Current Issue
July/August, Volume 34, Number 4

SUMMARY:
The stronger the ceramic material, the longer the restoration stays in the mouth. The current study evaluated the two-year clinical performance of a strong ceramic system, IPS Empress II, with increased strength on onlay/inlay restorations of molars.

Teeth from 35 patients, including three premolars and 32 molars, were prepared for 28 onlay and seven inlay restorations with IPS Empress II ceramics. The restorations were cemented with a highly viscous, dual-curing luting composite cement (Bifix) and evaluated by two examiners using USPHS criteria at baseline (one week following insertion), six months, one year and two years.

The baseline scores and recalls were assessed by Wilcoxon signed rank test. Statistically significant marginal discoloration at the Bravo level was found at the 12- and 24-month recalls (p=0.046). One debonding was statistically insignificant.

No changes were observed with respect to anamnesis, such as any symptom from the TMJ or masticatory muscles. No restorations were replaced due to hypersensitivity or were missing at the two-year evaluation. Any wear on the restoration, antagonist tooth or any changes of proximal contacts were not observed.

IPS Empress II Ceramics were found to be appropriate as onlay/inlay restorations for clinical use under the conditions of the current study.

SUMMARY:
The current in vivo study evaluated the degradation of dentin hybrid layers in deep occlusal-surface resin composite restorations using TEM. Caries-free premolars scheduled for extraction as part of orthodontic treatment were prepared and restored, then extracted after 12 months. The adhesive used was a single-bottle etch-and-rinse acetone-based product (Prime & Bond NT, Dentsply/Caulk). Control group restorations (n=8) were placed according to the manufacturer’s instructions, while the experimental group received application of a 2% solution of chlorhexidine digluconate after etching and rinsing and prior to application of the adhesive. Extensive degradation was observed in all of the teeth in the control group after 12 months, while no degradation was observed in the experimental group. In vitro testing showed no significant difference in immediate microtensile bond strength between the control and experimental adhesive protocols.

SUMMARY:
This double-blind randomized clinical trial compared different ethanol/water and acetone-based systems in non-carious cervical lesions over 36 months. Materials and Methods: Eighty-four patients having at least one non-carious cervical lesion [NCCL] under occlusion were enrolled in this study. A total of 84 restorations were placed, half for each group (Adper Single Bond [SB] + Filtek A110 or One Step [OS] + MicroNew). All the materials were placed by two calibrated operators. Two other independent examiners evaluated the restorations at baseline, 6, 12, 18 and 36 months, according to slightly modified USPHS criteria. Statistical analysis between materials in each period was conducted using the Fisher’s exact test (a=0.05), and performance of the materials in the baseline in comparison to each period was evaluated by McNemar’s test (a=0.05). Results: The 12-, 18- and 36-month retention rates for SB were 95.2% (12 and 18 months) and 92.3% (36 months). For OS, the retention rates were 83.3%, 73.8% and 56.4%, respectively, for each recall period. After 36 months, 10 OS restorations (25.7%) and seven SB restorations (17.9%) were rated as Bravo in the marginal discoloration item. Conclusions: The ethanol/water-based adhesive (Single Bond) that was evaluated showed a higher retention rate than the acetone-based system (One Step) after 36 months of clinical service.

SUMMARY:
Objective: Dentin hypersensitivity, or what patients may describe as “sensitive teeth,” is defined as a short, sharp pain arising from exposed dentin in response to thermal, evaporative, tactile, electrical, osmotic or chemical stimuli. It is widely accepted that dentin hypersensitivity is an uncomfortable condition that also affects function and quality of life. This study determines the differences in efficiency of three desensitizing products when compared with a placebo.

Methods: A randomized controlled clinical trial was conducted to compare three different professional dentin desensitizer agents in 52 patients. The age and sex of the patients was recorded. Gluma Desensitizer (Heraeus Kulzer), UltraEZ (Ultradent Products, Inc) and Duraphat (Colgate Oral Pharmaceuticals, Inc, New York, NY, USA) were used as desensitizer agents and distilled water was used as the placebo. The baseline measurement of the dentin hypersensitivity was made by using a visual analog scale (VAS). Twenty-four hours and seven days after application of the desensitizer agents and placebo, a new VAS analysis was conducted for patients’ sensitivity level. The desensitizer agents were compared in terms of mean values, and ANOVA was used for testing differences among the groups (p<0.05).

