Abstract
The purpose of this study was to evaluate the potential benefit of an ultrasonic device for cutting soft tissue in the surgical exposure of impacted canines. Forty-eight patients aged from 14 to 24 years were enrolled in this study. They were divided into two equal groups of 24 patients each. Patients in the first group were treated with ultrasonic surgery, whilst those in the second group were treated with a cold steel blade and served as a control group. Under ultrasonic surgery, the rate of cut was slower as compared to the cold steel blade. The ultrasonic cutting procedure was very time-consuming, however bleeding was greatly reduced and the time required for the entire surgical procedure was reduced as compared to the control group. The bonding procedure was aborted in three cases when using the cold steel scalpel, and a two-stage procedure was needed in these cases. Histological evaluation of the gingival resection showed no sharp cutting edges and no tissue necrosis. In conclusion, results of soft tissue cutting by ultrasonic surgery are encouraging. Vibration enhances the cutting ability of the blade and coagulates blood vessels as tissues are incised, with no necrosis occurring. Thus, it is may be possible to place brackets during the same surgery.
Introduction
Since the first reported use of ultrasound (US) in dentistry by Balamuth in 1952, when an industrial ultrasonic grinder was used to prepare cavities in extracted human teeth, ultrasonic surgical systems have been used to fragment, remove, and cut hard tissue using frequencies of 25–29 kHz, which are specific for cutting mineralized tissue, reducing the risk of nerve and vessel damage.
Generally, the vibratory energy is unfocused, as in US diagnostic imaging (frequency 1–10 MHz, power <0.05 W/cm 2 ). In contrast, in ultrasonic surgery, the focus of the ultrasonic waves, even at a low frequency (20–60 kHz), deploys relatively high-power vibratory energy (10–300 W/cm 2 ). It is well known that ultrasonic energy affects biological tissue through three mechanisms: micromechanical disarray, cavitation through oscillation of encapsulated microbubbles of gas or vapour, and finally a thermal effect as a result of a decreased dispersion of energy to surrounding tissues during use. Soft tissue dissection is a major matter in all spheres of surgery, and the use of US for cutting soft tissue is well documented in cataract phaco-emulsification, solid tumour resection and biopsies, and laparoscopic surgery of the abdomen and the uterus. However, its application in dentistry for soft tissue cutting has not yet been described.
Impacted canine surgery remains one of the most common and popular surgical procedures in orthodontic treatment, for aesthetic and functional reasons. In this surgery, the placement of the orthodontic attachment onto the tooth at the time of surgery can be limited by the extensive bleeding that occurs, which can obscure the surgical site and compromise bonding. It was hypothesized that the use of an ultrasonic device for cutting soft tissue would result in a significant reduction in bleeding, promoting optimal conditions for the bonding of orthodontic attachments, and also lead to a significant reduction in the duration of the surgery.
This study was designed as a qualitative observation of impacted maxillary canine surgery achieved with ultrasonic cutting of soft tissue. Further, the incidence of flap bleeding and the bonding of attachments to the impacted teeth at the time of surgical exposure were investigated.
Materials and methods
Patients
Forty-eight patients with retention of the primary canine beyond 14 years of age were enrolled in this study. Patients were divided into two equal groups of 24 patients each. Patients in the first group were treated with ultrasonic surgery, while those in the second group served as controls and the incision was made with a cold steel blade.
Only cases with maxillary impacted canines were included. A canine is considered impacted if it does not erupt into the mouth and remains in the alveolar bone in an ectopic position, apically in the vestibule, or near the middle of the alveolar bone, or palatally near the lateral incisors. Before surgery, adequate space was created to facilitate movement of the impacted tooth. The option to extract the canine was also considered for ankylosed teeth.
Cases who presented with external or internal root dilacerations or resorptions in the maxillary canines, those with canines lodged between the roots of the central and lateral incisors, and those with a pathologic or malformed root of the lateral incisor were excluded from the study.
Patients were instructed to stop medications and herbal and homoeopathic products (known to alter clot formation) for at least 2 weeks preoperatively.
Ethical approval was granted by the Ethics Committee of the Union of Tangiers Dental Surgeons.
