The aim of this retrospective clinical study was to evaluate the survival and the occurrence of t... more The aim of this retrospective clinical study was to evaluate the survival and the occurrence of technical and biological complications of zirconia crowns and fixed dental prostheses made in the student clinic of Turku University, Finland, between April 2009 and September 2017. Materials and methods: Twenty-seven patients (19 female, 8 male), with zirconia crowns or FDPs, participated in the follow-up investigation. The mean age of patients was 64.6 years. Of the 40 restorations, 17 were single crowns and 23 FDPs. Twenty-seven restorations were anterior and 13 posterior. Restorations were investigated according to modified USPHS criteria. Results: The survival rate of zirconia restorations after 2-8 years (average 5.7 years) of clinical use was 95%. Survival rate of single crowns was 94.2% and of FDPs 95.7%, respectively. The overall complication rate was 26% for FDPs and 5.8% for crowns. One posterior crown was lost due to a vertical root fracture and one FDP showed a framework fracture. Veneering ceramic fractures were detected in 12% of all cases (0% for crowns and 22% for FDPs). Bleeding on probing was present in 38.1% of restored teeth and 13.9% of control teeth. Embrasure space was insufficient in 52% of zirconia FDPs and 81% of these restorations showed elevated BOP values. Conclusions: Zirconia crowns and FDPs survived well in this retrospective follow-up study. Chipping of veneering ceramic and bleeding on probing were the most common complications. Thick connector areas made according to material demands resulted in insufficient embrasure spaces and inflammation of marginal gingiva.
The soft tissue-implant interface requires the formation of epithelium and connective tissue seal... more The soft tissue-implant interface requires the formation of epithelium and connective tissue seal to hinder microbial infiltration and prevent epithelial down growth. Nanoporous titanium dioxide (TiO2) surface coatings have shown good potential for promoting soft tissue attachment to implant surfaces. However, the impact of their surface properties on the biological response of gingival cells needs further investigation. This systematic review aimed to investigate the cellular behavior of gingival cells on TiO2-implant abutment coatings based on in vitro studies. The review was performed to answer the question: “How does the surface characteristic of TiO2 coatings influence the gingival cell response in in vitro studies?”. A search in MEDLINE/PubMed and the web of science databases from 1990 to 2022 was performed using keywords. A quality assessment of the studies selected was performed using the SciRAP method. A total of 11 publications were selected from the 289 studies that fulfi...
Journal of Materials Science: Materials in Medicine, 2021
In vitro studies of implant-tissue attachment are primarily based on two-dimensional cell culture... more In vitro studies of implant-tissue attachment are primarily based on two-dimensional cell culture models, which fail to replicate the three-dimensional native human oral mucosal tissue completely. Thus, the present study aimed to describe a novel tissue culture model using pig mandibular block including alveolar bone and gingival soft tissues to evaluate the tissue attachment to titanium implant provided with hydrothermally induced TiO2 coating. Tissue attachment on TiO2 coated and non-coated implants were compared. Ti-6Al-4V alloy posts were used to function as implants that were inserted in five pig mandibles. Implants were delivered with two different surface treatments, non-coated (NC) titanium and hydrothermal induced TiO2 coated surfaces (HT). The tissue-implant specimens were cultured at an air/liquid interface for 7 and 14 days. The tissue-implant interface was analyzed by histological and immunohistochemical stainings. The microscopic evaluation suggests that pig tissue exp...
AimThe aim of this study was to evaluate the design of fiber-reinforced composite (FRC) on some m... more AimThe aim of this study was to evaluate the design of fiber-reinforced composite (FRC) on some mechanical properties of a dental implant.Methods and MaterialsFRC implants were fabricated using different polymerization conditions and designs of the glass-fiber structure. Specimens were tested with a cantilever bending test and a torsional test. The degree of monomer conversion (DC%) was measured using a Fourier transform infrared spectroscopy (FTIR).ResultsStatistical analysis showed significant differences between groups revealing mean fracture load values from 437 N to 1461 N. The mean torsional force in fracture varied from 0.01 to 1.66 Nm. The DC% varied from 50% to 90%.ConclusionThis study suggests by modifying the polymerization conditions and fiber orientation of FRC implants, the biomechanical properties of an FRC can be tailored to the needs of dental implants.CitationBallo AM, Lassila LV, Närhi TO, Vallittu PK.In vitroMechanical Testing of Glass Fiber-reinforced Composite ...
