Blue Laser for Polymerization of Bulk Fill Composites: Influence on dentin bond strength and temperature rise during curing and co-curing method.

Blue diode lasers are alternative curing devices for dental composites. The aim of this study was to investigate the influence of blue diode laser polymerization on shear bond strength of bulk fill composites to human dentin and temperature rise during two types of polymerization. Composite cylinders of SDR Plus(SDR) and Ever X Flow(EX) were bonded to dentin slabs using Adhese Universal and curing devices blue diode laser (449 nm, 1.6 W) and Power Cure LED. For each material and curing device there were two polymerization approaches: 1)conventional: separate curing of adhesive; 2)co-curing: simultaneous adhesive and composite curing. Polymerization modes for each material in conventional and co-curing(c) approach were: blue laser 2000 mW/cm2 for 5 s (L5 and L5c); blue laser 1000 mW/cm2 for 10 s (L10 and L10c); Power Cure 2000 mW/cm2 for 5 s (LED5 and LED5c); Power Cure 1000 mW/cm2 for 10 s (LED10 and LED10c). Temeperature was measured using thermal vision camera. For SDR, the highest bond strength was 24.3 MPa in L10c, and the lowest 9.2 MPa in LED5c. EX exhibited the highest bond strength(21.3 MPa) in LED5, and the lowest in L5(7.7 MPa). The highest temperature rise for SDR was in L10 and L5 (7.3 and 7.2 °C), and the lowest in LED5(0.8 °C). For EX, the highest temperature rise was in L5 (13.0 °C), and the lowest in LED5 (0.7 °C). Temperature rise was higher during blue laser polymerization, especially at high intensity and with conventional curing. Preferable blue laser curing mode is co-curing at 1000mW/cm2 for 10 s.

Micro-CT analysis and leakage of bioceramic retrofillings after ultrasonic and Er:YAG laser cavity preparations: an in vitro study.

The purpose of the study was to determine the influence of preparation techniques on marginal adaptation and sealing of Biodentine™ and TotalFill® RRM bioceramic retrograde fillings. Fifty-two single-root teeth extracted for periodontal reasons were used. Root canals were instrumented using Reciproc Blue #25 and obturated using a single cone technique with an AH Plus® root canal sealer. Retrograde cavities were prepared with Piezomed device (Piezo), Er:YAG laser in short-pulse(SP) and quantum square pulse(QSP) modes and filled with Biodentine™ (BD) or TotalFill® RRM (TF). There were 6 groups (n=8): (1) Piezo BD, (2) Piezo TF, (3) SP BD, (4) SP TF, (5) QSP BD, and (6) QSP TF, and positive and negative controls (n=2). Micro-CT analysis was performed on two samples from each group. Percentage volumes of internal and external voids in apical 1.5 mm were determined. Rhodamine B dye leakage was done on six samples. The samples were cut longitudinally and examined under a stereomicroscope. Digital recordings were analyzed in ImageJ software. The deepest penetration of color in mm was recorded. The data were statistically analyzed using ANOVA and Duncan's test at the level of significance α=0.05. TotalFill® RRM performed significantly better than Biodentine™ in terms of sealing (p<0.05) and marginal adaptation, as evaluated by micro-CT. Sealing was significantly better in SP compared to QSP mode preparations (p<0.05). Differences between Piezomed and laser modes were not significantly different (p>0.05). Sealing was statistically significantly better with TotalFill® RRM compared to Biodentine™ and in Er:YAG SP preparations compared to Er:YAG QSP.

Influence of pH Cycling on Erosive Wear and Color Stability of High-Viscosity Glass Ionomer Cements.

