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Biomedical subjects

T Dostálová

Publications and source records attributed to T Dostálová.

16 recordsLinked to original sources
PubMed2006

Study of laser created ZRO2 and hydroxyapatite/ZrO2 films for implantology.

Thin films of ZrO2 and hydroxyapatite/ZrO2 were created by excimer laser ablation on Ti6Al4V substrates. ZrO2 layers were fabricated in vacuum by KrF laser at various substrate temperatures and hydroxyapatite (HA) layers were fabricated in water vapor ambient by ArF laser and in water vapor/argon ambient by KrF excimer laser. Film properties were evaluated by XRD, SEM and WDX methods. The test of mechanical adhesion was proceeded on ZrO2 films. XRD analysis proved the presence of amorphous or crystalline HA in the deposited films. SEM method demonstrated smooth surface covered by droplets for both HA and ZrO2 films. Ca/P ratio of the HA films is higher than that of the natural HA and is within the range of 2.8-3.0. The HA/ZrO2 and ZrO2 samples were tested in vitro for cytotoxicity. The best results were received by the HA/ZrO2 samples in the test of cytotoxicity. Fibroblasts cultivating with HA/ZrO2 samples exhibited subconfluent and confluent growth and showed fibronectin homogenously.

Coated Materials, Biocompatible↗
PubMed2006

Arthralgia of the temporomandibular joint and low-level laser therapy.

OBJECTIVE: This case report describes the treatment of a patient with arthralgia of the temporomandibular joint (TMJ) caused by disc displacement. BACKGROUND DATA: The goal of the treatment of TMJ arthralgia is to decrease pain by promotion of the musculoskeletal system's natural healing ability. METHODS: This report describes the complex treatment of TMJ arthralgia. Low-level laser therapy (LLLT) was chosen for its antiinflammatory and analgesic effects. Laser therapy was carried out using the GaAlAs diode laser with an output power of 400 mW, emitting radiation with a wavelength of 830 nm, and having energy density of 15 J/cm2; the laser radiation was applied by contact mode on four targeted spots in 10 sessions. Physiotherapy was recommended to this patient to prevent the injury of intraarticular tissue caused by incorrect movement during opening of the mouth. Splint stabilization and prosthetic treatment were used to reduce overloading of the TMJ, resulting from unstable occlusion and to help repositioning of the dislocated disc. RESULTS: Five applications of LLLT led to decrease of pain in the area of the TMJ on the Visual Analog Scale, from 20 to 5 mm. The anti-inflammatory effect of the laser was confirmed by thermographic examination. Before treatment, the temperature differences between the areas of the normal TMJ and TMJ with arthralgia was higher than 0.5 degrees C. However, at the conclusion of LLLT, temperatures in the areas surrounding the TMJ were equalized. CONCLUSION: This study showed the effectiveness of complex non-invasive treatment in patients with arthralgia of the TMJ. The analgesic and anti-inflammatory effects of LLLT were confirmed by infrared thermography.

Arthralgia↗
PubMed2006

Shape and size of dental arch--a five-year prospective study.

OBJECTIVES: The diagnostic procedure commences with the initial examination, during which a number of individual findings of the occlusion or malocclusion are clarified [1]. The objective is to describe the morphological and functional characteristics on each patient using specific guidelines, and then to provide a prognosis of the therapy. Upper and lower arch compression in first premolars and molars area was visible before treatment. METHODS: A special device (Czech technical university research prototype) was prepared for this purpose. The optical head contains a digital color camera. The front of the optical head consists of a removable prism which is put into the mouth. The findings can display live images from the camera, which can be archived on a PC. The device captured and geometrically calibrated images permitting comparison of several different dental casts. RESULTS: In the first part of this study 792 sets of study plaster casts were screened. Measurements of dental arch width between reference points of canines, first premolars and first molars were made: upper jaw: men: 3-3-35.1 mm (SE 0.13); 4-4-37.5 mm (SE 0.13); 6-6-48.1 mm (SE 0.19); women: 3-3-33.4 mm (SE 0.13); 4-4-35.6 mm (SE 0.15); 6-6-46.7 mm (SE 0.19). The second part concerns the group of 36 patients which is different from the 792 controls. There were studied changes between initial, post-treatment and post-retention alignment of upper and lower dental arch. CONCLUSIONS: Geometrically calibrated images help compare several different steps of the treatment and show a significant difference between patients before and after treatment.

