Study design 
 
 The purpose of this study was to investigate whether natural dentine repair could be enhanced by stimulating the formation of reparative dentine. Adult CD1 wild-type mouse first molars were used and damage stimulated by controlling drilling (see below). The drugs of choice and vehicle were based on previous reports in the literature and also translational potential into a simple, cost effective dental therapy. 
 
 In order to evaluate the reparative capacity of the drugs, six to nine teeth were evaluated per time point and a sample size of 20–30 teeth per group was used for the in vivo gene expression assay. The reparative time points used in this study were in accordance with UK Home Office animal regulations. This study was not blind and sample selection was not random. 
 
 Injury Protocol 
 
 All animals used in this study were handled in accordance to UK Home Office Regulations project license 70/7866 and personal license I6517C8EF. Experimental procedures were approved by the King’s College Ethical Review Process. The mice were anaesthetized with a solution made with Hypnorm (Fentanyl/fluanisone - VetaPharma Ltd.), sterile water and Hypnovel (Midazolam - Roche) in the ratio 1:2:1 at the rate of 10 ml/kg intraperitonially. A rounded carbide burr FG 1/4 coupled to a high speed hand piece was used to access the dentine of the mouse superior molar teeth. Once the burr cut exposed the dentine, a 30G needle was used to penetrate the pulp. In order to protect the pulp from external contamination and stimulate dentine repair, the injury was capped either with ProRoot Mineral Trioxide Aggregate (MTA) (Maillfer Dentsply), or Kolspon (Fish Collage Type 1- Eucare Ltd) alone, or in association with 50 nM BIO (SIGMA), 5 μM CHIR99021 (SIGMA), or 50 nM Tideglusib (SIGMA) dissolved and diluted in DMSO, in contact with the pulp. A layer of 3 M Ketac-Cem Radiopaque was used as a capping material to seal the injured site. The damage was performed on the two upper first molars. For incisor damage a fine needle was inserted through the mouse lower tooth into the pulp. Post-op the mice were given Vetergesic (Buprenorphine – Ceva) at the rate of 0.3 mg/kg by intraperitoneal injection as analgesic. The animals were sacrificed after 1 day, 4 weeks and 6 weeks. 
 
 Cytotoxity assay 
 
 17IA4 cells were plated in 96 well plates at 20,000 cells/cm2 and incubated (37 °C, 5% CO 2 /95% air, 100% humidity) for 24 hrs using standard culture medium. Thereafter, the medium was replaced with conditioned (drugs + media) and control media (media alone) for another 24 hrs. (10 μl of drug in DMSO + 90 μl of media resulting on the following concentrations BIO: 200, 100, 50 nM; CHIR99021: 10, 8, 5 μM; Tideglusib: 200, 100, 50 nM). To determine the cell metabolic activity, MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide, Sigma) was added to the controls and the conditioned media after 24 hrs. The resulting formazan product was then dissolved in 200 μl of dimethyl sulfoxide per well (DMSO, Sigma). A colorimetric plate reader (Thermo Multiskan Ascent 354 microplate reader) was used to read the absorbance at 540 nm with background subtraction at 630 nm. 
 
 In vitro drug release 
 
 17IA4 cells were plated in 24-well plates and incubated (37 °C, 5% CO 2 /95% air, 100% humidity) for 24 h using standard culture medium. FalconTM cell culture inserts for use with 24-well plates (3 μm pore size) were placed in the wells carrying 96 mm2 Kolspon cubes either dry or soaked in 30 μl of the drug optimal concentration for 15 and 30 minutes, 1, 6, and 12 hours. The cells were collected with TRIzol and stored at −20 °C. 
 
 Pulp collection 
 
 P21 mice had their superior first molars drilled according to the drilling protocol. Tooth pulp tissue was collected according to the experiment time course after injury. The superior first molars were extracted using a 21 G needle as an elevator to lift them from the alveolar bone and the extracted molars were kept in ice cold PBS. Using a 23 scalpel blade the molars were separated at the crown-root junction, so that the pulp chamber could be visualized. Using a 0.6 mm straight tip tweezer the pulp was gently scraped from the pulp chamber and the root canal. The pulp was then placed into cold Sigma RNAlater and stored at −80 °C. 
 
