Posterior Region Research Articles

Anatomy of vertebral artery hypoplasia and its relationship with clinical implications: a systematic review and meta-analysis of prevalence.

The vertebral artery (VA) is a vital branch of the subclavian artery, coursing through the transverse foramina of the cervical vertebrae, and playing a crucial role in irrigating the posterior region of the arterial cerebral circle, also known as the Polygon of Willis. Among the various possible alterations that can affect the VA, vertebral artery hypoplasia (HAV) emerges as a significant variant. This study aims to discern the anatomical features of HAV and its correlation with the clinical conditions of the posterior cerebral circulation. The databases Medline, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS were searched until January 2024. Two authors independently performed the search, study selection, and data extraction. Methodological quality was evaluated with an assurance tool for anatomical studies (AQUA). Pooled prevalence was estimated using a random effects model. A total of 24 studies met the established selection criteria, with a total of 8847 subjects. In this study, 6 articles were included for the meta-analysis with a total of subjects. The average prevalence of VAH reported in each study was 11% (95% CI 10-12%); the studies had a heterogeneity of 41% based on the funnel plot and a low risk of bias. The prevalence of VAH is low, but in the presence of this condition, the changes are mainly in diameter rather than morphological. If it is present, some clinical safeguards must be taken to avoid complications such as stroke.

Immediate Loading of 3-Unit Posterior Fixed Dental Prostheses on 3 Vs 2 Implants, Comparison and Evaluation with up to 10-Year Follow-up.

The aim of this prospective study was to evaluate and compare the implant survival rate, marginal bone levels and prostheses failure rate, of three-unit fixed dental prostheses (FDPs) supported by three vs. two implants immediately loaded in the posterior area. Partially edentulous patients in need of a three-unit implant supported FDP in the maxillary/mandibular posterior region were recruited and randomly split into two groups: Group 1 with three-unit FDP supported by three implants (Control); Group 2 with three-unit FDP supported by two implants (Test). Implants were inserted and immediately loaded with a temporary FDP. Sixty-three patients were included in the study. A total of 178 implants were placed and immediately loaded (128 maxillary/50 mandibular) to support 74 immediate provisional fixed prostheses (52 maxillary and 22 mandibular) delivered on the same day of implant insertion/placement; 30 in Group 1 and 44 in Group 2. The comparison of three vs. two implants resulted in comparable implant survival rate, marginal bone loss, and prostheses failure rate. All implants healed uneventfully with no adverse clinical and radiographical signs or symptoms except for one implant failure in Group 1 resulting in a cumulative success rate of 99,5%, 98,9% for Group 1 and 100% for Group 2 with a follow-up of 6-to-10 (mean 7 years). Once loaded, the implants remained in function from a minimum of 6 years to 10 years. Although more studies and larger sample sizes are needed to validate this study, the results showed no difference between the two Groups, demonstrating the potential viability of both clinical options.

Case report: pre-symptomatic clinical and metabolic profile in posterior cortical atrophy and dementia with Lewy bodies.

A research participant was monitored over nearly two decades at Mayo Clinic, undergoing annual neurologic assessments, neuropsychological tests, and multimodal imaging. Initially, he was cognitively normal but developed symptoms consistent with Posterior Cortical Atrophy (PCA) during the study. Early tests indicated mild, yet normal-range declines in language and visuospatial skills. FDG-PET scans revealed increased metabolism in posterior brain regions long before symptoms appeared. Advanced analysis using a novel in-house machine-learning tool predicted concurrent Alzheimer's disease and dementia with Lewy bodies. Autopsy confirmed a mixed neurodegenerative condition with significant Alzheimer's pathology and dense neocortical Lewy bodies. This case underscores the value of longitudinal imaging in predicting complex neurodegenerative diseases, offering vital insights into the early neurocognitive changes associated with PCA and dementia with Lewy bodies.

The anatomy of the motor branches of the sciatic nerve: an anatomical study with clinical implications.

