Effects of bleaching gels on the surface microhardness of tooth-colored restorative materials in situ

OBJECTIVES: The purpose of this study was to evaluate the effects of a home bleaching gel containing 15% carbamide peroxide on the surface microhardness of four tooth-colored restorative materials in situ. METHODS: Four types of tooth-colored restorative materials, including a nanocomposite resin (Filtek Z350), a packable composite resin (Filtek P60), a polyacid-modified composite (Dyract AP), and a glass-ionomer cement (Ketac Molar Easymix), were used in this study. Each material was divided into two groups equally (n=18): bleaching group and control group. Thirty-six Chinese volunteers were recruited and stone casts were constructed for their upper jaws. Two of the four types of restorative materials were randomly selected and mounted on the first or second molar of the cast for each subject. With respect to each material selected, two specimens from each group were put at a random side. Then custom-fabricated trays containing specimens were fabricated. The participants wore the tray in the daytime, and applied the bleaching gel for the side containing specimens of bleaching group during the night. Surface microhardness measurements were obtained on the top surface of each sample on the different time periods. RESULTS: There was a statistically significant increase in the surface microhardness of Ketac Molar Easymix due to the exposure to 15% carbamide peroxide, while it produced a significant decrease for Dyract AP. Following immersing in saliva without bleaching agent, Ketac Molar Easymix showed a significant increase in surface microhardness. CONCLUSIONS: The effects of 15% carbamide peroxide on surface microhardness were material dependent. Immersing in saliva produced a surface hardening effect of glass-ionomer cement.     

漂白剂对玻璃离子水门汀类材料充填Ⅴ类洞边缘微渗漏的影响

目的评估漂白凝胶和洁白牙贴对3种不同的玻璃离子水门汀类材料边缘微渗漏的影响。方法在45颗离体健康前磨牙的颊舌侧制备Ⅴ类洞,随机分为A、B、C组,分别使用加强型玻璃离子水门汀KetacTM Molar Easymix、复合体F2000、复合体Dyract AP充填,每个大组再分为3个亚组,第1组和第2组分别使用质量分数14％过氧化氢（HP）洁白牙贴和10％过氧化脲（CP）凝胶进行漂白,第3组为对照组。所有样本置入37 ℃蒸馏水中保存7 d后冷热循环500次,然后进行漂白。漂白21 d后置于碱性品红溶液中染色24 h,沿牙体长轴通过充填体中央颊舌向剖开牙齿,体视显微镜下观察并测量染料渗入窝洞壁的深度。结果2种漂白方式对充填体边缘微渗漏的影响没有明显差异（P>0.05）;与对照组相比,2种漂白方式对B、C组的微渗漏均没有产生明显影响（P>0.05）,但均可使A组的微渗漏增加（P<0.05）。结论10％CP凝胶和14％HP洁白牙贴对充填体边缘微渗漏的影响无明显差异;漂白不会影响复合体的微渗漏,但会增加加强型玻璃离子水门汀的微渗漏。     

Liner and light exposure: effect on in-vitro Class V microleakage

This in vitro study evaluated the influence of different glass ionomer liners and curing methods on microleakage of resin composite restorations. Class V root preparations were made in 120 bovine incisors randomly divided into 12 groups according to liner and curing method. The resin composite system (Single Bond + Z100) was inserted and polymerized in one increment in all groups. Cavity preparations were either not lined (control), lined with a resin modified glass-ionomer cement (Vitrebond) or a conventional glass-ionomer cement (Ketac Bond). The restorations were light-cured using one of four curing methods. The teeth were thermocycled and immersed in 0.5% basic fuchsin, sectioned, and dye penetration was measured (Image Tool). No significant difference in leakage among conventional, ramp or pulse-delay methods was seen. High intensity light groups showed significantly greater penetration compared to other curing methods. No significant difference existed in marginal leakage between liners, but microleakage was significantly higher in groups restored using no liner. No relationship between lining technique and light curing method was observed. The use of glass ionomer liners reduced microleakage, while high intensity light curing produced the greatest dye penetration.     

