Retrospective cohort assessment of survival and complications of zygomatic implants in atrophic maxillae.

OBJECTIVES: To report on zygomatic implant (ZI) survival rate and associated complications through a longitudinal retrospective cohort assessment. MATERIAL AND METHODS: A total of 940 ZIs (rough: 781, machined: 159; immediate loading: 454, delayed loading: 486) and 451 standard implants (rough: 195, machined: 256; immediate loading: 58, delayed loading: 393) were placed in 302 adult patients with atrophic maxilla from December 1998 till September 2020. Following data collection reported complications were grouped based on their origin as infectious/ non-infectious biological and mechanical. Statistical analysis was performed to identify risk factors and preceding complications leading to implant loss (P < 0.05). RESULTS: The survival rate of ZI was found to be 89.9% and the average time between implant placement and an eventual loss was 4.8 years. The mean ZI follow-up period was 7.9 ± 4.9 years. Amongst the infectious biological complications, sinusitis was the most reported (n = 138) occurring at a mean follow-up time-point of 4.5 years, whereas infraorbital nerve hypoesthesia occurred more frequently in the non-infectious biological category (n = 8, meantime: 0.3 years). The prosthetic screw fracture was the most reported complication of mechanical origin (n = 29, meantime: 4 years). Furthermore, sinusitis, standard implant loss, zygomatic/peri-zygomatic region infection, and oroantral communication were significantly associated with ZI loss. CONCLUSIONS: ZI placement offered a high survival rate for the rehabilitation of severely atrophied maxilla with most losses occurring within the first 5 years at follow-up. The most frequently observed complication was sinusitis which tends to develop several years following implant placement.

Peri-zygomatic infection associated with zygomatic implants: A retrospective longitudinal cohort study.

OBJECTIVES: The main objective of this retrospective, longitudinal, cohort study was to describe the occurrence of peri-zygomatic infection (PZI) as a complication associated with zygomatic implant (ZI) placement in a period of 22 years. MATERIALS AND METHODS: A retrospective search was carried out in the department of oral and maxillofacial surgery of Saint John's hospital in Genk, Belgium. Patients that had a severely atrophic fully or partially edentulous maxilla, and at least one ZI placed, were included. RESULTS: A total of 302 eligible patients, underwent ZI surgery between 1998 and 2020. From a total of 940 ZI, 45 were associated with the development of PZI. PZI was located in the upper portion of the cheek in relation to the external corner of the eye, one or two centimeters under the lower lid. The total number of affected patients was 25 (8.3%), who had a mean age of 58.1 years. In this subset, PZI occurred in 15 cases on the right side, in eight cases on the left side, and in two cases bilaterally. Ultimately, 16 ZI were lost in the PZI site. The mean time since the implant placement to the diagnosis of PZI was 1.9 years (SD ±2.4) and to the ZI removal of 3.8 years (SD ±3.7). After implant removal, the PZI symptomatology dissipated in all patients. CONCLUSION: Peri-zygomatic infection should be informed to the patients as a possible complication after ZI placement. Once identified, it should be acknowledged as a risk factor for ZI failure.

Modified Mandibular Inferior Border Sagittal Split Osteotomy Reduces Postoperative Risk for Developing Inferior Border Defects.

PURPOSE: The purpose of this study was to evaluate the impact of a modified sagittal split osteotomy (SSO) surgical technique on the incidence of persisting inferior border defects. The secondary aim was to identify risk factors associated with the development of these complications. MATERIALS AND METHODS: The patient charts and radiographs of 276 consecutive patients who underwent bilateral SSO, performed by a single surgeon in 2 different centers from July 2012 to September 2014, were retrospectively examined. The predictor variable was length of advancement. The outcome variable was the presence or absence of an inferior border defect. Other variables included age and side of the jaw. In all cases the same surgical technique was used. All statistical analyses were performed using SAS software, version 9.4 (SAS Institute, Cary, NC). RESULTS: The analysis included 408 operation sites in 204 patients (132 female and 72 male patients; median age, 22 years; age range, 13 to 66 years). In 5.1% of operation sites an osseous defect at the lower border of the mandible was observed. Age at the time of surgery (P < .0001) and length of advancement (P = .0111) were identified as risk factors for the development of a persisting osseous defect at the inferior border of the osteotomy gap after SSO. CONCLUSIONS: This study confirms the findings previously reported by our research group that the modified inferior border osteotomy technique in SSO results in a substantial lower frequency of persisting inferior border defects. Surgeons are advised to ensure that the lingual cortex of the inferior border is not included in the split during mandibular advancements, and in cases in which the advancement is more than 10 mm and/or the patient is older than 30 years, surgeons might want to consider using a bone graft or a bone graft substitute.

