title: Effect of Diode Laser on Bacteria Beyond the Apex in Relation to the Size of the Apical Preparation - An In-Vitro Study.
abstract: BACKGROUND
  Microorganisms causing periapical infection are usually difficult to eradicate after conventional endodontic treatment or even in retreatment resulting in poor outcomes. So the purpose of the study was to assess whether disinfection of root canal with laser had any effect on bacteria in the periapex region.
  
  
  OBJECTIVE
  The aim of the present study was to evaluate the effects of a diode laser when activated in root canals with varying apical diameters, on the bacteria present beyond the apex of the teeth.
  
  
  METHODS
  Total 30 intact single rooted teeth were taken and decoronated to standardize the root to a length of 12mm. They were divided into three groups depending on last file size used for instrumentation at apex i.e., size 30, 40 and 50 respectively. The samples were then mounted on test tubes such that roots of teeth were in contact with fresh broth of Escherichia coli (ATCC 25922) and left for incubation. Later a diode laser (Ezlase 940, Biolase) was used for disinfection of root canals of the samples. Following this the bacterial inoculums from each test tube were cultured and CFU were obtained from which the mean log values were obtained. Statistical analysis was done using Kruskal Wallis ANOVA test to compare mean CFU in three groups. Mann-Whitney U test with Bonferroni correction was used to compare inter-group differences.
  
  
  RESULTS
  There was statistically significant difference in mean log values of CFU in all the three study groups. Inter-group comparisons showed that, Group A had significantly lower mean CFUs than Group B and C respectively.
  
  
  CONCLUSIONS
  The study showed that intracanal irradiation with diode laser had an effect on the bacteria present beyond the apex, and it was influenced by the size of the apical preparation i.e., smaller apical size led to a greater reduction in the bacterial count.
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry and Endodontics, Sri Sai College of Dental Surgery , Vikarabad, India .
authors.forename: Sistla Venkata
authors.initials: SV
authors.lastname: Jyotsna
authors.affiliation: Professor and Head, Department of Conservative Dentistry and Endodontics, Sri Balaji Dental College , Moinabad, India .
authors.forename: Raja Vatsavai Chakradhar
authors.initials: RV
authors.lastname: Raju
authors.affiliation: Professor and Head, Department of Conservative Dentistry and Endodontics, PMNM Dental College , Bagalkot, India .
authors.forename: Jaya Prakash
authors.initials: JP
authors.lastname: Patil
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry and Endodontics, Sri Sai College of Dental Surgery , Vikarabad, India .
authors.forename: Thakur Veerandar
authors.initials: TV
authors.lastname: Singh
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry and Endodontics, Sri Sai College of Dental Surgery , Vikarabad, India .
authors.forename: Neha
authors.initials: N
authors.lastname: Bhutani
authors.affiliation: Professor, Department of Conservative Dentistry and Endodontics, Sri Sai College of Dental Surgery , Vikarabad, India .
authors.forename: Shekar
authors.initials: S
authors.lastname: Kamishetty
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry and Endodontics, Sri Sai College of Dental Surgery , Vikarabad, India .
authors.forename: Kiran
authors.initials: K
authors.lastname: Ghatole
keywords: Apical diameter; Apical periodontitis; Escherichia coli; Root canal disinfection