Mean Volume Loss Research Articles

Volumetric Analysis of Peri-implant Tissue Change Over Time: Validating an Innovative 3D Method.

To validate an innovative 3D volumetric method of evaluating tissue changes proposed by Lee et al in 2020 by comparing the results of this method-in which the scanned peri-implant surfaces were transformed, visualized, and analyzed as 3D objects-to the results reported by an existing method based on calculation of the mean distance between measured surfaces. The null hypothesis was that there was no statistically significant difference between the two methods. Additionally, the present study evaluated peri-implant tissue changes 5 years after single implant placement in the esthetic zone. Both methods were applied to 11 oral implant site casts (6 maxillary central incisor sites, 5 maxillary lateral incisor sites) taken from 11 patients at crown placement and at follow-up examinations 5 years later. The methods are based on digital workflows in which the reference and 5-year casts are scanned and the resulting STL files are superimposed and analyzed for three regions of interest (mesial papilla, central area, and distal papilla). The volumetric changes reported by the Lee et al method and the mean distance method were calculated and compared using the Spearman rank correlation coefficient (P < .01) and the Wilcoxon signed-rank test (P < .05). The correlation between the two sets of measurements was very high (Spearman rank correlation coefficient = 0.885). The new volumetric method indicated a mean volume loss of 2.82 mm3 (SD: 5.06), while the method based on the measurement of mean distance showed a mean volume loss of 2.92 mm3 (SD: 4.43; Wilcoxon signed-rank test result: P = .77). No statistically significant difference was found. The two methods gave equivalent results, and the null hypothesis was accepted. The new volumetric method was validated and can be considered a trustworthy tool.

Weekly assessment of volumetric and dosimetric changes during volumetric modulated arc therapy of locally advanced head and neck carcinoma: Implications for adaptive radiation therapy-A prospective study.

Chemoradiation in head and neck carcinoma (HNC) shows significant anatomical resulting in erroneous dose deposition in the target or the organ at risk (OAR). Adaptive radiotherapy (ART) can overcome this. Timing of significant target and OAR changes with dosimetric impact; thus, most suitable time and frequency of ART is unclear. This dosimetric study used prospective weekly non-contrast CT scans in 12 HNC patients (78 scans). OARs and TVs were manually contoured after registration with simulation scan. Dose overlay done on each scan without reoptimization. Dosimetric and volumetric variations assessed. Commonest site was oropharynx. Gross Tumor Volume (GTV) reduced from 47.5 ± 19.2 to 17.8 ± 10.7 cc. Nodal GTV reduced from 15.7 ± 18.8 to 4.7 ± 7.1 cc. Parotid showed mean volume loss of 35%. T stage moderately correlated with GTV regression. Maximum GTV changes occurred after 3 weeks. Best time to do single fixed interval ART would be by the end of 3 weeks.

Degrees of Testicular Atrophy Following Orchidopexy for Testicular Torsion.

Introduction Testicular torsion is an urological emergency. It is a time-sensitive condition in which twisting of the spermatic cord and testicular blood supply occurs, causing acute onset severe scrotal pain. The incidence of testicular torsion is highest amongst prepubertal males; however, it can occur at any age. Every hour that passes from the onset of symptoms has been shown to decrease the salvageability rate of the torted testis. Another significant factor that impacts testicular salvage is the degree of torsion. Prompt surgical exploration of the scrotum and orchidopexy, if the testis is salvageable, is the mainstay of treatment. A major sequela following orchidopexy for torsion is the decrease in testicular volume. The aim of this study is to assess testicular volume loss post orchidopexy in patients who presented with testicular torsion, as well as to identify the significance of the degree of rotation and duration of torsion in post-fixation volume loss. Methods This is a retrospective study in which all patients who underwent scrotal exploration for a primary diagnosis of testicular torsion between June 1, 2016, to January 15, 2023, were reviewed. The information obtained included the patients' demographics such as age, duration of symptoms, and laterality. Ultrasound images were reviewed for pre- and postoperative findings which included confirmation of testicular torsion as well as testicular volume measurements. Patients were excluded if they underwent an orchidectomy, had a diagnosis other than testicular torsion once scrotal exploration was done, or did not perform a follow-up scrotal ultrasound. Additionally, patients who underwent an orchidopexy for undescended testis earlier in life were also excluded. For statistical analysis purposes, degrees of testicular torsion and time to surgery were classified into mild, moderate, and severe. Results A total of 109 patient records were reviewed within the specific time frame. Of these, 47 patients were excluded as per the exclusion criteria mentioned previously, which gave us a sample size of 62 patients. Our findings showed that increasing severity of the degree of torsion as well as the time for surgery have statistically significant (p-value <0.05) effects on postoperative testicular volume loss. However, it was noted that time to surgery has a more pronounced effect on the mean volume loss than the degree of torsion. Moreover, the analysis also showed that, on average, with every additional hour from the onset of symptoms to surgery, the approximate volume loss is 0.15 ml. However, once time exceeds the 4.5-hour mark, the mean volume loss is 0.4 ml for each additional hour. Conclusion The current study indicates that earlier surgical intervention and correction of torsion are associated with enhanced preservation of postoperative testicular volume. Both the degree of torsion and time to surgery influence mean volume loss; however, time to surgery has a greater impact on the mean volume loss. These results highlight the importance of early diagnosis and intervention in cases of testicular torsion to minimize the risk of long-term testicular volume loss.

