American Journal of Dentistry
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Abstracts of the June 2007 Issue


Effect of LED light-curing time for the adhesive resin

on the modulus of elasticity


Pisol Senawongse, dds, msc, phd, Choltacha Harnirattisai, dds, phd, Masayuki Otsuki, dds, phd

& Junji Tagami, dds, phd

Abstract: Purpose: To evaluate the elastic modulus of successive layers where an adhesive resin was cured by different light-curing times. Methods: Eighty dentin discs which were 2 mm thick were prepared from 40 sound third molars. The dentin discs were further divided into four groups and bonded with 3M Single Bond 2 and cured with an LED for 5, 10, 15 and 20s. Bonded specimens were restored with a microhybrid resin composite. Specimens were cut perpendicular to the resin dentin interface, embedded in epoxy resin, and polished. Polished specimens were evaluated for the elastic modulus at the layer of dentin, hybrid layer, adhesive resin, and resin composite at 24 hours after preparation. Results: Light-curing times influenced the elastic modulus of hybrid layer and adhesive resin. The significant differences of elastic modulus among successive layers were found. The results suggested that extension of light-curing times of adhesive resin from 5 to 20 seconds increased the mechanical properties of the resin dentin interface. (Am J Dent 2007;20:139-141).

Clinical significance: Extending the light-curing time of adhesive resin from 5 to 15 seconds increased the modulus of elasticity of hybrid layer and adhesive layer at resin-dentin interfaces that might have a benefit on the durability of adhesive restorations.

: Dr. Pisol Senawongse, Department of Operative Dentistry, Faculty of Dentistry, Mahidol University, 6 Yothi Street, Phayathai, Bangkok, 10400, Thailand. E-:


Spectrophotometric and visual shade measurements of human teeth using three shade guides

Gabriele Fani, dds, Alessandro Vichi, dds, phd & Carel L. Davidson, md, phd

Abstract: Purpose: To compare spectrophotometric vs. visual color identification of tooth shade on the basis of three different commercially available shade guides. Methods: On 54 subjects, two operators (with >10 years experience) independently selected the best match of the middle third of one of the patient’s upper central incisors, using consecutively three shade guides (Vita Lumin Vacuum, Chromascop, Vita 3D Master). After each individual shade match, the same operator performed a shade measurement with a SpectroShade spectrophotometer. Results: The Vita Lumin shade guide appeared to provide the most consistent results between human and spectrophotometrical evaluation, although Vita 3D Master offered a greater variety of colors. In approximately 47% of the cases, the spectrophotometer provided more accurate results than visual selection. From a clinical point of view, this is a noteworthy improvement in the complex process of color match for indirect restoration. (Am J Dent 2007:20:142-146).

Clinical significance: Spectrophotometric shade selection correlated closely with visual shade selection, in particular with regard to the Value (L) dimension of color.

: Dr. Gabriele Fani, Viale Edmondo De Amicis, 25, 50127 Firenze, Italy. E-:


The effects of two monofunctional diluent monomers and two photoinitiator systems on the properties of UDMA-based composites

