Dental MRI using wireless intraoral coils.

Currently, the gold standard for dental imaging is projection radiography or cone-beam computed tomography (CBCT). These methods are fast and cost-efficient, but exhibit poor soft tissue contrast and expose the patient to ionizing radiation (X-rays). The need for an alternative imaging modality e.g. for soft tissue management has stimulated a rising interest in dental magnetic resonance imaging (MRI) which provides superior soft tissue contrast. Compared to X-ray imaging, however, so far the spatial resolution of MRI is lower and the scan time is longer. In this contribution, we describe wireless, inductively-coupled intraoral coils whose local sensitivity enables high resolution MRI of dental soft tissue. In comparison to CBCT, a similar image quality with complementary contrast was obtained ex vivo. In-vivo, a voxel size of the order of 250 ∙ 250 ∙ 500 µm(3) was achieved in 4 min only. Compared to dental MRI acquired with clinical equipment, the quality of the images was superior in the sensitive volume of the coils and is expected to improve the planning of interventions and monitoring thereafter. This method may enable a more accurate dental diagnosis and avoid unnecessary interventions, improving patient welfare and bringing MRI a step closer to becoming a radiation-free alternative for dental imaging.

Evaluation of bone substitute materials: comparison of flat-panel based volume CT to conventional multidetector CT.

Over the last decade tissue engineering has emerged as a key factor in bone regeneration within the field of cranio-maxillofacial surgery. Despite this in vivo analysis of tissue-engineered-constructs to monitor bone rehabilitation are difficult to conduct. Novel high-resolving flat-panel based volume CTs (fp-VCT) are increasingly used for imaging bone structures. This study compares the potential value of novel fp-VCT with conventional multidetector CT (MDCT) based on a sheep sinus floor elevation model. Calcium-hydroxyapatite reinforced collagen scaffolds were populated with autologous osteoblasts and implanted into sheep maxillary sinus. After 8, 16 and 24 weeks MDCT and fp-VCT scans were performed to investigate the volume of the augmented area; densities of cancellous and compact bone were assessed as comparative values. fp-VCT imaging resulted in higher spatial resolution, which was advantageous when separating closely related anatomical structures (i.e. trabecular and compact bone, biomaterials). Fp-VCT facilitated imaging of alterations occurring in test specimens over time. fp-VCTs therefore displayed high volume coverage, dynamic imaging potential and superior performance when investigating superfine bone structures and bone remodelling of biomaterials. Thus, fp-VCTs may be a suitable instrument for intraoperative imaging and future in vivo tissue-engineering studies.

Description of a method: computer generated virtual model for accurate localisation of tumour margins, standardised resection, and planning of radiation treatment in head & neck cancer surgery.

Communication between the surgeon, the pathologist and the radiation oncologist is improved by a virtual model of the final resection combining 3D imaging with computer aided navigation. The pathologist localises any questionable margins and the oncologist plans focussed delivery of radiation to native tissue in an area of complex anatomy.

Dental MRI: imaging of soft and solid components without ionizing radiation.

PURPOSE: To evaluate the ability of conventional and ultra-short or zero echo time MRI for imaging of soft and solid dental components in and ex vivo. MATERIALS AND METHODS: Turbo spin echo (TSE), ultra-short echo time (UTE), and zero echo time (ZTE) MRI were performed on extracted (human and equine) teeth and in vivo using whole-body and small-bore MR systems at 3 T, 7T, and 9.4T, respectively. RESULTS: At an isotropic resolution of (600 µm)(3) , strong signal of soft-tissue, e.g., mucosa and nerves with excellent contrast was achieved using TSE at 3T in vivo. No signal, though, was obtained from solid components, e.g., teeth (due to short T(2) ). In contrast, dentin, cementum as well as enamel of extracted teeth were readily depicted using UTE and ZTE at a resolution of ≈ (150 µm)(3) at 7T and 9.4T. In particular, ZTE provided higher signal in enamel. CONCLUSION: As an alternative to X-ray based methods like cone-beam computed tomography (CT) or conventional CT, the presented results demonstrate the potential of ZTE and UTE MRI as a radiation-free imaging modality, delivering contrast of soft and solid components at the same time.

Stable vertical distraction osteogenesis of highly atrophic mandibles after ablative tumour surgery of the oral cavity--a salvage pathway for mandibular reconstruction prior to oral rehabilitation with dental implants.

Mandibular reconstruction is still a challenge for surgeons. Distraction osteogenesis (DO) might contribute in certain instances to solve this problem. A principal advantage of DO is the expansion of the surrounding soft tissues that accompanies the bony regeneration. In addition there is no donor site morbidity when compared with reconstruction by autologous bone grafting. However its application may be limited by the thinness of the mandible and the attendant fracture risk. This article describes a technique that combines stable internal fixation with vertical distraction of the alveolar ridge in six patients with critical mandibular thickness after ablative surgery for cancer of the oral cavity. Prior to implant insertion for further prosthodontic restoration stable vertical mandibular distraction produced an additional 11-20mm. Improvement of the surrounding soft tissues, especially intraorally was achieved and dental implants were inserted after bony consolidation. This method can be a useful salvage technique for the augmentation of the atrophic mandible in patients who are not able or willing to undergo the risks and disadvantages of established methods such as free autologous bone transfer or microsurgical techniques.

Dental mutilations and associated alveolar bone pathology in African skulls of the anthropological skull collection, Charité, Berlin.

