A quantitative and visual examination of sealed restorative specimens following exposure to artificial aging.

Low-viscosity polymer resins, or surface sealants (SSs), have been utilized as a means of finalizing the polishing step following the placement of composite resin restorations. The aim of this study was to measure the surface roughness (Ra) of composite resins treated with different SSs before and after exposure to an accelerated artificial aging protocol. The study included 5 experimental groups of composite resin discs (TPH Spectra ST) treated with different SSs (PermaSeal, Embrace WetBond Seal-n-Shine, OptiGuard, BisCover LV, and DuraFinish) and a control group consisting of untreated discs (n = 6 per group). The discs were prepared by inserting composite resin in 10 × 1-mm rings, covering the ring and material with a transparent strip, compressing the assembly between glass slides, and polymerizing through the slides on each side for 40 seconds with an LED curing light. Each disc except for the control specimens received a coating of the selected SS followed by application of a transparent matrix strip and then light polymerization for 20 seconds using an LED light source. Surface roughness measurements were obtained with a digital contact profilometer at baseline (immediately after polymerization) and following exposure to a thermocycling regimen to simulate aging. The data were analyzed using 2-way analysis of variance and post hoc Student-Newman-Keuls test with significance set at P < 0.05. There were no statistically significant differences among the groups at baseline. There were no statistically significant differences between the baseline and post-thermocycling Ra measurements except among the DuraFinish specimens, which were significantly rougher than all other groups after accelerated artificial aging. The use of SSs for the initial insertion and possibly for the long-term maintenance of composite resins could be minimally beneficial for restoration maintenance if a transparent covering medium is utilized during polymerization. However, due to the effects caused by formation of an oxygen-inhibited layer of unpolymerized monomers if a covering medium is not used, the results suggest the benefits do not offset the costs considering both gloss and Ra surface-testing parameters.

The effect of artificial ultraviolet light on the gloss of composite resin surface sealants.

This study evaluated how exposure to ultraviolet (UV) light affected the gloss of composite resins following application of resin-based surface sealants (SSs). Thirty composite resin discs were fabricated using cylindrical molds and randomly assigned to 1 of 5 SS groups (n = 6 each). Both sides of each disc received a polyester film clear matrix surface finish, and then rotary finishing and polishing procedures were performed on 1 side only. Six baseline measurements for each disc surface were performed using a 60-degree-angle gloss meter. The finished and polished side then received an SS application and was polymerized with an LED light through a polyester film matrix. Gloss measurements were then obtained. All specimens were then exposed to an artificial UV light source for a total of 382 hours, after which final gloss measurements were made. A 2-way repeated-measures analysis of variance and Student-Newman-Keuls pairwise multiple comparison tests revealed statistically significant differences between the SS materials and surface treatments (P < 0.05). No statistically significant (P > 0.05) differences were found between the surfaces that were mechanically finished and polished and those that only received a polyester film finish. However, all specimens exhibited significantly (P < 0.0001) higher gloss readings after SS application. Following UV exposure, all SS specimens exhibited significantly (P < 0.0001) lower gloss readings. The study results suggest that application of SSs to composite resin discs increases the gloss on a short-term basis; however, long-term exposure of SSs to an artificial UV light source might have a negative effect on the surface properties. Thus, dentists need to periodically evaluate composite resin restorations.

Microscopic evaluation of luting techniques for a fiber-reinforced post system.

This study assessed application techniques for cementation of fiber-reinforced posts (FRPs). The treatment groups were defined by FRP luting application techniques and included 5 groups of 10 simulated teeth each: 1, application of the cement on the post using a syringe; 2, application of the cement in the canal using a syringe; 3, application of the cement in the canal and on the post using a syringe; 4, application of the cement in the canal using a syringe/Lentulo spiral instrument; and 5, application of the cement in the canal using a syringe/Lentulo spiral and on the post using a syringe. A dual-curing, automixing cement was utilized as the luting agent. For each group, the canals were endodontically prepared using tapered hand and rotary files and obturated, and then the FRPs were cemented in place. All specimens were encased in acrylic and sectioned at 2 locations, creating 4 viewing surfaces: coronal (C), middle coronal (MC), middle apical (MA), and apical (A). The surfaces were examined using a stereomicroscope and digitized computer software. The efficacy of each FRP application technique was determined in terms of percentages of cement void area by group and by surface. Group 1 exhibited a significantly (P < 0.05) greater overall percentage of cement void area than all other groups. Group 2 exhibited the smallest overall percentage of void area, although the difference was not always statistically significant. There were no statistically significant differences among the surfaces in cement void area (P > 0.05) when the areas of the different groups were combined. The most efficacious cementation method was the injection of cement into the canal space with a syringe, while the use of a Lentulo spiral instrument was found to be an unnecessary step.

