Cytotoxic effects of current dental adhesive systems on immortalized odontoblast cell line MDPC-23

Objectives: Evaluate the cytotoxic effect of the three dental adhesive systems. Methods: The immortalized mouse odontoblast cell line (MDPC-23) was plated (30,000 cell/cm 2) in 24 well dishes, allowed to grow for 72 h, and counted under inverted light microscopy. Uncured fresh adhesives were added to culture medium to simulate effects of unset adhesive. Three adhesives systems were applied for 120 min to cells in six wells for each group: Group 1) Single Bond (3M), Group 2) Prime & Bond 2.1 (Dentsply), and Group 3) Syntac Sprint (Vivadent). In the control group, PBS was added to fresh medium. The cell number was counted again and the cell morphology was assessed under SEM. In addition, the adhesive systems were applied to circles of filter paper, light-cured for 20 s, and placed in the bottom of 24 wells (six wells for each experimental materials and control group). MDPC-23 cells were plated (30,000 cell/cm 2) in the wells and allowed to incubate for 72 h. The zone of inhibition around the filter papers was measured under inverted light microscopy; cell morphology was evaluated under SEM; and the MTT assay was performed for mitochondrial respiration. Results: The fresh adhesives exhibited more toxic (cytopathic effects) to MDPC-23 cells than polymerized adhesives on filter papers, and as compared to the control group. The cytopathic effect of the adhesive systems occurred in the inhibition zone around the filter papers, which was confirmed by the MTT assay and statistical analysis (ANOVA) combined with Fisher's PLSD test. In the control group, MDPC-23 cells were dense on the plastic substrate and were in contact with the filter paper. In the experimental groups, when acid in the adhesive systems was removed by changing the culture medium, or when the adhesives were light-cured, some cells grew in the wells in spite of the persistent cytotoxic effect. Significance: All dentin adhesive systems were cytotoxic odontoblast-like cells. Both acidity and non-acidic components of these systems were responsible for the high cytopathic effect of those dental materials. © 1999 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.

Use of one-bottle adhesive as an intermediate bonding layer to reduce sealant microleakage on saliva-contaminated enamel

Purpose: To evaluate the influence of three different adhesives, each used as an intermediary layer, on microleakage of sealants applied under condition of salivary contamination. Materials and Methods: Six different experimental conditions were compared, 3 with adhesives and 3 without. After prophylaxis and acid etching of enamel, salivary contamination was placed for 10 s. In Group SC the sealant was applied after saliva without bonding agent and then light-cured. In Group SCA, after saliva, the surface was air dried, and then the sealant was applied and cured. In Groups ScB, SB and PB, a bonding agent (Scotchbond Dual Cure/3M, Single Bond/3M and Prime & Bond 2.1/Dentsply, respectively) was applied after the saliva and prior to the sealant application and curing. After storage in distilled water at 37°C for 24 hrs, the teeth were submitted to 500 thermal cycles (5°C and 55°C), and silver nitrate was used as a leakage tracer. Leakage data were collected on cross sections as percentage of total enamel-sealant interface length. Representative samples were evaluated under SEM. Results: Sealants placed on contaminated enamel with no bonding agent showed extensive microleakage (94.27% in SC; 42.65% in SCA). The SEM revealed gaps as wide as 20 μm in areas where silver nitrate leakage could be visualized. In contrast, all bonding agent groups showed leakage less than 6.9%. Placement of sealant with a dentin-bonding agent on contaminated enamel significantly reduced microleakage (P< 0.0001). The use of a bonding agent as an intermediary layer between enamel and sealant significantly reduced saliva's effect on sealant microleakage.

Effect of Surface Treatments on the Bond Strength between Composite Resin and Acrylic Resin Denture Teeth

Purpose: This investigation studied the effects of 3 surface treatments on the shear bond strength of a light-activated composite resin bonded to acrylic resin denture teeth. Materials and Methods: The occlusal surfaces of 30 acrylic resin denture teeth were ground flat with up to 400-grit silicon carbide paper. Three different surface treatments were evaluated: (1) the flat ground surfaces were primed with methyl methacrylate (MMA) monomer for 180 seconds; (2) light-cured adhesive resin was applied and light polymerized according to the manufacturer's instructions; and (3) treatment 1 followed by treatment 2. The composite resin was packed on the prepared surfaces using a split mold. The interface between tooth and composite was loaded at a cross-head speed of 0.5 mm/min until failure. Results: Analysis of variance indicated significant differences between the surface treatments. Results of mean comparisons using Tukey's test showed that significantly higher shear bond strengths were developed by bonding composite resin to the surfaces that were previously treated with MMA and then with the bonding agent when compared to the other treatments. Conclusion: Combined surface treatment of MMA monomer followed by application of light-cured adhesive resin provided the highest shear bond strength between composite resin and acrylic resin denture teeth.

