Christina Lindh

Assessments of trabecular bone density at implant sites on CT images.

OBJECTIVES To evaluate the association between trabecular bone density measurements of potential implant sites made on axial DICOM images (DentaCT software) and on the same images with eFilm workstation, to correlate bone densities in Hounsfield units (HU) with subjective classification, and to establish a quantitative scale for each bone quality class. STUDY DESIGN Twenty-seven maxillary and 27 mandibular computed tomographic (CT) examinations of 75 potential implant sites were selected. Trabecular bone density was evaluated with DentaCT and eFilm. Bone quality was subjectively evaluated by 2 examiners. Descriptive statistics, between- and within-group comparison, correlation analysis, and Bland-Altman plot were used for data analysis. RESULTS DentaCT measurements were higher than eFilm (P < .001). Bone type 2 was the most prevalent, and bone density was significantly reduced from bone types 1 to 4. Quantitative parameters ranged as follows: bone type 4 <200 HU, bone types 2 and 3 >200 to <400 HU, and bone type 1 >400 HU. CONCLUSION Different qualities of bone can be found in any of the anatomical regions studied (anterior and posterior sites of maxilla and mandible), which confirms the importance of a site-specific bone tissue evaluation prior to implant installation.

Assessment of the trabecular pattern before endosseous implant treatment: Diagnostic outcome of periapical radiography in the mandible

OBJECTIVES To study the diagnostic outcome of periapical radiography in the assessment of the bone trabecular pattern of the mandible. STUDY DESIGN Mandibular autopsy specimens were radiographed. Seven observers assessed the radiographs with the aid of a proposed classification with and without reference images and the classification presented by Lekholm and Zarb. Accuracy was estimated on the basis of morphometric measurements of trabecular bone volume. Observer agreement was calculated as the estimated probability of agreement between and within observers and as kappa index. RESULTS With the classification proposed by us, the overall accuracy was 58% with and 50% without reference images. The accuracy for assessing dense trabeculation was higher (78%) than that for sparse trabeculation (28%). The accuracy of the proposed classification by Lekholm and Zarb was not possible to evaluate. The interobserver agreement varied between 49% and 64% and the intraobserver agreement between 75% and 86%. CONCLUSION A new classification with reference images is recommended to assess the trabecular pattern in periapical radiographs before implant treatment.

Tooth loss and osteoporosis: the OSTEODENT Study

AIM To determine the cross-sectional association of the osteoporotic status of patients with the number of their teeth, with and without taking into account age and/or smoking. MATERIAL & METHODS At four centres, the study recruited 665 females aged 45-70 years and the number of teeth was counted for 651 subjects. Bone density was measured at the total hip, femoral neck and lumbar spine. RESULTS The mean number of teeth in the osteoporotic subjects was 3.3 fewer than normal subjects and 2.1 fewer if those with no teeth were excluded. The association between osteoporosis and having <6 or having <28 teeth remained significant after adjusting for age, smoking and centre with p-values of 0.016 and 0.011, respectively. A single regression model for tooth count with normal errors would not fit all the data. By fitting mixture regression models to subjects with tooth count >0, three clusters were identified corresponding to different degrees of tooth loss. The overall effect of osteoporosis was as follows: -1.8 teeth before and after adjusting for smoking, -1.2 teeth after adjusting for age, and -1.1 teeth after adjusting for both age and smoking. CONCLUSIONS We have established a significant association between osteoporosis and tooth loss after adjusting the effect for age and smoking.

Curriculum structure, content, learning and assessment in European undergraduate dental education – update 2010

This paper presents an updated statement on behalf of the Association for Dental Education in Europe (ADEE) in relation to proposals for undergraduate Curriculum Structure, Content, Learning, Assessment and Student / Staff Exchange for dental education in Europe. A task force was constituted to consider these issues and the two previous, related publications produced by the Association (Plasschaert et al 2006 and 2007) were revised. The broad European dental community was circulated and contributed to the revisions. The paper was approved at the General Assembly of ADEE, held in Amsterdam in August 2010 and will be updated again in 2015.

Immediate Loading of Implants in the Edentulous Maxilla: Use of an Interim Fixed Prosthesis Followed by a Permanent Fixed Prosthesis: A 32-Month Prospective Radiological and Clinical Study

PURPOSE The aim of this study was to prospectively evaluate the survival rate of splinted and immediately loaded Straumann sandblasted, large-grit, acid-etched, solid-screw dental implants in the edentulous maxilla after 32 months of loading. MATERIALS AND METHODS Twenty-eight patients (mean age 63 years) with edentulous maxillae received 168 implants (six each) and an implant-supported fixed interim prosthesis within 24 hours after surgery. After a mean healing time of 15 weeks, the patients received permanent screw-retained prostheses. Clinical and radiological examinations were made at implant placement and after 8, 20, and 32 months of loading. All permanent prostheses were removed at the 32-month follow-up; implant stability was checked with a torque device, and the implant stability quotient was determined with resonance frequency analysis. RESULTS Mean marginal bone loss from baseline to 8 months after loading was 1.6 mm (SD 1.16; p = .094), from 8 to 20 months 0.41 mm (SD 0.63; p = .094), and from 20 to 32 months 0.08 mm (SD 0.49; p = .039). The 32-month cumulative survival rate was 98.2%. CONCLUSIONS The 32-month survival of solid-screw implants - immediately loaded within 24 hours after placement - was similar to survival rates reported for solid-screw implants with conventional loading. Immediate loading and splinting of implants in the edentulous maxilla is a viable treatment alternative.

