Comparison of three-dimensional imaging of the nose using three different 3D-photography systems: an observational study

BACKGROUND

New 3D technologies for superficial soft tissue changes, especially in plastic and reconstructive surgical procedures, can improve the planning and documentation of facial surgeries. The purpose of this study was to compare and determine the applicability and feasibility of three different 3D-photography systems in clinical practice imaging the nose.

METHODS

A total of 16 healthy non-operated noses were included in this prospective study. A plaster model of each nose was produced, digitized, and converted to a .stl mesh (= ground truth model). Three-dimensional images of each nose were then taken using Artec Space Spider (gold standard), Planmeca ProFace®, and the Bellus3D Dental Pro application. All resulting .stl files were aligned to the ground truth model using MeshLab software, and the root mean square error (RMSE), mean surface distance (MSD), and Hausdorff distance (HD) were calculated.

RESULTS

The Artec Space Spider 3D-photography system showed significantly better results compared to the two other systems in regard to RMSE, MSD, and HD (each p < 0.001). There was no significant difference between Planmeca ProFace® and Bellus3D Dental Pro in terms of RMSE, MSD, and HD. Overall, all three camera systems showed a clinically acceptable deviation to the reference model (range: -1.23-1.57 mm).

CONCLUSIONS

The three evaluated 3D-photography systems were suitable for nose imaging in the clinical routine. While Artec Space Spider showed the highest accuracy, the Bellus3D Dental Pro app may be the most feasible option for everyday clinical use due to its portability, ease of use, and low cost. This study presents three different systems, allowing readers to extrapolate to other systems when planning to introduce 3D photography in the clinical routine.

Perioperative anticoagulation in head and neck free flap reconstructions: Experience of an anticoagulative scheme and its modification

OBJECTIVES

Microvascular anastomoses in microvascular reconstructions induce rheological changes in the anastomosed vessels and are usually counteracted by anticoagulative medication. There is no regimen commonly agreed on. This study provides an easy to use anticoagulative regimen.

PATIENTS AND METHODS

Consecutive cases of either anticoagulative regimen between 2013 and 2018 that underwent microvascular reconstruction in the head and neck area were included in this retrospective study, resulting in 400 cases in total. Two different anticoagulative regimens were applied to 200 patients in each group: (a) intraoperatively administered unfractionated 5000 I.U. high molecular weight heparin (HMWH) and postoperatively low molecular weight heparin (LMWH, Enoxaparin) 1 mg/kg/body weight postoperatively and (b) intraoperatively LMWH 0.5 mg/kg/body weight as well as 12 h later and 1 mg/kg/body weight postoperatively.

RESULTS

The LMWH cohort showed fewer overall thromboembolic (8.5% vs. 11%; p = .40) and peripheral thrombotic events (1% vs. 3.5%; p = .18) and lung embolisms (3% vs. 4%; p = .59). The number of thromboses at the site of the anastomosis was equally distributed. In regard to flap-specific complications, LMWH was associated with a positive effect, in particular with respect to total flap losses (5% vs. 7%; p = .40) and wound-healing disorders (14.5% vs. 20%; p = .145).

CONCLUSION

Findings indicate that intra- and postoperatively administered LMWH as the only anticoagulative medication seems reliable in our clinical routine of head and neck free flap reconstructions.

Face the Future-Artificial Intelligence in Oral and Maxillofacial Surgery

Artificial intelligence (AI) has emerged as a versatile health-technology tool revolutionizing medical services through the implementation of predictive, preventative, individualized, and participatory approaches. AI encompasses different computational concepts such as machine learning, deep learning techniques, and neural networks. AI also presents a broad platform for improving preoperative planning, intraoperative workflow, and postoperative patient outcomes in the field of oral and maxillofacial surgery (OMFS). The purpose of this review is to present a comprehensive summary of the existing scientific knowledge. The authors thoroughly reviewed English-language PubMed/MEDLINE and Embase papers from their establishment to 1 December 2022. The search terms were (1) "OMFS" OR "oral and maxillofacial" OR "oral and maxillofacial surgery" OR "oral surgery" AND (2) "AI" OR "artificial intelligence". The search format was tailored to each database's syntax. To find pertinent material, each retrieved article and systematic review's reference list was thoroughly examined. According to the literature, AI is already being used in certain areas of OMFS, such as radiographic image quality improvement, diagnosis of cysts and tumors, and localization of cephalometric landmarks. Through additional research, it may be possible to provide practitioners in numerous disciplines with additional assistance to enhance preoperative planning, intraoperative screening, and postoperative monitoring. Overall, AI carries promising potential to advance the field of OMFS and generate novel solution possibilities for persisting clinical challenges. Herein, this review provides a comprehensive summary of AI in OMFS and sheds light on future research efforts. Further, the advanced analysis of complex medical imaging data can support surgeons in preoperative assessments, virtual surgical simulations, and individualized treatment strategies. AI also assists surgeons during intraoperative decision-making by offering immediate feedback and guidance to enhance surgical accuracy and reduce complication rates, for instance by predicting the risk of bleeding.

