CAD/CAM fabrication of occlusal splints for orthognathic surgery.
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Computer-Aided Design↗
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The Virtual Pelvic Floor, a tele-immersive educational environment.
This paper describes the development of the Virtual Pelvic Floor, a new method of teaching the complex anatomy of the pelvic region utilizing virtual reality and advanced networking technology. Virtual reality technology allows improved visualization of three-dimensional structures over conventional media because it supports stereo vision, viewer-centered perspective, large angles of view, and interactivity. Two or more ImmersaDesk systems, drafting table format virtual reality displays, are networked together providing an environment where teacher and students share a high quality three-dimensional anatomical model, and are able to converse, see each other, and to point in three dimensions to indicate areas of interest. This project was realized by the teamwork of surgeons, medical artists and sculptors, computer scientists, and computer visualization experts. It demonstrates the future of virtual reality for surgical education and applications for the Next Generation Internet.
Anatomy↗
Plastic replicas as three-dimensional models of pulps.
It has been found that the plastic models significantly enhance the student's knowledge of the anatomy of teeth as it relates to operative dentistry. The fact that the models are three-dimensional eliminates guesswork as to the exact position of the pulp, and the rigidity of the plastic cast enhances the recovery of morphological features of the pulp as it existed in the natural tooth.
Dental Pulp↗
Analysis of human mandibular movement.
The parametric electrical outputs of the six-transducer mandibulograph were used to analyze three-dimensional pathways, displacement profiles, and velocity profiles of selected mandibular areas during jaw movement. This was accomplished by means of digital computer implementation of derived mathematical equations of motion. Five jaw movements were studied: chewing, open-close, right lateral, left lateral and protrusive. The results demonstrate the analytical and diagnostic value of this method and provice new clarification and insight into the nature of mandibular movements. The following observations summarize the principal findings derived from the analysis of jaw movement patterns of a normal patient. The chewing jaw movement exhibited a smoothly coordinated sequence of events. Lateral jaw motion appeared to be prominent during the masticatory phase and throughout the movement cycle. Mastication was abruptly terminated by a vertical desscent of the mandible through the freeway space, until the condyles began their forward movement producing a rotation in the sagittal plane. T occlusal area continued its downward descent along a nearly vertical pathway producing a compressed figure eight pattern in the frontal plane. The open-close jaw movement exhibited minor periods of hesitancy. Jaw movement was initiated with a forward and downward movement of the condyle occurring at the same time as a downward and backward movement of the occlusal area. This motion produced a rotation in the sagittal plane about a moving axis which was not coincident with the intercondylar axis. The general form of the command open-close jaw movement was that of noncoincident curved pathways in the sagittal plane with little lateral displacement. Closing jaw movement occurred with the condyle in a protruded position...
Adult↗
Model surgery prediction for mandibular midline distraction osteogenesis.
Mandibular midline distraction osteogenesis is available as a treatment option for the correction of mandibular transverse arch deficiency. A model surgery technique is presented here through a case report that will allow the surgeon to predict the amount of transverse expansion that can be gained by this procedure. Utilizing measurements from a three-dimensional stereolithography model, the mandibular cast is mounted on a semi-adjustable articulator. The maxillary model is mounted onto the articulator using an interocclusal record. Acrylic straps are fabricated that relate the condylar elements of the articulator to the right and left mandibular dental segments. The mandibular model is sectioned at the midline, the hemi-mandibular segments are rotated laterally until the desired midline expansion is achieved and the mandibular model is luted into its new position. The post-expansion relationship of the maxillary and mandibular arches can be visualized on the articulator and provide useful information to the surgeon and orthodontist.
Cephalometry↗
[Qualitative study, on a typodont, of the secondary effects in distal movement].
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Biomechanical Phenomena↗
A computerized model for teaching various methods of positioning the condyles to centric relation.
The entire masticatory system is within the realm of the dentist's responsibility, and therefore requires the dentist to have a working knowledge and understanding of the TMJs, neuromuscular system, and occlusion as well as the teeth and periodontal structures. This article presents how a computerized model can help dentists help their patients with TMJ disorders.
Centric Relation↗
Implant update: fabrication of a surgical template.
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Dental Implantation, Endosseous↗
Subgingival access and artificial plaque removal by a sonic cleaning device.
