J Curr Surg

Journal of Current Surgery, ISSN 1927-1298 print, 1927-1301 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Curr Surg and Elmer Press Inc

Journal website http://www.currentsurgery.org

Original Article

Volume 3, Number 2, October 2013, pages 73-81

Influence of Root Posts and Retained Coronal Dentin on Fracture Resistance and Failure Pattern of Endodontically Treated Maxillary Incisors

Figures

Figure 1. A mounted specimen positioned at 135° angle in a custom made holding grip used in the universal testing machine (MTS 858; MTS Systems Corp., Eden Prairie, MN, USA) employed for fracture resistance testing (From Amin et. al. JMMS; vol.(9):343-352, 2013).

Figure 2. Significance of root posts to fracture resistance of restored endodontically treated maxillary incisors. Different alphabets (inserts) denote statistically significant difference at 99% confidence level.

Figure 3. Reparable/irreparable failure mode fraction of the endodontically treated maxillary incisors restored with metal and fiber root post systems.

Figure 4. Radiographs of a sample of endodontically treated teeth demonstrating various modes of failure after being subjected to fracture resistance test. (A) a metal post restored specimen with a full-ring coronal dentin ferrule showing an irreparable middle third root fracture; (B) a metal post restored specimen showing fragmented core without post fracture; (C) a fiber post restored specimen showing core debonding without post fracture; (D) a fiber post restored tooth displaying root/post adhesive failure; (E) a fiber post restored tooth demonstrating a crown-core-post complex fracture with cracks extending above the assumed bone level; (F) a fiber post restored tooth exhibiting an irreparable crown-core-post complex fracture with a palato-labial oblique crack running below the simulated bone level.

Tables

**Table 1.** Thickness of Root Dentin (mm) After Preparing Post Space
Prepared tooth specimens for restoration with the following post systems	Thickness of root dentin (mm) after preparing post space
	Mean (n=20)	St dev.	Lowest dentin thickness	Highest dentin thickness
Metal posts	1.26	(±) 0.22	0.98	1.51
Fiber posts	1.23	(±) 0.26	0.69	1.07

**Table 2.** Force to Failure of Endodontically Treated Root-Post Restored Maxillary Incisors
Crown ferrule orientation	Force (N) to failure (mean ± St dev.) (n=10)
	Root post system
	Metal	Fiber	Control
Note: Different alphabets denote significant differences at 99% confidence level.
Ring ferrule	374 (±163)^A	310 (±49)^A	257.5 (±96)^A
No ferrule	76 (±60)^B	80 (±43)^B	54 (±57)^B

**Table 3.** Group Mean Differences. When the Obtained Tukey’s “T” Value of 176 was Smaller Than the Difference Between Two Means, the Means Would Be Significantly Different
Post system	Means (n=10) (N)	Comparison mean differences
Post system	Means (n=10) (N)	M2	M3	M4	M5	M6
** denotes significant difference P < 0.01. NS indicates not significant difference.
Ring ferrule metal post	M1 = 374	M1-M2= 298**	M1-M3= 64^NS	M1-M4= 294**	M1-M5= 116.5^NS	M1-M6= 320**
No ferrule metal post	M2 = 76		M3-M2= 234**	M4-M2= 4^NS	M5-M2= 181.5**	M2-M6= 22^NS
Ring ferrule fiber post	M3 = 310			M3-M4= 230**	M3-M5= 52.5^NS	M3-M6= 256**
No ferrule fiber post	M4 = 80				M5-M4= 177.5**	M4-M6=26^NS
Ring ferrule no post	M5 = 257.5					M5-M6= 203.5**
No ferrule no post	M6 = 54