Use of dental implants in children: A literature review

The aim of this literature review is to discuss the use of dental implants in growing patients and the influence of maxillary and mandibular skeletal and dental growth on the stability of those implants. It is recommended to wait for the completion of dental and skeletal growth, except for severe cases of ectodermal dysplasia.

Microleakage in primary teeth restored by conventional or bonded amalgam technique.

The aim of this in vitro study was to evaluate marginal leakage in class V restorations in primary teeth restored with amalgam, using three different techniques. Thirty maxillary anterior primary teeth, clinically sound and naturally exfoliated, were used. In group 1 (n = 10), two thin layers of a copal varnish (Cavitine) were applied. In group 2 (n = 10), Scotchbond Multi-Purpose Plus, a dual adhesive system, was used according to manufacturer instructions. In group 3 (n = 10), One-Step adhesive system in combination with a low-viscosity resin (Resinomer) were used according to manufacturer instructions. All samples were restored with a high-copper dental amalgam alloy (GS 80, SDI). After restoration, the samples were stored in normal saline at 37 degrees C for 72 h. The specimens were polished, thermocycled (500 cycles, 5 degrees and 55 degrees C, 30-s dwell time) and impermeabilized with fingernail polish to within 1.0 mm of the restoration margins. The teeth were then placed in 0.5% methylene blue for 4 h. Finally, the samples were sectioned and evaluated for marginal leakage. The Kruskal-Wallis test showed that the filled adhesive resin (group 3) had the least microleakage. There was no significant difference between groups 1 and 2.

Resistance to maxillary premolar fractures after restoration of class II preparations with resin composite or ceromer.

OBJECTIVE: The aim of this study was to evaluate the resistance to fracture of intact and restored human maxillary premolars. METHOD AND MATERIALS: Thirty noncarious human maxillary premolars, divided into three groups of 10, were submitted to mechanical tests to evaluate their resistance to fracture. Group 1 consisted of intact teeth. Teeth in group 2 received mesio-occlusodistal cavity preparations and were restored with direct resin composite restorations. Teeth in group 3 received mesio-occlusodistal cavity preparations and were restored with ceromer inlays placed with the indirect technique. After restoration, teeth were stored at 37 degrees C for 24 hours and then thermocycled for 500 cycles at temperatures of 5 degrees C and 55 degrees C. RESULTS: Statistical analysis revealed that group 3 (178.765 kgf) had a significantly greater maximum rupture load than did group 1 (120.040 kgf). There was no statistically significant difference between groups 1 and 2 or between groups 2 and 3. CONCLUSION: Class II cavity preparations restored with indirect ceromer inlays offered greater resistance to fracture than did intact teeth. The fracture resistance of teeth restored with resin composite was not significantly different from that of either the ceromer or intact teeth.

Cariostatic effect of fluoride-containing restorative systems associated with dentifrices on root dentin