Nicola D. Richards, dds, phd & Joseph M. Antonucci, phd

Abstract: Purpose: To compare the effects of two types of monofunctional co-monomers and two types of photoinitiator systems on the properties of urethane dimethacrylate (UDMA) based dental restorative composites. Methods: The resin blends consisted of UDMA and a diluent co-monomer at a molar ratio of 9:1. The diluent comonomers were neo-decyl vinyl ester (Neo 10) or n-hexyl methacrylate (HMA). The photoinitiator system consisted of a bis-acyl phosphine oxide (BAPO) or camphorquinone plus ethyl 4-(dimethylamino)benzoate (CQ/4E). Each initiator system was utilized at 1% or 2% by mass of the resin blend. These resin blends were mixed by hand with silanized zirconia glass (85.7% by mass) to make the various composites. Flexural strength (FS) specimens, made from these pastes by visible light photopolymerization, were tested to failure after 24 hours water storage. Mercury dilatometry was used to evaluate the shrinkage, and the degree of double bond conversion was evaluated using near infrared spectroscopy (NIR). The first hypothesis tested was that use of Neo 10 in a UDMA composite would not have an effect on properties compared to the methacrylate HMA. The second hypothesis tested was that the BAPO initiator would not have an effect on the properties of a UDMA-based composite compared to the CQ/4E initiator. Results: The hypotheses were tested at α= 0.05 and β= 0.20. The major finding was that the lower level (1% by mass) of BAPO resulted in lower FS, lower conversion and lower shrinkage (rejecting the hypothesis that there was no difference due to initiator used) than composites formulated with the higher level of this initiator or either level of the CQ/4E initiator system, regardless of the comonomer used. The effects of two comonomers used were not differentiated in this study with respect to the properties examined (accepting the hypothesis that there was no difference due to diluent monomer). (Am J Dent 2007;20:147-152).

Clinical significance: The lower level of BAPO had such low flexural strength and conversion that it should not be used clinically. As the higher level of BAPO performed as well as the CQ/4E system, this class of initiators may hold promise for use in dental composites.

: Dr. Joseph M. Antonucci, National Institute of Standards and Technology (NIST), Stop 8545, 100 Bureau Drive, Gaithersburg, MD 20899-8545 USA. E-:


Clinical and microbiological effects of a combined mechanic-antibiotic therapy in subjects with Actinobacillus actinomycetemcomitans-associated periodontitis

Bettina Dannewitz, dr med dent, Sabine Pohl, dr med, Peter Eickholz, prof, dr med dent

& Ti-Sun Kim, dr med, dr med dent

Abstract: Purpose: To evaluate the clinical and microbiological effects of a combined mechanic-antibiotic periodontal therapy in subjects that were tested positive for subgingival Actinobacillus actinomycetemcomitans (A.a.). Methods: The postoperative follow-up ranged from 12-115 months (average 39.2 months). This follow-up study analyzed the data of 53 subjects (37 females) aged from 16-59 years, who underwent systemic periodontal therapy with adjunctive systemic antibiotics between 1992-2001 and had their last re-examination including microbiological analysis done in 2003. The antibiotic regime was either amoxicillin/metronidazole or ciprofloxacine/metronidazole. During this study, A.a. was detected with two gene probe tests (IAI PadoTest 4.5 and DMDx/PathoTek) and cultivation on TSBV agar plates. The clinical situation was characterized with the help of pocket probing depths and subsequent categorization into three different groups ( 4 mm, 5-6 mm and 7 mm). Results: After therapy, A.a. was detected with IAI PadoTest 4.5 in a magnitude between 3.0 x 103 up to 2.06 x 105 counts per specimen in 9 out of 53 subjects. Only two subjects tested positive for A.a. with the DMDx/PathoTek-assays and the agar cultivation. The clinical situation improved significantly in all subjects after systemic periodontal therapy. The treatment results remained stable during the course of the postoperative follow-up. Concerning the clinical data, no differences were found between the subjects that were tested positive and negative for A.a in the postoperative period. (Am J Dent 2007;20:153-156.

Clinical significance: Positive test results for A.a. after completed periodontal therapy should be evaluated critically in the context of the clinical situation. These subjects should undergo a regular supportive periodontal therapy to diagnose any reinfection as early as possible and to plan the treatment accordingly.

