Head and neck cancer comprises a heterogeneous group of tumours affecting anatomical sites of the upper aerodigestive tract. Treatment often involves surgery and either radiotherapy or chemoradiotherapy. These treatments are associated with substantial morbidity and may have long-lasting adverse effects on oral health. Oral complications can negatively affect health-related quality of life, nutritional status, and social and work-related functioning. The aim is to evaluate an oral health care programme designed to prevent or mitigate late oral sequalae, and to assess its impact on health-related quality of life, oral health, work ability, nutritional status, healthcare-related economic costs, and psychological well-being. This is a study protocol for a Swedish multicentre, two-armed, superiority randomised controlled trial that has been ethically approved by the Swedish Ethical Review Authority. Patient inclusion commenced in September 2025, with an intended sample of 300 participants. Adult patients (≥ 18 years) planned for curative-intent treatment for head and neck cancer (oral cavity, oropharynx, larynx stage III and IV, hypopharynx, nasopharynx, salivary gland, or unknown primary) are randomised (1:1) to either an oral health care programme (intervention) or standard of care. Exclusion criteria: severe alcoholism, cognitive impairment, or inability to understand the Swedish language. Participants are followed before the start of cancer treatment and at 4 follow-ups: 6 months after completion of treatment, and 1, 2, and 3 years after the 6-month follow-up. The primary outcome measure is health-related quality of life. Secondary outcomes include quantitative oral health indicators, return to work, nutritional status, healthcare-related economic costs, and patient-reported outcome measures focusing on self-reported oral health and psychological well-being (depression, anxiety and stress), and self-efficacy. Oral health follow-up for head and neck cancer survivors often lacks consistency and uniformity. To date, few oral health care interventions for head and neck cancer survivors have been evaluated within the framework of a randomised controlled trial. The findings have the potential to inform clinical practice and contribute to the development of more integrated, evidence-based oral healthcare strategies within routine follow-up for head and neck cancer survivors, with the overarching goal of improving their oral health and long-term quality of life. ClinicalTrials.gov NCT07173270, date 15/9/2025.

ABSTRACT Introduction Dental caries is a disease that affects billions of people, and involves high and low genetic susceptibility phenotypes and different causal subtypes. The randomized clinical trial Precaries-RCT will evaluate caries prevention in adolescents, customized according to genetic cause and risk. Here we describe the Precaries-RCT and two nested Precaries studies for cost-efficient oral healthcare and personalized dentistry. Methods and analysis Here we present a basic and adaptive protocol for the Precaries-RCT multicentre caries intervention study, customized according to genetic cause and risk. It includes prescreening for high versus low genetic caries susceptibility, through self-performed sampling by mail of up to 2000 adolescents aimed for orthodontic treatment at community clinics, of which 520 are enrolled in the RCT. The participants are allocated into two groups – a high and a low genetic caries susceptibility group – that each is assigned to intensive or standard prevention. The primary outcome is % reduction in caries increment, relative to prevention and genotype, with caries outcomes measured using tactile and visual methods, bitewing radiographs, clinical photos, and quantitative laser fluorescence. The adaptive design allows for determination of incidence and progression rates and for inclusion of additional human and microbiota biomarkers and study subjects. Biological samples (e.g. swab DNA, whole and parotid saliva, and microbiota) and questionnaire data are collected. Here we also outline the nested Precaries-adolescent sample for mining of predictor and therapeutic target genes and Precaries-birth cohort samples for implementation of our findings in childhood. Ethics and dissemination Ethical approval was obtained from the Swedish national board research ethics committee (Dnr 2020-02533). Informed consent will be obtained from each participant. The findings will be disseminated to the public through conference presentations and publication in peer-reviewed scientific journals. Trial registration number www.clinicaltrials.gov , NCT05600517 STRENGTHS AND LIMITATIONS OF THIS STUDY Caries classification and prevention customized according to genetic cause and risk, and caries outcome measurements by tactile and visual methods, bitewing radiographs, clinical photos, and quantitative laser fluorescence. Multicentre study with orthodontic patients and conditions representative of the Public Dental Service clinics in Sweden, facilitating implementation, though in a part of the population. Prospective study design in an orthodontic model with shortened study time and caries development on available smooth tooth surfaces. Frequent follow-up enables study termination of individuals with high caries progression, which may allow further shortening of study times, but with reduced individual data for the entire study period. Consensus-based intensified and self-care prevention in multiple repeated blocks, ensuring a high therapeutic dose; and basic and adaptive design, allowing flexible study time, caries incidence and progression outcomes, and extensive genetic profiling for online multimodal machine learning. Synergizes with the Precaries-adolescence sample for mining of caries predictors and therapeutics, and Precaries-birth cohort for implementation in primary dentition/childhood.

