Examining the acceptability and feasibility of the Compassionate Mindful Resilience (CMR) programme in adults living with chronic kidney disease: the COSMIC study findings.

BACKGROUND: Individuals with chronic kidney disease experience difficult physical and psychological symptoms, that impact quality of life, and are at increased risk of anxiety and depression. Access to specialist psychological support is limited. This study aimed to support a new service development project, in collaboration with Kidney Care UK, to implement the Compassionate Mindful Resilience (CMR) programme, developed by MindfulnessUK, which provides accessible mindfulness techniques and practices to enhance compassion and resilience, and explore its feasibility for people living with stage 4 or 5 kidney disease and transplant. METHODS: A multi-method feasibility design was utilised. Participants over 18 years, from the UK, with stage 4 or 5 kidney disease or post-transplant, and who were not currently undergoing psychotherapy, were recruited to the four-week CMR programme. Data was collected at baseline, post-intervention and three-months post to measure anxiety, depression, self-compassion, mental wellbeing, resilience, and mindfulness. The acceptability of the intervention for a kidney disease population was explored through qualitative interviews with participants, and the Mindfulness Teacher. RESULTS: In total, 75 participants were recruited to the study, with 65 completing the CMR programme. The majority were female (66.2%) and post-transplant (63.1%). Analysis of completed outcome measures at baseline and post-intervention timepoints (n = 61), and three-months post intervention (n = 45) revealed significant improvements in participant's levels of anxiety (p < .001) and depression (p < .001), self-compassion (p = .005), mental wellbeing (p < .001), resilience (p.001), and mindfulness (p < .001). Thematic analysis of interviews with participants (n = 19) and Mindfulness Teacher (n = 1) generated three themes (and nine-subthemes); experiences of the CMR programme that facilitated subjective benefit, participants lived and shared experiences, and practicalities of programme participation. All participants interviewed reported that they found programme participation to be beneficial. CONCLUSION: The findings suggest that the CMR programme has the potential to improve psychological outcomes among people with chronic kidney disease. Future randomized controlled trials are required to further test its effectiveness.

Breaking down the Digital Fortress: The Unseen Challenges in Healthcare Technology-Lessons Learned from 10 Years of Research.

Healthcare is undergoing a fundamental shift in which digital health tools are becoming ubiquitous, with the promise of improved outcomes, reduced costs, and greater efficiency. Healthcare professionals, patients, and the wider public are faced with a paradox of choice regarding technologies across multiple domains. Research is continuing to look for methods and tools to further revolutionise all aspects of health from prediction, diagnosis, treatment, and monitoring. However, despite its promise, the reality of implementing digital health tools in practice, and the scalability of innovations, remains stunted. Digital health is approaching a crossroads where we need to shift our focus away from simply looking at developing new innovations to seriously considering how we overcome the barriers that currently limit its impact. This paper summarises over 10 years of digital health experiences from a group of researchers with backgrounds in physical therapy-in order to highlight and discuss some of these key lessons-in the areas of validity, patient and public involvement, privacy, reimbursement, and interoperability. Practical learnings from this collective experience across patient cohorts are leveraged to propose a list of recommendations to enable researchers to bridge the gap between the development and implementation of digital health tools.

Perceptibility and acceptability of lightness difference of a single maxillary central incisor.

OBJECTIVES: The aim of this study was to assess the lightness difference perceptibility and acceptability thresholds, for a single maxillary central incisor, and to investigate possible differences in these thresholds regarding the direction (+ΔL* vs. -ΔL*), the observer group (dentists vs. laypersons), and the gender and age of the observers. MATERIALS AND METHODS: A series of images with varying lightness (L*), were created by altering the right maxillary central incisor of a male Caucasian, on a frontal view full-portrait image. Digital modification of one central incisor by 1 ΔL* unit resulted in 15 different images: one control, seven with increased and seven with decreased lightness. The images were presented in random order, on a digitally calibrated monitor, to 158 observers, grouped into 79 dentists, and 79 laypersons, who were asked to evaluate every image and answer whether they perceive a difference and if yes, whether they accept this difference. A multifactorial analysis of covariance was performed to analyze the perception and acceptance of any difference in the central incisors and to estimate the thresholds. The statistical significance level was α = 0.05. RESULTS: Overall, the magnitude of ΔL*, direction of ΔL*, observer group and age were each significant (p < 0.001), as was gender (p = 0.03). The effect of the magnitude of ΔL* interacted with its direction and the observer group (p = 0.045), and the effect of age interacted with the direction of ΔL*, and the gender and the group of the observers. Estimated 50%:50% perceptibility thresholds ranged from 0.1 to 2.7, and 50%:50% acceptability thresholds ranged from 2.3 to 4.5. Overall, dentists perceived lightness differences at lower magnitudes than laypersons; difference in lightness was perceived and accepted at lower magnitudes when the tooth become lighter instead of darker; and female observers perceived and accepted lightness differences at lower magnitudes compared to males. As age increased overall, differences of lightness were perceived and accepted at higher magnitudes. CONCLUSIONS: Perceptibility and acceptability of lightness differences of a single maxillary central incisor are affected by the magnitude and the direction of lightness change, as well as the gender, the age, and the type of the observers. CLINICAL SIGNIFICANCE: Even small changes in lightness are perceivable; however, thresholds of perception and acceptance are dependent on the magnitude and the direction of change and are also dependent on the observer, with women, dentists and younger people perceiving and accepting changes at lower magnitudes of ΔL*.

