Publications by authors named "Azin Parsa"

14 Publications

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Comparison of anterior and posterior trabecular bone microstructure of human mandible using cone-beam CT and micro CT.

BMC Oral Health 2021 05 8;21(1):249. Epub 2021 May 8.

Department of Oral and Maxillofacial Radiology, Academic Center for Dentistry Amsterdam (ACTA), Louwesweg 1, 1066 EA, Amsterdam, The Netherlands.

Background: The aim of this study was to compare the trabecular bone microstructures of anterior and posterior edentulous regions of human mandible using cone-beam computed tomography (CBCT) and micro computed tomography (µCT).

Methods: Twenty volumes of interests consisting of six anterior and fourteen posterior edentulous regions were obtained from human mandibular cadavers. A CBCT system with a resolution of 80 µm (3D Accuitomo 170, J. Morita, Kyoto, Japan) and a µCT system with a resolution of 35 µm (SkyScan 1173, Kontich, Belgium) were used to scan the mandibles. Three structural parameters namely, trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp) were analysed using CTAn software (v 1.11, SkyScan, Kontich, Belgium). For each system, the measurements obtained from anterior and posterior regions were tested using independent sample t-test. Subsequently, all measurements between systems were tested using paired t-test.

Results: In CBCT, all parameters of the anterior and posterior mandible showed no significant differences (p > 0.05). However, µCT showed a significant different of Tb.Th (p = 0.023) between anterior and posterior region. Regardless of regions, the measurements obtained using both imaging systems were significantly different (p ≤ 0.021) for Tb.Th and Tb.N.

Conclusions: The current study demonstrated that only the variation of Tb.Th between anterior and posterior edentulous region of mandible can be detected using µCT. In addition, CBCT is less feasible than µCT in assessing trabecular bone microstructures at both regions.
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http://dx.doi.org/10.1186/s12903-021-01595-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8106860PMC
May 2021

Development of a Radiographic Index for Periodontitis.

Dent J (Basel) 2021 Feb 7;9(2). Epub 2021 Feb 7.

School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, UK.

The use of radiographic indices is noticeably diminished due to the lack of simplicity and standardisation among the existing ones. The aim of this study was to introduce a radiographic index to aid clinicians in determining the extent and severity of interproximal alveolar bone loss (iABL), in relation to individual root lengths, among patients suffering from periodontitis. A retrospective analysis of 50 anonymised dental panoramic tomograms (DPTs) of patients with periodontitis was conducted. Visual interpretation of iABL was recorded by a single investigator and by 20 volunteering clinicians for the 'worst site' in each quintet. Results were compared to a gold standard quantification method. Intra-examiner and inter-examiner agreement were measured using the Kappa coefficient and the intra-class correlation coefficient, respectively. Validity was assessed using Cramér's V test. The mean intra-examiner agreement on the severity and pattern of iABL was 0.808 () and 0.802 (), respectively. A stronger overall inter-examiner agreement was noted when the severity in contrast to the pattern of iABL and presence/absence of furcation involvement were analysed. The statistically significant total mean agreement values from this correlation coefficient were 0.892 and 0.739, respectively. A very strong association between all the visual interpretations carried out by all participants and the gold standard measurements was evident. Within the limitations of this study, the proposed radiographic index may serve as a simple, yet valid and reliable, adjunctive screening tool to further assist clinicians in determining the extent and severity of iABL in patients with periodontitis.
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http://dx.doi.org/10.3390/dj9020019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915110PMC
February 2021

Human jaw joint hypermobility: Diagnosis and biomechanical modelling.

J Oral Rehabil 2018 Oct 19;45(10):783-789. Epub 2018 Jul 19.

Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands.

