bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of apolipoprotein(a)-, apolipoprotein E-, and apolipoprotein A4- polymorphisms on quantitative lipoprotein(a) concentrations
Authors: Boomsma DI , de Knijff P , Kaptein A , Labeur C , Martin NG , Havekes LM , Princen HMG
Published: May 2007

The effects of apolipoprotein (a), apolipoprotein-E, and apolipoprotein-A4 isoforms on quantitative lipoprotein(a) [Lp(a)] levels were assessed in a sample of 142 Dutch families consisting of two parents and their adolescent twin offspring. A total heritability of 95% was estimated for plasma Lp(a) concentrations. The largest part of this heritability was due to the apo(a) locus which explained 61% of the total variance in Lp(a) levels. The pattern of familial correlations for the residual part of the Lp(a) variance that could not be attributed to the apo(a) isoforms, suggested genetic influences on the residual variance. We addressed the question whether this residual genetic variance could be ascribed to the apoE or the apoA4 locus. A simultaneous analysis of all three loci showed that both the apoE and the apoA4 polymorphism did not contribute significantly to Lp(a) variation. Twin Research (2000) 3, 152–158.
Defining discordance in twin studies of risk and protective factors for late life disorders
Authors: Gatz Margaret , Pedersen Nancy L , Crowe Michael , Fiske Amy
Published: May 2007

In studies that employ matched pair analysis to identify environmental exposures important for a disorder, criteria for discordant pairs are seldom discussed. Yet several assumptions concerning the definition of discordancy may have considerable influence over what results are found. Problems are exacerbated when age of onset for a disorder is late in life. We propose a new set of criteria for defining discordant pairs in studies of dementia, taking into account duration of discordance and competing causes of mortality, and evaluate the consequences of choosing alternative definitions of discordancy. Twin Research (2000) 3, 159–164.
Structured latent growth curves for twin data
Authors: Neale Michael C , McArdle John J
Published: May 2007

We describe methods to fit structured latent growth curves to data from MZ and DZ twins. The well-known Gompertz, logistic and exponential curves may be written as a function of three components – asymptote, initial value, and rate of change. These components are allowed to vary and covary within individuals in a structured latent growth model. Such models are highly economical, requiring a small number of parameters to describe covariation across many occasions of measurement. We extend these methods to analyse longitudinal data from MZ and DZ twins and focus on the estimation of genetic and environmental variation and covariation in each of the asymptote, initial and rate of growth factors. For illustration, the models are fitted to longitudinal Bayley Infant Mental Development Scale data published by McArdle (1986). In these data, all three components of growth appear strongly familial with the majority of variance associated with the shared environment; differences between the models were not great. Occasion-specific residual factors not associated with the curve components account for approximately 40% of variance of which a significant proportion is additive genetic. Though the growth curve model fit less well than some others, they make restrictive, falsifiable predictions about the mean, variance and twin covariance of other (not yet measured) occasions of measurement. Twin Research (2000) 3, 165–177.
Cross-cultural adaptation and preliminary validation of a zygosity determination questionnaire for twins in Sri Lanka
Authors: Sumathipala A , De Silva N , Siribaddana SH , Abeysingha MRN , Fernando DJS
Published: May 2007

We report the process of adaptation into Sinhala of a questionnaire given to mothers of twins to determine zygosity. Adaptation and validation was carried out in three stages. Firstly, we used a nominal group to translate the English version and to assess the extent of agreement (consensus measurement) on the appropriateness of the translation and resolve disagreement (consensus development). Secondly we used a qualitative interview with 25 mothers of twins. The three main stems of the translated questionnaire were used as a semi-structured interview, and the responses noted verbatim. These were categorised and analysed, and the translated full questionnaire was then presented as closed questions with fixed choice responses. The categorised responses generated during the qualitative interview were compared with the responses to the fixed choices in the full questionnaire. The third stage was the appraisal of the questionnaire by 17 bilingual parents of twins. The source and translated version of the questionnaire were given to them at least 3 days apart. The responses were rated and the total scores were computed to determine the zygosity. This step was carried out to measure the validity and reliability of the Sinhala version. A perfect correlation between the original and adapted version was obtained, with a kappa of 1. The results suggest that the Sinhala version of the questionnaire is conceptually equivalent to the original questionnaire. Comparison of the zygosity determination by using this adapted questionnaire with results from analysis of genetic markers on Sri Lankan twins is needed for final validation of the translated questionnaire. Twin Research (2000) 3, 205–212.
Parents' and teachers' ratings of problem behaviours in children: genetic and contrast effects
Authors: Kuntsi Jonna , Gayán Javier , Stevenson Jim
Published: May 2007

We obtained ratings on the Conners' scales from teachers (CTRS-28) and parents (CPRS-48) for 61 monozygotic and 64 dizygotic twin pairs, aged between 7 and 11 years. Model-fitting analyses were carried out to estimate the extent of genetic and environmental influences on problem behaviours, and to explore possible contrast effects in ratings by parents and teachers. Confirming previous findings with other measures, there was evidence of moderate to strong genetic effects on a range of problem behaviours. Parents' ratings on the Anxiety, Impulsive-Hyperactive and Learning Problem sub-scales showed significant evidence of contrast effects. There was no evidence of such rater bias or competitive sibling interaction effects in ratings by teachers, or in parents' ratings on the Conduct Problem and Psychosomatic sub-scales. Twin Research (2000) 3, 251–258.
Imprinting of Genes and the Barker Hypothesis
Authors: Young Lorraine E.
Published: May 2007

