Gernot Weibrich

Quantification of Thrombocyte Growth Factors in Platelet Concentrates Produced by Discontinuous Cell Separation

Platelet concentrates (PC) are increasingly used to increase bone regeneration in pre-prosthetic surgery. Although it is generally appreciated that certain growth factors (PDGF, TGF, EGF, and ECGF) are present in thrombocyte preparations, relatively little is known about these components in quantitative terms. The study reported here analysed the amounts of growth factors in PC produced under standard conditions from healthy volunteers. All the blood samples (237 in total) were analysed using Quantikine ELISA kits (R and D). The mean - SD platelet count in whole blood from these donors was 262,000 - 58,000/ w l, while in PC produced by discontinuous cell separation it was 1,419,000 - 333,000/ w l. The mean growth factor concentrations in PC preparations in ng/ml were as follows: PDGF-AB 125 - 55 ng/ml; TGF- g 1 221 - 92 ng/ml; IGF-I 85 - 25 ng/ml; PDGF-BB 14 - 9 ng/ml; TGF- g 2 0.4 - 0.3 ng/ml. These growth factor concentrations typically covered a 3-10 fold range: PDGF-AB 29-277 ng/ml; PDGF-BB 2-33 ng/ml; TGF- g 1 32-397 ng/ml; TGF- g 2 0.1-1.2 ng/ml; IGF-I 40-138 ng/ml. Platelet counts in PC were slightly higher for women (Mann-Whitney Test all p <0.001 ) than for men, while the concentrations of growth factors in PC exhibited no gender-related difference of any statistical significance.

The Influence of PRP on Early Bone Formation in Membrane Protected Defects. A Histological and Histomorphometric Study in the Rabbit Calvaria

BACKGROUND Platelet rich plasma (PRP) has been proposed to be a useful adjunct to bone grafting. PURPOSE The aim of the present study was to assess new bone formation in bone regeneration procedures using platelet rich plasma (PRP) alone or in combination with autogenous bone. MATERIALS AND METHODS Four surgically created, monocortical defects 5 mm in diameter in the calvariae of 15 New Zealand rabbits were grafted with a coagulum-filled control, PRP, particulated autogenous bone alone (A), or combined with PRP (A-PRP). RESULTS Mean platelet concentration of 1,761,930 ± 680,200/µl was achieved (5.30 ± 2.63 × fold of baseline). Animals were sacrificed 1, 2, and 4 weeks later. Histomorphometric analysis showed no statistical difference for total new bone formation at any time point, however, a detailed analysis revealed a statistically significant higher percentage of lamellar bone than woven bone for the autogenous bone group at 2 weeks; all other groups demonstrated equal percentages of either bone type. At 4 weeks, all groups revealed a statistically greater component of lamellar bone over woven bone. Graft resorption rate was similar for both A and A-PRP. PRP platelet concentration was significantly positively correlated with TGF-beta1 but not with PDGF-AB. CONCLUSIONS Within the limits of the chosen animal model, this study demonstrated that PRP during early healing, whether alone or mixed with autogenous bone, did not lead to greater bone remodelling, as compared to coagulum. In contrast, autogenous bone alone demonstrated accelerated bone remodelling at 2 weeks.

Wachstumsstimulation von humanen osteoblastenähnlichen Zellen durch Thrombozytenkonzentrate in vitro

