Relationship between Impacted Mandibular Third Molars and the Mandibular Canal on CBCT Scans

This study aimed to assess the relationship of impacted mandibular third molars with the mandibular canal on cone beam computed tomography (CBCT) scans. This cross-sectional study was conducted on CBCT scans of 137 patients with 204 impacted mandibular third molars. The relation of age, gender, class of impaction, anatomical position of canal relative to tooth (buccal, lingual, inferior, inter-radicular), tooth angulation (mesioangular, vertical, distoangular, horizontal), relationship of tooth with the mandibular canal (no contact, in contact, relation), relationship of tooth with the mandibular cortex, anatomical site of contact of tooth with the mandibular cortex (buccal, lingual, inferior), and the impression of canal (grooving, no effect) on impacted teeth were evaluated. Data were analyzed using one-way ANOVA, Chi-square test and Fisher's exact test. Class B of impaction (78.9%), inferior position of canal relative to the impacted tooth (53.9%) and mesioangular angulation (53.4%) had the highest frequency, respectively. The relationship of tooth with the mandibular canal was "relation" in most cases (53.4%) followed by no contact (26.9%) and in contact (19.6%). Significant associations were noted between depth of impaction (P < 0.001), tooth angulation (P = 0.024), anatomical position of canal relative to tooth (P < 0.001), relationship of tooth with the mandibular cortex (P = 0.032) and anatomical site of contact of tooth with the mandibular cortex (P = 0.013) with the impacted tooth-mandibular canal relationship. CBCT provides accurate information about the relationship of impacted third molars with the mandibular canal and can decrease the risk of traumatization of inferior alveolar nerve (IAN) during their surgical extraction.

The Effect of Changes in the Angular Position of Implants on Metal Artifact Reduction in Cone-Beam Computed Tomography Images: A Scoping Review

OBJECTIVE

Dental implant artifacts can compromise the quality of cone-beam computed tomography (CBCT) scans and challenge radiographic detection in surrounding regions. This literature review was conducted to examine the impact of implant angle modification on reducing metal artifacts in CBCT scans.

MATERIALS AND METHODS

A scoping review of literature was carried out in PubMed, Embase, Scopus, and Cochrane databases.

RESULTS

Different spatial planes, including alpha, beta, gamma, and phi, along with 0°, 5.2°, 9.8°, 14.5°, 15°, 30°, 45°, 60°, 75°, and 90° angles were studied. Changes in the angular position of implants may reduce metal artifacts and improve the quality of CBCT scans.

CONCLUSIONS

Rotating implants within the alpha plane and angling them at 90° in the alpha plane enables reducing dental implant artifacts.

Does the size of an object containing dental implant affect the expression of artifacts in cone beam computed tomography imaging?

Background

Artifacts fault image quality but handling several factors can affect it. This study was conducted to investigate the effect of object size on artifacts in cone-beam computed tomography systems.

Methods

Five phantoms, each containing a titanium implant in a sheep bone block, were fabricated of various sizes ranging from XS to XL: The M phantom was the same size as the device’s field of view (FOV). The L and XL phantoms were 20 and 40% larger than the FOV while the S and XS phantoms were 20 and 40% smaller than FOV, respectively. Ballistic gelatin was used to fill the phantoms. Phantoms were scanned by NewTom VGI and HDXWill Q-FACE. The mean and standard deviation (SD) of gray values in each 120 ROI was obtained by OnDemand software. The contrast to noise ratio (CNR) was also calculated.

Results

The gray value in S and M phantoms were more homogenous. The lowest SD value (10.20) was found in S phantom. The highest value for SD (125.16) was observed in XL phantom. The lowest (4.47) and highest (9.92) CNR were obtained in XL and S phantoms, respectively. HDXWill Q-FACE recorded a higher SD and a lower CNR than NewTom VGI (P < 0.05).

Conclusion

Object dimensions of the FOV size or up to 20% smaller provided better image quality. Since the dimensions of soft tissue in most patients are larger than the selective FOV, it is recommended that in CBCT artifacts studies, an object with dimensions closer to the patient’s dimensions be used to better relate the results with the clinical condition, because the sample dimensions affect the amount of artifacts.

