Intraoral radiography and dental implant restoration.

The usefulness of IOR has been described along with its limitations when considering implant restorations. One major issue is the alignment of the incident x-rays so that they are consistently perpendicular to the implant body, to provide the most reliable information possible. Other limitations include inconsistencies as a result of the inability to verify the nature and extent of bone around an implant, which is subject to variation as a result of type of bone and site. Where implants are concerned, as a diagnostic tool IOR should be considered as part of a multitude of tests-including probing, mobility, symptoms, and other soft-tissue evaluations. It must be emphasized that IOR cannot be relied upon as being the sole diagnostic test.

Evaluating craniofacial asymmetry with digital cephalometric images and cone-beam computed tomography.

INTRODUCTION: The aim of this study was to evaluate craniofacial asymmetry by using 2-dimensional (2D) posteroanterior cephalometric images, 3-dimensional cone-beam computed tomography (CBCT), and physical measurements (gold standard). METHODS: Ten dry human skulls were assessed, and radiopaque markers were placed on 17 skeletal landmarks. Twenty linear measurements were taken on each side to compare the right and left sides and to compare these measurements with the physical measurements made with a digital caliper. To acquire the 2D posteroanterior radiographs, an Extraoral Phosphor Storage Plate (Air Techniques, Chicago, Ill) was used as the image receptor with a Eureka x-ray-Duocon Machlett unit (Machlett Laboratores, Chicago, Ill). Three-dimensional imaging data were acquired from a CB MercuRay (Hitachi Medical, Tokyo, Japan). RESULTS: On average, the right side was larger than the left for most of the 20 distances evaluated in the digital 2D and the CBCT images, and there was poor agreement between the digital 2D images and the physical measurements (kappa = 0.0609) and almost perfect agreement (kappa = 0.92) between the CBCT and physical measurements when individual measurements were considered. CONCLUSIONS: Human skulls, with no apparent asymmetry, had some differences between the right and left sides, with dominance for the right side but with no clinical significance. CBCT can better evaluate craniofacial morphology when compared with digital 2D images.

A descriptive study of the radiographic density of implant restorative cements.

STATEMENT OF PROBLEM: Cementation of implant prostheses is a common practice. Excess cement in the gingival sulcus may harm the periodontal tissues. Identification of the excess cement may be possible with the use of radiographs if the cement has sufficient radiopacity. PURPOSE: The purpose of this study was to compare the radiographic density of different cements used for implant prostheses. MATERIAL AND METHODS: Eight different cements were compared: TempBond Original (TBO), TempBond NE (TBN), Fleck's (FL), Dycal (DY), RelyX Unicem (RXU), RelyX Luting (RXL), Improv (IM), and Premier Implant Cement (PIC). Specimen disks, 2 mm in thickness, were radiographed. Images were made using photostimulable phosphor (PSP) plates with standardized exposure values. The average grey level of the central area of each specimen disk was selected and measured in pixels using a software analysis program, ImageTool, providing an average grey level value representative of radiodensity for each of the 8 cements. The radiodensity was determined using the grey level values of the test materials, which were recorded and compared to a standard aluminum step wedge. An equivalent thickness of aluminum in millimeters was calculated using best straight line fit estimates. To assess contrast effects by varying the exposure settings, a second experiment using 1-mm-thick cement specimens radiographed at both 60 kVp and 70 kVp was conducted. The PSP plates with specimens were measured for a grey level value comparison to the standard aluminum step wedge, using the same software program. RESULTS: The highest grey level values were recorded for the zinc cements (TBO, TBN, and FL), with the 1-mm specimen detectable at both 60- and 70-kVp settings. A lower grey level was recorded for DY, indicative of a lower radiodensity compared to the zinc cements, but higher than RXL and RXU. The implant-specific cements had the lowest grey level values. IM could only be detected in 2-mm-thick sections with a lower aluminum equivalence value than the previously mentioned cements. PIC could not be detected radiographically for either the 1-mm or 2-mm thicknesses at either of the kVp settings. CONCLUSIONS: Some types of cement commonly used for the cementation of implant-supported prostheses have poor radiodensity and may not be detectable following radiographic examination.

