Mark W. Ochs

The effectiveness of flumazenil in reversing the sedation and amnesia produced by intravenous midazolam

In this double-blind study 31 outpatients undergoing third molar extraction were randomly assigned to one of two groups. All patients were sedated with intravenous midazolam (IV) by titration method. The flumazenil group (n = 20) received an average of 0.8 +/- 0.17 mg of flumazenil IV. The placebo patients (n = 11) each received 10 mL of normal saline. By both observer and patient alertness ratings, patients receiving flumazenil appeared significantly more alert than placebo patients at 5, 15, 30, and 60 minutes following reversal. After reversal the flumazenil group had significantly higher scores than the placebo group at all intervals through 60 minutes. All the patients receiving flumazenil were able to walk without assistance at 5 minutes, compared with only one patient in the placebo group, and more patients in the flumazenil group recognized the picture card shown to them at 5, 15, 30, and 60 minutes postreversal. Flumazenil is effective in terminating the amnestic properties of midazolam, but this appears to occur to a lesser extent than the reversal of its sedative properties.

Alveolar cleft bone grafting (Part II): Secondary bone grafting

Despite nearly a century of surgical experience in alveolar cleft repair’ and grafting; significant controversy remains in regards to timing, sequencing, and graft selection. With refinement and popularization of techniques by Boyne and Sands,2 secondary alveolar grafting has become an integral part of most cleft palate and craniofacial centers’ treatment philosophy and protocols. However, there remain advocates of primary alveolar grafting.’

Inductive, scaffold-based, regenerative medicine approach to reconstruction of the temporomandibular joint disk.

PURPOSE A device composed of extracellular matrix (ECM) was investigated as an inductive template in vivo for reconstruction of the temporomandibular joint (TMJ) disk after discectomy. MATERIALS AND METHODS A scaffold material composed of porcine-derived ECM was configured to mimic the shape and size of the TMJ. This device was implanted in a canine model of bilateral TMJ discectomy. After discectomy, 1 side was repaired with an ECM scaffold material and the contralateral side was left empty as a control. At 6 months after implantation, the joint space was opened, the joints were evaluated for signs of gross pathologic degenerative changes, and newly formed tissue was excised for histologic, biochemical, and biomechanical analysis. RESULTS The results showed that implantation of an initially acellular material supported the formation of site-appropriate, functional host tissue that resembled that of the native TMJ disk. Furthermore, this prevented gross degenerative changes in the temporal fossa and mandibular condyle. No tissue formation and mild to severe gross pathologic changes were observed in the contralateral controls. CONCLUSIONS These results suggest that an ECM-based bioscaffold could represent an off-the-shelf solution for TMJ disk replacement.

Intracranial reduction of an intact mandibular condyle displaced into the middle cranial fossa

Although displacement of the condyle intracranially is a relatively rare event, 1 this type of injury should be suspected when there is a history of the following : 1) severe trauma to the chin ; 2) limitation of opening ; 3) inability to close into occlusion ; 4) deviation of the chin toward the side of the suspected injury ; 5) occlusion only on the side of the suspected injury ; 6) cerebrospinal fluid (CSF) leak from the ear of the involved side ; 7) difficulty in interpreting condylar position on plain radiographs.6 The rarity of this injury, compared with subcondylar fractures, is related to the anatomy of the condylar neck, which is relatively weak compared with the rather dense posterior slope of the mandibular fossa. 2 Predisposing factors include : a thin condylar neck, 3 increased pneumatization of the temporal bone, lack of posterior teeth, or an open mouth position on impact. 4,5 Neurologic signs such as loss of consciousness, nausea, evidence of CSF leak, paresis of facial muscles, or deafness may indicate intracranial violation with resultant injury or edema. 6 Because of fibers from the inferior retina passing along the geniculocalcarine tract (Meyers loop) within the temporal lobe, a contralateral superior quadrantanopsia may ensue. Damage to vascular structures may cause a temporal lobe hematoma, resulting in clinical symptoms of lethargy, restlessness, or combativeness soon after the initial injury. Within a few hours of the formation of the hepatoma, focal neurologic signs may develop. These usually begin with weakness in the face and progress to hemiparesis by about the third day. Pupillary dilitation occurs late in the clinical course of an expanding hematoma. 7 It is recommended that patients undergo a computed tomography (CT) scan of the head and a neurosurgical consult be obtained in a case when there is clinical suspicion of intracranial injury.

