Differences in platelet growth factor release and leucocyte kinetics during autologous platelet gel formation.

Three commercial systems for whole blood separation were compared to obtain the buffy coat composed of platelet-rich plasma (BC-PRP) and leucocytes . These samples of the buffy coat were used to make a platelet gel (PG), which was used to measure platelet growth factor (PGF) release, to perform a white blood cell (WBC) count and to measure myeloperoxidase (MPO) release from WBCs. Aliquots of whole blood obtained from ten volunteers were distributed either to a blood cell separator (The Electa Cell-Separator, E-CS) or to a tabletop centrifuge (Gravitational Platelet Sequestration System, GPS) to prepare the BC-PRP. The third system combines the BC-PRP production by E-CS with a micro porous filter (Autologous Growth Factor filter, AGF) to enrich for the BC-PRP. Autologous thrombin was used to activate the BC-PRP and to prepare the PG and subsequently to degranulate the platelet concentrate. Platelet-derived growth factor-AB and transforming growth factor-beta1 were present in high levels after thrombin activation of the E-CS or GPS prepared samples. However, the AGF prepared samples released their growth factors before thrombin activation. The WBCs were significantly increased with each of the three systems. Contrary to the AGF, no leucocyte degranulation occurred with the E-CS or GPS prepared samples, based upon the low MPO concentrations in the BC-PRP. The three types of apparatus had different harvesting capacities for collecting the enriched platelets and the release of high concentrations of PGF. When the E-CS and GPS, but not the AGF, were used, low levels of MPO were maintained in the PG, which potentially contributes to antimicrobial properties of platelet gel at the site of application.

[Heerfordt's syndrome -- a rare initial manifestation of sarcoidosis]. / Das Heerfordt-Syndrom -- eine seltene Erstmanifestation der Sarkoidose.

Sarcoidosis is a chronic, multisystem disorder of unknown cause characterized by noncaseating epithelioid granulomas. Infectious agents and genetic components have been discussed. Heerfordt's syndrome with uveitis, enlargement of the parotid glands and optional paralysis of the Nn. facialis is a form of sarcoidosis. The diagnosis is confirmed by histology. Further analyses are fiberoptic bronchoscopy with bronchoalveolar lavage or the gallium-67 scan in combination with blood findings. The therapy of choice is glucocorticoids. We present a case report of Heerfordt's syndrome and a review of the literature covering different aspects of sarcoidosis.

Effect of platelet concentration in platelet-rich plasma on peri-implant bone regeneration.

This study analyzed the effect of the platelet count in platelet-rich plasma (PRP) on bone regeneration in vivo. Twenty male New Zealand white rabbits were used. PRP was produced using the Platelet Concentrate Collection System (PCCS) (3i, Miami, FL, USA). After inducing ketamine-xylazine anaesthesia, a self-tapping titanium screw (Branemark MK III TiUnite, 3.75 x 7 mm) was inserted in each distal femur; the femurs were randomized so that one side was treated with PRP while the other (control) was not. Intravital fluorochrome staining was performed on days 1, 7 (1.5 ml of 2% doxycycline/kg bodyweight), 14 (6% xylenol orange, 1.5 ml/kg), and 21 (1% calcein green, 5 ml/kg). Animals were euthanized on day 28 (n = 20). Specimens were prepared for histomorphological evaluation according to Donath and Breuner [J. Oral Pathol. 11 (1982) 318]. Comparing the bone regeneration (fluorochrome staining) in the 4-week implants (n = 19), the only significant difference (sign test, P = 0.004) was seen with intermediate platelet concentrations (n = 9,503,000-1,729,000 platelets/microl PRP). There were no differences in the bone/implant contact rates between the test and the control side among the three groups. The platelet concentration required for a positive PRP effect on bone regeneration seems to span a very limited range. Advantageous biological effects seem to occur when PRP with a platelet concentration of approximately 1,000,000/microl is used. At lower concentrations, the effect is suboptimal, while higher concentrations might have a paradoxically inhibitory effect. On the other hand, the effect of this type of platelet concentrate was not beneficial to accelerate the osseointegration of enosseous dental implants.

[Criteria of success in implantology]. / Erfolgskriterien in der Implantologie.

