A comparison of the marginal gaps of lithium disilicate crowns fabricated by two different intraoral scanners

BACKGROUND

The purpose of this study was to assess marginal gaps of CAD/CAM lithium disilicate crowns constructed using two different intraoral scanners of different generations.

METHODS

Twenty four Columbia model lower left molars were prepared for lithium disilicate crowns in a simulated environment by undergraduate students. The crown preparations were scanned by E4D and Trios 3 intraoral scanners and CAD/CAM lithium disilicate crowns designed and manufactured. The crowns were seated onto the original crown preparations and three vertical marginal gap measurements taken at four locations (mid-buccal, mid-lingual, mid-mesial and mid-distal) using a stereomicroscope. The mean marginal gap (MMG) was calculated for each crown and each individual tooth surface.

RESULTS

The MMG was not statistically significantly different for the Trios 3 and E4D scanners (P = 0.111). There was no statistically significant effect of measurement location on the tooth on the marginal gap (P = 0.1134).

CONCLUSIONS

There was no difference in the MMGs of CAD/CAM lithium disilicate crowns constructed using two different intraoral scanners of different generations. Within the limitations of this study, the advances in scanning technology have produced small and insignificant improvements in the accuracy of crown margins.

Associations Between Screen-Based Media Use and Brain White Matter Integrity in Preschool-Aged Children

IMPORTANCE

The American Academy of Pediatrics (AAP) recommends limits on screen-based media use, citing its cognitive-behavioral risks. Screen use by young children is prevalent and increasing, although its implications for brain development are unknown.

OBJECTIVE

To explore the associations between screen-based media use and integrity of brain white matter tracts supporting language and literacy skills in preschool-aged children.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study of healthy children aged 3 to 5 years (n = 47) was conducted from August 2017 to November 2018. Participants were recruited at a US children's hospital and community primary care clinics.

EXPOSURES

Children completed cognitive testing followed by diffusion tensor imaging (DTI), and their parent completed a ScreenQ survey.

MAIN OUTCOMES AND MEASURES

ScreenQ is a 15-item measure of screen-based media use reflecting the domains in the AAP recommendations: access to screens, frequency of use, content viewed, and coviewing. Higher scores reflect greater use. ScreenQ scores were applied as the independent variable in 3 multiple linear regression models, with scores in 3 standardized assessments as the dependent variable, controlling for child age and household income: Comprehensive Test of Phonological Processing, Second Edition (CTOPP-2; Rapid Object Naming subtest); Expressive Vocabulary Test, Second Edition (EVT-2; expressive language); and Get Ready to Read! (GRTR; emergent literacy skills). The DTI measures included fractional anisotropy (FA) and radial diffusivity (RD), which estimated microstructural organization and myelination of white matter tracts. ScreenQ was applied as a factor associated with FA and RD in whole-brain regression analyses, which were then narrowed to 3 left-sided tracts supporting language and emergent literacy abilities.

RESULTS

Of the 69 children recruited, 47 (among whom 27 [57%] were girls, and the mean [SD] age was 54.3 [7.5] months) completed DTI. Mean (SD; range) ScreenQ score was 8.6 (4.8; 1-19) points. Mean (SD; range) CTOPP-2 score was 9.4 (3.3; 2-15) points, EVT-2 score was 113.1 (16.6; 88-144) points, and GRTR score was 19.0 (5.9; 5-25) points. ScreenQ scores were negatively correlated with EVT-2 (F2,43 = 5.14; R2 = 0.19; P < .01), CTOPP-2 (F2,35 = 6.64; R2 = 0.28; P < .01), and GRTR (F2,44 = 17.08; R2 = 0.44; P < .01) scores, controlling for child age. Higher ScreenQ scores were correlated with lower FA and higher RD in tracts involved with language, executive function, and emergent literacy abilities (P < .05, familywise error-corrected), controlling for child age and household income.

