'Seeing is believing': a qualitative approach to studying the use of cone beam computed tomography in endodontics in Sweden.

AIM: To gain insight into the decision processes of dentists when requesting a cone beam computed tomography (CBCT) examination in endodontic settings. METHODOLOGY: Fourteen dentists (eight female) 33-58 years of age (mean = 44) practising in Sweden were interviewed. Ten of the dentists were specialists in Endodontics. The absolute inclusion criterion was experience of referring patients for CBCT for endodontic reasons. The included dentists comprised a strategically selected diverse sample in terms of gender, age, work experience, educational background, location of practice, service affiliation and accessibility to CBCT. Data were obtained through semistructured interviews exposing the context of their last three self-reported referrals. Dentists were encouraged to describe their experiences of the circumstances in their own words, aided by the interviewer's open-ended questions. The interviews were audio-recorded and transcribed verbatim. The text was analysed by qualitative content analysis. RESULTS: The manifest content was organized into three categories that were defined as visualization as a desire, facilitating tough decisions and allocating responsibility. CONCLUSION: An overall theme (covering the latent content) was identified: A balance between clinical common sense and a 'better safe than sorry' attitude guides the use of CBCT in endodontic settings. Informants had high clinical standards, knowledge concerning radiation risks and good sense, which could compensate for their lack of knowledge of guidelines. The national radiation regulatory system was perceived to work as a slightly porous gatekeeper for over-usage.

The impact of cone beam computed tomography on the choice of endodontic diagnosis.

AIM: To determine whether the outcome of cone beam computed tomography (CBCT) examinations performed in accordance with the European Commission guidelines in a clinical setting has an impact on choosing diagnoses in endodontics. METHODOLOGY: A prospective observational study was conducted. Fifty-three consecutive patients (81 teeth) from two different endodontic specialist clinics in Sweden were followed. After performing a thorough clinical examination (based on the history, clinical findings, and diagnostic tests such as intra-oral radiography), the examiner wrote down a preliminary diagnosis before CBCT examination. After the CBCT examination, a new diagnosis was made by the same examiner. Both the pre- and the post-CBCT examination diagnoses were plotted according to patients and teeth. The CBCT examinations were performed using similar equipment and protocols that were standardized amongst the clinics. RESULTS: The diagnoses were changed for at least one tooth in 22 patients (41%); overall, the diagnoses were changed for 28 teeth (35%). CONCLUSION: CBCT has a substantial impact on diagnostic thinking in endodontics when used in accordance with the European Commission guidelines.

The effect of cone beam CT (CBCT) on therapeutic decision-making in endodontics.

OBJECTIVES: The aim was to assess to what extent cone beam CT (CBCT) used in accordance with current European Commission guidelines in a normal clinical setting has an impact on therapeutic decisions in a population referred for endodontic problems. METHODS: The study includes data of consecutively examined patients collected from October 2011 to December 2012. From 2 different endodontic specialist clinics, 57 patients were referred for a CBCT examination using criteria in accordance with current European guidelines. The CBCT examinations were performed using similar equipment and standardized among clinics. After a thorough clinical examination, but before CBCT, the examiner made a preliminary therapy plan which was recorded. After the CBCT examination, the same examiner made a new therapy plan. Therapy plans both before and after the CBCT examination were plotted for 53 patients and 81 teeth. As four patients had incomplete protocols, they were not included in the final analysis. RESULTS: 4% of the patients referred to endodontic clinics during the study period were examined with CBCT. The most frequent reason for referral to CBCT examination was to differentiate pathology from normal anatomy, this was the case in 24 patients (45% of the cases). The primary outcome was therapy plan changes that could be attributed to CBCT examination. There were changes in 28 patients (53%). CONCLUSIONS: CBCT has a significant impact on therapeutic decision efficacy in endodontics when used in concordance with the current European Commission guidelines.

Basic principles for use of dental cone beam computed tomography: consensus guidelines of the European Academy of Dental and Maxillofacial Radiology.