Patients with hypermobility disorders of the jaw joint experience joint sounds and jerky movements of the jaw. In severe cases, a subluxation or luxation can occur. Clinically, hypermobility disorders should be differentiated from disc displacements. With biomechanical modelling, we previously identified the anterior slope angle of the eminence and the orientation of the jaw closers to potentially contribute to hypermobility disorders. Using cone-beam computed tomography (CBCT), we constructed patient-specific models of the masticatory system to incorporate these aspects. It is not known whether the clinical diagnosis of hypermobility disorders is associated with the prediction of hypermobility by a patient-specific biomechanical model. Fifteen patients and eleven controls, matched for gender and age, were enrolled in the study. Clinical diagnosis was performed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and additional testing to differentiate hypermobility from disc displacements. Forward simulations with patient-specific biomechanical models were performed for maximum opening and subsequent closing of the jaw. This predicted a hypermobility disorder (luxation) or a control (normal closing). We found no association between the clinical diagnosis and predictions of hypermobility disorders. The biomechanical models overestimated the number of patients, yielding a low specificity. The role of the collagenous structures remains unclear; therefore, the articular disc and the ligaments should be modelled in greater detail. This also holds for the fanned shape of the temporalis muscle. However, for the osseous structures, we determined post hoc that the anterior slope angle of the articular eminence is steeper in patients than in controls.
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http://dx.doi.org/10.1111/joor.12689DOI Listing
October 2018

Implant Mandibular Overdentures Retained by Immediately Loaded Implants: A 1-Year Randomized Trial Comparing the Clinical and Radiographic Outcomes Between Mini Dental Implants and Standard-Sized Implants.

Int J Oral Maxillofac Implants 2017 Nov/Dec;32(6):1377-1388

Purpose: The aim of this 1-year randomized trial was to evaluate and compare the clinical and radiographic performance of four immediately loaded mini dental implants (MDIs) and two immediately loaded standard-sized tissue-level (STL) implants, placed in the interforaminal region of the mandible and used to retain mandibular overdentures (IODs) in completely edentulous patients.

Materials And Methods: A total of 50 completely edentulous patients wearing conventional maxillary dentures and complaining about insufficient retention of their mandibular dentures were divided into two groups; 25 patients received four MDIs and 25 patients received two STL implants. The marginal bone loss (MBL) at the mesial and distal sides of each implant was assessed by means of standardized intraoral radiographs after a period of 1 year. Implant success and survival rates were also calculated.

Results: Immediate loading was possible for all patients in the first group. In the second group, an immediate loading protocol could not be applied for 10 patients. These patients were treated with a delayed loading protocol. A mean MBL of 0.42 ± 0.56 mm for the MDIs and 0.54 ± 0.49 mm for the immediately loaded STL implants was recorded at the end of the evaluation period. There was no statistically significant difference between the MDIs and the immediately loaded STL implants. Two MDIs failed, resulting in a survival rate of 98%. The success rate was 91%. For the immediately loaded conventional implants, the survival rate was 100% and the success rate 96.7% after 1 year of function. However, in 10 patients, the immediate loading protocol could not be followed.

Conclusion: Considering the limitations of this short-term clinical study, immediate loading of four unsplinted MDIs or two splinted STL implants to retain mandibular overdentures seems to be a feasible treatment option. The marginal bone level changes around the MDIs were well within the clinically acceptable range.
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http://dx.doi.org/10.11607/jomi.5981DOI Listing
May 2018

Can gray values derived from CT and cone beam CT estimate new bone formation? An in vivo study.

Oral Maxillofac Surg 2018 Mar 31;22(1):13-20. Epub 2017 Oct 31.

Department of Oral Radiology, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Objectives: The main aim of this study was to investigate whether Hounsfield unit derived from computed tomography (HU/CT) and gray value derived from cone beam computed tomography (GV/CBCT) can predict the amount of new bone formation (NBF) in the defects after bone reconstruction surgeries.

Materials And Methods: Thirty calvaria defects created in 5 rabbits and grafted with both radiolucent (RL, n = 15) and radiopaque (RO, n = 15) bone substitute materials were evaluated, 8 weeks postoperatively. The defects were scanned by multislice computed tomography (Somatom®, Siemens Healthineers, Erlangen, Germany) and CBCT (NewTom VG®, Qualitative Radiology, Verona, Italy). MSCT and CBCT scans were matched to select the exact region of interest (ROI, diameter = 5 mm and height = 1 mm). HU/CT and GV/CBCT of each ROI were obtained. Mean amount of NBF in whole of the defects was measured using serial histomorphometric assessment. We investigated the correlation between HU/CT and GV/CBCT, HU/CT and NBF, and GV/CBCT and NBF generally, and separately among the RL or RO grafted defects, by linear generalized estimating equation modeling. Receiver operation characteristic analysis was performed to check the accuracy of HU/CT and GV/CBCT in diagnosing more than 10% NBF in the samples.

