Disposable Micro Air Abrasion: A Minimally Invasive Restorative Technique

Minimally invasive restorative dentistry has been described as the management of caries with a biological approach, rather than a traditional (surgical) operative approach;¹ maximal preservation of healthy dental structures;² and the application of a systematic respect for the original tissue³, among others. For teeth needing this treatment, diagnosis of caries by explorer and radiograph are no longer effective.^4,5
This is primarily due to the phenomenon of noncavitated carious lesions preventing tactile and/or visual diagnosis.⁶ The traditional diagnostic method of explorer examination is capable of discovering fissure caries only after enamel decalcification. This reality makes pit and fissure examination by explorer ineffective.⁷ Visual diagnosis occurs only after collapse of the undermined enamel over a cavitated lesion. In addition, radiographs cannot show the presence of these lesions unless they are larger than 2 mm to 3 mm deep into dentin, or one-third the bucco-lingual distance.⁸
Currently, noncavitated carious lesions can be diagnosed using laser diagnostic technology (DIAGNOdent [KaVo]).^9,10 These lesions can then be accessed and the decay removed with a minimally invasive preparation design. One proven method for accessing noncavitated lesions using a minimally invasive technique is micro air abrasion.¹¹
Micro air abrasion removes tooth structure by concentrating a thin stream of aluminum oxide particles driven at high velocity by compressed air. This accesses tooth decay in a gentle, precise, and controlled manner. This is unlike the conventional high-speed handpiece, where burs often generate vibration, odor, noise, and potential enamel fracture. Air abrasion has the ability to “selectively dissect out damaged tooth structure,”¹² owing to its minimally invasive abilities. The majority of adults and children remain comfortable throughout a typical micro air abrasion procedure without requiring anesthetic, allowing multiquadrant restorations in a single visit. It facilitates immediate treatment of incipient lesions to prevent further decay,¹³ even when the decay is undetectable with radiographs. In conjunction with acid-etch, composite resin bond strengths are increased^14,15 and microleakage is decreased. In a study by Yazici, et al it was shown that air abrasion followed by acid-etching resulted in significantly higher sealant retention rates.¹⁶ When restoring conventional glass ionomer cements to dentin, it has been demonstrated that when air abrasion systems are used for cavity preparations, increased shear bond strength occurs by influencing the bonding performance.¹⁷

Figure 1. The PrepMaster, a prefilled disposable air abrasion system.

A new innovation in this technology, Groman’s Prep-Master (Figure 1), is a pre-filled disposable air abrasion system that adapts to standard handpiece connectors for restorative intraoral preparations. Applications include all class preparations, composite removal, enhanced bonding of laminate veneers, and improved retention of indirect restorations. A simple drawback lever activates the system, allowing the unit to be used by dentists new to air abrasion as well as those who are experienced with this modality. Since every Prep-Master is a new unit, each has a new nozzle. This feature always provides a finely focused abrasive stream, creates minimal overspray and a higher speed of air abrasion, and thus increased comfort. The nozzle is also bendable in all directions, thus avoiding the need for multiple nozzle configurations common to traditional air abrasion systems.

CASE REPORTS

The following 3 case reports demonstrate the use of the PrepMaster disposable intraoral air abrasion device in the preparation of noncavitated carious lesions without the need for anesthesia.

Case 1

Figure 2. The lower left second premolar with deep pits and fissures.	Figure 3. The pits and fissures were examined using the DIAGNOdent pen.

During a routine examination, the lower left second premolar (tooth No. 20) appeared to have darkly stained pits and fissures (Figure 2). The mesio-occlusal pit demonstrated a white halo surrounding it and was not accessible using a sharp explorer. These areas were prophylaxed using a confined stream of sodium bicarbonate (EtchMaster [Groman]). Following rinsing and drying, the pits and fissures were examined using the DIAGNOdent pen, a portable laser caries diagnostic device (Figure 3). The areas examined were detected at levels of 29, a reading that demonstrates the presence of caries.

Figure 4. The PrepMaster disposable air abrasion unit was used to create the cavity preparation without the need for local anesthesia.

The pits and fissures were prepared without anesthesia using the PrepMaster disposable air abrasion unit (Figure 4). Using air abrasion in this manner removes the caries in a minimally invasive manner, while mechanically roughening the enamel margins in preparation for bonding. Pit and fissure lesions are best suited for air abrasion. Since the shape of the abrading stream of the PrepMaster differs from a rotary instrument, a “top-down” technique for cavity preparation is indicated. A preparation is developed to its full occlusal dimension before proceeding pulpally, instead of first preparing to the depth of the caries followed by final extensions. This top-down approach limits over-preparation of pulpal floors. The tip of the PrepMaster is kept moving in a brushing motion across the selected tooth surface to achieve uniform depth and to “blow” away decay. The closer the tip is to the surface, the narrower the preparation will be and the faster the tooth structure will be removed. As caries or stain is removed from a portion of the prep, that area is no longer in need of the abrasive stream. If a preparation needs to be wider, then start widening prior to attaining the desired depth by angling the tip toward the walls. Attempting to widen a preparation after attaining the desired depth will also deepen the preparation. During initial technique practice, the preparation should be inspected visually and with an explorer every few seconds, since the depth cannot be accurately determined while cutting. When areas of deeper caries are discovered, the tip movement should be concentrated in those areas.

Figure 5. The completed cavity preparation.	Figure 6. The smear layer was removed and the enamel further conditioned using Cavity Conditioner.
Figure 7. The cavity was restored using Fuji IX Extra, a rapid auto-cure glass ionomer.	Figure 8. Excess Fuji is removed,  and the remaining occlusal layer is sealed using an applicator brush saturated with G-Coat Plus, a nanofilled, light-cured, self-adhesive, unfilled resin protective coating.