ASSESSMENT OF OCCUPATIONAL RADIATION DOSE FROM CAMERA MODEL INTRAORAL HANDHELD X-RAY DEVICE WITHOUT STRAY RADIATION PROTECTION SHIELD

The aim of this study was to assess the occupational exposure from portable X-ray device without stray radiation protection shield measured using thermoluminescent dosemeters (TLDs). A total of 108 intraoral periapical radiographies of six sextants were performed. The TLDs were located on right index finger and left palm, between the pupils of the eyes at the edges of the Nasion point, Manubrium of Sternum bone and genital area. The detected mean doses per procedure were 70, 99, 60, 51, 51 and 58 μSv in the right finger, left palm, level of the Nasion point, under left clavicle, above the sternum manubrium and at the gonad area, respectively. Maximum number of radiographic images that the operator is allowed to perform depends on eye exposure and in accordance with International Commission on Radiological Protection is 0.16 (0.12-0.23) per hour or 1.28 (0.96-1.84) per day.

A simplified tempo-spatial model to predict airborne pathogen release risk in enclosed spaces: An Eulerian-Lagrangian CFD approach

COVID19 pathogens are primarily transmitted via airborne respiratory droplets expelled from infected bio-sources. However, there is a lack of simplified accurate source models that can represent the airborne release to be utilized in the safe-social distancing measures and ventilation design of buildings. Although computational fluid dynamics (CFD) can provide accurate models of airborne disease transmissions, they are computationally expensive. Thus, this study proposes an innovative framework that benefits from a series of relatively accurate CFD simulations to first generate a dataset of respiratory events and then to develop a simplified source model. The dataset has been generated based on key clinical parameters (i.e., the velocity of droplet release) and environmental factors (i.e., room temperature and relative humidity) in the droplet release modes. An Eulerian CFD model is first validated against experimental data and then interlinked with a Lagrangian CFD model to simulate trajectory and evaporation of numerous droplets in various sizes (0.1 μm-700 μm). A risk assessment model previously developed by the authors is then applied to the simulation cases to identify the horizontal and vertical spread lengths (risk cloud) of viruses in each case within an exposure time. Eventually, an artificial neural network-based model is fitted to the spread lengths to develop the simplified predictive source model. The results identify three main regimes of risk clouds, which can be fairly predicted by the ANN model.

Lingual Foramen of the Mandible on Cone-Beam Computed Tomography Scans: A Study of Anatomical Variations in an Iranian Population

Objectives: Lingual foramen (LF) is an important landmark of the mandible, which should be considered in presurgical assessment. The purpose of this study was to assess the anatomical variations of the LF using cone-beam computed tomography (CBCT). Materials and Methods: The study was conducted on 200 CBCT scans of Iranian adults. The lingual foramina (LFs) were classified into two groups by their location in the mandible namely the medial LFs (MLFs) and the lateral LFs (LLFs). The frequency of both the MLFs and the LLFs and their distance from the inferior border of the mandible were evaluated. Additionally, the diameter of the MLFs and the location of the LLFs were assessed. Data were analyzed separately for males and females. Results: All 200 participants had at least one LF. Totally, 257 LFs were detected on 200 CBCT scans, including 223 MLFs (86.6%) and 34 LLFs (13.3%). The LLF was detected in 23 patients (11.5%). The prevalence of the LLF was higher in males and in the second premolar region. The diameter of the MLFs was less than 1mm in 81% of the cases, and males had a larger MLF. Conclusion: There was a significant variability in the anatomy and location of the mandibular LF in Iranian adults. CBCT is recommended for preoperative imaging to determine the exact location and size of the LFs in the mandible to prevent possible surgical complications.

Prevalence of pulp stones in an Iranian subpopulation: an assessment using cone beam computed tomography