Evaluation of the marginal integrity of a bioactive restorative material.

This in vitro study evaluated the marginal microleakage of a bioactive restorative with other restorative materials in standard Class V preparations. Sixty previously extracted, noncarious human molars were randomly assigned to 3 experimental groups (n = 20): a bioactive composite resin, a universal hybrid composite resin, and a resin-modified glass ionomer restorative. Class V cavities were prepared on the facial or lingual surface of each tooth so that coronal margins were located in enamel and apical margins in cementum (dentin). After the cavity preparations were restored with the appropriate material, the specimens were artificially aged in water baths. The root apices were sealed with utility wax, the tooth surfaces were coated with nail varnish to within 1 mm of the restoration, and specimens were immersed in 1% methylene dye solution for 8 hours. The teeth were invested in clear polymer resin, sectioned longitudinally, and examined under a stereomicroscope to assess dye penetration. Nonparametric scores indicated that microleakage was significantly greater at the apical margins than the coronal margins for all groups (P > 0.0001). The specimens restored with the bioactive material exhibited greater microleakage at both the coronal and apical margins than did specimens restored with the composite resin or resin-modified glass ionomer material, although the differences were not statistically significant (P > 0.05). Based on the results of the present study, the type of restorative material did not appear to have a significant influence on microleakage. Rather, the marginal position (coronal versus apical) of the restoration was the determining factor in microleakage.

An evidence-based review of dental matrix systems.

The restoration of proximal surface cavities, originating from Class II carious lesions, to "normal" anatomical specifications is a fundamental objective for the dental practitioner. Cognitive interpretation of tooth morphology attained from evidence-based resources, together with the necessary psychomotor skills for correct design and completion, are considered essential strategies for restoration success. Also, the visualization of the original tooth structure, if present, should substantially benefit the dentist in the creation of a clinically satisfactory restoration. The purpose of this evidence-based review is to define the cause and effect of decisions based on optimum treatment standards of care for the patient. The concepts of form and function, as related to the oral environment, and the consequences of unsatisfactory dental restorative care will be scrutinized. This article will identify and explain the different challenges and solutions for restoration of dental proximal lesions and provide an overview of past, present, and future procedures.

Effect of occlusal calculus utilized as a potential "biological sealant" in special needs patients with gastric feeding tubes: a qualitative in vitro contrast to pit and fissure sealant restorations.

The aim of this case report and in vitro investigation was to evaluate the marginal microleakage of intact occlusal calculus of primary molars extracted from a special needs patient who received nutrition via a gastric feeding tube. An adolescent with a history of developmental disturbance presented for routine dental care in a hospital facility. Prophylaxis was performed, and 2 mandibular permanent molars were restored. Five primary molars were extracted due to mobility and delayed retention. Heavy deposits of intact calculus were present on the occlusal surfaces of the primary teeth. The extracted teeth were immersed in methylene blue dye solution, invested in acrylic resin, sectioned into blocks, and photographed at 20× and 40× magnification. Previously photographed calculus-free molars with pit and fissure sealants were reviewed and served as contrasting "restorations." The occlusal calculus on the primary teeth extracted from the patient absorbed the dye, while the comparison teeth containing pit and fissure sealants exhibited varying degrees of marginal dye penetration (microleakage). No marginal microleakage was noted in the calculus specimens, indicating that this substrate may serve as a "natural" occlusal surface sealant and that its removal from occlusal surfaces during routine oral prophylaxis may be unnecessary.

Determination and Correlation of Depth of Cure of a New Composite Resin Delivery System.

