Doctoral Theses / Doktorsavhandlingar Institutionen för odontologi

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Assessment and management of oral health in nursing homes for older adults: Evaluation of structure, process and outcome
(2025-09-18) Bellander, Lisa
The oral health of older adults living in nursing homes in Sweden is generally poor, affecting their overall health and well-being negatively. This thesis aimed to explore and evaluate how oral health is assessed and managed in nursing homes, focusing on the preventive oral health care process using the ROAG-J (Revised Oral Assessment Guide – Jönköping) within the national quality register Senior Alert. The goal was to identify strengths and weaknesses in current practice to inform future improvements. Studies I and II were register-based and utilised Senior Alert data from 2011 to 2016, covering about 100,000 residents. The data included oral health assessment (ROAG-J), preventive actions and variables from other Senior Alert risk assessments. Study I found that approximately half of the residents in Swedish nursing homes had received at least one oral health assessment in 2016, with those with the greatest care dependency exhibiting the poorest oral health. Oral health was generally assessed as good using the ROAG-J, possibly indicating underreporting by nursing staff. Study II showed that approximately 60% of the residents that were assessed as having oral health problems also had received at least one preventive action, but overall, no clear improvements in oral health status were observed longitudinally. Study III was qualitative, exploring healthcare workers’ experiences of using the ROAG-J as well as planning and performing preventive oral care. Six focus groups with registered nurses and nurse assistants in nursing homes were conducted and analysed using reflexive thematic analysis. Results indicated that Senior Alert’s structured approach increased awareness and the prioritisation of oral health among staff. Challenges included resident resistance to oral care, the complexity of providing oral care to older adults with natural teeth and organisational issues such as unclear routines, insufficient training and unclear responsibilities. Study IV was a web- based survey including 464 respondents in leadership roles (managers, coordinators and registered nurses). Their views on oral health needs, routines, barriers and facilitators to good oral care were examined. Results showed widespread use and positive perceptions of the ROAG- J and Senior Alert. However, many residents were perceived to have substantial oral care needs, while staff often lacked sufficient training and materials for using the ROAG-J. Difficulties were reported especially when assisting with oral care in cases of non-cooperation among persons with dementia. In conclusion, oral care in nursing homes is complex and challenging, particularly among residents with cognitive impairment and care-resistant behaviour. A structured approach using the ROAG-J within Senior Alert can help increase the prioritisation and awareness of oral health and oral care; however, limited resources, insufficient training, unclear routines and a lack of defined responsibilities hinder both assessments and daily oral care. Future improvements require increased and continuous training, clearer role definitions, active leadership and enhanced collaboration with dental care services. Further research should focus on the development of educational interventions, the reliability of ROAG-J assessments, older adults’ experiences and preferences of oral care and interprofessional approaches to promote oral health.
On marginal bone resorption around oral implants
(2025-03-04) Reinedahl, David
The etiology of marginal bone loss (MBL) around osseointegrated implants remains controversial. Despite extensive research, the initiating causes of MBL are unclear. Long-term clinical studies challenge the notion that peri-implantitis, an infectious condition resulting in accelerating MBL over time, is the primary driver, as most implant failures occur early and decline over time. This thesis investigates alternative etiological factors for MBL, focusing on immune-mediated and iatrogenic causes. Study I systematically reviewed animal models for peri-implantitis, resulting in a qualitative synthesis of 133 studies and a meta-analysis of 35 studies. Plaque accumulation alone did not induce relevant MBL after up to 1.5 years. When artificial ligatures were added, as in 119 studies, MBL varied significantly depending on ligature materials and ligature application methods. The possibility that the ligature itself, due to its provocation of the immune system, could induce MBL, although refuted by some authors, was not tested in any of the reviewed ligature studies. Studies II and III examined possible immune-mediated MBL from aseptic ligatures in rabbit femurs and tibia using histology and qPCR, comparing silk and cotton ligatures to controls over 8 weeks (silk and cotton) and 12 weeks (silk). The studies confirmed significant MBL from ligatures at 8 weeks (p=0.007), with partial recovery at 12 weeks. At both time points, inflammatory infiltrates dominated by macrophages and foreign body giant cells surrounded all ligatures and were separated from resorbed bone surfaces by fibrous enclosure. M2 macrophages balanced inflammatory responses. Study IV compared chair-side cement-fitted (CR) and screw-fitted (SR) implant restorations over 1 year in 24 patients in a cross-over RCT design divided into three periods (P) of 16 + 16 + 20 weeks. Patients were randomly assigned to SR (group 1) or CR (group 2) at baseline. Restoration type was then swapped during P2, and during P3, both groups had SR. Radiographic MBL and clinical peri-implant indices were measured at baseline, 16, 32, and 52 weeks. The immunological response was assessed by qPCR on peri-implant soft tissue biopsies at 32 weeks. MBL was observed during periods with CR in both groups, and bone gain was observed during periods with SR. Differences in MBL were significant between groups during P1 (p = 0.006) and P2 (p < 0.001) and within group 2 during P1 (p = 0.002). Further, a 7-fold upregulation of IL-6 was found from CR after P2. Excess cement was found in 75% of all CR cases upon removal. In summary, this thesis demonstrates that immune-material interactions beyond the presence or absence of infection regulate MBL. Further, MBL recovery may occur after removing iatrogenic factors such as excess cement.
