Influence of CAD/CAM all-ceramic materials on cell viability, migration ability and adenylate kinase release of human gingival fibroblasts and oral keratinocytes

OBJECTIVES

The aim of this study was to analyze the influence of four CAD/CAM all-ceramic materials on cell viability, migration ability and adenylate kinase (ADK) release of human gingival fibroblasts (HGF) and oral keratinocytes (HOK).

MATERIALS AND METHODS

HGF and HOK were cultured on disc-shaped CAD/CAM all-ceramic materials (e.max CAD LT, e.max CAD HT, Empress CAD and Mark II) and on discs made of tissue culture polystyrene surface (TCPS) serving as control. Cell viability was analyzed by using an MTT assay, and migration ability was investigated by a scratch assay. A ToxiLight assay has been performed to analyze the effect of all-ceramic materials on ADK release and cell apoptosis.

RESULTS

At MTT assay for HGF, no significant decrease of cell viability could be detected at all points of measurement (p each > 0.05), while HOK demonstrated a significant decrease in cell viability especially on Empress CAD and Mark II at each point of measurement (p each < 0.001). Scratch assay demonstrated an increased migration ability for HGF on e.max CAD HT, Empress CAD and Mark II (p each < 0.001), whereas HOK showed a significantly decreased migration ability on all tested materials at all points of measurement (between -36 % and -71 %; p each < 0.001). At ToxiLight assay, only small cytotoxic effects of the all-ceramic materials could be investigated.

CONCLUSIONS

This study disclosed significant differences in cell viability and migration ability of HGF and HOK on CAD/CAM all-ceramic materials.

CLINICAL RELEVANCE

CAD/CAM all-ceramic materials can influence oral cell lines responsible for soft tissue creation which may affect the esthetic outcome.

Contrast curves of five different intraoral X-ray sensors: a technical note

OBJECTIVES

The aim of this article is to compare the contrast and resolution properties of five different sensors using a known technical target.

METHODS

Stripe patterns with defined amounts of line pairs per mm (2.5-20 LP/mm) were recorded using five commercial digital sensors. Image data were analyzed using ImageJ and MatLab to calculate different contrast curves using logistic regression.

RESULTS

The Dexis Platinum Sensor reached a calculated 10% contrast at 29.52 LP/mm. The Duerr VistaRay 6 Sensor reached a 10% contrast at 9.9 LP/mm. The 10% contrast was found at 18.8 LP/mm for the Duerr VistaRay 7. The Sirona Xios+ Sensor reached a calculated 10% contrast at 13.9 LP/mm. The Sirona Fullsize charge-coupled device (CCD) Sensor exhibited 10% contrast at 10.3 LP/mm.

CONCLUSIONS

The contrast transfer function assessment used in the study confirmed that the spatial frequency at 10% contrast was much lower than the theoretical resolution computed from the pixel size.

Advantages of fitting contrast curves using logistic function: a technical note

OBJECTIVE

The aim of this article is to demonstrate how the contrast properties of an imaging system can be ideally fitted with the use of stripe patterns and the logistic function.

STUDY DESIGN

Stripe patterns with defined amounts of line pairs (lp/mm) per mm (10-20 lp/mm) were recorded with the use of digital photostimulable storage phosphor. Scan data and normalized image data were analyzed with the use of ImageJ and MatLab to calculate different contrast curves.

RESULTS

For original scan data, the goodness of fit was 0.0000019 (sum of squared error [SSE]). The R-square was 0.9998. For normalized data the goodness of fit was 0.0007 (SSE) and the R-square 0.998. An amount of 50% contrast could be calculated to be found on 11.67 lp/mm in normalized images.

CONCLUSIONS

This article addresses a potentially new approach to compare digital x-ray modalities using a direct assessment of a known technical target.