Assessing color mismatch in single-shade composite resins for enamel replacement.

STATEMENT OF PROBLEM: Shade selection is a challenge in restorative dentistry. While single-shade composite resins may simplify this process, whether the color mismatch between this composite resin and the substrate is within acceptable levels to ensure successful outcomes is unclear. PURPOSE: The purpose of this in vitro study was to assess the influence of background and surrounding shade, thickness, and proximity to the surrounding on color mismatch when shaded and single-shade composite resins are used in the center of an enamel layer. MATERIAL AND METHODS: Two-layer specimens mimicking dentin (the background) and enamel (the surrounding and center) were prepared. Two shades were used for the background and the surrounding layer (OA1/A1 and OA3/A3). At the Ø3-mm center, 2 single-shade composite resins were placed, Omnichroma (OM) and Admira Fusion x-tra (FU), and also shaded composite resins A1, WE, A3, and C2. For the OA1/A1 background and surrounding, shades A1 and WE served as positive controls, while the A3 and C2 were negative controls. For OA3/A3, these controls were reversed. Two enamel layer thicknesses were evaluated (0.5- and 1.0-mm). Reflectance measurements were made at 0.0, 1.0, 2.0, and 2.5 mm from the center. Color differences were calculated between those at 2.5 mm and at other distances (ΔE0, ΔE1, and ΔE2). Data analysis employed a 4-way repeated measure ANOVA with Bonferroni corrections for the pair-wise comparisons (α=.05). RESULTS: Background and surrounding shade, central shade, distance, and thickness affected color mismatch (P<.05). For the OA1/A1 specimens, single-shade color mismatch values were found between both the positive and negative controls (P<.05). For the OA3/A3 specimens, the color mismatch did not differ significantly from that of negative controls (P>.05). No difference was found between ΔE0 and ΔE1, but each was distinct from ΔE2. Thickness did not affect the color mismatch of the single-shade composite resins (P<.05). CONCLUSIONS: Single-shade composite resins for enamel replacement showed higher color mismatches compared with positive controls.

A majority of trauma-related deep venous thromboses resolve prior to discharge.

Post-traumatic DVTs present unique challenges in patient populations with specific high-risk injury patterns. Duplex ultrasound (US) can be used to assess evolution of DVTs and may guide treatment for high-risk patients. We hypothesized that many DVTs resolve during the initial admission. Weekly duplex US are ordered on all trauma inpatients regardless of prior DVT at our facility. We reviewed US and outcomes data on all patients with lower extremity DVTs at our Level I trauma center from January 2012-December 2021. 392 patients were diagnosed with lower extremity DVT by US. 261 (67%) patients received follow-up US with a mean time to repeat US of 6 days. Of these, 91 (35%) patients experienced DVT resolution prior to the first follow-up US, and 141 (54%) patients experienced resolution prior to discharge. Mean time to resolution was 10 days. Over 50% of DVTs resolve before discharge and are detected by US. Further studies and post-discharge follow-up are needed to determine if patients with resolved DVTs can be managed without therapeutic anticoagulation.

Effect of monomer composition and filler fraction on surface microhardness and depth of cure of experimental resin composites.

This study evaluated microhardness profiles and calculated depths of cure at 80% of the surface microhardness of experimental dental resin composites having different base monomer compositions and different filler fractions. Composites were prepared using four different base monomers (bisphenol A-glycidyl methacrylate [Bis-GMA], urethane dimethacrylate [UDMA], ethoxylated bisphenol-A dimethacrylate [Bis-EMA], and Fit-852) with triethylene glycol dimethacrylate (TEGDMA) used as a co-monomer at three filler:resin matrix weight percent fractions (50:50, 60:40, and 70:30). Uncured material was placed in 3D printed molds and light cured for 40 s from the top surface only. Knoop microhardness was measured at the top of the specimen, and at every 0.5 mm up to 4 mm in depth. Microhardness at the surface increased in all experimental composites as the filler fraction increased. When comparing base monomers, microhardness was the highest in UDMA-based composites, while Bis-GMA-based composites showed the lowest values. When comparing depth of cure as a function of base monomer type, both Bis-GMA and Bis-EMA showed significantly lower values than UDMA or Fit-852. Composites having 50 wt% filler showed a significantly higher depth of cure than those with 60 and 70 wt% filler. Base monomer and filler fraction significantly influence microhardness and depth of cure in these experimental composites.

Coverage error of three resin composite systems to vital unrestored maxillary anterior teeth.

