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Background | Frailty | Psychometric properties of the Tilburg Frailty Indicator (TFI) have shown low internal consistency for psychological and social domains, and evidence for its structure validity is controversial. Moreover, research on TFI is frequently limited to community dwellings. | PMC10200782 | |
Aims | Frailty | To evaluate structural validity, reliability, and convergent and divergent validity of the Spanish version of the Tilburg Frailty Indicator (TFI) in both community-dwelling and institutionalized older people. | PMC10200782 | |
Materials and methods | A cross-sectional study was conducted on Spanish older adults ( | PMC10200782 | ||
Results and discussion | KCL-depressive mood | Some items from physical and social domains showed low factor loadings (< 0.40). The three-factor CFA model showed better fit indices after depurating these items. Reliability estimates were good (CRI ≥ 0.70) for physical and psychological domains in the institutionalized sample, while in the community dwellings, only physical domain reliability was adequate. Convergent and divergent validity of physical and psychological domains was good, except for some alternative psychological measures highly correlating with the TFI physical component (KCL-depressive mood and Edmonton mood). However, the social domain showed low correlations with some social indicators. | PMC10200782 | |
Conclusion | The findings of this study clarify some of the controversial validation results of the TFI structure and provide evidence to improve its use in psychometric terms. | PMC10200782 | ||
Clinical trial registration number | NCT03832608 | NCT03832608. | PMC10200782 | |
Keywords | Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. | PMC10200782 | ||
Introduction | Frailty | Studies on frailty are increasing in literature on aging. There is no consensus on its definition, but it is generally recognized as a state of increased vulnerability that is associated with high risk of adverse outcomes, such as falls, disability, and even mortality [Within this construct, the Tilburg Frailty Indicator (TFI) is a multi-domain frailty instrument, developed in 2010 as a screening tool for frailty [Among all validations, only the Spanish [Additionally, research on TFI has been limited to community-dwelling older adults. Thus, further studies involving institutionalized older adults could contribute to test its applicability to other contexts [ | PMC10200782 | |
Materials and methods | PMC10200782 | |||
Population and study design | This cross-sectional study was carried out between 2018 and 2021. A convenience sample of 457 older adults aged ≥ 65 years was included. Community-dwelling older adults were recruited from several community settings ( | PMC10200782 | ||
Measurements | Frailty | Tilburg Frailty Indicator was measured with a 15-item questionnaire, addressing physical (8 questions), psychological (4 questions), and social domains (3 questions). All items were dichotomized and scored with 0 points (absence) or 1 point (presence), and summed to obtain the total score ranging from 0 to 15 [Alternative frailty assessment tools were included: Fried’s Frailty Phenotype [ | PMC10200782 | |
Statistical analysis | SPSS 26 was used to calculate descriptive statistics for the variables under study, and to obtain Cronbach’s alpha coefficients, corrected item-total correlations, and correlations among the dimensions in the TFI and external criteria. Additionally, an R function was used for alpha coefficients confidence intervals. Given the nature of the study with voluntary participation and interviewers present, there was a very low percentage of missing data. There was only one missing data point (0.2%), from the institutionalized sample in a single indicator. With such very low level of missingness in the datasets, there is no need to handle the missing data, and therefore list-wise selection was employed across the statistical analyses. The factor structure was tested with CFAs estimated with Weight Least Square Mean and Variance (WLSMV) corrected estimation in Mplus 8.6. WLSMV was selected because the variables are binary and lacked multivariate normality. Several fit indices were used for assessing model fit: Chi-square statistic; Comparative Fit Index (CFI); Root Mean Square Error of Approximation (RMSEA); and Standardized Root Means-square Residuals (SRMR). Criteria for reasonable fit were [Finally, Spearman’s correlations were used to study the convergent and divergent validity of the physical, psychological, and social domains of the TFI with other frailty assessment tools. Based on Cohen’s criteria, a correlation coefficient of 0.10 ≤ 0.30, 0.30 ≤ 0.50, and ≥ 0.50 indicated weak, moderate, and strong correlations, respectively [ | PMC10200782 | ||
Results | Descriptive statistics are presented as means and standard deviations or percentages for the variables in Table Main descriptive characteristics of the sample (Descriptive data for the TFI items | PMC10200782 | ||
Structural validity | Frailty | Two CFA models were estimated in both community-dwelling and institutionalized older adults. These models were: a one-factor solution (frailty); and a three-factor solution with the three frailty domains: physical (items 1–8), psychological (items 9–12), and social (items 13–15).The one-factor solution had a poor fit: Final confirmatory factor analysis (CFA) standardized parameter estimates for the Tilburg Frailty Indicator in community-dwelling and institutionalized older adults | PMC10200782 | |
Reliability estimates | Internal consistencies for the community-dwelling older adults were: alpha for the physical domain = 0.629, 95% CI [0.560, 0.689] with CRI = 0.803; alpha for the psychological domain = 0.410, 95% CI [0.297, 0.508] and CRI = 0.662; and for the social domain, alpha = 0.315, 95% CI [0.174, 0.435] and CRI = 0.518. The estimates for the institutionalized older adults were: for the physical domain, alpha = 0.764, 95% CI [0.696, 0.820] and CRI = 0.894; the psychological domain had an alpha = 0.608, 95% and CI [0.487, 0.705] and CRI = 0.769; and finally, the alpha for the social domain was 0.378, 95% CI [0.126, 0.557] and CRI = 0.682. | PMC10200782 | ||
Discussion | weight loss, KCL-depressive mood | Our findings aim to offer further insights on the TFI structure and provide evidence to improve its use in psychometric terms.The need to confirm the structure of the scale is clear, given the available evidence gaps in some relevant measurement properties [Similarly, in the institutionalized sample, the three-factor solution fit better than the one-factor, but only fit well after depurating the poorly behaving items (2, 5, and 13). To our knowledge, no studies have previously analyzed the adequacy of the TFI in institutionalized older adults.The need to review the TFI model and refine some indicators of the scale has also been suggested by other studies, when analyzing the poor correlations with other items or other similar measures. Among the indicators to be checked, the following have been pointed out: unexplained weight loss (2) [A recent systematic review of the psychometric properties of the TFI [Reliability estimates were not equal in both samples, showing better values for the institutionalized older adults. The CRI values for the physical and psychological domains were good (CRI > 0.70) in the institutionalized sample, while only the physical domain was satisfactory in the community-dwelling older adults. In both cases, social domain reliability estimates were not acceptable. These differences between the two groups may be due to a higher mean age, greater variability in the variables or a larger sample of frail people in the institutionalized group. These findings suggest that the TFI seems to be a good assessment tool to detect physical frailty, as indicated by other authors [In addition, although some authors refer to the adequate reliability of the scale considering the estimates of the total TFI [Convergent and divergent validity for the physical and psychological domains are acceptable given the obtained results, except for some psychological measures whose constructs are similar to the TFI physical domain (KCL-depressive mood and Edmonton mood). These results are in line with several studies in which the construct of alternative psychological measures was related or similar to the TFI physical component [As mentioned before, previous validations have involved community-dwelling older adults. Thus, the use of the TFI in geriatrics still needs to be tested in different settings to explore its potential applications [ | PMC10200782 | |