The purpose of this in vitro study was to evaluate erosive wear and change in color of high-viscosity glass ionomer cements after pH cycling in two erosive media. There were 3 experimental groups with 22 samples each, (I) EQUIA Forte HT without coat, (II) Fuji IX and (III) Ketac Universal Aplicap. Each group was randomly divided into three subgroups (n = 6-8) further exposed to different environments, (1) distilled water, (2) green tea (pH 3.78) and (3) Aceto balsamico vinegar (pH 3.0). Mass and L* a* b* values were recorded before and after pH cycling. The samples in subgroups 2 and 3 were exposed to the acidic media two times a day for 10 min, over a period of 14 days. The differences among materials and erosive effects of the three media were tested using three-way analyses of variance with post hoc LSD test at the significance level p < 0.05. The effect of pH cycling in Aceto balsamico and green tea was degrading for all three materials. pH cycling in Aceto balsamico caused significantly higher erosive wear than pH cycling in Fuzetea and storage in distilled water, in all materials (p < 0.05). pH cycling in both acidic media and in the control group resulted in a significant change in L* a* and b* (p < 0.05). The L* value decreased significantly and the a* and b* values increased significantly (p < 0.05).

Compressive Strength of Conventional Glass Ionomer Cement Modified with TiO2 Nano-Powder and Marine-Derived HAp Micro-Powder.

The aim of this research was to investigate the compressive strength (CS), breaking strength (BS), and compressive modulus (CM) of conventional glass ionomer cement (GIC) modified with TiO2 nano particles, marine-derived hydroxyapatite (md-HAp) microparticles (<45 µm), and a combination of TiO2 NP and md-HAp particles. The materials used in the study were conventional GIC Fuji IX GP Extra (GC Corporation, Tokyo, Japan), TiO2 powder P25 (Degussa, Essen, Germany), and HAp synthesized from cuttlefish bone and ground in a mortar to obtain md-HAp powder. md-HAp was characterized using FTIR and SEM analysis. There were four groups of GIC samples: (i) Fuji IX control group, (ii) powder modified with 3 wt% TiO2, (iii) powder modified with 3 wt% HAp, and (iv) powder modified with 1.5 wt% TiO2 + 1.5 wt% HAp. Measurements were performed in a universal testing machine, and CS, BS, and CM were calculated. Statistical analysis was performed using ANOVA and Tukey's tests. CS, BS, and CM differed significantly between the Fuji IX control group and all experimental groups while differences between the experimental groups were not statistically significant. The addition of TiO2 NP, md-HAp micro-sized particles, and a combination of TiO2 and md-HAp reduced the CS, BS, and CM of conventional GICs when mixed at the powder/liquid (p/l) ratio recommended by the manufacturer.

Effect of Nano-Filled Protective Coating and Different pH Enviroment on Wear Resistance of New Glass Hybrid Restorative Material.

The purpose of the study was to determine the wear rate of Equia Forte HT Fil with Equia Forte Coat or without coating and compare it with Fuji IX GP high-viscosity glass ionomer cement (GIC) in conditions with acid load or at neutral pH. The samples were stored for 7 days: (1) in artificial saliva, (2) in artificial saliva and cyclically exposed to low pH, and (3) in distilled water and cyclically exposed to low pH. Wear was determined by measuring the difference in mass before and after brushing in an abrasion testing device. The wear of Fuji IX GP was significantly higher than that of Equia Forte HT Fil with or without coating (p = 0.000). The difference between Equia Forte HT Fil with and without Coat was not statistically significant (p < 0.803). The differences in wear resistance between samples stored in saliva and in distilled water were not significant (p = 0.588). Periodic exposure to the low pH solution significantly affected the wear resistance of all materials (p = 0.000). Equia Forte HT Fil was more resistant to wear than Fuji IX GP in all storage conditions. A resinous coat did not significantly increase wear resistance.

Mechanical Properties of Glass Ionomer Cements after Incorporation of Marine Derived Porous Cuttlefish Bone Hydroxyapatite.