Results: The results showed that the mean pain scores of the placebo group were significantly higher than that of the study groups (p<0.05). The VAS analysis revealed a significant decrease in dentin hypersensitivity over time with the use of agents (p<0.05). No statistically significant difference was found among the three desensitizing agents (p>0.05).

Conclusions: These three desensitizing agents, which contain different active ingredients, were effective in relieving dentin hypersensitivity. However, no superiority was found in dentin sensitivity relief among the agents.

SUMMARY:
Objective. The current study evaluated the micro-shear bond strength between a resin luting agent and four strengthened all-ceramic systems under different surface treatments.

Methods. Rectangular specimens of IPS Empress 2 (Ivoclar-Vivadent), Cergogold (DeguDent), In Ceram Alumina (Vita) and Cercon (DeguDent) ceramics were fabricated and randomly divided into three groups: 1—no treatment; 2—etched with 9.5% hydrofluoric acid and 3—airborne-particle abraded with 50 µm aluminum oxide particles. The ceramic surfaces of the specimens were coated with a silane agent (Clearfil Porcelain Bond, Kuraray), then bonded with a resin-luting agent (Panavia F, Kuraray). A micro-shear bond test was carried out to measure the bond strength. Moreover, each ceramic surface was observed morphologically by scanning electron microscopy. The results were submitted to analysis of variance and Tukey’s post-hoc analysis (p<0.05).

Results. The bond strength of all ceramic systems evaluated was affected by the surface treatments (p<0.05). The highest values for bond strength of IPS Empress 2 were found when the surface treatment used was hydrofluoric acid etching, followed by airborne particle abrasion treatment. On the other hand, airborne particle abrasion treatment and acid etching were not different for Cergogold and In Ceram Alumina ceramics, but they were higher when compared to the control (p<0.05). The highest bond strength to Cercon was found when it was treated with airborne particle abrasion with aluminum oxide. The SEM photographs showed that the hydrofluoric acid etching treatment affected the surface of IPS Empress 2 and Cergogold; however, Cercon and In Ceram surface morphology were not changed by the hydrofluoric acid etching. The airborne particle abrasion treatment altered the Cercon ceramic morphology but it did not change the other ceramic’s surface.

SUMMARY:
Purpose: To evaluate the effect of light guide distance and the different photoactivation methods on the degree of conversion (DC) and microleakage of a composite. Methods and Materials: Three photoactivation protocols (600mW/cm2 x 40 seconds; 400 mW/cm2 x 60 seconds or 200 mW/cm2 x 20 seconds, followed by 500 mW/cm2 x 40 seconds) and three distances from the light source (0, 3 or 7 mm) were tested. Cylindrical specimens (5 mm diameter; 2 mm tall; n=3) were prepared for the DC test (FT-Raman). Class V cavities were made in 90 bovine incisors to conduct the microleakage test. The specimens were conditioned for 15 seconds with phosphoric acid (37%), followed by application of the adhesive system Prime & Bond NT (Dentsply/Caulk). The preparations were restored in bulk. The specimens were stored for 24 hours in distilled water (37°C) before being submitted to the silver-nitrate microleakage protocol. The restorations were sectioned and analyzed under 25x magnification. Results: Statistical analyses (two-way ANOVAs and Tukey test, a=0.05) found significance only for the factor distance (p=0.015) at the top of the composite for the DC test. Conversion was statistically lower for the 7 mm groups compared to the 0 and 3 mm groups, which were equivalent to each other. At the bottom of the specimens, none of the factors or interactions was significant (p<0.05). The Kruskal-Wallis test showed that, in general, the soft-start method led to lower microleakage scores when compared to the continuous modes, mainly when associated with a distancing of 7 mm (p<0.01). With the exception of specimens irradiated with 400mW/cm2 that did not demonstrate variations on scores for the distances tested, higher microleakage was observed for shorter distances from the light source. Conclusions: Soft-start methods may reduce microleakage when the light guide distancing provides a low level of irradiance, which also causes a discrete reduction in the DC.

