Pre-clinical evaluation of a new dental panoramic radiographic system based on tomosynthesis method.

OBJECTIVES: The purpose of the study was to compare the image generated by a classic panoramic machine equipped with a cadmium telluride sensor capable of digital tomosynthesis and special software with images produced by other popular panoramic X-ray machines using a charge-coupled device and native software for image capture. METHODS: Panoramic images were made using a phantom of a human skull on Planmeca ProMax, Planmeca EC Proline, Kodak 8000 and PC-1000. With the last machine we used the PanoACT® software to adjust the entire arch and to adjust the image in selected regions of interest (ROIs). Ten viewers evaluated the images and provided the viewer data. ANOVA for repeated measures was used to compare the means by pairwise comparisons of means. RESULTS: The image of the entire arch adjusted by the PanoACT® software was statistically superior to the images produced by other machines. The images generated and individually adjusted by PanoACT® were statistically superior to all other images. CONCLUSIONS: The image generated by the cadmium telluride sensor has great potential and can be processed to create superior images to those taken with other machines. Furthermore, the ROI individual images enhanced by the PanoACT® were superior to the entire arch adjusted by the same software.

Development of a new dental panoramic radiographic system based on a tomosynthesis method.

The objective of this study was to develop a new practical method to reconstruct a high-quality panoramic image in which radiographers would be free from the onerous task of correctly locating the patient's jaws within the image layer of the panoramic unit. In addition, dentists would be able to freely select any panoramic plane to be reconstructed after the acquisition of the raw scan data. A high-speed data acquisition device was used with a CdTe (cadmium telluride) semiconductor detector and a sophisticated digital signal-processing technique based on tomosynthesis was developed. The system processes many vertical strip images acquired with the detector and generates a high-resolution and high-contrast image. To apply the tomosynthesis technique to the acquired strip images correctly, the actual movement of the panoramic unit was measured, including the X-ray tube and detector, in a scan using a calibration phantom and the authors generated a shift amount table needed for the shift-and-add tomosynthesis operation. The results of the experiments with a PanoACT-1000 panoramic unit, which was a PC-1000 panoramic unit fitted with a high frame rate semiconductor detector SCAN-300FPC, demonstrated the capability of a tomosynthesis technique which, when applied to the strip images of a dry skull phantom, could change the location and inclination of an imaging plane. This system allowed the extraction of an optimum-quality panoramic image regardless of irregularities in patient positioning. Moreover, the authors could freely reconstruct a fine image of an arbitrary plane with different parameters from those used in the original data acquisition to study fine anatomical details in specific locations.

Salivary secretion, mucin concentrations and Candida carriage in HIV-infected patients.

OBJECTIVES: To test whether the submandibular/sublingual (SMSL) salivary secretion, mucin concentration and candida carriage status were altered in human immunodeficiency virus-positive (HIV+) patients. SUBJECTS AND METHODS: SMSL saliva collected from 48 HIV-infected and 31 HIV-negative men were analyzed for flow rates, total protein and mucin concentrations. Salivary cultures were performed for Candida assessment. RESULTS: The salivary flow rate and protein secretion of the HIV+ patients was 37% and 32% less than that of the controls (P < 0.0001, P = 0.0087). The mucin concentrations (MG1 and MG2) were higher in the HIV+ subjects compared with controls (P = 0.0186, P = 0.0014); however, the mucin secretions were not different. The frequency of Candida-positive cultures was higher in the HIV+ subjects than in the controls (61.4%vs 24.1%, P = 0.0018). In the HIV-infected group, the unstimulated SMSL flow rates were lower in Candida-positive than in Candida-negative patients (P = 0.0158). CONCLUSION: The salivary secretion of the SMSL glands was reduced in HIV infection. Although the mucin concentration increased in HIV+ subjects, mucin secretion was not altered. Highly active antiviral therapy had no effect on salivary function. We found an association between the level of candida carriage and salivary flow rate in HIV-infected patients.

Oral mucosal conditions in elderly dental patients.