Kariesriskfaktorer och riskindikatorer hos förskolebarn
(2024-11-19) Ingemansson Hultquist, Ann
Background and aim: Caries is one of the most common diseases in preschool children. Pain, infections and sleep disturbances in childhood caries can adversely affect body weight and nutritional ability and may raise the risk of the disease continuing into adulthood. Modern dentistry is able assess caries risk and weight risks and protective factors on an individual basis. The general aim of this thesis was to determine risk factors and risk indicators for caries in preschool children through analyses of oral, environmental, and social factors. Patients and Methods: Paper I, II and III followed the dental records for children ages 1-6 years. At age 1, data on oral risk factors, environmental factors and presence of mutans streptococci were retrieved; at ages 1 and 3, caries risk assessment were performed and at ages 3 and 6 years, caries status were collected. Factors associated to caries risk were studied. Paper IV, a registry-based study that retrieved data on caries status from 3 to 6 years of age. The data included caries risk assessment and social factors from ages 3 to 5 years. Caries risk assessment models were designed, adding environmental and social factors, to established caries risk assessment. Results: Presence of mutans streptococci at age 1 year were associated to caries at 3 and 6 years of age. Environmental factors at age 1 year, siblings with caries, and beverage other than water between meals were associated to presence of MS (Paper I) and together with night meals associated to caries at 3- and 6-years of age (Papers II, III). Social factors, foreign background, low parental education level, three or more siblings and living in a one-parent family were associated to caries at 6 years of age. Supplementing a caries risk assessment with environmental and social factors in predictive models improved the ability of the model to predict caries progression, the predictive ability of the assessment improved more at younger ages than at older ages vi (Papers II, III, IV), and was higher when intervals between the risk assessment and oral examination were shorter (Papers III and IV). Conclusion: Risk factors found during an oral examination as well as information about the child's environmental- and social conditions should be included in a caries risk assessment. Environmental and social indicators at one year of age regarding; siblings with caries, night meals and beverage other than water between meals can replace saliva tests to find the risk factor mutans streptococci. Social indicators have a greater impact on younger children's caries risk compared to older children.
Behavioral Intervention for Improved Oral Hygiene in Adolescents - A Person-Centered and Theory-Based Approach
(2024-04-18) Lod Dimenäs, Sandra
To educate and enhance patients’ motivation for adequate oral hygiene, that is self-performed periodontal infection control, is essential in the prevention of periodontal disease. Surveys have shown poor oral hygiene conditions among Swedish adolescents, indicating a need for more effective educational/behavioral interventions. The overall aim was to contribute to the development of efficient educational interventions, directed at adolescents, to improve oral hygiene behavior and promote periodontal health. Studies I & II were based on a randomized field study on the effectiveness of a person-centered, theory-based, behavioral intervention (test) for improved oral hygiene, compared with conventional information/instruction (control). The field study involved 312 adolescents and 30 dental hygienists (DHs). Study I included 274 adolescents treated per protocol and with clinical data from baseline and 6 months. Bleeding and plaque scores improved in both groups, with greater improvements in the test group. At 6 months, adolescents in the test group used oral hygiene aids more frequently compared with the control group. Study II included 276 adolescents treated per protocol and with questionnaire data from baseline and 6 months. The test group was more satisfied with the education provided and the communication with the DH during therapy, compared with the control group. In addition, the test group reported to a larger extent that they were much more careful regarding their oral hygiene habits after treatment and had higher confidence about keeping up healthy gingival conditions. Studies III & IV were qualitative interview studies. Study III included 19 adolescents treated in accordance with the test intervention. They experienced the intervention towards improved oral hygiene behavior as a challenging journey and highlighted the importance of a person-centered approach in treatment. Personal insight about the importance of improved oral hygiene was fundamental for behavioral change. Planning and monitoring of behavior, with guidance and support, facilitated behavioral change and encouraged continued efforts. Still, they expressed a need of reminders and support to keep up oral hygiene routines over time. Study IV included 13 DHs who had worked in accordance with the test intervention. They experienced a changed professional approach, going from experts to encouraging partnership, which was considered challenging but more enjoyable. Prerequisites for implementing such an intervention in daily practice were adequate knowledge and skills, own interest and willingness for a change and a supportive work environment. The expenditure of time in relation to economic demands were seen as main barriers. In conclusion, the findings suggest that a person-centered, theory-based, behavioral intervention is more beneficial for the adolescent patient compared with conventional information/instruction. The findings contribute to further development of such a person-centered, theory-based, approach, and provide an understanding of the prerequisites and barriers on a professional and organizational level to consider for implementation in daily practice.
Endodontic inflammatory disease and myocardial infarction
(2024-01-15) Sebring, Dan
Atherosclerosis is the underlying cause to suffering an acute myocardial infarction. Disruption of atherosclerotic plaques lead to thrombus formation and occlusion of the coronary arteries which impedes blood supply to the heart. Inflammation plays a role in the pathogenesis. Through spread of pro-inflammatory mediators, oral inflammatory diseases may contribute to the risk of acute coronary events. The PAROKRANK study reported an independent association between marginal periodontitis and the risk of acute myocardial infarction. The main objective of this thesis was to explore if a similar association exists between endodontic inflammatory disease and acute myocardial infarction. Study I addressed observer reliability in assessment of endodontic variables in panoramic radiographs. Calibration improved agreement between three observers and a reference standard in assessment of periapical lesions (from weighted  0.22, 0.30 and 0.60 to 0.59, 0.64 and 0.80 respectively). In Study II, endodontic variables in PAROKRANK patients and controls were compared. Following adjustment for confounders, more missing teeth increased the risk (OR 1.04; 95% CI 1.02-1.06), whilst number of filled teeth reduced the risk (OR 0.98; 95% CI 0.96-1.00), of myocardial infarction. Decayed teeth (OR 1.18; 95% CI 1.02-1.37) and primary apical periodontitis (OR 1.57; 95% CI 1.08-2.29) increased the risk in younger age-groups while root filled teeth (OR 1.18; 95% CI 1.03-1.36) increased risk in older age groups. Study III explored a composite of endodontic inflammatory disease as an indicator of acute myocardial infarction. In a multivariable logistics regression model, the composite, calculated as the sum of seven weighted endodontic variables, best predicted the risk of myocardial infarction (OR 1.97; 95% CI 1.23-3.17). Study IV analysed correlations between endodontic variables and systemic levels of pro-inflammatory markers in blood. In adjusted analyses, presenting ≥1 root filled tooth related to lower levels of several cytokines (IL-1, IL-2, IL-6, and IL-12p70), whilst ≥1 primary apical periodontitis related to higher levels of interleukin-8 (=0.06). In Study V, national registries were assessed for mortality and morbidity data of the PAROKRANK cohort during a follow-up of eight years. Following adjustment for confounders, remaining teeth and non-root filled teeth decreased the risk of future events, whilst higher DMFT-score increased the risk and ≥1 primary apical periodontitis decreased the risk of suffering cardiovascular events. Higher DMFT-score and decayed teeth increased the risk of all-cause mortality.
