Adhesion of human fibroblasts to root-end-filling materials

This study evaluated the attachment of cultured explants of human periodontal ligament fibroblasts and gingival fibroblasts to different root-end-filling materials. Although periodontal ligament and gingival fibroblasts initially attached avidly to Geristore, these same cells displayed no significant attachment to ProRoot, Tytin amalgam, or SuperEBA. With further incubation on Geristore, the attachment of both periodontal ligament and gingival fibroblasts improved and these cells proliferated. In contrast, no improvement in attachment or proliferation was observed for cells incubated for greater times with ProRoot, Tytin amalgam, or SuperEBA. Because the attachment characteristics of these two groups of fibroblasts were identical, we examined the potential role of the extracellular matrix family of receptors (integrins) on the attachment of gingival fibroblasts. Gingival fibroblast attachment to collagen type I was determined to be dependent on alpha1beta1 and alpha2beta1 integrins, whereas their attachment to the RGD-binding sequence of fibronectin and vitronectin was partially inhibited by antibodies to the beta1 and alphaV integrin subunits. However, attachment of gingival fibroblasts to Geristore was not reduced by the addition of any of the attachment-perturbing anti-integrin antibodies examined. Thus, gingival fibroblasts attach to Geristore, but this attachment was mediated by mechanisms other than integrins.     

Solubility of root-end-filling materials: a comparative study

This study tested solubility of 3 root-end filling materials (IRM, Pro Root, and Superseal) and an endodontic sealer (Argoseal) used as positive control. The test was performed according to the International Standards Organization 6876 standard and the American Dental Association specification #30. Six specimens of each material were prepared and immersed in water. Solubility was determined after 24 hours and 2 months and analyzed statistically with a one-way analysis of variance test. All retrograde filling materials were of low solubility. Under the conditions of the present study, IRM, Superseal, and Pro Root are virtually insoluble; this is an adequate physical property for use as root-end filling materials.     

In vitro wear evaluation of dental materials in primary teeth

PURPOSE: To evaluate the effect of dental materials on primary enamel wear. METHODS: Four composites (Filtek Z250, Heliomolar, Point 4, SureFil), two compomers (Dyract AP, F2000) and a resin-modified glass-ionomer (Vitremer) were placed into box-shaped preparations in buccal surfaces of primary molars and stored for 24 hours in water at 37 degrees C. The specimens (n = 6) were subjected to abrasive three-body wear against a primary enamel cusp. Material wear, enamel wear (adjacent to the material), and wear on enamel cusps were estimated by profilometry and video-analysis software. Results were compared with ANOVA and Tukey's tests (P < 0.05). RESULTS: Vitremer showed the highest wear (P < 0.05), followed by Dyract AP and F2000, which were not statistically different (P > 0.05). There was no significant difference between Filtek Z250 and Dyract AP (P > 0.05). Filtek Z250, Heliomolar, Point 4 and SureFil, showed the lowest wear values and there was no difference among them (P > 0.05). The highest wear values on the enamel adjacent to the material were found with Dyract AP (P < 0.05) and the lowest next to Point 4 and SureFil (P < 0.05). There was no difference in the wear of the enamel next to Vitremer, F2000, Heliomolar and Filtek Z250 (P > 0.05). Vitremer and F2000 caused the highest wear on enamel cusps (P < 0.05), and there was no statistically significant difference (P > 0.05) between them; SureFil caused the lowest wear (P < 0.05) on the opposing enamel. There was a correlation (r = 0.85) between wear of materials and wear on the enamel cusps, but not (r = 0.53) for the wear on enamel besides the restoration and wear on enamel cusps. SEM micrographs showed different surface characteristics of the materials after the wear test.     