Several common adult diseases appear to be related to impaired fetal growth and this may be caused either by nutritional inadequacies at particular stages of pregnancy or by variation in alleles at specific growth loci. Little is known about the genes involved in the underlying mechanism. This review proposes that at least some of the effects have their origins at imprinted loci, genes that are unusual because they are expressed from only one parental allele. Many imprinted genes are crucial for fetal growth and determine birthweight. They can be disrupted in the early embryo by environmental influences and these disruptions can be inherited through many cell cycles into adult tissues. Their disruption can affect specific organs during fetal development and disruption could affect adult disease in a variety of direct and indirect means. Imprinted genes may be particularly vulnerable to disruption as they are functionally haploid and their expression is regulated by different means from the rest of the genome. Thus many imprinted genes provide plausible candidates for programming adult disease and warrant further study in this context.
Potential Bias Regarding Birth Weight in Historical and Contemporary Twin Data Bases
Authors: Sadrzadeh Sheda , Treloar Susan A. , van Baal G. Caroline M. , Lambalk Cornelis B.
Published: May 2007

In this study we examine the hypothesis that monozygotic (MZ) twins in historical databases are less discordant for birth weight due to negative selection of severely discordant MZ twins. Furthermore, we test the hypothesis that MZ twins are less discordant for birth weight when comparing a volunteer based twin registry with a population based twin registry, due to selective registration. Data were available on 3927 twin pairs from the volunteer Australian Twin Registry born before 1964, 3059 volunteer twin pairs from the Netherlands Twin Register born 1987–1989 and 454 Belgian twin pairs from The East Flanders Prospective Twin Survey born 1987–1989. Intrapair relative birth weight differences (RBWD) were computed for MZ and dizygotic (DZ) twins from each twin registry. Comparing birth weight differences between MZ and DZ twins provides support for the hypothesis that MZ twins are subject to a negative selection in historical databases. Furthermore, Australian MZ twins have a lower RBWD compared to Dutch MZ twins when corrected for the RBWD of Australian and Dutch DZ twins, indicating circumstances which only affect MZ twins. Our hypothesis that MZ twins are less discordant for birth weight in a volunteer based twin registry compared to a population based twin registry had to be rejected. We suggest that investigators using historical databases to test the fetal origins hypothesis should be aware of this increased likelihood of selective exclusion of individuals with extreme morphometric parameters at time of birth.
Glucose and Insulin Metabolism in Twins: Influence of Zygosity and Birth Weight
Authors: Poulsen Pernille , Vaag Allan
Published: May 2007

Several epidemiological and metabolic studies have demonstrated an impact of the intrauterine environment on the development of disease in adult life, including Type 2 diabetes and glucose intolerance. Our finding of lower birth weights among monozygotic diabetic twins compared to their non-diabetic genetically identical co-twins confirms this association and, furthermore, eliminates the possibility that the association could be explained solely by common genes leading to both impaired intrauterine growth and increased risk of Type 2 diabetes. Due to an often shared placenta monozygotic twins may experience a more adverse intrauterine environment compared to dizygotic twins and may therefore be more prone to develop various metabolic abnormalities. Our findings of a higher glucose and insulin profile after oral glucose ingestion, and recently lower insulin-stimulated glucose uptake — indicating glucose intolerance and insulin resistance — among monozygotic compared to dizygotic twins may to some extent question the validity of classical twin studies in diabetes research where equal environmental influences in monozygotic and dizygotic twins is assumed. The potential role of an adverse intrauterine environment in causing Type 2 diabetes in humans, may to some degree alter our conception of the twin model in diabetes research including the interpretation of aetiological conclusions reached in previous classical twin studies of diabetes. However, our present knowledge is far too insufficient to discard the results from classical twin studies concerning the relative role of genes versus environment for the development of diabetes and its metabolic effects.
Genetic and Non-Genetic Factors Affecting Birth-Weight and Adult Body Mass Index
Authors: Whitfield John B. , Treloar Susan A. , Zhu Gu , Martin Nicholas G.
Published: May 2007

Birthweight affects neonatal mortality and morbidity and has been used as a marker of foetal undernutrition in studies of prenatal effects on adult characteristics. It is potentially influenced by genetic and environmental influences on the mother, and effects of foetal genotype, which is partially derived from the maternal genotype. Interpretations of variation in birthweight and associated characteristics as being due to prenatal environment ignore other possible modes of materno-foetal transmission. Subjects were adult twins recruited through the Australian Twin Registry, aged 17 to 87 years, and the sample comprised 1820 men and 4048 women. Twins reported their own birthweight as part of a health questionnaire. Body Mass Index (BMI) was calculated from self-reports of height and weight. Correlations between co-twins' birthweights were high for both monozygotic (r = 0.77) and dizygotic (r = 0.67) pairs, leading to substantial estimates of shared environmental effects (56% of variance) with significant additive genetic (23%) and non-shared environmental (21%) components. Adult BMI was mainly influenced by genetic factors, both additive (36% of variance) and nonadditive (35%). The correlation between birthweight and BMI was positive, in that heavier babies became on average more obese adults. A bivariate model of birthweight and adult BMI showed significant positive genetic (rg = 0.16, p = 0.005) and environmental (re = 0.08, p = 0.000011) correlations. Intra-uterine environmental or perinatal influences shared by cotwins exercise a strong influence on birthweight, but the factors which affect both birthweight and adult BMI are partly genetic and partly non-shared environmental.
Perinatal Risk Factors for Hay Fever — A Study Among 2550 Finnish Twin Families
Authors: Räsänen Maija , Kaprio Jaakko , Laitinen Tarja , Winter Torsten , Koskenvuo Markku , Laitinen Lauri A.
Published: May 2007

