Stress is typically thought of as a negative phenomenon, but researchers at Hong Kong University (HKU) Dentistry found “positive stress” that can induce good changes in tooth stem cells to make them more resistant to injury and disease.

The study, published in the Journal of Dental Research, is the first to show that adaptive mechanisms in tooth stem cells induced by preconditioning to stress can boost the tooth pulp tissue regeneration. The researchers found that oxidative stress caused by a low-oxygen environment can elicit a protective response to make tooth stem cells less vulnerable to harm.

The research team led by Dr Waruna Dissanayaka, Assistant Professor in Oral Biosciences, aims to develop an approach to regenerate lost tooth pulp, which could revitalise the tooth and enable it to function normally.

The research team developed a preconditioning protocol that modified the cells genetically to mimic a responsive state for low oxygen conditions in order to activate a protein that induces adaptive changes in the cells.

Dr Yuanyuan Han, a co-investigator of the team pointed out: “As this protein was reported to activate several key adaptive mechanisms, we wondered whether this phenomenon can be applied to improve cell survival following transplantation until a sufficient blood supply is achieved”.

Dr Dissanayaka plans to utilise the knowledge of specific genes and proteins responsible for inducing cell survival to identify drugs that can be used in clinical tissue regeneration. He believes these new findings will promote the development of new strategies to enhance the therapeutic potential of tooth stem cells.


Research led by the University of Kent has discovered evidence of a biorhythm in human primary teeth that is associated with weight gain during adolescence. An international research team led by Dr Patrick Mahoney at Kent’s School of Anthropology and Conservation discovered the biorhythm in primary ‘milk’ molars, Retzius periodicity (RP), is related to aspects of physical development during early adolescence. A faster dental biorhythm produced smaller gains in weight and mass.

RP forms through a circadian-like process, occurring with a repeat interval that can be measured with a resolution of days. The rhythm relates to the period in which tooth enamel forms and is consistent within the permanent molars of individuals that do not retain evidence of developmental stress. The human modal RP has a near seven-day cycle but can vary from five to 12 days.

The first-of-its-kind research published by Nature’s Communications Medicine found that adolescents with a faster biorhythm (five- or six-day cycle) weighed less, gained the least weight, and had the smallest change in their body mass index over a 14-month period compared to those with a slower biorhythm. Those with a slow biorhythm (seven- or eight-day cycle) produced the greatest weight gain.

Dental histologists have known about the biological rhythm for over 100 years, but its significance for body mass and growth emerged recently in studies that compare mammalian species. Research has now focused on the meaning of the rhythm for humans. Rapid change in body size is a natural consequence of adolescence, but excessive weight gain during puberty can have vast consequences for health, such as obesity in adulthood.


Trinity College Dublin researchers, collaborating with University College London, have demonstrated for the first time the low environmental footprint of water fluoridation compared to other preventive measures for tooth decay. The study is published in the British Dental Journal.

Researchers quantified the environmental impact of water fluoridation for an individual five-year-old child over a one-year period and compared this to the traditional use of fluoride varnish and toothbrushing programmes, which take place in selected schools across the UK, and internationally.

Today, over 35% of the world’s population have access to water fluoridation, with studies showing significant reductions in dental caries. While data on the clinical effectiveness and cost analysis of water fluoridation are available, there have been no data regarding its environmental impact up to now.

To quantify this impact, the research team performed a life cycle assessment (LCA) by carefully measuring the combined travel, weight and amounts of all products and the processes involved in all three preventive programmes (toothbrushing, fluoride varnish programmes and water fluoridation).

The results of the study, led by Brett Duane, Associate Professor in Dental Public Health at Trinity College, concluded that water fluoridation had the lowest environmental impact in all categories studied, and had the lowest disability-adjusted life years impact when compared to all other community-level caries prevention programmes. The study also found that water fluoridation gives the greatest return on investment.

Considering the balance between clinical effectiveness, cost effectiveness and environmental sustainability, researchers believe that water fluoridation should be the preventive intervention of choice.


Though dry eye disease and xerostomia (dry mouth) have both been studied extensively independently of each other, their relationship remains relatively unexplored. A recent study of 150 randomly selected 65-year-olds in Norway has, therefore, examined this link and found that a correlation exists between the two conditions.

