| 1. |
- Al-Okshi, Ayman, et al.
(författare)
-
Dose optimization for assessment of periodontal structures in cone beam CT examinations
- 2016
-
Ingår i: Dento-Maxillo-Facial Radiology. - : British institute of radiology. - 0250-832X .- 1476-542X. ; 46:3
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate the relationship between dose and image quality for a dedicated dental CBCT scanner using different scanning protocols and to set up an optimal imaging protocol for assessment of periodontal structures. METHODS: Radiation dose and image quality measurements were made using 3D Accuitomo 170 (J. Morita, Kyoto, Japan) dental CBCT scanner. The SedentexCT IQ phantom was used to investigate the relationship between contrast-to-noise ratio (CNR) and dose-area product. Subjective image quality assessment was achieved using a small adult skull phantom for the same range of exposure settings. Five independent observers assessed the images for three anatomical landmarks using a three-point visual grade analysis. RESULTS: When correlating the CNR of each scanning protocol to the exposure parameters used to obtain it, CNR decreased as these parameters decreased, especially current-exposure time product. When correlating to subjective image quality, the CNR level remained acceptable when 5 mA and 17.5 s or greater was selected and 80 kV could be used without compromising the CNR. CONCLUSIONS: For a dedicated CBCT unit, changing the rotation angle from 360 degrees to 180 degrees degrades image quality. By altering tube potential and current for the 360 degrees rotation protocol, assessment of periodontal structures can be performed with a smaller dose without substantially affecting visualization.
|
|
| 2. |
- Al-Okshi, Ayman, et al.
(författare)
-
Effective dose of cone beam computed tomography (CBCT) of the facial skeleton : a systematic review
- 2015
-
Ingår i: British Journal of Radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 88:1045
-
Forskningsöversikt (refereegranskat)abstract
- Objective: To estimate effective dose of cone beam CT (CBCT) of the facial skeleton with focus on measurement methods and scanning protocols. Methods: A systematic review, which adhered to the preferred reporting items for systematic reviews (PRISMA) Statement, of the literature up to April 2014 was conducted. Data sources included MEDLINE®, The Cochrane Library and Web of Science. A model was developed to underpin data extraction from 38 included studies. Results: Technical specifications of the CBCT units were insufficiently described. Heterogeneity in measurement methods and scanning protocols between studies made comparisons of effective doses of different CBCT units and scanning protocols difficult. Few studies related doses to image quality. Reported effective dose varied across studies, ranging between 9.7 and 197.0 mSv for field of views (FOVs) with height #5cm, between 3.9 and 674.0 mSv for FOVs of heights 5.1–10.0 cm and between 8.8 and 1073.0 mSv for FOVs .10 cm. There was an inconsistency regarding reported effective dose of studies of the same CBCT unit with the same FOV dimensions. Conclusion: The review reveals a need for studies on radiation dosages related to image quality. Reporting quality of future studies has to be improved to facilitate comparison of effective doses obtained from examinations with different CBCT units and scanning protocols. A model with minimum data set on important parameters based on this observation is proposed. Advances in knowledge: Data important when estimating effective dose were insufficiently reported in most studies. A model with minimum data based on this observation is proposed. Few studies related effective dose to image quality.
|
|
| 3. |
- Al-Okshi, Ayman, et al.
(författare)
-
Measurability and reliability of assessments of root length and marginal bone level in cone beam CT and intraoral radiography : a study of adolescents
- 2019
-
Ingår i: Dento-Maxillo-Facial Radiology. - : British Institute of Radiology. - 0250-832X .- 1476-542X. ; 48:5, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To evaluate measurability and reliability of measurements of root length and marginal bone level in CBCT, periapical (PA) and bitewing (BW) radiographs. Methods: CBCT of both jaws, PA of maxillary incisors and posterior BW radiographs of 10 adolescents (mean age 13.4) were selected. The radiographs comprised part of the baseline examinations of a trial of orthodontic treatment. Six raters assessed measurability and measured root length and marginal bone level. Three raters repeated their assessments. Measurability was expressed as frequency of interpretable sites and reliability as intraclass correlation coefficient (ICC). Results: Measurability was 100 % in CBCT and 95 % in PA of maxillary incisors for root length measurements. For marginal bone level, measurability was 100 % in CBCT, 76 % in PA and 86 % in posterior BW. Mean ICC for interrater reliability for root length measurements in CBCT was 0.88 (range 0.27-0.96 among different teeth) and 0.69 in PA of maxillary incisors. For marginal bone level measurements, mean ICC was 0.4 in CBCT, 0.38 in PA of maxillary incisors and 0.4 in posterior BW. Intrarater reliability varied among methods, root length or marginal bone level and among raters, except for root length measurements in CBCT, which presented high reliability (above 0.8) for all raters. Conclusions: As measurability and reliability were high for root length measurements in CBCT, this may be the method of choice for scientific analyses in orthodontics. For clinical praxis, we recommend PA following the "as low as diagnostically acceptable" principle, as clinical decisions seem to be influenced only when severe root resorption occurs.
|
|
| 4. |
- Al-Okshi, Ayman, et al.
