Comparing fracture resistance on bovine incisors restored by tooth fragment reattachment versus direct composite restoration techniques.

BACKGROUND/AIM: Anterior teeth are prone to traumatic dental injuries (TDIs). Although a number of techniques ranging from original tooth fragment reattachment (TFR) to direct composite restoration (DCR) can be used to restore uncomplicated crown fractures, there is no consensus on which method is best. The purpose of this study was to investigate the fracture resistance of bovine incisors restored by two different techniques (TFR and DCR) in three different fracture models. MATERIALS AND METHODS: Sixty extracted bovine lower incisors were randomly divided into three groups (n = 20). Angle, oblique, or transverse sections of all the teeth in a group were prepared by using a disk. The cut surfaces were scanned, and the cross-sectional areas (CSA) of the enamel and dentin were measured. Half the teeth in each group were restored by DCR (n = 10) and the other half by TFR (n = 10). The forces required to fracture the restored teeth were then measured using a Universal testing machine, and the fracture modes were analyzed (cohesive, adhesive, or mixed). RESULTS: No statistically significant differences between the TFR and DCR restorations were detected for total and enamel CSAs in any of the restoration shapes (p > .067). The fracture forces required to break DCR angle and transverse restorations were significantly greater than for the corresponding shapes restored with TFR (p < .033). However, the difference in the forces needed to fracture oblique section restorations by DCR or TFR was not statistically significant (p = .239), despite a similar trend (143.4 ± 51 N and 120.9 ± 25 N, respectively). CONCLUSION: This study revealed that a greater force is required to fracture teeth restored by the DCR than by the TFR technique, especially for a transverse section. This demonstrates that restoring a fractured tooth provides a superior outcome compared to reattaching the fractured fragment.

Impact of physical and mental training on dental students' fine motor skills.

BACKGROUND: Mental training can be beneficial when learning new motor skills. OBJECTIVE: To evaluate whether a combination of physical and mental training can replace physical training. METHODS: Sixty dental students were randomly divided into six groups, which were assigned different regimens of physical and mental training: A. 75% mental 25% physical; B. 50% mental 50% physical; C. 75% physical 25% mental; D. 100% mental; E. 100% physical; F. control, no practice. The physical training comprised eight different tasks performed on the Purdue Pegboard: four tasks with direct vision (PD) and four tasks with indirect vision (PIND). The mental training involved listening to a recording explaining the actions to be performed. The tests were performed twice: T0, before training; and T1, at 24 h after training. The non-parametric Mann-Whitney test was used to detect differences between the groups. Changes between T0 and T1 within a group were analysed by Wilcoxon signed-rank test. RESULTS: There were no significant differences between the groups at T0. At T1, members of Groups A, B, C, and E had improved at five to eight tasks, while Groups D and F had improved at two tasks. Notably, Group D improved in the assembly tasks. Ranking the extent of improvement at T1, indicated that For PD Groups B, E > F, D while for PIND B, C, E > A, F and E > D. CONCLUSION: Substituting some physical training by mental training can provide similar improvements in fine motor skills, although the optimal combination remains to be determined. Mental training may be more effective for cognitive tasks.

Effect of Different Etching Times on Pit-and-Fissure Sealant Micro-Shear Bond Strength to the Enamel of Primary Teeth.

Successful clinical use of pit-and-fissure sealants relies on the sufficient etching of the enamel, field isolation and sealant retention. The etching time changes the physical and mechanical surface properties of the etched tooth tissues; therefore, it impacts both etching depth and the bond strength of sealants to the enamel. We examined if reducing the recommended 15 s etching time of primary teeth enamel affects the micro-shear bond strength (µSBS) of pit-and-fissure sealants. The cusps of forty non-carious, extracted human primary molars were separately etched for 8, 15 or 30 s. Then, a pit-and-fissure sealant was placed and light-cured. The µSBS values were evaluated and compared among the three groups. The mean µSBS values ± standard deviations were 34.68 ± 16.93, 34.19 ± 17.35 and 36.56 ± 16.57 MPa in the cusps etched for 8, 15 and 30 s, respectively. No statistically significant differences in µSBS were observed among the three test groups. In this study, we showed for the first time that the recommended etching time of primary teeth enamel may be reduced from 15 to 8 s without compromising the µSBS of the sealant. Further evaluations in a clinical setting are warranted.

