Identification of risk factors for postoperative delirium in patients following intraoral reconstruction with microvascular free flaps: a matched-pair analysis

Postoperative delirium (POD) following microvascular head and neck reconstruction negatively impacts patient outcomes, and only a few risk factors have been identified. The aim of this study was to identify additional risk factors for POD after intraoral reconstruction with microvascular free flaps. Data from 377 patients who underwent intraoral microvascular free flap reconstruction between 2011 and 2019 were analysed retrospectively. Preoperative, intraoperative, and postoperative variables were compared between 40 patients with POD and 40 patients without POD who were matched for previously identified risk factors (i.e., sex, age, American Society of Anesthesiologists class, preoperative arterial hypertension, tracheotomy, operation time, and blood transfusion). A multivariable regression analysis was then performed to identify risk factors associated with POD. POD occurred in 50 (13.3%) of the 377 cases studied; the median time of onset was postoperative day 2. Excessive preoperative alcohol consumption (odds ratio 9.22, 95% confidence interval 1.09-77.97; P = 0.041) and postoperative transplant revision (odds ratio 25.72, 95% confidence interval 1.26-525.43; P = 0.035) were identified as risk factors for POD. The identification of patients at high risk of POD based on these two risk factors may allow early adjustment of diagnostic and therapeutic modalities to improve outcomes and reduce healthcare costs.

Evaluation of fibrin, cyanoacrylate, and polyurethane-based tissue adhesives in sutureless vascular anastomosis: a comparative mechanical ex vivo study

The stability of a microvascular anastomosis is an important prerequisite for successful tissue transfer. Advances in tissue adhesives are potentially opening new avenues for their use in sutureless microsurgical anastomosis, however they have not yet gained clinical acceptance. In this ex vivo study, a novel polyurethane-based adhesive (PA) was used in sutureless anastomoses and its stability compared with that of sutureless anastomoses performed with fibrin glue (FG) and a cyanoacrylate (CA). Stability was assessed using hydrostatic (15 per group) and mechanical tests (13 per group). A total of 84 chicken femoral arteries were used in this study. The time taken to create the PA and CA anastomoses was significantly faster when compared to the FG anastomoses (P < 0.001): 1.55 ± 0.14 min and 1.39 ± 0.06 min, respectively, compared to 2.03 ± 0.35 min. Both sustained significantly higher pressures (289.3 mmHg and 292.7 mmHg, respectively) than anastomoses using FG (137.3 mmHg) (P < 0.001). CA anastomoses (0.99 N; P < 0.001) and PA anastomoses (0.38 N; P = 0.009) could both withstand significantly higher longitudinal tensile forces compared to FG anastomoses (0.10 N). Considering the background of an in vitro study, the PA and CA anastomosis techniques were shown to be similar to each other and superior to FG, due to their stability and faster handling. These findings need to be validated and confirmed in further in vivo studies.

Evaluation of anterolateral thigh flap dimensions with virtual flap models

Free flaps are commonly used for head and neck reconstruction. However, flap dimensions are still evaluated by visual and tactile assessment. The aim of this study was to enable preoperative planning of flap dimensions for soft tissue reconstruction based on clinical parameters. Computed tomography records from 230 patients dated from 2009 to 2019 were analysed retrospectively. A virtual, three-dimensional anterolateral thigh flap model was standardized, aligned to segmented leg models in two positions, and flap thicknesses and volumes were determined. Associations of flap thickness and volume with clinical parameters were evaluated, and an approximative calculation method was derived. The laterally positioned anterolateral thigh flap showed an average (interquartile range) thickness of 15.6 mm (8.7 mm) and volume of 1.5 cm³ (0.9 cm³) per cm². The medially positioned anterolateral thigh flap showed an average (interquartile range) thickness of 16.3 mm (8.7 mm) and volume of 1.6 cm³ (0.9 cm³) per cm². For both flap positions, leg circumference was the strongest predictor of flap thickness (β = 0.545, P < 0.001 and β = 0.529, P < 0.001) and flap volume (β = 0.523, P < 0.001 and β = 0.480, P < 0.001). Flap dimensions can be calculated based on leg circumference, and this preoperative planning of flap dimensions can help the surgeon to select the appropriate flap.

