In vitro measurement of the retention force of two stud attachment systems during cyclic load.

PURPOSE: To investigate the retentive behavior of the Locator legacy and Novaloc attachment systems with different retention inserts both within and across systems under cyclic load. MATERIALS AND METHODS: Three retention inserts of each system (green, yellow, and white for Novaloc; green, orange, and red inserts for extended range for legacy Locator) were tested on abutments of both systems with a sample number of 10 per force and 10,000 cycles of insertion and removal. The loading was applied in the axial direction of the abutments, which were placed in artificial saliva. The retention force was measured in each cycle. The results were compared with the manufacturer's specifications and evaluated for a simulated period of use of 10 years. Characteristic time constants were determined, and subsequently, the two systems were compared regarding their wear behavior. RESULTS: The manufacturer's specifications could only be confirmed for the green Novaloc retention insert on a Novaloc abutment (t-test: p = 0.50); for all other inserts, the baseline exceeded the manufacturer's specifications by 30%-75% (Novaloc; t-test: p < 0.001) and 75%-550% (Locator; t-test: p < 0.001). After 10,000 cycles performed, the manufacturer's specifications were confirmed on a Novaloc abutment for the white Novaloc retention insert (t-test: p = 0.86) and on a Locator abutment for the green Novaloc retention insert (t-test: p = 0.32). Both systems lost retention force during the experiment. Overall, Novaloc inserts on both abutments showed less wear (decrease to 56%-85% of initial force) and a slower decrease in retention force compared to Locator inserts (decrease to 6%-31% of initial force). CONCLUSIONS: In both systems, wear leads to a varying loss of retention; therefore, regular checks with possible replacement of the inserts are necessary in clinical use. Novaloc attachments seem to be more resistant to the loss of retention than Locator attachments. A cross-combination may be clinically useful in some cases.

Comparison of the Accuracy of a Mounting Fixture for Dental Implants for Implant Position Transfer and Open-Tray Implant Level Impression-An In Vitro Study.

The accuracy for the implant position transfer of a mounting fixture and a standardized open-tray implant level impression was compared. Ten aluminum master models with four implant analogs placed in different angulations were fabricated. By performing an open-tray implant level impression stone casts were produced. The master models and stone casts were scanned (comparison group one) using a laboratory scanner. Deviations in the scan body surface were determined in the form of mean (absolute) point distances and (signed) surface distances. The same procedure was performed with a screwed transfer and by fixing the posts of the mounting fixture (comparison group two). The mounting device was applied to each master model and scanned in a fixed and detached state (comparison group three). In a point comparison, the open-tray implant level impression showed mean deviations of 43.6 µm and a mounting fixture of 44.6 µm with no significant differences (p < 0.05). There were significant differences between groups two and three. The angulation of the implants had no effect on the accuracy. In a surface comparison, the open-tray implant level impression showed mean deviations of 36.0 µm and a mounting fixture of 2.0 µm (p > 0.05). Within the limits of this study, the mounting fixture transferred the implant position with the same accuracy as the open-tray implant level impression with respect to point deviations.

Artifacts in magnetic resonance imaging of the head and neck: Unwanted effects caused by implant-supported restorations fabricated with different alloys.

STATEMENT OF PROBLEM: Implant-supported restorations may cause artifacts in magnetic resonance imaging (MRI) of the head and neck area. However, the effect of different alloys remains unclear. PURPOSE: The purpose of this in vitro study was to assess artifacts in head and neck MRI caused by implant-supported restorations with different alloys. MATERIAL AND METHODS: Three dry mandibles were prepared to receive bilateral dental implants at the second premolar and second molar sites. Different alloy combinations were evaluated: titanium implants+cobalt chromium restorations; titanium-zirconium implants+cobalt chromium restorations; and zirconia implants+ceramic restorations. Specimens were imaged by using a 3-Tesla magnetic resonance scanner system (Achieva 3.0T TX; Philips GmbH) with a turbo-spin-echo sequence. Scan protocols were adjusted to optimize metal artifact reduction and shorten scan time. Artifact volumes were assessed and statistically analyzed by using the Kruskal-Wallis and Spearman tests (α=.05). RESULTS: A statistically significant difference was found among artifact volume caused by different materials (P=.002). The presence of titanium alloy was correlated with the artifact volume (r=-.87). Artifacts were greater for titanium and fewer for titanium-zirconium alloys, whereas zirconia implants found only minimal artifacts. CONCLUSIONS: The dimension of artifacts produced by implant-supported restorations varied according to the material.