Functional characteristics of periodontitis and peri-implantitis lesions in humans
(2023-11-14) Dionigi, Carlotta
In the current series of studies functional characteristics of periodontitis and peri-implantitis lesions in humans were investigated. Cell markers for antimicrobial activity were used to evaluate differences between periodontitis and peri-implantitis lesions (Study I), while epigenetic and oxidative stress markers were used to compare periodontitis lesions in smokers and non-smokers (Study II). The occurrence and localization of titanium micro-particles were assessed in tissue samples obtained from dental implant sites with and without peri-implantitis and the influence of titanium particles on gene expression profiles was investigated in peri-implantitis lesions (Study III). Gene expression profiles were analyzed in tissue samples obtained from dental implant sites with and without peri-implantitis by integrating spatial transcriptomics and RNA-sequencing data (Study IV). It was demonstrated that: - Peri-implantitis lesions were larger and presented with significantly larger densities of cells with antimicrobial activity than periodontitis lesions. In both lesions, cellular densities were higher in the inner zone, lateral to the pocket epithelium, than in the outer compartment of the lesion. The non-infiltrated connective tissue in peri-implantitis specimens showed significantly higher densities of cells with antimicrobial activity than that in periodontitis specimens (Study I). - Although periodontitis lesions did not differ in size between smokers and non-smokers, differences in cellular functions were observed. Periodontitis lesions in smokers presented with diminished antimicrobial activity and lower levels of epigenetic markers than lesions in non-smokers (Study II). - Densities of titanium micro-particles in peri-implant tissues varied across patients but not between dental implant sites with and without peri-implantitis within the same individual. The titanium micro-particles were of similar size and morphology and mainly located in a 2-mm wide tissue zone close to the implant, in samples with and without peri-implantitis. Out of >36000 analyzed genes, only 14 were differentially expressed when comparing peri-implantitis specimens with high and low densities of titanium micro-particles (Study III). - A clear association was observed between distinct gene clusters and specific compartments in peri-implant tissues. Peri-implantitis specimens showed overall higher levels of gene activity than specimens from reference implant sites. Several pathways specific for the activation of the host response towards bacterial insults were clearly dysregulated in peri-implantitis specimens (Study IV).
The Oral Hygiene Ability Instrument-OHAI Development and evaluation of an instrument measuring the cause of poor oral hygiene self-care in older adults
(2023-11-02) Grönbeck-Lindén, Ingela
Oral hygiene is an important preventive measure to maintain good oral health in the growing group of older adults. Oral hygiene often deteriorates with age, but the causes of this at the individual level are rarely investigated. One reason of several may be that a multifactorial assessment instrument is missing. The aim of this thesis was therefore to develop and evaluate an instrument to assess the cause of any inability for older adults to manage daily oral care. The qualitative Study I aimed to identify factors that affect older adults’ ability to manage oral hygiene. Focus group interviews (n = 4) were conducted with dental hygienists, occupational therapists, assistant nurses, and older adults. Data were analysed using content analysis. The results were formulated into the core category “Oral hygiene is a complex activity” that is influenced by psycho-logical, functional, and environmental factors. Inclusion criteria for Studies II-IV were: 1) age ≥ 65 years, 2) at least one natural tooth or osseointegrated implant, and 3) ability to manage oral hygiene independently. Study II describes the development process of the Oral Hygiene Ability Instrument (OHAI), which comprised three phases: planning, construction, and evaluation. The construction phase was based largely on the results of Study I. The evaluation phase resulted in the reduction of OHAI from 47 to 33 items. OHAI came to consist of three parts: Part I – interview, Part II – clinical examination, and Part III – observation of the oral hygiene activity. Based on the results of Parts I-III, the rater (a dental staff member) conducts a summary assessment of the impact of ten factors (cognitive function, frailty, motivation, vision, fine motor skills, coordination knowledge of oral hygiene, spatial ability, oral clearance, and balance) on the individual’s oral hygiene ability. Study III concerned the reliability of OHAI. Part I (interview) was tested for test–retest reliability on 37 older adults. Parts II and III were tested for intra-/interrater reliability. Four dental professionals assessed 15 films and intraoral photos of older adults undergoing OHAI assessment. Parts I and III were found to have acceptable-to-good test-retest and intra-/interrater reliability, respectively; however, five items in Part II displayed limited reliability. In Study IV, the OHAI was tested for criterion and construct validity in a stroke group (n = 50), a group with cognitive impairment (n = 49), and a group of general dental patients (n = 50). Criterion validity was analysed, with sensitivity/ specificity showing acceptable-to-good agreement. To test for construct validity, known-group validity analysis, factor analysis, and Rasch analysis were used. In general, OHAI demonstrated good criterion and construct validity. However, Study IV, like Study III, showed potential for improvement for some items, which meant that some minor changes were implemented in the OHAI to obtain a more robust and easier-to-use instrument. In conclusion, oral hygiene was found to be a complex activity that needs to be supported in different ways depending on the cause of the lack of ability. The development of the OHAI means that there now is a valid and reliable instrument for the assessment of the cause of an older adult’s inability to manage oral hygiene.