Objective. The aim of this in vitro study was to evaluate the interaction between two sources of fluoride (restorative systems and dentifrices) in inhibiting artificial root caries development. Methods. One hundred and eighty tooth segments were embedded in polyester resin, and sanded flat. Cylindrical cavities 1.0 mm-deep and 1.5 mm-diameter were prepared in root dentin and randomly restored by fluoride-containing restorative systems: Ketac-fil/Espe (Ke), Fuji II LC/GC Corp (Fj), F2000/3M (F2), Surefil/Dentsply (Su) or a control: Filtek Z250/3M (Z2). Ten experimental groups were made to test the association among the five restorative systems and two dentifrices: with F - (Sensodyne Baking Soda) or without F- (Sensodyne Original) (n = 18). After surface polishing, a 1 mm-wide margin around the restorations was demarcated and initial dentin surface Knoop microhardness values (KHNi) were obtained. The specimens were submitted to a pH-cycling model, and to applications of slurries of dentifrice. Afterwards the final dentin surface Knoop microhardness values (KHNf) were measured. Results. The differences between KHNi and KHNf, and the covariate KHNi were considered by the ANCOVA and Tukey's test (α = 0.05). The interaction between restorative system and dentifrice was statistically significant (p = 0.0026). All restorative systems provided some protection against artificial caries challenge when associated with the fluoride-containing dentifrice treatment. The means (standard deviation) of reductions in Knoop hardness values for systems associated with the fluoride-containing dentifrice were: Ke: 40.0(1.02)a, Fj: 41.9(1.02)b, F2: 43.3(1.04)c, Su: 43.5(1.00)c, Z2: 44.0(1.02)c; and with the non-fluoride-containing dentifrice were: Ke: 42.9(1.02)a, Fj: 44.7(1.01)b, F2: 45.2(1.09)bc, Su: 46.0(0.99)c, Z2: 46.6(0.99)c (statistical differences were expressed by different letters). Conclusion. The cariostatic effect shown by the fluoride-containing dentifrice could enhance that shown by Ketac-fil and Fuji II LC, and could mask that shown by F2000. © 2002 Elsevier Science Ltd. All rights reserved.

Evaluation of marginal microleakage in Class II cavities: Effect of microhybrid, flowable, and compactable resins

Objective: The goal of the present study was to evaluate the microleakage on the cementum/dentin and enamel surfaces in Class II restorations, using different kinds of resin composite (microhybrid, flowable, and compactable). Method and materials: Forty human caries-free molars were extracted and selected. Eighty Class II standardized cavities were made in the cervical wall at the cementoenamel junction (CEJ) and at the mesial and distal surfaces. The teeth were divided into four groups: G1 - adhesive system + microhybrid resin composite Z100; G2 - adhesive system + compactable resin composite Prodigy Condensable; G3 - adhesive system + flowable resin composite Revolution + Z100 resin composite; G4 - adhesive system + Revolution fluid resin + compactable resin composite Prodigy Condensable. The adhesive system used in this study was Scotchbond Multi-Purpose Plus. The specimens were thermocycled in baths of 5°C and 55°C for 1,000 cycles and immersed in 50% silver nitrate solution. The specimens then were sectioned and evaluated on degree of dye penetration. Results: The results were evaluated using the nonparametric Kruskall-Wallis test, which showed a statistically significant difference between groups G1 and G4, G2 and G4, and G3 and G4. Conclusions: None of the materials was able to eliminate the marginal microleakage at the cervical wall; the application of a low-viscosity resin composite combined with a compactable resin composite significantly decreased the microleakage.

Dental implants: Surface modification of cp-Ti using plasma spraying and the deposition of hydroxyapatite

The commercial pure titanium (cp-Ti) is currently being used with great success in dental implants. In this work we investigate how the cp-Ti implants can be improved by modifying the metal surface morphology, on which a synthetic material with properties similar to that of the inorganic part of the bone, is deposited to facilitate the bone/implant bonding. This synthetic material is the hydroxyapatite, HA, a calcium-phosphate ceramic. The surface modification consists in the application of a titanium oxide (TiO2) layer, using the thermal aspersion - plasma spray technique, with posterior deposition of HA, using the biomimetic method. The X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) and Diffuse Reflectance Infrared Fourier Transform (DRIFT) techniques have been used for characterizing phases, microstructures and morphologies of the coatings. The TiO2 deposit shows a mixture of anatase, rutilo and TiO2-x phases, and a porous and laminar morphology, which facilitate the HA deposition. After the thermal treatment, the previously amorphous structured HA coating, shows a porous homogeneous morphology with particle size of about 2-2.5 μm, with crystallinity and composition similar to that of the biological HA.

