Fungi and bacteria occupy distinct spatial niches within carious dentin.

The role of bacteria in the etiology of dental caries is long established, while the role of fungi has only recently gained more attention. The microbial invasion of dentin in advanced caries especially merits additional research. We evaluated the fungal and bacterial community composition and spatial distribution within carious dentin. Amplicon 16S rRNA gene sequencing together with quantitative PCR was used to profile bacterial and fungal species in caries-free children (n = 43) and 4 stages of caries progression from children with severe early childhood caries (n = 32). Additionally, healthy (n = 10) and carious (n = 10) primary teeth were decalcified, sectioned, and stained with Grocott's methenamine silver, periodic acid Schiff (PAS) and calcofluor white (CW) for fungi. Immunolocalization was also performed using antibodies against fungal ß-D-glucan, gram-positive bacterial lipoteichoic acid, gram-negative endotoxin, Streptococcus mutans, and Candida albicans. We also performed field emission scanning electron microscopy (FESEM) to visualize fungi and bacteria within carious dentinal tubules. Bacterial communities observed included a high abundance of S. mutans and the Veillonella parvula group, as expected. There was a higher ratio of fungi to bacteria in dentin-involved lesions compared to less severe lesions with frequent preponderance of C. albicans, C. dubliniensis, and in one case C. tropicalis. Grocott's silver, PAS, CW and immunohistochemistry (IHC) demonstrated the presence of fungi within carious dentinal tubules. Multiplex IHC revealed that fungi, gram-negative, and gram-positive bacteria primarily occupied separate dentinal tubules, with rare instances of colocalization. Similar findings were observed with multiplex immunofluorescence using anti-S. mutans and anti-C. albicans antibodies. Electron microscopy showed monomorphic bacterial and fungal biofilms within distinct dentin tubules. We demonstrate a previously unrecognized phenomenon in which fungi and bacteria occupy distinct spatial niches within carious dentin and seldom co-colonize. The potential significance of this phenomenon in caries progression warrants further exploration.

Key themes in periodontal treatment: Lessons learned from 40-year experiences.

BACKGROUND: Periodontitis is one of the most prevalent oral diseases with significant implications for systemic health. This study aims to explore themes influencing successful long-term outcomes in periodontal treatment through a historical lens, focusing on various factors influencing the longevity of periodontal health and dentition stability. METHODS: Utilizing an inductive qualitative thematic analysis approach, this study utilized a retrospective chart review of 19 patient records spanning, on average, 40 years. RESULTS: Four major themes contributing to periodontal stability were identified: (1) adequate patient plaque control; (2) regular periodontal maintenance; (3) collaboration between hygienists and periodontists; and (4) the application of various periodontist/dentist-performed procedures. CONCLUSION: Current findings underscore the importance of these factors in preserving patients' periodontal health by emphasizing conservative treatment approaches in the maintenance and retention of the natural dentition. KEY POINTS: Adequate patient plaque control is essential for maintaining a patient's periodontal health and dentition long-term. A regular periodontal maintenance schedule should be assigned and modified as necessary for each individual patient's care. Collaborative care with hygienist colleagues and ensuring there are flexible treatment options for patients can lead to successful treatment outcomes when hygiene alone is not sufficient. PLAIN LANGUAGE SUMMARY: Periodontitis is a widespread oral disease with significant systemic health implications. This study examined patient records to identify factors contributing to long-term periodontal stability and maintenance of teeth. By analyzing 19 patient charts over an average of 40 years using a qualitative approach, four key themes were identified in successful patient treatments: effective patient plaque control, regular periodontal maintenance, collaboration between dental hygienists and periodontists, and the addition of other approaches by periodontists and dentists when necessary. The study underscores the importance of these factors in preserving periodontal health and retaining natural teeth with conservative treatment approaches. This research highlights the critical role of sustained, multifaceted dental care and professional collaboration in achieving successful long-term oral and systemic health outcomes.