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Molin Thorén, MargaretaORCID iD iconorcid.org/0000-0002-4915-6845
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Publications (10 of 19) Show all publications
Ågren, M., Kou, W. & Molin Thorén, M. (2019). Bond strength of surface-treated novel high translucent zirconia to enamel. Biomaterial Investigations in Dentistry, 6(1), 35-42
Open this publication in new window or tab >>Bond strength of surface-treated novel high translucent zirconia to enamel
2019 (English)In: Biomaterial Investigations in Dentistry, ISSN 2641-5275, Vol. 6, no 1, p. 35-42Article in journal (Refereed) Published
Abstract [en]

Aim: The aim of the present study was to evaluate the shear bond strength of zirconia, stabilised with 5% yttria, luted to enamel and to evaluate the fracture pattern at loss of retention.

Methods: A total of 53 test specimen were manufactured from two partially stabilised zirconia materials, Zirkonzahn Prettau Anterior (ZPA) (n = 16) and Whitepeaks CopraSmile Symphony 5 layer (WCS) (n = 18), and a lithium disilicate (Ivoclar e.Max Press) (n = 19) acting as control. All test specimens were cemented to human enamel with Variolink Esthetic DC and then subjected to a shear bond strength test. Fracture and surface analysis were performed using light and scanning electron microscope.

Results: No significant differences in shear bond strength were detected when analysing the three groups. Dividing them according to the fracture pattern significant difference in shear bond strength between the two zirconia groups could be seen analysing test bodies with failure of adhesion to the test body, but not to enamel. The ZPA had higher shear bond strength (23.68 MPa) than WCS (13.00 MPa). No significant differences were seen compared to the control group (19.02 MPa).

Conclusion: Partially stabilised zirconia shows potential as a material to be used where macro mechanical bonding is not possible, although this study does not reveal how or if the bonding deteriorates over time.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Shear strength, zirconium dioxide, dental bonding, dental veneers
National Category
Biomaterials Science
Research subject
Odontology
Identifiers
urn:nbn:se:umu:diva-164925 (URN)10.1080/26415275.2019.1684200 (DOI)2-s2.0-85104490723 (Scopus ID)
Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2021-05-06Bibliographically approved
Lundegren, N., Sohrabi, M. M., Molin Thorén, M. & Akerman, S. (2019). Prosthetic dental restorations in Swedish samples: prevalence and agreement between self-report, clinical findings, and influence on quality of life. Acta Odontologica Scandinavica, 77(4), 296-302
Open this publication in new window or tab >>Prosthetic dental restorations in Swedish samples: prevalence and agreement between self-report, clinical findings, and influence on quality of life
2019 (English)In: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 77, no 4, p. 296-302Article in journal (Refereed) Published
Abstract [en]

Objective: To determine the prevalence of dental prosthetic restorations in an adult population, to study the agreement between self-reports and clinical findings of prosthetic restorations, and to study answers from a questionnaire in relation to the prevalence of prosthetic restorations. Material and methods: A questionnaire was sent to a sample of 10,000 adults. A further sample of 1000 individuals was invited to answer the questionnaire and also participate in a clinical study. The agreement between self-report and clinical findings was analyzed, as were the associations between prosthetic restorations and questionnaire responses, using the chi(2) test. Results: A total of 40% of the sample had fixed dental prostheses (FDP), 2.7% had removable dentures. The agreement between self-report and clinical findings was 93%. 34.7% of the individuals with no prosthetic restorations were university graduates and 4% of individuals with removable complete dentures. Oral health had the greatest impact on the quality of life of younger individuals with FDP, with an OHIP-14 (Oral Health Impact Profile) score of 7.3 for the age group 20-39 years compared to 4.9 for the age group 65-89 years. Conclusion: The questionnaire method can be a cost-effective way to determine the prevalence of prosthetic restorations.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2019
Keywords
Self-assessment, quality of life, agreement, fixed partial dentures, removable dentures
National Category
Dentistry
Identifiers
urn:nbn:se:umu:diva-158937 (URN)10.1080/00016357.2018.1542505 (DOI)000465152500009 ()30600743 (PubMedID)2-s2.0-85059593042 (Scopus ID)
Available from: 2019-05-27 Created: 2019-05-27 Last updated: 2023-03-24Bibliographically approved
Kou, W., Gabrielsson, K., Borhani, A., Carlborg, M. & Molin Thorén, M. (2019). The effect of artificial aging on high translucent zirconia. Biomaterial Investigations in Dentistry, 6(1), 54-60
Open this publication in new window or tab >>The effect of artificial aging on high translucent zirconia
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2019 (English)In: Biomaterial Investigations in Dentistry, ISSN 2641-5275, Vol. 6, no 1, p. 54-60Article in journal (Refereed) Published
Abstract [en]

