Investigations into the use of an ultrasonic chisel to cut bone. Part 2: Cutting ability

A longitudinal-torsional mode ultrasonic needle for deep penetration into bone

This work presents a longitudinal-torsional (L-T) composite mode ultrasonic needle device for deep bone penetration. The L-T needle is a geometrically modified version of an L-mode needle whose efficacy as a prototype ultrasonic bone biopsy device has been previously demonstrated by the authors. Finite element analysis (FEA) aided in the design of the L-T needle, with the aim of maximising the achievable torsional displacement while matching the longitudinal displacement achieved by the L-mode needle. Experimental modal analysis (EMA) of the fabricated ultrasonic device was used to identify the modal parameters and validate the FEA model. Harmonic analysis then provided an insight into how the inherent nonlinearities of the high-power transducer are affected by incorporating the geometrical features that degenerate the L mode into an L-T mode. High power characterisation shows that the longitudinal displacement amplitude of the L-T mode needle is larger than that of the L-mode needle. Comparative penetration tests in fresh Wistar rat skull were evaluated by investigating cell death and cell survival. The region of statistically significant cell death was small for both devices, with the combined axial and shear motion of the L-T device causing increased osteocyte necrosis within this region. Nevertheless, the results suggest a promising environment for post-operative healing. It is shown how this technology offers a potential technique for a surgical approach to the petrous apex, an application that requires a deep penetration into bone.

Piezoelectric versus conventional techniques for orthognathic surgery: Systematic review and meta-analysis

PURPOSE

A systematic review and meta-analysis of the advantages and disadvantages of the piezo surgery comparing with conventional osteotomy in orthognathic surgery.

METHODS

We conducted this systemic review in accordance with the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement. We searched for relevant studies in the PubMed/MEDLINE, Embase databases, Lilacs, Scopus and Science Direct to identify prospective and retrospective studies, compare patient outcomes (intraoperative blood loss, operative time, neurosensory disturbance) after performing orthognathic surgery by conventional saw or piezo-electric device. According to pool individual results we used the mean difference (MD) with the 95% confidence interval (95% CI).

RESULTS

Among three studies that used conventional saw and three studies used piezo-electric device and nine studies used both techniques, the operative time required to perform orthognathic standard procedures was longer using piezo-electric device compared to conventional saw. The results showed that during using the conventional saw to perform orthognathic surgery the amount of the blood loss was higher than the amount while using piezo-electric device (MD -140.4 mL; P = 0.29). based on the studies that evaluated neurosensory disturbance, after 3 months and 6 months respectively, neurosensory disturbance was seen in 23.8% and 23.4% of patient who underwent conventional osteotomy versus 4.3% and 2.4% of the patients who underwent surgery in which piezo surgery was used. Our meta-analysis showed difference in neurosensory disturbance between piezo-surgery and conventional surgery at 3 months (MD -19.5; P = 0.11) and 6 months (MD -21; P = 0.5) postoperatively.

CONCLUSION

Piezo-electric device enabled lower blood loss and higher nerve integrity rates in outcomes according to the complications that associated with orthognathic surgery.

Does Piezosurgery Influence the Severity of Neurosensory Disturbance Following Bilateral Sagittal Split Osteotomy?

The present paper aims to evaluate the long-term incidence and severity of the neurosensory disturbance (NSD) of the inferior alveolar nerve following bilateral sagittal split osteotomy (BSSO) of the mandibular ramus performed with piezosurgery. A retrospective study on patients referred to the Maxillofacial Surgery and Dentistry Clinic of the University of Verona for orthognathic surgery between March 2013 and October 2015 was performed. Inclusion criteria were having undergone BSSO with piezosurgery and follow-up lasting at least 24 months. Exclusion criteria were history of surgical infection, osteosynthesis failure or re-do surgery. The extent of mandibular repositioning movements was retrieved and patients underwent 4 clinical neurosensory tests. Descriptive statistical analysis was performed. 52 patients met the inclusion criteria. Average follow-up was 40 months (range 24-75). 83% of the nerves examined have no or slightly altered sensitivity. Seventy-one percent of patients perceive a moderate to none discomfort and none describes the discomfort as serious (Visual Analogue Scale [VAS] >7). The extent of mandibular repositioning did not have significant influence on the development and severity of the NSD. Resulting data led the Authors to infer that using piezosurgery in BSSO, the severity of the NSD of inferior alveolar nerve is reduced, but the incidence of permanent nerve lesions remains unchanged, compared to historical controls.