BACKGROUND: Dental mutilations (DM) were and are still common among people in Africa. The purpose of this study was to examine DM in 33 skulls from Cameroon, which have been collected around the turn of the 20th century (anthropological collection, Berlin Museum of Medical History). MATERIALS AND METHODS: From the files of the museum, locations and/or tribal origin were recorded. DM classification described by De Almeida was used (1957). RESULTS: DM of the inverted V-shaped type was most common (30.3%). Pulp exposure was seen in 10 cases (30.3%). Periapical ostitis/radicular cysts were seen in nine cases (27.3%). General loss of alveolar bone was seen in all cases with a marked loss of the maxillary anterior labial alveolar bone plate in six cases (18.2%). CONCLUSIONS: DM may result in alveolar bone pathology characterised by inflammatory changes such as periapical ostitis or formation of radicular cysts.

The 'Skull from Bangkok': a skull of a betel quid chewer in the anthropological collection of Rudolf Virchow (Berlin).

This report describes the 'Skull from Bangkok', collected by Rudolf Virchow (Berlin, Germany) in the late 19th century. The skull is part of an extensive anthropological collection of skeletons and skulls from all over the world. The skull was probably brought to Berlin during the years 1882-1883. An inscription on the frontal bone gives the name of the skull: 'Skull from Bangkok'. The few remaining teeth of the maxilla show brown black stains because of betel quid chewing. In the collection, there is an extensive number of skulls from South- and Southeast Asia with similar betel stains. Virchow himself was aware of this habit and has described some of the skulls in detail often mentioning the black stains because of betel quid chewing. The Skull from Bangkok is a proof that betel quid chewing was prevalent in Siam of the late 19th century.

The sensitivity and specificity of the OralCDx technique: evaluation of 103 cases.

In this study, we compared 103 OralCDx results with the histological findings of 96 clinical sites in 80 patients (33 females; 64.3+/-13.7 years and 47 males; 53.2+/-11.5 years). The histological findings were classified as follows: compatible with oral leukoplakia (OL; n = 60) or oral lichen planus (OLP; n = 17), both without dysplasia; dysplasia in OL or OLP (n = 9); and oral squamous cell carcinoma (OSCC; n = 17). There were seven (6.8%) specimens with an inadequate cell count. Overall, the sensitivity of the OralCDx technique to detect dysplasia and OSCC was 92.3% (95% CI: 74.9-99.1%), and the specificity was 94.3% (95% CI: 86.0-98.4%). The positive likelihood ratio (LR+) was 16.2 (95% CI: 6.2-42.1) and the negative likelihood ratio (LR-) was 0.08 (95% CI: 0.02-0.31). In conclusion, these figures are in agreement with previously published data and support the use of OralCDx as a screening tool of oral lesions, but further trials are still necessary.

Clinical risk factors of oral leukoplakia in a representative sample of the US population.

Studies on the risk factors of oral leukoplakia (OL) are relatively scarce. The objectives of this paper are to assess the clinical risk factors of OL in a representative sample of the US population. Data from the oral mucosal tissue assessment and some other covariates of 15,811 participants in the US National Health and Nutrition Examination Survey (NHANES III) were included. The clinical definition of OL was applied according to the WHO criteria. Tobacco smoking was found as the strongest independent risk factor. The OR were 3.00 (0.77-11.8) for < or =10 cigarettes/day up to 6.01 (2.4-15.0) for >20 cigarettes/day. Diabetes, age and socio-economic status were found as independent predictors of OL. Alcohol consumption, race/ethnicity, years of education and BMI showed no independent association with OL. Females with a history of estrogen use were less likely to have OL with an OR of 0.34 (0.11-1.07). In conclusion, the role of diabetes and estrogen in the pathogenesis of OL should be further investigated.

Low prevalence of oral leukoplakia in a representative sample of the US population.

Recent studies reported a tendency towards a lower prevalence of oral leukoplakia (OL), compared with the past. To assess the prevalence of OL in a representative sample of the US population, data from the oral mucosal tissue assessment and some other covariates of 16128 participants in the US National Health and Nutrition Examination Survey (NHANES III) were included. The clinical definition of OL was applied according to the WHO criteria. The weighted prevalence estimates of OL were 0.66+/-0.14% in males, 0.21+/-0.05% in females and 0.42+/-0.08% in total. The age peaks were at 40-49 years in males and at >or=70 years in females. The prevalence estimates were 0.37% for homogeneous OL and 0.06% for non-homogeneous OL. Gingiva (38.8%) and buccal mucosa (30.9%) were the most frequent locations. Compared to previous studies in the USA, a substantial decline of the prevalence of OL was shown.

Is there a natural limit of the transformation rate of oral leukoplakia?

Recent reviews described a cumulative risk of 0-38% of oral leukoplakias (OL) to transform into oral squamous cell carcinoma (OSCC). The annual transformation rate (ATR) of OL into OSCC amounted up to 6.3%. To elucidate epidemiological consequences of varying ATR. Variations of the prevalence (1-2%) and ATR (0.5-4%) of OL were used to compute the proportional incidences of OSCC developing in OL. These were compared to the actual incidences of OSCC excerpted from European cancer registries. A ratio <50% of predicted to actual incidence overall indicated a plausible ATR. With an ATR>or=3%, the predicted incidences of OSCC would exceed the reported incidences in all countries. With an ATR