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PubMed2006

[Specific strength measurement of musculus abductor pollicis brevis in order to objectively evaluate muscle regeneration after carpal tunnel release surgery].

47 patients with a carpal tunnel syndrome were preoperatively examined not only by electrophysical studies (nerve velocity and distal motoric latency) and clinical tests (Phalen's sign, Tinel's sign) but also by measuring the strength of the M. abductor pollicis brevis with a specifically designed strength-testing unit. 30 patients agreed to participate in a voluntary postoperative examination. In the 45 degrees -measurement there was a relative strength loss of the injured hand's thumb of about 25 % in comparison with the healthy hand preoperatively. The postoperative strength disadvantage amounted to only 10 %. Measurement of the strength in the neutral zero method showed a relative strength loss of the injured hand's thumb of 8 % while postoperatively there was even a strength advantage of 9 % in comparison with the thumb of the healthy hand. Both methods showed a relevant and significant postoperative strength increase of the injured hand's thumb. We could prove a significant correlation (p = 0.03) of the neutral zero strength measurement and the distal motoric latency of the median nerve. Furthermore, we could show a trend for a correlation between the neutral zero strength measurement and the median motoric velocity. In conclusion, it can be said that the special strength measurement of the M. abductor pollicis brevis is an important parameter to objectively evaluate the motoric symptomatology in carpal tunnel syndrome patients.

Adult↗

PubMed2001

Nutrition and handgrip strength of older adults in rural Malawi.

OBJECTIVE: To examine the relationship between the nutritional status and handgrip strength of older people in rural Malawi. DESIGN: Cross-sectional study. SETTING: : Lilongwe rural, Malawi, situated approximately 35-50 km from the city. SUBJECTS: Ninety seven males and 199 females participated in this study. METHODS: Selected anthropometric measurements were taken and nutrition indices were computed using standard equations. Handgrip strength was measured using an electronic grip strength dynamometer. RESULTS: The mean handgrip strength (in kg) for men was significantly higher than for women vs. In addition, there was a significant decline in handgrip strength with age in both sexes. Furthermore, handgrip strength was positively correlated to the following nutritional status indicators: BMI in males and in females), mid-upper arm circumference (MUAC) in males and in females) and arm-muscle area (AMA) in males and in females). After controlling for potential confounders, namely sex, height and age, the correlations between handgrip strength and the nutrition indices were still significant. CONCLUSION: The results of this study support the hypothesis that poor nutritional status is associated with poor handgrip strength. Malawian males had both lower handgrip strength and lower arm muscle area than their counterparts from industrialised countries. However, Malawian females had similar handgrip strength despite lower arm muscle area, in comparison with women from industrialised countries, reflecting perhaps their higher level of physical activity. Further studies are required to determine whether by alleviating nutritional problems a concomitant improvement in handgrip strength can be obtained.

Aged↗

PubMed2002

Norms for grip strength in children aged 4-16 years.

UNLABELLED: The aim of this study was to provide norms for grip strength in children. A total of 530 Swedish 4-16-y-olds was tested with the instrument Grippit. The instrument estimates peak grip strength over a 10s period, and sustained grip strength averaged across the 10s. The increase in grip strength with age was approximately parallel for boys and girls until 10 y of age, after which boys were significantly stronger than girls. Strong correlations existed between grip strength and the anthropometric measures weight, height and, in particular, hand length. Right-handed children were significantly stronger in their dominant hand, while left-handers did not show any strength difference between the hands. It is therefore suggested that when evaluating grip strength in left-handed children both hands should be assumed to be about equally strong, while right-handed children are expected to be up to 10% stronger with their right hand. Sustained grip strength was consistently about 80-85% of peak grip strength, with somewhat lower values in younger children. The present normative data for peak grip strength were slightly lower than 1980s' data from the USA and Australia, probably because of divergences in age grouping and in instruments used. CONCLUSION: Norms for grip strength including estimates of variation were provided for children aged 4-16 y. These data will enable therapists and physicians to compare a patient's score with the scores of normally developed children according to age, gender, handedness and body measures.

