Effect of thermomechanical aging on force system of orthodontic aligners made of different thermoformed materials : An in vitro study.

PURPOSE: The aim was to investigate the effect of aging by thermocycling and mechanical loading on forces and moments generated by orthodontic clear aligners made from different thermoplastic materials. METHODS: A total of 25 thermoformed aligners made from 5 different materials, i.e., Essix ACE® and Essix® PLUS™ (Dentsply Sirona, Bensheim, Germany), Invisalign® (Align Technology, San Jose, CA, USA), Duran®+ (Iserlohn, Germany), Zendura™ (Fremont, CA, USA), underwent a 14-day aging protocol involving mechanical loading (a 0.2 mm vestibular malalignment of the upper left second premolar [tooth 25]) and thermocycling in deionized water (temperature range 5-55 °C). The 3D forces/moments exerted on tooth 25 of a resin model were measured at three time points: before aging (day 0), after 2 days and after 14 days of aging. RESULTS: Before aging, extrusion-intrusion forces were 0.6-3.0 N, orovestibular forces were 1.7-2.3 N, and moments as mesiodistal rotation were 0.3-42.1 Nmm. In all directions, multilayer Invisalign® exhibited the lowest force/moment magnitudes. After aging, all materials showed a significant force/moment decay within the first 2 days, except Invisalign® for orovestibular and vertical translation. However, following thermomechanical aging, Duran®+ and Zendura™ aligners had equivalent or even higher vestibular forces (direction of mechanical load). CONCLUSION: Thermomechanical aging significantly reduced forces and moments during the first 48 h. Multilayer aligner materials exhibit lower initial forces and moments than single-layer ones, and were less influenced by aging. Material hardening was observed after subjecting some of the aligner materials to mechanical loading. Thus, orthodontists should be aware of possible deterioration of orthodontic aligners over time. This work also sheds light on how material selection impacts the mechanical behavior of aligners and may provide valuable guidance regarding optimal timing for the aligner changing protocol.

Effect of material composition and thickness of orthodontic aligners on the transmission and distribution of forces: an in vitro study.

OBJECTIVES: To investigate the effects of material type and thickness on force generation and distribution by aligners. MATERIALS AND METHODS: Sixty aligners were divided into six groups (n = 10): one group with a thickness of 0.89 mm using Zendura Viva (Multi-layer), four groups with a thickness of 0.75 mm using Zendura FLX (Multi-layer), CA Pro (Multi-layer), Zendura (Single-layer), and Duran (Single-layer) sheets, and one group with a thickness of 0.50 mm using Duran sheets. Force measurements were conducted using Fuji® pressure-sensitive films. RESULTS: The lowest force values, both active and passive, were recorded for the multi-layered sheets: CA Pro (83.1 N, 50.5 N), Zendura FLX (88.9 N, 60.7 N), and Zendura Viva (92.5 N, 68.5 N). Conversely, the highest values were recorded for the single-layered sheets: Duran (131.9 N, 71.8 N) and Zendura (149.7 N, 89.8 N). The highest force was recorded at the middle third of the aligner, followed by the incisal third, and then the cervical third. The net force between the incisal and cervical thirds (FI-FC) showed insignificant difference across different materials. However, when comparing the incisal and middle thirds, the net force (FI-FM) was higher with single-layered materials. Both overall force and net force (FI-FM) were significantly higher with 0.75 mm compared to those with a thickness of 0.50 mm. CONCLUSIONS: Multi-layered aligner materials exert lower forces compared to their single-layered counterparts. Additionally, increased thickness in aligners results in enhanced retention and greater force generation. For effective bodily tooth movement, thicker and single-layered rigid materials are preferred. CLINICAL RELEVANCE: This research provides valuable insights into the biomechanics of orthodontic aligners, which could have significant clinical implications for orthodontists. Orthodontists might use this information to more effectively tailor aligner treatments, considering the specific tooth movement required for each individual patient. In light of these findings, an exchangeable protocol for aligner treatment is suggested, which however needs to be proven clinically. This protocol proposes alternating between multi-layered and single-layered materials within the same treatment phase. This strategy is suggested to optimize treatment outcomes, particularly when planning for a bodily tooth movement.