On biological response and wear particles around oral implants and implant components
(2023-11-01) Olander, Julia
ABSTRACT Wear particles released from implant components are gaining interest in the dental literature. In orthopedic medicine, wear particles are known to cause bone loss around medical implants in an aseptic manner and several in vitro studies have shown proinflammatory responses to titanium particles. In dentistry and medicine, several materials are used for implant constructions, with a variation in material properties such as hardness and surface roughness. Theoretically, dissimilarity in material combination may cause aggravation as the materials wear. Due to aesthetical advantages, ceramic abutments made from zirconia are increasingly used in dentistry. Zirconia is harder than titanium, which could lead to more wear and particle release. It is unknow whether wear particles in tissues around dental implants cause peri-implant bone loss. This thesis investigates whether the combination of materials in dental implant constructions alters biological responses and release of wear particles. Specifically, the studies included in this thesis compare single implant crowns manufactured with two abutment materials regarding clinical outcomes (Study I), in vitro wear on two implant materials (Study II), inflammatory cell responses (Study III), gene expression and presence of particles in soft tissues (Study IV). In Study I, we retrospectively analyzed data from patients treated at a specialist clinic with implant-supported crowns manufactured with two abutment types – zirconia and titanium. These analyses focused on clinical outcome variables with respect to function up to five years after prosthetic placement. In Study II, we evaluated experimental dynamic loading to compare wear, corrosion, and wear particle generation when these two abutment materials were used to connect to two types of implant materials. In Study III, we investigated the proinflammatory response to human peripheral blood mononuclear cells (PBMCS) when exposed to two types of disc materials combined with two particle materials. In Study IV, we evaluated mucosa biopsies from patients with single implant supported crowns manufactured on two abutment materials, focusing on gene expression and presence of wear particles. The following conclusions were drawn from the thesis. Study I show that abutment material type was statistically significantly associated with amount of yearly bone loss and accumulated five-year bone loss in this cohort but did not affect occurrence of technical complications. Implants with zirconia abutment showed an increase in bone loss but a decrease in technical complications compared to titanium. However, limitations in this finding include small sample size and only slight differences in bone loss values, which may not be clinically relevant. Study II shows that all implants had signs of wear irrespective of abutment material. No clear difference was seen comparing material combinations. Particles were released from the implant-abutment junction and the internal connections harbored wear particles inside the implants. More particles were released when using zirconia abutments. Study III shows that titanium particles and discs generated a higher proinflammatory response compared to zirconia. Neutrophils reacted to zirconia particles by releasing neutrophilic extracellular traps (NETs), which was not seen when exposed to titanium particles. In Study IV, we found titanium wear particles in soft tissue samples and zirconia particles on implant heads. More particles were found in mucosa around zirconia abutments. Gene expression showed upregulation of several proinflammatory genes when using zirconia abutment compared to titanium abutment. Wear particles may trigger pro-inflammatory reactions in the peri-implant mucosa.
On oral health before and after obesity treatment
(2023-09-12) Taghat, Negin
The overall aim of this thesis was to study the oral health of individuals with obesity and how oral health may be affected by medical and surgical obesity treatment. The thesis comprises three study populations, with Paper I and IV studying female participants, while Paper II and III includes both genders. Paper I is a cross-sectional study of obese women (Body Mass Index, BMI 35 kg/m2 or more, n = 118), with the aim to describe oral health with increasing degrees of obesity and associations between obesity and dental caries. Paper II is a case series designed to describe the oral health profile of bariatric individuals (n = 14). Paper III is a questionnaire study aimed to examine how individuals (n = 1182) treated with gastric bypass perceived their oral health and oral health related quality of life (OHRQoL). Paper IV is a longitudinal follow-up study of the Paper I population aimed to compare the effect of bariatric surgery with medical obesity treatment on dental caries estimates until two years after the intervention. The results demonstrated that obese women had poor oral health habits and that there was an association between increasing degrees of obesity and dental caries frequency. The associations were robust, also after adjusting for confounders (Paper I). After bariatric surgery, both women and men may struggle with oral health problems with high frequencies of dental caries and hyposalivation (Paper II). In Paper III, a high proportion of women and men who underwent bariatric treatment reported poor self-perceived oral health and impacts on their OHRQoL. A longitudinal follow-up showed a higher frequency of caries lesions in women two years after surgical obesity treatment but not after medical treatment. The positive associations between surgical obesity treatment and dental caries were robust also after adjustments for confounders (Paper IV). In conclusion, the findings in this thesis indicate poor oral health and higher caries frequency with increasing BMI (Body Mass Index) in obese women, and oral health problems were observed in both men and women following bariatric surgery with impacts on OHRQoL. The findings can serve as a basis for adapting preventive dental care for obese and bariatric patients.
Effects of silicon on bone. Clinical observations and experimental cell studies.
(2023-08-16) Catarina Magnusson
Bone health has a major impact on life quality. In Sweden, osteoporosis is a highly prevalent skeletal disease that primarily affects the elderly, causing fragility fractures and pain. Local pathological bone defects due to traumas, infectious (such as periodontitis) or malignant diseases (such as osteosarcoma and bone metastases), and congenital abnormalities, may need to be corrected for optimal skeletal function. Silicon (Si), which is a trace element found in beverages and plant-based food, is suggested to promote bone health. Silicon is also a constituent of some bone-substitute materials, and the release of Si is suggested to contribute to bone regeneration. In line with this, experimental studies have demonstrated direct stimulatory effects of Si on osteoblast differentiation and function, whereas only a few studies have examined the effects of Si on osteoclasts. Knowledge regarding the effect of Si on osteoclasts and the regulatory mechanisms of bone cells is currently limited. Thus, the aims of this thesis were to study these aspects further. As reports on Si metabolism among different population groups are scarce, this thesis also aimed to describe Si excretion in relation to gender, pregnancy, and lactation, together with considering the aspects of bone changes in the latter two conditions. In Paper I, the direct effects of Si at different time-points on osteoclast differentiation in a murine macrophage cell line were investigated. In Paper II, we examined whether there is transmembrane passage of Si in bone cell precursors, and if the expression of genes for potential Si-transport proteins is regulated. In Paper III, the effects of Si were further investigated with regard to human osteoclast differentiation and bone resorption. In Paper IV, the 24-hour urinary Si excretion levels were compared between men, non-pregnant women, and pregnant women. In Paper V, the levels of Si in spot-urine samples were longitudinally measured from late pregnancy to 18 months post-partum, and compared in relation to lactation length and bone mineral density changes. The results of the experimental cell studies in this thesis demonstrate a direct inhibitory effect of Si on early osteoclast differentiation and, thereby, inhibition of bone resorption. Here, it is demonstrated that there is transmembrane passage of Si into bone cell precursors, and that Si regulates the expression of the gene encoding aquaporin9, which potentially mediates the passage. Furthermore, the results of the observational studies show that pregnant women excrete higher levels of Si in the urine than non-pregnant women and men. The Si excretion increases post-partum in women who are lactating for 4 months or longer, but are not related to changes in bone mineral density. This thesis supports that Si has beneficial effects on bone, and describes urinary Si excretion in sub-populations that have never been studied before.
