Four Osteotomy Methods With Piezosurgery to Remove Complicated Mandibular Third Molars: A Retrospective Study



Four Osteotomy Methods With Piezosurgery to Remove Complicated Mandibular Third Molars: A Retrospective Study




Journal of Oral and Maxillofacial Surgery, 2014-11-01, Volume 72, Issue 11, Pages 2126-2133, Copyright © 2014 American Association of Oral and Maxillofacial Surgeons


Purpose

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.

Results

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.

Conclusion

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.


Study Variables

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).


Surgical Procedure

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 ).

Complete bone removal technique. A, Extraction site of a precise osteotomy procedure by piezoelectric saw. B, Removal of the alveolar bone with a periosteal elevator. C, The tooth was sufficiently exposed and delivered from the socket.
Figure 1
Complete bone removal technique.
A, Extraction site of a precise osteotomy procedure by piezoelectric saw.
B, Removal of the alveolar bone with a periosteal elevator.
C, The tooth was sufficiently exposed and delivered from the socket.


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 ).

Segmental bone removal technique. A, Cortical bone sectioned into appropriate pieces with a piezoelectric saw. B, Full exposure of the dental root after the removal of alveolar bone. C, The impacted molar was extracted entirely and gently in an occlusal direction.
Figure 2
Segmental bone removal technique.
A, Cortical bone sectioned into appropriate pieces with a piezoelectric saw.
B, Full exposure of the dental root after the removal of alveolar bone.
C, The impacted molar was extracted entirely and gently in an occlusal direction.


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 ).

Bone removal combined with tooth-splitting technique. A, A 2-mm-deep tooth-splitting line, prepared by the piezoelectric device, was the guide line for splitting the tooth by a chisel. B, The removed tooth showed the tooth-splitting line extending from the buccal groove to the furcation.
Figure 3
Bone removal combined with tooth-splitting technique.
A, A 2-mm-deep tooth-splitting line, prepared by the piezoelectric device, was the guide line for splitting the tooth by a chisel.
B, The removed tooth showed the tooth-splitting line extending from the buccal groove to the furcation.


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 ).

Block bone removal technique. A, Cone-beam computed tomogram shows the tooth has periapical periodontitis and contacts the mandibular canal. B, At the alveolar cortical bone, a precise osteotomy procedure was performed along the osteotomy line with a piezoelectric saw. C, The tooth and surrounding bone were removed entirely. D, Lingual view shows the tooth and surrounding bone stuck together.
Figure 4
Block bone removal technique.
A, Cone-beam computed tomogram shows the tooth has periapical periodontitis and contacts the mandibular canal.
B, At the alveolar cortical bone, a precise osteotomy procedure was performed along the osteotomy line with a piezoelectric saw.
C, The tooth and surrounding bone were removed entirely.
D, Lingual view shows the tooth and surrounding bone stuck together.