Previous studies have suggested that perinatal factors influence the risk for asthma but population studies on perinatal factors and risk for hay fever are few. We studied the effect of perinatal factors on the risk for hay fever among adolescent twins by a questionnaire study involving five consecutive nation-wide birth cohorts of 16-year-old twins and their parents. The risk for parent-reported, doctor-diagnosed hay fever in the adolescents associated with several perinatal characteristics was assessed with logistic regression analysis among individuals and by a discordant pair analysis. In the univariate analysis of the birth factors, the risk for hay fever increased with increasing birth weight (pfor trend = 0.048, OR for those ≥ 3000g 1.35, 95% CI 0.91–2.02 compared to those < 2000g) and gestational age (pfor trend = 0.04, OR for those born after 40 weeks of gestation 2.24, 95% CI 1.03–4.86, compared to those born before 33 weeks of gestation) and was lower in those subjects hospitalised in the neonatal period (OR 0.74, 95% CI 0.58–0.93). Because of significant interactions between parental hay fever status and birth factors (ponderal index,p= 0.03 and maternal agep= 0.04), stratified analysis were performed. The positive association between birth weight and hay fever was most obvious among adolescents with no parental history of hay fever (pfor trend = 0.03). Similar, though not significant, trends were found with other birth factors among these families, whereas no such trend was found among adolescents with parental hay fever, suggesting that gestational maturity increases the risk for hay fever in the absence of genetic predisposition. However, of the perinatal factors only neonatal hospitalisation (OR 0.75, 95% CI 0.59–0.96) remained a significant risk factor for the development of hay fever, when adjusted for non-perinatal factors.
Birthweight and Body Mass Index in Young Adulthood: The Swedish Young Male Twins Study
Authors: Johansson Malin , Rasmussen Finn
Published: May 2007

Many studies have found an inverse association between fetal growth and cardiovascular disease related to the metabolic syndrome in adulthood. Nevertheless, the relative importance of genetics and the intrauterine environment remain unclear. The objective of the study was to test the fetal origins hypothesis and the fetal insulin resistance hypothesis by studying the impact of fetal growth on Body Mass Index (BMI) in young adulthood. In a nationwide cohort study, the Swedish Medical Birth Register for the years 1973–1979 was linked with the Military Service Conscription Register for 1990–1999. In 1998 a questionnaire was mailed to all male twins, included in the two registers, who were alive and still resident in Sweden. The study covers the 923 male twin pairs for which full data were available. Mixed linear models were used to estimate within-pair and between-pair differences in birthweight and their relations to BMI. A weak positive association was found among the monozygotic twins for the withinpair difference in birthweight and BMI. No significant association was found among the monozygotic for the between-pair difference in birthweight and BMI. No significant associations were found for dizygotic twins. These findings do not seem to support either the fetal programming hypothesis or the fetal insulin resistance hypothesis.
Responses of Neurons in Primary Visual Cortex to Transient Changes in Local Contrast and Luminance
Authors: Geisler Wilson S. , Albrecht Duane G. , Crane Alison M.
Published: May 2007

During normal saccadic inspection of natural images, the receptive fields of cortical neurons are bombarded with frequent simultaneous changes in local mean luminance and contrast, yet there have been no systematic studies of how cortical neurons respond to such stimulation. The responses of single neurons in the primary visual cortex of the cat were measured for 200 ms presentations of sine-wave gratings confined to the conventional receptive field. Both local mean luminance and contrast were parametrically and randomly varied over the 1–1.5 log unit ranges that are typical of natural images. We find that responses are strongly modulated by both the local mean luminance and contrast, but in an approximately separable manner: the contrast response function is approximately invariant except for a scale factor that depends on the local mean luminance. The shape of the temporal response profiles were found to be approximately invariant with contrast, but were strongly affected by the local mean luminance. The results suggest that most, if not all, cortical neurons carry substantial local luminance information.
β-Arrestin2 and c-Src Regulate the Constitutive Activity and Recycling of μ Opioid Receptors in Dorsal Root Ganglion Neurons
Authors: Walwyn Wendy , Evans Christopher J. , Hales Tim G.
Published: May 2007