Osteotomy speed, heat development, and bone structure influence by various piezoelectric systems-an in vitro study

OBJECTIVES

The aim of this in vitro study was to evaluate osteotomy speed, heat development, and bone structure influence from osteotomies performed by various piezoelectric devices and insert tips. These devices and tips were compared among each other with regard to conventional rotatory and oscillating systems with special focus on the insert tip design and thickness.

MATERIAL AND METHODS

The osteotomies were conducted on porcine ribs utilizing 12 different insert tips (straight and angulated) and three conventional systems. After time and temperature measurements, histological analysis was carried out. Light microscopy was used to evaluate the roughness of the osteotomic surface and to search for indications of thermal bone necrosis. A special software analyzing tool was employed to determine cutting width (mm) and debris (%).

RESULTS

All piezoelectric tips created smooth cuts. Cutting widths in general were wider than the actual insert tip size with a tendency for narrow straight insert tips producing relatively wide osteotomies, whereas narrow angulated inserts produced relatively small osteotomies. None of the samples demonstrated distinct indication of necrosis. Overall, there was only a small amount of debris in all osteotomy gaps. Conventional rotatory saws were faster and created less heat compared to all tested piezoelectric systems. Straight tips proved faster osteotomy speed than angulated tips. Thin insert tips indicated to have a positive correlation to osteotomy time and performed faster than conventional microsaw. The average temperature rise was lower when using conventional systems, but critical exceeding temperatures were only observed in short-time exceptional cases. In general, temperature rise was less when using angulated inserts.

CONCLUSION

All tested tips are appropriate for bone surgery. Only small differences were found among the piezoelectric insert tips. Although conventional rotatory systems in general performed faster osteotomies, special designed and thin piezoelectric insert tips seem to have a positive influence on osteotomy speed. Ultimately, none of the tested devices or inserts combined all best features of speed, heat development, bone structure influence, and safety.

CLINICAL RELEVANCE

Narrow and straight piezoelectric insert tips demonstrated reduced osteotomy times. Nevertheless, a combination of conventional and piezoelectric systems in clinical practice might be the best way to work time-efficient, patient-oriented, and safe. The choice of instrument should be based on clinical experience of the user and should be evaluated individually depending on the case.

Evaluation of the lingual fracture patterns after bilateral sagittal split osteotomy according to Hunsuck/Epker modified by an additional inferior border osteotomy using a burr or ultrasonic device

This study was conducted to compare fracture patterns and operation times after sagittal split osteotomy (SSO) by Hunsuck/Epker approach, performed using a burr or ultrasonic device, with and without osteotomy modification. A total of 80 SSOs were performed in fresh human cadavers using a burr or ultrasonic device to investigate the influence of surgical instruments as well as an additional bone cut on the inferior border of the mandible in terms of lingual fracture patterns. The times required for osteotomy and sagittal split were measured, and postoperative cone beam computed tomography images of all splits were analyzed. Without an additional inferior osteotomy, preferred splits according to Hunsuck/Epker were achieved in 35% of cases (7/20) with the burr and 45% (9/20) with the ultrasonic instrument. The inferior modification resulted in a greater number of unwanted fracture patterns in both groups. There was no relationship between the split technique and the fracture pattern (P=0.7854). Statistically significant differences in osteotomy time were observed between burr osteotomy and modified burr osteotomy (P=0.006), as well as modified ultrasonic osteotomy (P<0.001), but not between burr and ultrasonic surgery both without the inferior cut (P=0.36). The bone cut on the inferior border did not improve split control, but rather increased the risk of unwanted fractures and extended the operation time.

Comparison of the Effects of Ultrasonic and Conventional Surgery on the Neurosensory Disturbance After Bilateral Sagittal Split Osteotomy

PURPOSE

According to the literature, ultrasonic surgery reduces the incidence of neurosensory disturbance (NSD) of the inferior alveolar nerve (IFAN) after bilateral sagittal split osteotomy (BSSO). The purpose of this study was to evaluate the effects of ultrasonic surgery and the anatomic position of the IFAN canal on NSD after BSSO.