Effect of attachment configuration and trim line design on the force system of orthodontic aligners: A finite element study on the upper central incisor.

OBJECTIVES: To use the finite element method (FEM) to investigate the effect of various attachment configurations and trimming line designs of orthodontic aligners on their biomechanical performance. METHOD: A 3D upper jaw model was imported into 3D design software. The upper right central incisor tooth (Tooth 11) was made mobile, and its periodontal ligament (PDL) and bone structures were designed. Aligners were modelled with three distinct attachment configurations: No attachment, rectangular horizontal, rectangular vertical, and two trimming line designs; scalloped and straight extended, with a homogeneous thickness of 0.6 mm. These models were then imported into an FE software. Simulations were conducted for three different movements, including facial translation, distalization, and extrusion. RESULTS: Forces were recorded at 1.3-2.6 N during facial translation, 1.4-5.9 N in distalization, and 0.0-2.0 N in extrusion. The straight extended trimming line consistently generated higher forces than the scalloped design. Attachments had no significant impact on force components during facial translation but were more effective in distalization and extrusion. The combination of a straight extended trimming line with horizontal attachments exhibited the least stresses at the apical third during distalization, and the highest stresses during extrusion, suggesting superior retention. CONCLUSIONS: Rectangular attachments offer limited benefits in facial translation, but horizontal rectangular attachments can intensify load in distalization and are crucial for force generation in extrusion. Horizontal attachments are preferred over vertical options. Additionally, the straight extended trim line enhances control of tooth movement and can replace attachments in certain cases. CLINICAL RELEVANCE: These findings provide biomechanical evidence and an optimal protocol to guide clinical practice in planning diverse teeth movements. The emphasis is on the influence of attachment utilization and the specific design of aligner trimming lines to enhance control over tooth movement.

Numerical biomechanical finite element analysis of different trimming line designs of orthodontic aligners: An in silico study.

BACKGROUND: A finite element model was used to investigate the effect of different designs and thicknesses of orthodontic aligner margins on their biomechanical behavior. METHODS: A three-dimensional data set of an upper jaw was imported into the 3-matic software. The upper right central incisor tooth (Tooth 11) was separated from the remaining model, and its periodontal ligament and surrounding bone were designed. Aligners were designed with four different trimming lines (scalloped, straight, scalloped extended, straight extended), each with four different thicknesses (0.3, 0.4, 0.5, and 0.6 mm). The models were imported into a finite element package (Marc/Mentat). A linear elastic constitutive material model was applied. A facial 0.2 mm bodily malalignment of tooth 11 was simulated. RESULTS: The maximum resultant force was in the range of 1.0 N to 2.2 N. The straight trimming designs deliver higher resultant forces compared with scalloped trimming designs. Increasing the aligner thickness and/or extending the aligner edge beyond the gingival line leads to an increase in the resultant force. All designs showed an uneven distribution of the normal contact forces over the tooth surface with a predominant concentration toward the cervical third and distal third, particularly with the extended trimming designs. All designs showed uncontrolled tipping of the tooth. CONCLUSIONS: Based on the current model outcomes, the use of a straight extended trimming line design for aligners is favored because of its positive impact on force distribution and, consequently, the control of tooth movement. CLINICAL RELEVANCE: These findings provide aligner companies and orthodontists a valuable biomechanical evidence and guidance to enhance control over tooth movement and therefore optimize treatment outcomes. This can be achieved by trimming the edges of aligners with a straight extended design and selecting the appropriate aligner thickness.

Evaluation of micromotion in multirooted root analogue implants embedded in synthetic bone blocks: an in vitro study.

