The aim of this study was to compare the timing of tooth extraction with the piezoelectric instrument (RP), compared to the use of conventional rotary instruments (RO). 12 dogs and 12 cats were enrolled. Extraction times were recorded starting from dental sectioning, until complete avulsion, of both maxillary fourth premolars of patients, with the same grade of bone loss, in the same session, using the two surgical extraction techniques. Comparing the two surgical techniques, a statistically significant difference was shown, without distinction of species (p=0.001), analyzing separately the dog population (p=0.002), and the cat population (p=0.001), underlining that the piezosurgery extraction technique was faster than the conventional use of rotary instruments. Considering the known decreased surgical dose, and the intra- and post-operative reduction in complications, when possible, the use of piezosurgery may be preferable to conventional rotary instruments.

Introduction
Dental extractions performed with traditional rotary instruments can lead to intra- and post-operative complications in patients: damage to neuro-vascular structures, thermal and bone necrosis, iatrogenic mandibular fractures, post operative pain, edema , bleeding and delay in the healing process. These complications are mainly linked to the lower intra-operative safety of these instruments, and the need of 2-3kg pressure by the the surgeon’s hand, to obtain the maximum instrumentation effectiveness. For this reason, in recent decades a new surgical technique known as piezosurgery has been refined. Based on the piezoelectric effect, this device move the metallic tips at 25-35kHz frequency, with 0.2-0.6 mm micro oscillations, able to cut only hard mineralized and not soft tissues. Compared to rotatory instruments, it carries multiple advantages: saving bone thanks to a micrometric cut, an easy control of the instrument in small and difficult surgical fields due to the small amount of pressure needed (max 0,5kg), absence of coagulative necrosis on the cut surface, and less bleeding due to micro coagulation effect caused by the cavitation effect. Consequently leading to less post operative pain, edema and a faster healing. The main disadvantages described for piezosurgery procedures compared with traditional rotatory instrument, are the longer surgical time and a longer learning curve for a correct use of the piezotome. However, those studies were performed with old generation of piezoelectric devices. In the recent years new piezoelectric tips have been developed, with special materials like the T-Black stain, that allow a reduced friction effect, with a more effective cut and a decreased tissue heating. Moreover, new set up program were implemented, allowing the tip to move not only in the longitudinal and vertical direction, but in a 3 dimensional torsional mode, reducing extremely heating side effect on tissues. These lasts technological advantages allow the use of piezosurgery devices with the maximum power available in the market (70watts), increasing effectiveness of the instrument, and significantly reducing surgical times compared to the old piezoelectric units. The aim of this study was to compare the timing of tooth extraction with the piezoelectric instrument, compared to the use of conventional rotary instruments.

Materials and methods
Animals included in the study were client-owned dogs and cats, presented for dental pathologies that involved the extraction of both maxillary fourth premolars. In the same session and on the same patient, two surgical extraction techniques were used. One tooth was extracted with rotating instruments (RO) only and the controlateral tooth, with a combination of rotating instrument and piezosurgery device (RP) (Surgiyonic Moto piezoelectric medical device by Esacrom). In order to do not affect the extractions time, in the study were included only patients with the same grade of bone loss between the two maxillary forth premolars. Extraction times were recorded starting from dental sectioning, until complete avulsion of the tooth.

Results
In the study were included 12 dogs (e.i. 5 female and 7 males) and 12 cats (e.i. 4 female and 8 males). Represented breeds for dogs were: crossbreed, Beagle, Bolognese, and Jack Russel terrier. Represented breeds for cats were: domestic shorthaired, exotic shorthaired, and Siberian. Body weight ranged from 6.3 Kg to 29 Kg (median 11.85 Kg) in dogs, and from 2.4 Kg to 6 Kg (median 4.7 Kg) in cats. Age varied from 5 years and 5 months to 13 years and 8 months (median 11 years and 7 months) in dogs, and from 1 years and 7 months to 12 years and 9 months (median 4 years and 1 month) in cats. Comparing the two surgical techniques, it emerged that the mean statistical values, considering the 24 patients in total (without distinction of species), presented a statistically significant difference (P=0.001) with a median time of 263.9’’ (standard deviation 143.6’’) for the RO, and time of 153.8’’ (standard deviation 72.3’’) for the RP. Analyzing the individual species, in dogs the values presented a statistically significant difference equal to P=0.002 with median times of 337’’ (standard deviation 170.2’’) for the RO and 190’’ (standard deviation 87.2’’) for the RP, while in cats they presented a statistically significant difference equal to P=0.001 with median times of 190.8’’ (standard deviation 49.9’’) for the RO and 117.6’’ (standard deviation 21.7’’) for the RP.

Conclusions
This study evidence that extraction times of the maxillary fourth premolars, with the aid of piezosurgery, were shorter than the extraction times with the use of rotary instruments in both, the canine and feline species. In conclusion, the piezoelectric instrument represents an excellent surgical instrument in the field of veterinary exodontics, with even a greater potential than previously reported. Further clinical studies, including larger populations, are warranted to confirm the advantages of piezosurgery shown in this study; underlining a decreased surgical timing, alongside the already known decreased surgical dose, and intra- and post-operative complications reduction. Therefore, when possible, the use of piezosurgery may be preferable to conventional rotary instruments.

 References available upon request.