Stephen R. Matteson

A simple method for taking natural-head-position cephalograms

Standing natural head position is a reproducible, physiologically determined aspect of function. Recent studies have demonstrated associations between this aspect of function and the form of the skeletodental features, in both growing and nongrowing persons. A simple method has been devised which obviates the need for multiple radiographs to determine the clinical reliability of the method. The device, its construction, and method of use are described.

Computed tomography: A three-dimensional study of the nasal airway

1. Accurate volume measurement of the nasal airway based upon computed tomography images sequentially generated along the length of the airway is possible. 2. The cross-sectional area of the airway at any position along its length can be determined. 3. The most constricted part of the airway is not necessarily at the location of the turbinates. 4. Details of hard- and soft-tissue anatomy not otherwise discernible can be detected with computed tomography imaging.

Direct digital radiography for the detection of periodontal bone lesions

In this study the diagnostic accuracy of D-speed and E-speed film in the detection of simulated periodontal bone lesions was compared with that of an electronic direct digital image receptor. Lesions of increasing depth were created in 11 human hemimandibles at the buccal cortical plate in the interproximal marginal bone area by means of 1.4 mm diameter round bursa. Specimens were imaged at each lesion stage with the use of all three receptors. Nine viewers used a 5-point rating scale to evaluate whether lesions were present or absent in the resulting images. Receiver operating characteristic curves were generated, and maximum-likelihood curve areas were calculated. The area under the curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for D-speed film, E-speed film, and the direct digital system were 0.745 +/- 0.038, 0.740 +/- 0.038, and 0.741 +/- 0.037, respectively. Critical ratio analysis was used to compare the means. No statistical difference was found between any of the three image receptors (p > 0.05) for the detection of simulated periodontal lesions 1.0 to 3.0 mm in depth, which suggested that the digital system performed comparably with conventional film systems.

A method for three-dimensional image reformation for quantitative cephalometric analysis

Recognition and treatment of craniofacial deformities require an understanding of complex skeletal structures in three planes of space. Traditional imaging techniques rely on biplanar radiographs which provide only two-dimensional data. The introduction of three-dimensional image display (3DIR) has provided a method of object analysis in three planes of space, obviating the need for mental reconstruction, and yielding more spatial information than was previously available. This study was undertaken to investigate the quantitative value of three-dimensional images compared with cephalometric techniques in assessing a craniofacial deformity. Metallic marker references were placed on a deformed skull. Measurements taken from cephalograms and three-dimensional images were compared with corresponding digitized and manual measurements taken from the skull. Three-dimensional image reformation provided a more accurate representation of the deformity than the cephalometric methods. Because all structural relationships are preserved in the CT data matrix, measurements are inherently accurate and reproducible. 3DIR offers dynamic advantages over cephalometric methods because data can be manipulated interactively. Further investigation is needed to study the importance of head position and to develop patient selection criteria, scan protocols, and surgical treatment planning algorithms.

Advanced Imaging Methods

Recent developments in imaging sciences have enabled dental researchers to visualize structural and biophysical changes effectively. New approaches for intra-oral radiography allow investigators to conduct densitometric assessments of dento-alveolar structures. Longitudinal changes in alveolar bone can be studied by computer-assisted image analysis programs. These techniques have been applied to dimensional analysis of the alveolar crest, detection of gain or loss of alveolar bone density, peri-implant bone healing, and caries detection. Dental applications of computed tomography (CT) include the detailed radiologic anatomy of alveolar processes, orofacial soft tissues and air spaces, and developmental defects. Image analysis software permits bone mass mineralization to be quantified by means of CT data. CT has also been used to study salivary gland disease, injuries of the facial skeleton, and dental implant treatment planning. Magnetic resonance imaging (MRI) has been used extensively in retrospective and prospective studies of internal derangements of the temporomandibular joint. Assessments based on MRI imaging of the salivary glands, paranasal sinuses, and cerebrovascular disease have also been reported. Magnetic resonance spectroscopy (MRS) has been applied to the study of skeletal muscle, tumors, and to monitor the healing of grafts. Nuclear imaging provides a sensitive technique for early detection of physiological changes in soft tissue and bone. It has been used in studies of periodontitis, osteomyelitis, oral and maxillofacial tumors, stress fractures, bone healing, temporomandibular joint, and blood flow. This article includes brief descriptions of the technical principles of each imaging modality, reviews their previous uses in oral biology research, and discusses potential future applications in research protocols.

Short-term changes of condylar position after sagittal split osteotomy for mandibular advancement.