Attachment rate of the inferior alveolar nerve to buccal plate during bilateral sagittal split osteotomy influences self-reported sensory impairment.

This study was aimed to investigate a modified buccal osteotomy technique and whether the integrity of the lingual part of the lower border influences the attachment of the neurovascular bundle to the proximal segment of the mandible during a sagittal split osteotomy without increasing the number of bad splits. The presence of self-reported sensibility disturbance in the lower lip at the last follow-up visit was assessed. This study included 220 and 133 patients with bilateral sagittal split osteotomy undergoing the classical and the new modified buccal osteotomy techniques, respectively. In the new technique, the lower border is divided into a lingual fragment that remains incorporated in the tooth-bearing fragment and a buccal fragment that comes with the proximal fragment (buccal plate). In the classical technique, the inferior alveolar nerve was attached to the proximal segment of the mandible in more than one third of operation sites (36.36% on the right and 40.91% on the left) compared with less than one fourth of the operation sites using the new technique (9.73% on the right and 23.01% on the left). The overall figure of self-reported changed sensibility was 09.40% (12/128) in the new technique compared to 15.12% in the classical technique. We present a suitable improvement to the classical buccal osteotomy technique that allows less manipulation and injury of the inferior alveolar nerve with consequent reduction in self-reported postoperative changes in lower lip sensation

Safe surgical access to the mandibular nerve at the infratemporal fossae.

Some anatomic patterns formed by the anterior border of the ascending ramus relative to the mandibular canal can cause nerve complications during surgery. We determined the frequency of obstructive anatomy in patients undergoing jaw surgery, and we described a perioperative method for a bilateral sagittal split osteotomy that ensured inferior alveolar nerve (IAN) protection. The anatomy of the anterior border of the ascending ramus of the mandible was examined on axial and cross-sectional cone beam computed tomographic images of 114 consecutive patients undergoing bilateral sagittal split osteotomies. The thickness of the anterior border of the ascending ramus determined whether the mandibular foramen could be visualized (pattern A) or was obscured (pattern B). Patients with pattern B anatomy received a perioperative procedure. Direct visualization of the mandibular foramen was achieved in 100% of patients with pattern A anatomy. We examined 228 anterior borders of the ascending ramus of the mandible relative to the mandibular foramen in 114 patients. Pattern A was observed in 146 cases (64%); pattern B, in 82 (36%) cases. The use of the nerve hook resulted in no injuries to the IAN in all cases. The described procedure ensured direct visualization of the IAN, which prevented inadvertent damage to the IAN during instrumentation and surgical procedures at the mandibular foramen.

Osseous reconstruction using an occlusive titanium membrane following marginal mandibulectomy: proof of principle.

Guided bone regeneration using barrier membranes is useful in bone augmentation. In contrast to flexible membranes, stiff membranes such as titanium membranes are capable of maintaining sufficient space underneath them. We report a case of bone regeneration under an occlusive titanium membrane following marginal mandibulectomy in a 50-year-old patient with odontogenic keratocyst. Preoperative analysis of the anatomical conditions was evaluated with panoramic radiographs and spiral computer tomography (CT) scan. The digital data from the CT scan were transferred to a personal computer. Using Simplant software, a mirror image of the right mandible was constructed from which a custom-made titanium membrane was made. The cyst with the remaining inferior alveolar nerve was removed and curettage of the lesion was performed under general anesthesia. The definitive titanium plate was inserted and fixated with osteosynthesis screws, and then removed 5 years later. Postoperative CT scanning showed good healing, bone growth under the titanium plate, and no evidence of residual cyst The titanium plate reinforced the mandibular skeleton and restored the shape of the mandible and facial symmetry; it also promoted new bone formation to fill in the mandibular defects.

Accuracy of virtually planned and conventionally placed implants in edentulous cadaver maxillae and mandibles: a preliminary report.

