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Evaluation of toothbrush and generalized wear of luting materials.

PURPOSE: To evaluate (1) the wear rates of various types of luting materials by means of toothbrush and generalized wear tests, and (2) the relationship between interfacial gap and luting material wear. METHODS: NiCr inlays were cemented into cylindrical Class I cavities prepared on flattened extracted molars with various luting materials (composite, compomer, hybrid and conventional glass-ionomers, and zinc phosphate). They were stored in 37 degrees C water for 24 hours and then resurfaced with a 600 grit Si-C paper. Half the specimens were subjected to 100 minutes of toothbrushing with a 1.47 N load using an automated brushing device, and the rest of the specimens were subjected to three-body generalized wear test with a 75 N load and 1.2 Hertz for 133,333 cycles. Eight specimens were evaluated for each cement by both wear modes. Wear depths of the luting materials were measured with a profilometer. The data were statistically analyzed by two-way ANOVA, and differences between wear modes and among luting materials were analyzed by a Bonferroni test (P< 0.05). RESULTS: There were significant differences between the luting materials (P< 0.0001) and wear mode (P= 0.015) for wear depth but no significant interaction between luting material and wear mode (P= 0.1059). The wear values of the resin-based composite (6.4 +/- 3.1 microm) and compomer (6.2 +/- 2.4 microm) were significantly lower than those of the hybrid glass-ionomer (11.3 +/- 2.8 microm), the conventional glass-ionomer (11.1 +/- 4.4 microm), and the zinc phosphate (12.1 micro 1.7 microm) in the toothbrush wear. The wear value of the resin-based composite (6.5 +/- 3.1 microm) was significantly lower (P< 0.0001) than those of zinc phosphate (15.0 +/- 2.7 microm) and hybrid glass-ionomer (13.5 +/- 1.5 microm), but not significantly different from conventional glass-ionomer (10.1 +/- 3.9 microm) and compomer (10.2 +/- 2.5 microm) in the generalized wear.

Analysis of Variance↗

Clinical evaluation of different adhesive systems for restoring teeth with erosion lesions.

This investigation evaluated the performance of a resin-modified glass ionomer, a compomer, and a bonding system/composite combination for the restoration of cervical erosion lesions without cavity preparation. Forty-eight lesions (11 patients) were restored with a bonding agent/composite combination [Prime & Bond 2.1/PrismaTPH (P & B/TPH); DeTrey/Dentsply], a compomer (Dyract; DeTrey/Dentsply), or a light-curing glass ionomer (Fuji II LC; Fuji). The materials were randomly assigned to the patients in triplets. No cavity preparation was performed. The procedures strictly followed the manufacturers' instructions. The restorations were evaluated clinically, using modified USPHS criteria, and by quantitative scanning electron microscope (SEM) analysis, at baseline and 12 months. The clinical data were statistically evaluated with the Pearson chi-square test, the SEM data (criterion gap formation) were analyzed with the Mann-Whitney U-test and error rates method. Clinically, two restorations could not be evaluated. One Dyract restoration failed. With respect to marginal discoloration, recurrent caries and contour, no significant differences could be found between the materials. The surface texture of P & B/TPH and Dyract was significantly better than that of Fuji II LC at baseline and 12 months. Compared to P & B/TPH and Fuji II LC, Dyract revealed a significant decrease in marginal integrity between baseline and 12 months. In SEM analysis, gap formation was determined as follows: baseline, enamel interface: 4% Dyract= 4% Fuji >2% P & B/TPH and dentin interface: 11% Dyract >9% P & B/TPH >2% Fuji; 12 months, enamel interface: 15% Dyract >4% Fuji >3% P & B/TPH and dentin interface: 11% P & B/TPH >6% Fuji >5% Dyract. The error rates method revealed no significant differences, in general, between the three materials with regard to gap formation. In conclusion, the restorations of erosion lesions with different classes of adhesive materials were well retained after 12 months. None of the materials studied revealed superiority over the other materials. All materials revealed shortcomings with respect to either surface texture, marginal integrity or color stability clinically and for all materials gap formation was recorded in the SEM evaluation.