Adolescent↗

PubMed2001

Evaluation of grip strength with a sustained maximal isometric contraction for 6 and 10 seconds.

The grip strength in which subjects sustained a maximal isometric contraction for 6 seconds (the 6-second test) was compared with that for 10 seconds (the 10-second test) to clarify a reliable sustained grip strength test procedure. Fifty healthy students (22+/-4 years, 25 men and 25 women) participated in this study. Strength was measured continuously by the Dexter (Cedaron Medical Inc.). The maximal grip strength, the peak time, and the momentary strength every second during a trial were evaluated. For both tests, the reliable maximal strength and a typical strength-time curve consisting of an early peak time and a decrease in the strength after the peak gradually over time were obtained. In the 6-second test, the momentary strength after 5 seconds that was 82+/-10 approximately 87+/-7% of the peak strength showed good reliability. This variable may be effective in assessing the ability to sustain maximal grip strength.

Adolescent↗

PubMed1996

Tongue strength and endurance in different aged individuals.

BACKGROUND: It is generally accepted that age-related changes occur in voluntary muscle. Studies of hand grip strength and aging demonstrate a decrease in strength with age; however, there are little data regarding tongue function. The purpose of this study was to determine the relationship of increased age to tongue strength and endurance. METHODS: A pressure transducer, the Iowa Oral Performance Instrument, was used to measure maximal strength and endurance of both the hand and tongue. Ninety-nine healthy volunteers from the oral physiology component of the Baltimore Longitudinal Study of Aging were divided into four age groups, ranging from 21 to 96 years of age. A multivariate analysis of variance was used to determine differences in strength and endurance between age groups and genders. Regression analysis was done to determine the relationship of strength and endurance with age. RESULTS: Gender analysis indicated that both tongue and hand strength were greater in males; however, tongue and hand endurance demonstrated no gender differences. The strength in both the tongue and hand decreased with age. Individuals over the age of 79 years showed statistically decreased tongue strength, and individuals over the age of 59 years showed statistically decreased hand strength. There was no significant change in the tongue and hand endurance with age. CONCLUSIONS: The results of this study suggest that tongue function is gender- and age-dependent and follows the same trends as hand function. Tongue strength is decreased in older individuals and females, while tongue endurance is gender- and age-independent.

Adult↗

PubMed2002

Skeletal muscle strength as a predictor of all-cause mortality in healthy men.

Low muscle strength is associated with mortality, presumably as a result of low muscle mass (sarcopenia) and physical inactivity. Grip strength was longitudinally collected in 1071 men over a 25-year period. Muscle mass was estimated by using 24-hour creatinine excretion and physical activity values, obtained by questionnaire. Survival analysis examined the impact of grip strength and rate of change in strength on all-cause mortality over 40 years. Lower and declining strength are associated with increased mortality, independent of physical activity and muscle mass. In men <60 years, rate of loss of strength was more important than the actual levels. In men >/=60 years, strength was more protective than the rate of loss, which persisted when muscle mass was considered. Strength and rate of change in strength contribute to the impact of sarcopenia on mortality. Although muscle mass and physical activity are important, they do not completely account for the impact of strength and changes in strength.

Adult↗

PubMed2002

Relationship of interleukin-6 and tumor necrosis factor-alpha with muscle mass and muscle strength in elderly men and women: the Health ABC Study.

