Emeka Peter

Abstract Objectives: An animal study was carried out to investigate the influence of platelet-rich plasma (PRP) on the regeneration of bony defects.Material and methods: Critical-size defects in the forehead region of a mini-pig were filled with randomly distributed combinations of autogenous bone, tricalcium-phosphate granules (CeraSorb™), bovine spongious blocks (BioOss™) and a bovine bone inducing collagenous sponge (Colloss™) with and without PRP in two preparations (Cusasan, 3i). The animals were killed after 2, 4 and 12 weeks. The specimens were evaluated microradiographically and immunohistologically.Results: Autologous bone (38±9.9%) and Colloss (52.6±4.0%) showed the highest remineralization rates at 2 weeks. The initial high expression of BMP-2 in the Colloss®-group gives evidence of an early initiation of bony regeneration. At 2 weeks PRP ad modum 3i was able to enhance bone healing significantly (P=0.028) only when applied in combination with autogenous bone (62.8±1.6%). Four weeks after surgery, both PRP preparations did no longer increase bony regeneration in the autogenous groups. The osteoconductive effect of Bio-Oss™ (38.7±5.5%) and CeraSorb™ (41±4.9%) was remarkable as well 4 weeks after surgery. Nevertheless, the addition of PRP hardly influenced bony regeneration, ceramic degradation or cytokine expression when bone substitutes were applied. At 12 weeks, the level of reossification had adjusted similarly in all groups.Conclusion: PRP did not add additional benefit when xenogenic bone substitutes were used. However, a significant effect on bone regeneration was found in the autogenous group initially when PRP is added.Une étude animale a été effectuée pour étudier l'influence du plasma-riche en plaquettes (PRP) sur la régénération de lésions osseuses. Des lésions de dimensions critiques créées dans le front de cochons nains ont été comblées par des combinaisons randomisées d'os autogène, de granules de tri-calcium-phosphate (CeraSorbTM), de blocs spongieux bovins (BioOssTM) et une éponge collagène induisant l'os bovin (CollossTM) avec ou sans PRP dans les deux préparations (Cusasan, 3i). Les animaux ont été tués après deux, quatre et douze semaines. Les échantillons ont étéévalués micro-radiographiquement et immunohistologiquement. L'os autogène (38±9,9%) et Colloss (52,6±4,0%) apportaient les taux de reminéralisation les plus importants à deux semaines. La haute expression initiale de BMP-2 dans le groupe Colloss® donne une preuve d'une initiation précoce de la régénération osseuse. A deux semaines PRP ad modum 3i était capable d'augmenter la guérison osseuse de manière significative (p=0,028) mais seulement lorsqu'il était appliqué en association avec l'os autogène (62,8±1,6%). Quatre semaines après la chirurgie les deux préparations PRP n'augmentaient plus la régénération osseuse dans les groupes autogènes. L'effet ostéoconductif du Bio-OssTM (38,7±5,5%) et du CeraSorbTM (41±4,9%) était remarquable aussi quatre semaines après la chirurgie. Cependant, l'addition de PRP n'influençait que très peu la régénération osseuse, la dégradation de la céramique ou l'expression de la cytokine lorsque les substituts osseux étaient utilisés. A douze semaines le niveau de la réossification s'était ajusté de façon identique dans tous les groupes. Le plasma riche en plaquettes n'apportait pas un effet bénéfique additionnel lorsque des substituts osseux xénogéniques étaient utilisés. Cependant, un effet significatif sur la régénération osseuse était constaté dans le groupe autogène au départ lorsque PRP était ajouté.Der Einfluss eines plättchenangereicherten Plasmas auf die Knochenheilung, wenn Defekten von kritischer Grösse mit einem Gemisch aus autologem Knochen und Ersatzstoffen angefüllt werden - ein Tierexperiment.Ziel: Man führte zur Untersuchung des Einflusses eines