Intraoral cameras as a computer-aided diagnosis tool for root canal orifices

The aim of this study was to evaluate the diagnostic advantage of a new software tool in combination with an intraoral camera for automatic detection of root canal orifices in life videos via the access cavity of extracted human molars. The performance of a predoctoral dental student analyzing the images of the camera (without automatic detection) was compared with that of an experienced observer. Sensitivity and confidence intervals were provided and compared with histological slices of 200 teeth used for evaluation. The software's sensitivity for detection of root canal orifices was 0.957 (95 percent confidence interval: 0.936 to 0.972). The sensitivity for the observer was 0.906 (95 percent confidence interval: 0.877 to 0.929) compared to 0.847 (95 percent confidence interval: 0.813 to 0.877) achieved by the predoctoral student. The tested software reaches a high sensitivity for automatic real-time detection of root canal orifices with intraoral cameras in direct comparison to histological images. The system might be a useful help for both pre-and postdoctoral students as an aid for the detection of second mesiobuccal root canal orifices.

Correlation of cone beam computed tomography (CBCT) findings in the maxillary sinus with dental diagnoses: a retrospective cross-sectional study

This study was conducted to assess the coincidence of mucosal hyperplasia in the maxillary sinus and related clinical diagnoses of posterior maxillary teeth found in cone beam computed tomography (CBCT) scans. A total of 204 patients who underwent CBCT examinations between 2006 and 2008 were evaluated retrospectively. Clinical and CBCT findings were correlated using patient records. Absolute frequencies, odds ratios (OR), and 95% confidence intervals (95% CI) were calculated for statistical evaluations. There was a pronounced association between periodontitis and radiological signs of sinusitis. Basal mucosal wall thickening was more likely in patients with decayed and non-vital teeth compared to patients with sound teeth (OR = 5.2; 95% CI = 1.2-23.1). Basal mucosal wall thickening was also more likely than total mucosal thickening (OR = 10.4; 95% CI = 2.6-42.2). Patients with decayed and endodontically treated teeth were more likely to exhibit involvement of the basal wall (OR = 9.2; 95% CI = 3.3-25.2) than were patients with healthy teeth. CBCT examinations revealed a correlation between basal mucosal thickening in the maxillary sinus and decayed posterior maxillary teeth or periodontitis. Chronic symptoms involving the sinuses are one of the most common reasons for patients to consult physicians. One reason for chronic orofacial pain is the prevalence of undiagnosed sinus conditions.

The modulation transfer function and signal-to-noise ratio of different digital filters: a technical approach

OBJECTIVES

The aim of this study was to illustrate the influence of digital filters on the signal-to-noise ratio (SNR) and modulation transfer function (MTF) of digital images. The article will address image pre-processing that may be beneficial for the production of clinically useful digital radiographs with lower radiation dose.

METHODS

Three filters, an arithmetic mean filter, a median filter and a Gaussian filter (standard deviation (SD) = 0.4), with kernel sizes of 3 × 3 pixels and 5 × 5 pixels were tested. Synthetic images with exactly increasing amounts of Gaussian noise were created to gather linear regression of SNR before and after application of digital filters. Artificial stripe patterns with defined amounts of line pairs per millimetre were used to calculate MTF before and after the application of the digital filters.

RESULTS

The Gaussian filter with a 5 × 5 kernel size caused the highest noise suppression (SNR increased from 2.22, measured in the synthetic image, to 11.31 in the filtered image). The smallest noise reduction was found with the 3 × 3 median filter. The application of the median filters resulted in no changes in MTF at the different resolutions but did result in the deletion of smaller structures. The 5 × 5 Gaussian filter and the 5 × 5 arithmetic mean filter showed the strongest changes of MTF.

CONCLUSIONS

The application of digital filters can improve the SNR of a digital sensor; however, MTF can be adversely affected. As such, imaging systems should not be judged solely on their quoted spatial resolutions because pre-processing may influence image quality.

