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Biomedical subjects

G Watzek

Publications and source records attributed to G Watzek.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Dental magnetic resonance tomography (dental MRI) as a method for imaging maxillo-mandibular tooth retention structures].

PURPOSE: To establish a new method for dental imaging using magnetic resonance tomography named Dental-MRT and to demonstrate its usefulness in diagnosing dentogen pathologies of the mandible and maxilla. METHODS: Seven healthy volunteers, three patients with pulpitis, two patients with dentigerous cysts, two patients after tooth transplantation, and three patients with atrophic mandibles have been evaluated. Optimized axial T1- and T2-weighted gradient echo and spin echo sequences in 2D and 3D technique have been established to perform studies of the jaws. The acquired images were reconstructed with a standard dental software package on a work-station as panorama and cross-sectional views of the mandible or maxilla. RESULTS: The entire maxillo-mandibular bone, teeth, dental pulp, and the content of the mandibular canal were well depicted. Patients with pulpitis demonstrate bone marrow edema in the periapical region. Dentigerous cysts and their relation to the surrounding structures are clearly shown. After contrast media administration marked enhancement of the dental pulp can be demonstrated. CONCLUSION: Dental-MRT promises to provide a new tool for visualization and detection of dental diseases.

Adolescent↗
PubMed1997

Complications of sinus perforations and their management in endodontics.

The intimate position of the maxillary sinus to the apices of teeth creates problems if periapical inflammation occurs. This can lead to a perforation into the sinus and cause sinusitis. Persistent and complicated situations that do not respond after nonsurgical root canal treatment demand a suitable surgical therapy. Knowledge of the specific anatomic conditions, an adequate diagnosis, and an appropriate surgical procedure facilitate success rates that are comparable with those obtained in other regions, even in unfavorable initial conditions.

Acute Disease↗
PubMed1996

The relationship of smoking on peri-implant tissue: a retrospective study.

The term "peri-implantitis" is used to describe the formation of deep mucosal pockets around dental implants, inflammation of the peri-implant mucosa, and increased resorption of peri-implant bone. It has been speculated that when left untreated, peri-implantitis can result in implant failure. This retrospective study examines a possible correlation between smoking and the appearance of peri-implantitis. The clinical and radiographic observations of 366 implants in 107 patients who smoke were compared with those of a group of 1000 implants in 314 nonsmoking patients. Despite the retrospective nature of this study, a comparison between the two groups was possible. The mean follow-up period, mean patient age, implant locations, and percentages of fixed partial dentures and overdentures were consistent in both groups. There was no significant difference in the mean maxillary and mandibular hygienic indices between the group of smokers and that of nonsmokers. However, the group of smokers showed a higher score in the bleeding index, the mean peri-implant pocket depth, the degree of peri-implant mucosal inflammation, and radiographically discernible bone resorption mesial and distal to the implant. In the maxilla of the smoking group, these observations were significantly higher than both the mandibular observations for smokers and the maxillary observations of the group of nonsmokers (p < 0.01). No differences between the two groups were observed in the mandible. Aside from the systemic effects of tobacco smoking on the human organism, local cofactors seem to be responsible for the higher incidence of peri-implantitis in smokers and have a particularly negative effect on the maxilla. These findings confirm that smokers treated with dental implants have a greater risk of development of peri-implantitis.

Adolescent↗
PubMed1995

Brånemark single tooth implants: a preliminary report of 76 implants.

Seventy-six Brånemark single-tooth implants were inserted over a 6-year period. Two implants (2.63%) were removed during the follow-up period. All other implants received esthetic and functional single tooth crowns placed on a single tooth abutment or a CeraOne abutment. The most common complication observed was abutment screw loosening, which occurred with 12 crowns. However, it was possible to clearly reduce the occurrence of screw loosening by applying a defined torque. Peri-implant parameters were investigated on 56 implants that were in place for more than 1 year. Acceptable implant function was demonstrated with preestablished clinical parameters and radiographs. Despite the submucosal edge of the crown, peri-implant mucositis was not a major problem. The favorable clinical and esthetic results found in the study encourage an increased application of implants for single tooth restorations.