根管充填材料边缘微渗漏体外实验研究

目的 对比4种充填材料的边缘微渗漏情况,为其临床应用提供合理指导。方法 选择2013年1—6月青岛大学医学院附属医院口腔科因牙周病或阻生齿而拔除的健康新鲜后牙60颗,备洞后随机分为6组,每组10颗,分别使用FiltekTM Z250复合树脂（A1、A2组）、KetacTM N100树脂加强型玻璃离子（B1组）、KetacTM Molar Easymix型玻璃离子（B2、B3组）、F2000 Compomer玻璃离子复合体（B4组）充填窝洞。其中A2组充填后充填体表面涂布Adper Single Bond 2粘接剂,B3组充填后充填体表面涂布凡士林,而其他各组充填后表面不做任何处理。经冷热交替实验后,记录各组染料渗入窝洞壁与充填体之间的深度,并进行统计分析。结果 A2组微渗漏最小,B2组微渗漏最大,与其他组（A1、B1、B3、B4）相比差异有统计学意义（P < 0.05）;A1、B1、B3、B4组间两两比较差异均无统计学意义（P > 0.05）。结论 复合树脂、树脂加强型玻璃离子、玻璃离子复合体的边缘微渗漏均小于传统型玻璃离子;表面涂布隔湿剂后能增强上述材料的边缘封闭性能。     

Microleakage of various cementing agents for full cast crowns.

OBJECTIVES: To evaluate microleakage and marginal gaps in full cast crown restorations bonded with six different types of cementing agents. METHODS: Sixty non-carious human premolars and molars were prepared in a standardized manner for full cast crown restorations. The mesial and distal margins were located in dentin, while the vestibular and palatal/lingual margins were located in enamel. Crowns were made from a high-gold alloy using a standardized technique. The specimens were randomized to six groups of cementing agents: one zinc-phosphate cement (Harvard cement), one conventional glass-ionomer cement (Fuji I), one resin-modified glass-ionomer cement (Fuji Plus), two standard resin cements (RelyX ARC, Panavia F), and one self-adhesive universal resin cement (RelyX Unicem). After 4 weeks of storage in distilled water at 37 degrees C, the specimens were subjected to 5000 thermocycles ranging from 5 to 55 degrees C. Then, they were placed in a silver nitrate solution, embedded in resin blocks, and vertically cut in buccolingual and mesiodistal direction. Subsequently, the objects were evaluated for microleakage and marginal gap using a high-resolution digital microscope camera. RESULTS: A number of inter-group differences were statistically significant. RelyX Unicem showed the smallest degree of microleakage both in enamel and in dentin. Panavia F und RelyX Unicem were associated with significantly larger marginal gaps than all other cementing agents. No association was observed between microleakage and marginal gap other than a weak direct correlation when using Harvard cement on enamel. SIGNIFICANCE: The cementing agents investigated revealed different sealing abilities. These differences were not associated with specific types of materials.     

The physical-mechanical performance of the new Ketac Molar Easymix compared to commercially available glass ionomer restoratives

OBJECTIVES: To evaluate the time dependence of physical-mechanical performance of glass ionomer restoratives. METHODS: The physical-mechanical properties of Ketac Molar Easymix in comparison to four handmix glass ionomer restoratives were evaluated by testing the compressive and flexural strength, acid erosion and solubility. By testing the properties in the early and late setting phase it was determined how fast the level of material characteristics is achieved. IR spectroscopy was used for monitoring the acid-base reaction. RESULTS: The compressive strength after 1 and 24h setting time show that Ketac Molar Easymix and Fuji IX demonstrate a significantly higher performance. Ketac Molar Easymix exhibits by far the highest flexural strength 1h after start of setting. After 24h, it remains at this high level and only Vitro Molar and Fuji IX come close. Ketac Molar Easymix and Fuji IX show the lowest solubility in neutral media after 24h and 7d. It is remarkable that the solubilities of Ionofil Molar, Vitro Molar and Vidrion R stored in water for 24h are higher than those of Ketac Molar Easymix and Fuji IX obtained after 7d water immersion. In acidic media Ketac Molar Easymix is least prone to acid erosion. CONCLUSIONS: For clinical success of a filling material the early achievement of a high physical-mechanical performance is mandatory to minimize the risk of early damage to a restoration. With the high flexural strength reached after 1h combined with the lowest susceptibility for acid-attack and solubility in water, Ketac Molar Easymix, from 3M ESPE, provides the best performance of any materials tested.     