Perfusion of microvascular free flaps in head and neck reconstruction after prior neck dissection and irradiation

Microvascular free flaps are frequently used for head and neck reconstruction after prior neck dissection (ND) and neck irradiation (RTX). The aim of this study was to investigate the influence of ND and RTX on flap perfusion as a critical factor for flap success. Overall, 392 patients reconstructed with a microvascular fasciocutaneous flap (FF) or perforator flap (PF) in the head and neck region between 2011 and 2020 were analysed retrospectively. Flap perfusion measured intraoperatively and postoperatively with the O2C tissue oxygen analysis system was compared between patients who had received neither ND nor RTX (controls), patients who had received ND but no RTX (ND group), and patients who had received both ND and RTX (ND+RTX group). Intraoperative and postoperative flap blood flow was decreased in FFs in ND group patients compared to controls (median 66.3 AU vs 86.0 AU, P = 0.023; median 73.5 AU vs 93.8 AU, P = 0.045, respectively). In the multivariable analysis, these differences showed a tendency to persist (P = 0.052 and P = 0.056). Flap success rates were similar in control patients, ND patients, and ND+RTX patients (98.7%, 94.0%, and 97.6%, respectively). Flap perfusion is not reduced in FFs and PFs in patients who have undergone ND or ND and RTX. This indicates that neck dissection and neck irradiation should not be contraindications for microvascular free flap reconstruction.

[Current developments in primary and secondary surgical treatment of midface and periorbital trauma]

Fractures of the periorbita and the midface are among the most common bony facial injuries. Aesthetic and functional reconstruction is a challenge in clinical routine. This article illustrates recent developments in the primary and secondary surgical treatment of midface and periorbital trauma. Resorbable patches and films increase the anatomic reconstructive capacity and enable treatment of extensive orbital fractures. Orbital fractures with involvement of supporting key structures are advantageously reconstructed using patient-specific implants (PSI), which are fabricated by computer-assisted manufacturing techniques and positioned by intraoperative navigation. If late complications such as bulbar malposition and enophthalmos have occurred after the initial procedure, they can be addressed by overcorrective restoration of orbital volume. The use of PSI for initial fracture restoration of the midface is not yet established but may be useful in re-osteotomies of misconsolidated fragments. Extensive midface defects with significant soft tissue involvement can be reconstructed using microvascular grafts. Consecutive reconstructive procedures may include orthognathic surgery and local flap reconstruction. In summary, the integration and advancement of computer-assisted techniques now offers individualized reconstruction procedures, which may be a viable alternative to conventional implants and compression miniplates. Future developments may focus on the search for innovative biomaterials, which can be integrated into computer-aided design and manufacturing processes.

The primary stability of two dental implant systems in low-density bone

Primary stability in low-density bone is crucial for the long-term success of implants. Tapered implants have shown particularly favourable properties under such conditions. The aim of this study was to compare the primary stability of tapered titanium and novel cylindrical zirconia dental implant systems in low-density bone. Fifty implants (25 tapered, 25 cylindrical) were placed in the anterior maxillary bone of cadavers meeting the criteria of low-density bone. The maximum insertion (ITV) and removal (RTV) torque values were recorded, and the implant stability quotients (ISQ) determined. To establish the isolated influence of cancellous bone on primary stability, the implantation procedure was performed in standardized low-density polyurethane foam bone blocks (cancellous bone model) using the same procedure. The primary stability parameters of both implant types showed significant positive correlations with bone density (Hounsfield units) and cortical thickness. In the cadaver, the cylindrical zirconia implants showed a significantly higher mean ISQ when compared to the tapered titanium implants (50.58 vs 37.26; P < 0.001). Pearson analysis showed significant positive correlations between ITV and ISQ (P = 0.016) and between RTV and ISQ (P = 0.035) for the cylindrical zirconia implants; no such correlations were observed for the tapered titanium implants. Within the limitations of this study, the results indicate that cylindrical zirconia implants represent a comparable viable treatment option to tapered titanium implants in terms of primary implant stability in low-density human bone.