Undetected pulp stones can complicate root canal treatment. Knowledge about the prevalence of this anomaly in specific populations can improve endodontic treatment outcomes. The objective of this study was to use cone beam computed tomography (CBCT) to assess the prevalence of pulp stones in an Iranian subpopulation. In this descriptive, analytical, cross-sectional study, the CBCT scans of 150 (75 female and 75 male) patients aged 15 to 70 years were retrieved from the 2017 to 2018 archives of an Iranian university. A total of 4200 teeth were evaluated for the presence of pulp stones by a senior dental student under the supervision of an experienced oral and maxillofacial radiologist. The panoramic radiographic views were evaluated first, and then each tooth was evaluated on sagittal, coronal, axial, cross-sectional, and multiplanar views with 0.5-mm slice thickness. Data regarding the presence of pulp stones as well as the effects of age, sex, tooth type, and jaw on the presence of pulp stones were analyzed using independent t and chi-square tests. Of 4200 teeth, 571 had pulp stones, yielding prevalence rates of 13.6% in the studied teeth and 76.0% in the study population. The prevalence of pulp stones was higher in female patients, the mandible, anterior teeth, and the mandibular left quadrant. The mandibular left central incisor (tooth 24) had the highest (38.7%) and the maxillary left second premolar (tooth 13) had the lowest (1.3%) prevalence of pulp stones. The high prevalence of pulp stones in this study population suggests that dentists should consider the possible presence of pulp stones when planning endodontic treatment for Iranian patients.

Prevalence of nasal septum deviation using cone-beam computed tomography: A cross-sectional study

Background and Aim:

Nasal septum deviation (NSD) increases the chance of nasal obstruction, sinusitis, and upper airway and middle ear infections and can affect vocal cord activity, beauty, and breathing. The present study investigated the prevalence of NSD and its relation to gender, age, and history of trauma using cone-beam computed tomography (CBCT).

Subjects and Methods:

This cross-sectional study was performed on the data from CBCT examinations of 386 patients referred to two oral and maxillofacial radiology centers in Tehran, Iran, from January 2016 to January 2017. The presence of NSD and its type according to the Mladina's classification were evaluated. The effect of age, gender, and history of trauma on the prevalence of NSD was considered using a logistic regression.

Results:

86.6% (confidence interval = 0.81, 0.91) of the patients showed NSD. The prevalence was 19.4% type 1, 6.2% type 2, 20.7% type 3, 5.4% type 4, 4.4% type 5, 0.3% type 6, and 30.3% with type 7. The logistic regression indicated that the chance of deviation of nasal septum increased with age and every 10-year increase in age increased the odds of septal deviation by 0.32 (P < 0.001 and odds ratio = 1.032). Gender (P = 0.094) and history of trauma (P = 0.79) had no effects on the chance of deviation of nasal septum.

Conclusion:

This study showed that the frequency of NSD was 86.6%, with type 7 being the most common type, followed by type 3 and 1. NSD showed no association with trauma and gender, and the increase in age increases the chance of NSD.

Morphological patterns of lip prints in an Iranian population

BACKGROUND

Lip prints are verified to be unique to an individual and stable over time; hence they have potential for human identification purposes. The aim of this study was to assess the individuality and variability of lip prints in an Iranian population for the first time. We also sought to assess the possibility of sex determination via lip printing.

MATERIAL AND METHODS

Lip prints of 96 individuals including 22 males and 74 females were recorded on a plain white paper using a dark-colored lipstick and 50 mm of Scotch tape. Each lip print was divided into six sextants and studied independently by two observers using a magnifying lens to examine the lip grooves. The Suzuki and Tsuchihashi's classification was used to define the lip patterns and the data were statistically analyzed.

RESULTS

In the present study, no identically similar lip prints were observed. Type V was the most predominant pattern recorded in the study sample (33.16%), followed by type I (24.13%), type II (18.75%), type IV (11.63%), type I' (9.72%) and type III (2.60%). In addition, no statistically significant difference was observed in the lip print patterns of males and females.

CONCLUSIONS

It can be concluded that lip prints are unique and their analysis may enable human identification. Key words:Forensic anthropology, forensic dentistry, forensic medicine, iran, lip.

Effects of Different Viewing Conditions on Radiographic Interpretation

OBJECTIVES

Optimum viewing conditions facilitate identification of radiographic details and decrease the need for retakes, patients' costs and radiation dose. This study sought to evaluate the effects of different viewing conditions on radiographic interpretation.

MATERIALS AND METHODS

This diagnostic study was performed by evaluating radiograph of a 7mm-thick aluminum block, in which 10 holes with 2mm diameters were randomly drilled with depths ranging from 0.05 mm to 0.50mm. The radiograph was viewed by four oral radiologists independently under four viewing conditions, including a white light viewing light box in a lit room, yellow light viewing light box in a lit room, white light viewing light box in a dark room and yellow light viewing light box in a dark room. Number of circular shadows observed on the film was recorded. The data were analyzed by two-way ANOVA.

