Conventional alveoloplasty versus piezoelectricalveoloplasty- A comparative clinical prospective study

Introduction

Alveoloplasty is the process of recontouring and reshaping the irregular alveolar bone to achieve adequate tissue support for the planned prosthesis, with utmost preservation of the bone and soft tissues. Alveolar bone irregularities may be found after tooth extraction or post extraction after the site has completely healed. A rongeur, bone file, handpiece with bur, or a mallet and osteotome are the conventionally used instruments for alveoloplasty based on the degree of bone irregularity¹ . However, if not used accurately, they may cause harm to the surrounding soft tissue and excess removal of the bone, excessive heat production, thereby delaying the healing process and impair bone regeneration. Piezoelectric bone surgery is an advanced tool based on ultrasonic microvibrations which is diligent at cutting the bone and cause minimal or no soft tissue injury. To overcome the limitations of conventional instrumentation in the bone surgery, an Italian Oral surgeon Tomaso Vercellottiintroduced piezo surgery by modifying the ultrasound technology, in 1988. The piezo unit uses a frequency of 25— 29kHz, which allows it to cut the bone on the basis of piezo electric effect, as described by Jean and Marie Curie in 1880. Piezoelectric device is used in clinical practice by oral and maxillofacial surgeon for sinus lift, removal of osseointegrated implants, bone graft harvesting, osteogenic distraction, orthognathic surgery, alveolar ridge expansion, endodontic surgery, periodontal surgery, inferior alveolar nerve decompression, cyst removal, and exposure of impacted canines, dental extraction and impacted tooth removal^2,3. However the use of piezoelectric device for alveoloplasty is reported only in one article Gangwani K Det al⁴ (2018), which compared the use of piezosurgery and conventional techniques for alveoloplasty. Thus, we aim to compare the efficacies of piezosurgery and conventional techniques in alveoloplasty, and derive a conclusion which can decide the further use of piezosurgery for alveoloplasty.

Materials and methods

A clinical prospective study was carried out in 18 patients (10 female and 8 male) of either gender after obtaining ethical clearance from the Institutional review board and ethics committee. The age group of the study ranged from 20-70 years who reported to the Department of Oral and Maxillofacial Surgery, K.V.G. Dental College and Hospital, Sullia, who had been diagnosed as completely or partially edentulous were included in the study as per the inclusion and exclusion criteria, after obtaining written informed consent. The study was conducted from December 2018- December 2019. Inclusion criteria was as follows. 1)Patients with good general health of either gender between the age group of (20-70 years) diagnosed as completely or partially edentulous either maxillary arch or mandibular arch or both arches bilaterally. 2) For bone recontouring and smoothening after tooth extraction process. 3) For bone recontouring and smoothening of alveolar bone priorto fixed or removable prosthetic construction. 4) For removal of sharp bony spicules, undercuts. Exclusion Criteria was as follows: 1) when performed solely for cosmetic/aesthetic reasons. 2) Patients requiring alveoloplasty in single quadrant . 3) When there is diminished volume or atypical architecture of bone. 4) Immunocompromised patients. 5) Patients with history of head and neck radiation

The study designed was split mouth. The procedure was carried out either in maxilla or mandible by dividing into quadrants. Alveoloplasty was performed using conventional methods (rounger/ bur/ bone file) in one quadrant (Group A) and using piezoelectric surgery unit(refer fig.1) in opposite quadrant (Group B) after a time interval of two weeks. The procedure was explained to the patient and informed consent was obtained. Under standard aseptic conditions, betadine painting and draping was done. 2% lignocaine with adrenaline(1:80,000) was administered locally. Mucoperiosteal incision was placed and appropriate flap was raised. Small vertical releasing incisions were given when adequate exposure was not possible. The area of bony irregularity was exposed. Recontouring of bony irregularities was accomplished with conventional methods (rounger/bur/ bone file) in Group A(refer fig2a-g) and using piezoelectric surgery unit in Group B(refer fig3a-g), operated with modulated ultrasound to generate micromovements between 60-200 mm/sec. Saline at 40 C was used for irrigation. For all cases of group B, the settings selected were, mode boosted burst c and pump 5 for individual cuts and mode low, pump 3 for bone removal. Diamond-shaped tip was attached to the handpiece of the instrument for careful removal of bone⁵ . After recontouring, flap was approximated by digital pressure and ridge palpated to ensure that all irregularities have been removed. Closure was done using simple interrupted or continuous sutures using 3-0 silk. The parameters assessed were- 1) Intra-op time taken for procedure¬¬ was measured in minutes- from start of administration of LA till the completion of sutures. 2) Surgeon’s ease of operation will be assessed- Easy/Medium/ Difficult. Post-operative assessment- Patient was recalled on 3rd day, 1 week and 1 month postoperatively to assess the parameters as mentioned in objectives. 1) Healing of tissues will be assessed using Healing index by Landry⁶ . 2) Post-operative complications such as pain, swelling, wound dehisience, wound necrosis, infection was assessed

