Enhancement of human dental cyst PGI2 formation by platelet derived growth factor and its role in cyst growth and bone resorption.

Various prostaglandins, particularly PGE2 and PGI2, appear to play a major role in osteolytic processes. Radiochromatographic studies have demonstrated that 6-oxo-PGF1-alpha is a major product of exogenously added arachidonic acid in human dental cysts. As platelets may also act as inflammatory cells, platelet-derived growth factor might also have a PGI2-stimulating influence in such cysts. Eleven human dental cysts were examined by a radioimmunoassay and bioassay which can show PGI2 synthesis in human dental cysts without addition of PDGF. Incremental PDGF addition caused a highly significant increase in the rate of PGI2 synthesis. PGDF thus stimulates PGI2 synthesis in chronic inflammatory processes in vitro and may thereby elicit or accelerate osteolysis.

[Realtime sonography in the diagnosis and follow-up of malignant tongue tumors. II. Detection and staging]. / Real-time-Sonographie in Diagnostik und Verlaufskontrolle maligner Zungentumoren.Teil II: Nachweis und Staging.

92 sonographic examinations performed in 62 patients were evaluated to determine the possible application of sonography in the diagnosis and follow-up of malignant tumours of the tongue. Squamous cell carcinomas were by far dominant and proved to be hypoechoic, mainly inhomogeneous and ill-defined masses. In most cases, they ranged between 2 and 4 cm. in diameter. In 50% of the lesions an infiltration of the pharynx wall was confirmed, and exulcerations were correctly detected by sonography in 75%. In preoperative determination of the size of the tumour, sonography correctly detected the size in 93% of the cases and was thus markedly superior to the clinical palpatory examination, which determined a mere 43% correctly. Sonography should be included in the pretherapeutic staging of tumours of the tongue to objectify the clinical findings. It is also adequate to document tumour behaviour during radiation.

[Dental magnetic resonance tomography (dental MRI) as a method for imaging maxillo-mandibular tooth retention structures]. / Dentale Magnetresonanztomographie (Dental-MRT) als Verfahren zur Darstellung des maxillo-mandibulären Zahnhalteapparates.

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.

Sonographic imaging of the soft-tissue thickness of the edentulous maxilla.

For preimplantologic evaluation and diagnosis, there are various mechanical methods for measuring the thickness of the soft tissue and thus indirectly measuring the osseous bed of the implant. This study evaluated the use of real-time sonography for analyzing the soft-tissue thickness of the entire edentulous maxilla in an anatomic examination of human cadaver specimens. The data obtained were compared with findings from the usual needle measurement method. The ultrasound measurement method produced realistic data in all measurement points of all sectional planes selected.

Survival of 1,920 IMZ implants followed for up to 100 months.

A total of 1,920 IMZ implants, placed between March 1984 and December 1993, were evaluated retrospectively. The Kaplan-Meier cumulative survival rate of the implants was 89.9% after 60 months and 83.2% after 100 months. Life table analysis revealed a statistically significantly lower cumulative survival rate for maxillary implants (71.6% at 60 months and 37.9% at 100 months) than for mandibular implants (90.4% at 100 months). Implants placed in the anterior region of the maxilla failed significantly more often than those placed in the posterior region. This was not observed in the mandible. The age and sex of the patients, the status of the jaw (edentulous, partially edentulous), the time of implant placement in relation to tooth extraction, and the length and diameter of the implants had no statistically significant influence on the cumulative survival rate.

Examination of the damping behavior of IMZ implants.

The damping behavior of 392 IMZ implants with a diameter of 4 mm was examined by performing Periotest measurements during regular implant follow-up. The results were correlated with radiographically assessed peri-implant bone reduction. To guarantee statistical independence, only one randomly chosen implant per patient was considered in the examination. In 167 implants, the difference between the mean mandibular and maxillary Periotest values proved to be statistically significant. Age, sex, and radiographic length of the endosseous part of the abutment had no influence on the Periotest values. Assessment of the Periotest values can thus be considered an additional parameter for objective determination of IMZ implant success. However, exclusive use of the Periotest method without additional radiographic examinations does not seem to be justified.