Cross Sectional Analysis of Eurasian Skull Anatomy for 3D Cephalometry-Normative Data Reveal Four Different Skull Types.

The unsolved problem in three-dimensional surgical planning for patients with facial deformity, dysgnathia, or asymmetry is the lack of a normative database of "norm skulls" that can be used as treatment objectives. A study was conducted on 90 Eurasian persons (46 male and 44 female adults) for whom cone beam-computed tomography images were available. Inclusion criteria were adult patients with a skeletal Class I pattern, proper interincisal relationship with normal occlusion, the absence of an open bite both in the anterior and posterior region, and a normal and balanced facial appearance; patients with dysgnathia and malformations were excluded. A total of 18 landmarks were digitized and 3D cephalometric measurements were performed and analyzed by means of proportions calculated from the landmarks. Male and female skulls were analyzed, as well as subdivisions revealed by cluster analysis. The data showed that four subtypes of skulls were distinguishable with statistical significance (p < 0.05). A male and a female type subdivided in a brachiocephalic and dolichocephalic phenotype could be identified. For each type, a mean shape was calculated by a Procrustes transformation, which, in turn, was used to create four template skulls from a male and a female skull. This was accomplished by fitting the polygon models of the two skulls to each of the two subtypes based on the landmarks marked on them using a thin plate spline transformation. The normative data of the subtypes can individually serve as a guide for orthodontic surgery in the Eurasian population, which is especially helpful in 3D planning and the execution of craniofacial operations.

A systematic review: facial, dental and orthodontic findings and orofacial diagnostics in patients with FASD.

Background: The fetal alcohol spectrum disorder is a group of developmental disorders caused by maternal alcohol consumption. Patients with fetal alcohol syndrome show abnormal orofacial features. This review presents an overview over the facial, oral, dental or orthodontic findings and diagnostic tools concerning these features. Methods: For this systematic review Cochrane, Medline and Embase databases were considered and the review was performed according to the PRISMA checklist. Two independent reviewers evaluated all studies and recorded results in a summary of findings table. Risk of bias was analyzed via Quadas-2 checklist. Results: 61 studies were eligible for inclusion. All included studies were clinical studies. Methods and results of the studies were not comparable, guidelines or methods for the detection of FASD varied across studies. Facial features most often measured or found as distinguishing parameter were: palpebral fissure length, interpupillary or innercanthal distance, philtrum, upper lip, midfacial hypoplasia or head circumference. Conclusions: This review shows that to date a multitude of heterogeneous guidelines exists for the diagnosis of FASD. Uniform, objective diagnostic criteria and parameters for the orofacial region in FASD diagnosis are needed. A bio database with values and parameters for different ethnicities and age groups should be made available for diagnosis.

The Position of the Virtual Hinge Axis in Relation to the Maxilla in Digital Orthognathic Surgery Planning-A k-Means Cluster Analysis.