Preoperative preparation
All patients received 2 g of amoxicillin 1 h before the surgical procedure and 3 g/day for the subsequent 5 days. Also the same postoperative instructions were given to all patients: to follow a soft and cold diet for 24 h, to take 1 tablet of 500 mg of paracetamol–50 mg of caffeine when needed for analgesia, and to use polyvidone mouthwash for 12 days.
Ultrasonic surgical exposure of impacted canines
Surgical system specifications
Piezoelectric crystals convert electrical energy into mechanical energy, which cuts soft tissue by tip vibration under a reduced irrigation. Ultrasonic tips create both heat and cavitational energy and the tip moves at ultrasonic frequencies between 25 and 37 kHz. The amount of heat generated is directly proportional to the operating frequency and generates a simultaneous haemostasis. The use of a lower frequency limits the production of significant thermal energy and thus minimizes the risk of thermal injury.
An ultrasonic frequency vibrating system – Surgywave ® (ESACROM Dental, Imola (BO), Italy) – was used in this study. The equipment is engineered for use in medical ultrasonic debridement and deep cleaning of the wound (hand piece weight: 182 g; power: ≤50 W; frequency: 27–37 kHz, vibration: 20–200 μm; flow rate of the hydraulic circuit: 5–50 ml/min).
Surgical approach
The tissue incision was achieved by running the tip scalpel, based on ultrasonic oscillation scratching, to realize smooth cutting of the soft tissue with reduced irrigation (10 ml/min). The cutting effect occurred when the tip was dragged like a scalpel across the tissue, which was fairly rapidly divided with reasonable haemostasis.
For facial impacted canines the following procedure was employed: under local anaesthesia a flap was raised using a slightly crestal incision using the ultrasonic cutting soft tissue system and a tip scalpel ( Fig. 1 ). The flap was reflected, and with an ultrasonic hand piece (for bone surgery) and a round ball tip, the bone was removed if necessary around the impacted canine ( Fig. 2 ), so that a button could be placed on the tooth at the time of surgery. The field was kept completely dry for proper button attachment. Next, the button was attached to the arch wire or mini-implant with a chain or wire extending from the attachment into the oral cavity ( Fig. 3 ). Before flap closure, the tooth was gently luxated with a small straight elevator or periotome to verify if ankylosed. The flap was then sutured back into its original position. The tooth was then orthodontically extruded, with an elastic thread attached from the chain to the fixed orthodontic appliances. Orthodontic force was applied in order to help the eruption of the tooth after tissue healing. Patients were followed up on day 7 (suture removal) and every week thereafter.
For palatal impacted canines, the tissue incision was achieved by running the ultrasonic tip scalpel ( Fig. 4 ). A full-thickness flap was raised from the premolar to the midline. A round tip was attached to the piezoelectric hand piece (for bone surgery) and was used to remove the thin shell of bone around the impacted tooth; the follicle was removed and the tooth was gently luxated. The tooth was then isolated and dried prior to attachment of the brackets. The button was attached to the arch wire with a wire or chain that passed under the flap and through the incision ( Fig. 5 ). The flap was sutured back into its original position. For the closed flap technique, the flap was completely closed (no window was made) and the chain was placed through the incision line. The same machines and ultrasonic tips were used in all cases, and the patients were operated on by the same oral surgeon.
Exposure of impacted canines using a steel scalpel (control group)
In the control group, the tissue incision was performed using a conventional cold steel scalpel using the same surgical approach and techniques as used for the facial and palatal impacted canines of the first group.
Postoperative assessment
The following parameters were assessed after surgery:
- (1)
Complications: Infection, swelling, and postoperative pain were recorded.
- (2)
Pain: Subjects were asked to rate their current level of pain on a 10-cm visual analogue scale (from 0 = no pain, to 10 = worst pain imaginable). Pain was evaluated at baseline (day of surgery) and at visits on days 1, 3, 5, and 7 postoperatively, at approximately the same time of the day. In addition, the number of analgesic tablets consumed in the first postsurgical week was recorded.
- (3)
Rate of cut: The rate of cutting expressed in mm/min was calculated by measuring the distance and time of cutting.