The use of maxillary sinus endoscopy in the diagnosis of orbital floor fractures

PURPOSE The goal of the current study was to evaluate the ability to diagnose the presence of an inferior orbital wall fracture through the use of a transantral endoscopy technique at bedside. PATIENTS AND METHODS Seven trauma patients with initial axial computed tomography (CT) scan findings consistent with an orbital floor fracture were studied. Before endoscopy, the patients underwent a coronal CT scan with 3-mm cuts for later comparison with the endoscopic findings. The surgeon performing the endoscopy procedure was blinded to the results of the coronal CT scan. Visual acuity, intraocular pressure, and measurement for enophthalmos were performed before endoscopy. The endoscopic procedure was performed at the bedside using local anesthesia. A trocar was used in the canine fossa to gain access to the maxillary sinus. A 30 degrees and then a 70 degrees endoscope were introduced through the trocar to evaluate the integrity of the orbital floor (ie, maxillary sinus roof). The degree of mucosal injury of the orbital floor and the presence of blood or orbital contents in the sinus were recorded. The ophthalmologic examination was repeated after completion of endoscopy. RESULTS The endoscopic procedure was able to be completed in all patients. There was no change in the ophthalmologic examination in any patient as a result of endoscopy. In six of the seven patients studied, the endoscopic findings correlated with the need for surgical intervention to repair the orbital floor predicted on the basis of coronal CT scan. This was determined by the degree of injury to the orbital floor and the presence of hematoma, exposed bone, or fat. In the remaining case, endoscopy was not diagnostic for the presence of a fracture because only ecchymosis of the orbital floor was noted. CONCLUSIONS The ability to perform endoscopy under local anesthesia at the bedside is useful in those trauma patients whose concomitant injuries may prohibit other diagnostic modalities.

Extracellular Matrix as an Inductive Template for Temporomandibular Joint Meniscus Reconstruction: A Pilot Study

PURPOSE A device consisting of powdered porcine urinary bladder extracellular matrix (UBM-ECM) encapsulated within sheets of the same material was investigated as a scaffold for temporomandibular joint (TMJ) meniscus reconstruction. MATERIALS AND METHODS Five dogs underwent unilateral resection of the native meniscus and replacement with a UBM-ECM device. Necropsies were performed at 3, 4, 8, 12, and 24 weeks. Two additional dogs underwent bilateral resection of the meniscus with replacement with a UBM-ECM device on 1 side, leaving the contralateral side empty as a control. Necropsies were performed at 24 weeks for bilaterally treated animals. RESULTS Macroscopically, the UBM-ECM implants were remodeled rapidly and were indistinguishable from newly deposited host tissue at all time points. Microscopically, remodeling was characterized by a dense infiltration of predominantly CD68(+) mononuclear cells and smooth muscle actin-positive fibroblast-like cells at early time points changing with time to a sparse population of smooth muscle actin-negative spindle-shaped cells resembling those of the native fibrocartilaginous TMJ meniscus. Furthermore, the remodeling process showed deposition of predominantly type I collagen, the density and organization of which resembled those of the native meniscus by the 24-week time point. Ingrowth of calsequestrin-positive skeletal muscle tissue was also observed at the periphery of the remodeled UBM-ECM device and was similar to that found at the attachment site of the native meniscus to the surrounding soft tissues. Histologic results were identical for samples excised from both unilaterally and bilaterally treated animals. No adverse changes in the articulating surfaces of the condyle or fossa were observed in UBM-ECM-implanted joints. In the bilaterally treated animals, the unimplanted control side was characterized by degeneration and pitting of the articulating surfaces of both the condyle and the fossa, with disorganized bands of fibrous connective tissue observed within the joint space. CONCLUSION Results of this study suggest that the UBM-ECM device provides an effective interpositional material while serving as an inductive template for reconstruction of the TMJ meniscus.

Bone Morphogenetic Proteins in Craniomaxillofacial Surgery

Craniomaxillofacial surgery has many indications for bone regeneration and augmentation, ranging from socket preservation to reconstruction of large skeletal defects. The discovery of bone morphogenetic proteins (BMPs) as osteoinductive agents and the subsequent development of commercially available recombinant forms of BMPs have offered the potential to replace traditional grafting techniques with de novo bone formation. Extensive preclinical and clinical research has focused on establishing the safety and efficacy of using recombinant BMPs to regenerate bone in the facial skeleton. This article reviews the development and current scientific basis behind the use of these new biologics.

