Some metabolic disorder treatments require patients to follow a specific diet or to consume supplements that, over time, can lead to oral microbiome alterations. Well-known disorders requiring such treatment are phenylketonuria (PKU), an inborn error of amino acid metabolism, and type 1 diabetes (T1D), a metabolic disorder that requires a specific diet regimen. Therefore, the aim of this study was to investigate the oral health and microbiome characteristics that might contribute to caries activity and periodontal disease risk in PKU and T1D patients. In this cross-sectional study, 45 PKU patients, 24 T1D patients, and 61 healthy individuals between the ages of 12 and 53 years were examined. Their anamnestic data and dental status were assessed by one dentist. Microbial communities were detected from saliva-isolated DNA using 16S rRNA gene V3–V4 sequencing on Illumina MiSeq sequencing platform. Results revealed that the PKU patient group displayed the highest number of extracted teeth (on average 1.34), carious teeth (on average 4.95), and carious activity (44.44% of individuals) compared to the T1D and CTRL groups. The lowest numbers of filled teeth (on average 5.33) and extracted teeth (on average 0.63) per individual were observed in T1D patients. Gingivitis appeared more often in the T1D group; however, possible risk of periodontal disease was seen in both the T1D and PKU patient groups. The highest number of differentially abundant genera was detected in the PKU group (n = 20), with enrichment of Actinomyces (p_adj = 4.17 × 10⁻²²), Capnocytophaga (p_adj = 8.53 × 10⁻⁸), and Porphyromonas (p_adj = 1.18 × 10⁻⁵) compared to the CTRL group. In conclusion, the dental and periodontal health of PKU patients was found to be significantly inferior compared to T1D patients and healthy controls. T1D patients showed early signs of periodontal disease. Several genera that correlate with periodontal disease development were found in both groups, thus suggesting that T1D and PKU patients should seek early and regular dental advice and be educated about proper oral hygiene practices.

Phenylketonuria (PKU) is an autosomal recessive inherited disorder of phenylalanine metabolism resulting from a deficiency of phenylalanine hydroxylase. The aim of this study was to evaluate the dental status and periodontal health of PKU patients in Latvia. Forty-five PKU patients and age/sex-matched controls were recruited for this cross-sectional study. Their anamnestic data, periodontal health and dental status were assessed by one experienced dentist. Dental and periodontal clinical evaluation revealed that the median number of filled teeth was significantly smaller among PKU patients compared to the control group (p=0.021). PKU patients had a significantly larger median number of carious teeth than their healthy counterparts (p<0.001). Significant differences between the PKU and control groups were observed for several oral hygiene indices (p<0.001): Silness-Löe plaque index, OR=29.3 (95% CI: 3.7–232.4); CPITN index, OR=35.2 (95% CI: 4.5–278.3); Greene-Vermillion index, OR=10.2 (95% CI: 2.8–38.0); calculus removal necessity, OR=12.3 (95% CI: 3.3–45.4). Dental status and periodontal health of PKU patients was found to be significantly inferior compared to healthy controls. This is likely due to the regular consumption of PKU formula and the difficulties which mentally and/or physically disabled PKU patients experience with their oral hygiene. To prevent tooth decay and periodontal disease, PKU patients should visit a professional oral hygienist every three to six months. Furthermore, they should adopt the habit of rinsing their mouth with water immediately after consuming PKU formula to counteract the acidity in their oral cavity.

Objectives: Periodontitis is a multifactorial disease that affects approximately 11% of the global population. The objective of this study was to examine whether, among individuals with phenylketonuria and type 1 diabetes mellitus, those with the IL1B rs1143634 and/or DEFB1 rs11362 genetic variants exhibit a higher periodontitis risk compared to healthy controls. Materials and Methods: In all, 43 phenylketonuria patients (aged 12–53), 28 type 1 diabetes mellitus patients (aged 11–40), and 63 healthy controls (aged 12–53) were included. The evaluation of periodontitis risk was conducted using the Silness–Löe plaque index, the Greene–Vermillion index, and an assessment for the necessity of calculus removal. Genetic variants rs1143634 and rs11362 were genotyped from salivary samples using restriction length polymorphism analysis. Results: The DEFB1 rs11362 variant was associated with higher Silness–Löe and Greene–Vermillion index scores in phenylketonuria patients (p = 0.011 and p = 0.043, respectively). The IL1B rs1143634 variant was associated with lower calculus removal necessity in type 1 diabetes mellitus patients (p = 0.030). Clinical examination showed the worst oral hygiene index scores for PKU patients. PKU patients also reported the least consistent tooth brushing and flossing habits. Conclusions: Genetic associations between DEFB1 rs11362 and IL1B rs1143634 variants and oral hygiene indices were observed in the PKU and T1DM groups, suggesting that genetic factors may contribute to periodontal health differences in these populations. Further research with a larger sample size is needed to confirm these findings and develop targeted oral health interventions.