Ulnar Superficialis Slip Resection Versus Radial Superficialis Slip Resection: A Biomechanical Pilot Study.

BACKGROUND: There are numerous clinical scenarios during which the surgeon contemplates whether the radial or ulnar slip of the flexor digitorum superficialis (FDS) should be sacrificed. To date no study has assessed the point of failure of each one of the FDS slips in each digit, aiding the avid surgeon in deciding which slip to sacrifice. METHODS: A total of 41 digits were assessed, each digit was dissected, and a specimen containing the denuded bone of the middle phalanx with the attachments of the ulnar and radial FDS slips was obtained. An Instron 4502 device was utilized to biomechanically assess the point of failure of each slip of each digit. RESULTS: There was no statistical difference between ulnar and radial slip point of failure when compared across all digits and subjects. There was no statistical difference between male and female subject's specimens. The point of failure was higher in the ulnar slips of the second and third digits, whereas the point of failure was higher in the radial slips of the fourth and fifth digits. CONCLUSIONS: Sacrifice of a FDS slip may cause loss of grip strength. In several clinical scenarios one may be faced with the dilemma which FDS slip to sacrifice. Our findings show this is not an arbitrary choice. Hand surgeons should keep our findings in mind when deciding which slip to sacrifice, in effort to preserve function and strength in the injured hand.

Assessment of the modified O'Connor Tweezer Dexterity and Purdue Pegboard test for use among dental students.

OBJECTIVES: The current study aimed to assess criteria validity and test-retest reliability of the modified O'Connor Tweezer Dexterity (O'Connor) and the Purdue Pegboard test (PPT) for use among dental students. Occupational therapists were asked to assess dentist-related skills due to the high percentage of students who failed the dental school exams that year. The O'Connor and the PPT are suitable for these purposes, they aim to evaluate fine motor skills requirements. The original tests were modified for use under indirect visualization conditions (through a mirror) to mimic the typical dentists' work environment. MATERIALS AND METHODS: A total of 110 dentists were included in the present study (50 dentists for the O'Connor test and 60 for the PPT). Both tests were conducted twice. Initially, the original version of the tests was followed by the modified versions (through a mirror). For the test-retest reliability assessment, 21 participants (10 participants from the O'Connor group and 11 participants from the PPT group) repeated the evaluation within a 1-week interval using the same settings (original followed by modified versions). RESULTS: Both versions of the O'Connor tests were significantly correlated (r = 0.54, p < 0.01), as were the two PPT versions (r = 0.640, p < 0.01). Significantly test-retest reliability was found for both tests. The interclass correlation ranged between 0.883 and 0.997, p < 0.000. CONCLUSION: The results confirmed our hypothesis, demonstrating a criteria validity and test-retest reliability assessment of the modified O'Connor and the modified PPT for assessing dentists.

Influence of Practitioner-Related Placement Variables on the Compressive Properties of Bulk-Fill Composite Resins-An In Vitro Clinical Simulation Study.

Aims: To determine if restoration location and/or execution behavior force parameters have an influence on the mechanical properties of bulk-fill composite dental restorations. Methods: Pressure transducers were placed within each quadrant of dental mannequin jaws. Cylindrical molds were placed above the transducers and filled with two bulk-fill composite materials, Filtek and Tetric, by four experienced dentists. Each dentist prepared five specimens per quadrant and material. The total placement time, mean force, number of peak forces (above 25 N), and mean peak(s) force during placement were measured. Then, the stiffness and maximal compressive strength of the specimens were determined while loading the specimens up to failure using a universal loading machine. Results: Placement time was affected by jaw (p < 0.004) and side (p < 0.029), with the shortest time demonstrated for the left side of the mandible. Force exerted during restoration placement was not normally distributed without differences in location (jaw) or material. A higher application force was found on the right side (p < 0.01). The number of peak forces was affected by side (p < 0.03), with less peaks on the left side. No significant differences were found in compressive strength when correlated to restoration location, participant, or material (p = 0.431). The stiffness values of Filtek (3729 ± 228 N/mm) were found to be 15% higher than Tetric (3248 ± 227 N/mm) (p < 0.005). No correlations were found between the compressive strength or stiffness and the amount of force applied during placement. Conclusions: The individual restoration material placement parameters did influence practitioner performance; however, these differences did not affect the mechanical properties of the final restoration.

