| 1. |
- Berg, Camilla, et al.
(författare)
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ACP-Mg particles for treatment of dental hypersensitivity : a mode of action study
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction/purpose:Dental hypersensitivity is a common clinical condition usually associated with exposed dentinal tubules. Occlusion of those, hindering fluid movement as a response to external stimuli, is one approach to reduce pain.[1] The occluding agent should induce mineralization and have a good filling effect. In this study, particles (200-400 nm) of Amorphous Calcium Phosphate with Mg (ACP-Mg) were used aiming to evaluate the mode of action with in-vitro studies on dentine as well as degradation properties in buffered systems.Methods:Degradation properties and ion-release was monitored by dispersing the particles in Tris-HCl (10 mg/mL) storing the dispersions at 37 °C. In-vitro testing was performed on 1 mm thick dentine discs cut from extracted human molars. Specimens were etched in 35 % phosphoric acid, rinsed with DI-water followed by treatment by applying a gel formulation containing the particles using a soft bristled toothbrush, brushing 1 min on each side and leaving the specimen to rest for 3 min. Treatment was repeated four times during one day and samples were incubated at 37 °C in artificial saliva.Results:In vitro tests and degradation studies showed that ACP-Mg particles induced formation of Hydroxyapatite (HA). ICP-OES, XRD and SEM showed that there was a rapid release of all ions up to 6 hours followed by a re-precipitation of HA at 24 hours with a lower Mg-content. The crystallinity increased with time as the concentration of all ions decreased in the solutions. Morphological evaluation for the in-vitro tests showed that HA-like structures formed already after 24 hours on the dentine surface. Cross-sections revealed that the particles reached as far as 80 µm from the surface and tubules, fully occluded by HA-like structures, was visible at comparable depths after 7 days.Conclusions:ACP-Mg particles can be used to reduce dentine hypersensitivity by effective occlusion of dentine tubules via rapid formation of surface and intra-tubular HA.References:1. Splieth CH, Tachou A. 2013. Epidemiology of dentin hypersensitivity. Clin Oral Investig. 17:3–8.
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| 2. |
- Berg, Camilla, et al.
(författare)
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Amorphous Calcium Magnesium Phosphate Particles for Treatment of Dentin Hypersensitivity : A Mode of Action Study
- 2020
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Ingår i: ACS Biomaterials Science & Engineering. - : AMER CHEMICAL SOC. - 2373-9878. ; 6:6, s. 3599-3607
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Tidskriftsartikel (refereegranskat)abstract
- Occlusion of exposed dentin tubules may eliminate or reduce dentin hypersensitivity by hindering fluid movements within the tubules. In this study, the mode of action of spherical particles of amorphous calcium magnesium phosphate (180-440 nm in diameter) was studied. A degradation study of the particles in Tris-HCl buffer showed that the particles continuously released Ca2+, Mg2+, and phosphate, and XRD analysis revealed the formation of hydroxyapatite (HA) after 1 week. The occluding effect and efficacy of the spherical particles as an occluding agent were evaluated in an in vitro study. The ACMP particles were incorporated in a gel intended for at-home use and tested on extracted human molars. Application of the particles followed by incubation in artificial saliva resulted in occlusion of exposed tubules, and examination with SEM showed that the particles could penetrate the tubules down to 100 mu m from the dentin surface. Transformation of the particles into nanocrystalline HA-structures (nanoHA) was initiated at the dentin surface within 12 h of application, and tubule penetration of the particles, accompanied by further ion release and diffusion of ions, resulted in deep intratubular occlusion in the majority of the tubules within 3 days from application. NanoHA was tightly adhered to the tubule walls, filling the entire tubule volume after 7 days. The results of this study demonstrate the mode of action of the amorphous calcium magnesium phosphate particles in occluding exposed dentin tubules. Interaction with saliva and transformation of the particles within the tubules inducing further mineralization indicate that the particles may be used as an effective treatment to reduce dentin hypersensitivity.
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| 3. |
- Berg, Camilla, et al.