OBJECTIVE The goal of this study was to quantify condylar position changes after mandibular advancement surgery with rigid fixation (screws). Radiographic changes in condylar position were determined in all planes (X, Y, and Z). Computed tomography with image reconstruction was used. STUDY DESIGN A consecutive population of patients who elected to have rigid fixation for surgical stabilization method were studied (n = 21). Computed tomography data were acquired in the axial plane through use of abutting 1.5-mm-thick slices. Data acquisition occurred 1 week preoperatively and 8 weeks postoperatively. Measurements were made from 2-dimensional reconstructions. RESULTS The averages were as follows: lateral displacement from midline, 1.2 mm (55% of patients); medial displacement from midline, 1.5 mm (45% of patients; range, 3.2 mm); condyle angle increase from coronal plane, 3.5 degrees (60% of patients); condyle angle decrease from coronal, 4.3 degrees (40% of patients; range, 8.5 degrees); superior rotation of proximal segment, 3.2 degrees (39% of patients); inferior rotation of proximal segment, 8.6 degrees (61% of patients; range, 15.6 degrees); superior displacement, 1.2 mm (60% of patients); inferior displacement, 1.0 mm (40% of patients; range, 2.5 mm); anterior displacement, 1.6 mm (33% of patients); posterior displacement, 1.6 mm (67% of patients; range, 2.8 mm). CONCLUSIONS Changes occurred in all planes, but the most common postoperative condyle position was more lateral; with increased angle, the coronoid process was higher and the condyle was more superior and posterior in the fossa.

Evaluation of condylar position from temporomandibular joint radiographs.

This investigation evaluated the accuracy of three different transcranial TMJ radiographic records of condylar position and joint space dimension. In addition, the study evaluated how reliably observers determined condylar position and joint space dimensions from the radiographs. The results of this investigation support the following conclusions. The classification of condylar position is not the same at different sagittal locations within a TMJ. Skull position and radiographic projection must be identical if joint space measurements from serial radiographs are to be compared. The actual joint space dimensions and the anatomic anterior/posterior position of the condyles in the glenoid fossae cannot be accurately recorded by the radiographic techniques used in this investigation. Condyle/fossa relationships cannot be classified reliably by subjective evaluation of TMJ radiographs.

Bone scanning with99mtechnetium phosphate to assess condylar hyperplasia. Report of two cases

Abstract Condylar hyperplasia poses a problem in planning treatment because it is a self-limiting process for some but not all patients. Continued growth creates a progressive deformity that requires condylectomy, whereas an enlarged condyle can be left in place after hyperplastic growth ceases, even if ramus surgery is needed to correct asymmetry. Bone scan with 99m technetium phosphate can be used to assist in making the differential diagnosis. In the two patients reported here, abnormal metabolic activity revealed by bone scans supported clinical and historical evidence that the condylar hyperplasia was active and required surgical correction, including condylectomy. The two cases demonstrate different approaches to postsurgical orthodontic treatment, depending on the amount of normal growth expected.

Radiographic appearance and population distribution of the pneumatized articular eminence of the temporal bone

The pneumatized articular eminence of the temporal bone (PAT) is a cavity similar to that seen in the mastoid process that occurs in the zygomatic process of the temporal bone. Panoramic radiographs of 1061 dental school patients were reviewed to determine the radiographic appearance and population characteristics of this finding; PAT was found in 28 patients (2.6%). The mean age of the patients was 32.5 years; there was no sex predilection and four patients showed this defect bilaterally. Two radiographic types of PAT were identified, unilocular and multilocular. Panoramic radiography appears to be an efficacious method to display the articular eminence for visualization of PAT. Due to the relatively common occurrence of PAT and the increasing amount of surgery of the temporomandibular joint, visualization of this defect becomes important for the clinician planning surgical manipulation of the articular eminence.

Extreme distal migration of the mandibular second bicuspid. A variant of eruption

A five-year study of 26,264 panoramic radiographs found distal positioning of the mandibular second bicuspid associated with a missing adjoining first molar in one of every 505 patients. Following early removal of the first molar, there is a 5% to 10% chance that the second bicuspid will migrate distally. It usually continues until it contacts the root of the second molar, and then rotates up into occlusion adjacent to the parallel with that tooth. Mesial drift seldom occurs in this circumstance; the resulting space between lower first and second bicuspids remains. Early conservative management can be very important in these cases, making periodic x-ray examination advisable whenever a molar has been lost and the adjoining bicuspid has not yet erupted.