OBJECTIVE: Define the color of anterior teeth of a selected population and correlate it (by using coverage error [CE] and the frequency of best match) with the final color of all possible enamel-dentine combinations of three different resin composite systems. MATERIALS AND METHODS: Color of 636 vital unrestored anterior teeth (central incisors, lateral incisors and canines; n = 212) and disk specimens (12 mm diameter, varying thickness) corresponding to enamel-dentin combinations of all available enamel (0.5 mm and 1.0 mm thickness) and dentin shades (3.0 mm thickness) of Essentia, Enamel Plus HRi and IPS Empress Direct composite systems was measured using a clinical dental spectrophotometer (Spectroshade Micro). CE and frequency of best match for all composite systems were calculated for the measured in-vivo teeth color space. RESULTS: Natural in-vivo teeth exhibit higher lightness when compared to enamel-dentin composite combinations, independently of the enamel thickness used. The best (lowest) CE was found for IPS Empress, while the highest values were found for Enamel Plus Hri independently of tooth type and enamel thickness (p < 0.001). The use of 0.5 mm instead of 1.0 mm enamel thickness within enamel-dentin composite combinations resulted in a lower CE for in-vivo tooth color (p < 0.001). CONCLUSIONS: The color space defined by all possible enamel-dentin combinations of the studied resin composite systems does not fully match the color range of anterior teeth. All composite systems examined lack combinations with lightness values as high as the population's. IPS Empress Direct composite system represented better the in-vivo teeth color. CLINICAL SIGNIFICANCE: The use of 0.5 mm enamel shade thickness is suggested when building layered restorations, as it provided better color coverage than using 1.0 mm thickness.

Effect of cross-polarization filters on the trueness of colors obtained with a single-lens reflex camera, macro lens, and a ring flash.

OBJECTIVE: To investigate the effect of cross-polarization filters on the colors of shade tabs obtained with a digital single-lens reflex (DSLR) camera, macrolens, and a ring flash. MATERIALS AND METHODS: Digital images of four shade tables (1M1, 3L2.5, 3R2.5, and 5M3) from the VITA Toothguide 3D-Master shade guide were taken using a DSLR camera, 100 mm macrolens, and ring flash with two different cross-polarizing filters (Polar_eyes and Filtropolar), and without (Nonpolarizer; n = 7). The CIE L*a*b* color coordinates of digital images were calculated and remeasured with a spectroradiometer (SR). The color differences (ΔE00 ) between the SR and digital images were calculated and analyzed with the two-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05). RESULTS: ΔE00 values of all test groups were higher than the clinically acceptable threshold (∆E00 > 1.80). While the ∆E00 values of Filtropolar (6.19 ± 0.44) and Polar_eyes (7.82 ± 0.23) groups were significantly higher than the Nonpolarizer (4.69 ± 0.32) for the 1M1 shade tab, ∆E00 value of Polar_eyes (6.23 ± 0.34) was significantly lower than Nonpolarizer (10.71 ± 0.48) group for 5M3 shade tab (p < 0.05). CONCLUSION: The color-matching results of tested digital photography techniques with and without cross-polarization were unacceptable, compared to a spectroradiometer. While digital photography with Polar_eyes cross-polarizing filter has closer results to the reference device for the low-in-value shade table (5M3), for the high-in-value shade table (1M1), improved results were obtained without a cross-polarizing filter. CLINICAL SIGNIFICANCE: The cross-polarization filters are increasingly used in dentistry for tooth color communication with digital photography techniques. However, the digital photography techniques with-without cross-polarization filterers should be improved to obtain clinically acceptable color-matching results.

Error analysis of stages involved in CBCT-guided implant placement with surgical guides when different printing technologies are used.

STATEMENT OF PROBLEM: Digital light processing (DLP), continuous liquid interface printing (CLIP), and stereolithography (SLA) technologies enable 3-dimensional (3D) printing of surgical guides. However, how their accuracy compares and how accuracy may affect subsequent steps in guided surgery is unclear. PURPOSE: The purpose of this in vitro study was to investigate the fabrication and seating accuracy of surgical guides printed by using DLP, SLA, and CLIP technologies and evaluate the positional deviation of the osteotomy site and placed implant compared with the digital implant plan. MATERIAL AND METHODS: Twenty-one polyurethane models were divided into 3 groups and used to plan implants and design surgical guides. The guides were fabricated by using DLP, SLA, or CLIP 3D printers (n=7) and scanned, and the scan file was compared with the digital design file to analyze the fabrication accuracy at the intaglio and overall external surfaces using root mean square (RMS) values. The triple scan protocol was used to evaluate the seating accuracy of the guides on their respective models. Osteotomies were prepared on models by using the guides followed by a microcomputed tomography image of each osteotomy. The implants were placed through the guides, the scan bodies were tightened to implants, and the models were scanned to obtain the images of placed implant position. Osteotomy and placed implant images were used to calculate the entry point, apex, and long axis deviations from the planned implant position with a software program. A 2-way repeated-measures ANOVA of the RMS data was used to analyze printing and seating trueness, and homogeneity of variance analyses were used at each surface for precision. A 3-way repeated-measures ANOVA was used to analyze distance deviations over the stages (osteotomy and final implant) and locations studied, and a 2-way repeated-measures ANOVA was used for angular deviations. Homogeneity of variance analyses were performed for precision (α=.05). RESULTS: The 3D printer type significantly affected the trueness of the guide at the intaglio surface (P<.001). SLA guides had the lowest mean RMS (59.04 µm) for intaglio surface, while CLIP had the highest mean RMS (117.14 µm). Guides from all 3D printers had low variability among measured deviations and therefore were similarly precise. The seating accuracy of SLA and DLP guides was not significantly different, but both had lower mean RMS values than CLIP (P=.003 for SLA, P=.014 for DLP). There were no significant interactions between the stage of surgery, the printer type, or the location of implant deviation (P=.734). Only the location of deviation (cervical versus apical) had a significant effect on distance deviations (P<.001). The printer type, stage of surgery, and their interaction did not significantly affect angular deviations (P=.41). CONCLUSIONS: The 3D printing technology affected printing trueness. The intaglio surface trueness was higher with SLA and overall trueness was higher with the CLIP printer. The precision of all guides was similarly high. Guides from SLA and DLP printers had more accurate seating than those from CLIP. Higher deviations were observed at the apex; however, osteotomy and final implant position did not significantly differ from the digitally planned position.