Bone volume, tooth volume, and incisor relapse: a 3-dimensional analysis of orthodontic stability.

INTRODUCTION: Orthodontic relapse is a common and significant problem. Few risk factors have been identified, and the role of bone has only recently been investigated. The purpose of this study was to examine the influence of alveolar bone volume and tooth volume on dental relapse. METHODS: The sample was chosen from the postretention database at the Department of Orthodontics of the University of Washington in Seattle. Based on the 10-year postretention (T3) irregularity index (II), 40 relapse subjects (T3 II > 6 mm) and the 40 most stable subjects (lowest T3 II < 1.5 mm) were identified for the study. Cone-beam computed tomography (CBCT) scans were taken of the posttreatment (T2) models. Total volume (V) was defined laterally by the distal contact points of the canines and vertically by the cusp tips of the canines to a depth 7 mm below the most inferior gingival margin. Alveolar volume (AV) was defined as the region below a vertical line at the most inferior gingival margin and tooth volume (TV) as the region above that line. The ratio TV:AV was calculated. Logistic regression analysis was used to determine the association between relapse and AV, and to adjust for potentially confounding variables (TV, initial II, sex, age, retention time, and postretention time). Mandibular cortical thickness (CT) measured on T2 lateral cephalograms was used as another measure of bone quantity. Nine patients from the graduate orthodontic clinic who had pretreatment CBCT scans were identified. V, AV, and TV were measured on both the in-vivo scans and the scans of their dental casts to verify the method. RESULTS: The relapse group had significantly greater V and AV and significantly lower CT. TV:AV was not different between the groups. T2 II was found to be a significant predictor of relapse based on logistic regression analysis, whereas AV was not. CT was poorly correlated with AV. V and AV were highly correlated between in-vivo scans and dental cast scans, whereas TV approached significance. CONCLUSIONS: Although postretention relapse was associated with increased V and AV, when other variables were controlled, bone volume was not a significant predictor of relapse.

Isolation and characterization of Vibrio tubiashii outer membrane proteins and determination of a toxR homolog.

Outer membrane proteins (OMPs) expressed by Vibrio tubiashii under different environmental growth conditions were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, N-terminal amino acid sequencing, and PCR analyses. Results showed the presence of a 38- to 40-kDa OmpU-like protein and ompU gene, a maltoporin-like protein, several novel OMPs, and a regulatory toxR homolog.

Cell-based two-region competition algorithm with a map framework for boundary delineation of a series of 2D ultrasound images.

To ensure the delineated boundaries of a series of 2-D images closely following the visually perceivable edges with high boundary coherence between consecutive slices, a cell-based two-region competition algorithm based on a maximum a posteriori (MAP) framework is proposed. It deforms the region boundary in a cell-by-cell fashion through a cell-based two-region competition process. The cell-based deformation is guided by a cell-based MAP framework with a posterior function characterizing the distribution of the cell means in each region, the salience and shape complexity of the region boundary and the boundary coherence of the consecutive slices. The proposed algorithm has been validated using 10 series of breast sonograms, including seven compression series and three freehand series. The compression series contains two carcinoma and five fibroadenoma cases and the freehand series contains two carcinoma and one fibroadenoma cases. The results show that >70% of the derived boundaries fall within the span of the manually delineated boundaries. The robustness of the proposed algorithm to the variation of regions-of-interest is confirmed by the Friedman tests and the p-values of which are 0.517 and 0.352 for the compression and freehand series groups, respectively. The Pearson's correlations between the lesion sizes derived by the proposed algorithm and those defined by the average manually delineated boundaries are all higher than 0.990. The overlapping and difference ratios between the derived boundaries and the average manually delineated boundaries are mostly higher than 0.90 and lower than 0.13, respectively. For both series groups, all assessments conclude that the boundaries derived by the proposed algorithm be comparable to those delineated manually. Moreover, it is shown that the proposed algorithm is superior to the Chan and Vese level set method based on the paired-sample t-tests on the performance indices at a 5% significance level.