All the cases were operated by the same surgeon and all the required parameters were assessed and recorded by a single investigator.

Results

The study was carried out in 18 patients (10 female and 8 male patients) with mean age of 53 years. 12 patients were completely edentulous and 6 patients were partially edentulous. 2 patients required alveoloplasty in all 4 quadrants; so they were counted as two separate sample. A total of 40 alveoloplasties (20 in each group) were performed in 18 patients. The data obtained was analysed statistically using chi square test and unpaired t test. The mean intra-op time in group A was 33.2±5.80 min whereas in group B it was 24.70±10.98 min and proven to be statistically significant (p<0.01) (refer graph.1). Ease of procedure was assessed from surgeons and the results showed that it was 65% easy, 35% moderately difficult in group B whereas in group A the procedure was easy in only 20%, moderately difficult in 70% and difficult in 10% and was statistically significant (p<0.05) when compared between the two groups (refer graph.2). Healing was excellent in 5%, very good in 25%, good in 65% and poor in 5% cases in group A. Whereas it was excellent in 10%, very good in 30% and good in 60% of cases in group B. Pain was assessed using visual analog scale[7] (VAS) and was significant on 3rd day, 1st week and 1st month (Refer Table 1). Healing of tissues was better in group B compared to group A, but statistically insignificant. Post-operatively swelling was present in 2 cases in group A, whereas 1 case in group B during 1st post-operative week.

Discussion

Extraction of teeth is performed by clinicians frequently for various reasons such as root fracture, periapical pathology, extensive decay, periodontal disease or trauma. Even when removal of the tooth is exercised in the most atraumatic way, vertical and horizontal resorption is an inevitable natural consequence. Bony spicules and undercuts are formed on the ridges following extraction which causes pain and hinders in the rehabilitation of oral cavity. Various pre-prosthetic surgeries are performed to correct these defects such as ridge correction, ridge extension and ridge augmentation.

Alveoloplasty is a ridge correction procedure commonly performed to reduce/ removal of the labiobuccal alveolar bone along with some interdental and interradicular bone and is carried out at the time of extraction of teeth and after extraction of teeth⁸ .

The use of rounger and bone file for alveoloplasty has been practised since over a century⁹ . This makes it a well versed technique and easy in handling. But the inadequate/excessive cutting of bone, poor recontouring, adjacent soft tissue injury and prolonged intra operative time has been few of their disadvantages. The conventional rotary cutting instruments are also used for alveoloplasty. They are faster, aid in adequate bone removal thereby reducing the potential time bound complications. But these rotary instruments are implicitly harmful during bone drilling, as the greater necessity of applying torsional and rotational power to remove the dense bone, generation of extreme high temperature during the process may lead to marginal osteonecrosis and impair the bone healing¹⁰. Moreover, the macrovibrations generated by the bur, cause excessive noise and can create anxiety in the patient.

Pavlíková G et.al3 stated thatthe newly introduced technique of piezosurgery, minimises most of these complications. With the microvibrations and cavitation effect by the circulating coolant, the blood is continuously washed away, giving ideal visibility in the operative field, making the procedure precise, clean and smooth with less iatrogenic injury³ . The ultrasonic vibrations cause minimal or no soft tissue injury thereby leading to an uneventful healing of soft tissues. Studies have shown that piezosurgery spares a significant amount of surviving osteoblasts and osteocytes, which improves the potency and rapidity of bone healing¹¹. Although piezosurgery has advantages over conventional rotary instruments, longer intraoperative time is one of its disadvantages, as a result of slow bone cutting rate, and lesser experience among the surgeons. The device is not cost effective, and there are high possibilities of cutting the surgical inserts if not used precisely. However, with improvised technique and adequate experience, the shortcomings can be overcome over a period of time¹².

