title: Evaluation of Flexural Strength of Thermocycled Interim Resin Materials Used in Prosthetic Rehabilitation- An In-vitro Study.
abstract: BACKGROUND
  Provisional restoration is an analytical component of fixed prosthodontics serving as a ground plan for the design of fixed dental prosthesis. Flexural strength is critical in case of long standing fixed dental prosthesis, to appreciate success of full mouth rehabilitation cases and temporomandibular joint dysfunction therapies.
  
  
  OBJECTIVE
  The present study was to evaluate the flexural strength of different provisional restorative resins used for prosthetic rehabilitation.
  
  
  METHODS
  Forty identical samples (n=10 for each material) measuring 25mm×2mm×2mm according to ADA/ANSI specification no. 27 were fabricated using autopolymerizing Poly Methyl Methacrylate (PMMA) (Group A); heat activated PMMA (Group B); autopolymerizing Bis-GMA composite resin (Group C) and light activated Urethane Dimethacrylate Resin (UDMA) (Group D). For 14 days all these samples were stored in artificial saliva. Ten samples from each material were subjected to thermal cycling for 2500 cycles (5°C to 55°C). Later, a standard three point bending test was conducted on all the specimens with a universal testing machine at a crosshead speed of 0.75mm/min. Statistical analysis used included Kruskal-Wallis and Mann-Whitney U test.
  
  
  RESULTS
  The mean flexural strength of specimens confirmed higher flexural strength for Group C (102.98 Mpa) followed by Group B (91.86 Mpa), Group A (79.13 Mpa) and Group D (60.01 Mpa). There were significant differences between any two materials tested (p <0.05). Comparison between mean flexural strength values between four groups revealed significant difference between the interim materials (p <0.05).
  
  
  CONCLUSIONS
  The greatest flexural strength was observed for Bis-GMA composite resins followed by heat cure methacrylate resins, autopolymerizing methacrylate resins and was least for light cure resins. While fabricating provisional restorations, these greater values should be considered for better outcome of the treatment.
authors: Professor, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Krishna Kishore
authors: KK
authors: Kadiyala
authors: Postgraduate Student, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Mohan Krishna
authors: MK
authors: Badisa
authors: Professor, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Gopinadh
authors: G
authors: Anne
authors: Reader, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Sampath Chowdary
authors: SC
authors: Anche
authors: Professor, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Sandeep
authors: S
authors: Chiramana
authors: Reader, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Suresh Babu
authors: SB
authors: Muvva
authors: Senior Lecturer, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Srujana
authors: S
authors: Zakkula
authors: Senior Lecturer, Department of Prosthodontics, Sibar Institute of Dental Sciences , Guntur, Andhra Pradesh, India .
authors: Ravi Rakesh Dev
authors: RR
authors: Jyothula
keywords: Bis-acrylic composite resin; Flexural strength; Polymethyl methacrylate resin; Urethane dimethacrylate resin