| 1. |
- Alshammari, Hatem
(författare)
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Antimicrobial potential of strontium against bacteria associated with peri-implantitis
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dental implants are nowadays a standard treatment to replace missing teeth and restore function and aesthetics. However, biological complications associated with implants, e.g., peri-implant infections, are common and jeopardize the success of treatment. The main aim of this thesis was to explore strontium (Sr) as a possible prevention strategy against peri-implant infections, since Sr has been shown to have antibacterial action and also to promote titanium (Ti) implant osseointegration. In this thesis, a systematic appraisal of the literature about the antimicrobial potential of Sr-functionalized Ti surfaces for oral applications was performed, and was followed by a series of in vitro studies assessing the antimicrobial potential of Sr against micro-organisms associated with peri-implantitis.In Study I, the systematic appraisal of the literature resulted in an initial list of 1081 potentially relevant publications, where from nine publications from in vitro studies met the inclusion criteria. Most of the included studies showed that Sr-functionalized Ti exerted a limited immediate (i.e., 24 h) antimicrobial effect, likely due to a low Sr ion release; a relevant antimicrobial effect and biofilm inhibition potential against Streptococcus aureus was observed at both early and late timepoints, with an adequate Sr ion release.Study II assessed, in vitro, five different concentrations of soluble Sr(OH)2 (100, 10, 1, 0.1, and 0.01 mM) against 6 different mono-species bacteria (Streptococcusmitis, Staphylococcus epidermidis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Escherichia coli, and Fusobacterium nucleatum) in terms of cell growth, minimal inhibitory concentration (MIC), and biofilm viability. In the agar diffusion test, zones of inhibition were only observed for 0.01, 0.1, and 1 mM of Sr(OH)2 against P. gingivalis. Growth inhibition in planktonic cultures was achieved at 10 mM for all species tested. In the biofilm viability assay, 10 and 100 mM Sr(OH)2 showed potent bactericidal effect against S. mitis, S. epidermidis, A. actinomycetemcomitans, E. coli, and P. gingivalis. It was thus concluded that Sr(OH)2 has antimicrobial properties against bacteria associated with peri-implantitis.Study III assessed the in vitro early- and late bacteriostatic and bactericidal effect of Sr-functionalized wafers on bacteria associated with peri-implantitis (E. coli,S. aureus, Streptococcus oralis, Actinomyces naeslundii, Parvimonas micra, P.gingivalis and F. nucleatum) as mono-species after 2 and 24 hours, and as multispecies at day 1, 3, and 6. Sr-functionalized wafers, compared to Ti controls, were associated with statistically significant less viable cells in both mono- and multispecies tests. Number of colony forming units (CFUs) within the biofilm were significantly higher in Ti wafers, compared to Sr-functionalized wafers, for S. aureus at all time-points of evaluation and for E. coli at day 1. Gingipain activity was higher in Ti wafers compared to Sr-functionalized ones, and the qPCR showed that P. gingivalis comprised 15% of the total biofilm on Ti wafers at day 6, while it remained below detection levels at Sr-coated wafers.In Study IV, the impact of Ti surface roughness (turned vs moderately rough) on the antimicrobial effect of Sr on bacterial associated with peri-implantitis (S. oralis, P. micra, A. naeslundii, F. nucleatum, P. gingivalis, S. aureus, and E. coli), grown in different multispecies consortia, was assessed in vitro. Bacterial viability and biofilm formation, and well as, proteolytic activity of P. gingivalis were assessed at day 1, 3, and 6. Sr-functionalized surfaces were associated with statistically significant reduction in number of viable cells compared to nonfunctionalized surface at all times of investigation for all multispecies tested. Higher proteolytic activity of P. gingivalis was found at non-functionalized Ti disks compared to Sr-functionalized ones. Sr-functionalised surfaces were associated with notable growth inhibition of both E. coli and S. aureus, while P. gingivalis remined undetected at all time points of evaluation on all disks. The turned surface had a slightly higher release of Sr ion compared with the moderately rough surface in the first 24 hours, while both surfaces showed a sustained release for up to 15 days.Overall, the data generated with this series of projects indicate Sr surfaces exerts an antimicrobial potential on bacteria associated with peri-implantitis and it is worthwhile to further explore the potential of Sr-functionalized Ti in the prevention of peri-implant infections.
