ENDODONTIC SOLUTIONS VOLUME 1 ISSUE 2 E N D O I N VI VO FEBRUARY 2013 Evaluation of the Flexural Strength of Carbon Fiber-, Quartz Fiber-, and Glass Fiber-Based Posts Graziela A´ vila Galhano, DDS, Luiz Felipe Valandro, DDS, MSc,Renata Marques de Melo, MD, DDS, Roberto Scotti, MD, DDS, and Marco Antonio Bottino, DDS, PhDSPECIAL POINTSOF INTEREST: Abstract: This study investigated the flex- fiber post (Bisco) were statistically similar Flexural strength of ural strength of eight fiber posts (one car- and higher than the mean values of the other various fibre post bon fiber, one carbon/quartz fiber, one groups. The mean values of the groups C- systems opaque quartz fiber, two translucent quartz POST—carbon fiberpost (Bisco), LIGHT-POST— fiber,and three glass fiber posts). Eighty translucent quartz fiber post (Bisco), D.T. Rigid versus Flexible Dentin-like Endodontic fiber posts were used and divided into eight LIGHT-POST—double tapered translucent Posts groups (n=10): G1:C-POST (Bisco); G2: quartz fiber post (Bisco), PARAPOST WHITE— ÆSTHETI-POST (Bisco); G3: ÆSTHETI-PLUS glass fiber post (Coltene) and FIBREKOR—- Vertical root fractures in upper premolars (Bisco); G4: LIGHT-POST (Bisco); G5: D.T. glass fiber post (Pentron) were similar and with endodontic posts LIGHT-POST (Bisco); G6: PARAPOST WHITE higher than the group REFORPOST—glass (Coltene);G7: FIBERKOR (Pentron); G8: RE- fiber post (Angelus). Self-etching adhesives increase colla- FORPOST (Angelus). All of the samples Considering this evidence, the type of resinous genolytic activity in were tested using the three-point bending matrix and the fabrication process used to pro- radicular dentin test. The averages obtained were submit- mote chemical bonding between fiber and resin A simple etching tech- ted to the ANOVA and to Tukey’s test may possibly be the most important factors for the nique for improving (p<0.05). The mean values (MPa) of the fiber post strength. Much of this information is the retention of fiber groups ÆSTHETI-POST—carbon/quartz fiber kept under industrial secret unfortunately; how- posts to resin compos- post (Bisco) and ÆSTHETI-PLUS—quartz ever, it is reasonable to ask sales representatives. ites Geometric factors Rigid versus Flexible Dentine-like Endodontic Posts—Clinical Testing affecting dentin bond- of a Biomechanical Concept: Seven-year Results of a Randomized ing in root canals: Controlled Clinical Pilot Trial on Endodontically Treated Abutment A theoretical modeling Teeth with Severe Hard Tissue Loss approach Guido Sterzenbach, Dr med dent, DDS, Alexandra Franke, DDS,and Michael Naumann, Prof, Dr med dent, DDS Abstract Introduction: This is the first clinical ing cavity walls were randomly assigned to long-term pilot study that tested the biomi- receive either a tapered TP (n = 46) or a ta- metic concept of using more flexible, dentine- pered GFREP(n = 45). The posts were adhe- like (low Young modulus) glass fiber– sively luted using selfadhesive resin cement. reinforced epoxy resin posts (GFREPs) com- The composite core build-ups were prepared pared with rather rigid, stiff (higher Young ensuring a circumferential 2-mm ferrule. The modulus) titanium posts (TPs) in order to im- primary endpoint was a loss of restoration for prove the survival rate of severely damaged any reason. To study group differences, the endodontically treated teeth. Methods: log-rank test was calculated (P < .05). Hazard Ninety-one subjects in need of postendodon- plots were constructed. Results: After 84 tic restorations in teeth with 2 or less remain- months of observation (mean = 71.2 months),
ENDO IN VIVO Page 2Rigid Versus Flexible Dentine-like Endodontic Posts (cont’d) 7 restorations failed (ie, 4 Conclusions: When using GFREPs and 3 TPs). The self-adhesive luted prefab- failure modes were as fol- ricated posts in severely lows: GFREP:- root fracture destroyed abutment teeth (n = 3), core fracture (n = 1) with 2 or less cavity walls and TP:endodontic failure and a 2-mm ferrule, pos- (n = 3). No statistical differ- tendodontic restorations ence was found between achieved high long-term the survival rates (GFREPs survival rates irrespective = 90.2%, TPs = 93.5%, P of the post material used = .642). The probability of (ie, glass fiber vs tita- no failure was comparable nium). for both post materials (risk ratio; 95% confidence inter- val, 0.965–0.851/1.095).Vertical Root Fracture in Upper Premolars withEndodontic Posts: Finite Element AnalysisAndrea F.V. Santos, Carina B. Tanaka, Raul G. Lima, PhD, Camila O.M. Espósito, et al JOE — Volume 35, Number 1, January 2009Abstract: Upper premolars re- than for the bonded or intactstored with endodontic posts models, therefore confirming thepresent a high incidence of verti- second hypothesis.cal root fracture (VRF). Two hy-potheses were tested: (1) thesmaller mesiodistal diameterfavors stress concentration inthe root and (2) the lack of aneffective bonding between rootand post increases the risk ofVRF. Using finite element analy-sis, maximum principal stresswas analyzed in 3-dimensionalintact upper second premolarmodels. From the intact models,new models were built includingendodontic posts of differentelastic modulus (E =37 or E=200 GPa) with circular or ovalcross-section,either bonded ornonbonded to circular or oval (A) A three-dimensional model of the intact tooth andcross section root canals. rootcanals. The first hypothesis was (B) a three-dimensional model with endodontic post.partially confirmed because the Dimensions are in millimeters. E, elastic modulus; v,conditions involving nonbonded, Poisson’s ratio.low-modulus posts showedlower tensile stress for oval ca-nals compared to circular ca-nals. Tensile stress peaks forthe nonbonded models wereapproximately three time higher
