliable method that may offer an alternate approach to the use of arbitrary splints and 2-dimensional planning.

Prevalence of pathologic findings in the maxillary sinus in cone-beam computerized tomography

OBJECTIVE The aim of this study was to assess the prevalence of pathologic findings in the maxillary sinus by using cone-beam computerized tomography (CBCT). STUDY DESIGN One thousand twenty-nine consecutive CBCT scans were retrospectively inspected for pathologic findings in the maxillary sinus by 3 observers. Findings were differentiated by mucosal thickening, partial opacification with liquid accumulation, total opacification, and polypoidal mucosal thickening. Position and diameter of the maxillary sinus ostium were assessed. Correlations for pathologic findings and the factors of age and gender were calculated. Patients with clinical manifestations of sinusitis or total opacification in either sinus were reevaluated. RESULTS A total prevalence for pathologies in the maxillary sinus of 56.3% was found in this study. The most frequent pathology was mucosal thickening. Patients >60 years of age showed significantly more pathologies in the maxillary sinus (P = .02), and male patients showed significantly more pathologies than female patients (P = .01). Clinical signs of sinusitis could be confirmed on CBCT images for all patients. CONCLUSIONS Pathologies in the maxillary sinus are frequently found in CBCT imaging and have to be treated or followed-up accordingly. CBCT is applicable for diagnosis and treatment planning of clinically present sinusitis.

Computer-assisted orthognathic surgery: waferless maxillary positioning, versatility, and accuracy of an image-guided visualisation display

There may well be a shift towards 3-dimensional orthognathic surgery when virtual surgical planning can be applied clinically. We present a computer-assisted protocol that uses surgical navigation supplemented by an interactive image-guided visualisation display (IGVD) to transfer virtual maxillary planning precisely. The aim of this study was to analyse its accuracy and versatility in vivo. The protocol consists of maxillofacial imaging, diagnosis, planning of virtual treatment, and intraoperative surgical transfer using an IGV display. The advantage of the interactive IGV display is that the virtually planned maxilla and its real position can be completely superimposed during operation through a video graphics array (VGA) camera, thereby augmenting the surgeons 3-dimensional perception. Sixteen adult class III patients were treated with by bimaxillary osteotomy. Seven hard tissue variables were chosen to compare (ΔT1-T0) the virtual maxillary planning (T0) with the postoperative result (T1) using 3-dimensional cephalometry. Clinically acceptable precision for the surgical planning transfer of the maxilla (<0.35 mm) was seen in the anteroposterior and mediolateral angles, and in relation to the skull base (<0.35°), and marginal precision was seen in the orthogonal dimension (<0.64 mm). An interactive IGV display complemented surgical navigation, augmented virtual and real-time reality, and provided a precise technique of waferless stereotactic maxillary positioning, which may offer an alternative approach to the use of arbitrary splints and 2-dimensional orthognathic planning.

Bimaxillary ‘rotation advancement’ procedures in patients with obstructive sleep apnea: a 3-dimensional airway analysis of morphological changes

The aim of this retrospective three dimensional (3D) computed tomographic analysis was to investigate the morphological airway changes in 17 obstructive sleep apnea (OSA) patients following bimaxillary rotation advancement procedures. Morphological changes of the nasal cavity and naso-, oro- and hypopharynx were analysed separately, as were the total airway changes using nine parameters of airway size and four of shape. The Wilcoxon test was used to compare airway changes and the intraclass correlation coefficient to qualify inter-observer reliability. Following bimaxillary advancement and anti-clockwise maxillary rotation, the total airway volume and the lateral dimension of the cross-sectional airway increased significantly. The total length of the airway became shorter (p<0.05). Remarkable changes were seen in the oropharynx: the length, volume, cross-sectional area (CSA), antero-posterior and medio-lateral distance changed (p<0.05). This combined with a significant 3D change in the shape of the airway from round to elliptical. The average cross-sectional oropharyngeal area was nearly doubled, the minimal CSA increased 40%, and the hyoid bone was located more anterior and superior. Inter-examiner reliabilities were high (0.89). 3D airway analysis aids the understanding of postoperative pathophysiological changes in OSA patients. The airway became shorter, more voluminous, medio-laterally wider, and more compact and elliptical.

Injectable hemostatic adjuncts in trauma: Fibrinogen and the FIinTIC study.