SUMMARY:
The current study evaluated the micro-shear bond strength of two resin cements to astringent-contaminated dentin. Twelve occlusal dentin discs were prepared from extracted caries-free human molars and divided into two groups subjected to two types of resin cements, Panavia F (PF) and Variolink II (VL). Each disc was ground with 600 grit SiC paper and sectioned into two semi-disks, one for the normal dentin surface and the other for the contaminated dentin surface. For contaminated dentin, an astringent containing aluminum chloride was applied for two minutes and rinsed before the bonding procedures. A micro tygon tube was placed on the dentin surface following the bonding application and then filled with a resin cement. After the resin was polymerized, the specimen was kept in water for 24 hours before the micro-shear bond strengths evaluation. The micro morphology of the treated surfaces and resin-dentin interfaces were observed under a scanning electron microscope (SEM). Aluminum content under different dentin conditions was also examined. No significant differences were found between the dentin bond strengths to normal dentin and contaminated dentin surfaces in both the PF and VL groups (p>0.05). PF showed similar bond strengths to VL on normal and contaminated dentin (p>0.05). SEM observations of the VL groups revealed no differences in the treated dentin surfaces and the resin-dentin interfaces between normal and contaminated dentin. However, for the PF group, an inconsistent etching pattern of the self-etching primer and gap formation at the interface of resin cement to contaminated dentin were observed.

SUMMARY:
This in vitro study evaluated the toothbrush abrasion wear, three-body Alabama wear and two-body pin-on-disc wear of four commercial indirect resin composites. Enamel shades of Radica (R), Sculpture Plus (S), Belleglass-NG (B) and Gradia Indirect (G) were used. For measuring wear due to toothbrush abrasion, six specimens of each group were fabricated, then brushed in a toothbrush abrasion machine for 20,000 cycles. Material loss was determined by weighing and conversion to volume loss. Three-body wear was measured on six samples for each group using an Alabama-type wear testing machine for 400,000 cycles. Wear depth was measured with a contact profilometer. For two-body wear, five disc specimens were prepared and tested in a two-body wear-testing machine against hydroxypatite sliders for 25,000 cycles. Data were analyzed with one-way analysis of variance (ANOVA) and Tukey test (alpha=0.05). Wear was the highest in Sculpture Plus by all three methods tested and the lowest wear was observed in Belleglass-NG. No statistical difference in wear was noted from Radica.

SUMMARY:
This study compared the fracture strength of different conditioned metallic posts, fiber-reinforced-composite posts and composite cores only in teeth without coronal tooth structure and determined failure modes after the fracture test. Post spaces were prepared in the root canals, and the teeth were randomly divided into seven experimental groups: Gr1: Titanium posts (ParaPost) + Silano-Pen (Bredent) + silane; Gr2: Titanium posts + 30 µm CoJet-Sand (3M ESPE) + silane; Gr3: Titanium posts + 50 µm Al2O3+V-primer (Sun Medical); Gr4: Titanium posts+50 µm Al2O3 + Alloy primer (Kuraray); Gr5: E-glass FRC post (EverStick); Gr6: Polyethylene fiber (Ribbond) + Resin impregnation and Gr7: Resin composite core only, with no posts. The posts were cemented using Panavia F 2.0 (Kuraray); coronal parts of the roots were etched, primed, bonded and composite cores were built-up. After thermocycling (5°C-55°C, 6000x), the fracture strength test was performed. The fracture strength of titanium posts (408 ± 122 – 550 ± 149 N) was significantly higher (p<0.05) than that of FRC posts (321 ± 131 and 267 ± 108 N for Everstick and Ribbond, respectively) or the group without posts (175 ± 70 N) (Gr7) (ANOVA, Tukey’s test). The group without posts resulted in complete core detachment (100%). In the E-glass FRC group, 60% adhesive core fracture occurred, covering >1/3 of the core and, in the polyethylene FRC group, 100% post-core detachment at the canal opening was observed. In all the titanium post applied groups (Gr1-Gr4), the posts remained in place with partial detachment of the core material from the post surface at varying degrees, depending on the conditioning method used. When no coronal tooth structure exists, the metal posts showed higher fracture strength values as opposed to the FRC post or no-post approach.