 Q-PCR 
 
 RNA was extracted from the cells in culture with the drugs in after 15, and 30 mins, 1, 6, and 12 hours, and also from the dental pulp collected from CD1 P21 wild-type mice without injury (control) and 1 day after injury using TRIzol. (Thermo Fisher Scientific) as recommended by the manufacturer. The RNA was quantified using Nanodrop and reverse transcribed into cDNA. Beta-actin was used as housekeeping gene (Forward- GGCTGTATTCCCCTCCATCG, Reverse- CCAGTTGGTAACAATGCCTGT) and Axin2 was the read-out for Wnt pathway activity (Forward-TGACTCTCCTTCCAGATCCCA, Reverse-TGCCCACACTAGGCTGACA). 
 
 MicroCT/mineral analysis 
 
 Mice upper molars were dissected and fixed with PFA 4% overnight and scanned using a Bruker Skyscan1272 micro-CT scanner. After scanning, Microview software programme (GE) was used for visualization and analysis. Two dimensional (2D) images were obtained from micro-CT cross-sectional images of superior first molar internal part, to evaluate if the drilling was successful and mineral formation. In order to assay tissue mineral content a ROI of X = 0.2 mm, Y = 0.4 mm, and Z = 0.2 mm was set as standard for all the samples and the mineral analysis was performed. The region measured comprised only of the injury site. ROI complete filled with mineral = 0.0017 mg. 
 
 Histology 
 
 After 4 weeks decalcification in 19% EDTA the teeth were embedded in wax blocks and sectioned using 8 μm thickness. Sections were stained using Masson’s Trichrome. 
 
 β-galactosidase staining ||||| Image copyright Thinkstock 
 
 Teeth can be encouraged to repair themselves in a way that could see an end to fillings, say scientists. 
 
 The team at King's College London showed that a chemical could encourage cells in the dental pulp to heal small holes in mice teeth. 
 
 A biodegradable sponge was soaked in the drug and then put inside the cavity. 
 
 The study, published in Scientific Reports, showed it led to "complete, effective natural repair". 
 
 Teeth have limited regenerative abilities. They can produce a thin band of dentine - the layer just below the enamel - if the inner dental pulp becomes exposed, but this cannot repair a large cavity. 
 
 Normally dentists have to repair tooth decay or caries with a filling made of a metal amalgam or a composite of powdered glass and ceramic. 
 
 These can often need replacing multiple times during someone's lifetime, so the researchers tried to enhance the natural regenerative capacity of teeth to repair larger holes. 
 
 They discovered that a drug called Tideglusib heightened the activity of stem cells in the dental pulp so they could repair 0.13mm holes in the teeth of mice. 
 
 A drug-soaked sponge was placed in the hole and then a protective coating was applied over the top. 
 
 As the sponge broke down it was replaced by dentine, healing the tooth. 
 
 New treatment 
 
 Prof Paul Sharpe, one of the researchers, told the BBC News website: "The sponge is biodegradable, that's the key thing. 
 
 "The space occupied by the sponge becomes full of minerals as the dentine regenerates so you don't have anything in there to fail in the future." 
 
 The team at King's is now investigating whether the approach can repair larger holes. 
 
 Prof Sharpe said a new treatment could be available soon: "I don't think it's massively long term, it's quite low-hanging fruit in regenerative medicine and hopeful in a three-to-five year period this would be commercially available." 
 
 The field of regenerative medicine - which encourages cells to rapidly divide to repair damage - often raises concerns about cancer. 
 
 Tideglusib alters a series of chemical signals in cells, called Wnt, which has been implicated in some tumours. 
 
 However, the drug has already been trialled in patients as a potential dementia therapy. 
 
 "The safety work has been done and at much higher concentrations so hopefully we're on to a winner," said Prof Sharpe. 
 
 This is only the latest approach in repairing teeth - another group at King's believe electricity can be used to strengthen a tooth by forcing minerals into the layer of enamel. 
 
 Minerals such as calcium and phosphate naturally flow in and out of the tooth with acid, produced by bacteria munching on food in the mouth, helping to leach out minerals. 
 
 The group apply a mineral cocktail and then use a small electric current to drive the minerals deep into the tooth. 
 
 They say "Electrically Accelerated and Enhanced Remineralisation" can strengthen the tooth and reduce dental caries. 
 
 Follow James on Twitter. ||||| Need for fillings could be reduced in future as study reveals natural ability of teeth to repair themselves can be enhanced using Alzheimer’s drug 
 
 Dentists have devised a treatment to regenerate rotten teeth that could substantially reduce the need for fillings in the future. 
 
 The therapy works by enhancing the natural ability of teeth to repair themselves through the activation of stem cells in the soft pulp at the centre. 
 