(författare)
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Comparative study of technologies for tubule occlusion and treatment of dentin hypersensitivity
- 2021
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Ingår i: Journal of Functional Biomaterials. - : MDPI. - 2079-4983. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to evaluate the occluding/remineralization performance and resistance to acid attacks of the mineralization layer formed by a tooth-desensitizing gel containing amorphous calcium magnesium phosphate (ACMP) particles and compare it to six other desensitizing products available on the market. Similar comprehensive studies are few and there is especially a lack of studies that are up to date. A dentin-disc model was used for in vitro evaluation of the desensitizing toothpastes/gels. Application of the products was performed twice daily for seven days. One set of specimens were evaluated using scanning electron microscopy (SEM) directly after the final treatment and another set was evaluated after an acid challenge, exposing specimens to 2 wt% citric acid. The ACMP desensitizing gel was the only product resulting in complete occlusion by the formation of mineralized material on the dentin surface and inside the tubules. Particle deposition was dominant after treatment with the other desensitizing products, with little or no mineralization, resulting in partial occlusion only. Sensodyne Repair & Protect and Oral-B Pro-Expert showed the highest resistance toward acid attacks. Material inside the tubules remained relatively unaffected by acid attacks in all specimens. The results in this study indicated a great variability among the occluding agents in terms of occlusion and acid resistance of the mineralization layer. The high degree of occlusion and intra-tubular mineralization that could mitigate the effect of acid solubilization indicate that the ACMP desensitizing gel may be a superior option for the treatment of dentin hypersensitivity.
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| 4. |
- Berg, Camilla, et al.
(författare)
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Electron microscopy evaluation of mineralization on peritubular dentin with amorphous calcium magnesium phosphate microspheres
- 2020
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 46:11, s. 19469-19475
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Tidskriftsartikel (refereegranskat)abstract
- Dentin hypersensitivity can be reduced by the use of a remineralization agent to hinder movement of fluids within the dentin tubules. Penetration of particles into the tubules and a continuous release of Ca2+ and phosphate ions can induce the mineralization of a material mimicking the mineral component of dentin, sealing the tubules. In this work, we have used complementary electron microscopy techniques to investigate the ultrastructure of dentin and crystallization and occlusion effects when using amorphous calcium magnesium phosphate (ACMP) microspheres on extracted human molars. Application of the particles in a gel intended for athome use resulted in intra-tubular mineralization of a carbonate substituted hydroxyapatite (HA). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that crystallization was initiated on the peritubular dentin (PTD) with undirected crystal growth leading to the formation of a porous material. We additionally investigated the effects from using a fluoride toothpaste to potentially improve the remineralization and anti-cariogenic properties of the ACMP microspheres. Energy dispersive x-ray spectroscopy (EDX) using TEM in scanning mode (STEM) showed that fluoride incorporation resulted in an increase in aspect ratio of the crystals, crystal growth directed towards the center of the tubule lumen and densification of the mineralized material. Thus, ACMP microspheres are promising alternatives as occluding agents and the efficacy of the particles could be further improved with the complementary use of a fluoride toothpaste.
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| 5. |
- Campanello, Magnus, et al.
(författare)
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Quality of life and gastric acid-suppression medication 20 years after laparoscopic fundoplication
- 2020
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Ingår i: ANZ Journal of Surgery. - : Wiley. - 1445-1433 .- 1445-2197. ; 90:1-2, s. 76-80
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Tidskriftsartikel (refereegranskat)abstract
- Background: Laparoscopic fundoplication is an effective treatment for gastro-oesophageal reflux disease (GERD). We aimed to assess quality of life (QoL), long-term residual symptoms, patient satisfaction and use of acid-suppression medication at 5, 10 and 20 years after surgery. Methods: We identified a cohort of 100 patients who underwent laparoscopic fundoplication between 1993 and 1998. The validated QoL questionnaires Short Form health survey (SF-36), and Quality-of-Life in Reflux and Dyspepsia (QOLRAD), as well as a specific questionnaire regarding post-fundoplication symptoms, were sent to the patients at 5, 10 and 20 years after surgery. Furthermore, patients who reported using the acid-suppression medication after 20 years were interviewed by telephone regarding their reason for taking it. Results: Eighty-eight percent of the patients responded at 5 and 10 years post-surgery. Twenty years following fundoplication, 68 (84% of those still alive) patients completed the questionnaires. The patients had equivalent health-related QoL scores in both the QOLRAD and SF-36 questionnaires after 10 and 20 years, and those scores were in line with a Swedish age-matched population. After 20 years, 87% were satisfied with the results, and 84% of the patients would recommend reflux surgery to a relative or a friend. At the telephone interview, 32% (22/68) confirmed using acid-suppression medication, but only half (11/68) used it because of reflux symptoms. Conclusion: The long-term, satisfying outcomes in GERD symptoms and QoL 5 and 10 years after surgery were maintained at a 20-year follow-up. Half of the patients used acid-suppression medication for reasons other than GERD symptoms. © 2019 Royal Australasian College of Surgeons
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| 6. |
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| 7. |
- Engstrand, Johanna, et al.