Using Goldmann Visual Field Volume to Track Disease Progression in Choroideremia

Choroideremia is an X-linked choroidopathy caused by pathogenic variants in the CHM gene. It is characterized by the early appearance of multiple scotomas in the peripheral visual field that spread and coalesce, usually sparing central vision until late in the disease. These features make quantitative monitoring of visual decline particularly challenging. Here, we describe a novel computational approach to convert Goldmann visual field (GVF) data into quantitative volumetric measurements. With this approach, we analyzed visual field loss in a longitudinal, retrospective cohort of patients with choroideremia. Single-center, retrospective, cohort study. We analyzed data from 238 clinic visits of 56 molecularly-confirmed male patients with choroideremia from 41 families (range, 1-27 visits per patient). Patients had a median follow up of 4 years (range, 0-56 years) with an age range of 5 to 76 years at the time of their visits. Clinical data from molecularly-confirmed patients with choroideremia, including GVF data, were included for analysis. Goldmann visual fieldrecords were traced using a tablet-based application, and the 3-dimensional hill of vision was interpolated for each trace. This procedure allowed quantification of visual field loss from data collected over decades with differing protocols, including different or incomplete isopters. Visual acuity (VA) data were collected and converted to logarithm of the minimum angle of resolution values. A delayed exponential mixed-effects model was used to evaluate the loss of visual field volume over time. Visual acuity and GVF volume. The estimated mean age at disease onset was 12.6 years (standard deviation, 9.1 years; 95% quantile interval, 6.5-36.4 years). The mean field volume loss was 6.8% per year (standard deviation, 4.5%; 95% quantile interval, 1.9%-18.8%) based on exponential modeling. Field volume was more strongly correlated between eyes (r2=0.935) than best-corrected VA (r2=0.285). Volumetric analysis of GVF data enabled quantification of peripheral visual function in patients with choroideremia and evaluation of disease progression. The methods presented here may facilitate the analysis of historical GVF data from patients with inherited retinal disease and other diseases associated with visual field loss. This work informs the creation of appropriate outcome measures in choroideremia therapeutic trials, particularly in trial designs. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Three-Dimensional Peri-Implant Tissue Changes in Immediately vs. Early Placed Tapered Implants Restored with Two Different Ceramic Materials-1 Year Results.

A prospective multi-center randomized controlled clinical trial was performed to digitally analyze tissue volume changes in immediately and early placed implants with simultaneous bone augmentation restored with two different all-ceramic materials. A total of 60 patients received 60 bone-level tapered implants (BLT, Straumann AG) immediately (n = 30) or early placed, 8-10 weeks after tooth extraction, (n = 30). Implants were restored with all-ceramic single crowns fabricated out of zirconia (Lava Plus, 3M), or lithium disilicate (E.max CAD, Ivoclar Vivadent AG) bonded to titanium base abutments (Variobase for Cerec, Straumann AG). Impressions were taken at baseline (BL), 6 and 12 months, and STL data were used to define an area of interest (AOI) to analyze peri-implant volume changes and midfacial recessions. For immediate placement, a mean volume loss of -5.56 mm3 (±5.83 mm3) was found at 6 months, and of -6.62 mm3 (±6.56 mm3) at 12 months. For early placement, a mean volume loss of -1.99 mm3 (±5.82 mm3) at 6 months, and of -3.7 mm3 (±5.62 mm3) at 12 months was found. The differences in volume loss at 12 months between the two implant placement protocols were significant (p = 0.005). In both groups, mean midfacial recessions of 0.48 mm (±0.52) occurred. A more pronounced peri-implant volume loss can be expected 12 months after immediate implant placement compared with early placement.