BACKGROUND: While conventional threaded implants (TI) have proven to be effective for replacing missing teeth, they have certain limitations in terms of diameter, length, and emergence profile when compared to customised root analogue implants (RAI). To further investigate the potential benefits of RAIs, the aim of this study was to experimentally evaluate the micromotion of RAIs compared to TIs. METHODS: A 3D model of tooth 47 (mandibular right second molar) was segmented from an existing cone beam computed tomography (CBCT), and a RAI was designed based on this model. Four RAI subgroups were fabricated as follows: 3D-printed titanium (PT), 3D-printed zirconia (PZ), milled titanium (MT), milled zirconia (MZ), each with a sample size of n = 5. Additionally, two TI subgroups (B11 and C11) were used as control, each with a sample size of n = 5. All samples were embedded in polyurethane foam artificial bone blocks and subjected to load application using a self-developed biomechanical Hexapod Measurement System. Micromotion was quantified by analysing the load/displacement curves. RESULTS: There were no statistically significant differences in displacement in Z-axis (the loading direction) between the RAI group and the TI group. However, within the RAI subgroups, PZ exhibited significantly higher displacement values compared to the other subgroups (p < 0.05). In terms of the overall total displacement, the RAI group showed a statistically significant higher displacement than the TI group, with mean displacement values of 96.5 µm and 55.8 µm for the RAI and TI groups, respectively. CONCLUSIONS: The RAI demonstrated promising biomechanical behaviour, with micromotion values falling within the physiological limits. However, their performance is less predictable due to varying anatomical designs.

Physiochemical and mechanical characterisation of orthodontic 3D printed aligner material made of shape memory polymers (4D aligner material).

OBJECTIVES: To conduct a physiochemical and mechanical material analysis on 3D printed shape-memory aligners in comparison to thermoformed aligners. MATERIALS AND METHODS: Four materials were examined, including three thermoformed materials: CA Pro (CP), Zendura A (ZA), Zendura FLX (ZF), and one 3D printed material: Tera Harz (TC-85). Rectangular strips measuring 50 × 10 × 0.5 mm were produced from each material. Five tests were conducted, including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), shape recovery tests, three-points bending (3 PB), and Vickers surface microhardness (VH). RESULTS: DSC recorded glass transition temperatures (Tg) at 79.9 °C for CP, 92.2 °C for ZA, 107.1 °C for ZF, and 42.3 °C for TC-85. In DMA analysis at 20-45 °C, a prominent decrease in storage modulus was observed, exclusively for TC-85, as the temperature increased. Notably, within the temperature range of 30-45 °C, TC-85 exhibited substantial shape recovery after 10 min, reaching up to 86.1 %, while thermoformed materials showed minimal recovery (1.5-2.9 %). In 3 PB test (at 30, 37, 45 °C), ZA demonstrated the highest force at 2 mm bending, while TC-85 exhibited the lowest. Regarding VH at room temperature, there was a significant decrease for both ZA and ZF after thermoforming. ZA had the highest hardness, followed by ZF and TC-85, with CP showing the lowest values. CONCLUSIONS: TC-85 demonstrates exceptional shape memory at oral temperature, improving adaptation, reducing force decay, and enabling, together with its higher flexibility, extensive tooth movement per step. Additionally, it maintains microhardness similar to thermoformed sheets, ensuring the durability and effectiveness of dental aligners. CLINICAL RELEVANCE: The 3D printed aligner material with shape memory characteristics (4D aligner) has revolutionized the orthodontic aligner field. It showed mechanical properties more suitable for orthodontic treatment than thermoforming materials. Additionally, it offers enhanced control over aligner design and thickness, while optimizing the overall workflow. It also minimizes material wastage, and reduces production expenses.

Effect of thermomechanical aging of orthodontic aligners on force and torque generation: An in vitro study.

The aim of the study is to investigate the effects of artificial aging by thermocycling and mechanical loading on force/torque delivery by thermoplastic orthodontic aligners. Ten thermoformed aligners, made of Zendura™ thermoplastic polyurethane sheets, were aged over two weeks in deionized water by thermocycling alone (n = 5) and by both thermocycling and mechanical loading (n = 5). The force/torque generated on upper second premolar (Tooth 25) of a plastic model was measured before aging (as control), and after 2, 4, 6, 10, and 14 days of aging, using a biomechanical set-up. Before aging, the extrusion-intrusion forces were in the range of 2.4-3.0 N, the oro-vestibular forces were 1.8-2.0 N, and the torques on mesio-distal rotation were 13.6-40.0 Nmm. Pure thermocycling had no significant effect on the force decay of the aligners. However, there was a significant decrease in force/torque after 2 days of aging for both thermocycling and mechanical loading aging group, which is no longer significant over 14 days of aging. In conclusion, artificial aging of aligners in deionized water with both thermocycling and mechanical loading results in a significant decrease in force/torque generation. However, mechanical loading of aligners has a greater impact than pure thermocycling.

