Effects of pulsed electromagnetic fields on swelling and pain after implant surgery: a double-blind, randomized study

Abstract

The aim of this split-mouth, double-blind, randomized study was to determine whether pulsed electromagnetic field therapy (PEMF) can improve swelling and the management of pain after full-arch immediate loading implant surgery. Eleven patients were selected for the study. Each patient received four distal tilted implants in the upper or lower jaw and underwent full-arch immediate loading rehabilitation. After surgery, two PEMF devices were applied to each patient, one on each cheek. In a random manner, one of these PEMF devices was switched on (test side); the other served as a placebo (control side). Forty-eight hours after surgery clinicians estimated postoperative swelling through photographic documentation, comparing the condition before and after surgery, while pain was assessed using a verbal rating scale. The patient’s degree of comfort in relation to the PEMF devices was analyzed by questionnaire using a numerical rating scale. No statistically significant difference was observed between the test and control sides for swelling or pain ( P > 0.05). Most of the patients did not present swelling or pain at 48 h after surgery, regardless of whether the PEMF device was activated or not. Various outcomes were found in the comfort evaluation. Within the limitations of this study, PEMF does not reduce postoperative swelling or pain after implant surgery.

The immediate placement and loading of dental implants in totally edentulous patients has proven to be a reliable and predictable procedure, especially in the mandibular dental arch. This surgical and prosthetic approach has many advantages, for instance the shortened treatment time with quick return to function, the possibility of ideal implant placement in the post-extraction sockets, and the conservation of alveolar bone and soft tissues, with aesthetic improvement.

From the patient’s perspective, this has resulted in increased acceptance of and satisfaction with implant rehabilitation. However the patient may experience postoperative swelling and pain, as happens following most oral surgery procedures. Patients are often concerned about the possibility of feeling intense pain and this is sometimes the reason they postpone or avoid undergoing surgery. Furthermore, patients now expect to resume their normal everyday activities after surgery, in the best possible physical condition.

The use of local anaesthesia, the introduction of minimally invasive atraumatic surgical techniques, and the prescription of ice and analgesic drugs are determining factors in the control of postoperative pain and oedema. Nonetheless discomfort can still be considerable for some patients. Moreover analgesic drugs may present undesirable side effects, further increasing the potential risks to the patient and increasing their morbidity.

There is growing interest in the biological and clinical effects of alternative, drug-free, non-invasive means of oedema and pain control, such as pulsed electromagnetic field therapy (PEMF). Some authors have suggested that PEMF is useful in the treatment of acute pain or chronic painful illnesses like knee osteoarthritis, for the treatment of surgical wounds, and in enhancing the healing of bone injuries. PEMF appears to have beneficial effects in promoting healing in mandibular fractures treated with closed reduction, and in the treatment of femoral head osteonecrosis. Some reports of animal experiments have described PEMF therapy as an ‘adjuvant’ in bone healing around dental implants. The enhancement of osteogenesis by PEMF may be explained through a primary effect on vascular growth, but the precise mechanism has yet to be fully clarified.

On the other hand, there are systematic reviews reporting contradictory results, from which weak or absent statistically significant evidence on the effectiveness of PEMF has emerged, especially related to the relief of knee osteoarthritis pain. Many controlled trials and reviews have stated that the biophysical interactions between low energy waveforms and human tissues are not yet completely understood. Furthermore, the application of PEMF treatment to the management of postoperative pain and oedema in immediate functional implant surgery has not been reported yet.

Therefore, the primary aim of this split-mouth, double-blind, placebo-controlled study was to determine whether PEMF treatment, applied randomly to one side of the face, can improve swelling and pain control after a full-arch immediate loading implant rehabilitation. In addition, the secondary aim was to investigate the psychosocial impact of PEMF therapy on the patient.

Materials and methods

Patient recruitment

Between February 2014 and June 2014 a sample of 11 patients (three men, eight women) with a mean age of 63.4 years (range 51–75 years) was recruited for this study ( Table 1 ). The study protocol, questionnaires, and informed consent were structured in full accordance with the ethical principles stated in the Declaration of Helsinki of 1964, as revisited in 2013.