Summary: Background: Lifestyle- and sucrose-dependent polymicrobial ecological shifts are a primary cause of caries in populations with high caries prevalence. In populations with low prevalence, PRH1, PRH2 susceptibility and resistance phenotypes may interact with the Streptococcus mutans adhesin cariogenicity phenotype to affect caries progression, but studies are lacking on how these factors affect the microbial profile of caries. Methods: We analysed how the residency and infection profiles of S. mutans adhesin (SpaP A/B/C and Cnm/Cbm) phenotypes and commensal streptococci and lactobacilli influenced caries progression in a prospective case–referent sample of 452 Swedish adolescents with high (P4a), moderate (P6), and low (P1) caries PRH1, PRH2 phenotypes. Isolates of S. mutans from participants were analysed for adhesin expression and glycosylation and in vitro and in situ mechanisms related to caries activity. Findings: Among adolescents with the resistant (P1) phenotype, infection with S. mutans high-virulence phenotypes was required for caries progression. In contrast, with highly (P4a) or moderately (P6) susceptible phenotypes, caries developed from a broader polymicrobial flora that included moderately cariogenic oral commensal streptococci and lactobacilli and S. mutans phenotypes. High virulence involved unstable residency and fluctuating SpaP ABC, B-1, or Cnm expression/glycosylation phenotypes, whereas low/moderate virulence involved SpaP A phenotypes with stable residency. Adhesin phenotypes did not display changes in individual host residency but were paired within individuals and geographic regions. Interpretation: These results suggest that receptor PRH1, PRH2 susceptibility and resistance and S. mutans adhesin virulence phenotypes specify different microbial profiles in caries. Funding: Swedish Research Council and funding bodies listed in the acknowledgement section.

Dental caries, the most common chronic infectious disease, involve Streptococcus mutans SpaP A/B/C and Cnm/Cbm adhesin types of different virulence. We have explored their stability and dynamics over 5 years, their geographic distribution, as well as the potentially increased cariogenicity of specific SpaP B subtypes. We performed qPCR and TaqMan typing using whole saliva and isolates from 452 Swedish adolescents followed from 12 to 17 years of age. Approximately 50% of the children were infected at baseline with a single dominant (44%) or mixed (6%) SpaP A, B, or C type, some of which were also Cnm (6%) or Cbm (1%) positive. Stability (+, +) was high for S. mutans infection (85%) and dominant SpaP A or C (80% and 67%) and Cnm or Cbm (85% and 100%) types, but low for SpaP B (51%) and mixed SpaP A/B/C types (26%). Only five children switched from one SpaP type to another, and none between Cnm and Cbm types. Mixed SpaP A/B/C types were typically lost or changed into dominant types. Moreover, children infected with Cnm (n=26) types were more frequent in the northern (Skelleftea) region (p = 0.0041), and those with Cbm types (n=7) in the southern (Umea) region. Children infected with SpaP B-2 subtypes had a doubled caries experience (p = 0.009) and 5-year caries increment (p = 0.02) compared to those infected with SpaP A. In conclusion, the stable dominant but instable mixed adhesin types and geographic differentiation of Cnm and Cbm types suggest adaptation of low and high cariogenicity types to specific individuals.