Zirconia is known for its high strength but lacking translucency. Recently, a new type of high translucent zirconia, 5 mol% yttria partially stabilized zirconia (5Y-PSZ), with a larger fraction of cubic zirconia phase has become commercially available. However, the resistance to aging of these commercially available zirconia materials is not yet fully established.

Purpose: The aim of the present study was to analyze the effects of artificial aging on surface roughness, transparency, phase transformation and biaxial flexural strength of two 5Y-PSZ products, DD cubeX2 and Prettau Anterior.

Materials and methods: The artificial aging was performed in an autoclave under 2 bars of pressure at 134 °C for 10 hours, which is estimated to correspond to 30–40 years in vivo. Artificial aging for 10 hours had no significant effect on surface roughness, transparency, or phase transformation for either of the tested materials.

Results: DD cubeX2 had higher mean flexural strength than Prettau Anterior both before and after artificial aging for 10 hours (p < .05). DD cubeX2 showed, however, a significant reduction in flexural strength after artificial aging (p < .05), whereas Prettau Anterior showed a slight increase in flexural strength after artificial aging but not at a significant level.

Conclusion: Within the limitation of the present study, both DD cubeX2 and Prettau Anterior seems to be relatively resistant to aging. However, a wider range of measured flexural strength indicated that Prettau Anterior probably is a less stable material than DD cubeX2, which also means that the flexural strength of DD cubeX2 could be more predictable.

Keywords
High translucent zirconia, 5Y-PSZ, aging, biaxial flexural strength, transparency, surface roughness
National Category
Other Medical Sciences
Research subject
Odontology
Identifiers
urn:nbn:se:umu:diva-165606 (URN)10.1080/26415275.2019.1684201 (DOI)
Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2023-03-07Bibliographically approved
Pettersson, M., Pettersson, J., Johansson, A. & Molin Thorén, M. (2019). Titanium release in peri-implantitis. Journal of Oral Rehabilitation, 46(2), 179-188
Open this publication in new window or tab >>Titanium release in peri-implantitis
2019 (English)In: Journal of Oral Rehabilitation, E-ISSN 1365-2842, Vol. 46, no 2, p. 179-188Article in journal (Refereed) Published
Abstract [en]

Objectives: The aim of this study was to investigate the titanium (Ti) content of biopsies from patients with severe peri-implantitis or periodontitis and to examine whether Ti particles can be identified in samples from peri-implantitis lesions.

Background: Long-term follow-up studies show that implant usage to replace missing or lost teeth is a safe and predictable treatment. However, inflammation and loss of supporting bone around an implant (peri-implantitis) lead to patient suffering and costs. Peri-implantitis is considered to be an infectious disease, but recent studies have shown that Ti can aggravate inflammation in combination with bacterial products. The Ti content of peri-implantitis and periodontitis tissue is unknown.

Methods: Thirteen patients referred for peri-implantitis and eleven for periodontitis treatment were included in the study. Disease severity was obtained from dental records. Biopsies were taken from both groups and chemically analyzed with inductively coupled plasma mass spectrometry (ICP-MS) for Ti content. Additionally, two patients with peri-implantitis and two with periodontitis were recruited and their biopsies were analyzed microscopically with light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) with element analysis to investigate the presence of particulate Ti.

Results: All patients lost one or more implants despite undergoing peri-implant or periodontal treatment. Peri-implantitis tissue contained significantly higher concentrations of Ti than periodontitis tissue with a mean ± SDof 98.7 ± 85.6 μg/g and 1.2 ± 0.9 μg/g, respectively. Particulate metal was identified in peri-implantitis and periodontitis biopsies, but element analyses could confirm only the presence of Ti in peri-implantitis tissue. The mean size ± SDof the visible particles with LM was 10.9 ± 35.7 μm2 (mean of three repeated measurements) (95% CI, 6.5-15.3).

