Moon-Key Kim

Evaluation of condylar neck fracture plating techniques

The purpose of this study was to compare the biomechanical stability of four different plating techniques used to fix condylar neck fractures and to decide which fixation systems are strong enough to withstand the functional load. Ten recently acquired formalin-fixed cadaver mandibles were used for this study. Each of the four sets of osteotomized condylar processes was fixed by one of four different fixation systems. The mandibles were then held in an angle vice so that the mandibles were oriented to simulate actual masticatory force loading on the temporomandibular joint and were loaded with an Instron loading machine. Data demonstrated that a two-miniplate system applied to the anterior and posterior regions of the condylar neck was more stable than single-plate repairs using either mini-dynamic compression plates or 2.4 mm plates. The two-miniplate-fixation technique is indicated in cases of condylar neck fracture to achieve early mobility of the jaw and stability of the fracture site.

Onset of analgesia and analgesic efficacy of tramadol/acetaminophen and codeine/acetaminophen/ibuprofen in acute postoperative pain: A single-center, single-dose, randomized, active-controlled, parallel-group study in a dental surgery pain model

BACKGROUND The combination of tramadol and acetaminophen has demonstrated good efficacy in various clinical pain models. However, there is a need for comparisons of the onset of analgesia and other measures of analgesic efficacy with this combination and other strong combination analgesics for the management of acute pain. OBJECTIVE The goal of this study was to compare the time to onset of analgesia and other measures of analgesic efficacy with tramadol/acetaminophen 75/650 mg (Tr/Ac) and codeine/acetaminophen/ibuprofen 20/500/400 mg (Co/Ac/Ib) in the management of acute pain after oral surgery. METHODS This was a single-center, single-dose, randomized, active-controlled, parallel-group study in healthy subjects who had undergone surgical extraction of > or =1 impacted third molar requiring bone removal. When patients reported at least moderate pain after dental surgery (score > or =5 on a 10-point scale), they were randomized to 1 of 2 treatment groups. The time to onset of analgesia was measured using a 2-stopwatch technique. The time to the onset of perceptible and meaningful pain relief, pain intensity, pain relief, patients overall assessment, and adverse events were recorded for 6 hours after dosing. RESULTS One hundred twenty-eight subjects participated in the study, 64 in each treatment group. The 2 groups were similar in terms of baseline pain severity and demographic characteristics (mean age, 23.7 and 23.4 years in the Tr/Ac and Co/Ac/Ib groups, respectively; mean body weight, 58.5 and 60.3 kg). The median times to the onset of perceptible pain relief were a respective 21.0 and 24.4 minutes, and the median times to the onset of meaningful pain relief were 56.4 and 57.3 minutes. Mean total pain relief and the sum of pain intensity difference were also similar in the early period after dosing (0-4 hours). However, between 4 and 6 hours, Co/Ac/Ib was associated with significant differences in both variables compared with Tr/Ac (P < 0.05). Although similar through the 4-hour assessment, mean pain intensity difference was significantly greater with Co/Ac/Ib at 5 to 6 hours. The proportion of patients assessing their assigned treatment as good or better was significantly greater with Co/Ac/Ib compared with Tr/Ac (P < 0.05). The safety profile of Tr/Ac was comparable to that of Co/Ac/Ib. CONCLUSIONS In this small and selected group of subjects, the onset of analgesia and analgesic efficacy of Tr/Ac was comparable to that of Co/Ac/Ib. Tr/Ac provided rapid and effective analgesia for acute postoperative dental pain in this population.