The sciatic nerve gave the motor branches supply to: biceps femoris long and short head, semitendinosus, semimembranosus and adductor magnus muscles. The anatomy of these motor branches is highly variable. The aim of this study was to estimate the anatomy and morphometry of hamstring muscles innervation. The motor branches of the sciatic nerve were dissected from both sides from 20 cadaveric specimens (9 left and 11 right) from the 11 cadavers (4 females and 7 males) at the Department of Anatomy, Jagiellonian University Medical College Cracow. The motor branches of the sciatic nerve length, distance from piriformis muscle and number of all branches that exist from tibial nerve and common fibular nerve were measured. In most cases common fibular nerve gave off one branch to the short head of biceps femoris, in most cases the proximal hamstring tendon was innervated only by the first trunk, the highest number of branches were innervating the semimembranosus and the long head of biceps femoris, the longest branches were coming to the semimembranosus and the shortest to the proximal hamstring tendon CONCLUSIONS: The present study shows that there are various innervation types of the posterior group of thigh muscles. Knowledge of possible innervation patterns could be of utmost value to operators performing surgeries on the posterior region of the thigh.

Tomographic Planning of Dental Implants Using a Smartphone: Linear Measurements and Implant Selection-A Cross-Sectional Study.

This study assessed the accuracy of linear measurements and dental implant selection performed in a smartphone application compared to a computer software. Forty-four DICOM files from partially edentulous patients in the posterior region of the mandible were evaluated by three trained and calibrated examiners. Images were analyzed using three visualization methods: cross-sectional view (CScr) and coronal (CSco) plane using the CS 3D Imaging software, and coronal (DRco) plane using the DroidRender smartphone application. For the purpose of standardization, measurements of bone width and height were taken in the edentulous posterior region of the mandible, 10 mm posterior to the mental foramen. Dental implant selection was made according to Straumann® Standard implant catalog 2022/2023. Linear measurements were compared using the ANOVA test for repeated measurements and implant selection was compared using the Friedman test. Statistical analysis was performed using the SPSS software, considering a significance level of 5%. Linear measurements showed a statistically significant difference for bone width (p = 0.030), but not for height (p = 0.685). The choice of implant was not influenced by the visualization method (p = 0.614). It is possible to suggest the use of smartphone applications as an additional diagnostic tool for DICOM evaluation and dental implant planning in the posterior region of the mandible. Smartphone applications allow an assessment not limited to 2D images or to static environments. Therefore, information exchange and diagnostic opinion in emergency situations may be facilitated.

Glutamate imbalance in key structure of the default mode network in adults with attention-deficit/hyperactivity disorder.

The default mode network (DMN) is atypically active in patients with ADHD, likely contributing to the inattention patterns observed in patients with the disorder. Nonetheless, magnetic resonance spectroscopy (MRS) studies have rarely targeted the posterior cingulate cortex, a key DMN region, and little is known about the biochemical setting within this network in patients with ADHD. We aimed to assess the differences in metabolite profiles of the posterior cingulate cortex-a key region of the DMN-between patients with ADHD and controls. Five brain metabolites-glutamate, inositol, N-acetyl aspartate, choline, and creatine-were measured through MRS in the posterior cingulate cortex of patients and controls in a 3.0T scanner. Between-group comparison of neurometabolite concentrations in PCC was performed using multivariate analysis of covariance. A total of 88 patients and 44 controls were included in the analysis. Patients with ADHD showed lower levels of glutamate in the posterior cingulate cortex compared to controls (p = 0.003). Lower concentrations of glutamate in the posterior cingulate cortex suggest that a glutamatergic imbalance within the posterior cingulate cortex might play a role in the pathogenesis of ADHD. Further understanding of the causes and consequences of such glutamate decrease might help explain how some glutamate-related drug effects impact on ADHD symptomatology.

Peri-implantitis and maxillary sinus membrane thickening: A retrospective cohort study.