Effect of segmental versus marginal mandibular resection on local and lymph node recurrences in oral squamous cell carcinoma: is tumorous bone infiltration or location and resulting soft tissue recurrences a long-term problem?

PURPOSE

Oral squamous cell carcinomas (OSCCs) adjacent to the mandible or with clinically suspected bone infiltration are surgically treated either with marginal or segmental resections. This retrospective study compared both resections regarding local recurrence and lymph node recurrence or secondary lymph node metastases.

METHODS

All consecutive primary OSCC cases between January 2007 and December 2015 that underwent mandibular marginal or segmental resection were included. Rates of local and lymph node recurrences or secondary metastases and possible risk factors such as tumor localization according to Urken's classification were recorded.

RESULTS

In total, 180 patients with 85 marginal (group I) and 95 segmental (group II) mandibular resections were analyzed. The local recurrence rates were comparable between the groups (28.2% vs. 27.4%; p = 0.897). Lymph node recurrences or secondary metastases were higher in group I (9.4% (n = 8) vs. 6.2% (n = 6); p = 0.001). Tumor localization appears to affect the outcomes. Significantly fewer local and lymph node recurrences/metastases were found for Urken's classification SB and S calculated by two-proportion z-test (p = 0.014 and 0.056, respectively). Local recurrences mostly emerged from soft tissues, which should be resected more radically than the bones.

CONCLUSION

While bone infiltration appears technically well controllable from an oncologic point of view, local recurrences and lymph node recurrences/metastases remain an issue. Regular clinical aftercare with imaging is crucial to detect recurrences.

The impact of passive alveolar molding vs. nasoalveolar molding on cleft width and other parameters of maxillary growth in unilateral cleft lip palate

OBJECTIVE

Passive alveolar molding (PAM) and nasoalveolar molding (NAM) are established presurgical infant orthodontic (PSIO) therapies for cleft lip palate (CLP) patients. PAM guides maxillary growth with a modified Hotz appliance, while NAM also uses extraoral taping and includes nasal stents. The effects of these techniques on alveolar arch growth have rarely been compared.

MATERIAL AND METHODS

We retrospectively compared 3D-scanned maxillary models obtained before and after PSIO from infants with unilateral, non-syndromic CLP treated with PAM (n = 16) versus NAM (n = 13). Nine anatomical points were set digitally by four raters and transversal/sagittal distances and rotations of the maxilla were measured.

RESULTS

Both appliances reduced the anterior cleft, but NAM percentage wise more. NAM decreased the anterior and medial transversal width compared to PAM, which led to no change. With both appliances, the posterior width increased. The alveolar arch length of the great and small segments and the sagittal length of the maxilla increased with PAM but only partially with NAM. However, NAM induced a significant greater medial rotation of the larger and smaller segment compared to PAM with respect to the lateral angle.

CONCLUSIONS

NAM and PAM presented some significant differences regarding maxillary growth. While NAM reduced the anterior cleft and effectively rotated the segments medially, PAM allowed more transversal and sagittal growth.

CLINICAL RELEVANCE

The results of this study should be taken into consideration when to decide whether to use PAM or NAM, since they show a different outcome within the first few months. Further studies are necessary regarding long-term differences.