PATIENTS AND METHODS

This retrospective cohort study included skeletal mandibular prognathism cases operated on with an ultrasonic bone scalpel or a reciprocating saw. The primary predictor variable was osteotomy technique (ultrasonic or conventional surgery). The primary outcome variable was NSD. Other variables included age, gender, operator, degree of setback, surgical duration, blood loss, and IFAN position. Comparisons of 2 variables were performed by use of the Student t test or Fisher exact test. A regression model was used to examine the relationship between the presence or absence of NSD and other variables. The level of significance was set at P < .05 for all statistical tests.

RESULTS

The ultrasonic group was composed of 35 patients, whereas the conventional group was composed of 32. Three months after surgery, NSD was observed on 16 of 70 sides (22.9%) in the ultrasonic group and 28 of 64 sides (43.8%) in the conventional group; this difference was significant. Furthermore, recovery from NSD at 3 months after BSSO was significantly more common in the ultrasonic group than in the conventional group. In the ultrasonic group, even when the distance from the buccal aspect of the IFAN canal to the outer buccal cortical margin was shorter, NSD of the IFAN was less frequent.

CONCLUSIONS

Ultrasonic surgery may be an effective technique to reduce the incidence of NSD after BSSO, and it contributed to recovery from NSD. The use of an ultrasonic device for BSSO is recommended when the distance from the buccal aspect of the IFAN canal to the outer buccal cortical margin is shorter on computed tomography.

Comparison between piezoelectric surgery and conventional saw in sagittal split osteotomies: a systematic review

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.

Ultrasonic Needles for Bone Biopsy

Bone biopsy is an invasive clinical procedure, where a bone sample is recovered for analysis during the diagnosis of a medical condition. When the architecture of the bone tissue is required to be preserved, a core-needle biopsy is taken. Although this procedure is performed while the patient is under local anaesthesia, the patient can still experience significant discomfort. Additionally, large haematoma can be induced in the soft tissue surrounding the biopsy site due to the large axial and rotational forces, which are applied through the needle to penetrate bone. It is well documented that power ultrasonic surgical devices offer the advantages of low cutting force, high accuracy, and preservation of soft tissues. This paper reports a study of the design, analysis, and test of two novel power ultrasonic needles for bone biopsy that operate using different configurations to penetrate bone. The first utilizes micrometric vibrations generated at the distil tip of a full-wavelength resonant ultrasonic device, while the second utilizes an ultrasonic-sonic approach, where vibrational energy generated by a resonant ultrasonic horn is transferred to a needle via the chaotic motion of a free-mass. It is shown that the dynamic behavior of the devices identified through experimental techniques closely match the behavior calculated through numerical and finite-element analysis methods, demonstrating that they are effective design tools for these devices. Both devices were able to recover trabecular bone from the metaphysis of an ovine femur, and the biopsy samples were found to be comparable to a sample extracted using a conventional biopsy needle. Furthermore, the resonant needle device was also able to extract a cortical bone sample from the central diaphysis, which is the strongest part of the bone, and the biopsy was found to be superior to the sample recovered by a conventional bone biopsy needle.

Management of Giant Calcified Thoracic Disks and Description of the Trench Vertebrectomy Technique

STUDY DESIGN

Case series and review of the literature.

OBJECTIVE

To review the management of giant calcified disks in our large cohort and compare with the existing literature. We discuss our surgical technique.

METHODS

Twenty-nine cases of herniated thoracic disk between 2000 and 2013 were reviewed. Eighteen patients were identified as having giant calcified thoracic disks, defined as diffusely calcified disks occupying at least 40% of the spinal canal. Demographic data was collected in addition to presentation, imaging findings, operative details, and outcomes using the modified Japanese Orthopaedic Association (mJOA) scale.

RESULTS

Giant calcified thoracic disks (GCTDs) are unique clinical entities that require special neurosurgical consideration owing to significant (≥40%) involvement of the spinal canal and compression of the spinal cord, often leading to myelopathy. The median age at diagnosis was 51.2 years (range 37 to 70) with the mean duration of presenting symptoms being 9.9 months (range 2 weeks to 3 years). Seventeen (94.4%) patients presented with at least one sign of myelopathy (hyperreflexia, hypertonia, bladder or bowel dysfunction) with the remaining 1 (5.6%) patient presenting with symptoms in keeping with radiculopathy. Thoracotomy was performed on 17 (94.4%) patients, and 1 (5.6%) patient had a costotransverse approach. Mean follow-up was 19.8 months (range 7 months to 2 years). mJOA score improved in 15 (83.3%) patients. mJOA scores in the other patients remained stable.

