German S3 guideline on the use of dental ceramic implants.

PURPOSE: Based on the excellent long-term data, dental implants made of titanium are considered the international implantological standard for replacing missing teeth. However, ceramic implants made of zirconia (ZrO2) have experienced a renaissance in the last 15 years due to constant innovations in materials and products, with material properties and soft tissue- and osseointegration behavior comparable to those of titanium. However, one limitation concerning ceramic implants is the lack of reliable long-term data, especially in the case of two-piece implant systems. As there is an increasing demand for ceramic implants from practitioners and patients, the German Society for Implantology (DGI) has decided to develop a guideline on the use of dental ceramic implants at the highest available evidence level with the involvement of experts in this field. METHODS: Statements and recommendations were prepared after conducting a systematic literature search and an independent assessment process involving the relevant clinical literature from 2008 to 2021. The adopted recommendations and statements are summarized in this guideline. RESULTS AND CONCLUSIONS: It confirms the feasible use of one-piece zirconia implants as an addendum/alternative to titanium implants. No final conclusion regarding the application of two-piece ceramic implant systems could be drawn on the basis of the existing data, thus its use can only be recommended after the patient has been informed in detail about the lack of long-term clinical data.

Diabetic mitochondria are resistant to palmitoyl CoA inhibition of respiration, which is detrimental during ischemia.

The bioactive lipid intermediate palmitoyl CoA (PCoA) can inhibit mitochondrial ADP/ATP transport, though the physiological relevance of this regulation remains unclear. We questioned whether myocardial ischemia provides a pathological setting in which PCoA regulation of ADP/ATP transport would be beneficial, and secondly, whether the chronically elevated lipid content within the diabetic heart could make mitochondria less sensitive to the effects of PCoA. PCoA acutely decreased ADP-stimulated state 3 respiration and increased the apparent Km for ADP twofold. The half maximal inhibitory concentration (IC50 ) of PCoA in control mitochondria was 22 µM. This inhibitory effect of PCoA on respiration was blunted in diabetic mitochondria, with no significant difference in the Km for ADP in the presence of PCoA, and an increase in the IC50 to 32 µM PCoA. The competitive inhibition by PCoA was localised to the phosphorylation apparatus, particularly the ADP/ATP carrier (AAC). During ischemia, the AAC imports ATP into the mitochondria, where it is hydrolysed by reversal of the ATP synthase, regenerating the membrane potential. Addition of PCoA dose-dependently prevented this wasteful ATP hydrolysis for membrane repolarisation during ischemia, however, this beneficial effect was blunted in diabetic mitochondria. Finally, using 31 P-magnetic resonance spectroscopy we demonstrated that diabetic hearts lose ATP more rapidly during ischemia, with a threefold higher ATP decay rate compared with control hearts. In conclusion, PCoA plays a role in protecting mitochondrial energetics during ischemia, by preventing wasteful ATP hydrolysis. However, this beneficial effect is blunted in diabetes, contributing to the impaired energy metabolism seen during myocardial ischemia in the diabetic heart.

Comparison of imaging methods used for dental implant osseous integration assessment.

Two different imaging techniques used to determine bone tissue response to dental implants were compared. Dental implants were implanted into the maxillae of 18 pigs, which were sacrificed after 4, 8 and 12 weeks. Implants with surrounding bone tissue were retrieved for methyl methacrylate histology and contact radiography. On identical sections peri-implant bone density and bone implant contact (BIC) ratio were assessed with two different imaging methods. Evaluation of Giemsa eosin stained and contact radiographed sections showed direct osseous integration for all implants and both methods showed a strong correlation with correlation coefficient r = 0.930 (P < 0.0001) for peri-implant bone density and r = 0.817 (P < 0.0001) for bone implant contact ratio. While the two imaging methods showed moderate differences for peri-implant bone density there were significant differences between the BIC values determined. In general, contact radiography tends to underestimate BIC for approximately 4.5 % (P = 0.00003).

Osseointegration of zirconia and titanium dental implants: a histological and histomorphometrical study in the maxilla of pigs.

OBJECTIVES: The purpose of the present study was to histologically compare the bone tissue responses to surface-modified zirconia and titanium implants. METHODS: Threaded zirconia implants were produced using a new low-pressure injection moulding technique and thereafter surface treated by acid etching. Titanium implants with the exact shape and surface treated by sandblasting and acid etching (SLA) served as controls. Fifteen adult pigs received both implant types in the maxilla 6 months after extraction of the second and third incisors. The animals were sacrificed after 4, 8 and 12 weeks and 30 implants with surrounding bone were retrieved. RESULTS: Histological evaluation showed osseous integration for both materials. Zirconia implants revealed mean peri-implant bone density values of 42.3% (SD +/- 14.5) at 4 weeks, 52.6% (SD +/- 5.7) at 8 weeks and 54.6% (SD +/- 11.5) at 12 weeks after implantation, whereas Ti-SLA implants demonstrated mean values of 29% (SD +/- 10), 44.1% (SD +/- 18) and 51.6% (SD +/- 8.6) at corresponding time intervals. With respect to the bone-implant contact ratio, the mean values for zirconia ranged between 27.1% (SD +/- 3.5) and 51.1% (SD +/- 12.4) and for Ti-SLA, it ranged between 23.5% (SD +/- 7.5) and 58.5% (SD +/- 11.4). For the parameters investigated, no statistically significant differences between both types of implants could be detected at any time point. CONCLUSIONS: No statistical difference between implants could be demonstrated with any of the methods used. The limited number of animals per group, however, does not allow to conclude that there is no difference in osseointegration between the two types of implants, although the data tend to suggest such a trend.

Some factors influencing the survival of patients with less advanced stages of differentiated thyroid cancer.