BACKGROUND: So far there is no generally accepted definition of success in the case of dental implants, although criteria differing from country to country have been proposed, which evaluate the success of implants with reference to clinical and X-ray control parameters. The aim of the study was to examine the five most frequently used sets of criteria suggested for determination of the success or otherwise of implants ( Albrektsson, Jahn, Buser, NIH conference, Naert) and ascertain their relative values. METHODS: In a clinical review, 508 implants (Astra, Frialit-2, IMZ TwinPlus and ITI) were examined and a subjective evaluation of them was made by the patients. Subsequently a statistical analysis was executed (in situ rate, Kaplan-Meier, success criteria). RESULTS: The average observation time of all implants included in the study was 3.5 years, and the in situ survival rate was 95%; Kaplan-Meier survival analysis revealed that the probability of survival after 6 years was 93%. Application of different criteria for success gave very different results (Albrektsson 88%, Naert 89%, NIH 85%, Buser 88%, Jahn and dacute;Hoedt 75%). DISCUSSION: The increasing importance of quality assurance in medicine makes it necessary to establish standards that will permit reliable comparative analysis of how successful implants are in the future.

[Patient satisfaction with dental implants]. / Patientenzufriedenheit in der Implantologie.

BACKGROUND: Almost all implant systems available today achieve success rates of over 90%. The subjective satisfaction of patients with dental implants is only rarely considered in the definition of implant success and there are only limited data on the satisfaction of patients with dental implants in the literature. Therefore, a satisfaction analysis was carried out in a retrospective study. DESIGN OF STUDY: In addition to a clinical investigation, 330 patients with 1,273 implants (Astra, Frialit-2, IMZ TwinPlus and ITI) were asked to answer a standardized questionnaire to rate their personal opinion on the implant success. A total of 199 questionnaires (803 implants, 63%) were returned and could be analyzed. RESULTS: Of the patients, 67% participated in regular follow-up after implantation and 15% indicated postoperative discomfort. Patient satisfaction with the implants (rated on a scale of 1-6) was good or excellent (2 and 1, respectively) in 88% of cases. Satisfaction with the prosthetic treatment was 80%. The whole treatment was considered good or very comfortable by 86% of patients. If necessary, 91% of patients who underwent the procedure would do so again, and 94% would recommend the procedure to someone else. The Spearman correlation analysis did not reveal any statistically significant correlations between the clinical parameters and patient satisfaction scores. DISCUSSION: Despite the high number of patients involved ( n=330), the expected influence of objective clinical parameters on patient satisfaction could not be statistically evaluated. Nevertheless, in addition to the clinical parameters, subjective patient satisfaction should be included in the evaluation of implant success.

[Life threatening oral hemorrhage after implantation into the distal right mandible]. / Biochirurgische Wund-konditionierung mittels Madentherapie und Vakuum-verbänden nach Teilnekrose eines Haut-Muskel-Transplantats im bestrahlten Kopf-Hals-Bereich.

In dental practice, surgical implant procedures are frequently conducted for pre-prosthetic surgery. Intra-operative complications are rare and can mostly be prevented effectively with adequate preparatory measures. However, not all risks can be anticipated a priori. Anatomical variation, such as variation in the path of blood vessels, is often unpredictable. This paper describes a life-threatening hemorrhage that occurred in a 60-year-old male during the insertion of an implant in the distal right mandible. It was impossible to stop the bleeding using local measures. Only extraoral ligation of the facial artery proved effective in suppressing the hemorrhage. The submentalis artery, a branch of the facial artery, had an atypical path directly below the caudal ridge of the mandible. The possibility of similar complications should make us re-evaluate preoperative preventive measures, and places greater demands on intra-operative complication prophylaxis. The international literature on this topic is discussed.

[Growth stimulation of human osteoblast-like cells by thrombocyte concentrates in vitro]. / Wachstumsstimulation von humanen osteoblastenähnlichen Zellen durch Thrombozytenkonzentrate in vitro.

