Validity and Reproducibility of an Incremental Sit-To-Stand Exercise Test for Evaluating Anaerobic Threshold in Young,Healthy Individuals

Sit-to-stand exercise (STS) is a common activity of daily living. The objectives of the present study were: 1) to assess the validity of aerobic fitness measurements based on anaerobic thresholds (ATs), during incremental sit-to-stand exercise (ISTS) with and without arm support compared with an incremental cycle-ergometer (CE) test; and 2) to examine the reproducibility of the AT measured during the ISTSs. Twenty-six healthy individuals randomly performed the ISTS and CE test. Oxygen uptakes at the AT (AT-VO₂) and heart rate at the AT (AT-HR) were determined during the ISTSs and CE test, and repeated-measures analyses of variance and Tukey’s post-hoc test were used to evaluate the differences between these variables. Pearson correlation coefficients were used to assess the strength of the relationship between AT-VO₂ and AT-HR during the ISTSs and CE test. Data analysis yielded the following correlations: AT-VO₂ during the ISTS with arm support and the CE test, r = 0.77 (p < 0.05); AT-VO₂ during the ISTS without arm support and the CE test, r = 0.70 (p < 0.05); AT-HR during the ISTS with arm support and the CE test, r = 0.80 (p < 0.05); and AT-HR during the ISTS without arm support and the CE test, r = 0.66 (p < 0.05). The AT-VO₂ values during the ISTS with arm support (18.5 ± 1.9 mL·min^-1·kg^-1) and the CE test (18.4 ± 1.8 mL·min^-1·kg^-1) were significantly higher than those during the ISTS without arm support (16.6 ± 1.8 mL·min^-1·kg^-1; p < 0.05). The AT-HR values during the ISTS with arm support (126 ± 10 bpm) and the CE test (126 ± 13 bpm) were significantly higher than those during the ISTS without arm support (119 ± 9 bpm; p < 0.05). The ISTS with arm support may provide a cardiopulmonary function load equivalent to the CE test; therefore, it is a potentially valid test for evaluating AT-VO2 and AT-HR in healthy, young adults.

Key points

• The ISTS is a simple test that varies only according to the frequency of standing up, and requires only a small space and a chair.
• The ISTS with arm support is valid and reproducible, and is a safe test for evaluating AT in healthy young adults.
• For evaluating the AT, the ISTS may serve as a valid alternative to conventional CPX, using either a cycle ergometer or treadmill, in cases where the latter methods are difficult to implement.

Key words: Sit-to-stand, cycle ergometer, anaerobic threshold, correlations, reproducibility, validity     

A comparative study of unilateral dislocated mandibular condyle fractures in the rabbit.

PURPOSE: The purpose of this study was to clarify the influence of patients age and the degree of dislocation on the healing of mandibular condyle fractures. MATERIAL AND METHODS: Sixty-two Japanese white rabbits (30 adolescent and 30 adult ones) were used. They underwent unilateral condylar neck osteotomy. The proximal fragments were positioned differently. In group I animals, the fragments were reduced into the original position, in group II animals the small fragment was dislocated 55-90 degrees to the ramus. In group III animals the proximal fragment was dislocated 135 degrees to the ramus. Gross and microscopic assessment was performed 4, 6, 8, 12 and 24 weeks postoperatively. RESULTS: In adolescent animals, complete healing of the fracture was observed, irrespective of the degree of dislocation. In the adult animals, there was complete healing of the fractures in groups I and II. In group III animals, there was a decrease of ramus height accompanied by some fibro-cartilaginous changes. CONCLUSION: Even in rabbits condylar deformation has been found following heavily dislocated artificial condylar fractures in adult animals. This result will help to decide for or against surgical treatment of condylar fractures in humans.     

An ultrastructural analysis of the prototype single-step adhesive applied on enamel and dentin surfaces

A new type of self-etching agent, the single-step adhesive, was developed. The purpose of this study was to investigate the difference in the ultrastructural features of enamel and dentin surfaces following application of the prototype single-step adhesive (EXM618, 3M, MN, USA). Extracted caries-free human premolars were used in this study. Occlusal enamels of teeth--to be used as cut surface specimens--were removed perpendicular to the long axis of the specimens. The mesial and distal surfaces of these teeth, on the other hand, were used as uncut surface specimens in the test. In addition, Mega Bond (Kuraray Medical Inc., Tokyo, Japan) and Xeno CFII Bond (Dentsply Sankin, Tokyo, Japan) were used as controls. After covering half of the tooth surfaces with nail varnish (for control), the other half of each surface was treated with one of the three test adhesives--EXM618, Mega Bond, or Xeno CFII Bond--according to the manufacturer's recommendations. Conditioned enamel and dentin surfaces (i.e., decalcified depth and rugged surface) were observed with a scanning confocal laser microscope (SCLM 1100, Olympus, Tokyo, Japan; henceforth abbreviated as SCLM). Based on the findings of this study, the prototype single-step adhesive EXM618 appears to be suitable for use in dental clinics.     

Effect of overglazed and polished surface finishes on the compressive fracture strength of machinable ceramic materials

Controversy prevails over the effect of overglazing on the fracture strength of ceramic materials. Therefore, the effects of different surface finishes on the compressive fracture strength of machinable ceramic materials were investigated in this study. Plates prepared from four commercial brands of ceramic materials were either surface-polished or overglazed (n=10 per ceramic material for each surface finish), and bonded to flat surfaces of human dentin using a resin cement. Loads at failure were determined and statistically analyzed using two-way ANOVA and Bonferroni test. Although no statistical differences in load value were detected between polished and overglazed groups (p>0.05), the fracture load of Vita Mark II was significantly lower than those of ProCAD and IPS Empress CAD, whereas that of IPS e.max CAD was significantly higher than the latter two ceramic materials (p<0.05). It was concluded that overglazed and polished surfaces produced similar compressive fracture strengths irrespective of the machinable ceramic material tested, and that fracture strength was material-dependent.     

Effect of a desensitizing agent containing glutaraldehyde and HEMA on bond strength to Er:YAG laser-irradiated dentine

OBJECTIVES: The aim of this study was to investigate whether a desensitizing agent (GLUMA Desensitizer) containing glutaraldehyde and HEMA improved the bond strength and bonding durability of a self-etching primer adhesive to Er:YAG-irradiated dentine. METHOD: Dentine of 120 human molars was exposed by wet grinding on SiC paper for bond strength testing. Thirty specimens each were allocated to the following treatment groups: (1) control; (2) Er:YAG laser irradiation; (3) Er:YAG laser irradiation followed by application of GLUMA Desensitizer; (4) Er:YAG laser irradiation followed by application of GLUMA Desensitizer and 10s rinsing with water. Composite cylinders were bonded to the dentine surfaces with a self-etching priming adhesive system. Tensile bond strengths (TBS) of 10 specimens of each treatment group were measured after 24-h water storage, 6 months water storage and 12 months water storage, respectively, and the failure modes were analyzed. TBS data were statistically treated by two-way ANOVA and Fisher's PLSD test at a significance level of p<0.05. RESULTS: TBSs for the GLUMA-non rinse and GLUMA-rinse groups were significantly higher than for the laser group at 24 h and 12 months. Specimens from the Er:YAG-irradiated dentine group had significantly lower bond strengths than the control group at each storage time. All control specimens showed cohesive fractures in resin close to the bonding interface whereas the Er:YAG laser-irradiated groups showed both dentine cohesive, resin cohesive and dentine-resin mixed failures. CONCLUSION: Application of GLUMA Desensitizer to Er:YAG-irradiated dentine increases the bond strength and durability of the self-etching priming adhesive used.