过氧化氢酶对外漂白后树脂充填体边缘微渗漏的影响

目的： 观察过氧化氢酶对10%过氧化脲外漂白后复合树脂充填体边缘微渗漏的影响。方法： 选取牙体健康完整的人离体前磨牙40颗,随机分为4组,第1组不漂白直接进行树脂充填,第2组外漂白后立即树脂充填,第3组外漂白后将牙在人工唾液中浸泡3周再进行树脂充填,第4组外漂白后先用过氧化氢酶处理窝洞再进行树脂充填。然后将4组样本进行2000个周期的冷热循环,应用2%亚甲基蓝染色24 h,体视显微镜下观察剖面树脂充填体的微渗漏程度,采用SPSS17.0软件包对数据进行统计学分析。结果： 第1组微渗漏值最低,第2组微渗漏值最高,第3组微渗漏值显著高于第1组但与第2组相比无显著差异（P>0.05）;第4组微渗漏值较第2组显著下降（P<0.05）。结论： 10%过氧化脲外漂白致树脂充填体边缘微渗漏明显增加,树脂充填前应用过氧化氢酶处理窝洞,可有效减少微渗漏,延迟充填不能有效改善微渗漏。     

Compressive strength of two newly developed glass-ionomer materials for use with the Atraumatic Restorative Treatment (ART) approach in class II cavities

ObjectivesThe null-hypotheses tested were that no difference in compressive strength of ART class II cavities exists between those restored with (1) glass-carbomer and a commonly used glass-ionomer; (2) KMEM and the commonly used glass-ionomer and; (3) glass-carbomer and KMEM.Methods100 molar teeth, stratified by size, were randomly allocated to the four test groups. Large ART class II cavities were drilled and restored with Clearfil photoposterior (negative control), Fuji IX (positive control), Glass-carbomer and Ketac? Molar Easymix (KMEM) (experimental groups). Half of the samples in each test group were 5000 times thermocycled between 5 °C and 55 °C, with a 30 s dwell time in each bath and a transfer time of 10 s. The restorations were statically tested at the marginal ridge until failure, using a rounded rectangular testing rod at crosshead speed of 1.0 mm/min. ANOVA and Student's t-test were applied to test for differences between the dependent variable (compressive strength at the final breaking point) and the independent variables (thermocycling and restorative material).ResultsRestorations of Clearfil photoposterior had a statistically significant higher mean compressive strength value at final breaking point than those of the three glass-ionomers tested (p = 0.0001). No thermocycling effect was observed (p = 0.19). ANOVA between the three glass-ionomer materials and mean compressive strength at final breaking point showed no statistically significant difference (p = 0.09).SignificanceClass II ART cavities restored with the newly launched Glass-carbomer and Ketac? Molar Easymix were not significantly more fracture resistant than comparable restorations using the conventional glass-ionomer Fuji IX.     

Clinical evaluation of multisurface ART restorations

The aim of this study was to evaluate the performance of two different glass-ionomer cements: a high-density (Ketac Molar - ESPE) and a resin-modified cement (Fuji VIII - GC) using the Atraumatic Restorative Treatment technique to restore multisurface cavities in permanent teeth. A total of 60 ART restorations (30 with each material) were placed in schoolchildren (9-16 years of age) by two operators. After a period of 6 months, two independent examiners evaluated 59 restorations according to the criteria used in previous ART studies. Data were submitted to McNemar and Fischer tests. The success rate of the treatment was 98.3%. One restoration (Ketac Molar) was replaced by another material and was recorded as failure. The success rates of the restorations were 100% and 96.6% for Fuji VIII and Ketac Molar, respectively. There was no statistically significant difference in the restorations success between baseline and 6 months (p>0.05). In the same way, no significant differences were found between materials, cavity types or operators (p>0.05). The ART approach was highly appropriate and effective in restorations involving two or more tooth surfaces, after 6 months. The results showed a promising performance of the ART technique with both materials.     