This study was designed to investigate the effect of nanostructured TiO2 coatings on human gingiv... more This study was designed to investigate the effect of nanostructured TiO2 coatings on human gingival fibroblast and to explore the influence of ultraviolet (UV) light on surface wettability and cellular response. Ti‐6Al‐4V titanium alloy discs (n = 96) were divided into three groups: a sol–gel‐derived MetAlive™ (MA) coating; hydrothermal (HT) coating; and a non‐coated (NC) group. Forty‐eight titanium substrates were further treated with UV light for 15 min. The water contact angles of the substrates were measured using the sessile drop method. Human gingival fibroblasts were used to evaluate the cell adhesion strength and cell proliferation on experimental surfaces. The strength of cell adhesion against enzymatic detachment was studied after 6 hr of adhesion using gentle trypsinization for 15 min at room temperature. A fluorescence microscope was used for cell imaging (Zeiss‐stereo‐lumar‐v12), and images were analyzed for cell counting, and the percentage of detached cells were calcu...
The International journal of oral & maxillofacial implants
The purpose of this retrospective study was to evaluate the clinical performance of and patients&... more The purpose of this retrospective study was to evaluate the clinical performance of and patients' satisfaction with maxillary overdentures retained by splinted and unsplinted implants. Patients who had been treated with maxillary implant-retained overdentures because of functional problems with conventional complete dentures were identified and invited to participate in the study. A total of 16 patients fulfilled the enrollment criteria and agreed to participate. Eleven patients were treated with bar-retained overdentures with 3 to 6 clips (mean follow-up 32 months), and 5 patients wore overdentures retained by 2 to 6 ball attachments (mean follow-up 54 months). All subjects were satisfied with their prostheses, and most subjects experienced improvement in their oral function after treatment with implant-retained overdentures. At the time of clinical examination, 92% (n = 77) of the 84 implants placed were functioning satisfactorily. The cumulative survival rate for the implants...
Summary In August 23–25, 2007, the Scandinavian Society for Prosthetic Dentistry in collaboratio... more Summary In August 23–25, 2007, the Scandinavian Society for Prosthetic Dentistry in collaboration with the Danish Society of Oral Implantology arranged a consensus conference on the topic ‘Implants and/or teeth’. It was preceded by a workshop in which eight focused questions were raised and answered in eight review articles using a systematic approach. Twenty‐eight academicians and clinicians discussed the eight review papers with the purpose to reach consensus on questions relevant for the topic. At the conference the consensus statements were presented as well as lectures based on the review articles. In this article the methods used at the consensus workshop are briefly described followed by the statements with comments.
ObjectivesAlthough titanium is commonly used as a favorable bone implant material due to its mech... more ObjectivesAlthough titanium is commonly used as a favorable bone implant material due to its mechanical properties, its bioactive and osteoconductive capacity is relatively low. Calcium phosphate ceramics, predominantly hydroxyapatite (HA), have been frequently used for coating purposes to improve the bioactive properties. In view of the suggested osteopromotive capacity of bioactive glasses (BGs), this study aimed to evaluate the effect of BG incorporation into HA coatings on implant performance in terms of bone contact and bone area.Materials and MethodsA total of 48 screw‐type titanium implants with magnetron sputter coatings containing different ratios of HA and BG (HA, HABGLow, and HABGHigh; n = 8) were placed into the mandible of 16 Beagle dogs. After 4 and 12 weeks, their performance was evaluated histologically and histomorphometrically. Peri‐implant bone area percentage (BA%) was determined in three zones (inner, 0–500 μm; middle, 500–1000 μm; and outer, 1000–1500 μm). Addi...