Results: There were linear correlations between HU/CT and GV/CBCT, HU/CT and NBF, and GV/CBCT and NBF.

Conclusion: According to the results, both HU/CT and GV/CBCT can be considered as fairly good predictors for assessment of the amount of NBF following bone reconstruction surgeries.
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http://dx.doi.org/10.1007/s10006-017-0657-7DOI Listing
March 2018

A Pilot Study on Mandibular Overdentures Retained By Mini Dental Implants: Marginal Bone Level Changes and Patient-Based Ratings of Clinical Outcome.

Int J Oral Maxillofac Implants 2016 Sep-Oct;31(5):1171-8

Purpose: The aim of this study was to investigate the effect of immediately loaded mini dental implants (MDIs) used to support mandibular overdentures on the peri-implant bone level as well as patients' related levels of satisfaction and quality of life.

Materials And Methods: Four MDIs were placed in the interforaminal region of 10 completely edentulous patients, and the implants were loaded immediately (same day) with an overdenture. Radiographic assessment of the bone loss during a period of 18 months was performed by measuring the bone level changes at the mesial and distal aspects of each implant on panoramic radiographs. At the end of this period, patients' satisfaction level on the visual analog scale (VAS) and oral health-related quality of life was assessed by means of questionnaires.

Results: A mean bone loss of 1.04 mm on the mesial and distal sides was recorded during the 18-month period after loading of the implants. The score for general satisfaction level was 95.67 ± 5.68. Similarly high VAS scores were given by the patients in all other specific items on patient satisfaction. The total score for the Oral Health Impact Profile-20 (OHIP-20) was 34.07 ± 13.90, which was comparable to that recorded in other studies.

Conclusion: The short-term radiographic peri-implant bone level changes of MDIs immediately loaded with overdentures in the edentulous mandible were within the physiologic limits. The patients expressed a high level of satisfaction and oral health-related quality of life with this treatment modality.
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http://dx.doi.org/10.11607/jomi.4339DOI Listing
May 2017

Reliability of three-dimensional measurements of the upper airway on cone beam computed tomography images.

Oral Surg Oral Med Oral Pathol Oral Radiol 2016 Jul 23;122(1):104-10. Epub 2016 Apr 23.

Professor and Chair, Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.

Objectives: The aim of this study was (1) to assess intra- and interobserver reliability of the localization of anatomic landmarks of the upper airway on cone beam computed tomography (CBCT) images; and (2) to assess intra- and interobserver reliability of the three-dimensional measurements of the upper airway based on these landmarks.

Study Design: Fifteen NewTom 5G (QR systems, Verona, Italy) CBCT data sets were randomly selected from the archives of the Department of Oral Radiology, Academic Centre for Dentistry (ACTA) at University of Amsterdam and VU University, Amsterdam, The Netherlands. Three observers localized six anatomic landmarks that are relevant for upper airway analysis twice, with a 10-day interval, using 3Diagnosys software (v5.3.1, 3diemme, Cantu, Italy). Subsequently, the observers performed upper airway volume measurement based on those landmarks twice as well, again with a 10-day interval, using Amira software (v4.1, Visage Imaging Inc., Carlsbad, CA). The upper airway measurements also included the minimum cross-sectional area (CSAmin), location of the CSAmin, and anteroposterior and lateral dimensions of the CSAmin.

Results: Both intraobserver reliability and interobserver reliability were excellent for the localization of the anatomic landmarks of the upper airway (intraclass correlation coefficients = 0.97-1.00) as well as for the three-dimensional upper airway measurements (intraclass correlation coefficients = 0.78-1.00).

Conclusions: The methodology of landmark localization and upper airway measurements, as used in this study, showed an excellent reliability and can thus be recommended for upper airway analysis on CBCT images.
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http://dx.doi.org/10.1016/j.oooo.2016.04.005DOI Listing
July 2016

Accuracy of cone beam computed tomography in following simulated autogenous graft resorption in maxillary sinus augmentation procedure: an ex vivo study.

Dentomaxillofac Radiol 2016 Jul 26;45(6):20160092. Epub 2016 May 26.

1 Department of Implantology and Prosthetic Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, Netherlands.

Objectives:: Maxillary sinus augmentation is a well-documented procedure with long-term success in implant dentistry. Assessing graft volume changes over time is crucial, since resorption remains a major concern. CBCT is commonly employed to assess the quantity and quality of the available bone at the implant receptor site. However, its applicability in following graft volume changes is yet to be determined. The study aimed to assess CBCT accuracy in following simulated graft resorption ex vivo.

