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ABSTRACT: OBJECTIVES: The primary objective of the study was to compare the postoperative complications following surgical removal of impacted third molars using panoramic radiography (PAN) images- and cone-beam computed tomography (CBCT)-based surgeries for "moderate-risk" cases of impacted third mandibular molars. The secondary objective was to compare the reliability of CBCT with that of PAN in preoperative radiographic determination of the position of the third molar, number of roots, and apical divergence. MATERIALS AND METHODS: A randomized controlled multicenter trial was conducted to compare the surgical complications of PAN- and CBCT-based surgeries of impacted third molars. The sample consisted of impacted third molars from 256 patients with a close relation to the inferior alveolar nerve (IAN). Exclusion criteria were "no risk" and "high risk" of damage to the IAN based on the assessment of the panoramic radiograph. Patients were divided into two groups: the CBCT group (n = 126) and the PAN group (n = 130). The incidences of IAN sensory disturbance and other postoperative complications were recorded for each group at 7 days after surgery. Statistical analysis (kappa values) was used to compare the diagnoses of five trained dentomaxillofacial radiologists and to relate radiologic diagnoses to perioperative findings. Logistic regression was used to determine whether the imaging modality influenced occurrence of postoperative complications. RESULTS: Two extractions (1.5 %) in the CBCT group and five (3.8 %) in the PAN group resulted in IAN sensory disturbance (p = 0.45). Logistic regression models did not show that CBCT modality decreased postoperative complications following surgical removal of impacted third molars. Yet, CBCT revealed the number of roots and apical divergence of the roots more reliably than panoramic radiographs. CONCLUSIONS: CBCT was not better than panoramic radiography in predicting postoperative complications for moderate-risk cases of impacted third mandibular molars. Nonetheless, a CBCT buccolingual view can accurately confirm the number of roots and root morphology of the third molar better than PAN. CLINICAL RELEVANCE: For management of postoperative complications for moderate-risk cases of impacted mandibular third molars, careful preoperative radiographic planning followed by an atraumatic surgical approach seems to be valuable, irrespective of the 2D or 3D nature of the preoperative images.
Clinical Oral Investigations 03/2013; · 2.36 Impact Factor
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European journal of radiology 07/2012; · 2.65 Impact Factor
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ABSTRACT: OBJECTIVE: The purpose was to evaluate the perceived spatial and contrast resolution for a wide range of cone-beam computed tomography (CBCT) devices. STUDY DESIGN: A customized polymethyl methacrylate (PMMA) phantom was developed. Inserts containing a line-pair and rod pattern were used. The phantom was scanned with 13 CBCT devices and 1 multislice CT (MSCT) device using a variety of scanning protocols. The images were presented to 4 observers for scoring. RESULTS: The observer scores showed excellent agreement. A wide range was seen in image quality between CBCT exposure protocols. Compared with the average CBCT scores, the MSCT protocols scored lower for the line-pair insert but higher for the rod insert. CONCLUSIONS: CBCT devices are generally suitable for the visualization of high-contrast structures. Certain exposure protocols can be used for depicting low-contrast structures or fine details. The user should be able to select appropriate exposure protocols according to varying diagnostic requirements.
Oral surgery, oral medicine, oral pathology and oral radiology. 07/2012; 114(1):127-135.
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ABSTRACT: To measure sensory disturbances of the inferior alveolar nerve (IAN) after removal of impacted mandibular third molars using cone beam computed tomography (CBCT) and dental panoramic radiography (PAN) for preoperative assessment in a randomized controlled trial and to measure the efficacy of the observers' prediction of IAN exposure at surgery based on CBCT compared with PAN.
The sample consisted of 86 impacted third molars (from 79 consecutive patients) in close relation to the IAN as determined by PAN and judged as showing a "moderate" risk of IAN damage. Cases presenting with no close relation between the IAN and roots and extremely risky cases with an obvious interrelation were excluded. Potential neurosensory disturbances of the lip and chin were assessed before surgery and during the postoperative recall by measuring the function of the IAN with the light-touch sensation method.
Postoperative sensory disturbances occurred in 1 patient in the CBCT group and 1 patient in the PAN group. The light-touch sensation test showed no significant differences at the lip (P = .10) and chin (P = .17) levels for CBCT- versus PAN-based surgery. Significant differences in making a correct diagnosis of neurovascular bundle exposure at the extraction of impacted teeth were found between the 2 modalities (P = .029).