BACKGROUND: A decline in muscle mass and muscle strength characterizes normal aging. As clinical and animal studies show a relationship between higher cytokine levels and low muscle mass, the aim of this study was to investigate whether markers of inflammation are associated with muscle mass and strength in well-functioning elderly persons. METHODS: We used baseline data (1997-1998) of the Health, Aging, and Body Composition (Health ABC) Study on 3075 black and white men and women aged 70-79 years. Midthigh muscle cross-sectional area (computed tomography), appendicular muscle mass (dual-energy x-ray absorptiometry), isokinetic knee extensor strength (KinCom), and isometric grip strength were measured. Plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were assessed by enzyme-linked immunosorbent assay (ELISA). RESULTS: Higher cytokine levels were generally associated with lower muscle mass and lower muscle strength. The most consistent relationship across the gender and race groups was observed for IL-6 and grip strength: per SD increase in IL-6, grip strength was 1.1 to 2.4 kg lower (p <.05) after adjustment for age, clinic site, health status, medications, physical activity, smoking, height, and body fat. An overall measure of elevated cytokine level was created by combining the levels of IL-6 and TNF-alpha. With the exception of white men, elderly persons having high levels of IL-6 (>1.80 pg/ml) as well as high levels of TNF-alpha (>3.20 pg/ml) had a smaller muscle area, less appendicular muscle mass, a lower knee extensor strength, and a lower grip strength compared to those with low levels of both cytokines. CONCLUSIONS: Higher plasma concentrations of IL-6 and TNF-alpha are associated with lower muscle mass and lower muscle strength in well-functioning older men and women. Higher cytokine levels, as often observed in healthy older persons, may contribute to the loss of muscle mass and strength that accompanies aging.

Aged↗

PubMed2006

Lower extremity strength and power are associated with 400-meter walk time in older adults: The InCHIANTI study.

BACKGROUND: It has been suggested that lower extremity muscle power is more important for physical function in older adults compared to strength, and that there is a nonlinear relationship between power or strength and physical function that might be indicative of a threshold above which the association between muscle function and physical function is no longer evident. This study examined the association between lower extremity strength or power with the time to complete a 400-meter walk, and attempted to identify thresholds within the relationship. METHODS: A cross-sectional analysis of a sample of 384 females and 336 males aged > or = 65 years from the InCHIANTI study ("Invecchiare in Chianti," i.e., Aging in the Chianti Area) was conducted. Measures included 400-meter walk time, lower extremity strength and power, comorbidities, and sociodemographic variables (age, gender, height, education, cognitive function, depression). RESULTS: Linear regression models showed that both lower extremity strength and power were significant predictors of 400-meter walk time, although power explained marginally more of the variance in 400-meter walk time. Quadratic models of lower extremity strength and power fit the data slightly better than the linear models. Regardless of gender, comorbidities, or normalization scheme for strength and power, the curvilinear form of the relationship between strength or power and 400-meter walk time remained the same. CONCLUSIONS: Lower extremity muscle strength and power are both important predictors of the 400-meter walk time. Although curvilinear relationships existed between muscle strength and power and the 400-meter walk time, the data do not indicate a clear threshold for either strength or power above which the performance in the 400-meter walk test plateaus.

Aged↗

PubMed2006

Developmental origins of midlife grip strength: findings from a birth cohort study.

BACKGROUND: There is growing evidence that the prenatal environment has long-term effects on adult grip strength, but little is known about the effects of the postnatal environment. We tested whether prepubertal growth, pubertal growth, or the development of motor and cognitive capabilities was associated with midlife muscle strength independently of other determinants of grip strength. METHODS: Handgrip strength and body size were measured in a representative British sample of 1406 men and 1444 women 53 years old with prospective childhood data. Normal regression models were used to examine the effects of birth weight, postnatal height and weight gain before 7 years and between 7 and 15 years, motor milestones and cognitive ability on grip strength at age 53, taking account of lifetime social class, current physical activity, and health status. RESULTS: Birth weight and prepubertal height gain were associated with midlife grip strength, independently of later weight and height gain and other determinants. Pubertal growth was also independently associated with midlife grip strength; for men weight gain during puberty was beneficial, whereas for women it was height gain. Those participants with earlier infant motor development had better midlife grip strength, which was partly confounded by the growth trajectory. CONCLUSIONS: This study showed that components of prenatal, prepubertal, and pubertal growth have long-term effects on midlife grip strength. To the extent that these associations are modifiable, interventions in childhood that help to build muscle mass and strength, such as increased physical exercise, may have long-term beneficial effects on adult muscle strength and may help to prevent sarcopenia, disability, and frailty in later life.

Adolescent↗

PubMed2005

Low grip strength is associated with bone mineral density and vertebral fracture in women.