STATEMENT OF PROBLEM: The accuracy of mental navigation is thought to depend on the clinician's spatial ability. Mental navigation, therefore, is associated with deviations between the mental plan and the definitive implant position. To learn more about the deviation that might occur, it is important to evaluate the accuracy of mental navigation during placement of implants. PURPOSE: The purpose of the study was to compare accuracy outcomes between virtually planned and conventionally placed implants, and among surgeons with varying experience. MATERIAL AND METHODS: Five completely edentulous sets of maxillae and mandibles from human cadaver heads were scanned by computed tomography. Five surgeons planned and placed 60 implants into these jaws, and accuracy was analyzed for 4 parameters: coronal and apical positions, angulation, and depth. The preoperative and postoperative computed tomographies were aligned in voxel-based registration software, which allowed comparison between virtually planned implant positions and actual implant positions. Data were analyzed with the t test (α=.05), ANOVA, and the Scheffé test. RESULTS: Mean (standard deviation) values were as follows: apex, 2.33 ±1.20 mm (range, 0.51-6.31 mm); coronal, 1.88 ±1.02 mm (range, 0.2-5.0 mm); angle, 7.34 ±3.62 degrees (range, 0.19-16.57 degrees); and depth, 0.03 ±1.15 mm (range, -3.47 to 2.10 mm). The apex and coronal position and the angle differed significantly between the virtually planned and actually placed implants. Significant between-surgeon differences were found in implant depth and coronal position. The apex and coronal positions differed significantly between the upper and lower jaw, with better performance achieved in the upper jaw. CONCLUSIONS: The results found statistically significant differences between the virtually planned and conventionally placed implants and among the 5 surgeons.

Risk factors for the development of lower border defects after bilateral sagittal split osteotomy.

PURPOSE: Defects at the lower border of the mandible may persist after bilateral sagittal split osteotomy (BSSO). The purpose of this study was to estimate the frequency of lower border defects after BSSO and to identify factors associated with the development of these defects. MATERIALS AND METHODS: This retrospective study included patients who underwent BSSO at St John's Hospital from January 2010 through December 2011. The predictor variables were length of advancement and inclusion of the full thickness of the lower border in the split. The outcome variable was the presence or absence of a lower border defect. Other variables were age and the side of the mouth. All analyses were performed using SAS 9.22. RESULTS: The analysis included 400 operation sites in 200 patients (124 female, 76 male; median age, 24.5 yr; range, 14 to 57 yr). A defect at the mandibular border presented in more than one third of operation sites. Inclusion of the full thickness of the lower border in the split, length of advancement, side of the jaw, and age (P < .0001) were risk factors for a permanent defect at the lower border of the osteotomy gap after BSSO. CONCLUSIONS: Inclusion of the full thickness of the lower mandibular border, the age of the patient, and the magnitude of advancement during BSSO are important predictors of whether a postoperative mandibular defect will remain after surgery. Surgeons should ensure that the lingual cortex of the lower border is not included in the split in large mandibular advancements.

Evaluation of 3 different registration techniques in image-guided bimaxillary surgery.

Perioperative navigation is an upcoming tool in orthognathic surgery. This study aimed to access the feasibility of the technique and to evaluate the success rate of 3 different registration methods--facial surface registration, anatomic landmark-based registration, and template-based registration. The BrainLab navigation system (BrainLab AG, Feldkirchen, Germany) was used as an additional precision tool for 85 patients who underwent bimaxillary orthognathic surgery from February 2010 to June 2012. Eighteen cases of facial surface-based registration, 63 cases of anatomic landmark-based registration, and 8 cases of template-based registration were analyzed. The overall success rate of facial surface-based registration was 39%, which was significant lower than template-based (100%, P = 0.013) and anatomic landmark-based registration (95%, P < 0.0001). In all cases with successful registration, the further procedure of surgical navigation was performed. The concept of navigation of the maxilla during bimaxillary orthognathic surgery has been proved to be feasible. The registration process is the critical point regarding success of intraoperative navigation. Anatomic landmark-based registration is a reliable technique for image-guided bimaxillary surgery. In contrast, facial surface-based registration is highly unreliable.

Accuracy of upper jaw positioning with intermediate splint fabrication after virtual planning in bimaxillary orthognathic surgery.