Adolescent↗
PubMed2005

Long-term clinical evaluation of fixed dentures--two to fifteen years after insertion.

Fixed denture durability is characterized as a period of time for which a dental appliance satisfies functional and esthetic requirements. First of all, its durability is based on the properties of materials it is made of, and depends, at the same time, on the characteristics of biological environment, in which the denture is placed. The purpose of this study was a long-term monitoring of changes taking place in the fixed dental constructions during their application in the oral cavity. These changes were to be evaluated for different types of materials used for fixed dentures manufacturing, namely metal alloys, ceramics, and plastics. A set of 454 full crowns from 134 patients divided in 6 clinical studies was examined and both qualitative and quantitative changes evaluated after 2 and 8 to 15 years after cementation. Clinical assessment adopted the United States Public Health Service System criteria. Alloys of precious metals veneered with ceramics are considered the optimal method of choice for both high precision of execution and consideration of future changes brought on by the use of the dentures.

Crowns↗
PubMed2005

Long-term stability of prosthetic treatment of oronasal and oroantral communications.

This five-year prospective study demonstrates prosthetic treatment by multidisciplinary therapy: surgeon, orthodontist, and prosthodontist. 10 patients volunteered for the study (a group of 7 men and 3 women at an average age of 33.2 years). 10 obturators, 49 fixed dentures were inserted to the upper jaw. Based on ADA (American Dental Association) recommendation a special card was prepared containing relevant information on the patients. Clinical assessments were carried out in accordance with the US Public Health Service System. In a 5-year period only 50.0% of restorations were excellent, receiving 100% alpha rating. The marginal ridge contour and adaptation of obturator achieved 60.0% alpha rating. The anatomic form of dental arch was destroyed in 50.0%. The presence of caries was not detected. Six teeth were extracted due to periodontal disease. The general contour of the restoration followed the overall contour of the fixed denture in 95.9%. Plaque accumulation was found in 50%. The colour match of crowns was darker and translucent in 27.7%, but discoloration of removable denture was seen in 30.0%. The three case reports demonstrate the long-term stability of treatment (from alpha to charlie evaluation). Attachment retention, fixed and removable denture with metal base are the first method of choice, due to acceptable long-term stability.

Adult↗
PubMed2004

A two-year clinical study of metal-ceramic and metal-polymer crowns.

The purpose of this study was to compare full metal crowns with two different types of veneering material - ceramics and polymer after a two-year period in a function. The aim was to evaluate the changes of occlusal relief, marginal adaptation, break of material, changes of shape and color and gingival status. One hundred and two crowns were examined in 34 patients immediately after cementation, and they were reviewed within two years of crown placement. These fixed restorations were checked according two modified US Public Health Service System criteria. After two years the crowns were found clinically intact in 94% for metal-ceramics versus 98% for metal-polymer. No crown was lost. There were found significant differences in positions of a crown margin between both materials and marginal adaptation between initial (baseline) and follow-up results. Gingival health at baseline was related in optimal in 67% versus 77%, after two years in 43% versus 71%. Slight mismatch in color occurred in 0 versus 60% crowns, obvious mismatch was apparent in 0 versus 21% crowns after two years. Within the limitations of this study, it was found that the examined metal crowns with two different veneerings are very stable fixed restorations, mechanical resistance and integrity of polymer material was surprisingly good but its color stability presented mismatch after two-years period. Ceramic veneering was excellent in color match but there were three visible cracks of the ceramic layer.

Crowns↗
PubMed2001

Osseointegration of loaded dental implant with KrF laser hydroxylapatite films on Ti6Al4V alloy by minipigs.