: Priv. Doz. Dr. Ti-Sun Kim, Section of Periodontology, Dental Clinic, INF 400, 69120 Heidelberg, Germany. E-:

The role of oxygen inhibition of a self-etch adhesive on self-cure

resin composite bonding

Tatsuo Endo, dds, phd Werner J. Finger, dr med dent, phd, Marcus Hoffmann, dr rer nat,

Masafumi Kanehira, dmd, phd & Masashi Komatsu, dds, phd

Abstract: Purpose: To evaluate the bond strengths on enamel and dentin with a self-etch adhesive (iBond), with or without oxygen-inhibited surface layer, or covered with intermediate self-curing resin, in combination with chemical-cured composite (Core Paste). Methods: Bond strengths on human enamel and dentin (n = 8) were determined according to the following procedures: 1. Adhesive cured under ambient air. 2. Inhibited surface wiped with ethanol. 3. Adhesive cured under nitrogen. 4. Adhesive covered with glycerol during activation. 5. Adhesive coated with glycerol for 1 minute after activation. 6. As 5, but covered for 5 minutes. 7. Cured adhesive coated with intermediate self-curing resin. 8. As 7, but intermediate resin’s amine component loaded with anion exchange resin in OH- form. Shear bond strengths (SBS) were measured after 24-hour storage in 37°C water. Results: SBSs on enamel (7.1 to 25.6 MPa) were, by ranking order (P< 0.05): 4 < 3, 5, 6 < 1, 2, 3, 6 <1, 2, 3, 7 < 1, 7, 8; SBSs on dentin (1.0 to 19.6 MPa): 1, 4, 5, 6 < 1, 2, 6 < 2, 3, 7 < 8. Oxygen inhibition had no adverse effect on enamel bond strengths. On dentin, all groups, apart from the anion exchange resin group (mean 19.6 MPa), showed bond strengths < 8 MPa. Dentin SBS of self-etch adhesive combined with self-cured resin was low, irrespective of the presence of an oxygen-inhibited layer. Deprotonization of the acidic adhesive monomer with an admixed anion exchange compound, added to an intermediate self-cured resin, was effective at overcoming the incompatibility. (Am J Dent 2007;20:157-160).

Clinical significance: Bond strength on dentin was severely compromised when the self-etch adhesive iBond was used in combination with chemical-cured resin composite.

: Dr. Werner J. Finger, Department of Preclinical Dentistry, School of Dental Medicine, University of Cologne, Kerpener Strasse 32, D-50931 Cologne, Germany. E-:


Micro-tensile and micro-shear bond strengths of current self-etch adhesives to enamel and dentin


Ayano Ishikawa, dds, Yasushi Shimada, dds, phd, Richard M. Foxton, bds, phd, mfds rcs (Ed) & Junji Tagami, dds, phd

Abstract: Purpose: To evaluate the micro-tensile and micro-shear bond strengths of self-etch adhesives to enamel and dentin. Methods: Extracted human molars were ground to expose flat enamel or dentin surfaces using wet #600 grit SiC paper. The enamel and dentin surfaces were assigned to four groups of four adhesives: three one-step self-etch adhesives (Clearfil S3 Bond; AQ Bond Plus, G-Bond) and a two-step self-etch adhesive (Clearfil SE Bond). Each of the adhesives were applied to the enamel or dentin surfaces in accordance with the manufacturers’ instructions and restored with resin composite (Clearfil AP-X). The bonded teeth were then prepared for either micro-tensile or micro-shear bond strength tests. After storage in saline at 37°C for 24 hours, specimens were stressed at a crosshead speed of 1 mm/minute. Mean bond strengths and modes of failure were analyzed using one-way ANOVA followed by Scheffe’s F test and the Chi-square test, respectively, at a 95% level of confidence. Results: SE Bond produced significantly higher values than the one-step adhesives in the micro-shear bond test to enamel (P< 0.05), while no significant differences were found among the adhesives in the micro-tensile bond test (P> 0.05). For dentin, SE Bond showed the highest bond strengths in both micro-tensile and micro-shear bond tests; values were significantly higher than both AQ Bond Plus and G-Bond (P< 0.05). (Am J Dent 2007;20:161-166).

