Marc Christian Metzger

Inferior Alveolar Nerve Transposition—An In Vitro Comparison Between Piezosurgery and Conventional Bur Use

An in vitro comparison between a new ultrasound-based piezoelectric device and a conventional bur was performed for lateralization or transposition of the inferior alveolar nerve to evaluate the effects on soft and hard tissue. Transposition of the inferior alveolar nerve was performed in the cadaver mandibles of 10 sheep: the left nerve was uncovered with a saline-cooled diamond-coated spherical bur (2000 rpm), and the right nerve was uncovered with the piezoelectric device mounted with a spherical diamond tip. The surface, the zone of bone defect, and the nerve were examined by light microscopy and laser microscopy. Bone treated with the rotary bur showed significantly smoother surfaces and shallower defect zones (50 microm) in comparison with the piezoelectric device (150 microm). Lesions of the epineurium and an increased amount of bone particles were found in the lesions prepared with the piezoelectric device. In vitro preparation with the piezoelectric device was more invasive to the bone than was a conventional diamond bur. Touching the inferior alveolar nerve resulted in roughening of the epineurium without affecting deeper structures. The degree of injury was lower than when using the conventional rotary bur.

Surgical treatment of bisphosphonate-associated osteonecrosis of the jaw: Technical report and follow up of 21 patients

INTRODUCTION Bisphosphonates are used to reduce skeletal related events in patients with bone consuming diseases such as osteoporosis and bone metastases. However recently there has been an increased awareness of bisphosphonate-associated necrosis of the jaws (BP-ONJ). Many authors propose conservative management in these cases but invariably the problem is not treated successfully allowing the bone defect to worsen. Recently there has been a move to treat this problem surgically. The aim of this retrospective study was to provide a surgical solution for patients suffering from BP-ONJ. MATERIALS AND METHODS All patients presenting with BP-ONJ were treated with bone debridement of the affected area and multilayer wound closure. The considered variables were: gender, age, underlying diagnosis, type of bisphosphonate (BP) used, duration of bisphosphonate use, route of administration, location of the osteonecrosis, clinical symptoms, association with dental treatment and surgical outcome. RESULTS Nineteen cases of a total of 21 demonstrated no recurrence of osteonecrosis during follow up (Mean 16 months - Range 12-24 months). One patient with a bilateral defect showed a dehiscence on one side and a small fistula on the contralateral side 6 weeks post-operatively and required revision surgery. Another patient developed a fistula after 4 weeks that was treated successfully with antibiotics and curettage. No patients had evidence of exposed bone, bland mucosa nor pain at the surgical site. CONCLUSION The technique described can be recommended for patients with BP-ONJ if a conservative treatment fails.

Computer-assisted therapy in orbital and mid-facial reconstructions.

Management of orbital and mid‐facial fractures requires a thorough ophthalmic evaluation and precise imaging. A principle goal of therapy is to anatomically reduce fracture segments and to restore a normal orbital volume as soon as possible. Diagnostic advances such as new surgical and imaging techniques have dramatically improved both the functional and aesthetic outcome of reconstructions.

Comparison of 3 Optical Navigation Systems for Computer-Aided Maxillofacial Surgery

OBJECTIVE To compare the accuracy of 3 computer-aided surgery systems for maxillofacial reconstruction. DESIGN Evaluation of 3 computer-aided surgery systems: StealthStation, VectorVision, and Voxim. SETTING The University of California, Davis, Department of Otolaryngology computer-aided surgery laboratory. PARTICIPANTS Four fresh cadaveric heads. MAIN OUTCOME MEASURE Mean target registration error. RESULTS The StealthStation was the most accurate (mean [SD] target registration error, 1.00 [0.04] mm), followed by VectorVision (1.13 [0.05] mm) and then Voxim (1.34 [0.04] mm). All values met statistical significance (P < .05). CONCLUSIONS Measurable accuracy differences were found among the navigation systems evaluated. The StealthStation was the most accurate. However, the differences are small, and the clinical significance for maxillofacial reconstruction is negligible.

Comparison of 4 registration strategies for computer-aided maxillofacial surgery

PURPOSE: Surgeons have recently started to use computer-aided surgery (CAS) to assist with maxillofacial reconstructive surgery. This study evaluates four different CAS registration strategies in the maxillofacial skeleton. MATERIALS AND METHODS: Fifteen fiducial markers were placed on each of four cadaveric heads. Four registration protocols were used: 1) group 1—invasive markers, 2) group 2—skin surface, 3) group 3—bony landmark, 4) group 4—intraoral splint. Two observers registered each head twice with each of the four protocols and measured the target registration error (TRE). The process was repeated on two different navigation systems for confirmation. RESULTS: The mean TRE values were: invasive, 1.13 ± 0.05 mm (P < 0.05); skin, 2.03 ± 0.07 mm (P < 0.05); bone, 3.17 ± 0.10 mm (P < 0.05); and splint, 3.79 ± 0.13 mm (P < 0.05). The TRE values were consistent across CAS systems. CONCLUSION: Of the techniques tested for CAS registration, invasive fiducial markers are the most accurate. Skin surface landmarks, bony landmarks, and an intraoral splint are incrementally less accurate.

Semiautomatic procedure for individual preforming of titanium meshes for orbital fractures.

