Mucoepidermoid carcinoma in the mandible: Findings of panoramic radiography and computed tomography

Six patients with mucoepidermoid carcinoma in the mandible were studied with both panoramic radiography and computed tomography. Lesion shape and margin were evaluated on panoramic radiography, and bony expansion and cortical plate destruction were evaluated on computed tomography. In addition, a possible correlation among radiographic findings, histologic findings, and prognosis was investigated. Lesions found on panoramic radiography were classified into three types; each type pertained to two of the six patients. The lesion types were as follows: cystic, characterized by a large, cystic radiolucent area; rarefying, characterized by rarefying changes of the trabeculae; and infiltrative, characterized by a central ill-defined area of bony destruction. The results show that computed tomography is useful in the identification of tumor extent, bony expansion, and cortical plate destruction resulting from tumors. None of the patients whose lesions were of the cystic or rarefying type showed evidence of disease after surgery. In contrast, both of the patients whose lesions were of the infiltrative type died of their tumors. Histologic findings of the cystic and rarefying types showed tumors that were well-differentiated or moderately well-differentiated, whereas findings of the infiltrative type showed poorly differentiated tumors. Radiographic findings correlated with histologic findings and prognosis of mucoepidermoid carcinoma in the mandible in this limited series.     

Use of an inclined footrest for panoramic dental radiography.

An inclined footrest was evaluated as a positioning aid for dental panoramic radiography. Experimental and control groups of students were examined by a conventional panoramic technique, with and without the addition of an inclined footrest. All radiographs obtained were evaluated for six parameters in a single-blind fashion by three dentists. Results indicated that the inclined footrest reduced spinal-shadow artifacts and improved over-all image quality.     

Early microbial colonization of permucosal implants in edentulous patients

In edentulous patients, the microbial colonization of permucosal implants of sintered hydroxyapatite was studied. Samples were taken from mucosa and dentures before insertion of implants and from supra- and subgingival sites two to 10 weeks after insertion. In total, five patients and 10 implants with clinically healthy peri-implant tissues were studied. The samples were investigated by dark-field microscopy and anaerobic culture. The supragingival plaque of the implants was dominated by Gram-positive cocci and rods, the subgingival plaque by Haemophilus spp. and Veillonella parvula. A group of bacteria was found specifically related to the implants: Actinomyces odontolyticus, Peptostreptococcus micros, Haemophilus actinomycetemcomitans, Eikenella corrodens, Capnocytophaga sputigena, and Leptotrichia buccalis. Black-pigmented Bacteroides was not found in any of the examined samples. Spirochetes were observed in denture plaque samples and in supragingival plaque of the implants. It is concluded that bacteria known as potential periodontal pathogens colonize the permucosal implants in the first weeks after insertion. The presence of these species seems to be dependent on the ecological factors provided by the artificial gingival crevice of the permucosal implants in the edentulous mouth.     

Diagnostic imaging of diseases affecting the mandible with the use of computed panoramic radiography

Computed panoramic radiography was performed on patients with bone cyst, osteomyelitis, gingival cancer, and fibrous dysplasia, respectively, to determine the best imaging procedure for disease processes affecting the mandible. Gradational enhancement images for detection of density changes and frequency enhancement images for detecting changes in the margin and texture were effective in aiding the diagnosis of diseases of the mandible with the use of computed panoramic radiography.     

Success of implants in the moderately resorbed edentate maxilla

In applications of implants in the moderately resorbed maxilla factors such as bone quantity and the loading of the bone are of importance for the prognosis. Long-term studies have shown that for the maxilla the results were less good than for the mandible. The main reason for this is the condition of the bone, especially reduced bone quantity together with a thin corticalis an low bone density. Beside these factors there are also the general negative factors such as rheumatoid arthritis, osteoporosis, smoking and radiotherapy. The prognosis of implant supported prostheses is not primarily determined by the number of implants, but by the condition of the bone and to some extent by the splinting effect of the implants.     