CONCLUSIONS AND RELEVANCE

This study found an association between increased screen-based media use, compared with the AAP guidelines, and lower microstructural integrity of brain white matter tracts supporting language and emergent literacy skills in prekindergarten children. The findings suggest further study is needed, particularly during the rapid early stages of brain development.

Electrical stimulation mapping of language with stereo-EEG

OBJECTIVE

We prospectively validated stereo-electroencephalography (EEG) electrical stimulation mapping (ESM) of language against a reference standard of meta-analytic functional magnetic resonance imaging (fMRI) framework (Neurosynth).

METHODS

Language ESM was performed using 50 Hz, biphasic, bipolar, stimulation at 1-8 mA, with a picture naming task. Electrode contacts (ECs) were scored as ESM+ if ESM interfered with speech/language function. For each patient, presurgical MRI was transformed to a standard space and coregistered with computed tomographic (CT) scan to obtain EC locations. After whole-brain parcellation, this fused image data were intersected with three-dimensional language fMRI (Neurosynth), and each EC was classified as lying within/outside the fMRI language parcel. Diagnostic odds ratio (DOR) and other indices were estimated. Current thresholds for language inhibition and after-discharges (ADs) were analyzed using multivariable linear mixed models.

RESULTS

In 10 patients (5 females), aged 5.4-21.2 years, speech/language inhibition was noted with ESM on 87/304 (29%) ECs. Stereo-EEG language ESM was a valid classifier of fMRI (Neurosynth) language sites (DOR: 9.02, p < 0.0001), with high specificity (0.87) but poor sensitivity (0.57). Similar diagnostic indices were seen for ECs in frontal or posterior regions, and gray or white matter. Language threshold (3.1 ± 1.5 mA) was lower than AD threshold (4.0 ± 2.0 mA, p = 0.0001). Language and AD thresholds decreased with age and intelligence quotient. Electrical stimulation mapping triggered seizures/auras represented patients' habitual semiology with 1 Hz stimulation.

CONCLUSIONS

Stereo-EEG ESM can reliably identify cerebral parcels with/without language function but may under detect all language sites. We suggest a 50-Hz stimulation protocol for language ESM with stereo-EEG.

A Novel Approach to Evaluate Brain Activation for Lower Extremity Motor Control

BACKGROUND AND PURPOSE

The purpose of this study was to assess the consistency of a novel MR safe lower extremity motor control neuroimaging paradigm to elicit reliable sensorimotor region brain activity.

METHODS

Participants completed multiple sets of unilateral leg presses combining ankle, knee, and hip extension and flexion movements against resistance at a pace of 1.2 Hz while lying supine in a 3T MRI scanner. Regions of Interest (ROI) consisted of regions primarily involved in lower extremity motor control (right and left primary motor cortex, primary somatosensory cortex, premotor cortex, secondary somatosensory cortex, basal ganglia, and the cerebellum).

RESULTS

The group analysis based on mixed effects paired samples t-test revealed no differences for brain activity between sessions (P > .05). Intraclass correlation coefficients in the sensorimotor regions were good to excellent for average percent signal change (.621 to .918) and Z-score (.697 to .883), with the exception of the left secondary somatosensory cortex percent signal change (.165).

CONCLUSIONS

These results indicate that a loaded lower extremity force production and attenuation task that simulates the range of motion of squatting, stepping, and landing from a jump is reliable for longitudinal neuroimaging applications and support the use of this paradigm in further studies examining therapeutic interventions and changes in dynamic lower extremity motor function.

