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Pekka Vallittu

Publications and source records attributed to Pekka Vallittu.

8 recordsLinked to original sources
PubMed2006

Sol-gel derived aluminosilicate coatings on alumina as substrate for osteoblasts.

Rat bone marrow stromal cell differentiation on aluminosilicate 3Al(2)O(3)-2SiO(2) coatings was investigated. Thin ceramic coatings were prepared on alpha-alumina substrates by the sol-gel process and calcined in order to establish an amorphous aluminosilicate ceramic phase with and without nanosized transitional mullite crystals. In addition, coatings of thermally sprayed aluminosilicate and diphasic gamma-alumina-silica nanosized colloids were prepared. Cell culture testing by rat osteoblasts showed good biocompatibility for aluminosilicates with sustained normal osteoblast functions. Despite mutual disparities in physical and chemical nanostructures, the culture findings suggested fairly similar osteoblast response to all tested coatings. The results suggest that topographical frequency parameters and chemical uniformity are important parameters in determining the best conditions for osteoblasts on sol-gel derived aluminosilicate materials.

Aluminum Oxide↗
PubMed2005

Early plaque formation on fibre-reinforced composites in vivo.

In the present study, two different fibre-reinforced composites (FRCs) (glass and polyethylene FRC), dental ceramic and restorative composite were compared with respect to early plaque formation in vivo. Disc-shaped specimens were randomly distributed among the upper first and second molars of 14 healthy adult volunteers. Plaque samples were collected 24 h after the attachment of the specimens. Mutans streptococci (MS), non-mutans streptococci and total facultative bacteria were cultured. The plaque recovered from polyethylene FRC harboured significantly more MS than the plaque of ceramic, restorative composite and glass FRC. For the counts of non-mutans streptococci and total facultative bacteria, polyethylene FRC showed the highest counts, and ceramic showed a trend towards lower counts. The amount of plaque accumulation showed an association to the earlier reported surface roughness values of the studied materials. It was concluded that in the oral environment, polyethylene FRC promotes plaque accumulation and adhesion of MS more than glass FRC, restorative composite and dental ceramic. Glass FRC resembles restorative composite with respect to plaque accumulation and the adherence of MS.

Adult↗
PubMed2005

Synthesis and characterization of polyamide of trans-4-hydroxy-L-proline used as porogen filler in acrylic bone cement.

The aim of this study was to synthesize on a larger scale, an experimental polyamide based on an amino acid of trans-4-hydroxy-L-proline. The polyamide of trans-4-hydroxy-L-proline has been used as porogen filler (i.e., a hydrophilic pore generating material) in nondegradable acrylic bone cement. In in vitro studies, this hydrophilic filling component has been shown to form porosity within the acrylic bone cement in an aqueous environment. The formation of in situ porosity in the acrylic polymer matrix is believed to improve the fixation between the cement and the living bone. Namely, a porous structure can support bone ingrowth and strengthen the mechanical connection between the acrylic bone cement and the bone. The monomer, trans-4-hydroxy-L-proline methyl ester, was prepared from trans-4-hydroxy-L-proline by means of two steps, and the monomer was then polymerized to polyamide of trans-4-hydroxy-L-proline. The polymerization was carried out using a melt polycondensation method. The molecular weights (M(psi)) of the produced polyamides were between 1800 and 3600. The products were characterized by FTIR and (1)H-NMR spectroscopy.

Hydroxyproline↗
PubMed2005

[Effect of occlusal therapy with FRC splint on periodontal parameters in maintenance phase].

The purpose of this study was to evaluate the changes of the periodontal parameters of mobile, but splinted teeth with intracoronal fiber reinforced composite and compare to non-mobile teeth in maintenance phase. We splinted 73 teeth (29 non-mobile, 44 mobile) in 18 cases. The periodontal parameters - probing depth, gingival index (Loe-Silness, 1964), plaque index (Silness-Loe, 1965) - were monitored clinically immediately, 1 year and 2 years after complete periodontal treatment. There were scored 69 treated teeth after 1 year and 37 treated teeth after 2 years. Statistical comparisons were performed using Wilcoxon test for two related parameters and Mann-Whitney U test for two independent parameters in the software package SPSS 11.0 for Windows (SPSS, Chicago, IL, USA). There was not mobility recorded at splinted teeth neither after treatment immediately nor at recall visits. The periodontal parameters demonstrated no significant changes of probing depth (-0,08 +/- 0,41, 0,05 +/- 0,51) and gingival index (-0,32 +/- 0,79, -0,32 +/- 0,75) 1 and 2 years after complete therapy. There was significant decrease in plaque index (-0,77 +/- 0,43, -0,36 +/- 0,55) measured at recall visits. No significant differences were detected between the mobile and the non-mobile groups in all parameters. No significant correlation between changes of gingival index and plaque index was determined. The intracoronal FRC splint do not obstruct the individual and professional oral hygiene. The stabilize of mobile teeth allow the same healing like a non-mobile teeth.

Adult↗
PubMed2004

Bonding of composite resin luting cement to fiber-reinforced composite root canal posts.

PURPOSE: The aim of this study was to compare bonding of composite resin luting cement to a fiber-reinforced composite (FRC) root canal post with either a cross-linked or a semi-interpenetrating polymer network (IPN) polymer matrix. MATERIALS AND METHODS: Four different types of prefabricated FRC posts with a cross-linked polymer matrix and two types of FRC posts with a semi-IPN polymer matrix which were individually formed were tested. Serrated titanium posts served as the reference. An auto-polymerizing resin luting cement was used for cementing the posts into the holes of composite resin disks. The pull-out force was measured using a universal testing machine after the post/cement/disk system had been stored dry or thermocycled (5 degrees C/55 degrees C, 6000x) in water. The bonding sites of the posts were examined with SEM. RESULTS: The FRC posts with a semi-IPN polymer matrix gave significantly higher pull-out force values than the prefabricated FRC posts with a smooth surface and a cross-linked polymer matrix (p < 0.004). The highest pull-out force was obtained with serrated titanium posts. Both the type of FRC post and thermocycling had a significant effect on the pull-out force (n = 8, ANOVA p < 0.001 and p < 0.007, respectively). SEM photomicrographs confirmed the results. CONCLUSION: This study showed that FRC posts with a semi-IPN polymer matrix bonded better to composite resin luting cement than did prefabricated FRC posts with a cross-linked polymer matrix, although their pull-out force was not as high as that of the mechanically interlocked serrated titanium posts.

Acrylic Resins↗
PubMedDate not supplied

Consensus statement on fiber-reinforced polymers: current status, future directions, and how they can be used to enhance dental care.

The Second Scientific Fibre Reinforcement Symposium was held in Nijmegen, The Netherlands, on October 13th, 2001. The participants were invited speakers with extensive scientific and clinical backgrounds in glass fiber and polyethylene fiber research. The symposium reports focused on four areas of fiber reinforcement research: materials development, laboratory testing, clinical systems development, and clinical data. The consensus reached on the current status and future directions of this technology is reported here.

Dental Materials↗