The objective of this study is to investigate the association of peri-implantitis (PI) and sinus membrane thickening and to assess the resolution of membrane thickening following intervention (implant removal or peri-implantitis treatment) aimed at arresting PI. Forty-five patients with 61 implants in the posterior maxillary region were retrospectively included in the study. Twenty-four patients were diagnosed with peri-implantitis (PI) and 21 had peri-implant health (PH). Cone-beam computed tomography (CBCT) scans were evaluated to assess maxillary sinus characteristics, including membrane thickening, sinus occupancy and ostium patency. The CBCT scans taken 6 months after intervention aimed at arresting disease (implant removal or treatment of PI) in the PI group were also appraised and compared to baseline scans. At baseline, all parameters evaluating membrane thickness disorders yielded significant differences between groups (p < .001). Patients with posterior maxillary implants diagnosed with PI were 7× more likely to present membrane thickening compatible with pathology when compared to patients with healthy implants (OR = 7.14; p = .005). Furthermore, the likelihood was 6x greater in implants diagnosed with PI to exhibit moderate membrane thickening (OR = 6.75, p = .001). The patients receiving interventions aimed at arresting PI experienced significant enhancement in all radiographic parameters related to the sinus cavity at the 6-month follow-up (p < .001), though these variations were similarly independent of whether treatment consisted of PI treatment or implant removal. Maxillary sinus membrane thickening and the permeability/obstruction of the ostium are frequently associated with the presence of PI in posterior implants. Interventions targeting disease resolution effectively reduce membrane thickness to levels compatible with maxillary sinus health.

Mechanical Analysis of the Connection Structure of a Double-Layered Valve Stent within an Annuloplasty Ring

Background: In this study, to address the failure of mitral valve repair surgery, a novel valve-in-ring model for an artificial mitral valve annuloplasty ring and a new double-layer mitral valve were established. A suitable number and length of ventricular fixation struts within the annuloplasty ring, as well as the implantation depth, result in variations in stress and strain for the inner and outer stent layers. Methods: The compression and self-expansion model of the stent was established via finite element analysis. The changes in stress and strain were analyzed by setting the length and number of the ventricular fixed struts and implantation depth. Results: When only affected by factors such as blood pressure, the maximum stresses of stent structures with three and six ventricular fixed struts are 476 and 222 MPa, respectively, in the right posterior annular region. At implantation depths of 0, 0.5, 1, and 2 mm, the maximum stresses are located in the left posterior annular region of the outer stent and are 740, 697, 709, and 742 MPa, respectively, and the maximum displacements of the inner stent are all in the right posterior ventricular fixed strut region of the posterior annulus and are 3.71, 3.10, 2.48, and 1.87 mm, respectively. In the three and six ventricular fixed strut stents, when the ventricular fixed strut length is 3, 4, and 5 mm, the maximum stresses are 570, 557, and 621 MPa and 674, 666, 644 MPa, respectively. Conclusions: Appropriately increasing the number of ventricular fixed struts can effectively reduce damage to the stent inside the body, and the damage to the stent is relatively consistent across different implantation depths; however, the right side of the stent's posterior annulus is particularly susceptible to damage. However, if the implantation depth is lower, the impact on the inner stent will be more significant. As the number of ventricular fixed struts increases, the strut length variation has a relatively stable impact on stent damage.

Histological features of the gastrointestinal tract of elongate tigerfish, Hydrocynus forskahlii (Cuvier, 1819), from Lake Albert