F adequate hemostasis, sufficient amounts of thrombin and coagulable substrate are fundamental prerequisites. In addition to platelets, on whose surfaces most of the thrombin is generated, fibrinogen can be considered as the substrate of the coagulation process. If sufficient thrombin is formed, it converts fibrinogen into stable fibrin, which determines the firmness of the developing clot in the presence of activated coagulation factor XIII (Fig. 1). Under physiologic conditions, fibrinogen availability is regulated through dynamic changes in synthesis and breakdown to preserve coagulation function. As a consequence of blood loss, consumption of coagulation factors, dilutional coagulopathy, hypothermia and acidosis, as well as profibrinolytic activation, fibrinogen may reach critical levels earlier than any other procoagulant factor and also platelets even before packed red blood cell concentrate administration becomes necessary. Floccard et al. have described even significant drops in fibrinogen levels to occur already during the ultra early prehospital phase of care when comparing blood samples obtained from bleeding trauma patients at the scene and at the time point of arrival to the trauma bay (fibrinogen median, 2.6 g/L; interquartile range [IQR], 2.3Y3.1; 95% confidence interval [CI], 2.4Y2.9 vs. 2.1 g/L; IQR, 1.4Y2.5; 95% CI, 1.7Y2.3) (changes, j0.6 g/L; IQR, j1.1 to j0.3; 95%CI,j0.9 toj0.3;pG 0.001). In this study, fibrinogen levels decreased substantially as a function of injury severity reflected by Injury Severity Scores (ISSs). Recently, Kimura et al. have reported similar results when searching retrospectively for predictors of hypofibrinogenemia in 290 blunt traumapatients upon admission to aLevel 1 trauma center during a 3-year period. Their multivariate regression analysis identified patient’s age (odds ratio [OR], 0.97; p G 0.001), Triage Revised Trauma Score (T-RTS including Glasgow Coma Scale [GCS] score, respiratory rate, and systolic blood pressure; OR, 0.81; p = 0.003), and prehospital volume therapy (OR, 2.54; p = 0.01) as independent predictors for early hypofibrinogenemia. In contrast todisseminated intravascular coagulopathy, there is no generalized intravascular microcoagulation with increased consumption in trauma-induced coagulopathy. Instead, there is hemorrhage-related loss of coagulation factors and platelets with subsequent dilution of procoagulant factors due to (uncritical) volume resuscitation with direct effect on fibrinogen polymerization. Dilution of fibrinogen by crystalloid fluids and additional reduced fibrin interlinkage by synthetic colloids has been discussed. Recently, experimental data confirmed significant fibrinogen breakdown by acidosis following hypoperfusion with no effect on fibrinogen synthesis, while hypothermia decreased fibrinogen synthesis with no effect on fibrinogen degradation. Furthermore, synthesis and degradation seem to be regulated through different mechanisms, and a potential deficit in fibrinogen availability during hypothermia has been suggested.

The predictors of implant failure after maxillary sinus floor augmentation and reconstruction: a retrospective study of 1045 consecutive implants

OBJECTIVE To assess the predictors of implant failure after grafted maxillary sinus (GMS). MATERIAL AND METHODS A total of 1045 implants were inserted in 224 patients/347 GMS during a period of 14 years. Kaplan-Meyer and multivariate log-regression analysis were used to assess the following variates: patients age, gender, smoker/nonsmoker, American Society of Anesthesiologists (ASA) class, one/two-stage surgery, merged/submerged healing, membrane, antibiotics, auto/allo/xenogenic bone grafts, implants lengths/surface/diameter, crestal bone atrophy/quality, implant region, prosthetics, opposing dentition, and implant proximity to evaluate the predictors and relative risk (hazard ratio [HR]) of implant failure. RESULTS Significant implant failure predictors were the graft material (HR = 4.7), with superior results for autogenic bone, residual crestal bone height (HR = 3.51), ASA class (HR = 2.73), surgical technique (HR = 2.56), implant proximity (HR = 2.07), smoker (HR = 1.98), and age (>60/HR=1.39). All other factors were insignificant. Overall survival rate was 93.3%. CONCLUSIONS GMS is effective when the predictors are considered. Patient selection, including the ASA status, smoking, residual bone height, and the graft material are the predominant predictors. In highly atrophic situations, autogenic bone grafts showed superiority; however, in less atrophic cases, nonautogenic bone-grafts are equivalent.