The COVID-19 pandemic and its possible impact on the treatment of odontogenic and intraoral abscesses

Most odontogenic and intraoral abscesses can be treated on an outpatient basis with local anesthesia. However, severe disease progression may require an incision under general anesthesia (GA) with postoperative inpatient treatment. This study aimed to evaluate the first "COVID-19 year" in Germany and compare the first "COVID-19 year" with the two previous years. All consecutive cases with odontogenic or intraoral abscesses treated in an outpatient or inpatient setting between 2018 and 2021 were included in this study. Data were collected, including the type of anesthesia, length of hospital stay, and healthcare costs. Despite the lower total number of abscess treatments in the first year of COVID-19 (n = 298 patients) than that in the two previous years (n = 663 patients), the number of advanced abscesses requiring intervention under GA was significantly higher (p < 0.001). This increased burden of care was also reflected in increased healthcare costs. The measures taken against the COVID-19 pandemic had an impact on the course of other diseases, for example, odontogenic and intraoral abscesses. The results showed an emerging conflict in patient care during the pandemic crisis that should be considered in possible future pandemics.

Mandibular reconstructions with free fibula flap using standardized partially adjustable cutting guides or CAD/CAM technique: a three- and two-dimensional comparison

Background

Mandibular reconstruction with the fibula free flap (FFF) is performed freehand, CAD/CAM-assisted, or by using partially adjustable resection/reconstruction aids. The two latter options represent the contemporary reconstructive solutions of the recent decade. The purpose of this study was to compare both auxiliary techniques with regard to feasibility, accuracy, and operative parameters.

Methods and materials

The first twenty consecutively operated patients requiring a mandibular reconstruction (within angle-to-angle) with the FFF using the partially adjustable resection aids between January 2017 and December 2019 at our department were included. Additionally, matching CAD/CAM FFF cases were used as control group in this cross-sectional study. Medical records and general information (sex, age, indication for surgery, extent of resection, number of segments, duration of surgery, and ischemia time) were analyzed. In addition, the pre- and postoperative Digital Imaging and Communications in Medicine data of the mandibles were converted to standard tessellation language (.stl) files. Conventional measurements - six horizontal distances (A-F) and temporo-mandibular joint (TMJ) spaces - and the root mean square error (RMSE) for three-dimensional analysis were measured and calculated.

Results

In total, 40 patients were enrolled (20:20). Overall operation time, ischemia time, and the interval between ischemia time start until end of operation showed no significant differences. No significant difference between the two groups were revealed in conventional measurements of distances (A-D) and TMJ spaces. The Δ differences for the distance F (between the mandibular foramina) and the right medial joint space were significantly lower in the ReconGuide group. The RMSE analysis of the two groups showed no significant difference (p=0.925), with an overall median RMSE of 3.1 mm (2.2-3.7) in the CAD/CAM and 2.9 mm (2.2-3.8) in the ReconGuide groups.

Conclusions

The reconstructive surgeon can achieve comparable postoperative results regardless of technique, which may favor the ReconGuide use in mandibular angle-to-angle reconstruction over the CAD/CAM technique because of less preoperative planning time and lower costs per case.

Infantile human labial glands: Distribution of aquaporins and claudins in the context of paracellular and transcellular pathways

Human labial glands consist of saliva-secreting cells which are formed by serous and predominantly mucous glandular cells. The following excretory duct system converts the isotonic saliva into a hypotonic fluid. Liquids are transported across the membrane of epithelial cells by paracellular or transcellular mode of action. We studied aquaporins (AQP) and tight junction proteins in the endpieces and duct system of human labial glands of 3-5-month-old infants for the first time. AQP1, AQP3, and AQP5 represent the transcellular transport; tight junction proteins like claudin-1, - 3, - 4, and - 7 regulate the permeability of the paracellular pathway. Specimens of 28 infants were included in this study and analyzed histologically. AQP1 was present in myoepithelial cells and in endothelial cells of small blood vessels. AQP3 showed basolateral plasmamembrane localization in glandular endpieces. AQP5 was localized at the apical cytomembrane in serous and mucous glandular cells and at the lateral membrane in serous cells. Ducts remained unstained with the antibody to AQP1, AQP3, and AQP5. Claudin-1, - 3, - 4, and - 7 were expressed mainly in the lateral plasmamembrane of serous glandular cells. In the ducts, claudin-1, - 4, and - 7 were detected at the basal cell layer, claudin-7 also at the lateral cytomembrane. Our findings provide new insights into the localization of epithelial barrier components necessary for regulating saliva-modification in infantile labial glands.