SUMMARY:
This study evaluated the effect of conventional versus ultrasonic cementation techniques on the fracture strength of resin composite laminates. In addition, the failure modes were assessed. Window-type preparations 1 mm above the cemento-enamel junction were made on intact human maxillary central incisors (N=60) of similar size with a depth cutting bur. All the prepared teeth were randomly assigned to six experimental groups (10/per group). Using a highly filled polymeric material (Estenia), laminates were produced and finished.The standard thickness of laminates in original tooth form was achieved using the impression molds made prior to tooth preparation. A three-step bonding procedure and dual polymerized resin composite cement (Panavia F 2.0) was employed. The cementation surfaces of the laminates were conditioned (CoJet-Sand, 30 µm SiO2) and silanized (ESPE-Sil). Laminates in Groups 1, 2, 3, 4 and 5 were cemented by five different operators under finger pressure and Group 6 was cemented ultrasonically (Amdent). After excess removal, the laminates were light polymerized. The specimens were stored in water at 37°C for one month prior to the fracture test (universal testing machine, 1 mm/minute). Failure types were classified as: a) Cohesive failure within the composite laminate (Type A), b) Adhesive failure between the tooth and laminate (Type B) and c) Chipping of the laminate with enamel exposure (Type C). No significant difference was found among the mean fracture strength values of the laminates in all the experimental groups (ANOVA, p=0.251). The mean fracture strength values in descending order were: 513 ± 197, 439 ± 125, 423 ± 163, 411 ± 126, 390 ± 94, 352 ± 117 N for Groups 2,5,4,3,1 and 6, respectively. The majority of failure types was Type A (30/60). While Type B failure was not observed in Group 6 (0/10), Group 1 presented a more frequent incidence of this failure (6/10). The two cementation techniques did not effect the fracture strength of composite laminates, but failure types varied between groups, being more favorable for the ultrasonically cemented group.

SUMMARY:
Purpose: To evaluate the effect of different strategies for post cementation on the pullout bond strength of a double-tapered glass fiber post cemented into a root canal. Materials and Methods: The root canals of 70 single-rooted bovine teeth (16 mm-length) were prepared to 9 mm using the preparation drill of a double-tapered glass fiber post system (White Post DC, FGM). Each specimen was embedded in a plastic cylinder using acrylic resin up to 3 mm of the most coronal portion of the specimen and allocated into one of seven groups (n=10) based on strategies for cementation: Gr1–ScotchBond Multi Purpose plus (SBMP) + Relyx ARC resin cement; Gr2–Single Bond + Relyx ARC; Gr3–ED Primer + Panavia F resin cement; Gr4–SBMP + AllCem resin cement; Gr5–Relyx ARC; Gr6–Relyx Unicem resin cement; Gr7–Relyx Luting 2 glass ionomer cement. After cementation, the specimens were stored for seven days (in a humid environment at 37°C) and submitted to pullout bond strength testing (the inferior part of each specimen was fixed and the fiber post was pulled out). The data (Kgf) were submitted to statistical analysis (one-way ANOVA and post-hoc Tukey tests, a=.05). The tested specimens were analyzed under the microscope and SEM for fracture analysis. Results: The strategy for post cementation affected the pullout retentive strength (Kgf) (p<0.0001) significantly. Gr6 (37.7 ± 8a), Gr1 (37.4 ± 5.7a) and Gr4 (31.6 ± 6.6ab) presented the highest pullout bond strengths. Gr2 (12.2 ± 5.6c), Gr3 (6.5 ± 5.2c) and Gr7 (5.1 ± 2.8c) presented the lowest pullout bond strengths. Gr5 (24.2 ± 7.4b) was similar to Gr4 and inferior to Gr6 and Gr1. Conclusion: The use of a three-step etch-&-rinse adhesive system appears to be effective. The application of other adhesive systems (single-bottle etch-&-rinse and self-etch adhesive systems) did not present high pullout strength values. The simplified self-adhesive resin cement (without adhesive application) presented good retentive performance. Further studies should be conducted.