3种表面保护剂对玻璃离子水门汀表面硬度的影响

目的研究不同表面保护剂对玻璃离子水门汀表面硬度的影响,讨论最适于临床应用的防水涂层材料.方法选取3种玻璃离子水门汀为研究对象,分别为KetacTM Molar Easymix、 GC FujiⅡ LC、 KetacTM N100.每种材料制备30个圆盘状样本,随机分为3组：对照组、凡士林涂布组、 GLUMA Comfort Bond涂布组.在样本材料完成初期固化后表面涂布表面保护剂,将样本浸于人工唾液中,置于37℃恒温箱中.用显微硬度计分别于1 h、24 h、1周、1月时测定样本的微硬度,每个样本上每次测定5个位置取平均值,记录微硬度值,采用SPSS 13.0软件对数据进行t检验.结果对于GC FujiⅡ LC,3种表面保护剂对材料微硬度的影响的差异无统计学意义.对于KetacTM Molar Easymix,凡士林涂布组在24 h的微硬度值高于对照组. KetacTM N100的凡士林涂布组在24 h的微硬度值高于GLUMA Comfort Bond涂布组.结论粘接树脂作为表面保护剂在材料表面形成的致密保护膜不利于材料的固化反应,凡士林可作为表面保护剂以提高材料的远期硬度.     

Class I gap-formation in highly-viscous glass-ionomer restorations: delayed vs immediate polishing

This in vitro study evaluated the effects of delayed versus immediate polishing to permit maturation of interfacial gap-formation around highly viscous conventional glass-ionomer cement (HV-GIC) in Class I restorations, together with determining the associated mechanical properties. Cavity preparations were made on the occlusal surfaces of premolars. Three HV-GICs (Fuji IX GP, GlasIonomer FX-II and Ketac Molar) and one conventional glass-ionomer cement (C-GIC, Fuji II, as a control) were studied, with specimen subgroups (n=10) for each property measured. After polishing, either immediately (six minutes) after setting or after 24 hours storage, the restored teeth were sectioned in a mesiodistal direction through the center of the model Class I restorations. The presence or absence of interfacial-gaps was measured at 1000x magnification at 14 points (each 0.5-mm apart) along the cavity restoration interface (n=10; total points measured per group = 140). Marginal gaps were similarly measured in Teflon molds as swelling data, together with shear-bond-strength to enamel and dentin, flexural strength and moduli. For three HV-GICs and one C-GIC, significant differences (p<0.05) in gap-incidence were observed between polishing immediately and after one-day storage. In the former case, 80-100 gaps were found. In the latter case, only 9-21 gaps were observed. For all materials, their shear-bond-strengths, flexural strength and moduli increased significantly after 24-hour storage.     

