title: In vitro Comparison of Impact of Different Bleaching Agents on the Microhardness of Enamel.
abstract: BACKGROUND
  Various agents are used these days for increasing the esthetics. One such procedure is bleaching that offers various advantages, as it is minimal invasive and cheap option to color the teeth and remove stain. The altered enamel after the bleaching process shows surface demineralization and porosities. The present study aimed to evaluate the effect of different bleaching agents on the microhardness of enamel.
  
  
  METHODS
  A total of 100 freshly human extracted maxillary premolar teeth were selected for the study. Teeth with sound tooth structure were included for the study. All the specimens were randomly divided into four groups with 25 specimens in each group depending upon the type of bleaching agent used: Group A, artificial saliva (Control group); Group B, 35% hydrogen peroxide (HP); Group C, 25% HP; Group D, 10% carbamide peroxide (CP). Knoop Hardness Number (KHN) was calculated at 24, 48-hour, and 7-week interval.
  
  
  RESULTS
  Results showed no statistical significant differences between the microhardness of enamel of different groups (p < 0.005). A slight fall in the value of KHN was seen in all the groups, except for the control group, although the results were statistically nonsignificant (p > 0.005).
  
  
  CONCLUSIONS
  Although nonsignificantly, all the bleaching solutions produced some amount of alterations in the microstructure of enamel. More studies with higher study groups and more advanced estimation technologies are required to minimize microstructure alterations and promote for better outcome of bleaching procedures.
authors.affiliation: Senior Lecturer, Department of Conservative Dentistry and Endodontics, Index Institute of Dental Sciences, Index City, Nemawar Road, Indore 452016, Madhya Pradesh, India, Phone: +919501544877 e-mail: subhrad@gmail.com.
authors.forename: Subhra
authors.initials: S
authors.lastname: Dey
authors.affiliation: Department of Conservative Dentistry and Endodontics Faculty of Dental Sciences, Rama University, Kanpur, Uttar Pradesh, India.
authors.forename: Vinisha
authors.initials: V
authors.lastname: Pandey
authors.affiliation: Department of Oral and Maxillofacial Surgery, Bhagwan Mahavir Medical Superspeciality Hospital, Ranchi, Jharkhand India.
authors.forename: Anuj
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Pedodontics and Preventive Dentistry, School of Dental Sciences, Sharda University, Greater Noida, Uttar Pradesh, India.
authors.forename: Neha
authors.initials: N
authors.lastname: Awasthi
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics Hazaribag College of Dental Sciences and Hospital, Hazaribag Jharkhand, India.
authors.forename: Anshu
authors.initials: A
authors.lastname: Sahu
authors.affiliation: Department of Conservative Dentistry and Endodontics, PDU Dental College, Solapur, Maharashtra, India.
authors.forename: Sudarshan C
authors.initials: SC
authors.lastname: Pujari
mesh_terms: D003743:Dental Enamel / Q000187:drug effects*; D006244:Hardness / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D058205:Tooth Bleaching Agents / Q000494:pharmacology*
chemical_list: D058205:Tooth Bleaching Agents
keywords: Bleaching; Enamel; Microhardness.