OBJECTIVES: To quantify the depth of cure (DOC) of a composite resin system using two different testing criteria. METHOD AND MATERIALS: The DOC testing employed two different experimental protocol: 1) Forty-eight previously extracted human molars were randomly assigned to four groups of twelve each (n = 12): Group 1 SonicFill composite resin system, shade A1; Group 2 SonicFill, shade A3; Group 3 Herculite Ultra composite resin, shade A1; Group 4 Herculite Ultra, shade A3. Cylindrical cavities (4.0 mm diameter and 10 mm depth) were prepared at the tooth CEJ, in a mesiodistal direction. The preparations were filled with each composite resin material in one bulk increment and polymerized with a LED light for 20 seconds. After 5 minutes, the occlusal surfaces of the teeth (specimens) were ground flat until the composite was exposed in a transverse plane. The uncured (soft) composite was scraped away, using a "modified" ISO 4049 DOC specification, and the remaining cured (hard) material was measured. Three measurements, at different positions of the specimen, were performed, for a total of thirty-six measurements per specimen group. The measurements were averaged and divided by fifty percent, arriving at the final DOC for each specimen. 2) A DOC testing protocol was performed using a two-piece (4.0 mm x 10.0 mm) custom-made Teflon device (mold). The groupings duplicated the previous experimental protocol. The mold was filled with each composite resin material in one bulk increment to a 10 mm length (depth). Excess composite material was removed, followed by placement of a Mylar strip over the external orifice. The composite resin specimen was light-polymerized for 20 seconds. Again, the uncured (soft) composite was scraped away, with the same measurement protocol followed as in method 1. Statistical analyses were conducted using ANOVA tests at a p < .05 level of significance. RESULTS: Statistical differences were exhibited between the two different DOC methodologies, extracted teeth versus the Teflon device. Considering each method, the SonicFilTM composite revealed significantly greater DOC compared to the Herculite Ultra composite resin. Also, significant differences were displayed between the Al compared to the A3 shades, with the A1 (lighter) shades exhibiting greater DOC. CONCLUSION: The prepped teeth seemed a more realistic DOC testing approach due to the variables of light interaction of the composite resin to either tooth substance (enamel/dentin) versus using the Tefion mold, although greater DOCs were recorded using the manufactured device. The SonicFill composite system did reveal greater DOC compared to the Herculite Ultra composite regardless of experimental method or material shade.

Fracture resistance of permanent anterior incisors using fiber-reinforced composite posts.

This in vitro study investigated whether permanent anterior incisors that are endodontically treated with cemented fiber-reinforced composite (FRC) posts without additional canal preparation can potentially increase the resistance to fracture and thus reduce the rate of clinical failure in root canals. Extracted human permanent maxillary central incisors (n = 120) were randomly assigned to 2 experimental groups (n = 60): thermocycled (Group 1) and non-thermocycled (Group 2). These 2 groups were then further divided into 3 subgroups (n = 20). Subgroup 1.1 specimens had root canals prepared and obturated with FRC posts placed. Subgroup 1.2 specimens were prepared and obturated, but did not receive posts. Subgroup 1.3 specimens did not receive root canal preparation, and served as a control. The same processes were repeated for Subgroups 2.1, 2.2, and 2.3, respectively. Significant differences were found between the thermocycled and the non-thermocycled subgroups. Subgroup comparison within the thermocycled group (Group 1) showed significantly higher fracture resistance values for the teeth with post cementation (P < .0001).

Effect of adhesive agent and fissure morphology on the in vitro microleakage and penetrability of pit and fissure sealants.

OBJECTIVE: To evaluate the effect of adhesive agents and fissure morphology on the microleakage and penetrability of pit and fissure sealants. METHOD AND MATERIALS: Sealants used in this study included Aegis (Bosworth), conseal f (Southern Dental Industries), and Admira Seal (Voco). Adhesive agents included Optibond Solo Plus (sds/Kerr) and Clearfil S3Bond (Kuraray). Ninety extracted permanent molars were randomly assigned to 9 groups combining sealant and adhesive agent materials. A sealant and control group (phosphoric acid etch only) was also included. Dye penetration (microleakage), penetrability, and fissure morphology assessment was performed for the treatment groups through microscopic evaluation. RESULTS: Significant (P = .003) differences in microleakage were exhibited, with the Aegis + control and Aegis + Optibond Solo Plus groups displaying less leakage, while significant (P = .03) differences were also noted between groups regarding penetrability. Fissure morphology was not a significant (P = .82) factor affecting microleakage; however, fissure type did significantly (P < .001) impact penetrability. No correlation was found between the extent of microleakage and penetrability. CONCLUSION: Application of sealants using phosphoric acid as a conditioning agent revealed superior results, while the use of adhesives was found to be unnecessary.