Conclusion: We showed that high contents of particulate and submicron Ti were present in peri-implantitis tissue. These high Ti contents in peri-implant mucosa can potentially aggravate inflammation, which might reduce the prognosis of treatment interventions.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, light microscopy, peri-implantitis, scanning electron microscopy, titanium
National Category
Dentistry
Research subject
Odontology
Identifiers
urn:nbn:se:umu:diva-147118 (URN)10.1111/joor.12735 (DOI)000455483300010 ()30325523 (PubMedID)2-s2.0-85056667959 (Scopus ID)
Funder
Västerbotten County Council, VLL 1147-2014
Note

Originally included in thesis in manuscript form.

Available from: 2018-04-27 Created: 2018-04-27 Last updated: 2024-01-17Bibliographically approved
Pettersson, M., Pettersson, J., Molin Thorén, M. & Johansson, A. (2018). Effect of cobalt ions on the interaction between macrophages and titanium. Journal of Biomedical Materials Research. Part A (9), 2518-2530
Open this publication in new window or tab >>Effect of cobalt ions on the interaction between macrophages and titanium
2018 (English)In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, no 9, p. 2518-2530Article in journal (Refereed) Published
Abstract [en]

Inflammation and bone reduction around dental implants are described as periimplantitis and can be caused by an inflammatory response against bacterial products and toxins. Titanium (Ti) forms aggregates with serum proteins, which activate and cause release of the cytokine interleukin (IL-1β) from human macrophages. It was hypothesized that cobalt (Co) ions can interact in the formation of pro-inflammatory aggregates, formed by titanium. To test this hypothesis, we differentiated THP-1 cells into macrophages and exposed them to Ti ions alone or in combination with Co ions to investigate if IL-1β release and cytotoxicity were affected. We also investigated aggregate formation, cell uptake and human biopsies with inductively coupled plasma atomic emission spectroscopy (ICP-AES) and electron microscopy. Co at a concentration of 100 μM neutralized the IL-1β release from human macrophages and affected the aggregate formation. The aggregates formed by Ti could be detected in the cytosol of macrophages. In the presence of Co, the Ti-induced aggregates were located in the cytosol of the cultured macrophages, but outside the lysosomal structures. It is concluded that Co can neutralize the Ti-induced activation and release of active IL-1β from human macrophages in vitro. Also, serum proteins are needed for the formation of metal-protein aggregates in cell medium. Furthermore, the structures of the aggregates as well as the localization after cellular uptake differ if Co is present in a Ti solution. Phagocytized aggregates with a similar appearance seen in vitro with Ti present, were also visible in a sample from human peri-implant tissue.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
titanium, cobalt, interleukin-1β, peri-implantitis, aggregate formation
National Category
Dentistry
Research subject
Odontology
Identifiers
urn:nbn:se:umu:diva-147124 (URN)10.1002/jbm.a.36447 (DOI)000445615600016 ()29708655 (PubMedID)2-s2.0-85053870464 (Scopus ID)
Funder
Västerbotten County Council, VLL 1147-2014
Available from: 2018-04-27 Created: 2018-04-27 Last updated: 2023-03-24Bibliographically approved
Karlsson, K., Derks, J., Håkansson, J., Wennström, J. L., Molin Thorén, M., Petzold, M. & Berglundh, T. (2018). Technical complications following implant-supported restorative therapy performed in Sweden. Clinical Oral Implants Research, 29(6), 603-611
Open this publication in new window or tab >>Technical complications following implant-supported restorative therapy performed in Sweden
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2018 (English)In: Clinical Oral Implants Research, ISSN 0905-7161, E-ISSN 1600-0501, Vol. 29, no 6, p. 603-611Article in journal (Refereed) Published
Abstract [en]

Objective: The aim of this study was to evaluate the occurrence and consequences of technical complications in implant-supported restorative therapy.

Material & Methods: The occurrence and consequences of technical complications in implant-supported restorative therapy over a mean follow-up period of 5.3years were assessed based on documentation in files from 2,666 patients. Risk indicators were identified by the use of survival models, considering repeated events. Results were expressed as hazard ratios (HR) including 95% confidence intervals.

Results: Technical complications occurred in 24.8% of the patients. Chipping and loss of retention were the most common, affecting 11.0% and 7.9% of supraconstructions, respectively, while implant-related complications (e.g., implant fracture) were rare. More than 50% of the affected patients experienced technical complications more than once and almost all reported complications led to interventions by a dental professional. The extent of the supraconstruction was the strongest risk indicator for both chipping (HR<0.2) and loss of retention (HR>3).