Immune checkpoint analysis in lip cancer

The aim of this study was to establish whether PD-L1, PD-1, and markers of the tumor microenvironment (CD4, CD8, FOXP3) could have a prognostic value in squamous cell carcinoma of the lip (LSCC). In patients with histologically proven LSCC, tumor specimens were stained using immunohistochemistry (for PD-1, PD-L1, CD4, CD8, and FOXP3) on paraffin-embedded tissues. Patients with (N+) and without (N-) nodal metastasis were stratified and matched to each other according to prognostically relevant clinicopathological parameters. 58 patients (29 N+ and 29 N-) were included. PD-L1 expression was positive (>1%) in 56.1% (n = 33) of all LSCC cases, but its expression did not differ significantly between metastasis groups (65.5% in N+ versus 48.3% in N-; p = 0.144). Nodal disseminated LSCC showed a tendency for higher PD-L1 expression. None of the analyzed markers showed significant correlation with the risk for nodal disease, or revealed significant prognostic value. Due to their significant expression, PD-L1 and PD-1 are potential targets for checkpoint inhibitor therapy in LSCC. Their expression should be analyzed in advanced and metastasized LSCC cases.

The effect of zirconia and titanium surfaces on biofilm formation and on host-derived immunological parameters

The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P< 0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.

Immediate dental and skeletal influence of distractor position on surgically assisted rapid palatal expansion with or without pterygomaxillary disjunction

The outcome of surgically assisted rapid palatal expansion (SARPE) can be affected by pterygomaxillary disjunction (PMD) and the distractor position. In this study, SARPE was performed, with or without PMD, in 20 fresh cadaver heads. Transverse expansion was conducted twice using a bone-borne distractor in the anterior and posterior positions, resulting in four groups (n=10). Cone beam computed tomography scans were completed before and after SARPE to evaluate maxillary changes. A comparative anterior decrease and posterior increase in midpalatal opening resulted from SARPE with PMD combined with a posteriorly placed distractor. Significant differences in the internal transverse changes were found between the two SARPE techniques combined with an anterior distractor at the level of the premolars and molars for alveolar ridge width (P=0.040, P=0.024), and at the level of the molars for the dental crown width (P=0.017) and corresponding tooth cusp width (P=0.018). In contrast, using a posteriorly placed distractor led to a significant difference for tooth cusp width only (P=0.050). No statistically significant differences were found between external transverse changes or between distractor positions. PMD is more important in achieving a more uniform and parallel transverse expansion pattern than the distractor position. However, a posterior distractor seems to intensify the effects of PMD.

Evaluation of a novel osteosynthesis plate system for mandibular defects

Continuity defects of the jaw can be reconstructed with titanium plates or microvascular bone flaps; osteosynthesis plates are necessary for both. In this study we performed a retrospective review of patients treated with Medartis MODUS® Mandible Trauma/Reco 2.0-2.5, TriLock bridging plates, mandibulectomy and soft tissue free flap or reconstruction with a bony free flap and TriLock mandibular plates from the same system from January 2015 to August 2019. The variables recorded were sex, age, diagnosis, radiotherapy, date of implantation, date of explantation or death of patient, size of mandibular defect, Jewer classification of defect, number of screws used, segments of bony reconstruction, screws per segment, plate exposure, plate breakage, and pseudarthrosis. The bridging plate group consisted of 41 patients, while the mandibular plate group consisted of 24 patients. The percentage of plate exposure was 17.07% for the bridging plate group and 4.17% for the mandibular plate group. Plate breakage was 0 in both groups. Pseudarthrosis was 4.17% in the mandibular plate group. In the bridging plate group, an anterolateral thigh flap covered all exposures. Of 7 plate exposures, 4 were found in a C defect. The complication rate of the investigated plates was lower than the complication rates of other plate systems.

