Tests for proteins in saliva that control cavity-causing microbes could help predict a young child’s risk of dental caries. In a review article, Jing Zou and colleagues from Sichuan University in Chengdu, China, outline the roles of oral microorganisms and salivary proteins in the development and prevention of tooth decay in preschool-aged children. Streptococcus bacteria are the main cause of caries in young children, although other bacteria and fungi also contribute. Various proteins and other biomolecules found in saliva affect the survival of these microbes. The authors suggest that the concentrations of these proteins could serve as early indicators of tooth decay risk. However, studies have not found a correlation between total salivary proteins and decay risk, suggesting that more work is needed to identify the best biomarker in saliva.

Using blue light, researchers can detect the presence of abnormal cells in tissues such as the tongue. As abnormal (‘dysplastic’) cells can become cancerous, prompt identification and treatment are key. Researchers led by Koji Kawaguchi from Japan’s Tsurumi University-, Yokohama, shone a specific wavelength of blue light onto the tongues of 62 patients. The excitatory light caused healthy tissue to fluoresce green light, whereas dysplastic or cancerous tissue appeared black. Results were compared against final diagnoses done via biopsy. To minimize human error, the emitted light was measured digitally rather than manually, as had been done in previous studies on the technique, known as ‘autofluorescence visualization’. This change improved result consistency; however, some cancers were missed. The team are optimistic that their technique has great clinical potential after further refinements.

The Encouraging Novel Amelogenesis Models and Ex vivo cell Lines (ENAMEL) Development workshop was held on 23 June 2017 at the Bethesda headquarters of the National Institute of Dental and Craniofacial Research (NIDCR). Discussion topics included model organisms, stem cells/cell lines, and tissues/3D cell culture/organoids. Scientists from a number of disciplines, representing institutions from across the United States, gathered to discuss advances in our understanding of enamel, as well as future directions for the field.

Research in mice has provided new insight into the mechanisms through which the protein enamelin contributes to formation of tooth enamel. Enamelin is one of several proteins that make up the enamel matrix and is secreted from ameloblasts, the cells responsible for enamel formation. Previous work has shown that mutation of enamelin to prevent its phosphorylation at a specific site disrupts enamel formation. Xiaofang Wang from the Texas A&M University College of Dentistry, USA, and colleagues showed that the mutation caused a fragment of enamelin that is normally secreted to remain inside ameloblasts, altering the enamel matrix and affecting cellular processing of ameloblastin, another essential component of the enamel matrix. The finding shows that preventing phosphorylation of enamelin at the mutated site hinders interactions of the proteins required for enamel formation.

An investigation into the interaction between tooth root cells and an inflammatory protein sheds light on root degradation following injury. Osteoclast cells digest old bone to release nutrients and recycle bone tissues in a vital process called bone resorption. Cementum, the mineral substance covering tooth roots, is not usually resorbed, but injury to the tissues surrounding roots often triggers inflammation followed by root degradation. To understand this phenomenon better, Ruchanee Salingcarnboriboon Ampornaramveth at Chulalongkorn University in Bangkok, Thailand, and co-workers investigated whether cementum cells can promote the formation of osteoclasts. They found that when cementum cells were treated with interleukin 1 beta, an inflammatory protein expressed at high levels in tissues following injury, levels of another protein needed for osteoclast formation increased. This boosted osteoclast formation around roots, resulting in root resorption

Bacteria in dental plaque from children with early childhood caries metabolize carbon from different sources than bacteria from healthy individuals. Early childhood caries (ECC) is the most common chronic disease in children. Scientists from the Peking University School and Hospital of Stomatology led by Feng Chen and Yunsong Liu, compared the oral microbe populations of 18 ECC patients and 18 caries-free children. The team found that bacteria in plaque from ECC patients preferred certain sugars and carbohydrates as carbon sources, whereas bacteria from healthy subjects preferred certain amino acids and short protein chains. Analysis showed that anaerobic bacteria in ECC patients exhibited greater metabolic activity than those from the caries-free group. This study indicates that metabolic profiles could act as ‘signatures’ of disease states, and that further studies might suggest carbohydrates for ECC-susceptible children to avoid.

Investigation of bacterial cells that can evade treatment for tooth decay has suggested a novel approach that could improve treatment. Streptococcus mutans, the main bacteria involved in tooth decay, are targeted with antibiotics called quaternary ammoniums, but some bacterial cells, known as persisters, can evade these drugs by becoming dormant, reducing the effectiveness of treatment. Lei Cheng from Suchuan University, China, and colleagues have now investigated the development of persisters when the usually highly effective quaternary ammonium dimethylaminododecyl methacrylate was used against cultures of S. mutans. Persisters were present after treatment, and exhibited tolerance to six other antibiotics. However, increasing the amount of glucose in the cultures to stimulate metabolism in the persisters reduced their numbers, suggesting that such a novel approach may improve antibacterial treatment for tooth decay.