The potential effects of pH and buffering capacity on dental erosion.

Soft drink pH (initial pH) has been shown to be a causative factor--but not necessarily the primary initiating factor--of dental erosion. The titratable acidity or buffering capacity has been acknowledged as playing a significant role in the etiology of these lesions. This in vitro study sought to evaluate five different soft drinks (Coca-Cola Classic, Diet Coke, Gatorade sports drink, Red Bull high-energy drink, Starbucks Frappucino coffee drink) and tap water (control) in terms of initial pH and buffering capacity. Initial pH was measured in triplicate for the six beverages. The buffering capacity of each beverage was assessed by measuring the weight (in grams) of 0.10 M sodium hydroxide necessary for titration to pH levels of 5.0, 6.0, 7.0, and 8.3. Coca-Cola Classic produced the lowest mean pH, while Starbucks Frappucino produced the highest pH of any of the drinks except for tap water. Based on statistical analysis using ANOVA and Fisher's post hoc tests at a P < 0.05 level of significance, Red Bull had the highest mean buffering capacity (indicating the strongest potential for erosion of enamel), followed by Gatorade, Coca-Cola Classic, Diet Coke, and Starbucks Frappucino.

The erosive potential of soft drinks on enamel surface substrate: an in vitro scanning electron microscopy investigation.

AIM: Using scanning electron and light microscopy, this study qualitatively evaluated the erosive potential of carbonated cola beverages as well as sports and high-energy drinks on enamel surface substrate. METHODS AND MATERIALS: Beverages used in this study included: Coca Cola Classic, Diet Coke, Gatorade sports drink, Red Bull high-energy drink, and tap water (control). Extracted human permanent molars free of hypocalcification and/or caries were used in this study. The coronal portion of each tooth was removed and sectioned longitudinally from the buccal to the lingual surface. The crown sections were embedded in acrylic resin, leaving the enamel surfaces exposed. Following finishing and polishing of all surfaces, one side was covered with red nail varnish while the remaining side was exposed to individual beverage immersion for 14 days, 24 hours per day, at 37 degrees C. The specimens were evaluated for enamel surface changes using scanning electron and light microscopy. RESULTS: Enamel specimens exhibited visual surface changes following immersion in the test beverages with Red Bull and Gatorade revealing the most striking surface morphological changes. Specimens subjected to Coca Cola Classic and Diet Coke immersion also displayed irregular post-treatment surface morphology. CONCLUSIONS: As verified by microscopic evaluation, all test beverages displayed enamel dissolution in the following order: Red Bull>Gatorade>Coca-Cola Classic>Diet Coke.

Effect of preparation technique, fissure morphology, and material characteristics on the in vitro margin permeability and penetrability of pit and fissure sealants.

PURPOSE: The purpose of this study was to evaluate the effect of material characteristics, preparation techniques, and fissure morphology on the microleakage and penetrability of pit and fissure sealants. METHODS: Sealants used in the study included: (1) Aegis; (2) Conseal f; (3) Admira Seal; (4) Triage; and (5) Delton Opaque. A total of 100 extracted permanent molars were randomly assigned to 10 groups that combined the materials and preparation technique (pumice prophylaxis and air abrasion). Following sealant placement, the specimens were: (1) subjected to thermal-cycling and dye immersion; (2) invested in acrylic; (3) sectioned for microscopic examination; and (4) assessed for dye penetration (microleakage) and penetrability. RESULTS: Significant differences in microleakage were seen. Aegis using pumice-prophylaxis surface pretreatment showed significantly less leakage than the other groups. Significant differences were also exhibited between groups seen regarding sealant penetrability, with Delton and Triage (pumice prophylaxis) revealing the greatest values. Fissure morphology was not a significant factor regarding microleakage. Morphology did significantly impact sealant penetrability, however, with u-type fissures displaying the greatest values. No correlation was found between the extent of microleakage and sealant penetrability. CONCLUSION: Material characteristics and fissure morphology were significant factors regarding sealant success, while surface preparation did not play an important role in sealant microleakage or fissure penetrability.