Dimensional Alterations Following Immediate Implant Placement Using the Socket-Shield Technique in the Anterior Maxilla: A Case Series

Tissue volume loss after tooth extraction is an esthetic challenge. The socket-shield technique (SST) has been used to compensate it with promising results but limited evidence. This prospective study aims to present the dimensional changes after SST. Ten consecutive patients with an anterior hopeless tooth to be extracted and an immediate implant placed using the SST were prospectively enrolled. An impression and a CBCT scan were taken prior to surgery and 6 months later. Models were scanned, and DICOM and STL (standard tessellation language) files were superimposed and analyzed by software to measure the dimensional differences. Five patients could be evaluated for bone alterations and 9 for soft tissue alterations. The mean horizontal shrinkage of the buccal bone plate at 1 mm from the most coronal part was -0.22 ± 0.13 mm in the CBCT analysis. The mean volume loss in the region of interest was -2.94 ± 2.45 mm3, with a mean change in soft tissue contours of -0.49 ± 0.41 mm between pre- and postoperative analysis. SST limited the buccal contour loss after tooth extraction and may be considered a potential option to prevent volume loss in immediate implant placement. Further standardization in the digital measurement method is still needed.

Osteoporosis as a Risk Factor for Intraoperative Complications and Long-term Instrumentation Failure in Patients With Scoliotic Spinal Deformity.

A retrospective review study. This study aims to determine the effect of osteoporosis on spine instrumentation. Osteoporosis is a common skeletal pathology that affects systemic cortical bone maintenance and remodeling. This disease accelerates the degeneration of the spine, often necessitating spinal surgery for progressive vertebral deformity, pathologic fracture, bony canal stenosis, and/or neural element decompression. There is a paucity of literature describing the role of osteoporosis as it relates to both perioperative complications and outcomes after spine fusion surgery. A retrospective review was conducted of a prospectively maintained database for patients undergoing spine surgery between January 1, 2006 and October 3, 2017. Inclusion criteria included age 18 years and above and surgery performed for the correction of thoracolumbar scoliosis. Data collected included various demographic, clinical, and operative variables. A total of 532 patients met inclusion criteria, including 144 (27%) patients with a diagnosis of osteoporosis. Osteoporosis was significantly associated with increased blood volume loss (P=0.003). Postoperatively, osteoporosis was associated with increased rates of instrumentation failure (19% vs. 10%; P=0.008) and the need for revision surgery (33% vs. 16%; P<0.001). Multivariate analysis confirmed osteoporosis to be an independent risk factor for increased mean number of spinal segments fused (P<0.05), mean blood volume loss (P<0.05), rate of postoperative deep venous thrombosis/pulmonary embolism (P<0.05), rate of instrumentation failure (P<0.05), and need for revision surgery (P<0.05). Osteoporosis is a significant risk factor for instrumentation failure and need for revision surgery following arthrodesis for scoliosis correction. Furthermore, patients with osteoporosis have a significantly higher risk of intraoperative blood volume loss and postoperative thromboembolic events.