Shear bond strength of glass-ionomer cements to air-abraded dentin

PURPOSE: The aim of this in vitro study was to evaluate the shear bond strength of two conventional glass-ionomer cements to bovine dentin when using the air-abrasion technique for cavity preparation. MATERIALS AND METHODS: Forty bovine central incisors were selected, embedded in polyester resin, and ground until the dentin surface was exposed. The teeth were randomly assigned to four groups: I and II--rotating instrument with a carbide bur; III and IV--an air-abrasion system. Groups I and III were restored with Fuji IX and groups II and IV with Ketac Molar. A 3-mm-diameter bonding site was delimited and treated with 10% polyacrylic acid for 10 s in the Fuji IX subgroups and with 25% polyacrylic acid for 10 s in the Ketac Molar subgroups. After surface treatment, a glassionomer cylinder was prepared for each specimen, using a split bisected Teflon matrix. The finished specimens were submitted to the shear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed using ANOVA and Scheffé statistical tests. The dentin bonding areas were analyzed under a stereoscopic optical magnifier (40X) to assess the type of failure. RESULTS: The mean (SD) shear bond strengths in MPa were: group I--3.49 (+/- 3.77), group II--7.17 (+/- 2.93), group III--7.55 (+/- 2.99), group IV--5.67 (+/- 3.90). Ketac Molar showed higher bond strength values in bur-prepared cavities, while on the air-abraded preparations, Fuji IX showed superior results. CONCLUSION: It can be concluded that the air-abrasion system used for cavity preparations may influence the bonding performance of conventional glass-ionomer cements to dentin.     

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目的对比4种充填材料的边缘微渗漏情况,为其临床应用提供合理指导。方法选择2013年1—6月青岛大学医学院附属医院口腔科因牙周病或阻生齿而拔除的健康新鲜后牙60颗,备洞后随机分为6组,每组10颗,分别使用Fihek Z250复合树脂（A1、A2组）、Ketac N100树脂加强型玻璃离子（B1组）、Ketac MolarEasymix型玻璃离子（B2、B3组）、F2000Compomer玻璃离子复合体（B4组）充填窝洞。其中A2组充填后充填体表面涂布AdperSingleBond2粘接剂,B3组充填后充填体表面涂布凡士林,而其他各组充填后表面不做任何处理。经冷热交替实验后,记录各组染料渗入窝洞壁与充填体之间的深度,并进行统计分析。结果A2组微渗漏最小,B2组微渗漏最大,与其他组（A1、B1、B3、B4）相比差异有统计学意义（P〈0．05）;A1、B1、B3、B4组间两两比较差异均无统计学意义（P〉0．05）。结论复合树脂、树脂加强型玻璃离子、玻璃离子复合体的边缘微渗漏均小于传统型玻璃离子;表面涂布隔湿剂后能增强上述材料的边缘封闭性能。     

The effect of a chlorhexidine containing cavity disinfectant on the clinical performance of high-viscosity glass-ionomer cement following ART: 24-month results

PURPOSE: To evaluate the effect of a chlorhexidine-gluconate-based cavity disinfectant on the clinical performance of high viscosity glass-ionomer cement following the ART approach under field conditions after 24 months. METHODS: 126 school children 6-8 years old who had bilateral matched pairs of carious Class I and II primary molars were included. A split mouth design was used in which Ketac Molar was randomly placed with or without the use of chlorhexidine-gluconate-based cavity disinfectant on contralateral sides by three dentists. The restorations were evaluated after 6, 12 and 24 months by two experienced examiners using USPHS-Ryge criteria. RESULTS: The 24-month mean cumulative survival rates of Ketac Molar without the use of disinfectant were 97.7% and 69.4% while in the disinfectant group, the survival rates were 95.2% and 63.9% in Class I and II restorations, respectively with no significant difference between the groups in both class types. In the non-disinfected group, large Class II cavities had significantly better survival rates than did small Class II cavities (P = 0.023). In the disinfected group, the failure rates in mean cumulative survivals from 6 to 12 months and 12 to 24 months significantly increased with time (P = 0.004 and P = 0.016 respectively).     