Acetone↗

Thermographic investigation of contemporary resin-containing dental materials.

OBJECTIVES: To measure the temperature rise induced during visible light curing of modern resin-containing dental materials and the effect of dentine sections in reducing this temperature rise. METHODS: A variety of newly introduced resin-containing materials were investigated, including flowable, packable and conventional hybrid composites, as well as a compomer and a resin modified glass ionomer material. The resin was packed into polytetrafluoroethylene (PTFE) moulds and cured for 40s. Temperature rises on the undersurface of the curing resin were measured using the Thermovision 900 infra-red scanning system. In the second part of the study, extracted, caries free teeth were sectioned into dentine disks of three thicknesses (0.7, 1.4 and 1.9 mm). Composite samples were overlaid by the disks and the insulating effect of dentine measured. RESULTS: The maximum temperature increases were: 43.1 degrees C (flowable composite), 32.8 degrees C (conventional composite), 32.8 degrees C (RMGI), 23.3 degrees C (compomer) and 22.4 degrees C (packable composite). CONCLUSIONS: There was a quantifiable amount of heat generated in resin-containing material during light curing. Dentine sections were good thermal insulators that significantly reduced temperature rises associated with resin composite photocuring.

Analysis of Variance↗

In vitro retentive strength of zirconium oxide ceramic crowns using different luting agents.

STATEMENT OF PROBLEM: In contrast to gold crowns, in vitro determination of the retentive strength of all-ceramic crowns is more difficult because components allowing connection to testing apparatus are not as easily integrated into the all-ceramic material. Nevertheless, retentive strength data are crucial for obtaining information about the potential clinical performance of luting cements for all-ceramic restorations. Therefore, a new in vitro model was necessary to evaluate the retentive strength of all-ceramic crowns. PURPOSE: The purpose of this in vitro study was to determine the retentive strength of 4 resin-cement systems, a compomer, a glass-ionomer cement, a resin-modified glass-ionomer cement, and a self-adhesive resin for luting zirconium oxide ceramic crowns. MATERIAL AND METHODS: One-hundred-twenty extracted human teeth were randomly divided into 12 groups (n = 10) and prepared in a standardized manner (5-degree taper, 3-mm occlusogingival height). All-ceramic crowns (Lava) were fabricated in a standardized manner for each tooth. The following cements and corresponding bonding regimens were used to lute the crowns to the teeth according to manufacturers' recommendations: CO, Compolute/EBS Multi; CO/RT, Compolute/EBS Multi/Rocatec; CB, Superbond C and B; CB/RT, Superbond C and B/Rocatec; CB/PL, Superbond C&B/Porcelain Liner M; PA, Panavia F; DC, Dyract Cem Plus/Xeno III; CH/PL, Chemiace II/Porcelain Liner M; RL, RelyX Luting, K/C, Ketac Cem/Ketac Conditioner; K, Ketac Cem; and RU, RelyX Unicem. After thermal cycling (5000 cycles, 5 degrees C-55 degrees C), the outer surfaces of the cemented zirconium oxide ceramic crowns were treated (Rocatec) to improve bonding and then placed into a low-shrinkage epoxy resin block (Paladur). The block/crown and tooth components for each specimen were connected to opposing ends of a universal testing machine so that crown retention could be measured. Crowns were removed from teeth along their path of insertion. The retentive surface area (mm 2 ) was determined individually for each tooth. Statistical analyses were performed using the Wilcoxon exact test, (alpha =.05) and a Bonferroni correction (alpha =.001). RESULTS: The median (minimum/maximum) retentive strength values (MPa) were as follows: CO, 1.7 (0.6/4.3); CO/RT, 3.0 (1.3/5.4); CB, 4.8 (3.7/7.9); CB/RT, 8.1 (4.2/12.7); CB/PL, 5.3 (3.7/10.2); PA, 4.0 (3.3/5.1); DC, 3.3 (2.1/5.6); CH/PL, 4.0 (1.3/6.3); RL, 4.7 (2.8/6.6); K/C, 1.8 (0.6/2.3); K, 1.9 (0.2/4.5); and RU, 4.8 (2.5/6.7). Superbond C&B (+ Rocatec) specimens showed the highest median retentive strength, but were not significantly different from Superbond C&B without Rocatec pretreatment of the all-ceramic crown's inner surface. Compolute specimens also did not benefit significantly from the Rocatec pretreatment. Within the materials used without pretreatment of the ceramic, Superbond C&B, Panavia, Dyract Cem Plus, RelyX Luting, and RelyX Unicem showed the highest median retentive strength values and were not significantly different. CONCLUSION: Within the conditions of this study, the compomer-cement, the resin-modified glass-ionomer cement, and the self-adhesive resin luting agent had the same level of retentive quality as the resin luting agents, Superbond C&B, and Panavia. Rocatec pretreatment of the ceramic surface did not improve the retentive strengths of Compolute and Superbond C&B.