RESULTS

The mean number of detected circular shadows was 6.75, 7.5, 7.25 and 7.75 in white light viewing light box in a lit room, white light viewing light box in a dark room, yellow light viewing light box in a lit room and yellow light viewing light box in a dark room, respectively. Although the surrounding illumination had statistically significant effect on the radiographic details (P≤0.03), the light color of the viewing light box had no significant effect on visibility of the radiographic details.

CONCLUSION

White and yellow light of the viewing light box had no significant effect on visibility of the radiographic details but more information was obtained in a dark room.

Relationship between carotid artery calcification detected in dental panoramic images and hypertension and myocardial infarction

BACKGROUND

Carotid artery calcification may be related to cerebrovascular accident, which may result in death or physical and mental disabilities in survivors.

OBJECTIVES

Our purpose is to study the association of carotid artery calcification (CAC) on dental panoramic radiographs and two risk factors of cerebrovascular accident (CVA) including hypertension and myocardial infarction (MI).

PATIENTS AND METHODS

Panoramic images of 200 patients that were all women above 50 years of age (a population suffering from vascular diseases) were investigated. All panoramic images were provided under similar conditions in terms of the type of panoramic radiograph equipment, type of applied films and the automatic film processor. Then, the patients answered questions about MI history and taking antihypertensive drugs. We also measured the blood pressure of patients in two separate surveys. Data analysis was performed by SPSS statistical program. We used Exact Fisher test and Chi-Square test at a significant level of less than 0.05 to study the effect of these variables on the occurrence of carotid artery calcification.

RESULTS

Among 200 studied samples, 22 of the patients (11%) had carotid artery calcification on the dental panoramic radiograph. In total, 52 patients (26%) had hypertension and four people (2%) had a history of MI. Eleven individuals among patients suffering from hypertension (21.2%) and three individuals among patients with a history of MI (75%) demonstrated CAC on dental panoramic images .

CONCLUSIONS

The relationship between CAC found on dental panoramic radiographs and two CVA risk factors--hypertension and MI-- was significant. Therefore, it seems that detection of CAC on panoramic images of dental patients must be considered by dentists.

Radiologic assessment and frequency of idiopathic osteosclerosis of jawbones: an interpopulation comparison

BACKGROUND

Idiopathic osteosclerosis is a localized growth of compact bone with an unknown cause. This asymptomatic lesion is an insignificant finding and as such requires no treatment. It should be distinguished from other types of osteosclerosis created by inflammatory processes and systemic diseases.

PURPOSE

To determine the prevalence and distribution of idiopathic osteosclerosis in the jawbones in Iran and to compare this prevalence and distribution with other populations.

MATERIAL AND METHODS

This cross-sectional descriptive study was performed in the Dental School of Shahid Beheshti University of Medical Sciences, Tehran, between 2010 and 2011. Data were collected from the files of patients who underwent panoramic radiography for dental treatment. Location, shape, and relation between idiopathic osteosclerosis and the tooth as well as the resorption of the tooth involved were evaluated. Lesion distribution regarding age, gender, localization, shape, dental relationship, and root resorption was assessed using the chi-squared test.

RESULTS

In total, 787 panoramic radiographs of 456 women and 331 men were assessed. Idiopathic osteosclerosis was detected in 75 (9.5%) patients. The prevalence of idiopathic osteosclerosis was significantly higher in the women (11.8% vs. 6.3%; P < 0.01). The mean age of the patients with idiopathic osteosclerosis was 31.9 ± 17.9 years and 30.8 ± 13.3 years in the patients without idiopathic osteosclerosis. The distribution of idiopathic osteosclerosis in the mandible (97.3%), mostly in the premolar region, was significantly higher than that in the maxilla (2.7%).

CONCLUSION

Our results showed high frequencies of idiopathic osteosclerosis in Iran in comparison to some other countries.

Correlation between symphyseal morphology and mandibular growth

Background:

This study sought to assess symphyseal morphology in adolescents with different mandibular growth patterns (MGPs) in order to see if a relation exists.

