Effectiveness of glass ionomer cements in the restorative treatment of radiation-related caries - a systematic review.

PURPOSE: The aim of this systematic review was to investigate the clinical effectiveness of glass ionomer cements (GICs) compared to other restorative materials in the treatment of radiation-related caries. METHODS: Two independent researchers searched literature databases (PubMed, Scopus, Web of Science, Cochrane Library, Lilacs/BBO) and the grey literature to identify clinical trials that compared GICs with other restorative materials for the treatment of radiation-related caries. The clinical criteria considered for the performance of the restorations were based on the parameters of marginal adaptation/anatomical form, secondary caries, retention, and cumulative failures of the restorations. The methodological quality and risk of bias were evaluated using the Cochrane Collaboration tool. RESULTS: From a total of 511, only four articles fulfilled the inclusion criteria. Conventional GIC restorations presented higher marginal adaptation failures than the resin-modified glass ionomer cements (RM-GICs) and composite restorations in all of the follow-up periods. Secondary caries was not observed in conventional GIC restorations throughout the follow-up periods, in three out of four of the included studies. RM-GICs and composite restorations showed significantly lower cumulative failure rates than conventional GICs at 6-, 12-, and 18-month follow-ups. CONCLUSION: Due to insufficient scientific evidence, it was not possible to conclude that GICs are more effective than other restorative materials for the treatment of radiation-related caries.

Fracture strength of extended class I composite restorations with different restorative techniques.

To evaluate the fracture strength of extended Class I restorations with different restorative techniques using nanofilled and nanohybrid composites. Sixty extracted human third molars were prepared with extended Class I cavities and divided into six groups: groups FS-F (Filtek bulk-fill Flow + Filtek Supreme Ultra, 3 M) and GR-F (X-tra base + GrandioSO, VOCO), restored with a flowable bulk-fill composite as a base covered by a nanofilled or nanohybrid composite; groups FB (Filtek One Bulk-Fill, 3 M) and AF (Admira Fusion X-tra, VOCO), restored with a bulk-fill resin composite; and groups FS (Filtek Supreme Ultra, 3 M) and GR (GrandioSO, VOCO), restored incrementally with a nanofilled or nanohybrid composite. Sound extracted teeth (n = 10) were used as a control group (CTL). The specimens were axially loaded until failure. Data were analyzed using one-way ANOVA and Games Howell test (α = 0.05). Groups CTL and GR-F demonstrated significantly higher mean fracture strength when compared to FS, AF, and GR (p < 0.05). Group AF obtained more repairable fractures than the other groups. Restorations made with a nanofilled bulk-fill composite or with conventional resin composites associated with a flowable bulk-fill base were able to reestablish the fracture strength to that of sound teeth.

Occlusal problems, mental health issues and non-carious cervical lesions.

Non-carious cervical lesions (NCCLs) are characterized by a loss of hard dental tissue near the cement-enamel junction with multifactorial etiology. The aim of this study was to demonstrate that occlusal factors as attrition, malocclusion, and bruxism, and mental disorders as depression, stress, and anxiety are involved in the etiology of NCCLs. Salivary samples and clinical data of 340 individuals selected from 6,112 participants were obtained from the University of Pittsburgh School of Dental Medicine Dental Registry and DNA Repository project. The affected group was formed by individuals with NCCL (34 females, 34 males, mean age 55.34 years). In addition, the comparison group was formed by individuals without NCCL (136 females, 136 males, mean age 55.14 years). Eleven single-nucleotide polymorphisms (SNPs) previously associated with mental disorders were genotyped and tested for association with NCCLs. When all occlusal factors were combined there was found a significant association with NCCL (p = 0.000001/adjusted OR 4.38, 95% CI 2.50-7.69). Attrition (OR 3.56, 95% CI 2.00-6.32) and malocclusion (OR 5.09, 95% CI 1.65-15.68) as separate variables showed statistically significant associations with NCCL. There was a significant difference in stress history between the two groups (OR 2.17, 95% CI 1.08-4.39). No associations between NCCLs and the SNPs selected were found. However, when the occlusal factors were analyzed as covariates, associations were found between bruxism and seven of the selected SNPs. Our results suggest that occlusal factors might be associated with NCCLs.