Associated risk factors with quantitative erosive tooth wear progression

ObjectivesThe aim of this study was to determine predictors of erosive tooth wear (ETW) progression, using novel primary-care quantitative analysis techniques. MethodsIn a single-centre, prospective, observational cohort longitudinal study, adolescents, aged 11–18 years, underwent a baseline BEWE examination, validated risk factors questionnaire and baseline intraoral scan (IOS, TRIOS 3.0, 3Shape, Copenhagen, Denmark). One year later a repeat scan was taken. Quantitative analysis of wear progression (volume loss) on first permanent molars and upper central incisors was performed using previously published protocols. Multilevel linear regression was used to investigate the associations between baseline predictors and volume loss per mm2. ResultsA total of 295 dental surfaces (131 incisors and 164 molars) in 70 patients were analysed for this study. The mean age of participants at baseline was 15.0 years (SD: 0.79), and the average time between scans was 11.8 months (1.61 SD; range 10–13). The mean volume loss per mm2 of dental surfaces was -0.013 mm3 (SD: 0.009). Greater volume loss was observed amongst adolescents with higher baseline BEWE scores and those whose parents had lower education as well as on molar than incisor surfaces. No associations were found with dietary acid intake and intrinsic acid exposure when baseline levels of tooth wear, parental education and other factors were controlled for. ConclusionsThe findings help to characterise groups at greater risk of ETW and would indicate that improved screening and upstream preventative measures should form the basis of a preventative program. Clinical significanceIntra-orals scans and registration software might improve the ability to diagnose, monitor and prevent the early loss of dental hard tissue.

Temporal LiDAR scanning in quantifying cumulative rockfall volume and hazard assessment: A case study at southwestern Saudi Arabia

Rockfalls and unstable slopes pose a serious threat to people and property along roads/highways in the southwestern mountainous regions of Saudi Arabia. In this study, the application of terrestrial light detection and ranging (LiDAR) technology was applied aiming to propose a strategy to analyze and accurately depict the detection of rockfall changes, calculation of rockfall volume, and evaluate rockfall hazards along the Habs Road, Jazan Region, Saudi Arabia. A series of temporal LiDAR scans were acquired at three selected sites. Our results show that these three sites have different degrees of hazard due to their geological differences. The mean volume loss of sites A1, A2, and A3 is 327.1, 424.4, and 3.7 L, respectively. Statistical analysis confirms the significance of the influence of site type on rockfall volume, with a probability value of < 0.0105. The rockfall volume and change detection values are then correlated with precipitation, which is a triggering factor. The study also reveals that the use of terrestrial LiDAR could reduce time and effort, increase accessibility, and produce effective solutions. LiDAR could be an indispensable tool for disaster risk assessment, response and recovery process.

Impact of Residual Limb Volume Loss on Socket Internal Pressures: A Preliminary Study

ABSTRACT Introduction Daily volume loss of residual limb is a condition that most prosthetic users face, negatively affecting their life. One of the consequences is the loss of contact between the residual limb and the socket, which modifies internal pressures. Objective The aim of this study was to study how the loss of volume of the residual limb affects socket adjustment through measuring pressures inside the socket. Study design The study design is prospective longitudinal. Materials and Methods Four subjects with unilateral transtibial amputation, with at least 1 year of prosthetic use, and walking with a comfortable prosthesis participated in this study. The pressure between the socket and the subject's residual limb was measured with an FSocket System (Tekscan). Residual limb volume was measured before and after each test with two different methods: optical scanning (Structure Sensor, Occipital) and conical frustum model. Sanders' protocol for volume loss was followed (Sanders et al. J Rehabil Res Dev. 2012;49:1467–1478). Volume changes in the residual limb and socket internal pressures were analyzed. Results/Discussion The pressure graph obtained is consistent with Sanders' volume graphs. The pressure distribution inside the socket is lost after 5 hours of use of the prosthetic device; this can be related to volume loss and alignment. The only area where the pressure increases is in the distal zone, given that once the prosthetic fit is lost, weight bearing is transferred to the socket's distal section (mean volume loss, intrasession −3%; mean pressure loss, intrasession −39%). Conclusions The study suggests that a small change in the volume can cause a change in the distribution of pressures inside the socket, indicating that the prosthetic fit may be compromised. For patient follow-up, measuring pressure inside the socket could be a useful indicator of socket misfit. Clinical Relevance Daily volume changes in the prosthesis can produce pressures that lead to pain, injuries, an inefficient gait, and prosthesis abandonment. Consequently, it is important to understand the behavior of the pressures inside the socket and the influence of the daily changes of volume on the socket adjustment to design better strategies and techniques of daily volume changes management.

The Wear Behavior of Various Monolithic Ceramics after Wear Simulation against Human Enamel.