The aim of this study was to investigate a possible relation between skeletal phenotypes and virtual mounting data in orthognathic surgery patients. A retrospective cohort study including 323 female (26.1 ± 8.7 years) and 191 male (27.9 ± 8.3 years) orthognathic surgery patients was conducted. A k-means cluster analysis was performed on the mounting parameters: the angle α between the upper occlusal plane (uOP) and the axis orbital plane (AOP); the perpendicular distance (AxV) from the uOP to the hinge axis; and the horizontal length (AxH) of the uOP from upper incisor edge to AxV, with subsequent statistical analysis of related cepalometric values. Three clusters of mounting data were identified, representing three skeletal phenotypes: (1) balanced face with marginal skeletal class II or III and α=8∘, AxV = 36 mm and AxH = 99 mm; (2) vertical face with skeletal class II and α=11∘, AxV = 27 mm and AxH = 88 mm; (3) horizontal face with class III and α=2∘, AxV = 36 mm and AxH = 86 mm. The obtained data on the position of the hinge axis can be applied to any digital planning in orthognathic surgery using CBCT or a virtual articulator, provided that the case can be clearly assigned to one of the calculated clusters.

Conformity between Pacifier Design and Palate Shape in Preterm and Term Infants Considering Age-Specific Palate Size, Facial Profile and Lip Thickness.

This retrospective case-control study is the first to examine the spatial conformity between pacifiers and palates in 39 preterm infants (12 females, 27 males) and 34 term infants (19 females, 15 males), taking into account the facial-soft-tissue profile and thickness. The shape of 74 available pacifiers was spatially matched to the palate, and conformity was examined using width, height, and length measurements. In summary, the size concept of pacifiers is highly variable and does not follow a growth pattern, like infant palates do. Pacifiers are too undersized in width, length, and height to physiologically fit the palate structures from 0 to 14 months of age. There are two exceptions, but only for premature palates: the palatal depth index at 9−11 months of age, which has no clinical meaning, and the nipple length at <37 weeks of age, which bears a resemblance to the maternal nipple during non-nutritive sucking. It can be concluded that the age-size concept of the studied pacifiers does not correspond to any natural growth pattern. Physiologically aligned, pacifiers do not achieve the age-specific dimensions of the palate. The effects attributed to the products on oral health in term infants cannot be supposed.

In Vivo Accuracy of a New Digital Planning System in Terms of Jaw Relation, Extent of Surgical Movements and the Hierarchy of Stability in Orthognathic Surgery.

This retrospective cohort study compares the virtual planned and postoperative jaw positions in patients undergoing orthognathic surgery. Surgery was virtually planned with the Digital Münster Model Surgery system (DMMS). Primary outcome: Spatial difference in the maxillo-mandibulo relation between virtual planning and postoperative result. Secondary outcome: Possible relationship between the measured differences and surgical movements as well as the postoperative stability according to Proffit. Ninety female and sixty-one male patients were included in the study. The average translation errors were 0.54 ± 0.50 mm (anteroposterior), 0.37 ± 0.33 mm (mediolateral), and 0.33 ± 0.28 mm (superoinferior). Orientation errors were 0.86 ± 0.79 degrees (yaw), 0.54 ± 0.48 degrees (roll), and 0.90 ± 0.72 degrees (pitch). The surgical procedures do not differ with respect to their error sizes. Maxilla forward and class II maxilla up with mandible forward are the most precise procedures. Most significant differences were found in the anteroposterior direction, whereby the extent of the surgical movement has no effect on the magnitude of the error. The process of planning with the DMMS followed by surgery is highly accurate and shows error values well below the clinically accepted limit of two millimeters in translation and four degrees in rotation.

Simplifying Diagnosis of Fetal Alcohol Syndrome Using Machine Learning Methods.