Fragestellung. Thrombozyten enthaltenverschiedene Wachstumsfaktoren, deren möglicher Nutzen zur Beschleunigungder Knochenregeneration aktuell diskutiert wird. Basisdaten zur biologischenWirkung von Thrombozytenkonzentraten (platelet-rich plasma: PRP) stehen derzeitnoch weitgehend aus. Daher wurde in dieser Studie der In-vitro-Effekt von PRPauf die Proliferationsrate von humanen osteoblastenähnlichen Zellenuntersucht (OLC: osteoblast-like cells). Material und Methode. Aus humanerBeckenkammspongiosa in Zellkultur etablierte OLC wurden mit Thrombozyten (Thr)in verschiedenen Verdünnungslösungen(0–1.700.000 Thr/µl) stimuliert. Nach 3 Tagen erfolgteein WST-1-Test (Roche Diagnostics) zur Quantifizierung der mitochondrialenSynthese bzw. der zellulären Proliferationsrate. Ergebnisse. Die gemessenen Extinktionenvon OLC ließen sich in vitro durch die Zugabe von Thrombozytenkonzentrationsabhängig bis zu einem Plateau steigern. Eine Stimulationüber diesen Peak hinaus führte zu einem leichten Abfall derExtinktionswerte. Die statistische Analyse der Extinktionskurven nach Brunnerund Langer ergab beim paarweisen Vergleich der evaluiertenZellproliferationsraten (nach Stimulation mit unterschiedlich konzentriertenThrombozytenverdünnungslösungen) signifikante Unterschiede (p<0,0001). Statistisch signifikante Unterschiede zeigtensich auch hinsichtlich des Zeitverlaufs der Extinktionsmessungen nach0–5 h (p<0,0001). Schlussfolgerung. Die Studie zeigt,dass die Proliferationsrate von humanen OLC in vitro durch PRPkonzentrationsabhängig gesteigert werden kann. Dieses In-vitro-Ergebnisstützt damit die aktuell diskutierte Annahme, dass der klinische Einsatzvon Thrombozytenkonzentraten die Knochenregeneration beschleunigenkönnte. Aim of the study. Thrombocytes containdifferent growth factors. Their potential use for increasing bone regenerationis currently under discussion. Basic data about the biologic effect of plateletconcentrates (platelet-rich plasma, PRP) are still lacking. This study analyzesthe in vitro effect of PRP on the proliferation rate of human osteoblast-likecells (OLC). Material and method. Human OLC werestimulated with thrombocytes in different dilutions (0–1,700,000thrombocytes/µl). Three days later a WST test (Roche Diagnostics) wasperformed to measure the mitochondrial syntheses and cellular proliferationrate. Results. The proliferation rate of theOLC was (concentration-dependent) increased up to a certain plateau by addingthrombocytes. Further stimulation led to a slight decrease in the proliferationrate. The statistical analysis of the extinction measurements showedsignificant differences in the cell proliferation rates between mostly allthrombocyte concentration groups (p<0.0001). Moreover,a statistically significant difference was evaluated for the time-dependentchange in extinction (0–5 h) (p<0.0001). Conclusion. This study shows that theproliferation rate of human OLC can be stimulated in vitro byconcentration-dependent platelet concentrates. This in vitro result supportsthe currently discussed assumption that the clinical use of PRP might increasebone regeneration.

Bestimmung der Größe der spezifischen Oberfläche von Knochenersatzmaterialien mittels Gasadsorption