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| 2. |
- Kloukos, Dimitrios
(författare)
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Gingival recession development in orthodontic patients : studies on gingival phenotype diagnostics, local and systemic biomarkers, and the impact of orthodontic treatment on gingival recession development
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gingival recession refers to the apical displacement of the gingival margin from the cemento-enamel junction, resulting in exposure of the root of the tooth. Recessions can be localized, involving a single surface and tooth or may involve more tooth surfaces and/or teeth. Exposure of the root surface often causes a esthetic concerns, dentin hypersensitivity and increased susceptibility to root caries. Gingival recessions have been found to be more frequent in mandibular than maxillary teeth, and on buccal than lingual surfaces, especially within creasing age and have been found in persons with both good and poor oral hygiene.Several factors are associated with the etiology of gingival recessions; these are often categorized in predisposing and causative factors. A possible etiological factor for gingival recession is orthodontic tooth movement. The precise mechanism, nevertheless, by which orthodontic treatment influences the occurrence of recessions remains unclear, since bone dehiscence development during orthodontic treatment, per se, does not always lead to recession. It has been, therefore, assumed that the presence of a bone dehiscence before the beginning of orthodontic therapy is a prerequisite for the development of gingival recession. The retrospective and uncontrolled design of the available studies up to date, have not yet allowed the elucidation of the treatment- or patient- related risk factors for the development of gingival recession.The overall aims of this thesis were:• to determine whether or not orthodontic treatment is associated with the development of gingival recession and to quantify its magnitude and significance.• to document possible periodontal and systemic factors that are linked with gingival recession before, during or after orthodontic therapy.This thesis is based on 6 studies:• Paper I was designed as a cross-sectional study to determine accuracy and reproducibility of four different methods for assessing gingival thickness.• Paper II comprised an ex-vivo study assessing how well transgingival probing represents the true value of soft tissue thickness. The aim of this study was to assess differences and variation in gingival thickness when measured with transgingival probing or scanned with an intraoral device in porcine cadavers.• Paper III evaluated in a prospective manner if bone remodeling can be followed through the bone turnover markers (BTMs) in orthodontic patients. Aim was to record the fluctuation of an osteoclastic and an osteoblastic BTM [C-terminal telopeptide of type I collagen (CTX) and N-terminal pro-peptide of type I pro-collagen (PINP), respectively] in both the gingival crevicular fluid (GCF) and the serum of orthodontic patients before and after the initial application of orthodontic forces.• Paper IV assessed in a prospective process the impact of fixed orthodontic appliances on blood Count and High-Sensitivity C-Reactive Protein Levels. Aim was to elucidate the magnitude of alterations in systemic blood counts in healthy individuals and identify possible inflammation status during the first period after fixed orthodontic appliance placement.• Paper V was a prospective controlled study aimed to assess whether incisor inclination change during orthodontic treatment with fixed appliances affects gingival thickness and the width of keratinized gingiva at mandibular incisors, compared with an untreated group of participants.• Paper VI was a prospective controlled study to assess whether orthodontic treatment with fixed appliances, compared to no treatment, has an effect on the development of gingival recession up to one year after treatment.The following conclusions were drawn:Paper I• The results demonstrated the differences between the tested methods (a.transgingival probing with a standard periodontal probe, b. transgingival probing with a stainless-steel acupuncture needle, c. ultrasound and d. color-coded periodontal probe), as far as accuracy and reproducibility were concerned.• Based on the reproducibility, the transgingival probing with the periodontal probe as well as the ultrasound determination seem to present an adequate choice for everyday practice.Paper II• Transgingival probing with a standard metal periodontal probe for assessing gingival thickness is a reliable method, with values very close to the true gingival thickness, and it can thus be considered as the clinical gold standard.Paper III• This was the first time PINP and CTX have been evaluated in the GCF and serum of orthodontic patients with fixed appliances.• No statistically significant alterations of CTX and PINP levels in the GCF and the serum of patients were recorded over time during the initial stages of orthodontic treatment.Paper IV• Orthodontic fixed appliances led to a limited and transient change in WBC and Hb levels during the first days after bracket placement.• The fluctuation of hs-CRP levels was not significant, demonstrating a lack of association between systemic inflammation and orthodontic treatment.Paper V• Mandibular incisor proclination during orthodontic treatment does not appear to significantly alter gingival thickness and width of keratinized gingiva, but orthodontic treatment, overall, leads to reduction of the width of keratinized gingiva.• Whether this limited reduction of width of keratinized gingiva during orthodontic therapy has an impact on the development of gingival recessions, especially on the long-term, still remains to be elucidatedPaper VI• Evolution of recessions varied during orthodontic treatment: in some patients recession developed over time, but in several cases orthodontic treatment resulted in a reduction in the number of gingival recessions. The most affected teeth were the canines and the first premolars.• Orthodontic therapy exerted a negative impact on the development of gingival recession at 1-year posttreatment. The adjusted incidence rate was 67% higher for the intervention group versus the control; however, the severity was limited since most recessions were up to 1mm.• A long-term follow-up (5 years or more) after orthodontic treatment is necessary to provide data on whether orthodontic treatment is a major risk factor for the development of gingival recession.Key Conclusions and Clinical Implications• Transgingival probing with the periodontal probe as well as the ultrasound determination present an adequate choice for gingival thickness evaluation.• No statistically significant alterations of CTX and PINP levels in the gingival crevicular fluid and the blood serum of patients were recorded over time during the initial stages of orthodontic treatment. Moreover, a lack of association between systemic inflammation and orthodontic treatment during the first days after bracket placement was demonstrated.• Mandibular incisor proclination during orthodontic treatment does not appear to significantly alter gingival thickness and width of keratinized gingiva, but orthodontic treatment, overall, may lead to reduction of the width of keratinized gingiva.• Evolution of recessions varied during orthodontic treatment: in some patients recessions developed over time, but in several cases orthodontic treatment resulted in a reduction in the number of gingival recessions. The most affected teeth were the canines and the first premolars.• Orthodontic therapy exerted a negative impact on the development of gingival recession at 1-year post treatment. The adjusted incidence rate was 67% higher for the intervention group versus the control; however, the severity was limited, since most recessions were up to 1mm.• A detailed 3D analysis of the movement of the involved teeth presenting recession after orthodontic movement could provide further insights on the effect of orthodontic tooth movement on the development of gingival recession.• A long-term evaluation will show whether orthodontic treatment is a major factor for the development of gingival recession.