Application of a novel hydrophilic infrared-transparent membrane to the differentiation between microcolonies of Enterobacter sakazakii and Klebsiella pneumoniae.

A proof-of-concept study is reported for the differentiation between microcolonies of Enterobacter sakazakii and Klebsiella pneumoniae by means of a novel sample preparation for infrared (IR) analysis. A disposable, IR-transparent, microporous (0.2-microm pores), hydrophobic, polyethylene (PE) membrane (51 microm thick) was plasma treated under an oxygen atmosphere and used to (i) filter (or print microarrays of) dilute aqueous foodborne bacterial suspensions and (ii) subsequently grow bacterial microcolonies when the treated, hydrophilic PE membrane was placed over brain heart infusion agar medium and incubated. Because this unique membrane is transparent to IR light, isolated microcolonies (200 microm) of bacterial cells grown on this PE substrate for the first time could be directly fingerprinted by IR microspectroscopy in the transmission mode. Hence, time-consuming bacterial cell transfer from culture plates to an IR sample holder for subsequent measurement by IR spectroscopy was eliminated. Multivariate analysis of the observed IR spectra for microcolonies allowed the rapid differentiation between E. sakazakii and K. pneumoniae.

A model for digital archiving of radiographs into a searchable database.

Digital images are routinely used in orthodontic practices today. Many systems and formats are available for producing, storing, retrieving, viewing, and sharing these images. The digital imaging and communication in medicine (DICOM) standard is designed to ensure that these systems and formats are compatible, so that an image produced in a small private practice today can be viewed next year in a large hospital. The purpose of this article is to describe a method for laser scanning and digitization of analog (film) radiographs that meets DICOM standards and allows for web-based archiving, searching, and retrieval.

Trabecular and cortical bone as risk factors for orthodontic relapse.

INTRODUCTION: Dental relapse of the mandibular incisors after orthodontic treatment is a common problem, and few risk factors have been identified. The purpose of this case-control study was to evaluate whether the amount or the structure of mandibular bone affects the potential for postorthodontic mandibular incisor relapse. METHODS: The subject sample was selected from the postretention database at the University of Washington. Subjects were chosen based on the availability of lateral cephalograms and mandibular periapical radiographs taken approximately 10 years postretention (T3). The mandibular incisor irregularity index (II) was measured on the T3 casts. Two groups were identified: subjects with the II greater than 6 mm (relapse or case) and those with the II less than 3.5 mm (stable or control). Once the case/control status was determined, the II was measured on models taken at the initial orthodontic examination (T1) and at the end of treatment (T2). Sixty relapse and 263 stable subjects were identified. Mandibular cortical thickness measured on both panoramic and lateral cephalometric radiographs was used to assess the amount of mandibular bone, and fractal analysis was used to analyze the trabecular bone structure around the mandibular incisors on the periapical radiographs. Logistic regression analyses were used to determine the association between dental relapse and significant bone parameters. The models were adjusted for potentially confounding variables (initial II, sex, age, and postretention time). RESULTS: The relapse subjects had a larger mean II at T1 and a longer postretention time than the stable subjects. The mean cephalometric mandibular cortical thickness was significantly smaller in the relapse group than in the stable group at T1, T2, and T3. There were no statistically significant differences in the trabecular structure of bone, as measured with fractal analyses, between the relapse and stable groups. CONCLUSIONS: These results indicate that patients with thinner mandibular cortices are at increased risk for dental relapse.

Cell-competition algorithm: a new segmentation algorithm for multiple objects with irregular boundaries in ultrasound images.