Conclusion: Over a 5-year period, technical complications in implant-supported restorative therapy occurred frequently and their management required professional intervention.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
diagnosis, clinical assessment, epidemiology, prosthodontics
National Category
Dentistry
Identifiers
urn:nbn:se:umu:diva-150486 (URN)10.1111/clr.13271 (DOI)000439498900008 ()29923628 (PubMedID)2-s2.0-85050084986 (Scopus ID)
Funder
Swedish Social Insurance AgencySwedish Research Council, 2016-01571
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2023-03-23Bibliographically approved
Pettersson, M., Pettersson, J., Molin Thorén, M. & Johansson, A. (2017). Release of titanium after insertion of dental implants with different surface characteristics: an ex vivo animal study. Acta Biomaterialia Odontologica Scandinavica, 3(1), 63-73
Open this publication in new window or tab >>Release of titanium after insertion of dental implants with different surface characteristics: an ex vivo animal study
2017 (English)In: Acta Biomaterialia Odontologica Scandinavica, E-ISSN 2333-7931, Vol. 3, no 1, p. 63-73Article in journal (Refereed) Published
Abstract [en]

In the present study, amount of titanium (Ti) released into the surrounding bone during placement of implants with different surface structure was investigated. Quantification of Ti released during insertion from three different implants was performed in this ex vivo study. Jaw bone from pigs was used as model for installation of the implants and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) was used for analysis of the released Ti. Implant surface were examined with scanning electron microscopy (SEM), before and after the placement into the bone. Ti was abraded to the surrounding bone upon insertion of a dental implant and the surface roughness of the implant increased the amount of Ti found. Diameter and total area of the implant were of less importance for the Ti released to the bone. No visible damages to the implant surfaces could be identified in SEM after placement.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
Keywords
titanium, dental implants, inductively coupled plasma atomic emission spectroscopy (ICP-AES)
National Category
Dentistry
Research subject
biological chemistry
Identifiers
urn:nbn:se:umu:diva-143106 (URN)10.1080/23337931.2017.1399270 (DOI)29242814 (PubMedID)
Available from: 2017-12-16 Created: 2017-12-16 Last updated: 2023-06-28Bibliographically approved
Pettersson, M., Kelk, P., Belibasakis, G. N., Bylund, D., Molin Thorén, M. & Johansson, A. (2017). Titanium ions form particles that activate and execute interleukin-1β release from lipopolysaccharide-primed macrophages. Journal of Periodontal Research, 52(1), 21-32
Open this publication in new window or tab >>Titanium ions form particles that activate and execute interleukin-1β release from lipopolysaccharide-primed macrophages
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2017 (English)In: Journal of Periodontal Research, ISSN 0022-3484, E-ISSN 1600-0765, Vol. 52, no 1, p. 21-32Article in journal (Refereed) Published
Abstract [en]

BACKGROUND AND OBJECTIVE: Peri-implantitis is a destructive inflammatory process characterized by destruction of the implant-supporting bone. Inflammasomes are large intracellular multiprotein complexes that play a central role in innate immunity by activating the release of proinflammatory cytokines. Although inflammasome activation has previously been linked to periodontal inflammation, there is still no information on a potential association with peri-implantitis. The aim of this study was to examine cytotoxic and proinflammatory effects, including inflammasome activation, of metals used in dental implants, in an in vitro model, as well as from clinical tissue samples.

MATERIAL AND METHODS: Human macrophages were exposed to different metals [titanium (Ti), cobalt, chromium and molybdenum] in a cell-culture assay. Cytotoxicity was determined using the neutral red uptake assay. Cytokine secretion was quantified using an ELISA, and the expression of genes of various inflammasome components was analysed using quantitative PCR. In addition, the concentrations of interleukin-1β (IL-1β) and Ti in mucosal tissue samples taken in the vicinity of dental implants were determined using ELISA and inductively coupled plasma mass spectrometry, respectively.