Cementation↗

Retention of adhesive cement on the tooth surface after crown cementation.

STATEMENT OF PROBLEM: Adhesive cements increase crown retention, but it is unknown if traces of cement remain undetected on the tooth surface after clinical removal of excess cement, which could exacerbate plaque retention. PURPOSE: This study measured the surface area, volume, mean depth, and maximum depth of a resin composite and a compomer luting cement left adherent on the tooth surface after removal of excess cement, as judged clinically. METHODS AND MATERIAL: Four groups of specimens (n = 48) were prepared for full coverage crowns: group AC bonding alloy with chamfer finish line, group G gold alloy with chamfer finish line, group PC porcelain with a chamfer finish line, and group PS porcelain with a shoulder finish line. Two profiles of the mesial and distal surfaces of the teeth were carried out: (1) tooth with crown seated but not cemented and (2) tooth with the crown cemented in place. Two cements and 2 methods of cement removal were studied. RESULTS: A 4-way analysis of variance for cement, crown type, method of removal, and tooth surface morphology showed that significantly greater volumes and mean depth, but not surface areas, of resin composite cement remained adherent than compomer cement (P<.05). Among crown types, significant differences were found for cement volume (group G>AC, G>PC, G>PS), cement surface area (group AC>PC, G>PC, G>PS), and maximum cement depth (group G>AC). There was no significant difference between the 2 methods of cement removal. Significantly larger surface areas and maximum depths of cement were retained on the anatomically grooved mesial surface of the maxillary first premolars than on the ungrooved distal surface. CONCLUSION: Subclinical cement retention occurred after crown cementation, which was influenced by cement, crown type, and tooth surface morphology but not method of cement removal.

Adhesives↗

"No-bottle" vs "multi-bottle" dentin adhesives--a microtensile bond strength and morphological study.

PURPOSE: To compare the adhesive capability of the new adhesive Prompt L-Pop (ESPE) with that of two total-etch adhesive systems-EBS Multi (ESPE) and Prime&Bond NT (Dentsply). METHODS: Extracted human molars were bonded and prepared for microtensile dentin bond strength (microTBS) testing using Prompt L-Pop, EBS Multi, and Prime&Bond NT combined with Pertac II (composite) or Hytac Aplitip (compomer). Prompt L-Pop was applied using five different protocols: (1) as an "all-in-one" self-conditioning adhesive, as per manufacturer's instructions (LP); (2) as a self-etching primer combined with a separate bonding resin (LP/self-etch 2-step); (3) as a classical primer used upon etching dentin with phosphoric acid, followed by a bonding resin (LP/total-etch 3-step); (4) as a multi-application "all-in-one" self-conditioning adhesive (LP/multi-coat) to leave a visibly glossy dentin surface; and (5) as a filled adhesive, upon adding quartz fillers to its composition (LP/filled). After 24h of storage in water at 37 degrees C the microTBS were measured in an Instron machine. Corresponding interfaces of the same specimens were micromorphologically analyzed using SEM and TEM. RESULTS: When used with a composite resin, LP/filled and LP/multi-coat resulted in significantly higher microTBS than LP. The addition of an extra adhesive bonding resin (LP/self-etch 2-step) had no effect on bond strength. The use of Prompt L-Pop as a primer of a fourth-generation adhesive (LP/total-etch 3-step) replacing the EBS Multi primer, resulted in lower bond strengths than those of the original EBS Multi. LP/multi-coat showed similar microTBS to Prime&Bond NT (P&BNT). When used with a compomer, LP exhibited higher bond strengths than when used with the resin composite and was as effective as the experimental groups LP/filled and LP/multi-coat and the control group P&BNT. The SEM evaluation showed an inconsistent hybrid layer for the LP specimens, whereas in both the LP/filled and LP/multi-coat specimens a hybrid layer was clearly evident. Under the TEM all groups displayed dentin hybridization with dissolved smear plugs in the specimens that had been conditioned with Prompt L-Pop without a separate etching step. In many tubules of specimens conditioned with LP (as per manufacturer's instructions), fillers of the resin composite were present within the dentinal tubules. CONCLUSIONS: When combined with a resin composite, Prompt L-Pop resulted in statistically lower bond strengths when applied in one layer than when applied in multiple layers. Prompt L-Pop also resulted in higher bond strengths when used with a polyacid-modified composite resin than with a composite resin. When applied in multiple coats, Prompt L-Pop results in bond strengths that are not statistically different from those of Prime&Bond NT, a total-etch adhesive.