Author contributions | Conceptualization: MB-B, TS-M, JMT, and NC-S. Methodology: MB-B, TS-M, MAC I, MAT-C, AA-G, and NC-S. Formal analysis and investigation: JMT, MB-B, and NC-S. Writing—original draft preparation: MB-B, TS-M, JMT, and NC-S. Writing—review and editing: MB-B, TS-M, JMT, MACI, MAT-C, AA-G, and NC-S. Funding acquisition: MACI and JMT. Supervision: MB-B, TS-M, and NC-S. | PMC10200782 | ||
Funding | Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the Generalitat Valenciana, Valencia, Spain [GV/2019/131, 2019] and by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe” [project PID2021-124418OB-I00]. | PMC10200782 | ||
Data availability | The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. | PMC10200782 | ||
Declarations | PMC10200782 | |||
Conflict of interest | The authors have no relevant financial or non-financial interests to disclose. | PMC10200782 | ||
Statement of human and animal rights | Approval was obtained from the Ethics Committee for Human Research of the University of Valencia (No. H1542733812827). The procedures performed in this study were in accordance with the ethical standards of the institutional research ethics committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. | PMC10200782 | ||
Informed consent | Informed consent was obtained from all individual participants included in the study. | PMC10200782 | ||
References | PMC10200782 | |||
1. Introduction | ’ explosive strength and jump/leap, ’ explosive | CONTRACTION | Background: Explosive strength is essential for rhythmic gymnasts’ performance. It has been suggested that core stability (CS) and plyometric training can enhance athletes’ explosive strength. Nevertheless, there is some uncertainty about the effects of integrated core and plyometric training (CPT) programs on rhythmic gymnastics (RG) performances. Purpose: to evaluate the effects of an integrated functional CPT program on young rhythmic gymnasts’ explosive strength and jump/leap performance. Method: We recruited 44 young (age = 10.5 ± 1.8 years old; peak height velocity, PHV = 12.2 ± 0.6 years old) female rhythmic gymnasts and randomly allocated them into a control group (CG) and an experimental group (EG). Pre and post-intervention, the explosive strength of both groups was assessed using countermovement jump (CMJ) and single-leg CMJ (SLCMJ) tests, conducted using a force platform, and expert RG judges evaluated their performance of RG-specific jumps. Before the post-test, the EG (Strength is among the main physical capacities that have been found to contribute to performance in rhythmic gymnastics (RG) [The specific manifestations of strength in RG are strength-endurance and explosive strength [RG judges observe and qualitatively assess jumps/leaps to determine their validity [In RG movements, isometric force plays a critical role in the pre-activation of the muscle before a contraction of the stretch-shortening cycle (SSC) [Plyometric training (PT) improves athletes’ explosive strength and jumping ability [In order to reach the top level of RG performance, it is fundamental to begin intensive training at a very young age, as this is the ideal time to start to learn and perform complex gymnastics skills [Some necessary RG attributes can be developed simply by practicing regular gymnastics routines. However, PT seems likely to facilitate the further progression of athletes who have already reached a certain level of force and speed [CS training protocols improve explosive strength and jump performance in RG and artistic gymnastics [ | PMC9859241 |
2. Materials and Methods | PMC9859241 | |||
2.1. Design | We carried out a randomized parallel clinical trial. The study was conducted according to the CONSORT standards [ | PMC9859241 | ||
2.2. Participants | We used GPOWER v3.1 software (Bonn FRG, University of Bonn, Department of Psychology) to make an a priori calculation of the sample size needed to obtain a Power (1 − ß) > 0.9, effect size = 0.4, and α = 0.05. The total required sample was 36 participants. In the end, we screened 59 participants for eligibility. However, only 45 participants met the inclusion criteria (All the participants gave their consent to participate in the study, and the procedures followed the latest version of the WMA Declaration of Helsinki. The gymnasts recruited must meet the three inclusion criteria: (1) training regularly at least three times a week, (2) having trained in gymnastics for more than a year without long breaks, and (3) having competed in regional federated and school RG competitions (The ethics committee of Ramon Llull University in Barcelona approved this study (CER- FPCEE Blanquerna, 1819007D). Parents or legal guardians of the participants completed the informed consent document prior to the study. | PMC9859241 | ||
2.3. Procedures | MAY | The EG underwent the 8 week combined functional CPT program, featuring three 30 min sessions a week (a total of 24 sessions), from 19 March 2020 until 15 May 2020. The CG followed their regular training regimen over the same number of sessions.All participants were tested 2 weeks before and2 weeks after the 8 week intervention. Prior to the testing session, the order of the participants and the two tests was randomly determined using a true random number generator to control for bias. Jump tests were carried out over 2 weeks, in the pre-test and post-test, by a sport-specialized physiotherapist unaware of each subject’s allocation group. The gymnasts performed a 15 min warm-up of cardiovascular activation and dynamic stretching exercises before the tests. | PMC9859241 | |
2.4. Training Protocol | The present study was registered on clinicaltrials.gov with the ID number NCT04663633. The program involved exercises challenging the gymnasts’ core stability and postural control, and it included SSC explosive strength exercises executed with specific RG elements and postures (Participants in the EG were encouraged to hollow their navels while exhaling during each repetition of the CS exercises. They had to perform each repetition simultaneously with the breathing cycle, and they kept their lumbopelvic area neutral and stable while performing RG specific jumps and balance elements. The functional integrated CPT program contained three blocks. The first block consisted of a specific CS and plyometric skill circuit using cones, hurdles, and unstable surfaces. The second block included plyometric exercises involving RG jumps and balances combined with CS actions. Finally, the third block consisted of CS exercises in prone, supine, and side positions on the floor, combining specific balance poses that place demands on the core, as well as standing-up balances, with a series of jumps. We selected three different leaps (scissors, stag from assemble, and split leap) and three balances (passé, side with help, and arabesque) all of which are very common in novice-to-intermediate RG. These specific exercises are intended to convert the integrated CPT into sport-specific functional training, and they were selected to encompass various lower limb position planes and different techniques. It is advisable to employ exercises with the potential to challenge the core musculature, in all three planes and ranges of movement, to fully develop CS [Every session, participants rated their internal perceived intensity in the rate of perceived exertion session scale (sRPE). The sRPE is a valid method of quantifying the effects of a training session through the assessment of the internal training load that can be applied in a wide variety of exercises [During sessions, the EG and the CG did their general warm-up simultaneously, which consisted of approximately 30 min of general activation and stretching exercises. After that, the EG did the CPT program, while the CG completed their regular conventional RG-specific warm-up, combining traditional flexibility, strength, and abdominal exercises, all aimed at RG body techniques (splits, bridges, leg kicks, body waves, v abs, candlesticks, feet work, etc.) (detailed RG warm-up exercises and training load are shown in The integrated functional CPT protocol was included in the competitive macrocycle (second half of the season) with a frequency of three times per week, as suggested previously [ | PMC9859241 | ||
2.5. Measurements | CMJ and single-leg CMJ (SLCMJ) tests were used to assess the explosive strength of rhythmic gymnasts. RG jumps use either one-leg or two-leg push-off techniques, which justifies the selection of bilateral (CMJ) and unilateral (SLCMJ) jump tests. The two tests were administered in a random order to each of the gymnasts. | PMC9859241 | ||
2.6. Testing Procedures and Instrumentation | PMC9859241 | |||
2.6.1. Counter-Movement Jump (CMJ) Test | The participants performed the CMJ from a standing position in accordance with Bosco’s [ | PMC9859241 | ||