SUMMARY:
This study evaluated the effect of the C-factor and dentin preparation method (DPM) in the bond strength (BS) of a mild self-etch adhesive; the study also observed the SEM superficial aspects of the corresponding smear layer. For purposes of this study, 25 molars (n=5) were used in a bond strength test. The molars were divided into two parts (buccal and lingual): one part received a Class V cavity (C-factor=3) and the other received a flat surface (C-factor=0) with the same bur type (coarse diamond or carbide bur and fine diamond or carbide bur), both within the same dentin depth. Five teeth were prepared with wet 60-grit and 600-grit SiC papers. After restoration with Clearfil SE Bond, microtensile beans (0.8 mm2) were prepared and tested after 24 hours in a universal testing machine (0.5 mm/minute). An additional two teeth for each DPM were prepared for SEM evaluation of the smear layer superficial aspects. The BS values were submitted to one-way ANOVA, considering only the DPM (flat surfaces) and two-way ANOVA (C-Factor x DPM, considering only burs) with p=0.05. Although the DPM in the flat surfaces was not significant, the standard deviations of carbide bur-prepared specimens were markedly lower. The BS was significantly lower in cavities. The fine carbide bur presented the most favorable smear layer aspect. It was concluded that different dentin preparation methods could not prevent the adverse effect in bond strength of a high C-factor. A coarse cut carbide bur should be avoided prior to a mild self-etch adhesive, because it adversely affected bond strength. In contrast, a fine cut carbide bur provided the best combination: high bond strength with low variability, which suggests a more reliable bond strength performance.

SUMMARY:
Objective: This study examined the effect of Er,Cr:YSGG laser irradiation on the microtensile bond strength (µTBS) of a three-step etch-and-rinse and a two-step self-etch adhesive to sound and caries-affected dentin. Methods: Sixteen freshly extracted human molars with occlusal dentin caries were used. The caries lesion was removed by one of the following methods: conventional treatment with burs or Er,Cr:YSGG laser (Waterlase MD, Biolase). The adhesive systems (AdheSE, Ivoclar Vivadent and Scotchbond Multi Purpose, 3M ESPE) were applied to the entire tooth surface according to the manufacturers’ instructions. Resin composites were applied to the adhesive-treated dentin surfaces and light-cured. Each tooth was sectioned into multiple beams with the “non-trimming” version of the microtensile test. The specimens were subjected to microtensile forces (BISCO Microtensile Tester, BISCO). The data was analyzed by three-way ANOVA and independent t-tests (p=0.05). Results: Er,Cr:YSGG laser irradiation exhibited similar µTBS values compared to that of conventional bur treatment, regardless of the adhesive system and type of treated dentin. The self-etch system revealed lower µTBS values, both with conventional and laser treatment techniques, compared to the etch-and-rinse adhesive in sound and caries-affected dentin (p<0.05). Conclusion: Er,Cr:YSGG laser irradiation did not negatively affect the bonding performance of adhesive systems to sound and caries-affected dentin.

SUMMARY:
The current study evaluated the bonding ability of composite to glass ionomer cement (GIC) using three different bonding systems. One hundred samples of composites bonded to GIC were prepared and divided into five groups. In Group A, the composite was bonded to GIC after the initial setting of the GIC being employed as a total-etch adhesive. In Group B, the self-etch primer was employed to bond composite to GIC before the initial setting of the GIC. In Group C, the self-etch primer was employed to bond composite to the GIC after the initial setting of the GIC. In Group D, the GIC-based adhesive was employed to bond composite to the GIC before the initial setting of the GIC. In Group E, the GIC-based adhesive was employed to bond composite to the GIC after the initial setting of the GIC. Shear bond strength analysis was performed at a crosshead speed of 0.5 mm/minute. The results were tabulated and the statistical analysis was performed with one-way ANOVA; the Tukey’s test showed that the bond strength of composite to GIC was significantly higher for the self-etch primer group employed on unset GIC and the GIC-based adhesive group employed on the set GIC for bonding composite to GIC.