Decontamination of implant surfaces
(2023-04-06) Ichioka, Yuki
Peri-implantitis is a pathological condition occurring in tissues around dental implants. It is caused by microorganisms and characterized by inflammation in the peri-implant connective tissue and progressive loss of supporting bone. The goal of treatment of peri-implantitis is to resolve inflammation and to arrest further loss of supporting bone. Removal of the bacterial biofilm from the implant surface is a prerequisite to achieve this goal. The aim of the present series of studies was to evaluate the efficacy in biofilm removal of different implant surface decontamination methods. In Studies I and II, different mechanical and chemical decontamination protocols on biofilm-coated titanium discs were evaluated. It was demonstrated that air-polishing and rotating titanium brush were the superior mechanical methods, while alkaline electrized water (AEW) and N-acetyl-L-cysteine were the most effective chemical agents. In Study III, different combinations of mechanical protocols and chemical agents were examined using commercially available implants covered with a multispecies biofilm. Decontamination protocols including an air-polishing device or a rotating titanium brush were superior in terms of biofilm removal and in reducing atomic% of Carbon on implant surfaces when compared to methods restricted to wiping with gauzes. The use of chemical agents as adjuncts to the mechanical cleaning protocols provided no relevant benefit over saline. Study IV evaluated the cleaning efficacy of air-polishing and a combination of air-polishing and AEW in surface decontamination of explanted peri-implantitis-affected implants. SEM analysis revealed that both treatment protocols were effective in biofilm removal. While differences between treatment protocols were small, implant thread geometry, implant surface characteristics and gender influenced results. In addition, EDS analysis showed that target zones of the implant (apical, middle, coronal) influenced the atomic% of Carbon and Calcium and that implant surface characteristics affected the atomic% of Titanium. The present series of in vitro studies demonstrated that both air-polishing and rotating titanium brush are effective tools in removing biofilm from implants. Clinical studies are needed to assess the efficacy of the implant surface decontamination protocols during surgical treatment of peri-implantitis.
Caries Prevention in Patients Undergoing Orthodontic Treatment
(2022-10-14) Enerbäck, Hanna
Background: Scientifically based guidelines to predict and prevent caries during orthodontic treatment with fixed orthodontic appliances are lacking. Aim: The overall aim of this thesis was to improve caries risk assessment before orthodontic treatment, as well as to evaluate caries risk and improve caries prevention during treatment. Patients and methods: Patients (n=270) undergoing treatment with fixed appliance at the Specialist Clinic of Orthodontics in Mölndal, Sweden, were included. Studies I, III and IV were performed with an RCT design, with the subjects being randomly assigned to one of the following groups: i. Fluoride mouth rinse (FMR) group, 0.2 % sodium fluoride (NaF) mouth rinse plus 1450 ppm F toothpaste; ii. High-fluoride toothpaste (HFT) group, 5000 ppm F; and iii. Control (CTR) group, 1450 ppm F toothpaste. In study I, the effect of orthodontic treatment and the different fluoride regimens on caries risk and caries risk factors were evaluated. Study II was performed with a prospective design that evaluated the CRA programmes and the caries indices abilities to predict the outcome of caries during treatment. In studies III and IV, the impacts of the different fluoride regimens on caries incidence (through radiographs and clinical photographs) during orthodontic treatment were evaluated. Results: The FMR and HFT groups showed an unchanged caries risk during treatment, while the caries risk increased significantly in the CTR group (p<0.0001). The DiFS index demonstrated the highest accuracy in predicting initial and manifest caries during treatment with fixed appliances, as compared to the multi-factorial CRA programmes. Radiographic analyses revealed no significant difference between the fluoride groups in terms of increased caries incidence during treatment. However, the numbers of patients with an increase of one or more white spot lesions (WSL) during orthodontic treatment were significantly higher in the CTR group than in the FMR group (p=0.0097) or HFT group (p=0.018) when the data for incisors, lateral incisors and canines were included. Conclusion: The DiFS index most-accurately predicts caries during orthodontic treatment. Furthermore, a mouth rinse or high-fluoride toothpaste can be recommended during orthodontic treatment to retain low caries risk and to reduce the numbers of WSLs in the aesthetic front.