Within the limits of the present pilot study, CBCT was not superior to PAN in predicting postoperative sensory disturbances but was superior in predicting IAN exposure during third molar removal in cases judged as having "moderate" risk.
Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 06/2012; 70(10):2264-70. · 1.58 Impact Factor
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ABSTRACT: The aims were (i) to propose a framework for costing diagnostic methods in oral health care and (ii) to illustrate the application of the framework to the radiographic examination of maxillary canines with eruption disturbances.
The framework for costing, following Drummond et al. (2005), includes three elements: (i) identification of different resources used in producing and delivering the service, (ii) measurement of the amount of each resource required and (iii) valuation of the resources in monetary terms. Four data collection instruments were designed - a protocol for apportioning the cost of capital equipment to each diagnostic procedure, separate forms for recording consumable items, for the time of different health care providers used for a diagnostic examination and a patient survey for calculation of the total cost to the patient associated with the examination. The framework was applied to the radiographic examination of maxillary canines with eruption disturbances comparing two imaging methods: (i) a new method with cone beam computed tomography and panoramic radiography and (ii) a conventional method using intraoral and panoramic radiography. The primary analysis was performed from the perspective of the health care system. A separate analysis included patient costs with health care system costs to provide a societal perspective. Comparison of the two perspectives allows consideration of whether any costs savings to the health care system are generated at the expense of greater costs for patients and their families. Data for the cost-analysis were retrieved from 47 patients (mean age 14 years) referred to a department of radiology for examination of maxillary canines.
Application of the framework for costing allowed us to compare the resources used to perform examinations of the two methods. The mean total cost per examination for the new method was 128.38€ and 81.80€ for the conventional method, resulting in an incremental cost per examination of the new method of 46.58€.
The application of the framework demonstrates the feasibility of measuring and comparing the total costs as well as the distribution of total costs between providers and patients for different approaches to this common examination.
Community Dentistry And Oral Epidemiology 03/2012; 40(4):351-61. · 1.89 Impact Factor
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ABSTRACT: OBJECTIVES: To quantify metal artifacts obtained from a wide range of cone beam computed tomography (CBCT) devices and exposure protocols, to compare their tolerance to metals of different densities, and to provide insights regarding the possible implementation of metal artifact analysis into a QC protocol for CBCT. MATERIALS AND METHODS: A customized polymethyl methacrylate (PMMA) phantom, containing titanium and lead rods, was fabricated. It was scanned on 13 CBCT devices and one multi-slice computed tomography (MSCT) device, including high dose and low-dose exposure protocols. Artifacts from the rods were assessed by two observers by measuring the standard deviation of voxel values in the vicinity of the rods, and normalizing this value to the percentage of the theoretical maximum standard deviation. RESULTS: For CBCT datasets, artifact values ranged between 6.1% and 27.4% for titanium, and between 10.% and 43.7% for lead. Most CBCT devices performed worse than MSCT for titanium artifacts, but all of them performed better for lead artifacts. In general, no clear improvement of metal artifacts was seen for high-dose protocols, although certain devices showed some artifact reduction for large FOV or high exposure protocols. CONCLUSIONS: Regions in the vicinity of the metal rods were moderately or gravely affected, particularly in the area between the rods. In practice, the CBCT user has very limited possibilities to reduce artifacts. Researchers and manufacturers need to combine their efforts in optimizing exposure factors and implementing metal artifact reduction algorithms.
Clinical Oral Implants Research 12/2011; · 2.51 Impact Factor
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ABSTRACT: A three dimensional appreciation of the form of the anterior mandible is required to place dental implants safely in the region. This study compared the subjective image quality of four available methods of cross sectional imaging of the symphyseal region, the lateral cephalometric view, cone beam computed tomography (CBCT), spiral tomography and the transymphyseal X-ray view.
An experimental water phantom was developed to reproduce human soft tissue around the mandible. Images were taken of four mandibles by the four X-ray techniques. Three different CBCT machines were included. The source of each image was disguised by displaying all images in the same format on the same computer screen. A protocol was developed to process the images for viewing whilst preserving their image quality. A panel of observers of ten dentists viewed the images and rated their image quality by recording their agreement with six statements on a five point Likert scale.
