Piezosurgery has been used widely in oral and maxillofacial surgery, but there has been no report systematically describing an osteotomy method with piezosurgery for complicated mandibular third molar removal. The aim of this study was to introduce 4 osteotomy methods using piezosurgery and evaluate their effects.
Materials and Methods
A retrospective study was conducted of patients with a complicated impacted mandibular third molar requiring extraction. The predictor variable was the extraction technique. Four osteotomy methods using piezosurgery were tested according to different impaction types: method 1 involved complete bone removal; method 2 involved segmental bone removal; method 3 involved bone removal combined with tooth splitting; and method 4 involved block bone removal. Outcome variables were success rate, operative time, major complications (including nerve injury, mandible fracture, severe hematoma, or severe edema), and serious pyogenic infection. Data were analyzed using descriptive statistics.
The study was composed of 55 patients with 74 complicated impacted mandibular third molars. All impacted mandibular third molars were removed successfully. The average surgical time was 15 minutes (range, 8 to 26 minutes). Thirty-eight molars (51.4%) were extracted by method 1, 18 molars (24.3%) by method 2, 12 molars (16.2%) by method 3, and 6 molars (8.1%) by method 4. Two cases (2.7%) developed postoperative infections and recovered within 1 week using drainage and antibiotic administration.
The 4 osteotomy methods with piezosurgery provide effective ways of removing complicated impacted mandibular third molars.
The surgical removal of impacted mandibular third molars is a common surgical procedure. However, because of the relatively high surgical difficulty and incidence of major complications, it remains a challenging problem in some complicated cases. In clinical practice, the rotatory osteotomy technique has been widely adopted, but its defects are obvious: 1) the heat produced by the high-speed air-driven handpiece can lead to marginal osteonecrosis and impair regeneration and healing ; 2) the postoperative bone healing process is relatively slow ; 3) air flow from the high-speed air-driven handpiece can be forced into the soft tissue, resulting in subcutaneous emphysema ; and 4) bacterial contamination of the water supply system increases the incidence of alveolar osteitis. Contemporary surgical trends call for the maximum surgical effect and the minimum physical and psychological trauma to the patient. The urgency for a more rational, minimally invasive, and precise osteotomy method is strong. The advent of piezosurgery has shed new light on the problem.
During the past 5 years, piezosurgery has been used widely in oral and maxillofacial surgery, including sinus lift surgery, bone grafting, distraction osteogenesis, inferior alveolar nerve decompression, cyst excision, and removal of impacted teeth. Although various sources have advocated piezosurgery for impacted mandibular third molar removal, sparse information has been provided on the optimal osteotomy method for different impaction types. Furthermore, piezoelectric osteotomy techniques have a longer surgical time compared with rotatory osteotomy techniques.
The purpose of this study was to describe 4 osteotomy methods using piezosurgery for the application of complicated impacted mandibular third molar removal. The authors hypothesized that the unique extraction technique could remove complicated mandibular third molars successfully. The specific aim of the study was to evaluate its success rate, operative time, and incidence of major complication.
Materials and Methods
Study Design and Sample
To address the research purpose, a retrospective study was designed and implemented. The study population was composed of all patients who required removal of impacted mandibular third molars from April 2012 through October 2013. To be included in the study sample, patients must have met at least 1 of the following inclusion criteria: 1) a deeply impacted tooth (ie, below the cervical line of the adjacent second molar) or a fully impacted tooth; 2) all or most of the third molar in the ascending ramus of the mandible; 3) root hypertrophy (root wider than the neck), no periodontal space, or roots with an obvious curve (curvature, >45°) ; 4) an intimate relation between the inferior alveolar nerve and the impacted molar (contact or interruption of the cortical bone of the lower alveolar canal) ; or 5) the impacted third molar occupies more than 50% of the overall bony thickness of the mandibular angle.
Patients were excluded as study subjects if they had a history of uncontrolled diabetes, blood dyscrasias, alcoholism, drug abuse, and heavy smoking or if they had acute infections such as pericoronitis, acute alveolar abscess, or oral submucous fibrosis at the time of operation.
The predictor variable was the extraction technique.
All patients were informed about the procedure, the postoperative recovery time, and possible complications and they signed a detailed consent form. After a detailed medical and dental history was obtained, orthopantomographic and cone-beam computed tomographic (CBCT) images of the site were obtained, and treatment was started. The retrospective study followed the tenets of the Declaration of Helsinki for research involving human subjects, informed consent was obtained from all participants, and the study was critically reviewed and approved by the institutional review board of the Ninth People's Hospital (Shanghai, China).
All patients were operated on by the same surgeon under local anesthesia with 2% lidocaine. The osteotomy methods for a particular patient were selected according to the situation of the molar. A piezosurgical device (Silfradent SrL, S Sofia, Italy) was used for ostectomy to cut a precisely defined bony window. Cutting of bone and tooth was continuously accompanied by copious irrigation with chilled saline solution. No drainage and perioperative antibiotics were adopted in any cases. The extraction socket was debrided and filled with colloidal silver (Gelatamp; Coltene, Langenau, Germany). A spongiose bone substitute (Bio-Oss; Geistlich, Baden-Baden, Germany), filling, and coverage with a resorbable bilayer membrane (Bio-Gide) were used when the third molar was associated with a dentigerous cyst or a severe distal alveolar bone defect of the adjacent second molar. All extraction sockets were closed with 4-0 nonabsorbable silk sutures (Covidien, Mansfield, MA).
The extraction direction and osteotomy line were designed according to the impacted molar's radiographic and clinical manifestations (angulation of the tooth, state of eruption, root morphology, relation between the root and the inferior alveolar canal, and amount of surrounding alveolar bone). The 4 osteotomy methods using piezosurgery are described below.
Method 1: Complete Bone Removal
The indication for method 1 was third molars that were partially impacted and required a small amount of bone removal. The alveolar bone was cut along the osteotomy line and removed with a periosteal detacher. Then, the tooth was exposed and extracted by an elevator ( Fig 1 ).
Method 2: Segmental Bone Removal
The indication for method 2 was third molars that were deeply or fully impacted and required a large amount of bone removal. The alveolar bone was cut and sectioned along the osteotomy line and then removed with a periosteal detacher. Then, the tooth was exposed and extracted by an elevator ( Fig 2 ).
Method 3: Bone Removal Combined With Tooth Splitting
The indication for method 3 was a third molar with root hypertrophy (root wider than the neck). The alveolar bone was cut along the osteotomy line and removed with a periosteal elevator. A 2-mm-deep tooth-splitting line was prepared by a piezoelectric saw after alveolar bone removal. The tooth was split into 2 or 3 portions using a chisel to make a sharp blow on the tooth-splitting line and was delivered using a Cryer elevator posteriorly ( Fig 3 ).
Method 4: Block Bone Removal
The indication for method 4 was third molars that were deeply or fully impacted and exhibited dentoalveolar ankylosis. The alveolar bone was cut along the osteotomy line, and the tooth and surrounding bone were removed entirely with an elevator ( Fig 4 ).