Researchers from the University of Oslo’s Faculty of Dentistry and the Norwegian Dry Eye Clinic collaboratively carried out the cross-sectional study. Potential study subjects were randomly chosen from the Norwegian tax registry and invited to participate in an initial examination.

Each participant underwent subjective and objective dry eye assessments at the Norwegian Dry Eye Clinic. This involved several questionnaires and a clinical examination. Subsequently, the study subjects were orally examined at the research clinic at the University of Oslo’s Faculty of Dentistry and asked to complete an additional questionnaire on the frequency of the oral dryness they experienced. Each participant’s xerogenic medication intakes and histories of systemic disease were also recorded.

According to the study authors, a significant positive correlation was found between dry eye and xerostomia symptoms among the study’s participants. Through examinations, the two conditions were demonstrated to coexist pathologically in 4% of the study’s subjects, whereas those with current or former systemic diseases were very likely to experience symptoms of dry eye disease and xerostomia.

The study, titled ‘The relationship between ocular and oral dryness in a cohort from the 65-year-old population in Norway’, was published online in Scientific Reports.


Even with the support of modern computer-aided design (CAD)/computer-aided manufacturing (CAM) technology, creating a dental prosthesis is still time-consuming, resulting in more chair time and high costs for patients. To facilitate the design of molar crowns, researchers from the Faculty of Dentistry at the University of Hong Kong (HKU) and the Department of Computer Science of Chu Hai College of Higher Education in Hong Kong collaborated to develop a novel approach using artificial intelligence (AI).

In order to restore the patient’s original appearance, masticatory function and general oral health, dental protheses should have the same occlusal morphology and 3D position of the natural teeth. These can be deduced for a missing tooth from those of the surrounding dentition because the teeth of an individual are all controlled by the same set of genes and exposed to the same oral environment. The researchers hypothesised that AI could thus generate the design for a single-tooth prothesis based on the characteristics of the remaining dentition.

The research team used a machine learning approach called a generative adversarial network (GAN) to train and validate their AI system and have tested it on 175 participants. The system was able to reconstruct the shape of a natural tooth and automate the process of dental protheses design based only on the digital model of the patient’s dentition.

The study, titled ‘Artificial intelligence-designed single molar dental prostheses: A protocol of prospective experimental study’, was published online in PLOS ONE.


Biofilm not fully cleared from the nooks and crannies of the root canal system remains a leading cause of treatment failure and persistent endodontic infections, and there are limited means to diagnose or assess the efficacy of disinfection. One day, clinicians may have a new tool to overcome these challenges in the form of microrobots.

In a proof-of-concept study, researchers from Penn Dental Medicine in the US and its Center for Innovation & Precision Dentistry (CiPD), have shown that microrobots can access the difficult to reach surfaces of the root canal with controlled precision, treating and disrupting biofilms and even retrieving samples for diagnostics, enabling a more personalised treatment plan. The Penn team shared their findings on the use of two different microrobotic platforms for endodontic therapy in the August issue of the Journal of Dental Research.

In both platforms, the building blocks for the microrobots are iron oxide nanoparticles (NPs) that have both catalytic and magnetic activity and have been FDA approved for other uses. In the first platform, a magnetic field is used to concentrate the NPs in aggregated microswarms and magnetically control them to the apical area of the tooth to disrupt and retrieve biofilms through a catalytic reaction. The second platform uses 3D printing to create miniaturised helix-shaped robots embedded with iron oxide NPs. These helicoids are guided by magnetic fields to move within the root canal, transporting bioactives or drugs that can be released on site.


Dental teams are in the ideal position to identify and act on early signs of eating disorders, says the Oral Health Foundation in the UK. Around nine-in-ten (90%) patients with bulimia and one-in-five (20%) with anorexia suffer from enamel erosion. Tooth decay, sensitive teeth, dry mouth and enlarged salivary glands are also frequent.

The Oral Health Foundation believes that thousands of undiagnosed eating disorder can be picked up during regular dental check-ups by dentists, dental hygienists, therapists, and dental nurses.

Chief executive of the Oral Health Foundation, Dr Nigel Carter, says: “During the routine dental examination, dental teams carry out checks on the hard and soft tissues of the mouth and look for signs of tooth erosion. They will also look for possible injuries to the mouth which could have been induced by inserting foreign objects that cause a person to vomit”.