CONCLUSIONS

GCTDs are difficult neurosurgical challenges owing to their size, degree of spinal cord compression, and consistency. We recommend a trench vertebrectomy via a thoracotomy in their surgical management. This procedure safely allows the identification of normal dura on either side of the compressed segment prior to performing a diskectomy. Excellent fusion rates were achieved with insertion of rib head autograft in the trench.

A novel technique for micro-hole forming on skull with the assistance of ultrasonic vibration

Micro-hole opening on skull is technically challenging and is hard to realize by micro-drilling. Low-stiffness of the drill bit is a serious drawback in micro-drilling. To deal with this problem, a novel ultrasonic vibration assisted micro-hole forming technique has been developed. Tip geometry and vibration amplitude are two key factors affecting the performance of this hole forming technique. To investigate their effects, experiment was carried out with 300μm diameter tools of three different tip geometries at three different vibration amplitudes. Hole forming performance was evaluated by the required thrust force, dimensional accuracy, exit burr and micro-structure of bone tissue around the generated hole. Based on the findings from current study, the 60° conically tipped tool helps generate a micro-hole of better quality at a smaller thrust force, and it is more suitable for hole forming than the 120° conically tipped tool and the blunt tipped tool. As for the vibration amplitude, when a larger amplitude is used, a micro-hole of better quality and higher dimensional accuracy can be formed at a smaller thrust force. Findings from this study would lay a technical foundation for accurately generating a high-quality micro-hole on skull, which enables minimally invasive insertion of a microelectrode into brain for neural activity measuring.

Machining of bone: Analysis of cutting force and surface roughness by turning process

There are millions of orthopedic surgeries and dental implantation procedures performed every year globally. Most of them involve machining of bones and cartilage. However, theoretical and analytical study on bone machining is lagging behind its practice and implementation. This study views bone machining as a machining process with bovine bone as the workpiece material. Turning process which makes the basis of the actually used drilling process was experimented. The focus is on evaluating the effects of three machining parameters, that is, cutting speed, feed, and depth of cut, to machining responses, that is, cutting forces and surface roughness resulted by the turning process. Response surface methodology was used to quantify the relation between the machining parameters and the machining responses. The turning process was done at various cutting speeds (29-156 m/min), depths of cut (0.03 -0.37 mm), and feeds (0.023-0.11 mm/rev). Empirical models of the resulted cutting force and surface roughness as the functions of cutting speed, depth of cut, and feed were developed. Observation using the developed empirical models found that within the range of machining parameters evaluated, the most influential machining parameter to the cutting force is depth of cut, followed by feed and cutting speed. The lowest cutting force was obtained at the lowest cutting speed, lowest depth of cut, and highest feed setting. For surface roughness, feed is the most significant machining condition, followed by cutting speed, and with depth of cut showed no effect. The finest surface finish was obtained at the lowest cutting speed and feed setting.

Piezoelectric Bone Surgery: A Review of the Literature and Potential Applications in Veterinary Oromaxillofacial Surgery

Piezoelectric bone surgery is a recent and innovative technology, permitting a selective cut of mineralized tissue while sparing soft tissue. Similar to a dental scaler, a high frequency vibration, in the range of 25-35 kHz, is transmitted to a metallic tip. However, the power of the piezosurgical instrument is three to six times higher than that of a dental scaler. The major advantages of this technology include high precision, a design that increases ease of curvilinear osteotomy, less trauma to soft tissue, preservation of neurological and vascular structures, reduced hemorrhage, minimal thermal damage to the bone, as well as overall improvement of healing. The handpiece of the instrument is equipped with a sterile irrigation system and light-emitting diode (LED) light, which improves visibility and overall safety. Piezoelectric surgery is particularly useful when performing delicate bone procedures such as periodontal or endodontic surgery. It is also indicated when performing more invasive bone surgery such as maxillectomy, mandibulectomy, and condylectomy, where preservation of neurovascular structures is important. Piezoelectric instruments are different from rotary instrumentation or oscillating saws, they require light pressure with constant motion of the tip. Training is required to master the technique.

Three-dimensional computed tomographic evaluation of bilateral sagittal split osteotomy lingual fracture line and le fort I pterygomaxillary separation in orthognathic surgery using cadaver heads: ultrasonic osteotome versus conventional saw

PURPOSE

The purpose of this study was to observe the quality of the fracture line on the lingual side of the mandible after sagittal split osteotomy and the quality of pterygomaxillary separation after Le Fort I osteotomy using the BoneScalpel ultrasonic osteotome.