Abstract Purpose: To evaluate and compare the surface roughness (SR), weight loss and volume loss of three monolithic ceramics; monolithic zirconia functional explore (f.explore), lithium disilicate glass ceramic (IPS.e. max CAD), and lithium silicate (Obsidian) and their wear effect on the natural enamel. Materials and Methods Twenty four ceramic disc and twenty four natural tooth antagonist were used. Samples were divided according to ceramic materials into 3 groups (n=8). Group I: f.explore, Group II: Obsidian, and Group III: IPS e.max CAD. SR, weight loss and volume loss of the discs and the enamel were verified before and after exposing the specimens to chewing simulator. Digital and Scanning electron microscopic evaluations were used. Results: The roughness differences changes between all groups was non-significant. While Obsidian antagonist cusp recorded the highest roughness followed by f.explore, whereas, e.max recorded least value. The greatest mean weight loss of materials was recorded in e. max followed by f.explore, where the lowest was recorded for Obsidian significantly.The greatest mean weight loss for antagonist cusp was recorded for f.explore followed by obsidian with insignificant difference ,while the lowest weight loss significantly was recorded in e.max antagonist cusp . The greatest mean volume loss of materials was recorded in e. max followed by f.explore where Obsidian recorded least value significantly. The greatest mean antagonist cusp volume loss was recorded in f.explore followed by e.max , whereas obsidian recorded least value. Conclusions: Obsidian is more wear resistant than e.max and f.explore and produced the least wear in opposing enamel.

Digital wear analysis of different CAD/CAM fabricated monolithic ceramic implant-supported single crowns using two optical scanners.

To digitally evaluate the volumetric wear of four different implant-crown materials and their antagonists after artificial aging using an intraoral scanner (IOS) device and a laboratory desktop scanner. A total of 48 implants were restored with monolithic crowns divided according to restorative material: lithium disilicate (LDS), zirconia (ZR), polymerinfiltrated ceramic network (PICN), and porcelain fused to metal (PFM). Each specimen was scanned using a desktop scanner (LAB; iScan D104, IMETRIC 3D) and an IOS (TRIOS 3, 3Shape) before and after chewing simulation (1,200,000 cycles, 49 N, steatite antagonist, 5°C to 50°C). The obtained STL files were superimposed, and the volumetric loss of substance of the crowns and their antagonists was quantified (Materialise 3-matic). Kruskal-Wallis, Spearman rho, and paired t tests were used to analyze the data (α = .05). The means of volume loss for each restorative material varied between 0.05 ± 0.06 mm3 (ZR with IOS) and 3.42 ± 1.65 mm3 (LDS with LAB). The wear of the antagonists was significantly lower (P < .05) for ZR than the other groups. Increased wear of the crowns was highly correlated with increased wear of their antagonists (rs = 0.859). When comparing the wear measurement using the two scanning devices, no difference in mean volume loss was found (IOS: 1.81 ± 1.81 mm3; LAB: 1.82 ± 1.78 mm3) (P = .596). Polished ZR was the most wear-resistant material and the least abrasive to the respective antagonist among the tested ceramics. For the quantification of wear, this IOS device can be used as an alternative to desktop scanners.

Evaluation of contact-wear behavior of lithium disilicate glass ceramic materials; In vitro study

Background: The purpose of this work is to evaluation of contact-wear behavior of lithium disilicate glass ceramic materials under in vitro chewing tests. Methods: Eight specimens of each ceramic materials were exposed contact-wear tests using a computer-controlled chewing simulator (1.2 Hz 50 N bite force loads, 120.000 mechanical cycles, constantly 37 °C temperature immersed in distill water. Al2O3 balls of 6 mm in diameter were used for each chewing test. The mean volume loss of all ceramic specimens after the contact-wear tests was determined with use 3D profilometer. In addition to a random specimen was selected from each test group and scanning electron microscopy (SEM) images were taken for analysis of wear tracks. Results: As a result, the ceramic materials tested in this study showed similar wear behaviors after 120.000 chewing tests. Conclusions: However, it was observed that more particles were carried on the wear surface and occurred micro cracks of the IPS e.max ceramic material. These micro cracks can be the continuation of cracks that occur subsurface of ceramic material.