Monolithic zirconia prostheses are emerging as a promising option in the implant-based rehabilita... more Monolithic zirconia prostheses are emerging as a promising option in the implant-based rehabilitations of edentulous patients, yet their clinical performance is not fully documented. The purpose of this systematic review was to assess the clinical performance of complete-arch implant-supported monolithic zirconia fixed dental prostheses. The electronic databases PubMed, Science Direct, and Cochrane Library were searched for clinical studies on complete-arch implant-supported monolithic zirconia fixed dental prostheses. Human studies with a mean follow-up of at least 1 year and published in an English-language peer-reviewed journal up to June 2015 were included. Two independent examiners conducted the search and the review process. The search generated 903 titles. Eighteen qualifying studies were retrieved for full-text evaluation. Nine studies were included on the basis of preestablished criteria. Eight studies reported satisfactory clinical and esthetic outcomes. One study demonstrated prosthesis failure. Clinical studies are lacking on the long-term outcome of complete-arch implant-supported monolithic zirconia prostheses. Complete-arch dental implant restoration with monolithic zirconia is associated with high short-term success. Despite the many advantages and short-term favorable reports, studies of longer duration are necessary to validate the broad application of this therapy.
Dental materials : official publication of the Academy of Dental Materials, 2015
To evaluate the surface topography and optical properties of monolithic zirconia after immersion ... more To evaluate the surface topography and optical properties of monolithic zirconia after immersion in simulated gastric acid. Four partially stabilized (PSZ) and one fully stabilized (FSZ) zirconia materials were selected for the study: Prettau (PRT, Zirkonzahn), Zenostar (ZEN, Ivoclar), Bruxzir (BRX, Glidewell), Katana (KAT, Noritake) and FSZ Prettau Anterior (PRTA, Zirkonzahn). IPS e.max (Ivoclar) was used as a control. The specimens (10×10×1.2mm, n=5 per material) were cut, sintered, polished and cleaned before immersed in 5ml of simulated gastric acid solution (Hydrochloric acid (HCl) 0.06M, 0.113% solution in deionized distal water, pH 1.2) for 96h in a 37°C incubator. Specimens were weighed and examined for morphological changes under scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Surface roughness was evaluated by a confocal microscope. Surface gloss and translucency parameter (TP) values were determined by a reflection spectrophotom...
Streptococcus mutans is able to form a high-affinity biofilm on material surfaces. S. mutans has ... more Streptococcus mutans is able to form a high-affinity biofilm on material surfaces. S. mutans has also been detected around infected implants. Bioactive glasses have been shown to possess antibacterial effects against S. mutans and other microorganisms. This in vitrostudy was performed to investigate the influence of bioactive glass air-abrasion on S. mutans biofilm on sandblasted and acid etched titanium surfaces. Sandblasted and acid etched commercially pure titanium discs were used as substrates for bacteria (n=107). The discs were immersed in an S. mutans solution and incubated for 21 h to form S. mutans biofilm. Twenty colonized discs were subjected to air-abrasion with the Bioglass®45S5 (45S5 BAG), experimental zinc oxide containing bioactive glass (Zn4 BAG) and inert glass. After the abrasion, the discs were incubated for 5 h in an anaerobic chamber followed by an assessment of viable S. mutans cells. Surface morphology was evaluation using SEM (n=12). Thrombogenicity of the g...
Objective of this study was to develope low temperature sol-gel coatings for shape memory metal (... more Objective of this study was to develope low temperature sol-gel coatings for shape memory metal (NiTi) and evaluate their biocompatibility on NiTi suture material. A series of low temperature TiO 2 and TiO 2-SiO 2 sol-gel coatings were prepared on glass substrates. The silica content of TiO 2-SiO 2 coatings ranged from 0 to 30 mol%. The coatings were also prepared with polyethyleneglycol (PEG). The contact angle and photocatalytic activity measurements were used to evaluate the surface properties of the coatings. Stability of the coatings was tested in simulated body fluid (SBF). The TiO 2-SiO 2 90/10 film made with PEG was more hydrophilic, showed photocatalytic activity and was crack-free after the SBF test, thus it was chosen to animal experiment as a new experimental coating. Uncoated NiTi suture and the suture coated with high temperature TiO 2 were used as reference materials. NiTi sutures were inserted subcutaneously on the back of rat for four weeks. In routine histological examinations all materials showed good biocompatibility with mild inflammatory cell reaction. No significant differences in the soft tissue response among the materials were observed. Both the high and new low temperature processed sol-gel coatings remained attached on the sutures confirming the suitability of the coating technique on thin NiTi sutures.