Influence of bone density, screw size and surgical procedure on orthodontic mini-implant placement - part B: implant stability

This in vitro study aimed to investigate the influence of bone density, implant size, and surgical procedure on the primary stability (PS) of orthodontic mini-implants (OMIs). In total, 640 OMIs of various sizes (2.0 × 7, 2.3 × 7, 2.0 × 11 and 2.3 × 11 mm) were inserted in the artificial bone of different densities (D1-D4). Placement was performed with an insertion angle of 90° or 60° to the bone surface and in 320 cases without predrilling, which resulted in 64 groups. PS was measured on the basis of implant stability quotient (ISQ) and insertion torque (IT). With regard to all possible influencing parameters, the mean PS differed between 39.20 and 60.00 (ISQ), and 10.00 and 39.00 Ncm (IT). The effect of OMI size and surgical procedure was dependent on bone quality. For example, implant size had less effect in high-density bone and was stronger with decreasing density. Overall, implant length had a greater influence than the diameter, and a high correlation was found among both PS measurement techniques. Therefore, a suitable choice of implant size and surgical protocol with regard to bone density can positively influence PS. In principle, ISQ and IT are suitable for measuring OMI stability.

Influence of bone density, screw size and surgical procedure on orthodontic mini-implant placement - part A: temperature development

The aim of this in vitro study was to determine the influence of bone density, orthodontic mini-implant (OMI) size, and the surgical procedure on temperature increase during implant site osteotomy and placement. OMIs of different sizes (2.0×7, 2.3×7, 2.0×11, and 2.3×11mm) were placed in artificial bone blocks of different densities (D1-D4). Optionally, the drilling and insertion angle was 90° or 60° to the bone surface. A total of 640 OMIs were inserted, and predrilling was performed in 320 cases. All insertions were done without irrigation with an axial load of 20N, which resulted in 64 groups. Temperature measurements were performed during implant site preparation and placement using Type-K-thermocouples. Mean temperature increase differed for OMI osteotomy between 1.38°C and 8.75°C and placement between 3.8°C and 18.74°C, respectively. Critical thermal increase was especially reached during placement using long implants. Increasing bone density and implant size (diameter <length) correlated with thermal increase. Predrilling and angulated implant placement resulted in less heat development. Critical temperature behaviour in high-density bone could be partially responsible for the high failure rates of OMI placement in the lower jaw. The influence of the implant size on temperature development should be considered when selecting an OMI.

Aesthetic aspects of adjacent maxillary single-crown implants-influence of zirconia and titanium as implant materials

The purpose of this retrospective survey was to assess the esthetic aspects of adjacent zirconia and titanium implants in the anterior maxillary area. A total of 40 patients and 109 adjacent implants (17 patients with 47 titanium implants and 23 patients with 62 zirconia implants) was included. The primary aim of this survey was to assess the papillary fill (Jemt score). Additionally, further esthetic aspects were assessed. Papillae were fully present (Jemt score 3) around 39.1% of adjacent zirconia implants and 17.4% of adjacent titanium implants (p<0.01). The papilla deficit was significantly higher 1.64 mm (SD 1.35) around titanium compared to zirconia implants 0.92 mm (SD 0.94, p<0.01). The evaluation of the soft tissue recessions revealed no differences between implant materials, whereas titanium implants presented more visible implant shadows (p<0.01). Zirconia implants had more implants with papillae that filled the entire proximal space compared to titanium implants. Furthermore, titanium implants had a greater frequency of visible implant shadowing than the zirconia implants. Esthetic rules such as the interdental contact area and golden percentage rules did not differ significantly between the titanium and zirconia implants.