Fragestellung: Die Oberfläche sowie die Mikro- und Mesoporosität von Knochenersatzmaterialien beeinflussen deren chemische und biologische Eigenschaften. Daher wurden in dieser Untersuchung die Größe der spezifischen Oberfläche sowie die Verteilung der Porendurchmesser (Poren < 1 μm) in Knochenersatzmaterialien bestimmt. Material und Methode: Die untersuchten Hydroxylapatite waren synthetischen, bovinen und phytotrophen Ursprungs. Die Trikalziumphosphate und die Biogläser umfassten nur rein synthetische Materialien. ¶Die Gasadsorptionsuntersuchung je einer Probe erfolgte mit Hilfe eines volumetrischen N 2 -Kr-Systems (ASAP 2010, Micromeritics). Zusätzlich wurde für Materialien mit spezifischen Oberflächen ¶> 2 m 2 /g die Porengrößenverteilung nach der BJH-Methode ermittelt. Ergebnisse: 1. Spezifische Oberfläche: 2 der Materialien zeigten eine auffallend große spezifische Oberfläche (BioOss 79,7 m 2 /g, Algipore neu 14,6 m 2 /g). Eine mittlere Oberfläche zeigten Algipore alt (4,9 m 2 /g) und Interpore 200 (2,64 m 2 /g). Die übrigen Materialien zeigten nur kleine Oberflächen (Ceros 80 1,8 m 2 /g, Ceros 82 ¶1,31 m 2 /g, Cerasorb 1,2 m 2 /g, Biobase 0,7 m 2 /g, Endobone 0,7 m 2 /g, Perioglas 0,6 m 2 /g, Allotropat 50 0,2 m 2 /g, Biogran 0,2 m 2 /g). 2. Häufigkeitsverteilung des Porendurchmessers: Die Materialien mit großen und mittleren spezifischen Oberflächen zeigten folgende Porendurchmesser: BioOss 2–50 nm, Algipore neu 2–¶100 nm, Algipore alt 5–50 nm, Interpore 200 2–100 nm. Porengrößen < 2 nm fanden sich kaum. Schlussfolgerungen: Die Materialien BioOss, Algipore alt und neu und Interpore 200 haben ein großes interkonnektierendes Mesoporensystem (Durchmesser < 1 μm). Für die Materialien Biobase, Endobone, Perioglas, Allotropat 50 und Biogran ist dies nicht anzunehmen. Die Materialien Ceros 80, Ceros 82 und Cerasorb zeigen eine dazwischen liegende spezifische Oberflächengröße und weisen einen mäßigen Anteil von solchen interkonnektierenden Poren auf. Ein Einfluss der interkonnektierenden Porosität und der deutlich unterschiedlichen spezifischen Oberflächen auf das Verhalten der Knochenersatzmaterialien in vivo ist nahe liegend. 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 μm) 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 μm). 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.

Lebensbedrohliche Mundbodenblutung nach Implantatinsertion im Unterkieferseitenzahnbereich

Implantologisch-chirurgische Maßnahmen im Rahmen implantatprothetischer Eingriffe werden in der Zahnarztpraxis häufig durchgeführt. Intraoperative Komplikationen kommen bei diesen Operationen relativ selten vor und können aufgrund einer sorgfältigen Vorbereitung des Patienten weitestgehend vermieden werden. Nicht alle Risiken sind jedoch a priori erkennbar, denn anatomische Besonderheiten wie z. B. Variationen der Gefäßversorgung können nicht immer diagnostisch erfasst werden. Im vorliegenden Fallbericht (männlich, 60 Jahre) wird eine lebensbedrohliche Nachblutung vorgestellt, die während einer Implantatinsertion im rechten Unterkieferseitenzahnbereich aufgetreten ist. Eine lokale Blutstillung war nicht möglich, sodass eine extraorale Unterbindung erforderlich war. Dabei wurde ein untypischer Verlauf der A. submentalis, einem Abgang der A. facialis direkt unterhalb des Unterkieferrands, festgestellt. Anhand dieses Fallbeispiels wird die international verfügbare Literatur zu diesem Thema diskutiert. 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.

Röntgenspektrometrischer Vergleich der aktuell verfügbaren Knochenersatzmaterialien

