Endodontic Treatment of a Maxillary Incisor Tooth in a Chimpanzee (Pan troglodytes).

Chimpanzees (Pan troglodytes) with teeth severely damaged by dental caries and/or periodontal disease are often managed with medication and/or tooth extraction. A common endodontic treatment for severely decayed teeth in a 26-year-old female chimpanzee is reported. The left maxillary central incisor tooth had lost its crown, probably due to trauma that was not recent, and it had a fistula most likely due to chronic apical periodontitis. The diagnosis was confirmed radiographically before treatment. To treat the infected root canal, endodontic treatment used in humans was adapted for a chimpanzee. After the treatment, the tooth was sealed using an adhesive resin composite. At 11-years post-treatment, there were no signs of recurrence of the lesion or of failure of the tooth seal. The results of this case report suggest that common endodontic treatments used in humans are also effective in chimpanzees.

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

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.

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.

Evidence-based consensus for treating incipient enamel caries in adults by non-invasive methods: recommendations by GRADE guideline.

Remineralization treatment, which offers the advantage of being non-invasive, is increasingly being used as a minimal intervention treatment in managing incipient enamel caries. The aim of this review was to develop EBM guideline for optimized strategies for non-invasive treatment of incipient enamel caries. Japanese Society of Conservative Dentistry (JSCD) guideline committee formulated a Guideline for treating incipient enamel caries using the GRADE system, which is the global, mainstream standard for guideline development. The committee selected the most frequent clinical questions (CQs) in treating incipient enamel caries and identified clinically important outcomes in evaluating the efficacy of treatments. Using extensive electronic and manual searches, relevant randomized controlled trials and controlled clinical trials were identified. Based on evidence profiles produced by the committee, the panel discussed the effects, benefits and disadvantages of the selected treatments, as well as their cost effectiveness and feasibility, in order to achieve a consensus in treating incipient enamel caries non-invasively. A recommendation was made for each clinical question after voting by the panel members. Based on the evidence profile and panel discussions for each CQ, the experts strongly recommended application of topical fluoride to inhibit cavitation of incipient enamel caries, and to diminish white spot lesions.

High microbicidal effect of peroxynitric acid on biofilm-infected dentin in a root carious tooth model and verification of tissue safety.

OBJECTIVES: Root-caries, which frequently occurs in elderly people, is more difficult to treat than caries in a tooth crown, especially in filling restorations. To overcome this difficulty, it is essential to find a strategy for sufficiently sterilizing the infected dentin; however, techniques for sterilizing carious pathogens inside the biofilm, called dental plaque, have not yet been established. Recently, dental applications of plasma sterilization technology have attracted attention. The mechanism of plasma sterilization became clear, and revealed that peroxynitric acid (PNA) is an effective sterilization substance. Highly concentrated PNA solutions can be chemically synthesized in large quantities without using plasma technology. We thought that the application of PNA solution could be a novel treatment for root caries, and examined the microbicidal effect and safety of PNA. METHODS: A sterilization experiment was performed using an extracted tooth model infected with Streptococcus mutans. Subsequently, a biofilm of S. mutans and Candida albicans was formed on a plate or a dentin slice, and sterilization experiments were performed in comparison with chlorhexidine. Furthermore, a toxicity test of PNA was performed using an epithelial tissue model. RESULTS: In the infection model, sterilization was achieved with a 22 mM PNA solution in only 10 s. In the biofilm model, a 22 mM PNA solution showed a higher microbicidal effect than 2.0% chlorhexidine. In the toxicity test, 2.0% chlorhexidine was toxic, but a 220 mM PNA solution showed no toxicity. CONCLUSIONS: PNA is an unprecedented disinfectant that has high microbicidal activity on biofilm and is safe for tissues.

Properties of manual toothbrush that influence on plaque removal of interproximal surface in vitro.