Collagenase Administration into Periodontal Ligament Reduces the Forces Required for Tooth Extraction in an Ex situ Porcine Jaw Model.

Minimally invasive exodontia is among the long-sought-for development aims of safe dental medicine. In this paper, we aim, for the first time, to examine whether the enzymatic disruption of the periodontal ligament fibers reduces the force required for tooth extraction. To this end, recombinantly expressed clostridial collagenase G variant purified from Escherichia coli was injected into the periodontal ligament of mesial and distal roots of the first and second split porcine mandibular premolars. The vehicle solution was injected into the corresponding roots on the contralateral side. Following sixteen hours, the treated mandibles were mounted on a loading machine to measure the extraction force. In addition, the effect of the enzyme on the viability of different cell types was evaluated. An average reduction of 20% in the applied force (albeit with a large variability of 50 to 370 newton) was observed for the enzymatically treated roots, reaching up to 50% reduction in some cases. Importantly, the enzyme showed only a minor and transient effect on cellular viability, without any signs of toxicity. Using an innovative model enabling the analytical measurement of extraction forces, we show, for the first time, that the enzymatic disruption of periodontal ligament fibers substantially reduces the force required for tooth extraction. This novel technique brings us closer to atraumatic exodontia, potentially reducing intra- and post-operative complications and facilitating subsequent implant placement. The development of novel enzymes with enhanced activity may further simplify the tooth extraction process and present additional clinical relevance for the broad range of implications in the oral cavity.

Effects of Aging Torque Controllers on Screw Tightening Force and Bacterial Micro-Leakage on the Implant-Abutment Complex.

AIM: We assess the accuracy of torque controllers after several aging processes and the bacterial leakage on implant-abutment complexes (IAC). METHODS: A total of 12 spring-type and 12 friction-type torque controllers and 48 IAC (24 conical and 24 hexagonal connections) were evaluated. Chemical, mechanical, temperature, and pressure-aging methods were applied individually to replicate clinical use. Torque controller accuracy was analyzed before and after aging using a calibrated gauge. To assess bacterial leakage, the IAC were suspended in a bacterial medium for 24 h. Direct Contact Test (DCT) and Polymerase Chain Reaction Test (RT-PCR) analyzed the infiltration of F. nucleatum and P. gingivalis into the IAC micro-gap. RESULTS: A significant decrease in torque after 10 days of aging was found. The spring-type torque controller was affected the most, regardless of the aging method (P < 0.05). PCR results indicated that all groups exhibited significantly more bacterial leakage, regardless of the method used (P < 0.05). The conical IAC demonstrated more bacterial leakage of P. gingivalis compared with the hexagonal IAC (P = 0.07). DCT found bacterial growth in the IAC only before aging and was not identified after aging. CONCLUSION: Aging affects torque accuracy. A reduction in force was noticed after 10 days. The conical IAC exhibits more bacterial leakage, although this was not statistically significant.

The Balance between Orthodontic Force and Radiation in the Jawbone: Microstructural, Histological, and Molecular Study in a Rat Model.

Irradiation of facial bones is associated with a lifelong risk of osteonecrosis. In a rat model, maxillae were exposed to a single 5 Gy dose of external beam radiation and orthodontic force was applied for 2 weeks on the first maxillary molar; control rats were treated identically without radiation. Tooth movement in irradiated jaws was 30% less than in controls, representing radiation-related damage. Micro-CT, histological, and molecular outcomes of orthodontic tooth movement were studied. Microstructurally, bone parameters (trabecular thickness, bone volume fraction, bone mineral density) were significantly affected by orthodontic force but not by radiation. Histological parameters were influenced only by orthodontic force, especially by an increase in osteoclasts. A molecular study revealed a differential distribution of cells expressing pre-osteoclast markers (RANK+-majority, CD11b+, CD14+-minority), with changes being influenced by orthodontic force (increased CD11b+ and CD14+ cells) and also by radiation (decreased RANK+ cells). The activation status of osteoclasts (TRAP staining) showed an orthodontic-force-related increase, which probably could not fully compensate for the radiation-associated impairment. The overall balance showed that orthodontic force had elicited a substantial microstructural, histological, and functional normalization process in irradiated maxillae but a radiation-induced impact was still conspicuous. Additional studies are needed to validate these findings.