In 1990, 364 elderly (76-86 years) inhabitants of Helsinki, Finland, attended a dental and oral e... more In 1990, 364 elderly (76-86 years) inhabitants of Helsinki, Finland, attended a dental and oral examination study that was conducted as part of the Helsinki Aging Study. In spring 1996, these subjects were recalled for a 5-year follow-up. Between the baseline and follow-up examinations, 114 (31%) subjects had deceased (86 women and 28 men), whereas 134 had either moved, were too ill, or refused to participate in the follow-up. Follow-up examination was conducted for 113 subjects (79 women and 34 men), with the participating rate being 46%. Five subjects became edentulous during the follow-up. Of the subjects, 61% had 1-32 teeth at follow-up. In these subjects, the mean number of teeth decreased from 14AE9 (-8AE3) to 13AE5 (-8AE6) (P < 0AE0001). Prosthetic status changed in 40% of the elderly dentate people: 25% received new prostheses whereas 15% lost prostheses that were not replaced. New fixed partial dentures were made in five maxillae and in nine mandibles during the follow-up. Acrylic removable partial dentures (ARPD) were most frequently used: 35% of dentate subjects had an ARPD. Subjects with removable prostheses had higher levels of salivary microbes and higher root caries incidence than those with natural teeth. Furthermore, the presence of removable prostheses at baseline, together with the male gender, was clearly associated with tooth loss during follow-up. This study indicates that fixed rather than removable prostheses should be used in elderly patients. The need for a removable denture ought to be carefully considered.
Journal of Biomedical Materials Research Part A, 2004
A firm bond between an implant and the surrounding soft tissue is important for the performance o... more A firm bond between an implant and the surrounding soft tissue is important for the performance of many medical devices (e.g., stents, canyls, and dental implants). In this study, the performance of nonresorbable and reactive sol-gel-derived nano-porous titania (TiO 2) coatings in a soft tissue environment was investigated. A direct attachment between the soft tissue and the sol-gel-derived titania coatings was found in vivo after 2 days of implantation, whereas the titanium control implants showed no evidence of soft tissue attachment. The coated implants were in immediate contact with the connective tissue, whereas the titanium controls formed a gap and a fibrous capsule on the implant-tissue interface. The good soft tissue attachment of titania coatings may result from their ability to initiate calcium phosphate nucleation and growth on their surfaces (although the formation of poorly crystalline bonelike apatite does not occur). Thus, the formation of a bonelike CaP layer is not crucial for their integration in soft tissue. The formation of bonelike apatite was hindered by the adsorption of proteins onto the initially formed amorphous calcium phosphate growth centers, thus preventing the dissolution/ reprecipitation processes required for the formation of poorly crystalline bonelike apatite. These findings might open novel application areas for sol-gel-derived titaniabased coatings.
Journal of Biomedical Materials Research Part A, 2009
Average scaffold pore sizes in the order of several hundred microns are generally required for ef... more Average scaffold pore sizes in the order of several hundred microns are generally required for efficient bone tissue ingrowth in vivo, whereas the culture of large bone engineering constructs in vitro can require bioreactor cultures to decrease diffusional constraints on the cells. In this study, we prepared poly(epsilon-caprolactone/D,L-lactide)-based scaffolds with continuous phase macroporosity using a novel CaCl(2) . 6H(2)O porogen agent. Osteogenic differentiation and scaffold colonization in rat bone marrow stromal cell cultures were compared in such polymer scaffolds, and in composites with 30 wt % bioactive glass filler. The effect of a rotating wall bioreactor culture on the cell response was also evaluated. Bioactive filler enhanced proliferation, early osteogenic differentiation, and mineralization of the cultured cells under static conditions. Dynamic cultures, in turn, resulted in decreased cell numbers and inhibition of the differentiation process irrespective of the scaffold type. This effect was ascribed to the harsh mechanical stresses caused by constant collisions of the scaffolds in the bioreactor vessels. However, cells were able to penetrate into the scaffold interior only under dynamic culture conditions. Thus, interconnected macroporosity is an essential, but not sufficient, condition to allow for full colonization of millimeter scale tissue engineering scaffolds in vitro.