AIM OF THE STUDY: Thrombocytes contain different growth factors. Their potential use for increasing bone regeneration is currently under discussion. Basic data about the biologic effect of platelet concentrates (platelet-rich plasma, PRP) are still lacking. This study analyzes the in vitro effect of PRP on the proliferation rate of human osteoblast-like cells (OLC). MATERIAL AND METHOD: Human OLC were stimulated with thrombocytes in different dilutions (0-1,700,000 thrombocytes/microliter). Three days later a WST test (Roche Diagnostics) was performed to measure the mitochondrial syntheses and cellular proliferation rate. RESULTS: The proliferation rate of the OLC was (concentration-dependent) increased up to a certain plateau by adding thrombocytes. Further stimulation led to a slight decrease in the proliferation rate. The statistical analysis of the extinction measurements showed significant differences in the cell proliferation rates between mostly all thrombocyte concentration groups (p < 0.0001). Moreover, a statistically significant difference was evaluated for the time-dependent change in extinction (0-5 h) (p < 0.0001). CONCLUSION: This study shows that the proliferation rate of human OLC can be stimulated in vitro by concentration-dependent platelet concentrates. This in vitro result supports the currently discussed assumption that the clinical use of PRP might increase bone regeneration.

Correlation of platelet concentration in platelet-rich plasma to the extraction method, age, sex, and platelet count of the donor.

An important reason to improve methods of isolating platelet-rich plasma (PRP) is the potential use of autologous platelet growth factors. In addition to discontinuous plasma separation, a second method for extraction of PRP has now become available, which can be performed directly by the surgeon. In this study, the suitability of the 2 methods of producing PRP was compared. Whole blood was drawn from 158 healthy donors (112 men, 46 women) aged 20 to 62 years (mean 34, SD 10). The PRP was separated by the discontinuous plasma separation method (by the blood bank) or by the so-called "buffy coat" method (the "self-concentration" method, analogous to the PRP Kit, Curasan, Kleinostheim, Germany). Platelet counts differed significantly according to donor blood (median men 237,500/microL, women 272,000/microL), blood bank PRP preparation (median men 1,302,000/microL, women 1,548,500/microL), and self-concentrated PRP (median men 944,000/microL, women 1,026,000/microL). The platelet concentration of the blood bank PRP correlated with the platelet count in the donor whole blood (Spearman's correlation coefficient r(s) = 0.73). However, there was no significant correlation between the platelet count of self-concentrated PRP and donor whole blood (r(s) = 0.22). Significant but irrelevant influences of sex on platelet concentration were found, but no influence of age was detected.

Five-year prospective follow-up report of the Astra tech standard dental implant in clinical treatment.

Between 1994 and 1999, 515 Astra standard implants were placed and documented prospectively in 107 patients. Of these implants, 364 were placed in original jawbone, 38 in areas augmented with local osteoplasty, and 113 in bone grafts from the iliac crest. The main indications for implantation were an atrophic edentulous alveolar crest (n = 361) and a shortened dental arch (n = 113). Single-tooth implants were excluded. In a special clinical examination, 56 patients with 258 implants were investigated. The average in situ time of the implants was 34.2 months. Failing osseointegration (n = 10), peri-implantitis (n = 10), and implant fracture (n = 1) in 15 patients resulted in the failure of 21 implants (4.1%). Three patients with 8 implants died from malignant tumor. Currently, 27 implants have been lost to follow-up, and 488 implants remain in situ (95.9%). Under analyses with different implant success criteria, the success rate decreased to 85%. Based on the results in this patient population, this implant was found to be a useful alternative to established implant systems for the indications analyzed.

[IMZ-TwinPlus bone implant system--4 years clinical experience]. / Das IMZ-TwinPlus-Schraubenimplantat-System--4 Jahre klinische Erfahrung.