Acid Etching, Dental↗

Bacterial microleakage and pulp inflammation associated with various restorative materials.

OBJECTIVES: Many restorative materials are claimed to be successful in preventing bacterial microleakage and minimizing pulp inflammation. However, information regarding the in vivo performance of materials in comparison with each other is limited. The aim of this study was to evaluate and compare the pulp response of nine restorative materials when placed in non-exposed monkey cavities. METHODS: 279 standardized non-exposed Class V cavities, were prepared into buccal dentin. Cavities were restored with a number of materials in the following categories: Zinc oxide eugenol (ZnOE), Calcium hydroxide [Ca(OH)(2)], zinc phosphate (ZP), Resin-modified glass ionomer (RMGI), Composite resin (CR), Bonded amalgam (BA), Gutta-percha (GP), Compomer and Silicate. Pulp tissues were collected and evaluated at short, intermediate and long-term intervals according to ISO guidelines; employing histomorphometric analysis, Spearman's rho and ANOVA statistics. Pulp responses were categorized according to FDI, ISO and ADA standards. Bacteria were detected using McKay stains. RESULTS: Pulp inflammation was found to be correlated to bacterial microleakage around the restoration (p < or =0.0001). The frequency of bacterial microleakage was found to vary between restorative materials (p < or =0.0001). In rank order of preventing bacterial microleakage from best to the worst; RMGI (100%), BA (88%), ZnOE (86%), CR (80%), GP (64%), Ca(OH)(2) (58%), compomer (42%), silicate (36%) and ZP (0%). SIGNIFICANCE: The most effective restorative materials to prevent bacterial microleakage and pulp injury from inflammatory activity were RMGI, BA, ZnOE and CR restorations.

Analysis of Variance↗

Effect of different luting materials on the marginal adaptation of Class I ceramic inlay restorations in vitro.

OBJECTIVES: The aim of this in vitro study was to assess the marginal adaptation of prefabricated Class I ceramic inlay restorations placed with various luting materials. METHODS: Forty-two standardized occlusal cavities were prepared in extracted human molars with diamond burs exactly corresponding to the dimensions of prefabricated glass ceramic inlays. The prepared teeth were randomly assigned to seven groups of six teeth each and restored using (1). the composite resin Tetric Ceram in increment technique [Group I] or (2). ceramic inlays (Cerana) luted with: the composite based materials Dual Cement [Gr. II] and Panavia 21 [Gr. III], the compomer material Dyract Cem [Gr. IV], Dyract Cem with additional use of Prime & Bond 2.1 [Gr. V], the silicophosphate cement Trans-Lit [Gr. VI], or the ethylcyanoacrylate Cyano-Veneer [Gr. VII]. Marginal adaptation was evaluated by SEM-analyses before and after thermal cycling (2500 cycles; 5-55 degrees C) and mechanical loading (100N; 500000 cycles) using replica models. Kruskal-Wallis H-test and Mann-Whitney U-test were used for statistical analyses. RESULTS: Group I (increment technique) as well as Groups II-V (inlay technique) revealed high percentages of perfect marginal adaptation in over 95% of the analyzed margins, both before and after thermo-mechanical loading. Statistical significant differences could not be detected within these groups. All inlays luted with silicophosphate cement (Group VI) and four of six inlays applied with Cyano-Veneer (Group VII) fractured under occlusal load. SIGNIFICANCE: A stable bonding to the enamel and to the ceramic inlay was achievable with the composite luting resins Dual Cement and Panavia 21 as well as with the compomer based luting material Dyract Cem but not with the use of the silicophosphate cement Trans-Lit or the ethylcyanoacrylate Cyano-Veneer.