OBJECTIVES: To develop "basic principles" on the use of dental cone beam CT by consensus of the membership of the European Academy of Dental and Maxillofacial Radiology. METHODS: A guideline development panel was formed to develop a set of draft statements using existing European directives and guidelines on radiation protection. These statements were revised after an open debate of attendees at a European Academy of Dental and Maxillofacial Radiology (EADMFR) Congress in June 2008. A modified Delphi procedure was used to present the revised statements to the EADMFR membership, utilising an online survey in October/November 2008. RESULTS: Of the 339 EADMFR members, 282 had valid e-mail addresses and could be alerted to the online survey. A response rate of 71.3% of those contacted by e-mail was achieved. Consensus of EADMFR members, indicated by high level of agreement for all statements, was achieved without a need for further rounds of the Delphi process. CONCLUSIONS: A set of 20 basic principles on the use of dental cone beam CT has been devised. They will act as core standards for EADMFR and, it is hoped, will be of value in national standard-setting within Europe.

Radiation doses in examination of lower third molars with computed tomography and conventional radiography.

OBJECTIVES: To measure organ doses and calculate effective doses for pre-operative radiographic examination of lower third molars with CT and conventional radiography (CR). METHODS: Measurements of organ doses were made on an anthropomorphic head phantom with lithium fluoride thermoluminescent dosemeters. The dosemeters were placed in regions corresponding to parotid and submandibular glands, mandibular bone, thyroid gland, skin, eye lenses and brain. The organ doses were used for the calculation of effective doses according to proposed International Commission on Radiological Protection 2005 guidelines. For the CT examination, a Siemens Somatom Plus 4 Volume Zoom was used and exposure factors were set to 120 kV and 100 mAs. For conventional radiographs, a Scanora unit was used and panoramic, posteroanterior, stereographic (scanogram) and conventional spiral tomographic views were exposed. RESULTS: The effective doses were 0.25 mSv, 0.060 mSv and 0.093 mSv for CT, CR without conventional tomography and CR with conventional spiral tomography, respectively. CONCLUSIONS: The effective dose is low when CT examination with exposure factors optimized for the examination of bone structures is performed. However, the dose is still about four times as high as for CR without tomography. CT should therefore not be a standard method for the examination of lower third molars. In cases where there is a close relationship between the tooth and the inferior alveolar nerve the advantages of true sectional imaging, such as CT, outweighs the higher effective dose and is recommended. Further reduction in the dose is feasible with further optimization of examination protocols and the development of newer techniques.

A 20-year follow-up study of endodontic variables and apical status in a Swedish population.

AIM: To re-examine a population after 20 years and evaluate changes in prevalence of endodontic treatment and apical periodontitis, as well as the technical quality of root fillings. METHODOLOGY: One hundred and fifteen out of an original 200 patients living in the northern part of Sweden were re-examined with a full mouth radiographic survey after 20 years. Frequencies of root canal treated teeth, apical periodontitis and quality parameters of root fillings were registered. RESULTS: The frequency of root canal treated teeth increased significantly (P < 0.05) from 13.9% at the first investigation to 17.7% after 20 years. There was also a statistically significant increase (P < 0.05) in teeth with apical periodontitis from 3.3% to 6.8%. Apical periodontitis both in connection with root canal treated teeth and teeth without endodontic treatment, had increased during the follow-up period. Even though the quality of the root fillings had improved, there was no corresponding improvement of the apical status in teeth with root fillings. CONCLUSIONS: There is still a great need for endodontic treatment in the Swedish population, and no improvement in apical health was found during this 20-year follow up.

Pre-operative radiographic evaluation of lower third molars with computed tomography.