Table 1
Characteristics of the study patients.
Patient Sex Age, years Systemic disease and related therapy Treated jaw Residual teeth Bone quality
Right Left Right Left
1 Female 67 Negative Upper 0 0 D4 D4
2 Male 62 Atrial fibrillation; warfarin 5 mg/day PO Upper 0 0 D4 D4
3 Female 59 Negative Upper 3 3 D3 D4
4 Female 62 Negative Upper 3 3 D2 D2
5 Female 56 Negative Upper 4 5 D4 D4
6 Female 72 Negative Upper 1 2 D4 D4
7 Female 71 Negative Lower 0 0 D3 D3
8 Male 75 Negative Upper 0 0 D4 D4
9 Male 63 Negative Upper 0 0 D3 D3
10 Female 60 Negative Lower 4 3 D2 D2
11 Female 51 Negative Upper 3 5 D3 D3

PO, orally.

Patients were enrolled if they met the following inclusion criteria: (1) male and female patients, over 18 years of age; (2) good general health condition and no contraindications to oral surgery (American Society of Anesthesiologists (ASA) risk ≤2); (3) non-smoker or having ceased their smoking habit for at least 5 years; (4) desire to be treated with fixed prostheses supported by dental implants in the upper or lower jaw; (5) patients affected by total edentulism or with a few hopeless residual teeth in the jaw designated to undergo immediate implant surgery; (6) sufficient bone volume to accommodate a minimum of four implants with a diameter of 4 mm and length of ≥13 mm; (7) anatomical and clinical situation as symmetrical as possible on the right and left sides of the jaw as regards bone quality (assessed with the Lekholm and Zarb 1985 classification ) and the presence/absence of teeth.

The exclusion criteria encompassed patients with pacemakers or other electro-medical equipment (as a precaution to avoid interference with the PEMF treatment), patients with a mucosal disease, and patients undergoing treatment with cortisone and/or warfarin. Indeed, cortisone can interfere with postoperative swelling and warfarin treatment can interfere with the production of blood clots at the surgical sites. In the case of a patient treated with warfarin, the following protocol was adopted: warfarin was discontinued 3 days prior to surgery and replaced with low molecular weight heparin, in agreement with the cardiologist; heparin therapy was discontinued on the day of surgery and was resumed the next day for 2 days; warfarin therapy was resumed on the third day after surgery and heparin administration was ceased. Only one patient in this study was being treated with warfarin ( Table 1 ).

Clinicians provided all candidates with a full explanation of the surgical procedure and the study protocol. All patients provided oral and written informed consent to participate in this research.

Study design

This was a split-mouth, double-blind, placebo-controlled study in which the PEMF treatment was assigned randomly to one side of the mouth by means of a simple randomization procedure (1:1 allocation ratio) with the use of a computer-generated list of random numbers.

Surgical procedures

Patients were treated with implant-supported full-arch immediate loading rehabilitation following the Columbus Bridge Protocol. The surgical and prosthodontic team carried out clinical and radiographic assessments prior to surgery in order to plan implant placement. The radiographic assessment consisted of preliminary panoramic radiographs ( Fig. 1 ), followed by a computed tomography (CT) examination.

Fig. 1
Radiographic examinations. (a) Panoramic radiograph obtained before surgery. (b) Panoramic radiograph obtained after surgery.

Details of the patient’s complete history, as reported by the patient, were also collected ( Table 1 ). Patients received 2 g of amoxicillin–clavulanic acid (875 mg–125 mg) 1 h before surgery and chlorhexidine 0.2% mouthwash 10 ml twice a day starting 48 h before surgery.