In-House, Open-Source 3D-Software-Based, CAD/CAM-Planned Mandibular Reconstructions in 20 Consecutive Free Fibula Flap Cases: An Explorative Cross-Sectional Study With Three-Dimensional Performance Analysis

Background

Mandibular reconstruction is conventionally performed freehand, CAD/CAM-assisted, or by using partially adjustable resection aids. CAD/CAM-assisted reconstructions are usually done in cooperation with osteosynthesis manufacturers, which entails additional costs and longer lead time. The purpose of this study is to analyze an in-house, open-source software-based solution for virtual planning.

Methods and Materials

All consecutive cases between January 2019 and April 2021 that underwent in-house, software-based (Blender) mandibular reconstruction with a free fibula flap (FFF) were included in this cross-sectional study. The pre- and postoperative Digital Imaging and Com munications in Medicine (DICOM) data were converted to standard tessellation language (STL) files. In addition to documenting general information (sex, age, indication for surgery, extent of resection, number of segments, duration of surgery, and ischemia time), conventional measurements and three-dimensional analysis methods (root mean square error [RMSE], mean surface distance [MSD], and Hausdorff distance [HD]) were used.

Results

Twenty consecutive cases were enrolled. Three-dimensional analysis of preoperative and virtually planned neomandibula models was associated with a median RMSE of 1.4 (0.4–7.2), MSD of 0.3 (-0.1–2.9), and HD of 0.7 (0.1–3.1). Three-dimensional comparison of preoperative and postoperative models showed a median RMSE of 2.2 (1.5–11.1), MSD of 0.5 (-0.6–6.1), and HD of 1.5 (1.1–6.5) and the differences were significantly different for RMSE (p < 0.001) and HD (p < 0.001). The difference was not significantly different for MSD (p = 0.554). Three-dimensional analysis of virtual and postoperative models had a median RMSE of 2.3 (1.3–10.7), MSD of -0.1 (-1.0–5.6), and HD of 1.7 (0.1–5.9).

Conclusions

Open-source software-based in-house planning is a feasible, inexpensive, and fast method that enables accurate reconstructions. Additionally, it is excellent for teaching purposes.

Comparison between Different Perforator Imaging Modalities for the Anterolateral Thigh Perforator Flap Transfer: A Prospective Study

BACKGROUND

 Perforator imaging is routinely performed before perforator flap harvest. Hand-held Doppler (hhD) and color duplex ultrasonography (CDU) are currently the most popular radiation-free methods for this purpose that can be applied by the surgeon alone. The aim of this study was to compare the accuracy, reliability, and feasibility of hhD and CDU with indocyanine green angiography (ICGA) in the anterolateral thigh perforator flap (ALTPF).

METHODS

 All consecutive ALTPF procedures between May 2017 and April 2018 were included in this prospective study. The perforators were visualized by three investigators independently and randomized, applying hhD, CDU, and ICGA. The presence and the distance to the identified perforator were registered. Further, body mass index (BMI), American Society of Anesthesiologists-status, and the patient's history regarding smoking, alcohol use, and diabetes mellitus were registered alongside gender and age to analyze possible confounders.

RESULTS

 A total of 12 patients were enrolled with a median age of 67 (52-87) years. In total, 30 perforators were detected intraoperatively as well as with the ICGA. The latter visualized the perforators significantly more precisely than hhD and CDU (p < 0.001 and p = 0.001). The sensitivity and positive predictive value were 67 and 62% for hhD, 73 and 64% for CDU, and 100 and 100% for ICGA, respectively.

CONCLUSION

 According to this study, ICGA visualized perforators more accurately than the standard methods hhD and CDU. Further, it was associated with the highest sensitivity and positive predictive value. ICGA consistently delivered excellent results, whereas hhD and CDU showed variability.

Identifying perioperative volume-related risk factors in head and neck surgeries with free flap reconstructions - An investigation with focus on the influence of red blood cell concentrates and noradrenaline use

INTRODUCTION

The amount of fluids administered intraoperatively seems to influence the postoperative outcome, and especially the transfusion of red blood cell concentrates (RBC) are known to have an increased risk of postoperative complications. This prospective study focuses on patients planned with microvascular free flap reconstruction and investigates the effect of various types and amounts of volumes given intraoperatively and on the intensive care unit with regard to overall postoperative complications.