Background: Three-dimensional reconstruction of the orbital floor is a key procedure in primary or secondary orbital deformity. A new procedure for individually bending and preforming implants preoperatively for the reconstruction of orbital fractures is presented. Methods: By using diagnostic computed tomographic scan data, the topography of the orbital floor and wall structures can be recalculated. After mirroring the unaffected side onto the affected side, the defect can be reconstructed virtually. Data of the individual virtual model of the orbital cavity are sent to a template machine that reproduces the surface of the orbital floor and medial walls automatically. A titanium mesh can then be adjusted preoperatively for exact three-dimensional reconstruction. Twelve patients with orbital fractures were treated using individually preformed titanium implants. Results: All patients treated with this procedure showed normal eye mobility and function after primary reconstruction. The accuracy of the preformed implants lies in the range of 1 mm. Conclusions: This procedure offers an individual anatomical reconstruction of the orbital cavity true to original, especially when the deep orbital cone is affected. Navigation-aided procedures guarantee intraoperatively an exact placement of the preformed mesh even for precise reconstruction of extensive orbital defects.

Morphometric analysis - Cone beam computed tomography to predict bone quality and quantity.

AIM Modified quantitative computed tomography is a method used to predict bone quality and quantify the bone mass of the jaw. The aim of this study was to determine whether bone quantity or quality was detected by cone beam computed tomography (CBCT) combined with image analysis. MATERIALS AND PROCEDURES: Different measurements recorded on two phantoms (Siemens phantom, Comac phantom) were evaluated on images taken with the Somatom VolumeZoom (Siemens Medical Solutions, Erlangen, Germany) and the NewTom 9000 (NIM s.r.l., Verona, Italy) in order to calculate a calibration curve. The spatial relationships of six sample cylinders and the repositioning from four pig skull halves relative to adjacent defined anatomical structures were assessed by means of three-dimensional visualization software. RESULTS The calibration curves for computer tomography (CT) and cone beam computer tomography (CBCT) using the Siemens phantom showed linear correlation in both modalities between the Hounsfield Units (HU) and bone morphology. A correction factor for CBCT was calculated. Exact information about the micromorphology of the bone cylinders was only available using of micro computer tomography. CONCLUSION Cone-beam computer tomography is a suitable choice for analysing bone mass, but, it does not give any information about bone quality.

Three-Dimensional Plotting and Printing of an Implant Drilling Guide: Simplifying Guided Implant Surgery

PURPOSE To present an efficient workflow for the production of implant drilling guides using virtual planning tools. For this purpose, laser surface scanning, cone beam computed tomography, computer-aided design and manufacturing, and 3-dimensional (3D) printing were combined. MATERIALS AND METHODS Intraoral optical impressions (iTero, Align Technologies, Santa Clara, CA) and digital 3D radiographs (cone beam computed tomography) were performed at the first consultation of 1 exemplary patient. With image processing techniques, the intraoral surface data, acquired using an intraoral scanner, and radiologic 3D data were fused. The virtual implant planning process (using virtual library teeth) and the in-office production of the implant drilling guide was performed after only 1 clinical consultation of the patient. Implant surgery with a computer-aided design and manufacturing produced implant drilling guide was performed during the second consultation. The production of a scan prosthesis and multiple preoperative consultations of the patient were unnecessary. CONCLUSIONS The presented procedure offers another step in facilitating the production of drilling guides in dental implantology. Four main advantages are realized with this procedure. First, no additional scan prosthesis is needed. Second, data acquisition can be performed during the first consultation. Third, the virtual planning is directly transferred to the drilling guide without a loss of accuracy. Finally, the treatment cost and time required are reduced with this facilitated production process.

Speech and Swallowing Impairment After Treatment for Oral and Oropharyngeal Cancer

OBJECTIVES To assess the prevalence of speech and swallowing impairment after radical surgery for oral and oropharyngeal cancer from the patients viewpoint and to examine the association of these functional alterations with selected clinical characteristics regarding patients, tumors, and oncologic treatment. DESIGN Cross-sectional, multicenter study using a self-administered questionnaire. SETTING Forty-three hospitals in Germany, Switzerland, and Austria. PATIENTS A total of 3894 questionnaires about rehabilitation problems after treatment for oral and oropharyngeal squamous cell carcinoma were sent to patients. Of these, 1652 were filled out and returned, and 1334 (80.8%) met the inclusion criteria. MAIN OUTCOME MEASURES Morbidity associated with treatment of oral and oropharyngeal cancer. RESULTS Speech problems were reported by 851 patients (63.8%), and swallowing problems were reported by 1006 patients (75.4%). The variables that presented a significant association with speech and swallowing impairment were sex, tumor location, pTNM stages, stage of tumor, treatment modality, and reconstruction type. CONCLUSIONS This survey, based on patient perception, suggests that those who undergo radiotherapy associated with the surgical removal of a tumor, have late-stage tumors (III-IV), or have tumors located in the floor of the mouth should be informed of the greater risk of persistent severe speech and swallowing problems.

Anatomical shape analysis of the mandible in Caucasian and Chinese for the production of preformed mandible reconstruction plates

PURPOSE The purpose of this study was to evaluate and analyze statistical shapes of the outer mandible contour of Caucasian and Chinese people, offering data for the production of preformed mandible reconstruction plates. METHODS A CT-database of 925 Caucasians (male: n=463, female: n=462) and 960 Chinese (male: n=469, female: n=491) including scans of unaffected mandibles were used and imported into the 3D modeling software Voxim (IVS-Solutions, Chemnitz, Germany). Anatomical landmarks (n=22 points for both sides) were set using the 3D view along the outer contour of the mandible at the area where reconstruction plates are commonly located. We used morphometric methods for statistical shape analysis. RESULTS We found statistical relevant differences between populations including a distinct discrimination given by the landmarks at the mandible. After generating a metric model this shape information which separated the populations appeared to be of no clinical relevance. The metric size information given by ramus length however provided a profound base for the production of standard reconstruction plates. CONCLUSION Clustering by ramus length into three sizes and calculating means of these size-clusters seem to be a good solution for constructing preformed reconstruction plates that will fit a vast majority.