OBJECTIVES: The goals of this study were as follows: to obtain baseline information on the incidence of oral mucosal conditions in a population of elderly Thai patients and to investigate differences in the presentation of these findings in relation to age, sex and the wearing of dentures. SUBJECTS AND METHODS: The incidence of oral mucosal conditions was determined by the clinical examination of a sample of 500 Thai patients aged 60 years and older. RESULTS: The overall incidence of oral mucosal conditions was 83.6% with no significant difference between men (81.4%) and women (85%). The incidence of oral mucosal conditions indicated a significant increase with advancing age. Varices (59.6%), fissured tongue (28%) and traumatic ulcer (15.6%) were the three most common conditions; and the incidence increased with age. Leukoplakia and smoker's melanosis were more common in men whereas lichen planus was seen more frequently in women. Three cases of oral cancer were detected, representing an incidence of 0.6%. Denture wearers (62.7%) exhibited a significantly higher prevalence of oral mucosal conditions than subjects who had no dentures (28.5%) and subjects with crowns and/or bridges (8.8%). The three most common denture-related problems were traumatic ulcer (22.6%), denture stomatitis (14.3%) and angular cheilitis (4.8%). In addition, the incidence of denture-related conditions among complete denture wearers (46.3%) was higher than in those wearing partial dentures (40.8%). CONCLUSION: The current results regarding an elderly Thai population support the studies of other populations whereby the incidence of oral mucosal conditions in the elderly is related to age, sex and the wearing of dentures.

Maxillary sinus floor in edentulous and dentate patients.

To compare the depth of the maxillary sinus floor on panoramic radiographs between the edentulous and dentate patients. Thirty panoramic radiographs of edentulous female patients and 47 panoramic radiographs of female dentate patients were used for the sample. To measure the depth of the maxillary sinus floor, the outline of the maxillary sinus on the panoramic radiograph was traced on transparent paper. An apparent difference in depth of the maxillary sinus floor was recognized only in comparing the left sides of the edentulous and dentate jaws(P < 0.05). However, there was no statistical difference in the depth of the maxillary sinus floor between the right and left sides in the edentulous and dentate jaws. In this study there seems to be no difference in the depth of maxillary sinus floor between the right and left sides of either the edentulous or dentate jaws. It is not clear as to why, on the other hand, there is a statistical difference in between only the left maxillary sinus floor of the edentulous and dentate jaws, this apparent contradiction might be further investigated statistically.

Buccal and palatal exostoses: prevalence and concurrence with tori.

OBJECTIVES: The aims of this study were to investigate the prevalence and location of oral exostoses and the concurrence of buccal and palatal exostoses with tori. STUDY DESIGN: With clinical inspection and palpation, 960 Thais were examined for the presence or absence of torus palatinus (TP), torus mandibularis (TM), and exostoses. RESULTS: Of the 960 subjects studied, 26.9% exhibited exostoses. Exostoses were more common in the maxilla than in the mandible (5.1:1). In addition, most of the exostoses were located on the buccal aspect of the jaws. The prevalence of exostoses increased with age (P = .000). Exostoses were significantly more common in men than in women (62.4% vs 37.6%, P =.000). Exostoses were concurrent with TM more frequently than with TP (36.2% vs 20.6%). The highest concurrence of exostoses with tori was observed in subjects who had both TP and TM (42.6%). CONCLUSIONS: The occurrence of exostoses is related to increasing age. TM and exostoses may share the same causative factors, and functional influences may contribute. Our findings lend support to the hypothesis that the etiology of exostoses involves an interplay of multifactorial genetic and environmental factors.

Three-dimensional computed tomography imaging in dentistry.

The authors have presented several 3-D CT imaging techniques that may be useful in dentistry. MPR and dental MPR provides cross-sectional images of the jaws and the dental arches, and its utility in implant treatment planning is widely recognized. SSD allows the clinician to visualize the surface of an anatomic structure that is selected by a threshold value. Volume rendering is a powerful and flexible three-dimensional imaging technique that can create various unique images. MIP may be useful in contrast-enhanced CT examinations, such as sialography. Model production and virtual reality three-dimensional imaging may become major techniques in the near future. Although the increased radiation dose to the patients has to be considered, future imaging demands will bring more access to 3-D CT imaging by dental patients and, with adequate three-dimensional rendering techniques, more accurate diagnosis and treatment planning.

Magnetic resonance imaging in dentistry.