MATERIAL AND METHODS

In this prospective study, 52 consecutive patients planned for reconstruction with microvascular free flaps were included. Intraoperatively administered volumes including blood products were documented by the anesthesiologists as well as volumes given during the intensive care unit stay. Postoperative complications were registered for the entire hospital stay. Statistical analysis was carried out correlating the amount and type of volumes with the incidence of postoperative complications.

RESULTS

The intraoperative use of RBC showed a close to statistically significant increased risk of postoperative complications (mean/SD concentrates: 0.5/1.1 [no complications] vs. 1.0/1.4 [complications], p = 0.058). In a multivariate analysis with stepwise selection the use of human albumin, gelatin, or Ringer's acetate showed no correlation with complications. The overall blood loss, however, had no significant influence on the incidence of complications (mean/SD ml: 1187/761 [no complications] vs. 1004/600 [complications], p = 0.37). The use of noradrenalin during reconstructive surgeries with microvascular flaps bears statistically no increased risk of failure (mean/SD μg/kg/min: 36/23 [no flap loss] vs. 22/15 [flap loss], p = 0.289) or complications (mean/SD μg/kg/min: 34/22 [no complications] vs. 35/23 [complications], p = 0.807).

CONCLUSION

In our investigation, the use of crystalloids and colloids seems to have no influence on the postoperative outcome, but the use of RBC may have an increased overall incidence of postoperative complications. A careful hemostasis to limit the use of RBC remains essential despite available options of substitutions. The use of infusion-pump-administered noradrenaline seems valuable to sustain a stable circulation during surgeries with microvascular free flaps and may have no negative impact on postoperative complications.

Simultaneous, radiation-free registration of the dentoalveolar position and the face by combining 3D photography with a portable scanner and impression-taking

Objectives

Simultaneous, radiation-free registration of the teeth and the upper and lower jaw positions in relation to the extraoral soft tissue could improve treatment planning and documentation. The purpose of this study is to describe a workflow to solve this form of registration and surface acquisition with a mobile device.

Methods

Facial scans of ten healthy participants were taken using a blue-light LED 3D scanner (Artec® Space Spider; Artec® Group; Luxembourg). An impression of the maxillary dentoalveolar arch was taken simultaneously to the 3D photo using a modified impression tray with two different extraoral registration geometries (sphere vs. cross). Following, an impression of the mandibular dentoalveolar arch was taken once. Both impressions were scanned with the 3D scanner. All resulting standard tesselation language (.stl) files of the geometries were compared to the original, virtual .stl files and the root mean square errors (RMSE) were calculated for each surface (Artec Studio 13 Professional × 64; Artec® Group; Luxembourg) to determine which geometry serves as a better reference for intra-extraoral registration.

Results

The RMSE between the original geometries and the scanned counterfeits were statistically lower for spherical geometries (p < 0.008). Once scanned and aligned, both geometries enabled an alignment of the intra- and extraoral scan. However, the spherical geometries showed virtually better results without significance (p = 0.70).

Conclusions

The presented study provides a radiation-free solution for simultaneous dentoalveolar correlations in relation to the extraoral soft tissue. Spherical geometries achieved more precise and easier intra-extraoral alignments using the applied mobile 3D scanner and workflow.

The absolute and relative effects of presurgical nasoalveolar moulding in bilateral cleft lip and palate patients compared with nasal growth in healthy newborns

BACKGROUND

This study investigated the efficiency of nasoalveolar moulding (NAM) in patients presenting with bilateral cleft lip and palate (BCLP). It focused explicitly on nasal outcome and therefore made comparisons with healthy age-matched infants with normal nasal development.

METHODS

Nasal impressions from 19 BCLP patients were analysed at the beginning and at the end of NAM treatment. In addition, nasal impressions from 32 healthy newborns were taken monthly for 4 months. The casts were digitalized and analysed, using defined anatomic landmarks, by two independent observers. Initial values were compared with outcome parameters at the end of NAM therapy and with the healthy cohort.

RESULTS

NAM significantly elongated the columella in BCLP patients, with an increase of 106.5% versus 14.5% in healthy newborns. Nostril height showed significant expansion from 4.2 mm to 5.6 mm on the right side, and from 4.3 mm to 6.2 mm on the left side.