The purpose of the study is to present and discuss a workflow regarding computer-assisted surgical planning for bimaxillary surgery and intermediate splint fabrication. This study describes a protocol starting from wax bite registration to fabrication of the necessary intermediate splint. The procedure is a proof of concept to replace not only the model surgery but also facebow registration and transfer from facebow to articulator. Three different modalities were utilized to obtain this goal: cone beam computed tomography (CBCT), optical dental scanning, and 3-dimensional printing. A universal registration block was designed to register the optical scan of the wax bite to the CBCT data set. Integration of the wax bite avoided problems related to artifacts caused by dental fillings in the occlusal plane of the CBCT scan. Fifteen patients underwent bimaxillary orthognathic surgery. The printed intermediate splint was used during the operation for each patient. A postoperative CBCT scan was taken and registered to the preoperative CBCT scan. The difference between the planned and the actual bony surgical movement at the edge of the upper central incisor was 0.50 ± 0.22 mm in sagittal, 0.57 ± 0.35 mm in vertical, and 0.38 ± 0.35 mm in horizontal direction (midlines). There was no significant difference between the planned and the actual surgical movement in 3 dimensions: sagittal (P = 0.10), vertical (P = 0.69), and horizontal (P = 0.83). In conclusion, under clinical circumstances, the accuracy of the designed intermediate splint satisfied the requirements for bimaxillary surgery.

Obstructive airway compromise in the early postoperative period after orthognathic surgery.

Between January 1, 1989 and April 30, 2012, approximately 2164 consecutive patients were treated with orthognathic surgery at the St. John's Hospital, Genk, Belgium. They all underwent a mandibular, maxillary, or bimaxillary osteotomy, performed by one of the 3 resident maxillofacial surgeons at the St. John's hospital in Genk. The purpose of the review was to investigate the incidence of major airway difficulties occurring postoperatively because of surgically related causes. It seemed that obstructive airway compromise was the only reason for urgent intervention to protect or to restore the airway. In total, 3 urgent unanticipated life-saving reintubations were attempted. One was successful, and the other was changed into an urgent tracheostomy. No deaths occurred in this patient series after orthognathic surgery. Osseous genioplasties, as stand-alone surgery or in combination with other simultaneous orthognathic procedures, do care the risk for a life-threatening respiratory distress because of a hematoma of the floor of the mouth, when performed with an oscillating saw or a surgical drill. If so, this probably will happen within the first 4 postoperative hours according to the experience in our series. This risk can be avoided by using a piezosurgical unit to perform the osseous genioplasty.

Removal of a low-velocity projectile from the base of the sphenoid sinus using navigation-guided endoscopy.

PURPOSE: A patient surviving after a metal projectile penetrates the sphenoid sinus is unusual. Removing a foreign object from this region is challenging because of the difficult access and proximity to delicate structures. The use of navigation-guided endoscopy makes the manipulation of the surgical instruments near delicate structures safer, and the procedure is minimally invasive. RESULTS: A computed tomographic scan of brain showed the projectile located at the base of the left sphenoid sinus. To prevent infection and irritation and avoid secondary surgical damage, navigation-guided endoscopy was used to remove the bullet. Using the BRAINLAB navigation system, the movement of the endoscope could be followed on the screen, and the tip could be navigated into close contact with the projectile. The bullet could be located, without being visible through the endoscope, making the incision and removal of the bony wall of the sinus minimal; it was removed without complications. Intraoperative navigation of endoscopes is very useful because it enables the surgeon to correlate the visual information through the endoscope with the localization of the instruments seen on the navigation screen. Patient safety and reinforced self-confidence of surgeons are advantages of this procedure. Reduced operative time may not always occur because of a lack of experience with the navigation system. CONCLUSIONS: When there are no vascular or neurologic complications, a minimally invasive treatment using nasal navigation-guided endoscopic removal can limit the potential surgical damage.

Survival of conventional dental implants in the edentulous atrophic maxilla in combination with zygomatic implants: a 20-year retrospective study.

PURPOSE: Implant-supported prosthetic rehabilitation in the resorbed maxilla is a great challenge. The aim of this study was to determine the survival rate of conventional anterior implants placed in combination with zygomatic implants according to the Brånemark technique, and to identify risk factors for implant failure. METHODS: We collected data retrospectively from 72 consecutive patients who received treatment from 1998 to 2018 at our center, according to Brånemark's original technique. Kaplan-Meier analysis was conducted to assess survival rate, and a survival regression model was used with the patient as the random factor, applying the Weibull distribution. RESULTS: A total of 236 maxillary anterior implants were included, with a mean follow-up of 12.1 years. Kaplan-Meier analysis showed overall cumulative survival rates of 95.3% at 1 year, 94.8% at 2 years, 93.0% at 5 years, 90.5% at 10 years, 81.6% at 15 years, and 67.7% at 20 years. Survival regression showed an association between bruxism and implant failure as well as implants bearing an overdenture. Implants with length ≤ 10 mm had a significantly lower survival time. No significant association was found between the number of anterior implants and survival rate. CONCLUSIONS: We found acceptable long-term anterior conventional implant survival. Significant risk factors for failure were bruxism, overdentures, and implants shorter than 10 mm.