OBJECTIVES:The aim was to study self-image and the level of psychological symptoms in patients with symptoms attributed to their dental restorative materials.MATERIALS AND METHODS:A questionnaire containing questions regarding dental and medical history was answered by 257 participants, one group with local oral symptoms only (LSO), and one group with multi-symptoms (M-S). A reference group was randomly selected from a research database at the Department of Psychology, Umeå University, Sweden. The self-image was assessed using the Structural Analysis of Social Behavior (SASB). Psychological symptoms such as somatization, depression, and anxiety were assessed using the Symptom Check List 90 (SCL-90) and the Global Severity Index (GSI) was used to determine the level of psychological symptoms.RESULTS:SASB showed that the M-S group and the LSO-group scored significantly higher on the "spontaneous" and "positive self-image" than the reference group. In the SCL-90, the M-S group scored significantly higher than the LSO-group and the references on the somatization subscales. On depression, anxiety, and the GSI scale, the M-S group scored significantly higher than the reference group.CONCLUSIONS:The two subgroups scored significantly higher on the SASB Spontaneous and Positive clusters which indicates that these patients have an excessively positive self-image, are very spontaneous and have an overconfidence in themselves compared to the reference group. In the M-S group there was a clear tendency to somatization, depression, and anxiety and they were more psychologically stressed than the reference group.CLINICAL RELEVANCE:Among the patients with illness attributed to their dental materials, the M-S-patients had a significantly higher level of general psychological distress and somatization than the control group which may lead to mental stress.

Dental caries, which affects billions of people, is a chronic infectious disease that involves Streptococcus mutans, which is nevertheless a poor predictor of individual caries development. We therefore investigated if adhesin types of S.mutans with sucrose-independent adhesion to host DMBT1 (i.e. SpaP A, B or C) and collagen (i.e. Cnm, Cbm) match and predict individual differences in caries development. The adhesin types were measured in whole saliva by qPCR in 452 12-year-old Swedish children and related to caries at baseline and prospectively at a 5-year follow-up. Strains isolated from the children were explored for genetic and phenotypic properties. The presence of SpaP B and Cnm subtypes coincided with increased 5-year caries increment, and their binding to DMBT1 and saliva correlated with individual caries scores. The SpaP B subtypes are enriched in amino acid substitutions that coincided with caries and binding and specify biotypes of S. mutans with increased acid tolerance. The findings reveal adhesin subtypes of S. mutans that match and predict individual differences in caries development and provide a rationale for individualized oral care.

Dental caries is a chronic infectious disease that affects billions of people with large individual differences in activity. We investigated whether PRH1 and PRH2 polymorphisms in saliva acidic proline-rich protein (PRP) receptors for indigenous bacteria match and predict individual differences in the development of caries. PRH1 and PRH2 variation and adhesion of indigenous and cariogenic (Streptococcus mutans) model bacteria were measured in 452 12-year-old Swedish children along with traditional risk factors and related to caries at baseline and after 5-years. The children grouped into low-to-moderate and high susceptibility phenotypes for caries based on allelic PRH1, PRH2 variation. The low-to-moderate susceptibility children (P1 and P4a-) experienced caries from eating sugar or bad oral hygiene or infection by S. mutans. The high susceptibility P4a (Db, PIF, PRP12) children had more caries despite receiving extra prevention and irrespective of eating sugar or bad oral hygiene or S. mutans-infection. They instead developed 3.9-fold more caries than P1 children from plaque accumulation in general when treated with orthodontic multibrackets; and had basic PRP polymorphisms and low DMBT1-mediated S. mutans adhesion as additional susceptibility traits. The present findings thus suggest genetic autoimmune-like (P4a) and traditional life style (P1) caries, providing a rationale for individualized oral care.

Anxiety for adverse health effects attributed to dental restorative materials especially dentalamalgam, have been discussed extensively off and on the last 30 years. The possible health effect ofam ...

The aim of this study was to explore the experiences of illness and the encounters with health care professionals among women who attributed their symptoms and illness to either dental restorative materials and/or electromagnetic fields, despite the fact that research on health effects from dental fillings or electricity has failed to substantiate the reported symptoms. Thirteen women (aged 37–63 years) were invited to the study and a qualitative approach was chosen as the study design, and data were collected using semi-structured interviews. The analysis was conducted with a constant comparative method, according to Grounded Theory. The analysis of the results can be described with the core category, “Struggle to obtain redress,” the two categories, “Stricken with illness” and “A blot in the protocol,” and five subcategories. The core category represents the women's fight for approval and arose in the conflict between their experience of developing a severe illness and the doctors’ or dentists’ rejection of the symptoms as a disease, which made the women feel like malingerers. The informants experienced better support and confirmation from alternative medicine practitioners. However, sick-leave certificates from alternative medicine practitioners were not approved and this led to a continuous cycle of visits in the health care system. To avoid conflicting encounters, it is important for caregivers to listen to the patient's explanatory models and experience of illness, even if a medical answer cannot be given.