Young adults and oral health - Oral health behaviors and an intervention for better oral health
(2022-08-22) Hagman, Jennie
Although the oral health among young adults in Sweden is generally good, there are groups where poor oral health remains a problem. The aim of this thesis is to increase our knowledge of oral health and oral health-related behaviors among young adults with caries disease, and to evaluate the ability of a brief form of Acceptance and Commitment Therapy (ACT) to promote oral health and oral health behaviors in this group of individuals at the Public Dental Service Clinics. The studies included are based on a randomized controlled trial carried out in a sample of 18-25-year-olds, with ≥ 2 new approximal dentin caries lesions since their last dental examination. In Study I, we analyzed baseline data to describe oral health, oral health-related quality of life (OHRQoL), oral health behaviors, and the association between different known risk factors for poor oral health and caries severity. The results demonstrate that, in general, the young adults suffered from poor oral health, negatively affected OHRQoL, and they engaged in different oral health risk behaviors. Levels of gingivitis, the frequency of sugary soda consumption, poor OHRQoL and less frequent dental attendance were found to be associated with the caries severity. Study II evaluated the direct effect of ACT on oral health behavior, and Study III evaluated the effect on the levels of gingivitis and plaque at the 9-week and 18-week follow-ups. Study II showed a promising direct effect of ACT on oral hygiene behaviors, in favor of ACT treatment. In Study III, reduced gingivitis and plaque levels were found both in the intervention and the control group. Although slightly lower levels of plaque and gingivitis were maintained in the intervention group at the 18-week follow-up, the improvement was not statistically significantly better than in the control group. The finding in Study I emphasizes the need to develop effective interventions to promote oral health in this subgroup of young adults. Study II and III contribute with important knowledge but also acknowledge the need for further development and evaluation of theory-based interventions in the dental field.
Neutrophil Serine Proteases in Health and Disease
(2022-05-17) Sanchez Klose, Felix P
Neutrophils are filled with many antimicrobial agents, including the neutrophil serine proteases (NSPs); a group of proteases including Elastase, Proteinase 3, and Cathepsin G. Synthesized as inactive proforms, the NSPs are activated through proteolytic processing by Cathepsin C (CTSC). The NSPs have been demonstrated to degrade microbes in vitro. Therefore, NSPs have been described as crucial for microbial killing and are also believed to be critical for NETosis, a neutrophil-specific type of cell death capable of ensnaring extracellular microbes. Periodontitis is a destructive inflammation of the tooth supporting tissues initiated by colonizing bacteria. Neutrophils are abundantly present in the gingival crevice and more are recruited during periodontitis. Certain defects in neutrophil functions, like the Papillon-Lefèvre Syndrome (PLS), are associated with severe forms of periodontitis. PLS is a rare autosomal recessive loss-of-function mutation in the CTSC gene. The subsequent absence of CTSC activity in PLS neutrophils, results in absence of NSP activity. Interestingly, patients with PLS do not typically display increased susceptibility to opportunistic infections. The cardinal symptom of PLS is instead a rapidly progressing periodontitis with prepubertal onset. By studying PLS neutrophils, this thesis shows that NSP activity is indeed important for certain but not all types of NETosis (paper I). The work also demonstrates that PLS neutrophils from two families with distinct CTSC mutations, are indeed devoid of CTSC as well as NSP activities (paper II). Despite this, PLS neutrophils appeared to function normally with the exception of NETosis. To explain how lack of NSP activity results in periodontitis, it was hypothesised that NSPs may regulate inflammation by the cleavage of cytokines. In vitro, it was shown that whereas normal neutrophils were capable of degrading certain cytokines, PLS neutrophils were unable to do so (paper III). Most notably, IL-17A, IL-23, CCL20, and RANKL, all of potential importance for driving periodontal pathology, were quite susceptible to NSP-mediated cleavage. Other cytokines, e.g., IL-17F and CCL2, were resistant to NSP mediated cleavage indicating that degradation was not indiscriminate. In conclusion, this thesis shows that NSP activity is important for certain types of NET formation, but otherwise dispensable for basic neutrophil function. It also demonstrates that NSP activity may be able to regulate inflammatory processes and could help to explain the aggressive periodontal pathology seen in patients with PLS.
Evidence-based dental hygenist practice in the non-surgical therapy of patients with periodontitis: outcomes of therapy and factors associated with the quality of care
(2022-04-05) Liss, Anna
The overall aim was to investigate clinical and patient-reported outcomes of non-surgical treatment approaches to periodontitis and factors associated with the quality of care provided by dental hygienists (DHs) in general practice. The goal of non-surgical therapy of periodontitis is to establish infection con-trol. In Sweden, DHs perform >90% of such non-surgical interventions, but little is known about the effectiveness of the therapy and factors associated with the quality of care. Study I was a questionnaire study including 291 DHs, with the focus on professional competencies and behavioral interventions in periodontal therapy, perceived work-related support and work satisfaction. Perceived competencies in the treatment of periodontitis patients were related to the practice of behav-ioral interventions as a part of the therapy. A supportive work environment was important for DHs work satisfaction. Studies II & III were based on a randomized clinical field study focusing on the effectiveness of two non-surgical treatment approaches to periodontitis; a guided approach to periodontal infection control (GPIC) versus conventional non-surgical therapy (CNST). The study involved 689 patients and 95 DHs. Study II included 494 patients with questionnaire and clinical data at baseline and 6 months. No substantial differ-ences were found between the treatment approaches regarding patient-reported experiences or outcomes of therapy. The patient’s experience of being involved in the therapy decisions was a significant predictor for positive patient-reported outcomes as well as clinical outcomes in terms of patients’ adherence to treatment regimens, i.e. self-performed infection control. Study III included 615 patients who had com-pleted the initial treatment phase. Both approaches resulted in significant clinical improvements, with no differences between treatment groups. Smoking and age affected the outcome in terms of pocket closure (PPD≤4 mm) at 6 months. The GPIC was significantly more time-effective than CNST. Study IV was a qualitative interview study including 18 DHs who had participated in the preceding clinical study. The findings emphasized the DHs’ ambivalence between theory and practice in the treatment of patients with periodontitis. DHs were aware of what to do to offer adequate care, but this did not coincide with how they usually worked. Established routines and the culture in the clinic, predetermined beliefs about patients’ lack of motivation and ability to cooperate, lack of time and reflection, financial demands on the care offered and lack of interest/support from co-working dentists were considered as barriers in the periodontal care. In conclusion, the results bring knowledge about the clinical effectiveness of non-surgical treatment approaches performed by DHs in a real-world setting. In addition, the findings provide knowledge about patients’ experiences and therapy benefits. The results also elucidate facilitators and barriers influencing the quality of care offered to patients with periodontitis and emphasize the need for improvement on both a professional and organizational level. The focus should be on the competencies of dental profes-sionals to provide therapy based on the best available knowledge and on creating an organizational envi-ronment that supports good quality of care.