(författare)
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Hydroxyapatite formation on a novel dental cement in human saliva
- 2012
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Ingår i: ISRN Dentistry. - : Hindawi Limited. - 2090-438X. ; , s. 624056-
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Tidskriftsartikel (refereegranskat)abstract
- Dental materials have to meet high standards regarding mechanical strength and handling properties. There is however only a limited amount of research that has been devoted to natural formation of hydroxyapatite (HA) in contact with the materials. The objective of the current investigation was to study the surface reactions occurring in human salvia on a novel dental cement. Ceramir Crown & Bridge, a bioceramic luting agent intended for permanent cementation of conventional oral prosthetics, was evaluated by immersing discs made from the cement in human saliva and phosphate buffered saline (PBS) for seven days, after which they were dried and analyzed. The analytical methods used in order to verify HA formation on the surface were grazing incidence X-ray diffraction (GI-XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). All results showed that HA was formed on the surfaces of samples stored in saliva as well as on samples stored in PBS. The possibility of a dental luting cement to promote natural formation of HA at the tooth interface increases the stability and durability of the system and could help prevent secondary caries.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Fu, Le, et al.
(författare)
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Transparent single crystalline ZrO2-SiO2 glass nanoceramic sintered by SPS
- 2016
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 36:14, s. 3487-3494
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Tidskriftsartikel (refereegranskat)abstract
- Transparent ZrO2-SiO2 glass ceramics show potential for application in the dental industry. The application of this material prepared by a sol-gel method was hindered by the difficulties in obtaining large dimension samples. Spark plasma sintering (SPS) offers the possibility of achieving transparent ZrO2-SiO2 glass ceramics. In this study, a ZrO2-SiO2 powder was prepared by the sol-gel method and subsequently sintered by SPS. Varied sintering temperatures and pressures were explored to achieve better mechanical strength and transparency. TEM results showed single crystalline ZrO2 spherical nanocrystals (approximately 20 nm) homogenously embedded in the SiO2 matrix. Tetragonal ZrO2 was the only crystalline phase in all specimens. With sintering conditions of 1200 degrees C and 30 MPa, a glass ceramic with fracture toughness of 4.13 MPa was obtained. This value is similar to the commercial dental glass ceramic of IPS e.max (R) Press. The studied transparent glass ceramic with high transparency and moderate mechanical strength shows promise for dental application.
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| 12. |
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| 13. |
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| 14. |
- Janson, Oscar, et al.
(författare)
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Organic degradation potential of a TiO2/H2O2/UV-Vis system for dental applications
- 2017
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Ingår i: Journal of Dentistry. - : Elsevier BV. - 0300-5712 .- 1879-176X. ; 67, s. 53-57
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesThe combination of TiO2 and H2O2 under light activation constitutes a promising method for disinfection of dental prosthetics and implants, due to production of reactive oxygen species (ROS). The aim of this work was to investigate the organic degradation ability of TiO2 particles in combination with H2O2 and under light activation utilizing the organic dye rhodamine B (RhB).MethodsFive different types of TiO2 particles, consisting of anatase, rutile, or a mixture of these crystalline phases, were combined with H2O2 and RhB, and subsequently exposed to UV (365 nm) or visible (405 nm) light at an irradiance of 2.1 mW/cm2.ResultsIt was found that rutile in combination with low concentrations of H2O2 (1.0–3.5 mM) resulted in a degradation of RhB of 96% and 77% after 10 min exposure to 365 nm and 405 nm light, respectively, which was the highest degradation of all test groups. Control measurements performed without light irradiation or irradiation at 470 nm, or without TiO2 particles resulted in little or no degradation of RhB.ConclusionsLow H2O2 concentrations (1.0 mM–3.5 mM) and visible light (405 nm) used in combination with rutile TiO2 particles showed the highest RhB degradation capacity.Clinical significanceA combination of TiO2 particles and H2O2 exposed to low energy UV or high energy visible light has an organic degradation capability that could be utilized in applications to kill or inactivate bacteria on medical devices such as dental implants for treatment against, e.g., peri-implantitis.