The results showed a statistically significant difference in image quality between imaging methods. There were clear differences in the ratings between the three cone beam computed tomography machines. Small volume, high resolution CBCT provided images with the highest scores for subjective image quality.
Within the limitations of this study, significant differences in subjective image quality were found between imaging systems used for cross sectional imaging for the symphyseal region of the mandible prior to dental implant placement.
Journal of dentistry 08/2011; 39(11):764-70. · 2.00 Impact Factor
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ABSTRACT: Cone-beam CT (CBCT) has shown to be a useful imaging modality for various dentomaxillofacial applications. However, optimization and quality control of dental CBCT devices is hampered due to the lack of an appropriate tool for image quality assessment. To investigate the application of different image quality parameters for CBCT, a prototype polymethyl methacrylate (PMMA) cylindrical phantom with inserts for image quality analysis was developed. Applicability and reproducibility of the phantom were assessed using seven CBCT devices with different scanning protocols. Image quality parameters evaluated were: CT number correlation, contrast resolution, image homogeneity and uniformity, point spread function, and metal artifacts. Deviations of repeated measurements were between 0.0% and 3.3%. Correlation coefficients of CBCT voxel values with CT numbers ranged between 0.68 and 1.00. Contrast-to-noise ratio (CNR) values were much lower for hydroxyapatite (0 < CNR < 7.7) than for air and aluminum (5.0 < CNR < 32.8). Noise values ranged between 35 and 419. The uniformity index was between 3.3% and 11.9%. Full width at half maximum (FWHM) measurements varied between 0.43 mm and 1.07 mm. The increase of mean voxel values surrounding metal objects ranged between 6.7% and 43.0%. Results from preliminary analyses of the prototype quality control phantom showed its potential for routine quality assurance on CBCT. Large differences in image quality performance were seen between CBCT devices. Based on the initial evaluations, the phantom can be optimized and validated.
Journal of Applied Clinical Medical Physics 01/2011; 12(4):3478. · 1.29 Impact Factor
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Ruben Pauwels,
Jilke Beinsberger,
Bruno Collaert,
Chrysoula Theodorakou,
Jessica Rogers,
Anne Walker,
Lesley Cockmartin,
Hilde Bosmans,
Reinhilde Jacobs,
Ria Bogaerts, Keith Horner
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ABSTRACT: To estimate the absorbed organ dose and effective dose for a wide range of cone beam computed tomography scanners, using different exposure protocols and geometries.
Two Alderson Radiation Therapy anthropomorphic phantoms were loaded with LiF detectors (TLD-100 and TLD-100 H) which were evenly distributed throughout the head and neck, covering all radiosensitive organs. Measurements were performed on 14 CBCT devices: 3D Accuitomo 170, Galileos Comfort, i-CAT Next Generation, Iluma Elite, Kodak 9000 3D, Kodak 9500, NewTom VG, NewTom VGi, Pax-Uni3D, Picasso Trio, ProMax 3D, Scanora 3D, SkyView, Veraviewepocs 3D. Effective dose was calculated using the ICRP 103 (2007) tissue weighting factors.
Effective dose ranged between 19 and 368 μSv. The largest contributions to the effective dose were from the remainder tissues (37%), salivary glands (24%), and thyroid gland (21%). For all organs, there was a wide range of measured values apparent, due to differences in exposure factors, diameter and height of the primary beam, and positioning of the beam relative to the radiosensitive organs.
The effective dose for different CBCT devices showed a 20-fold range. The results show that a distinction is needed between small-, medium-, and large-field CBCT scanners and protocols, as they are applied to different indication groups, the dose received being strongly related to field size. Furthermore, the dose should always be considered relative to technical and diagnostic image quality, seeing that image quality requirements also differ for patient groups. The results from the current study indicate that the optimisation of dose should be performed by an appropriate selection of exposure parameters and field size, depending on the diagnostic requirements.
European journal of radiology 12/2010; 81(2):267-71. · 2.65 Impact Factor
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Keith Horner,
Philip Allen,
Jim Graham,
Reinhilde Jacobs,
Steven Boonen,
Susan Pavitt,
Olivia Nackaerts,
Elizabeth Marjanovic,
Judith E Adams,
Kety Karayianni,
Christina Lindh,
Paul van der Stelt,
Hugh Devlin
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ABSTRACT: The OSTEODENT index is a predicted probability of osteoporosis derived from a combination of an automated analysis of a dental panoramic radiograph and clinical information. This index has been proposed as a suitable case-finding tool for identification of subjects with osteoporosis in primary dental care; however, no data exist on the relationship between OSTEODENT index and fracture risk. The aims of this study were to assess the relationship between the OSTEODENT index and hip fracture risk as determined by FRAX and to compare the performance of the OSTEODENT index and FRAX (without femoral BMD data), in determining the need for intervention as recommended in UK national treatment guidance.