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Four Osteotomy Methods With Piezosurgery to Remove Complicated Mandibular Third Molars: A Retrospective Study Jing Ge MD, PhD , Chi Yang MD, PhD , Jia-Wei Zheng PhD , Dong-Mei He MD , Ling-Yan Zheng MD and Ying-Kai Hu MS Journal of Oral and Maxillofacial Surgery, 2014-11-01, Volume 72, Issue 11, Pages 2126-2133, Copyright © 2014 American Association of Oral and Maxillofacial Surgeons Purpose 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. Results 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. Conclusion 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. Study Variables 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). Surgical Procedure 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 ). Figure 1 Complete bone removal technique. A, Extraction site of a precise osteotomy procedure by piezoelectric saw. B, Removal of the alveolar bone with a periosteal elevator. C, The tooth was sufficiently exposed and delivered from the socket. 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 ). Figure 2 Segmental bone removal technique. A, Cortical bone sectioned into appropriate pieces with a piezoelectric saw. B, Full exposure of the dental root after the removal of alveolar bone. C, The impacted molar was extracted entirely and gently in an occlusal direction. 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 ). Figure 3 Bone removal combined with tooth-splitting technique. A, A 2-mm-deep tooth-splitting line, prepared by the piezoelectric device, was the guide line for splitting the tooth by a chisel. B, The removed tooth showed the tooth-splitting line extending from the buccal groove to the furcation. 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 ). Figure 4 Block bone removal technique. A, Cone-beam computed tomogram shows the tooth has periapical periodontitis and contacts the mandibular canal. B, At the alveolar cortical bone, a precise osteotomy procedure was performed along the osteotomy line with a piezoelectric saw. C, The tooth and surrounding bone were removed entirely. D, Lingual view shows the tooth and surrounding bone stuck together. Outcome Variables and Their Assessment The primary outcome variables were success rate, operating time (from the first incision to the last suture, with the duration of bone grafting deducted), and the incidence of major complications. Patients were recalled on postoperative days 7, 15, and 30 and examined for wound healing, nerve function, and major postoperative complications. Major complications included mandibular second molar injury, sensory impairment of lingual and inferior alveolar nerve, tooth pieces slipping into the pterygomandibular space, mandibular fracture, temporomandibular joint injury, excessive hemorrhage, severe swelling of the pharyngeal space, and severe pyogenic infection. The operative time and incidence of major complications were compared with data from previously published studies to evaluate the effect of the 4 osteotomy methods using piezosurgery. Third Category of Variables The third category of variables included age, gender, anatomic position of the third molar, and osteotomy method. Anatomic position of the third molar was assessed according to the inclusion criteria: status of eruption, relation with the ramus, root morphology, relation with the inferior alveolar nerve canal, and remaining bone volume of the mandibular angle. Data Analysis Data were analyzed using descriptive statistics. Results Fifty-five patients (26 men and 29 women; age range, 20 to 64 yr; mean age, 33 yr) fulfilled the eligibility criteria and 74 surgeries were performed. Forty third molars were on the right side and 34 were on the left. With regard to the inclusion criteria, 38 molars (51.4%) met inclusion criterion 1, 12 molars (16.2%) met inclusion criterion 2, 29 molars (39.2%) met inclusion criterion 3, 60 molars (81.1%) met inclusion criterion 4, and 9 molars (12.2%) met inclusion criterion 5. Twelve molars (16.2%) were associated with dentigerous cysts ( Fig 5 ). Figure 5 Distribution of samples that met the inclusion criteria. The osteotomy method was applied as follows: 38 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 ( Fig 6 ). Figure 6 Distribution of the adopted osteotomy method. All impacted mandibular third molars were successfully removed; thus, the success rate was 100%. The average surgical time was 15 minutes (range, 8 to 26 minutes). No major intraoperative complications occurred during the operation. No sign of inferior alveolar nerve or lingual nerve impairment was observed. Seventy-two extraction sites (97.3%) healed primarily. Two cases (2.7%) developed a postoperative infection and recovered within 1 week using draining and antibiotic administration. Discussion 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 this 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. The hypothesis that the 4 osteotomy methods using piezosurgery could be used to remove complicated mandibular third molars successfully was accepted. In this study, the authors proposed 4 osteotomy methods using piezosurgery after reviewing their 2-year experience of clinical applications. Among the 4 osteotomy methods, method 1 (complete bone removal) was the most frequently performed (51.4%). A third molar that was partially impacted and required a small amount of bone removal