Clinical experiences of digital model surgery and the rapid-prototyped wafer for maxillary orthognathic surgery

OBJECTIVE The aim of this study was to present our clinical experience regarding the production and accuracy of digitally printed wafers for maxillary movement during the bimaxillary orthognathic surgery. STUDY DESIGN Fifty-five consecutive patients requiring maxillary orthognathic surgery were included in this study. The plan for digital model surgery (DMS) was dictated by the surgical plans for each clinical case. We carried out digital model mounting, DMS, wafer printing, and confirmation of the accuracy of the procedure. RESULTS Moving the reference points to the target position in DMS involved a mean error of 0.00-0.09 mm. The mean errors confirmed by the model remounting procedure with the printed wafer by DMS were 0.18-0.40 mm (for successful cases; n = 42) and 0.03-1.04 mm (for poor cases; n = 3). CONCLUSION The accuracies of the wafers by DMS were similar to those for wafers produced by manual model surgery, although they were less accurate than those produced by DMS alone. The rapid-prototyped interocclusal wafer produced with the aid of DMS can be an alternative procedure for maxillary orthognathic surgery.

Three-dimensional anatomic analysis of mandibular foramen with mandibular anatomic landmarks for inferior alveolar nerve block anesthesia

OBJECTIVE We sought to standardize 3-dimensional anatomic positioning of the mandibular foramen (MnF) for inferior alveolar nerve block anesthesia. STUDY DESIGN Three-dimensional mandibular computerized tomography (CT) images were reconstructed from data for 49 patients aged 8-16 years (growth group) and 59 patients aged 18-25 years (adult group). To measure MnF position, we defined 5,6 as the superior contact point between the mandibular first molar and second premolar and 5,6 MnFP as the point on the MnF plane intersecting 5,6 at a right angle. The MnF plane passed through the MnF and parallel to the occlusal plane. RESULTS In the growth group, the distance from the MnF to the anterior ramus increased with age, as did distance from the gonion to MnF. CONCLUSIONS Measurements correlated significantly with age in the growth group. Needle insertion at an obtuse angle in the MnF plane from the contralateral first molar is appropriate for inferior alveolar nerve block anesthesia.

Accurate computerised mandibular simulation in orthognathic surgery: a new method for integrating the planned postoperative occlusion model.

Department of Oral and Maxillofacial Surgery, National Health Insurance Corporation Ilsan Hospital, 1232, Baekseok-dong, Ilsan-donggu, Goyang-si, yeonggi-do, 410-719, Republic of Korea Department of General Dentistry, Dental Hospital, Yonsei University, 134 Shinchon-dong, Seodaemun-Ku, Seoul, 120-752, Republic of Korea Department of Oral & Maxillofacial Surgery, College of Dentistry, Yonsei University, 134 Shinchon-dong, Seodaemun-Ku, Seoul, 120-752, epublic of Korea

Early orthognathic surgery with three-dimensional image simulation during presurgical orthodontics in adults.

To correct dentofacial deformities, three-dimensional skeletal analysis and computerized orthognathic surgery simulation are used to facilitate accurate diagnoses and surgical plans. Computed tomography imaging of dental occlusion can inform three-dimensional facial analyses and orthognathic surgical simulations. Furthermore, three-dimensional laser scans of a cast model of the predetermined postoperative dental occlusion can be used to increase the accuracy of the preoperative surgical simulation. In this study, we prepared cast models of planned postoperative dental occlusions from 12 patients diagnosed with skeletal class III malocclusions with mandibular prognathism and facial asymmetry that had planned to undergo bimaxillary orthognathic surgery during preoperative orthodontic treatment. The data from three-dimensional laser scans of the cast models were used in three-dimensional surgical simulations. Early orthognathic surgeries were performed based on three-dimensional image simulations using the cast images in several presurgical orthodontic states in which teeth alignment, leveling, and space closure were incomplete. After postoperative orthodontic treatments, intraoral examinations revealed that no patient had a posterior open bite or space. The two-dimensional and three-dimensional skeletal analyses showed that no mandibular deviations occurred between the immediate and final postoperative states of orthodontic treatment. These results showed that early orthognathic surgery with three-dimensional computerized simulations based on cast models of predetermined postoperative dental occlusions could provide early correction of facial deformities and improved efficacy of preoperative orthodontic treatment. This approach can reduce the decompensation treatment period of the presurgical orthodontics and contribute to efficient postoperative orthodontic treatments.