Effect of Different Surface Treatments of Lithium Disilicate on the Adhesive Properties of Resin Cements.

The aim of the current study was to evaluate the influence of hydrofluoric (HF) acid concentration and conditioning time on the shear bond strength (SBS) of dual cure resin cement to pressed lithium disilicate ceramic compared to treatment with an Etch and Prime self-etching glass-ceramic primer (EP). A total of 100 samples of pressed lithium disilicate (IPS e.max Press, Ivoclar Vivadent) were randomly divided into five groups (n = 20) according to surface treatment: two different concentrations of HF (5% or 9%), for different durations (20 or 90 s), or treatment with EP. Adhesion of light-cured resin cement to the treated surface was tested by the SBS test. The substrate surfaces of the specimen after failures were examined by SEM. Data were analyzed using Weibull distribution. The highest cumulative failure probability of 63.2% of the shear bond strength (η parameter) values was in the 9% HF -90 s group (17.71 MPa), while the lowest values were observed in the 5% HF -20 s group (7.94 MPa). SBS values were not affected significantly by the conditioning time (20 s or 90 s). However, compared to treatment with 5% HF, surface treatment with 9% HF showed a significantly higher η (MPa) as well as ß (reliability parameter). Moreover, while compared to 9% HF for 20 s, EP treatment did not differ significantly in SBS values. Examination of the failure mode revealed a mixed mode of failure in all the groups. Within the limits of this study, it is possible to assume that IPS e.max Press surface treatment with 9% HF acid for only 20 s will provide a better bonding strength with resin cement than using 5% HF acid.

Does Augmented Visual Feedback from Novel, Multicolored, Three-Dimensional-Printed Teeth Affect Dental Students' Acquisition of Manual Skills?

Although three-dimensional (3D) printing technology is increasingly used in dental education, its application regarding the provision of online visual augmented feedback has not been tested. Thus, this study aimed to: (1) develop two generations of multicolored 3D-printed teeth that provide visual augmented feedback for students conducting the cavity preparation process, (2) assess students' clinical performance after training on the 3D models, and (3) acquire student feedback. For the first-generation model, augmented feedback was obtained from five 3D-printed teeth models for five cavity preparation procedures. Each model comprised three layers printed in green, yellow, and red indicating whether preparation was acceptable, limited, or unacceptable, respectively. The study used a crossover design in which the experimental group trained on five multicolored models and 10 standard plastic teeth, and the control group trained on 15 standard plastic teeth. Students gave positive feedback of the methodology but complained about the printed material's hardness. Therefore, a second-generation model was developed: the model's occlusal plane was replaced with a harder printed acrylic material, and the experiment was repeated. During training, instructors provided external terminal feedback only for performance on standard plastic teeth. Manual grades for cavity preparations on standard plastic teeth were compared. No significant differences were found between the control and experimental groups in both generations' models. However, less instructor time was needed, and similar clinical results were obtained after training with both generations. Thus, multicolored 3D-printed teeth models promote self-learning during the process of acquiring manual skills and reduce student dependency on instructors.

Tensile Properties of Three Selected Collagen Membranes.