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| 3. |
- Aghazadeh, Ahmad
(författare)
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Peri-implantitis : risk factors and outcome of reconstructive therapy
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on (I) the outcome of reconstructive treatment of peri-implant defects and (II) risk factors for the development of peri-implantitis.BackgroundAn increasing number of individuals have dental implant-supported reconstructions. The long-time survival rate of dental implants is good, but complications do occur. Accumulation of bacteria on oral implants and the development of a pathogenic biofilm at the mucosal margin will result in inflammatory responses diagnosed as peri-implant mucositis(PiM). Furthermore, PiM may progress to peri-implantitis (Pi) involving the implant-supporting bone and potentially result in a severe inflammatory process resulting in alveolar bone destruction and consequently implantloss. Currently, Pi is a common clinical complication following implant therapy.The prevalence of peri-implantitis has been reported to be around 20 %. Susceptibility to infections and a history of periodontitis are considered as important risk indicators for peri-implantitis. It seems logical that a past history of periodontitis is linked to an increased risk of peri-implantitis. It is possible that other patient-associated factors such as a smoking habit, and presence of general diseases may also be linked to a higher risk for developing peri-implantitis.Treatment of peri-implantitis is difficult. Non-surgical treatment modalities may not be sufficient to resolve the inflammatory process to obtain healthy conditions.Surgical treatment of peri-implantitis has commonly been employed in clinical practice to obtain access to the implant surface thereby increasing the possibility to effectively decontaminate the implant surfaces.The effectiveness and long-term outcomes of reconstructive surgical treatments of peri-implantitis has been debated. The scientific evidence suggests that regular supportive care is an essential component in order to maintain and secure long-term results following treatment of peri-implantitis.Aims1. To assess the short-term efficacy of reconstructive surgical treatmentof peri-implantitis (Study I).2. To analyse risk factors related to the occurrence of peri-implantitis(Study II).3. To assess the importance of defect configuration on the healing response after reconstructive surgical therapy of peri-implantitis (Study III).4. To assess the long-term efficacy of reconstructive surgical treatmentof peri-implantitis (Study IV).MethodsFour studies were designed to fulfil the aims:- A single-blinded prospective randomised controlled longitudinal human clinical trial evaluating the clinical and radiographic results of reconstructive surgical treatment of peri-implantitis defects usingeither AB or BDX.- A retrospective analysis of individuals with either peri-implantitis, or presenting with either peri-implant health, or peri-implant mucositis assessing the likelihood that peri-implantitis was associated with a history of systemic disease, a history of periodontitis, and smoking.- A prospective study evaluating if the alveolar bone defect configuration at dental implants diagnosed with peri-implantitisis related to clinical parameters at the time of surgical intervention and if the short- and long-term outcome of surgical intervention of peri-implantitis is dependent on defect configuration at the time of treatment.- A prospective 5-year follow-up of patients treated either with AB or BDX.Results- The success for both surgical reconstructive procedures was limited. Nevertheless, bovine xenograft provided evidence of more radiographic bone fill than AB. Improvements in PD, BOP, and SUP were observed for both treatment modalities-In relation to a diagnosis of peri-implantitis, a high likelihood of comorbidity was expressed in the presence of a history of periodontitis and a medical history of cardiovascular disease- The buccal-lingual width of the alveolar bone crest was explanatory to defect configuration- 4-wall defects and deeper defects demonstrated more radiographic evidence of defect fill- Reconstructive surgical treatment of peri-implant defects may result in successful clinical outcomes, that can be maintained over at least five years- The use of BDX is more predictable than use of harvested bone from the patient (AB)ConclusionsThe study results suggest that a bovine xenograft provides better radiographic evidence of defect fill than the use of autogenous bone harvested from cortical autologous bone grafts.Treatment with bone grafts to obtain radiographic evidence of defect fill is more predictable at 3- and 4-wall defects than at peri-implantitis bone defects with fewer bone walls.In relation to a diagnosis of peri-implantitis, a high likelihood of comorbidity was found for a history of periodontitis and a history of cardiovascular disease.
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| 4. |
- Abele, H., et al.
(författare)
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Particle physics at the European Spallation Source
- 2023
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Ingår i: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 1023, s. 1-84
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Forskningsöversikt (refereegranskat)abstract
- Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world’s brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
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