Einleitung: Die kristalline Struktur von Knochenersatzmaterialien wie Hydroxylapatitkeramiken (HA) oder Trikalziumphosphatkeramiken (TCP) beeinflußt deren physikalische und sicher auch biologische Eigenschaften. Unterschiedliches Löslichkeitsverhalten von synthetischem und biologischem HA scheinen mit unterschiedlichen Ergebnissen in der Röntgenpulverdiffraktometrie (RDX), einem Routineverfahren der Materialwissenschaften [2, 6] zur Analyse kristalliner Strukturen, korreliert zu sein [1]. Vergleichende RDX-Analysen von TCP liegen in der einschlägigen Literatur nicht vor. Best et al. [4] unterstrichen in jüngster Zeit die Bedeutung der Charakterisierung der Knochenersatzmaterialien zum Verständnis der Resorptionsmechanismen [4]. Fragestellung: Ausmaß und Qualität der Kristallisation verschiedener z. Z. verfügbarer Knochenersatzmaterialien wurden mittels RDX-Analyse bestimmt. Material und Methoden: Die verwendeten Materialien wurden in 3 Gruppen eingeteilt: Hydroxylapatitkeramiken, Trikalziumphosphatkeramiken und Biogläser. Anhand der mittels Pulverdiffraktometer gewonnenen Intensitätsspektren können die Materialien hinsichtlich ihrer Zusammensetzung und Kristallisation charakterisiert werden. Ergebnisse: Die HA-Materialien (bis auf Algipore) scheinen monophasige Produkte zu sein, wobei nur Ceros80 und Endobone eine hohe Kristallisation aufweisen. Auch die TCP-Produkte Biobase und Cerasorb sind nahezu monophasig, während Ceros82 aus einer Mischung von 30% HA und 70% β-TCP zu bestehen scheint. Alle TCP weisen einen hohen Kristallisationsgrad auf. Die Biogläser zeigten erwartungsgemäß keine kristallinen Strukturen. Diskussion: Die möglichen Ursachen der inhomogenen Kristallisation der untersuchten Materialien reichen von der Zusammensetzung aus kleinen Einzelkristalliten über Fremdioneneinschlüsse zu defizitären Apatiten durch Kalziumkarbonatbeimengungen. Deren Bedeutung für das biologische Verhalten ist nicht geklärt. Resümee: Es fanden sich Unterschiede zwischen den untersuchten Materialien, deren Bedeutung für das biologische Verhalten nicht geklärt ist. Weiterführende Untersuchungen sind erforderlich, um diese Eigenschaften mit dem klinischen Verhalten zu korrelieren. 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 mineralogy [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% β-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 neccesary to correlate the characteristics of the materials to the clinical outcome.

Fracture Strength of Monolithic All-Ceramic Crowns on Titanium Implant Abutments.

PURPOSE The fracture strengths of all-ceramic crowns cemented on titanium implant abutments may vary depending on crown materials and luting agents. The purpose of this study was to examine differences in fracture strength among crowns cemented on implant abutments using crowns made of seven different monolithic ceramic materials and five different luting agents. MATERIALS AND METHODS In total, 525 crowns (75 each of Vita Mark II, feldspathic ceramic [FSC]; Ivoclar Empress CAD, leucite-reinforced glass ceramic [LrGC]; Ivoclar e.max CAD, lithium disilicate [LiDS]; Vita Suprinity, presintered zirconia-reinforced lithium silicate ceramic [PSZirLS]; Vita Enamic, polymer-reinforced fine-structure feldspathic ceramic [PolyFSP], Lava Ultimate; resin nanoceramic [ResNC], Celtra Duo; fully crystallized zirconia-reinforced lithium silicate [FcZirLS]) were milled using a CAD/CAM system. The inner surfaces of the crowns were etched and silanized. Titanium implant abutments were fixed on implant analogs, and airborne-particle abrasion was used on their exterior specific adhesion surfaces (Al2O3, 50 μm). Then, the abutments were degreased and silanized. The crowns were cemented on the implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, GC FujiCEM, Panavia 2.0). After thermocycling for 5,000 cycles (5 to 55°C, 30 seconds dwell time), the crowns were subjected to fracture strength testing under static load using a universal testing machine. Statistical analyses were performed using analysis of variance (α = .0002) and the Bonferroni correction. RESULTS No significant difference among the luting agents was found using the different all-ceramic materials. Ceramic materials LiDS, PSZirLS, PolyFSP, and ResNC showed significantly higher fracture strength values compared with FSC, FcZirLS, and LrGC. The PSZirLS especially showed significantly better results. CONCLUSION Within the limitations of this study, fracture strength was not differentially affected by the various luting agents. However, the fracture strength was significantly higher for PSZirLS, PolyFSP, ResNC, and LiDS ceramics than for the FSP, LrGC, and the FcZirLS ceramic with all luting agents tested.