On the day of surgery, two expert surgeons carried out the following technical steps. First, regional anaesthesia was applied to the surgical areas by infusion with a vasoconstrictor (mepivacaine 20 mg/ml with adrenalin 1:100,000). Next, hopeless residual teeth and/or roots were extracted non-traumatically. A full thickness flap was raised with a slightly lingual/palatal incision, in order to preserve a sufficient amount of buccal keratinized mucosa. Then osteotomy and osteoplasty of the edentulous ridge were performed with a tungsten carbide bur mounted on a low-speed hand-piece, under constant irrigation with physiological sterile solution. Non-traumatic under-preparation of the implant sites was performed in the maxillary arch (burs working at 1200 rpm, bone irrigation with physiological sterile solution, and no ovalization of the implant site); the implant sites were not under-prepared if the jaw designated for surgery was the mandibular arch. Four implants were inserted at the level of the canines and first molars ( Fig. 1 ), with distal tilted implants parallel to the anterior sinus wall (diameter 4 mm, length 13 mm or 15 mm, and insertion torque ≥40 N cm) (Full Osseotite; Biomet 3i, Palm Beach Gardens, FL, USA). A continuous 4–0 silk suture was then applied. Impression copings were mounted on the implants and an impression of the dental arch was made with plaster impression material by pick-up technique. The impression copings were then disassembled and the healing abutments mounted on the implants.

The following information was recorded for each patient: number of tooth extractions and their sites, fixture diameter and length, primary stability of the fixture (insertion torque value, N cm), and intraoperative and postoperative complications.

PEMF devices

The RecoveryRx system (BioElectronics Corp., Frederick, MD, USA) used in this study is a non-invasive, disposable, drug-free localized system in the form of a patch for the management of postoperative swelling and pain with PEMF ( Fig. 2 ).

Fig. 2
The RecoveryRx PEMF system applied in the surgical areas.

The device consists of a microchip linked to a circuit loop 8 cm long (i.e. the antenna) that can be shaped on the skin in order to cover the areas of interest. It emits a safe form of non-ionizing electromagnetic radiation within the antenna. The power source is a battery with a life of almost 720 h in on/off mode or 170 h in continuous mode. The RecoveryRx generates an electromagnetic field of 27.12 MHz, which is at the short end of the radiofrequency band for medical use. The field has an extension of 100 μV/cm and a pulsed radiofrequency rate of 1 kHz, which induces low-level electromagnetic pulses on tissues. The peak burst output of power of the loop-antenna is about 0.0098 W. RecoveryRx circuitry consists of 3 V low-voltage digital–analogue electronics that control all timing functions to generate the PEMF above the surgical site.

According to the manufacturer, the electromagnetic waves act deeply through several centimetres into the soft tissues, modifying the nerve signals that regulate blood flow. This should stimulate the healing processes in the damaged tissues by enhancing blood flow and leading to a reduction in swelling and pain relief. The therapeutic field lies within the loop. For this reason it is highly recommended that the loop be placed directly over the source of pain for maximum treatment efficacy, since the energy intensity is high in the central part of the loop and decreases to zero towards its periphery. PEMF treatment is recommended for use in chronic wounds (diabetic foot ulcers, pressure venous leg ulcers) and in orthopaedics, podiatry, plastic surgery, and oral surgery. According to the manufacturer, the benefits in oral surgery include a reduction in scarring, pain, and inflammation, with accelerated healing.

Discharge protocol

Immediately after surgery, two RecoveryRx devices were applied to the patient’s cheeks (one on each) using medicated plasters that allow transpiration ( Fig. 2 ). The first device was fixed on the right cheek, while the second was fixed on the left cheek. The oval circuit loop of each device was shaped on the skin in order to include within it the area treated surgically. Only one of the two RecoveryRx devices, the right or the left one, was switched on (test site). The selection of the test site was done randomly by an independent researcher following a computer-generated list of random numbers. The other RecoveryRx was switched off and was applied as a placebo (control site). Patients, surgeons, and data collectors did not know which of the two RecoveryRx was active, because the red LED lights of both microchips were covered with medicated plasters. The surgeons instructed patients not to remove the PEMF devices during the following 48 h.

The application of ice at the sites of the surgical wounds was prohibited, as this would interfere with postoperative swelling. The postoperative antibiotic prescribed was 1 g amoxicillin–clavulanic acid (875 mg–125 mg) every 12 h for a week. Only if requested by the patient was an oral non-steroidal anti-inflammatory drug (NSAID) prescribed ( Table 2 ). Moreover all of the patients were instructed on postoperative hygiene and received a detailed written hygiene and diet protocol specifically designed for patients undergoing full-arch immediate loading rehabilitation.

Jan 16, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Effects of pulsed electromagnetic fields on swelling and pain after implant surgery: a double-blind, randomized study
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