Push-Out Bond Strength Evaluation of Glass Fiber Posts With Different Resin Cements and Application Techniques.

The purpose of this study was to evaluate the push-out strength of two different adhesive cements (total etch and self-adhesive) for glass fiber post (GFP) cementation using two different techniques (microbrush and elongation tip) of cement application. In addition, this study evaluated the effect of total-etch conditioning before the use of a self-adhesive cement. Sixty premolar specimens with a single root canal were selected, endodontically treated, and shaped for GFP cementation. The specimens were randomly placed into one of six groups according to the cement and technique used: RelyX ARC (ARC): ARC + microbrush, ARC + elongation tip; RelyX Unicem (RU): RU + microbrush, RU + elongation tip; or RelyX Unicem + 37% phosphoric acid (RUE): RUE + microbrush, RUE + elongation tip. Each specimen root was cut perpendicular to the vertical axis yielding six 1.0-mm-thick sections. Push-out strength test was performed, followed by statistical analysis using three-way analysis of variance and the Games-Howell test (p<0.05). Statistically significant differences between the groups were found (p< 0.05). The cervical third of the roots had the highest mean push-out strength values, while the apical third had the lowest mean values regardless of the technique used. The elongation technique produced higher mean push-out strength values compared to the microbrush technique. The self-etch adhesive cement had the highest mean push-out strength value in all thirds. The addition of a conditioning step before the self-etch adhesive cementation appears to be effective in enhancing push-out strength with GFPs.

Dental student perception and assessment of their clinical knowledge in educating patients about preventive dentistry.

In today's dental school curricula, an increasing amount of time is dedicated to technological advances, and preventive dentistry topics may not be adequately addressed. Freshman (D1) students participated in a new Introduction to Preventive Dentistry course, which consisted of didactic lectures, active learning breakout sessions and case-based studies. The goal of this study was to determine if D1 dental students completing the course had a better knowledge and comfort level with basic preventive dentistry concepts and caries risk assessment than the upcoming graduating senior dental students. Following the completion of the course, D1 students were administered a survey that assessed their comfort level describing preventive dentistry topics to patients. This was immediately followed by an unannounced examination over the same topics. Senior (D4) students, who had not taken a formal course, reported statistically significant higher comfort levels than D1 students. However, the D4s scored significantly lower in all of the examination areas than the D1 students. Higher scores in D1s may have been due to recent exposure to the course material. However, the basic nature of the content-specific questions should be easily answered by novice practitioners educating their patients on oral disease prevention. As the current data shows lower content-specific scores of basic preventive dentistry knowledge amongst graduating D4 students, this may indicate a need for more guidance and education of students during the patient care. This study showed that implementation of a formalised course for D1 students can successfully ameliorate deficiencies in knowledge of preventive dentistry topics.

Reducing microleakage in Class II restorations: an in vitro study.

The aim of this in vitro study was to evaluate four methods of reducing the marginal microleakage of directly placed Class II composite resin restorations. Mesio-occlusal and disto-occlusal preparations with all margins confined to enamel were placed in extracted human molars. The teeth were restored with one of four techniques using multi-incremental placement, stored for 24 hours in 37 degrees C water, thermocycled, and placed in a dye solution. The teeth were sectioned in a mesiodistal direction through the restoration and evaluated for microleakage at the gingival margins. Restorations placed in conjunction with an enamel bonding agent demonstrated severe microleakage. Marginal microleakage was reduced by the use of an extended base of visible light-cured glass-ionomer cement, a BondAband, or a dentinal bonding agent.

Effect of aging on microleakage of restorative systems.