Evaluation of two methods of tracings for implants in panoramic radiographs

In the last years, computer programs have appeared in order to help dental practitioners in implants planning. These programs aim to facilitate the acquisition of adequate measures in digitalized radiographs. The aims of this study were: to evaluate the intra-examiner agreement in the acquisition of measures using two methods (manual and computer program - Radioimp), comparing their performances. Three examiners analyzed twenty-one panoramic radiographs. They used the two methods in two occasions. In the manual method, the examiners made a tracing on a paper fixed to the images and measured nine regions with a caliper. The images were digitalized and showed in a computer screen to be analyzed in the computer program. The examiners acquired measures of the same regions by the manual method. Vertical measures of spheres in the images were acquired in order to discount the magnifying factor of the technique. Through statistics analysis (p=.05), it was possible to conclude that there were differences in intra-examiner agreement and the examiners had greater difficulty in reproducing the measures when they used the computer program; the measures acquired by the manual method were closer to the real ones.     

Radiation exposure during panoramic radiography in children.

In an effort to determine the amount of radiation exposure a child receives during a panoramic radiograph and to evaluate the effect of a protective thyroid collar, dosimeter readings were made on twenty-nine child patients at fourteen anatomic sites. The levels of radiation recorded were similar to those previously recorded for adults and phantoms, except for greater doses in the thyroid area. Placement of a lead-lined thyroid collar resulted in significant reduction of the thyroid doses.     

Research methods in dentistry. 8. Methods for longitudinally detecting differences in bone density: digital subtraction radiography

Subtraction radiography has been developed in 1934 by the Dutch radiologist B. Ziedses des Plantes. The technique is based on the subtraction of two radiographic images. As a result, only the differences remain visible, and structures which have been unaltered in between both exposures, are suppressed. The technique was introduced also in dental radiology in the eighties in the last century. Since then, many studies have been performed showing the benefit of this technique in dental diagnosis. A requirement for reliable results is that the two radiographs which are used for the subtraction have equal brightness and contrast, as well as a completely identical projective geometry. Since radiographic images can be acquired digitally, methods have been developed to make density and contrast equal for both images used for the subtraction process even after the images have been taken, using dedicated software programs. The projection geometry of two images can be made identical in this way as well. Because of this, the technique can also be applied in general dental practice.     

Aspects of panoramic radiography in general dental practice.

OBJECTIVES: To gather information on the types of panoramic x-ray equipment used in NHS dental practice and whether dentists satisfy the legal requirements for safety, to determine which practice personnel take panoramic radiographs and to assess the prevalence of the practice of 'routine' panoramic radiography among NHS dentists. DESIGN: Postal questionnaire survey of general dental practitioners carried out during 1997 in selected FHSAs in England and Wales. RESULTS: 542 dentists returned the questionnaire, a 73.3% response. Panoramic x-ray equipment ranged in age from 27 years old to new, with 42.2% exceeding 10 years in age. The overwhelming majority of GDPs satisfied the requirement for regular maintenance and surveying of equipment. Almost all dentists (95.9%) performed a history and clinical examination prior to panoramic radiography but 42% practised 'routine screening' of new adult patients. A substantial proportion (36.7%) of dentists used unqualified personnel to take panoramic radiographs. CONCLUSIONS: While some aspects of this study give reassurance about the prevalence of good practice, widespread panoramic screening and using unqualified staff to take radiographs causes concern. These findings have implications for educators and for those involved in maintaining clinical standards.     