Multimodal MRI staging for tracking progression and clinical-imaging correlation in sporadic Creutzfeldt-Jakob disease

Diffusion imaging is very useful for the diagnosis of sporadic Creutzfeldt-Jakob disease, but it has limitations in tracking disease progression as mean diffusivity changes non-linearly across the disease course. We previously showed that mean diffusivity changes across the disease course follow a quasi J-shaped curve, characterized by decreased values in earlier phases and increasing values later in the disease course. Understanding how MRI metrics change over-time, as well as their correlations with clinical deficits are crucial steps in developing radiological biomarkers for trials. Specifically, as mean diffusivity does not change linearly and atrophy mainly occurs in later stages, neither alone is likely to be a sufficient biomarker throughout the disease course. We therefore developed a model combining mean diffusivity and Volume loss (MRI Disease-Staging) to take into account mean diffusivity’s non-linearity. We then assessed the associations between clinical outcomes and mean diffusivity alone, Volume alone and finally MRI Disease-Staging.In 37 sporadic Creutzfeldt-Jakob disease subjects and 30 age- and sex-matched healthy controls, high angular resolution diffusion and high-resolution T1 imaging was performed cross-sectionally to compute z-scores for mean diffusivity (MD) and Volume. Average MD and Volume were extracted from 41 GM volume of interest (VOI) per hemisphere, within the images registered to the Montreal Neurological Institute (MNI) space. Each subject’s volume of interest was classified as either “involved” or “not involved” using a statistical threshold of ± 2 standard deviation (SD) for mean diffusivity changes and/or −2 SD for Volume. Volumes of interest were MRI Disease-Staged as: 0 = no abnormalities; 1 = decreased mean diffusivity only; 2 = decreased mean diffusivity and Volume; 3 = normal (“pseudo-normalized”) mean diffusivity, reduced Volume; 4 = increased mean diffusivity, reduced Volume. We correlated Volume, MD and MRI Disease-Staging with several clinical outcomes (scales, score and symptoms) using 4 major regions of interest (Total, Cortical, Subcortical and Cerebellar gray matter) or smaller regions pre-specified based on known neuroanatomical correlates.Volume and MD z-scores correlated inversely with each other in all four major ROIs (cortical, subcortical, cerebellar and total) highlighting that ROIs with lower Volumes had higher MD and vice-versa. Regarding correlations with symptoms and scores, higher MD correlated with worse Mini-Mental State Examination and Barthel scores in cortical and cerebellar gray matter, but subjects with cortical sensory deficits showed lower MD in the primary sensory cortex. Volume loss correlated with lower Mini-Mental State Examination, Barthel scores and pyramidal signs. Interestingly, for both Volume and MD, changes within the cerebellar ROI showed strong correlations with both MMSE and Barthel. Supporting using a combination of MD and Volume to track sCJD progression, MRI Disease-Staging showed correlations with more clinical outcomes than Volume or MD alone, specifically with Mini-Mental State Examination, Barthel score, pyramidal signs, higher cortical sensory deficits, as well as executive and visual-spatial deficits. Additionally, when subjects in the cohort were subdivided into tertiles based on their Barthel scores and their percentile of disease duration/course (“Time-Ratio”), subjects in the lowest (most impaired) Barthel tertile showed a much greater proportion of more advanced MRI Disease-Stages than the those in the highest tertile. Similarly, subjects in the last Time-Ratio tertile (last tertile of disease) showed a much greater proportion of more advanced MRI Disease-Stages than the earliest tertile. Therefore, in later disease stages, as measured by time or Barthel, there is overall more Volume loss and increasing MD.A combined multiparametric quantitative MRI Disease-Staging is a useful tool to track sporadic Creutzfeldt-Jakob- disease progression radiologically.