Clinical significance: The two-step self-etch adhesive showed higher bond strength values than the one-step adhesives in both the micro-tensile and micro-shear bond tests.

: Dr. Ayano Ishikawa, Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. E-:


Push-out bond strengths of endodontic posts bonded with different

resin-based luting cements


Lionel Huber, dmd, Maria Cattani-Lorente, phd, Ligia Shaw, dmd, Ivo Krejci, dmd, phd & Serge Bouillaguet, dmd, phd

Abstract: Purpose: To compare the push-out bond strengths of endodontic posts bonded with different resin-based luting cements and to verify that bond strengths did not vary with cement thickness. Methods: 48 root canals were shaped using 6% NiTi rotary files, obturated with gutta-percha and AH Plus sealer and prepared for post cementation using Panavia F, Parapost cement, SuperBond and Unicem Rely X. All roots were sectioned into 0.7 mm thick slices and digital photographs of each slice were analyzed using Scion Image to measure the surface area of the luting cement. The root slices were stressed to failure at 1 mm/minute using a push-out test. Push-out strength was calculated as the force at failure divided by the bonded surface area. Least squares linear regression analysis was used to assess the effect of cement thickness on bond strength. Fractured specimens were further observed under the SEM. Results: Mean push-out bond strengths were: Panavia F (8.8 3.6 MPa), Parapost cement (9.1 4.4 MPa) SuperBond (14.6 2.9 MPa) and Rely X Unicem (12.4 3.3 MPa). The Panavia F and the Parapost cement were not significantly different from each other, but both were significantly lower (P ≤ 0.05) than SuperBond and Rely X Unicem. Although there were large variations in cement thickness, the cementation of fiber posts with thicker cement layers did not affect the performance of the adhesive luting cements applied to root canal dentin. (Am J Dent 2007;20:167-172).

Clinical significance: Although the thickness of the luting cement observed after post cementation was variable, it did not influence the bonding performances of the resin-based luting cements tested to root canal dentin.

: Dr. Serge Bouillaguet, Section of Dental Medicine, 19 rue B. Menn, 1205 Geneva, Switzerland. E-:


Susceptibility of bleached enamel and root dentin to artificially

formed caries-like lesions

Márcio de Menezes dds, Cecilia Pedroso Turssi, dds, ms, phd, Juliana Jendiroba Faraoni-Romano, dds, ms

& Mônica Campos Serra, dds, ms, phd

Abstract: Purpose: To evaluate in vitro the susceptibility of caries-like lesion formation on enamel and root dentin that had been bleached with carbamide peroxide agents. Methods: 150 slabs of bovine enamel and root dentin were ground flat and polished. According to a randomized complete block design, the specimens were then allocated to be bleached with agents (Rembrandt) containing 12% [CP12], 16% [CP16], 22% [CP22] or 30% [CP30] of carbamide peroxide over 21 days. The control group remained unbleached. Afterwards, all specimens were randomly distributed between two sub-groups (n= 15): one was subjected to alternating demineralizing and remineralizing solutions to induce caries-like lesions and the other was not. Enamel specimens were cycled four times in demineralizing (pH 5.0) and remineralizing solutions (pH 7.0), while root dentin specimens were cycled twice. Microhardness measurements were carried out at the post-bleaching and at the post-caries lesion formation phases. Results: In the post-bleaching condition, microhardness values for both enamel and root dentin were dependent on the bleaching agent used. At the post-caries formation stage, there was a significant interaction between the bleaching treatment and substrate condition (carious or noncarious) for enamel and root dentin. Regardless of the bleaching agent, carious enamel and root dentin presented significantly lower microhardness values as compared to the noncarious counterparts. For carious enamel, those specimens exposed to CP16 exhibited higher microhardness values than the subset group formed by CP22, CP30 and unbleached samples. Both subsets did not differ from CP12. For carious root dentin, no difference was observed among the microhardness values attained as a result of the different bleaching treatments. (Am J Dent 2007;20:173-176).