OBJECTIVES: Grip strength has been reported to be associated with bone mass locally at the forearm and also at distant skeletal sites, including the spine and hip. Less is known about the association between low grip strength and risk of vertebral fracture. The aim of this study was to examine the association between low grip strength, bone mineral density at the hip and spine, and vertebral fracture in middle-aged and elderly European men and women. METHODS: Men and women aged 50 yr and over were recruited for participation in a screening survey of vertebral osteoporosis across Europe. Subjects who agreed to take part had an interviewer-administered questionnaire and lateral spinal radiographs performed. Subjects were assessed also for grip strength using a handgrip dynamometer (range 0-300 mmHg). A subsample of those recruited had bone mineral density measurements performed at the spine and femoral neck. Subjects had repeat lateral spine radiographs performed a mean of 3.8 yr following the baseline survey. Linear regression analysis was used to determine the association between low grip strength and bone mineral density at the hip and spine. Logistic regression was used to determine the association between grip strength and both prevalent and incident vertebral fracture. RESULTS: One thousand two hundred and sixty-five men and 1380 women with data concerning grip strength and bone mineral density were included in the analysis. In women, after age adjustment, compared with those with 'normal' grip, those with 'impaired' (231-299 mmHg) and low grip (<231 mmHg) had significantly lower bone mass at the spine and femoral neck. In men, those with low grip strength had a lower BMD at the spine and hip than those in the normal group. However, because of the small numbers with submaximal grip strength, the confidence intervals around all estimates included zero. Adjustment for body size and levels of physical activity had little effect on the results. In addition, among women, after adjustment for age, body mass index and physical activity levels, compared with those with normal grip, those with low grip strength had an increased risk of developing incident vertebral fracture (odds ratio = 2.67; 95% confidence interval 1.13, 6.30). Further adjustment for spine bone density had little influence on the association (odds ratio = 2.60). CONCLUSIONS: In women, low grip strength is associated with low bone mineral density at both the spine and hip and an increased risk of incident vertebral fracture. These associations cannot be explained by differences in body size or lifestyle.

Absorptiometry, Photon↗

PubMed2005

Cognitive status, muscle strength, and subsequent disability in older Mexican Americans.

OBJECTIVES: To examine the association between Mini-Mental State Examination (MMSE) score and subsequent muscle strength (measured using handgrip strength) and to test the hypothesis that muscle strength will mediate any association between impaired cognition and incident activity of daily living (ADL) disability over a 7-year period in elderly Mexican Americans who were initially not disabled. DESIGN: A 7-year prospective cohort study (1993-2001). SETTING: Five southwestern states (Texas, New Mexico, Colorado, Arizona, and California). PARTICIPANTS: Two thousand three hundred eighty-one noninstitutionalized Mexican-American men and women aged 65 and older with no ADL disability at baseline. MEASUREMENTS: In-home interviews in 1993/1994, 1995/1996, 1998/1999, and 2000/2001 assessed social and demographic factors, medical conditions (diabetes mellitus, stroke, heart attack, and arthritis), body mass index (BMI), depressive symptomatology, handgrip muscle strength, and ADLs. MMSE score was dichotomized as less than 21 for poor cognition and 21 or greater for good cognition. Main outcomes measures were mean and slope of handgrip muscle strength over the 7-year period and incident disability, defined as new onset of any ADL limitation at the 2-, 5-, or 7-year follow-up interview periods. RESULTS: In mixed model analyses, there was a significant cross-sectional association between having poor cognition (MMSE<21) and lower handgrip strength, independent of age, sex, and time of interview (estimate=-1.41, standard error (SE)=0.18; P<.001). With the introduction of a cognition-by-time interaction term into the model, there was also a longitudinal association between poor cognition and change in handgrip strength over time (estimate=-0.25, SE=0.06; P<.001), indicating that subjects with poor cognition had a significantly greater decline in handgrip strength over 7 years than those with good cognition, independent of age, sex, and time. This longitudinal association between poor cognition and greater muscle decline remained significant (P<.001) after controlling for age, sex, education, and time-dependent variables of depression, BMI, and medical conditions. In general estimation equation models, having poor cognition was associated with greater risk of 7-year incident ADL disability (odds ratio=2.01, 95% confidence interval (CI)=1.60-2.52); the magnitude of the association decreased to 1.66 (95% CI=1.31-2.10) when adjustment was made for handgrip strength. CONCLUSION: Older Mexican Americans with poor cognition had steeper decline in handgrip muscle strength over 7 years than those with good cognition, independent of other demographic and health factors. A possible mediating effect of muscle strength on the association between poor cognition and subsequent ADL disability was also indicated.