In vitro comparison of the biocompatibility of mineral trioxide aggregate, 4META/MMA-TBB resin, and intermediate restorative material as root-end-filling materials

This study compared the effects of three root-end-filling materials: mineral trioxide aggregate (MTA), 4-META/MMA-TBB resin (Super-bond), and intermediate restorative material (IRM) on osteoblast adhesion, proliferation, and matrix formation. MC3T3-E1 cells were inoculated on set material specimens, and the number of cells adhered to each material was assessed at 6 hours and at 3 days of incubation by using Hoechst 33258 staining under a fluorescence microscope. Furthermore, on day 21 of culture, areas in contact with each material surface were observed at light and electron microscopic levels. Cultured cells that adhered to MTA and Super-bond proliferated significantly between 6 hours and 3 days of culture. In addition, on day 21, they produced a thick matrix layer directly on the material surfaces. In contrast, the number of cells that adhered to IRM significantly decreased with time. These cells appeared round in shape, and no matrix formation was found. These results suggest that MTA and Super-bond have good biocompatibility and allow hard-tissue forming cells to create a matrix layer, which might enhance apical tissue regeneration.     

牙齿脱敏材料降低牙本质通透性的体外评价

目的：体外评价3种牙齿脱敏材料降低牙本质通透性的效果。方法用低速锯切取新鲜离体人下颌第三磨牙牙合侧近髓牙本质片60个,牙本质片远髓面经磷酸溶液处理后,分别应用Green Or、Gluma Disensitizer和舒适达修复牙膏共3种牙齿脱敏材料,然后,采用基于液压渗透法的自制通透性测定装置测定每个牙本质片远髓面涂布前、后的通透值,并用SEM观察牙本质表面形貌。结果3种材料应用后牙本质片的通透值均显著下降（P＜0.05）,下降效果：Green Or≈Gluma〉舒适达修复牙膏（P＜0.05）, SEM观察发现3种材料均在不同程度上堵塞牙本质小管。结论3种脱敏材料均能有效降低牙本质的通透性;液压渗透法测定牙本质的通透性,操作简单,数据可量化,可真实反映牙本质的通透性。     

In vitro evaluation of microleakage of different materials used as pit-and-fissure sealants

The aim of this study was to evaluate in vitro the marginal microleakage of different materials used as pit-and-fissure sealants (Delton, Filtek Flow, Dyract Flow and Vitremer). Fifty-six extracted sound human third molars were randomly assigned to 4 groups (n=14). After sealant placement, the teeth were thermocycled (500 cycles; 5 degrees C, 37 degrees C and 55 degrees C), isolated, immersed in 2% buffered methylene blue dye for 4 h, included in acrylic resin and sectioned longitudinally in a buccolingual direction. The sections were analyzed for leakage using an stereomicroscope. A 4-criteria ranked scale was used to score dye penetration. All materials exhibited dye penetration to some extension and no statistically significant difference was observed among the groups (p>0.05). In conclusion, the findings of this study showed that a flowable composite resin, a flowable compomer and resin-modified glass ionomer placed on occlusal pits and fissures had similar marginal sealing as the unfilled self-cured resin-based sealant.     

In vitro evaluation of Candida albicans adherence to soft denture-lining materials.

The adherence of Candida albicans to seven commercial soft denture-lining materials was studied in vitro with BCA protein assay reagent. A good correlation was observed between the amount of protein in yeast cells and the number of yeasts (r = 0.993, p < 0.01), and it was revealed that the adherence of C. albicans to bare surfaces of these soft denture-lining materials correlated well with their relative hydrophobic properties (r = 0.905, p < 0.01); thus there was consistency with the thermodynamic theory. These results combined corroborated the accuracy of this method. To know the effect of pellicle on fungal adherence, the adherence of C. albicans to saliva-coated samples was examined. It was revealed that neither the amount of protein adsorbed by substrates nor the adherence of yeast to saliva-coated substrates correlated with the relative hydrophobic properties of these samples, suggesting that factors other than hydrophobic interaction play an important role in the adherence of C. albicans to pellicle-coated soft liners and tissue conditioners.     