Positional trueness of three removable die designs with different root geometries manufactured using stereolithographic 3D printing.

STATEMENT OF PROBLEM: Three-dimensional (3D) printed casts are a suitable alternative to dental stone casts. Contemporary dental design computer programs permit designing definitive casts with removable dies with different root geometries and retention mechanisms. Studies on the positional trueness of 3D-printed removable dies with different root geometries are lacking. PURPOSE: The purpose of this in vitro study was to investigate the 3D displacements of three 3D-printed removable die designs with different root geometries. MATERIAL AND METHODS: The digital file of a dental stone alveolar cast with root-form removable dies (MOD UJ IV Fixed Prosthetics; Ivoclar AG) was used as a reference to create 3 removable die and alveolar cast designs (Root Form, RF; Conical, CON; Cylindric, CYL) with different root geometries in 2 dental design computer programs (DentalCAD 3.1 Rijeka; exocad; GmbH; InLab CAD 22.0; Dentsply Sirona). 3 equidistant Ø1-mm spheres (C, Cervical; M, Middle; O, Occlusal) were designed on the buccal surface of the coronal portion of the removable die to evaluate their displacement. A total of 45 alveolar casts with 45 removable dies were fabricated using a stereolithographic 3D printer (Form 3; Formlabs); each die group consisted of 15 specimens. After fabrication and postprocessing, the specimens were scanned, and their digital files were analyzed in a metrology-grade computer program to evaluate the displacement of the removable dies with respect to the position of the die in the master reference file. Subsequently, the data were analyzed using a 3-way analysis of variance (ANOVA) followed by step-down Bonferroni-corrected pairwise comparisons (α=.05). RESULTS: Two statistically significant 2-way interactions were detected between the independent variables, die design and direction (P<.001), and location and direction (P<.001). The post hoc analysis identified significant differences between the displacement values of RF and CYL (P<.001) and RF and the CON (P<.001) designs on the Y axis. The measured displacements were statistically different between the C and O locations on the Y axis (P=.001) and the M and O locations on the Z axis (P=.006). CONCLUSIONS: The root geometry of a 3D-printed removable die and alveolar cast can affect seating, and variable degrees of tipping of the removable die can be seen. The seating and congruence of the removable die with the interocclusal space and relationships observed intraorally should be confirmed before adjusting indirect restorations.

Color and translucency of enamel in vital maxillary central incisors.

STATEMENT OF PROBLEM: Limited data, especially in vivo data, exist regarding translucency parameter (TP) values for vital anterior nonrestored dentition. Additionally, published information on the CIELab values of vital enamel at a theoretical infinite thickness is lacking. Obtaining TP and CIELab values in a population that varies in terms of ethnicity, age, and sex would be useful to inform the development and placement of esthetic dental restorations that more accurately capture the complex optical qualities of enamel. PURPOSE: The purpose of this clinical study was to investigate in vivo the TP and CIELab values of vital anterior incisor enamel at a theoretical infinite thickness in a diverse pool of participants who varied in age, ethnicity, and sex. MATERIAL AND METHODS: Spectral reflectance measurements (380 to 780 nm at 2-nm intervals) of the mid-incisal region of vital, unrestored maxillary anterior teeth were made in 120 participants, equally divided into 2 sexes, 4 racial or ethnic groups, and 5 age ranges. Instruments were oriented to achieve 0-degree observation and 45-degree illumination, and spectral measurements were made with white and black silicone backgrounds. Reflectance spectra of the incisal enamel from both the black and white silicone backing were used to fit to the Kubelka-Munk (K-M) reflectance theory. The CIEDE2000 color difference formula was used to determine TP, and data were compared among participant demographics. CIELab color coordinate values for enamel at an infinite thickness were calculated by using a D65 illumination and CIE standard human (2-degree) observer. To determine value ranges and significant differences among participant groups, CIELab values were analyzed with a 4-way ANOVA, and TP values were analyzed with a generalized linear mixed model. Pairwise comparisons of interest were evaluated with Bonferroni-corrected Student t tests. RESULTS: For maxillary central incisor enamel, the average TP was 10.1 ±3.6, and the average CIELab color coordinates were L∗=73.5 ±7.6, a∗=2.2 ±1.8, b∗=11.9 ±8.4. TP values of incisal enamel significantly differed among specific age and ethnic groups, with general significant interactions of age and sex (P=.009), as well as ethnicity and age (P=.042). CIE color coordinates of enamel at an infinite thickness were found in the L∗ coordinate among different age groups with the same sex and ethnicity, specifically when comparing CIELab direction with the population characteristics of age (P=.011) and the interaction between age, sex, and ethnicity (P=.035). CONCLUSIONS: In vivo L∗ values and TP values of incisal enamel differed significantly among groups determined by ethnicity, age, and sex.