- (4)
Duration of the surgical procedure: The total duration of the surgical procedure was recorded for both groups.
- (5)
Histological evaluation of the cutting borders: The quality of tissue alteration and depth of coagulation necrosis were examined histopathologically. After cutting and staining the margins with black ink, four specimens from the ultrasonic surgery group were studied.
Statistical analysis
The statistical analysis was conducted using SPSS for Windows, version 10.0. Significant differences were defined as P < 0.05. Differences between groups were assessed with the Mann–Whitney test.
Materials and methods
Patients
Forty-eight patients with retention of the primary canine beyond 14 years of age were enrolled in this study. Patients were divided into two equal groups of 24 patients each. Patients in the first group were treated with ultrasonic surgery, while those in the second group served as controls and the incision was made with a cold steel blade.
Only cases with maxillary impacted canines were included. A canine is considered impacted if it does not erupt into the mouth and remains in the alveolar bone in an ectopic position, apically in the vestibule, or near the middle of the alveolar bone, or palatally near the lateral incisors. Before surgery, adequate space was created to facilitate movement of the impacted tooth. The option to extract the canine was also considered for ankylosed teeth.
Cases who presented with external or internal root dilacerations or resorptions in the maxillary canines, those with canines lodged between the roots of the central and lateral incisors, and those with a pathologic or malformed root of the lateral incisor were excluded from the study.
Patients were instructed to stop medications and herbal and homoeopathic products (known to alter clot formation) for at least 2 weeks preoperatively.
Ethical approval was granted by the Ethics Committee of the Union of Tangiers Dental Surgeons.
Preoperative preparation
All patients received 2 g of amoxicillin 1 h before the surgical procedure and 3 g/day for the subsequent 5 days. Also the same postoperative instructions were given to all patients: to follow a soft and cold diet for 24 h, to take 1 tablet of 500 mg of paracetamol–50 mg of caffeine when needed for analgesia, and to use polyvidone mouthwash for 12 days.
Ultrasonic surgical exposure of impacted canines
Surgical system specifications
Piezoelectric crystals convert electrical energy into mechanical energy, which cuts soft tissue by tip vibration under a reduced irrigation. Ultrasonic tips create both heat and cavitational energy and the tip moves at ultrasonic frequencies between 25 and 37 kHz. The amount of heat generated is directly proportional to the operating frequency and generates a simultaneous haemostasis. The use of a lower frequency limits the production of significant thermal energy and thus minimizes the risk of thermal injury.
An ultrasonic frequency vibrating system – Surgywave ® (ESACROM Dental, Imola (BO), Italy) – was used in this study. The equipment is engineered for use in medical ultrasonic debridement and deep cleaning of the wound (hand piece weight: 182 g; power: ≤50 W; frequency: 27–37 kHz, vibration: 20–200 μm; flow rate of the hydraulic circuit: 5–50 ml/min).
Surgical approach
The tissue incision was achieved by running the tip scalpel, based on ultrasonic oscillation scratching, to realize smooth cutting of the soft tissue with reduced irrigation (10 ml/min). The cutting effect occurred when the tip was dragged like a scalpel across the tissue, which was fairly rapidly divided with reasonable haemostasis.
For facial impacted canines the following procedure was employed: under local anaesthesia a flap was raised using a slightly crestal incision using the ultrasonic cutting soft tissue system and a tip scalpel ( Fig. 1 ). The flap was reflected, and with an ultrasonic hand piece (for bone surgery) and a round ball tip, the bone was removed if necessary around the impacted canine ( Fig. 2 ), so that a button could be placed on the tooth at the time of surgery. The field was kept completely dry for proper button attachment. Next, the button was attached to the arch wire or mini-implant with a chain or wire extending from the attachment into the oral cavity ( Fig. 3 ). Before flap closure, the tooth was gently luxated with a small straight elevator or periotome to verify if ankylosed. The flap was then sutured back into its original position. The tooth was then orthodontically extruded, with an elastic thread attached from the chain to the fixed orthodontic appliances. Orthodontic force was applied in order to help the eruption of the tooth after tissue healing. Patients were followed up on day 7 (suture removal) and every week thereafter.
