Ultrasonic Surgical Aspirator to Treat Deep Infrabony Defects: A New Flapless Minimally Invasive Approach

The primary outcome of the present study was to assess the percentage of pocket closure, and the secondary aim was to evaluate the clinical performance in terms of clinical attachment level (CAL) gain, probing pocket depth (PPD) reduction, and gingival recession (REC) after the use of cavitron ultrasonic surgical aspirator (CUSA) in deep infrabony defects. Fourteen deep infrabony defects in 11 patients who were previously treated with active periodontal therapy followed by one year of supportive periodontal therapy (at least three sessions) were additionally treated by the aid of CUSA. Eighty-six percent of the initial defects (12 out of 14) resulted in a PD < 5 mm, showing complete resolution six months after CUSA treatment, without any adverse event and with negligible pain (VAS from 0 to 3). CUSA showed potential as a method to promote pocket healing, reduce PPD, and increase clinical attachment (P < 0.001) in deep infrabony defects. This trial is registered with ClinicalTrials.gov NCT03567161.


Introduction
Deep periodontal pockets, which are associated with infrabony defects, are specific risk factors for periodontal disease progression and tooth loss [1,2]. In the past, the interest of researchers on regeneration focused to develop materials as a type of bone substitute and membrane or biological mediator to improve result in tissue regeneration [3][4][5][6], but recently, interest has been moving to the tissue management to achieve better result introducing the minimally invasive surgical approaches (MIS) [7][8][9][10][11][12][13].
In this context, we have to consider other new studies in which authors define and compare the performance of the minimally invasive nonsurgical technique (MINST) to the minimally invasive surgical approach [25]. MINST has been introduced as a concept that aims at obtaining extensive subgingival debridement with a retention of the preoperative gingival architecture, creating a minimal wound, and gentle handling of the soft and hard tissues to stimulate the formation of a stable blood clot by natural filling of the infrabony defect [25][26][27][28].
Cavitron ultrasonic surgical aspirator (CUSA) is a well-known technology that is used in medicine for different purposes; its most frequent applications are in neurosurgery and liver disease [29][30][31]. CUSA has proven to be effective in biofilm disruption and cell stimulation [32]. e hypothesis is that the employment of CUSA for nonsurgical treatment of infrabony defects, thanks to its abilities to disrupt, fragment, and aspirate granulation tissue, will allow the formation of larger and more stable blood clot. e purpose of this study was to test CUSA in nonsurgical treatment of infrabony defects to promote pocket closure.

Materials and Methods
is was a Phase 2 noncontrolled clinical trial performed on patients with infrabony defects to test whether the employment of CUSA for treating periodontal patients.
(1) provides benefits in terms of a PD reduction and CAL gain; (2) is comfortable for both the patient and the operator; (3) is free from adverse events.
All subjects included in the study were consecutive periodontal patients attending a private clinic in Settimo Milanese (Milan, Italy) who were treated by two operators (CG and CD) with a similar experience in nonsurgical produce who performed a specific training for CUSA on a periodontal model. ey were selected on the basis of the following criteria. All patients were informed on the objective of the studies and provided informed consent.
e clinical procedure was always performed in a single session. Before intervention, all cases received local anaesthesia with 1 : 100,000 mepivacaine. All residual pockets ≥5 mm underwent the following: (1) Ultrasonic debridement: to minimize trauma to the soft tissues, we used piezoelectric devices with specific thin and delicate tips (EMS Electro Medical Systems S.A. Chemin de la Vuarpillière, 31 1260, Lyon, Switzerland). (2) Flapless treatment: according to the anatomy of the osseous sites, the sonotrode (Sonocare 300, Söring GmbH, Justus-von-Liebig-Ring 2-25451 Quickborn, Germany) was inserted both intrasulcularly and transgingivally (smallest tip is 0.8 mm): intrasulcularly, in the cases of three wall defects, and transgingivally in cases of one to two wall defects ( Figure 1). e stack of piezoelectric quartzes transforms the electrical energy from the generator into a longitudinal, mechanical vibration of the sonotrode tip (Figures 2-4). When the tip of the sonotrode approaches the tissue, the ultrasonic energy, as a result of the high force of acceleration and cavitation effect, separates cells from the conglomerate of tissues (fragmentation). e fragmented tissue can be aspirated as a semiliquid substance through the sonotrode hole, freeing the defect from the formation of a stable blood clot ( Figure 5). e end point is achieving a condition in which the infrabony defect is free from the granulation tissue as if we had performed a surgical technique with the positive biological consequences that were previously described [17][18][19][20].
After CUSA treatment, the formation of a stable blood clot was stimulated by avoiding any subgingival rinse.
No medications were prescribed advising the patients to use painkillers (NSAIDs) if they experience postoperative pain.
Clinical measurements of the defects and X-ray with bite block were taken at baseline and 3 and 6 months. CD and CG acquired all clinical measurements and radiographs, respectively. e following primary and secondary outcomes were recorded. (i) Comfort and acceptability of the patient during and after the procedure, as measured by interviews, use of painkillers in the following three days, and the visual analogue scale (VAS) after one week; (ii) Comfort and convenience of the operator during the procedure, as measured by interviews at the end of the procedure; (iii) Adverse events.
Clinical data from all patients were entered into an Excel file and checked for entry errors. Continuous variables were expressed as the mean ± standard deviation (SD). Dichotomous data were expressed as a percentage. e comparison between baseline and 6 months after flapless treatment was performed by applying a Wilcoxon signed-rank test. All calculations were performed using Stata version 11.1 (College Station, TX, USA). e defect was used as a statistical unit, and a P value <0.05 was considered statistically significant.