Background: Phenylketonuria (PKU) is an autosomal recessive inherited disorder of phenylalanine (Phe) metabolism that results from a deficiency of phenylalanine hydroxylase (PAH). Patients with PKU rely on amino acid mixtures and low-protein diets, which often exhibit an acidic nature and pose various challenges to oral health. The objective of the study was to evaluate oral care habits of PKU patients in Latvia and the impact of the recommendations developed on improving oral care. Materials and methods: In this study, during a one-month interval before and after the implementation of oral hygiene recommendations, questionnaires were distributed to all patients with PKU diagnosed in Latvia, with a response rate of 78 % (79 of 101). Results: The group older and 18 years of age showed a poorer understanding of oral care even after receiving recommendations, 82 % brushing their teeth twice a day (92 % in the group <18 years of age), continuing 57 % rinsing their mouth after using amino acid formula (75 % in the younger group). Significant improvements were observed only in the respondent group younger than 18 years of age - including increases in toothbrushing twice a day by 25 % (p = 0.001), dental flossing by 23 % (p = 0.001), mouth rinsing after amino acid-based formula by 13 % (p = 0.020). Conclusion: This study concludes that PKU patients older and 18 years of age have a poor understanding of maintaining oral hygiene and the use of the necessary supplements to improve it. Activities are needed in the future that would regularly remind and motivate PKU patients to take care of their oral health.

Background: Phenylketonuria (PKU) is an autosomal recessive inherited disorder of phenylalanine metabolism caused by a deficiency of the enzyme phenylalanine hydroxylase. Individuals with PKU must adhere to a lifelong low-protein diet and consume a specialised amino acid mixture daily. However, these amino acid supplements are often acidic, creating an unfavourable oral environment. The resulting low pH promotes plaque accumulation, which can lead to gingivitis and periodontitis, while also increasing the risk of dental caries due to the persistently acidic conditions in the mouth. Type 1 diabetes (T1D) is a metabolic disorder caused by defective insulin secretion and/or action and diet regimen is often suggested. In T1D chronic hyperglycaemia and impaired immune response increase the risk of periodontal disease, while altered salivary composition contributes to a higher susceptibility to dental caries and oral infections. Advancements in insulin therapy have simplified the disease management, allowing many patients with T1D to maintain a diet that is comparable to that of healthy individuals. The aim of this study was to evaluate oral health in patients with PKU and T1D compared to individuals in a control group from the Latvian population, and to analyse factors influencing it, such as oral hygiene habits, the oral microbiome, and genetic predisposition, as well as to develop specially tailored oral hygiene recommendations for patients with PKU. Material and methods: Our study included three groups – individuals with PKU, T1D and a control group without reported chronic diseases and dietary restrictions, all at least 12 years old. Oral health assessment was performed for all participants, followed by collection of saliva for microbial community analysis using 16S rRNA gene V3-V4 region sequencing and for genotyping of genetic variants in the IL1, DEFB1, TAS1R2, TAS2R38, CD36 genes. In this study, two questionnaires on oral hygiene habits and knowledge were prepared and administered by trained medical personnel, with a one-month interval between pre- and post-implementation of oral hygiene recommendations. These recommendations were based on previous oral health examinations and a literature review. The questionnaires were completed by all diagnosed patients with PKU in