Segmentation of multiple objects with irregular contours and surrounding sporadic spots is a common practice in ultrasound image analysis. A new region-based approach, called cell-competition algorithm, is proposed for simultaneous segmentation of multiple objects in a sonogram. The algorithm is composed of two essential ideas. One is simultaneous cell-based deformation of regions and the other is cell competition. The cells are generated by two-pass watershed transformations. The cell-competition algorithm has been validated with 13 synthetic images of different contrast-to-noise ratios and 71 breast sonograms. Three assessments have been carried out and the results show that the boundaries derived by the cell-competition algorithm are reasonably comparable to those delineated manually. Moreover, the cell-competition algorithm is robust to the variation of regions-of-interest and a range of thresholds required for the second-pass watershed transformation. The proposed algorithm is also shown to be superior to the region-competition algorithm for both types of images.

Mandibular inferior cortical bone thickness on panoramic radiographs in patients using bisphosphonates.

OBJECTIVE: The goal of this study was to detect dimensional changes in the mandibular cortical bone associated with bisphosphonate (BP) use and to correlate measurements of the cortical bone with the cumulative dose of BPs. STUDY DESIGN: Mandibular inferior cortical bone thickness (MICBT) was measured under the mental foramen on panoramic radiographs of patients with and without bisphosphonate-related osteonecrosis of the jaws (BRONJ) taking BPs and controls. RESULTS: Patients with BRONJ had the highest mean MICBT (6.81 ± 1.35 mm), compared with patients without BRONJ taking BPs (5.44 ± 1.09 mm) and controls (4.79 ± 0.85 mm) (P < .01). Mean MICBT of patients with BRONJ was significantly higher than that of patients without BRONJ taking BPs. There was a correlation between MICBT and cumulative dose of zolendronate. CONCLUSIONS: Measurement of MICBT on panoramic radiographs is a potentially useful tool for the detection of dimensional changes associated with BP therapy.

Cytopathology and release of an RNA virus from a strain of Trichomonas vaginalis.

A strain of Trichomonas vaginalis infected with a double-stranded RNA virus showed pronounced cytopathology in the form of giant syncytia generated by the recruitment of single cells. The giant cells ultimately lysed, releasing virus into the culture medium. In the infected cells, clusters of electron-dense particles resembling viral structures were found in the cytoplasm. In addition, distinctive inclusions composed of similar particles were present in the nuclei of some cells. Double-stranded viral RNA of 5.5 kbp was demonstrated in both cytoplasmic and nuclear fractions from these cells. Viral particles collected from the cell-free culture supernatant were of the same shape and size as the RNA virus isolated from a strain of T. vaginalis described previously (Wang & Wang, Journal of Biological Chemistry, 260: 3697-3702, 1985; Wang & Wang, Proceedings of the National Academy of Sciences of the U.S.A. 83: 7956-7960, 1986) which does not show this cytopathology.

Twin carriers of X-linked agammaglobulinemia (XLA) due to germline mutation in the Btk gene.

We report on an X-linked agammaglobulinemia (XLA) family in which mothers of two affected cousins were monozygotic twins. We analyzed the Btk gene of several members in three generations of the family by SSCP analysis, DNA sequencing, and RFLP analysis following polymerase chain reaction-amplification of the individual exons. We identified a missense point mutation, G1817C (R562P), in exon 17 of the Btk gene in the affected cousins. The same mutation was also present in both mothers (twin sisters) of the cousins identifying them as carriers. However, the mutation was absent in all other relatives including the grandmother of the cousins (mother of the twin sisters). This strongly suggests that the mutation in the Btk gene had originated in one of the germ lines or in the zygote. This may be the first demonstration of a germ line (or zygotic) mutation in XLA.

Microspectrophotometric estimates of non-histone proteins in cell nuclei displaying differing degrees of chromatin condensation.