Coloanal Anastomosis.

The furthest extent of restorative proctectomy involves a colon to anal anastomosis in the deep pelvis. While the anastomosis can be challenging, it can allow the patient to avoid a permanent ostomy. Patient and surgeon preparation can improve patient outcomes. This article will describe the options, technical challenges, and anecdotal tips for coloanal anastomosis.

Intermittent boluses of balanced salt solution for post-operative intravenous hydration following elective major abdominal and thoracic surgery in children.

PURPOSE: Maintenance fluids following major operations in children are typically administered with a continuous rate. We hypothesized that administering fluids as intermittent boluses is more physiologic and could limit post-operative fluid volume, thereby avoiding harmful effects of excess fluid. METHODS: We retrospectively reviewed children aged 1-21 admitted after an elective major abdominal or thoracic operation from 2015 to 2021. We excluded non-elective operations and patients receiving peri-operative enteral or parenteral nutrition. We analyzed total fluid volume at 0-24, 24-48, 48-72, and 72-96 h, time to regular diet and discharge, and end-organ complications. RESULTS: We identified 363 patients, of which 108 received intermittent boluses and 255 continuous fluids. Bolus group patients received significantly less fluid up to 72 h post-operatively with average rates of 0.49 mL/kg/h vs 0.86 mL/kg/h at 0-24 h (p << 0.01), 0.57 mL/kg/h vs 1.46 mL/kg/h at 24-48 h (p << 0.01), and 0.50 vs 0.92 mL/kg/h at 48-72 h (p << 0.01). Additionally, the bolus group maintained adequate urine output, tolerated a regular diet sooner (2.08 days vs 2.51 days; p = 0.0023) and averaged a shorter hospital stay (3.12 vs 4.14 days; p = 0.004). There was no difference in adverse effects between the two groups. CONCLUSION: Utilizing intermittent boluses reduces the volume of maintenance fluids administered and may lead to a faster time to regular diet and discharge. LEVEL OF EVIDENCE: IV. TYPE OF STUDY: Retrospective review.

Surgical considerations for neuroblastoma-associated opsoclonus-myoclonus-ataxia syndrome: a series of 14 patients from a single institution.

INTRODUCTION: Neuroblastoma is a childhood cancer of neural crest cells occasionally associated with opsoclonus-myoclonus-ataxia syndrome (OMAS), a paraneoplastic process characterized by ataxia, rapid eye movements, and muscle twitching. OMAS treatment and outcomes are well studied, but prior reports do not detail how the presence of OMAS should impact surgical approach, particularly for tumors with image defined risk factors (IDRF). METHODS: We reviewed patients with neuroblastoma and OMAS at our institution from January 2009 to December 2020 and recorded tumor characteristics, operative details, OMAS therapies, and outcomes. RESULTS: We identified 14 patients with neuroblastoma and OMAS out of 212 patients referred for surgery. There were 11 gross total resections and three partial resections. Two patients with partial resections developed OMAS after initial resection. One patient with gross total resection developed tumor recurrence 10 years later with OMAS redevelopment signaling recurrence. Three patients were positive for IDRFs and the one receiving neoadjuvant therapy achieved a gross total resection. CONCLUSIONS: OMAS development after partial resection and OMAS recurrence following tumor recurrence indicates a correlation between tumor bulk and the paraneoplastic process. This justifies an aggressive resection even for low-risk tumors. Neoadjuvant therapy should be considered for potentially unresectable tumors with image defined risk factors. LEVEL OF EVIDENCE: IV.

Displacement and performance of abutments in narrow-diameter implants with different internal connections.

STATEMENT OF PROBLEM: Displacement of abutments into conical connection implants during screw tightening may also occur during functional loading, creating unsettling forces that may cause loss of preload. A recent conical-hexagon connection with double friction fit (conical-hexagon connection) could prevent this axial displacement. PURPOSE: The purpose of this in vitro study was to measure the 3D axial displacement of abutments with a conical-hexagon connection or conical connection in narrow-diameter implants. Removal torque values (RTVs), preload efficiency, and survival after cyclic loading were also compared. MATERIAL AND METHODS: Narrow-diameter implants with a conical connection (Osseospeed EV, 3.0×13 mm-AST) and narrow-diameter implants with a conical-hexagon connection (Eztetic, 3.1×13 mm) were embedded in resin rods (G10) (n=6). Six titanium abutments per system were used, and their spatial relationship to the implant platforms after hand tightening was determined by using 3D digital image correlation. The abutments were tightened to the manufacturers' specified values, and the abutments' relative position was recorded again. The displacement of the abutment after tightening was calculated. The implants were subjected to cyclic loading (5×106 cycles at 2 Hz) under 200-N loads at a 30-degree angle. After cyclic loading, the RTVs of screws were measured and compared with those specified by the manufacturers to calculate preload efficiency. ANOVA was used to compare the differences in displacements after tightening and to compare differences in RTVs after cyclic loading across the groups (α=.05). RESULTS: The mean displacement in the U direction (X-axis) for the AST was -0.7 µm and -4.7 µm for ZIM, with no statistical difference (P=.73). The mean displacement in the V direction (Y-axis) for AST was -37.0 µm, and -150.0 µm for ZIM, with significant statistical difference (P<.001). The mean displacement in the W direction (Z-axis) for AST was -0.9 µm, and -23.0 µm for ZIM, with no statistical difference (P=.35). The survival of groups was similar (P=.058). During cyclic loading, 3 AST specimens fractured. After cyclic loading, mean RTV for AST was -8.77 Ncm, and -14.24 Ncm for ZIM, and these values were significantly different (P=.04). Preload efficiency was 28.1% for AST and 41.5% for ZIM. CONCLUSIONS: Greater abutment displacements were observed with the conical-hexagon connection, which required a higher torque, as specified by its manufacturer. The abutments displaced more in the V-axis in both implants. Only the conical connection implant (Ti Grade 4, commercially pure) had failures during cyclic loading, but the survival of the implants was similar. After cyclic loading, the abutment screws in both systems lost some of their torque value. The abutment screws of the conical-hexagon connection implant maintained preload more efficiently during cyclic loading than those of the conical connection implant.