2.6.2. Single Leg Countermovement Jump (SLCMJ) Test | The participants performed SLCMJ from a standing position with one bare foot on the board and the free lower limb bent and not touching the force plate. The gymnasts were instructed to place their hands on their hips and jump as fast and high as possible. The first movement consisted of a single-leg half squat, i.e., knee at ~90° and, then, without a pause, a single-leg jump pushing vertically off the ground. Each participant completed six jumps (three with the right leg and three with the left as support) with 1 min rest periods between them. The jumps with the highest power value for the right and the left lower limbs were used for further analysis (Data for the CMJ and SLCMJ tests were collected using a force plate (Kistler 9260AA, Winterthur, Switzerland) connected to a data acquisition system (Kistler 5695b, Winterthur, Switzerland). We employed the MARS software (Kistler, Winterthur, Switzerland) to acquire and store the raw data (sampling rate 1000 Hz) and to calculate all dependent variables. Calibration of the system was performed according to the MARS software recommendations. The CMJ and SLCMJ variables measured were: jump height of flight (Height), which was the height of the jump calculated from the deformation of the platform’s force sensors, measured in meters; this parameter was calculated from the take-off speed. Vertical take-off velocity (Take-off) was the velocity of the vertical movement at the time of take-off, calculated from flight time, measured in m/s. The average power (AVE P) is measured in watts (W). Moreover, the maximum concentric rate of force development (RFD)—P3 was also calculated. P3 is the software designation for the portion of the force curve used to calculate the RFD. The force platform software (MARS) calculates the RFD from the maximum slope of the force curve from the start of the concentric movement to the force peak.The RFD parameter indicates maximal force development in a unit of time and is an index of explosive strength [ | PMC9859241 | ||
2.6.3. Rhythmic-Gymnastics-Specific Jump Tests | The participants performed three RG jumps—the stag leap, the scissors leap, and the split leap ( | PMC9859241 | ||
2.6.4. PHV Age | Strength is affected by age [ | PMC9859241 | ||
2.7. Statistical Analyses | The descriptive data on the variables were presented as mean ± SD. The dependent variables included Height, Take-off, Average Power, and RFD, as measured in the CMJ and the SLCMJ with right and left leg tests. The other dependent variables were the scores awarded by the expert judges for the performance of scissors, stag jump, and split leap under different conditions.Linear mixed models for repeated measure designs were employed to analyze the changes and differences between groups when all assumptions were met. A normality analysis of the residuals was carried out using the Kolmogorov–Smirnov test for each variable, and no deviations from a normal distribution were found. Homoscedasticity was examined by plotting the residuals-predicted value. This analysis indicated that the residuals were constant for all the predicted values. An alpha level of GAMLj was used to carry out the linear mixed model analyses. This module relies on the R formulation of random effects. Specifically, it was done using the lme4 R package in Jamovi software (Concomitantly, when no significant interaction effect was found, Cohen’s d effect size was calculated on all scores awarded by the expert judges (scissors, stag jump, and split leap), in the pre- and post-tests, to measure small (0.2), moderate (0.5), and large (0.8) effect sizes [ | PMC9859241 | ||
4. Discussion | ’ explosive strength, ankle joints, ’ explosive | This study aimed to analyze the effectiveness of an 8 week RG-based CPT program on the explosive strength of young rhythmic gymnasts. As far as we know, this is the first study to evaluate the effects of a CPT program on the explosive strength of young rhythmic gymnasts. The main findings comprise significant improvements in the EG in CMJ, as well as right and left SLCMJ, post-test results in all the dependent variables (Height, Take-off, AVE P, and RFD). The judges’ scores for the RG-specific jump tests did not indicate significant differences between the EG and the CG in any of the three leaps evaluated (stag, scissors, or split). Indeed, at the time of the post-test, both groups significantly improved their scores on the RG-specific leaps. However, it is worth noting that an examination of the particular kinds of jump shows large effect sizes on the stag and the split leap in the EG, while only a medium improvement in the CG appears in the post-test. Both groups displayed a large effect size in their post-test scissors leap scores. The results of the pre-tests did not show any significant differences between the EG and CG, so the differences obtained in the post-test can be attributed to the functional integrated CPT. These results suggest that adding an integrated functional CPT program to regular RG training can provide young rhythmic gymnasts with greater explosive strength than they would achieve if performing only RG-specific training. To the best of our knowledge, no prior study has evaluated young rhythmic gymnasts’ explosive strength after completing a CPT training program. However, a similar study involving integrated training was found. After 1 month of integrated training using Pilates and water resistance plyometrics, improved results elite rhythmic gymnasts’ jump height and explosive strength were found [Some earlier studies have featured PT programs and evaluated rhythmic gymnasts’ explosive strength. For example, Taktak et al. [Meanwhile, core training might also have helped improve the gymnasts’ explosive strength. Since the core provides greater stability for the movements of the lower extremities, from proximal to distal, improving core function may enhance the legs’ power [The significant improvement of the EG in the post-test in the CMJ and SLCMJ right and left tests on all variables measured (Height, Take-off, AVE P, and RFD) suggest that our functional training helps enhance explosive strength in young rhythmic gymnasts, thus improving physical parameters of the gymnasts’ vertical jump. The jump height variable is related to the length of flight time during the jump, the vertical take-off with the speed and coordination of this phase of the leap, and the power and RFD variables of explosive strength indicators [These results also suggest that the CPT program helped gymnasts improve their performance throughout the three jump phases (take-off, flight, and landing). A prior study of split leap performance in RG highlighted the importance of the take-off and flight phase total time [Regarding the judges’ overall scores, we did not find any significant differences between groups after the CPT program. However, a significant improvement associated with the time factor was found, indicating that both the EG and the CG improved their RG leap scores at the post-test time. A large effect was found for the stag and split leap in the EG compared to a medium effect on the CG. These results show a tendency toward greater improvement in the EG than in the CG after the functional training. A possible explanation for the results, in terms of the judges’ scores, might be that, for young beginning gymnasts, the leap technique is complex, as these athletes may not have fully developed the execution factors involved in scissors, stag, and split leaps. The execution factors include the physical components of explosive strength, leg flexibility, and proper leap movement techniques [As discussed above, it is clear that the angular flexibility of the joints, especially the amplitude of the hips and the extension of the ankle joints (with pointed toes), is an important factor influencing RG leap execution [Our findings suggest a tendency toward improvements in RG jumps in the EG, especially in the stag and the split leap. These two jumps require the widest hip amplitude, indicating that the training program helped the gymnasts improve their legs’ opening capacity and specific explosive force. However, the CPT program was not aimed at improving the technical aspects of RG jumps nor enhancing flexibility, which is why it may not have been reflected as much in the judges’ scores.Our functional CPT is creative and closely tied to the reality and functional needs of RG since it is linked to RG motor patterns. In our study, gymnasts trained using CS exercises that demanded SSC explosive strength, balance, and postural control. The challenges imposed on explosive strength, CS, and balance are close to the RG skills’ demands. This intention is supported by Lederman [This study considered the importance of biological maturity for physical performance by calculating the gymnasts’ PHV age, and no significant differences between the randomly