MR imaging has found a place in the imaging sciences. These images are unique in that no ionizing radiation is used, the same tissues may or may not have different appearances with different machine settings, a unique set of terms is used to describe the findings in the images, and these findings can be analyzed with the view of obtaining more diagnostic information not readily available with any other imaging modality. Cases have been presented to help demonstrate differences in T1-weighted and T2-weighted sequences as well as the value of contrast material. Additionally, plain film and CT views were included so that they may be contrasted with the MR images. The role and application of CT versus MR imaging has been further discussed and illustrated by Nortjé and van Rensburg. A typical temporomandibular joint case has also been presented. In the future, it is hoped that clinicians will refer more patients for MR imaging so that diagnoses can be made more accurately with analytic software.

Digital X-rays are here; why aren't you using them?

Digital imaging is here. It is cost-effective and helps dentists glean more useful information to make treatment decisions. Many more choices of digital systems are available for dentists to adopt than when the technology was introduced. The hardware is less costly than it was even one year ago, and image storage is now very inexpensive. Technical time is reduced, and no special training is required if the dentist or auxiliary has used a paralleling system. Insurance companies are gearing up to accept image files attached to claims. Why, then, are dentists not buying these systems as fast as manufacturer's can build them? This article explores that question and discusses the false assumptions behind perceived obstacles.

Panoramic radiographic patterns of the infraorbital canal and anterior superior dental plexus.

OBJECTIVE: To describe and classify the presentations of the infra-orbital canal/groove (IOC/G) complex and anterior superior dental plexus (ASDP) on panoramic radiographs. METHODS: The frequency of occurrence and variations in appearance of the IOC/G were determined on 246 random panoramic radiographs. A classification system consisting of Types I, II and III was developed to describe the radiographic patterns of the IOC/G. RESULTS: Two hundred radiographs (81.3%) demonstrated evidence of the IOG/C. The most frequent appearance of the IOC was Type III (44.75%) closely followed by Type I (42%) and Type II (13.25%), with only minor differences in prevalence between right and left sides. Sixty one percent were bilateral. Radiologic evidence of the ASDP was noted in 29% of radiographs demonstrating an IOG/C with 12% of cases being bilateral. Three distinct radiographic patterns of the anterior superior dental plexus (ASDP) were also observed. CONCLUSION: A classification of the appearance of the IOC/G and ASDP on panoramic radiographs has been presented.

Three-dimensional computed tomography evaluation of postsurgical condylar displacement after mandibular osteotomy.

OBJECTIVE: The purpose of this study was to examine both condylar displacement of the temporomandibular joint after sagittal split ramus osteotomy with rigid osteosynthesis and intraoral vertical ramus osteotomy without osteosynthesis in patients with mandibular prognathism by means of three-dimensional computed tomography. STUDY DESIGN: In this pilot study, five patients treated with sagittal split ramus osteotomy and 5 patients treated with intraoral vertical ramus osteotomy were evaluated. A technique to superimpose a postoperative three-dimensional computed tomography image on its corresponding preoperative image was designed. Postoperative condylar displacement, rotation, and tilting were measured in three-dimensional computed tomography images. RESULTS: Within 3 to 6 months after surgery, changes in the inclination of the condylar axes were distinctly seen, although changes in the position of the condyles within the joints were minimal. In particular, outward rotation of the condylar long axes after intraoral vertical ramus osteotomy was a frequent finding. CONCLUSIONS: The three-dimensional computed tomography superimposition technique was a practical method of evaluating postsurgical condylar displacement after mandibular osteotomy.

Herpes B virus infection.

Herpes B virus (B virus) infection is common in macaques. Primary infection of B virus in primates is similar to herpes simplex virus 1 infection in human beings, but B virus generally produces only mild localized lesions in its natural host. In human beings, however, B virus can cause severe infection that may lead to death from encephalitis. Contact with monkey saliva, tissues, or tissue fluids is the most commonly reported route of transmission of B virus; a single case of person-to-person transmission has been reported. Airborne transmission is postulated to have occurred as a result of clinical circumstances in two reported cases, but there is no strong evidence to support the hypothesis of aerosol infection. Because B virus infection in human beings is often fatal, awareness of the risk of B virus infection should be emphasized. Although B virus infection in human beings is rare, it is an occupational health risk in exposed health care workers and laboratory personnel. This review of the literature of B virus infection includes case reports and a discussion of the nature of the B virus, characteristics of B virus infection in primates and human beings, the treatment of human infection, and the implications for dental health care providers. This report also serves as an introduction of the disease to the dental literature.