Assessment of vertical facial and dentoalveolar changes using panoramic radiography

The purpose of the study was to analyse longitudinal vertical facial and dentoalveolar changes using panoramic radiographs (PRs) and to compare the results with measurements on lateral cephalometric radiographs (LCRs) in order to determine whether, under certain circumstances, the radiation dose for a patient may be reduced by taking only a PR instead of a PR and a LCR. Pre- and post-treatment PRs and LCRs of 30 (15 females and 15 males) orthodontically treated adolescents (mean age pre-treatment 10.9 years, post-treatment 13.4 years) were analysed using Pearson's correlation coefficients and gender differences using Fisher's z-transformation. The results revealed that most variables exhibited larger absolute values on PRs than on LCRs. Comparison of dentoskeletal morphology between the LCRs and the PRs revealed moderate to high, mostly statistically significant, interrelations both before and after orthodontic treatment. The lowest correlations were found for the maxillary jaw base angle (NL/H; r= 0.35***) and the highest for the gonial angle (ML/RL; r = 0.90***). However, when assessing the combined growth and treatment changes from before to after treatment, only weak to moderate, not statistically significant, interrelations were found between LCRs and PRs. Anterior face height (AFH; r = 0.43***), the mandibular plane angle (ML/H; r = 0.06*), and the distance of the incisal tip of the most extruded mandibular incisor to the ML-line (ii-ML; r = -0.21*) were the only statistically significant parameters. The average group differences for growth and treatment changes, however, were small for most parameters. Analysis of vertical facial and dentoalveolar parameters on PRs delivers a moderate approximation to the situation depicted on LCRs. However, PRs cannot be recommended for the analysis of individual longitudinal changes in vertical facial and dentoalveolar parameters.     

Diagnostic charting of panoramic radiography using deep-learning artificial intelligence system

Oral Radiology - The goal of this study was to develop and evaluate the performance of a new deep-learning (DL) artificial intelligence (AI) model for diagnostic charting in panoramic radiography....     

Patient satisfaction with different types of implant-retained overdentures in the edentate mandible

The purpose of this study was to determine patient satisfaction with implant supported mandibular overdentures using magnet, bar-clip and ball-socket attachments, and to assess the relation between maximum bite force and patient satisfaction. In a crossover clinical trial, 18 edentulous patients with lower denture complaints received 2 mandibular implants and new lower and upper dentures. The lower denture initially came without any kind of attachment system, but was fitted with one of the attachment types after 3 months. The attachments were changed 3 months thereafter, in random order. A questionnaire concerning denture complaints was given at baseline (with the old denture), after 3 months of functioning with the new denture without attachments and after 3 months of functioning with each of the attachments (within-subject comparison). In addition, at the end of the experiment patients were asked to express their overall satisfaction with their dentures on a visual analogue scale (VAS). Data regarding maximum bite force were obtained from a previous study with the same population. Mandibular implant supported overdenture treatment reduced various denture complaints. The VAS score reflected patients' preference more accurately than scale-scores. Patients strongly preferred bar-clip (10 subjects) and ball-socket attachments (7 subjects) over magnet attachments (1 subject). Patients' preference could not be predicted on the basis of baseline observations. Maximum bite force was not correlated to scale- or VAS scores.     

Soft tissue calcifications in the differential diagnosis of opacities superimposed over the mandible by dental panoramic radiography

Not all opacities observed on panoramic dental radiographs are associated with the jaws. Two thousand six hundred and twenty-eight panoramic radiographs obtained from a single dental health clinic were evaluated for the presence of opacities associated with the mandible. Opacities were observed in 4 per cent of cases. The radiographic features of these opacities are presented. The importance of including soft tissue calcifications which may be superimposed over the mandible on panoramic views in the differential diagnosis is discussed. Information on the various soft tissue calcifications which can occur in this region is presented.     