A sonic subgingival cleaning device (soniPick Sonic Interdental Plaque Remover) has recently been marketed with three bristle tips varying in size lengths and bundle diameters. The purpose of this study was to evaluate the ability of these bristle tips to remove subgingival artificial plaque deposits in a laboratory method used for toothbrushes. The laboratory method has been modified for testing the sonic device, to simulate the directions for using the product at home. The dimensions (length x bundle width) of three tips tested were: 0.007" x 0.040"; 0.007" x 0.062"; and 0.009" x 0.062". The tips used with the sonic device were placed on the tooth surface at a 20 degrees angle according to directions, and inserted 3 mm under simulated gingivae. The device was turned on and the tip was moved in a maximum 10 mm stroke for 15 seconds with the brushing machine. For control purposes, a flat, multi-tufted, ADA-accepted manual toothbrush (Oral-B P35) was also tested. The manual toothbrush was tested using the standard methods for evaluating toothbrushes, i.e., with the bristle tips placed at the gingival margin, then brushed at a 45 degrees angle at 250 g weight, using 15 mm strokes for 60 seconds. The depth of subgingival deposit removal was recorded as the maximum depth of the artificial plaque deposit removed from the pressure-sensitive paper under the simulated gingivae over anterior- or posterior-shaped teeth. In the assays conducted, the three bristle tips on the sonic device removed artificial plaque deposits under the simulated gingival at depths of 1.9-2.7 mm. The manual toothbrush had a mean subgingival cleaning depth of 0.6 mm. Differences between the three bristle tips used with the sonic device and the manual toothbrush were significant (p < 0.001 ANOVA). In this laboratory assay, all 3 bristle tips provided with the sonic cleaning device maintained access into and subsequent removal of artificial plaque from the subgingival space.
Analysis of Variance↗
3-D computer visualization and interactive prostate biopsy simulation leads to an improved systematic technique for the detection of prostate cancer: clinical correlation.
OBJECTIVES: Urologists routinely use the systematic sextant needle biopsy technique to detect prostate cancer. However, recent evidence suggests that this technique has a significant sampling error. Recent data based upon whole-mounted step-sectioned radical prostatectomy specimens using a 3-D computer assisted prostate biopsy simulator suggests that an increased detection rate is possible using laterally placed biopsies. A new 10-core biopsy pattern was shown to be superior to the traditional sextant biopsy. This pattern includes the traditional sextant biopsy cores and four laterally placed biopsies in the right and left apex and mid portion of the prostate gland. The objective of this study is to confirm the higher prostate cancer detection rate obtained using the 10-core biopsy pattern in a small cohort of patients. METHODS: We retrospectively reviewed 35 consecutive patients with a pathologic diagnosis of prostate cancer biopsied by a single urologist using the 10-core biopsy pattern. The frequency of positive biopsy was determined for each core. Additionally, the sextant and 10-core prostate biopsy patterns were compared with respect to prostate cancer detection rate. RESULTS: Of the 35 patients diagnosed with prostate cancer, 54.3% (19/35) were diagnosed when reviewing the sextant biopsy data only. Review of the 10-core pattern revealed that an additional 45.7% (16/35) of patients were diagnosed solely with the laterally placed biopsies. The laterally placed biopsies had the highest frequency of positive biopsies when compared to the sextant cores. CONCLUSIONS: Our results suggest that biopsy protocols that use laterally placed biopsies based upon a five region anatomical model are superior to the routinely used sextant prostate biopsy pattern. Lateral biopsies in the apex and mid portion of the gland are the most important.
Biopsy, Needle↗
Surgical template for completely edentulous patients.
Implant angulation is of utmost importance for fabrication of esthetic, hygienic, and functional prostheses, even in the treatment of completely edentulous patients. Most mandibular surgical templates are not reliable because of a lack of stability resulting either from severe resorption of the mandible or from the interference of mucoperiosteal flaps elevated during surgery. This article describes a technique for fabrication and surgical application of a stable template for the completely edentulous mandible. By combining the mandibular template with a maxillary duplicate denture, the problem of lack of stability can be overcome. A consistently reliable reference for implant placement in the edentulous mandible, specifically in relation to implant angulation (trajectory), can be obtained.
Acrylic Resins↗
Septal branches of right coronary artery as a source of blood supply to interventricular septum in morphological and clinical studies.
The aim of this article was to investigate septal branches of the right coronary artery in order to create both their typologies and to evaluate the usefulness of the vessels mentioned above for revascularisation procedures on the interventricular heart septum. The clinical studies were performed on 58 human hearts aged 28-80. Technical method of direct preparation, corrosive preparation and coronarographic picture assessment. The tests showed that the number of septal branches ranged from 5 to 11, their diameter from 0.7 to 1.2 mm. There were no main trunk or vessels with different dimensions than other arteries. Creation of septal vascularisation model was not possible because of rapid changes in studied vessels, their distribution and small diameters (about 1 mm) disqualifying them for direct revascularised operations on interventricular heart septum.
Adult↗
Simulating the spread of membrane potential changes in arteriolar networks.