Compomers↗

A new screening test for toxicity testing of dental materials.

OBJECTIVES: The development of a micro plate assay for cytotoxicity testing of dental materials based on a bioassay using brine shrimp larvae (artemia salina) as sensitive organisms. METHODS: Brine shrimp larvae are commonly used for cytotoxicity assays in pharmacology. These larvae are sensitive to toxic substances. The ratio between dead larvae (no motility) and living larvae (high motility) in comparison to a control without any toxic substances is used to estimate the toxicity of the test solutions. The test materials (Arabesk((R)), Solitaire((R)), Pertac((R)) II, Tetric((R)), Herculite((R)) and the compomer materials Dyract((R)), Hytac((R)), Compoglass((R))) were polymerized and consecutively milled. After incubation of 1g in 4ml distilled water at 37 degrees C for 48h, the solid materials were separated by centrifugation. The solutions were equibrilated with NaCl to a salt content of 25g/l. Aliquots of 200microl were distributed in eight micro wells and 50microl of a artemia salina containing (n=8-14) solution were added to each well. As controls eight wells with 250microl salt solution containing a comparable number of brine shrimp were used. At baseline, after 2, 5, 24 and 48h, the dead shrimp were counted using a stereo microscope. Finally all shrimps were sacrificed using Na-acid (5%) and counted to get the number of shrimps per well. RESULTS: All compomers and Solitaire caused 100% brine shrimp lethality after 24h and showed significantly (p<0.01, signed rank test) higher toxicities than the remaining composites. With the exception of Pertac II, all composites showed significantly higher toxic values than the control. Pertac II did not show any differences from the controls used. CONCLUSIONS: This new technique has some advantages for toxicity testing of restorative materials, because it can quickly be carried out at low costs. The disadvantage is the high quantity of material used and the low sensitivity.

Animals↗

Evaluation of the F2000 bonding procedure: a high resolution SEM study.

OBJECTIVES: The aim of this study was to define the morphological bonding of the F2000 Restorative System (3M Dental Product) to enamel and dentin. For this purpose, high resolution scanning electron microscope (SEM) in conjunction with a tensile bond strength analysis was used to correlate the morphological findings to the bonding potential. Scotchbond 1 (SB1) adhesive system was utilized as a control. MATERIALS AND METHODS: Teeth were prepared in vivo and prepared as: (1) F2000 PA for 15s, (2) F2000 PA for 30s, (3) 35% phosphoric acid for 15s and SB1 and (4) 35% phosphoric acid for 30s and SB1. All teeth were then restored with the F2000 compomer restorative material, extracted, sectioned and analyzed by means of a field emission in-lens SEM (FEISEM). The conditioning/etching patterns of the two adhesive systems were also evaluated in vitro on dentin disks in order to show high resolution details of every single step of the bonding procedure. RESULTS: FEISEM images showed a repetitive pattern of the enamel crystals with several microporosities after the 30s application of F2000 PA; moreover a good adaptation of the adhesive resin on the conditioned enamel was observable. FEISEM analysis of the dentin surface revealed no evidence of a smear layer after the application of F2000 PA for 30s. Residual smear plugs were partially obliterating the tubule orifices when F2000 PA was used, while they were completely absent after etching with 35% phosphoric acid. The total etching technique revealed open tubules and resin tags formation after the application of SB1. CONCLUSIONS: The one step etching/priming/bonding procedure of the F2000 PA showed favorable results at ultra-structural level when applied on both the enamel and the dentin surface for 30s (as per manufacturers' instructions), but the bond strength analysis showed higher values of bonding of the F2000 compomer when the SB1 adhesive agent (after etching with 35% phosphoric acid) was used (7.7+/-2.2 vs 19.0+/-4.4MPa).