Effect of trimming line design and edge extension of orthodontic aligners on force transmission: A 3D finite element study.

OBJECTIVES: To investigate in a numerical study the effect of the geometry and the extension of orthodontic aligner edges and the aligner thickness on force transmission to upper right central incisor tooth (Tooth 11). METHODS: A three-dimensional (3D) digital model, obtained from a 3D data set of a complete dentulous maxilla, was imported into 3-matic software. Aligners with four different trimming line designs (scalloped, straight, scalloped extended, straight extended) were designed, each with four different thicknesses (0.3, 0.4, 0.5, and 0.6 mm). The models were exported to a finite element (FE) software (Marc/Mentat). A facial 0.2 mm bodily malposition of tooth 11 was simulated. RESULTS: The maximum resultant force was in the range of (7.5 - 55.2) N. The straight trimming designs had higher resultant force than the scalloped designs. The resultant force increases with increasing the edge extension of the aligner. The normal contact forces were unevenly distributed over the entire surface and were concentrated in six areas: Incisal, Mesio-Incisal, Disto-Incisal, Middle, Mesio-Cervical, and Disto-Cervical. The resultant force increases super linearly with increasing thickness. CONCLUSIONS: The design of the trimming line, the edge extension, and the thickness of the aligner affect significantly the magnitude of the resultant force and the distribution of normal contact force. The straight extended trimming design exhibited better force distribution that may favor a bodily tooth movement. CLINICAL RELEVANCE: A straight extended trimming design of an orthodontic aligner may improve the clinical outcomes. In addition, the manufacturing procedures of the straight design are much simpler compared to the scalloped design.

Trueness and precision of milled and 3D printed root-analogue implants: A comparative in vitro study.

OBJECTIVES: The present study aimed to evaluate the accuracy (trueness and precision) of titanium and zirconia multi-rooted root analogue implants (RAIs) manufactured by milling and 3D-printing. METHODS: A multi-rooted RAI was designed based on a mandibular second molar segmented from cone-beam computed tomography (CBCT). The manufactured RAIs were divided into four groups: 3D-printed titanium (PT) and 3D-printed zirconia (PZ) (n=10 each), as well as milled titanium (MT) and milled zirconia (MZ) (n=5 each). The specimens were scanned with a high-precision scanner, and the scanned data were imported into 3D-measurement software to evaluate the precision and trueness of each group. Root mean square (RMS) deviations were measured and statistically analysed (One-way ANOVA, Tukey's, p≤0.05). RESULTS: PZ showed the highest precision with RMS value of 21±6 µm. Nevertheless, there was no statistically significant difference in precision among the other groups. Regarding trueness, MZ showed the highest trueness with RMS value of 66±3 µm, whereas MT showed the lowest trueness result. Inspection sections showed that MT had significantly high RMS deviation in the furcation area (612±64 µm), whereas PZ showed significantly high RMS deviation at the apical area (197±17 µm). CONCLUSIONS: The manufacturing process significantly influenced the RAI accuracy. PZ exhibited the highest precision, whereas MZ exhibited the highest trueness, followed by PT. Finally, our results suggest that 3D-printing can reproduce concave surfaces and less accessible areas better than milling. CLINICAL SIGNIFICANCE: Milled and 3D-printed RAIs showed promising results in terms of precision and trueness. However, further clinical research is needed to advocate their use as immediate implants. Additionally, the inherent volumetric changes of the various materials during manufacturing should be considered.

Computer-aided finite element model for biomechanical analysis of orthodontic aligners.

