Kostas Tsiklakis

Evaluation of the severity of temporomandibular joint osteoarthritic changes related to age using cone beam computed tomography

OBJECTIVES The aim of this study is to evaluate and correlate with age the severity of temporomandibular joint (TMJ) osteoarthritic changes using cone beam CT (CBCT). METHODS The images of 71 patients with findings of degenerative arthritis were retrieved from the computer data base. All patients had been examined with CBCT (NewTom 9000 QR-DVT). Left and right TMJs were evaluated independently for each patient. TMJ evaluation included: (a) bony changes of the condyle (flattening, erosion, sclerosis, osteophytes, resorption); (b) joint space (normal, increased, reduced, bony contact between the condyle and the mandibular fossa); and (c) bony changes of mandibular fossa (normal, sclerosis, erosion, resorption). The radiographic findings were statistically analysed. RESULTS Significant differences in the mean age were found: (a) between absent and moderate erosion (P = 0.019), as well as between absent and extensive erosion (P = 0.048); (b) between absent and extensive formation of osteophyte (P = 0.003), as well as between slight and extensive formation of osteophyte (P = 0.025); (c) between normal joint space and bony contact (P = 0.0002), as well as between reduced joint space and bony contact (P = 0.001). CONCLUSIONS Degenerative arthritis is an age-related disease. The progression and severity of osseous changes in the condylar head and mandibular fossa are increased with age. In older age groups, patients are expected to have more frequent and severe progressive degenerative bony changes due to the development of TMJ osteoarthritis than patients in younger age groups.

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.

Quantification of metal artifacts on cone beam computed tomography images

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.

Variability of dental cone beam CT grey values for density estimations

OBJECTIVE The aim of this study was to investigate the use of dental cone beam CT (CBCT) grey values for density estimations by calculating the correlation with multislice CT (MSCT) values and the grey value error after recalibration. METHODS A polymethyl methacrylate (PMMA) phantom was developed containing inserts of different density: air, PMMA, hydroxyapatite (HA) 50 mg cm(-3), HA 100, HA 200 and aluminium. The phantom was scanned on 13 CBCT devices and 1 MSCT device. Correlation between CBCT grey values and CT numbers was calculated, and the average error of the CBCT values was estimated in the medium-density range after recalibration. RESULTS Pearson correlation coefficients ranged between 0.7014 and 0.9996 in the full-density range and between 0.5620 and 0.9991 in the medium-density range. The average error of CBCT voxel values in the medium-density range was between 35 and 1562. CONCLUSION Even though most CBCT devices showed a good overall correlation with CT numbers, large errors can be seen when using the grey values in a quantitative way. Although it could be possible to obtain pseudo-Hounsfield units from certain CBCTs, alternative methods of assessing bone tissue should be further investigated. ADVANCES IN KNOWLEDGE The suitability of dental CBCT for density estimations was assessed, involving a large number of devices and protocols. The possibility for grey value calibration was thoroughly investigated.

Evaluation of the visibility and the course of the mandibular incisive canal and the lingual foramen using cone‐beam computed tomography

OBJECTIVES To assess the visibility and the course of the incisive canal and the visibility and the location of the lingual foramen using cone-beam computed tomography (CBCT). METHODS In total, 100 CBCT examinations of patients for preoperative planning were used for this study. The examinations were taken using the NewTom 3G CBCT unit, applying a standardized exposure protocol. Image reconstruction from the raw data was performed using the NewTom software. Three experts were asked to assess the visibility of the incisive canal using a four-point rating scale. The position of the incisive canal was recorded in relation to the lower, buccal and lingual border of the mandible using the application provided by the CBCT software. RESULTS The incisive canal was definitely visible in 83.5% of the scans and the mean endpoint was approximately 15 mm anterior to the mental foramen. The mean distance from the lower border of the mandible was 11.5 mm and its course was closer to the buccal border of the mandible in 87% of the scans. The lingual foramen was definitely visible in 81% of the scans. CONCLUSIONS The high detection rate of the incisive canal and the lingual foramen in the anterior region of the mandible using CBCT indicates the potential high preoperative value of CBCT scan for surgical procedures in the anterior mandible.

Development and applicability of a quality control phantom for dental cone‐beam CT

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. PACS numbers: 87.57.C‐, 87.57.N‐, 87.57.Q‐

Treatment of periodontal endosseous defects with platelet-rich plasma alone or in combination with demineralized freeze-dried bone allograft: a comparative clinical trial.