One-year clinical evaluation of bulk-fill flowable vs. regular nanofilled composite in non-carious cervical lesions.

OBJECTIVE: The aim of this double-blind, randomized trial was to evaluate the 1-year clinical performance of a bulk-fill flowable and a regular nanofilled composite in non-carious cervical lesions (NCCLs). METHODS: Twenty-two subjects with at least two NCCLs were enrolled in the study. A total of 89 restorations were performed by a single operator using Filtek Supreme (FS) Ultra Universal or Filtek Bulk (FB) Fill Flowable. A universal adhesive (Scotchbond™ Universal Adhesive) was used with a self-etching approach in dentin. The restorations were evaluated by two independent and previously calibrated examiners at baseline (7 days), 6 months and 1 year, according to the USPHS modified criteria. Mann-Whitney U test was used to analyze the differences between composites and Wilcoxon signed rank test for comparisons between the baseline and follow-ups (α = 5%). RESULTS: One restoration was considered clinically unacceptable due to loss of retention after 6 months in the FS group. FS presented statistically high scores for surface roughness when compared to FB after 1 year (p < 0.05), but both were considered clinically acceptable. After 1 year, the frequency of clinically unacceptable rates was 3.3% for anatomical form in the FB group, 1.1% for retention in the FS group, and 2.2% for marginal adaptation in both groups. All restorations, in both groups, presented score 0 over the 1-year period for marginal staining, postoperative sensitivity, and secondary caries. CONCLUSION: Both composite resins showed acceptable clinical performances for the restoration of NCCLs after 1 year. CLINICAL RELEVANCE: Both bulk-fill flowable and regular nanofilled composites showed good clinical performances for the restoration of NCCLs after 1 year.

Clinical efficacy of resin-based materials for dentin hypersensitivity treatment.

PURPOSE: To evaluate the effect of three resin-based materials in the treatment of dentin hypersensitivity (DH) up to a 6-month follow-up. METHODS: 30 participants (179 teeth) with DH were enrolled in this randomized, double-blind, controlled clinical study. The teeth were randomly allocated into one of three groups: CV (resin-modified glass ionomer varnish - Clinpro XT Varnish), CP (fluoride-containing self-etch adhesive - Clearfil SE Protect) and GB (glutaraldehyde-containing etch-and-rinse adhesive - Gluma 2 Bond). The materials were applied according to the manufacturer's instructions. DH was evaluated by subjects' perception measured on a 0-10 visual analog scale (VAS) after evaporative (air blast) stimuli. The scores were recorded at baseline, immediately and at 1, 3 and 6 months after treatment. The data were analyzed by a two-way ANOVA with repeated measures for "time" and Games-Howell test (α = 0.05). RESULTS: ANOVA detected statistically significant differences among the time intervals, but not among the materials or interactions. There was a significant decrease in sensitivity scores from baseline to all the time points (P< 0.05). However, the differences were not statistically significant among the follow-ups, from immediately until 6 months after treatment (P> 0.05). All the resin-based materials were able to reduce DH up to 6 months after treatment. CLINICAL SIGNIFICANCE: Resin-based materials used as desensitizing agents were effective in reducing DH after a 6-month period and so could be recommended as a safe treatment for sensitive teeth.

Effect of Erosion/Abrasion Challenge on the Dentin Tubule Occlusion Using Different Desensitizing Agents.

The aim of the study was to evaluate dentinal tubule occlusion, measuring the dentin permeability (Lp) and using different desensitizing agents before and after abrasive/erosive challenge. Dentin discs from 42 healthy human third molars were obtained. Minimum Lp was measured after a smear layer simulation using #600 SiC paper and maximum Lp after an immersion in 0.5 M EDTA. The specimens were treated with different desensitizers: two varnishes (Clinpro XT Varnish-CV, Fluor Protector-FP), a paste (Desensibilize Nano P-NP) and a gel (Oxa Gel-OG). The Lp of each specimen was measured immediately after the desensitizers' application. The discs were subjected to erosion/abrasion cycles for 7 days, with 0.5% citric acid solution (6x/day) and tooth brushing (3x/day). Lp was measured after the first, fourth and seventh day of the challenge. The data were analyzed by 3-way ANOVA with repeated measurements and by a Games-Howell test (α=5%). FP and CV did not show significant differences in Lp immediately after application until the 7th day (p<0.05). OG showed a significant increase in Lp after the 4th and 7th days. NP resulted in a significantly higher permeability compared to the other materials immediately after the application and after the 1st day of challenge. All the desensitizers reduced the dentin permeability immediately after application. However, only the varnishes were able to maintain the occlusive effect after the erosion/abrasion challenge.