assigned groups were found. In addition, other studies affirm that regular gymnastics training helps to obtain better results in jump height, take-off speed, and maximum vertical speed of the center of mass, all of which are essential for the adequate performance of vertical jumps [There are certain issues and limitations connected to this study’s design. Some researchers have questioned the use of general jumping ability tests to assess athletes in specific sports. For example, a study by Grande et al. [To our knowledge, only one prior study has analyzed the impact of an integrated CPT training program on rhythmic gymnasts [The most important practical application of the present study is that RG functional training, which combines core and plyometric exercises executed with specific RG balance and leap postures, improves young rhythmic gymnasts’ explosive strength. Gymnasts can take advantage of including more specific content in their warm-up, and increasing their performance at the same time, if they try to be explosive in each jump and balanced in each jump reception; furthermore, they should exercise their core while keeping their lumbopelvic area straight and stable and hollowing the navel while exhaling. Considering these considerations, gymnasts will increase their performance and save time, reducing the necessity for extra sessions. | PMC9859241 | |
5. Conclusions | An 8 week RG-based CPT program enhanced explosive strength in young rhythmic gymnasts, specifically in terms of the variables of jump height, vertical take-off velocity, average power, and RFD measured during a CMJ, a right SLCMJ, and left SLCMJ tests using a force plate. The judges’ scores for RG leaps improved in both groups in the post-test, but there was a tendency toward the more remarkable improvement of the stag and the split leap scores in the EG. Hence, adding a functional CPT to regular training might help to improve rhythmic gymnasts’ explosive strength and RG jump performance-related variables. We encourage researchers to design studies with more extended training periods, analyzing the effects of CPT programs on the RG leaps and other RG key performance indicators. | PMC9859241 | ||
Supplementary Materials | Table S1: Training protocol exercises; all exercises were performed with right and left sides. * Mixed CS and plyometric exercises. (a) All planks and lateral hip bridges were executed with passe, side leg, and arabesque positions and were maintained for 2” in each position. (b) All drop jumps and jump-drop jumps were performed with a 30 cm bench. Available online at | PMC9859241 | ||
Author Contributions | Conceptualization, M.S.-T. and C.C.; methodology, J.M., M.S.-T. and C.C.; software, J.M. and E.C.; validation, E.C., A.N., E.P. and A.B.; formal analysis, J.M. and E.C.; investigation, C.C.; data curation, C.C., J.M. and E.C.; writing—original draft preparation, C.C.; writing—review and editing, M.S.-T., J.M. and E.C.; project administration M.S.-T. and J.M.; visualization, J.M. and M.S.-T.; supervision, E.C., A.N., E.P. and A.B. All authors have read and agreed to the published version of the manuscript. | PMC9859241 | ||
Institutional Review Board Statement | MAY | The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board (or Ethics Committee) of CER- FPCEE Blanquerna (protocol code 1819007D, date 20 May 2019). | PMC9859241 | |
Informed Consent Statement | Informed consent was obtained from all subjects involved in the study. | PMC9859241 | ||
Data Availability Statement | All data files are available from the figshare database: | PMC9859241 | ||
Conflicts of Interest | The authors declare no conflict of interest. | PMC9859241 | ||
References | Sample flowchart.(RG-specific jump tests performed [Judges’ technical score results. * Significant differences pre–post (Standardized effect size of differences between pre and post-test RG leap scores.Participants’ Characteristics.No significant differences between groups.Overview of the 8 week integrated functional CPT program.Note. Reprinted with permission from “The Effect of Eight-Week Functional Core Training on Core Stability in Young Rhythmic Gymnasts: A Randomized Clinical Trial” by C. Cabrejas, 2022, Int. J. Environ. Res. Public Health, 19, 3509 p. 5, doi:10.3390/ijerph19063509. Copyright: © 2022 by the authors. Licensee MDPI. DJ = drop jump, JDJ = jump-drop-jump, W = week, Block 1. Circuit = mixed CS, balance, and plyometric exercises. Each week contained three CPT sessions. All exercises were performed with the right and left sides. All planks and lateral hip bridges were executed with passé, side leg, and arabesque positions, and they were maintained for 2 sec in each position. All DJ and JDJ were performed with a 30 cm bench.Fixed effects of the CMJ and SLCMJ variables.CMJ, right SLCMJ, and left SLCMJ descriptive results and Post Hoc comparisons within subjects.HEIGHT = jump height; TAKE OFF = vertical take-off; AVE P = average power; RFD = rate of force development. Fixed effects of the technical scores’ variables. | PMC9859241 | ||
Introduction | GAD, anxiety disorder, Anxiety, anxiety, worry | According to World Health Organization [Generalized anxiety disorder (GAD) is a subtype of anxiety disorder. People with GAD tend to have chronic uncontrollable worry and excessive anxiety for no specific reason that occurs constantly for at least 6 months. The Generalized Anxiety Disorder-7 (GAD-7) was initially developed by Spitzer et al. [The GAD-7 has been validated across different countries and populations and has shown good psychometric properties. However, it is noteworthy that different factorial structures have been documented ranging from the original unidimensional structure, unidimensional structure with residual covariances, two-factor model with cognitive-emotional domain and somatic symptoms domain [ | PMC10174505 | |
Overview of the present study | anxiety disorder | It is noteworthy that past studies have found different factorial structures of the GAD-7 in different cultural contexts. The inconsistency suggests that there could be cultural differences in the concept of generalized anxiety disorder. In other words, there is a possibility that GAD-7 may not capture the idea of generalized anxiety disorder in terms of the local perspective. Moreover, studies have found that some items of the measurements that have been validated in other contexts are not applicable to Malaysian samples [In addition, although the Malay version of the GAD-7 has demonstrated good screening properties among women attending primary care clinics [ | PMC10174505 | |
Methods | PMC10174505 | |||
Participants | University students who were above 18 years old and studying at the randomly selected tertiary education centers in Klang Valley were recruited using convenience sampling. A total of 1272 university students (MAn online questionnaire was created using Google Forms and then distributed via Facebook, Instagram and WhatsApp to the university students in the Klang Valley. Data were collected between 4th to 17th January 2021 during the third wave of the COVID-19 Pandemic in Malaysia. Ethical approval was granted by the Scientific and Ethical Review Committee (Ref: U/SERC/211/2020). All respondents participated in the study voluntarily and gave their consent online (by checking the “I agree” box) prior to answering the online survey. The data of the present study are available at | PMC10174505 | ||
Measurements | anxiety disorder, anxiety | The GAD-7 is a self-report of the severity of generalized anxiety disorder and its symptoms with 7 items. Participants rated each item on a 4-point Likert scale ranging from 0 (Not at all) to 3 (Nearly every day). A total score was calculated by summing up the item scores. The score ranges from 0 to 21 and can be categorized as 0–4 (minimal anxiety), 5–9 (mild anxiety), 10–14 (moderate anxiety), and 15–21 (severe anxiety). | PMC10174505 | |
Analytical approach | The data were randomly and equally divided into exploratory and confirmatory samples. The exploratory sample ( | PMC10174505 | ||
Results | PMC10174505 | |||
Exploratory factor analysis | Parallel analysis with Promax rotation on the exploratory sample suggested a 3-factor solution. Supporting the factorability of the seven items, the Kaiser-Meyer-Olkin (KMO) test value was .911 and the Bartlett’s test was statistically significant, χ | PMC10174505 | ||
Second-order model of the Generalized Anxiety Disorder 6-item (GAD-6). | Anxious distress, Anxiety | DISORDER | Values shown are standardized parameter estimates. The item numbers shown here are the item numbers from the Generalized Anxiety Disorder 7-item. GAD = Generalized Anxiety Disorder; Expectation = Apprehensive expectation dimension; Excitation = Autonomic excitation dimension; Distress = Anxious distress dimension. | PMC10174505 |