Solitary bone cyst of the jaws: radiographic review of 44 cases.

Solitary bone cyst is a radiolucent lesion classified as a pseudocyst with a variety of reported shapes including round, oval, and irregular. In the long bones, a truncated cone shape has been described, and the fallen trabecula sign is seen in association with pathologic fracture. The purpose of this study was to classify and document the various shapes, to describe the width versus height dimensions of jaw SBCs, to determine the identifying signs of trauma, and to evaluate other reported radiographic features. Radiographs of 44 SBCs in 43 patients were studied. Sixty-four percent demonstrated the cone shape, and four subtypes of this shape were identified. Other shapes included oval (16%), irregular (16%), and round (4%). Radiographic signs of trauma were observed in 28% of the cases. No evidence of the "fallen trabecula sign" was found in this series.

Conditions peculiar to the tongue.

The tongue is the organ of taste, and it functions in speech, mastication, and the deglutition of food. This muscular organ is affected by many conditions and diseases, including a variety of developmental, traumatic, inflammatory, infectious, and neoplastic lesions.

Early pioneers of oral and maxillofacial radiology.

Because this year (1995) is the 100th anniversary of the discovery of radiography, it is appropriate that we again describe the events surrounding one of the most exciting times in our early dental x-ray history--the discovery of radiography by Roentgen and the application of radiography to the diagnosis and treatment of dental disease. Biographic sketches of some of the more prominent early pioneers in oral and maxillofacial radiology are presented, such as those of Walkhoff, Morton, Kells, Rollins, and Raper, along with a discussion of their contributions to the field.

Infection control in dental radiology.

Although exposure to blood is rare in oral and maxillofacial radiology, contact with saliva occurs. Thus the spread of infectious diseases is possible through cross-contamination, and specific infection control protocols and unit dosing of items are needed. This article outlines rationale for implementing state-of-the-art infection control procedures; and explains federal standards and guidelines with an impact on infection control and occupational safety in dental radiology procedures.

Infection control in dental radiology.

Although exposure to blood is rare in oral and maxillofacial radiology, contact with saliva occurs. Thus the spread of infectious diseases is possible through cross-contamination, and specific infection control protocols and unit dosing of items are needed. This article outlines rationale for implementing state-of-the-art infection procedures; and explains federal standards and guidelines with an impact on infection control and occupational safety in dental radiology procedures.

Risks from dental radiation in 1995.

Risks from dental radiation are primarily to the somatic tissues of exposed persons, although the genetic tissues may receive small amounts of radiation. Maximum permissible doses have been established at various levels depending on the tissue exposed and whether the exposure was occupational or non-occupational: for pregnant workers, the occupational exposure is 1/10 the normal limits. Risks from dental radiation is expressed as the number of extra fatal cancers per million exposed persons, referred to as relative risk. Generally, the relative risk is tenfold greater for the full mouth survey than for a simple panoramic radiograph. Several ways of reducing the risk, to patients as well as healthcare workers, are outlined.

Lingual cortical defect of the mandible: an unusual presentation and tomographic diagnosis.

A well-defined, bilocular radiolucency was found in the angle of the lower left mandibular ramus. The patient was asymptomatic. Serial cross-sectional tomography of the lesion revealed a lingual concavity in the mandibular cortical bone. A diagnosis of atypical Stafne's bone cavity was made.

Allergic stomatitis.

There are basically two types of hypersensitivity reactions involved in allergic stomatitis, type I immediate hypersensitivity, and type IV delayed hypersensitivity. The allergic stomatitides may present with clinical appearances that mimic classic oral vesiculobullous and ulcerative lesions. Differential diagnosis from specific mucosal diseases is important in the treatment of oral allergy. Precise history taking and the elimination of the causative agents will be necessary. The mechanisms involved in oral reactions, etiologic factors, clinical manifestations, and treatment of allergic stomatitis will be described and discussed in this article.