Latvia who were not lost to follow-up and who were older than two years. Results: Oral examination data was obtained from 45 patients with PKU (four were excluded due to severe intellectual disability), 31 T1D patients, and 70 control subjects. Clinical evaluation revealed that patients with PKU had the poorest oral hygiene index scores, with statistically significant differences in all variables compared to the T1D and control groups, except for the number of filled teeth. Patients with PKU also reported the lowest consistency in tooth brushing and flossing habits. Based on the questionnaires among patients with PKU under 18 years of age, 27 % cleaned their teeth once a day, while 6 % did not engage in regular tooth brushing at all. Among those aged 18 years and older, 26 % reported brushing only once a day. Additionally, a mere 39 % of patients with PKU aged ≥ 18 years and 17 % aged < 18 years incorporated flossing in their oral hygiene routine. In total, 45 % of patients with PKU aged ≥ 18 years and 44 % aged < 18 years visited a dentist once a year, but 40 % aged ≥ 18 years and 39 % aged < 18 years reported visiting a dentist less frequently than once per year. After reading the recommendations, a remarkable improvement in daily oral hygiene was observed among patients with PKU under 18 years of age: 25 % improved their toothbrushing habits and 23 % began flossing. Oral microbiome analysis revealed that the lowest number of shared genera was between the PKU and T1D groups. The highest number of differentially abundant genera was detected in the PKU group (n = 20), with significant enrichment of Actinomyces (padj = 4.17×10-22), Capnocytophaga (padj = 8.53×10-8) and Porphyromonas (padj = 1.18×10-5) compared to the control group. In contrast, the genus Leptotrichia (padj = 5.79×10-7) was enriched in T1D group, whereas the abundance of genera Fusobacterium (padj = 2.05×10-4) and Alloprevotella (padj = 7.24×10-4) was decreased compared to the control group. Analysis of genetic variant associations with oral health characteristics revealed that the DEFB1 rs11362 variant was associated with higher Silness-Löe plaque and Greene-Vermillion index scores in patients with PKU (p = 0.011 and p = 0.043, respectively). The IL1B rs1143634 variant was associated with a lower necessity for calculus removal in T1D patients (p = 0.030). Conclusions: PKU and T1D patients have a higher prevalence of carious teeth, and an increased risk of periodontal disease compared to the control group. Differences in the oral microbiome among PKU, T1D patients and controls may contribute to variations in oral health. In addition to metabolic disease and diet, genetic predisposition may also influence oral health outcomes in the PKU, T1D and control groups. Results of the survey on oral hygiene habits before and after receiving targeted recommendations suggest that a tailored approach may be needed to improve oral hygiene practices, particularly among adult patients with PKU. The Doctoral Thesis was developed at Rīga Stradiņš University, Latvia. Defence of the Doctoral Thesis will take place at the public session of the Promotion Council of Clinical Medicine on 17 December 2025 at 16.00 D. Kalvelis Great Hall, Institute of Stomatology, 20 Dzirciema Street and remotely via online platform Zoom. 3.2. Clinical Medicine; Sub-Sector – Dentistry. Keywords: 16S rRNA sequencing; caries; genetic predisposition; microbiome; oral health; oral hygiene indices; periodontitis; phenylketonuria; recommendations of daily oral hygiene procedures; single nucleotide variants; type...