BACKGROUND Platelet-rich plasma (PRP) alone or combined with other regenerative materials was previously studied in human periodontal endosseous defects. There are no sufficient data evaluating to what extent the addition of demineralized freeze-dried bone allograft (DFDBA) to PRP may enhance the effectiveness of PRP. The aim of this randomized, double-masked, controlled clinical trial was to compare the effectiveness of autologous PRP alone to PRP + DFDBA in periodontal endosseous defects. METHODS Twenty-four proximal endosseous defects in 24 patients with severe chronic periodontitis were randomly treated with PRP alone or in combination with DFDBA. The final evaluation at 6 months was based on clinical and radiographic parameters. Subtraction radiography was used. The primary outcome variable was clinical attachment level (CAL). RESULTS The two treatment groups were initially comparable (mean CAL: 8.67 +/- 2.19 mm for PRP + DFDBA and 8.25 +/- 1.96 mm for PRP). Both treatments achieved statistically significant and similar CAL gain (3.08 +/- 1.17 mm for PRP + DFDBA and 3.08 +/- 0.95 mm for PRP), probing depth, defect depth, and area surface reduction. The percentage of defect fill did not significantly differ between the two treatments. There was a non-significant trend to greater defect fill (45.42% versus 41.29%), defect depth (54.05% versus 49.52%), and area surface (58.43% versus 52.16%) reduction with the graft. In both groups, 66.66% of the defects gained > or =3 mm of CAL. CONCLUSION Within its limits, this study demonstrates that both PRP and PRP combined with DFDBA resulted in significant clinical and radiographic improvement in human periodontal endosseous defects at 6 months, and the addition of DFDBA to PRP did not significantly enhance the treatment outcome.

Radiation dose reduction in direct digital panoramic radiography

OBJECTIVES (a) To measure the absorbed radiation doses at 16 anatomical sites of a Rando phantom and (b) to calculate the effective doses including and excluding the salivary gland doses in panoramic radiography using a conventional and a digital panoramic device. STUDY DESIGN Thermoluminescent dosimeters (TLD-100) were placed at 16 sites in a Rando phantom, using a conventional, Planmeca Promax and a digital, Planmeca PM2002CC Proline 2000 (Planmeca Oy, 00880 Helsinki, Finland) panoramic device for panoramic radiography. During conventional radiography the selected exposure settings were 66 kVp, 6 mA and 16s, while during digital radiography two combinations were selected 60 kVp, 4 mA, 18 s and 66 kVp, 8 mA, 18s with and without image processing function. The dosimeters were annealed in a PTW-TLDO Harshaw oven. TLD energy response was studied using RQN beam narrow series at GAECs Secondary Standard Calibration Laboratory. The reader used was a Harshaw, 4500. Effective dose was estimated according to ICRP(60) report (E(ICRP60)). An additional estimation of the effective dose was accomplished including the doses of the salivary glands (E(SAL)). A Wilcoxon signed ranks test was used for statistical analysis. RESULTS The effective dose, according to ICRP report (E(ICRP60)) in conventional panoramic radiography was 17 microSv and E(SAL) was 26 microSv. The respective values in digital panoramic radiography were E(ICRP60)=23 microSv and E(SAL)=38 microSv; while using the lowest possible radiographic settings E(ICRP60) was 8 microSv and E(SAL) was 12 microSv. CONCLUSIONS The effective dose reduction in digital panoramic radiography can be achieved, if the lowest possible radiographic settings are used.

The relationship between osteoporosis and periodontitis in women aged 45–70 years

OBJECTIVE To explore the possible relationship between the osteoporotic condition and the severity of periodontitis in women aged 45-70 years. MATERIALS AND METHODS Ninety women with generalized chronic periodontitis, aged 45-70 years, were studied. Areal bone mineral density (BMDa) was assessed using standardized dual energy X-ray absorptiometry (normal: T-score ≥ -1, osteopenic: -2.5 ≤ T-score <-1, osteoporotic: T-score < -2.5). Gingival index (GI), bleeding on probing, clinical attachment loss (CAL), probing pocket depth and gingival recession (GR) were recorded. Periodontitis severity was represented by CAL. Menopausal condition and smoking were documented. RESULTS Mean GI, bleeding on probing, CAL and GR were significantly greater for osteoporotic women than women with normal BMDa (P = 0.002, P = 0.01, P = 0.04, respectively). Osteopenic women and women with normal BMDa significantly differed in mean GI (P = 0.02). The associations found between osteoporotic women and women with normal BMDa and the associations found between osteopenic women and women with normal BMDa existed even after adjusting for smoking and menopausal status. CONCLUSION Subjects with osteoporosis (OPR) presented with greater CAL than the subjects with normal BMDa, which suggests a greater severity of periodontitis. Subjects with OPR had greater GR than the subjects with normal BMDa. Subjects with osteopenia and subjects with normal BMDa did not differ in CAL, which might suggest that the early diagnosis of reduced BMDa, prior to the establishment of a significant negative impact on the periodontal tissues, might be important. Smoking and menopausal status did not alter these associations.

Localized jaw enlargement in renal osteodystrophy: Report of a case and review of the literature

Renal osteodystrophy is a common long-term complication of end-stage renal disease. Involvement of the jaws is common and radiographic alterations are often one of the earliest signs of chronic renal disease. However, marked enlargement of the jaws is a rare complication of renal osteodystrophy. A case of localized asymptomatic enlargement of the mandible in a 38-year-old woman with chronic renal failure is presented. The clinical, radiographic, and histological findings were consistent with renal osteodystrophy. To our knowledge, this is the third case of localized mandibular enlargement of renal osteodystrophy reported in the English-language literature.