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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.

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.

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 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.

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.

In five autopsy specimen studies human temporomandibular joints were investigated by conventional tomography, macroscopy, and microscopy for degenerative changes, in particular erosive hard-tissue changes.In the microscopical evaluation special attention was paid to the calcified cartilage. The calcified cartilage was outlined by a flat or gently undulating basophilic tidemark and an irregular osteochondral junction. A significant correlation was found between the thickness of the calcified cartilage and that of the total articular cartilage. Two types of erosive changes were found; an extensive type with complete loss of overlying cartilage and a local type with retained cartilage. The erosive changes were generally more extensive in the condyle. Microscopically, the erosive changes in the condyle were evenly distributed. In the temporal component there was a slight predominance of these changes located to the lateral part of the tubercle. Tomography underestimated both the presence and the extent of the erosive changes. Positive predictive values and negative predictive values were 0.70 and 0.83, respectively, for changes in the condyle and 0.91 and 0.68 for changes in the temporal component. The likelihood ratio for a positive test was 10.6 in the temporal component and 5.6 in the condyle. The likelihood ratio for a negative test was comparable in the two joint components 0.49 and 0.47 respectively. Three different techniques of computer-aided bone histomorphometry (manual, automatic and semi-automatic) were assessed. The variation when assessing the total and trabecular bone volume was evaluated. Good reproducibility in the assessment of the total and trabecular bone volume was achieved with the aid of a single observer and a semi-automatic technique. This technique was therefore used to assess the total and trabecular bone volume in condyles and temporal components of joints with and without microscopically verified erosive changes. Condyles with erosive changes demonstrated both a higher trabecular bone volume (P&lt; 0.05) and higher total bone volume (P&lt; 0.01) than condyles without erosive changes. In a clinical study on patients undergoing diskectomy, the two cartilage matrix macromolecules aggrecan and cartilage oligomeric matrix protein (COMP) were quantified by enzyme-linked immunosorbent assay in lavage fluids from temporomandibular joints before and six months after surgery. The aggrecan/COMP ratio was higher in the lavage fluid of all joints at follow-up as compared to preoperatively. All joints developed radiographic changes indicative of degenerative changes (osteoarthrosis) during the postoperative period.

Background: Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has been proven to be a good method to detect distant spread of head and neck cancer (HNC). However, most prior studies are based on Asian populations and may not be directly transferable to western populations.

Purpose: To investigate the frequency and distribution of distant metastases and synchronous malignancies detected by PET/CT in HNC in a northern Swedish population.

Material and Methods: All primary whole-body FDG-PET/CT examinations performed on the suspicion of HNC (n = 524 patients) between 1 January 2013 and 31 December 2016 at Umeå University Hospital in Sweden were retrospectively reviewed . After the exclusion of 189 examinations without evidence of primary HNC, 335 examinations were analyzed.

Results: Distant metastases were detected in 10 (3%) patients, all with advanced primary tumors corresponding to TNM stage 3–4, most frequently in salivary gland adenocarcinoma, where 50% of patients had distant spread. Four patients had metastases below the diaphragm, representing 20% of the salivary gland malignancies. In the remaining six patients, metastases were supraphrenic, of which all but one were identified by CT alone. Synchronous malignancies were discovered in 14 (4.2%) patients, of which five were below the diaphragm.

Conclusion: The overall frequency of distant spread and synchronous malignancy in primary HNC was generally low. However, the risk for distant metastases below the diaphragm was relatively higher in salivary gland adenocarcinoma, supporting whole-body FDG-PET/CT in the primary diagnostic work-up in these patients.

Background: The value of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for TN staging in head and neck cancer (HNC) has been proven in numerous studies. A few studies have investigated the value of FDG-PET/magnetic resonance imaging (MRI) in the staging of HNC; the combined results indicate potential for FDG-PET/MRI, but the scientific evidence remains weak.

Purpose: To compare performance of FDG-PET/CT and FDG-PET/MRI for locoregional staging in patients with oropharyngeal carcinomas.

Material and Methods: Two radiologists independently of each other retrospectively reviewed primary pre-therapeutic FDG-PET/CT and FDG-PET/MRI examinations from 40 individuals with oropharyngeal carcinomas. TN stage and primary tumor size were noted. The results were compared between observers and modalities and against TN stage set at a multidisciplinary conference.

Results: For nodal staging, PET/MRI had slightly higher specificity and accuracy than PET/CT for the most experienced observer. Both methods demonstrated excellent sensitivity (≥ 0.97 and 1.00, respectively), as well as high negative predictive values (≥ 0.95 and 1.00, respectively). No significant differences were found for tumor staging or measurement of maximum tumor diameter. There was a weak agreement (κ = 0.35–0.49) between PET/CT and PET/MRI for T and N stages for both observers. Inter-observer agreement was higher for PET/MRI than for PET/CT, both for tumor staging (κ = 0.57 vs. 0.35) and nodal staging (κ = 0.69 vs. 0.55). The agreement between observers was comparable to the agreement between methods.

Conclusion: PET/MRI may be a viable alternative to PET/CT for locoregional staging (TN staging) and assessment of maximal tumor diameter in oropharyngeal squamous cell cancer.

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.