Nuclei isolated from mouse thymus, kidney, and liver were fixed in ethanol-acetic acetic acid; treated with dilute acid to extract histones; stained by three protein end-group procedures; and measured by scanning, integrating microspectrophotometry. Measurements were also made of nuclei isolated from the same organs and stained by the Feulgen procedure for DNA. Protein end-group procedures included pH 2.8 Biebrich scarlet (for basic groups), mercury orange (for sulfhydryl groups), and mercury orange after thioglycolate reduction (for the sum of sulfhydryl and disulfide groups). With the exception of the comparison between Feulgen-stained 2C liver and kidney nuclei, the integrated extinction values obtained for nuclei of a given organ differed significantly from the measurements of nuclei from other organs, regardless of the staining procedure. Furthermore, the integrated extinction values for 2C nuclei were highest in larger, more vesicular nuclei (from liver and kidney) and lowest in condensed thymocyte nuclei, except in the case of measurements of the disulfide content of the nuclei. In this instance, the values of integrated extinction were highest in condensed thymocyte nuclei, intermediate in kidney nuclei, and lowest in 2C liver nuclei. When 2C, 4C, and 8C liver nuclei were compared, the integrated extinction values of 4C nuclei were found to be approximately twice those of 2C nuclei whose disulfide and Feulgen values were, respectively, higher and lower than expected. The greater disulfide values and reduced Feulgen values obtained in thymocyte and 8C liver nuclei might be related to a greater degree of chromatin condensation in these nuclei, and therefore, to a reduction or selective restriction of their RNA transcriptional capacities.

Ultrastructure and histochemistry of the supportive structures associated with the radula of the slug, Limax maximus.

The odontophore and connective tissue-filled portion of the radular sac (called the "collostyle") of the slug, Limax maximus, were examined by light and electron microscopy. While both of these structures grossly resemble vertebrate cartilage, neither is composed of a type of tissue with the microscopic appearance and histochemical properties of cartilage. The roughly U-shaped odontophore possesses a thin capsule composed of connective tissue. The parenchyma of the odontophore consists of modified muscle cells which are organized into irregular groups by incomplete trabeculae composed of conventional muscle cells. The odontophoral cells are variable in size; they contain glycogen-filled "cores" as well as bundles of peripherally located filaments resembling myofilaments; and they are innervated like muscle cells. The nuclei of the cells are located eccentrically in the glycogen-filled portions of the cells and typically contain prominent nucleoli. The nuclei are surrounded by multiple small Golgi complexes and pleomorphic dense bodies resembling lysosomes. The extracellular matrix of the odontophore is very sparse and contains glycogen and fibrillar material but no histochemically demonstrable acidic mucosubstances. The collostyle consists of a gelatinous type of tissue somewhat like vertebrate mucoid connective tissue. The abundant extracellular matrix contains cross-banded filaments, a flocculent material disposed in wavy indefinite strands, and small electron-dense particles. The matrix contains histochemically demonstrable neutral and weakly acidic mucosubstances. The cell population of the collostyle includes solitary muscle cells and fibrocytes containing large quantities of glycogen.

Ultrastructural and histochemical features of the thymus glands of the adult lungless salamander, Plethodon glutinosus (Caudata: Plethodontidae).

The thymus glands of adult slimy salamanders (Plethodon glutinosus) were examined by light and electron microscopy with the objective of describing the populations of epithelial cells believed to be secretory. The results of various histochemical procedures designed to demonstrate nucleic acids, proteins, lipids, and mucosubstances were evaluated by light microscopy. Each thymus is incompletely subdivided into a variable number of interconnected lobules by trabeculae extending inward from a thin capsule composed of connective tissues. The thymic parenchyma lacks distinct cortical and medullary regions, although developing lymphocytes and plasma cells tend to accumulate in larger numbers in the outermost portions of the glands. Basophils are found regularly in the capsule and trabeculae, but only very rarely within the thymic parenchyma. The epithelial cells of the thymus can be classified into five categories: epithelial reticular cells; three varieties of granulated cells (types I, II, and III), and myoid cells. Epithelial reticular cells form a three-dimensional network which extends throughout all portions of the thymus. Type I and type II granulated cells can be distinguished from one another by various morphological criteria at the ultrastructural level, but only small differences in the composition of their inclusions can be demonstrated histochemically. Both types of granules are composed principally of a proteinaceous material containing an abundance of primary amino and guanidyl groups. In addition, most type I inclusions possess a lipid component that cannot be demonstrated in type II granules. Type III granulated cells possess very small cytoplasmic inclusions resembling those of gastroenteric endocrine cells. Myoid cells contain concentrically arranged myofibrils composed of sarcomeres. In favorably oriented material, small cysts can be identified whose walls are composed of mixtures of type I cells, type II cells, and epithelial reticular cells. Groups of degenerating epithelial cells form lamellated structures corresponding to Hassall's (thymic) corpuscles.