Discussion | Anxiety | DISORDER | This is the first study that reveals a 6-item second-order model with three specific factors of the Generalized Anxiety Disorder (GAD-6). The new model is superior to the original and other competing models in a sample of Malaysian university students.Our findings (of the second-order model) are consistent with Doi and colleagues’ [The GAD-6 and its three subscales have shown good reliability. The results are supportive that the GAD-6 may provide both clinically useful summed score and subscale scores. Following Stochl et al. [It was unexpected that Item 3 (Despite the promising findings, the present study is not without limitations. First, the results were derived from the original 7-item version of GAD-7. It is not clear whether the 6-item second-order model can be replicated if the data were collected using the newly proposed GAD-6. Second, test-retest reliability and diagnostic validity of the GAD-6 are not examined. Finally, the GAD-6 has not been examined in other cultures and its generalizability is limited. Therefore, further studies with a more inclusive population spectrum are warranted to verify our findings and further investigate the psychometric qualities of the GAD-6. | PMC10174505 |
Conclusion | anxiety disorder, Anxiety | DISORDER | The Generalized Anxiety Disorder 6-item (GAD-6) with a second-order structure is a psychometrically sound tool for researchers and clinicians to assess the overall severity level of anxiety disorder, as well as symptomatic dimensions in the Malaysian context. | PMC10174505 |
Supporting information | PMC10174505 | |||
Summary the factor structure of the Generalized Anxiety Disorder 7-item. | (DOCX)Click here for additional data file.The authors are grateful to the participants who took part in the study. We would also like to express our sincere gratitude to Kah-Yue Low, who played a crucial role in formatting this manuscript. Her tireless effort and dedication to ensuring the accuracy and consistency of the document were invaluable to the successful completion of this project. | PMC10174505 | ||
Background | Fracture, fracture | ENDODONTICALLY TREATED TEETH | Fracture resistance of post-core restoration depends on the design of the post, post diameter, post length, the type of adhesive cement used along with material of the core. Despite the different studies concerning the effect of post space diameter on the fracture resistance of endodontically treated teeth, more information regarding fracture resistance and the effect of different post space systems/materials and diameters is required. | PMC10714464 |
Aim of the study | fracture | ENDODONTICALLY TREATED TEETH | This study aimed to evaluate fracture resistance of endodontically treated teeth, restored with two post-core systems in different post space diameters. | PMC10714464 |
Materials and methods | incisors | Twenty freshly extracted maxillary central incisors were collected for this study. They were randomly divided into four groups according to intracanal post and its diameter. Group GN (glass-fiber post of 10-mm length and 1.3-mm diameter with composite core), group GW (glass-fiber post of 10-mm length and 1.75-mm diameter with composite core), group ZN (custom-made zirconia one-piece post-core of 10-mm length and 1.3-mm diameter) and group ZW(custom-made zirconia one-piece post-core of 10-mm length and 1.75-mm diameter).Fracture resistance for all samples was evaluated using the universal testing machine under a static load. The data was collected and statistically analyzed using One-Way ANOVA test. Modes of failure were assessed using stereomicroscope for each group. | PMC10714464 | |
Results | fracture | The highest mean fracture resistance was recorded in group GW (638.7 ± 285.1 N), followed by group ZW (598.5 ± 127.6 N), then GN group (442.8 ± 65.38 N). The lowest mean fracture resistance was recorded in group ZN (435.3 ± 117.3 N). One-Way ANOVA test revealed that there was no statistically significant difference in fracture resistance values among the groups. | PMC10714464 | |
Conclusion | fracture, tooth | ENDODONTICALLY TREATED TEETH | Post space diameter had an impact over the fracture resistance of endodontically treated teeth. Modulus of elasticity of post material had a major effect on the fracture resistance and mode of failure along with the restorability of the restored tooth. However, there was no statistically significant difference among the tested groups. | PMC10714464 |
Keywords | Open access funding provided by The Science, Technology & Innovation Funding Authority (STDF) in cooperation with The Egyptian Knowledge Bank (EKB). | PMC10714464 | ||
Background | major loss of natural tooth, fracture, incisors, tooth, trauma | FRAGILITY, DENTAL CARIES, AIDS, ENDODONTICALLY TREATED TEETH | The restoration of endodontically treated teeth is controversial and remains a challenge to the dental clinicians, as a result of major loss of natural tooth structure due to dental caries or trauma; which is mandatory for the retention of the coronal restoration. The remaining tooth structure is the most crucial factor for the good prognosis as they are devoid of mechanical properties including loss of strength, fragility as well as the liability to fracture [Endodontically treated teeth are traditionally restored with a post-core and crown foundation system which depend mainly on the design, material and modulus of elasticity of dental posts as they play a major role in retention and fracture resistance of coronal restoration of endodontically treated teeth [Posts are classified according to their material into metallic or tooth-colored posts. Tooth-colored posts are further classified into pre-fabricated and custom-made posts. Among the prefabricated type, fiber posts are the most appropriate to select as they acquire simple technique of application in addition to the optimum mechanical properties; dentin-like modulus of elasticity that aids in dissipation of occlusal forces and the decrease of incidence of root fracture [Fiber posts contain either carbon fibers or quartz fibers, embedded in epoxy or methacrylate resin matrix. The fibers are parallel to the long axis of the post with diameter ranging between 6 to 15 mm. While the number of fibers range between 25 and 35 per mmCustom-made tooth-colored posts include ceramic and zirconia posts. They are used when high esthetic demand is required in the anterior zone of teeth to prevent long term discoloration. However, these posts show difficult retrievability in the retreatment cases as the removal require rotary instruments which might lead to root fracture or perforation [Zirconia post and core system offers chemical stability and its similarity to natural tooth structure whereby the tooth-colored translucency of all-ceramic crowns that provides high stiffness and distributes stresses better to the root; providing greater clinical longevity, light transmission and radio-opacity as well as the promising esthetic restorative outcome to the patients [Grewal et al. and Khaldi et al. stated that the success of various post systems depend on length, diameter, design of the post, canal shape and preparation, ferrule, luting cement, technique of cementation along with its location in the dental arch and proper retention of the post is mandatory in order to sustain the vertical occlusal forces [Sughaireen et al. and Mou et al. recommended the optimum diameter of the post preparation to stay at one-third of root’s diameter or have 1:4 ratio approximately. This wide preparation of posts aided in resisting occlusal forces but led to root fracture [In spite of different statements concerning the effect of post space diameter on the fracture resistance of endodontically treated teeth, more information regarding fracture resistance and the effect of different post space systems/materials and diameters is required. This study aimed to evaluate fracture resistance of endodontically treated teeth, restored with two post-core systems in different post space diameters. The null hypothesis of this study was that there would be no significant difference between fracture resistance of endodontically treated maxillary central incisors, restored with glass-fiber posts and composite resin core and zirconia post-core one-piece restoration in different post space diameters. | PMC10714464 |