Results
A total of 14 defects in 11 patients were treated and included in this case series. e demographic and clinical baseline characteristics of the 11 subjects are depicted in Table 1. e average age was 56 ± 8 years. Within the 14 treated defects, five were in the mandible and nine in the maxilla. Seven defects affected the lateral and central incisors, and three were adjacent to premolars and four to molars. e mean PPD at baseline was 8.6 ± 1.5 mm, with an average gingival recession of 2.6 ± 2.1 mm, and therefore, the mean CAL was 11.1 ± 3 mm. Table 2 shows the characteristics of the 14 infrabony defects included in this study.
Clinical measurements were taken during the last follow-up visit, six months after CUSA treatment (Table 2). e CUSA procedure achieved pocket closure (PPD < 5 mm) in 86% of the defects (12 out of 14).
At that time point, the mean values of PPD, CAL, and REC were 3.9 ± 1.4 mm, 6.8 ± 1.9 mm, and 2.8 ± 1.6 mm, respectively; the differences with baseline data were statistically significant for PPD and CAL (P < 0.01). e mean PPD reduction was 4.7 ± 2 mm, and mean CAL gain was 4.3 ± 2.2 mm.
X-rays of the selected defects are presented in Figures 6-9. At the end of the procedure, all patients reported negligible discomfort; none took any painkillers in the following week or more. e mean VAS was 1.18 ± 1.11 (the distribution among the study population is shown in Figure 10).
e VAS values ranged between 0 and 3; no adverse event was recorded.

Discussion
Systematic review studies [33,34] revealed that both conventional nonsurgical and surgical therapies were effective methods for making improvements in terms of CAL gain and PD reduction.
However, in recent studies in which MINST was performed in initially deep pockets (PD > 6 mm), there was a greater CAL gain and PD reduction; the change in these clinical parameters was similar, showing a mean CAL gain of 2.56 mm and PD reduction of 3.13 mm in Ribeiro's study and mean CAL gain of 2.78 and a PD reduction of 3.12 mm in Nibali's study [25,26]. ese data confirm the initial hypothesis of the authors; specifically, the use of minimally invasive strategies in nonsurgical therapy could lead to improvement of results compared to the standard nonsurgical approach [25,26]. e present study tested a new flapless approach to further improve the results of debridement. For this reason, the starting point of our research was one year after FMUD, followed by repeated sessions of SPT [35]. e primary idea was to eliminate old and capsulated granulation tissue following the chronic process of  Advances in Medicine periodontitis, allowing the defects to have an appropriate and stable new blood clot resulting from a nonsurgical approach. e ability of the surgical aspirator to reach all areas of the defect with Mini tips, fragmenting and aspirating the tissue, makes this instrument particularly suitable to this purpose [32].
Clinical results of the present study showed potential benefits of CUSA as an alternative to current subgingival instruments. We obtained the resolution of 86% of the periodontal pockets (12 out of 14), that is, a reduction of PD at <5 mm, a clinically relevant. CUSA has potential as a method for reducing PD and gaining clinical attachment in deep infrabony defects, showing mean differences of 4.7 ±1.9 and 4.3 ± 2.1, respectively. is approach may be clearly indicated in patients who are not candidates for traditional surgery.
e tested treatment has been proven to be safe, as no local (i.e., recessions) or systemic adverse event was reported, and no painkillers were necessary for any patient, and pain, as recorded by VAS, was negligible, as demonstrated by the high level of acceptance among patients. In addition, both of the operators who performed the procedures (CG and CD) described it as "simple," "convenient," and "rapid," while indicated, as a major limit of the instrument, the lack of different tips in terms of dimensions and curvatures able to be adapted to the varying tooth anatomy. e limitations of the present study are the relatively small number of patients enrolled, although this was designed as a preliminary study to test the potential benefits and risks of applying CUSA to gingival and periodontal tissues. Another limitation is that, at present, such instrument is not available for the specific dental application, and thus, we had to design and prepare a small number of ad hoc tips. In addition, the cost of the CUSA is too expensive Figure 5: is sequence shows an infrasulcular approach to fragment the tissue. e sonotrode was inserted in a periodontal pocket (a). e tip of the device, placed in contact with the tissues, destroys and emulsifies cells that are irrigated and removed through a built-in suction tube (b). After CUSA treatment, a blood clot fills the target area (c, d).

Conclusion
e flapless approach that was used for treating infrabony defects achieved successful outcomes in terms of pocket closure and clinical parameters.
is approach was identified as a promising method to amplify, and in secondary care, the results that are achievable with nonsurgical therapy, promoting less morbidity than any other surgical technique and providing patient satisfaction. is approach requires future randomized control studies to better explain its potential and different application strategies.

Data Availability
e data used to support the findings of this study are available from the corresponding author upon request.
Ethical Approval e protocol was approved by the Ethical Committee of the University of Milan (Università degli studi di Milano; number 1/17; date 30/01/2017). All of the procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Consent
Informed consent was obtained from all of the individual participants who were included in the study.

Conflicts of Interest
All of the authors declare that they have no conflicts of interest.    Advances in Medicine