Clinical significance: Bleaching does not seem to pose any extra risk to caries lesion formation in enamel and root dentin.

: Dr. Cecilia Pedroso Turssi, Department of Restorative Dentistry, Faculdade de Odontologia de Ribeirão Preto – USP, Av. do Café, s/n Monte Alegre, Cep: 14040-904, Ribeirão Preto, SP, Brazil. E-:


Shear bond characteristics of a tooth-colored temporary coating material to enamel

Chieko Imamiya, dds, Yasushi Shimada, dds, phd, Michael F. Burrow, mds, phd & Junji Tagami, dds, phd

Abstract: Purpose: To evaluate the bonding performance of a coating material “White Coat” (Kuraray) to enamel. Methods: Effect of surface treatment on bonding, durability of bonding, as well as re-bonding as a repeated treatment were investigated using extracted human incisors. To evaluate the effect of surface treatment, intact or ground enamel surfaces were treated using White Coat primer for 20 seconds or 40% phosphoric acid (K-etchant) for 10 or 60 seconds, as well as combination usage of White Coat primer and 40% phosphoric acid. Small resin cylinders of the base-coat of White Coat were bonded to the treated surfaces and irradiated for 30 seconds. For the durability test, small resin cylinders of base coat were bonded to intact enamel using White Coat primer and stored in 37°C saline for 1 day, 1 week, 1, 3, and 6 months. Furthermore, to investigate the effect of re-bonding after the removal, re-bonding was done after various removal regimens. A micro-shear test was used to assess the bond strength of all specimens. Results: Application of the primer for 20 seconds to intact enamel produced a mean micro-shear bond strength of 28 MPa for intact and ground enamel. Values were similar to 10 seconds phosphoric acid etching to ground enamel (P> 0.05). The bond strength of the primed intact enamel did not decrease up to 3 months (P> 0.05), but decreased significantly by 6 months (P< 0.05). The removal and rebonding of the coating, as well as the storage time showed no significant influence on the bonding of the coat (P> 0.05). Consequently, White Coat was considered an acceptable temporary coating material for no longer than 3 months. (Am J Dent 2007;20:177-181).

Clinical significance: Within the limitations of this study, the coating material White Coat showed acceptable bonding as a temporary restoration in vitro for up to 3 months using the associated primer. This material also showed no decrease of the bond after repeated debonding and reapplication with no enamel fracture being observed.

: Dr. Chieko Imamiya, Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. E-:


Clinical and radiographic evaluation of adhesive pulp capping in primary molars following hemostasis with 1.25% sodium hypochlorite:

2-year results

Tahsin Demir, dds & Zafer C. Çehreli, dds, phd


Abstract: Purpose: To evaluate, prospectively, the clinical and radiological response of primary molars, pulp-capped with calcium hydroxide and different adhesive systems after hemorrhage control with 1.25% sodium hypochlorite (NaOCl). Methods: 100 primary molar teeth were pulp-capped in 67 children who met inclusion criteria. Hemorrhage at the exposure site was controlled with 60 seconds application of 1.25% NaOCl. Teeth were randomly assigned into five groups (n=20 each) with respect to the material/technique used for capping: (1) calcium hydroxide cement (Dycal); (2) acetone-based total-etch adhesive (Prime&Bond NT); (3) a non-rinse conditioner (NRC) and Prime&Bond NT; (4) total-etching with 36% phosphoric acid followed by Prime&Bond NT; and (5) a self-etch adhesive system (Xeno III). Teeth in Group 1 were restored with amalgam and Groups 2-5 with polyacid-modified resin-based composite (Dyract AP). The teeth were evaluated clinically and radiographically for 24 months. Marginal integrity of the restorations was also recorded at recall periods using modified USPHS/Ryge criteria. Results: After 2 years, the overall success rate of direct pulp capping was approximately 93% (78/84 teeth, excluding exfoliations). The Dycal and Prime&Bond NT groups did not exhibit any clinical or radiographic failure. A majority of failures were observed in teeth that received NRC and phosphoric acid pretreatments (Groups 3 and 4). Clinical symptoms were seldom associated with failed teeth. Only one tooth failed in the Xeno III group. Marginal integrity scores were not compatible with the clinical/ radiographic outcome. (Am J Dent 2007;20:182-188).