Use of crestal bone for augmentation of extremely knife-edged alveolar ridges prior to implant placement: report of 3 cases.

A technique is presented for interforaminal lateral augmentation of mandibles with adequate bone height, but extremely knife-edged mandibular alveolar ridges (Class IV of Cawood and Howell's classification of residual ridges), in which the crestal portion of the knife-edged ridge is used as grafting material. Following an osteotomy and rotation of the grafts by 180 degrees, the grafts were fixed to the residual ridge below the osteotomy line by means of miniscrews. All grafts showed only mild resorption after a healing period of 3 months, and it was possible to place 4 implants in the now sufficiently wide host region.

Regional chemotherapy of inoperable maxillofacial tumours combined with radiotherapy. Long-term results.

At the Department of Oral Maxillo-Facial Surgery, University of Vienna, we have from January 1973 to September 1985, subjected 117 patients with inoperable malignant tumours in the maxillo-facial area to intra-arterial chemotherapy consisting of methotrexate and bleomycin. In this group 103 patients have also been given radiotherapy. In this report only 68 patients of the group of 103 patients who have undergone combined treatment have been considered eligible for evaluation on the basis of their post-therapeutic survival time, which ranged from 2 to 11 years. 10 cases with complete remission and 34 cases with partial remission were observed, indicating that 65% responded to combined treatment.

[Cloning of solid tumors in double agar (human tumor stem cell assay]. / Cloning von soliden Tumoren im Doppelagar (human tumour stem cell assay).

62 specimens from 37 patients with solid malignant tumours were cloned by the human tumour stem cell assay (HTSCA). The growth rate, the use of two different disaggregation methods and their influence on vitality and plating efficiency were analyzed as well as the cloning rate from different tumour regions and metastases. The growth rate was 68%, and there was a significant difference in the vitality, depending on which mode of disaggregation was used. Enzymatic disaggregation showed a higher vitality than the mechanical method, although there was no difference in plating efficiency (PE). There was a marked heterogeneity in the PE of specimens from different sites of the same tumour and lymph node metastases (variation coefficient 0.507 and 2.093 respectively). The possibilities and limitations of the HTSCA are discussed with respect to our own results and those in the literature.

Experience with radical surgical treatment of maxillofacial tumours invading the base of the skull. Long term results.

A review of patient data of maxillofacial tumours invading the base of the skull shows a relatively high fatality rate as a result of surgical intervention but also an unexpectedly high life expectancy. Surgical intervention seems to be the right choice whenever clinical examination suggest tumour removal is possible even if a tumour cannot be extirpated in one operation and a further operation from a second access is needed.

Five-year results of maxillary intramobile Zylinder implants.

We retrospectively analysed the time-dependent function of 501 Intramobile Zylinder (IMZ) implants inserted between August 1983 and December 1994 to restore partially and fully edentulous maxillae. To ensure the independence of implants when calculating level of significance, we chose one implant per patient at random. This was done 500 times to obtain a representative result. The simplified success rate was 473/501 (92%) whereas the time-related survival probability was 76% after 60 months. In 31% (156/500) of the life-table calculations, implants placed in completely edentulous maxillae showed a significantly lower probability of survival than did those placed in partially edentulous patients (P mean: 0.17; SD: 0.19). Implants, that had been placed in the anterior and premolar regions of edentulous maxillae, had a survival probability of 60%, after 60 months. The survival probability of implants placed in the molar region was 100%, over the same observation period. The patient's age, sex, and the time of placement of the implant after tooth extraction had no significant influence on the implant's prognosis. The prognosis of implants inserted for partial edentulism meets the criteria proposed for a viable implant system. Our findings indicate that in complete edentulous maxillae, implants should be placed in the posterior rather than in the anterior region, even though this necessitates augmentation procedures such as sinus lift.

Local benefit of prostaglandin E2 in radiochemotherapy-induced oral mucositis.

In 15 patients suffering from maxillofacial cancer with radiochemotherapy-induced oral mucositis the local application of prostaglandin E2 (PGE2) tablets, 0.5 mg four times a day at a 4-h interval was performed. Plasma determination of the bicyclo-prostaglandin E2 metabolite showed no significant amount of the locally applied substance in the circulation. It is claimed that for this particular indication, PGE2 is a potent locally acting compound without affecting circulating levels.