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| 15. |
- Jung, Bärbel, et al.
(författare)
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Preoperative mechanical preparation of the colon : the patient's experience
- 2007
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Ingår i: BMC Surgery. - : Springer Science and Business Media LLC. - 1471-2482. ; 7, s. 5-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Preoperative mechanical bowel preparation can be questioned as standard procedure in colon surgery, based on the result from several randomised trials. METHODS: As part of a large multicenter trial, 105 patients planned for elective colon surgery for cancer, adenoma, or diverticulitis in three hospitals were asked to complete a questionnaire regarding perceived health including experience with bowel preparation. There were 39 questions, each having 3 - 10 answer alternatives, dealing with food intake, pain, discomfort, nausea/vomiting, gas distension, anxiety, tiredness, need of assistance with bowel preparation, and willingness to undergo the procedure again if necessary. RESULTS: 60 patients received mechanical bowel preparation (MBP) and 45 patients did not (No-MBP). In the MBP group 52% needed assistance with bowel preparation and 30% would consider undergoing the same preoperative procedure again. In the No-MBP group 65 % of the patients were positive to no bowel preparation. There was no significant difference between the two groups with respect to postoperative pain and nausea. On Day 4 (but not on Days 1 and 7 postoperatively) patients in the No-MBP group perceived more discomfort than patients in the MBP group, p = 0.02. Time to intake of fluid and solid food did not differ between the two groups. Bowel emptying occurred significantly earlier in the No-MBP group than in the MBP group, p = 0.03. CONCLUSION: Mechanical bowel preparation is distressing for the patient and associated with a prolonged time to first bowel emptying.
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| 16. |
- López, Alejandro, et al.
(författare)
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Direct and interactive effects of three variables on properties of PMMA bone cement for vertebral body augmentation
- 2011
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 22:6, s. 1599-1606
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Tidskriftsartikel (refereegranskat)abstract
- PMMA bone cements are widely used for vertebral body augmentation procedures vertebroplasty and balloon kyphoplasty. Although there are studies in the literature on the direct effects of relevant variables on the properties of these cements, there are none on the interactive effects. In the present work, such a study was performed on both types of effects, with the variables being the concentration of initiator (benzoyl peroxide), the concentration of crosslinker (ethylene glycol dimethacrylate), and the liquid-to-powder ratio used in preparing the cement; and the properties being the compressive strength, the compressive modulus, the doughing time, the setting time, and the maximum polymerization temperature. Two additional properties obtained from the viscosity-versustime curves, namely the time at the onset of curing, and the critical curing rate were also studied. Significant interactive effects between the amount of crosslinker and the amount of radical initiator were found to affect the doughing time and the critical curing rate. These effects were explained in terms of the reaction kinetics. It was concluded that interactive effects may exist and should be taken into account when designing bone cement formulations.
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| 17. |
- Nilsson, Ulrica, 1960-, et al.
(författare)
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Improved recovery after music and therapeutic suggestions during general anaesthesia : a double-blind randomised controlled trial
- 2001
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 45:7, s. 812-817
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study was designed to determine whether music or music in combination with therapeutic suggestions in the intra-operative period under general anaesthesia could improve the recovery of hysterectomy patients.Methods: In a double-blind randomised clinical investigation, 90 patients who underwent hysterectomy under general anaesthesia were intra-operatively exposed to music, music in combination with therapeutic suggestion or operation room sounds. The anaesthesia was standardised. Postoperative analgesia was provided by a patient-controlled analgesia (PCA). The pain scores were recorded by means of a visual analogue scale. Nausea, emesis, bowel function, fatigue, well-being and duration of hospital stay were studied as outcome variables.Results: On the day of surgery, patients exposed to music in combination with therapeutic suggestions required less rescue analgesic compared with the controls. Patients in the music group experienced more effective analgesia the first day after surgery and could be mobilised earlier after the operation. At discharge from the hospital patients in the music and music combined with therapeutic suggestion group were less fatigued compared to the controls. No differences were noted in nausea, emesis, bowel function, well-being or length of hospital stay between the groups.Conclusion: This double-blind study has demonstrated that intra-operative music and music in combination with therapeutic suggestions may have some beneficial effects on postoperative recovery after hysterectomy. Further controlled studies are necessary to confirm our results.