AIM OF THE STUDY: For more than twenty years the IMZ-system has been in clinical use, since 1995 modified as IMZ-TwinPlus. The aim of this prospective clinical trial was to analyse the success of the latter implant system, which is an automatically threading cylindrical titanium screw with a deep structured surface (Fa. FRIATEC AG, Mannheim, BRD). Investigated parameters were the peri-implant situation of the soft tissues, the bone loss and the rate of implant failure after a maximum period of 4.5 years of clinical use. MATERIAL AND METHODS: From 1995-2000 sixty-eight patients were provided with a total of 278 IMZ TwinPlus screw implants for various indications (mainly alveolar ridge atrophy). 191 implants were inserted without any, 35 implants with a loco-regional and another 52 implants after comprehensive reconstructive osteoplastic surgery. 38 patients with 155 implants were re-examined using a standardised protocol to evaluate peri-implant hard- and soft tissue situation as well as the patient's subjective assessment of the treatment. RESULTS: With a maximum of 54 months the mean observation period was 30 months. The implant failure rate has risen to 6% so far (n = 18 in 12 patients). Two patients bearing 7 implants have passed away. One patient with 4 implants was lost to follow up. 249 implants were still under function at examination, thus the in situ rate was 91%. The Kaplan-Meier survival rate after 54 months proved 91%. DISCUSSION: To our knowledge there are at present no other data published on the survival rate of the IMZ TwinPlus implant system. The results of this study evaluate a survival rate similar to the classical IMZ cylinder implant and other implant systems for the analysed observation period. CONCLUSIONS: After a maximum observation period of 4.5 years the IMZ TwinPlus implant system showed results in the range of other well-established implant systems. Designed to resist rotation of the superstructure the IMZ TwinPlus screw implant widens the range of indications in comparison to the classical IMZ cylinder implant system.

[Cytokeratin expression in botryoid odontogenic cyst. A rare differential keratocyst and ameloblastoma diagnosis]. / Zytokeratinexpression der botryoiden odontogenen Zyste. Eine seltene Differentialdiagnose zu Keratozyste und Ameloblastom.

The botryoid odontogenic cyst (BOC) is considered a rare multilocular variant of the lateral periodontal cyst. The origin of the BOC can be seen in aberrant odontogenic tissue. The BOC is found especially in the premolar region of the mandible, as well as in the frontal region of the maxilla of patients aged between 60 and 70 years. Most of the 11 published articles of BOC have shown high rates of recurrence. Histopathologically the BOC is marked by multilocular cysts lined by a thin, nonkeratinized epithelium. Clusters of glycogen-rich epithelial cells may be noted in nodular thickenings of the cyst lining. For the clinician, the differentiation of the BOC from the keratocyst and ameloblastoma is relevant. One case of a large BOC (65-year-old male, BOC regio 33-45, diameter 5 cm, radiographically and histologically multilocular) is presented with a review of the literature, including the therapeutic management, and the possible diagnostic criteria are discussed. The immunohistochemically determined expression of cytokeratin (CK) 13 implicates the histogenetic origin of the BOC from the squamous epithelium of the oral cavity and excludes the origin from the small salivary glands. The expression of CK 19 and the lack of expression of p53, as well as the higher proliferation rate of the basal epithelial cell layer by the BOC, may be useful for distinction between the keratocyst.

[Determining the size of the specific surface of bone substitutes with gas adsorption]. / Bestimmung der Grösse der spezifischen Oberfläche von Knochenersatzmaterialien mittels Gasadsorption.

The surface area and the microporosity of bone regeneration materials influence their chemical and biological properties. Therefore, the size of the specific surface area and the distribution of the pore diameters (pores < 1 micron) of bone regeneration materials were analyzed within this study. The analyzed hydroxyapatites were of synthetic, bovine, and phytotroph origin. The tricalcium phosphates and the bioglasses included only synthetic materials. The gas adsorption of each specimen was analyzed using a volumetric N2/Kr system (ASAP 2010, Micromeritics). Additionally, for materials with a specific surface area (> 2 m2/g) the pore size distribution was evaluated by the BJH-method. Two of the materials evaluated astonishingly large dimensions of the specific surface area (BioOss 79.7 m2/g, Algipore new 14.6 m2/g). A medium surface area was found for Algipore old (4.9 m2/g) and Interpore200 (2.64 m2/g). All other included materials showed only small sizes of the specific surface area (Ceros80 1.8 m2/g, Ceros82 1.31 m2/g, Cerasorb 1.2 m2/g, Biobase 0.7 m2/g, Endobone 0.7 m2/g, Perioglas 0.6 m2/g, Allotropat50 0.23 m2/g, Biogran 0.2 m2/g). The materials with large and medium sizes of the specific surface area evaluated the following pore diameters: BioOss 2-50 nm, Algipore new 2-100 nm, Algipore old 5-50 nm, Interpore200 2-100 nm. Pore sizes less than 2 nm were not found in relevant numbers. The materials BioOss, old and new Algipore, and Interpore200 contain a large interconnecting mesopore system (diameter < 1 micron). For the materials Biobase, Endobone, Perioglas, Allotropat 50, and Biogran this cannot be assumed. The materials Ceros80, Ceros82, and Cerasorb evaluated a specific surface area between those and might include only a small part of these interconnecting pores. An influence of the interconnecting porosity and the different sizes of the specific surface areas on the biological behavior of the bone regeneration materials can be suggested.