[Simultaneous radiation- and chemotherapy (methotrexate and bleomycin) of inoperable malignant oro-facial tumors]. / Inoperabilis arctáji malignomák radio-kemoterápiával (i. a. methotrexat és bleomycin) történö egyidejü kezelése.

The overall response rate is 65% with 17% CR (medium 56 months) and 49% PR (medium 5 months). The Kaplan-Meier survival plot shows no difference between the previously treated and untreated groups, whereas the kappa 2-analysis indicates a significant advantage for patient with complete response in the previously untreated group (p less than 0.03). Between the different tumor sites and the presence or absence of lymphnodes, there was no significant difference either in survival or in the distribution of the CR, PR and P. The group with bone destruction has a significant shorter median survival time of 9 months versus 15 months in patients with no bone-involvement (p less than 0.03).

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.

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.

Elimination of bacteria on different implant surfaces through photosensitization and soft laser. An in vitro study.

Microbiologic examinations of implants have shown that certain microorganisms described as periodontal pathogens may have an influence on the development and the progression of peri-implant disease. This experimental study aimed to examine the bactericidal effect of irradiation with a soft laser on bacteria associated with peri-implantitis following exposure to a photosensitizing substance. Platelets made of commercially pure titanium, either with a machined surface or with a hydroxyapatite or plasma-flame-sprayed surface or with a corundum-blasted and etched surface, were incubated with a pure suspension of Actinobacillus actinomycetemcomitans or Porphyromonas gingivalis or Prevotella intermedia. The surfaces were then treated with a toluidine blue solution and irradiated with a diode soft laser with a wave length of 905 nm for 1 min. None of the smears obtained from the thus treated surfaces showed bacterial growth, whereas the smears obtained from surfaces that had been subjected to only one type of treatment showed unchanged growth of every target organism tested (P < 0.0006). Electron microscopic inspection of the thus treated platelets revealed that combined dye/laser treatment resulted in the destruction of bacterial cells. The present in vitro results indicate that lethal photosensitization may be of use for treatment of peri-implantitis.

A minimally invasive second-stage procedure for single-tooth implants.

The natural look of dental restorations has become a universally claimed treatment objective, especially when single-tooth gaps are restored with implants. A harmonious gingival margin is crucial to achieve this goal. This article presents a new procedure for exposure of single-tooth implants that yields a favorable esthetic result in the visible maxillary regions because of the simple type of incision used. The procedure consists of two incisions: the first incision makes it possible to find out the implant position and the second incision shapes the mucous membrane according to local supply. The second incision also prevents the soft tissue from tearing after careful stretching and subsequent pressing of the supraimplant mucosa. There is minimal soft tissue traumatization, and as a result, healing time can be reduced to 1 week and an appealing esthetic result can be reached.

[Bone resorption at the entry of osseointegrated implants--a biomechanical phenomenon. Finite element study]. / Die Knochenresorption an der Eintrittstelle osseointegrierter Implantate--ein biomechanisches Phänomen. Eine Finite-Element-Studie.

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.

[Causation of stomatitis during cytostatic chemotherapy for head and neck tumors]. / Zur Ursache der Stmoatitis bei der Chemotherapie von Kopf-Hals-Tumoren.

In a prospective trial involving 17 patients with head and neck tumors an attempt was made to relate the occurrence of stomatitis during cytostatic chemotherapy to changes in the resident microbial population, if any. Of the 17 patients who received the same cytostatic regimen, 10 developed stomatitis after a mean interval of 12 days. Smears were taken of the 2 patient subgroups (with and without stomatitis) at the onset of treatment and after comparable intervals during treatment and compared to those of a normal control group. Pretreatment smears did not show any quantitative or qualitative differences in the aerobic and anaerobic microbial spectrum between the 3 subgroups examined. During treatment patients developing mucositis were found to show a statistically significant multiplication of pathogens, while the other 2 groups still did not differ from one another. Together with the direct cytostatic effect of chemotherapy, proliferation of pathogens in the oral cavity appears to contribute to the development of stomatitis.