OBJECTIVES: To design a finite element (FE) model that might facilitate understanding of the complex mechanical behavior of orthodontic aligners. The designed model was validated by comparing the generated forces - during 0.2-mm facio-lingual translation of upper left central incisor (Tooth 21) - with the values reported by experimental studies in literature. MATERIALS AND METHODS: A 3D digital model, obtained from scanning of a typodont of upper jaw, was imported into 3-matic software for designing of aligners with different thicknesses: 0.4, 0.5, 0.6, 0.7 mm. The model was exported to Marc/Mentat FE software. Suitable parameters for FE simulation were selected after a series of sensitivity analyses. Different element classes of the model and different rigidity values of the aligner were also investigated. RESULTS: The resultant maximum forces generated on facio-lingual translation of Tooth 21 were within the range of 1.3-18.3 N. The force was direction-dependent, where lingual translation transmitted higher forces than facial translation. The force increases with increasing the thickness of the aligner, but not linearly. We found that the generated forces were almost directly proportional to the rigidity of the aligner. The contact normal stress map showed an uneven but almost repeatable distribution of stresses all over the facial surface and concentration of stresses at specific points. CONCLUSIONS: A validated FE model could reveal a lot about mechanical behavior of orthodontic aligners. CLINICAL RELEVANCE: Understanding the force systems of clear aligner by means of FE will facilitate better treatment planning and getting optimal outcomes.

Effect of trimming line design and edge extension of orthodontic aligners on force transmission: An in vitro study.

OBJECTIVES: To investigate how the stress distribution and forces transmitted from orthodontic aligners to the tooth surface are affected by the geometry and extension of the trimming line. MATERIALS AND METHODS: Thirty-six aligners were thermoformed from Zendura FLX sheets (0.75 mm thick) and divided into four groups based on the design of the trimming line: Scalloped, Scalloped extended, Straight and Straight extended. Fuji pressure-sensitive films were used for pressure measurement. The pressurized films were scanned and evaluated. Pressures and forces were measured over the entire facial surface of an upper right central incisor (Tooth 11) and at 7 different locations [cervical, middle, incisal, mesio-incisal, mesio-cervical, disto-incisal, and disto-cervical]. In addition, the thickness of the aligners at these 7 sites was measured with a digital caliper. RESULTS: The active force ranged from (2.2 to 6.9) N, and the average pressure was (1.6-2.7) MPa. The highest values were recorded for the (straight extended) design, while the lowest values were recorded for the scalloped design. The forces and stresses were not uniformly distributed over the surface. When the values in each area were compared separately, significant differences were found between the different designs in the cervical area, with the scalloped design transmitting the lowest cervical forces. Aligner thickness was drastically reduced (60-75% thinning) over the entire tooth surface after thermoforming. CONCLUSIONS: The straight extended design of aligner's trimming line exhibited more uniform force transfer and stress distribution across the surface than the other designs. CLINICAL RELEVANCE: The trimming line design could have a significant impact on the clinical outcome of orthodontic aligner treatment.

Biomechanical behavior of endodontically treated premolars restored with different endocrown designs: Finite element study.

PURPOSE: Although endocrown is a successful restorative approach for endodontically treated molars, its survival rate in endodontically treated premolars with extensive loss of coronal structure has been debated. The aim of this study was to evaluate the biomechanical behavior of endodontically treated maxillary premolars restored with different lithium disilicate endocrown designs. MATERIALS AND METHODS: Based on cone-beam computed tomography (CBCT) of an intact maxillary premolar, five models were designed. Model A: fiber post, core, and crown; Model B: endocrown, 5 mm pulpal extension and butt margin; Model C: endocrown, 5 mm pulpal extension and axial extension; Model D: Endocrown, 3 mm pulpal extension and butt margin; Model E: Endocrown, 3 mm pulpal extension and axial extension. The bone geometry was simplified as a cylinder of compact and trabecular bone. All models were imported into finite element analysis (FEA) software, where the base of the bone cylinder was chosen as fixed support. Axial and oblique loads of 100 N each were applied separately to each model, and static structural analysis was performed. RESULTS: Regardless of the design of the endocrown, the resulting von Mises stresses were far below the yield strength of the tooth structure and the flexural strength of the ceramic material. The generated von Mises stresses on the restoration decreased by 15% in the models with 3 mm pulp extension (D and E) compared to the 5-mm pulpal extension models. In addition, the resulting von Mises stresses on the tooth structure decreased also by 15% in models C and E with the axial extension compared to models B and D with the butt margin. CONCLUSION: Endocrown is a suitable restoration for endodontically treated maxillary premolars. Furthermore, reducing the depth of the pulpal extension to 3 mm with the addition of an axial extension resulted in a more favorable stress distribution within the tooth-restoration interface.