Acid Etching, Dental↗

Bonded molar tubes--an in vitro evaluation.

This study aimed to evaluate the mean shear bond strength of molar tubes with micro-etched bases bonded with either a compomer (Ultra Band-Lok), a resin-modified glass ionomer cement (3M Multi-Cure or Fuji Ortho LC), or a light-cured resin adhesive (Transbond). The amount of adhesive remaining on the tooth surface following tube removal was assessed also. Finally, survival time of molar tubes bonded with each bonding agent was assessed following simulated mechanical fatigue in a ball mill. A total of 120 extracted human third molars were collected and randomly divided into 4 test groups. Thirty teeth (20 to assess debonding force and 10 to assess survival time) were bonded with each adhesive according to the manufacturers' instructions. Debonding was carried out using a Nene M3000 testing machine with a crosshead speed of 0.5 mm/min. The mean shear bond strength of tubes bonded with Transbond was significantly less than that of those bonded with 3M Multi-Cure (P = .0036) or Fuji Ortho LC (P < .0001). Tubes bonded with Ultra Band-Lok also had significantly lower mean shear bond strength than those bonded with Fuji Ortho LC (P = .020). Distribution of adhesive remnant index scores only differed significantly between tubes bonded with 3M Multi-Cure or Transbond. Only I molar tube, bonded with Transbond, debonded in the ball mill at 5 hours, but at 50 hours there was no significant difference in the survival time of tubes bonded with any of the bonding agents. Compomer or resin-modified glass ionomer cements appear to be viable alternatives to light-cured resin adhesive for bonding molar tubes.

Acrylic Resins↗

The influence of finishing time on the marginal seal of a resin-modified glass-ionomer and polyacid-modified resin composite.

The aim of this study was to compare the effect of immediate and delayed finishing on the microleakage of encapsulated resin-modified glass-ionomer, Fuji II LC and a polyacid-modified resin composite, Dyract compomer at both the enamel and dentine margins. Standardized Class V cavities were prepared along the cemento-enamel junction on buccal and palatal surfaces of 24 freshly extracted non-carious premolars. Equal numbers of buccal and palatal cavities in each group were restored with Fuji II LC and Dyract compomer following the manufacturer's instructions. The groups with delayed finishing were restored 1 week earlier, stored in saline at 37 degrees C and finished on the same day as the groups with immediate finishing. The specimens were then thermocycled 500 times and subjected to dye penetration testing. The results showed that both materials leaked more at the dentine than enamel margins for both regimes of finishing methods. There was no statistical difference in the microleakage of Dyract finished immediately or later at enamel and dentine margins and Fuji II LC finished immediately or later in dentine. However, a statistical difference existed between the microleakage in Fuji II LC finished immediately and later in enamel.

Bicuspid↗

Bacterial penetration of restored cavities.

The aim of this study was to assess the quality of the marginal seals of 7 restoratives by means of a bacterial penetration test in vitro. Sixty intact premolars and third molars that were scheduled for extraction were used in the test. There were 2 experimental groups of teeth, as follows: (1) A class V conventional cavity and a wedge erosion cavity were prepared on the buccal surface and the lingual surface, respectively, of each tooth. (2) A class V conventional cavity and a wedge erosion cavity were prepared on the buccal surface and the lingual surface, respectively, of each tooth with a completely removed enamel layer. The cavities were then reconstructed with different restorative materials. The quality of the marginal seals was evaluated by submerging the teeth in a bacterial suspension and incubating them in an anaerobic milieu at 37 degrees C for 20 hours. The teeth were subsequently processed for histologic data and bacterial staining. The best marginal sealing in both the wedge erosion and the class V cavities was provided by the Herculite/Optibond system and the Valux Plus/Scotchbond Multipurpose system. Bacterial penetration was slightly greater with the Luxat compomer and the Dyrect compomer, as well as with Vitremer glass ionomer cement and Fuji LC glass ionomer cement. The bacterial penetration test showed that the use of restorative material does not entirely eliminate microleakage.