VOLUME 1 ISSUE 2 Page 3Self-Etching Adhesives Increase Collagenolytic Activity inRadicular DentinFranklin R. Tay, David H. Pashley, Robert J. Loushine, R. Norman Weller, et al JOE—Volume 32,Number 9, September 2006Abstract: Endogenous matrix metalloproteinases (MMPs) release from crown dentin andtheir activation results in degradation of hybrid layers created by dentin adhesives. Thisstudy tested the hypothesis that instrumented intraradicular dentin possesses latent colla-genolytic activity that is activated by mild self-etching adhesives. Root dentin shavings chlor-hexidine for 10 minutes before or after adhesive application. Collagenolytic activities of thenine groups were assayed with a fluorometer in 96-well plates, by recording the changes influorescence before and after addition of fluorescein-labeled type I collagen. Epoxy resin- Sealer penetration demonstratedembedded powders were examined with TEM for the extent of demineralization. Instru- by confocal photographymented, mineralized intraradicular dentin possessed low but detectable collagenolytic activ-ity that was inhibited by chlorhexidine (p <0.001) and EDTA (p<0.001). Both adhesives par-tially demineralized the dentin powder and activated latent MMPs, with 14- to 15-fold in-creases in collagenolytic activities (p<0.001) that were significantly (p<0.001)but incom-pletely inactivated after 10 min application of chlorhexidine. Mild self-etching adhesivesactivate latent MMPs without denaturing these enzymes, and may adversely affect the lon-gevity of bonded root canal fillings and posts. Much of the fractureA Simple Etching Technique for Improving the Retention of FiberPosts to Resin Composites susceptibility, however, is intrinsic to the root andFrancesca Monticelli, DDS, MSc, Manuel Toledano, MD, DDS, PhD, Franklin R. Tay, DDS, MSc, PhD, canal morphology (dentinFernanda T. Sadek, BDSc (Hons), PhD, et al JOE—Volume 32, Number 1, January 2006 thickness, canal shape and size, external root shape) Abstract: Coupling of fiber posts to composites is hampered byabsence of chemi- and is beyond the cal union between epoxy resins and methacrylate-based resins. This study exam- influence of the clinician. ined a clinically feasible protocol for creating micromechanical retention on the surface of fiber posts, using hydrogen peroxide etching to remove the surface layer of epoxyresin. This was followed by silanization of the exposed quartz fibers to enhance their chemical bonding to composites. Etching with 24% H2O2 for 10 min or 10% H2O2 for 20 min produced a 50 µm thick surface zone that is de- pleted of epoxy resin, leaving intact, undamagedquartz fibers for silanization. Low viscosity flowable composites were employed to infiltrate this zone, to simu- late the creation of hybrid layers in acid-etched dentin by dentin adhesives. Inter- facial strengths were enhanced with the adjunctive use of H2O2 etching and si- lanization, and were probably dependent on the ability of the flowable compos- ites to completely infiltrate this interdiffusion zone.
www.endosolns.com ENDODONTIC SOLUTIONS 4310 Sherwoodtowne Blvd., Suite 300 Mississauga, ON L4Z4C4 Phone - 905.270.3357 Fax - 905.270.4172 Email - firstname.lastname@example.org P A T I E N C E , P E R S I S T E N C E , P E R S E V E R A N C EGEOMETRIC FACTORS AFFECTING DENTIN BONDING IN ROOT CANALS:A THEORETICAL MODELING APPROACHFranklin R. Tay, BDSc (Hons), PhD, Robert J. Loushine, DDS, Paul Lambrechts, DDS, PhD,R. Norman Weller, DMD, MS, David H. Pashley, DMD, PhD JOE—Volume 31, Number 8, August 2005Abstract: Cavity configuration factor (C-factor) is the ratio of the bonded surface area in a cavity to the unbondedsurface area. In a box-like class I cavity, there may be five times more bonded surface area than the unbonded sur-face area. During polymerization, the volume of monomers is reduced, which creates sufficient shrinkage stressesto debond the material from dentin, thereby decreasing retention and increasing leakage. The important variablesinfluencing bonding adhesive root-filling materials to canals was examined using a truncated inverted cone model.C-factors in bonded root canals exhibit a negative correlation with sealer thickness. For a 20 mm-long canal pre-pared with a size 25 file, calculated C-factors ranged from 46 to 23,461 with decreasing sealer thickness (500–1µm), comparedto a C-factor of 32 when the canal was filled only with sealer. As the thickness of the adhesive isreduced, the volumetric shrinkage is reduced, which results in a reduction in shrinkage stress (S-factor). C-factorsabove 954 calculated with sealer thickness smaller than 25 µm are partially compensated by increases in bondingarea and decreases in shrinkage volume. However, the interaction of these two geometrically related factors (C-and S-factors) predicts that bonding of adhesive root-filling materials to root canals is highly unfavorable whencompared with indirect intracoronal restorations with a similar resin film thickness.