OBJECTIVES: To report radiographic findings of examinations with computed tomography (CT) of impacted lower third molars with an intimate relation to the mandibular canal and to investigate how findings of a dark band across the roots of the lower third molar on panoramic views correspond to the CT findings. METHODS: CT images of 90 lower third molars (64 patients, mean age 34.6 years) in which plain radiography was insufficient to allow determination of the precise anatomical relations were reviewed retrospectively. Panoramic views of 88 teeth existed; these images were interpreted independent of the CT examinations with respect to presence of a dark band across the roots. RESULTS: In 31% of the CT images, the course of the mandibular canal was buccal, in 33% lingual, in 26% inferior, and in 10% inter-radicular. The tooth was in contact with the mandibular canal in 94% and with the lingual cortex in 86%. In 23%, grooving of the root by the canal was judged to be present. In 63% of the cases where a dark band across the roots was observed on panoramic radiographs, CT revealed grooving of the root. CONCLUSIONS: Pre-operative CT of lower third molars is motivated in selected cases when plain radiography is inconclusive. The finding of a dark band across the roots on panoramic radiographs is an indicator of grooving of the tooth by the canal and justifies a pre-operative CT examination. The absence of dark bands on panoramic views does not exclude grooving of the roots.

Perioperative validation of localisation of the mental foramen.

AIM: To assess the accuracy of panoramic radiography and spiral or computed tomography for the localisation of the mental foramen. MATERIALS AND METHODS: The distance from the alveolar crest to the mental foramen was measured from panoramic radiographs, spiral tomograms and CT scans. The same distance was measured during implant surgery using a specially designed caliper. RESULTS: Panoramic radiography showed more deviation (+0.6 mm) from the perioperative measurements than either spiral or computed tomography (+0.4 and -0.3 mm respectively). The difference was significant (P<0.05). In general, distances were overestimated on the panoramic radiographs. CONCLUSIONS: Cross-sectional imaging techniques are recommended for the pre-operative planning of implants in the posterior mandible.

Cartilage matrix macromolecules in lavage fluid of temporomandibular joints before and 6 months after diskectomy.

The purpose was to investigate if antigenic fragments of aggrecan and cartilage oligomeric matrix protein (COMP) are detectable by enzyme-linked immunosorbent assay in lavage fluids from the temporomandibular joint (TMJ) and to examine if the relative content of these cartilage markers changes during development of osteoarthrosis (OA) after diskectomy. Lavage fluid was obtained at surgery and 6 months postoperatively in 13 patients. Computed tomography or magnetic resonance imaging was without evidence of hard-tissue changes prior to surgery in all patients. In 9 of the patients, sufficient material for analysis was obtained at both examinations. Aggrecan and COMP were detectable in all but 2 fluids, in which the COMP levels were below detection limit. The aggrecan/COMP ratio increased in all 9 patients during the 6-month period, indicating increased release of aggrecan relative to COMP fragments. The changed aggrecan/COMP ratio possibly reflects increased cartilage turnover during development of OA. Changes compatible with OA were present on computed tomography in all cases at the 6-month follow-up. This study shows that the lavage procedure is feasible for obtaining synovial fluid from the TMJ for immunochemical analyses of tissue-derived macromolecules.

Bone volume in human temporomandibular autopsy joints with and without erosive changes.

The aim was to compare the trabecular bone volume (TBV) and the total bone volume (TOBV) of human temporomandibular joints (TMJ) with erosive changes with those of joints without erosive changes. We examined 35 TMJ autopsy specimens from 19 individuals aged 66 88 years. Sagittal sections of the joints were analyzed microscopically for erosive hard-tissue changes. The TBV and the TOBV of the sections were assessed with the aid of computerized image analysis. A significant increase in trabecular and total bone volume was found in condyles with erosive changes (TBV = 21%, TOBV = 54%) as compared with condyles without erosive changes (TBV = 15%, TOBV = 40%). The trabecular bone volume of the temporal component was also increased (TBV = 24%) in joints with erosive changes in the condyle as compared with joints with unaffected condyles (TBV = 16%). The findings indicate that the relative bone mass may play a role in the development of erosive changes in the TMJ.

Bone histomorphometry using interactive image analysis. A methodological study with application on the human temporomandibular joint.