The aim of this retrospective clinical study was to evaluate the survival and the occurrence of t... more The aim of this retrospective clinical study was to evaluate the survival and the occurrence of technical and biological complications of zirconia crowns and fixed dental prostheses made in the student clinic of Turku University, Finland, between April 2009 and September 2017. Materials and methods: Twenty-seven patients (19 female, 8 male), with zirconia crowns or FDPs, participated in the follow-up investigation. The mean age of patients was 64.6 years. Of the 40 restorations, 17 were single crowns and 23 FDPs. Twenty-seven restorations were anterior and 13 posterior. Restorations were investigated according to modified USPHS criteria. Results: The survival rate of zirconia restorations after 2-8 years (average 5.7 years) of clinical use was 95%. Survival rate of single crowns was 94.2% and of FDPs 95.7%, respectively. The overall complication rate was 26% for FDPs and 5.8% for crowns. One posterior crown was lost due to a vertical root fracture and one FDP showed a framework fracture. Veneering ceramic fractures were detected in 12% of all cases (0% for crowns and 22% for FDPs). Bleeding on probing was present in 38.1% of restored teeth and 13.9% of control teeth. Embrasure space was insufficient in 52% of zirconia FDPs and 81% of these restorations showed elevated BOP values. Conclusions: Zirconia crowns and FDPs survived well in this retrospective follow-up study. Chipping of veneering ceramic and bleeding on probing were the most common complications. Thick connector areas made according to material demands resulted in insufficient embrasure spaces and inflammation of marginal gingiva.
The soft tissue-implant interface requires the formation of epithelium and connective tissue seal... more The soft tissue-implant interface requires the formation of epithelium and connective tissue seal to hinder microbial infiltration and prevent epithelial down growth. Nanoporous titanium dioxide (TiO2) surface coatings have shown good potential for promoting soft tissue attachment to implant surfaces. However, the impact of their surface properties on the biological response of gingival cells needs further investigation. This systematic review aimed to investigate the cellular behavior of gingival cells on TiO2-implant abutment coatings based on in vitro studies. The review was performed to answer the question: “How does the surface characteristic of TiO2 coatings influence the gingival cell response in in vitro studies?”. A search in MEDLINE/PubMed and the web of science databases from 1990 to 2022 was performed using keywords. A quality assessment of the studies selected was performed using the SciRAP method. A total of 11 publications were selected from the 289 studies that fulfi...
Journal of Materials Science: Materials in Medicine, 2021
In vitro studies of implant-tissue attachment are primarily based on two-dimensional cell culture... more In vitro studies of implant-tissue attachment are primarily based on two-dimensional cell culture models, which fail to replicate the three-dimensional native human oral mucosal tissue completely. Thus, the present study aimed to describe a novel tissue culture model using pig mandibular block including alveolar bone and gingival soft tissues to evaluate the tissue attachment to titanium implant provided with hydrothermally induced TiO2 coating. Tissue attachment on TiO2 coated and non-coated implants were compared. Ti-6Al-4V alloy posts were used to function as implants that were inserted in five pig mandibles. Implants were delivered with two different surface treatments, non-coated (NC) titanium and hydrothermal induced TiO2 coated surfaces (HT). The tissue-implant specimens were cultured at an air/liquid interface for 7 and 14 days. The tissue-implant interface was analyzed by histological and immunohistochemical stainings. The microscopic evaluation suggests that pig tissue exp...
AimThe aim of this study was to evaluate the design of fiber-reinforced composite (FRC) on some m... more AimThe aim of this study was to evaluate the design of fiber-reinforced composite (FRC) on some mechanical properties of a dental implant.Methods and MaterialsFRC implants were fabricated using different polymerization conditions and designs of the glass-fiber structure. Specimens were tested with a cantilever bending test and a torsional test. The degree of monomer conversion (DC%) was measured using a Fourier transform infrared spectroscopy (FTIR).ResultsStatistical analysis showed significant differences between groups revealing mean fracture load values from 437 N to 1461 N. The mean torsional force in fracture varied from 0.01 to 1.66 Nm. The DC% varied from 50% to 90%.ConclusionThis study suggests by modifying the polymerization conditions and fiber orientation of FRC implants, the biomechanical properties of an FRC can be tailored to the needs of dental implants.CitationBallo AM, Lassila LV, Närhi TO, Vallittu PK.In vitroMechanical Testing of Glass Fiber-reinforced Composite ...