β-Arrestins bind to agonist-activated G-protein-coupled receptors regulating signaling events and initiating endocytosis. In β-arrestin2−/−(βarr2−/−) mice, a complex phenotype is observed that includes altered sensitivity to morphine. However, little is known of how β-arrestin2 affects μ receptor signaling. We investigated the coupling of μ receptors to voltage-gated Ca2+channels (VGCCs) in βarr2+/+and βarr2−/−dorsal root ganglion neurons. A lack of β-arrestin2 reduced the maximum inhibition of VGCCs by morphine and DAMGO (d-Ala2-N-Me-Phe4-glycol5-enkephalin) without affecting agonist potency, the onset of receptor desensitization, or the functional contribution of N-type VGCCs. The reduction in inhibition was accompanied by increased naltrexone-sensitive constitutive inhibitory coupling of μ receptors to VGCCs. Agonist-independent μ receptor inhibitory coupling was insensitive to CTAP (Cys-Tyr-d-Trp-Arg-Thr-Pen-Thr-NH2), a neutral antagonist that inhibited the inverse agonist action of naltrexone. These functional changes were accompanied by diminished constitutive recycling and increased cell-surface μ receptor expression in βarr2−/−compared with βarr2+/+neurons. Such changes could not be explained by the classical role of β-arrestins in agonist-induced endocytosis. The localization of the nonreceptor tyrosine kinase c-Src appeared disrupted in βarr2−/−neurons, and there was reduced activation of c-Src by DAMGO. Using the Src inhibitor PP2 [4-amino-5-(4-chlorophenyl)-(t-butyl)pyrazolo[3,4-d]pyrimidine], we demonstrated that defective Src signaling mimics the βarr2−/−cellular phenotype of reduced μ agonist efficacy, increased constitutive μ receptor activity, and reduced constitutive recycling. We propose that β-arrestin2 is required to target c-Src to constitutively active μ receptors, resulting in their internalization, providing another dimension to the complex role of β-arrestin2 and c-Src in G-protein-coupled receptor function.
Postnatal Generation of Neurons in the Ventrobasal Nucleus of the Rat Thalamus
Authors: Mooney Sandra M. , Miller Michael W.
Published: May 2007

Most CNS systems, including the trigeminal–somatosensory system, develop via a hierarchical order (from the periphery and up the neuraxis). We tested the hypothesis that development of the trigeminal system can proceed via a nonhierarchical mechanism (i.e., that neuronogenesis can occur postnatally). Preweanling rats were perfused, and brain sections were stained with cresyl violet or immunolabeled with NeuN (for neuronal counts), or processed for acetylcholinesterase (AChE) activity or p75 immunoreactivity [to identify boundaries of the ventrobasal nucleus (VB)]. Neuronal number decreased during the first postnatal week but increased 2.5-fold over the next 3 weeks. To determine whether this remarkable rise resulted from the generation of new neurons, preweanlings were given injections of bromodeoxyuridine (BrdU) on postnatal day 6 (P6) or P21. BrdU-positive VB cells were apparent on both days. Cumulative BrdU labeling showed that the cell cycle was 17.3 h on P6. Moreover, Ki-67, a protein elaborated throughout the cell cycle, was expressed by 25.8–29.3% of all VB cells on P6–P15, falling to 7.7% by P21. BrdU-positive VB cells coexpressed neuronal markers: NeuN, HuC/D, microtubule-associated protein 2, and a dextran placed in the somatosensory cortex. Note that postnatal neuronal generation was also evident in other thalamic nuclei (e.g., the lateral geniculate nucleus). Thus, the developing VB experiences two periods of neuronal generation. Prenatal neuronogenesis is part of hierarchical trigeminal–somatosensory development. Postnatal nonhierarchical neuronogenesis is intrathalamic and matches changes in neuromodulatory systems (exemplified by AChE activity and p75) and the arrival of corticothalamic afferents.
Differential Regulation of Endogenous N- and P/Q-Type Ca2+Channel Inactivation by Ca2+/Calmodulin Impacts on Their Ability to Support Exocytosis in Chromaffin Cells
Authors: Wykes Robert C. E. , Bauer Claudia S. , Khan Saeed U. , Weiss Jamie L. , Seward Elizabeth P.
Published: May 2007

P/Q-type (CaV2.1) and N-type (CaV2.2) Ca2+channels are critical to stimulus-secretion coupling in the nervous system; feedback regulation of these channels by Ca2+is therefore predicted to profoundly influence neurotransmission. Here we report divergent regulation of Ca2+-dependent inactivation (CDI) of native N- and P/Q-type Ca2+channels by calmodulin (CaM) in adult chromaffin cells. Robust CDI of N-type channels was observed in response to prolonged step depolarizations, as well as repetitive stimulation with either brief step depolarizations or action potential-like voltage stimuli. Adenoviral expression of Ca2+-insensitive calmodulin mutants eliminated CDI of N-type channels. This is the first demonstration of CaM-dependent CDI of a native N-type channel. CDI of P/Q-type channels was by comparison modest and insensitive to expression of CaM mutants. Cloning of the C terminus of the CaV2.1 α1 subunit from chromaffin cells revealed multiple splice variants lacking structural motifs required for CaM-dependent CDI. The physiological relevance of CDI on stimulus-coupled exocytosis was revealed by combining perforated-patch voltage-clamp recordings of pharmacologically isolated Ca2+currents with membrane capacitance measurements of exocytosis. Increasing stimulus intensity to invoke CDI resulted in a significant decrease in the exocytotic efficiency of N-type channels compared with P/Q-type channels. Our results reveal unexpected diversity in CaM regulation of native CaV2 channels and suggest that the ability of individual Ca2+channel subtypes to undergo CDI may be tailored by alternative splicing to meet the specific requirements of a particular cellular function.
Encoding of Movement Fragments in the Motor Cortex
Authors: Hatsopoulos Nicholas G. , Xu Qingqing , Amit Yali
Published: May 2007

