title: Comparison of fracture resistance and failure pattern of endodontically treated premolars with different esthetic onlay systems: An in vitro study.
abstract: OBJECTIVE
  To compare the fracture resistance and modes of failures of three different aesthetic MOD onlays on endodontically treated premolars.
  
  
  METHODS
  Forty sound maxillary premolars were selected of which 10 untreated teeth were taken as control (Group I). The other thirty premolars were subjected to standardized MOD onlay preparations and root canal treatments and divided into 3 equal groups. Onlays were prepared in Group II- Indirect composite, Group III- Lithium Disilicate ceramic and Group IV- Full Zirconia. All onlays were cemented using Multilink Automix. All the 40 samples were subjected to fracture resistance testing on Universal testing machine. Also fractured specimens were observed under stereo-microscope for modes of failure.
  
  
  RESULTS
  Group IV presented the highest fracture resistance. Groups II and III presented no significant difference in fracture resistance from each other (P > 0.05). Group II and Group III showed significantly lower fracture resistance values than Group I. Coming to modes of failure, only Group IV had showed no cracks in any of the restorations.
  
  
  CONCLUSIONS
  Full Zirconia MOD onlays increased the fracture resistance of endodontically treated premolars to a significantly higher level than the sound teeth.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinoutapalli, Andhra Pradesh, India.
authors.forename: Praffulla
authors.initials: P
authors.lastname: Mynampati
authors.affiliation: Department of Conservative Dentistry and Endodontics, Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinoutapalli, Andhra Pradesh, India.
authors.forename: Mandava Ramesh
authors.initials: MR
authors.lastname: Babu
authors.affiliation: Department of Conservative Dentistry and Endodontics, Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinoutapalli, Andhra Pradesh, India.
authors.forename: Devabhaktuni Disha
authors.initials: DD
authors.lastname: Saraswathi
authors.affiliation: Department of Conservative Dentistry and Endodontics, Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinoutapalli, Andhra Pradesh, India.
authors.forename: Janga Ravi
authors.initials: JR
authors.lastname: Kumar
authors.affiliation: Department of Conservative Dentistry and Endodontics, Drs Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinoutapalli, Andhra Pradesh, India.
authors.forename: Leneena
authors.initials: L
authors.lastname: Gudugunta
authors.affiliation: Department of Pedodontics and Preventive Dentistry, Mamata Dental College, Khammam, Telangana, India.
authors.forename: Divya
authors.initials: D
authors.lastname: Gaddam
keywords: CAD/CAM onlays; Indirect composite onlay; Lithium disilicate onlay; Zirconia onlay
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