(författare)
-
Using GafChromic film to estimate the effective dose from dental cone beam CT and panoramic radiography
- 2013
-
Ingår i: Dento-Maxillo-Facial Radiology. - : British Institute of Radiology. - 0250-832X .- 1476-542X. ; 42:7
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To demonstrate the feasibility of GafChromic(®) XR-QA2 (ISP Corp., Wayne, NJ) as a dosemeter when performing measurements of the effective dose from three cone beam CT (CBCT) units and to compare the doses from examinations of three common dental clinical situations. A second aim was to compare the radiation doses for three digital panoramic units with the doses for the CBCT units. METHODS: The CBCT units used were Veraviewepocs 3De(®) (J Morita MFG Corp., Kyoto, Japan), ProMax(®) 3D (Planmeca, Helsinki, Finland) and NewTom VGi(®) (Quantitative Radiology, Verona, Italy). GafChromic XR-QA2 films were placed between the selected layers of the head and neck of a tissue-equivalent human skull (RANDO(®) phantom; The Phantom Laboratory, Salem, NY). The exposure parameters were set using the automatic exposure control function of the units. Depending on the availability, medium and smaller field of view (FOV) scanning modes were used. The effective dose was estimated using the 2007 International Commission on Radiological Protection formalism. RESULTS: The lowest effective dose of a CBCT unit was observed for ProMax 3D, FOV 4 × 5 cm (10 μSv), the highest for NewTom VGi, FOV 8 × 8 cm-high resolution (129 μSv). The range of effective doses for digital panoramic machines measured was 8-14 μSv. CONCLUSIONS: This study demonstrates the feasibility of using radiochromic films for dental CBCT and panoramic dosimetry.
|
|
| 5. |
- Allen, P Danny, et al.
(författare)
-
Detecting reduced bone mineral density from dental radiographs using statistical shape models
- 2007
-
Ingår i: IEEE transactions on information technology in biomedicine. - : Institute of Electrical and Electronics Engineers (IEEE). - 1089-7771 .- 1558-0032. ; 11:6, s. 601-610
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Bergkvist, Göran, et al.
(författare)
-
Bone Density at Implant Sites and Its Relationship to Assessment of Bone Quality and Treatment Outcome
- 2010
-
Ingår i: INTERNATIONAL JOURNAL OF ORAL and MAXILLOFACIAL IMPLANTS. - : Quintessence Publishing Co, Inc. - 0882-2786 .- 1942-4434. ; 25:2, s. 321-328
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate the relationship between bone mineral density (BMD) before implant placement, implant stability measures at implant placement, and marginal bone loss of immediately loaded implants after 1 year in situ. Materials and Methods: Consecutively recruited patients received Straumann SLActive implants loaded with fixed provisional prostheses within 24 hours. BMD was measured from computed tomographic images before implant placement. Alveolar bone quality was assessed during surgery. Implant stability-both rotational and as measured with resonance frequency analysis- and marginal bone height were assessed at implant placement and after 1 year. The Pearson correlation coefficient was used to calculate correlations, and significance was considered when P andlt; .05. Results: Twenty-one patients received 137 implants (87 in maxillae and 50 in mandibles). BMD was significantly correlated with bone quality classification in both arches (P andlt; .001). Mean BMD was also significantly correlated with stability values (P andlt; .001). Mean marginal bone loss at implant surfaces differed, but not significantly, at the 1-year follow-up, regardless of BMD values (P = .086) and measured stability (rotational stability P = .34, resonance frequency analysis P = .43) at implant placement. Conclusion: Within the limits of this study, it can be concluded that computed tomographic examination can be used as a preoperative method to assess jawbone density before implant placement, since density values correlate with prevailing methods of measuring implant stability. However, in the short time perspective of 1 year, there were no differences in survival rates or changes in marginal bone level between implants placed in bone tissue of different density.
|
|
| 7. |
- Bergkvist, Goran, et al.
(författare)
-
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
- 2009
-
Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899 .- 1708-8208. ; 11:1, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- 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. 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. 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%. 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.
|
|
| 8. |
- Bergkvist, G, et al.