Effect of cyclic loading on reverse torque values of angled screw channel systems.

STATEMENT OF PROBLEM: The angled screw channel concept has become popular. However, research is lacking as to how reverse torque values of nonaxially tightened implant crowns compare with axially tightened cement-retained crowns restored on angle-correcting abutments when subjected to long-term cyclic loading. PURPOSE: The purpose of this in vitro study was to evaluate the ability of different 25-degree angled screw channel hexalobular systems to apply the target torque value on their screws, the effect of cyclic loading on their reverse torque values, and their survival compared with crowns cemented on conventional 0-degree screw channel abutments. MATERIAL AND METHODS: A total of 28 implants were divided into 4 groups. Twenty-one angled screw channel crowns were fabricated at a 25-degree angle correction by using angled titanium (Ti) bases by 3 manufacturers DY (Dynamic Tibase), DE (AngleBase), and ASC (Angulated Screw Channel) (n=7). The fourth group, UB (Universal Base, Control), had cement-retained crowns with 25-degree custom-milled, angled zirconia abutments that were cemented onto their respective Ti bases (n=7). All implants were embedded in epoxy resin blocks and tightened to manufacturer recommended values: 35 Ncm for ASC, UB, and DE and 25 Ncm for DY. Initial torque values (ITV1) were recorded. After 24 hours, the reverse torque values (24hr-RTV1) were recorded. A new set of screws was then used for each group, and the initial torque values (ITV2) were recorded. Specimens were loaded at 2 Hz for 5 million cycles under a 200-N load, and reverse torque values (RTV2) were recorded. ANOVA (α=.05) was used to compare differences in the means of deviation of initial torque values and means of reverse torque values followed by a Tukey-Kramer post hoc analysis (α=.05). Preload efficiency was calculated for each system (RTV2/ITV2), and a survival analysis was performed by using the Lifetest procedure. RESULTS: A significant difference in the means of deviation of initial torque values of the groups with 25-degree torque application (DY, DE, and ASC) was found when compared with UB at 0 degrees. ASC and DE had lower initial torque values than UB (P<.001 and P=.003 for ASC ITV1 and ITV2, P<.001 and P=.006 for DE ITV1 and ITV2). A significant difference was found in mean reverse torque values both for after 24 hours and after cyclic loading among all groups (P<.001). A significant difference was found between mean reverse torque values before and after cyclic loading for each group (P<.001). Preload efficiency was 43.8% for DY, 46.8% for DE, 54.2% for ASC, and 48.5% for UB. No significant difference was found in the time-to-failure survival among groups (P>.05). CONCLUSIONS: The hexalobular system of DY delivered comparable initial torque values to its target value at 25 degrees, similar to how UB (control group) delivered at 0 degrees. ASC and DE scored lower initial torque values than their target value compared with UB. The DY abutment, which had a lower manufacturer recommended torque value, had lower reverse torque values compared with those of other groups. Time-to-failure survival of all groups was similar. Fractures at the zirconia to titanium base connection were seen with ASC crowns.

Effect of crown height on the screw joint stability of zirconia screw-retained crowns.