MELD score is predictive of 90-day mortality after veno-arterial extracorporeal membrane oxygenation support.

BACKGROUND: The Model for End-Stage Liver Disease (MELD) score was originally described as a marker of survival in chronic liver disease. More recently, MELD and its derivatives, MELD excluding INR (MELD-XI) and MELD with sodium (MELD-Na), have been applied more broadly as outcome predictors in heart transplant, left ventricular assist device placement, heart failure, and cardiogenic shock, with additional promising data to support the use of these scores for prediction of survival in those undergoing veno-arterial extracorporeal membrane oxygenation (VA ECMO). METHODS: This study assessed the prognostic impact of MELD in patients with cardiogenic shock undergoing VA ECMO via a single-center retrospective review from January 2014 to March 2020. MELD, MELD-XI, and MELD-Na scores were calculated using laboratory values collected within 48 h of VA ECMO initiation. Multivariate Cox regression analyses determined the association between MELD scores and the primary outcome of 90-day mortality. Receiver operating characteristics (ROC) were used to estimate the discriminatory power for MELD in comparison with previously validated SAVE score. RESULTS: Of the 194 patients, median MELD was 20.1 (13.7-26.2), and 90-day mortality was 62.1%. There was a significant association between MELD score and mortality up to 90 days (hazard ratio (HR) = 1.945, 95% confidence interval (95% CI) = 1.244-3.041, p = 0.004) after adjustment for age, indication for VA ECMO, and sex. The prognostic significance of MELD score for 90-day mortality revealed an AUC of 0.645 (95% CI = 0.565-0.725, p < 0.001). MELD-Na score and MELD-XI score were not associated with mortality. CONCLUSION: MELD score accurately predicts long-term mortality and may be utilized as a valuable decision-making tool in patients undergoing VA ECMO.

Thermography as a non-ionizing quantitative tool for diagnosing periapical inflammatory lesions.

BACKGROUND: Thermography is a contemporary imaging modality based on acquiring and analyzing thermal data using non-contact devices. The aim of the present study was to assess the validity of thermography, compared with that of the reference-standard, for the diagnosis of periapical inflammatory lesions and to evaluate the temperature ranges for acute pulpitis with apical periodontitis (AAP), acute periapical abscess (AA) and chronic periapical abscess (CA). METHODS: AAP, AA and CA were diagnosed based on clinical and radiographic criteria. Thermographic data were acquired using the FLIR E-5 Infrared Camera. Extraoral thermal images were taken from the front and right and left sides of patients whose mouths were closed, and one intraoral thermal image was taken from the palatal perspective. Agreement in the diagnoses based on the combination of clinical and radiographic assessments and the thermographic evaluation was calculated. The temperature ranges of the three diagnostic subgroups were also measured. RESULTS: A total of 80 patients were enrolled in this study. The mean intraoral thermal image temperature for AA was 37.26 ± 0.36, that for CA was 35.03 ± 0.63 and that for AAP was 36.07 ± 0.45. The differences between the mean intraoral thermal temperatures of the three diagnostic groups were statistically significant (P < 0.001). The result of the Kappa coefficient of agreement between the combination of clinical and radiographic assessments and the thermographic evaluation was significant (P < 0.001). CONCLUSIONS: Thermography is an effective, quantitative and nonionizing approach that can be used for the diagnosis of periapical inflammatory lesions. The results of the present study indicated that the highest thermal image temperatures were recorded for AA. Thermography might be able to detect inflammatory reactions during the preclinical stage, leading to early diagnosis.

Primary Evaluation of Shape Recovery of Orthodontic Aligners Fabricated from Shape Memory Polymer (A Typodont Study).