mit Plättchen angereicherten Plasmas (PRP) auf die Regeneration von Knochendefekten eine Tierstudie durch.Material und Methode: Nach einer rein zufälligen Auswahl füllte man Knochendefekte von kritischer Grösse im vorderen Schädelbereich eines Meerschweinchens mit autologem Knochen, Körnern aus Tri-Calcium-Phosphat (CeraSorb®), Spongiosablöcken aus Rinderknochen (BioOss®) oder einem aus Rinderknochen gewonnenen Kollagenschwamm (Colloss®) auf. All diese Präparate waren entweder mit PRP in zwei verschiedenen Herstellungsarten (Cusasan, 3i) angereichert, oder enthielten kein PRP. Man opferte die Tiere nach 2, 4 und 12 Wochen. Die Präparate wurden dann microradiographisch und immunohistologisch untersucht.Resultate: Nach zwei Wochen zeigten der autologe Knochen (38+9.9%) und Colloss (52.6+4.0%) die höchsten Mineralisationsrate. Die initial sehr hohe Ausscheidung von BMP-2 in der Colloss®-Gruppe ist Indiz für das sehr frühe Einsetzen der Knochenregeneration. Nach zwei Wochen war das PRP (ad modum 3i) nur dann in der Lage die Knochenheilung signifikant zu steigern (p=0.028), wenn es in Kombination mit autologem Knochen angewendet worden war (62.8+1.6%). Vier Wochen nach der Chirurgie vermochte in der Gruppe mit autologem Knochen keines der zwei PRP-Präparate die Knochenregeneration weiter zu beschleunigen. Der osteokonduktive Einfluss von Bio-Oss® (38.7+5.5%) und CeraSorb® (41+4.9%) war auch vier Wochen nach dem chirurgischen Eingriff noch beachtlich. Der Zusatz von PRP zu den Knochenersatzstoffen beeinflusste die Knochenregeneration, den Abbau der Keramikmasse oder die Ausscheidung von Zytokinen kaum. Nach 12 Wochen war der Stand der Reossifikation in allen Gruppen nahezu identisch.Zusammenfassung: Ein plättchenangereichertes Plasma brachte bei kombiniertem Einsatz mit einem Xenotransplantat keine zusätzlichen Vorteile. Man konnte jedoch mit dem Zusatz von PRP zum autologem Knochen in der Anfangsphase der Heilung einen signifikanten Einfluss auf die Knochenregeneration feststellen.Objetivos: Se llevó a cabo un estudio animal para investigar la influencia del plasma rico en plaquetas (PRP) en la regeneración de defectos óseos. Material y métodos: Se rellenaron defectos de tamaño crítico en la región frontal de un mini-cerdo con combinaciones distribuidas aleatoriamente de hueso autógeno, gránulos de fosfato tricálcico (CeraSorbTM), bloques de esponjosa bovina (BioOssTM) y esponjas colágenas bovinas inductoras óseas (CollossTM) con y sin PRP en dos preparaciones (Cusasan, 3i). Los animales se sacrificaron tras 2, 4 y 12 semanas. Los especímenes se evaluaron microrradiograficamente e inmunohistologicamente. Resultados: El hueso autólogo (38±9.9%) y el Colloss (52.6±4.0%) mostraron los índices de remineralización mas altos a las dos semanas. La expresión inicial elevada de BMP-2 en el grupo Colloss® da una evidencia de una iniciación temprana de regeneración ósea. A las dos semanas el PRP ad modum 3i fue capaz de realzar la cicatrización ósea significativamente (p=0.028) solo cuando se aplicó en combinación con hueso autógeno (62.8±1.6%). Cuatro semanas tras la cirugía ambas preparaciones de PRP no aumentaron más la regeneración ósea en los grupos autógenos. El efecto osteoconductivo del BioOssTM (38.7±5.5%) y del CeraSorbTM (41±4.9) fue notable también a las cuatro semanas tras la cirugía. Sin embargo, la adición de PRP difícilmente influyó en la regeneración ósea, en la degradación cerámica o en la expresión citoquina cuando se aplicaron sustitutos óseos. A las 12 semanas el nivel de reosificación se había ajustado similarmente en todos los grupos. Conclusión: El plasma rico en plaquetas no añadió ningún beneficio adicional cuando se usaron sustitutos óseos xenogénicos. De todos modos, se encontró un efecto significativo en la regeneración ósea en el grupo autógeno inicialmente cuando se añade PRP.