Methods:: 4 differently sized autogenous bone blocks harvested from the zygomatic buttress were bilaterally placed in the maxillary sinus of 12 human cadavers. The Accuitomo (J Morita, Kyoto, Japan) CBCT system was employed to scan each one of the 4 grafts in each of the 12 cadavers using identical settings. Gold standard graft measurements were obtained using micro-CT. One independent observer assessed the volume of each graft on CBCT images twice. Intraobserver reliability was assessed using Cohen's kappa and one-sample t-test was used to compare CBCT with micro-CT volumetric measurements.

Results:: The mean micro-CT graft volumes were 97.12 ± 1.4, 197.32 ± 3.4, 361.41 ± 4.2 and 1040.11 ± 3.2 mm for Grafts 1-4, respectively, and the mean CBCT volumes of the corresponding grafts were 115.39 ± 7.01, 205.97 ± 9.91, 404.05 ± 16.81 and 1138.04 ± 20.98 mm. CBCT measurements were statistically significantly different from micro-CT measurements (p = 0.001). Intraobserver reliability was good (r = 0.78).

Conclusions:: In every case, CBCT overestimated the maxillary graft volume in comparison with micro-CT. However, the measurement differences were limited and might not influence clinical performance.
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http://dx.doi.org/10.1259/dmfr.20160092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5124774PMC
July 2016

Cone-beam computed tomographic scans in comparison with periapical radiographs for root canal length measurement: an in situ study.

J Endod 2014 Aug 28;40(8):1206-9. Epub 2014 Mar 28.

Department of Endodontology, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University, Amsterdam, The Netherlands.

Introduction: The primary aim of this study was to compare the precision of root canal length determination on cone-beam computed tomographic (CBCT) scans and periapical radiographs (PAs) with the actual root canal length. The secondary aim was to examine the influence of tooth type on root canal length measurements as assessed on CBCT scans and PAs.

Methods: In total, 40 root canals of 33 teeth (molars, premolars, canines, and incisors) out of 5 dentate maxillas of human cadavers were included. Root canal length measurement was performed by a consensus panel (2 examiners) on CBCT scans (3D Accuitomo 170; J Morita, Kyoto, Japan) and digital PAs. After straight-line access opening, a #15 file was fixated in every root canal at the length measured on CBCT scans. All teeth were extracted, and the root canal containing the file was uncovered. Measurements made on images taken with a digital camera (AxioCam; Carl Zeiss, Sliedrecht, The Netherlands) linked to a stereozoom microscope (Stemi SV6, Carl Zeiss) were used as the actual root canal length.

Results: When all roots were examined together, it was not clear which method is better for all types of teeth. For root canals of anterior teeth, there was no significant difference between the 2 methods. For root canals of posterior teeth, CBCT images gave results significantly closer to the actual root canal length in comparison with PAs (t value = -1.96; critical value is 1.74 with a significance level of 0.05).

Conclusions: Root canal length measurements of posterior maxillary teeth were more accurate when assessed by CBCT images than PAs.
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http://dx.doi.org/10.1016/j.joen.2013.12.036DOI Listing
August 2014

Bone quality evaluation at dental implant site using multislice CT, micro-CT, and cone beam CT.

Clin Oral Implants Res 2015 11;26(1):e1-7. Epub 2013 Dec 11.

Section of Oral Radiology, Department of General and Specialized Dentistry, Academic Center for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands.

Objectives: The first purpose of this study was to analyze the correlation between bone volume fraction (BV/TV) and calibrated radiographic bone density Hounsfield units (HU) in human jaws, derived from micro-CT and multislice computed tomography (MSCT), respectively. The second aim was to assess the accuracy of cone beam computed tomography (CBCT) in evaluating trabecular bone density and microstructure using MSCT and micro-CT, respectively, as reference gold standards.