Analysis of Variance↗

Fluoride release from restorative materials and a luting cement.

STATEMENT OF PROBLEM: In addition to conventional glass ionomers, a considerable number of different types of materials have been formulated to release fluoride. Variation in composition results in quantitative differences in the amount of fluoride release by these materials. PURPOSE: This study evaluated and compared fluoride release in distilled water from different types of restorative materials and a luting cement. MATERIAL AND METHODS: Fluoride release from 4 glass ionomer formulation restorative materials (Miracle-Mix, Fuji ionomer type III, Fuji II LC improved, and Ketac-Silver), a luting cement (Ketac Cem), a compomer (Compoglass Flow), 2 sealants (Fissurit F, Helioseal F), and a composite resin (Tetric) was evaluated at time intervals of 4, 8, 12, and 24 hours and 2, 3, 7, 14, 28, 56, and 112 days. Seven disks of each material were made and stored for equilibration in double distilled water at 37 degrees C for the time of each measurement. The equilibrated solution was analyzed for fluoride with a TISAB and an ion-specific combination electrode (ORION 960900) connected to an expandable ion analyzer (Crison micropH 2002). Data were analyzed by means of univariate analysis of variance, the Dunnett C post hoc test, and repeated measures analysis. RESULTS: Fluoride was released from all the evaluated materials, with considerable variation in the rate of release but a similar pattern. Among the materials tested, fluoride release from glass ionomer formulations was greater than that from composite resin formulations; the rank of decreasing order was as follows: Miracle Mix > Fuji III, Ketac Cem > Fuji II LC > Ketac Silver, Compoglass F > Fissurit F, Helioseal F > Tetric (> indicates statistical significance; P< .05). CONCLUSION: Under the conditions of this study, glass ionomer formulations and the compomer released more fluoride than the sealants and the composite resin tested.

Cariostatic Agents↗

Interfacial micromorphological differences in hybrid layer formation between water- and solvent-based dentin bonding systems.

STATEMENT OF PROBLEM: Many dentin bonding systems of different compositions, and in particular containing different solvents, have been introduced to the market. Their effect on the quality of the interface requires clarification by means of comparative trials. PURPOSE: This study investigated micromorphological differences in hybrid layer formation with a variety of commercially available water- or solvent-based dentin bonding products and their recommended compomers. MATERIAL AND METHODS: Five bonding systems were used on groups of 10 teeth each as follows: group I, acetone-based system used with 36% phosphoric acid; group II, a different acetone-based system containing nano-sized particles for filler loading and used with a non-rinsing conditioner containing maleic acid; group III, the acetone-based system of group II used with 36% phosphoric acid (the only difference in the treatment for groups II and III was the acid etching system); group IV, a mixed-solvent-based system (water/ethanol) used with 37% phosphoric acid; and group V, a water-based system used with 37% phosphoric acid. Each bonding system was covered with the recommended compomer. Class I occlusal preparations were made in extracted teeth and restored with one of the above systems. Five specimens of each group were studied with optical microscopy after staining. Scanning electron microscopy was used to examine the interface of the bonding system/dentin of the other 5 teeth in each group. The optical microscopy measurements were made with a 10 x 10 reticle. A micron mark with scale was used for the scanning electron microscope. All measurements were made in microm. The following criteria were used to define a good interface: absence of voids between the different parts of the interface, uniformity of the hybrid layer, good opening of the tubuli orifices, and tag adherence to the tubuli walls. RESULTS: Morphological differences were found at the interface depending on dentin treatment and adhesive composition. The acetone-containing systems were associated with a continuous, gap-free hybrid layer that was linked intimately with the dentin. The tags adhered well to the tubuli walls and were often joined by side branches. In the water-based solvent systems, a lack of contact was visible between the resin tags and the tubuli walls, with some incompletely filled tubuli and some gaps in the hybrid layer. The 2 observational methods used, optical and scanning electron microscopy, proved to be complementary. CONCLUSION: Within the limitations of this study, use of the acetone-based systems after phosphoric acid etching resulted in a continuous, thick hybrid layer with reverse-cone-shaped tags in close contact with the tubuli walls. Use of the water-based systems resulted in a thinner hybrid layer with some incompletely sealed dentinal tubules.