Immediate Loading of Single-Tooth Restorations: One-Year Prospective Results

Immediate loading of splinted implant restorations is a growing trend, but limited clinical documentation hampers evidence-based treatment planning for single-tooth applications. This study prospectively evaluated the clinical efficacy of placing implant-supported, single-tooth restorations into immediate, full-occlusal loading. Sixty consecutive patients (intent-to-treat group) with 1 missing tooth between 2 intact teeth were treated with a total of 69 implants. At placement, final impressions were made and implants were provisionalized with nonoccluding prostheses. Definitive prostheses were delivered 2 weeks later. A claim of noninferiority was made with a 95% confidence interval (Mann-Whitney U test) if the success rates between the experimental group and a 97% historical control was > 7%. Standardized radiographs taken at placement and bimonthly intervals were analyzed for crestal bone changes at a type I (alpha) error level of .05; significance levels were not adjusted for multiplicity (Fisher exact tests and Student t tests). Sixteen patients (18 implants) were withdrawn for protocol deviations. The resulting treated-per-protocol group consisted of 44 subjects with 51 implants. Cumulative implant success rates were 98.55% (n = 68/69) for the intent-to-treat group and 98.04% (n = 50/51) for the treated-per-protocol group. There were no significant adverse events or statistically significant differences between the experimental and historical control groups. At 12 months mean crestal bone loss was 1.05 mm, and ranged from 0.38 to 1.5 mm (77%) and 1.6 to 2.69 mm (23%). Immediate full-occlusal loading of single-tooth restorations was safely performed in selected subjects when good primary implant stability and an appropriate occlusal load were achieved.

The effects of guided tissue regeneration and fixation technique on osseous wound healing in rabbit zygomatic arch osteotomies.

The development of fibrous nonunions after craniofacial surgery is thought to result from an interaction of biomechanical stress and the differential migration of various tissue types into the wound site during healing. The present study is designed to test this hypothesis through the manipulation of guided tissue regeneration and osteotomy fixation techniques in an experimental rabbit model. Bilateral, critical size (5 mm), vertical osteotomies (n = 32) were produced in the zygomatic arches of eight adult rabbits. The mobile bony segments were fixed rigidly or nonrigidly using bone microplates and screws or osteosynthetic wires. The defects were then covered with a resorbable collagen membrane or left uncovered. The rabbits were followed for 4 weeks with serial dorsoventral cephalographs and the zygomatic arches harvested for histological analysis. Cephalometric results revealed significantly (p < 0.001) increased bone growth in the margins of the defects covered with the collagen membrane; however, no significant (p > 0.05) differences were noted between fixation techniques. Histological analysis revealed that defects fixed rigidly and covered by the membrane showed the most rapid and organized osseous wound healing, followed by the defects that were fixed nonrigidly and membrane covered. The defects not covered by the collagen membrane showed invasion by fibroblasts resulting in fibrous nonunions. These results demonstrate the efficacy of guided tissue regeneration with a resorbable collagen membrane in preventing fibrous tissue ingrowth in large bony defects. The addition of rigid fixation at a potentially mobile site appeared to enhance bony trabecular organization but not the osteogenic rate in this rabbit model.

Electromechanical impedance method to assess dental implant stability

The stability of a dental implant is a prerequisite for supporting a load-bearing prosthesis and establishment of a functional bone?implant system. Reliable and noninvasive methods able to assess the bone interface of dental and orthopedic implants (osseointegration) are increasingly demanded for clinical diagnosis and direct prognosis. In this paper, we propose the electromechanical impedance method as a novel approach for the assessment of dental implant stability. Nobel Biocare??implants with a size of 4.3?mm diameter ?13?mm length were placed inside bovine bones that were then immersed in a solution of nitric acid to allow material degradation. The degradation simulated the inverse process of bone healing. The implant?bone systems were monitored by bonding a piezoceramic transducer (PZT) to the implants? abutment and measuring the admittance of the PZT over time. It was found that the PZT?s admittance and the statistical features associated with its analysis are sensitive to the degradation of the bones and can be correlated to the loss of calcium measured by means of the atomic absorption spectroscopy method. The present study shows promising results and may pave the road towards an innovative approach for the noninvasive monitoring of dental implant stability and integrity.