Activities of Daily Living↗

PubMed1994

Early tensile bond strengths of several enamel and dentin bonding systems.

Tensile bond strength tests are commonly used for the evaluation of adhesive dental materials. The majority of these tests are carried out after 24 h of storage in water. However, determination of the early tensile bond strength could be more important, especially in relation to gap formation between the cavity surface and the restorative material. This study investigated the tensile bond strengths of five enamel/dentin bonding systems and two experimental dentin bonding systems. Tensile bond strengths were obtained at one min, ten min, and 24 h after the resin composite was cured. Bond strengths at the early stages were always somewhat less than the 24-hour test results. For the enamel/dentin bonding systems, a significant difference was found between the enamel and dentin bond strengths at all time periods, except with Superbond D-liner and Liner Bond. The experimental group with glyceryl methacrylate as the primer produced a good 24-hour result (14.3 MPa), but the early bond strengths were no different from those in the non-primer-treated groups. It was concluded that this material may actually retard the polymerization of the bonding resin. Previous workers have suggested that a tensile bond strength in the order of 20 MPa is necessary for gap-free restorations to be obtained. Should this be the case, then all of the materials tested, from the aspect of early bond strength, lack the strength for prevention of gap formation, although Superbond D-liner and Liner Bond approached this hypothetical figure. These systems, Superbond D-liner and Liner Bond, also exhibit small differences between the enamel and dentin tensile bond strengths.

Analysis of Variance↗

PubMed2006

Plantarflexion strength of the toes: age and gender differences and evaluation of a clinical screening test.

BACKGROUND: The toes play an important stabilizing role in weightbearing activities. However, the factors that influence toe plantarflexion strength are poorly understood, and there are no validated measures for assessing toe weakness in the clinical setting. Therefore, the objectives of this study were to determine whether plantarflexion strength of the toes differs according to age and gender and to evaluate the validity of a clinical screening test for assessing toe plantarflexor weakness (the paper grip test). METHODS: Plantarflexion strength of the hallux and lesser toes was measured in 40 young participants (20 men and 20 women, mean age 20.8 +/- 2.2 years) and 40 older participants (20 men and 20 women, mean age 74.6 +/- 5.7 years) using a pressure platform in conjunction with clinical assessment using the paper grip test. RESULTS: Older participants exhibited 32% less plantarflexion strength of the hallux and 27% less plantarflexion strength of the lesser toes compared to younger participants, and women exhibited 42% less hallux plantarflexor strength than men. Gender did not influence lesser toe plantarflexor strength. Participants who failed the paper grip test exhibited significantly reduced plantarflexion strength for both the hallux and lesser toes. The sensitivity and specificity of the paper grip test of the hallux to predict plantarflexor strength less than 2.6 kg was 80% and 79%, respectively, and the sensitivity and specificity of the paper grip test of the lesser toes to predict plantarflexor strength less than 2.2 kg was 75% and 74%, respectively. CONCLUSIONS: These findings indicate that aging is associated with reduced plantarflexion strength of the toes. The paper grip test may be a useful screening tool to detect toe weakness in the clinical setting.

Adult↗

PubMedDate not supplied

The impact of hand dominance and ulnar and median nerve impairment on strength and basic daily activities.