In vitro evaluation of two adhesive systems used with compomer filling materials

AIM: To evaluate and compare the in-vitro shear bond strength, microleakage and dentine-restorative interface of a self-etching/self-priming dentine bonding agent with a three-component dentine-bonding agent. METHOD: For shear bond strength (SBS) testing 30 non-carious human molars were used of which 15 were tested with Non-Rinse Conditioner (NRC)/Prime&Bond NT (PBNT) and Dyract AP and 15 were tested with Scotchbond Multi-Purpose Plus (SBMP) and F2000. For the microleakage evaluation cavity preparations were made on the facial surfaces of 30 non-carious human premolars of which 15 were restored with NRC and PBNT with Dyract AP and 15 were restored with SBMP and F2000. The dentine-restorative interface was examined through a confocal scanning laser microscope (CSLM). RESULTS: The mean SBS of PBNT and SBMP were 12.8 and 18.1 MPa, respectively. The microleakage scores showed NRC/PBNT leaked on the dentine side in 13 of the 15 specimens examined. On the enamel side two of the 15 specimens showed microleakage. With SBMP no microleakage was observed on either enamel or dentine sides. The CSLM images show clear resin tag and hybrid layer formation for both the materials examined although SBMP showed better and deeper penetration into the dentine with longer resin tags. SBMP showed resin tags measuring about 150 mm while the hybrid layer measured about 5 mm. The length of the resin tags as well as the thickness of the hybrid layer for PBNT were 20 mm Pounds and 2 mm Pounds, respectively. CONCLUSIONS: The acid-etch technique of SBMP produced higher bond strength and no microleakage when compared with the self-etching/self-priming 'non-rinse technique' of NRC with PBNT. Thus it can only be speculated that SBMP should be the superior in the clinical situation.     

In vitro evaluation of the apical seal of two different retrograde filling materials

To determine whether the selection of retrograde filling material or the choice of instruments in root tip resection influences the seal of the retrograde root filling. Seventy‐two single‐rooted teeth were used. Root resection was performed using a Lindemann bone cutter, a Lindemann bone cutter with A‐shaped cutting design or a diamond‐coated bur. Retro‐cavities were prepared by piezo‐tips and filled with Super‐EBA or MTA. Teeth were made transparent and dye penetration was assessed. Teeth filled with MTA, irrespective of the resection instrument, showed no measurable dye penetration. All groups filled with Super‐EBA showed an apical leakage. There were no significant differences between the three groups filled with Super‐EBA (P = 0.09). The comparison of MTA versus Super‐EBA showed significant superiority in apical seal in favour of MTA (P < 0.0001). To use MTA as a retrograde filling material showed superior results in terms of the tightness of the apical seal as compared to Super‐EBA.     

In vitro evaluation of fracture strength of zirconia restoration veneered with various ceramic materials

PURPOSE

Fracture of the veneering material of zirconia restorations frequently occurs in clinical situations. The purpose of this in vitro study was to compare the fracture strengths of zirconia crowns veneered with various ceramic materials by various techniques.

MATERIALS AND METHODS

A 1.2 mm, 360° chamfer preparation and occlusal reduction of 2 mm were performed on a first mandibular molar, and 45 model dies were fabricated in a titanium alloy by CAD/CAM system. Forty-five zirconia copings were fabricated and divided into three groups. In the first group (LT) zirconia copings were veneered with feldspathic porcelain by the layering technique. In the second group (HT) the glass ceramic was heat-pressed on the zirconia coping, and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented onto their titanium dies with Rely X™ Unicem (3M ESPE) and loaded with a universal testing machine (Instron 5583) until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc test (α=0.05). Scanning electron microscope was used to investigate the fractured interface.

RESULTS

Mean fracture load and standard deviation was 4263.8±1110.8 N for Group LT, 5070.8±1016.4 for Group HT and 6242.0±1759.5 N for Group ST. The values of Group ST were significantly higher than those of the other groups.

CONCLUSION

Zirconia crowns veneered with CAD/CAM generated glass ceramics by the sintering technique are superior to those veneered with feldspathic porcelain by the layering technique or veneered with glass ceramics by the heat-pressing technique in terms of fracture strength.     