BackgroundThe tigerfish (Hydrocynus forskahlii) is an important food fish in different regions of Africa. As such, interest in its performance and nutritional requirements as a potential candidate for aquaculture is increasing. Characterization of the morpho-histological features and functions of the gut provides valuable insights into the feeding physiology and digestive system of fish species.ResultAn investigation of the morpho-histological features of the gastrointestinal tract of H. forskahlii captured from Lake Albert was conducted over an eight-month period. The digestive tract of H. forskahlii is characterised by a short oesophagus, well-developed and distensible stomach and moderately long intestine. The oesophagus had a higher abundance of mucous-secreting goblet cells compared to other digestive tract tissues. The stomach had a bag-like shape for swallowing large prey and was distinguishable into the cardiac, fundic and pyloric regions. Both the cardiac and fundic regions of the stomach had numerous gastric glands, whereas the pyloric region had large compound folds consisting of pseudo-stratified columnar epithelium. Many goblet cells were also observed in the mid and posterior regions of the intestine. The relative length of the gut of the H. forskahlii was 1.27 ± 0.03 cm, and it had a total of 20–22 pyloric caeca. The liver was observed to be divided in lobules by a central vein contained within connective sheets. Irregular cords of hepatocytes were also visible throughout the parenchyma.ConclusionsThe histological features of the H. forskahlii gut observed in the present study are consistent with those of carnivorous and omnivorous fish.

Shared EEG correlates between non-REM parasomnia experiences and dreams

Sleepwalking and related parasomnias result from incomplete awakenings out of non-rapid eye movement sleep. Behavioral episodes can occur without consciousness or recollection, or in relation to dream-like experiences. To understand what accounts for these differences in consciousness and recall, here we recorded parasomnia episodes with high-density electroencephalography (EEG) and interviewed participants immediately afterward about their experiences. Compared to reports of no experience (19%), reports of conscious experience (56%) were preceded by high-amplitude EEG slow waves in anterior cortical regions and activation of posterior cortical regions, similar to previously described EEG correlates of dreaming. Recall of the content of the experience (56%), compared to no recall (25%), was associated with higher EEG activation in the right medial temporal region before movement onset. Our work suggests that the EEG correlates of parasomnia experiences are similar to those reported for dreams and may thus reflect core physiological processes involved in sleep consciousness.

Reduced cerebrospinal fluid motion in patients with Parkinson’s disease revealed by magnetic resonance imaging with low b-value diffusion weighted imaging

BackgroundParkinson’s disease is characterized by dopamine-responsive symptoms as well as aggregation of α-synuclein protofibrils. New diagnostic methods assess α-synuclein aggregation characteristics from cerebrospinal fluid (CSF) and recent pathophysiologic mechanisms suggest that CSF circulation disruptions may precipitate α-synuclein retention. Here, diffusion-weighted MRI with low-to-intermediate diffusion-weightings was applied to test the hypothesis that CSF motion is reduced in Parkinson’s disease relative to healthy participants.MethodsMulti-shell diffusion weighted MRI (spatial resolution = 1.8 × 1.8 × 4.0 mm) with low-to-intermediate diffusion weightings (b-values = 0, 50, 100, 200, 300, 700, and 1000 s/mm2) was applied over the approximate kinetic range of suprasellar cistern fluid motion at 3 Tesla in Parkinson’s disease (n = 27; age = 66 ± 6.7 years) and non-Parkinson’s control (n = 32; age = 68 ± 8.9 years) participants. Wilcoxon rank-sum tests were applied to test the primary hypothesis that the noise floor-corrected decay rate of CSF signal as a function of b-value, which reflects increasing fluid motion, is reduced within the suprasellar cistern of persons with versus without Parkinson’s disease and inversely relates to choroid plexus activity assessed from perfusion-weighted MRI (significance-criteria: p < 0.05).ResultsConsistent with the primary hypothesis, CSF decay rates were higher in healthy (D = 0.00673 ± 0.00213 mm2/s) relative to Parkinson’s disease (D = 0.00517 ± 0.00110 mm2/s) participants. This finding was preserved after controlling for age and sex and was observed in the posterior region of the suprasellar cistern (p < 0.001). An inverse correlation between choroid plexus perfusion and decay rate in the voxels within the suprasellar cistern (Spearman’s-r=-0.312; p = 0.019) was observed.ConclusionsMulti-shell diffusion MRI was applied to identify reduced CSF motion at the level of the suprasellar cistern in adults with versus without Parkinson’s disease; the strengths and limitations of this methodology are discussed in the context of the growing literature on CSF flow.