The authors sought to determine the impact of hand dominance and its relation to function among ulnar alone and combined ulnar and median nerve lesions in leprosy patients. The study sample consisted of 62 persons affected with leprosy (mean age 36.1 years) who were either suffering from ulnar nerve lesions alone (34 patients) or combined ulnar and median lesions (28 patients). The data from the earlier work of this institution with normal hands in the adjacent rural uninvolved population were taken as controls. Grip, pulp-to-pulp, lateral, and three-jaw-chuck pinch strengths were measured using a hydraulic hand dynamometer and a pinch gauge. Basic daily activities were assessed using the battery developed at Karigiri. Means, standard errors, correlations, and t-tests were used in the analyses. The overall difference between grip and pinch strength measurements in both dominant and nondominant hands was 40% less than those in normal hands if the ulnar nerve alone was involved. If impairment of this nerve was combined with that of the median nerve, the overall difference in strength measurements increased to 51%. The hand strength of the dominant side was statistically significant between single and two nerves for pulp-to-pulp pinch (p = 0.019). No other strength tests produced statistically significantly results related to hand dominance (grip strength, lateral, chuck pinch) with either one or two nerve involvement. To observe differences in basic daily activities, scores were compared to Karigiri norms. The bilateral basic daily activities score was impaired by 45% compared with norms with only ulnar nerve involvement and by 59% with ulnar and median nerve involvement. The different pinch strengths related to basic daily activities was not significantly affected in nondominant hands, whether it was ulnar alone or combined ulnar and median nerve lesions. In this population diagnosed with leprosy, ulnar nerve impairment at the level of the elbow reduced the grip and pinch strengths and performance in basic daily activities by 40% and 45%, respectively. If combined with median nerve lesion at wrist level, the strengths and daily activity losses increased to 50% and 60%, respectively. There is no effect on grip strength either in ulnar or ulnar and median nerve injuries, irrespective of whether dominant or nondominant hands were involved. Different pinch strengths related to basic daily activities were significantly affected only in the dominant hand with involvement of these nerves.

Activities of Daily Living↗

PubMed2006

Concurrent strength and endurance training: from molecules to man.

Strength and endurance training produce widely diversified adaptations, with little overlap between them. Strength training typically results in increases in muscle mass and muscle strength. In contrast, endurance training induces increases in maximal oxygen uptake and metabolic adaptations that lead to an increased exercise capacity. In many sports, a combination of strength and endurance training is required to improve performance, but in some situations when strength and endurance training are performed simultaneously, a potential interference in strength development takes place, making such a combination seemingly incompatible. The phenomenon of concurrent training, or simultaneously training for strength and endurance, was first described in the scientific literature in 1980 by Robert C. Hickson, and although work that followed provided evidence for and against it, the interference effect seems to hold true in specific situations. At the molecular level, there seems to be an explanation for the interference of strength development during concurrent training; it is now clear that different forms of exercise induce antagonistic intracellular signaling mechanisms that, in turn, could have a negative impact on the muscle's adaptive response to this particular form of training. That is, activation of AMPK by endurance exercise may inhibit signaling to the protein-synthesis machinery by inhibiting the activity of mTOR and its downstream targets. The purpose of this review is to briefly describe the problem of concurrent strength and endurance training and to examine new data highlighting potential molecular mechanisms that may help explain the inhibition of strength development when strength and endurance training are performed simultaneously.

Adaptation, Physiological↗

PubMed2004

Human pulling strengths in different conditions of exertion.

This study tested 29 young Taiwanese men and 31 young Taiwanese women to examine the effects of pulling type (one-handed and two-handed) and height (48 cm, 84 cm, 120 cm, and 156 cm) on maximum horizontal isometric pulling strengths. Analysis showed differences in pulling strength between one-handed and two-handed efforts were surprisingly small for free pulling postures. The pulling strength decreased significantly with pulling height. The highest pulling strength was approximately two to three fold the lowest pulling strength across the four pulling heights. The women's pulling strength was approximately 59% to 67% of men's pulling strength. The test-retest correlations for pulling strength were satisfactory. The correlations between pulling strength and subjects' anthropometry were not sufficiently high to justify the prediction of strength. Most correlations between strengths in any two different pulling conditions were high and significant.

Adult↗

PubMed2001

Shear strength of dentin and dentin bonded composites.

