title: Effect of flavonoids on the mechanical properties of demineralised dentine.
abstract: OBJECTIVE
  This study compared the effect of three flavonoids: proanthocyanidin, naringin and quercetin on the modulus of elasticity (MOE) and ultimate tensile strength (UTS) of demineralised dentine.
  
  
  METHODS
  Thirty teeth were sectioned into 0.5mm×1.7mm×7mm beams for MOE measurement. Another 30 non-carious molars were sectioned into 0.5mm×0.5mm thick dentine beams for UTS testing. Demineralised specimens were divided into three groups according to treatments: 6.5% proanthocyanidin, 6.5% quercetin and 6.5% naringin. Specimens were kept in their respective solutions and tested at baseline, 10min, 30min, 1h and 4h. The MOE of each specimen was determined using a three-point bending test at a crosshead speed of 0.5mm/min. For UTS evaluation, each specimen was tested in tension until failure using a crosshead speed of 1mm/min. Means and standard deviation were calculated. Two-way ANOVA and Tukey test were used to evaluate the effect of flavonoid treatment and treatment duration on MOE and UTS.
  
  
  RESULTS
  Both MOE and UTS were significantly affected by flavonoid treatment (p<0.001) and treatment duration (p<0.001). Interaction of the two factors was significant for MOE (p<0.001), but not for UTS (p>0.05). Flavonoid treatment improved the mechanical properties of demineralised dentine in the order: proanthocyanidin>quercetin>naringin. It took a longer time for the flavonoids to produce a significant change in UTS, when compared to MOE.
  
  
  CONCLUSIONS
  Proanthocyanidin was more effective than quercetin and naringin in improving biomechanical properties of dentine matrix, thereby enhancing preventive and reparative dental therapies.
  
  
  CONCLUSIONS
  Despite its larger molecular size, proanthocyanidin was more effective than quercetin and naringin, in enhancing the biomechanical properties of demineralised dentine.
authors.affiliation: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Pokfulam, Hong Kong, China.
authors.forename: D J
authors.initials: DJ
authors.lastname: Epasinghe
authors.affiliation: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Pokfulam, Hong Kong, China. Electronic address: ckyyiu@hkucc.hku.hk.
authors.forename: C K Y
authors.initials: CK
authors.lastname: Yiu
authors.affiliation: Oral Diagnosis and Polyclinics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Pokfulam, Hong Kong, China.
authors.forename: M F
authors.initials: MF
authors.lastname: Burrow
authors.affiliation: Oral Rehabilitation, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Pokfulam, Hong Kong, China.
authors.forename: J K H
authors.initials: JK
authors.lastname: Tsoi
authors.affiliation: Department of Endodontics, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA.
authors.forename: F R
authors.initials: FR
authors.lastname: Tay
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D001696:Biomechanical Phenomena; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000187:drug effects* / Q000473:pathology; D055119:Elastic Modulus; D044950:Flavanones / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D044945:Proanthocyanidins / Q000494:pharmacology; D011794:Quercetin / Q000494:pharmacology; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors; D017001:Tooth Demineralization / Q000473:pathology / Q000503:physiopathology*
chemical_list: D000975:Antioxidants; D044950:Flavanones; D005419:Flavonoids; D044945:Proanthocyanidins; C013221:proanthocyanidin; D011794:Quercetin; C005274:naringin
keywords: Flavonoids; Modulus of elasticity; Ultimate tensile strength