INTRODUCTION: The fetal alcohol spectrum disorder (FASD) is a complex and heterogeneous disorder, caused by gestational exposure to alcohol. Patients with fetal alcohol syndrome (FAS-most severe form of FASD) show abnormal facial features. The aim of our study was to use 3D- metric facial data of patients with FAS and identify machine learning methods, which could improve and objectify the diagnostic process. MATERIAL AND METHODS: Facial 3D scans of 30 children with FAS and 30 controls were analyzed. Skeletal, facial, dental and orthodontic parameters as collected in previous studies were used to evaluate their value for machine learning based diagnosis. Three machine learning methods, decision trees, support vector machine and k-nearest neighbors were tested with respect to their accuracy and clinical practicability. RESULTS: All three of the above machine learning methods showed a high accuracy of 89.5%. The three predictors with the highest scores were: Midfacial length, palpebral fissure length of the right eye and nose breadth at sulcus nasi. CONCLUSIONS: With the parameters right palpebral fissure length, midfacial length and nose breadth at sulcus nasi, machine learning was an efficient method for the objective and reliable detection of patients with FAS within our patient group. Of the three tested methods, decision trees would be the most helpful and easiest to apply method for everyday clinical and private practice.

Assessment of facial and cranial symmetry in infants with deformational plagiocephaly undergoing molding helmet therapy.

OBJECTIVES: The aim of this study was to determine the effects on facial and cranial symmetry through molding helmet therapy in infants with positional plagiocephaly. A 3D asymmetry index (3DAI), which measures both cranial and facial symmetry, was introduced and compared to the Cranial Vault Asymmetry Index (CVAI). MATERIAL & METHODS: Optical 3D-scans of children with positional plagiocephaly were evaluated retrospectively. Pre- and post-therapeutic asymmetry values of the cranium and face were determined and paired t-tests were applied. Pearson correlations were calculated for facial and cranial asymmetries. RESULTS: 65 children (age: 3-6 months) were included. Asymmetry values (mean/standard deviation, pre- and post-therapeutic) were for 3DAI determinations: cranium: 9.96/1.84-8.11/1.74 p < 0.001; face: 4.70/1.06-3.89/0.91 p < 0.001; and for CVAI measurements: 9.10/3.29-5.88/2.78 p < 0.001. No correlation was found between facial and cranial asymmetry (p > 0.05). CONCLUSION: Symmetry values improved significantly in post therapeutic 3D-scans for both asymmetry indices. The analysis of cranial symmetry by 3DAI should be preferred over the CVAI because it gives more comprehensive information, including the symmetry of the entire cranial surface and the face.

3D-printed Surgical Training Model Based on Real Patient Situations for Dental Education.

Background: Most simulation models used at university dental clinics are typodonts. Usually, models show idealized eugnathic situations, which are rarely encountered in everyday practice. The aim of this study was to use 3D printing technology to manufacture individualized surgical training models for root tip resection (apicoectomy) on the basis of real patient data and to compare their suitability for dental education against a commercial typodont model. Methods: The training model was designed using CAD/CAM (computer-aided design/computer-aided manufacturing) technology. The printer used to manufacture the models employed the PolyJet technique. Dental students, about one year before their final examinations, acted as test persons and evaluated the simulation models on a visual analogue scale (VAS) with four questions (Q1-Q4). Results: A training model for root tip resection was constructed and printed employing two different materials (hard and soft) to differentiate anatomical structures within the model. The exercise was rated by 35 participants for the typodont model and 33 students for the 3D-printed model. Wilcoxon rank sum tests were carried out to identify differences in the assessments of the two model types. The alternative hypothesis for each test was: "The rating for the typodont model is higher than that for the 3D-printed model". As the p-values reveal, the alternative hypothesis has to be rejected in all cases. For both models, the gingiva mask was criticized. Conclusions: Individual 3D-printed surgical training models based on real patient data offer a realistic alternative to industrially manufactured typodont models. However, there is still room for improvement with respect to the gingiva mask for learning surgical incision and flap formation.

Asymmetry-index and orthodontic facial analysis of children with foetal alcohol syndrome using 3D-facial scans.