PURPOSE: The objective of this study was to compare the shear strength of dentin with the shear strength of dentin bonded composites, and to determine how variables such as composite strength and blade width used during shear testing influence shear strength values. MATERIALS AND METHODS: Dentin test samples (n = 36) were made by milling the anatomical molar crowns to a shape similar to a composite rod bonded to a flat dentin surface. Dentin bonding was accomplished by bonding composites to flat dentin surfaces (n = 72) using Scotchbond MP and Z100 (n = 36) or Silux Plus (n = 36) composites. Shear testing was conducted using a guillotine-like device with a flat blade embracing half the dentin or composite cylinders. The blade thickness was either 0.25, 0.5, 0.75, 1.0, 1.25, or 1.50 mm. Six samples per material and blade thickness were tested. In addition to the above study, the bond strength of Z100 (n = 6) and Silux (n = 6) bonded with Scotchbond MP and tested with an orthodontic edgewire loop were also tested and compared with the bond strength of the Z100 and Silux samples tested with the 0.5 thick blade. All shear testing was done at a load rate of 0.5 mm/min. The results were analyzed using ANOVA and Duncan's multiple range test. RESULTS: The shear strength values when tested with the blades were: dentin = 39.7 +/- 13.0 MPa, Z100 = 29.3 +/- 7.2 MPa, and Silux = 21.1 +/- 4.9 MPa; each group had significantly different values (p < 0.05). The blade thickness had no significant effect on strength (p = 0.471). Comparing the 0.5-mm-wide blade with the edge wire (width = 0.45 mm) revealed a significant difference (p = 0.0014) favoring the blade. Z100 performed better than Silux (p = 0.0014). CONCLUSION: The shear strength of the tested bonding agent is significantly lower than the shear strength of dentin. The shear strength depends on testing method (blade vs loop) and composite material.

Analysis of Variance↗

PubMed2006

Effect of acid etching time and a self-etching adhesive on the shear bond strength of composite resin to porcelain.

UNLABELLED: PURPOSE The purpose of this study was to evaluate the effect of different acid etching times with 9.6% hydrofluoric acid gel and two adhesive systems on shear bond strengths of resin composite to porcelain. MATERIALS AND METHODS: Ninety-eight 7 x 7 x 2 mm feldspathic porcelain blocks (VMK 95, Vita) were prepared. The specimens were divided into 7 groups: 1 control (no surface treatment) and 6 groups acid etched with 9.6% hydrofluoric acid gel for different etching times, including 30 s, 30+30 s, 60 s, 60+60 s, 120 s, and 180 s. Each of the etching time groups was divided into two bonding agent (Single Bond, AdheSE) subgroups (n = 7). Microhybrid composite (Filtek Z250) was condensed using a teflon mold and light polymerized for 20 s on the porcelain specimens. The prepared specimens were then stored in distilled water at 37 degrees C for 24 h before mechanical testing. Shear testing of all groups was performed on a universal testing machine (Lloyd LRX) at a crosshead speed of 0.5 mm/min. The bond strength data were analyzed with two-way ANOVA. The means were compared using the Tukey HSD test (alpha = 0.05). RESULTS: Acid etching time and bonding agent statistically significantly influenced bond strength (p < 0.05). In the Single Bond group, the bond strengths between group 0 (10.48 MPa) and Group 30 (11.17 MPa) did not differ significantly, with these groups exhibiting the lowest bond strength values. The highest bond strength in Single Bond group was observed in group 120 (15.07 MPa) and group 60+60 (15.42 MPa), which did not differ significantly from each other. In the AdheSE group, the bond strengths of group 0 (9.33 MPa) and group 30 (9.49 MPa) did not differ significantly, and these groups exhibited the lowest bond strength values. The highest bond strengths in the AdheSE subgroup were observed in group 120 (14.84 MPa) and group 60+60 (14.96 MPa), which were not significantly different. Comparing the two different adhesive systems, Single Bond exhibited higher bond strength values than did the self-etching adhesive AdheSE. CONCLUSIONS: Acid etching of porcelain with 9.6% hydrofluoric acid gel for 120 s provided adequate bond strength for composite repair with a microhybrid composite. When a porcelain restoration is repaired with composite, Single Bond adhesive should be preferred to the AdheSE self-etching adhesive system.

Acid Etching, Dental↗