Clinical significance: For primary molars with Class I cavities that are expected to exfoliate within 2 years, direct pulp capping with prior NaOCl hemostasis can be performed using calcium hydroxide or the tested total- and self-etch adhesives. However, in pulp capping, the tested total-etch adhesive (Prime&Bond NT) must not be used in conjunction with phosphoric acid or NRC.

: Dr. Zafer C. Çehreli, Gazi M. Kemal Bulvari, 61/11, 06570 Maltepe, Ankara, Turkey. E-:


Clinical and radiographic evaluation of indirect pulp treatment

in primary molars: 36 months follow-up

Renata Franzon, dds, Luciano Casagrande, dds, ms, Alice Souza Pinto, dds, ms,

Franklin García-Godoy, dds, ms, Marisa Maltz, dds, ms, phd & Fernando Borba de Araujo, dds, ms phd

Abstract: Purpose: To evaluate the clinical and radiographic changes in primary teeth submitted to indirect pulp treatment (IPT) over a 36-month period. Methods: Thirty-nine primary molars with deep caries, but without pre-operative signs and symptoms of irreversible pulpits, received IPT. The teeth were randomly divided into two groups, according to the material used for protection of the dentin-pulp complex: (1) a calcium hydroxide liner (Hydro C) and (2) a gutta-percha sheet. Both groups were restored with Z250 resin-based composite. Results: After 36 months, Group 1 showed a success rate of 73.3% and Group 2, 85.7%. The overall success rate was 79.3%, with no statistically significant difference between the groups (P = 0.36). (Am J Dent 2007; 20:189-192).

Clinical significance: The results of this study suggested that indirect pulp treatment of primary teeth restored with a resin-based composite may arrest the progression of the underlying caries, regardless of the material used as a liner.

: Dr. Fernando Borba de Araujo, Department of Pediatric Dentistry, Faculty of Dentistry, UFRGS, Rua Ramiro Barcelos, 2492, Bom Fim, Porto Alegre, Rio Grande do Sul, CEP: 90035-003, Brazil. E-:


Effect of a 40% chlorhexidine varnish on demineralization

of dentin surfaces in situ


Mozhgan Bizhang, dds, dr med dent, Rainer Seemann, dds, phd, dr med dent, Gregor Römhild, dds,

Yong-Hee P. Chun, dds, ms, dr med dent, Niklas Umland, dds, dr med dent, Hermann Lang, dds, phd

& Stefan Zimmer, dds, phd, mphd

Abstract: Purpose: To evaluate the effect of varnish with different chlorhexidine concentrations on the demineralization of dentin surfaces in situ. Methods: An intraoral model was used to study the ability of chlorhexidine to prevent demineralization. Dentin specimens from extracted human teeth were treated with chlorhexidine varnish and exposed to the oral environment of 47 subjects. The dentin specimens were prepared from the cervical regions of 47 third molars, sterilized by irradiation with 60 GY and mounted in intraoral appliances worn by the subjects. Before the delivery of the appliance, the specimens and participants were treated once with one of the three different varnishes (according to the manufacturer’s instructions). All participants were randomly assigned to one of the three groups: (1) EC 40 (n=16), (2) Cervitec (n=15), or (3) ChemFil Varnish (control group, n=16). The appliances were worn day and night for 3 weeks. At mealtimes, the appliance was stored in 10% sucrose solution. After exposure to demineralization, the dentin surface was evaluated by microradiography to assess the depth of the lesion (µm) and the loss of mineral (Vol% µm). Data analysis was accomplished using one-way ANOVA plus LSD testing (P< 0.05). Results: Both chlorhexidine varnishes EC 40 and Cervitec resulted in significantly decreased mineral loss and lesion depth in dentin than the control. In addition, EC 40 treated specimens demonstrated significantly reduced lesion depth compared to Cervitec® and the control (109.22 µm vs. 139.23 µm and 178.21µm). (Am J Dent 2007;20:193-197).