Performance of Dental Students in Shade Matching: Impact of Training.

OBJECTIVE: The present study evaluated the effect of training on dental students' ability for matching two different shade guides. MATERIALS AND METHODS: The study was conducted in 2012. The participants were 88 male and female undergraduate dental students from Brazil and Portugal, with or without previous color education and vision refractive errors (response rate of 73.33%). They were asked to match a pair set of the shade guides Vita Classical (VC) and Vitapan 3D Master (3DM), with a 20-minutes' rest between each match. The sets were assembled over a neutral gray background and under controlled light. About 7-10 days later, all participants watched a video lecture on color education and repeated the matching procedure. The percentage of matches was calculated and submitted to statistical analysis for the variables gender, geographic region, shade guide and previous color education (Mann-Whitney tests), vision refractive errors (Kruskal-Wallis), and training (Wilcoxon signed rank). All tests were performed at a confidence level of 95%. RESULTS: Training increased the percentage of matches for all groups, except for Portuguese and hyperopic individuals (VC and 3DM) and men (3DM). Previous color education affected VC shade matching before training. Gender, refractive errors, and geographic region did not affect shade matching ability. CONCLUSIONS: Previous education and training in color positively affected shade-matching ability of dental students on shade guide pairing tests. CLINICAL SIGNIFICANCE: The subjectivity of the visual method might not be a clinical concern in daily practice. The human eye can detect small differences in color and visualize the tooth with all its complex geometry, multilayered tissues, and secondary color parameters. Therefore, any color-matching task will be judged by the patient and/or other observers with consideration to this complexity. In other words, visual assessment is paramount to the success/failure of esthetic restorative procedures. The efficiency of the visual color method may be improved by color education through the development of professional color discrimination ability. This would make the students responsible for color selection, reproduction, and evaluation and lead to increased capability over a layperson observer receiving the restorative treatment. (J Esthet Restor Dent 29:E24-E32, 2017).

Effect of Erosion/Abrasion Challenge on the Dentin Tubule Occlusion Using Different Desensitizing Agents

The aim of the study was to evaluate dentinal tubule occlusion, measuring the dentin permeability (Lp) and using different desensitizing agents before and after abrasive/erosive challenge. Dentin discs from 42 healthy human third molars were obtained. Minimum Lp was measured after a smear layer simulation using #600 SiC paper and maximum Lp after an immersion in 0.5 M EDTA. The specimens were treated with different desensitizers: two varnishes (Clinpro XT Varnish-CV, Fluor Protector-FP), a paste (Desensibilize Nano P-NP) and a gel (Oxa Gel-OG). The Lp of each specimen was measured immediately after the desensitizers’ application. The discs were subjected to erosion/abrasion cycles for 7 days, with 0.5% citric acid solution (6x/day) and tooth brushing (3x/day). Lp was measured after the first, fourth and seventh day of the challenge. The data were analyzed by 3-way ANOVA with repeated measurements and by a Games-Howell test (α=5%). FP and CV did not show significant differences in Lp immediately after application until the 7th day (p<0.05). OG showed a significant increase in Lp after the 4th and 7th days. NP resulted in a significantly higher permeability compared to the other materials immediately after the application and after the 1st day of challenge. All the desensitizers reduced the dentin permeability immediately after application. However, only the varnishes were able to maintain the occlusive effect after the erosion/abrasion challenge.