Materials and Methods:

In this study the symphyseal parameters (height, depth, and ratio) of normal subjects were compared with four groups with malocclusion (cl III vertical, cl II vertical, cl III horizontal, and cl II horizontal). These groups (15 samples each) were matched (for sex and cervical maturation stage [CVMS]) based on their cephalograms and patient charts. Growth patterns were differentiated by seven vertical parameters and the Wylie analysis. After confirmation of normality of the groups and similarity of their variances the two-way analysis of variance (ANOVA) was used for analysis of data assessed by adjusted chi-square (P < 0.001). The comparison of cases with the normal group was performed by the Dunnett method. Intraclass Correlation Coefficient (ICC) was used for evaluation of intraobserver reliability.

Results:

We found the symphyseal ratio to have a significant correlation with the MGP (P < 0.001). The symphyseal ratio (Height/Depth) was small in a mandible with vertical growth pattern Cl II or Cl III. Conversely, a horizontal growth pattern of a Cl II or Cl III mandible was associated with a larger ratio of the symphysis in comparison with the normal group. The symphyseal ratio was also found to be greater in females.

Conclusion:

The symphyseal ratio was found to be strongly associated with the MGP.

Predicting mandibular growth increment on the basis of cervical vertebral dimensions in Iranian girls

BACKGROUND

The purpose of this longitudinal study was to establish an equation to predict incremental mandibular length on the basis of the analysis of the cervical vertebrae on a single cephalometric radiograph and to compare the predictive accuracy with the method by Mito et al.

METHODS

Data consist of a group of 33 Iranian girls, 9 to 11 years old with two lateral cephalometric radiographs taken at a 24-month interval. For each individual, on the lateral cephalometric radiographs, points and lines for the description of the morphologic characteristics of the third and fourth cervical vertebral bodies were traced and measured. The real mandibular length increment (MLI) in this period was determined by the difference between the second (24 months) and first (baseline) radiographs: MLI=Ar-Pog (second)-Ar-Pog (first). An equation was determined to calculate mandibular length increments on the basis of the measurements in the third and fourth cervical vertebral bodies. The predictive accuracy was assessed using multiple regression analysis.

RESULTS

The adjusted R2 for this equation was 54.9% which is a reliable value for evaluating prediction accuracy .The average error between the predicted increment and the actual increment was 0.149 mm for our method and 5.87 mm for the method by Mito et al.

DISCUSSION

There are two items that contributed to easier and better prediction accuracy in our equation: (1) higher R2 and (2) fewer independent variables. In our subjects, the prediction accuracy was lower when using Mito et al.'s method, which could be due to genetic and environmental factors and selected age range.

CONCLUSION

These results indicate that cervical vertebral measurements, obtained in lateral cephalograms, are able to predict properly the mandibular growth potential.

Conventional versus digital radiography in detecting root canal type in maxillary premolars: an in vitro study

OBJECTIVE

Successful endodontic therapy depends on adequate mechanical and chemical debridement of the canal which requires knowledge of the canal morphology. Conventional radiography has been used to evaluate the canal type; however, direct digital radiography has recently been practiced for this purpose due to the shortcomings of conventional radiography. The aim of the present study was to compare the accuracy of digital and conventional radiography taken at 0° and 30° angles in the diagnosis of the canal type of extracted maxillary premolars.

MATERIALS AND METHODS

This diagnostic study was performed on 90 extracted maxillary premolars. Conventional and digital radiographies were taken of all teeth at 0° and 30° horizontal angles. The images were assessed by an oral and maxillofacial radiologist. The clearing technique was used as the gold standard. The canal type was determined using Weine classification. The agreement between each one of the 4 radiographic modalities and gold standard was determined by kappa statistics.

RESULTS

The kappa values for the agreement of parallel conventional, 30° conventional, parallel digital and 30° digital modalities with the clearing technique were 0.059, 0.215, 0.043 and 0.391, respectively. Parallel modalities were unable to determine the tooth canal type. Radiographic images taken at 30° significantly determined the canal type, although only a poor level of agreement was noted between the two modalities and the clearing technique.

CONCLUSION

All modalities had limited value to determine the root canal type in maxillary premolars. However, direct digital imaging taken at 30° angle showed the highest accuracy for canal type assessment.

