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 (padj = 4.17 × 10−22), Capnocytophaga (padj = 8.53 × 10−8), and Porphyromonas (padj = 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.

Objectives 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. Material and Methods 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. Results 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). Conclusion 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.