10%抗坏血酸钠对外漂白后复合树脂充填体微渗漏的影响

目的观察10%抗坏血酸钠与含表面活化剂(Tween,0.2%)的10%抗坏血酸钠对经10%过氧化脲外漂白后复合树脂充填体微渗漏的影响。方法选取牙体完整健康的人离体前磨牙50颗,随机分为5组,第1组不漂白直接树脂充填,第2组用10%过氧化脲漂白后立即树脂充填,第3组漂白后将牙齿浸泡在人工唾液中3周再进行树脂充填,第4组漂白后先用10%抗坏血酸钠处理窝洞后再充填树脂,第5组漂白后先用含0.2%Tween的10%抗坏血酸钠处理窝洞后再进行树脂充填。然后,将5组样本进行2000个周期的冷热循环,2%亚甲基蓝染色24h,体视显微镜下观察剖面充填体的微渗漏情况。结果第1组微渗漏值最低,第2组微渗漏值最高,第3、4组微渗漏值显著高于第1组但与第2组无显著性差异(P>0.05);第5组渗漏值较第2组及第4组显著下降(P<0.05)。结论 10%过氧化脲外漂白致复合树脂充填体边缘微渗漏明显增加,含0.2%Tween的10%抗坏血酸钠处理窝洞可以有效减少该微渗漏的增加,延迟充填和单纯使用抗坏血酸钠均不能有效减少微渗漏。     

Microleakage in conventional and bonded amalgam restorations: influence of cavity volume

This study verified the relationship between the volume and microleakage of conventional and bonded amalgam restorations. Also, the microleakage influence of intermediate materials, substrates and the direction of sectioning was investigated. Fifty-six bovine incisors were selected. Standard Class V cavities were prepared in buccal and lingual surfaces. For each tooth, two cavity sizes were prepared, corresponding to two cavity volumes: one larger (A) and the other smaller (B). The cervical wall was located in cementum/dentin and the incisal wall in enamel. The teeth were distributed in four groups (n=28) according to the intermediate material employed (glass-ionomer cement, resin cement, adhesive system and copal varnish-control). The materials were applied following manufacturers' directions. After restoration, the teeth were submitted to thermal cycling. They were then immersed in a dye solution and sectioned in two directions inciso-cervical (IC) and mesio-distal (MD) sections to evaluate the microleakage. Data were subjected to non-parametric statistical analysis (Wilcoxon's paired test and Kruskal-Wallis test). No significant difference was found between the two cavity sizes. Leakage in enamel was statistically lower than in the cementum/dentin interface (p < 0.05). In some situations, glass-ionomer or resin cement lined amalgam restorations presented less dye leakage than copal varnish lined restorations (p < 0.05). No significant difference was observed in microleakage between IC or MD sectioning. Within the limitations of this study, it was concluded that cavity size and direction of section were not significant factors for microleakage, while substrate and intermediate materials had a significant effect on the sealing ability in amalgam restorations.     

Reversal of dentin bonding to bleached teeth

Many studies have shown a considerable reduction in enamel bond strength of resin composite restorations when the bonding procedure is carried out immediately after bleaching. These studies claim that a certain waiting period is needed prior to restoration to reach the original bond strength values prior to bleaching. This study determined the effect of anti-oxidant applications on the bond strength values of resin composites to bleached dentin. Ninety human teeth extracted for orthodontic purposes were used in this study. The labial surface of each tooth was ground and flattened until dentin appeared. The polished surfaces were subjected to nine different treatments: 1) bleaching with gel (35% Rembrandt Virtuoso); 2) bleaching with gel + 10% sodium ascorbate (SA); 3) bleaching with gel + 10% butylhydroxyanisole (BHA); 4) bleaching with sol (35% hydrogen peroxide); 5) bleaching with sol + 10% sodium ascorbate; 6) bleaching with sol + 10% BHA; 7) bleaching with gel + immersed in artificial saliva for seven days; 8) bleaching with sol + immersed in artificial saliva for seven days; 9) no treatment. After bonding application, the resin composite in standard dimensions was applied to all specimens. The teeth were stored in distilled water at 37 degrees C for 24 hours and a universal testing machine determined their resistance to shear bond strength. The data was evaluated using ANOVA and Duncan tests. Bond strength in the bleached dentin group significantly decreased compared to the control group. On the other hand, the antioxidant treatment had a reversal effect on the bond strength to dentin. After the bleaching treatment, the 10% sodium ascorbate application was effective in reversing bond strength. In the samples where antioxidant was applied after the bleaching process, bonding strength in dentin tissue was at the same level as those teeth kept in artificial saliva for seven days.     