Cobalt-Chromium alloys in fixed prosthodontics
(2022-03-03) KASSAPIDOU, MARIA
Gold and its alloys have been the dominant framework materials in metal-ceramic constructions when substantial loss of tooth substance or missing teeth needs to be replaced. However, base metal alloys, such as cobalt-chromium (Co-Cr), have been introduced due to increased gold price. Co-Cr alloys possess beneficial mechanical properties because the alloys can, even with small dimensions, resist high chewing forces and exhibit an acceptable bond to the surface porcelain layer. Yet, the biocompatibility of Co-Cr alloys has been questioned. The overall aim of the present thesis is to increase our knowledge about Co-Cr alloys that are used in fixed prosthodontics. Results from Study I, which was a survey directed to all dental laboratories in Sweden, demonstrated that more than thirty different Co-Cr alloys were reported to be used in fixed prosthodontics. Besides the various chemical composition among the reported alloys, they were also manufactured by four different techniques; cast, milled, laser melted and pre-sintered milled. Based on the results from Study I, five Co-Cr alloys manufactured by four techniques, together with commercially pure titanium (c.p. Ti) grade 4 and Ti6Al4V ELI, were further included in Studies II-IV. In vitro studies were conducted in order to evaluate ion release, cell viability and inflammatory response. The effect of material combinations was also investigated. The mechanical properties and material structure with regards to yield strength, elongation after fracture, hardness, elastic modulus, surface roughness and microstructure were evaluated. The effect of heat treatment was also investigated on the above-mentioned parameters. The total ion release from all materials was extremely low, yet highest for the cast Co-Cr alloys in acidic conditions. The combination of Co-Cr, Ti6Al4V ELI and c.p. Ti showed lower total ion release compared with the non-presence of c.p. Ti. All tested materials demonstrated non-cytotoxic effects, although the highest inflammatory response from cells exposed to the materials was observed for the cast and pre-sintered milled Co-Cr materials. Overall, the laser melted Co-Cr demonstrated the highest values in mechanical properties. Conclusion: In vitro biological aspects and mechanical properties are influenced by the choice of manufacturing technique, heat treatment and microstructure of the materials. In order to evaluate these findings, more clinical studies are needed.
On the use of radiography and radiation dose consideration in orthodontic treatment
(2021-11-25) Stervik, Christina
The aims of this thesis were to analyse the use of radiography and radiation risk associated with orthodontic treatment. Study I measured absorbed doses to radiosensitive organs in the head and neck in an anthropomorphic phantom head using thermo¬luminescent dosimeters (TLDs) from digital intra-oral and panoramic radiography. Effective doses were calculated. Study II retrospectively evaluated panoramic radiographs of children and adolescents to determine positioning errors and pathological findings. A web-based questionnaire in Study III queried orthodontists about their use of radiographic examinations. Study IV retrospectively analysed the radiographs used in orthodontic treatment at two specialist clinics. Results: The salivary glands and the oral mucosa received the highest absorbed doses in intra-oral full-mouth and panoramic radiography and effective doses were 15µSv and 1975µSv, respectively. Positioning errors were found in 96% of the panoramic radiographs, 24% of the errors may have influenced diagnostic accuracy. The number of pathologies and anomalies were 1,221 in 558 (43%) patients, mainly in tooth-bearing regions. Only 63 (5%) of the findings may have influenced treatment outcome. Questionnaire respondents stated that radiographic examinations were mainly used in treatment planning stage, the most common were panoramic radio¬graphs. Local radiographic guidelines were often applied while little need for national guidelines was expressed. Preliminary results confirmed the use of radiographs predominantly during treatment planning and estimated radiation risk was comparable to approximately a week of natural background radiation in Sweden. In summary, effective doses were higher than previously reported in panoramic radiographs. Positioning errors in panoramic radiographs were common. Pathologies or anomalies were mainly found in the dentoalveolar regions, indicating that the radiation field could be limited in panoramic radiography. Panoramic radiographs are frequently used in orthodontic treatment. Even though radiation risk at the individual level is low, the risk at the population level is not negligible.
Prevention and treatment of experimental peri-implantitis
(2021-11-22) Almohandes, Ahmed
Peri-implantitis is a plaque-associated pathological condition occurring in tissues around dental implants. It is characterized by inflammation in the peri-implant mucosa and progressive loss of supporting bone. The aims of the present series of studies were to (a) analyze the effect of plaque-formation on implant abut-ments with an antibacterial coating, (b) evaluate the effect of surgical treatment of experimental peri-implantitis using different decontamination methods, (c) evaluate the effect of the use of bone substitute materials on soft and hard tissue healing following reconstructive surgical therapy and (d) evaluate the accuracy of bone level assessments using either cone beam computed tomography, intra-oral periapical radiographs or histology. In Study I, plaque formed on implant abutments with an antimicrobial coating for 6 months. Data from radiological, microbiological and histological examinations were analyzed. In study II, III and IV, differ-ent surgical treatment protocols of experimental peri-implantitis were applied to implants with different surface characteristics. Radiographs were obtained to longitudinally evaluate disease progression and treatment outcome and block biopsies were obtained and prepared for histological analysis. In study IV, cone beam computed tomography was obtained following reconstructive treatment of experimental peri-implantitis. Implant abutments with an antibacterial coating failed to prevent biofilm formation and did not influence the inflammatory response in the adjacent peri-implant mucosa (Study I). Disease resolution of experi-mental peri-implantitis occurred after surgical therapy using different methods for implant surface decon-tamination (Study II and III). Healing following surgical treatment of experimental peri-implantitis was superior around implants with a smooth surface than at implants with rougher surfaces. (Study II and III). Defect fill and re-osseointegration following reconstructive peri-implantitis surgery occurred at 23 out of 24 implants with a smooth surface and at 13 out of 24 implants with a moderately rough surface. The additional effect of using bone substitute materials during surgery was small (Study III). Significant corre-lations were observed between assessments of marginal bone levels using cone beam computed tomogra-phy, periapical radiographs or histology. Measurements in periapical radiographs consistently resulted in an overestimation of the bone level of about 0.3 mm (Study IV).