Resumo O objetivo do estudo foi avaliar a permeabilidade da dentina (Lp) usando diferentes agentes dessensibilizantes antes e depois de um desafio abrasivo/erosivo. Discos de dentina foram obtidos a partir 42 terceiros molares humanos. Lp mínima foi medida após uma simulação de smear layer usando lixa de SiC # 600 e a Lp máxima foi medida após imersão em EDTA 0,5 M. As amostras foram tratadas com diferentes dessensibilizantes: dois vernizes (Fluor Protector-FP, Clinpro XT Varnish-CV), uma pasta (Desensibilize Nano P-NP) e um gel (Oxa Gel-OG). A Lp de cada amostra foi medida imediatamente após a aplicação dos dessensibilizantes. Os discos foram submetidos a um ciclo de erosão/abrasão durante 7 dias, com uma solução de 0,5% de ácido cítrico (6x/dia) e escovação (3x/dia). Lp foi medida do primeiro ao sétimo dia do desafio. Os dados foram analisados por ANOVA a 3 critérios com medidas repetidas e teste de Games-Howell (α=5%). FP e CV demonstraram Lp semelhante imediatamente depois da aplicação até 7 dias (p<0,05). OG apresentou um aumento significativo na Lp depois do 4º e 7º dias. NP resultou numa permeabilidade significativamente mais elevada comparada com a dos outros materiais imediatamente após a aplicação e após o primeiro dia de desafio. Todos os dessensibilizantes reduziram a permeabilidade da dentina imediatamente após a aplicação. No entanto, apenas os vernizes foram capazes de manter o efeito oclusivo após o desafio da erosão/abrasão.

Correlative analysis of cement-dentin interfaces using an interfacial fracture toughness and micro-tensile bond strength approach.

OBJECTIVES: To determine the interfacial fracture toughness (iFT) and micro-tensile strength (µTBS) of composite cements bonded to dentin. METHODS: Fifty feldspar ceramic blocks (Vita Mark II, Vita Zahnfabrik) were luted onto dentin using two self-adhesive (G-CEM LinkAce, GC; SpeedCEM, Ivoclar Vivadent), two self-etch (Multilink Primer & Multilink Automix, Ivoclar Vivadent; Scotchbond Universal & RelyX Ultimate, 3 M ESPE), and one etch-and-rinse (Excite F DSC & Variolink II, Ivoclar Vivadent) composite cement (n=10). After 48h in 100% relative humidity at 37°C, one half of each tooth was sectioned in sticks with a chevron notch at the cement-dentin interface and tested in a 4-point bending test setup (iFT). The remaining half of the tooth was sectioned in micro-specimens and stressed in tension until failure (µTBS). The mode of failure was determined with a stereomicroscope at 50× magnification. Data were submitted to Weibull analysis and Pearson's correlation (α=0.05). RESULTS: At 10% probability of failure, no significant differences could be found using iFT, while the etch-and-rinse composite cement Variolink II presented a significantly higher µTBS at this level. At 63.2% probability of failure, the self-adhesive composite cement G-CEM LinkAce revealed a significantly lower µTBS and iFT, and the self-etch cement Multilink Automix also revealed a significantly lower µTBS than all other cements. The correlation found between iFT and µTBS was moderate and not significant (r2=0.618, p=0.11). SIGNIFICANCE: Overall, the etch-and-rinse and 'universal' self-etch composite cements performed best. The micro-tensile bond strength and interfacial fracture toughness tests did not correlate well.

Effect of desensitizing agents on the microtensile bond strength of two-step etch-and-rinse adhesives to dentin.

Desensitizers can be used to control postoperative sensitivity in adhesive restorations. The aim of this study was to evaluate the effect of desensitizing agents on the bond strength of two-step etch-and-rinse adhesive systems to dentin. Forty-two human molars were sectioned to obtain 3-mm-thick dentin discs. The discs were divided into three groups (n = 14 in each) - no-treatment control group (CT), and oxalic acid [BisBlock (BB)] and calcium phosphate [Desensibilize Nano-P (NP)] desensitizers - before the application of two adhesive systems [Adper Single Bond Plus (SB) and One-Step Plus (OSP)]. A nanoparticle composite resin was used to create a 3-mm-thick build-up. The specimens were stored in distilled water for 24 h before a microtensile bond-strength test was performed. The failure modes were determined using a stereomicroscope at 100 × magnification. Specimens were sectioned perpendicular to the interface for scanning electron microscopy analyses. The CT-SB group exhibited the highest bond strength, differing significantly from BB-SB and BB-OSP groups. Mixed failures were prevalent for all groups. Scanning electron microscopy revealed a continuous hybrid layer and resin tags in all groups. Dentin bond strength of etch-and-rinse adhesive systems was reduced by an oxalic acid desensitizer but was not affected by a calcium phosphate-containing desensitizer.

