Hiroto Hyakutake

Three-dimensional analysis of the pharyngeal airway morphology in growing Japanese girls with and without cleft lip and palate

INTRODUCTION We evaluated the 3-dimensional craniofacial skeletal and pharyngeal airway morphology in growing patients with and without cleft lip and palate. METHODS Our juvenile subjects consisted of 34 girls (ages, 9-12 years); 15 had cleft lip and palate, and 19 did not. The adolescent subjects consisted of 32 girls (ages, 13-17 years); 14 had cleft lip and palate, and 18 did not. Each subject was examined with cone-beam computed tomography. The dimensions of the craniofacial skeleton and pharyngeal airway were measured. The Scheffé method of multiple comparisons was used to identify relationships among skeletal and pharyngeal variables. RESULTS The pharyngeal airway and mandibular size variables did not differ significantly between the juvenile and adolescent cleft lip and palate groups. Significant differences were observed between each cleft lip and palate group and its corresponding control group. FHN-A, FHN-B, FH-NA, FH-NB, and Co-Me were significantly smaller in the cleft lip and palate groups than in the corresponding control groups. Anteroposterior and lateral widths, heights, and volumes of the superior oropharyngeal airway were significantly smaller in the adolescent cleft lip and palate group than in the adolescent controls. CONCLUSIONS The mandible and the oropharyngeal airway were larger in the adolescent controls than in the juvenile controls without cleft lip and palate, but there were no significant differences between the adolescent and juvenile patients with cleft lip and palate.

An asymptotically optimal fixed-width confidence interval for the difference of two normal means

We consider the problem of providing a fixed width confidence interval for the difference of two normal means when the variances are unknown and unequal. We propose a two-stage procedure that differs from those of Chapman (1950) and Ghosll (1975). The procedure provides the desired confidence, subject to the restriction on the width, for certain values of the design parameter h. Values of h are given by the Monte Carlo rnethod for various combinations of first stage sample size and confidence level. Finally, it is shown that the procedure is asymptotically more efficient than those of Chapmail and Ghosh with respect to total sample size, as the width of the interval approaches zero.

Maximum principal strain as a criterion for prediction of orthodontic mini-implants failure in subject-specific finite element models

OBJECTIVE To investigate the most reliable stress or strain parameters in subject-specific finite element (FE) models to predict success or failure of orthodontic mini-implants (OMIs). MATERIALS AND METHODS Subject-specific FE analysis was applied to 28 OMIs used for anchorage. Each model was developed using two computed tomography data sets, the first taken before OMI placement and the second taken immediately after placement. Of the 28 OMIs, 6 failed during the first 5 months, and 22 were successful. The bone compartment was divided into four zones in the FE models, and peak stress and strain parameters were calculated for each. Logistic regression of the failure (vs success) of OMIs on the stress and strain parameters in the models was conducted to verify the ability of these parameters to predict OMI failure. RESULTS Failure was significantly dependent on principal strain parameters rather than stress parameters. Peak maximum principal strain in the bone 0.5 to 1 mm from the OMI surface was the best predictor of failure (R(2) = 0.8151). CONCLUSIONS We propose the use of the maximum principal strain as a criterion for predicting OMI failure in FE models.

Fixed-size confidence regions for the multinormal mean in an intraclass correlation model

SYNOPTIC ABSTRACTThe problem of constructing fixed-size confidence regions for estimating the mean vector of a multivariate normal distribution is considered when the covariance matrix has the intraclass correlation coefficient. Two-stage procedure and purely sequential procedure are proposed. In order to apply these procedures, an asymptotic approximation to a distribution is used.

On a General Selection Procedure for Multivariate Normal Populations: Asymptotic Approximation to Constants

SYNOPTIC ABSTRACTA general treatment for the problem of selecting the best (with respect to mean vector) from several multivariate normal populations was previously derived, using a two-stage sampling scheme, when covariance matrices are unknown. This paper gives an asymptotic approximation to a distribution needed to determine the sample sizes in that general treatment. The asymptotic formula for percentage points is presented, based on which numerical tables are given.