Patient Eligibility for Standardized Treatment of the Edentulous Mandible: A Retrospective CBCT-Based Assessment of Mandibular Morphology.

The aim of the study was to evaluate the proportion of patients recommended for full-arch mandibular restoration that would be eligible for treatment with a recently developed premanufactured full-arch prosthesis (Trefoil™, Nobel Biocare) based on the morphology of their lower jaw. Anonymized cone beam computed tomography (CBCT) data from 100 partially and fully edentulous patients referred for full-arch mandibular restoration were retrospectively collected from an imaging center database. Using custom-built software, CBCTs of mandibles were registered to a reference CBCT of a patient treated previously with a premanufactured full-arch prosthesis to determine if patients had adequate horizontal width and vertical height for implant placement. Bone height and thickness around simulated implants and distances to the incisive canal were evaluated. Mandibular arch width and semi-automated volume calculations were also performed. Using the system-specific 5.0 mm diameter implants with lengths of 13 and 11.5 mm, 85% and 86% of patients, respectively, were eligible for treatment with the standardized prosthesis. Eligibility was higher for men than women (odds ratio = 3.9, p = 0.045) due to increased bone volume. Based on mandibular morphology, our results suggest that the standardized treatment concept could serve a large percentage of patients with edentulous mandibles or failing dentition in the mandible.

Long-term outcome of autogenously transplanted maxillary canines.

The aim of this study was to determine the long-term outcome of autotransplanted maxillary canines and to investigate the influencing parameters. Seventy-one patients (84 transplanted canines) volunteered to participate in this study. The mean follow-up time was 21 years. In case of tooth survival and when patients were found willing for recall, teeth were investigated clinically and radiographically. Transplanted teeth were compared to the contralateral canine and scored with an aesthetic and radiographic index. The survival rate was 67.9%, considering that 27 transplanted teeth were lost before examination. The mean survival time was 15.8 years. Maxillary canine autotransplantation may have a successful outcome up to 21 years after transplantation requiring minimal patient compliance and low financial costs. The survival rate can be considered favorable realizing that autotransplantation is a treatment option in a selected group of cases.

Intraorbital hemorrhage following a secondary intervention at integrated zygomatic implants: A case report.

INTRODUCTION: Zygomatic implant placement can be the best option for restoring masticatory function of an extremely atrophic upper jaw, but the procedure is more invasive than conventional implant placement and can be associated with complications. PRESENTATION OF CASE: We report a complication that occurred during a secondary corrective surgical procedure four years after zygomatic implant placement. The patient was a 54-year-old female who had been edentulous for 25 years. Four zygomatic implants were placed. Subsequent prosthetic rehabilitation was successful. Four years later, the patient complained of discomfort. It was found that the tips of the implants on the right side were subcutaneously palpable and surrounded by granulomatous tissue. Intraoral surgery was performed to remove the protruding tips of the two implants. Post-operatively, the patient developed severe orbital pain on the right side with proptosis and diffuse swelling of the eyelids. Emergency surgery was performed to drain the intraorbital hemorrhage. The patient healed uneventfully without loss of visual acuity. DISCUSSION: Scarce prior reports describe trauma to the orbit during zygomatic implant surgery, mostly involving orbital penetration during zygoma implant placement. To our knowledge, the present case report is the first to describe an intraorbital hemorrhage that led to an orbital compression syndrome necessitating emergency surgery. CONCLUSION: In our case, corrective surgery in a patient with zygomatic implants resulted in an intraorbital hemorrhage, followed by an orbital compression syndrome. Emergency surgery was immediately performed, allowing hematoma drainage and eliminating compression of the intraorbital content. Symptoms quickly resolved and eyesight was not compromised.

Computer-assisted implant placement: scan template, simplant, surgiguide, and SAFE system.