Adolescent↗
PubMed1995

The edentulous maxillary alveolar process in the region of the maxillary sinus--a study of physical dimension.

From 47 anatomic specimens, vertical sections were cut in the molar region, and computer-assisted measurements of both height and width of the alveolar ridge were made to assess the available bone volume for endosseous implant placement. The mean ridge heights ranged between 9.30 and 3.23 mm, the highest and lowest values being 13.8 and 0.8 mm, respectively. The ridge widths generally proved to be sufficient for placement of endosseous implants. Small knife-edge ridges are rarely found in the posterior maxilla. Reduction of the cancellous portion of the posterior maxilla seems to be influenced by the duration of edentulousness, as well as by osteoporotic changes, without being directly related to ridge configuration and bone volume.

Aged↗
PubMed1995

[Advantages of microsurgical apicoectomy and retro-preparation with ultrasound compared with current apicoectomy].

From September 1992 to March 1994 at the Department of Oral Surgery of the Dental School of the University of Vienna a total of 218 microsurgical apicoectomies and ultrasonic retro-preparations were carried out in 142 patients. Among other indications for operation was the failure of previous surgical-endodontic procedures in 62 cases. In 51 teeth (82%) of these patients the cause of failure could be evaluated with the help of the microscope. Twelve teeth (19%) extracted afterwards showed a longitudinal root fracture which had not been diagnosed before. In all other teeth retro-preparation and filling with zincoxide-eugenol cement was possible, even in cases of difficult anatomic approach. Due to the excellent experiences with microsurgical technique in apicoectomies, the use of the microscope in other fields of dental surgery remains only a matter of time.

Adult↗
PubMed1995

[Follow-up of tooth vitality with laser Doppler flowmetry in transplanted teeth].

21 autotransplanted teeth were examined by using laser Doppler flowmetry (LDF) at 1, 2, 3, 6 and 12 postoperative weeks. 20 teeth showed statistically significantly higher perfusion units up to the 6th weeks as compared to the control group. At 12 postoperative weeks, the perfusion values of the autotransplanted teeth were at the same level as those of the control group. It was possible to show a non-revascularisation of one tooth with LDF. Currently, LDF can be considered as the only practicable, non-invasive method to evaluate the revascularization of autotransplanted teeth.

Adolescent↗
PubMed1993

Location of the mandibular canal within the atrophic mandible.

In 43 edentulous, lower jaw halves, sections were carried out in the area between the mental foramen and the third molar. The relative changes in the location and course of the mandibular canal which are caused by atrophy were analysed. For this purpose, the mandibles were classified according to so-called residual ridge orders which describe the different stages of alveolar ridge resorption. The following findings were obtained: The distance between the mandibular canal and the lingual and buccal external border does not change in any stage of the atrophic process, i.e. it remains conspicuously constant. However, the distance between the mandibular canal and the cranial and caudal borders of the body of the mandible partly changes to a statistically highly-significant extent, the distance between the canal and the atrophic alveolar ridge being affected more strongly than that between the canal and the base of the mandible. These changes were most clearly pronounced in the area of the first molar.

Aged↗
PubMed1993

Surgical criteria for endosseous implant placement: an overview.

This paper presents an overview of important criteria for successful endosseous implantation. It discusses implant-specific anatomy, preoperative planning, the influence of structure and quality of the available bone on implant prognosis, and the principles of mechanical implant site preparation. The presentation also considers the vitality of adjacent bone, implant surface integrity, local bone defect augmentation, implant selection, and immediate implantation. The learning objective of this article is to enhance the knowledge of surgical and implant site preparation protocol.

Dental Implantation, Endosseous↗
PubMed1993

Effects of drill cooling and bone structure on IMZ implant fixation.