Evaluation of the bactericidal effect of cold atmospheric pressure plasma on contaminated human bone: an in vitro study

The use of cold atmospheric pressure plasma (CAPP) as a bacterial decontaminant for chronic wounds has shown good results. The purpose of this in vitro study was to evaluate the bactericidal effects of CAPP on the cancellous area of the bone. Sterile glass slides and processed sterile human bone allografts 1, 2, 3, and 4mm thick were used for initial contamination and further CAPP treatment. Each block was contaminated with Staphylococcus aureus suspension on one side. Each slide was turned 180° and treated on the reverse side. The bacterial count in colony-forming units (CFU) was then measured and compared with that of a control group, and the bactericidal effects of CAPP in relation to bone density evaluated. A significant reduction in count was measured between treated and untreated groups (groups A-D: p<0.01 and group E: p=0.04). A strong positive linear relation was found between bone density and the S aureus count (r=0.844, p=0.156). Treatment with CAPP had a bactericidal effect on bone structures with a penetration depth of up to 4mm. It might be used for all diseases involving infected bone, and so extends the existing range of treatments.

Blended learning modules for lectures on oral and maxillofacial surgery

Over the last couple of years, new teaching methods have been developed and implemented in German universities, but only rarely in dental schools. The aim of this project therefore was to implement students' requests for such methods to be used in dental education. In 2012, based on an analysis of both quantitative and qualitative requirements, we designed a questionnaire for quantitative analysis, and evaluated a series of lectures on oral and maxillofacial surgery. Based on our findings, we then designed a blended learning module that was gradually integrated into the series. In 2017 we again evaluated the lectures, and rated the module. The two evaluations were then compared using a two-sample z-test. The results showed that students were very satisfied with the approach. They were particularly happy with the surgical videos, which were shown during the lectures and also included in the module, as they helped them to understand the surgical technique. Our survey showed that most of the students were using the online learning program and that it was the resource they preferred. Application of a blended learning approach could satisfy the requirements of the new generation of students, and transform traditional lectures into modern, sustainable, and technology-enhanced learning experiences.

Vascularised fatty tissue: its role in prevention of the symptoms of Frey syndrome after parotidectomy

We studied 37 consecutive patients who had parotidectomies between 2008 and 2017 and who had vascular fat flaps inserted to replace the excised parotid tissue and prevent Frey syndrome. They were followed up for 1-9 years to check for the relevant symptoms. We studied 17 female and 20 male patients, mean age 52 (range 19-78) years. The flaps took a maximum of 17minutes to dissect. There was no donor site morbidity, the vascular fat flap was stable in all cases for up to nine years, and none of the patients complained of symptoms of Frey syndrome.

Evaluation of facial blood flow using three-dimensional scanning

The Vectra X3 3-dimensional face scanner allows us to visualise the erythema of superficial layers of skin in addition to its regular scanning functions. The aim of our study was to find out whether changes we provoked in the circulation of the skin would be registered and displayed by the face scanner. We measured the circulation in the skin of the cheeks of 20 volunteers with a face scanner, a laser Doppler device, and a skin pigmentation analyser before and after the application of a nitric oxide cream. The results were compared in terms of grey tones, local concentrations of haemoglobin, and erythema. All methods showed significant changes (p<0.001) before and after application of the cream. The study proved that the Vectra X3 recognises changes in skin circulation and displays them in a simple and evident way.

Maxillary advancement versus mandibular setback in class III dentofacial deformity: are there any differences in aesthetic outcomes?

A retrospective evaluation of maxillary advancement and mandibular setback in class III patients was performed and their aesthetic outcomes compared. Patients with a sella-nasion-A-point angle (SNA) of 80-84° were selected. Pre- and postoperative lateral cephalograms were obtained for 34 class III patients; these were divided into two groups according to the surgical procedure performed: mandibular setback group (n=17) and maxillary advancement group (n=17). The pre- and postoperative cervical length, lip-chin-throat angle, lower/upper lip thickness, distance from the lower/upper lip to the aesthetic line, soft tissue angle, facial contour angle, and nasolabial angle of the two groups were compared. Significant differences were observed for cervical length (P=0.0003) and sex (P=0.003) when comparing maxillary advancement with mandibular setback. Although the preoperative cervical length was similar in the two groups, it increased significantly after maxillary advancement and decreased after mandibular setback. In this study, the differences in aesthetic outcomes depending on the surgical procedure performed were considered. Some aesthetically important parameters proved to be superior after maxillary advancement when compared to mandibular setback, even with the maxilla in the normal position.

