The Caries Phenomenon: A Timeline from Witchcraft and Superstition to Opinions of the 1500s to Today's Science

This historical treatise follows the documented timeline of tooth decay into today's understanding, treatment, and teaching of caries biology. Caries has been attributed to many different causes for several millennia, however, only since the late 1900s has research revealed its complex multifactorial nature. European writers of the 1600s to 1700s held views that general health, mechanical injuries, trauma, and sudden temperature changes all caused caries—holding a common belief that decay was due to chemical agents, faulty saliva, and food particles. Until the early 1800s most writers believed that caries was due to inflammation from surrounding diseased alveolar bone. Today's science has demonstrated that caries is caused by indigenous oral microorganisms becoming a dynamic biofilm, that in the presence of fermentable sugars produce organic acids capable of dissolving inorganic enamel and dentin followed by the proteolytic destruction of collagen leaving soft infected dentin. As bacteria enter the pulp, infection follows

A rat model of human FENIB (familial encephalopathy with neuroserpin inclusion bodies)

金沢大学大学院医学系研究科脳細胞分子学FENIB (familial encephalopathy with neuroserpin inclusion bodies) is caused by intracellular accumulation/polymerization of mutant neuroserpins in the endoplasmic reticulum (ER). Transgenic rats overexpressing megsin (Tg meg), a newly identified serine protease inhibitor (serpin), demonstrated intraneuronal periodic-acid Schiff (PAS)-positive inclusions distributed throughout deeper layers of cerebral cortex, CA1 of the hippocampus, and substantia nigra. Hippocampal extracts from Tg meg rats showed increased expression of ER stress proteins, and activation of caspases-12 and -3, associated with decreased neuronal density. Enhanced ER stress was also observed in dopaminergic neurons in the substantia nigra, in parallel with decreased neuronal viability and motor coordination. In each case, PAS-positive inclusions were also positive for megsin. These data suggest that overexpression of megsin results in ER stress, eventuating in the formation of PAS-positive inclusions. Tg meg rats provide a novel model of FENIB, where accumulation of serpins in the ER induces selective dysfunction/loss of specific neuronal populations. © 2006 Elsevier Inc. All rights reserved

Global Oral Health Policies and Guidelines: Using Silver Diamine Fluoride for Caries Control

Silver diamine fluoride (SDF) was developed in Japan in the 1960s. It is a clear solution containing silver and fluoride ions. Because of its anti-bacterial and remineralizing effect, silver diamine fluoride has been used in managing dental caries for decades worldwide. This paper aims to summarize and discuss the global policies, guidelines, and relevant information on utilizing SDF for caries management. SDF can be used for treating dental caries in most countries. However, it is not permitted to be used in mainland China. Several manufacturers, mainly in Australia, Brazil, India, Japan, and the United States, produce SDF at different concentrations that are commercially available around the world. The prices differ between contents and brands. Different government organizations and dental associations have developed guidelines for clinical use of SDF. Dental professionals can refer to the specific guidelines in their own countries or territories. Training for using SDF is part of undergraduate and/or postgraduate curriculums in almost all countries. However, real utilization of SDF of dentists, especially in the private sector, remains unclear in most places because little research has been conducted. There are at least two ongoing regional-wide large-scale oral health programs, using SDF as one of the components to manage dental caries in young children (one in Hong Kong and one in Mongolia). Because SDF treatment does not require caries removal, and it is simple, non-invasive, and inexpensive, SDF is a valuable strategy for caries management in young children, elderly people, and patients with special needs. In addition, to reduce the risk of bacteria or virus transmission in dental settings, using SDF as a non-aerosol producing procedure should be emphasized under the COVID-19 outbreak.</p

Development and feasibility of an oral health e-learning program for long-term Japanese overseas workers: a pilot randomized controlled trial

Abstract Background This study aimed to assess the feasibility and acceptability of an oral health self-care e-learning intervention for overseas workers as well as the research procedures for a future controlled trial. Methods We randomly allocated participants to either the intervention (n = 48) or control (n = 51) group. The intervention group received a standardized leaflet plus a theory-based oral health e-learning program. The control group received only the standardized leaflet. We assessed health behaviour related to fluoride toothpaste use, oral care knowledge, motivation, oral care self-efficacy, and oral health related quality of life (QoL). Chi-square and t test analyses were performed to make comparisons between the two groups. To evaluate the research process, participants in the intervention group were asked open-ended questions to assess the acceptability and feasibility of the research procedures in practice. Results A total of 82 participants (Intervention = 36, Control = 46) were included in the analysis. The dropout rate was 17.2%. The modal time taken to complete the e-learning intervention was more than 30 min (33.3%). Of the 36 respondents in the intervention group, 27 (70.4%) said that the e-learning intervention had changed their behaviour. At the three months follow-up, oral care knowledge alone was improved in the e-learning group. Conclusion This pilot study provides evidence that the theory-based self-care for oral health e-learning intervention is feasible in overseas workers. Next, this feasible and acceptable pilot study should be used with an appropriate sample size in a randomized controlled trial. Trial registration The trial protocol was registered with UMIN-CTR (ID: UMIN000045883) on 27/10/2021