As an innovative approach to overcome the rate-limiting staging of conventional aligners, using shape memory polymers (SMPs) as aligners' materials was investigated in this in vitro study. The ability of SMPs to shape recover and consequently move tooth, upon appropriate stimuli, was evaluated on a typodont model before clinical application. The study design was to achieve 1.9 mm correction movement of an upper central incisor by one aligner after multiple steps/activation. A custom-made aligned typodont model with a movable upper central incisor was scanned. Using an orthodontic software and a 3D printer, resin-models were generated. Seven aligners of ClearX sheets (SMPs) were fabricated by thermoforming on the resin aligned model. Each aligner was tested for repositioning of the central incisor in the typodont model. The model was scanned after each step and the corrective movement was measured through the superimposition of scans. Results showed that the total correction efficiency of the SMPs' aligner was ≈93% (1.76 mm). The corrective movement was 0.94 ± 0.04 mm after the reforming step, 0.66 ± 0.07 mm after the first activation step, and 0.15 ± 0.10 mm after the second activation step. It was concluded that aligners made of SMPs could have a promising future-use in orthodontic aesthetic treatment.

"To nitrous oxide, chloroform gives way": Was Dr. W.J.A. DeLancey's poetic license in advertising inspired?

Born in New Hampshire but raised in Massachusetts, 14-year-old William J.A. DeLancey became "the man of the house" after the accidental death of his father. Amiable and good humored, young DeLancey supported his widowed mother and his three sisters until the girls all reached maturity. After he married, DeLancey moved to Illinois and took up dentistry, eventually settling in Centralia. Following anesthesia training back east at Manhattan's Colton Dental Association, DeLancey returned to Centralia. There he practiced the Coltonian method of testing freshly made nitrous oxide upon himself before using the gas upon patients. Before his training at Colton Dental, DeLancey had advertised in Centralia newspapers only in prose. After he began administering laughing gas to his patients and to himself, DeLancey waxed poetic and began advertising in heroic couplets in local newspapers.

The polymerization efficiency of a bulk-fill composite based on matrix-modification technology.

OBJECTIVES: To evaluate the polymerization efficiency of a matrix-modified bulk-fill composite, and compare it to a conventional composite which has a similar filler system. The degree of conversion (DC%) and monomer elution were measured over different storage periods. Additionally, fillers' content was examined. MATERIALS AND METHODS: Cylindrical specimens were prepared, in bulk and incrementally, from Filtek Bulk Fill (B) and Filtek Supreme XTE (S) composites using a Teflon mold, for each test (n = 6). Using attenuated total reflection method of Fourier transformation infrared spectroscopy, DC% was measured after 24 hours, 7 days, and 30 days. Using high-performance liquid chromatography, elution of hydroxyethyl methacrylate, triethylene glycol dimethacrylate, urethane dimethacrylate, and bisphenol-A glycidyl dimethacrylate was measured after 24 hours, 7 days and 30 days. Filler content was examined by scanning electron microscopy (SEM). Data were analyzed using 2-way mixed-model analysis of variance (α = 0.05). RESULTS: There was no significant difference in DC% over different storage periods between B-bulk and S-incremental. Higher monomer elution was detected significantly from S than B. The elution quantity and rate varied significantly over storage periods and between different monomers. SEM images showed differences in fillers' sizes and agglomeration between both materials. CONCLUSIONS: Matrix-modified bulk-fill composites could be packed and cured in bulk with polymerization efficiency similar to conventional composites.

Evaluation of Two Resin Composites Having Different Matrix Compositions.

This study compared two resin composites with similar filler systems and different matrix compositions. The depth of cure (DoC), polymerization shrinkage, and marginal leakage were evaluated. A Filtek Bulk Fill resin composite (FB) and a Filtek Supreme resin composite (FS) were used. For the DoC and polymerization shrinkage, cylindrical specimens with different thicknesses were prepared. The DoC was attributed to the bottom/top ratios of Vickers microhardness numbers. For polymerization shrinkage, each specimen was firstly scanned using micro-computed tomography (µCT) then cured for 20 s, then for 10 s, and then for 10 s, and they were rescanned between each curing time. Data were processed using the Mimics software. For marginal leakage, standardized 5 mm cavities were prepared in 90 molars. After etching and bonding, materials were packed according to groups: FB-bulk, FB-incremental, and FS-incremental, which were cured for 20, 30, and 40 s, respectively. After thermo-cycling, teeth were stored in 1% methylene blue dye for 24 h and then sectioned and observed for dye penetration. The results showed insignificant differences in the shrinkage and leakage between the different packing techniques and curing times of both materials. In conclusion, the introduction of a novel matrix into resin composite composition enabled bulk-filling in one layer up to 5 mm deep while keeping a tolerable polymerization shrinkage.