In vitro evaluation of the marginal seal of four restoration materials on deciduous molars

The aim of this study was to compare the marginal microleakage of Fuji II LC (A), composite resin Z250 (B), Fuji IX GP (C), and Dyract AP (F) in class V cavities and at the Fuji II LC/Z250 (D) and Fuji IX GP/composite resin Z250 (E) interfaces of an open sandwich technique on deciduous teeth. After thermocycling the mean marginal dye penetration at the enamel junction was 21.6 microns +/- 14.2 for group A; 83.6 microns +/- 32.3 for group B; 7.5 microns +/- 7.5 for group C; 38.7 microns +/- 27.5 for group D, and 0 micron for groups E and F. Mean dye penetration at the cementum junction was 37.1 +/- 20.2 (A); 123 +/- 42.1 (B); 28.7 +/- 17.1 (C); 0 (D); 14.4 +/- 14.4 (E); and 0 (F) microns. No leakage was seen at the junction between Fuji II LC and Z250 (0 micron), whereas a mean leakage of 184 microns between Fuji IX and Z250 was measured. In enamel the best seal was obtained with Dyract AP, but with differences at the limit of significance (P = 0.07). Sealing was significantly worse with Z250 (p = 0.03 versus Fuji II LC; p = 0.006 versus Fuji IX GP; and p = 0.003 versus Dyract AP). In cementum, the comparison between the grouped data Z250-Fuji II LC versus Fuji IX GP-Dyract AP was highly significant (p < 0.001), while there was no detectable difference between Z250 and Fuji II LC.     

In vitro cytotoxicity of orthodontic bonding materials

Previous studies have shown that toxic reactions to direct-bonding adhesives can be demonstrated both in animals and in cell culture tests. These effects have also been shown with other related dental materials. The purpose of this study was to compare the relative toxicity of a number of common orthodontic adhesives and to determine, by means of a rapid, sensitive in vitro cell culture agar overlay test, how their toxicity changed with time subsequent to polymerization. Various othordontic bonding materials were tested either immediately or at various times up to 30 days after polymerization. The cells were stained with a vital dye (neutral red), the diameter of the area of unstained, nonviable cells was measured, and the results of three tests per sample were averaged and analyzed by means of Duncan's Multiple Range Tests. All materials were found to have some cytotoxic effect immediately after mixing, with the activator components of two "no-mix" materials exhibiting significantly higher toxicity (p less than 0.05) than other materials tested. The sealant materials showed a significantly greater toxicity than paste resins, both initially after mixing and after 30 days postpolymerization. If applicable to the clinical situation, these data indicate that care is needed particularly in handling liquid activators. Excess "polymerized" sealant, which may contain many nonreacted groups, should be carefully removed by scaling peripheral to the bracket bases, particularly in subgingival and interproximal areas.     

In vitro evaluation of fluoride-releasing restorative materials for sealing the root canals of overdenture abutments

PURPOSE: The purpose of this study was to evaluate the ability of newer fluoride-releasing restorative materials to protect the root surface from acid attack. MATERIALS AND METHODS: The materials used were glass-ionomer cement (GIC), resin-modified glass-ionomer cement (RM-GIC), and a compomer (Comp). A composite resin (CR) was used as the control. The restored teeth were stored in deionized, distilled water for 14 days and subjected to 300 thermocycles (55 degrees C and 5 degrees C). The teeth were cycled in a demineralizing solution (pH 5.0 or 4.0) for 6 hours and in a remineralizing solution (pH 7.0) for 17 hours for 10 days. The depths of lesions created by acid challenge were measured at the interface of the tooth and the restorative material and then at a distance of 50, 100, and 300 microns from the tooth-restoration margin using polarized light microscopy and contact microradiography. RESULTS: At pH 4.0, there was significant difference in the depth at the interface between the tooth and the restorative material (P < .001). The GIC and RM-GIC were protective, and the lesion depths were significantly shallower than for Comp or CR. The protective effect varied depending on the distance from the interface of the tooth and the restorative material. At pH 5.0, the GIC and RM-GIC had no lesions at the interface, while the Comp and the CR had lesions (P < .001). CONCLUSION: Fluoride-releasing glass-ionomer cement seems to be an appropriate material to seal the root canals of overdenture abutments, because it has an inhibiting effect on demineralization at the cavity wall in vitro.     