[Tissue damage and regeneration after laser surgery using different scanning systems]. / Gewebeschädigung und -regeneration nach Laseranwendung unter Verwendung unterschiedlicher Scanning-Systeme.

INTRODUCTION: Laser systems are frequently used in dentistry. New laser scanner technologies are promising more homogeneous ablation of pathological ablations of the skin and mucosa. The theoretical advantages of these systems have not yet been sufficiently evaluated by histological findings. For this reason, we compared two laser scanners with different scanning patterns in this study (Silktouch and Swiftlase, by Sharplan, Germany). MATERIALS AND METHODS: In this animal study (79 male Osborn-Mendel rats), skin defects of 3-mm diameter were lasered on to the backs of the animals, one for each method mentioned above (defocused laser, Swiftlase, and Silktouch). The histological investigations were conducted, depending on the time after surgery (9 h, 1, 2, 3, 4, 5, 6, 7, 9, 11, or 13 days). On the clinical site, we evaluated the visible ablation rate, homogeneity and morphology of the wound surface and the degree of carbonization. In the histomorphological investigations, we determined the degree of thermal damage as well as the morphology of the necrotic area and reepithelization pattern of the surface. RESULTS: The Silktouch scanner clinically showed a homogeneous ablation rate with less carbonization than the Swiftlase scanner. In the histological specimen, this correlated with an increase in the tissue ablation rate and decreasing thermal damage to the surrounding tissue. Especially in the early wound-healing period, there was a more rapid reepithelization after the use of the Silktouch scanner. These differences could not be evaluated in the later wound-healing period. Compared to the defocused laser ablation, both scanning systems seem to have benefits within these parameters. CONCLUSIONS: The results of this study seem to show a diminished perifocal damage and reduced clinical postoperative morbidity achieved by using laser scanning systems. Compared to the Swiftlase laser, the Silktouch seems to deliver better results.

[Roentgen spectrometry comparison of currently available bone substitutes]. / Röntgenspektrometrischer Vergleich der aktuell verfügbaren Knochenersatzmaterialien.

INTRODUCTION: The crystalline structure of hydroxyapatite (HA) and tricalciumphosphate (TCP) used as bone regeneration materials affects their physical and probably also their biological properties. Varying velocities of the HA solution process seem to be correlated to different results in powder diffraction analysis (RDX) [1], a validated, routine procedure in minerology [2, 6] to analyse crystallized materials. As far we know there are no comparative RDX analyses for the TCP materials in clinical use. GOALS: The dimension and quality of the crystallization of several bone regeneration materials are analysed by RDX. MATERIAL AND METHODS: The materials analysed were divided in different groups: hydroxyapatite, tricalciumphosphate and bioglass. The materials are characterized by the specific intensity curve measurements. RESULTS: The HA products, with the exception of Algipore, seem to be monophasic. Ceros80 and Endobone were the only ones which seem to be totally crystallized. The TCP products Biobase and Cerasorb are nearly monophasic, whereas Ceros82 seems to contain a mixture of 30% HA and 70% beta-TCP. All TCPs show a high crystallization. The bioglasses did--as suspected--not show crystalline structures. DISCUSSION: There are many possible causes for inhomogeneous crystallization of the investigated materials, as they are composites of different foreign ions, extremely small crystals or abnormal (deficient) apatites. How this affects the biological behaviour is not known. SUMMARY: We found differences between the examined materials; how this affects the biological behaviour is unknown. Further investigations are necessary to correlate the characteristics of the materials to the clinical outcome.