This study evaluated the sealing properties of AP.H/Prisma Universal Bond 3, Z100/Scotchbond MultiPurpose, AP.H/Imperva Bond, Charisma/Denthesive, Bisfil M/All-Bond 2, resin composite/dentin adhesive systems and Fuji II LC light-cured glass ionomer, in Class V preparations following 6 months of storage in a 37 degrees C water bath. The Class V preparations extended just beyond the cemento-enamel junction of extracted human molars. The restored teeth were placed in 37 degrees C water for 24 hours and then thermally stressed for 100 temperature cycles. Half of the specimens were tested for microleakage at this time. The other specimens were returned to water storage and thermally stressed every 30 days during the following 6 months and then assessed for microleakage by dye penetration. AP.H/Imperva Bond, Z100/Scotchbond Multi-Purpose and Fuji II LC were not affected by the storage, while AP.H/Prisma Universal Bond 3, Charisma/Denthesive and Bisfil M/All-Bond 2 revealed some increase in microleakage at the dentin/cememtum margin.

Marginal leakage of visible light-cured glass ionomer restorative materials.

This study examined the sealing of two visible light-cured glass ionomer restorative materials and a conventional glass ionomer. Class V cavity preparations were completed at the cementoenamel junction on the facial and lingual surfaces of extracted human molars. The cavity preparations were restored with either VariGlass VLC, GC Fuji II LC, or GC Fuji II glass ionomer cements. The restored teeth were thermocycled, immersed in fuchsin dye for 24 hours, sectioned, and evaluated with a measuring microscope. No microleakage occurred at the enamel/glass ionomer or dentin/glass ionomer cement interfaces of any samples, but the enamel adjacent to the VariGlass glass ionomer cement restorations exhibited crazing and staining.

Microleakage resistance of glutaraldehyde-containing adhesives.

This study evaluated the microleakage resistance of various glutaraldehyde-containing dental adhesives in Class V preparations. The materials tested were Gluma Bond System (3 Step), Prisma Universal Bond 3, and Syntac. The Class V preparations extended just beyond the cemento-enamel junction of extracted human molars. The restored teeth were stored in tap water for 24 hours and then thermally stressed for 100 cycles. Marginal leakage was assessed by measuring the dye linear penetration. The results indicated that all three dentin bonding agents provided leak-proof seals under certain conditions. The sealing ability of the Gluma Bond System (3 Step) appeared to be significantly affected by the resin composite used in the restoration.

Prerestorative bleaching: effect on microleakage of Class V cavities.

The effect of bleaching extracted teeth on the microleakage of subsequently placed Class V composite resin restorations was evaluated. Ten extracted premolars were stored in water at 37 degrees C to serve as controls. Ten premolars were exposed to a carbamide peroxide gel for three 2-hour periods per day for 9 days. These specimens were stored in water at 37 degrees C except during treatment periods. Class V cavity preparations were then placed at the cementoenamel junction of the facial and lingual surfaces of all teeth. Half of the teeth of each group were restored with Scotchbond 2/Silux Plus and half were restored with Prisma Universal Bond 3/AP.H. After 24 hours of storage in 37 degrees C water, the teeth were thermally stressed for 100 cycles. Microleakage was assessed by dye penetration. The results demonstrated that prerestorative bleaching did not affect the marginal seal of subsequently placed restorations.

Pneumatic versus hand condensation of amalgam: effect on microleakage.

This study compared two techniques of amalgam condensation for effect on early microleakage. Class V preparations were restored with a high-copper amalgam using pneumatic condensation or conventional hand condensation. Significantly less microleakage was observed when pneumatic condensation was used. Further, pneumatic condensation proved equally effective in reducing early microleakage whether or not a dentinal sealant was used as an intermediary.

Post-operative bleaching: effect on microleakage.

The effect of a carbamide peroxide bleaching gel on the microleakage of Class V resin composite restorations with two dentin bonding agents was evaluated using extracted human teeth. Class V cavity preparations were placed at the cementoenamel junction of the facial and lingual surfaces of 20 teeth for a total of 40 preparations. Half of the teeth were restored with Scotchbond 2/Silux Plus and half were restored with Prisma Universal Bond 3/AP.H. Five teeth were randomly selected from each of the two groups and were stored in water at 37 degrees C to serve as controls. The remaining teeth were exposed to a carbamide peroxide gel for three 2-hour periods per day for 9 days. The specimens were stored in distilled water at 37 degrees C except during treatment periods. All teeth were then thermally stressed for 100 cycles. Microleakage was assessed by dye penetration. The results demonstrated that the carbamide peroxide agent adversely affected the marginal seal of both restorative systems.