Functional Connectivity of Attention, Visual, and Language Networks During Audio, Illustrated, and Animated Stories in Preschool-Age Children

The American Academy of Pediatrics recommends that parents read with their children early and often and limits on screen-based media. While book sharing may benefit attention in children, effects of animated content are controversial, and the influence of either on attention networks has not previously been studied. This study involved functional magnetic resonance imaging (fMRI) of three separate active-task scans composed of similar 5-min stories presented in the same order for each child (audio → illustrated → animated), followed by assessment of comprehension. Five functional brain networks were defined a priori through literature review: dorsal attention network (DAN), ventral attention network (VAN), language (L), visual imagery (VI), and visual perception (VP). Analyses involved comparison of functional connectivity (FC) within- and between networks across formats, applying false discovery rate correction. Twenty-seven of 33 children completed fMRI (82%; 15 boys, 12 girls; mean 58 ± 8 months old). Comprehension of audio and illustrated stories was equivalent and lower for animation (p < 0.05). For illustration relative to audio, FC within DAN and VAN and between each of these and all other networks was similar, lower within-L, and higher between VI-VP, suggesting reduced strain on the language network using illustrations and imagery. For animation relative to illustration, FC was lower between DAN-L, VAN-VP, VAN-VI, L-VI, and L-VP, suggesting less focus on narrative, reorienting to imagery, and visual-language integration. These findings suggest that illustrated storybooks may be optimal at this age to encourage integration of attention, visual, and language networks, while animation may bias attention toward VP.

The influence of different cement spaces on the marginal gap of CAD/CAM all-ceramic crowns

BACKGROUND

The purpose of this study was to measure the marginal gaps of CAD/CAM all-ceramic crowns constructed using different cement spaces on crown preparations created by undergraduate students.

METHODS

Twenty-four Columbia model lower left first molars with assessed tapers and reduction volumes (RV) were recruited to receive complete coverage E.max crowns. Three E.max crowns were digitally designed and milled for each crown preparation using three different cement spaces: 50 μm (CS-50), 100 μm (CS-100), 200 μm (CS-200). Each crown was seated onto its original crown preparation and three vertical marginal gap measurements were taken at four locations (mid-buccal, mid-lingual, mid-mesial, mid-distal) using a stereomicroscope. The mean marginal gap (MMG) was calculated for each crown and each individual tooth surface.

RESULTS

The MMG was statistically significantly different for each of the three cement spaces (126 μm for CS-50, 89 μm for CS-100, and 75 μm for CS-200) (P < 0.0001). A taper of between 20 and 30° produced the smallest MMG. Insufficient RV caused significantly larger MMGs. The buccal margin had significantly smaller MMGs than all other measured surfaces.

CONCLUSIONS

The most accurate margins of digitally designed all-ceramic crowns constructed on simulation teeth prepared by undergraduate students were observed when using a 200 μm cement space.

Altered brain microstructure in association with repetitive subconcussive head impacts and the potential protective effect of jugular vein compression: a longitudinal study of female soccer athletes

PURPOSE

To (1) quantify white matter (WM) alterations in female high school athletes during a soccer season and characterise the potential for normalisation during the off-season rest period, (2) determine the association between WM alterations and exposure to repetitive subconcussive head impacts, and (3) evaluate the efficacy of a jugular vein compression collar to prevent WM alterations associated with head impact exposure.

METHODS

Diffusion tensor imaging (DTI) data were prospectively collected from high school female soccer participants (14-18 years) at up to three time points over 9 months. Head impacts were monitored using accelerometers during all practices and games. Participants were assigned to a collar (n=24) or non-collar group (n=22). The Tract-Based Spatial Statistics approach was used in the analysis of within-group longitudinal change and between-group comparisons.

RESULTS

DTI analyses revealed significant pre-season to post-season WM changes in the non-collar group in mean diffusivity (2.83%±2.46%), axial diffusivity (2.58%±2.34%) and radial diffusivity (3.52%±2.60%), but there was no significant change in the collar group despite similar head impact exposure. Significant correlation was found between head impact exposure and pre-season to post-season DTI changes in the non-collar group. WM changes in the non-collar group partially resolved at 3 months off-season follow-up.

DISCUSSION

Microstructural changes in WM occurred during a season of female high school soccer among athletes who did not wear the collar device. In comparison, there were no changes in players who wore the collar, suggesting a potential prophylactic effect of the collar device in preventing changes associated with repetitive head impacts. In those without collar use, the microstructural changes showed a reversal towards normal over time in the off-season follow-up period.