(författare)
-
Immediate loading of implants with interim fixed prostheses in edentulous maxillas and mandibles. A 2 year prospective clinical and radiological follow-up
- 2009
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background and aim: An increasing number of studies show that one-stage surgery and immediate loading of implants, in both edentulous mandibles and maxillae, is a treatment alternative with success rates comparable with two stage-surgery and conventional loading. Furthermore, the development of new implant surfaces has shortened the healing time after implant placement. Such a new surface texture is the sand-blasted, large-grit and acid-etched, active surface (SLActive). Using implants with a shortened healing period is presumably advantageous when immediate loading implants. The aim of the study was to prospectively evaluate the survival rate of splinted and immediately loaded SLActive implants in edentulous mandibles and maxillae after 2 years of loading. Materials and methods Thirty-three patients (mean age 70 yr) with 23 edentulous maxillae and 14 edentulous mandibles received 6 implants each in maxillae and 5 in mandibles respectively, and an implant-supported fixed interim prosthesis within 24 hours after surgery. After a mean healing time of 15 weeks the patients received a permanent screw-retained implant supported fixed prosthesis. A total of 204 Straumann Standard Plus SLActive implants were placed. Bone quality and jaw shape were classified according to Lekholm and Zarb (1985). Implant stability was measured with Resonance Frequency Analysis at placement, after 2, 4 and 8 weeks and at the one year follow-up. Implant rotational stability was measured with a torque control device at placement and after one year. Radiological examinations and assessments were made at implant installation and after one and two years. Results Mean marginal bone level at baseline for implants placed in maxillae were measured at a point 1.74 (SD 0.94) apical of the reference point (the implant shoulder) and in mandibles 1.73 (SD 1.23). Change in mean marginal bone level from baseline to the 1-year follow-up was 1.18 mm (SD 0.98) in maxillae and 1.15 (SD 1.23) in mandibles. For almost 80% of the implant surfaces marginal bone loss was ≤ 1 mm. The cumulative implant survival rate was 100% after one and two years respectively. Conclusion Straumann Standard Plus SLActive implants immediately loaded within 24 hours, in combination with fixed cross-arch prostheses, had successful survival rate and is a viable treatment alternative.
|
|
| 9. |
- Bergkvist, Göran, et al.
(författare)
-
Immediately loaded implants supporting fixed prostheses in the edentulous maxilla : A preliminary clinical and radiologic report
- 2005
-
Ingår i: International Journal of Oral & Maxillofacial Implants. - 0882-2786 .- 1942-4434. ; 20:3, s. 399-405
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate the survival rate of immediately loaded ITI sand-blasted, large-grit, acid-etched (SLA) solid-screw dental implants in the edentulous maxilla after 8 months of loading. Materials and Methods: Twenty-eight patients (mean age 63 years) with edentulous maxillae each received 6 implants and 1 implant-supported fixed provisional prosthesis within 24 hours after surgery. After a mean healing time of 15 weeks, the patient received a definitive, screw-retained, implant-supported fixed prosthesis. A total of 168 implants were placed. Clinical parameters were registered after 1 month of loading with the implant-supported fixed prostheses as well as 8 months after implant place ment. Radiologic examinations and assessments were made at implant placement and after 8 months. Results: The mean marginal bone level at implant placement was 1.6 mm (range 0 to 5.1, SD 1.1) apical of the reference point (the implant shoulder). The mean marginal bone level at the 8-month follow-up was 3.2 mm (range 0.4 to 5.9, SD 1.1) apical of the reference point. Three implants failed during the healing period. Discussion: The improved results in the present study might be a result of the positive effect of splinting the implants immediately after placement Conclusion: ITI SLA solid-screw implants immediately loaded (ie, loaded within 24 hours of placement) and supporting fixed prostheses had successful survival rates after 8 months. The present results constitute a solid base line for future follow-up studies.
|
|
| 10. |
- Bergkvist, Göran, et al.
(författare)
-
Implant-supported Fixed Prostheses in the Edentulous Maxilla. A 2-year Clinical and Radiological Follow-up of Treatment with Non-submerged ITI Implants
- 2004
-
Ingår i: Clinical Oral Implants Research. - : Wiley. - 0905-7161 .- 1600-0501. ; 15:3, s. 351-359
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVES: To evaluate the survival rate of non-submerged solid-screw ITI dental implants with a rough (titanium plasma sprayed, TPS) surface in the edentulous maxilla after 1 and 2 years of loading. MATERIAL AND METHOD: Twentyfive patients (mean age 64 years) with edentulous upper jaws received five-seven implants and, after a mean healing time of 6.9 months, screw-retained implant-supported fixed prostheses. A total of 146 ITI solid screw TPS implants were inserted. The diameter of 56% of the implants was smaller (3.3 mm) than the standard (4.1 mm) and the diameter of the rest (44%) was standard. The bone quantity of the majority of the patients was low and the bone quality poor. Clinical parameters were registered at baseline and at two annual follow-ups. Radiological examinations and assessments were also made at these times. RESULTS: Mean marginal bone level at baseline was measured at a point 4.52 mm (range 1.45-7.70, SD 1.2) apical of the reference point. Mean bone loss from baseline to 1 year of loading was 0.24 mm (SD 0.9, P=0.002) and from 1 year to 2 years of loading 0.15 mm (SD 0.4, P<0.001). Five implants failed, four of which were early failures prior to loading. One implant failed shortly after bridge installation. The cumulative survival rate was 96.6% after 1 and 2 years. CONCLUSION: ITI TPS solid-screw implants in combination with fixed prostheses had successful survival rates and were found to be a viable treatment alternative in the edentulous maxilla.
|
|