A general mathematical theory of rotational panoramic radiography incorporating non-rotational scanographic methods

In the present paper a general and exact theory is presented that is valid for rotational panoramic radiography irrespective of the projection geometry and that incorporates non-rotational scanographic methods. The general theory includes as a special case the conventional approximate theory of the working principle of panoramic radiography. Complete analytical mathematical expressions including no approximations are derived for motion unsharpness and the geometrical properties of the panoramic image. Such exact expressions for motion unsharpness do not appear in the literature previous studies having made extensive use of approximations. This work was performed while Dr. Masaru Shiojima, Department of Oral Radiology, Aichi-Gakuin University, Nagoya, Japan, was a visiting professor at the Department of Oral Radiology, University of Umea, Umea, Sweden Retired June 30, 1990. Director from July 1 Prof. Ulf Welander     

Immediate occlusal loading of implants in the partially edentate mandible: a prospective 1-year radiographic and 4-year clinical study

PURPOSE: The purpose of the present prospective clinical study was to evaluate the radiographic and clinical outcome of immediately loaded implants in the partial edentulous mandible over a 4-year follow-up period using a modified surgical protocol, primary implant stability criteria, and splinting for inclusion. MATERIALS AND METHODS: Patients in need of implant treatment in the partial edentate mandible were consecutively included in the study. The implant sites were underprepared to obtain maximal stability. Inclusion criteria for the study were torque of a least 30 Ncm before final seating of the implant and an ISQ greater than 60. A provisional fixed partial denture was delivered within 24 hours and a definitive fixed partial denture within 3 months. The patients were monitored with clinical and radiographic follow-up examinations for up to 4 years. Stability of the implants was measured with resonance frequency analysis at placement and after 6 months. RESULTS: Ninety-six patients were evaluated, and 77 patients who met the inclusion criteria were included. A total of 111 fixed partial dentures supported by 257 Br?nemark System implants (77 turned and 180 TiUnite implants) were delivered. Four (1.6%) of the 257 implants did not osseointegrate, giving an overall survival rate of 98.4% after 4 years. Three turned (3.9%) implants and 1 oxidized implant (0.6%) failed after 4 to 13 months. The average marginal bone resorption was 0.7 mm (SD 0.78) during the first year in function. Turned implants showed an average bone loss of 0.5 mm (SD 0.8) and oxidized implants an average of 0.7 mm (SD 0.8). Resonance frequency analysis showed a mean implant stability quotient of 72.2 (SD 7.5) at placement and 72.5 (SD 5.7) after 6 months of loading. CONCLUSION: It is concluded that immediate loading of implants with firm primary stability in partially edentulous areas of the mandible appears to be a viable procedure with predictable outcome.     

Fine-detail panoramic radiography by free-focus radiography. A clinical demonstration of diagnostic radiographs

Previous comprehensive clinical studies have shown that free-focus radiography (FFR) may be used to improve image detail and diagnostic value in panoramic radiography of the teeth and jaws. This study demonstrated the clinical image quality in fine-detail panoramic FFR surveys relative to conventional surveys made by rotational panoramic or intraoral radiography. Cases of particular diagnostic interest with respect to common dental disease and changes in the jaws were included. The radiographic area of diagnostic interest depicted in FFR surveys generally resembled that of conventional dental radiographic surveys with the use of intraoral films rather then those of conventional rotational panoramic surveys.     

Third molar position: reliability of panoramic radiography.

PURPOSE: The purpose of the present study was to determine whether panoramic radiographs could predict physical contact between the mandibular third molar and the mandibular canal on limited cone-beam computed tomography, known as dental 3D-CT (3-dimensional computed tomography [3D-CT]). PATIENTS AND METHODS: The association of images between the panoramic radiograph and the dental 3D-CT was investigated in a cross-sectional study. Seventy-three lower third molars in 65 patients were examined. Findings of absence or presence of the white line of the mandibular canal wall on panoramic radiographs and contact or separation between the tooth and the mandibular canal on dental 3D-CT were compared. RESULTS: Absence of a superior white line on panoramic radiography was associated with an increased risk of contact between the third molar and the mandibular canal on dental 3D-CT, even when the effects of tooth position, age, and gender were taken into account. The multivariate adjusted odds ratio was 10.79. Women were more likely to have contact between the 2 structures on dental 3D-CT when their panoramic radiograph showed absence of the white line. CONCLUSIONS: Panoramic radiography is useful for predicting to a limited extent physical contact between the mandibular third molar and the mandibular canal on dental 3D-CT.