Impact of Low-Level Blast Exposure on Brain Function after a One-Day Tactile Training and the Ameliorating Effect of a Jugular Vein Compression Neck Collar Device

Special Weapons and Tactics (SWAT) personnel who conduct breacher exercises are at risk for blast-related head trauma. We aimed to investigate the potential impact of low-level blast exposure during breacher training on the neural functioning of working memory and auditory network connectivity. We also aimed to evaluate the effects of a jugular vein compression collar, designed to internally mitigate slosh energy absorption, preserving neural functioning and connectivity, following blast exposure. A total of 23 SWAT personnel were recruited and randomly assigned to a non-collar (n = 11) and collar group (n = 12). All participants completed a 1-day breacher training with multiple blast exposure. Prior to and following training, 18 participants (non-collar, n = 8; collar, n = 10) completed functional magnetic resonance imaging (fMRI) of working memory using N-Back task; 20 participants (non-collar, n = 10; collar, n = 12) completed resting-state fMRI. Key findings from the working memory analysis include significantly increased fMRI brain activation in the right insular, right superior temporal pole, right inferior frontal gyrus, and pars orbitalis post-training for the non-collar group (p < 0.05, threshold-free cluster enhancement corrected), but no changes were noted for the collar group. The elevation in fMRI activation in the non-collar group was found to correlate significantly (n = 7, r = 0.943, p = 0.001) with average peak impulse amplitude experienced during the training. In the resting-state fMRI analysis, significant pre- to post-training increase in connectivity between the auditory network and two discrete regions (left middle frontal gyrus and left superior lateral occipital/angular gyri) was found in the non-collar group, while no change was observed in the collar group. These data provided initial evidence of the impact of low-level blast on working memory and auditory network connectivity as well as the protective effect of collar on brain function following blast exposure, and is congruent with previous collar findings in sport-related traumatic brain injury.

A jugular vein compression collar prevents alterations of endogenous electrocortical dynamics following blast exposure during special weapons and tactical (SWAT) breacher training

Exposure to explosive blasts places one at risk for traumatic brain injury, especially for special weapons and tactics (SWAT) and military personnel, who may be repeatedly exposed to blasts. In the current study, the effectiveness of a jugular vein compression collar to prevent alterations in resting-state electrocortical activity following a single-SWAT breacher training session was investigated. SWAT team personnel were randomly assigned to wear a compression collar during breacher training and resting state electroencephalography (EEG) was measured within 2 days prior to and two after breacher training. It was hypothesized that significant changes in brain dynamics-indicative of possible underlying neurodegenerative processes-would follow blast exposure for those who did not wear the collar, with ameliorated changes for the collar-wearing group. Using recurrence quantification analysis (RQA) it was found that participants who did not wear the collar displayed longer periods of laminar electrocortical behavior (as indexed by RQA's vertical max line measure) after breacher training. It is proposed that the blast wave exposure for the no-collar group may have reduced the number of pathways, via axonal disruption-for electrical transmission-resulting in the EEG signals becoming trapped in laminar states for longer periods of time. Longer laminar states have been associated with other electrocortical pathologies, such as seizure, and may be important for understanding head trauma and recovery.

Does brain functional connectivity contribute to musculoskeletal injury? A preliminary prospective analysis of a neural biomarker of ACL injury risk

OBJECTIVES

We aimed to present a unique prospective neurological dataset for participants who experienced an ACL injury.

DESIGN

Prospective longitudinal case-control.