OBJECTIVE: Our aim was to simulate the spread of membrane potential changes in microvascular trees and then make the simulation programs accessible to other researchers. We have applied our simulations to demonstrate the implications of electrical coupling between arteriolar smooth muscle and endothelium. METHODS: A two-layered, cable-like model of an arteriole was used, and the assumptions involved in the approach explicitly stated. Several common experimental situations that involve the passive spread of membrane potential changes in microvascular trees were simulated. The calculations were performed using NEURON, a well-established computer simulation program that we have modified for use with vascular trees. RESULTS: Simulated results show that membrane potential changes would probably not spread as far in the endothelium as they would in the smooth muscle of arterioles. Where feed arteries are connected to larger distributing arteries, passive spread alone may not explain the physiologically observed spread of diameter changes. CONCLUSIONS: Simulated results suggest that the morphology of an arteriole, in which the muscle layer is much thicker than the endothelium, favors electrical conduction along smooth muscle rather than the endothelium. However, it seems that passive electrical spread is insufficient to explain the apparent spread of membrane potential changes in experimental situations. Active responses involving voltage-dependent conductances may be involved, and these can also be included in our simulation.
Animals↗
Predictability of bimaxillary orthognathic surgery using "piggyback" intermediate splints.
Ten consecutive patients underwent bimaxillary surgery including segmental Le Fort I and bilateral sagittal split ramus osteotomies. All 10 patients were symmetric skeletal Class II malocclusion with an anterior open bite. Asymmetry cases were excluded. Dimensional changes depicted on the cephalometric prediction tracing were reproduced in the model surgery and then transferred to the patient during the operative procedure using a "piggyback" intermediate splint. All dimensional changes, except vertical, were transferred from the model surgery to the patient intraoperatively by using a "piggyback" intermediate splint. The accuracy of this transfer and final skeletal result was examined. All the data clearly showed that in no case was any discrepancy greater than 2 mm, which demonstrates the predictable results that can be achieved by using a "piggyback" intermediate splint in bimaxillary orthognathic surgery.
Cephalometry↗
Reliability of bimaxillary surgical planning with the 3-D orthognathic surgery simulator.
Functional and esthetic dysgnathia surgery requires accurate planning and precise surgical technique. Programs that simulate such surgery have thus become increasingly important. These are useless, however, when there is no technique for reproduction of surgical planning in the patient. This can be mediated by a surgical model. The present study investigates the accuracy resulting from use of the 3-D orthognathic surgery simulator (3-D OSS) in reproducing planned patient treatment. Eighteen patients with Angle Class III malocclusions who required bimaxillary surgery were evaluated. Planning criteria depended on the orthognathically intended occlusion and the jaw position simulated in the dentofacial planner, which predicted a harmonious profile. Model planning was carried out in the 3-D OSS. The accuracy of surgical reproduction was determined by cephalometric comparison of the postoperative cephalograms and computer simulation images. There were horizontal repositioning errors of 0.61 +/- 0.45 mm to 0.78 +/- 0.52 mm at the maxillary reference points (posterior nasal spine, anterior nasal spine, point A, and incision superius). Analysis of the positioning precision attained vertically was of the same order of magnitude, with values between 0.57 +/- 0.46 mm and 0.85 +/- 0.71 mm. Less precision was achieved in the mandible. The mean horizontal variation observed at incision inferius (0.91 +/- 0.51 mm) was still within the range of values for the maxilla, but an increase in the error to 1.61 +/- 0.79 mm was registered caudally to menton. The attained position of the maxilla did not vary significantly from the planned position (P < or = 0.05). Use of the orthognathic surgery simulator allowed precise implementation of the planned surgery. The model planning proved to be very helpful in preparing difficult bimaxillary operations.
Adult↗
Interrelationships between the width, depth, and perimeter of the dental arch.
Recently, beta function has been shown to be an accurate mathematical model of the human dental arch. In this article a beta function-based nomograph is presented that shows interrelationships between arch width, arch depth, and arch perimeter. This nomograph can be especially useful in predicting the effect of orthognathic surgery on these 3 variables of a dental arch.
Dental Arch↗
A novel missense mutation of the CBFA1 gene in a family with cleidocranial dysplasia (CCD) and variable expressivity.
The aim of this study was to analyze the CBFA1 gene in a phenotypically variable family with autosomal dominant cleidocranial dysplasia (CCD). Five members of a family with CCD were characterized clinically. X-rays and photographs of the two clinically affected family members were taken. The genotype of all five affected family members was determined with the use of single strand conformation polymorphism (SSCP) and direct sequencing. A point-mutation in exon 2 (R148G) was detected in a patient with the full-blown clinical phenotype. His son, demonstrating the same mutation, showed only the dental CCD characteristics. No mutation could be found in the three clinically healthy family members. To conclude, a missense mutation in the CBFA1 gene was detected in a family with variably expressed CCD syndrome. A detailed clinical examination is necessary to detect minimally affected gene mutation carriers.
Adult↗
TOMAC: an orthognathic treatment planning system. Part 2 VTO construction in the horizontal dimension.
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Adolescent↗