Comparative study of the fluorescence intensity of dental composites and human teeth submitted to artificial aging.

The aim of this study was to evaluate quantitatively the fluorescence of resin composites and human teeth, and to determine the stability of fluorescence after aging. Ten specimens were built using a 1 mm thick increment of dentin composite overlapped by a 0.5 mm thick increment of enamel composite. Ten sound human molars were sectioned and silicon carbide-polished to obtain enamel and dentin slabs 1.5 mm in thickness. Fluorescence measurements were carried out by a fluorescence spectrophotometer before and after thermocycling (2000 cycles, 5°C and 55°C). One-way analysis of variance (ANOVA) with repeated measures and Tukey's test were performed at a significance level of 5%. Most of the tested composites showed significant differences in fluorescence both before and after aging (P < 0.05). Opallis was the only composite whose fluorescence was similar to that of human teeth at both periods of evaluation (P > 0.05), and was the only composite that showed comparable results of fluorescence to the tooth structure before and after thermocycling. With the exception of Filtek Supreme, there were significant reductions in fluorescence intensity for all the tested composites (P < 0.05).

Effect of open-sandwich vs. adhesive restorative techniques on enamel and dentine demineralization: an in situ study.

OBJECTIVES: To assess in situ the effect of different restorative techniques used with fluoride-releasing materials on enamel and dentine demineralization in the presence of a cariogenic challenge. METHODS: Thirty human molars were prepared for 60 Class V cavities, with enamel and dentine margins. The teeth were divided into four groups (n=15): L1 - open sandwich technique with a conventional glass ionomer cement (GIC), L2 - open sandwich technique with a resin-modified GIC, A1 - total-etch bonding with a fluoride-containing adhesive, A2 - total-etch bonding with a nonfluoride-containing adhesive. All the cavities were restored with a nanofilled composite. Fifteen volunteers used appliances containing one specimen from each group. The cariogenic challenge was carried out with a 20% sucrose solution 8×/day for 7 days. The specimens were sectioned for microhardness test and EDS analysis at different depths below the enamel and dentine margins (25, 50 and 100µm) and distances from the tooth-restoration interfaces (25 and 75µm). The data were analyzed by ANOVA and Games-Howell test (α=5%). RESULTS: Both GICs produced higher hardness in enamel at all depth-and-distance combinations, but only L1 produced higher hardness in dentine (p<0.05). L2 and A1 exhibited similar dentine hardness at 25µm distance for all depths (p>0.05). L1 demonstrated significantly higher amounts of calcium in dentine than the other groups, but had similar amounts in enamel to L2 and A1. CONCLUSIONS: The open sandwich technique using conventional GIC proved more effective in reducing enamel and dentine demineralization at depths of up to 100µm under a cariogenic challenge. CLINICAL SIGNIFICANCE: Conventional GICs should be considered the materials of choice for lining of cavities not having all margins in enamel, particularly using the open sandwich technique.

Assessing the use of 35 percent sodium ascorbate for removal of residual hydrogen peroxide after in-office tooth bleaching.

BACKGROUND: The authors conducted a study to quantify the amount of hydrogen peroxide remaining after in-office bleaching and to investigate the effectiveness of 35 percent sodium ascorbate (SA) on removal of the bleaching agent from dentin. METHODS: The authors sectioned 70 extracted human third molars to form 4×4×2-millimeter blocks of dentin and then categorized them into eight groups as follows: group 1, no bleaching; group 2, bleaching (35 percent hydrogen peroxide) and daily measurement; group 3, bleaching plus one application of 35 percent SA for 60 minutes; group 4, bleaching plus one application of SA for 10 minutes; group 5, bleaching plus two applications of SA for 10 minutes each; group 6, bleaching plus two applications of SA for five minutes each; group 7, bleaching plus three applications of SA for one minute each; and group 8, bleaching plus two applications of SA for one minute each. They quantified the amount of residual hydrogen peroxide by using a colorimetric assay with horseradish peroxidase and o-phenylenediamine dihydrochloride as the enzyme and substrate, respectively. RESULTS: The authors analyzed the data by using the Kruskal-Wallis test (α = .05). The results showed that no hydrogen peroxide remained after 120 hours in group 2 and at their respective measurement points in groups 5, 6, 7 and 8, whereas hydrogen peroxide had been removed only partially in groups 3 and 4. CONCLUSION: Two applications of 35 percent SA for one minute each produced the same result--complete removal of the bleaching agent--as that observed five days after tooth bleaching with 35 percent hydrogen peroxide without any application of SA. CLINICAL IMPLICATIONS: In an appropriate concentration, SA facilitates rapid elimination of residual peroxide up to two minutes after bleaching with 35 percent hydrogen peroxide. This finding suggests that clinicians can perform bonding procedures shortly after the bleaching procedure.