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| 18. |
- Nilsson, Ulrica, 1960-, et al.
(författare)
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Improved recovery after therapeutic suggestions and music during general anaesthesia
- 2001
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 45:7, s. 812-817
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study was designed to determine whether music or music in combination with therapeutic suggestions in the intra-operative period under general anaesthesia could improve the recovery of hysterectomy patients. Methods: In a double-blind randomised clinical investigation, 90 patients who underwent hysterectomy under general anaesthesia were intra-operatively exposed to music, music in combination with therapeutic suggestion or operation room sounds. The anaesthesia was standardised. Postoperative analgesia was provided by a patient-controlled analgesia (PCA). The pain scores were recorded by means of a visual analogue scale. Nausea, emesis, bowel function, fatigue, well-being and duration of hospital stay were studied as outcome variables. Results: On the day of surgery, patients exposed to music in combination with therapeutic suggestions required less rescue analgesic compared with the controls. Patients in the music group experienced more effective analgesia the first day after surgery and could be mobilised earlier after the operation. At discharge from the hospital patients in the music and music combined with therapeutic suggestion group were less fatigued compared to the controls. No differences were noted in nausea, emesis, bowel function, well-being or length of hospital stay between the groups. Conclusion: This double-blind study has demonstrated that intra-operative music and music in combination with therapeutic suggestions may have some beneficial effects on postoperative recovery after hysterectomy. Further controlled studies are necessary to confirm our results.
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| 19. |
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| 20. |
- Nordin, Pär, et al.
(författare)
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Type of anaesthesia and patient acceptance in groin hernia repair : a multicentre randomised trial
- 2004
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Ingår i: Hernia. - : Springer Science and Business Media LLC. - 1265-4906 .- 1248-9204. ; 8:3, s. 220-225
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Tidskriftsartikel (refereegranskat)abstract
- Background Groin hernia repair can be performed under general (GA), regional (RA), or local (LA) anaesthesia. This multicentre randomised trial evaluates patient acceptance, satisfaction, and quality of life with these three anaesthetic alternatives in hernia surgery.Methods One hundred and thirty-eight patients at three hospitals were randomised to one of three groups, GA, RA, or LA. Upon discharge, they were asked to complete a specially designed questionnaire with items focusing on pain, discomfort, recovery, and overall satisfaction with the anaesthetic method used. The global quality-of-life instrument EuroQol was used for estimation of health perceived.Results Significantly more patients in the LA group than in the RA group felt pain during surgery (P<0.001). This pain was characterised as light or moderate and for the majority of LA patients was felt during infiltration of the anaesthetic agent. Postoperatively, patients in the LA group first felt pain significantly later than patients in the other two groups (P=0.012) and significantly fewer LA patients consumed analgesics more than three times during the first postoperative day (P=0.002). The results concerning nausea, vomiting, and time to first meal all favour LA. No difference was found among the three groups concerning overall satisfaction and quality of life.Conclusion In a general surgical setting, we found LA to be well tolerated and associated with significant advantages compared to GA and RA.
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| 21. |
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| 22. |
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| 23. |
- Persson, Cecilia, et al.
(författare)
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Nano grain sized zirconia–silica glass ceramics for dental applications
- 2012
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 32:16, s. 4105-4110
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Tidskriftsartikel (refereegranskat)abstract
- Glass ceramics based on lithium disilicates are commonly used in dental veneers and crowns. Alternative materials with improved mechanical properties may be of interest for more demanding applications, e.g. bridgeworks. In this study, a sol-gel method was optimized to produce nano grain-sized zirconia-silica glass ceramics with properties adequate for dental applications. The material properties were compared to those of IPS e.max (R) CAD, a commercially available lithium disilicate. The zirconia-silica glass ceramic was found to be translucent, with a transmittance of over 70%, and possessed excellent corrosion resistance. It also presented a somewhat lower elastic modulus but higher hardness than the lithium disilicate, and with the proper heat treatment a higher fracture toughness was achieved for the zirconia-silica glass ceramic. In conclusion, the material produced in this study showed promising results for use in dental applications, but the production method is sensitive and large specimen sizes may be difficult to achieve.