Figure 9. The completed restoration.

Following complete caries removal (Figure 5), the smear layer was removed and the enamel and dentin conditioned using a mild polyacrylic acid (Cavity Conditioner [GC America]; Figure 6), then rinsed and dried. The use of this step is critical to the long-term success of the restoration because it enhances the bond between glass ionomer restorative materials and tooth structure. The cavity was restored using GC America’s Fuji IX Extra, a rapid auto-cure glass ionomer (Figure 7), and the material was burnished and sealed using an applicator brush with a nanofilled, light-cured, self-adhesive, unfilled resin protective coating (G-Coat Plus [GC America]; Figures 8 and 9). This technique and modifications thereof have been demonstrated by Milicich¹⁸ as methods for treating carious lesions using early intervention models with micro dental techniques to maximize sound tooth preservation.

Case 2

Figure 10. An upper left first molar with both white spots (decalcification) and dark grooves (decay).	Figure 11. The PrepMaster was used to carefully access the fissures and remove subsurface caries.
Figure 12. The completed preparation.	Figure 13. The tooth was restored using Clearfil Majesty Flow, a high-strength, high-modulus universal flowable composite resin.

An upper left molar (tooth No. 14; Figure 10) demonstrated signs of caries due to  darkly stained fissures surrounded by white decalcifications. The existence of caries was confirmed using the DIAGNOdent pen, with a reading of 21. The PrepMaster was used to carefully open the fissures and remove the subsurface caries (Figure 11). In this case, a self-etching, single-bottle bonding agent (Clearfil S³ Bond [Kuraray America]) was selected. This is especially useful in cases where the clinician may choose to use a seventh-generation bonding agent. A separate acid-etching of uncut enamel was not required since all surrounding enamel was already etched by the air abrasion preparation. Following rinsing and drying (Figure 12), Clearfil S³ Bond was applied to the preparation as per manufacturer’s instructions and light-cured. This single-component bonding agent provides significantly reduced postoperative sensitivity and high bond strength, and is very easy and fast to use. With its single-bottle liquid, Clearfil S³ Bond dramatically simplifies bonding procedures while also providing a long-term durable bond; the improved features are the result of a new and proprietary homogenous combination of hydrophilic and hydrophobic technology. Clearfil Majesty Flow (Kuraray America), a new high-strength, high-modulus, universal flowable composite resin was injected into the cavity preparations, the excess was removed, and it was light-cured (Figure 13). Clearfil Majesty Flow is a light-cure, superfilled, radiopaque restorative composite resin that has excellent consistency and strength, very low shrinkage, extremely high filler loading (81 wt%), and a smooth-flow, bubble-free syringe dispenser. Restorations that include Clear-fil Majesty Flow will not pull away from the margins or surrounding walls. The restorations will retain their size, shape, and durability, almost exactly like natural teeth.

Case 3

Figure 14. A lower right first premolar as seen on initial examination.	Figure 15. While this tooth did not appear to have a carious lesion on gross examination, a DIAGNOdent reading determined that there was a noncavitated carious lesion.
Figure 16. The lesion was accessed without the need for local anesthesia using the PrepMaster disposable air abrasion unit.	Figure 17. Approximately 1 mm of tooth structure was prepared in depth.
Figure 18. The preparation was evaluated for remaining caries using the DIAGNOdent pen.	Figure 19. Remaining caries was removed and the preparation completed in its entirety using the PrepMaster.

Figure 20. The tooth was restored using OptiBond All-In-One Dental Adhesive System, a single-component self-etching dental adhesive, followed by Premise, a universal nanofilled composite resin.

A lower right first premolar (tooth No. 28) is presented, as seen on initial examination (Figure 14). While this tooth did not appear to have a carious lesion on gross examination, a DIAGNOdent reading determined that there was a subsurface enamel lesion (Figure 15). The lesion was accessed without the need for local anesthesia using the PrepMaster disposable air abrasion unit (Figure 16). Following the removal of approximately 1 mm of tooth structure (Figure 17), the preparation was re-examined using the DIAGNOdent pen (Figure 18). Caries was still present and was completely removed using air abrasion (Figure 19). The tooth was rinsed and dried, and Opti-Bond All-In-One Dental Adhesive System (Kerr Dental), a single-component self-etching dental adhesive, was ap-plied to the preparation. This was light-cured and restored using Premise (Kerr Dental), a universal restorative composite resin (Figure 20).

CONCLUSION

The PrepMaster single-use air abrasion system promotes minimally invasive dental care in an economical air abrasion system that has empowered the dental community to take a less invasive, more preventive approach to dentistry. It is now practical to build a microdentistry-centered practice and to provide patients with better care and greater comfort. The reduced need for anesthesia and the ability to treat multiple quadrants directly is often the treatment of choice for children and adults. Today’s patients treated in this manner will never perceive the anxiety that traditional methods caused in past generations and will become excellent referral sources.

References

Dr. Shuman maintains a full-time general, reconstructive, and aesthetic dental practice in Pasadena, Md. Since 1995 Dr. Shuman has lectured and published on advanced, minimally invasive techniques; he has taught these procedures to thousands of dentists and developed many of these methods. He has published more than 65 articles on topics including creating cosmetic smiles, adhesive resin dentistry, and minimally invasive restorative and cosmetic dentistry. He is a Master in the AGD, a Fellow of the Pierre Fauchard Academy, a member of the ADA, and was named one of the Top Clinicians in Continuing Education in 2005, 2006, and 2007 by Dentistry Today. To have Dr. Shuman speak at your next seminar or to order educational materials, call (877) 4-SHUMAN or visit ianshuman.com.