Relationship between the stability of muscle activity in the masseter muscle and craniofacial morphology

Abstract Purpose The stability of muscle activity is considered to be an important functional characteristic of masticatory muscle in relation to craniofacial morphology. The purpose of this study was to investigate whether the stability of masseter activity can be considered as a factor related to craniofacial morphology. Materials and methods Data were obtained from 25 healthy Japanese volunteers (25 males, 24.7 years old) and 65 Japanese orthodontic patients (34 males and 31 females, 23.2 years old). Electromyography signals were taken from the masseter muscle under instructions to perform 10%, 20%, 30%, 40%, and 50% of maximal voluntary clenching for 6 s 10 times. The standard deviation (SD) of median frequency of the last 4 s of the 6-s sampling period was calculated on each power spectrum. The stability index (SI) was obtained by averaging 10 repetitions of SD as functional parameters. Eight angular and eight linear cephalometric variables were measured as morphological parameters. Pearsons correlation coefficient was calculated to determine the correlation between cephalometric parameters and the SI in 25 volunteers. Regression analysis was conducted in 65 orthodontic patients. Results The SI was negatively correlated with interincisal angle, anterior facial height, anterior lower facial height, size of mandible, and maxillary and mandibular molar heights and positively correlated with inclination of the mandibular incisor to the mandibular plane. The correlation between the SI and mandibular length was confirmed using different subjects. Conclusion The stability of masseter muscle activity could be an important factor related to facial height and mandible size.

Three-dimensional dynamic evaluation of a posed smile in normal occlusion and Class II malocclusion

Abstract Purpose The purpose of this study was to quantify the three-dimensional movements of the lips during a posed smile and to verify the differences in the dynamic characteristics among normal occlusion and Class II malocclusion. Materials and methods The subjects included 30 healthy female volunteers with normal occlusion, 23 healthy female volunteers with dentoalveolar Class II malocclusion, and 20 adult female patients with skeletal Class II malocclusion. The three-dimensional measurements of the lips during a posed smile were generated using video-based tracking with three high-speed cameras. Eight landmarks on the lips were used to track lip movement. The Scheffé method of multiple comparisons was used to identify significant differences among the normal occlusion and both Class II groups. Results The lower lip point moved significantly faster and farther backward in the skeletal Class II group compared with the other groups. The upper quarter point in the skeletal Class II group in the posed smile was significantly more medial than in the other groups. The vertical movements of the cheilion point of the normal occlusion group were faster than those in the other groups. Conclusion Three-dimensional dynamic evaluation of posed smiles showed significant differences in the characteristics of lip movement between the normal occlusion and Class II subjects.

Pairwise comparisons for parallel profile models with mixed effects

ABSTRACT There are several linear and nonlinear models for analyzing repeated measurements. The mean response for an individual depends on the regression parameters specific to that individual. One of the simple forms is the sum of vectors of fixed parameters and random effects. When the models with mixed effects for several groups are parallel, pairwise comparisons of level differences are considered. For the comparisons, approximate simultaneous confidence intervals are given.

Multiple comparisons with a control in nonlinear repeated measurements

SYNOPTIC ABSTRACT It is interesting to compare specified functions of parameters in nonlinear repeated measurements. The specified function would be the maximum (or minimum) values of a nonlinear model. The functions of parameters in a nonlinear model for repeated measurement data are compared by simultaneous confidence intervals of the difference between each treatment effect with a control. The confidence intervals are approximated by the first order Taylor expansion.

Selection of the best normal population: a new exact solution, asymptotically optimal when k = 2

SYNOPTIC ABSTRACT The problem we deal with in this paper was first stated in 1954 in Bechhofers pioneering paper in ranking and selection. Namely, there are k (2 or more) normal populations with all parameters unknown, and the goal is to select one population which has the largest mean. Despite much interest (and a number of failed attempts to solve this problem in the literature), the first solution came in a 1975 paper by Dudewicz and Dalal. A slightly different solution followed in a 1978 paper by Rinott. While there has been other work on the problem, to date these are the only exact solutions (all other “solutions” are either heuristic or asymptotic only). It has been recognized for some time that the available exact solutions do not (asymptotically) allocate sample size in a way which corresponds to what is known to be optimal when the variances are known. In this paper we give a new, third, exact solution to the problem. The new solution is asymptotically optimal in the case when there are two populations. In an example on a real data set, we illustrate the procedure and see that it would save 7% of the sample size in that example (and asymptotically saves 6% in that example).