 Normally, this mechanism is limited to repairing small cracks and holes in dentine, the solid bulk of the tooth beneath the surface enamel. Now scientists have shown that the natural process can be enhanced using an Alzheimer’s drug, allowing the tooth’s own cells to rebuild cavities extending from the surface to the root. 
 
 No more fillings as dentists reveal new tooth decay treatment Read more 
 
 Prof Paul Sharpe, who led the work at King’s College London, said: “Almost everyone on the planet has tooth decay at some time – it’s a massive volume of people being treated. We’ve deliberately tried to make something really simple, really quick and really cheap.” 
 
 In the trial, in mice, the team showed that when defects were filled with a biodegradable sponge soaked in the drug, the tooth was gradually able to rebuild itself. 
 
 Restoring the tooth’s original dentine structure is preferable because dental cements used in conventional fillings weaken the tooth, leave it prone to future infections – and inevitably erode or detach. 
 
 In the case of large cavities, the tooth may eventually need to be extracted after undergoing multiple treatments. The new method, which would encourage natural tooth repair, has the potential to eliminate these issues, according to the scientists. 
 
 “The tooth is not just a lump of mineral, it’s got its own physiology. You’re replacing a living tissue with an inert cement,” said Sharpe. “Fillings work fine, but if the tooth can repair itself, surely [that’s] the best way. You’re restoring all the vitality of the tooth.” 
 
 The new treatment would not eliminate the need for the dentist’s drill, however, since decaying sections of the tooth would still need to be removed. “Sorry, you’re still going to have the drill, you can’t get away from that, I’m afraid,” said Sharpe. 
 
 
 
 The therapy relies on a drug called tideglusib, which has been assessed as a potential Alzheimer’s treatment, and which is known to be safe for clinical use. 
 
 Previous work by the team has shown that the drug stimulates stem cells in the centre of the tooth, triggering them to develop into odontoblasts (specialised tooth cells) and boosting the production of dentine, allowing larger defects to be reversed. “We get more of the cells, much quicker and they are more active,” said Sharpe. 
 
 In the study, published in Scientific Reports, the scientists drilled holes into the teeth of mice, inserted a biodegradable collagen sponge soaked in the drug and sealed the tooth with a dental adhesive. 
 
 A quarter of five-year-olds in England have tooth decay, data shows Read more 
 
 When the teeth were examined several weeks later, the sponge had degraded and been replaced with new dentine. Collagen sponges are commercially available and clinically-approved. The dental preparation of the tooth would be almost identical to that required for conventional fillings, according to the scientists. 
 
 A remaining question is whether the method will scale up successfully to human teeth, in which cavities can be significantly larger. The team are currently testing the technique in rats, whose teeth are about four times larger than those of mice, and if this is successful plan to apply later this year to carry out the first clinical trials in patients. 
 
 Ben Scheven, an oral cell biologist at the University of Birmingham, said that preserving the live tooth tissue was increasingly viewed as a priority. “Dentistry is not only about filling and drilling but also about keeping the teeth healthy,” he said. “Especially since it’s an accessible and cheap treatment I can imagine this being used in the clinic.” 
 
 Winnie Wong, a dentist based in Hertfordshire, said: “Clinically speaking, the best material is always natural tooth structure, so I’m sure this method will be encouraged by most dentists.” 
 
 Wong added that the therapy could “cut down on trauma caused by dentists who are slightly overzealous in their caries removal”. “I think it would be welcomed amongst patients, as no one likes going to the dentist to have fillings and injections, no matter how nice we are!” she said.
– A novel therapy holds real promise in changing the way dentists treat your cavities—they'd get the cavities to fill themselves. As the Guardian reports, researchers at King's College London found that they could stimulate stem cells within the teeth to regenerate through a relatively simple approach: They insert a tiny drug-soaked sponge in the cavity. "The sponge is biodegradable, that's the key thing," researcher Paul Sharpe tells the BBC. "The space occupied by the sponge becomes full of minerals as the dentine regenerates so you don't have anything in there to fail in the future." In their study, the drug used was tideglusib, which has been used in clinical trials as a treatment for dementia and Alzheimer's. Having a tooth refill itself naturally is far preferable to the usual treatment of filling the cavity with some kind of amalgam that raises the risk of related problems down the road. "This simple, rapid natural tooth repair process could thus potentially provide a new approach to clinical tooth restoration," write the researchers in Scientific Reports. Also promising is that because the drug already has been proven safe for clinical trials, the turnaround to real-world applications could happen relatively quickly. One caveat: The study was on mice, and researchers can't say for sure yet whether they'd get the same results in larger, human cavities. (The main reason people avoid the dentist isn't fear.)