was the indication for method 1. Method 2 (segmental bone removal) ranked after method 1 (24.3%). A third molar that was deeply or fully impacted and required a large amount of bone removal was suitable for method 2. Method 3 (bone removal combined with tooth splitting) was the third most frequently performed technique (16.2%); it could eliminate the root resistance of a third molar with root hypertrophy (root wider than the neck). Method 4 (block bone removal) was the least frequently performed technique (8.1%); it was the optimal choice for a third molar with dentoalveolar ankylosis. Piezosurgery has prominent advantages, including precise cutting, soft tissue protection, and flexibility in complex anatomic areas, over conventional osteotomy instruments. The 4 osteotomy methods can be executed effectively. In addition, the alveolar bone removed by piezosurgery has better viability and integrity than that removed by rotatory instruments, so it can be used as a bone grafting substitute to facilitate bone regeneration of the extraction site. In this study, a complicated impacted mandibular third molar was defined as an impacted molar whose surgical removal is very difficult and prone to develop major complications. The widely used Pell-Gregory classification and modified Pederson scale address partial coverage of complicated impacted lower third molars. Root hypertrophy, no periodontal space, or roots with an obvious curve (curvature, >45°) can greatly increase the surgical difficulty and prolong the operative time, resulting in a higher incidence of dry socket and secondary pyogenic infection. For major complications, the intimate relation between the lower alveolar nerve and an impacted molar (contact or interruption of the cortical bone of the inferior alveolar canal) shows a greater incidence of inferior alveolar nerve injury. Because a ratio of 44 to 84% for the height of the third molar to the height of the mandible greatly increases the incidence of mandibular fracture, a ratio above 50% was an inclusion criterion. The anatomic structures listed earlier were added to the inclusion criteria. Preoperative examination of complicated impacted mandibular third molars is very important for surgical design. Compared with panoramic images, CBCT images are considerably superior in providing information about the angulation of the tooth, the state of eruption, the relation between an adjacent tooth and the inferior alveolar nerve canal, and the buccal and lingual bone thickness. The surgical design, including the osteotomy line, osteotomy method, and tooth extraction direction, is based primarily on CBCT images. The piezoelectric osteotomy technique has been described as a less efficient osteotomy technique compared with the rotatory osteotomy technique. However, the average surgical time was 15 minutes (range, 8 to 26 minutes) in this study, showing a relatively shorter duration compared with that in previously published studies using a rotatory osteotomy technique for complex extraction. It shows that the 4 osteotomy methods can be used to successfully complete the extraction with improved efficiency and decreased surgical difficulty. Owing to the complex anatomic factors, a complicated impacted mandibular third molar has a much higher incidence of major complications. The incidence of permanent injury to the inferior alveolar nerve has been reported to be lower than 1%. If a third molar has close proximity to the mandibular canal, the incidence is increased. In this study, 60 molars (81.1%) were contacting or interrupting the inferior alveolar nerve canal on the CBCT images. However, no patient declared neurosensory impairment. Weakening of the mandibular bone, as a result of a third molar occupying a large space in the mandibular bone or a third molar with dentoalveolar ankylosis requiring extensive bone removal, is the main cause of iatrogenic mandibular fracture. In this study, 9 molars occupied more than 50% of the height of the mandible and 10 molars were associated with dentoalveolar ankylosis on the CBCT images, although no mandibular fracture occurred. Nevertheless, excessive biting force should be avoided 1 month postoperatively. The incidence of infection after impacted mandibular third molar removal has been reported as 2.1 to 12.9%. Taking complicated impacted teeth into consideration, the incidence could be much higher. In this study, 2 cases (2.7%) developed postoperative infection, which was attributed to the greater degree of surgical trauma and bacterial contamination. No patient received drainage in this study; however, postoperative wound drainage should be used for tooth extraction with significant trauma to prevent infection. In addition, 72 cases (97.3%) achieved primary healing, so the 4 osteotomy methods can be used successfully to complete the extraction, with improved healing and a lower incidence of major complications. However, as a retrospective review, this study has its intrinsic limitation, and the conclusion drawn from these data compared with those in previously published articles is not adequate. From the results of the study, it can be concluded that the 4 osteotomy methods using piezosurgery can be used to remove complicated mandibular third molars successfully, may enhance efficiency, and lower the rate of major complication. 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