BACKGROUND/PURPOSE: Few papers were available on the interproximal cleaning efficiency by manual toothbrushes when used alone. The aim was to investigate the efficiency of commercially available toothbrushes on interproximal cleaning and determine the key properties that would make the differences. MATERIALS AND METHODS: Artificial-teeth were coated with manicure type experimental dental plaque covering mainly the interproximal surface and fixed in the jaw model of a dental simulator. A modified scrubbing technique was employed to brush out the plaque conducted by one trained dentist using 26 different toothbrushes from the equal number of separate interproximal conditions. The rate of the plaque removal (%) was calculated by measuring the plaque free areas on the post-brush images. RESULTS: The data analysis using mixed effect modelling showed that stiffness, number of tufts and total length have effect on the rate of the plaque removable from the interproximal surfaces. CONCLUSION: This study indicated consideration should be given to toothbrush properties to enhance plaque removal from the interproximal surfaces.

A review of the literature on the efficacy of mineral trioxide aggregate in conservative dentistry.

The aim of this literature review was to assess the clinical performance of MTA to establish the evidence level for its effectiveness in vital pulp therapy, perforation repair, and retrograde root canal filling. A comprehensive literature survey was performed via electronic databases of PubMed/MEDLINE. A total of 58 papers were reviewed in this study, of which 2 were systematic reviews/meta-analysis, 9 were randomized controlled trials (RCTs), and the rest were fallen into other categories. Mineral trioxide aggregate (MTA) provided better pulp protection as a direct capping material when compared with calcium hydroxide. As perforation repair materials, MTA demonstrated an excellent sealing ability in vitro. For periodontal tissues around a perforation, MTA provided normal healing processes in clinical trials. It is therefore concluded that MTA has a high potential in repairing perforations. MTA is the most promising material when used for retrograde root canal filling demonstrating normal healing in short/long term clinical outcomes.

A simple technique for impression taking of teeth and functionally generated paths.

The objective of this case report is to introduce a simple technique for simultaneously taking a closed-mouth impression and functionally generated path (FGP) for a full coverage crown restoration. A monolithic zirconia crown was the restoration of choice. An alginate impression of the abutment tooth was taken to fabricate a custom-made closed-mouth impression tray covering the abutment tooth and the adjacent teeth. The tray had an FGP table and an abutment tray in cameo and intaglio surfaces, respectively. The impression was taken with silicone impression material after adjusting the abutment tray and inscribing the FGP using self-curing acrylic resins. Plaster casts were made from the impression, and a zirconia crown was fabricated. The crown was cemented to the abutment tooth with minimal adjustments. This simple technique resulted in a well-fitting crown that accounted for mandibular movements. Using the custom closed-mouth impression tray incorporating an FGP table simultaneously aids in fabricating an accurately fitting restoration that incorporates harmonious mandibular movements using a single impression capture.

Changes in polymerization stress and elastic modulus of bulk-fill resin composites for 24 hours after irradiation.

The objective of this study was to investigate changes in polymerization stress and elastic modulus for light-cured bulk-fill resin composites following irradiation. Crack analysis was applied to obtain the stresses for 24 h after irradiation, which were calculated from the lengths of cracks in a glass mold bonded to the composites. The elastic modulus was repeatedly measured by nano-indentation tests performed over 24 h. The lengths of the cracks, the interfacial stress, and the elastic modulus were significantly affected by the material and time after irradiation (p<0.01). The stress and elastic modulus continued to increase for more than 6 and 1 h, respectively (p<0.05). Strong relationships (r>0.85) were revealed between the stress and elastic modulus. The bulk-fill resin composites generated smaller stresses than a flowable resin composite reported to generate relatively low stress. Post-irradiation polymerization during the first 1 h is a major determinant for the magnitude of stress.

Addition of Na2CO3 Improves the Shelf Life of Experimental 4-META Self-etch Primer.