This study was designed to investigate the effect of nanostructured TiO2 coatings on human gingiv... more This study was designed to investigate the effect of nanostructured TiO2 coatings on human gingival fibroblast and to explore the influence of ultraviolet (UV) light on surface wettability and cellular response. Ti‐6Al‐4V titanium alloy discs (n = 96) were divided into three groups: a sol–gel‐derived MetAlive™ (MA) coating; hydrothermal (HT) coating; and a non‐coated (NC) group. Forty‐eight titanium substrates were further treated with UV light for 15 min. The water contact angles of the substrates were measured using the sessile drop method. Human gingival fibroblasts were used to evaluate the cell adhesion strength and cell proliferation on experimental surfaces. The strength of cell adhesion against enzymatic detachment was studied after 6 hr of adhesion using gentle trypsinization for 15 min at room temperature. A fluorescence microscope was used for cell imaging (Zeiss‐stereo‐lumar‐v12), and images were analyzed for cell counting, and the percentage of detached cells were calcu...
The International journal of oral & maxillofacial implants
The purpose of this retrospective study was to evaluate the clinical performance of and patients&... more The purpose of this retrospective study was to evaluate the clinical performance of and patients' satisfaction with maxillary overdentures retained by splinted and unsplinted implants. Patients who had been treated with maxillary implant-retained overdentures because of functional problems with conventional complete dentures were identified and invited to participate in the study. A total of 16 patients fulfilled the enrollment criteria and agreed to participate. Eleven patients were treated with bar-retained overdentures with 3 to 6 clips (mean follow-up 32 months), and 5 patients wore overdentures retained by 2 to 6 ball attachments (mean follow-up 54 months). All subjects were satisfied with their prostheses, and most subjects experienced improvement in their oral function after treatment with implant-retained overdentures. At the time of clinical examination, 92% (n = 77) of the 84 implants placed were functioning satisfactorily. The cumulative survival rate for the implants...
Summary In August 23–25, 2007, the Scandinavian Society for Prosthetic Dentistry in collaboratio... more Summary In August 23–25, 2007, the Scandinavian Society for Prosthetic Dentistry in collaboration with the Danish Society of Oral Implantology arranged a consensus conference on the topic ‘Implants and/or teeth’. It was preceded by a workshop in which eight focused questions were raised and answered in eight review articles using a systematic approach. Twenty‐eight academicians and clinicians discussed the eight review papers with the purpose to reach consensus on questions relevant for the topic. At the conference the consensus statements were presented as well as lectures based on the review articles. In this article the methods used at the consensus workshop are briefly described followed by the statements with comments.
ObjectivesAlthough titanium is commonly used as a favorable bone implant material due to its mech... more ObjectivesAlthough titanium is commonly used as a favorable bone implant material due to its mechanical properties, its bioactive and osteoconductive capacity is relatively low. Calcium phosphate ceramics, predominantly hydroxyapatite (HA), have been frequently used for coating purposes to improve the bioactive properties. In view of the suggested osteopromotive capacity of bioactive glasses (BGs), this study aimed to evaluate the effect of BG incorporation into HA coatings on implant performance in terms of bone contact and bone area.Materials and MethodsA total of 48 screw‐type titanium implants with magnetron sputter coatings containing different ratios of HA and BG (HA, HABGLow, and HABGHigh; n = 8) were placed into the mandible of 16 Beagle dogs. After 4 and 12 weeks, their performance was evaluated histologically and histomorphometrically. Peri‐implant bone area percentage (BA%) was determined in three zones (inner, 0–500 μm; middle, 500–1000 μm; and outer, 1000–1500 μm). Addi...
