title: High strength re-mineralizing, antibacterial dental composites with reactive calcium phosphates.
abstract: OBJECTIVE
  Development of high strength dental composites with adhesive, antibacterial and re-mineralizing potential.
  
  
  METHODS
  Urethane and triethylene glycol dimethacrylates were combined with HEMA (10 or 20wt%) and 2MP (2 or 10wt%), antibacterial chlorhexidine (2.5wt%) and chemical cure initiators. Reactive mono/tri calcium phosphate (CP) mixed with silica/silicon carbide nanoparticles (S) (CP:S weight ratio 1:2 or 2:1) was added (50wt%).
  
  
  RESULTS
  Decreasing CP/S ratio and HEMA content reduced monomer conversion at 15min from 93 to 63%. Conversely, decreasing CP/S increased initial "dry" compressive (137-203MPa) and flexural (79-116MPa) strength. With high HEMA content, these decreased by ∼15-20MPa upon 24h water storage. With low HEMA content, average decline was <8MPa due to reduced water sorption. Early water sorption induced mass increase, volume expansion, mono calcium phosphate dissolution and chlorhexidine release, were proportional to the initial calcium phosphate content. Furthermore, they increased ∼1.5 fold upon raising HEMA wt%. These diffusion controlled processes and strength decline slowed after 24h as phosphates reaction bound water within the materials. Increasing 2MP concentration reduced calcium release but did not affect strength. Formulations with high CP/S indicated greater antibacterial activity in agar diffusion and in vitro biofilm tests.
  
  
  CONCLUSIONS
  New material use beneath a conventional composite could potentially reduce high failure rates associated with residual caries and bacterial microleakage.
authors: UCL Eastman Dental Institute, 256 Gray's Inn Road, London, UK.
authors: Idris M
authors: IM
authors: Mehdawi
authors: Jonathan
authors: J
authors: Pratten
authors: David A
authors: DA
authors: Spratt
authors: Jonathan C
authors: JC
authors: Knowles
authors: Anne M
authors: AM
authors: Young
mesh_terms: D000190:Actinomyces / Q000187:drug effects; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D002130:Calcium Phosphates / Q000737:chemistry* / Q000494:pharmacology; D017554:Carbon Compounds, Inorganic / Q000737:chemistry*; D002478:Cells, Cultured; D002710:Chlorhexidine / Q000737:chemistry* / Q000494:pharmacology; D003188:Composite Resins / Q000138:chemical synthesis* / Q000494:pharmacology; D019245:Compressive Strength; D007780:Lacticaseibacillus casei / Q000187:drug effects; D008689:Methacrylates / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013295:Streptococcus mutans / Q000187:drug effects; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D002130:Calcium Phosphates; D017554:Carbon Compounds, Inorganic; D003188:Composite Resins; D008689:Methacrylates; D017655:Silicon Compounds; D002710:Chlorhexidine; C022088:silicon carbide