CONCLUSION

NAM significantly elongated columella length and increased nostril height. The comparison with healthy newborns showed the effectiveness of early cartilage moulding. Detailed knowledge about absolute and relative early nasal growth was gained. However, despite highly effective NAM treatment in BCLP, nasal dimensions will not reach healthy proportions.

Prenatal intrauterine maxillary development - An evaluation with three-dimensional ultrasound

OBJECTIVES

The aim of this prospective study was to investigate normal fetal maxillary development with volume ultrasound during the prenatal phase, for a better estimation of maxillary growth processes.

METHODS

Some 210 3D volumes were obtained in two measurement series from 38 healthy women (gestational age: 19⁺² to 31⁺⁴ weeks) using a GE Voluson™ E10 ultrasound system. Maxillary length and width were determined in the axial and sagittal planes. Clearly defined, reproducible landmarks were used for measurements. The results were correlated with gestational age and compared with previously reported studies.

RESULTS

Total maxillary length ranged from 10.30 to 24.75 mm, total maxillary width from 13.65 to 37.30 mm in an observation period during the second trimester, with high reproducibility for all landmarks. All evaluation results showed steep growth with exponential character. Length growth was determined to be more dominant than width growth. Intra-rater correlation was evaluated to be almost perfect (ICC (3) > 0.8).

CONCLUSION

This study presents measurements of physiological fetal maxillary development. The defined landmarks proved to be representative for further investigations. This study serves as a baseline for a better understanding of fetal maxillary growth processes, and may be useful for standardising detection of malformations or intrauterine growth restrictions.

Facilitating CAD/CAM nasoalveolar molding therapy with a novel click-in system for nasal stents ensuring a quick and user-friendly chairside nasal stent exchange

Nasoalveolar molding (NAM) aims to improve nasal symmetry with a nasal stent in cleft lip and palate (CLP) patients. When plates have to be exchanged because of dentoalveolar growth or cleft reduction, the nasal stent has to be mounted onto a new plate. This procedure elongates visiting hours for patients and parents or requires second treatment sessions. This study introduces a quick-lock additive manufacturing solution for chairside nasal stent exchange called RapidNAM. A novel taping retention pin has been designed that enables nasal stent insertion. Patients with unilateral CLP were included in this study. Plaster models were digitalized and measured by two independent observers. Two methods of CAD/CAM-molding therapies were compared: (i) conventional adhesion of a nasal stent (CAD/CAM NAM); (ii) quick-lock system in which the nasal stent was transferred to another plate (RapidNAM). CAD/CAM NAM and its refinement RapidNAM significantly increased the cleft-side nasal height and tilted the nose towards symmetry. The quick-lock system minimizes wire adaptations, since the pre-existing stent can be reused. The new nasal stent development seems a feasible solution to minimize visiting hours but with clinically satisfactory results. This new nasal stent system combines traditional elements of NAM with CAD/CAM-technology.

A semi-automated virtual workflow solution for the design and production of intraoral molding plates using additive manufacturing: the first clinical results of a pilot-study

Computer-aided design and computer-aided manufacturing (CAD/CAM) technology has been implemented in the treatment of cleft lip and palates (CLP) by several research groups. This pilot study presents a technique that combines intraoral molding with a semi-automated plate generation and 3D-printing. The clinical results of two intraoral molding approaches are compared. This is the first clinical investigation of semi-automated intraoral molding. Our study included newborns with unilateral CLP. Plaster models were digitalized and measured by two independent observers. Two methods of CAD/CAM-assisted intraoral molding were compared: (i) stepwise manual design of molding plates (conventional CAD/CAM-intraoral molding) and (ii) a semi-automated approach with an automated detection of alveolar ridges (called RapidNAM) assisted by a graphical user interface (GUI). Both approaches significantly narrowed the clefts and resulted in a harmonic alveolar crest alignment. The GUI was easy to use and generated intraoral molding devices within minutes. The presented design solution is an efficient technical refinement with good clinical results. The semi-automated plate generation with a feasible GUI is fast but allows individual adaptations. This promising technique might facilitate and foster the more widespread use of CAD/CAM-technology in intraoral molding therapy.

The possibilities of a portable low-budget three-dimensional stereophotogrammetry system in neonates: a prospective growth analysis and analysis of accuracy

Background

With the technical development, portable three-dimensional (3D) photogrammetry systems are becoming more en vogue because of cost-effectiveness and comparable accuracy to common stationary 3D systems. The purpose of the study was to evaluate the feasibility and accuracy of a low-budget portable system for 3D image acquisition with special regard to the gracile nasal region in neonates. Furthermore, the study aimed to establish a 3D data set of the first 180 days post partum.