The study was a retrospective analysis of data from 339 female subjects (mean age 55.3 years), from 2 centers: Manchester (UK) and Leuven (Belgium). Clinical information and femoral neck BMD were available for FRAX, and dental panoramic radiographic data and clinical information were available to calculate the OSTEODENT index. Subjects were classified into "treat" or "lifestyle advice and reassurance" categories using the National Osteoporosis Guideline Group (NOGG) threshold.
The OSTEODENT index result was significantly related to the 10-year probability of hip fracture derived from the reference standard FRAX tool (Rs = 0.67, P < .0001); 84 patients (24.8%) were allocated to the "treat" category on the basis of FRAX and the UK national guidance. Using this "treatment/no treatment" classification as the reference standard, ROC analysis showed no significant difference between areas under the curves for the OSTEODENT index (0.815) and the 10-year probability of hip fracture derived from the FRAX index without BMD (0.825) when used as tests for determining therapeutic intervention.
The results suggest that the OSTEODENT index has value in prediction of hip fracture risk. Prospective trials are needed to confirm this finding and to examine the feasibility for its use in primary dental care.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 08/2010; 110(2):243-9. · 1.50 Impact Factor
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ABSTRACT: To investigate the effect of platelet-rich plasma (PRP) on the healing of hard and soft tissues of extraction sockets with a pilot study.
Patients undergoing tooth extraction under intravenous sedation were asked to participate in the trial. Autologous platelet concentrates were prepared from the patients' blood and autologous thrombin was produced. Outcome measures were: pain level, analgesic consumption, oral function (ability to eat food, swallowing, mouth opening and speech), general activity, swelling, bruising, bleeding, bad taste or halitosis, food stagnation, patient satisfaction, healing complications, soft tissue healing, trabecular pattern of newly formed bone in extraction sockets, trabecular bone volume, trabecular separation, trabecular length, trabecular width, and trabecular number. Patients were followed up to 3 months post-extraction.
Twelve patients (15 sockets) were randomly allocated to the PRP group and 11 patients (14 sockets) to the control group. Two patients from the control group did not attend any of the scheduled appointments following tooth extraction, and were considered dropouts. Additionally, one more patient from the control group and four patients from the PRP group did not attend their 3-month radiographic assessment appointments. Statistically significantly more pain was recorded in the control group for the first (P=0.02), second (P=0.02) and third (P=0.04) post-operative days for Visual Analogue Scale scores, whereas no differences were observed for the fourth (P=0.17), fifth (P=0.38), sixth (P=0.75) and seventh (P=0.75) post-operative days. There was a statistically significantly higher analgesic consumption for the first (P=0.03) and second (P=0.02) post-operative days in the control group and no differences thereafter. Differences in patients' responses in the health-related quality of life questionnaire were statistically significant in favour of PRP treatment only for the presence of bad taste or bad smell in the mouth (P=0.03), and food stagnation in the operation area (P=0.03). The difference between groups was not statistically significant for patient satisfaction with the treatment (P=0.31). Regarding complications, two dry sockets and one acutely inflamed alveolus occurred in patients of the control group, which determined a borderline statistically significant difference in favour of the PRP group (P=0.06). Soft tissue healing was significantly better in patients treated with PRP (P=0.03). Radiographic evaluation carried out by the two blinded examiners revealed a statistically significant difference (P=0.01) for sockets with dense homogeneous trabecular pattern, a borderline statistically significant difference in the trabecular pattern for bone volume (P=0.06) favouring PRP use, and no significant differences for trabecular separation (P=0.66), trabecular length (P=0.16), trabecular width (P=0.16) and trabecular number (P=0.38).
PRP may have some benefits in reducing complications such as alveolar osteitis and improving healing of soft tissue of extraction sockets. There were insufficient data to support the use of PRP to promote bone healing or to enhance the quality of life of patients following tooth extraction, although the sample size was too small to detect statistically significant differences.