Previous studies have suggested that complex movements can be elicited by electrical stimulation of the motor cortex. Most recording studies in the motor cortex, however, have investigated the encoding of time-independent features of movement such as direction, velocity, position, or force. Here, we show that single motor cortical neurons encode temporally evolving movement trajectories and not simply instantaneous movement parameters. We explicitly characterize the preferred trajectories of individual neurons using a simple exponential encoding model and demonstrate that temporally extended trajectories not only capture the tuning of motor cortical neurons more accurately, but can be used to decode the instantaneous movement direction with less error. These findings suggest that single motor cortical neurons encode whole movement fragments, which are temporally extensive and can be quite complex.
Excitatory GABA Action Is Essential for Morphological Maturation of Cortical NeuronsIn Vivo
Authors: Cancedda Laura , Fiumelli Hubert , Chen Karen , Poo Mu-ming
Published: May 2007

GABA exerts excitatory actions on embryonic and neonatal cortical neurons, but thein vivofunction of this GABA excitation is essentially unknown. Usingin uteroelectroporation, we eliminated the excitatory action of GABA in a subpopulation of rat ventricular progenitors and cortical neurons derived from these progenitors by premature expression of the Cl−transporter KCC2, as confirmed by the changes in the reversal potential of GABA-induced currents and the resting membrane potential after GABAAreceptor blockade. We found that radial migration to layer II/III of the somatosensory cortex of neurons derived from the transfected progenitors was not significantly affected, but their morphological maturation was markedly impaired. Furthermore, reducing neuronal excitability of cortical neuronsin vivoby overexpressing an inward-rectifying K+channel, which lowered the resting membrane potential, mimicked the effect of premature KCC2 expression. Thus, membrane depolarization caused by early GABA excitation is critical for morphological maturation of neonatal cortical neuronsin vivo.
Universal overconvergence of homogeneous expansions of harmonic functions
Authors: Gauthier Paul M. , Tamptse Innocent
Published: May 2007

On certain domains of Euclidean space, we establish the existence of harmonic functions, which are universal in the sense that their Taylor polynomials approximate all plausibly approximable functions in the complement of the domain.
A discrete universality theorem for general Dirichlet series
Authors: Macaitiene Renata
Published: May 2007

We prove a discrete universality theorem for functions given by general Dirichlet series, satisfying several conditions.
Universal Taylor series on open subsets of Rn
Authors: Costakis George , Marias M. , Nestoridis V.
Published: May 2007

In the case of the complex plane, several notions of universal Taylor series have been introduced, ([10, 2, 19, 20]). The purpose of the present article is to establish the existence of universal Taylor series of
Microscrew Anchorage in Skeletal Anterior Open-bite Treatment
Authors: Xun Chunlei , Zeng Xianglong , Wang Xing
Published: May 2007

Objective: To evaluate the effectiveness of miniscrew anchorage for intrusion of the posterior dentoalveolar region to correct skeletal open bite.

Materials and Methods: The study was comprised of 12 patients (aged 14.3 to 27.2 years; mean 18.7 years) with anterior open bites. All the patients presented a Class II skeletal pattern and excessive posterior growth. Self-drilling miniscrew implants were inserted into the posterior midpalatal area and the buccal alveolar bone between the lower molars. A transpalatal and a lingual arch were used to maintain the molars on each side in order to avoid overrotation during intrusion. A force of 150 g was applied to the microscrews on each side to intrude the posterior teeth. Lateral cephalograms of all 12 patients were taken preintrusion and immediately after completion of the intrusion. The cephalometric films were measured and compared.

Results: The results showed that the anterior open bites in 12 patients were all corrected in a mean of 6.8 months. Overbite increased by a mean of 4.2 mm (P < .001), from −2.2 mm in preintrusion to 2.0 mm in postintrusion. The maxillary and mandibular first molars were intruded for an average of 1.8 mm (P < .001) and 1.2 mm (P < .001), respectively. The mandibular plane angle was reduced by 2.3° (P < .001), which led to a counterclockwise rotation of the mandible with a significant decrease in the anterior facial heights (mean of 1.8 mm; P < .001).

Conclusion: Miniscrew anchorage has the advantages of being a simpler procedure, being minimally invasive, and requiring minimal patient cooperation.
Dental Arch Widths and Mandibular-Maxillary Base Width in Class III Malocclusions with Low, Average and High MP-SN Angles
Authors: Chen Fengshan , Terada Kazuto , Wu Liping , Saito Isao
Published: May 2007

Objective: To analyze the development of the dental arches and skeletal mandibular-maxillary bases in untreated Class III malocclusions with low averages and high mandibular plane angles in subjects aged 10 to 14.