Microhardness of dentin underneath fluoride-releasing adhesive systems subjected to cariogenic challenge and fluoride therapy.

OBJECTIVES: The aim of this study was to evaluate the microhardness of dentin subjacent to the bonding interface of composite restorations using fluoride-releasing adhesive systems submitted to pH-cycling regimen associated or not to fluoride therapies. METHODS: Thirty human third molars were prepared with class V cavities with dentin cervical margins. The adhesive systems One-Up Bond F Plus (OU), Prime&Bond NT (NT), Clearfil Protect Bond (CF), Optibond Solo Plus (OP) and also the controls [-] Single Bond 2 (SB) and [+] Ketac Molar (KM) were used previously to composite resin restorations. The restorations were sectioned into four slabs and submitted to different storage media for 15 days: distilled water, pH-cycling, pH-cycling associated to NaF 0.05% and associated to NaF 1.23%. The Knoop microhardness test was performed in dentin at 50, 100, 150 and 300 microm from the adhesive interface. Data was analyzed by three-way ANOVA and Tukey HSD test (p<0.05). RESULTS: KM resulted in significantly higher microhardness when compared to all the adhesive systems at 50 microm, with the exception of OU, that was similar to KM when submitted to pH-cycling alone or associated to 1.23% NaF. Microhardness of dentin was significantly higher with all the tested materials, when pH-cycling was associated to NaF 0.05%, at 50 microm and 100 microm depths. OU resulted in similar dentin hardness at all depths and storage media. CONCLUSIONS: The incorporation of NaF 0.05% fluoride therapy to the cariogenic challenge was capable to recover the original microhardness of dentin at 50 and 100 microm with all the tested materials.

Reaction kinetics of sodium ascorbate and dental bleaching gel.

OBJECTIVE: The aim of this study was to establish the reaction kinetics of 35% hydrogen peroxide and sodium ascorbate and to determine the mass of antioxidant required to neutralize the bleaching gel. METHODS: The method used to quantify sodium ascorbate was based on the United States Pharmacopeia (1995)(26). Oxidation-reduction titration was used to confirm the concentration of hydrogen peroxide and sodium ascorbate and to determine the reaction kinetics between them. RESULTS: The results indicated a direct correlation between the mass of hydrogen peroxide and that of the antioxidant agent. In addition, 5 min of contact was sufficient to neutralize the hydrogen peroxide used. CONCLUSION: This in vitro study showed that the amount of sodium ascorbate required for reduction of hydrogen peroxide is directly related to the concentration of the latter. In addition, the reaction kinetics between oxidant and antioxidant showed that a longer application time for sodium ascorbate does not influence the effectiveness of the reaction and that 5 min is sufficiently long for this antioxidant to exert an antioxidant effect.

Effect of reservoirs on gingival inflammation after home dental bleaching.

OBJECTIVE: To evaluate the influence of reservoirs on the gingival mucosa of patients submitted to at-home bleaching with 16% carbamide peroxide. METHOD AND MATERIALS: Nineteen nonsmoking male patients, 18 to 25 years of age, were submitted to home bleaching with a 16% carbamide peroxide gel for 2 consecutive hours for 21 days. The custom-made mouth trays were made with a reservoir on only the left side and cut anatomically 1 mm beyond the gingival margin. Smears of the gingival mucosa were obtained by the exfoliation cytology in liquid media technique before (control), immediately after, and 30 and 45 days after treatment. The samples were processed in the laboratory and evaluated according to Papanicolaou's criteria of malignity. Statistical analysis was carried out by McNemar test, 2 proportions test, and Wilcoxon test with a level of significance of 1%. RESULTS: The presence of a reservoir in the custom tray resulted in an increase of inflammation only immediately after the bleaching procedure. After 30 and 45 days, the difference between inflammation on the sides with and without a reservoir was not statistically significant. Significant differences were found in the degree of inflammation, classified as predominantly mild on the nonreservoir side and moderate on the reservoir side (P < .01). CONCLUSIONS: A 16% carbamide peroxide bleaching gel caused gingival inflammation immediately after the procedure and persisted until 45 days after the bleaching treatment. The use of a reservoir in the custom tray for home bleaching resulted in higher rates and higher intensity of gingival inflammation.