BACKGROUND: Biological barriers are commonly used to treat alveolar bone defects and guide tissue regeneration. Understanding the biological and mechanical properties of the available membranes is crucial for selecting the one that is optimal for enhancing clinical outcomes. PURPOSE: To evaluate the mechanical behavior of three different collagen membranes to increasing tensile force in dry and wet conditions. MATERIALS AND METHODS: Three commercially collagen membranes were selected for analysis: Bio-Gide® (Geistlich Biomaterials, Baden-Baden, Germany), Remaix™ (RX; Matricel GmbH, Herzogenrath, Germany), and Ossix Plus® (Datum Dental Biotech, Lod, Israel). Increasing tensile forces were applied on 10 dry and wet membranes of standard size via a loading machine. Force and extension values were acquired up to maximum load before failure, and maximum stress, maximum extension, and amount of energy needed for membrane tearing were analyzed. Membranes' densities were also calculated. RESULTS: The Remaix membrane exhibited the highest values of maximum load tensile strength, maximum extension, and maximum energy required for membrane tearing, followed by Bio-Gide. Ossix Plus had the lowest scores in all these parameters. Dry membranes had the highest scores for all parameters except extension. Membrane density was directly and significantly correlated with all tested parameters. CONCLUSIONS: The study was undertaken to provide clinicians with data upon which to base the selection of collagen membranes in order to achieve optimal clinical results. It emerged that the mechanical properties of dry and wet collagen membranes were significantly different from one another. Among the 3 tested membranes, Remaix exhibited higher performance results in all the mechanical tests. Collagen membrane density seems to have a significant influence upon mechanical resistance. These findings may also guide manufacturers in improving the quality of their product.

Enhanced Nanoassembly-Incorporated Antibacterial Composite Materials.

The rapid advancement of peptide- and amino-acid-based nanotechnology offers new approaches for the development of biomedical materials. The utilization of fluorenylmethyloxycarbonyl (Fmoc)-decorated self-assembling building blocks for antibacterial and anti-inflammatory purposes represents promising advancements in this field. Here, we present the antibacterial capabilities of the nanoassemblies formed by Fmoc-pentafluoro-l-phenylalanine-OH, their substantial effect on bacterial morphology, as well as new methods developed for the functional incorporation of these nanoassemblies within resin-based composites. These amalgamated materials inhibit and hinder bacterial growth and viability and are not cytotoxic toward mammalian cell lines. Importantly, due to the low dosage required to confer antibacterial activity, the integration of the nanoassemblies does not affect their mechanical and optical properties. This approach expands on the growing number of accounts on the intrinsic antibacterial capabilities of self-assembling building blocks and serves as a basis for further design and development of enhanced composite materials for biomedical applications.

An interventional study for improving the manual dexterity of dentistry students.

OBJECTIVES: Traditionally, the acquisition of manual skills in most dental schools worldwide is based on exercises on plastic teeth placed in a "phantom head simulator". No manual trainings are done at home. Studies revealed that preliminary training of one motoric task leads to significant improvement in performance of the required motoric task that has similar components. Performing tasks indirectly via a dental mirror are complicated for the young dental students. We hypothesized that instructed training of basic skills required in dentistry at home on a tool simulating the phantom laboratory will improve the capabilities of the students and will be reflected by their clinical grades. METHODS: We developed a portable tool PhantHome which is composed of jaws, gingival tissue, rubber cover and a compatible stand. Specific teeth produced by a 3D printer with drills in different directions were placed in both jaws. Students were requested to insert pins by using tweezers and dental mirror according to instructions initiating with easy tasks and continue to ones that are more complicated. 106 first clinical year dental students participated in the study; 65 trained only in the traditional phantom lab (control). 41 trained at home by the PhantHome tool two weeks before and 2 months during the initial stage of phantom lab. The students grades routinely provided in the phantom laboratory at different stages were compared. RESULTS: Students who trained with the portable tool performed better than the control group in the first direct and second indirect preparations (p<0.05). These exams were taken when the PhantHome was available to the students. Then, the tool was returned and the phantom course continued regularly. We believe that this is why no differences between the grades of the groups were observed further on. CONCLUSIONS: Training by the PhantHome improves motor skills and consequently the clinical performances.

A Self-Healing, All-Organic, Conducting, Composite Peptide Hydrogel as Pressure Sensor and Electrogenic Cell Soft Substrate.