Bone healing with or without platelet-rich plasma around four different dental implant surfaces in beagle dogs.

PURPOSE Surface development is one of the major aims in dental implant engineering. Additive application of substances could possibly improve the new bone formation around dental implants. The present study evaluated the bone reaction on four different implant surfaces with or without platelet-rich plasma (PRP). MATERIALS AND METHODS Four self-tapping titanium screw implants (Brånemark MK III [Nobel Biocare, Göteborg, Sweden], Osseotite [3i, Miami, FL, USA], Xive [Densply Friadent, Mannheim, Germany], and Compress [IGfZ eG, Diez, Germany]) with different surfaces were inserted in each hemimandible of 12 female beagle dogs; the implant positions and the application of PRP were randomized. After intravital fluorochrome staining, sacrifices and biopsies harvesting were performed after 6 weeks (five dogs; one dog died before) and 12 weeks (six dogs) and the respective specimens were analyzed. RESULTS The only significant difference in bone remodeling was found for the Compress implants with increased bone formation compared with the Brånemark implants at 12 weeks (sign test, p = .03). Comparing the histological and histomorphometric specimens of all other implant surfaces with respect to peri-implant bone remodeling and the resulting bone-implant contact rates (BICRs), no statistically significant differences were seen in the PRP or non-PRP groups (sign test, all p values ≥ .063). CONCLUSIONS This study found no significant differences in the BICR for roughened implant surfaces compared with machined surfaces. In this animal model, the addition of PRP did not demonstrate evidence of faster bone formation or the resulting BICR.

Erfolgskriterien in der Implantologie

Hintergrund. Für die Erfolgsdefinition dentaler Implantate gibt es bis heute keinen allgemeingültigen Konsens, obwohl international verschiedene Kriterienvorschläge aufgestellt wurden, die den Erfolg mittels klinischer und röntgenologischer Kontrollparameter bewerten. Ziel dieser Studie war es, an einem eigenem Patientenkollektiv 5 häufig angewendete Erfolgskriterienvorschläge (Albrektsson-Kriterien, Jahn-d’Hoedt-Kriterien, Buser-Kriterien, NIH-Kriterien, Naert-Kriterien) hinsichtlich ihrer klinischen Wertigkeit zu vergleichen. Methode. In einer speziellen klinischen Nachuntersuchung wurden 508 Implantate (Astra, Frialit-2, IMZ-TwinPlus und ITI) untersucht und eine subjektive Bewertung der Implantate durch die Patienten vorgenommen. Im Anschluss erfolgte eine Erfolgsanalyse (In-situ-Rate, Kaplan-Meier-Auswertung, Erfolgskriterien). Ergebnisse. Bei einer durchschnittlichen Liegedauer von 3,5 Jahren lag die In-situ-Rate aller eingeschlossenen Implantate bei 95%, die Kaplan-Meier-Schätzung ergab eine Überlebenswahrscheinlichkeit von 93% nach 6 Jahren. Bei Anlage der Erfolgskriterien ergaben sich unterschiedliche Ergebnisse (Albrektsson-Kriterien 88%, Naert-Kriterien 89%, NIH-Kriterien 85%, Buser-Kriterien 88%, Jahn-d’Hoedt-Kriterien 75%). Diskussion. Bei zunehmender Bedeutung der Qualitätssicherung in der Medizin scheint es erforderlich, sich in Zukunft auf Standards zu einigen, die einen zuverlässigen Vergleich von Implantaterfolgen erlauben. 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 d´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.

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. Heerfordts 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 Heerfordts syndrome and a review of the literature covering different aspects of sarcoidosis.