Acetone↗

Influence of chemo-mechanical caries removal on the surface topography of dental composite resin and glass-ionomer materials: an in vitro study.

The aim of the present study was to investigate the influence of a chemo-mechanical caries removal system, Carisolv gel, on the surface topography of dental filling materials. Thirty specimens of a composite resin (Spectrum) and a compomer (Dyract AP) and 60 specimens of a glass-ionomer (Ketac-Fil Plus) were prepared. The surface topography was investigated with an optical interferometer before and after chemical exposure for 5, 10, or 20 min. Each specimen acted as its own control. The topographical part of the glass-ionomer materials was performed in two series with different drying procedures, since this material exhibits a higher sensitivity to dehydration than the other materials. The surface topographical investigations were complemented with contact angle measurements. After Carisolv gel exposure the density of summits and the developed surface area ratio (3D/2D) were slightly smaller for the composite resin and the compomer. For the minimally dried glass-ionomer material, the results indicated a reduction of the height of the surface structures, as well as a surface area enlargement, after Carisolv gel exposure. No statistically significant changes of contact angles due to Carisolv gel exposure could be detected for any material investigated. If dental filling materials of composite resin or glass-ionomer materials are exposed to Carisolv gel, no or only minor surface topographical changes can be expected. n

Compomers↗

Sealing ability of Dyract, Geristore, IRM, and super-EBA as root-end filling materials.

The purpose of this study was to evaluate the apical sealing ability of two compomers (Dyract and Geristore), IRM, and Super-EBA. Forty single canal roots from human teeth were instrumented until a size 40 file extended 1 mm beyond the apex. One millimeter of root apex was removed and a preparation 3-mm deep was prepared. Roots were divided into 4 groups of 10 roots each and filled with IRM, Super-EBA, Dyract, or Geristore. Canals were not obturated to ensure that any leakage was due to the apical filling material alone. Each root was then affixed to a fluid filtration device and subjected to a pressure of 14 cm of H2O, which has been determined to be the normal pulpal tissue pressure. The integrity of the seal was evaluated for 5 min at 1, 7, 30, and 180 days. Data were analyzed at each time point using one-way analysis of variance on ranks. The results of this study suggest that the new compomers Dyract and Geristore are equal or superior to IRM and equivalent to Super-EBA in their ability to reduce apical leakage when used as retrofilling materials.

Analysis of Variance↗

Resinous perforation-repair materials inhibit the growth, attachment, and proliferation of human gingival fibroblasts.

The choice of repair material is one of the important factors in the prognosis of the endodontically treated tooth with a perforation defect. The cytotoxicity of perforation-repair materials must be investigated to ensure a safe biological response. The aim of this in vitro study was to evaluate the effect of resin-modified, glass-ionomer cement, compomer, and resin on human-gingival fibroblasts. Human gingival fibroblasts from crown lengthening surgery were cultured by using an explant technique with the consent of the patient. Cytotoxicity was judged by using an assay of tetrazolium bromide reduction. The results showed that resin-modified, glass-ionomer cement Fuji II LC, compomer Compoglass, and resin SpectrumTPH (TPH) were cytotoxic to primary human gingival fibroblast cultures by inhibiting cell growth and proliferation. TPH alone had an effect on cell attachment. It was found that TPH was the most cytotoxic repair material among those tested in all cultures. The toxicity decreased in the order of TPH>FLC>CG.

Biocompatible Materials↗