PURPOSE: The objective of this study was to assess the influence of the addition of Na2CO3 on the shelf life and bond strength of 4-META self-etch primer. MATERIALS AND METHODS: Two 4-META self-etch primers were experimentally formulated with and without the addition of Na2CO3 (primer A and primer B, respectively). The primers were stored at 37°C for several periods of time after formulation. Clearfil SE Bond Primer (Kuraray Noritake Dental) was used as a control. A composite was bonded to bovine dentin using a combination of the primer and a bonding agent (Clearfil SE Bond), and the shear bond strengths were measured. Changes in the pH of the experimental primers were monitored and macroscopic observations were made as a function of the storage periods. RESULTS: With 0-day storage, the bond strength of primer A was equivalent to that of primer B and significantly lower than that of Clearfil SE Primer. The bond strengths of primer A were stable during 90-day storage; by contrast, the bond strengths of primer B significantly decreased during 7-day storage. primer A exhibited stable pH values during 180-day storage; primer B exhibited significantly lower pH than primer A with 0-day storage and discolored gelation during 7-day storage. CONCLUSION: By adding Na2CO3, the shelf life of the 4-META self-etch primer was obviously improved without significant deterioration in dentin bond strength. Adjusting the pH to around 4.5 was effective for obtaining sufficient bond strength and hydrolytic stability of the primer.

Plasma-treated water eliminates Streptococcus mutans in infected dentin model.

Non-mechanical procedures for removing caries-infected dentin are warranted in dentistry. We previously demonstrated the marked sterilization effect for direct irradiation of low-temperature plasma using dentin model infected with Streptococcus mutans. However it requires 180 s of intraoral plasma irradiation to eliminate bacteria. We alternatively investigated whether plasma-treated water (PTW), i.e., pure water exposed to plasma in an atmosphere, has a same bactericidal activity with the plasma irradiation. In the infected dentin model, the viable S. mutans counts recovered by bur at depth of 0.8-2.4 mm from the cavity floor were 104-106 CFU/round bur. After PTW application for only 10 s, the count was significantly decreased to below the detection limit (2.5 CFU/round bur) or 3.0±5.0 CFU/round bur. Since the bactericidal activity of PTW is rapidly deactivated at body temperature (37°C), PTW is likely to be biocompatible and holds significant potential for non-mechanical procedures for removing caries-infected dentin.

Complete genome sequence of Streptococcus troglodytae TKU31 isolated from the oral cavity of a chimpanzee (Pan troglodytes).

Streptococcus troglodytae TKU31 was isolated from the oral cavity of a chimpanzee (Pan troglodytes) and was found to be the most closely related species of the mutans group streptococci to Streptococcus mutans. The complete sequence of TKU31 genome consists of a single circular chromosome that is 2,097,874 base pairs long and has a G + C content of 37.18%. It possesses 2082 coding sequences (CDSs), 65 tRNAs and five rRNA operons (15 rRNAs). Two clustered regularly interspaced short palindromic repeats, six insertion sequences and two predicted prophage elements were identified. The genome of TKU31 harbors some putative virulence associated genes, including gtfB, gtfC and gtfD genes encoding glucosyltransferase and gbpA, gbpB, gbpC and gbpD genes encoding glucan-binding cell wall-anchored protein. The deduced amino acid identity of the rhamnose-glucose polysaccharide F gene (rgpF), which is one of the serotype determinants, is 91% identical with that of S. mutans LJ23 (serotype k) strain. However, two other virulence-associated genes cnm and cbm, which encode the collagen-binding proteins, were not found in the TKU31 genome. The complete genome sequence of S. troglodytae TKU31 has been deposited at DDBJ/European Nucleotide Archive/GenBank under the accession no. AP014612.

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 as a result of inactivation of the amine co-initiator through an 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. The DC of three experimental adhesive formulations, containing either of the two functional monomers [10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) or 4-methacryloxyethyl trimellitic acid anhydride (4-META)] or no 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 the 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.

Streptococcus panodentis sp. nov. from the oral cavities of chimpanzees.