The aim was to develop a reproducible method for bone histomorphometry with the aid of a computerized image analysis program, and to examine the variation when assessing the total and the trabecular bone volume. Histologic sections of 18 temporomandibular joint autopsy specimens were read interactively using a cursor. The two parameters total bone volume and trabecular bone volume, of the condyle and the temporal component respectively, were estimated 2 x by 1 observer using 3 different threshold settings: an automatic, a semi-automatic and a manual technique. The threshold was based on the gray-scale distribution of the image. 2 observers read the same sections with the aid of the semi-automatic technique. The intra-observer variation expressed as coefficient of variation ranged between 1.9% and 7.1% for the different parameters, when the automatic threshold setting technique was employed, and between 2.8% and 8.7% with the semi-automatic technique. The manual technique resulted in a high intra-observer variation with a coefficient of variation between 5.2% and 19.9%. There was a systematic difference between the estimates of the 2 observers. In general, intra- and inter-observer variation was higher in the temporal component than in the condyle. The inter-section variation was moderate, the coefficient of variation ranging from 3.8% to 11.1%. The automatic and semi-automatic techniques resulted in comparable intra-observer variation, with a lower bias in the estimates of the semi-automatic technique. By letting one observer apply the semi-automatic technique, it was possible to achieve fast and reproducible analysis of the total and trabecular bone volume.

Chronic recurrent multifocal osteomyelitis involving both jaws: report of a case including magnetic resonance correlation.

A case of chronic recurrent multifocal osteomyelitis in a 14-year-old girl is presented. The disease had an initial aggressive osteolytic appearance involving both the maxilla and the mandible. Conservative treatment with minimal surgical intervention has been successful in this case during a 2-year follow-up period. The value of magnetic resonance imaging and bone scintigraphy in this case and the cause of chronic recurrent multifocal osteomyelitis is discussed.

Microscopy and tomography of erosive changes in the temporomandibular joint. An autopsy study.

Thirty-nine temporomandibular joint autopsy specimens were examined by microscopy and tomography for erosive changes. We found two types of erosive changes, an extensive type with complete loss of cartilage and a local type with retained articular cartilage. On microscopic examination nearly twice as many temporal components as condyles were eroded. The erosions were generally more extensive in the condyle. Erosions in the condyle were evenly distributed. In the temporal component there was a slight predominance of erosions located to the lateral part of the tubercle. The radiologic investigation underestimated both the presence and the extent of the erosions. Positive predictive values and negative predictive values were 0.70 and 0.83, respectively, for erosions in the condyle and 0.91 and 0.68 for erosions in the temporal component. It is suggested that the initial event in osteoarthrosis of the TMJ can occur as a subarticular hard-tissue change. The need for more accurate diagnostic tools than radiography should be stressed.

Calcified cartilage zone and its dimensional relationship to the articular cartilage in the human temporomandibular joint of elderly individuals.

The aim was to describe the appearance of the calcified cartilage zone (CCZ) and to determine its dimensional relationship to the articular cartilage thickness in the normal human temporomandibular joint. An autopsy material comprising 21 joints from 12 elderly individuals was examined microscopically. The appearance of the CCZ was examined, and the thickness of the CCZ and of the total articular cartilage was measured in 18 different positions in each joint. The CCZ was outlined by a flat or gently undulating tidemark and an irregular osteochondral junction. The cellularity of the CCZ varied extensively. The cells were numerous in the CCZ when the overlying articular cartilage displayed high cellularity. Statistical analysis of the measurements demonstrated a relationship (p < 0.001) between the thickness of the CCZ and of the articular cartilage. Our findings, both qualitative and quantitative, indicate a close relationship between the physiology of the CCZ and of the overlying articular cartilage.

Macroscopic and microscopic findings of areas with radiologic erosions in human temporomandibular joints.