Computer-driven implant dentistry uses the latest technology to coordinate every aspect of implant treatment. It provides a means with which to control the placement of implants with a high degree of accuracy. This is important, since accuracy has a direct bearing on the safety, esthetics, invasiveness, and cost of implant treatment. Computer-driven implant dentistry must be conceived as a chain in which every link is related to the others. Within this chain, there are elements that can be employed to maximize the benefits realized by computer-guided implant dentistry. A scan template is a radiologic template that permits visualization of the prosthetic plan prior to treatment and determines the course of implant treatment from the perspective of esthetics. The SimPlant software program (Materialise) allows implants to be planned in two and three dimensions using data received from a computerized tomographic scan. The resulting implant plan can be transferred to the mouth and implemented by means of a stereolithographic surgical guide (SurgiGuide, Materialise). Finally, the SAFE System (Materialise) is used for guided implant placement. It is associated with dedicated drilling devices and can be used in combination with SurgiGuides or with traditional acrylic resin guides manufactured by the dental lab on a synthetic plaster cast.

Biologic response of immediately versus delayed loaded implants supporting ill-fitting prostheses: an animal study.

BACKGROUND: Computer-assisted preoperative implant planning and transfer toward the patient allow the production of a prosthesis prior to surgery. This implies that the prosthesis can be installed immediately following implant insertion. An inherent disadvantage of this is a cumulated error, which can lead to prosthesis misfit owing to topographic deviations of the planned versus the installed implants. PURPOSE: The aim of this study was to determine whether prosthesis misfit is compromising the osseointegration of immediately versus delayed loaded implants and whether freshly installed implants adapt to the prosthesis. MATERIALS AND METHODS: In each of five New Zealand White rabbits, two experimental conditions were compared. One tibia harbored the so-called test implant, which originally showed a vertical misfit of about 500 microm with the prosthesis to which it was tightened immediately after implant installation. The control implant was installed in the other tibia and was allowed to heal during 9 weeks before the prosthesis with the vertical misfit of about 500 microm was connected to it. The prostheses were left in place for 12 weeks, after which the animals were sacrificed. RESULTS: All implants healed uneventfully. There were no statistically significant differences between the biologic responses of test and control implants. With a three-dimensional laser scanner, significantly more displacement of the test implants toward the prostheses was observed compared with the control implants. This led to a significant decrease in prosthesis misfit for the test implants compared with the control implants. CONCLUSIONS: This study indicates that prosthesis misfit does not per se lead to biologic failure of immediately loaded or of already osseointegrated implants. In addition, immediately loaded implants seem to topographically adapt to the prosthesis, thereby minimizing the existing misfit.

Accuracy of a Dedicated Bone-Supported Surgical Template for Dental Implant Placement with Direct Visual Control.

The aim of this study is to evaluate feasibility and accuracy of dental implant placement utilizing a dedicated bone-supported surgical template. Thirty-eight implants (sixteen in maxilla, twenty-two in mandible) were placed in seven fully edentulous jaws (three maxillae, four mandibles) guided by the designed bone-supported surgical template. A voxel-based registration technique was applied to match pre- and post-operative CBCT scans. The mean angular deviation and mean linear deviation at the implant hex and apex were 6.4 ± 3.7° (0.7°-14.8°), 1.47 ± 0.64 mm (0.5-2.56 mm) and 1.70 ± 1.01 mm (0.71-4.39 mm), respectively. The presented bone-supported surgical template showed acceptable accuracy for clinical use. In return for reduced accuracy, clinicians gain accessibility when using this type of surgical template for both the maxilla and the mandible. This is particularly important in patients with reduced mouth opening.

Coronectomy of Deeply Impacted Lower Third Molar: Incidence of Outcomes and Complications after One Year Follow-Up.

OBJECTIVES: The purpose of present study was to assess the surgical management of impacted third molar with proximity to the inferior alveolar nerve and complications associated with coronectomy in a series of patients undergoing third molar surgery. MATERIAL AND METHODS: The position of the mandibular canal in relation to the mandibular third molar region and mandibular foramen in the front part of the mandible (i.e., third molar in close proximity to the inferior alveolar nerve [IAN] or not) was identified on panoramic radiographs of patients scheduled for third molar extraction. RESULTS: Close proximity to the IAN was observed in 64 patients (35 females, 29 males) with an impacted mandibular third molar. Coronectomy was performed in these patients. The most common complication was tooth migration away from the mandibular canal (n = 14), followed by root exposure (n = 5). Re-operation to remove the root was performed in cases with periapical infection and root exposure. CONCLUSIONS: The results indicate that coronectomy can be considered a reasonable and safe treatment alternative for patients who demonstrate elevated risk for injury to the inferior alveolar nerve with removal of the third molars. Coronectomy did not increase the incidence of damage to the inferior alveolar nerve and would be safer than complete extraction in situations in which the root of the mandibular third molar overlaps or is in close proximity to the mandibular canal.