Three strains TKU9, TKU49 and TKU50(T) , were isolated from the oral cavities of chimpanzees (Pan troglodytes). The isolates were all gram-positive, facultative anaerobic cocci that lacked catalase activity. Analysis of partial 16S rRNA gene sequences showed that the most closely related species was Streptococcus infantis (96.7%). The next most closely related species to the isolates were S. rubneri, S. mitis, S. peroris and S. australis (96.6 to 96.4%). Based on the rpoB and gyrB gene sequences, TKU50(T) was clustered with other member of the mitis group. Enzyme activity and sugar fermentation patterns differentiated this novel bacterium from other members of the mitis group streptococci. The DNA G + C content of strain TKU50(T) was 46.7 mol%, which is the highest reported value for members of the mitis group (40-46 mol%). On the basis of the phenotypic characterization, partial 16S rRNA gene and sequences data for two housekeeping gene (gyrB and rpoB), we propose a novel taxa, S. panodentis for TKU 50(T) (type strain = CM 30579(T) = DSM 29921(T) ), for these newly described isolates.

Evaluation of a new hardness tester (Cariotester): Comparison with transverse microradiography for assessing the inhibitory effect of fluoride application on bovine root dentin demineralization.

The objective of this study was to investigate the correlation between CT depth, indentation depth determined by a new hardness tester (Cariotester), and the transverse microradiography (TMR) parameters, i.e., lesion depth and mineral loss. For that purpose, this study evaluated the feasibility of using Cariotester as a root caries diagnostic system and capability of Cariotester to detect effect of fluoride application on inhibiting dentin demineralization. Fluorides were applied to bovine root dentin specimens, which were subsequently demineralized for 1-21 days and then CT depth and TMR parameters were assessed. There were significant correlations between CT depth and TMR parameters in fluoride and non-fluoride groups. There were significant differences between fluoride and non-fluoride groups for CT depth and TMR parameters respectively. Current results suggested that Cariotester may be capable of providing an objective evaluation of root caries progression and the fluoride effect on inhibiting dentin demineralization.

Polymerization stress of dental resin composite continues to develop 12 hours after irradiation.

OBJECTIVE: This study assessed the development of stress from polymerization of light-cured dental resin composites for 24 hours after irradiation. MATERIALS AND METHODS: Initial cracks were made near the edge of a cylindrical hole in glass, and crack lengths were measured. Revolution Formula 2, Kalore and Venus Diamond were polymerized in the hole. Crack lengths were measured at several intervals after irradiation up to 24 hours. Stresses at the composite-glass interface were calculated using the crack lengths. Elastic moduli of the composites were measured at the same time intervals. RESULTS: Interfacial stress and elastic modulus were significantly related to material and time. Stress continued to increase up to 12 hours after irradiation. Significantly lower stresses were measured in Kalore and Venus Diamond than Revolution Formula 2 throughout 24 hours. Stress at 24 hours was two times greater than the stress at 30 minutes. The increase in elastic modulus from 30 minutes to 24 hours ranged from 8 to 24%, which was less than the increase in stress over the same time period. CONCLUSIONS: Interfacial stress and elastic modulus of the composites demonstrated the average increases of 155% and 14%, respectively, from 30 minutes to 24 hours after irradiation. CLINICAL SIGNIFICANCE: Since the elastic modulus is a measure of stiffness and resistance to load, clinicians might consider advising their patients to avoid heavy occlusal function until the elastic modulus has reached a plateau, which would be 60 minutes for Venus Diamond, 12 hours for Kalore, and 24 hours for Revolution Formula 2.

Measurement of surface hardness of primary carious lesions in extracted human enamel -measurement of Knoop hardness using Cariotester.

The clinical feasibility of a novel device called a Cariotester was investigated by measuring the Knoop hardness (KHN) of white spot lesions diagnosed as ICDAS code 1, 2 or 3. To obtain an equation for converting the Cariotester indentation depth into the KHN, a regression analysis was performed between the depth and measured KHN for human enamel. The Cariotester was then used to measure the indentation depth for white spots (ICDAS code 1, 2 or 3) in extracted teeth, and the KHN values were determined using the above equation. The KHN was 219.9±19.7, 162.4±24.0 and 31.7±17.5 for code 1, 2 and 3 lesions, respectively, which was 30, 49 and 90% lower than that for healthy enamel. Using the formula reported in the literature, the mineral density was calculated to be 87.7 vol.% for healthy enamel, and 75.1, 66.1 and 35.5 vol.% for code 1, 2 and 3 lesions, respectively.