European Journal of Oral Implantology 01/2010; 3(2):121-34. · 1.67 Impact Factor
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Kety Nicopoulou-Karayianni,
Panagiotis Tzoutzoukos,
Anastasia Mitsea,
Athanasios Karayiannis,
Kostas Tsiklakis,
Reinhilde Jacobs,
Christina Lindh,
Paul van der Stelt,
Philip Allen,
Jim Graham, Keith Horner,
Hugh Devlin,
Susan Pavitt,
Jingsong Yuan
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ABSTRACT: 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.
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.
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.
We have established a significant association between osteoporosis and tooth loss after adjusting the effect for age and smoking.
Journal Of Clinical Periodontology 04/2009; 36(3):190-7. · 3.00 Impact Factor
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Olivia Nackaerts, Keith Horner,
Reinhilde Jacobs,
Kety Karayianni,
Anastasia Mitsea,
Leonidas Berkas,
Michael Mastoris,
Christina Lindh,
Paul F van der Stelt,
Elizabeth Marjanovic,
Judith E Adams,
Susan Pavitt,
Hugh Devlin
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ABSTRACT: The aim of this study was to determine whether alcohol consumption would predict mandibular bone quality and quantity in a large European female population. In total, 672 middle-aged and elderly women (45-70 yr of age; standard deviation = 6) were recruited in the study. Alcohol consumption was recorded through a self-reported questionnaire. Mandibular cortical width was measured, by five observers, in the mental foramen region on panoramic radiographs. Mandibular bone density, expressed as aluminium thickness, was recorded on intra-oral radiographs. Alcohol consumption was associated with a reduction of mandibular bone density and cortical width. This association was higher in subjects with excessive alcohol consumption, defined in the present study as > 14 units consumed per week. This study showed reduced jaw-bone quality in older individuals and in those with increased alcohol consumption.
European Journal Of Oral Sciences 02/2009; 117(1):7-12. · 1.88 Impact Factor
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ABSTRACT: The provision of an implant-retained overdenture with two implants in the canine regions is a well established treatment modality. Assessment of the form of the anterior mandible is essential in order to avoid surgical complications. Cross-sectional imaging gives ideal images but has radiation and economic costs. A panoramic radiograph supplemented by a lateral cephalometric radiograph is commonly used in these cases, but the latter is not widely available in dental practices. A transymphyseal radiographic technique is presented, using equipment and materials readily available in general dental practice, which may be used as an alternative to the lateral cephalometric radiograph.
Dental update 01/2009; 35(10):689-94.
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ABSTRACT: This randomised double-blind placebo-controlled trial was carried out to investigate the effect of a one-week post-operative course of 600 mg of ibuprofen taken four times a day on marginal bone level around dental implants.
A total of 61 patients were allocated to the ibuprofen (31 patients) or placebo group (30 patients). Overall, 132 implants were inserted, 67 implants in the ibuprofen group and 65 implants in the placebo group. Preparation of the implant sites was carried out with an intermittent drilling sequence adapted to the fixture diameter and the local bone quality according to the Astra Tech implant installation guide. The primary outcome measure was the change in marginal bone level around dental implants from the baseline (2 weeks post-placement) to the 3- and 6-month radiographic examinations. The paralleling technique and a film holder coupled to a beamaiming device were used to take the periapical radiographs. Measurement of changes in bone level was made using a viewing box and x8 magnifier.
Two patients from the ibuprofen group were unable to complete the prescribed course of ibuprofen owing to a minor self-reported stomach upset. A patient from the control group did not attend any of the scheduled appointments following implant placement. A total of three patients dropped out. All implants survived in either group during the 6-month observation period. The mean marginal bone level changes from the baseline were (-0.33 mm) at the 3-month and (-0.29 mm) at the 6-month follow-up for the ibuprofen group while the corresponding values for the placebo group were (-0.12 mm) and (-0.30 mm). There were no statistically significant differences between groups for mean marginal bone level changes at 3 months (P = 0.27) or 6 months (P = 0.97).
Administration of a short course of systemic ibuprofen for post-operative pain management subsequent to implant placement may not have a significant effect on the marginal bone around dental implants in the early healing period.