The aim of the study was to determine the prognosis and to evaluate the regression of lichenoid contact reactions (LCR) and oral lichen planus (OLP) after replacement of dental restorative materials suspected as causing the lesions. Forty-four referred patients with oral lesions participated in a follow-up study that was initiated an average of 6years after the first examination at the Department of Odontology, i.e. the baseline examination. The patients underwent odontological clinical examination and answered a questionnaire with questions regarding dental health, medical and psychological health, and treatments undertaken from baseline to follow-up. After exchange of dental materials, regression of oral lesions was significantly higher among patients with LCR than with OLP. As no cases with OLP regressed after an exchange of materials, a proper diagnosis has to be made to avoid unnecessary exchanges of intact restorations on patients with OLP.

The aim of this follow-up study was to assess the long-term development of symptoms and their social consequences among patients referred for diagnosis and treatment of symptoms believed to be related to dental-restorative materials. A questionnaire was sent to 614 such patients containing questions on civil status, present health, changes between baseline and follow-up, current employment situation, and consequences of the problems. The results showed that patients with complex symptoms at baseline had a worse prognosis (i.e. more symptoms remaining) at follow-up than patients with local symptoms only. Replacement of dental materials seemed to have the largest impact on the alleviation of the symptoms reported. Those with remaining complex symptoms had more often stopped working or had decreased their work hours because of their symptoms. Only one-sixth of the patients were symptom-free at the follow-up. Our results indicate a relationship between patients with complex symptoms and social consequences in daily life. Therefore, social factors must be taken into consideration when examining the patients. Dental, medical, and social factors have to be considered simultaneously when examining a patient with symptoms that they relate to dental materials, in order to recommend appropriate care-management programs for this group of patients.

The aim of the present study was to investigate the psychobiological personality dimensions in two subgroups of patients with environmental illness (EI). Fifty-nine patients, 34 women and 25 men (aged 32–69 years), were referred for symptoms allegedly caused by abnormal sensitivity to either dental fillings (DF; n=26) or electromagnetic fields (EMF; n=33). For the evaluation of personality, the Swedish 238-item version of the Temperament and Character Inventory (TCI) was used. Compared with a control group, the EMF group scored higher on the temperament dimension Persistence. The DF group scored higher on the TCI subscales Harm Avoidance (fatigability and asthenia) and Self-Directedness (self-acceptance). Women scored higher than men did on the Novelty Seeking and Reward Dependence (RD) dimensions in the DF group and on RD in the control group, indicating an inherited gender difference. No differences were found between men and women in the EMF group. Our results indicate that the high level of persistence found in the EMF group and the high level of fatigability and asthenia in combination with high self-acceptance found in the DF group represent vulnerable personalities. No significant differences were found between the two patient groups, indicating that these groups are quite similar regarding personality. This vulnerability can be expressed as various mental and somatic symptoms, which can be interpreted as EI symptoms by the affected individual.

OBJECTIVESIn Sweden, many patients with symptoms allegedly caused by their dental materials have exchanged their restorations, but the effects of the exchange have been insufficiently investigated. Therefore, the aim of the study was to describe the change in health over time for these patients and the hypothesis was that the patients could be divided based on their symptoms and that the ability to recover differs between these groups. Furthermore, we also examined if other factors such as replacement of dental restorative materials and follow-up time had any impact on the perceived health status.METHODSA questionnaire was sent to 614 patients who had been referred to the School of Dentistry, Umeå, Sweden, with symptoms allegedly caused by dental restorative materials. The response rate was 55%.RESULTSThe risk of having any further complaints was higher for patients with complex symptoms (P = 0.03) and these patients had exchanged their restorations to a significantly larger extent than the others (P = 0.03). The remaining complaints was more frequent among men (P = 0.02). Exchange of dental restorative materials had no significant impact on the ability to recover completely. However, the patients who had exchanged their restorations completely perceived a significantly larger alleviation of their symptoms than the others (P < 0.01), although the frequency of most of the symptoms had increased.CONCLUSIONSPatients with complex symptoms had a more unfavorable long-term prognosis concerning persistent complaints than those with localized symptoms only. Furthermore, the results indicate that the patients might experience health improvements after removal of their dental restorative materials. The reason for this improvement, however, is unclear. Further analyses regarding other possible explanations than the 'odontological/medical' are needed.