Length of endodontic files measured in digital radiographs with and without noise-suppression filters: an ex-vivo study

OBJECTIVES

The aim of this study is to evaluate if theoretically possible edge shifts induced by noise-suppression filters potentially occur on objects found in digital radiographs. Most manufacturers carry out noise-suppression filtering of their images before they are displayed to the user. It is not usually possible for the user to disrupt the function of the filters. The use of these filters can lead to deletion of small image structures.

METHODS

K-files (ISO size 06, 08, 10 and 15) were placed in the root canals of 6 human teeth located in cadaver jaw segments. File tip positions were measured on original and filtered digital images by three observers. The file position was marked on each filtered image and compared with the unfiltered ones.

RESULTS

The 5 × 5 pixel-sized median and mean filters caused the largest underestimation of measured lengths between -7.87 pixels and -10.8 pixels (-306.93 μm and -421.2 μm). Maximum standard deviation for length differences was found for the calculated position ( = gold standard) and the original unfiltered images with 13.31 pixels. The standard deviation found for the 5 × 5 mean and median filter was 7.62 pixels and 8.68 pixels.

CONCLUSION

Different studies showed that noise-suppression filters can induce edge shifts in diagnostic radiographs. The high standard deviations found for length differences between the defined gold-standard and the original images indicate that theoretical edge shifts may not be clinically relevant for length measurements of endodontic files.

Recognition of root canal orifices in video sequences as a future support system during endodontic treatment

INTRODUCTION

The objective of this study was to show the practical application of computer-aided techniques for detecting root canal orifices through the access cavity using a video camera mounted on a microscope.

METHODS

A minimum distance classification image recognition algorithm was tested in an in vitro study to assess the possibilities of computer-aided recognition of root canal orifices. A Motic DM143 digital stereo microscope (Motic Germany GmbH, Wetzlar, Germany) was used because it includes a video camera that can be connected via USB1.1 to any computer.

RESULTS

The newly developed software is capable of communicating with a video camera and can automatically detect the root canal orifices in all teeth used in this study. A total of 165 extracted human teeth (molars and premolars) were used as test data to collect 8,250 images via screenshots for the evaluation of the detection quality. The software provided a detection sensitivity of 90.1%, with only 11.9% of the images as false-positive detections.

CONCLUSION

The study shows that computer-aided recognition of root canal orifices with video cameras is possible.

Software for automated application of a reference-based method for a posteriori determination of the effective radiographic imaging geometry

OBJECTIVES

Presentation and validation of software developed for automated and accurate application of a reference-based algorithm (reference sphere method: RSM) inferring the effective imaging geometry from quantitative radiographic image analysis.

METHODS

The software uses modern pattern recognition and computer vision algorithms adapted for the particular application of automated detection of the reference sphere shadows (ellipses) with subpixel accuracy. It applies the RSM algorithm to the shadows detected, thereby providing three-dimensional Cartesian coordinates of the spheres. If the three sphere centres do not lie on one line, they uniquely determine the imaging geometry. Accuracy of the computed coordinates is investigated in a set of 28 charge-coupled device (CCD)-based radiographs of two human mandible segments produced on an optical bench. Each specimen contained three reference spheres (two different radii r1=1.5 mm, r2=2.5 mm). True sphere coordinates were assessed with a manually operated calliper. Software accuracy was investigated for a weighted and unweighted algebraic ellipse-fitting algorithm.

RESULTS

The critical depth- (z-) coordinates revealed mean absolute errors ranging between 1.1+/-0.7 mm (unweighted version; r=2.5 mm) and 1.4+/-1.4 mm (weighted version, r=2.5 mm), corresponding to mean relative errors between 5% and 6%. Outliers resulted from complete circular dense structure superimposition and one obviously deformed reference sphere.

CONCLUSIONS

The software provides information fundamentally important for the image formation and geometric image registration, which is a crucial step for three-dimensional reconstruction from > or =2 two-dimensional views.