Ievads: Fenilketonūrija (FKU) ir autosomāli recesīvi pārmantots fenilalanīna metabolisma traucējums, ko izraisa fenilalanīna hidroksilāzes deficīts. Pacientiem tiek piemērota zema olbaltumvielu diēta mūža garumā. 1. tipa cukura diabēts (1.TCD) ir vielmaiņas saslimšana, ko izraisa traucēta insulīna sekrēcija un/vai darbība. Attīstoties insulīna terapijai, diabēta ārstēšana ir kļuvusi vienkāršāka, ļaujot pacientiem ievērot diētu, kas ir līdzīga veselam cilvēkam. Šī pētījuma mērķis bija novērtēt mutes veselību FKU un 1.TCD pacientiem, salīdzinot ar kontroles grupu Latvijā, kā arī analizēt tās ietekmējošos faktorus – mutes dobuma higiēnas paradumus, mutes mikrobiomu un ģenētisko predispozīciju. Materiāli un metodes: Pētījumā tika iekļautas trīs grupas – FKU, 1.TCD un kontroles grupa bez hroniskām slimībām un diētas ierobežojumiem, vecumā virs 12 gadiem. Tika novērtēta mutes veselība, ievāktas siekalas šādām analīzēm: mutes mikrobioma profilēšanai, izmantojot 16S rRNS V3-V4 gēna sekvencēšanu, kā arī ģenētisko variantu genotipēšanai IL1, DEFB1, TAS1R2, TAS2R38 un CD36 gēnos. Katrai no analīzēm grupu lielumi nedaudz atšķīrās. Pētījumā ar viena mēneša intervālu pirms un pēc mutes higiēnas ieteikumu ieviešanas, balstoties uz iepriekšējo mutes veselības pārbaudi un literatūras apskatu, tika sagatavotas un medicīniskā personāla aizpildīšanai nodrošinātas divas anketas par mutes higiēnas paradumiem un zināšanām visiem Latvijā diagnosticētajiem FKU pacientiem vecumā virs diviem gadiem, kuri ir turpinājuši novēroties. Rezultāti: Mutes veselības pārbaudi bija iespējams veikt 45 FKU pacientiem (vidējais vecums 24,10 ± 9,04 gadi), no kuriem četri nevarēja piedalīties smagas intelektuālās attīstības traucējumu dēļ, kā arī 31 1.TCD pacientam un 70 kontroles grupas indivīdiem. Visi dati, izņemot plombēto zobu skaitu starp 1.TCD un kontroles grupām, uzrādīja statistiski nozīmīgas atšķirības. Klīniskā izmeklēšanā FKU pacientiem konstatēti vissliktākie mutes higiēnas rādītāji. Viņi arī visretāk tīrīja zobus un izmantoja zobu diegu. Pamatojoties uz anketu datiem, 27 % no FKU pacientiem vecumā līdz 18 gadiem tīrīja zobus vienu reizi dienā, savukārt 6 % netīrīja zobus regulāri. No pacientiem vecumā virs un 18 gadiem 26 % tīrīja zobus tikai reizi dienā. Tikai 39 % FKU pacientu ≥ 18 gadu vecumā un 17 % < 18 gadu vecumā lietoja zobu diegu. Kopumā 45 % ≥ 18 gadu vecumā un 44 % < 18 gadu vecumā apmeklēja zobārstu reizi gadā, savukārt 40 % ≥ 18 gadu vecumā un 39 % < 18 gadu vecumā – retāk nekā reizi gadā. Pēc ieteikumu izlasīšanas ievērojams skaits FKU pacientu, kas jaunāki par 18 gadu vecumu, uzlaboja savus ikdienas mutes higiēnas paradumus – zobu tīrīšanu (25 %) un zobu diega lietošanu (23 %). Analizējot mutes mikrobiomu, vismazākais kopīgo ģinšu skaits bija starp FKU un 1.TCD grupām. FKU grupā tika identificēts vislielākais skaits baktēriju ar būtiski atšķirīgu sastopamību (n = 20), no kurām tādas ģintis kā Actinomyces (padj = 4.17×10−22), Capnocytophaga (padj = 8.53×10−8) un Porphyromonas (padj = 1.18×10−5) bija ievērojami biežāk sastopamas salīdzinājumā ar kontroles grupu. Savukārt, 1.TCD grupā tika novērota paaugstināta Leptotrichia ģints sastopamība (padj = 5.79×10−7), bet Fusobacterium (padj = 2.05×10−4) un Alloprevotella (padj = 7.24×10−4) ģinšu sastopamība bija būtiski zemāka nekā kontroles grupā. Analizējot ģenētisko variantu saistību ar mutes veselības rādītājiem, tika atklāts, ka DEFB1 rs11362 variants saistīts ar augstākiem Silness–Löe aplikuma un Greene–Vermillion indeksiem PKU pacientiem (p = 0.011 un p = 0.043). IL1B rs1143634 variants saistīts ar mazāku nepieciešamību pēc zobakmens noņemšanas 1.TCD pacientiem (p = 0.030). Secinājumi: FKU un 1.TCD pacientiem ir augstāka kariesa izplatība un palielināts periodonta slimību risks salīdzinājumā ar kontroles grupu. FKU, 1.TCD un kontroles grupās ir atšķirīgs mutes mikrobioms, kas var ietekmēt mutes veselību. Ģenētiskā predispozīcija papildus vielmaiņas slimībai un diētai var ietekmēt mutes veselību šajās grupās. Anketu rezultāti par mutes higiēnas paradumiem pirms un pēc mērķētu ieteikumu saņemšanas liecina, ka īpaši pielāgotas pieejas ir nepieciešamas, lai uzlabotu mutes higiēnu, īpaši pieaugušiem FKU pacientiem. Promocijas darbs izstrādāts Rīgas Stradiņa universitātē,...