SUMMARY:
Recently, self-etch adhesive systems, the one-step (all-in-one) and two-step adhesive systems have become widely utilized due to their simplified application procedures and low technique sensitivity. In the current study, in order to understand the effects on shelf life of the two types of self-etch adhesives, the effects from storage temperature and time period on the alteration stage of 10-methacryloxydecyl dihydrogen phosphate (MDP)-based, a one-step adhesive (all-in-one adhesive system) and an MDP-based self-etching primer (two-step adhesive system) were examined. Clearfil Tri-S Bond (TSB), an MDP-based one-step adhesive (all-in-one adhesive system), and Clearfil Mega Bond Primer (MBP), an MDP-based self-etching primer (two-step adhesive system), were used. Both TSB and MBP, received within two days after they were produced, were immediately stored at 8°C, 20°C or 40°C for 1, 3, 7 and 14 weeks, respectively. At the end of each storage period, 13C NMR observations were performed by an EX-270 spectrometer. In addition, NMR observations of TSB and MBP were immediately performed within two days, after both were produced as a control. The effects from the storage temperature and time period on the alteration rate and stage of TSB and MBP were examined by determining the amount of hydrolyzed 2-hydroxyethyl methacrylate (HEMA) and MDP in both materials. Specimens bonded to dentin by using TSB or MBP in different alteration stages were prepared. The degradation stage effect of TSB or MBP on bond durability was examined by measuring the shear bond strength before and after thermocycling (20,000 times). With increases in storage temperature and time period, the relative intensities of the NMR peak “e” assigned to both methylene carbons in the ethylene glycol (EG) and to the NMR peak “z” assigned to the terminal methylene carbon bonded to the hydroxy group in the 10-hydroxydecyl dihydrogen phosphate (HDP) produced by the hydrolysis of the ester portion in HEMA or MDP, respectively, increased. The alteration stages of TSB and MBP were strongly dependent on storage temperature and time period. When TSB or MBP, stored at 40°C for 14 weeks, was applied to dentin, specific decreases in mean bond strength were observed in both adhesive systems. However, the application of thermocycling did not exhibit any specific decreases in the mean bond strength, even though the alteration stage of TSB and MBP progressed. From the results of the current study, storage temperature and time period significantly affect the alteration rate and stage of TSB and MBP. However, TSB and MBP exhibit expectant bond strength and bond durability when both are stored below 20°C.

SUMMARY:
The current study evaluated the effect of 2% chlorhexidine digluconate (CHX) on the immediate and six-month resin-dentin bond strength (BS) and nanoleakage pattern (NL) of etch-and-rinse adhesives when applied in aqueous or associated to the phosphoric acid conditioner. The occlusal enamel of 42 caries-free extracted molars was removed in order to expose a flat dentin surface. In groups 1 and 2 (control–C), the surfaces were acid etched with conventional phosphoric acid, and the adhesives Prime&Bond NT (PB) and Adper Single Bond 2 (SB) were applied after rinsing, drying and rewetting with water. In groups 3 and 4 (Ac/CHX), the adhesives were applied in a similar manner, however, a 2% CHX-containing acid was previously applied. In groups 5 and 6 (CHX), the adhesives were applied according to the control group; however, the rewetting procedure was performed with an aqueous solution of 2% CHX for 60 seconds. Composite buildups (Opallis, FGM) were constructed incrementally, and the specimens were longitudinally sectioned in the “x” and “y” directions to obtain bonded sticks (0.8 mm2) to be tested in tension at 0.5 mm/minute immediately or after six months of water storage. For NL, two bonded sticks from each tooth were coated with nail varnish, placed in silver nitrate and polished down with SiC paper. Resin-dentin interfaces were analyzed by EDX-SEM. The BS and NL data from each adhesive was submitted to two-way repeated measures ANOVA and Tukey’s test (a=0.05). After six months of water storage, significant reductions in BS were observed for both adhesives in the control group (p<0.05). When Ac/CHX or CHX was used, no significant reductions in BS were observed for both systems. Nanoleakage was more evident in the control group than in the experimental groups (p<0.05), even after six months. The use of CHX in an aqueous solution or associated with the acid conditioner was effective for reducing degradation of resin-dentin bonds after six months of water storage.

SUMMARY:
The current paper describes a modified treatment procedure for a traumatized mandibular left second molar resulting in a crown-root fracture and root perforation with the fracture line below the gingival attachment and alveolar bone crest. After the mobile crown-root fragment was extracted, the root perforation was obturated with mineral trioxide aggregate (MTA), and the subgingival defect was directly repaired with polyacid-modified resin composites (Ionosite Baseline). A 24-month recall showed no evidence of periodontal inflammation and no adverse symptoms, and the treated tooth exhibited good healing and normal function.