Investigation of two-body wear behavior of zirconia-reinforced lithium silicate glass-ceramic for biomedical applications; in vitro chewing simulation

The aim of this work was to the investigate two-body wear behavior of zirconia-reinforced lithium silicate glass-ceramic and composite resins through in vitro chewing simulation. Two types of glass-ceramics (IPS e.max CAD; lithium disilicate, Vita Suprinity; zirconia-reinforced lithium silicate) and two types of composite resins (Filtek Supreme; nano-filled, Ivoclar Vivadent Heliomolar; micro-filled) were used. All specimens were exposed to two-body wear tests using a dual-axis computer-controlled chewing simulation. Each chewing simulation test procedure, Al2O3 ball with a diameter of 6 mm, was used as antagonist material. The mean volume loss and wear depth of all specimens after the chewing tests were determined with use non-contact 3 D profilometer. Zirconia-reinforced lithium silicate Vita Suprinity had significantly higher two-body wear resistance than lithium disilicate IPS e.max CAD glass-ceramic and other composite resins after chewing tests. While Vita Suprinity exhibited a homogeneous crystal microstructure, IPS e.max CAD glass-ceramic exhibited a structure with needle-shaped fine-grained crystals embedded in a glassy matrix. As a result, the homogeneous distribution of zirconia particles into the ceramic material will increase the two-body wear resistance through chewing simulation tests.

Morphological changes of the human face after massive weight-loss due to bariatric surgery

The aim of this study was to evaluate the morphological changes in the face of obese patients during massive weight loss using a more reliable method than two dimensional photographs or tape measures. The faces of 23 patients were recorded prior to and six months after bariatric surgery. Distances between important anatomical landmarks of the face were calculated and the volume of the neck was compared. The distance between the Tragion and Subnasale (132.7 ± 6.804 mm to 131.5 ± 6.866 mm; p = 0.0003), and the distance between Tragion and Stomion became significantly longer 136.0 ± 8.016 mm to 134.3 ± 7.698 mm; p = 0.0031), while distances between the Tragion and Pogonion (150.2 ± 8.216 mm to 148.3 ± 8.383 mm; p < 0.0001), Tragion and Menton (152.3 ± 9.037 mm to 148.9 ± 9.623 mm; p < 0.0001), and Tragion and tip of the nose (144.9 ± 7.273 mm to 144.0 ± 7.416 mm; p = 0.0023) were significantly reduced. The mean volume loss of the neck was 75.218 ± 40.197 ml. No significant correlation was found between total weight loss and cervical volume loss (r = 0.3447; p = 0.1072). The morphological changes of the face after massive weight loss vary in different areas of the face. Patients and their attending physicians must be aware of the face's morphology change after massive weight loss in an extent that does not correlate with the total weight loss of the patient.

Investigating the Effect of Chewing Force and an Abrasive Medium on the Wear Resistance of Composite Materials by Chewing Simulation

Various composite materials used as biomaterials were tested by 20-, 50-, and 80-N chewing forces in distilled water and a poppy seed medium by using a computer-controlled chewing simulation procedure. In each chewing test, steatite balls 6 mm in diameter were used as an antagonist material. The mean volume loss of worn surfaces and the surface roughness of the composite materials was measured with a contactless 3D profilometer.

Quantitative tooth wear analysis of index teeth compared to complete dentition

ObjectivesRecent software advancements have facilitated quantification of erosive tooth wear progression using intraoral scans. This paper investigated if wear on commonly affected surfaces (central incisors and first molars) was representative of wear on the full arch. MethodsBimaxillary digital intraoral scans (True Definition, 3 M, USA) of patients (n = 30) from the monitoring arm of the Radboud Tooth Wear Project, were taken at baseline and at 3 years (+/-10months). The occlusal/incisal surface of each tooth (excluding 3rd molars) was analysed for volume change and volume change per mm of analysed surface area in WearCompare (www.leedsdigitaldentistry.com/Wearcompare) following previously published protocols. Data were normal, descriptives and multi-level linear regression analysis was performed in Stata v15.1 taking patient level and surface type data into account. ResultsData from 556 surfaces in 29 patients were included in analysis. Per patient, mean volume loss (95 % CI) was -0.91mm3(-1.28,-0.53) on all surfaces, -1.85mm3(-2.83,-0.86) on index surfaces, -2.53mm3(-3.91,-1.15) on molar surfaces and -0.83 mm3(-1.34,-0.31) on upper central incisal surfaces. Statistical differences were observed between analysing all surfaces and index teeth(p = 0.002) in addition to molar surfaces(p < 0.0001). Mean volume loss per mm2 of surface analysed was -0.024 mm3 (-0.031,-0.017), -0.028mm3 (-0.041,-0.014), -0.030mm3 (-0.046,-0.013) and -0.025mm3 (-0.041,-0.010) for all surfaces, index surfaces, first molar surfaces and central incisor surfaces respectively with no statistical differences between groups. ConclusionsWear on upper central incisors was not statistically different to full arch wear analysis. If the surface area is standardised, wear on both index surfaces are statistically similar to wear on the full arch. Clinical SignificanceThese results suggest that analysing rates of wear on index teeth can be a resource-saving substitute for analysing rates of wear on the entire dentition, provided the surface area is standardised. If whole surfaces are analysed, the molar surfaces will show greater rates of wear.