He continued: “If they suspect that a person might be suffering from an eating disorder, they will be able to talk calmly through the clinical signs they are seeing in the mouth. They might also speak about prescribing a high fluoride toothpaste or varnish to protect your teeth from decay.

“The more open and honest patients can be with their dental team, the better they will be able to help. Your dental team can be trusted to help you and will not judge you over any symptoms you are having”.


People with both type 1 and type 2 diabetes are prone to tooth decay, and a new study from Rutgers School of Dental Medicine in the United States may explain why: reduced strength and durability of enamel and dentine (the hard substance under enamel that gives structure to teeth).

Researchers induced type 1 diabetes in 35 mice and used a Vickers microhardness tester to compare their teeth with those of 35 healthy controls over 28 weeks. Although the two groups started with comparable teeth, enamel grew significantly softer in the diabetic mice after 12 weeks, and the gap continued to widen throughout the study. Significant differences in dentine microhardness arose by week 28.

Mohammad Ali Saghiri, an assistant professor of restorative dentistry at the Rutgers School of Dental Medicine said: “We’ve long seen elevated rates of cavity formation and tooth loss in patients with diabetes, and we’ve long known that treatments such as fillings do not last as long in such patients, but we did not know exactly why”.

The study advances a multiyear effort by Saghiri and other researchers to understand how diabetes affects dental health and to develop treatments that counter its negative impact. Previous studies have established that people with both types of diabetes have significantly elevated rates of most oral health issues, both in the teeth and the soft tissues that surround them. Saghiri and other researchers also have demonstrated that diabetes can interfere with the ongoing process of adding minerals to teeth as they wear away from normal usage.


A shapeshifting robotic microswarm may one day act as a toothbrush, rinse, and dental floss in one. The technology, developed by a multidisciplinary team at the University of Pennsylvania, is poised to offer a new and automated way to perform the mundane but critical daily tasks of brushing and flossing. It’s a system that could be particularly valuable for those who lack the manual dexterity to clean their teeth effectively themselves.

The building blocks of these microrobots are iron oxide nanoparticles that have both catalytic and magnetic activity. Using a magnetic field, researchers could direct their motion and configuration to form either bristle-like structures that sweep away dental plaque from the broad surfaces of teeth, or elongated strings that can slip between teeth like a length of floss. In both instances, a catalytic reaction drives the nanoparticles to produce antimicrobials that kill harmful oral bacteria on site.

Experiments using this system on mock and real human teeth showed that the robotic assemblies can conform to a variety of shapes to nearly eliminate the sticky biofilms that lead to cavities and gum disease. The Penn team shared their findings establishing a proof of concept for the robotic system in the journal ACS Nano.

The customisable nature of the system, the researchers say, could make it gentle enough for clinical use, but also personalised, able to adapt to the unique topographies of a patient’s oral cavity.

To advance this technology to the clinic, the Penn team is continuing to optimise the robots’ motions and considering different means of delivering the microrobots through mouth-fitting devices.

They’re eager to see their device help patients.


The British Orthodontic Society (BOS) has recently released guidance on teledentistry and remote interactions in orthodontic care. The guidance is planned to help orthodontic providers and their teams gain a deeper understanding of the scope of teledentistry services and technologies for orthodontic care.

According to the guidance, dental professionals can greatly benefit from teledentistry. For one, it has the potential to enhance patient care and help achieve desired treatment outcomes. When integrated into orthodontic care, teledentistry can also offer improved accessibility and patient satisfaction. Most importantly, it decreases the number of physical appointments, culminating in reduced environmental impact and less face-to-face contact, a benefit that has gained increased value during the Covid-19 pandemic.

According to the BOS, clinicians should be made aware of some core principles when conducting a remote orthodontic consultation. For example, it is vital that all diagnostic and prescriptive decisions are made by a registered treating orthodontist or a dentist who has proper training and skills and is directly involved in the monitoring of orthodontic care.

It also points out certain patient rights. It explains that patients who are undergoing treatment should receive the contact information of the responsible clinician and be able to make direct contact or arrange face-to-face appointments when required. In the case of clear aligner treatment, patients should also be informed not only about the benefits but also about the limitations of such treatment and made aware that they are going to receive a medical procedure involving a medical device.




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