METHODS

High school female soccer athletes were evaluated using functional magnetic resonance imaging to capture resting-state brain connectivity prior to their competitive season. Two of these athletes later experienced an ACL injury (ACLI). We matched these ACLI participants with eight teammates who did not go on to sustain an ACL injury (uninjured controls, Con) based on age, grade, sex, height, and weight to examine differences in preseason connectivity. Knee-motor regions of interest (ROIs) were created based on previously published data from which five specific areas were selected as seeds for analysis. Independent-samples t-tests with a false discovery rate correction for multiple comparisons determined differences in connectivity between the ACLI and Con.

RESULTS

There was significantly greater connectivity between the left primary sensory cortex (a brain region responsible for proprioception) and the right posterior lobe of the cerebellum (a brain region responsible for balance and coordination) for the Con relative to ACLI, t (8)=4.53, p=0.03 (false discovery rate corrected).

CONCLUSIONS

These preliminary data indicate that those who do not later sustain an ACL injury exhibit a stronger functional connection between a cortical sensory-motor region and a cerebellar region responsible for balance and coordination. These findings may help to guide development of brain-driven biofeedback training that optimizes and promotes adaptive neuroplasticity to reduce motor coordination errors and injury risk.

Mild Jugular Compression Collar Ameliorated Changes in Brain Activation of Working Memory after One Soccer Season in Female High School Athletes

Recent neuroimaging studies have suggested that repetitive subconcussive head impacts, even after only one sport season, may lead to pre- to post-season structural and functional alterations in male high school football athletes. However, data on female athletes are limited. In the current investigation, we aimed to (1) assess the longitudinal pre- to post-season changes in functional MRI (fMRI) of working memory and working memory performance, (2) quantify the association between the pre- to post-season change in fMRI of working memory and the exposure to head impact and working memory performance, and (3) assess whether wearing a neck collar designed to reduce intracranial slosh via mild compression of the jugular veins can ameliorate the changes in fMRI brain activation observed in the female high school athletes who did not wear collars after a full soccer season. A total of 48 female high school soccer athletes (age range: 14.00-17.97 years) were included in the study. These athletes were assigned to the non-collar group (n = 21) or to the collar group (n = 27). All athletes undewent MRI at both pre-season and post-season. In each session, a fMRI verbal N-Back task was used to engage working memory. A significant pre- to post-season increase in fMRI blood oxygen level dependent (BOLD) signal was demonstrated when performing the N-back working memory task in the non-collar group but not in the collar group, despite the comparable exposure to head impacts during the season between the two groups. The collar group demonstrated significantly smaller pre- to post-season change in fMRI BOLD signal than the non-collar group, suggesting a potential protective effect from the collar device. Significant correlations were also found between the pre- to post-season increase in fMRI brain activation and the decrease in task accuracy in the non-collar group, indicating an association between the compensatory mechanism in underlying neurophysiology and the alteration in the behavioral outcomes.

Twenty-year analysis of implant treatment in an Australian public dental clinic

BACKGROUND

This retrospective cohort study reviewed dental implant treatment completed at the Adelaide Dental Hospital over a 20-year period.

METHODS

The database of implant treatment completed between 1996 and 2015 was analysed for patient, implant, prosthesis and operator specifics together with known implant status.

RESULTS

Three hundred and twenty patients (mean age, 51.50 years) were treated with 527 implants. One hundred and eighty-four female patients received 296 implants and 136 males received 231 implants. Three hundred implants were restored with single crowns, 147 implants were restored with 63 mandibular implant overdentures, five implants were restored with two maxillary implant overdentures and 67 implants were restored with 20 full-arch fixed prostheses. The overall known implant survival rate was 87.67%. Mandibular implant overdentures had a risk of implant failure four times that of single implant-retained crowns that was statistically significant (P = 0.0100).

CONCLUSIONS

Implant treatment completed in this public sector clinic using finite resources and a defined system of patient and restorative selection criteria demonstrated a high known implant survival rate. Utilizing a structured and maintained patient recall protocol, it would be ideal to investigate further parameters of interest, particularly those that could improve treatment delivery and longevity.