On factors associated with development of oral squamous cell carcinoma
(2021-11-18) Jäwert, Fredrik
Oral squamous cell carcinoma (OSCC) has severe impacts on the affected patient’s morbidity and mortality. Early detection of OSCC is of outmost importance to reduce morbidity and to improve patient survival. A significant fraction of all OSCCs is preceded by oral leukoplakia (OL). OL is clinically detectable as a more-or-less white patch in the oral mucosa. However, there is still limited knowledge regarding which patients with OL that will develop OSCC and how to best monitor and manage these patients. The overall aims of this thesis were to investigate clinical, histopathologic, genomic and epigenomic factors associated with OL progression to OSCC and to evaluate a follow-up program for these patients. To assess if clinical follow-ups of OL patients result in early detection and high survival rate if cancer develops, a retrospective medical record and register-based study of 739 patients with OSCC was performed (Paper I). The results indicate that follow-ups of OL patients at an Oral and Maxillofacial Surgery - or Oral Medicine clinic results in early detection and improved survival, if the lesion transforms into cancer. Clinicopathologic features of OL that are associated with progression to OSCC were investigated in a retrospective medical record – and register-based study that included 234 patients (Paper II). The results showed that non- homogeneous OL progressed to OSCC to a significantly greater extent than homogeneous OLs. In addition, dysplastic OLs and OLs located at the tongue were associated with increased risk of progression to OSCC. Copy number alterations (CNAs) of known cancer driver genes were studied using fluorescence in situ hybridization (FISH) in OLs and OSCC (Paper III). CNAs in OLs that progressed to OSCC and the corresponding OSCC (N = 14) were analyzed. Comparisons were made with OLs that did not transform into OSCC (N = 14). The results showed that CNAs not only occur in OSCC but also in OLs. Some CNAs were detected somewhat more frequently in OLs that transformed into cancer. This indicates possible roles for CNAs of some genes in the development and progression of subsets of OLs. Epigenetic gene regulation mechanisms, such as DNA methylation, are involved in carcinogenesis. The epigenetic factors 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC) and ten-eleven- translocation-2 (TET2) were analyzed in OSCC (N = 15) and compared to healthy oral epithelium (N = 12) (Paper IV). Using immunohistochemistry, significantly lower levels of 5hmC and TET2 were detected in OSCCs compared to healthy oral epithelium. In summary, this thesis highlights the importance of monitoring patients with OL, since it results in early detection and high survival rates, if cancer develops. In addition, we identify clinical, histopathologic, genomic and epigenomic factors that can, or have potential to, be used to identify patients with OL who are at high risk for cancer development. This knowledge may be used to identify patients who should be prioritized for regularly scheduled clinical examinations.
On dental implant failure and patient-related factors
(2021-10-08) Olsson Malm, Malin
Dental implants function as anchorage for dental prostheses. In a small number of cases, osseointegration fails to establish or be maintained around the implants, but the reasons for these failures are not yet fully understood. This thesis investigated a cohort of patients rehabilitated with dental implants, with respect to incidence of implant failure and potential risk factors for early implant failure, and explored the gene expression of selected biological markers in peri-implant bone sites with severe bone loss. Patient data were retrospectively compiled from one specialist referral clinic. Data were analyzed on the patient level covering 27-31 years of implant treatment (Studies I, II and III). Study I described the inci-dence of implant failure for the total group of rehabilitated patients. In Studies II and III, multivariable logistic regression analyses of several anamnestic and clinical variables were performed to find potential risk factors for early implant failure in edentulous jaws. In Study IV, an experimental pilot study, gene expression analysis was performed in biopsies from bone and peri-implant crevicular fluid (PICF) sur-rounding implants with severe bone loss compared to un-affected bone, using qPCR technique. In Study I, a total number of 39,077 implants were inserted in 8528 patients. Of these, 9% of the rehabili-tated jaws were registered with implant failure and 69% of these had the first implant failure during the first year of function. Implant failures were more frequent in the maxilla as compared to the mandible. The change from implants with turned, minimally rough surfaces to implants with different moderately rough surfaces coincided with a decrease of early implant failure. In Study II, the incidence of early implant failure in edentulous jaws was higher in the maxilla compared to the mandible, with turned as well as moderately rough surfaces. The highest risk of early implant failure was related to the maxilla together with implants with a turned surface. Older age at implant surgery was associated with lower risk of early implant failure. In Study III, nine risk factors for early implant failure were identified: systemic disease, allergies, food allergies, smoking, analgetic medication, implants in the opposing jaw, low primary stabil-ity, reduced bone volume, and healing complications. In Study IV, an upregulation of pro-inflammatory cytokines and bone degradation markers were found in bone biopsies from bone loss sites compared to biopsies from unaffected bone in the same patients. The results were partly corresponded by the PICF samples. The results need to be interpreted with caution due to the small sample size and the pilot study design. In conclusion, implant failures occurred in 9% of the jaws. Several risk factors for early implant failure were identified, which need to be considered in future implant rehabilitations. There was a difference in the gene expression around implants with severe bone loss compared to samples from un-affected bone. Further studies are needed to describe the processes associated with implants that display ongoing bone loss.

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