The purpose of this study was to evaluate the effects of the incorporation of hydroxyapatite (HA) derived from cuttlefish bone on the mechanical properties of glass ionomer cements (GIC). Fuji II LC and Fuji IX GP Extra (GC Corporation, Tokyo, Japan) were used in the study. There were four groups (n = 11-18) for each material: a group without the addition of HA particles and three groups modified by incorporation of 2, 5, and 10 wt% HA. The tests were performed on a universal testing machine (Shimadzu, Duisburg, Germany) and descriptive statistics, two-way analysis of variance (ANOVA) for the comparison of three mechanical properties, and one-way ANOVA for the comparison of different concentrations for each material were performed. Regarding the Fuji IX groups, compressive strength (CS) and flexural strength (FS) were highest in the group without HA particles added. The differences in CS between the Fuji IX group without HA particles and the Fuji IX groups with 2 wt% HA and 10 wt% HA were significant. The Fuji II 5 wt% HA group exhibited higher diametral tensile strength (DTS) and CS than other Fuji II groups, but not significantly. The Fuji II group, modified with 10 wt% HA, exhibited significantly higher FS than the Fuji II group without HA particles (p < 0.05). Porous HA incorporated into the Fuji IX groups had a significant impact on mechanical properties only in the Fuji IX 5 wt% HA group. Fuji II groups modified with 10 wt% HA showed the most favorable results with respect to FS.

Impact of oral hygiene instructions on plaque index in adolescents.

OBJECTIVE: The objective of the study, which consisted of a motivational lecture and hands-on training, was to evaluate the role of oral hygiene education for adolescents. METHODS: The study population included sixty-two high school students between fourteen and fifteen years of age (thirty males and thirty-two females). The response rate was 76.5%. The measurement of oral hygiene level was performed using the modified Green Vermilion Index (GVI). The values were recorded at baseline, one week, three months, and six months after education through motivational lecture and hands-on training was performed. Descriptive and nonparametric statistical methods were used in statistical analysis. Level of significance was 0.05. RESULTS: At the beginning of the study, the GVI of all examined subjects was 3.52 (SD = 0.70). One week after the motivational lecture and training, it decreased to 2.64 (SD = 0.69). Three months later, the level of plaque index had the lowest value (1.44; SD = 0.66). At the end of the study the level of plaque index increased to 2.52 (SD = 0.86). CONCLUSIONS: A significant oral hygiene improvement in adolescents as a result of education was presented. However, due to a decline in oral hygiene level six months after the education, there is a need for educational programmes continuity.

Cytotoxicity and Genotoxicity of Resin Based Dental Materials in Human Lymphocytes In Vitro.

The aim of this in vitro study was to evaluate cytotoxicity and genotoxicity of six different dental nanocomposite materials, three conventional ones and three flowable composite resin materials, in human lymphocytes. The following materials were tested: Tetric EvoCeram, Tetric EvoFlow, Filtek Ultimate, Filtek Ultimate Flow, G-aenial and G-aenial Flo. Cytotoxicity was evaluated for two mass concentrations (0.007 g/mL and 0.013 g/mL) of each material, non-cured and cured, after 4 hours and 24 hours. Genotoxicity was evaluated using micronucleus assay under the same conditions as applied during the investigation of cytotoxicity. Uncured forms of Tetric EvoCeram, Tetric EvoFlow and Filtek Ultimate Flow in higher mass concentration caused genotoxic effect. Uncured G-aenial Flo in higher mass concentration induced apoptosis and necrosis. Uncured Tetric EvoFlow and uncured Filtek Ultimate Flow in higher mass concentration induced early apoptosis after both test periods. None of the conventional composite resin materials tested showed cytotoxicity except for uncured G-aenial, which induced apoptosis in higher mass concentration in both test periods. In conclusion, under the conditions of this in vitro study, cured conventional composites did not show cytotoxic or genotoxic effect, which is important for clinical application of these materials, whereas uncured forms exhibited certain level of cytotoxicity and genotoxicity, mainly because of monomers in their composition.