BACKGROUND: The foetal alcohol spectrum disorder (FASD) is a complex and heterogenic disorder, caused by gestational exposure to alcohol. Patients with foetal alcohol syndrome (FAS-most severe form) show abnormal facial features. Our study aims at finding additional reliable and objective parameters for FAS diagnosis. METHODS: Facial three-dimensional scans of 30 children with FAS and 30 controls were analysed. Orthodontic profile analysis (concerning position of upper and lower jaw) was performed. Vertical facial proportions were taken and facial asymmetry index (right to left side) was calculated. RESULTS: Profile type was significantly different for children with FAS (p = 0.001) with lower jaws more frequently in a retral position. Profile angle was significantly larger in the group with FAS (p = 0.009). Children with FAS had shorter middle thirds and longer lower thirds of the face (p < 0.001). Stomion (point between upper and lower lip) was located significantly more caudally in the FAS group (p < 0.001). Facial asymmetry index was not significantly different. CONCLUSIONS: Children with FAS differ significantly from controls in vertical and sagittal facial measurements. Profile analysis and measurement of vertical proportions are easy to apply standard procedures in everyday orthodontic practice and could be time-saving and objective means for additional verification of FAS.

Children with Fetal Alcohol Syndrome (FAS): 3D-Analysis of Palatal Depth and 3D-Metric Facial Length.

Background: Drinking alcohol during pregnancy can result in severe developmental disorders in the child. Symptoms of the fetal alcohol spectrum disorder (FASD) comprise growth deficiencies, abnormal facial phenotype and damage or dysfunction of the central nervous system. Numerous diagnostic methods for facial phenotyping in FASD exist, but diagnoses are still difficult. Our aim was to find additional and objective methods for the verification of FAS(D). Methods: Three-dimensional dental models of 60 children (30 FAS and 30 controls) were used to metrically determine maximum palatal depths at the median palatine raphe. Three-dimensional facial scans were taken, and vertical distances of the face were measured at five defined facial landmarks (FP1-FP5) for each child. Results: Mean palatal height, total facial length (FP1-FP5) as well as FP4-FP5 did not significantly differ between the FAS group and the control group. Comparing vertical facial subdivisions, however, resulted in significant differences for distances FP1 to FP2 (p = 0.042, FAS > controls), FP2 to FP3 (p < 0.001, FAS < controls), FP3 to FP4 (p < 0.001, FAS > controls) and FP3 to FP5 (p = 0.007, FAS > controls). Conclusions: Metric vertical measurements of the face can be used as additional objective criteria for FAS diagnoses. However, no significant differences were reported for palatal depth evaluation in the specific age range tested in the present study.

Tooth Malformations, DMFT Index, Speech Impairment and Oral Habits in Patients with Fetal Alcohol Syndrome.

Background: Fetal alcohol spectrum disorder (FASD) is a developmental disorder with severe negative lifetime consequences. Although knowledge about the harmfulness of alcohol consumption during pregnancy has spread, the prevalence of fetal alcohol spectrum disorder is very high. Our study aims at identifying fetal alcohol syndrome (FAS)-associated dental anomalies or habits, which need early attention. Methods: Sixty children (30 FAS; 30 controls) were examined prospectively. Swallowing pattern, oral habits, breastfeeding, speech therapy, ergotherapy, physiotherapy, exfoliation of teeth, DMFT (decayed, missing, filled teeth) index, modified DDE (developmental defects of enamel) index and otitis media were recorded. Results: Swallowing pattern, exfoliation of teeth, and otitis media were not significantly different. Significant differences could be found concerning mouthbreathing (p = 0.007), oral habits (p = 0.047), age at termination of habits (p = 0.009), speech treatment (p = 0.002), ergotherapy, physiotherapy, and breastfeeding (p ≤ 0.001). DMFT (p ≤ 0.001) and modified DDE (p = 0.001) index showed significantly higher values for children with fetal alcohol syndrome. Conclusions: Children with fetal alcohol syndrome have a higher need for early developmental promotion such as speech treatment, ergotherapy, and physiotherapy. Mouthbreathing, habits, and lack of breastfeeding may result in orthodontic treatment needs. High DMFT and modified DDE indexes hint at a higher treatment and prevention need in dentistry.