MATERIALS AND METHODS

Bimaxillary procedures, according to the standard protocol, were performed using 10 fresh cadaver heads. The ultrasonic osteotome was used in the study group, and a reciprocating saw was used in the control group. Three-dimensional reconstructions of postoperative computed tomographic scans were obtained. The lingual ramus fracture pattern and the pterygomaxillary separation pattern were observed, classified, and compared. Postoperative dissections of the skulls were performed to assess the integrity of the infra-alveolar nerve and the descending palatine artery.

RESULTS

No significant differences were found in the cutting time of bone between the BoneScalpel and the sagittal saw. Of the sagittal split osteotomies in the study group, 90% showed a good pattern (vertical pattern of fracture line extending to the inferior border of the mandible running behind the mandibular canal) compared with 50% of the sagittal split osteotomies in the control group. Ideal separation of the pterygoid plates without fractures was observed in 80% of the Le Fort I osteotomies in the study group compared with 50% of the osteotomies in the control group. High-level fractures occurred in 30% of cases in the control group compared with none in the study group. The integrities of the infra-alveolar nerve and the descending palatine artery were preserved in all cases.

CONCLUSION

Use of the ultrasonic BoneScalpel did not require more time than the conventional method. An improved pattern of lingual fracture lines in mandibular sagittal split osteotomy procedures and the pattern of pterygomaxillary separation in Le Fort I osteotomy procedures were observed.

Patient-based assessment of tooth extraction with ultrasonic dental surgery

BACKGROUND

The aim of this study was to compare the postoperative period and healing of 2 methods used for simple tooth extraction: traditional and ultrasonic bone surgery. The clinical healing of the sockets and psychologic acceptance of the ultrasonic bone surgery were also evaluated.

METHODS

Two hundred patients requiring bilateral maxillary or mandibular extractions were enrolled. The extractions of the 2 teeth were performed in the same surgical session. The extraction on 1 side was performed using traditional surgery (control site), whereas ultrasonic surgery was used on the other side (test site). The patients were clinically screened at 1, 7, 14, and 21 days.

RESULTS

A total of 200 patients (115 women and 85 men), with a mean age of 54.8 years (range, 40-65 y), provided 400 extraction sites. The time required to perform the tooth extractions was longer at the test site than at the control site, although this difference did not reach statistical significance.

CONCLUSIONS

The piezoelectric extraction technique also provided the best surgical healing results, as evidenced by the integrity of the alveolar walls and surrounding soft tissues. In addition, the patients responded positively to ultrasonic surgery and preferred it to traditional surgery for both the surgical and postsurgical phases.

CLINICAL IMPLICATION

Our preliminary study showed that Piezosurgery is an excellent tool for reducing the risk for complications and for improving the clinical healing and postoperative period in particular. The use of ultrasound reduces trauma to the adjacent bone and soft tissues during the tooth extraction.

Analysis of forces in conventional and ultrasonically assisted plane cutting of cortical bone

Bone cutting is a well accepted but technically demanding surgical procedure in orthopaedics. A level of tool penetration force during cutting of bones has been the prime concern to surgeons, since it can produce unnecessary mechanical damage to surrounding tissues. Research in this area has been undertaken for many decades to find ways to minimise the cutting force. Cutting of bone with ultrasonic tools is a relatively new technique replacing conventional procedures in neuro-, dental and orthopaedic surgeries, due to its precision and safety. In this article, the level of forces produced during a chisel-like tool penetration in a fresh cortical bone is studied. The obtained force data are analysed for both conventional cutting and ultrasonically assisted cutting. Through a series of experiments, it was demonstrated that the depth of cut and parameters of ultrasonic oscillations affected the level of cutting force, the former being the main factor in both types of cutting. It was found that the tool penetration force was decreased with an increase in the ultrasonic frequency or amplitude and was not affected by the cutting speed. The rise in bone temperature was measured and was found to be insensitive to the level of cutting speed within the range used in this study.

Piezoelectric vs. conventional implant site preparation: ex vivo implant primary stability

OBJECTIVES

This study aims to determine differences in primary stability between implants placed in cortical bone following Piezoelectric or conventional site preparation, as assessed by resonance frequency analysis (RFA) and reverse torque testing (RTT).