Materials and Methods: The records of 50 untreated Japanese girls with Class III malocclusions at age 10 were selected from the files of patients pending orthodontic surgery. The patients included those with low (≤27°), average (27° through 37°) and high (>37°) mandibular plane angles. The maxillary skeletal base width, biantegonial width, and maxillary and mandibular intermolar width were determined on posteroanterior cephalograms obtained at annual intervals when subjects were between 10 and 14 years of age. The difference between the maxillary and mandibular intermolar width was also calculated and reported.

Results: All skeletal and dental transverse widths in the high-angle group were significantly smaller than those in the low-angle group (P < .05) from ages 10 to 14. On the other hand, the maxillary to mandibular molar difference was the same for the three groups (P > .05) at each age. The deviations in molar differences did increase from age 10 to age 14 in all three groups.

Conclusion: Mandibular plane angles might play a stronger role in the transverse skeletal growth of the maxilla and the mandible than the transverse dental growth of the maxilla and the mandible.
Long-term Stability of Orthodontic Treatment and Patient Satisfaction
Authors: Bondemark L. , Holm Anna-Karin , Hansen Ken , Axelsson Susanna , Mohlin Bengt , Brattstrom Viveka , Paulin Gunnar , Pietila Terttu
Published: May 2007

Objective: To evaluate morphologic stability and patient satisfaction at least 5 years after orthodontic treatment.

Materials and Methods: Published literature was searched through the PubMed and Cochrane Library electronic databases from 1966 to January 2005. The search was performed by an information specialist at the Swedish Council on Technology Assessment in Health Care. The inclusion criteria consisted of a follow-up period of at least 5 years postretention; randomized clinical trials, prospective or retrospective clinical controlled studies, and cohort studies; and orthodontic treatment including fixed or removable appliances, selective grinding, or extractions. Two reviewers extracted the data independently and also assessed the quality of the studies.

Results: The search strategy resulted in 1004 abstracts or full-text articles, of which 38 met the inclusion criteria. Treatment of crowding resulted in successful dental alignment. However, the mandibular arch length and width gradually decreased, and crowding of the lower anterior teeth reoccurred postretention. This condition was unpredictable at the individual level (limited evidence). Treatment of Angle Class II division 1 malocclusion with Herbst appliance normalized the occlusion. Relapse occurred but could not be predicted at the individual level (limited evidence). The scientific evidence was insufficient for conclusions on treatment of cross-bite, Angle Class III, open bite, and various other malocclusions as well as on patient satisfaction in a long-term perspective.

Conclusions: This review has exposed the difficulties in drawing meaningful evidence-based conclusions often because of the inherent problems of retrospective and uncontrolled study design.
Maxillary Canine—First Premolar Transposition
Authors: Capelozza Filho Leopoldino , Cardoso Mauriciode Almeida , An Tien Li , Bertoz Francisco Antonio
Published: May 2007

Tooth transpositions present at a relatively low incidence in the world population and primarily affect maxillary canines and premolars. Treatment of this disturbance should take into account aspects such as facial pattern, age, malocclusion, tooth-size discrepancy, stage of eruption, and magnitude of the transposition. Mechanics for correction should be entirely individualized, reducing the risks and adverse effects. Practitioners often select simpler options, indicating extraction of permanent teeth, which is an irreversible procedure that may bring about damages to the patient. This study presents a case report and treatment of unilateral transposition of maxillary canine and premolar with repositioning of affected teeth to their respective normal positions.
Unusual Extraction Treatment in Class II division 1 Using C-Orthodontic Mini-Implants
Authors: Chung Kyu-Rhim , Cho Jae-Hee , Kim Seong-Hun , Kook Yoon-Ah , Cozzani Mauro
Published: May 2007

This paper describes the treatment of a female patient, aged 23 years and 5 months, with a Class II division 1 malocclusion, who showed severe anterior protrusion and lower anterior crowding. Specially-designed orthodontic mini-implants were placed bilaterally in the interdental space between both the upper and the lower posterior teeth. Both lower first molars showed severe apical lesions. Therefore, the treatment plan consisted of extraction of both upper first premolars and lower first molars, en masse retraction of the upper six anterior teeth, lower anterior alignment, and protraction of all the lower molars. C-implants® were used as substitutes for maxillary posterior anchorage teeth during anterior retraction and as hooks for mandibular molar protraction. The correct overbite and overjet were obtained by intruding and retracting the upper six anterior teeth into their proper positions. The dentition was detailed using conventional orthodontic appliances. The upper C-implants contributed to an improvement in facial balance, and the lower C-implants made it possible to protract the lower second and third molars with less effect on the axis of the lower anterior teeth. The active treatment period was 29 months and the patient's teeth continued to be stable 11 months after debonding.
Chinese Norms of McNamara's Cephalometric Analysis
Authors: Wu John , Hägg Urban , Rabie A. Bakr M.
Published: May 2007

Objective: To establish cephalometric norms of McNamara's analysis in young Chinese and compare them to those of a matched young Caucasian sample.

Materials and Methods: The material comprised lateral cephalometric radiographs of a random sample of 200 male and 205 female 12-year-old southern Chinese children, and an additional sample of 43 male and 43 female 12-year-old British Caucasian children in Hong Kong. The radiographs were digitized twice with the CASSOS program.