Conducting polymer hydrogels (CPHs) emerge as excellent functional materials, as they harness the advantages of conducting polymers with the mechanical properties and continuous 3D nanostructures of hydrogels. This bicomponent organization results in soft, all-organic, conducting micro-/nanostructures with multifarious material applications. However, the application of CPHs as functional materials for biomedical applications is currently limited due to the necessity to combine the features of biocompatibility, self-healing, and fine-tuning of the mechanical properties. To overcome this issue, we choose to combine a protected dipeptide as the supramolecular gelator, owing to its intrinsic biocompatibility and excellent gelation ability, with the conductive polymer polyaniline (PAni), which was polymerized in situ. Thus, a two-component, all-organic, conducting hydrogel was formed. Spectroscopic evidence reveals the formation of the emeraldine salt form of PAni by intrinsic doping. The composite hydrogel is mechanically rigid with a very high storage modulus ( G') value of ∼2 MPa, and the rigidity was tuned by changing the peptide concentration. The hydrogel exhibits ohmic conductivity, pressure sensitivity, and, importantly, self-healing features. By virtue of its self-healing property, the polymeric nonmetallic hydrogel can reinstate its intrinsic conductivity when two of its macroscopically separated blocks are rejoined. High cell viability of cardiomyocytes grown on the composite hydrogel demonstrates its noncytotoxicity. These combined attributes of the hydrogel allowed its utilization for dynamic range pressure sensing and as a conductive interface for electrogenic cardiac cells. The composite hydrogel supports cardiomyocyte organization into a spontaneously contracting system. The composite hydrogel thus has considerable potential for various applications.

Consolidation of complex motor skill learning: evidence for a delayed offline process.

Following initial acquisition, studies across domains have shown that memories stabilize through consolidation processes, requiring a post-acquisition temporal interval to allow their occurrence. In procedural skill memories, consolidation not only stabilizes the memory, but also simultaneously enhances it by accumulating additional gains in performance. In addition, explicit skill tasks were previously shown to consolidate through sleep, whereas implicit tasks were consolidated following a time interval which did not include a period of sleep. Although previous research has been instrumental in utilizing simple motor tasks designed to model skill learning, whether and how skill consolidation processes operate in complex real-life environments remains to be determined. Here, we tested consolidation in a complex motor skill, used to train execution of fine-motor movements. Since the complex task was explicit, we hypothesized that consolidation will be evident immediately following sleep, as in simple explicit motor skills. However, results show that even though participants were aware of the goal of the complex skill task, consolidation was evident only 24 hr following skill acquisition, and not following a shorter 12 hr interval, even when the latter included sleep. An additional experiment verified that without a temporal interval longer than 12hr, the same skill training does not undergo complete consolidation. These results suggest that task complexity is a crucial characteristic determining the proper terms allowing full consolidation. Due to the enhanced ecological validity of this study, revealing the differences between complex and simple motor skills could enable the facilitation of advanced rehabilitation methods following neurological injuries.

Circumferential root strains generated during lateral compaction with stainless steel vs. nickel-titanium finger spreaders.

The circumferential strains created in the radicular dentin by nickel-titanium (NiTi) and stainless steel (SS) finger spreaders (FSs) during a simulated clinical procedure of lateral compaction were compared after minimal (size 50) and extensive (size 100) canal preparations. Nineteen maxillary central incisors underwent minimal preparation, while 10 underwent an extra phase of extensive preparation. Four miniature strain gauges were bonded circumferentially in the apical third of the root (buccal, lingual, mesial, and distal). Lateral compaction was performed using either NiTi-FSs or SS-FSs. Force and strains were continuously recorded. The maximal strains (with and without normalization according to force) were recorded. The SS-FSs generated higher maximal strains normalized according to force compared with the NiTi-FSs. The maximal normalized strains were higher by 37%-43% for the mesial and distal aspects and by 6%-14% for the buccal and lingual aspects after the minimal preparation and by 24%-28% for the mesial and distal aspects and by 19%-20% for the buccal and lingual aspects after extensive preparation. The maximal normalized strains increased by 30%-70% from minimal to extensive preparations, with two teeth exhibiting vertical root fracture while compaction with SS-FS. The NiTi-FSs induce less strain in root dentin than the SS-FSs and thus may contribute less to the risk of vertical root fracture.