Materials and methods | fracture, incisors, orthodontic | STERILE, ROOT CARIES | This study was in-vitro, parallel controlled in which fracture resistance and failure mode of four parallel groups were examined. It was held at the Conservative Dentistry Department laboratory at the Faculty of Dentistry, Alexandria University, Egypt. A sample size was calculated using a sample size calculation program(G*Power version 3.1.9.2, Department of Biomedical Informatics and Medical Statistics, Medical Research Institute, University of Alexandria, Egypt.) [For this study, 20 freshly extracted, for orthodontic or diabetic purpose, maxillary central incisors were collected and preserved in normal sterile saline until the onset of use. For teeth standardization, teeth selected for this study had nearly same size and shape with intact coronal and apical structure as well as root canal diameters that aided in drilling of post spaces. Periapical radiographs were taken for each specimen to verify the straight pathway of the root canals. Each specimen was measured using a Digital Caliper (Sedradent, TDV Co. Pomerode, Santa Catarina, Brazil) to insure size range at the cervical line area of 6 ± 1 mm bucco-lingually and 5 ± 1 mm mesio-distally and root length from cemento-enamel junction to the root apex of 13 ± 0.5 mm. The specimens with similar root length and diameters were selected and stored in sterile saline solution until use.Teeth with extensive root caries, fracture, and internal/external cracks/resorption were excluded from this study. Also, teeth with previous endodontic treatment or severe apical curvature were excluded. | PMC10714464 |
Teeth preparation | calculus | DENTAL PLAQUE | The selected teeth root lengths were measured from the cervical line of teeth to the apex using Digital caliper (Sedradent, TDV Co. Pomerode, Santa Catarina, Brazil); they were more or less 13 mm long (± 0.5 mm). Teeth were then mechanically cleaned with aid of hand scaler (Nordent Manufacturing Inc., 610 Bonnie Lane, Elk Grove Village, IL 60007, T: 800.966.7336 US & Canada)to remove remaining dental plaque, calculus, and periodontal tissues [Eighteeth curing pen (Changzhou Sifary Medical Technology Co., Ltd.) was used to transilluminate the specimens at light intensity of 600 mW/cm2 and wavelength of 385 nm–410 nm to ensure they were devoid of any internal or external crack lines [Teeth were embedded in auto-polymerizing acrylic resin blocks, in cylindrical metallic molds, along with their vertical long axis; leaving 2 mm coronal structure out of each block. Teeth were then removed, light-body ZHERMACK Elite HD+(Zhermack S.p.A., Via Bovazecchino, 100 | 45,021 Badia Polesine (RO) ITALY) was injected all around the roots of specimens and inside their corresponding acrylic blocks and each specimen was repositioned into its specific block. Excess material was removed before complete setting. That step allowed the simulation of the periodontal ligament space in a thickness of 0.5 mm [Specimens held in acrylic resin blocks | PMC10714464 |
Access opening and root canal preparation of specimens | JapanWaveOne reciprocating | COLD, CAVITY, PULP STONES | Preoperative periapical radiograph was taken for each specimen to ensure absence of any kind of root canal calcifications, internal resorption or presence of pulp stones or accessory canals. Rose-head bur and Endo-Z(Komet Dental. Gebr. Brasseler GmbH & Co. KG Trophagener Weg 25.32657 Lemgo. Germany) were mounted on high-speed handpiece, respectively, for access cavity preparation. Root canal length determination was done by inserting number 10 k-file (MANI, INC., Tochigi-Ken, JapanWaveOne reciprocating single file(Maillefer-Dentsply, Ballaigues, Switzerland.) was used for mechanical preparation of root canals up to the full working length. The tip size was ISO 40 with an apical taper of 8% that reduced towards the coronal end. Regarding irrigation, 2.5% Sodium Hypochlorite irrigation solution using 30-gauge side-vented irrigation needle(SUNGO Certification Company Limited, RM101, Maple House, 118 High Street Purley, London, England.); after every instrument change to ensure the complete elimination of any dentinal debris which might cause blockage of the canals [Root canals were dried using #40 paper points until complete drying of the canals was achieved. Cold lateral condensation technique was followed to obturate all the canals using ISO #40 gutta-percha(Metabiomed Co. LTD, South Korea.) cone, ISO #30 gutta percha(Metabiomed Co. LTD, South Korea.) accessory cones and ADseal sealer(Metabiomed Co. LTD, South Korea.) to the full working length. Access cavities were then filled with Tetric N-ceram nanohybrid composite(Ivoclar Vivadent Dental Products, Liechtenstein, Germany.) temporarily to be stored in laboratory incubator at 37 °C and 100% relative humidity for at least 2 days; allowing the complete setting of endodontic sealer [ | PMC10714464 |
Grouping of specimens | The total number of specimens was randomly divided into two main groups (
| PMC10714464 | ||
Post space preparation | After the random division of specimens, the access cavities were reopened again with round bur mounted on a high-speed handpiece until completely removed. Post space preparation protocol was followed including removal of gutta percha from the two coronal thirds of the roots; which was approximately 10 mm long, leaving ±4 mm of gutta percha apically as an apical seal, indicating a long post space using peeso reamer drills (MANI, INC., Tochigi-Ken, Japan) that were mounted on a low-speed handpiece, length adjusted by endodontic ruler and then used in the order of #1, #2, #3 and #4 sequentially, to achieve a standardized post space preparation; 0.7, 0.9, 1.1 and 1.3 mm in diameter respectively. 10 mm of gutta percha was removed from all canals leaving 4 mm of coronal seal, to standardize the length of preparation in all specimens [ | PMC10714464 | ||
For the narrow glass-fiber post space preparation (subgroup GN) | Using no. 1 shaping drill of HAHNENKRATT-Contec glass-fiber post kit(E.HAHNENKRATT GMBH | Benzstr. 19 | DE-75203 Königsbach-Stein, Germany), the white calibration drill of 1.3 mm diameter was used to prepare a narrow post space, in respect of adjusting the drill’s length to 10 mm [ | PMC10714464 | ||
For the wide glass-fiber post space preparation (subgroup GW) | Using no. 3 shaping drill of HAHNENKRATT-Contec glass-fiber post kit, the blue calibration drill of 1.75 mm diameter was used to prepare a wide post space, in respect of adjusting the drill’s length to 10 mm [Regarding the composite resin core that was built in both subgroups GN and GW, it had dimensions of 4-mm labio-palatally, 4-mm mesio-distally and 4-mm inciso-cervically. These composite cores were then built after the cementation procedure of glass fiber posts [ | PMC10714464 | ||
For the narrow zirconia post space preparation (subgroup ZN) | For a standardized post space preparation and to ensure the similar and precise dimensions of both glass-fiber post and custom-made zirconia post, the same calibration drill of group GN was also used in ZN subgroup.No. 1 white calibration drill of 1.3 mm diameter was used to prepare a narrow post space, in respect of adjusting the drill’s length to 10 mm [ | PMC10714464 | ||
For the wide zirconia post space preparation (subgroup ZW) | Using the shaping drills of Contec-HAHNENKRATT glass-fiber post kit, no. 3 blue calibration drill of 1.75 mm diameter was used to prepare a wide post space for the ZW subgroup, in respect of adjusting the drill’s length to 10 mm [Periapical radiograph was taken for each specimen to insure complete removal of root canal filling material as well as the fitting of the corresponding glass-fiber post in both subgroups ZN and ZW [ | PMC10714464 | ||
Direct post-core pattern fabrication (subgroups ZN and ZW) | Post spaces were irrigated with 2.5% NaoCl, normal saline and 70% alcohol then partially dried with air/water syringe then completely dried using endodontic paper points. Plastic posts were firstly inserted into specimens’ canals to check its fitting passively, each plastic post was marked to the predetermined length; 10 mm length, then was inserted back to confirm the proper seating [Light-cured universal modelling acrylic resin of gel-consistency (Sedradent, TDV Co. Pomerode, Santa Catarina, Brazil)was injected into each prepared canal around the plastic post, slight bumping motion was done without any excessive pressure, to the predetermined length. Light-curing of the material was done for 20 seconds and 1500 mW/cmThe core was built with the same material; light-cured universal modelling acrylic resin of paste-consistency (Sedradent, TDV Co. Pomerode, Santa Catarina, Brazil) with the same dimensions of core of GN and GW subgroups. After obtaining the proper dimensions, the core was finished and polished using composite finishing and polishing burs [ | PMC10714464 | ||
Scanning of resin pattern | The fabricated direct resin patterns were held upside down, the highest point of the core curvature was placed over the stiff clay that was supported in metallic circular molds to ease the scanning procedures without deformation of the pattern and gaining the correct dimensions throughout the scanning process. | PMC10714464 | ||