Three-dimensional assessment of the maxilla after modified surgically assisted rapid expansion: a retrospective study.

This retrospective study aims to assess the three-dimensional dentoskeletal effects and median palatal suture opening pattern in patients undergoing modified surgically assisted maxillary rapid expansion (SARME) without pterygoid plate detachment. Twenty-eight patients submitted to modified SARME between 2009 and 2016 were retrospectively evaluated through cone-beam computed tomography (CBCT). Dental and skeletal measurements were taken at three different operative periods (before the expansion - T0; at the end of the activation of the Hyrax device - T1; and six months after the immobilization of the device - T2). Statistical analyses, including ANOVA and Pearson's correlation coefficient, were performed using SPSS software. SARME demonstrated significant transverse maxillary expansion (with an average of 6.05mm) with a greater impact in the anterior region. Dental measurements, including canine and molar distances, exhibited significant changes over the operative periods. Bone measurements (ANS and PNS) presented small but significant alterations, including a slight inferior displacement of ANS during device activation. The nasal floor width increased, followed by a width reduction after immobilization. The median palatal suture predominantly exhibited a Type II (V-shaped) opening. The modified SARME presented a transversal direction increase and a super-lower skeletal displacement, with the anterior region being more affected than the posterior region. There was no change in the anteroposterior direction of the maxilla. Additionally, there was an increase in the linear dental measurements and a decrease in the angular measurement, with a positive correlation between the amount of posterior bone expansion and molar expansion as a result of the treatment in the analyzed period.

Maxillary Bone Necrosis in Post-COVID-19 Patients: Possibility of Medication-Related Osteonecrosis of Jaws (MRONJ) Induced by Tocilizumab.

Medication-related osteonecrosis of the jaws (MRONJ) is a serious condition often linked with antiresorptive, immune modulating, and antiangiogenic drugs, initially associated with bisphosphonates but now including a broader range of medications. Tocilizumab, an interleukin-6 (IL-6) receptor-inhibiting monoclonal antibody used for conditions like rheumatoid arthritis and recently for COVID-19 to reduce IL-6 activity and alleviate symptoms, has raised concerns over its potential to induce MRONJ, particularly in post-COVID-19 patients. A case involving a 36-year-old male who developed tooth mobility and pain in the right maxillary posterior region after COVID-19 treatment with tocilizumab and dexamethasone is highlighted. Despite treatments like antibiotics, the necrosis persisted until more extensive surgery was performed, leading to improvement without recurrence over 2 years. This case emphasizes the need for awareness and research into the risk of MRONJ in patients treated with tocilizumab after COVID-19, underlining the importance for healthcare professionals to recognize and manage this complication.

Reproducibility of Quantitative Double-Echo Steady-State T2 Mapping of Knee Cartilage.

Cartilage T2 can detect joints at risk of developing osteoarthritis. The quantitative double-echo steady state (qDESS) sequence is attractive for knee cartilage T2 mapping because of its acquisition time of under 5 minutes. Understanding the reproducibility errors associated with qDESS T2 is essential to profiling the technical performance of this biomarker. To examine the combined acquisition and segmentation reproducibility of knee cartilage qDESS T2 using two different regional analysis schemes: 1) manual segmentation of subregions loaded during common activities and 2) automatic subregional segmentation. Prospective. 11 uninjured participants (age: 28 ± 3 years; 8 (73%) female). 3-T, qDESS. Test-retest T2 maps were acquired twice on the same day and with a 1-week interval between scans. For each acquisition, average cartilage T2 was calculated in four manually segmented regions encompassing tibiofemoral contact areas during common activities and 12 automatically segmented regions from the deep-learning open-source framework for musculoskeletal MRI analysis (DOSMA) encompassing medial and lateral anterior, central, and posterior tibiofemoral regions. Test-retest T2 values from matching regions were used to evaluate reproducibility. Coefficients of variation (%CV), root-mean-square-average-CV (%RMSA-CV), and intraclass correlation coefficients (ICCs) assessed test-retest T2 reproducibility. The median of test-retest standard deviations was used for T2 precision. Bland-Altman (BA) analyses examined test-retest biases. The smallest detectable difference (SDD) was defined as the BA limit of agreement of largest magnitude. Significance was accepted for P < 0.05. All cartilage regions across both segmentation schemes demonstrated intraday and interday qDESS T2 CVs and RMSA-CVs of ≤5%. T2 ICC values >0.75 were observed in the majority of regions but were more variable in interday tibial comparisons. Test-retest T2 precision was <1.3 msec. The T2 SDD was 3.8 msec. Excellent CV and RMSA-CV reproducibility may suggest that qDESS T2 increases or decreases >5% (3.8 msec) could represent changes to cartilage composition. Stage 2.

