A systematic review of the advantages and disadvantages of piezoelectric surgery in comparison with conventional saws for sagittal split osteotomy (SSO) was performed. Relevant studies published in the last 10 years were identified through a search of the PubMed/MEDLINE, Science Direct, and Embase databases and assessed against predetermined eligibility criteria. The initial search resulted in 1736 articles. After applying the inclusion and exclusion criteria, 12 articles remained. A total of 799 patients with an average age of 27.5 years underwent SSO performed using a saw or ultrasonic device. Results showed that it took longer to perform the osteotomies using an ultrasonic device than using a conventional saw. At ≥6 months of follow-up, neurosensory disturbance was seen in 4.7% of patients who underwent piezoelectric surgery versus 61.6% of patients who underwent surgery in which a conventional saw was used. It was found that the use of piezoelectric surgery in SSO leads to the best outcome regarding neurosensory disturbance when compared to conventional saws ( P = 0.04) at ≥6 months of follow-up. Further studies are required for the evaluation of the other clinical parameters assessed.
The sagittal split osteotomy (SSO) is a technique commonly used for the correction of mandibular deformities and malocclusions, mainly because it offers a good contact area for the osteotomized segments . However, there are complications associated with this technique, such as injury to the inferior alveolar nerve (IAN), haemorrhage, temporomandibular dysfunction, periodontal disease, bad split, and recurrence .
Factors related to neurosensory disturbance after SSO include age of the patient, amount of intraoperative mandibular movement, degree of IAN manipulation, and thickness of the marrow space between the IAN canal and the external cortical bone . Most of these risk factors can be minimized during the surgical procedure by experienced surgeons; however, neurosensory disturbance remains a common postoperative morbidity .
Piezoelectric bone surgery is a system of bone cutting based on ultrasonic micro-vibrations that preserves the soft tissue. It is indicated for surgical procedures such as bone graft harvesting, tooth extraction, maxillary sinus lifting, osteogenic distraction, and orthognathic surgery . With regard to SSO, some studies on the use of ultrasonic devices have reported minor postoperative complications such as oedema, bleeding, and IAN lesions . The major limitations of ultrasonic devices are related to the prolonged time needed to perform the bone cuts and the necessity of completing the bone cuts with other instruments .
The aim of this study was to perform a systematic literature review to compare the advantages and drawbacks of SSO completed via piezoelectric surgery with those of SSO completed using electric or pneumatic saws.
This systematic review was conducted in accordance with the PRISMA statement and following models proposed in the literature . The selection of the articles was performed by two authors (LFS and ENRCR) and by a third reviewer (JPB).
The studies were selected for this review according to the following PICO framework: (1) population: patients undergoing orthognathic surgery; (2) intervention: SSO; (3) comparison: SSO using conventional saw vs. piezoelectric surgery; (4) outcome: the main outcomes assessed were bleeding, duration of surgery, bad splits, postoperative oedema, and neurosensory disturbance.
Information sources and search strategy
Articles in the English language reporting the results of relevant studies were sought in the PubMed/MEDLINE, ScienceDirect, and Embase databases.
The search was conducted using three pairs of key words: “Orthognathic surgery” AND “Piezosurgery”; “Orthognathic surgery” AND “Ultrasonic surgical procedures”; “Orthognathic surgery” AND “Osteotomy; sagittal split ramus”.
The following inclusion criteria were applied: articles from clinical trials, prospective and retrospective studies concerning orthognathic surgery where an SSO was performed, published in the English language during the last 10 years.
Studies on animals, case reports, case series, and reviews and systematic reviews of the literature were excluded. Articles that used a similar sample and were reported by the same authors in the same year were also excluded. In these cases, only the article with the more relevant data was included. Articles that did not present data relevant to the aim of this study were excluded.
Data collection process
The articles were selected by two authors (LFS and ENRCR) and a third reviewer (JPB). Inter-examiner (kappa) tests were applied to the evaluation of titles and abstracts, and to the full-text reading for article interpretation, resulting in concordance kappa test values of κ = 0.83, 0.92, and 1, respectively. Agreement was reached during a meeting, and any differences were discussed and resolved by consultation with the third reviewer (JPB). After analysis of the titles, abstracts, and full-text articles, 12 studies were selected based on the inclusion criteria.
The following data were identified in each article and recorded: first author, level of evidence, number of patients, number of SSOs performed, equipment used to perform the osteotomy, volume of blood loss, duration of surgery, level of postoperative oedema, and the presence of IAN lesions as a complication.
For the analysis of neurosensory disturbances, articles that presented at least one of the following evaluation methods were selected: light touch sensation, pin-prick sensation, static two-point discrimination (the Weber test), moving two-point discrimination (the Dellon test), and subjective evaluation. For the articles that presented all of these methods, a global sensitivity score was used, while for those that did not use all of the tests above, the test with the largest number of patients showing sensory disturbances was chosen.
Risk of bias in the individual studies
The studies were analyzed to determine the risk of bias in the results and conclusions. The Jadad scale was used to assess the quality of each study . Each study received a score from 0 to 5; studies with a score of 3 or above were considered adequate.
A comparative analysis between piezoelectric surgery and electric or pneumatic saws used in SSO was performed to evaluate the volume of blood loss, duration of surgery, postoperative oedema, damage to the IAN, and number of bad splits.
Risk of bias across studies
Regarding this review, it is acknowledged that the comparison of outcomes of different studies with different surgeons, different patient selection, and different methods of patient evaluation is difficult. However, this is a challenge for any systematic review.
Fisher’s exact test was applied for the comparative evaluation of neurosensory disturbances observed between osteotomies performed with a saw or via piezoelectric surgery, at 3 months and 6 months post-surgery. A P -value of <0.05 was considered statistically significant. The statistical analysis was performed using SigmaPlot 12.3 (Systat Software Inc., San Jose, CA, USA).