Alternating use of the original method of internal drill cooling with manual external cooling, one IMZ implant was placed in the diaphysis (compact bone) and metaphysis (spongy bone) of the left distal tibia in each of six sheep. After polyfluorochrome sequential labeling, two animals survived for 4, 8, and 16 weeks without functional loading of the implants. The drill holes and bone-implant reactions were evaluated in undecalcified ground sections and microradiographs, using computer-aided histomorphometry. At least 30% of all drill holes were incongruent, but up to 25% of the implant surfaces had primary bone contacts. Four weeks after implantation, distinct differences in the bone reactions could be determined between the experimental conditions. After both cooling methods, osteoclastic resorption had extended up to 0.5 mm into peri-implant compact bone and up to 0.18 mm into spongy bone. Based on the percentage of newly formed bone-to-implant contacts, external cooling proved superior at all superficial drill hole levels in compact bone and in all spongy bone beds, while internal cooling was only better at the deeper drill hole levels in compact bone. After 8 and 16 weeks, peri-implant bone remodeling led to further increased new bone-implant contacts, irrespective of incongruent drill holes or cooling methods. At all time periods, abraded titanium particles were observed within interfacial foreign body cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Reproducibility of three-dimensional CT-assisted model production in the maxillofacial area.

In the mid-eighties, computerised tomography (CT) assisted three-dimensional imaging, and modelling of skull structures was introduced into preoperative diagnosis in maxillofacial surgery. This new method is already being used in the preoperative planning of corrections of post-traumatic defects and craniofacial deformities as well as in tumour surgery and implantology. The aim of the present study was to collect information on the reproducibility of a skull model milled from hardened polyurethane foam, and based on the CT data of a real skull. Thirty one measurements were carried out on the model and on the original skull, leading to the result that the model showed a mean inaccuracy of 1.5 mm. The deviations ranged between 0.0 and 3.6 mm. Generally, the model structures, however, tended to be larger than those of the original. As far as the total of all measurements is concerned, the model deviated from the original skull by 1.6%. A convincing aspect of the model, which cannot be obtained by any other method, is its plasticity and the possibility of 3-D orientation on a lifesize model. However, the study indicates that surgeons using this technique should consider the possible discrepancies between the model and the real skull when making preoperative assessments.

Artificial Intelligence↗
PubMed1989

[Conditions of the gingiva around endosteal implants with attached and unattached mucosa].

The condition of the peri-implant mucosa is critical for the long-term success of endosteal implants. 111 endosteal implants (IMC and Brånemark) were examined to see whether peri-implant gingival attachment to bone and peri-implant inflammatory reactions correlated with implant stability. A direct relation was found exist between peri-implant mucosal attachment and pocket depth around implants, while the severity of peri-implant inflammatory reactions did not correlate with implant stability. But this might be explained by the relatively short implant residence of 5 years at the time of the follow-up study.

Biocompatible Materials↗
PubMed1989

[Bone resorption at the entry of osseointegrated implants--a biomechanical phenomenon. Finite element study].

Using finite element analysis, osseointegrated implants exposed to physiologic stresses were examined for the occurrence of stress concentrations at the site of implant entry into bone and factors affecting such stress concentrations were looked for. Qualitative and quantitative alterations of stresses around endosseous implants were computed for different implant sizes, implant materials and cortical thicknesses. The following factors were found to be important for reducing peak stresses in cortical bone: Cylindrical implants are preferable to conical implant shapes. Large implant diameters provide for more favorable stress distributions. Implant materials should have a modulus of elasticity of at least 110,000 N/mm2. Slipping between implants and cortical bone is desirable.

Bone Resorption↗
PubMed1988

Local prostaglandin E2 in patients with oral malignancies undergoing chemo- and radiotherapy.

Patients undergoing chemo- and/or radiotherapy for malignancies were often found to develop annoying inflammation of the oral mucosa. As prostaglandins are known to be cytoprotective. Prostaglandin E2 was given to 10 patients who received combined radio- and chemotherapy for oral neoplasms. Patients receiving PGE2 reported substantially less intense pain then those in the control group. Our statistically significant results indicate that topical treatment of side effects produced by combined radio- and chemotherapy of oral neoplasms with PGE2 holds promise and is clearly superior to conventional treatment modalities.

Adult↗