Results: The results showed that there were statistically significant gender differences for six out of the 11 cephalometric variables in the Chinese, but for only one variable in the Caucasians. The size of the statistically significant gender differences varied from −0.3 to 0.4 on SD scores. There were statistically significant ethnic differences for eight variables in males and seven variables in females. The size of the observed statistically significant ethnic differences varied from −1.8 to 1.6 on SD scores.

Conclusion: The use of specific standards for Chinese, separate for gender, for McNamara's cephalometric analysis seems to be justified.
Tooth Size Discrepancies in an Orthodontic Population
Authors: Othman Siti , Harradine Nigel
Published: May 2007

Objective: To explore how many millimeters of tooth size discrepancy (TSD) are clinically significant, to determine what percentage of a representative orthodontic population has such a tooth size discrepancy, and to determine the ability of simple visual inspection to detect such a discrepancy.

Materials and Methods: The sample comprised 150 pretreatment study casts with fully erupted and complete permanent dentitions from first molar to first molar, which were selected randomly from 1100 consecutively treated white orthodontic patients. The mesiodistal diameter tooth sizes were measured using digital calipers, and the Bolton analysis and the tooth size corrections were calculated by the Hamilton Arch Tooth System (HATS) software. Simple visual estimation of Bolton discrepancy was also performed.

Results: In the sample group 17.4% had anterior tooth-width ratios and 5.4% had total arch ratios greater than 2 of Bolton's standard deviations from Bolton's mean. For the anterior analysis, correction greater than ± 2 mm was required for 16% of patients in the upper arch or 9% in the lower arch. For the total arch analysis, the corresponding figures are 28% and 24%.

Conclusions: It is recommended that 2 mm of required tooth size correction is an appropriate threshold for clinical significance. A significant percentage of patients have a TSD of this size. Visual estimation of TSD has low sensitivity and specificity. Careful measurement is more frequently required in clinical practice than visual estimation would suggest.
Intrusion of Overerupted Upper First Molar Using Two Orthodontic Miniscrews
Authors: Kravitz Neal D. , Kusnoto Budi , Tsay Peter T. , Hohlt William F.
Published: May 2007

Loss of the mandibular first molar often leads to the overeruption of the opposing maxillary first molar, resulting in occlusal interference, loss of periodontal bony support, and inadequate room to restore the mandibular edentulous space. Without orthodontic molar intrusion or segmental surgical impaction, restoring the posterior occlusion often entails the need for significant reduction of maxillary molar crown height, with the potential need for costly iatrogenic root canal therapy and restoration. The literature has cited successful maxillary molar intrusion with minor prosthodontic reduction using palatal orthodontic miniscrews and buccal zygomatic miniplates. In this report, the authors present successful maxillary molar intrusion with two orthodontic miniscrews in a patient with extreme dental anxiety and significant dental erosion due to gastric reflux. Using two orthodontic miniscrews for skeletal anchorage to intrude the maxillary molar simplified the orthodontic treatment by eliminating the need for extensive surgery, headgear, and intraoral multiunit anchorage and preserved indispensable tooth enamel. The clinical results showed significant intrusion through the maxillary sinus cortical floor while maintaining periodontal health, tooth vitality, and root length.
Three-Dimensional Palatal Development between 3 and 6 Years
Authors: Ciusa Veronica , Dimaggio Francesca Romana , Sforza Chiarella , Ferrario Virgilio Ferruccio
Published: May 2007

Objective: To measure palatal landmarks of healthy nonpatient children aged 3 to 6 years with a normal deciduous dentition and to evaluate palatal shape independent of size.

Materials and Methods: Fifty-eight dental casts of children with a normal and complete deciduous dentition were obtained and digitized with a computerized 3D instrument. At all ages, male and female data did not differ (Student's t-test), so the pooled values were considered. Dimensions were compared between ages by analyses of variance.

Results: Palatal slope and height increased significantly as a function of age (P < .001). Palatal length did not change with age (average: 23.1 mm). In the frontal plane, the intermolar width increased slightly with age by about 1.8 mm at the second molars, 1.1 mm at the first molars, and 0.9 mm at the canines. Palatal height in the frontal plane did not change in the posterior part of the palate, but decreased anteriorly. The intercanine distance increased by 0.9 mm with age. However, this change did not reach statistical significance.

Conclusions: Between 3 and 6 years of age, palatal shape changed and became proportionally higher in both the frontal and sagittal planes.
Periodontal Ligament Hydrostatic Pressure with Areas of Root Resorption after Application of a Continuous Torque Moment
Authors: Hohmann Ansgar , Wolfram Uwe , Geiger Martin , Boryor Andrew , Sander Christian , Faltin Rolf , Faltin Kurt , Sander Franz Guenter
Published: May 2007

Objective: To evaluate the risk of root resorption, individual finite element models (FEMs) of extracted human maxillary first premolars were created, and the distribution of the hydrostatic pressure in the periodontal ligament (PDL) of these models was simulated.

Materials and Methods: A continuous lingual torque of 3 Nmm and 6 Nmm respectively was applied in vivo to the aforementioned teeth. After extraction, FEMs of these double-rooted teeth were created based on high-resolution microcomputed tomographics (micro CT, voxel size: 35 microns). This high volumetric resolution made the recognition of very small resorption lacunae possible. Scanning electron micrographs of the root surfaces were created as well. This enabled the investigation of advantages and disadvantages of the different imaging techniques from the viewpoint of the examination of root resorption. Using the FEMs, the same loading conditions as applied in vivo were simulated.