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| 24. |
- Unosson, Erik, et al.
(författare)
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Amorphous Calcium Magnesium Fluoride Phosphate — Novel Material for Mineralization in Preventive Dentistry
- 2023
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes novel and innovative amorphous calcium magnesium fluoride phosphate (ACMFP) core-shell microparticles that may be applied in preventive dentistry for the prevention of caries and the treatment of dentin hypersensitivity. The particles can be synthesized with varied fluoride content, up to approximately 6 wt%, without any observable differences in morphology or crystallinity. Fluoride release from the particles is correlated to the fluoride content, and the particles are readily converted to fluoride-substituted hydroxyapatite or fluorapatite in a simulated saliva solution. The remineralization and dentin tubule occlusion potential of the particles was evaluated in vitro on acid-etched dentin specimens, and treatment with the ACMFP particles resulted in complete tubule occlusion and the formation of a dense mineralization layer. The acid resistance of the mineralization layer was improved compared to treatment with analogous particles without fluoride inclusion. A cross-sectional evaluation of dentin specimens after treatment revealed the formation of high aspect ratio fluorapatite crystals and poorly crystalline hydroxyapatite, respectively. The particles of the current study provide a single source vehicle of readily available calcium, phosphate, and fluoride ions for the potential remineralization of carious lesions as well as exposed dentin tubules for the reduction of hypersensitivity.
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| 25. |
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| 26. |
- Unosson, Erik, et al.
(författare)
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Antibacterial Properties of Dental Luting Agents : Potential to Hinder the Development of Secondary Caries
- 2012
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Ingår i: International Journal of Dentistry. - : Hindawi Publishing Corporation. - 1687-8736 .- 1687-8728. ; 2012, s. 529495-
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Tidskriftsartikel (refereegranskat)abstract
- A modified direct contact test was used to evaluate the antibacterial properties of four commercially available dental luting agents (RelyX Unicem, Ketac Cem, Ceramir Crown & Bridge and Harvard Cement) and two reference materials (glass-ionomer cement and calcium aluminate cement) compared to a negative-control material (PMMA). Streptococcus mutans bacteria were placed in direct contact with specimens that had been aged for 10 min, 1 day, and 7 days, in order to test the antibacterial properties of the materials. A metabolic assay containing resazurin was used to quantify the amount of viable bacteria remaining after the direct contact tests. The effects of pH and fluoride on bacteria proliferation were also evaluated. Strongest antibacterial properties were found for calcium aluminate cement, followed by Ceramir Crown & Bridge and RelyX Unicem. Ketac Cem, Harvard Cement, and the reference glass-ionomer cement showed bacteria content either higher than or not significantly different from the PMMA control in all instances. pH levels below 6.3 and above 9.0 were found to have negative effects on bacterial proliferation. No correlation between either acidic materials or fluoride release and antibacterial properties could be seen; rather, basic materials showed stronger antibacterial properties.