This study was performed with the objective of evaluating osseointegration of titanium alloy Ti6Al4V dental implants coated with hydroxylapatite (HA) deposited by a KrF laser. For this a KrF excimer laser and stainless-steel deposition chamber were used. The thickness of the HA films was approximately 1 microm. In this investigation experimental animals minipigs were used; the implants were placed vertically into the lower jaw. After 14 weeks of unloaded osseointegration, metal-ceramic crowns were inserted and, at the same time, fluorescent solution was injected into the experimental animals. Six months after insertion of crowns the animals were sacrificed. The vertical position of the implants was checked by a radiograph. Microscopic sections were cut and ground, and the sections were examined under polarized and fluorescent light using a microscope with a charge coupled device camera. The six month long osseointegration in the lower jaw has confirmed the presence of newly formed bone around all the implants. In the experimental group, which had a laser-deposited coating, the layer of fibrous connective tissue was seen only randomly. In the control group (titanium implant without a cover) the fibrous connective tissue between the implant and the newly formed bone was observed more frequently, but this difference was not significant.

Alloys↗
PubMed2000

Low-level laser therapy after molar extraction.

OBJECTIVE: The aim of the study was to evaluate effect of the different frequencies of low-level laser radiation (diode 670 nm and Helium-Neon 632.8 nm) on the healing process after human molar extractions. Frequencies of 5 Hz, 292 Hz, and 9,000 Hz were used in experiments. Monitoring of secretory IgA and albumin level in saliva and changes in bone density were used as objective markers of biostimulatory effect. SUMMARY BACKGROUND DATA: From the literature, it is known that if the alveolus is irradiated after extraction along with the lingual and buccal bony wall, faster coagulation, less postoperative discomfort, and quicker healing can be expected. METHODS: Subjective evaluation of therapy was observed using a scale (from -, negative therapeutic effect, to ++++, excellent treatment effect). Changes of secretory immunoglobulin A (sIgA), albumin levels, and bone density were compared in a group of 150 patients (nonlaser therapy, 30 patients). RESULTS: Differences in levels of the saliva markers (sIgA and albumin) were found to be significant when comparing irradiated and nonirradiated groups, and in comparison with those groups irradiated by various modulatory frequencies. Significant differences were observed between the increase of sIgA res. albumin and subjective feelings during treatment. Bone density after extraction and 6 months after surgical treatment was examined using dental digital radiovisiography. No significant differences were detected between bone density in irradiated and nonirradiated groups, perhaps due to our therapy protocol. CONCLUSIONS: The low-level laser has no influence on the process of osseointegration. This effect was observed on fracture healing in rats using He-Ne laser radiation. We found no differences in the bone density when compared to the control group.

Adolescent↗
PubMed1999

Er:YAG and alexandrite laser radiation propagation in root canal and its effect on bacteria.

OBJECTIVE: The objective of this study was to compare the bactericidal effect of the Er:YAG (wavelength 2.94 microm) and the Alexandrite (wavelength 0.75 microm) laser radiation. The spreading laser energy in the surrounding hard dental tissues round the root canal was evaluated and the bactericidal effect of both these different laser wavelengths was analyzed. SUMMARY BACKGROUND DATA: The use of a laser to clean and shape the root canal space is the latest method used for cleaning of root canals. The interest in laser endodontics was concentrated on the possibility to extirpate the contents of the root canal, to sterilize and to "melt" the walls of the root canals. The previous reports were performed with CO2, excimer, argon, Nd:YAG, Ho:YAG, and Er:YAG lasers. METHODS: Er:YAG laser system (2.94 microm, energy 100 mJ or 300 mJ, repetition rate 1 Hz, 30 pulses) and alexandrite laser system (0.75 microm, energy 250 mJ, repetition rate 1 Hz, 30 pulses) were prepared and three experimental arrangements were used during the measurements. First the energy transport through the tooth tissue was observed (frontal and side experimental setups) and then, the bactericidal effect was evaluated. RESULTS: It was demonstrated that due to the absorption in the hydroxyapatite and water content in the dentin, the Er:YAG laser radiation is fully absorbed in the root canal wall. This direct influence of the radiation could be expected only close to the sapphire tip. It was found that the tissue, which was not directly affected by the laser radiation, cannot be disinfected by the subablative effect of Er:YAG laser radiation. In the second part of the experiment the real bactericidal effect of Er:YAG ablative energy (300 mJ) could be observed. It was also shown that the alexandrite laser radiation with a wavelength of 0.75 microm spreads through the canal system space and leaks into the surrounding tooth tissues. Both lasers have bactericidal effect. CONCLUSIONS: The pulsed Er:YAG and alexandrite lasers can be efficiently used for killing dental bacteria but the spreading of their radiation in the tooth tissues are different.