Fluoride release by restorative materials before and after a topical application of fluoride gel

The release of fluoride from restorative materials (Vitremer, Ketac-Fil, Fuji II LC and Freedom) was evaluated during two 15-day periods, before and after a topical application of acidulated phosphate fluoride gel (APF). For each material, 6 specimens were made, which were immersed in 2 ml of deionized water. The fluoride concentration dosages in the solutions were read at intervals of 24 hours for 15 days. After this period, the specimens of each material received treatment with APF gel for 4 minutes and the fluoride released was analyzed at 24-hour intervals during the following 15 days. The analysis of variance and the Tukey test (p < 0.05) showed that the total mean fluoride released during the initial 15 days was greater for Vitremer and Ketac-Fil and lower for Fuji II LC and Freedom; and in the final 15 days there was a difference in release readings, with the greatest value for Vitremer, followed by Fuji II LC, Ketac-Fil and Freedom. The comparison of the results between the 1st day and the 16th day (after gel application) showed a greater fluoride release on the 16th day for Vitremer, Fuji II LC and Freedom and was equal for Ketac-Fil. Although all the materials evaluated gained fluoride with the application of APF, the data suggest that the resin-modified ionomers are more efficient in releasing fluoride to the medium than the other materials.

Behavioral evaluation during dental care in children ages 0 to 3 years

Purpose: Many studies concluded that the behavior of babies complicated dental care because of child immaturity or the difficulty of establishing acceptable communication and comprehension. Methods: The records of 696 babies were randomly selected from the baby clinic of Araçatuba in Brazil. Patient age ranged from 0 to 36 months. They were divided into 6 groups according to age: Group I-0 to 6 months; Group II-7 to 12 months; Group III-13 to 18 months; Group IV-19 to 24 months; Group V-25 to 30 months; Group VI-31 to 36 months. The behavior of the child was evaluated upon entrance in the dental office and during the first 4 clinical appointments with a clinical exam and oral physiotherapy. The baby was classified as collaborator (C) or noncollaborator (NC). Statistical analysis was performed using Pearson's chi-square method (P< .05). Results: The percentage of NC for Groups II, III, IV, and V (66%), was significantly higher than for groups I (30%) and VI (50%). Conclusions: Babies from 0 to 6 months showed a collaborative behavior; babies from 7 to 30 months showed noncollaborative behavior; and babies from 31 to 36 months showed no statistically significant difference between the percentage of C and NC.

Influence of dental care for infants on caries prevalence: A comparative study

Purpose: The influence of early dental care on the prevalence of dental caries was determined in children ages 35 to 40 months divided into 2 groups of 160 children each, with 1 group participating in a dental care program from the first year of life to the time of the study, while the other group did not receive any dental care. Methods: The clinical conditions considered for the evaluation were: sound teeth, enamel caries without cavitation, enamel caries with cavitation, and dentinal caries. The proportion and chi-square tests were used for statistical analysis with the level of significance set at 5%. Results: A significant difference regarding the presence of dental caries, especially in the number of children presenting enamel caries with cavitation (P<.0001), was observed between the 2 groups. The number of children with enamel caries without cavitation and dentinal caries was similar for the 2 groups. Conclusions: Considering the aspect of dental caries prevention, the authors concluded that children in the age range of 3 to 4 years who received early dental care showed better oral conditions.

Effects of bleaching with carbamide peroxide gels on microhardness of restoration materials

The objective of this in vitro study was to quantitatively assess the effects of bleaching with 10 and 15% carbamide peroxide (CP) on restoration materials by performing superficial microhardness analysis. Acrylic cylindrical containers (4 x 2 mm) were filled with the following restoration products: Charisma (Heraues Kulzer, Vila Santa Catarina, São Paulo, Brazil), Durafill VS (Heraeus Kulzer), Vitremer (3M, Sumaré, São Paulo, Brazil), Dyract (Dentsply, Petrópolis, Rio de Janeiro, Brazil), and Permite C (SDI, São Pauio, São Paulo, Brazil). Sixty samples were prepared of each restoration material. Twenty samples received bleaching treatment with 10% CP, 20 samples received bleaching treatment with 15% CP, and 20 samples were kept submerged in artificial saliva, which was replaced daily. The treatment consisted of immersion of the specimens in 1 cm3 of CP at 10 and 15% for 6 hours per day during 3 weeks, whereupon the test specimens were washed, dried, and kept immersed in artificial saliva for 18 hours. Then the test and control specimens were analyzed using a microhardness gauge. The Knoop Hardness Number (KHN) was taken for each test and control specimen at five different locations by applying a 25 g force for 20 seconds. The values obtained were transformed into KHNs and the mean was calculated. The data were submitted to statistical analysis by analysis of variance and Tukey test, p < .05. The means/standard deviations were as follows: Charisma: CP 10% 38.52/4.08, CP 15% 34.31/6.13, saliva 37.36/4.48; Durafill VS: CP 10% 18.65/1.65, CP 15% 19.38/2.23, saliva 18.27/1.43; Dyract AP: CP 10% 30.26/2.81, CP 15% 28.64/5.44, saliva 33.88/3.46; Vitremer: CP 10% 28.15/3.04, CP 15% 17.40/3.11, saliva 40.93/4.18; and Permite C: CP 10% 183.50/27.09, CP 15% 159.45/5.78, saliva 215.80/26.15. A decrease in microhardness was observed for the materials Dyract AP, Vitremer, and Permite C after treatment with CP at 10 and 15%, whereas no effect on either of the two composites (Charisma and Durafill) was verified. CLINICAL SIGNIFICANCE: The application of the carbamide peroxide gels at 10 and 15% did not alter the microhardness of the composite resins Charisma and Durafill. In situ and clinical studies are necessary to enable one to conclude that the reduction in microhardness of the materials effectively results in clinical harm to the restorations.