In vitro evaluation of surface roughness and microhardness of restorative materials submitted to erosive challenges

The aim of this study was to evaluate the effect of different acidic solutions on the microhardness and surface roughness of restorative materials. The 120 specimens of restorative materials (Fuji II LC, Vitremer, Supreme XT, and Supreme XT + Biscover LV) were randomly divided into three groups according to the immersion media: hydrochloric acid, soft drink, or distilled water. Over a period of five weeks, the groups were immersed in the solutions, which were changed weekly. Data were tested using analysis of variance and the Fisher protected least significant difference test (p<0.05). The results showed that the glass ionomer materials showed the highest surface roughness values (Fuji II LC: 0.111 ± 0.014 μm before and 0.139 ± 0.016 μm after immersion; Vitremer: 0.177 ± 0.012 μm before and 0.084 ± 0.012 μm after immersion), whereas the lowest values were found for the resin sealed with Biscover LV before (0.047 ± 0.011 μm) and after exposure in distilled water (0.043 ± 0.007 μm), soft drink (0.040 ± 0.005 μm), and hydrochloric acid (0.045 ± 0.005 μm). The Supreme XT showed the highest microhardness values before (44.96 ± 2.51 KHN) and after the aging process (41.26 ± 1.22 KHN in water, 35.96 ± 0.81 KHN in soft drink, and 34.74 ± 0.97 KHN in HCl), with significant differences from the other materials (p<0.0001). The lowest microhardness values were found for glass ionomer materials. The solutions used in this study decreased the microhardness of all studied materials, whereas the sealed surface suffered minor changes in microhardness and surface roughness after exposure to acidic solutions.     

In vitro evaluation of ampicillin-gentamicin interactions

Ampicillin at a concentration of 100 micrograms/mL was combined in vitro with either gentamicin 10 micrograms/mL in serum, 0.01 mol/L phosphate-buffered saline at 37 degrees C, or water at room temperature (25 degrees C). At these concentrations, which represent the peak prophylactic serum concentrations likely to be achieved by a 70-kg person after parenteral administration of 1.5 mg/kg gentamicin and 2 g of ampicillin, no clinically significant inactivating effects of these antibiotics on each other were observed over a period of six hours.     

医用高分子材料的体外细胞毒性研究

目的 研究１１种医用高分子材料的细胞毒性。方法 应用体外细胞培养琼脂覆盖法对９种医用硅橡胶材料和２种聚氨酯材料的细胞毒性进行评价。结果 １１种实验材料的材料周围和材料下脱色区范围及脱色区内细胞溶解评价（Ｚ／Ｌ值）除Ｄ．Ｃ硅橡胶材料为０／０、复旦聚氨酯材料为２／２外、其余９种材料均为１／１。结论 琼脂覆盖法快速,简便,是评价生物医用材料细胞毒性的一种有效方法。     

暂时冠桥材料挠曲强度的体外研究

目的体外对比2种甲基丙烯酸酯类和3种bis-acryl类暂时冠桥材料的挠曲强度.方法依据ISO40492000标准,制作25mm×2 mm×2 mm条状试样,人工唾液中37℃保存24 h后,在万能力学实验机上三点加荷测定试样挠曲强度.结果5种材料挠曲强度值排序QuickResin＜Protemp Ⅱ＜Curefast＜Luxatemp＜Protemp 3 Garant.QuickResin、Protemp Ⅱ和Curefast之间没有统计学差异(P＞0.05).Protemp 3 Garant挠曲强度值高于Luxatemp(P＜0.05),他们均高于前三者(P＜0.05).结论bis-acryl类材料较甲基丙烯酸酯类材料强度好,但是早期bis-acryl类材料强度一般.临床医生应根据不同的病人选用合适的暂时冠桥材料.