There exists a single study by Gangwani K Det al4 (2018) which compared piezosurgery versus conventional method alveoloplasty. There were no studies available in literature at the time of our study designing and ethical presentation, we had taken up this study to compare the efficacies of piezoelectric surgery in alveoloplasty with the conventional alveoloplasty.

The mean operating time was recorded in minutes from the start of administration of LA till the completion of sutures. The mean operating time was less in group B(24.70±10.98) compared to group A (33.2±5.80) and proven to be statistically significant (p<0.01). Similar results were obtained by Gangwani K Det al⁴ where the mean operating time was lower in the alveoloplasty performed using piezosurgery technique compared to the conventional method. The instrumentation required is less and there is no need for manual irrigation as there is built-in irrigation system in piezoelectric unit which provides a clear field throughout the procedure and helps to reduce the intraoperative time.

Ease of procedure was assessed from surgeons and the results showed that it was 65% easy, 35% moderately difficult in group B whereas in group A the procedure was easy in only 20%, moderately difficult in 70% and difficult in 10% and was statistically significant (p<0.05) when compared between the two groups. The rounger and file need manual pressure for bone cutting, and bur being harmful to soft tissue needs precision and care. The ultrasound vibrations created by piezoelectric device cut the bone faster compared to mechanical devices and do not injure the adjacent soft tissue, thereby giving the surgeon ease and a stress-free mind and ease in operating. The present study was first to compare the ease of performing alveoloplasty using conventional methods versus piezoelectric device.

Patients were followed up on 3rd day, 1 week and 1 month post-operatively to assess healing of tissues, pain and any post-operative complications such as swelling, wound dehisience, wound necrosis, infection was assessed. Healing of tissues were assessed using Healing index by Landry⁵ and recorded. Healing was excellent in 5%, very good in 25%, good in 65% and poor in 5% cases in group A whereas it was excellent in 10%, very good in 30% and good in 60% of cases in group B. Healing of tissues was better in quadrants operated by piezosurgery device compared to those operated using conventional methods and was clinically significant but statistically insignificant. The significant amount of surviving osteoblasts and osteocytes, improves the potency and rapidity of bone healing and the spared soft tissue heal the incisions faster¹¹. Similar results were observed by Gangwani K Det al⁴ where their piezosurgery subgroup showed better and faster healing compared to that in the conventional subgroup and statistically significant contradict to the results obtained in our study.

Pain was assessed using visual analog scale (7) (VAS) and was significant on 3rd day, 1st week and 1st month. VAS score was 6.05±1.19, 4.40±1.50, 1.95±1.27 in group A, whereas it was reduced in group B, 4.95±1.53, 2.85±1.03 and 1±0.97 at 3rd day, 1st week and 1st month respectively and proven to be statistically significant at all the three intervals (p<0.05).The mean VAS score was significantly lower in piezo subgroup (0.94) compared to the conventional subgroup (2.74) in a study conducted by Gangwani KDet.al⁴ . Since there was uneventful healing in almost all the cases of piezo subgroup, the VAS score remained low. Also, we found that the patients tolerated piezo better and had a lower anxiety level.

However, the sample size used was comparatively small and the follow up period was 1 month. The objective pain assessment was not done and hence we had to depend only on the patient’s pain perspective. The method compared conventional with piezosurgery, where conventional includes use of bur as well as bone rounger and file, which are in themselves comparable.

Conclusion

Alveoloplasty isa frequently performed procedure in dental office by oral and maxillofacial surgeon. Conventional methods may causemore of trauma to the tissues leading to prolonged postoperative pain and delayed wound healing. On the contrary,piezoelectric device is less traumatic to the tissues, provides ease of operation to the surgeon and is more comfortable both for surgeon and patient. Owing to its advantages in implant dentistry and other fields of surgery, piezosurgery unit is available in most of the maxillofacial surgical setups and is mandatory in Dental Colleges as per DCI. However, it’s a novel technique and surgeons must be encouraged for its use in alveoloplasty over conventional methods.