Age and Periodontal Health - Immunological View.

PURPOSE OF THE REVIEW: Aging clearly impacts a wide array of systems, in particular the breadth of the immune system leading to immunosenescence, altered immunoactivation, and coincident inflammaging processes. The net result of these changes leads to increased susceptibility to infections, increased neoplastic occurrences, and elevated frequency of autoimmune diseases with aging. However, as the bacteria in the oral microbiome that contribute to the chronic infection of periodontitis is acquired earlier in life, the characteristics of the innate and adaptive immune systems to regulate these members of the autochthonous microbiota across the lifespan remains ill defined. RECENT FINDINGS: Clear data demonstrate that both cells and molecules of the innate and adaptive immune response are adversely impacted by aging, including in the oral cavity, yielding a reasonable tenet that the increased periodontitis noted in aging populations is reflective of the age-associated immune dysregulation. Additionally, this facet of host-microbe interactions and disease needs to accommodate the population variation in disease onset and progression, which may also reflect an accumulation of environmental stressors and/or decreased protective nutrients that could function at the gene level (ie. epigenetic) or translational level for production and secretion of immune system molecules. SUMMARY: Finally, the majority of studies of aging and periodontitis have emphasized the increased prevalence/severity of disease with aging, all based upon chronological age. However, evolving areas of study focusing on "biological aging" to help account for population variation in disease expression, may suggest that chronic periodontitis represents a co-morbidity that contributes to "gerovulnerability" within the population.

Resolving differences between animal models for expedited orthodontic tooth movement.

OBJECTIVE: To highlight differences in commonly used animal models of orthodontic tooth movement (OTM). METHODS: Narrative review. RESULTS: A critical review of the literature on animal models has become increasingly important in the last decade as methods to increase the rate of tooth movement have been intensely sought. We provide a review focusing on the rodent and canine models for expedited OTM and describe the challenges in extrapolation of the results to the clinical practice of orthodontics. We review and contrast the two (rodent, canine) most commonly used animal models for OTM. We then describe animal models to study bone adaptation, remodelling and modelling, which are keys events in describing and quantifying OTM. CONCLUSIONS: Understanding the differences between animal models and their adaptation biology as it relates to OTM is key to make valid conclusions. The rodent model can be used to understand the initial phases of tooth movement. Unlike the dog model, the rodent model does not lend itself to understand prolonged adaptation in response to bodily tooth movement. Extrapolation of rate of tooth movement to humans is more challenging from rodent model data.

In vitro evaluation of osteoblast responses to carbon nanotube-coated titanium surfaces.

BACKGROUND: The effects of surface roughness and carboxyl functionalization of multi-walled carbon nanotubes (MWCNTs) mixed with collagen coated onto titanium (Ti) substrates on MC3T3-E1 osteoblasts were evaluated. METHODS: The proliferation, differentiation, and matrix mineralization were investigated using (1) smooth-surfaced Ti discs, (2) Ti discs coated with collagen and MWCNT (Ti-MWCNT), and (3) Ti discs coated with collagen and MWCNT-COOH (Ti-MWCNT-COOH) for applications in orthodontic mini screw implants (MSIs). The coatings were uniform when analyzed using scanning electron microscopy (SEM), and surface roughness was evaluated by surface profilometry that demonstrated similar surface roughness (R a , mean ± SD) in the MWCNT (0.83 ± 0.02 µm) and MWCNT-COOH (0.84 ± 0.01 µm) groups. MTT (3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide) assay was performed after days 1, 3, and 7 to assess proliferation. Alkaline phosphatase (ALP)-specific activity was assessed after day 7 to quantify differentiation. Alizarin red staining was measured after day 28 to quantify matrix mineralization. All data were analyzed with JMP Pro11 software (SAS, USA) with a statistical significance of p < 0.05. RESULTS: Surface profilometry demonstrated similar surface roughness (R a , mean ± SD) in the MWCNT (0.83 ± 0.02 µm) and MWCNT-COOH (0.84 ± 0.01 µm) groups. On day 7, ALP assay showed that MWCNT-COOH (mean ± SD 0.98 ± 0.26 U/µg of protein) enhanced cell differentiation when compared to the uncoated group (p = 0.05). Alizarin red staining after 28 days of cell culture revealed that MWCNT-COOH (mean ± SD 1.5 ± 0.2 OD405) increased (p = 0.03) matrix mineralization when compared to the uncoated group (0.9 ± 0.09 OD405). CONCLUSIONS: This study showed that coatings containing MWCNT-COOH (increased hydrophilic surface chemistry) influence osteoblast proliferation, differentiation, and matrix mineralization and should be further studied for applications in orthodontic MSIs.