Dental Pulp Cavity↗
PubMed1998

Noncontact Er:YAG laser ablation: clinical evaluation.

OBJECTIVE: The aim of this study is to evaluate the quality of laser ablation in comparison with the classical drilling preparation. METHODS: For the experiment, the Er:YAG laser drilling machine was used. The system had a laser head, water cooler, and power supply with automatic control. Spot size of 300-350 microns was used for the preparation. Repetition rate of 1-4 Hz, and pulse energies of 100-400 mJ with water spray were chosen. Cavity shape in comparison with classical drill, time of preparation, and influence of cavity shape on filling materials retention in accordance with the U.S. Public Health Service System were used. The evaluation criteria for noncontact Er:YAG ablation were done. RESULTS: The cavity shape is irregular, but spot surface has larger area and microretentive appearance. Caries of enamel and dentin were treated with a noncontact preparation. It was possible to remove the old insufficient fillings, except for amalgam or metal alloys. The average number of pulses was 111.22 (SE 67.57). Vibrations of microexplosions during preparation were felt by patients on 14 cavities; however, nobody felt unpleasant pain. The qualities of filling materials in laser cavities were very stable; however, cavo surface margin discoloration of 82-86% of Alfa rating could be a problem. Changes of the color and anatomic form of the tooth were observed in 4-8%. CONCLUSIONS: In comparison with the classical treatment, it could be said that the retention and quality of filling materials is the same or very similar.

Adult↗
PubMed1997

Dentin and pulp response to Erbium:YAG laser ablation: a preliminary evaluation of human teeth.

OBJECTIVE: We determined the real effect of Erbium:YAG laser ablation on human teeth in vivo. SUMMARY BACKGROUND DATA: We advocated the idea that overheating of teeth, specially pulp damage can be avoided if correct laser parameters are used. METHODS: We evaluated human premolars scheduled for extraction during orthodontic treatment. Before tooth extraction, an oval cavity preparation was made with a pulsed Er:YAG laser. After extraction, the teeth were decalcified for 6 weeks. Routine staining with haematoxylin and eosin was performed on longitudinal section. One hundred seventy-two sections were prepared and examined in a light microscope. RESULTS: Under Er:YAG laser application, reduction of the dentin layer was observed. Dentinal tubules had a radial course up to the surface. No cracks or structural injury were observed. Inflammatory reaction in the pulp was not found. The vascularity of the pulp was normal. The odontoblasts were of the usual spindle-like or star-like cell shape. The cementum and epithelial attachment were healthy. No changes of structure or indications of inflammation were observed. CONCLUSIONS: The results of this in vivo experiment on human teeth confirm safety of Er:YAG laser ablation of enamel and dentin under the conditions described.

Adolescent↗
PubMed1996

Evaluation of the surface changes in enamel and dentin due to possibility of thermal overheating induced by Erbium:YAG laser radiation.

This study investigates the thermal danger of Erbium (Er):YAG laser ablation. Classical preparation techniques have many disadvantages caused by unfavorable changes of temperature, pressure, and by mechanical vibrations. The effect of mechanical vibrations and pressure is eliminated by use of laser ablation technique. The purpose of this study was to analyze the side effects resulting from thermal changes of enamel and dentin in extracted human teeth subjected to pulsed Er:YAG laser radiation using both wet and dry ablation methods. The micrographs of the sections were checked and measured afterwards. The effect of the investigated laser irradiation on the origin of cracks was analyzed in the scanning electron microscope. The hard structures of the teeth were observed under transmitted and polarized light. The occurrence of cracks can be directly correlated to overheating during dry enamel ablation, because heat is generated by absorption of the laser beam by enamel and dentin. The addition of water mist during irradiation not only enables rapid ablation of enamel and dentin, but offers thermal protection to the pulp. The heat changes to the pulp caused by an energy level of 200 mJ from the tested laser system may be reduced by adding a fine water spray during the lasing procedure.

Dental Enamel↗