Two groups of patients with less advanced stages of differentiated thyroid cancer were followed from 2 to more than 25 years: 1. 326 patients with preventive thyroid ablation (PTA) in cases of a tumor without lymphatic and remote metastases; 2. 471 patients with lymph node syndrome. It was found that the survival of patients with lymph node syndrome was less including the group below 40 years of age. Within the first group (with PTA) the survival was less in cases with the invasion of tumor through the thyroid capsula (stage T3 according to WHO classification). In both groups neither any significant effect of sex nor histological characteristics of the tumor (i.e. papillary v.s. follicular) was found. However, the effect of age was found to be remarkable in both groups, the prognosis being worse in patients after 40 years of age. Finally, the prognosis of less advanced stages of differentiated cancer was much better than than in patients with remote metastases.

The rational use of 201Tl scintigraphy in the evaluation of differentiated thyroid cancer.

Fifteen patients with differentiated thyroid cancer were examined following 131I thyroid ablation, of these seven were examined after radio-iodine therapy to disseminated neck cancer. They had no further radio-iodine uptake and were evaluated using a 201Tl scan. In thirteen patients there was a good correlation between the results and the clinical diagnosis, showing no uptake in seven subjects with negative clinical findings, and positive delineation of tumour tissue in the neck region in six patients. The remaining two patients with lymph node metastases after previous radio-iodine irradiation showed marked clinical regression of the metastases with absent uptake of both 131I and 201Tl, probably due to radiation-induced changes. The comparison of thallium scans with plasma thyroglobulin levels showed certain differences (high plasma thyroglobulin without any proof of remaining thyroid tissue in one patient and normal/low plasma thyroglobulin in the presence of a tumour in two patients) but both measurements could give additional information. It is believed that while in the differential diagnosis of a thyroid nodule no important information could be expected of scanning (compared with the high value of aspiration biopsy), the evaluation of patients without 131I uptake by 201Tl scans could provide important information for further therapy.

Serum thyroglobulin determinations in patients with differentiated thyroid carcinoma.

Serum thyroglobulin levels were measured in 636 patients with differentiated thyroid carcinoma, in whom altogether 1240 determinations were performed in different phases of disease and treatment. A modified sensitive radioimmunoassay was employed using an own high-specific thyroglobulin antibody. The results showed that both the majority of patients with functioning metastases accumulating radioiodine and with non-functioning metastases which could not be detected by scanning had higher serum TG levels, compared with a group of healthy subjects. However, "normal" TG values in patients with metastases, especially non-functioning, were found too. Thus, these findings decrease the diagnostic value of the TG determination. The highest TG values were found in patients with distant metastases of differentiated thyroid carcinoma (in lungs and bones); on the other hand, the proportion of patients with lymph-node(s) metastases and "normal" TG levels was relatively high. We suggest that the serum TG determination cannot generally replace scanning with 131I and cannot serve as the only test, while being a helpful indicator in the long-term follow-up of differentiated thyroid cancer patients.

TSH stimulation and other ways to increase the uptake in normal and tumorous thyroidal tissue.

The use of bovine TSH is still the most important means for increasing the radioiodine uptake in functionally active tissue. The increase is more marked in normal thyroid tissue (where 2.5 fold increase of the initial value can be expected); but the tumorous tissue reacts to the stimulation, though less substantially (mean increase to 1.5). In intact thyroid gland the increase of uptake is more pronounced with lower uptake in the remaining thyroid tissue; in functionally active tumor this relation cannot be proved. With very low uptake in the tumorous tissue (below 2.5%/24 h) the chance to achieve practically significant increase is negligible. The complications with TSH administration appear especially with repeated application, the proportion of more serious side effects being low. The use of diuretic regime with the iodine depletion simultaneously with TSH stimulation is rather pretentious for the patient; it substantially increases the uptake in the tumorous tissue (again to 2.6 times), although more markedly decreases the iodine excretion in the urine what leads to higher danger of complications caused by radioiodine therapy. The use of TSH stimulation to increase the uptake in the tumorous tissue had not yet been shown to be useful.

Thyroidectomy as a pathogenic factor in the evolution of thyroid cancer.

In a group fo 860 patients with thyroid cancers (TC), 66 were found having had thyroid surgery for benign disorder more than 5 years before the diagnosis of TC. More than 70% of these patients were operated upon 10 or more years ago. The incidence of cancers developing in thyroid postsurgical remnants could thus be estimated to 5.5-7.7% of all thyroid cancers. These patients had predominantly follicular cancers and usually were older than 40 years at the age of diagnosis of TC. Unusually high incidence of distant metastases (pulmonary or osseous) was proved compared to other patients with TC, while the increase of patients having both pulmonary and osseous metastases was not found. It seems that the risk of developing TC late after thyroid surgery is somehow connected with endemic goitre areas, as all such reports arise from the central European area. Whichever the pathogenic mechanism may be, all patients following surgery for benign eumetabolic goitres should be checked up in regular intervals with regard to the possible benign or malignant recurrence. Patients operated upon because of hyperthyroidism do not seem to carry any similar risk.

[Roentgenological characteristic of pulmonary metastases in thyroid cancer in respect of its biological behaviour (author's transl)]. / Röntgenologische Charakteristik von Lungenmetastasen des Schilddrüsenkarzinoms mit Bezug auf sein biologisches Verhalten.

In metastases of the lung which must be considered as typical in cancer of the thyroid, it is possible to differentiate roentgenologically between fine and coarse nodules, the limit being approximately 10 mm. Metastases consisting of fine nodules are by no means to be considered as representing a fatal generalisation, whereas metastases with coarse nodules are frequently accompanied by other metastases distant from the primary tumour.