3D-Analysis of Mouth, Nose and Eye Parameters in Children with Fetal Alcohol Syndrome (FAS).

Background: Fetal alcohol spectrum disorder (FASD) is a developmental disorder with severe negative lifetime consequences for the affected person. Numerous diagnostic methods for facial assessment in FAS exist, but most of them are based on subjective evaluations. Our aim was therefore to find objective methods for the verification of FAS(D). Methods: 58 children (28 FAS; 30 controls) were examined prospectively. 3D facial scans were performed for each child and facial parameters at the mouth, nose and eye regions were measured and compared between the groups. Results: Significant differences could be found for the distance between right and left sulcus nasi at the transition point to the philtrum (p < 0.001), for the inner canthal distance (p = 0.001) as well as for the right and left palpebral fissure length (p < 0.001). No significant difference between the FAS and control children could be found for the measurements of mouth breadth (p = 0.267) and breadth between the left and right alares nasi (p = 0.260). Conclusions: Measurements of mouth breadth and nose breadth for the alares nasi are not suitable for FAS diagnosis. In contrast, digital contactless measurements of the distance between the right and left sulcus nasi at the transition point to the philtrum, as well as the inner canthal distance and palpebral fissure length of the left and right eyes, showed significant differences when comparing children with FAS to healthy controls. These measurements could thus be additional objective means for the verification of FAS.

Facial and midfacial symmetry in cleft patients: Comparison to non-cleft children and influence of the primary treatment concept.

PURPOSE: Patients with cleft lip, alveolus and palate (CLAP) may suffer from marked asymmetry with an impact on attractiveness and psychosocial aspects. The aim of this study was to assess symmetry in CLAP patients compared to non-cleft controls of similar age with regard to cleft type and treatment concept. MATERIALS AND METHODS: In CLAP patients with different cleft forms and in healthy non-cleft subjects (control group) a three-dimensional stereophotogrammetric face scan was performed and an objective 3D asymmetry index (AI) was calculated for the whole face, the midface, the upper lip and the nose. RESULTS: In total, 305 patients were included: 140 CLAP patients (90 male, 50 female, mean age 9.9 ± 3.6 years) and 165 controls (87 male, 78 female, mean age 8.7 ± 2.1 years). In general, CLAP patients showed significantly higher asymmetry than controls, with the most severe asymmetry found in unilateral complete CLAP. Patients treated according to an actual concept considering reconstruction of all affected muscular systems had a significant lower and more favourable AI than patients not treated according to this concept (p < 0.05). CONCLUSION: An adequate treatment concept is essential to achieve better results concerning symmetry in CLAP, but symmetry values of healthy non-cleft controls are not reached.

3D Analysis of Philtrum Depth in Children with Fetal Alcohol Syndrome.

AIMS: Diagnosis of fetal alcohol spectrum disorder (FASD) is complex and difficult. The estimated number of unreported FASD is thus assumed to be substantial. In our cross-sectional study, we aimed to identify possible metric differences in philtrum depth in children with fetal alcohol syndrome (FAS) compared to healthy controls based on non-invasive 3D facial scanning in order to provide an objective, metrical tool improving FASD diagnosis. METHODS: Twenty-five children with confirmed FAS and 30 healthy school children without FAS, both in the mixed dentition, were prospectively recruited and 3D facial scans were performed after recording body length, weight and head circumference. Philtrum surface data were extracted and metric philtrum depth was determined at four geometrically defined measuring points (P1-P4) along the vertical length of the philtrum. RESULTS: Philtrum depths at P1 (P = 0.025), P2 (P = 0.001), P3 (P < 0.001) and P4 (P = 0.001) as well as mean philtrum depth P1-P4 (P < 0.001) differed significantly between patients with and without FAS. Compared to controls, the philtrum was shallower in patients with FAS by on average 0.4 mm at each of the respective points. Whereas no differences could be determined for body height and weight, head circumference was significantly smaller in patients with FAS (P = 0.001), particularly in girls (P = 0.008). CONCLUSIONS: Apart from head circumference, philtrum depth is significantly reduced in children with FAS and can thus be used as diagnostic indicator to aid and confirm FAS diagnosis. In contrast to visual assessments, 3D face scan methods allow a more objective quantification and can thus provide additional evidence in FAS diagnosis.

