TY - JOUR ID - 43629 TI - The Effects of New Design of Access Hole on Porcelain Fracture Resistance of Implant-Supported Crowns JO - Journal of Dentistry JA - DENTJODS LA - en SN - 2345-6485 AU - Derafshi, Reza AU - Farzin, Mitra AU - Taghva, Masumeh AU - Heidary, Hosein AU - Atashkar, Berivan AD - Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. AD - Postgraduate Student of Prosthodontics, Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shi-raz, Iran. AD - Postgraduate Student of Prosthodontics, Dept. of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. Y1 - 2015 PY - 2015 VL - 16 IS - Spring 2015- 16 (Supplement) SP - 61 EP - 67 DO - N2 - Statement of the Problem: One disadvantage of cement-retained crowns is the lack of predictable irretrievability. This problem can be overcome through designing a screw access hole in the metal substructure of cement-retained restoration and using porcelain stain to define this area.Purpose: This study aimed to evaluate the influence of existence of screw access hole on porcelain fracture resistance of metal-ceramic implant-supported crowns.Materials and Method: Thirty six standardized metal-ceramic crowns were fabricated and divided into 3 groups (n=12); group 1 conventional cement-retained metal-ceramic crowns as control group, group 2 cement-retained MC crowns in which porcelain stain was used to define the location of screw access channel, and group 3 cement-retained metal-ceramic crowns in the metal substructure of which a hole and ledge was designed in the location of screw access channel. The specimens were cemented (TempBond, Kerr) to their dedicated abutments. A hole was made in the location of screw access channel in group 2 and 3 and filled with photo-polymerized composite resin (3M; ESPE). All specimens were thermocycled and loaded in universal testing machine at crosshead speed of 2mm/min until fracture. Mean values of load at fracture were calculated in each group and compared with One-way ANOVA (α=0.05).Results: Mean value of the load required to fracture the restorations was 1947±487 N in group 1, 1927±539 N in group 2, and 2170±738 N in group 3. No statistically significant difference was found between the fracture resistance values of the three groups (p> 0.05)Conclusion: Presence of screw access channel in cement-retained implant restorations does not compromise fracture resistance. UR - https://dentjods.sums.ac.ir/article_43629.html L1 - https://dentjods.sums.ac.ir/article_43629_963c9648cd7c68b98bda446910d77847.pdf ER -