Effect of different surface treatments on the repair bond strength of indirect composites.

PURPOSE: To evaluate the tensile bond strength of indirect composites repaired with different surface treatments and direct composites. METHODS: 180 specimens were prepared with Targis, belleGlass HP and Sculpture indirect composites, light-activated and post-cured according to the manufacturers' recommendations. The specimens were stored in distilled water for 24 hours at 37 degrees C. The bonding surfaces were prepared with air abrasion, hydrofluoric acid or hydrofluoric acid followed by a neutralizing solution. All the treated surfaces were subject to the application of a silane and a bonding agent before the repair procedures with Tetric Ceram and Tetric Flow for the Targis specimens, Herculite XRV and Revolution for the belleGlass HP specimens and Sculp-It and Flow-It for Sculpture specimens. The tensile bond strength tests were carried out using a universal testing machine at cross-head speed of 0.5 mm/minute. The type of fracture was observed under a light microscope at x40 magnification. Data were analyzed by a two-way ANOVA and Tukey's post-hoc tests (P < 0.05). RESULTS: Targis showed a statistically higher repair bond strength than belleGlass HP and Sculpture, which were not significantly different from each other. Air abrasion increased the repair bond strength of belleGlass HP and Sculpture. For Targis, all the surface treatments resulted in similar repair bond strength. The different viscosity of repair composites did not affect the repair of indirect composites. Fractured surfaces showed mostly adhesive failures, mainly with hydrofluoric acid treatment.

Sorption and solubility of composites cured with quartz-tungsten halogen and light emitting diode light-curing units.

AIM: The objective of this study was to evaluate the effect of light polymerization on water sorption and solubility of hybrid composites. METHODS AND MATERIALS: Three composite resins were used to make discs cured with either quartz-tungsten halogen (QTH) or light emitting diode (LED) curing units. The specimens were stored in a desiccator at 37 degrees C and weighted to a constant mass, then immersed in deionized water for different periods of time, and reconditioned until achieving a constant mass. Sorption and solubility were calculated and subjected to analysis of variance (ANOVA) and Tukey tests (p<0.01). RESULTS: There were no statistically significant differences between the light sources. Water sorption increased with storage time for all the composites. The lowest sorption was observed for Herculite XRV, followed by Tetric Ceram, and Filtek Z250. Increased storage times reduced the solubility of Filtek Z250 but did not affect the solubility of Herculite XRV and Tetric Ceram. CONCLUSION: Water sorption and solubility of composites are not affected by the type of polymerization when the same intensity and exposure times are used. Thus, the differences found are probably related to the composition of the materials. CLINICAL SIGNIFICANCE: Water sorption and solubility of composites can lead to a shortened service life. However, these properties are not correlated to the type of polymerization.

Effects of irradiance, wavelength, and thermal emission of different light curing units on the Knoop and Vickers hardness of a composite resin.

The aim of this study was to evaluate the effects of irradiance, light emission wavelength, and heating of different light curing units on the Knoop and Vickers hardness of a hybrid composite resin. The specimens were irradiated during 40 s with ten different light curing units, LEDs, and halogen lights. The spectral emission of each light curing unit was assessed by a spectrometer, the irradiance was measured by two commercial radiometers, and the heating measured with a thermocouple. After 48 h of storage in a dark recipient under a 100% humidity condition, the Knoop and Vickers hardness tests were carried out. The hardness results were analyzed by ANOVA, and Tukey HSD test (p < 0.05). The results showed that the surface hardness of the composite resin depends not only on the irradiance, but strongly on the emission wavelength and heating of the light curing units. It was observed, a linear correlation between the conversion degree and radiant exposure. In addition, it is suggested that the well known base to top surface hardness ratio convention of 80-90% is not appropriate to evaluate curing efficiency of composites, since the top surface is not always sufficiently polymerized.