Differential neural correlates underlying visuospatial versus semantic reasoning in autistic children.

While fronto-posterior underconnectivity has often been reported in autism, it was shown that different contexts may modulate between-group differences in functional connectivity. Here, we assessed how different task paradigms modulate functional connectivity differences in a young autistic sample relative to typically developing children. Twenty-three autistic and 23 typically developing children aged 6 to 15years underwent functional magnetic resonance imaging (fMRI) scanning while completing a reasoning task with visuospatial versus semantic content. We observed distinct connectivity patterns in autistic versus typical children as a function of task type (visuospatial vs. semantic) and problem complexity (visual matching vs. reasoning), despite similar performance. For semantic reasoning problems, there was no significant between-group differences in connectivity. However, during visuospatial reasoning problems, we observed occipital-occipital, occipital-temporal, and occipital-frontal over-connectivity in autistic children relative to typical children. Also, increasing the complexity of visuospatial problems resulted in increased functional connectivity between occipital, posterior (temporal), and anterior (frontal) brain regions in autistic participants, more so than in typical children. Our results add to several studies now demonstrating that the connectivity alterations in autistic relative to neurotypical individuals are much more complex than previously thought and depend on both task type and task complexity and their respective underlying cognitive processes.

Impact of bone levels on stress distribution around all-on-four concept: A 3-D finite element analysis

This study aimed to investigate the impact of implant placement levels within the bone on stress distribution in the context of the All-on-Four concept. In this Finite Element Analysis(FEA), two 4.1 mm x 10 mm implants were axially placed in the anterior region of the jawbone, while two 4.1 mm x 14 mm implants were tilted at 30 ° in the posterior region following the all-on-four concept. In the EC scenario, all implants were inserted at the equicrestal level. In other scenarios, implants were positioned at 1 mm and 2 mm subcrestal levels (SC1, SC2). In all groups, the prosthesis was designed to replicate a group-function occlusion. A total load of 450 N was applied to the prosthesis. Upon deeper implant placement below the crest level, a trend of decreasing Von Mises stresses was observed in both implants and implant fragments. The highest Pmax value in the bone was recorded in SC-2, characterized by the absence of cortical bone support, with values of 3.16 N/mm2 in the anterior region and 1.55 N/mm2 in the posterior region. Conversely, the lowest Pmax values were noted in SC-1 for the anterior implant (2.67 N/mm2) and the EC for the posterior implant (0.87 N/mm2). Implant placements devoid of cortical bone support result in stress transmission from the implant and its components to the peri-implant bone. Optimal stress minimization is achieved by placing anterior axial angle implants deeper than the crest level while retaining cortical bone support and positioning posterior tilted implants at the crest level.