Analysis of linear measurement accuracy obtained by cone beam computed tomography (CBCT-NewTom VG)

BACKGROUND

One of the major uses of cone beam computed tomography (CBCT) is presurgical implant planning. Linear measurement is used for the determination of the quantity of alveolar bone (height and width). Linear measurements are used in orthodontic analysis and definition of jaw tumor size. The objective of this study is to evaluate the accuracy of the linear measurement of CBCT (Newtom VG) in the axial and coronal planes, with two different voxel sizes.

MATERIALS AND METHODS

In this accuracy diagnostic study, 22 anatomic landmarks in four dry human skulls were marked by gutta-percha. Fifteen linear measurements were obtained using a digital caliper. These were considered to be the gold standard (real measurement). The skulls were scanned by CBCT (Newtom VG) at two settings: (a) Voxel size 0.3 mm (b) voxel size 0.15 mm High Resolution (HR). The radiographic distance measurements were made in the axial and coronal sections by three observers. The radiographic measurements were repeated two weeks later for evaluation of intraobserver reliability. SPSS software version 17 was used for data analysis. The level of significance was considered to be 5% (P ≤ 0.05).

RESULTS

The mean differences of real and radiographic measurements were -0.10±0.99 mm in the axial sections, -0.27±1.07 mm in the coronal sections, +0.14±1.44 mm in the axial (HR) sections, and 0.02±1.4 mm in the coronal (HR) sections. The intraclass correlation (ICC) for CBCT measurements in the axial sections was 0.9944, coronal sections 0.9941, axial (HR) sections 0.9935, and coronal (HR) sections 0.9937. The statistical analysis showed high interobserver and intraobserver reliability (P ≤ 0.05).

CONCLUSION

CBCT (Newtom VG) is highly accurate and reproducible in linear measurements in the axial and coronal image planes and in different areas of the maxillofacial region. According to the findings of the present study, a CBCT scan with a larger voxel size (0.3 mm in comparison to 0.15 mm) is recommended when the purpose of the CBCT scan is to measure linear distances. This will result in lower patient radiation dose and faster scan time.

Oro-facial manifestations of 100 leprosy patients

Objectives: To verify the frequency of oral and facial involvement in diagnosed leprosy patients. Study design: This study was performed on 100 leprosy patients (62 male, 38 female, mean ages 51.86±6.1). After explaining the study design, we studied descriptive information including: patient’s sex, age, job, place of birth, familial history of leprosy, types of disease (lepromatous, borderline and tuberculoid leprosy), ocular and oral lesions, facial involvement and neuropathy. The statistical signification was measured by chi-square test. Results: A total of 46 (23 lepromatous, 15 borderline, and 8 tuberculoid leproy) out of 100 patients with leprosy had oral lesions. Statistical analysis did not show any significant difference in frequency of oral lesions between different types of disease. Facial lesions were presented in 57 (39 lepromatous, 10 borderline, and 8 tuberculoid leprosy) patients. There was a statistical significant difference in frequency of facial manifestations between different types of leprosy. It has to be mentioned that, atrophy of nasal spine, facial nerve involvement, ocular lesions and facial deformity were seen in 15%, 17%, 22% and 44% of leprosy patients, respectively. Conclusion: Examination of leprosy patients should be extended to the oral mucosa because oral mucosa may be a secondary source of M.Leprae transmission and infection.

Key words:Leprosy, lepromatous, tuberculoid, oral lesions, facial lesions.

Prevalence of calcified carotid artery on panoramic radiographs in postmenopausal women

BACKGROUND AND AIMS

This study was designed to evaluate the prevalence of calcified carotid artery in 50 year-old and older postmenopausal dental outpatients for early diagnosis of individuals at risk of stroke.

MATERIALS AND METHODS

This is a descriptive study of 200 panoramic radiographs. These radiographs included post-menopausal women referring to the Department of Oral Medicine at Shahid Beheshti Faculty of Dentistry during 2006-2007. The x-ray machine, developer and film type were the same for all the radiographs. Statistical analysis included chi-square test and Fisher's exact test.

RESULTS

We found 22 calcified carotid arteries. The left and right carotid arteries were involved in 7 and 9 cases, respec-tively. In 6 cases both carotid arteries were calcified. Four individuals had no vascular risk factor excluding age and others had at least one risk factor. We found significant statistical correlation between hypertension, past history of myocardial infarction, and hypercholesterolemia with calcified carotid artery on panoramic radiographs.