European Journal of Oral Implantology 01/2009; 2(3):185-99. · 1.67 Impact Factor
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Christina Lindh, Keith Horner,
Grethe Jonasson,
Peter Olsson,
Madeleine Rohlin,
Reinhilde Jacobs,
Kety Karayianni,
Paul van der Stelt,
Judith Adams,
Elizabeth Marjanovic,
Sue Pavitt,
Hugh Devlin
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ABSTRACT: 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.
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.
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).
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.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 09/2008; 106(2):285-93. · 1.50 Impact Factor
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ABSTRACT: Since 1988, thirteen dental schools have provided dental undergraduate programmes within the United Kingdom (UK). In 2006, two new dental schools were created supporting dental education in the community. A further new dental school in Scotland will be accepting students in autumn 2008. In the past 25 years, extensive reorganisation of the NHS has resulted in long-term implications for the training of medical and dental academic staff. The number of academic clinicians is below the minimum viable level and external constraints, combined with a lack of suitable applicants, have led to a moratorium on academic recruitment within some Dental Schools. A detailed review of the historical and associated factors which have led to the problems presently besetting academic dentistry are discussed along with the initiatives introduced in the last 10 years to revitalise the speciality. Also, the present and future outlook for academic dentistry in other countries are discussed. Opinion is divided as to the appropriate setting for the training of undergraduate students between those who support community-based dental education and those who believe dental education should remain within research led dental establishments. External factors are moulding an unsatisfactory situation that is proving increasingly unattractive to the potential dental academic and the case for reform is obvious.
Journal of Dentistry 08/2008; 36(7):472-80. · 2.95 Impact Factor
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ABSTRACT: Measurement of cortical thickness and subjective assessment of cortical porosity on panoramic radiographs are methods previously reported for diagnosing osteoporosis. The aims of this study were to determine the relative efficacy of the mandibular cortical index and cortical width in detecting osteoporosis, both alone and in combination, and to determine the optimal cortical width threshold for referral for additional osteoporosis investigation.
Six hundred seventy-one postmenopausal women 45 to 70 years of age were recruited for this study. They received dual energy x-ray absorptiometry (DXA) scans of the left hip and lumbar spine (L1 to L4), and dental panoramic radiographic examinations of the teeth and jaws. Three observers separately assessed the mandibular cortical width and porosity in the mental foramen region of the mandible. Cortical width was corrected for magnification errors. Chi-squared automatic interaction detection analysis (CHAID) software was used (SPSS AnswerTree, version 3.1, SPSS Inc., Chicago, IL).
Chi-squared automatic interaction detection analysis showed that the cortical porosity was a poorer predictor of osteoporosis than mandibular cortical width. For the 3 observers, a mandibular cortical width of <3 mm provided diagnostic odds ratios of 6.51, 6.09, and 8.04. The test is therefore only recommended in triage screening of individuals by using radiographs made for purposes other than osteoporosis.
When evaluating panoramic radiographs, only those patients with the thinnest mandibular cortices (i.e., <3 mm) should be referred for further osteoporosis investigation.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 12/2007; 104(6):821-8. · 1.50 Impact Factor
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ABSTRACT: 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 characterstic (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.
IEEE Transactions on Information Technology in Biomedicine 12/2007; 11(6):601-10. · 1.68 Impact Factor
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ABSTRACT: Among the current mathematical models for bone remodeling, few can consider bone resorption due to overload. The objective of this paper is to develop a new bone remodeling model which can simulate both underload and overload resorptions that often occur in dental implant treatments.
Based on the traditional model, a new mathematical equation relating the density change rate with mechanical stimulus has been developed. The new equation contains an additional quadratic term which can produce reduction in bone density at high load levels. In addition, to fully exploit the characteristics of this model, a range of different bone remodeling behaviors were studied under the load cases with both constant and varying stress magnitudes. Finally, the model was applied in conjunction with the finite element method to a practical case of dental implant treatment.
The FE analysis results showed that bone resorption at the neck of the implant occurred due to occlusal overload but then resorption stopped after some time before reaching the coarse threads. Meanwhile, the density of the bone deeper into the mandible increased slightly due to the additional mechanical stimulus provided by the occlusal load. This phenomenon is observable in some clinical situations.
The new model can describe the bone overload resorption, a feature which is absent in most of the current models. And by simulating the dental implant treatment using FE method, the ability of the new mathematical model to simulate overload bone resorption has been clearly demonstrated.
Dental Materials 10/2007; 23(9):1073-8. · 3.13 Impact Factor