MATERIAL AND METHODS

Four fresh bovine ribs were acquired and surgical guides fabricated with five sites per rib (n = 20), for proper site preparation. Implant sites were prepared via conventional drilling technique as per manufacturer's instruction (Implantium) or via Piezoelectric (Mectron) implant site preparation using the Implant Prep kit. Twenty 10 mm long, 3.6 mm diameter Implantium implants were placed with 35 Ncm torque; 10 implants per preparation method. RFA was assessed via the Osstell Mentor. Five values were taken per implant. All implants where subjected to a reverse torque in increasing increments of 5 until 50 Ncm force was reached.

RESULTS

The five RFA values per site were averaged and plotted by placement technique. A paired t-test statistical analysis was run. The average RFA values showed no statistical significance between the 10 test (RFA = 69.04 ± 5.11) and 10 control (RFA = 70.94 ± 6.41) sites (P > 0.05). All implants in both groups withstood RTT up to 50 Ncm force without movement and thus showed no statistical differences.

CONCLUSION

Results of this ex vivo study imply that the Piezoelectric implant site preparation affords similar primary implant stability in comparison to conventional rotary instrumentation in cortical bone.

Analysis of Forces and Temperatures in Conventional and Ultrasonically-Assisted Cutting of Bone

Bone cutting is a frequently used procedure in orthopaedic and neuro surgeries. Current research on bone cutting is concerned with the efforts to decrease the forces generated during cutting the bone as well as temperature to avoid mechanical and thermal damage (bone necrosis) induced by surgical tools. The paper presents results of finite-element simulations of conventional cutting (CC) and ultrasonically-assisted cutting (UAC) of bone in order to understand thermomechanics of the process. The study was aimed at investigating the levels of tool-penetration force and temperatures induced in the bone when a hard cutting tool penetrates into it in both types of cutting. The models allow the quantitative analysis of forces and temperatures produced during the cutting process. The use of UAC reduces the tool penetration force and temperature in the cutting region

Influence of the power level of an ultra-sonic system on dental cavity preparation

The aim of this study was to evaluate the shape of dental cavities made with the CVDentus system using different ultrasound power levels. One standard cavity was made on the buccal aspect of 15 bovine incisors with a CVDentus cylindrical bur (82142). The sample was divided into three groups: G1-ultrasound with power II; G2-ultrasound with power III; and G3-ultrasound with power IV. A standardizing device was used to obtain standardized preparations and ultrasound was applied during one minute in each dental preparation. The cavities were sectioned in the middle, allowing observation of the cavity's profile with a magnifying glass, and width and depth measurement using the Leica Qwin program. The Kruskal-Wallis (p<0.05) and Dunn statistical analyses demonstrated differences between the dental cavity shapes when powers III and IV were used. However, the cavities that were made with power III presented dimensions similar to those of the bur used for preparation. We concluded that the power recommended by the manufacturer (III) is the most adequate for use with the CVDentus system.

Ultrasonic osteotomy as a new technique in craniomaxillofacial surgery

Ultrasound osteotomy is a new surgical technique used in dentistry to section hard tissues without damaging adjacent soft tissues. It was hypothesized that this could also be useful in craniofacial and orthognathic surgery. An ultrasonic device was employed in the following craniofacial surgical procedures: 144 Le Fort I osteotomies, 140 palatal expansions after Le Fort I osteotomies and 140 bilateral sagittal osteotomies; 2 Le Fort III osteotomies for treatment of Crouzon syndrome in two patients; 12 cases of unicortical calvarial bone grafting; removal of superior orbital roof in 25 cases of craniofaciostenosis; removal of external wall of the orbit in 10 cases of orbital cavity tumour; removal of anterior and posterior walls of the frontal sinuses in four cases of orbital cavity tumour. Integrity of soft tissues and surgical time were evaluated. Functional results were good without any soft-tissue damage being observed, but the overall operative time was increased. Ultrasound osteotomy is a new technical procedure that is advantageous for bone cutting in multiple situations, with minimal to no damage in adjacent soft tissues such as brain, palatal mucosa and the inferior alveolar nerve.

Piezoelectric osteotomy: a new technique for bone surgery-advantages in craniofacial surgery

INTRODUCTION

Ultrasonic bone cutting is a new surgical technique used in dentistry to section hard tissues without damaging adjacent soft tissues. We hypothesized that such a device could also be useful in craniofacial surgery, particularly during the removal of the superior orbital roof during craniofaciostenosis surgery.