Effect of carbonated beverages, coffee, sports and high energy drinks, and bottled water on the in vitro erosion characteristics of dental enamel.

PURPOSE: This study evaluated the effect of carbonated and non-carbonated beverages, bottled and tap water, on the erosive potential of dental enamel with and without fluoride varnish protection. MATERIALS AND METHODS: Beverages used in this study included: Coca Cola Classic, Diet Coke, Gatorade sports drink, Red Bull high-energy drink, Starbucks Frappuccino coffee drink, Dasani water (bottled), and tap water (control). Enamel surfaces were coated with Cavity Shield 5% sodium fluoride treatment varnish. Twenty-eight previously extracted human posterior teeth free of hypocalcification and caries were used in this study. The coronal portion of each tooth was removed and then sectioned transverse from the buccal to lingual surface using a diamond coated saw blade. The crown sections were embedded in acrylic resin blocks leaving the enamel surfaces exposed. The enamel surfaces were polished using 600 to 2000 grit abrasive paper and diamond paste. Test specimens were randomly distributed to seven beverage groups and comprised 4 specimens per group. Two specimens per beverage group were treated with a fluoride varnish while 2 specimens did not receive fluoride coating. Surface roughness (profilometer) readings were performed at baseline (prior to fluoride treatment and immersion in the beverage) and again, following immersion for 14 days (24 hours/day). The test beverages were changed daily and the enamel specimens were immersed at 37 degrees C. Surface roughness data was evaluated using multiple factor ANOVA at a significance level of p<0.05. RESULTS: Results showed that Coca-Cola Classic, Gatorade and Red Bull with/without fluoride revealed the highest post-treatment surface roughness measurements. Coca-Cola Classic, Diet Coke, Gatorade, and Red Bull all showed significantly higher post treatment readings than StarBucks coffee, Dasani water, and tap water. Fluoride varnish was not a significant impact factor; however, beverage (type) and exposure time were significant impact variables. CONCLUSION: Both carbonated and non-carbonated beverages displayed a significant erosive effect on dental enamel; however, fluoride varnish treatments did not demonstrate a significant protective influence on enamel surfaces.

Radiometric and spectrophotometric analysis of third generation light-emitting diode (LED) light-curing units.

AIMS: Light-emitting diode (LED) polymerization of dental restorative materials has become increasingly popular. However, individual light-curing unit (LCU) functions (intensity and/or wavelength emission) may not conform to manufacturer specifications due to quality control issues. The purpose of this study was to evaluate the quality of irradiance, in terms of power density (intensity) and spectral distribution (peak wavelength), emitted from LED and quartz-tungsten halogen (QTH) LCUs in vitro. The battery expenditure of these LED units was also tested. METHODS AND MATERIALS: The intensity and spectral distribution from four third generation LED (Smartlite PS, Coltolux LED, radii Plus, Diopower) and one QTH (Schein Visible Cure) light sources were measured using six different dental curing light meters (Coltolux, Cure Right, Demetron 100, Demetron LED., Hilux, and Light Meter-200) and a visible-ultraviolet light spectrophotometer (Hitachi Elmer-Perkins). The battery life was also plotted for each light source following a 1500 second duration period. The data obtained from radiometric and spectrophotometric analysis was compared to manufacturer specifications. RESULTS: Radiometric evaluation revealed LED light units tested did not satisfy manufacturer claims for minimum intensities. Spectral emissions from the LED light sources did meet manufacturer requirements. No clinically appreciable battery drain was evidenced from testing all re-chargeable LED units. CONCLUSION: Despite limitations LED technology appears to be an effective alternative for curing of light-activated esthetic restorative materials. Additional advantages associated with LED curing lights include ergonomic handling capabilities, negative heat generation, and minimal maintenance concerns.

