Changes in a Child's Subgingival Microbiome Following Prophylaxis - a Pilot Study

• Author / Creator

  Gibb, Andrew

• Background: Periodontitis is a multifactorial, complex chronic oral disease facilitated by oral microbes. Transmissibility studies of the past have shown that oral microbes are transmissible between individuals. Furthermore, periodontal disease phenotypes also appear to be inheritable to some extent, both from parent to child and between adults. Modern DNA sequencing has allowed for greater resolution and further insight into the transmission rates of the oral microbiome. In this study, transmission rates of the oral microbiome were investigated within the family unit, especially as it relates to the recolonization of the oral microbiome of the youngest child in multi-child families.Aims: 1) Identify the sources of subgingival microbiome within an individual. 2) Identify the effect of intimate contact between parents and child as well as between siblings and child in vertical and horizontal transmission of the microbiome. 3) Examine the effect of recolonization on the child after professional oral prophylaxis.Materials and methods: 14 families were recruited, each family having 1 mother, 1 father, and two or more children. Microbial samples were collected from each individual. Oral prophylaxis was then performed for the youngest child. An additional saliva sample was collected from the youngest child at day 3, and then all oral samples again collected for the youngest child at one week following prophylaxis. Samples were then processed and DNA isolated, sequenced (V1-V3), and passed through a computational pipeline (DADA2) to determine amplicon sequence variants (ASVs). These were then analyzed using a Bayesian analysis model to estimate the contribution of all samples to the subgingival microbiota of the youngest child.Results: The findings of this study are four-fold:1. Oral niche was the main driver of microbial separation. The microbes that were found in a specific location in the mouth were mainly selected due to the characteristics of that niche rather than by familial similarity or geographical proximity.2. Saliva was the conduit for oral cavity microbiota. Saliva was the main vehicle for microbial transmission between individuals. The saliva was made up of microbes from other areas of the mouth, including the tongue (58.9%), buccal mucosa (14.8%), supragingival plaque (1.1%), subgingival plaque (0.8%), and unknown sources (12.5%).3. Various sources of microbes contributed to the subgingival plaque of the child. Some of these sources were internal to the child, specifically the subgingival plaque already present at time 0 (46%), as well as the supragingival plaque at time 0 (9%), and buccal mucosal microbes (1%). Sources external to the child also existed. Both mother and father contributed about 3% each to the recolonization of the oral microbiome, while each sibling contributed approximately 8%. Of those sources external to the child, 8% was from subgingival sources, 4% from supragingival sources, and 1% was from the buccal. All other sources were negligible.4. The only close contact activities that had a statistically significant contribution to the subgingival plaque of the child included mother close sleeping with the child and saliva contribution, and father kissing the child on the cheek and buccal mucosal microbial transmission. Conclusion: Within the family unit, transmission of oral microbes does occur. This transmission is most pronounced between siblings (8%), and not as strongly from parent to child (3%) as originally expected. The majority of this transmission is via the saliva, which contains only 0.8% of subgingival bacteria. Even then, the major contributor to the subgingival microbes of the child from external sources is the subgingival bacteria of family members. As shown in this study, transmission of oral microbes between family members does occur, with greater importance seen in the contribution of siblings than expected. Thus, the treatment of periodontal disease may need to shift from an individual disease control model to a family-based, transmissible disease model.

• Subjects / Keywords

  • oral
  • microbiome
  • niche
  • transmission

• Graduation date

  Fall 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-r22p-ty81

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.