Shared Reading Quality and Brain Activation during Story Listening in Preschool-Age Children

OBJECTIVE

To explore the relationship between maternal shared reading quality (verbal interactivity and engagement) and brain function during story listening in at-risk, preschool-age children, in the context of behavioral evidence and American Academy of Pediatrics, recommendations.

STUDY DESIGN

In this cross-sectional study, 22 healthy, 4-year-old girls from low socioeconomic status households completed functional magnetic resonance imaging using an established story listening task, followed by videotaped observation of uncoached mother-daughter reading of the same, age-appropriate picture book. Shared reading quality was independently scored applying dialogic reading and other evidence-based criteria reflecting interactivity and engagement, and applied as a predictor of neural activation during the functional magnetic resonance imaging task, controlling for income and maternal education.

RESULTS

Shared reading quality scores were generally low and negatively correlated with maternal distraction by smartphones (P < .05). Scores were positively correlated with activation in left-sided brain areas supporting expressive and complex language, social-emotional integration, and working memory (P <.05, false discovery rate corrected).

CONCLUSIONS

Maternal shared reading quality is positively correlated with brain activation supporting complex language, executive function, and social-emotional processing in at-risk, preschool-age children. These findings represent novel neural biomarkers of how this modifiable aspect of home reading environment may influence foundational emergent literacy skills, reinforce behavioral evidence and American Academy of Pediatrics, recommendations, and underscore the potential of dialogic reading interventions to promote healthy brain development, especially in at-risk households.

Prosthodontic management of maxillofacial cases: a case series

Maxillofacial prosthetics is an important and recognized sub-discipline of prosthodontics that forms a key component of postgraduate training programmes. General dentists have a role to play in the management of maxillofacial defect patients even though treatment usually requires a multidisciplinary approach in an institutional environment. Maxillofacial prosthetic cases frequently present with complex histories but simple patient goals. The conservatively managed implant-retained auricular prosthesis, speech aid prosthesis and orbital prosthesis cases described in this report were completed in a postgraduate clinical residency program and highlight the intrinsic complexities, challenges and ultimately satisfaction related to cases of this nature.

Story time turbocharger? Child engagement during shared reading and cerebellar activation and connectivity in preschool-age children listening to stories

Expanding behavioral and neurobiological evidence affirms benefits of shared (especially parent-child) reading on cognitive development during early childhood. However, the majority of this evidence involves factors under caregiver control, the influence of those intrinsic to the child, such as interest or engagement in reading, largely indirect or unclear. The cerebellum is increasingly recognized as playing a "smoothing" role in higher-level cognitive processing and learning, via feedback loops with language, limbic and association cortices. We utilized functional MRI to explore the relationship between child engagement during a mother-child reading observation and neural activation and connectivity during a story listening task, in a sample of 4-year old girls. Children exhibiting greater interest and engagement in the narrative showed increased activation in right-sided cerebellar association areas during the task, and greater functional connectivity between this activation cluster and language and executive function areas. Our findings suggest a potential cerebellar "boost" mechanism responsive to child engagement level that may contribute to emergent literacy development during early childhood, and synergy between caregiver and child factors during story sharing.

All-ceramic crown preparations: An alternative technique

BACKGROUND

The aim of this study was to compare the crown preparation dimensions produced from two different techniques of preparation for posterior all-ceramic crowns.

METHODS

Twenty-four fourth year dental students undertook a course of advanced simulation training involving education in an alternative technique of preparation for a 36 all-ceramic crown. Crown preparations performed using the traditional technique were compared with an alternative technique for total occlusal convergence (TOC) and reduction difference (RD) using digital scanning and comparative software.

RESULTS

Groups that spent the most time performing the alternative technique produced crown preparations with significantly lower buccolingual (BL) TOC. The training resulted in crown preparations that were closer to ideal TOC and RD measurements.

CONCLUSIONS

The alternative technique of crown preparation for a posterior all-ceramic crown showed initial promise in creating a less buccolingually tapered and more ideally occlusally reduced crown preparation.