300 Rinderinzisivi wurden je zur Hälfte mit zwei verschiedenen Metallbrackets mit jeweils unterschiedlicher Bracketbasis (Netzbasis bzw. photogeätzter Basis) beklebt. Zum Kleben wurden zwei Fluorid abgebende, lichthärtende Materialien verwendet: das Komposit Sequence® und der Glasionomerzement Photac®-Fil. Als Vergleichsgruppe diente Concise® ein autopolymerisierendes Zwei-Komponenten-Komposit. Es wurden sechs Versuchsgruppen mit jeweils 50 Zähnen gebildet. Die Haftfestigkeit wurde in Abzugsversuchen bestimmt und der Bruchverlauf visuell analysiert. Sequence® zeigte eine vergleichbar gute Haftfestigkeit wie Concise®. Photac®-Fil erreichte nur eine halb so große Haftfestigkeit wie die beiden Komposite, so daß ein klinischer Einsatz kritisch zu beurteilen ist. Sequence® und Concise® erzielten an der photogeätzten Basis signifikant geringere Werte als an der Netzbasis und wiesen ein vergleichbares Bruchverhalten auf. Die Bruchstelle lag überwiegend am Übergang Komposit/Bracket, während der Verbund Schmelz/Komposit sich als sehr stabil erwies. Bei photogeätzter Basis waren bei beiden Kompositen signifikant weniger Abrisse am Schmelz zu beobachten als an der Netzbasis. Deutliche Unterschiede im Bruchverhalten zeigte Photac®-Fil. An der photogeätzten Basis lag der Schwachpunkt des Verbundes am Übergang Schmelz/Glasionomerzement, während an der Netzbasis ein den beiden Kompositen ähnliches Bruchverhalten zu beobachten war. Vor einem klinischen Einsatz von Sequence® und Photac®-Fil sind noch die tatsächliche Fluoridfreisetzung und ihr Verhalten nach einer Temperaturwechselbelastung zu untersuchen. Three hundred bovine incisors, which were divided into 6 groups of 50 teeth each, were used in this study. Two types of metal brackets, 1 with a conventional foil mesh base and the other with a photo etched Micro-Loc base, were adhered to the teeth with 3 different bonding agents, namely, Sequence™, a fluoride releasing, light activated composite, Photac-Fil™, a light hardened glasionomer cement, and, in the control group, Concise™, a 2-component composite which hardens chemically. A universal testing machine was employed to test tensile bonding strength and the site of failure was visually determined and analyzed. The study showed that Sequence™ can be considered as a qualitatively equal alternative to Concise™. Both composites demonstrate equal tensile bonding strength. The use of Photac-Fil™, the light hardened glasionomer bonding agent, cannot be recommended. It posses significantly less tensile bonding strength than the other 2 bonding agents. Sequence™ and Concise™, which showed better results with the brackets with conventional foil mesh base than with the brackets with photo etched Micro-Loc base, had no significant differences in their failure sites. The interface of the composite with the bracket was the main failure site. Both composites demonstrated a significantly reduced rate of failure at the interface of the composite with the enamel, when they were used with the brackets with the Micro-Loc base. This differed from the failure site of Photac-Fil™, when the photo etched base was used. With Photac-Fil™ the main site of failure came at the interface of the enamel with this glasionomer cement. In use with the conventional foil mesh, failure took place primarily at the interface of the Photac-Fil™ with the bracket. Before Sequence™ and Photac-Fil™ can be used in orthodontic practice, the 2 bonding systems' actual release of fluoride over time and their reaction under conditions of temperature change remain to be studied.

Highly porous titanium structures are widely used for maxillofacial and orthopedic surgery because of their excellent mechanical properties similar to those of human bone and their facilitation of bone ingrowth. In contrast to common methods, the generation of porous titaniumproducts by selective electron beam melting (SEBM), an additive manufacturing technology, overcomes difficulties concerning the extreme chemical affinity of liquid titanium to atmospheric gases which consequently leads to strongly reduced ductility of the metal. The purpose of this study was to assess the suitability of a smooth compact and a porous Ti-6Al-4V structure directly produced by the SEBM process as scaffolds for bone formation. SEBM-processed titanium implants were placed into defects in the frontal skull of 15 domestic pigs. To evaluate the direct contact between bone and implant surfaces and to assess the ingrowth of osseous tissue into the porous structure, microradiographs and histomorphometric analyses were performed 14, 30, and 60 days after surgery. Bone ingrowth increased significantly during the period of this study. After 14 days the most outer regions of the implants were already filled with newly formed bone tissue (around 14%). After 30 days the bone volume inside the implants reached almost 30% and after 60 days abundant bone formation inside the implants attained 46%. During the study only scarce bone–implant contact was found around all implants, which did not exceed 9% around compact specimens and 6% around porous specimens after 60 days. This work demonstrates that highly porous titanium implants with excellent interconnectivity manufactured using the SEBM method are suitable scaffolds for bone ingrowth. This technique is a good candidate for orthopedic and maxillofacial applications. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010

Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts. Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1=poor; 3=excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n=26) with a 5-point scale (1=poor; 5=excellent), CTA source data served as the reference. Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries. Excellent bone suppression could be achieved, DE imaging with 100 and 140kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.