Effect of antioxidant treatment on bond strength of a luting resin to bleached enamel

PURPOSE: The aim of this study was to comparatively investigate the effect of antioxidant treatment and delayed bonding after bleaching with carbamide peroxide on the shear bond strength (SBS) of a luting resin to enamel. MATERIALS AND METHODS: Forty flat enamel surfaces were prepared from freshly extracted human molars using a low speed diamond saw, then divided into three bleaching groups (n=10/group) and a control group (n=10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent, 10% sodium ascorbate, while Group 3 specimens were immersed in artificial saliva for 1 week after bleaching. Specimens in Group 4 were not bleached, but immersed in artificial saliva for 1 week before bonding. Forty ceramic blocks (Empress 2, Ivoclar) were prepared and luted to teeth using a dual-curing resin cement (Variolink II, Ivoclar). The specimens were thermocycled and the SBS tests were performed using a universal testing machine (crosshead speed: 0.5mm/min). Fracture analysis of the bonded surfaces was done using a scanning electron microscope. Statistical analysis was carried out by Kruskall-Wallis and Mann-Whitney U-tests. RESULTS: While the samples that were immediately bonded after bleaching (Group I) demonstrated significantly lower shear bond strengths and 10% sodium ascorbate group (Group II) demonstrated significantly higher bond strengths than control group samples (p<0.05), no significant differences were found among delayed bonded group and control group (p>0.05). CONCLUSION: Using sodium ascorbate with a concentration of 10% may be reliable for reversing the compromised bond strength.     

Ketac Molar Versus Dyract Class II restorations in primary molars: twelve month clinical results

The aim of the present clinical study was an in vivo evaluation of an improved conventional glass ionomer cement Ketac Molar (ESPE), compared to a polyacid modified composite resin, Dyract (Dentsply/De Trey), used in primary molars. Fifty-three Ketac Molar and fifty-two Dyract restorations were placed in box-only preparations in primary molars. The application time for the chemically cured Ketac Molar, was longer compared to the light-cured Dyract. In comparing the materials, no differences were found, comparing both materials regarding secondary caries, marginal adaptation, wear and fracture toughness. One case of recurrent caries adjacent to a Ketac Molar restoration and two cases in the Dyract group were reported. Two Ketac Molar restorations and one Dyract showed bulk fracture at the time of evaluation. At the twelve-month evaluation, no difference between the investigated materials was registered, which indicates that Ketac Molar can be used as a proximal restoration in the primary dentition. It should be emphasized, however, that one-year data should not be extrapolated to indicate the long-term success of restorations.     

The effect of incremental versus bulk fill techniques on the microleakage of composite resin using a glass-ionomer liner.

Incremental placement of composite resin has been suggested to reduce microleakage, particularly at the gingival margin of class 5 cervical restorations. It has become clinically advantageous to place a glass-ionomer liner over dentin to further minimize microleakage resulting from a bond between the dentin and glass ionomer, and glass ionomer and resin. The objective of this study was to compare the microleakage behavior of three hybrid composite/bonding agent systems using bulk and incremental filling techniques utilizing a glass-ionomer liner. This was accomplished in vitro using freshly extracted bovine incisors and a Ca45 radioisotope and autoradiography. Sixty bovine incisors were divided into six experimental groups of 10 specimens per group. Class 5 preparations were cut at the cementoenamel junction and restored with the appropriate combination of Herculite XR/Bondlite, P50/Scotchbond 2, or Pertac Hybrid/Pertac Bond. All teeth were lined with the glass ionomer Ketac Bond before the final restoration was placed. The samples were finished and stored for 24 hours in distilled water before thermocycling. The samples were tested for microleakage using a Ca45 radioisotope technique and autoradiography. Incisal (enamel) and gingival (dentin) margins were scored separately for microleakage but grouped for statistical analysis. Results were analyzed using the Kruskal-Wallis H test. Pertac Hybrid exhibited more leakage than Herculite XR or P50. The difference between microleakage of bulk and incremental filling techniques was only significant for P50.