Monolithic zirconia prostheses are emerging as a promising option in the implant-based rehabilita... more Monolithic zirconia prostheses are emerging as a promising option in the implant-based rehabilitations of edentulous patients, yet their clinical performance is not fully documented. The purpose of this systematic review was to assess the clinical performance of complete-arch implant-supported monolithic zirconia fixed dental prostheses. The electronic databases PubMed, Science Direct, and Cochrane Library were searched for clinical studies on complete-arch implant-supported monolithic zirconia fixed dental prostheses. Human studies with a mean follow-up of at least 1 year and published in an English-language peer-reviewed journal up to June 2015 were included. Two independent examiners conducted the search and the review process. The search generated 903 titles. Eighteen qualifying studies were retrieved for full-text evaluation. Nine studies were included on the basis of preestablished criteria. Eight studies reported satisfactory clinical and esthetic outcomes. One study demonstrated prosthesis failure. Clinical studies are lacking on the long-term outcome of complete-arch implant-supported monolithic zirconia prostheses. Complete-arch dental implant restoration with monolithic zirconia is associated with high short-term success. Despite the many advantages and short-term favorable reports, studies of longer duration are necessary to validate the broad application of this therapy.
Dental materials : official publication of the Academy of Dental Materials, 2015
To evaluate the surface topography and optical properties of monolithic zirconia after immersion ... more To evaluate the surface topography and optical properties of monolithic zirconia after immersion in simulated gastric acid. Four partially stabilized (PSZ) and one fully stabilized (FSZ) zirconia materials were selected for the study: Prettau (PRT, Zirkonzahn), Zenostar (ZEN, Ivoclar), Bruxzir (BRX, Glidewell), Katana (KAT, Noritake) and FSZ Prettau Anterior (PRTA, Zirkonzahn). IPS e.max (Ivoclar) was used as a control. The specimens (10×10×1.2mm, n=5 per material) were cut, sintered, polished and cleaned before immersed in 5ml of simulated gastric acid solution (Hydrochloric acid (HCl) 0.06M, 0.113% solution in deionized distal water, pH 1.2) for 96h in a 37°C incubator. Specimens were weighed and examined for morphological changes under scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Surface roughness was evaluated by a confocal microscope. Surface gloss and translucency parameter (TP) values were determined by a reflection spectrophotom...
Streptococcus mutans is able to form a high-affinity biofilm on material surfaces. S. mutans has ... more Streptococcus mutans is able to form a high-affinity biofilm on material surfaces. S. mutans has also been detected around infected implants. Bioactive glasses have been shown to possess antibacterial effects against S. mutans and other microorganisms. This in vitrostudy was performed to investigate the influence of bioactive glass air-abrasion on S. mutans biofilm on sandblasted and acid etched titanium surfaces. Sandblasted and acid etched commercially pure titanium discs were used as substrates for bacteria (n=107). The discs were immersed in an S. mutans solution and incubated for 21 h to form S. mutans biofilm. Twenty colonized discs were subjected to air-abrasion with the Bioglass®45S5 (45S5 BAG), experimental zinc oxide containing bioactive glass (Zn4 BAG) and inert glass. After the abrasion, the discs were incubated for 5 h in an anaerobic chamber followed by an assessment of viable S. mutans cells. Surface morphology was evaluation using SEM (n=12). Thrombogenicity of the g...
Objective of this study was to develope low temperature sol-gel coatings for shape memory metal (... more Objective of this study was to develope low temperature sol-gel coatings for shape memory metal (NiTi) and evaluate their biocompatibility on NiTi suture material. A series of low temperature TiO 2 and TiO 2-SiO 2 sol-gel coatings were prepared on glass substrates. The silica content of TiO 2-SiO 2 coatings ranged from 0 to 30 mol%. The coatings were also prepared with polyethyleneglycol (PEG). The contact angle and photocatalytic activity measurements were used to evaluate the surface properties of the coatings. Stability of the coatings was tested in simulated body fluid (SBF). The TiO 2-SiO 2 90/10 film made with PEG was more hydrophilic, showed photocatalytic activity and was crack-free after the SBF test, thus it was chosen to animal experiment as a new experimental coating. Uncoated NiTi suture and the suture coated with high temperature TiO 2 were used as reference materials. NiTi sutures were inserted subcutaneously on the back of rat for four weeks. In routine histological examinations all materials showed good biocompatibility with mild inflammatory cell reaction. No significant differences in the soft tissue response among the materials were observed. Both the high and new low temperature processed sol-gel coatings remained attached on the sutures confirming the suitability of the coating technique on thin NiTi sutures.
