The Impact of a Microcrystalline Hydroxyapatite Toothpaste on Recolonization of Oral Microbiota After Periodontal Therapy

Objectives: Previous studies suggested anti-adhesive effects of oral hygiene products containing microcrystalline zinc hydroxyapatite (mHA). In this study, we investigated the effect of a toothpaste containing mHA compared to a fluoridated toothpaste (AmF/SnF₂) on oral microbial recolonization of patients after periodontal treatment.
Methods: We analyzed 369 samples from 41 randomly selected patients with chronic periodontitis from a larger study. Twenty of those used a toothpaste with mHA (test) and 21 with AmF/SnF₂ (control) for daily oral care. From each patient 9 pooled samples from four representative teeth were taken: (i) supragingival-buccal (ii) supragingival-interdental and (iii) subgingival-interdental at three time points: (1) baseline, (2) two weeks after supragingival mechanical debridement and (3) 10 weeks after supra- and subgingival debridement. Sequencing of the 16S-rDNA of oral bacteria was performed using Illumina Miseq Sequencing. All raw reads were processed based on ribosomal sequence variances using the DADA2-pipeline. Differences between test and control groups on compositional level were analyzed using Bray-Curtis dissimilarity, principal coordinates analyses, and PERMANOVA. Analysis of single bacterial taxa was done with a negative binomial regression model.
Results: Altogether 370 different bacterial taxa were identified. We found a statistically noticeable difference on compositional level, between the three sampling sites at each time point (p=0.001). Taxa classified as Prevotella and Alloprevotella showed a stronger reduction in the test group after therapy at the supragingival-buccal sites. At the supragingival-interdental sites taxa classified as Lactobacillus increased only in the control group. At the subgingival-interdental sites Moryella decreased only in the test group. However, all other identified taxa were not differentially affected between both groups.
Conclusions: The daily use of a mHA containing toothpaste as an adjunct to periodontal therapy reduced recolonization of single oral taxa compared to a fluoridated toothpaste and this was stable for at least 12 weeks.