Material And Methods: Twenty partially edentulous human mandibular cadavers were scanned by three types of CT modalities: MSCT (Philips, Best, the Netherlands), CBCT (3D Accuitomo 170, J Morita, Kyoto, Japan), and micro-CT (SkyScan 1173, Kontich, Belgium). Image analysis was performed using Amira (v4.1, Visage Imaging Inc., Carlsbad, CA, USA), 3Diagnosis (v5.3.1, 3diemme, Cantu, Italy), Geomagic (studio(®) 2012, Morrisville, NC, USA), and CTAn (v1.11, SkyScan). MSCT, CBCT, and micro-CT scans of each mandible were matched to select the exact region of interest (ROI). MSCT HU, micro-CT BV/TV, and CBCT gray value and bone volume fraction of each ROI were derived. Statistical analysis was performed to assess the correlations between corresponding measurement parameters.

Results: Strong correlations were observed between CBCT and MSCT density (r = 0.89) and between CBCT and micro-CT BV/TV measurements (r = 0.82). Excellent correlation was observed between MSCT HU and micro-CT BV/TV (r = 0.91). However, significant differences were found between all comparisons pairs (P < 0.001) except for mean measurement between CBCT BV/TV and micro-CT BV/TV (P = 0.147).

Conclusions: An excellent correlation exists between bone volume fraction and bone density as assessed on micro-CT and MSCT, respectively. This suggests that bone density measurements could be used to estimate bone microstructural parameters. A strong correlation also was found between CBCT gray values and BV/TV and their gold standards, suggesting the potential of this modality in bone quality assessment at implant site.
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http://dx.doi.org/10.1111/clr.12315DOI Listing
November 2016

Volumetric changes in apical radiolucencies of endodontically treated teeth assessed by cone-beam computed tomography 1 year after orthograde retreatment.

J Endod 2013 Dec 15;39(12):1504-9. Epub 2013 Oct 15.

Department of Endodontology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University, Amsterdam, the Netherlands. Electronic address:

Introduction: Cone-beam computed tomography (CBCT) allows us to assess in 3 dimensions the location and size of periapical radiolucencies. We aimed to assess by CBCT scans the volumetric changes of periapical radiolucencies in endodontically treated teeth 1 year after orthograde retreatment.

Methods: Forty-five root-filled teeth with persistent apical periodontitis requiring endodontic orthograde retreatment from 37 individuals were included in the study. The research protocol was approved by the VU University Medical Center Amsterdam ethics committee (2007/265), and the participants signed a letter of consent. We made 2 CBCT scans for every patient, the first one before retreatment and the second one a year later. Two observers measured independently the volume of radiolucencies on CBCT images by using the AMIRA software. The intraclass correlation coefficient was used to evaluate interobserver agreement, and the Wilcoxon signed rank test was used to assess pretreatment and post-treatment volume size.

Results: The intraclass correlation coefficients were 0.994 and 0.998 for the scans before retreatment and 1 year after, respectively. The recall rate was 78% for the teeth and 73% for the patients. The volumetric change in periapical radiolucencies 1 year after retreatment was statistically significant (z = -3.112, P < .005). The volume of periapical radiolucencies reduced in 20 teeth (57%), remained unchanged in 8 (23%), and increased in 7 (20%).

Conclusions: One year after endodontic orthograde retreatment, the volume of periapical radiolucencies reduced significantly in 57% of the teeth.
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http://dx.doi.org/10.1016/j.joen.2013.08.034DOI Listing
December 2013

Accuracy of trabecular bone microstructural measurement at planned dental implant sites using cone-beam CT datasets.

Clin Oral Implants Res 2014 Aug 15;25(8):941-5. Epub 2013 Apr 15.

Department of General and Specialized Dentistry, Section of Oral and Maxillofacial Radiology, Academic Center for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands; Department of General Dental Practice and Oral & Maxillofacial Imaging, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia.

Objective: Cone-beam CT (CBCT) images are infrequently utilized for trabecular bone microstructural measurement due to the system's limited resolution. The aim of this study was to determine the accuracy of CBCT for measuring trabecular bone microstructure in comparison with micro CT (μCT).

Materials And Methods: Twenty-four human mandibular cadavers were scanned using a CBCT system (80 μm) and a μCT system (35 μm). Three bone microstructural parameters trabecular number (Tb.N), thickness (Tb.Th) and separation (Tb.Sp) were assessed using CTAn imaging software.

Results: Intraclass correlation coefficients (ICC) showed a high intra-observer reliability (≥ 0.996) in all parameters for both systems. The Pearson correlation coefficients between the measurements of the two systems were for Tb.Th 0.82, for Tb.Sp 0.94 and for Tb.N 0.85 (all P's<0.001). The Bland and Altman plots showed strongest agreement in Tb.N (-0.37 μm) followed by Tb.Th (1.6 μm) and Tb.Sp (8.8 μm).