The Oral Status of Adult Population in the Croatian Town of Knin: a Cross Sectional Study.

THE AIM: Epidemiologic studies in many countries show uneven distribution of oral diseases (primarily caries) within the population. This is why more studies are oriented towards specific regions or subpopulations instead of large scale national surveys. The major purpose of this cross sectional study was to obtain relevant data about the oral status of the population of Knin and its surroundings according to the WHO criteria. SUBJECTS AND METHODS: The study included 414 participants aged between 18 and 65. The recorded variables included general anamnestic data, extraoral status, oral mucosa status, temporomandibular joint status, dental, periodontal and prosthetic status, and the need for dental restoration. The comparison between different groups regarding age, gender, educational level and origin was made. RESULTS: DMFT index was 17.3 - with on average 1.7 caries, 6.2 fillings, and 9.4 teeth extracted. SiC index equaled 26.4. The difference was significant regarding the level of education and age (p<0.001). The percentages of individuals with the highest CPI scores from 0-4 were 27.3, 16.9, 36.5, 16.4 and 2.9%, respectively. The difference between the age groups in CPI scores was statistically significant, while the differences according to the gender and origin were not significant (p=0.001). CONCLUSION: The population of Knin and the surrounding area exhibited very bad oral status which can be attributed to the consequences of the war in the 1990-ies, the economic transition, and the lack of national program for oral health promotion.

Region- and stage-specific effects of FGFs and BMPs in chick mandibular morphogenesis.

The mandibular processes are specified as at least two independent functional regions: two large lateral regions where morphogenesis is dependent on fibroblast growth factor (FGF)-8 signaling, and a small medial region where morphogenesis is independent of FGF-8 signaling. To gain insight into signaling pathways that may be involved in morphogenesis of the medial region, we have examined the roles of pathways regulated by FGFs and bone morphogenetic proteins (BMPs) in morphogenesis of the medial and lateral regions of the developing chick mandible. Our results show that, unlike in the lateral region, the proliferation and growth of the mesenchyme in the medial region is dependent on signals derived from the overlying epithelium. We also show that medial and lateral mandibular mesenchyme respond differently to exogenous FGFs and BMPs. FGF-2 and FGF-4 can mimic many of the effects of mandibular epithelium from the medial region, including supporting the expression of Msx genes, outgrowth of the mandibular processes and elongation of Meckel's cartilage. On the other hand, laterally placed FGF beads did not induce ectopic expression of Msx genes and did not affect the growth of the mandibular processes. These functional studies, together with our tissue distribution studies, suggest that FGF-mediated signaling (other than FGF-8), through interactions with FGF receptor-2 and downstream target genes including Msx genes, is part of the signaling pathway that mediates the growth-promoting interactions in the medial region of the developing mandible. Our observations also suggest that BMPs play multiple stage- and region-specific roles in mandibular morphogenesis. In this study, we show that exogenous BMP-7 applied to the lateral region at early stages of development (stage 20) caused apoptosis, ectopic expression of Msx genes, and inhibited outgrowth of the mandibular processes and the formation of Meckel's cartilage. Our additional experiments suggest that the differences between the effects of BMP-7 on lateral mandibular mesenchyme at stage 20 and previously reported results at stage 23 (Wang et al., [1999] Dev. Dyn. 216:320-335) are related to differences in stages of differentiation in that BMP-7 promotes apoptosis in undifferentiated lateral mandibular mesenchyme, whereas it promotes chondrogenesis at later stages of development. We also showed that, unlike mandibular epithelium and medially placed FGF beads, medially placed BMP-7 did not support outgrowth of the isolated mesenchyme and at stage 20 induced the formation of a duplicated rod of cartilage extending from the body of Meckel's cartilage. These observations suggest that BMPs do not play essential roles in growth-promoting interactions in the medial region of the developing mandible. However, BMP-mediated signaling is a part of the signaling pathways regulating chondrogenesis of the mandibular mesenchyme.