Incidence and treatment of burns: A twenty-year experience from a single center in Germany

OBJECTIVE To analyze trends in incidence and treatment of thermal injuries over the last two decades. METHODS We retrospectively reviewed our local single center database of patients with thermal injuries admitted to the burn intensive care unit (BICU) of the Cologne-Merheim Medical Center (University Hospital of Witten/Herdecke). The cohort was divided into two groups according to the decade of admission and the epidemiology and clinical course of the patient sample admitted during the period 1991-2000 (n=911) was compared to that of 2001-2010 (n=695). RESULTS The following variables were significantly different in the bivariate analysis: mean age (39.8 years vs. 44.0 years), burn size of total body surface area (23.2% vs. 18.0%) and size of 3rd degree burns (9.6% vs. 14.9%). The incidence of inhalation injury was significantly lower in the last decade (33.3% vs. 13.7%) and was associated with a shorter duration of mechanical ventilation (10.8 days vs. 8.5 days). The ABSI-score as an indicator of burn severity declined in the second period (6.3 vs. 6.0) contributing partially to the decline of BICU length of stay (19.1 days vs. 18.8 days) and to the mortality rate decrease (18.6% vs. 15.0%). CONCLUSION The severity of burn injuries during the last two decades declined, probably reflecting the success of prevention campaigns. Concerning mortality, the chance of dying for a given severity of injury has decreased.

Donor-site Morbidity of Ear Cartilage Autografts

Background: The external ear provides a versatile cartilage source for reconstructive procedures, especially for augmentative rhinoplasty. The authors evaluated the short- and long-term morbidity associated with ear cartilage harvest using concha, tragus, and scapha as donor sites. Methods: The study included 52 patients in whom a cartilage graft from the external ear was harvested between February of 2001 and June of 2005. Donor-site morbidity was assessed in the early postoperative follow-up period. Twenty-eight patients were examined within a follow-up time of 3 to 168 months. Long-term morbidity assessment included documentation of patients’ subjective complaints, clinical examination of the donor site, and anthropometric measurements. Results: The relevant morbidity factors in the early postoperative period were hematoma formation (6.7 percent) and sensory impairment (3.3 percent). In long-term follow-up, sensory impairment was the most frequent condition objectively assessed and subjectively complained of (12.9 percent). Overall, sensory impairment was confined to concha as the donor site. Anthropometric measurements showed a mean difference in the length of the affected ear compared with the contralateral ear of 1.8 mm, a width difference of 2.5 mm, a difference in tragus/lateral canthus distance of 1.4 mm, and a difference in protrusion angle of 2.4 degrees. Statistically significant differences between values obtained from operated and nonoperated ears could not be detected for every evaluated parameter using the paired t test. Aesthetically relevant complications were rare and their occurrence restricted to single cases. Conclusion: Cartilage graft harvest from the auricle can be considered as a relatively safe procedure with a favorable aesthetic outcome.

CBCT device dependency on the transfer accuracy from computer‐aided implantology procedures

OBJECTIVES To evaluate the potential influence of different cone-beam computed tomography (CBCT) devices on the transfer accuracy of an open-source system for computer-aided implantology (CAI). MATERIAL AND METHODS A total of 108 implants in 18 partially edentulous patient-equivalent models were planned and fully guided implants were inserted using an open-source CAI system with three different CBCT devices. After follow-up CBCT and fiducial marker-matching procedure, linear horizontal, vertical, and maximal three-dimensional deviations, as well as angle deviations between the virtual planning data and the surgical results were calculated. Variance analysis was carried out to prove whether or not the observed differences between the CBCT devices were statistically significant. RESULTS The observed mean three-dimensional deviation rates between virtually planned and achieved implant positions varied by around 400 μm (45%) at the implants base and around 540 μm (50%) at the implants tip in dependence to the applied CBCT device. Mean vertical deviations varied around 370 μm (76%) at the implants base and 350 μm (69%) at the implants tip, whereas axes deviations varied around 0.81° (40%) between the three investigated CBCT devices. Except for the axes deviations and the horizontal linear deviations at the implants base, observed differences reached significance level between the CBCT devices. CONCLUSIONS Until now, the potential influence from different CBCT devices on the transfer accuracy of CAI systems has not yet been investigated. Data from the present study confirm for the first time the in vitro CBCT device dependency on the transfer accuracy of CAI systems reaching up to axes deviations of 0.6 angle degree and linear deviations around half a millimeter.

Prognostic quality of the Union Internationale Contre le Cancer/American Joint Committee on Cancer TNM classification, 7th edition, for cancer of the maxillary sinus

Carcinomas of the maxillary sinus are classified according to the Union Internationale Contre le Cancer (UICC)/American Joint Committee on Cancer (AJCC) TNM classification. The purpose of this study was to assess the prognostic significance of the UICC/AJCC TNM classification seventh edition, which was introduced in 2010.