Designing and milling of zirconia one-piece post-core restoration | ZirkonZahn blank(Prettau 2 Dispersive, Zirkonzahn Srl, Via An Der Ahr 7–39,030 Gais(Bz),Val Pusteria-South Tyrol–Italy)was used for the milling process to fabricate the zirconia post-core samples into the required dimensions, leaving 2-mm ferrule all around which permitted zirconia core to mimic same dimensions of composite cores in both groups GN and GW, by using ED5X(EMAR MILLS,C2, Industrial Complex, 10th of Ramadan City Asharqia, Egypt) milling machine, with prime water cooling system to produce one-piece post-core unit with respect to different diameters of tested groups (LN and LW). Nevertheless in this study, dry milling was performed in conjugation to dust extraction unit to vacuum any dust or particles resulting from the milling process. The milling process took about 10 minutes for each specimen, according to manufacturer’s instructions. | PMC10714464 | ||
Sintering of the zirconia post-core restorations | furnace | MV-R (MIHM-VOGT GmbH & Co.; Friedrich-List-Str. 876,297 Stutensee-Blankenloch) sintering furnace was used to sinter zirconia samples that took about 8 hours, as it required 4 hours to raise from room temperature up to 1550 | PMC10714464 | |
Cementation of glass-fiber posts in subgroups GN and GW | Post spaces were irrigated with 2.5% NaoCl, normal saline and 70% alcohol, dried and etched with 37% phosphoric acid(Metabiomed Co. LTD, South Korea) then rinsed with water then completely dried by endodontic absorbing paper points(Metabiomed Co. LTD, South Korea) [Calibra Universal Self-Adhesive resin cement (Maillefer-Dentsply, Ballaigues, Switzerland) was used for cementation of each specimen with changing injection tip, with respect to different diameters for each subgroup. Following the manufacturer’s instructions, the auto-mixing tip was attached then injection of the cement was done into the post spaces as well as all around posts’ surfaces. It was light-cured for 20 seconds. The excess cement was removed using composite finishing burs(Komet Dental. Gebr. Brasseler GmbH & Co. KG Trophagener Weg 25.32657 Lemgo. Germany) mounted on high-speed handpiece. | PMC10714464 | ||
Composite resin core for subgroups GN and GW | After cementation of the glass-fiber posts, Tetric N-ceram nano-hybrid composite (Ivoclar Vivadent Dental Products, Liechtenstein, Germany) was used to build the core for both subgroups GW and GN. It was dome-shaped with dimension of 4-mm circumferentially [ | PMC10714464 | ||
Luting the fabricated zirconia post-core for subgroups ZN and ZW | Calibra Universal Self-Adhesive resin cement was also used to cement the zirconia post-core restorations into their corresponding post spaces in each group, in respect to different diameters for each subgroup. | PMC10714464 | ||
Tests | PMC10714464 | |||
Fracture resistance test | Samples with the acrylic resin blocks were held in metallic molds for testing. Specimens were loaded at 3 mm below the incisal part of the core palatally at an angle of 45Specimens with acrylic resin blocks held in metallic molds to be tested by universal testing machine | PMC10714464 | ||
Assessment of mode of failure | fracture | To determine the type of failure, the failed teeth were examined under a stereomicroscope (SZ1145TR Olympus; Japan 1990) by using software (Toup view, version 3.7). It was classified as follows [
Favorable or restorable failure: When the failure or fractured line or area was found to be above the cervical line of restored teeth.Non-favorable or non-restorable or catastrophic failures: were present when the fracture line or failure occurred at the cervical line or extended beyond it. Vertical root fracture is also included. | PMC10714464 | |
Statistical analysis | Comparison between the four study groups was done using One-Way ANOVA test. Data were fed to the computer and analyzed using IBM SPSS software package version 20.0 | PMC10714464 | ||
Discussion | tooth dentin, failure of teeth, Fracture, fracture, incisors, rigidity, fractures, tooth, lower mean fracture | AIDS, ENDODONTICALLY TREATED TEETH, CAVITY | When the remaining tooth structure of endodontically treated teeth cannot provide sufficient support and retention for restoration; remaining less than 50% of tooth structure, post and core is beneficial. So the rehabilitation of pulpless teeth is crucial in order to restore them esthetically, functionally and structurally for a successful restorative outcome and prognosis [Fracture resistance of post-core restoration depends on the design of the post, post diameter, post length, the type of adhesive cement used along with material of the post and core system material that aids in dissipation of occlusal forces along to the post then to remaining radicular root [Mechanical properties vary between different types of posts. An ideal post-core foundation should have superior fracture resistance that is higher than mastication forces. While other mechanical properties such as elastic modulus, coefficient of thermal expansion and compressive strength must be same as those of radicular dentin [This study investigated the fracture resistance of endodontically treated maxillary central incisors, restored with two post-core systems in 1.3-mm (narrow) and 1.75-mm (wide) post space diametersThus in this study there was no statistically significant difference among the four groups. Although, mean fracture resistance was in its highest value in group GW (638.7 ± 285.1 N), followed by group ZW (598.5 ± 127.6 N), then GN group (442.8 ± 65.38 N). The lowest mean fracture resistance was recorded in group ZN (435.3 ± 117.3 N).The highest fracture resistance was found in subgroup GW; glass fiber posts with 1.75 mm diameter, with mean of 638.7 ± 285.1 N. This high value is attributed to that the modulus of elasticity of glass fiber posts is almost same as that of radicular dentin. This supported the presence of a monoblock that aided in dissipation of forces along the long axis of the post itself, thus high resistance of the roots against fracture when subjected to occlusal forces. This came in agreement with a study by Habibzadeh et al. [In accordance with the results of the current study, previous studies also reported that increasing the post diameter enhances its fracture resistance. They reported value of 514.2 ± 136.3 N, which is comparable to the findings of the present study. However, this leads to the excessive removal of sound tooth dentin and hence weakening of the residual tooth structure occurs [Kul et al. explained the most probable reason causing the variety in mode of failure. They reported that the low modulus of elasticity of glass-fiber post closely reaches that of dentin. While zirconia posts have high modulus of elasticity. The low modulus of elasticity aided in the absorption of forces along the length of fiber posts as well as its ability to bond to the tooth dentin; providing a monoblock effect, greatly reducing the force transmission to the tooth leading to lower risk of fracture. That also came in agreement with the results of the current study [Previous studies by Saritha et al., Kurthukoti et al. and Shukla et al. compared fracture resistance of zirconia posts and glass fiber posts of endodontically treated teeth. They proved that fracture resistance between tested groups was not significant (On the contrary, Habibzadeh at al., evaluated the fracture resistances of zirconia and fiber-composite post systems under all-ceramic crowns in endodontically treated teeth. Fiber-glass posts with composite cores showed the highest fracture resistance values (915.70 ± 323 N), while the zirconia post-system showed the lowest resistance (435.34 ± 220 N). The differences among the groups were statistically significant (Özarslan et al. investigated the fracture resistance and fracture mode of maxillary central incisors restored with two different diameters and three different post-core systems. Their study revealed that the highest fracture strength was found in Group F; teeth restored with glass fiber posts, followed by group Z; teeth restored with zirconia custom-made posts. Their findings showed statistically significant differences existed between the fracture strengths of the post materials, which came in contrary to the findings of the current study. That might be explained by the different types of zirconia used as well as the glass-fiber post, in addition to the minute difference in post space diameters in that study; 1.4-mm and 1.6-mm [Subgroup ZW; custom-made zirconia posts with 1.75 mm diameter, showed a slightly lower mean fracture resistance than subgroup GW. This is supported by a previous study by Alkhatri et al. and Abduljabbar et al., as they reported that CAD/CAM zirconia posts had high fracture resistance due to the chemical