STATEMENT OF PROBLEM: Medium- to long-term data for the performance of zirconia crowns with titanium (Ti) bases are sparse, particularly when the crown height space and occlusal loads are high. PURPOSE: The purpose of this in vitro study was to assess the effect of the height of zirconia screw-retained implant crowns with a Ti base on the screw joint stability after cyclic loading. A secondary aim was to investigate the survival of zirconia crowns of different heights after cyclic loading. MATERIAL AND METHODS: Twenty-one internal connection implants were secured between fiberglass-reinforced epoxy resin sleeves. Mandibular first molar monolithic zirconia crowns with 3 different heights (6 mm, 10 mm, and 14 mm) were milled and bonded to the Ti bases (n=7). The screws were tightened to 30 Ncm, and a 30-degree 120-N cyclic load was applied to the crowns at 2 Hz for 5 million cycles. After 5 million cycles, the crowns were evaluated for stability, and the same protocol was repeated for 275-N and 435-N loads for 5 million cycles each. After loading, the detorque values were recorded. Failure was characterized based on whether the crown, screw, and/or implant fracture was observed. The detorque values were analyzed by using a 1-way-ANOVA with the restricted maximum likelihood estimation. The percentage of torque loss was calculated. The LIFETEST procedure was used to analyze the survival probability of the groups (α=.05). RESULTS: The effect of crown height on the detorque values of screws was not found to be statistically significant (P>.05). The mean detorque value for 6-mm crowns was 23.5 Ncm, 24.4 Ncm for 10-mm crowns, and 22.1 Ncm for 14-mm crowns. A significant effect of crown height was found on the survival (P=.006), and the time-to-failure survival of 14-mm crowns was significantly lower than the survival of 6 mm and 10 mm crowns (P=.020), where no failures were observed. Four 14-mm crowns failed between the 1 and 2 million cycles after the loads were increased to 435 N. The failure modes were the same for all the crowns, implants, and screws fractured. CONCLUSIONS: When the tested internal connection implant was used, the crown height did not affect the detorque values, and 14-mm crowns performed similarly to the shorter crowns in terms of torque loss after cyclic loading. However, survival of the 14-mm crown-implant complex was lower, resulting in screw and implant fractures.

Effect of three-dimensionally printed surface patterns on the peak tensile load of a plasticized acrylic-resin resilient liner.

STATEMENT OF PROBLEM: Stereolithographic (SLA) three-dimensional (3D) printing is considered a reliable manufacturing method for immediate complete dentures. However, studies on the implementation of computer-generated surface patterns to promote the union between printed denture base polymers and dental materials with different chemistries such as plasticized acrylic-resin resilient liners are lacking. PURPOSE: The purpose of this in vitro study was to assess the effect of 3D-printed surface patterns on the peak tensile load of a short-term plasticized acrylic-resin resilient liner. MATERIAL AND METHODS: A total of 30 denture base specimens (Denture Base LP; FormLabs) were fabricated with 3 adhesive surface designs by using an SLA 3D printer (Forms2; FormLabs). Twenty specimens were designed with surface patterns in the adhesive areas (grid and spheres); 10 specimens comprised each surface pattern group. The remaining specimens were roughened with 220-grit silicon carbide paper and served as a control. A commonly used short-term resilient liner (CoeSoft; GC-America) was applied to the adhesive surface of all the specimens. Subsequently, the specimens were kept in distilled water at 37 °C for 48 hours. The specimens were tested in a universal testing machine, and the resulting peak tensile load data were analyzed by using a 1-way analysis of variance (ANOVA) and a post hoc Tukey test (α=.05). RESULTS: The groups with surface patterns on the adhesive surface displayed higher peak tensile load values than the control group. The mean peak tensile load of the grid group was 6.73 ±0.43 N, and that for the spheres group was 6.58 ±0.33 N. The control group displayed the lowest mean peak tensile load (2.71 ±0.51 N). Statistically significant differences were detected between the mean peak tensile loads of the surface pattern groups and the control group (P<.001) No statistically significant difference was found between the mean peak tensile loads of the grid and spheres groups (P=.893). CONCLUSIONS: Incorporating surface patterns on the intaglio surface of denture bases made with Denture Base LP via SLA 3D printing can enhance their union to a plasticized acrylic-resin resilient liner. Surface patterns generated higher peak tensile load values than slightly roughening the surface of a 3D-printed denture with a 220-grit silicon carbide paper. No significant differences in the mean peak tensile loads were observed between the 2 types of surface patterns.

Adhesive strength of 3 long-term resilient liners to CAD-CAM denture base polymers and heat-polymerized polymethyl methacrylate with thermocycling.