The aim was to describe the macroscopic and microscopic findings of areas with radiologic erosions in the human temporomandibular joint. An autopsy material of 40 human joints, removed as blocks, was examined with tomography, and an erosion was found in 37 areas. A macroscopic and a microscopic examination focused on the presence of the calcified cartilage zone (CCZ) was performed in these areas. In the condyle 13 of 14 areas with a radiologic erosion showed denudation of bone macroscopically. Microscopically, these areas were covered by a thin fibrocellular tissue, and the CCZ was absent. In the temporal component, only 1 of the 23 areas showed bone exposure macroscopically. Microscopically, the soft tissue in these areas varied in thickness. The CCZ was missing in 13 of the 23 areas, even in some areas that appeared normal macroscopically and were microscopically covered by intact soft tissue. Thus, in areas with a radiologic erosion the macroscopic and microscopic appearance differed between the condyle and the temporal component. The nature of the findings is discussed.

A comparative study of the clinical efficacy of Screw Vent implants versus Brånemark fixtures, installed in a periodontal clinic.

The clinical success of 85 Screw Vent and 107 Brånemark implants, consecutively installed in a private periodontal clinic under the same conditions and by the same operator, is compared. Mobile implants were removed and considered as failures. Intra-oral radiographs were assessed for the presence of peri-implant radiolucencies and for analysis of bone loss after functional loading. 85 Screw Vent implants were installed in 31 patients. Of 23 implants installed in 9 mandibles, none failed after 16.8 (range 12-25) months of function. Of 62 Screw Vent implants installed in 23 maxillae, 6 failed at abutment connection, 1 failed after 2 months and 2 after 13 months of function. The absolute failure rate after 13.2 (range 6-24) months was 9/62. Mean loss of bone was 1.47 mm (-1.0- +4) after 12 months of functional loading. 107 Brånemark fixtures were installed in 25 patients. Of 51 fixtures inserted in 12 mandibles, none failed; of 56 fixtures installed in 13 maxillae 1 failed before and 2 failed during abutment connection. The absolute failure is 3/56. All remaining fixtures were immobile after loading. 13 fixtures were more than 6 months in function. Only short-term comparison between both systems is possible because the observation time is longer for the Screw Vent implants. In the 1st year, only 1 implant system was available to the periodontist. Short-term comparison reveals 11.3% versus 5.3% of cumulative failure after 6 months for the Screw Vent and Brånemark implants, respectively. The results indicate that clinical efficacy is as effectively obtained with Screw Vent as with Brånemark implants in the mandible. The outcome of treatment with Screw Vent implants in the maxilla seems less predictable.

Control of an affinity purification procedure using a thermal biosensor.

Lactate dehydrogenase (LDH) was recovered from a solution by affinity binding to an N(6)-(6-aminohexyl)-AMP-Sepharose gel. An enzyme thermistor unit was employed to continously measure the activity of the unbound LDH. The enzyme activity signal from the enzyme thermistor was used in a PID controller to regulate the addition of AMP-Sepharose gel to the LDH solution. In another type of experiment, a desktop computer was utilized to control the addition of the adsorbent. Both systems worked satisfactorily, and enabled a rapid and accurate assessment of correct addition of adsorbent.

Stable storage conditions of Immobiline chemicals for isoelectric focusing.

Most of the problems connected with the use of the Immobiline chemicals (a set of six, non-amphoteric, acrylamido buffers having pK values in the pH 3.5-9.5 interval) can be attributed to the alkaline species (with pK values 6.2, 7.0, 8.5 and 9.3). These compounds, to varying degrees are subjected to two degradation pathways: (a) hydrolysis of the amido bond, producing free acrylic acid and a diamine, the latter unable to be incorporated into the polyacrylamide matrix; (b) spontaneous auto-polymerization, producing a number of oligomers up to n-mers, able to aggregate and precipitate large proteins. Storage of their water solutions as frozen aliquots, a method widely employed, only partially alleviates the problem. Addition of trace-amounts of inhibitors, as lately adopted by the manufacturer, could only reduce the problem of auto-polymerization, but not block the hydrolysis of the amido bond. A new solution has been found, which abolishes both phenomena: storage in n-propanol. As demonstrated by gas chromatography, HPLC analyses and two-dimensional separations of complex samples, storage in organic solvent completely abolishes both hydrolysis and auto-polymerization and allows production of highly reproducible focusing patterns.