Measurement of dental crown wear -In vitro study.

The purpose of the study was to test new method for in vitro evaluation of dental material wear with 3D digitization procedure. Thirty dental crowns, made of polyetheretherketone and veneered with composite material, were subjected to wear test. The crown surface was digitized using coordinate measuring machine before and after the performed wear test. Mesh 3D models were reconstructed and average and maximum depth of lost material and volume loss was calculated (GOM Inspect 2016 software). Mean average depth value amounted 12±7 µm, maximum depth value was 42 µm, while mean volume loss was 0.0024 mm3. The smallest measured values were 4 µm for depth value and 0.0003 mm3 for volume loss. Coefficient of variation was very high for all tested parameters (>50%) as a result of data inconsistency. Within the limitations of applied methodology, the possibility of using coordinate measuring machine in measurement of dental material wear was confirmed.

Age-dependent cut-offs for pathological deep gray matter and thalamic volume loss using Jacobian integration

IntroductionSeveral recent studies indicate that deep gray matter or thalamic volume loss (VL) might be promising surrogate markers of disease activity in multiple sclerosis (MS) patients. To allow applying these markers to individual MS patients in clinical routine, age-dependent cut-offs distinguishing physiological from pathological VL and an estimation of the measurement error, which provides the confidence of the result, are to be defined. MethodsLongitudinal MRI scans of the following cohorts were analyzed in this study: 189 healthy controls (HC) (mean age 54 years, 22% female), 98 MS patients from Zurich university hospital (mean age 34 years, 62% female), 33 MS patients from Dresden university hospital (mean age 38 years, 60% female), and publicly available reliability data sets consisting of 162 short-term MRI scan-rescan pairs with scan intervals of days or few weeks. Percentage annualized whole brain volume loss (BVL), gray matter (GM) volume loss (GMVL), deep gray matter volume loss (deep GMVL), and thalamic volume loss (ThalaVL) were computed deploying the Jacobian integration (JI) method. BVL was additionally computed using Siena, an established method used in many Phase III drug trials. A linear mixed effect model was used to estimate the measurement error as the standard deviation (SD) of model residuals of all 162 scan-rescan pairs For estimation of age-dependent cut-offs, a quadratic regression function between age and the corresponding annualized VL values of the HC was computed. The 5th percentile was defined as the threshold for pathological VL per year since 95% of HC subjects exhibit a less pronounced VL for a given age. For the MS patients BVL, GMVL, deep GMVL, and ThalaVL were mutually compared and a paired t-test was used to test whether there are systematic differences in VL between these brain regions. ResultsSiena and JI showed a high agreement for BVL measures, with a median absolute difference of 0.1% and a correlation coefficient of r = 0.78. Siena and GMVL showed a similar standard deviation (SD) of the scan-rescan error of 0.28% and 0.29%, respectively. For deep GMVL, ThalaVL the SD of the scan-rescan error was slightly higher (0.43% and 0.5%, respectively). Among the HC the thalamus showed the highest mean VL (−0.16%, −0.39%, and −0.59% at ages 35, 55, and 75, respectively). Corresponding cut-offs for a pathological VL/year were −0.68%, −0.91%, and −1.11%. The MS cohorts did not differ in BVL and GMVL. However, both MS cohorts showed a significantly (p = 0.05) stronger deep GMVL than BVL per year. ConclusionIt might be methodologically feasible to assess deep GMVL using JI in individual MS patients. However, age and the measurement error need to be taken into account. Furthermore, deep GMVL may be used as a complementary marker to BVL since MS patients exhibit a significantly stronger deep GMVL than BVL.