Computer-aided design of facial prostheses by means of 3D-data acquisition and following symmetry analysis.

The aim of this study was to investigate whether a method of designing digital models of facial prostheses was suitable for patients with orbital defects. 32 patients were included in a retrospective study. 23 of them already had a facial prosthesis. 3D-data of the faces were acquired optically using fringe projection technique without and with (if available) the facial prosthesis in place. The healthy side of the surface models was mirrored to reconstruct the defect area. By generating a NURBS-model, the edges of the virtual prostheses were adapted to the defect region. The CAD models were stored in STL format as templates for facial prostheses. Using an automatically calculated asymmetry index (AI), four situations of the digitized facial surface were analysed for symmetry: 1. with defect area excluded, 2. with mirrored healthy surface, 3. with digital CAD template, and 4. with manually produced facial prosthesis inserted (if available). Mean AI values were 6.05 ± 3.26 (situation 1), 4.79 ± 2.51 (situation 2), 5.12 ± 2.61 (situation), and 6.74 ± 2.77 (situation 4). Additionally, the CAD templates were rated by three anaplastologists. Ratings did not differ significantly. They partially agreed with the three statements "The CAD prosthesis fits harmoniously within the face", "The CAD prosthesis could be used for a wax pattern during conventional fabrication" and "The CAD prosthesis and the wax pattern reduce workload". The results indicate that the presented technique has the potential to increase facial symmetry and facilitate the technical procedure. However, symmetry alone is not a sufficient criterion for design of a facial prosthesis.

Dynamic behavior of different quantities of osteoblasts during formation of micromass cultures.

Implantation of micromass cultures of osteoblastic cells offers the possibility of scaffold free tissue engineering for example, regeneration of bone defects. However, the details of cell dynamics during the formation of these micromasses are still not well understood. This study aims to investigate and clarify the extent to which cell quantity influences the dynamics of micromass formation of osteoblastic cell cultures. For this purpose, the migration and aggregation during this process are investigated by optical inspection employing image processing software that allows for automated tracking of cell groups using digital image correlation. An exponential time behavior is observed with respect to the velocity of the cells and the distance of the cells to their common center of gravity. Characteristic time constants are derived as quantitative measures of the cell dynamics. The results indicate that the time constants strongly depend on the quantity of cells, that is, will decrease with increasing cell quantity. © 2018 International Society for Advancement of Cytometry.

Quantitative phase imaging for cell culture quality control.

The potential of quantitative phase imaging (QPI) with digital holographic microscopy (DHM) for quantification of cell culture quality was explored. Label-free QPI of detached single cells in suspension was performed by Michelson interferometer-based self-interference DHM. Two pancreatic tumor cell lines were chosen as cellular model and analyzed for refractive index, volume, and dry mass under varying culture conditions. Firstly, adequate cell numbers for reliable statistics were identified. Then, to characterize the performance and reproducibility of the method, we compared results from independently repeated measurements and quantified the cellular response to osmolality changes of the cell culture medium. Finally, it was demonstrated that the evaluation of QPI images allows the extraction of absolute cell parameters which are related to cell layer confluence states. In summary, the results show that QPI enables label-free imaging cytometry, which provides novel complementary integral biophysical data sets for sophisticated quantification of cell culture quality with minimized sample preparation. © 2017 International Society for Advancement of Cytometry.