Genioplasty using a simple CAD/CAM (computer-aided design and computer-aided manufacturing) surgical guide

BackgroundThe present study introduces the design and fabrication of a simple surgical guide with which to perform genioplasty.MethodsA three-dimensional reconstruction of the patient’s cranio-maxilla region was built, with a dentofacial skeletal model, then derived from CT DICOM data. A surgical simulation was performed on the maxilla and mandible, using three-dimensional cephalometry. We then simulated a full genioplasty, in silico, using the three-dimensional (3D) model of the mandible, according to the final surgical treatment plan. The simulation allowed us to design a surgical guide for genioplasty, which was then computer-rendered and 3D-printed. The manufactured surgical device was ultimately used in an actual genioplasty to guide the osteotomy and to move the cut bone segment to the intended location.ResultsWe successfully performed the osteotomy, as planned during a genioplasty, using the computer-aided design and computer-aided manufacturing (CAD/CAM) surgical guide that we initially designed and tested using simulated surgery.ConclusionsThe surgical guide that we developed proved to be a simple and practical tool with which to assist the surgeon in accurately cutting and removing bone segments, during a genioplasty surgery, as preoperatively planned during 3D surgical simulations.

Verification of the usability of a navigation method in dental implant surgery: In vitro comparison with the stereolithographic surgical guide template method

OBJECTIVE This study investigates the usefulness of a navigation method using a reference frame directly fixed to the mandible compared to the stereolithographic (STL) surgical guide template method in dental implant surgery. MATERIALS AND METHODS Twenty rapid prototyping (RP) mandibular models were divided into two groups. Simulation surgery was performed using SimPlant software for both groups. The actual dental implants were placed in the RP models using a real-time navigation system or the surgical guide template, which was fabricated based on STL data by a 3-dimensional printer. Positional implantation errors were measured by comparing the simulation surgery implant positions to the actual postoperative implant positions. RESULTS The vertical distance error of the top surface area in the first molar region was not significantly different between groups. Otherwise, the implantation method using real-time navigation showed greater errors except for the horizontal and vertical errors in the apical area of the canine region. CONCLUSION The STL surgical guide template was associated with fewer errors than the real-time navigation method in dental implant surgery.

Modification of Planned Postoperative Occlusion in Orthognathic Surgery, Based on Computer-Aided Design/Computer-Aided Manufacturing–Engineered Preoperative Surgical Simulation

In orthognathic surgery, it is important to have a planned postoperative occlusion. A 3-dimensional preoperative simulation, based on 3-dimensional optically scanned occlusion data, can predict how the planned postoperative occlusion will affect the maxilla-mandibular relationship that results from orthognathic surgery. In this study we modified the planned postoperative occlusion, based on computer-aided design/computer-aided manufacturing-engineered preoperative surgical simulations. This modification made it possible to resolve the facial asymmetry of the patient successfully with a simple bilateral intraoral vertical ramus osteotomy and no additional maxillary or mandibular surgery.

Accuracy assessment of image-based surface meshing for volumetric computed tomography images in the craniofacial region.

Background Three-dimensional printing and computer-assisted surgery demand a high-precision three-dimensional mesh model created from computed tomography (CT) imaging data using an image-based meshing algorithm. We aimed to evaluate the three-dimensional geometric accuracy of surface meshes produced from CT images with commercially available software packages. Methods The CT images were acquired for 3 human dry skulls and 10 manufactured plastic skulls. Four commercially available software packages were used to produce the surface meshes in stereolithography (STL) file format. These CT-based STL surface meshes were registered and compared with three-dimensional optical-scanned reference mesh surface for evaluating the accuracy of the STL mesh produced with each software package. Results The surface geometries produced by the CT-image–based meshing process were all relatively accurate; differences from the three-dimensional optical-scanned data were in the voxel or subvoxel range. However, when comparisons with the three-dimensional optical-scanned surface data were performed in individual anatomic regions, we found significantly different accuracies of the CT-based STL surface meshes produced by the different software packages. Conclusions We found that all 4 software packages showed reasonably good meshing accuracies for clinical use. However, the range of errors inherent in the CT-image–based meshing process demands that caution should be taken in selecting and manipulating the software to avoid potential errors in specific clinical applications.