Papers by Author: Teemu Tirri

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Authors: Sari Tuusa, Matti Peltola, Teemu Tirri, Lippo Lassila, Pekka K. Vallittu
Abstract: In these studies, E-glass-fibre-reinforced composite (FRC) implants with photopolymerisable resin systems and bioactive glass granules (BAG) were evaluated as a reconstructive material in the critical size bone defects made to rabbits’ calvarial bones. In the first study, a new experimental resin system, DD1/MMA/BDDMA, was used to impregnate the doubleveil FRC-implants, while in the second study, a commercial resin system composed of BisGMA/MMA/PMMA was used in impregnation. These double-veil FRC-implants were coated with bioactive glass granules (BAG, 315-500 0m). In the second study, an experimental FRC consisting of two laminates of woven fibres, was also tested as an implant material. These implants were filled with BAG-granules and pure fused quartz fibers (Quartzel wool). In the first study, implantation time was 4 or 12 weeks, while in the second study, it was 12 weeks for both the implant types. Results: In the first study, the healing of the defects had started in the form of new bone growth from the defect margins, as well as small islands of woven bone in the middle of the defect, at 4 weeks postoperatively. Ingrowth of dense connective tissue into the pores of the implant was widely seen. At 12 weeks postoperatively, more bony islands were seen as compared to the animals studied at 4 weeks. Part of the newly formed bone had an appearance of lamellar structure. The porous structures of the implant were deeply filled with fibroconnective tissue. Ingrowth of maturing bone to the implant structures was occasionally seen. The inflammatory reaction was moderate, and was mostly found inside the upper part of the implant. In the second study, inflammatory reactions caused by both types of the FRC implants were very slight. Small amount of new bone had started to grow from the defect margins in doulble-veil implanted defects. No ingrowth of connective tissues or new bone formation was seen inside these implants. Instead, both the connective tissues and newly formed, mineralizing bone were seen inside the experimental double-laminate implants. SiO2-fibres seemed to cause moderate inflammatory reaction inside the implants, while BAG granules did not. In both the study groups, the brain tissue was oedemic, but no obvious serious damage was found. Conclusions: The structural properties of the FRC-implants had an influence on the healing process of the bone defect. BAG, as a constituent of the FRCimplants, enhanced the bone formation process. After some modifications to the properties of the FRC, this type of implant has possibilities to become one material alternative in clinical bone defect reconstruction at the craniofacial area in the future.
Authors: Allan Aho, Teemu Tirri, Jukka Seppälä, J. Rich, N. Strandberg, T. Jaakkola, Timo Närhi, J. Kukkonen
Authors: Timo Närhi, Teemu Tirri, J. Rich, Jukka Seppälä
Authors: Mervi Puska, Allan Aho, Teemu Tirri, Antti Yli-Urpo, Minna Vaahtio, Pekka K. Vallittu
Authors: Matti Peltola, Kalle Aitasalo, Teemu Tirri, Jami Rekola, A. Puntala
Abstract: Successful craniofacial reconstruction needs both a well-known and a reliable reconstruction material. However, there is often a lack of long-term knowledge of the tissue reactions and healing process in the human body. In this study, frontal sinus obliterations with bovine bone natural hydroxyapatite derivative (BHA), synthetic bioactive glass S53P4 (BAG) and hydroxyapatite cement (HAC) were investigated with clinical, histologic, scanning electron microscopic (SEM) and energy dispersive x-ray analysis (EDXA) 27, 12 and 3 years postoperatively. The aim was to determine the long-term clinical biocompatibility of the used materials. Histologic studies revealed bone formation with BHA particles and lamellar bone with BAG granule remnants in close contact to the new bone formation. In HAC reconstruction there was scattered fibroconnective tissue growth without new bone formation in the surface of HAC implantation. Neither foreign body reaction nor any abnormal findings were seen. SEM studies revealed a CaP layer on the surface of BAG granule remnants. In EDXA studies, composition profiles showed Ca-, P- and Si- rich layers on the BAG granule surface. No differences were found in CaO and P2O5 levels between BHA granules and HAC implantation and the surrounding bone. All investigated biomaterials were well tolerated in long-term applications.
Authors: Teemu Tirri, T. Jaakkola, Timo Närhi, J. Rich, Jukka Seppälä, Antti Yli-Urpo
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