Conclusions: Cone-beam CT datasets can be used to evaluate trabecular bone microstructure at dental implant sites. The accuracy for measuring Tb.N was the best followed by Tb.Th and Tb.Sp.
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http://dx.doi.org/10.1111/clr.12163DOI Listing
August 2014

Accuracy of preemptively constructed, cone beam CT-, and CAD/CAM technology-based, individual Root Analogue Implant technique: an in vitro pilot investigation.

Clin Oral Implants Res 2014 May 21;25(5):598-602. Epub 2012 Dec 21.

Department of Oral Function and Restorative Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Research Institute Move, Amsterdam, The Netherlands.

Objectives: The aim of this in vitro pilot investigation is to assess the accuracy of the preemptive individually fabricated root analogue implant (RAI) based on three-dimensional (3D) root surface models obtained from a cone beam computed tomography (CBCT) scan, computer-aided designing (CAD), and computer-aided manufacturing (CAM) technology and to measure the discrepancy in congruence with the alveolar socket subsequent to placement of the RAI.

Materials And Methods: Eleven single-rooted teeth from nine human cadaver mandibles were scanned with the 3D Accuitomo 170 CBCT system. The 3D surface reconstructions of the teeth acquired from the CBCT scans were used as input for fabrication of the RAIs in titanium using rapid manufacturing technology. The teeth were then carefully extracted. The teeth and RAIs were consequently optically scanned. The mandibles with the empty extraction sockets were scanned with CBCT using identical settings to the first scan. Finally, the preemptively made RAIs were implanted into their respective sockets, and the mandibles were again scanned with CBCT using the same scan settings as previous scans. All 3D surface reconstructions (CBCT 3D surface models and optical scan 3D models) were saved for further analysis. 3D models of original teeth and optical scans of the RAIs were superimposed onto each other; differences were quantified as root mean square (RMS) and Hausdorff surface distance. To obtain an estimate of the fit (congruence) of the RAIs in their respective sockets, the volumetric data sets of the sockets were compared with those of the root part of RAIs congruent with the sockets.

Results: Superimposed surfaces of the RAIs and the original tooth reveal discrepancy for RMS, volumetric geometry, and surface area varying from 0.08 mm to 0.35 mm, 0.1% to 7.9%, and 1.1% to 3.8%, respectively. Comparing volume differences of the alveolus with the socket corresponding part of the RAI resulted in every case the volume of the socket being greater than the root part of the RAI ranging from 0.6% to 5.9% volume difference.

Conclusion: The preemptive CAD/CAM-based RAI technique might offer promising features for immediate implant placement. However, due to the lack of prospective clinical data, further research is needed to fine-tune and evaluate this technique.
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http://dx.doi.org/10.1111/clr.12104DOI Listing
May 2014

Reliability of voxel gray values in cone beam computed tomography for preoperative implant planning assessment.

Int J Oral Maxillofac Implants 2012 Nov-Dec;27(6):1438-42

Department of General and Specialized Dentistry, Academic Center for Dentistry Amsterdam, Amsterdam, The Netherlands.

Purpose: To assess the reliability of cone beam computed tomography (CBCT) voxel gray value measurements using Hounsfield units (HU) derived from multislice computed tomography (MSCT) as a clinical reference (gold standard).

Materials And Methods: Ten partially edentulous human mandibular cadavers were scanned by two types of computed tomography (CT) modalities: multislice CT and cone beam CT. On MSCT scans, eight regions of interest (ROI) designating the site for preoperative implant placement were selected in each mandible. The datasets from both CT systems were matched using a three-dimensional (3D) registration algorithm. The mean voxel gray values of the region around the implant sites were compared between MSCT and CBCT.

Results: Significant differences between the mean gray values obtained by CBCT and HU by MSCT were found. In all the selected ROIs, CBCT showed higher mean values than MSCT. A strong correlation (R=0.968) between mean voxel gray values of CBCT and mean HU of MSCT was determined.

Conclusions: Voxel gray values from CBCT deviate from actual HU units. However, a strong linear correlation exists, which may permit deriving actual HU units from CBCT using linear regression models.
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July 2013
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