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.

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.

Case report of maxillofacial fracture in a patient under bisphosphonates in the absence of ONJ disease: Guidelines?

INTRODUCTION: Inspired by the presented case, this paper investigates treatment options for patients under active bisphosphonate therapy, suffering from a traumatic fracture in the absence of MRONJ (patients classified as 'at risk'). We review literature in search of standardized protocols and in combination. PRESENTATION OF CASE: A 75-year-old woman, suffering from osteoporosis for over a decade and being treated with alendronate for about 10 years, stumbled and fell and ended up with a displaced fracture on the right side of her extremely atrophied mandible. Under general anesthesia, using a limited submandibular approach with minimal reflecting of the periosteum, an external fixation device was placed. The patient recovered well from surgery and was discharged after 2 days. Long term follow-up shows good healing with a mouth opening of 46 mm in the absence of any sensory of functional deficits. DISCUSSION: We conclude from our literature review that there are no clear guidelines regarding fixation of traumatic (non-pathologic) maxillofacial fractures in patients under active antiresorptive therapy. Literature suggests that damaging the periosteum needs to be avoided since this would endanger the already fragile blood supply in the area. This could make an intra-oral approach unfavourable. CONCLUSION: We prefer an extra-oral approach whenever possible. The choice between the use of supraperiostally placed locking reconstruction plates or external fixation should be based on the overall medical condition of the patient, the regional osseous anatomy and the specific fracture morphology.

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.

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.

Accuracy of Dental Implant Placement Using CBCT-Derived Mucosa-Supported Stereolithographic Template.

PURPOSE: The aim of the present in vivo study was to evaluate whether a difference exists between the maxilla and the mandible regarding the precision of implant placement utilizing a cone beam computed tomography (CBCT)-derived mucosa-supported stereolithographic (SLA) template. MATERIALS AND METHODS: Eighty implants (44 maxilla, 36 mandible) were placed in 18 fully edentulous jaws (10 maxillas, eight mandibles) using a mucosa-supported SLA surgical template. A voxel-based registration technique was applied to match the postoperative and preoperative CBCT scans. RESULTS: Vertical deviation (p = .026) at the implant hex and angular deviation (p = .0188) were significantly lower in the maxilla than in the mandible. The global linear deviation and lateral deviation at the implant hex were not significantly different. At the implant apex, the average maximum vertical deviation was within 1 mm (0.1-4.6 mm). The average maximum lateral deviation was 1.8 mm (0.9-5.5 mm) in the maxilla and 2.3 mm (0.5-5.5 mm) in the mandible when a 15-mm-long implant was placed. CONCLUSIONS: When using CBCT-derived mucosa-supported SLA templates, clinicians should be aware of differences in the angular deviation of the implants in the mandible and maxilla. The average maximum linear deviation should be considered as a safety margin at the implant apex.

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 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.

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.

Validation of anatomical landmarks-based registration for image-guided surgery: an in-vitro study.

INTRODUCTION: Perioperative navigation is a recent addition to orthognathic surgery. This study aimed to evaluate the accuracy of anatomical landmarks-based registration. MATERIALS AND METHODS: Eighty-five holes (1.2 mm diameter) were drilled in the surface of a plastic skull model, which was then scanned using a SkyView cone beam computed tomography scanner. DICOM files were imported into BrainLab ENT 3.0.0 to make a surgical plan. Six anatomical points were selected for registration: the infraorbital foramena, the anterior nasal spine, the crown tips of the upper canines, and the mesial contact point of the upper incisors. Each registration was performed five times by two separate observers (10 times total). RESULTS: The mean target registration error (TRE) in the anterior maxillary/zygomatic region was 0.93 ± 0.31 mm (p < 0.001 compared with other anatomical regions). The only statistically significant inter-observer difference of mean TRE was at the zygomatic arch, but was not clinically relevant. CONCLUSION: With six anatomical landmarks used, the mean TRE was clinically acceptable in the maxillary/zygomatic region. This registration technique may be used to access occlusal changes during bimaxillary surgery, but should be used with caution in other anatomical regions of the skull because of the large TRE observed.

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.

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.

Plate removal following orthognathic surgery.

OBJECTIVES: The objectives of this study were to analyze outcomes with miniplates in orthognathic surgery and define risk factors resulting in plate removal. STUDY DESIGN: Clinical files of 570 orthognathic surgery patients operated between 2004 and 2009 were reviewed: 203 had a bimaxillary operation, 310 a lower jaw osteotomy, and 57 an upper jaw osteotomy. Age, sex, and jaw movement were analyzed. Reasons for hardware removal were recorded. RESULTS: Hardware was removed in 157 patients (27.5%). Seventy-eight patients (13.7%) needed removal because of plate-related infection; 66 (11.6%) because of clinical irritation; 5 (0.9%) for dental implant placement; and 8 (1.4%) for other reasons. Average time between operation and removal was 9.9 months. More women (31.7%) than men (20.3%) had plates removed, but age was not a factor except with infection. CONCLUSIONS: More than a quarter of patients developed complications from plates and screws, necessitating their removal, and infection occurred in 13.7%. Prompt removal constituted adequate management.

The use of a Kirschner wire in the treatment of a comminuted le fort I fracture: a case report.

Simultaneous fracture of the maxilla and cervical vertebrae rarely occurs in bicycling accidents. The following case report describes a simple technique for closed reduction of a severely comminuted maxillary fracture with shattering of the dentoalveolar process. The combination of a rigid external distractor halo frame on the skull, a Kirschner wire through the maxilla, and an intermaxillary wire fixation resulted in stable vertical and sagittal correction of the fragmented maxilla with adequate access and minimal manipulation and without necessitating removal of the cervical collar.

Proliferation of epithelial rests of Malassez following auto-transplantation of third molars: a case report.

INTRODUCTION: Auto-transplantation of third molars is frequently undertaken in order to restore a perfect occlusion and to improve mastication following a substantial loss of molars. However, little is known about the precise role of the periodontal membrane during this procedure. Therefore, we investigated if the epithelial rests of Malassez persist in the periodontal ligament of auto-transplanted teeth and, if so, whether these may show signs of a neuro-epithelial relationship. CASE PRESENTATION: We report a case of a 21-year-old Caucasian woman who underwent an auto-transplantation of two third molars. After two years, renewed progressive caries of the auto-transplanted teeth led to the removal of the auto-transplanted elements. The periodontal ligament was removed and studied with a light and transmission electron microscope. CONCLUSION: In this report we examined the ultrastructure of the periodontal ligament after auto-transplantation in order to see if the periodontal ligament recovers completely from this intervention. We observed fully developed blood vessels and a re-innervation of the epithelial rests of Malassez which were proliferating following auto-transplantation. This proliferation might be critical in the remodelling of the alveolar socket in order to provide a perfect fit for the transplanted tooth. In order to minimalise the damage to the epithelial rests of Malassez, the extraction of the tooth should be as atraumatic as possible in order to provide an optimal conservation of the periodontal ligament which will be beneficial to the healing-process.