Methods

Thirty-three healthy, full-term newborn were enrolled and 3D photographs were prospectively taken monthly with a portable low-budget 3D stereophotogrammetry system (FUEL3D® SCANIFY®) for six months. In the third month, age-matched and corresponding 3D models were acquired by taking an impression of the perinasal area. The resulting plaster models were scanned (3Shape D700, 3Shape® A/S, Denmark). Three examiners analyzed independently 21 defined landmarks of the generated Standard Tessellation Language files with regard to accuracy by using 3dMDvultus™ software. A semi-automatic 3D best-fit analysis of 3D photo and plaster models were performed by using Geomagic® and the Root Mean Squared (RMS) errors were calculated.

Results

Statistically significant changes of midfacial distances and angles with a focus on nasal growth during the first 180 days postpartum could be specified in absolute and relative dimensions. Best-fit analysis in the third month revealed a RMS error of 0.72 ± 0.22 mm with a mean standard deviation of 0.71 ± 0.21 mm.

Conclusions

The analyzed portable 3D stereophotogrammetry system is a feasible methodology with good accuracy, even in newborn. A description of the growth as well as the establishment of a 3D data set was performed. Its implementation for basic documentation for example in cleft patients is possible and might reduce the need for impressions and facilitate the communications with parents and the interdisciplinary team.

Evaluation of a portable low-budget three-dimensional stereophotogrammetry system for nasal analysis

BACKGROUND

Three-dimensional (3D) photogrammetry has reached high standards and accuracy but is mainly conducted with stationary and expensive systems. The purpose of this study was to evaluate the accuracy of a low-budget portable system with special regard to the gracile and challenging nasal region.

MATERIAL AND METHODS

3D models of the perinasal area were acquired by impression-taking and the scanning of the generated plaster models (3Shape D500) or with a portable low-budget 3D stereophotogrammetry (FUEL3D^® SCANIFY^®) system. Four examiners analysed defined landmarks of the generated Standard Tessellation Language files with regard to accuracy and interobserver reliability by using 3dMDvultus™ software. A semi-automatic 3D best-fit analysis of both models was performed by using Geomagic^® and the Root Mean Squared (RMS) errors were calculated.

RESULTS

41 volunteers were included, with 22 perinasal and perioral landmarks, 15 3D distances and eight 3D angles being analysed per data set. In a point-based analysis the mean spreads were partially smaller in the plaster model scans. Most measurements showed very high (>0.8) to excellent (>0.9) intraclass correlation coefficients, the lowest being found for columella length (0.686) and left nostril width (0.636). Overall, the mean RMS error between the superimposed surfaces was 0.89 ± 0.22 mm in the best-fit analysis.

CONCLUSIONS

The corresponding software program was operator-friendly. The findings indicate that the analysed, affordable and portable system is a feasible solution for 3D image acquisition with comparable accuracy reported in the literature. Further studies will analyse the feasibility in neonates.

Establishment of a finite element model of a neonate's skull to evaluate the stress pattern distribution resulting during nasoalveolar molding therapy of cleft lip and palate patients

Nasoalveolar Molding (NAM) is associated with ambivalent acceptance regarding effectiveness and unknown long-term results. Our purpose was to analyze the stress distribution patterns within the viscero- and neurocranium of neonates during the first phase of NAM therapy. A finite element (FE) model of a healthy four-week-old neonate was generated, derived from a computed tomography scan allowing the implementation of a bone-density-dependent material model. The influence of dental germs with variable material properties, the cleft width and area of expected force application were analyzed in a worst-case scenario. The resulting stress distribution patterns for each situation were analyzed using the software Ansys APDL. The established FE model was verified with a convergence analysis. Overall, stress patterns at the age of four weeks showed von Mises stress values below 60.000 Pa in the viscero- and neurocranium. The influences of the allocation of material properties for the dental germs, the area of force application, and the cleft width were negligible. A workflow to simulate the stress distribution and deformation in neonates attributable to various areas of force application has been established. Further analyses of the skulls of younger and older neonates are needed to describe the stress distribution patterns during NAM therapy.