Effect of single step adhesives on the marginal permeability of Class V resin composites.

This in vitro study evaluated the coronal and apical marginal microleakage of four self-etch, seventh generation adhesive systems. Sixty non-carious human molars were randomly assigned to four groups (n = 12). Class V cavities were prepared on the facial or lingual surface of each tooth with coronal margins in enamel and apical margins in cementum (dentin) at the cementoenamel junction. The preparations were restored using four self-etch adhesive systems (iBond, G-Bond, Xeno IV and Clearfil S3 Bond) and a control (no adhesive), followed by insertion of Gradia Direct microfilled hybrid resin composite. The teeth (specimens) were thermocycled 1,000 cycles, immersed in 1% methylene blue dye for 24 hours and invested in acrylic resin. The specimen blocks were then sectioned longitudinally, with dye penetration (microleakage) examined using a 20x binocular microscope. Coronal and apical margins were scored separately for microleakage using a 0-3 ordinal ranking system. Data were analyzed using non-parametric tests at a p < 0.05 level of significance. A comparison of adhesive and control groups at the coronal and apical margins revealed that significant (p < .0001) differences were exhibited. At the coronal margin, Xeno IV revealed significantly less leakage than the other adhesives, with Clearfil S3 Bond exhibiting significantly less leakage at the apical margin. Groups with no adhesive treatment (control) showed significantly greater leakage at both the coronal and apical margin locations. A Wilcoxon signed rank test showed no significant differences at the coronal compared to the apical margins of the four adhesive systems and control tested.

Effect of new generation surface sealants on the marginal permeability of Class V resin composite restorations.

This study evaluated, in vitro, the effectiveness of 5 surface sealants (Biscover, Optiguard, Seal-n-Shine, PermaSeal and DuraFinish); 1 pit and fissure sealant (Helioseal) and 1 dentin bonding agent (Adper Scotchbond MultiPurpose Adhesive) on the marginal sealing ability of Class V hybrid resin composite (Esthet.X) restorations. Ninety-six non-carious human molars were randomly assigned to 8 groups (n=12). Class V cavities were prepared on either the facial or lingual surfaces, with coronal margins in enamel and apical margins in cementum (dentin), and restored following manufacturers' instructions. Following finishing and polishing procedures, the covering agents were applied to each restoration and adjacent tooth surface, except for the control group restorations, which were not sealed. The teeth were thermocycled, immersed in a 1% methylene blue dye solution, sectioned and analyzed for dye penetration (leakage) using a 20x binocular microscope. Microleakage was evaluated at the coronal and apical margins using an 0-3 ordinal grading scale. Non-parametric data was analyzed at a p< or =0.05 level of significance. The Kruskal-Wallis test showed a significant difference was exhibited among groups at the coronal margins, with Helioseal pit/fissure sealant and DuraFinish surface sealant exhibiting significantly less leakage than the control and Adper Scotchbond MultiPurpose adhesive. At the apical margins, DuraFinish surface sealant showed significantly less leakage than the Biscover, Seal-n-Shine and PermaSeal surface sealants or Helioseal pit/fissure sealant, Adper Scotchbond MultiPurpose adhesive and the control group. According to the Wicoxon signed-rank test, significantly greater leakage was revealed at the apical margins compared to the enamel margins of the material groups.

Alternative rubber dam isolation technique for the restoration of Class V cervical lesions.

This article describes an expedited, atraumatic technique of restoring cervical abrasion-erosion, abfraction or carious lesions using an alternative placement sequence of the dental rubber dam for adequate field isolation. As shown by this technique, the rubber dam retainer is modified and positioned on the tooth with subsequent placement of the dental dam material over theretainer and tooth. This technique saves time and provides good retraction of the gingival tissue and isolation of the cavity preparation from contamination (saliva, hemorrhage) that can potentially cause post-operative symptoms and possible restoration replacement.

Marginal permeability of self-etch and total-etch adhesive systems.