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| 27. |
- Unosson, Erik, 1983-
(författare)
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Antibacterial Strategies for Titanium Biomaterials
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Titanium and titanium based alloys are widely used in dentistry and orthopedics to replace hard tissue and to mend broken bones. It has become a material of choice due to its low density, high strength, good biocompatibility and its capacity to integrate closely with the bone. Today, modern materials and surgical techniques can enable patients to live longer, and aid in maintaining or regaining mobility for a more fulfilling life. There are, however, instances where implants fail, and one of the primary causes for implant failure is infection.This thesis deals with two possible ways of reducing or eliminating implant associated infections; TiO2 photocatalysis, where a surface can become antibacterial upon irradiation with UV light; and incorporation of silver, where a subsequent release of silver metal ions result in an antibacterial effect.For the TiO2 photocatalysis strategy, a simple and cost effective chemical oxidation technique, using hydrogen peroxide (H2O2) and water, was used to create an active TiO2 surface on titanium substrates. This surface was shown to effectively degrade an organic model substance (rhodamine B) by generating reactive oxygen species (ROS) under UV illumination. However, it was shown that Ti-peroxy radical species remaining in the surface after the H2O2-oxidation process, rather than generation of ROS from a heterogeneous photocatalytic process, was responsible for the effect. This discovery was further exploited in a TiO2/H2O2/UV system, which demonstrated synergy effects in both rhodamine B degradation tests and in antibacterial assays.For the silver ion release strategy, a combinatorial materials science approach was employed. Binary Ag-Ti oxide gradients were co-deposited in a reactive (O2) environment using a custom built physical vapor deposition system, and evaluated for antibacterial properties. The approach enabled synthesis and composition-structure-property evaluation unlikely to have been achieved by traditional means, and the gradient coatings demonstrated antibacterial properties against both S. aureus and S. epidermidis according to silver ion release. The release was shown to depend more on structural features, such as surface area, crystallinity and oxidation state, than on composition.Ag-Ti oxide gradients were also evaluated under UV illumination, as Ag deposits on crystalline TiO2 can enhance photocatalytic properties. In this work, however, the TiO2 was amorphous and UV illumination caused a slight reduction in the antibacterial effect of silver ions. This was attributed to a UV-induced SOS response in the S. epidermidis bacteria.The results of this thesis demonstrate that both TiO2 photocatalysis, or UV induced activation of Ti-peroxy radical species, as well as incorporation of silver are viable antibacterial strategies for titanium biomaterials. However, their clinical applications are still pending risk-benefit analyses of potential adverse host tissue responses.
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| 28. |
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| 29. |
- Unosson, Erik, 1983-, et al.
(författare)
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In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin films
- 2016
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 27:3
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Tidskriftsartikel (refereegranskat)abstract
- Implanted materials are susceptible to bacterial colonization and biofilm formation, which can result in severe infection and lost implant function. UV induced photocatalytic disinfection on TiO2 and release of Ag+ ions are two promising strategies to combat such events, and can be combined for improved efficiency. In the current study, a combinatorial physical vapor deposition technique was utilized to construct a gradient coating between Ag and Ti oxide, and the coating was evaluated for antibacterial properties in darkness and under UV light against Staphylococcus epidermidis. The findings revealed a potent antibacterial effect in darkness due to Ag+ release, with near full elimination (97%) of viable bacteria and visible cell lysis on Ag dominated surfaces. The photocatalytic activity, however, was demonstrated poor due to low TiO2 crystallinity, and UV light irradiation of the coating did not contribute to the antibacterial effect. On the contrary, bacterial viability was in several instances higher after UV illumination, proposing a UV induced SOS response from the bacteria that limited the reduction rate during Ag+ exposure. Such secondary effects should thus be considered in the development of multifunctional coatings that rely on UV activation.
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| 30. |
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| 31. |
- Unosson, Erik, et al.
(författare)
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Photocatalytic activity of low temperature oxidized Ti-6Al-4V
- 2012
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 23:5, s. 1173-1180
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Tidskriftsartikel (refereegranskat)abstract
- Numerous advanced surface modification techniques exist to improve bone integration and antibacterial properties of titanium based implants and prostheses. A simple and straightforward method of obtaining uniform and controlled TiO2 coatings of devices with complex shapes is H2O2-oxidation and hot water aging. Based on the photoactivated bactericidal properties of TiO2, this study was aimed at optimizing the treatment to achieve high photocatalytic activity. Ti-6Al-4V samples were H2O2-oxidized and hot water aged for up to 24 and 72 h, respectively. Degradation measurements of rhodamine B during UV-A illumination of samples showed a near linear relationship between photocatalytic activity and total treatment time, and a nanoporous coating was observed by scanning electron microscopy. Grazing incidence X-ray diffraction showed a gradual decrease in crystallinity of the surface layer, suggesting that the increase in surface area rather than anatase formation was responsible for the increase in photocatalytic activity.
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| 32. |
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| 33. |
- Unosson, Erik, 1983-, et al.