RESULTS: Ti ions in physiological solutions stimulated inflammasome activation in human macrophages and consequently IL-1β release. This effect was further enhanced by macrophages that have been exposed to lipopolysaccharides. The proinflammatory activation caused by Ti ions disappeared after filtration (0.22 μm), which indicates an effect of particles. Ti ions alone did not stimulate transcription of the inflammasome components. The Ti levels of tissue samples obtained in the vicinity of Ti implants were sufficiently high (≥ 40 μm) to stimulate secretion of IL-1β from human macrophages in vitro.

CONCLUSION: Ti ions form particles that act as secondary stimuli for a proinflammatory reaction.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
caspase-1, inflammation, interleukin-1β, macrophage, peri-implantitis, titanium
National Category
Medical Biotechnology Dentistry
Research subject
Odontology
Identifiers
urn:nbn:se:umu:diva-118473 (URN)10.1111/jre.12364 (DOI)000393165200003 ()26987886 (PubMedID)2-s2.0-84961176243 (Scopus ID)
Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2023-03-24Bibliographically approved
Falk, A., von Steyern, P. V., Franssori, H. & Thoren, M. M. (2015). Reliability of the Impression Replica Technique. International Journal of Prosthodontics, 28(2), 179-180
Open this publication in new window or tab >>Reliability of the Impression Replica Technique
2015 (English)In: International Journal of Prosthodontics, ISSN 0893-2174, E-ISSN 1139-9791, Vol. 28, no 2, p. 179-180Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to evaluate the reliability of the impression replica technique with a four-unit zirconia fixed dental prosthesis (FOP). Marginal and internal fit were measured by repeatedly placing the FDP on an epoxy cast using light-body silicone material corresponding to cement. All measured marginal and internal fit points showed varying values. The greatest variations were seen at the most distal margin (33 mu m) and at the distal abutment of the FDP (77 mu m). The results showed that the technique gives moderate variations and is a useful method to evaluate marginal and internal fit.

National Category
Dentistry
Identifiers
urn:nbn:se:umu:diva-102371 (URN)10.11607/IJP.4132 (DOI)000351890000012 ()25822305 (PubMedID)2-s2.0-84929031916 (Scopus ID)
Available from: 2015-05-28 Created: 2015-04-23 Last updated: 2023-03-24Bibliographically approved
Molin, M. K. & Karlsson, S. L. (2008). Five-year clinical prospective evaluation of zirconia-based Denzir 3-unit FPDs. International Journal of Prosthodontics, 21(3), 223-227
Open this publication in new window or tab >>Five-year clinical prospective evaluation of zirconia-based Denzir 3-unit FPDs
2008 (English)In: International Journal of Prosthodontics, ISSN 0893-2174, E-ISSN 1139-9791, Vol. 21, no 3, p. 223-227Article in journal (Refereed) Published
Abstract [en]

Purpose: The aim of this prospective study was to evaluate the clinical performance of fully sintered hot isostatic pressed yttria-partially-stabilized zirconia (Denzir) 3-unit fixed partial dentures (FPDs).

Materials and Methods: Nineteen 3-unit FPDs were placed in 18 patients. Ten FPDs were placed in the maxilla and 9 in the mandible. Two calibrated examiners evaluated the FPDs independently 1 week (baseline), 1 year, 3 years, and 5 years after placement using the California Dental Association quality evaluation system.

Results: All FPDs were intact at the 5-year examination. One FPD lost retention after 12 months but remained intact; it was recemented and is still in function after 5 years. All FPDs were rated satisfactory over 5 years. No changes were seen in terms of color and anatomic form. The number of slightly rough or pitted occlusal surfaces increased approximately 30% over 5 years. Visible evidence of ditching along the margin increased over time, but only for those FPDs luted with zinc phosphate cement.

Conclusion: The 5-year results indicate that yttria-partially-stabilized zirconia 3-unit FPDs with anatomically designed frameworks are promising prosthetic alternatives, even in the premolar and molar regions. However, for all-ceramic FPDs with more units in function, further studies are necessary.

Place, publisher, year, edition, pages
Hanover Park: Quintessence Publishing, 2008
Keywords
fixed partial dentures, all-ceramic crowns, fracture-resistance, posterior FPDs, follow-up, bridges, performance, lifetime
National Category
Dentistry
Identifiers
urn:nbn:se:umu:diva-117500 (URN)000256156000008 ()18548960 (PubMedID)2-s2.0-44849111859 (Scopus ID)
Available from: 2016-03-02 Created: 2016-03-01 Last updated: 2023-03-24Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4915-6845

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