Three-layer reconstruction of lower third nasal defects using forehead flap, reversed nasolabial flap, and auricular cartilage

The reconstruction of a full-thickness defect of the distal third of the nose requires the restoration of all three anatomical layers. A practical method for three-layer reconstruction of the lower third of the nose and the long-term results of this technique are presented herein. A combined reconstruction technique was utilized, including a reverse subcutaneous pedicled nasolabial flap to restore the nasal mucosa, an auricular cartilage graft for structural support, and a forehead flap for cutaneous coverage of the defect. This technique was applied in 21 patients following the full-thickness excision of basal cell carcinoma of the lower part of the nose. All patients (12 male and nine female; mean age 59.8 years) were treated successfully and were satisfied with the aesthetic and functional outcomes. The wound had to be further revised in three cases for the correction of contour or residual deformities; however, no further complications were experienced. One patient had a wound infection and the cartilage had to be removed. The grafting procedure was repeated successfully after resolution of the infection. Donor site morbidity was unremarkable. Combined flaps from the forehead and nasolabial regions with an incorporated auricular cartilage graft can be used to reconstruct full-thickness defects of the lower third of the nose.

Effects on primary stability of three different techniques for implant site preparation in synthetic bone models of different densities

Preparation of implant sites affect the primary stability of implants that is necessary for osseointegration. We have investigated the effect on the primary stability of implants of three techniques used to prepare the site for implants in synthetic bone models of different densities. A total of 540 implants of varying diameters (3.3 (narrow), 4.1 (standard), and 4.8 (wide) mm) and lengths (8 or 12mm) were inserted into three artificial bone blocks (the density of which decreased from D2, D3, to D4), and we compared conventional, fully-guided, and condensing preparation of the site. After insertion, primary stability was measured using resonance frequency analysis. There were significant differences between conventional and condensing procedures (p <0.0001 in all cases) and between fully-guided and condensing procedures (p<0.01 in all cases), but there were no differences between fully-guided and conventional procedures when short implants were used, with a standard or wide diameter in low-density bone blocks (D3 and D4). In low-density bone blocks (D3 and D4) wide implants (4.8mm) compared with narrow (3.3mm) resulted in significantly better primary stability (p<0.0001 in all cases). Fully-guided preparation of the implant site is associated with increased primary stability, but is not an alternative to bone condensing. Use of longer or wider implants can increase primary stability, but the effect is less pronounced after bone condensing.

Corrigendum to "Heat generation and drill wear during dental implant site preparation: systematic review" [Br. J. Oral Maxillofac. Surg. 53(8) (2015) 679–689]

The authors regret D. A. Mitchell’s affiliation address was listed incorrectly in the original paper. The correct affiliation addressis: Maxillofacial Unit, Bradford Teaching Hospitals NHS Foundation Trust, St Lukes, Hospital, Little Horton Lane, Bradford,West Yorkshire, BD5 0NA, England, UK.The authors would like to apologise for any inconvenience caused.

Heat generation and drill wear during dental implant site preparation: systematic review

To identify factors that minimise damage during the drilling of sites for dental implants, we reviewed published papers on the amount of heat that is generated. We systematically searched English language studies published between January 2000 and February 2014 on MEDLINE/PubMed and found 41 articles, of which 27 related to an increase in temperature during preparation of the site. We found only basic research with a low level of evidence. Most of the studies were in vitro, and osteotomies were usually made in non-vital bone from cows or pigs. To measure heat in real time, thermocouples were used in 18 studies and infrared thermographs in 7. Three studies reported the use of immunohistochemical analysis to investigate immediate viability of cells. The highest temperature measured was 64.4°C and the lowest 28.4°C. Drill wear was reported after preparation of 50 sites, and there was a significant increase in temperature and a small change in the physiological balance of the proteins in the bone cells. Differences in the study designs meant that meta-analysis was not appropriate. For future work, we recommend the use of standard variables: an axial load of 2kg, drilling speed of 1500rpm, irrigation, standard artificial bone blocks, and the use of infrared thermography.