(författare)
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Reactive combinatorial synthesis and characterization of a gradient Ag–Ti oxide thin film with antibacterial properties
- 2015
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1742-7061 .- 1878-7568. ; 11, s. 503-510
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Tidskriftsartikel (refereegranskat)abstract
- The growing demand for orthopedic and dental implants has spurred researchers to develop multifunc- tional coatings, combining tissue integration with antibacterial features. A possible strategy to endow titanium (Ti) with antibacterial properties is by incorporating silver (Ag), but designing a structure with adequate Ag+ release while maintaining biocompatibility has been shown difficult. To further explore the composition–structure–property relationships between Ag and Ti, and its effects against bacteria, this study utilized a combinatorial approach to manufacture and test a single sample containing a binary Ag–Ti oxide gradient. The sample, sputter-deposited in a reactive (O2) environment using a custom-built combinatorial physical vapor deposition system, was shown to be effective against Staphylococcus aureus with viability reductions ranging from 17 to above 99%, depending on the amount of Ag+ released from its different parts. The Ag content along the gradient ranged from 35 to 62 wt.%, but it was found that structural properties such as varied porosity and degree of crystallinity, rather than the amount of incor- porated Ag, governed the Ag+ release and resulting antibacterial activity. The coating also demonstrated in vitro apatite-forming abilities, where structural variety along the sample was shown to alter the hydrophilic behavior, with the degree of hydroxyapatite deposition varying accordingly. By means of combinatorial synthesis, a single gradient sample was able to display intricate compositional and structural features affecting its biological response, which would otherwise require a series of coatings. The current findings suggest that future implant coatings incorporating Ag as an antibacterial agent could be structurally enhanced to better suit clinical requirements.
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| 34. |
- Unosson, Erik, 1983-, et al.
(författare)
-
Stability and prospect of UV/H2O2 activated titania films for biomedical use
- 2013
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 285:Part B, s. 317-323
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Tidskriftsartikel (refereegranskat)abstract
- Biomedical implants and devices that penetrate soft tissue are highly susceptible to infection, but also accessible for UV induced decontamination through photocatalysis if coated with suitable surfaces. As an on-demand antibacterial strategy, photocatalytic surfaces should be able to maintain their antibacterial properties over repeated activation. This study evaluates the surface properties and photocatalytic performance of titania films obtained by H2O2-oxidation and heat treatment of Ti and Ti-6Al-4V substrates, as well as the prospect of assisting photocatalytic reactions with H2O2 for improved efficiency. H2O2-oxidation generated a nanoporous coating, and subsequent heat treatment above 500 °C resulted in anatase formation. Tests using photo-assisted degradation of rhodamine B showed that prior to heat treatment, an initially high photocatalytic activity (PCA) of H2O2-oxidized substrates decayed significantly with repeated testing. Heat treating the samples at 600 °C resulted in stable yet lower PCA. Addition of 3% H2O2 during the photo-assisted reaction led to a substantial increase in PCA due to synergetic effects at the surface and H2O2 photolysis, the effect being most notable for non-heat treated samples. Both heat treated and non-heat treated samples showed stable PCA through repeated tests with H2O2-assisted photocatalysis, indicating that the combination of H2O2-oxidized titania films, UV light and added H2O2 can improve efficiency of these photocatalytic surfaces.
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| 35. |
- Unosson, Erik, et al.
(författare)
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Synergetic inactivation of Staphylococcus epidermidis and Streptococcus mutans in a TiO2/H 2O2/UV system
- 2013
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Ingår i: Biomatter. - : Informa UK Limited. - 2159-2535. ; 3:4, s. e26727-
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Tidskriftsartikel (refereegranskat)abstract
- TiO 2 photocatalysis can be used to kill surface adherent bacteria on biomaterials, and is particularly interesting for use with percutaneous implants and devices. Its efficiency and safety, however, depend on the activation energy required. This in vitro study investigates synergetic effects against the clinically relevant strains S. epidermidis and S. mutans when combining photocatalytic surfaces with H 2O 2. After 20 min exposure to 0.1 wt% H 2O 2 and UV light on TiO 2 surfaces, viabilities of S. epidermidis and S. mutans were reduced by 99.7% and 98.9%, respectively. Without H 2O 2 the corresponding viability reduction was 86% for S. epidermidis and 65% for S. mutans. This study indicates that low concentrations of H 2O 2 can enhance the efficiency of photocatalytic TiO 2 surfaces, which could potentially improve current techniques used for decontamination and debridement of TiO 2 coated biomedical implants and devices.
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| 36. |
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| 37. |
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| 38. |
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