Microleakage of three dentinal bonding systems: a 6-month evaluation.

This study evaluated the marginal sealing ability of three of the latest generation of dentinal bonding agents following 6 months of storage in a 37 degree C water bath. Class V preparations were placed at the cementoenamel junction of extracted human molars. Herculite XR was used to restore cavities that had been pretreated with Gluma, Tenure, or XR Bond. The restored teeth were thermally stressed every 30 days during the following 6 months, and then microleakage was assessed by dye penetration. Under the experimental conditions, the microleakage associated with XR Bond and Gluma was not statistically significantly different. XR Bond performed statistically significantly better than Tenure (a = 0.01).

Microleakage of three resin placement techniques.

The microleakage associated with three composite resin placement techniques was compared using Class V preparations that extended just beyond the cemento-enamel junction of extracted human molars. The placement techniques were evaluated in conjunction with four adhesive bonding agents. The restored teeth were stored in tap water for 24 hours and then thermally stressed for 100 temperature cycles. Marginal leakage was assessed by measuring the linear penetration of a dye solution. Dye penetration was minimized by using an incremental placement procedure in which the first increment was placed in the coronal portion of the cavity, extended down to the gingivo-axial line angle, and cured. The second increment was used to fill the remainder of the preparation.

Prepolymerization of Gluma 4 sealer: effect on bonding.

This study evaluated the effect on microleakage of placing a composite resin over either cured or uncured Gluma 4 sealer. Class V preparations were placed at the cemento-enamel junction of extracted human molars. Herculite XR was used to restore cavities that had been pretreated with Gluma bonding system with the sealer being either uncured or cured prior to placing the restorative resin. The restored teeth were thermally stressed for 100 temperature cycles and placed in a dye solution for 24 hours. Microleakage was measured under a microscope at x50 magnification. Under the experimental conditions, leakage was significantly reduced when the sealer was pre-polymerized and an incremental composite resin placement technique was utilized.

Effect of substrate age on microleakage of dentine adhesive agents.

The present investigation was performed to determine the effect of substrate age on the microleakage of two new dentine adhesive agents. Class 5 preparations were placed at the cemento-enamel junctions of two groups of extracted human molar teeth which had been stored in water for less than 3 months or for approximately 18 months. Silux Plus was used to restore cavities that had been primed with either Scotchbond 2 or GLUMA. The restored teeth were thermally stressed for 100 temperature cycles and placed in a dye solution for 24 h. Leakage was measured under a microscope at X50 magnification. Under the experimental conditions, there was no significant difference in microleakage which could be attributed to the two different post-extraction tooth storage periods.

Influence of bonding agents and composites on microleakage.

The compatibility of selected composite resins was compared with Scotchbond Dual Cure adhesive. In addition, the influence of the types of composite resins on microleakage was investigated. No significant difference was found in microleakage of preparations restored with Scotchbond Dual Cure adhesive and the five composite resins of other manufacturers from restorations inserted with the manufacturers bonding agent and composite resin. Severe leakage occurred at the gingival dentinal margin in all restorations. However, leakage was greatly reduced when a less viscous microfilled composite resin was used in conjunction with various bonding agents. The findings of this study indicate that the higher viscosity and lower water-sorption values of some composite resins may adversely influence micro-leakage regardless of the bonding agent used.

Effect of etchant time on microleakage.

This study supports the growing evidence that satisfactory marginal sealing can be achieved with reduced enamel etch-times. It is possible to create good marginal sealing in enamel after a fifteen-second etch--especially beneficial in young patients.