Clinical significance: The results suggested that dentin treatment with either EC 40 or Cervitec prevents mineral loss and lesion depth. Therefore, chlorhexidine treatment of dentin might be a favorable regimen to prevent deminerali­zation in patients at high risk for root caries.

: Dr. Mozhgan Bizhang, Heinrich-Heine-Universität, Dept. of Operative and Preventive Dentistry and Endodontics, Moorenstr. 5, 40225 Düsseldorf, Germany. E-:

Retention of three endodontic post systems

John Peters, dds, Gad Zyman, dds, Enrique Kogan, dds, Sergio Kuttler, dds & Franklin García-Godoy, dds, ms

Abstract: Purpose: To evaluate the retention of three post systems using one adhesive and one cement. The hypothesis tested was that there was no significant difference among the posts. Methods: 90 freshly extracted single rooted lower bicuspids were evaluated for similar root morphology. The teeth were decoronated using an Isomet saw leaving a 15 mm-long sample. Preoperative digital radiographs were taken of all samples from the buccal and mesial direction. A glide path was established with #15K type file. Roots were then instrumented to working length to a size #40 .04 using Profile nickel titanium files. 1cc of distilled water was used as an irrigant after each file to remove dentinal debris. The teeth were then obturated with custom fit #40 0.04 taper gutta percha points and AH Plus as a sealer, using a warm vertical compaction technique. Residual gutta percha of 5 mm was left. The samples were divided into three experimental groups to receive posts. Group 1: Fiber White Para-Post No. 2 red; Group 2: No. 1 DT Light Post; Group 3: PeerlessPost No. 3. Post spaces were created in Groups 1 and 2 with the appropriate drills supplied by the manufacturer using a slow speed handpiece. The post spaces from Group 3 required no further preparation after endodontic treatment. All posts were cemented with Nexus 2 Universal Luting System. A layer of excess cement was left in the most coronal portion of the tooth for visual confirmation of tensile strength failure. Using an Instron the teeth were mounted in a custom-made jig to prevent crushing of the post and to ensure extension perpendicular to the long axis of the post. Samples were then subjected to tensile stresses until failure occurred. Failure was defined as the maximum load produced under tensile load that corresponded to visual separation of the post from the tooth. The maximum load at failure in kilograms was recorded. The average of each group was compared for significant difference. Data was analyzed using ANOVA at a significance level of P= 0.016 (Bonferroni correction for multiple t-tests). Results: Maximum load at failure, measured in kilograms, were as follows: PeerlessPosts 126.07 kg, Fiber White Posts 90.14kg, and DT Light Posts 88.46 kg. ANOVA revealed a statistically significant difference among the three posts systems. PeerlessPosts required statistically significantly higher force to be removed while there was no statistically significant difference between the Fiber White Posts and the DT Light Posts; therefore, the hypothesis was rejected. (Am J Dent 2007;20:198-200).

Clinical significance: The PeerlessPost required more force to be removed from single-rooted extracted bicuspids than the Fiber White Posts and DT Light Posts (P= 0.0044, ANOVA and t-test with Bonferroni correction). Furthermore, the PeerlessPost required no canal preparation after the completion of root canal therapy unlike the DT Light and the Fiber White posts.

: Dr. Sergio Kuttler, College of Dental Medicine, Nova Southeastern University, 3200 South University Drive, Fort Lauderdale, Florida 33328, USA. E-:

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