Morphological analysis of abnormal digital chondrogenesis in the brachypod (bpH) mouse limb in organ culture.

Brachypod (bpH/bpH), an autosomal mutation in mice, is characterized by a shortening of the long bones and paws, and a delay or absence of ossification in some of the distal limb elements. The present study represents a detailed description of the brachypod phenotype in day 12 hindlimb buds maintained for 6 days in a submerged, serum-free organ culture system. Using this in vitro system, the proximal-to-distal effect on the severity of cartilage reduction was intensified in the brachypod explants with an intermediate expression in the heterozygotes. Immunofluorescent staining of the brachypod cartilage revealed a deficiency in and an abnormal distribution of the proteoglycans. Although there was no recognizable difference in the immunofluorescent staining for type II collagen between the mutant and wild-type, electron micrographs showed the presence of thick fibrils in the matrix. Other atypical structures in the brachypod cartilage included pleomorphic nuclei, reduced intracellular glycogen granules and profuse intercellular contacts. It is proposed that with the use of this in vitro system which supports the autonomous development of the individual limb elements, experiments concerning the pathogenesis of skeletal mutations such as brachypod should be more feasible.

Testicular development and establishment of spermatogenesis in Holstein bulls.

Fifty-two Holstein bulls were castrated at 12, 16, 20, 24, 28 or 32 weeks to (1) determine whether testicular development is influenced by season of birth (April or October) and (2) examine quantitatively the establishment of spermatogenesis. Season of birth (spring or fall) did not influence (P less than .05) either testis weight at castration or the establishment of spermatogenesis. With age held constant, scrotal circumference and testis weight were correlated (.79; p less than .05). Testis weight increased from 9 +/- 1 g at 12 weeks to 117 +/- 10 g at 32 weeks of age. Seminiferous tubules occupied 44% of the testicular parenchyma at 12 weeks and 81% at 32 weeks. Differentiation of basal indifferent supporting cells to Sertoli cells started at 20 weeks, and formation of Sertoli cells was completed near 28 weeks. Gonocytes predominated at 12 weeks, but by 20 weeks most had been replaced by prespermatogonia and A-spermatogonia. Thus, transformation from a prepubertal testis to a pubertal testis containing Sertoli cells and A-spermatogonia occurred between 16 and 24 weeks (testis weight = 18 to 42 g). Preleptotene to diplotene spermatocytes appeared sequentially between 16 and 28 weeks and their numbers increased through 32 weeks. Significant numbers of pachytene spermatocytes and spermatids were not present before 28 and 32 weeks, respectively. Establishment of spermatogenesis was completed by 32 weeks (testis weight less than 80 g). Testes weighing less than 80 g were producing few if any sperm. Thus, the establishment of spermatogenesis was progressive, associated with more than a fourfold increase in testis weight, and occurred over a period of about 16 weeks.

Use of ivermectin for treatment of ear mite infestation in rabbits.

Ivermectin was used to treat ear mite infestation in 480 rabbits in 2 commercial rabbitries. Ivermectin (cattle formulation) injected sc at a dosage of 400 to 440 micrograms/kg of body weight repeated in 18 days appeared to be safe and effective in reducing the prevalence of ear mites in naturally infested rabbits.