Maxillary bone mineral density and its relationship to the bone mineral density of the lumbar spine and hip

OBJECTIVE We sought to measure the bone mineral density (BMD) of various regions in the maxilla before implant treatment and to investigate correlations between these values and the BMDs of the spine and hip. STUDY DESIGN Eighteen patients were examined by means of quantitative computed tomography, and the BMD of the maxillary alveolar ridge was calculated. The same patients also underwent dual-energy x-ray absorptiometry of the lumbar spine and the total hip. Analysis of variance was used to compare BMD values between and within individuals. The Pearson correlation coefficient was used to correct for sex and body mass and to calculate the correlation between the BMD of the maxillary alveolar ridge and the BMD of the spine and hip. RESULTS The maxillary BMD varied significantly between individuals (P <.001) and within individuals (P <.001). The BMD of the anterior region of the maxilla was correlated significantly with the BMD of the lumbar spine (r=0.6; P <.05). CONCLUSION A site-specific evaluation of maxillary bone tissue could be of value before implant treatment.

Detecting Reduced Bone Mineral Density From Dental Radiographs Using Statistical Shape Models

We describe a novel method of estimating reduced bone mineral density (BMD) from dental panoramic tomograms (DPTs), which show the entire mandible. Careful expert width measurement of the inferior mandibular cortex has been shown to be predictive of BMD in hip and spine osteopenia and osteoporosis. We have implemented a method of automatic measurement of the width by active shape model search, using as training data 132 DPTs of female subjects whose BMD has been established by dual-energy X-ray absorptiometry. We demonstrate that widths measured after fully automatic search are significantly correlated with BMD, and exhibit less variability than manual measurements made by different experts. The correlation is highest towards the lateral region of the mandible, in a position different from that previously employed for manual width measurement. An receiver-operator characteristic (ROC) analysis for identifying osteopenia (T < - 1: BMD more than one standard deviation below that of young healthy females) gives an area under curve (AUC) value of 0.64. Using a minimal interaction to initiate active shape model (ASM) search, the measurement can be made at the optimum region of the mandible, resulting in an AUC value of 0.71. Using an independent test set, AUC for detection of osteoporosis (T < -2.5) is 0.81.

Unusual jaw-bone cysts

Four cases of unusual types of jaw-bone cysts (paradental, lateral periodontal/botryoid type, sialo-odontogenic, and intraosseous dermoid cyst) are reported. Radiographic and histopathologic features are described. Current literature is reviewed with special attention given to radiographic, histogenetic, and histopathologic aspects of these entities.

The use of visual assessment of dental radiographs for identifying women at risk of having osteoporosis: the OSTEODENT project

OBJECTIVE The objective of this study was to investigate the diagnostic accuracy of visual assessment of the trabecular pattern in intraoral periapical radiographs to identify female subjects at risk of having osteoporosis. STUDY DESIGN Six hundred female subjects underwent intraoral periapical radiography of the maxillary and mandibular premolar region. Five observers assessed the trabecular pattern as dense, heterogeneous, or sparse, with the aid of reference images. All patients received a central dual energy x-ray absorptiometry (DXA) examination of the hip and lumbar spine. RESULTS With sparse trabecular pattern as indicative of osteoporosis, mean specificity was high (91.6 for the upper jaw and 90.8 for the lower jaw) while the sensitivity was low (28.2 for the upper and lower jaw). The mean intraobserver agreement was comparable for radiographs of the upper and lower jaw (median kappa(w) 0.53 and 0.57, respectively). CONCLUSION Visual assessment of the trabecular pattern in intraoral periapical radiographs of premolar regions is a potential method to identify women at risk of having osteoporosis.

Osteoporosis detection using intraoral densitometry

OBJECTIVES To determine the diagnostic accuracy of mandibular and maxillary bone density in detecting osteoporosis using receiver operating characteristic (ROC) analysis. METHODS 671 women between 45 years and 70 years of age underwent dual energy X-ray absorptiometry (DXA) of the hip and lumbar spine. This was the gold standard for diagnosing osteoporosis. Intraoral radiography of the upper and lower right premolar region was performed, using an aluminium wedge as a densitometric reference. Jaw bone density was determined using dedicated software. Observer differences and ROC curves were analysed. RESULTS For detecting osteoporosis using jaw bone density, the area under the ROC curve (A(z)) was 0.705. For separate analysis of mandibular and maxillary films, sensitivity varied from 33.9% to 38.7% and specificity from 83.5% to 85.3% when using a threshold of 4.3 mm Al equivalent. CONCLUSIONS Density of the premolar region reaches a fair diagnostic accuracy, which might improve when including additional factors in the analysis and refining the densitometric tool.