Metallic vs Ceramic Bracket Failures After 12 Months of Treatment: A Prospective Clinical Trial

IntroductionOrthodontic treatment with fixed vestibular appliances is still widely used worldwide. When choosing the aesthetic alternative of ceramic brackets, the possibility of failure and cracking of braces should be considered. Therefore, the aim of the present study was to compare the failure rates of ceramic and metal brackets in a 12-month clinical study. MethodsEighty patients undergoing fixed orthodontic treatment with vestibular appliances were enrolled and divided into 2 equal groups: MET for metal brackets and CER for ceramic brackets. After bonding, bracket failures were recorded for 12 months, along with the archwire placed at the time of failure. Angle's dental class, skeletal class, Wits appraisal, Little's irregularity index, overjet, overbite, age, and gender of the patients were recorded from pretreatment cephalometric tracings and study casts. The data were statistically analysed (P < .05). ResultsSignificantly higher failure rates were found for ceramic brackets in the overall analysis, in the mandibular arch, and in the posterior region. Regression analysis revealed a significant influence of round nickel-titanium archwires on higher failure rates, whilst a significant influence of rectangular archwires was found on lower failure rates. ConclusionsCeramic brackets showed higher failure rates. Patients should be aware that orthodontic treatment with ceramic brackets may involve delays and inconvenience due to the higher failure rate compared to metal brackets.

Monolithic Zirconia Single Crowns Supported by Narrow or Standard Diameter Titanium-zirconium Implants in Posterior Sites: One-year Results of a Randomized Controlled Trial.

The replacement of missing teeth with implant-supported prostheses has become a standard treatment option with reliable long-term outcomes in various clinical indications.1-6 The implant-supported single crowns, in particular, presented the most favorable outcome with a survival rate of 89.5% to 96% over a 10-year period.5,6 A notable prosthetic maintenance requirement, however, was reported irrespective of the prosthetic material used for the crown construction.1,7 Metal-ceramic restorations have been considered the gold standard when replacing single or multiple missing teeth with implant-supported fixed dental prostheses.8 A systematic review of 4363 metal-ceramic implant-supported single crowns in the anterior and posterior region reported an impressive survival rate of 98.3% over five years.9 Yet, the biologic and prosthetic complications associated with these restorations were substantial with a rate of 13.5%. In the posterior region, a recent systematic review of short-term randomized controlled trials10 reported a survival rate of 99.1% for metal-ceramic implant-supported single crowns. The reported prosthetic complications, mainly ceramic chipping, were also notable with an incidence rate of 7.6%.mIn recent years, the introduction of high-strength all-ceramic materials as well as digitaldesign and manufacturing processes, has allowed faster fabrication of more esthetic and cost effective restorations.11 Zirconia-based fixed dental prostheses on teeth and implants are now increasingly used and show 5-year cumulative survival rates of 89.4 to 100%.12 These restorations are typically made up of a zirconia framework that is veneered with a layer of glass ceramic to impart translucency for enhanced esthetics.13 However, chipping of the ceramic layer has been a lingering issue, shifting the attention toward the use of full anatomic monolithic zirconia restorations.14,15 Replacement of missing teeth with dental implants in posterior ridges with limited bone width can be surgically challenging and the notion of narrow diameter implants has been suggested.16,17 These implants were thought to offer potential advantages in terms of costeffectiveness and surgical morbidity.18,19 The literature, however, remains controversial on treatment outcomes with narrow diameter implants, particularly in posterior sites.19-21 When single tooth replacement with monolithic zirconia implant-supported single crowns in posterior sites are considered, only short to medium-term outcomes are available.22-26 The survival rates and clinical performances reported in these studies were variable. Crown survival rates between 84% and 100% were demonstrated over an observation time of one to three years, while the prosthetic complications were between 0% to 14%. In three studies,22,23,25 standard diameter titanium implants were used in premolar and molar sites to support the single crowns. The remaining two studies by Mühlemann et al. (2020) and Zumstein et al. (2023) reported the one-year and three-year outcomes, respectively, of the same cohort. In these studies, narrow titanium-zirconium (TiZr) implants of 3.3 mm diameter were exclusively utilized in molar sites. The implant and crown survival rates reported at one and three years were 97.4% and 84%, respectively. The lower survival rate observed in the report of Zumstein et al. (2023) resulted from fracture of five implants and the subsequent loss of their respective crowns. Aside from these two reports, no other information on the outcomes of monolithic zirconia single crowns supported by narrow diameter TiZr implants in posterior sites are available. The validity of this treatment, therefore, needs further investigation with well-designed clinical trials. Hence, a randomized controlled trial was undertaken to assess various implant, prosthetic, and patient-reported outcomes of monolithic zirconia single crowns supported by either narrow or standard diameter titanium-zirconium (TiZr) implants in posterior sites. The present report focuses on the one-year prosthetic results.

