Air abrasion: its uses and abuses.

Air abrasion, a pseudo-mechanical, non-rotary method of cutting and removing dental hard tissue, was originally conceived in 1945. After promising early clinical developments, the advent of the air turbine handpiece and burs resulted in the loss of this early technology to mainstream dentistry. However, recent advances in adhesive dentistry have called for changes to concepts in cavity design and preparation, and air abrasion has once again come to the forefront of clinical operative dentistry. This review explains the mode of action of the current units and discusses some of the clinical uses of this technique as well as potential pitfalls.

Effectiveness of metal surface treatments in controlling microleakage of the acrylic resin-metal framework interface.

STATEMENT OF PROBLEM: Microleakage at the junction between the metal alloy and acrylic resin in a removable partial denture may result in discoloration, fluid percolation, and acrylic resin deterioration. The junction between a metal alloy and acrylic resin is an area of clinical concern. Failure of a removable partial denture may be linked to this interface. Enhancing resistance to microleakage at this interface may improve the long-term union between the 2 materials. PURPOSE: This investigation was designed to determine the effects of various metal surface treatment protocols on microleakage and bond strength between the metal alloy and acrylic resin used in the fabrication of a removable partial denture. MATERIAL AND METHODS: Ninety-six nickel-chromium-beryllium alloy specimens were randomly divided into 8 groups. After adaptation of baseplate wax, each specimen was invested. Subsequent to wax removal, each specimen was divided into a control half and an experimental half. Air abrasion, tinplating/oxidation, and silanation were evaluated individually and in all combinations. Heat-polymerized acrylic resin was processed against all specimens before storage in distilled water at 37 degrees C for 72 hours. Each specimen then was thermocycled in distilled water (3000 cycles) before immersion in sodium fluorescein dye for 24 hours. Counting grids that exhibited dye penetration under ultraviolet light exposure allowed assessment of microleakage. RESULTS: Air abrasion resulted in a significant decrease in microleakage when used individually and in all combinations (P<0.05). All experimental combinations that did not involve air abrasion demonstrated no significant reduction in measured microleakage between the experimental and control sides. Tukey's pair-wise comparison of the difference in the mean number of squares exhibiting microleakage between the control and treated sites for each experimental group revealed a significant difference, based on the involvement of air abrasion. Groups involving air abrasion did not differ significantly from each other (P<0.05). In addition, no significant difference was detected between groups not involving air abrasion (P<0.05). CONCLUSION: Air abrasion, alone and in combination with tinplating/oxidation and with silanation, resulted in a significant reduction in microleakage between the metal alloy and acrylic resin.

Microleakage evaluation of restorations prepared with air abrasion.

PURPOSE: The objective of this in-vitro study was to measure and compare microleakage around preventive resin restorations prepared conventionally or with air abrasion, in the presence or absence of acid etching. METHODS: One hundred extracted human non carious molars were assigned to each of four groups. Group A: fissures opened with a high speed handpiece, etched, and restored with composite and sealant. Group B: fissures opened with KCP 1000 and restored with composite and sealant. Group C: fissures opened with KCP 1000, etched, and restored with composite and sealant. No adhesive was used for groups A, B, or C. Group D: fissures opened with KCP 1000, adhesive resin was applied, cured, and restored with composite and sealant. All teeth were thermocycled, stained with silver nitrate, sectioned and viewed with a computer linked measuring microscope. Measurements were recorded in relative percentages and absolute millimeters. RESULTS: One-way ANOVA and two sample independent t-test showed no statistical significance between groups A and C, or between groups B and D. Statistically significant differences were found among groups A and B, groups A and D, groups B and C, and groups C and D (P < 0.0001). CONCLUSION: The use of air abrasion alone does not provide adequate sealability of preventive restorations.

Effect of air abrasion and acid etching on sealant retention: an in vitro study.

PURPOSE: This in-vitro study evaluated shear bond strength and analyzed, via scanning electron microscopy, enamel prepared for pit and fissure sealant placement. Various surface pretreatment methods were conducted prior to short-term (72-hour) and long-term (120-day) analysis. METHOD: Six treatment groups of 14 teeth, having 28 bonding surfaces (buccal and lingual) were treated. Cylinders of Delton pit and fissure sealant were placed on the prepared buccal and lingual surfaces and light-cured for 60 seconds. One-half of each group's specimens were stored in distilled water for 72 hours and the other half were stored in water distilled for 120 days followed by thermocycling. All specimens were subjected to shear bond strength analysis as determined on an Instron testing machine. RESULTS: All acid treated groups were equivalent and greater than air abrasion alone after 72 hours of water storage. Scanning electron microscopy of air-abraded and combination treated enamel surfaces revealed a more detailed retentive pattern in the combination treatment than in either treatment alone. CONCLUSION: Based on in-vitro shear bond strength values, air abrasion with 50 micron alumina is an effective pre-etch treatment for sealant placement and in concert with phosphoric acid treatment significantly enhanced the long-term bond of a sealant to enamel. The clinical relevance of this has not been established.