Results: The results of clinical examination and simulations were compared using the identical roots of the teeth. The regions that showed increased hydrostatic pressure (>0.0047 MPa) correlated well with the locations of root resorption for each tooth. Increased torque resulted in increased high-pressure areas and increased magnitudes of hydrostatic pressure, correlating with the experiments.

Conclusion: If hydrostatic pressure exceeds typical human capillary blood pressure in the PDL, the risk of root resorption increases.
Glenoid Fossa Responses to Mandibular Lateral Shift in Growing Rats
Authors: Liu Chang , Kaneko Sawa , Soma Kunimichi
Published: May 2007

Objective: To evaluate the morphological and histological responses of the glenoid fossa to mandibular lateral shift in growing rats.

Materials and Methods: A resin plate was placed on the upper incisors of 4-week-old rats in the experimental groups to displace the mandible to the left during closure. The rats were killed after 2, 4, 8, and 12 weeks. The morphometric measurements were performed on dry skulls, and tissue blocks were processed for periodic acid and Schiff's reagent (PAS) staining to examine the new bone formation.

Results: Gross measurements showed asymmetry in both the position and size of the fossae between the two sides after 4 weeks of lateral shift. The glenoid fossa on the ipsilateral side was repositioned relatively backward, outward and upward compared with the contralateral side and control group, whereas the fossa on the contralateral side was relocated relatively forward and downward compared with the control group. The length of the fossa was smaller on the ipsilateral side than on contralateral side and control group. At 2 weeks, the amount of newly formed bone in the posterior region of the fossa was higher in the experimental group than the control group.

Conclusion: It is suggested that the mandibular lateral shift causes asymmetry in the position and size of the glenoid fossa and that this phenomenon can be related to different bilateral directional new bone formation in the posterior region.
Proportional Analysis of Longitudinal Craniofacial Growth Using Modified Mesh Diagrams
Authors: Jiang Jiuhui , Xu Tianmin , Lin Jiuxiang , Harris Edward F.
Published: May 2007

Objective: To study the craniofacial changes of adolescents followed longitudinally with their heads oriented in natural head position.

Materials and Methods: Longitudinal cephalograms of adolescents (n = 28) with normal occlusion, selected from among 900 candidates, were taken at 13 and again at 18 years of age. Modified elaborate mesh diagrams were developed defined by 90 anatomic landmarks and an additional 172 interpolated points for each cephalogram using a preset computer program. Detailed proportional and disproportional craniofacial changes were showed by both statistical and graphical methods.

Results: In females, most craniofacial regions exhibited growth that was proportionate to the mesh core rectangle reference on extracranial true vertical. In males, there was an upward, disproportional enhanced shift of the anterior cranial base and a downward enhanced shift of the mandibular symphysis and inferior border of the corpus.

Conclusions: This elaborate mesh analysis, based on mesh core rectangle and referenced on estimated natural head position, provides a novel graphical as well as quantitative method of assessing craniofacial growth. From 13 to 18 years of age, two sexes with normal occlusion displayed different growth patterns referenced on estimated natural head position. In females, most craniofacial regions exhibited growth proportional to the mesh core rectangle. In males, there was an upward, enhanced shift of the anterior cranial base and a downward enhanced shift of the mandibular symphysis and inferior border of the corpus.
A Self-Conditioner for Resin-Modified Glass Ionomers in Bonding Orthodontic Brackets
Authors: Bishara Samir E. , Ostby Adam W. , Laffoon John , Warren John J.
Published: May 2007

Objective: To evaluate a new self-etch conditioner used with resin-modified glass ionomers (RMGIs) in bonding orthodontic brackets.

Materials and Methods: Sixty human molars were cleaned, mounted, and randomly divided into three groups. In group 1 (control), 20 orthodontic brackets were bonded to teeth using Transbond Plus Self-etching Primer; in group 2, 20 brackets were bonded using an RMGI with a 10% polyacrylic acid conditioner. In group 3, 20 brackets were bonded using Fuji Ortho LC with a new no-rinse self-conditioner for RMGIs. The same bracket type was used on all groups. The teeth were debonded in shear mode using a universal testing machine, and the amount of residual adhesive remaining on each tooth was evaluated. Analysis of variance was used to compare the shear bond strength (SBS), and the χ2 test was used to compare the Adhesive Remnant Index (ARI) scores.

Results: There were no significant differences in the SBS (P = .556) between the groups. The mean SBS for Transbond Plus was 8.6 ± 2.6 MPa, for Fuji Ortho LC using 10% polyacrylic acid 9.1 ± 4.6 MPa, and for Fuji Ortho LC using GC Self-conditioner 9.9 ± 4.1 MPa. The comparisons of the ARI scores between the three groups (χ2 = 35.5) indicated that bracket failure mode was significantly different (P < .001), with more adhesive remaining on the teeth bonded using Transbond.

Conclusions: The new self-etch conditioner can be used with an RMGI to successfully bond brackets. In addition, brackets bonded with Fuji Ortho LC resulted in less residual adhesive remaining on the teeth.