Predicting the clinical performance of dental students with a manual dexterity test.

Dentists must be skilled when using dental mirrors. Working with mirrors requires spatial perception, bimanual coordination, perceptual learning and fine motor skills. Many studies have attempted to determine the predictors of manual skills among pre-clinical students, but consensus has yet to be reached. We hypothesized that valid and reliable occupational therapy test performance regarding indirect vision would differ between dental students and junior dentists and would explain the variance in manual skill performance in pre-clinical courses. To test this hypothesis, we applied the Purdue Pegboard test and O'Connor Tweezer Dexterity test under different conditions of direct and indirect vision. We administered these tests to students in phantom-head academic courses in 2015 and 2016 and to junior dentists. Students performed the tests at three time points: before phantom training (T0), at the end of the training (T1) and in the middle of the following year of study (T2). Dentists performed the same tests twice at 1st and 2nd trials one week apart. The results showed that indirect tasks were significantly more difficult to perform for both groups. These dexterity tests were sensitive enough to detect students' improvement after phantom training. The dentists' performances were significantly better than those of students at T0, specifically with regard to the use of tweezers under direct and indirect vision (the O'Connor test). A regression analysis showed that students' manual grades obtained at the beginning of the phantom course, their performance on the Purdue test using both hands, and their performance on the O'Connor test under indirect vision predicted phantom course success in 80% of cases. The O'Connor test under indirect vision is the most informative means of monitoring and predicting the manual skills required in the pre-clinical year of dentistry studies.

Effects of a Program for Improving Biomechanical Characteristics During Walking and Running in Children Who Are Obese.

PURPOSE: To investigate the influence of a weight-reduction program with locomotion-emphasis on improving biomechanical characteristics of children who are obese (OW). METHODS: Ten children who are OW participated in a 6-month multidisciplinary childhood obesity management program (GRP1); another 10 children who are OW participated in the same multidisciplinary childhood obesity management program with additional locomotion-emphasis exercises for improving biomechanical characteristics (GRP2); and 10 control children who are OW with no intervention program. Outcomes were anthropometric measurements and temporal and foot pressure parameters. RESULTS: GRP2 had significantly improved foot pressure in the different walking/running speeds compared with GRP1. In the temporal parameters, pretests by speed by group interactions were significantly improved for GRP2 compared with GRP1. CONCLUSIONS: We found evidence to support beneficial effects of combined dietary and physical activity/locomotion-emphasis exercises on the movement characteristics of children who are OW.

Subacromial corticosteroid injections transiently decrease suture anchor pullout strength: biomechanical studies in rats.

BACKGROUND: Arthroscopic rotator cuff (RC) repair incorporates suture anchors to secure torn RC tendons to the greater tuberosity (GT) bone. RC repair strength depends on the anchor-bone interface and on the quality of the GT. We evaluated the effect of single and multiple corticosteroid injections on the pullout strength of suture anchors. METHODS: Fifty rats were divided into those receiving saline solution injection (control group), a single methylprednisolone acetate (MTA) injection (MTA1 group), or 3 once-weekly MTA injections (MTA3 group). Rats were killed humanely at 1 or 4 weeks after the last injection. A mini-suture anchor was inserted into the humeral head through the GT. Specimens were tested biomechanically. RESULTS: At 1 week after the last injection, the mean maximal pullout strength was significantly reduced in the MTA1 group (63.5%) and MTA3 group (56%) compared with the control group (P < .05 for both). Mean stiffness decreased significantly in both treatment groups compared with controls (P < .05). At 4 weeks after the last injection, there was a significant increase in the mean maximal pullout strength after single and triple MTA injections compared with values recorded at the 1-week time point (P < .05). At 4 weeks, the mean maximal pullout strength after a single MTA injection was 92.8% of the pullout strength measured in the control group. CONCLUSIONS: We showed a significant detrimental effect of corticosteroid exposure on the pullout strength of a suture anchor at 1 week. However, this effect was transient and resolved within a relatively short period. These findings indicate that a waiting period is required between subacromial corticosteroid injection and RC repair surgery that involves the use of suture anchors.