Surgery for Active Infective Endocarditis of the Aortic Valve With Infection Extending Beyond the Leaflets.

BACKGROUND: The optimal aortic substitute in extensive aortic valve active infective endocarditis (AIE) continues to be debated. To determine the surgical approach in aortic valve AIE with infection extension beyond the leaflets, we evaluated the outcome of reconstructive surgery with various valve substitutes in those patients. METHODS: During 2000-2013, 168 patients had surgery for extensive aortic valve AIE. Patients were categorised based on aortic valve substitute: Group A: Stented aortic valve replacement (AVR), Group B: Stented AVR with patch support, Group C: Stentless valve, Group D: Aortic allograft, and Group E: Composite valve graft. Outcome parameters were mortality, postoperative cardiogenic or septic shock, stroke, or reinfection. RESULTS: Stented valves with patch support were more frequently utilised in cases of native valve endocarditis (p<0.001). Postoperative complications were comparable among groups. Concomitant preoperative extension of infection in the mitral valve predicted reinfection (OR 3.6; confidence interval 1.46-8.66; p=0.005). Survival was not affected by operative group (log rank=0.6). Univariable preoperative predictors of mortality were: septic shock (hazard ratio 8.3; 95% confidence interval 3.6-19.2; p<0.001), ejection fraction (hazard ratio 0.96; 95% confidence interval 0.93-0.99; p=0.006), preoperative cardiogenic shock (hazard ratio 1.9; 95%CI 1.1-3.6, p=0.02) and concomitant mitral valve surgery (hazard ratio 1.8; 95% confidence interval 1.2-2.5; p=0.002). CONCLUSIONS: Surgical treatment of extensive aortic valve infective endocarditis remains a challenge. Outcomes were not affected by the surgical complexity of aortic reconstruction procedure or valve substitute. Surgical approach should be tailored to individual patient's characteristics.

Giardia intestinalis in patients with nonulcer dyspepsia.

BACKGROUND AND STUDY AIMS: Giardiasis may present with dyspeptic symptoms that may mimic other gastrointestinal and/or biliary disorders. The objective of this study was to determine the prevalence of giardiasis in stool and duodenal aspirate of patients with NUD, assess symptomatic benefit of therapy, and compare the diagnostic tools for giardiasis utilizing stool and duodenal aspirates microscopic evaluation versus ELISA testing. PATIENTS AND METHODS: 109 Patients with endoscopic diagnosis of NUD out of 278 consecutive patients with dyspepsia were included. The severity of dyspepsia and the quality of life were assessed utilizing Rome II criteria and SF-36 for Quality of Life and concomitant stool and/or duodenal aspirate samples were submitted for ELISA antigen test for Giardia intestinalis. Those who tested positive for giardiasis (Group 1) were assigned to receive Tinidazole 2.0g. single dose plus omeprazole for 4weeks and the remaining patients (Group 2) omeprazole alone for 4weeks. One month after therapy, both groups were reassessed and Stool ELISA antigen test for G. intestinalis for Group 1, was performed. RESULTS: ELISA testing of stool (19%) and duodenal aspirates (19%) had significantly better results than microscopic ones in stool (11%) or duodenal aspirates (7%). The two groups were well matched with respect to age, sex, initial results on the Glasgow Dyspepsia Severity Score, prevalence of previously prescribed antisecretory-drug therapy, prevalence of smoking, predominant symptom at presentation, and quality of life. The outcome of patients at 1month, on an intention-to-treat basis, showed that the symptoms were resolved (defined as a score of 0 or 1) in 17 of 21 patients (81%) in Group 1 as compared with 31 of 88 patients (35%) in Group 2 P<0.001. The scores in both groups were lower than those at base line and there was a highly statistically significant difference between both groups. CONCLUSION: G. intestinalis as a cause of dyspepsia should be considered in patients with negative endoscopy and in those who remain symptomatic in spite of adequate treatment for known upper G.I. disorders. NUD associated with the presence of Giardia, had better symptomatic benefit (81%) with specific treatment than controls (35%). ELISA testing of stool (19%) and duodenal aspirates (19%) had significantly better results than microscopic ones in stool (11%) or duodenal aspirates (7%).