MATERIALS AND METHODS

An ultrasonic device was employed in different craniofacial surgical procedures: 1. to remove the superior orbital roof in 30 cases of craniofaciostenosis, 2. to perform a Le Fort III osteotomy for the treatment of Crouzon syndrome in two patients, 3. to cut the parietal and frontal bone in 30 cases of craniofaciostenosis. The integrity of soft tissues and surgical time was evaluated.

RESULTS

Functional results were good without any soft tissue damage appreciated. The overall operative time, however, was increased.

CONCLUSIONS

Piezosurgery is a new technical procedure, which can be advantageous for bone cutting in multiple situations with minimal to no damage in adjacent soft tissues.

Qu’est-ce que la Piezosurgery®? Intérêten chirurgie craniomaxillofaciale. Àpropos de deux ans d'expérience

INTRODUCTION

Piezosurgery is a new surgical technique used in dentistry to section hard tissues without damaging adjacent soft tissues. We hypothesized that such a device could also be useful in craniofacial and orthognathic surgery.

MATERIAL AND METHOD

An ultrasonic device (Mectron) was employed in different craniofacial surgical procedures: a) to perform 144 Le Fort I osteotomies, 140 palatal expansions after Le Fort I osteotomies, and 134 bilateral sagittal osteotomies; b) to perform a Le Fort III osteotomy for treatment of Crouzon syndrome in 2 patients; c) to perform 5 segmental osteotomies and 3 osteotomies of the inferior edge of the mandible for facial asymmetry; d) to perform 12 cases of unicortical calvarial bone grafting; e) to remove the superior orbital roof in 20 cases of craniofaciostenosis and the frontal bone in 5 cases; f) to remove the external wall of the orbit or the anterior and posterior wall of the frontal sinuses in 10 cases of orbital cavity tumors; g) to approach the skull base through the frontal sinuses in 4 cases. Integrity of soft tissues and surgical time were evaluated.

RESULTS

Analysis of the results showed that Piezosurgery: a) allows very precise cutting; b) avoids bone cutting using an osteotome; c) spares soft tissue such as brain, dura-mater, palatal mucosa, and the inferior alveolar nerve; d) increases the time of bone cutting but not the overall operative time because of the absence of soft tissue protection.

DISCUSSION

Piezosurgery is a new technical procedure, which can be advantageous for bone cutting in many situations, sparing adjacent soft tissues such as brain, palatal mucosa, and the inferior alveolar nerve from any damage. The device's lack of power appears to be a minor problem compared with the advantages.

Effects of different tissue loads on high power ultrasonic surgery scalpel

The objective of this study is to investigate the influence of various tissue loads on the working characteristic of the ultrasonic scalpel, including working frequency, input admittance and reflection factor. Ex vivo animal experiments are carried out and relevant discussions of experimental results are provided. Admittance measurement results show that different tissue loads have different effects on a scalpel's working ability. Soft tissue makes the working frequency decrease and bone tissue makes it increase. Radius of admittance circles and reflection factor are also different. Equivalent circuit model is found and with a least-square parameter identification method, input admittance of ultrasonic scalpel with different tissue loads is solved. Results show that admittance circle radius is determined by the value of R1. Changes in L1 and C1 contribute to the shift of working frequency. This study will help decrease the sensitivity of ultrasonic scalpel to loads and greatly increase surgery efficiency.

Inferior Alveolar Nerve Transposition—An In Vitro Comparison Between Piezosurgery and Conventional Bur Use

An in vitro comparison between a new ultrasound-based piezoelectric device and a conventional bur was performed for lateralization or transposition of the inferior alveolar nerve to evaluate the effects on soft and hard tissue. Transposition of the inferior alveolar nerve was performed in the cadaver mandibles of 10 sheep: the left nerve was uncovered with a saline-cooled diamond-coated spherical bur (2000 rpm), and the right nerve was uncovered with the piezoelectric device mounted with a spherical diamond tip. The surface, the zone of bone defect, and the nerve were examined by light microscopy and laser microscopy. Bone treated with the rotary bur showed significantly smoother surfaces and shallower defect zones (50 microm) in comparison with the piezoelectric device (150 microm). Lesions of the epineurium and an increased amount of bone particles were found in the lesions prepared with the piezoelectric device. In vitro preparation with the piezoelectric device was more invasive to the bone than was a conventional diamond bur. Touching the inferior alveolar nerve resulted in roughening of the epineurium without affecting deeper structures. The degree of injury was lower than when using the conventional rotary bur.