Microbiologic and radiographic analysis of ligature-induced peri-implantitis with different dental implant surfaces

Purpose: The goal of this study was to evaluate microbiota and radiographic peri-implant bone loss associated with ligature-induced peri-implantitis. Materials and Methods: Thirty-six dental implants with 4 different surfaces (9 commercially pure titanium, 9 titanium plasma-sprayed, 9 hydroxyapatite, and 9 acid-etched) were placed in the edentulous mandibles of 6 dogs. After 3 months with optimal plaque control, abutment connection was performed. On days 0, 20, 40, and 60 after placement of cotton ligatures, both microbiologic samples and periapical radiographs were obtained. The presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia/nigrescens, Campylobacter spp, Capnocytophaga spp, Fusobacterium spp, beta-hemolytic Streptococcus, and Candida spp were evaluated culturally. Results: P intermedia/nigrescens was detected in 13.89% of implants at baseline and 100% of implants at other periods. P gingivalis was not detected at baseline, but after 20 and 40 days it was detected in 33.34% of implants and at 60 days it was detected in 29.03% of dental implants. Fusobacterium spp was detected in all periods. Streptococci were detected in 16.67% of implants at baseline and in 83.34%, 72.22%, and 77.42% of implants at 20, 40, and 60 days, respectively. Campylobacter spp and Candida spp were detected in low proportions. The total viable count analysis showed no significant differences among surfaces (P = .831), although a significant difference was observed after ligature placement (P < .0014). However, there was no significant qualitative difference, in spite of the difference among the periods. The peri-implant bone loss was not significantly different between all the dental implant surfaces (P = .908). Discussion and Conclusions: These data suggest that with ligature-induced peri-implantitis, both time and periodontal pathogens affect all surfaces equally after 60 days.

Effect of 2% chlorhexidine on microtensile bond strength of composite to dentin

Purpose: To evaluate the effect of 2% chlorhexidine on the microtensile bond strength of composite resin to dentin treated with three dentin bonding systems. Materials and Methods: Flat dentinal surfaces were prepared in 24 extracted human third molars. Teeth were randomly divided into 8 distinct experimental groups according to the adhesive applied (Prime & Bond NT, Single Bond and Clearfil SE Bond), the application (yes/no) of chlorhexidine, and the time point at which it was applied (before or after acid etching the dentin). Composite resin blocks were built up over treated surfaces, and teeth were then stored in water at 37°C for 24 h. Samples were thermocycled, stored under the same conditions, and then vertically sectioned, thus obtaining specimens with 1.0 ± 0.1 mm2 cross-sectional area. Specimens were stressed in tension at 0.5 mm/min crosshead speed. Bond strength results were evaluated using a one-way ANOVA (p < 0.05). The modes of failures were verified using optical microscopy. Dentin disks were obtained from 3 additional teeth treated in the same manner for observation under SEM. The most representative samples of fractured specimens were also observed under SEM. Results: No statistically significant differences of bond strength values were found between any groups. Failures occurred mainly within the bond; exclusively adhesive fractures (adhesive-dentin) were not observed. Conclusion: The 2% chlorhexidine solution, applied before or after acid etching of the dentin, did not interfere with the microtensile bond strength of composite resin to the dentin treated with Prime & Bond NT, Single Bond, or Clearfil SE Bond bonding systems.