Separation of overlapping dental arch objects using digital records of illuminated plaster casts.

BACKGROUND: Plaster casts of individual patients are important for orthodontic specialists during the treatment process and their analysis is still a standard diagnostical tool. But the growing capabilities of information technology enable their replacement by digital models obtained by complex scanning systems. METHOD: This paper presents the possibility of using a digital camera as a simple instrument to obtain the set of digital images for analysis and evaluation of the treatment using appropriate mathematical tools of image processing. The methods studied in this paper include the segmentation of overlapping dental bodies and the use of different illumination sources to increase the reliability of the separation process. The circular Hough transform, region growing with multiple seed points, and the convex hull detection method are applied to the segmentation of orthodontic plaster cast images to identify dental arch objects and their sizes. RESULTS: The proposed algorithm presents the methodology of improving the accuracy of segmentation of dental arch components using combined illumination sources. Dental arch parameters and distances between the canines and premolars for different segmentation methods were used as a measure to compare the results obtained. CONCLUSION: A new method of segmentation of overlapping dental arch components using digital records of illuminated plaster casts provides information with the precision required for orthodontic treatment. The distance between corresponding teeth was evaluated with a mean error of 1.38% and the Dice similarity coefficient of the evaluated dental bodies boundaries reached 0.9436 with a false positive rate [Formula: see text] and false negative rate [Formula: see text].

Evaluation of dental morphometrics during the orthodontic treatment.

BACKGROUND: Diagnostic orthodontic and prosthetic procedures commence with an initial examination, during which a number of individual findings on occlusion or malocclusion are clarified. Nowadays we try to replace standard plaster casts by scanned objects and digital models. METHOD: Geometrically calibrated images aid in the comparison of several different steps of the treatment and show the variation of selected features belonging to individual biomedical objects. The methods used are based on geometric morphometrics, making a new approach to the evaluation of the variability of features. The study presents two different methods of measurement and shows their accuracy and reliability. RESULTS: The experimental part of the present paper is devoted to the analysis of the dental arch objects of 24 patients before and after the treatment using the distances between the canines and premolars as the features important for diagnostic purposes. Our work proved the advantage of measuring digitalized orthodontic models over manual measuring of plaster casts, with statistically significant results and accuracy sufficient for dental practice. CONCLUSION: A new method of computer imaging and measurements of a dental stone cast provides information with the precision required for orthodontic treatment. The results obtained point to the reduction in the variance of the distances between the premolars and canines during the treatment, with a regression coefficient RC=0.7 and confidence intervals close enough for dental practice. The ratio of these distances pointed to the nearly constant value of this measure close to 0.84 for the given set of 24 individuals.

Possibility of reconstruction of dental plaster cast from 3D digital study models.

OBJECTIVES: To compare traditional plaster casts, digital models and 3D printed copies of dental plaster casts based on various criteria. To determine whether 3D printed copies obtained using open source system RepRap can replace traditional plaster casts in dental practice. To compare and contrast the qualities of two possible 3D printing options--source system RepRap and commercially available 3D printing. DESIGN AND SETTINGS: A method comparison study on 10 dental plaster casts from the Orthodontic department, Department of Stomatology, 2nd medical Faulty, Charles University Prague, Czech Republic. MATERIAL AND METHODS: Each of 10 plaster casts were scanned by inEos Blue scanner and the printed on 3D printer RepRap [10 models] and ProJet HD3000 3D printer [1 model]. Linear measurements between selected points on the dental arches of upper and lower jaws on plaster casts and its 3D copy were recorded and statistically analyzed. RESULTS: 3D printed copies have many advantages over traditional plaster casts. The precision and accuracy of the RepRap 3D printed copies of plaster casts were confirmed based on the statistical analysis. Although the commercially available 3D printing enables to print more details than the RepRap system, it is expensive and for the purpose of clinical use can be replaced by the cheaper prints obtained from RepRap printed copies. CONCLUSIONS: Scanning of the traditional plaster casts to obtain a digital model offers a pragmatic approach. The scans can subsequently be used as a template to print the plaster casts as required. Using 3D printers can replace traditional plaster casts primarily due to their accuracy and price.

Concentrations of MMP-9 and TIMP-1 in lip tissue and their impact on cleft lip surgery healing.

AIM: To compare aspects of wound healing after cleft lip surgery performed within one week of age and wound healing after surgery performed within 2 - 4 months of age, especially concentrations of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in tissue removed during surgery. METHODS: 34 tissue samples (26 boys and 8 girls) were removed during surgery within one week of age (n=19) or within 2 - 4 months of age (n=15). Tissue samples were separated into epidermis, dermis and mucous membrane. Proteins were extracted in cacodylic buffer for 24 h at a temperature 2 - 8 ºC. Total protein concentrations were examined using a modification of the Lowry method. Samples were examined using ELISA kit Amersham Biotrak Activity Assay (GE Healthcare UK) for detection of MMP-9 and TIMP-1 concentrations. RESULTS: MMP-9: early surgery - epidermis 2.168 ± 3.303 µg/g of protein (mean ± SD), dermis 1.251 ± 1.848 µg/g, 2 - 4 months surgery - epidermis 0.347 ± 0.212 µg/g, dermis 0.555 ± 0.276 µg/g. TIMP-1: early surgery - epidermis 1.762 ± 2.162 µg/g, dermis 1.628 ± 0.822 µg/g, mucous membrane 2.066 ± 1.717 µg/g, 2 - 4 months surgery - epidermis 1.881 ± 2.810 µg/g, dermis 3.117 ± 1.540 µg/g, mucous membrane 4.833 ± 6.550 µg/g. CONCLUSIONS: There were no significant differences in concentrations of protein MMP-9 in epidermis and dermis and TIMP-1 in epidermis and mucous membrane according to time of surgery. Significantly decreased levels of TIMP-1 in dermis were found in samples obtained from early surgery compared to levels in samples obtained from 2 - 4 months surgery.

Effectiveness of physiotherapy and GaAlAs laser in the management of temporomandibular joint disorders.

OBJECTIVE: Low-level laser therapy (LLLT) is a treatment method commonly used in physiotherapy for musculoskeletal disorders. The aim of this study was to monitor the function of temporomandibular joint (TMJ) and surrounding tissues and compare the objective measurements of the effect of LLLT. BACKGROUND DATA: LLLT has been considered effective in reducing pain and muscular tension; thus improving the quality of patients' lives. MATERIALS AND METHODS: TMJ function was evaluated by cephalometric tracing analysis, orthopantomogram, TMJ tomogram, and computer face-bow record. Interalveolar space between central incisors before and after therapy was measured. Patients evaluated pain on the Visual Analog Scale. LLLT was performed in five treatment sessions (energy density of 15.4 J/cm(2)) by semiconductive GaAlAs laser with an output of 280 mW, emitting radiation wavelength of 830 mm. The laser supplied a spot of ~0.2 cm(2). RESULTS: Baseline comparisons between the healthy patients and patients with low-level laser application show that TMJ pain during function is based on anatomical and function changes in TMJ areas. Significant differences were seen in the posterior and anterior face height. The results comparing healthy and impaired TMJ sagittal condyle paths showed that patients with TMJ pain during function had significantly flatter nonanatomical movement during function. After therapy, the unpleasant feeling was reduced from 27.5 to 4.16 on the pain Visual Analog Scale. The pain had reduced the ability to open the mouth from 34 to 42 mm. CONCLUSIONS: The laser therapy was effective in the improvement of the range of temporomandibular disorders (TMD) and promoted a significant reduction of pain symptoms.