In 1990, 364 elderly (76-86 years) inhabitants of Helsinki, Finland, attended a dental and oral e... more In 1990, 364 elderly (76-86 years) inhabitants of Helsinki, Finland, attended a dental and oral examination study that was conducted as part of the Helsinki Aging Study. In spring 1996, these subjects were recalled for a 5-year follow-up. Between the baseline and follow-up examinations, 114 (31%) subjects had deceased (86 women and 28 men), whereas 134 had either moved, were too ill, or refused to participate in the follow-up. Follow-up examination was conducted for 113 subjects (79 women and 34 men), with the participating rate being 46%. Five subjects became edentulous during the follow-up. Of the subjects, 61% had 1-32 teeth at follow-up. In these subjects, the mean number of teeth decreased from 14AE9 (-8AE3) to 13AE5 (-8AE6) (P < 0AE0001). Prosthetic status changed in 40% of the elderly dentate people: 25% received new prostheses whereas 15% lost prostheses that were not replaced. New fixed partial dentures were made in five maxillae and in nine mandibles during the follow-up. Acrylic removable partial dentures (ARPD) were most frequently used: 35% of dentate subjects had an ARPD. Subjects with removable prostheses had higher levels of salivary microbes and higher root caries incidence than those with natural teeth. Furthermore, the presence of removable prostheses at baseline, together with the male gender, was clearly associated with tooth loss during follow-up. This study indicates that fixed rather than removable prostheses should be used in elderly patients. The need for a removable denture ought to be carefully considered.
Journal of Biomedical Materials Research Part A, 2004
A firm bond between an implant and the surrounding soft tissue is important for the performance o... more A firm bond between an implant and the surrounding soft tissue is important for the performance of many medical devices (e.g., stents, canyls, and dental implants). In this study, the performance of nonresorbable and reactive sol-gel-derived nano-porous titania (TiO 2) coatings in a soft tissue environment was investigated. A direct attachment between the soft tissue and the sol-gel-derived titania coatings was found in vivo after 2 days of implantation, whereas the titanium control implants showed no evidence of soft tissue attachment. The coated implants were in immediate contact with the connective tissue, whereas the titanium controls formed a gap and a fibrous capsule on the implant-tissue interface. The good soft tissue attachment of titania coatings may result from their ability to initiate calcium phosphate nucleation and growth on their surfaces (although the formation of poorly crystalline bonelike apatite does not occur). Thus, the formation of a bonelike CaP layer is not crucial for their integration in soft tissue. The formation of bonelike apatite was hindered by the adsorption of proteins onto the initially formed amorphous calcium phosphate growth centers, thus preventing the dissolution/ reprecipitation processes required for the formation of poorly crystalline bonelike apatite. These findings might open novel application areas for sol-gel-derived titaniabased coatings.
Journal of Biomedical Materials Research Part A, 2009
Average scaffold pore sizes in the order of several hundred microns are generally required for ef... more Average scaffold pore sizes in the order of several hundred microns are generally required for efficient bone tissue ingrowth in vivo, whereas the culture of large bone engineering constructs in vitro can require bioreactor cultures to decrease diffusional constraints on the cells. In this study, we prepared poly(epsilon-caprolactone/D,L-lactide)-based scaffolds with continuous phase macroporosity using a novel CaCl(2) . 6H(2)O porogen agent. Osteogenic differentiation and scaffold colonization in rat bone marrow stromal cell cultures were compared in such polymer scaffolds, and in composites with 30 wt % bioactive glass filler. The effect of a rotating wall bioreactor culture on the cell response was also evaluated. Bioactive filler enhanced proliferation, early osteogenic differentiation, and mineralization of the cultured cells under static conditions. Dynamic cultures, in turn, resulted in decreased cell numbers and inhibition of the differentiation process irrespective of the scaffold type. This effect was ascribed to the harsh mechanical stresses caused by constant collisions of the scaffolds in the bioreactor vessels. However, cells were able to penetrate into the scaffold interior only under dynamic culture conditions. Thus, interconnected macroporosity is an essential, but not sufficient, condition to allow for full colonization of millimeter scale tissue engineering scaffolds in vitro.
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Papers by Timo Närhi