Purpose To determine whether ras-activated cascades lead to activation of ets-1 expression in sequential histological stages of oral oncogenesis in an experimental animal model. Methods Thirty-seven Syrian golden hamsters were divided into three experimental groups (A, B, C) and one control group. The hamsters’ buccal pouches in experimental groups were treated with 0.5% 9, 10-dimethyl-1, 2-benzanthracene (DMBA) for 14 weeks and were excised at 10, 14, 19 weeks, respectively. The biopsies were classified pathologically (normal mucosa, hyperkeratosis, hyperplasia, dysplasia, early invasion, well and moderately differentiated carcinoma) and studied immunohistochemically. The two-tailed Student’s t test was performed for each animal group and for each histological category. Results The ets-1 expression increased in early stages of oral tumor formation and invasion. The expression of N-ras gradually decreased during oral oncogenesis, as previously observed with H-ras. Conclusions Neither N-ras nor H-ras affects ets-1 expression in contrast to other types of cancer in which N-ras and ets-1 are implicated in the same signalling pathway. Therefore, the existing pathway implicating these proteins might be somehow altered in oral cancer. It seems that ets-1 is a good prognostic marker for invasiveness and progression of oral cancer.

It has been the aim of the present prospective clinical study to assess the morbidity following the harvest of bone from the anterior and posterior ilium in elective preprosthetic augmentations. Fifty consecutive healthy patients (30 female, 20 male, mean age 52.5+/-9.3 years, range 31 years to 65 years) underwent augmentations of implant sites by iliac crest bone grafts. The bone harvest was carried out in 25 cases from the anterior and in 25 cases from the posterior ilium. The superficial sensory function of the skin was determined quantitatively preoperatively, 7 and 30 days after surgery with the 'Pain and Thermal Sensitivity' Test (PATH Test). On the same occasions subjective pain on a visual analogue scale (VAS) and gait disturbances were documented. In the PATH Test, for the innervation areas of the lateral femoral cutaneous nerve (LFCN) and the superior and middle cluneal nerves (SMCN) a significant impairment of the superficial sensory function could be found after 1 week and a significant tendency towards recovery after 1 month (warm stimulus(FCNpreop) 37.9+/-3.0 degrees C, warm stimulus(LFCNday7): 38.6+/-3.2 degrees C, warm stimulus(LFCNday30): 37.9+/-2.9 degrees C, P(LFCNwarmpreop/day7)=0.023,P(LFCNwarmpreop/day30) =0.886, warm stimulus(SMCNpreop): 36.1+/-2.4 degrees C, warm stimulus(SMCNday7): 36.6+/-2.3 degrees C, warm stimulus(SMCNday30): 36.3+/-4.0 degrees C,P(SMCNwarmpreop/day7) <0.0005,P(SMCNwarmpreop/day30) =0.086). Gait disturbances were seen in seven patients after anterior and in three patients after posterior bone harvest 7 days after surgery (P(gaitdisturbanceanterior/posterior)=0.123). After 1 month none of the patients of both groups showed gait disturbances any longer. The maximum subjective pain level was found on the second postoperative day in both groups. It was significantly higher for the anterior approach (VAS(anteriorday2) 7.0+/-1.5, VAS(posteriorday2) 5.5+/-1.8,P(VASanterior/posteriorday2) =0.004). At day 7 and at day 30, the pain levels did no longer differ significantly (VAS(anteriorday7) 3.7+/-1.4, VAS(posteriorday7) 3.2+/-1.6,P(VASanterior/posteriorday7) =0.165, VAS(anteriorday30) 1.4+/-0.7, VAS(posteriorday30) 1.4+/-0.8,P(VASanterior/posteriorday30) =0.724). Because of the lower morbidity of bone harvest from the posterior ilium in the early postoperative phase compared to the anterior approach it seems that it should be preferred in elective augmentation procedures.