stability, high elastic modulus, and high toughness in conjugation with mechanical strength [Regarding zirconia post-core unit, Prettau Zirkonzahn was used in this study. Prettau Zirconia is partially stabilized with yttrium and enhanced with aluminum. This aided in increasing mechanical properties; high flexural strength up to 1200 MPa, along with stable shrinking feature allowing the optimum precision [All samples restored with zirconia post-core system showed non-favorable mode of fracture. This came in correlation with the variation between elastic modulus of zirconia post, which is high, and the radicular dentin that varies between 12 and 14 MPa [Previous studies evaluated flexural strength (900–1200 MPa) of zirconia posts and high modulus of elasticity of 200 MPa which prevent the plastic manner of the material to be presented; resisting high forces but without dissipation. This led to failure of teeth in a non-restorable manner; vertical root fracture that end by extraction of the restored teeth [Subgroup GN showed lower values of fracture resistance as they had a narrower diameter that couldn’t resist forces and failed at less exerted forces. However, failures were confined to the core foundation only, without any damage to the tooth itself. This came in agreement with a study by Özarslan et al. [A study by Beck at al. reported that fracture resistance of glass-fiber posts was not significantly different to that of custom-made zirconia one piece post and core. They also reported that catastrophic failures most often occur with zirconia posts and restorable fractures occurred with glass-fiber posts. That came in accordance to the findings of this study as all samples of group G showed favorable fractures that were confined to the core material only or barely reaching the post itself, while zirconia posts showed catastrophic failure that unfortunately end by tooth extraction [This study’s findings were also in agreement with a study by Habibzadeh et al., Gu et al. and Akkayan and Gülmez stated that fractures associated with zirconia posts were mostly non-restorable, while these associated with glass-fiber posts were more reparable. They came out with an explanation that the high rigidity as well as the high elastic modulus of zirconia posts transfer subjected forces directly to the tooth without any kind of dissipation or absorption by the post-core unit, and that was the main reason causing the fracture of restored teeth. That also came in agreement with the findings of the current study [Limitations of the present study is the lower sample size and the lack of thermal changes that are present in the oral environment and masticatory forces were not applied as it is an in-vitro study, which does not reflect the oral cavity conditions as well as the absence of cyclic loading of the specimens before testing which might alter the results. So, further in-vivo studies are required to evaluate fracture resistance of different esthetic posts in oral environment for successful prosthodontic procedures. So the use of chewing stimulator, crown restoration and cyclic loading of the samples is recommended to obtain more consistent results to the clinical situation. That’s because in the current study, a universal testing machine with a static manner was used to measure fracture resistance of specimens. Furthermore, the teeth collected for this study were selected according to the preferred post sizes. The different canal configurations, post drills and posts themselves may have affected the homogeneity of the cement thickness between the post and root canal wall. Also, a larger sample size is recommended in further in-vitro studies to obtain a more accurate significant difference among the groups in future studies. | PMC10714464 |
Conclusion | fracture | ENDODONTICALLY TREATED TEETH | Based on the findings of this study, we conclude that:
There is no statistically significant difference between fracture resistance of endodontically treated teeth restored with either zirconia post-core or glass fiber post and composite resin core in different post space diameters. Highest was presented in group GW and lowest was exhibited in group ZN.The increase in post diameter increases the fracture resistance of the post itself, however, it greatly affects the fracture resistance of remaining radicular dentin.Modulus of elasticity is a major contributing factor that affects the fracture resistance of endodontically treated teeth and their mode of failure that occurs.Teeth restored with glass fiber posts and composite resin core can be retreated after their favorable failure. On the other hand, teeth restored with custom-made zirconia post-core require extraction later on as their failure extends beyond the cervical line and involves vertical fracture along the length of the root. | PMC10714464 |
Authors’ contributions | K.B. contributed to the study design, the data acquisition, analysis, and interpretation, and wrote the manuscript draft. R.G. contributed to the study design, and the interpretation of the results, and revised the manuscript. S.I. contributed to the study design, revised the manuscript, and supervised the work.All authors have read and approved the final manuscript. | PMC10714464 | ||
Funding | Open access funding provided by The Science, Technology & Innovation Funding Authority (STDF) in cooperation with The Egyptian Knowledge Bank (EKB). This study was not funded by any agency in the public, commercial, or non-profit sectors. Open access funding provided by The Science, Technology & Innovation Funding Authority (STDF) in cooperation with The Egyptian Knowledge Bank (EKB). | PMC10714464 | ||
Availability of data and materials | The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request. | PMC10714464 | ||
Declarations | PMC10714464 | |||
Ethics approval and consent to participate | This study was approved by the Scientific Research Ethics Committee at the Faculty of Dentistry, Alexandria University (International No.: IORG0008839, Ethics Committee No.: 0436–05/2022). All methods were performed in accordance with the Declaration of Helsinki and the ethical guidelines adopted by the Research Ethics Committee of the Faculty of Dentistry, Alexandria University. No human participants were involved in the study. The need for informed consent was waived by the Ethics committee of the Faculty of Dentistry, Alexandria University. | PMC10714464 | ||
Consent for publication | Not applicable. | PMC10714464 | ||
Competing interests | The authors declare no competing interests. | PMC10714464 | ||
References | PMC10714464 | |||
Methods | ™ Q SARS-CoV-2 | COVID-19 INFECTION | Adults and children with symptoms consistent with suspected current COVID-19 infection were prospectively recruited from 19 UK general practices and two COVID-19 testing centres between October 2020 and October 2021. Participants were tested by trained healthcare workers using at least one of two index POCTs (Roche-branded SD Biosensor Standard™ Q SARS-CoV-2 Rapid Antigen Test and/or BD Veritor™ System for Rapid Detection of SARS-CoV-2). The reference standard was laboratory triplex reverse transcription quantitative PCR (RT-PCR) using a combined nasal/oropharyngeal swab. Diagnostic accuracy parameters were estimated, with 95% confidence intervals (CIs), overall, in relation to RT-PCR cycle threshold and in pre-specified subgroups. | PMC10361479 |
Results | SENSITIVITY | Of 663 participants included in the primary analysis, 39.2% (260/663, 95% CI 35.5% to 43.0%) had a positive RT-PCR result. The SD Biosensor POCT had sensitivity 84.0% (178/212, 78.3% to 88.6%) and specificity 98.5% (328/333, 96.5% to 99.5%), and the BD Veritor POCT had sensitivity 76.5% (127/166, 69.3% to 82.7%) and specificity 98.8% (249/252, 96.6% to 99.8%) compared with RT-PCR. Sensitivity of both devices dropped substantially at cycle thresholds ≥30 and in participants more than 7 days after onset of symptoms. | PMC10361479 | |
Conclusions | infection | INFECTION, DISEASE | Both POCTs assessed exceed the Medicines and Healthcare products Regulatory Agency target product profile’s minimum acceptable specificity of 95%. Confidence intervals for both tests include the minimum acceptable sensitivity of 80%. In symptomatic patients, negative results on these two POCTs do not preclude the possibility of infection. Tests should not be expected to reliably detect disease more than a week after symptom onset, when viral load may be reduced. | PMC10361479 |
Data Availability | Data cannot be shared publicly because of participant confidentiality considerations. Research data access requests should be submitted to the Nuffield Department of Primary Care Health Sciences Information Guardian for consideration (contact via | PMC10361479 |
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