Application of chimeric glucanase comprising mutanase and dextranase for prevention of dental biofilm formation.

Water-insoluble glucan (WIG) produced by mutans streptococci, an important cariogenic pathogen, plays an important role in the formation of dental biofilm and adhesion of biofilm to tooth surfaces. Glucanohydrolases, such as mutanase (α-1,3-glucanase) and dextranase (α-1,6-glucanase), are able to hydrolyze WIG. The purposes of this study were to construct bi-functional chimeric glucanase, composed of mutanase and dextranase, and to examine the effects of this chimeric glucanase on the formation and decomposition of biofilm. The mutanase gene from Paenibacillus humicus NA1123 and the dextranase gene from Streptococcus mutans ATCC 25175 were cloned and ligated into a pE-SUMOstar Amp plasmid vector. The resultant his-tagged fusion chimeric glucanase was expressed in Escherichia coli BL21 (DE3) and partially purified. The effects of chimeric glucanase on the formation and decomposition of biofilm formed on a glass surface by Streptococcus sobrinus 6715 glucosyltransferases were then examined. This biofilm was fractionated into firmly adherent, loosely adherent, and non-adherent WIG fractions. Amounts of WIG in each fraction were determined by a phenol-sulfuric acid method, and reducing sugars were quantified by the Somogyi-Nelson method. Chimeric glucanase reduced the formation of the total amount of WIG in a dose-dependent manner, and significant reductions of WIG in the adherent fraction were observed. Moreover, the chimeric glucanase was able to decompose biofilm, being 4.1 times more effective at glucan inhibition of biofilm formation than a mixture of dextranase and mutanase. These results suggest that the chimeric glucanase is useful for prevention of dental biofilm formation.

Dentistry in the 21st century: challenges of a globalising world.

Oral health is - literally - vital to good general health, not least because the mouth is the sentinel of the body. Dentistry, the Cinderella of health care, faces immense challenges of globalisation. Governments, having spent freely on everything from defence to social security, face mountains of debts which make budget cutbacks essential. Simultaneously, most developed countries have to pay increasing costs of caring for rapidly ageing populations. Dentistry is being pulled two ways: wealthy members of society demand high-end expensive treatment, much of it cosmetic rather than necessary to deal with disease, whereas many millions of poor people in developing countries cannot afford basic dental treatment and may never see a dentist. Too many governments and dentists persist with the expensive and destructive regime of 'drill and fill (and bill)'. International advances in care may not reach the clinician's chair because treatment guidelines and payments are set locally. An international symposium to celebrate Mikako Hayashi becoming Professor of Restorative Dentistry and Endodontology at Osaka University concluded that dentistry should move from an increasingly un-affordable curative model to a cost-effective evidence-based preventive model. The goal is to help people retain healthy natural teeth throughout their lives, as an essential part of enhancing their general health.

Newly developed hardness testing system, "Cariotester": measurement principles and development of a program for measuring Knoop hardness of carious dentin.

We previously discovered that when a cone-shaped indenter coated with paint was pressed into an object, the paint disappeared in accordance with the depth of the indentation. Based on this fact, we developed the Cariotester, a portable system for measuring the Knoop hardness (KHN) of carious dentin. The Cariotester is composed of a handpiece with an indenter, a microscope, and a computer. In this system, the painted indenter is forced into the material with a 150-gf load, and the indentation depth (CT depth) is obtained from the paint disappearance. The CT depth by the Cariotester and the KHN by a microhardness tester were determined at 14 dentin regions. From the data, a program was created to convert the CT depth of the carious dentin into the KHN. As a result, if the CT depth is measured with this system, the KHN of carious dentin can be displayed in real time.