STATEMENT OF PROBLEM: Computer-aided design and computer-aided manufacturing (CAD-CAM) technologies have become popular for manufacturing complete dentures. However, the adhesive strength of resilient liners to the polymers used to fabricate CAD-CAM complete dentures is unclear. PURPOSE: The purpose of this in vitro study was to determine the adhesive strength of 3 long-term resilient liners to CAD-CAM denture base polymers and heat-polymerized PMMA with thermocycling. MATERIAL AND METHODS: A total of 90 specimens were fabricated, 30 per group of denture base material (Lucitone 199, Ivo Base CAD, Denture Base LP). For each denture base polymer, 10 specimens were relined with 1 of 3 resilient liners (Permasoft, Mucopren Soft, Molloplast-B). Five specimens of each group were thermocycled, and the other 5 specimens were stored in distilled water. Subsequently, the adhesive strength of the specimens was assessed by tensile testing. The resulting data were analyzed by using a 3-way analysis of variance (ANOVA) (α=.05). RESULTS: After thermocycling, the adhesive strengths of all the resilient liners were found to be statistically different from each other for the same denture base polymer (P≤.012). Mucopren Soft displayed a high mean ±standard deviation adhesive strength to Lucitone 199 (1.78 ±0.32 MPa), followed by Molloplast-B (1.27 ±0.21 MPa) and Permasoft (0.66 ±0.06 MPa). For Ivo Base CAD, Molloplast-B exhibited a high mean ±standard deviation adhesive strength (1.70 ±0.36 MPa), followed by Mucopren Soft (1.11 ±0.16 MPa) and Permasoft (0.53 ±0.04 MPa). Molloplast-B displayed high mean ±standard deviation adhesive strength to Denture Base LP (1.37 ±0.08 MPa), followed by Mucopren Soft (0.68 ±0.20 MPa) and Permasoft (0.32 ±0.04 MPa). The adhesive strength of the majority of resilient liners not exposed to thermocycling was statistically different from each other for the same type of denture base polymer (P<.001). The only exception was the difference between the adhesive strength of Molloplast-B and Mucopren Soft to Lucitone 199 with mean ±standard deviation values of 1.42 ±0.18 and 1.66 ±0.40 MPa, respectively, (P=.067). Without thermocycling, the mean ±standard deviation adhesive strength to Lucitone 199 of Permasoft (0.57 ±0.02 MPa) was statistically different from that of Molloplast-B and Mucopren Soft (P<.001). Molloplast-B displayed a high mean ±standard deviation adhesive strength to Ivo Base CAD (1.83 ±0.25 MPa), followed by Mucopren Soft (1.26 ±0.19 MPa) and Permasoft (0.58 ±0.08 MPa). Molloplast-B displayed a high mean ±standard deviation adhesion to Denture Base LP (1.76 ±0.23 MPa), followed by Mucopren Soft (0.88 ±0.14 MPa) and Permasoft (0.25 ±0.06 MPa). Only Molloplast-B was significantly adversely affected by thermocycling (P=.009). CONCLUSIONS: Molloplast-B displayed high adhesive strength to both CAD-CAM denture base polymers regardless of the storage conditions. Mucopren Soft displayed high adhesion to Lucitone 199. Permasoft presented moderate adhesion to PMMA-based denture bases and low adhesion to DBLP. Combining Permasoft with Denture Base LP should be considered carefully and limited to short-term use. Thermocycling had a detrimental effect on the adhesive strength of Molloplast-B.

ICP-MS measurements of elemental release from two palladium alloys into a corrosion testing medium for different solution volumes and agitation conditions.

STATEMENT OF PROBLEM: The in vivo release of Pd from palladium alloys into the oral environment and sensitivity reactions by patients has been of concern. However, little information is available about the variation in elemental release from different palladium alloys. PURPOSE: The purpose of this in vitro study was to compare the elemental release into a corrosion-testing medium from a high-palladium alloy (Freedom Plus, 78Pd-8Cu-5Ga-6In-2Au) and a Pd-Ag alloy (Super Star, 60Pd-28Ag-6In-5Sn) under different conditions. MATERIAL AND METHODS: Alloys were cast into Ø12×1-mm-thick disks, subjected to simulated porcelain-firing heat treatment, polished, and ultrasonically cleaned in ethanol. Three specimens of each alloy were immersed for 700 hours in a solution for in vitro corrosion testing (ISO Standard 10271) that was maintained at 37 °C. Two solution volumes (125 mL and 250 mL) were used, and the solutions were subjected to either no agitation or agitation. Elemental compositions of the solutions were analyzed by using inductively coupled plasma-mass spectroscopy (ICP-MS). Concentrations of released elements from each alloy for the 2 solution volumes and agitation conditions were compared by using the restricted maximum likelihood estimation method with a 4-way repeated-measures ANOVA, the Satterwhite degrees of freedom method, a lognormal response distribution, and the covariance structure of compound symmetry. RESULTS: For the 4 combinations of solution volume and agitation conditions, the mean amount of palladium released was 3 orders of magnitude less for the Pd-Ag alloy (0.009 to 0.017 µg/cm2 of alloy surface) compared with the Pd-Cu-Ga alloy (17.9 to 28.7 µg/cm2). Larger mean amounts of Sn, Ga, Ag, and In (0.29 to 0.39, 0.57 to 0.83, 0.71 to 1.08, and 0.91 to 1.25 µg/cm2, respectively) compared with Pd were released from the Pd-Ag alloy. Smaller amounts of Cu, Ga, and In (4.8 to 9.9, 5.9 to 12.8, and 4.2 to 9.5 µg/cm2, respectively) compared with Pd were released from the Pd-Cu-Ga alloy. The Ru released was much lower for the Pd-Ag alloy (0.002 µg/cm2) than the Pd-Cu-Ga alloy (0.032 to 0.053 µg/cm2). Statistically significant differences (P<.001) in elemental release were found for the factors of alloy and element and the alloy×element interaction. Significant differences were found for the solution volume (P=.022), solution volume×element interaction (P=.022), and alloy×solution volume×element interaction (P=.004). No significant effect was found for agitation condition. CONCLUSIONS: The relative amounts of released elements from each alloy were not proportional to the relative amounts in the composition. The amounts of Pd and Ga released from the Pd-Cu-Ga alloy were consistent with the breakdown of a Pd2Ga microstructural phase and perhaps some dissolution of the palladium solid solution matrix. Precipitates, rather than the palladium solid solution matrix, appeared to undergo greater dissolution in the Pd-Ag alloy. The Pd-Ag alloy should have lower risk of adverse biological reactions than the Pd-Cu-Ga alloy.