Distribution of Streptococcus troglodytae and Streptococcus dentirousetti in chimpanzee oral cavities

ABSTRACT The aim of this study was to analyze the distribution and phenotypic properties of the indigenous streptococci in chimpanzee (Pan troglodytes) oral cavities. Eleven chimpanzees (aged from 9 to 44 years, mean AE SD, 26.9 AE 12.6 years) in the Primate Research Institute of Kyoto University were enrolled in this research and brushing bacterial samples collected from them. Streptococci were isolated from the oral cavities of all chimpanzees. The isolates (n ¼ 46) were identified as thirteen species by 16S rRNA genes analysis. The predominant species was Streptococcus sanguinis of mitis streptococci from five chimpanzees (45%). Mutans streptococci were isolated from six chimpanzees (55%). The predominant species in the mutans streptococci were Streptococcus troglodytae from four chimpanzees (36%), this species having been proposed as a novel species by us, and Streptococcus dentirousetti from three chimpanzees (27%). Streptococcus mutans was isolated from one chimpanzee (9%). However, Streptococcus sobrinus, Streptococcus macacae and Streptococcus downei, which are indigenous to human and monkey (Macaca fasciclaris) oral habitats, were not isolated. Of the mutans streptococci, S. troglodytae, S. dentirousetti, and S. mutans possessed strong adherence activity to glass surface

Interference of functional monomers with polymerization efficiency of adhesives

The degree of conversion (DC) of camphorquinone/amine-based adhesives is affected by acidic functional monomers due to inactivation of the amine co-initiator through acid-base reaction. During bonding, functional monomers of self-etch adhesives chemically interact with hydroxyapatite (HAp). Here, we tested in how far the latter interaction of functional monomers with HAp counteracts the expected reduction in DC of camphorquinone/amine-based adhesives. DC of three experimental adhesive formulations, either containing one of the two functional monomers, namely 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate) and 4-META (4-methacryloxyethyl trimellitic acid anhydride), or a version without functional monomer (no-FM; control), was measured with and without HAp powder added to the adhesive formulations. Both the variables ‘functional monomer’ and ‘HAp’ were found to be significant, with the functional monomer reducing DC and HAp counteracting this effect. It is concluded that the functional monomers 10-MDP and 4-META interfere with the polymerization efficiency of adhesives. This interference is less prominent in the presence of HAp, which would clinically correspond to when these two functional monomers of the adhesive simultaneously interact with HAp in tooth tissue.status: publishe

TEM interfacial characterization of an experimental self-adhesive filling material bonded to enamel/dentin

A great challenge regarding the ease-of-use of composites involves the development of 'self-adhesive' composites that no longer require a separate adhesive to bond to tooth enamel/dentin. OBJECTIVES: To characterize the interfacial ultra-structure of an experimental self-adhesive filling material bonded to enamel and dentin using transmission electron microscopy (TEM). METHODS: The experimental self-adhesive material was bonded to bur-cut human enamel and dentin, and to fractured (smear-free) dentin, strictly according to the manufacturers' instructions. The specimens were stored for 1 day in distilled water (37°C) prior to further common specimen processing for TEM. RESULTS: The experimental self-adhesive filling material revealed a typical micro-hybrid filler distribution. At bur-cut enamel, a tight interface was formed, mostly exhibiting only tiny micro-tags without distinct surface demineralization. At bur-cut dentin, the experimental self-adhesive filling material interacted superficially, with the surface structure being more irregular because of the bur preparation. No clear resin tags were formed due to the obstruction of dentin tubules with smear plugs. At fractured dentin, the formation of a relatively thin hybrid layer of maximum a few hundreds of nanometer was disclosed without clear surface demineralization. Distinct resin tags were formed due to the absence of smear plugs. Silver-nitrate infiltration showed a pattern of spot-like appearance of nano-leakage. Ag deposition was observed more along the dentin-adhesive interface of bur-cut dentin, as compared to that of fractured dentin. SIGNIFICANCE: The obtained tight interface at both enamel and dentin demonstrates the self-adhesive capacity of the experimental self-adhesive filling material.status: publishe