**5. Discussions**

**Figure 21.** Application of etching gel.

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**Figure 22.** Application of adhesive.

The appearance of adhesive materials and their increasing use has led to more conservative preparation of dental tissues. Alternative techniques to bur preparation have emerged and developed. They have the advantage of being minimally invasive, removing altered dental tissues with minimal sacrifice of sound tissues; they do not produce vibrations, noise, pressure, or heat and are well tolerated by patients, being painless in the majority of situations, thus rarely needing anesthesia. All these advantages are displayed by the air abrasion technique, which is more often used in dental practice. Research made on air abrasion assessed various aspects of its application technique. Special attention was granted to clinical, macroscopical, and microscopical evaluation of retention of various restoration materials applied on teeth prepared by air abrasion. The degree of patient acceptance and dentists' opinions on this method were also investigated.

The most important aspect of air abrasion to be considered is practicing the method on extracted teeth, prior to applying it to patients. Thus, dentists become acquainted with the method, which lacks tactile sense, and also learn to control certain parameters which influence the preparation: working distance from the operatory field, nozzle orifice diameter, air pressure in the device, abrasive particles dimensions, and flow [20]. By mastering these parameters and applying the specific protection measures recommended, efficient and safe dental preparations are obtained, leading to high acceptance by patients [2, 21, 22], as our study revealed as well. Although time spent for air abrasion therapy was found to be 1.5 higher than in case of burs, it tends to shorten as more preparations are performed [23].

Air abrasion was found suitable for diagnosing fissural caries and conditioning occlusal surfaces prior to sealant application. The results after 6 months evaluation demonstrated sealant retention in 83% of treated teeth [24]. Also, sealant retention rate was higher when applied to sound pits and fissures prepared by air abrasion and acid etching than in those prepared only by acid etching, at evaluations made after 6, 12, and 24 months following application [25]. However, another study found no statistical difference in sealant retention degree after tooth preparation by acid etching or air abrasion at 1-, 2-, and 5-year evalua‐ tions [26].

Shear bond strength of various materials applied to enamel after air abrasion was another topic investigated. Thus, Ellis et al. [27] assessed shear bond strength of sealants applied to enamel surfaces prepared by air abrasion, with and without etching with 35% phosphoric acid. Their results demonstrated that shear bond strength was greater when air abrasion was associated with acid etching.

Wright et al. [28] evaluated microleakage produced at tooth-sealant interface in three different situations: pits and fissures prepared by rotary instruments and acid etching; air abrasion preparations; and dental sealants applied after acid etching. The least microleakage appeared in bur preparation, followed by acid etching.

Borsatto et al. [29] assessed enamel shear bond strength in teeth treated by acid etching (15 seconds with 37% phosphoric acid) or by air abrasion or by combining the two methods. Survey findings were that air abrasion could not substitute acid etching, their association being needed for best results.

Abraham et al. [30] made a review of research made on nondrill methods (air abrasion, laser, and chemomechanical method) and their efficacy in treating dental decay. The study conclu‐ sions were that the alternative techniques were not superior to dental burs in removing carious lesions, although having the advantage of preserving more sound dental tissue. The duration of nondrill interventions is increased as compared to bur preparations but patients tolerate them better, especially because of the lack of pain, thus being especially useful in children and anxious patients. Other conclusions referred to the need of exercising nondrill methods on extracted teeth before being applied to patients and to the higher costs of equipment acquisi‐ tion, compared to conventional rotary handpieces.

More studies are needed in order to assess all the aspects that concern the use of nondrill methods.