Survival Analysis up to 8 Years of 304 Anatomic-Contour Implant Zirconia Crowns Fabricated with a Fully Digital Cast-Free Workflow and Directly Screwed on External Hexagonal Implant Connections without the Interposition of a Ti-Base: A Multicentric Retrospective Study.

Data on the clinical performance of monolithic Zirconia screw-retained crowns on external hexagon implants fabricated from digital scans through a cast-free, fully digital workflow is lacking and needs to be included. This retrospective multicentric study aimed to evaluate the real-life clinical results of monolithic Zirconia screw-retained crowns without the interposition of a Ti-base on external hexagon implants fabricated from intraoral scans and a cast-free approach in private practices. Single external hex implant fixtures were restored with monolithic zirconia crowns without the interposition of a Tibase. The crowns were directly screwed on external hexagonal implant connections with a castfree, fully digital workflow. Data were analyzed using descriptive statistics and the Kaplan- Meier test. Between September 2022 and March 2023, the California Dental Association modified criteria were adopted for clinical evaluation after recalling all patients. A total of 304 single tooth restorations in the maxillary and mandibular posterior regions fabricated between July 2014 and July 2022 in 252 patients (120 males and 132 females, mean age 53.6 years, SD 23.3). Seven crowns were excluded because of patient dropout. The most common minor technical complications were screw loosening (3 crowns) and loss of the screw-access hole filling (3 crowns). Four failures included two implant failures with mobility and two fractured crowns. No screw or implant fractures were recorded. The overall cumulative survival rate was 98.6% and the average success rate (crowns experiencing no failures or complications) was 96.0%. The mean overall survival time was 101.3 months (standard error, 0.847; 95% confidence interval for the mean, 99.67-102.99). The overall survival probability was 87.9% up to 97 months. With careful case selection and comprehensive periodontal maintenance program, single crowns directly screwed onto an external hexagon platform have shown to have excellent survival and success (complication-free) rates, comparable to available data regarding single crowns with a metal implant- prosthetic interface.

Quantitative analysis of visually normal EEG reveals spectral power abnormalities in temporal lobe epilepsy

ObjectiveTo compare quantitative spectral parameters of visually-normal EEG between Mesial Temporal Lobe Epilepsy (MTLE) patients and healthy controls (HC). MethodWe enrolled 26 MTLE patients and 26 HC. From each recording we calculated total power of all frequency bands and determined alpha-theta (ATR) and alpha-delta (ADR) power ratios in different brain regions. Group-wise differences between spectral parameters were investigated (p < 0.05). To test for associations between spectral-power and cognitive status, we evaluated correlations between neuropsychological tests and quantitative EEG (qEEG) metrics. ResultsIn all comparisons, ATR and ADR were significantly decreased in MTLE patients compared to HC, particularly over the hemisphere ipsilateral to epileptic activity. A positive correlation was seen in MTLE patients between ATR in ipsilateral temporal lobe, and results of neuropsychological tests of auditory verbal learning (RAVLT and RAVLT-D), short term verbal memory (Digit span backwards), and executive function (Weigl's sorting test). ADR values in the contralateral posterior region correlated positively with RAVLT-D and Digit span backwards tests. DiscussionResults confirmed that the power spectrum of qEEG is shifted towards lower frequencies in MTLE patients compared to HC. ConclusionOf note, our results were found in visually-normal recordings, providing further evidence of the value of qEEG for longitudinal monitoring of MTLE patients over time. Exploratory analysis of associations between qEEG and neuropsychological data suggest this could be useful for investigating effects of antiseizure medications on cognitive integrity in patients.