This study evaluated microleakage in vitro of self-etch and multi-step, total-etch adhesive systems. Ninety-six extracted non-carious human molars were randomly assigned to eight groups (n=12) and restored with different adhesive systems: Optibond Solo Plus, iBond, Adper Prompt L-Pop, Xeno III, Simplicity, Nano-Bond, Adper Scotchbond Multi-Purpose and Touch & Bond. Each group was treated following the manufacturer's instructions. Class V cavities were prepared on the facial or lingual surfaces of each tooth with coronal margins in enamel and apical margins in cementum (dentin). The teeth were restored with Z-100 resin composite. After polishing with Sof-Lex disks, the teeth were thermocycled for 1000 cycles and coated with nail varnish to within 1.0 mm of the restoration. The teeth were stained in 1% methylene blue dye for 24 hours and sectioned from the facial to lingual surface. Dye penetration (microleakage) was examined with a 20x binocular microscope. Enamel and dentin margin leakage was scored on a 0 to 3 ordinal scale. Data were analyzed using Kruskal-Wallis Analysis of Variance and Mann-Whitney U tests. Comparison of the adhesive groups at the enamel margin revealed: 1) Adper Scotchbond Multi-Purpose exhibited significantly less leakage than the other adhesive groups (except iBond); 2) among the self-etch adhesive groups, iBond exhibited significantly less leakage than Nano-Bond and 3) the other adhesive groups clustered intermediately. In contrast, there were no significant differences among the adhesive groups when the dentin margin was evaluated. A Wilcoxin signed rank test showed significantly less leakage at the enamel margins compared to the dentin margins of the eight adhesive systems tested. All data were submitted to statistical analysis at p<0.05 level of significance.

Evaluation of curing performance of light-emitting polymerization units.

The depth of cure of resin composites is affected by material physical qualities and polymerization source variables. This study evaluated the spectral distribution and intensity of light-emitting diode (LED) and conventional quartz-tungsten halogen curing units, with depth of cure as the testing parameter. The depth of cure was determined using a scraping test, modified from an International Organization for Standards protocol. The light energy spectral distribution (peak wavelength) from each curing unit was determined using a visible-ultraviolet light spectrophotometer. The intensity of each unit (LED and halogen) was measured using LED and conventional radiometers. Data analysis using ANOVA revealed significant differences between the curing units. Based upon depth of cure measurements, the LED units generally were more effective than the conventional halogen unit at polymerizing resin composite. Dentists should be aware that LED curing units offer portability, reduced heat production, and more consistent intensity output per life of the unit.

Effect of residual caries-disclosing solutions on microleakage of a dental adhesive system.

OBJECTIVE: The purpose of this in vitro study was to determine the effect of residual caries-disclosing dyes on a dentinal adhesive system and accompanying resin composite, using microleakage as the quantifying criterion. METHOD AND MATERIALS: The dye pretreatment groups (10 teeth in each group, n = 60) were as follows: Group 1, Caries Detector; group 2, Cari-d-tect; group 3, Seek; group 4, Snoop; group 5, To Dye For; and group 6, control (no dye pretreatment). Circular preparations were cut on the facial or lingual surface of each tooth. Caries-disclosing dyes were placed on the preparations; this was followed by treatment with 35% phosphoric acid etchant, application of a Single-Bond adhesive, and insertion of Z-100 hybrid resin composite. Following thermocycling, the teeth were sealed with nail varnish, placed in methylene blue dye, invested in acrylic resin, labeled, and sectioned. Leakage was examined (20x magnification) by dye penetration at the occlusal and gingival surface positions of the specimen blocks using an ordinal ranking system. The data were analyzed using two-way analysis of variance with P < .05 as the significance level. RESULTS: Results of the study showed that, at the occlusal surface position of the restorations, significantly greater leakage was exhibited by To Dye For compared to Snoop. At the gingival surface position, significantly greater leakage was exhibited by: (1) Caries Detector, Cari-d-tect, Seek, and To Dye For compared to the controls; and (2) To Dye For compared to Snoop. When comparing the same dye pretreatment groups with respect to occlusal versus gingival surface positions, significantly greater leakage was exhibited at the gingival surface positions, except for the control group. CONCLUSION: Our data showed that all dye groups leaked (except Snoop at the occlusal surface position), and significantly greater leakage was exhibited at the gingival surface position of all groups except the control. Snoop revealed the least leakage of all the dyes tested.