CONCLUSION

Under the limitations of the present study, prevalence of calcified carotid arteries is 11.0 % in 50 year-old and older postmenopausal dental outpatients.

Therapeutic approaches for AIDS-related toxoplasmosis

OBJECTIVE

To summarize current knowledge of prophylaxis and treatment of AIDS-related toxoplasmosis.

DATA SOURCES

A MEDLINE search (1985-1994) was used to identify pertinent literature, including reviews.

STUDY SELECTION AND DATA EXTRACTION

All articles were considered for possible inclusion in the review. Pertinent information, as judged by the authors, was selected for discussion.

DATA SYNTHESIS

Trimethoprim/sulfamethoxazole (TMP/SMX) appears to be useful for prophylaxis against toxoplasmosis in patients with AIDS. The most effective TMP/SMX dose for prevention of toxoplasmosis needs to be determined. Dapsone in combination with pyrimethamine therapy may be an effective alternative for toxoplasmosis prophylaxis. The most effective regimen for the treatment of AIDS-related toxoplasmosis is the combination therapy of pyrimethamine/sulfadiazine. In patients who cannot tolerate sulfadiazine therapy because of adverse effects or allergy, pyrimethamine with clindamycin therapy may be considered as a second-line alternative. Lifelong suppressive therapy is required after either treatment regimen to prevent relapse. Other newer agents such as azithromycin, clarithromycin, atovaquone, or timetrexate-leucovorin need further studies to confirm their true effectiveness in the treatment of toxoplasmosis.

CONCLUSIONS

TMP/SMX remains a useful agent in prophylaxis against toxoplasmosis. Pyrimethamine/sulfadiazine is the most effective combination in the treatment of acute toxoplasmosis.

Three-dimensional elastic matching of volumes

Registering volumes that have been deformed with respect to each other involves recovery of the deformation. A 3-D elastic matching algorithm has been developed to use surface information for registering volumes. Surface extraction is performed in two steps: extraction of contours in 2-D image planes using active contours, and forming triangular patch surface models from the stack of 2-D contours. One volume is modeled as being deformed with respect to another goal volume. Correspondences between surfaces in the two image volumes are used to warp the deformed volume towards its goal. This process of contour extraction, surface formation and matching, and warping is repeated a number of times, with decreasing image volume stiffness. As the iterations continue the stretched volume is refined towards its goal volume. Registration examples of deformed volumes are presented.

Ciprofloxacin-induced toxic epidermal necrolysis

OBJECTIVE

To report a case of probable ciprofloxacin-induced toxic epidermal necrolysis (TEN) in an adult with systemic lupus erythematosus (SLE).

CASE SUMMARY

A 31-year-old woman with SLE developed a pruritic rash following her first dose of oral ciprofloxacin. She continued taking ciprofloxacin, and the rash progressively worsened, becoming painful and covering her entire body. She discontinued the ciprofloxacin six days later and presented to the hospital, where two days later, her rash began to desquamate with epidermal erosions and a positive Nikolsky's sign. Skin biopsy was positive for TEN. She then was transferred to a burn-treatment unit because of the severity of the skin involvement. The patient recovered following prolonged hospitalization and rehabilitation.

CONCLUSIONS

Although TEN occurs rarely with ciprofloxacin, extensive postmarketing surveillance needs to be performed to determine other risk factors for its development and to establish the incidence of TEN and other severe cutaneous reactions caused by ciprofloxacin or the other fluoroquinolones.

Directional interpolation for magnetic resonance angiography data

Interpolation is a necessary step in magnetic resonance (MR) angiography when the center-to-center spacing between the MR slices is larger than the in-plane pixel size of the slices. Conventional methods interpolate normal to the slice only, causing a staircase artifact for oblique vessels. Reconstructions of these vessels demonstrate jagged structures with reduced resolution and contrast. A directional interpolation scheme is presented here, in which the orientation of interpolation is determined locally by template matching. By aligning this orientation with the vessels, the algorithm reconstructs the correct shape and contrast for oblique vessels. Simulations and application of the algorithm to clinical MR angiography data demonstrate the advantages of directional interpolation over conventional methods. Examples are shown of combining the algorithm with background suppression, where the background values in the slices are suppressed prior to projection and directional interpolation. This results in even higher vessel-to-background contrast.