Three-dimensional stereophotogrammetric analysis of 50 smiles: A study of dento-facial proportions.

OBJECTIVES: The purpose of this study was to analyze 50 smiles using 3D stereophotogrammetry (3D-spg)-based facial reconstruction, to calculate ratios involving measurements of the distances between dental and facial landmarks and to compare these ratios with the golden ratio φ (1.618). MATERIALS AND METHODS: Fifty subjects with no obvious malocclusion participated in this study. For each subject, 4 photographs were acquired using the LifeViz Mini™, an absolute calibration 3D-spg system. Facial and dental landmarks (based on Farkas' definitions) were fixed, and 8 distances were measured. Four ratios were then calculated and compared with the value of 1.618. RESULTS: The ratio "incisal edge of the maxillary central incisor-lower border of the chin/subnasal point-incisal edge of the maxillary central incisor" (IE-Me/SN-IE) was 1.693 ± 0.190, the ratio "right endocanthion-left endocanthion/right exocanthion-right endocanthion" was 1.582 ± 0.173, the ratio "incisal edge of the maxillary central incisor-distal edge of the right canine/distal edge of the right canine-right labial commissure" was 1.670 ± 0.355, and the ratio "right labial commissure-left labial commissure/distal edge of the right canine-distal edge of the left canine" was 1.602 ± 0.136. In contrast, the vertical ratio IE-Me/SN-IE significantly differed from the golden ratio (1 sample t test, P = .009). CONCLUSION: This study revealed that the observed ratios were surprisingly close to the golden ratio. Only the vertical ratio differed from the golden ratio, whereas the horizontal ratios appear to be adequately approximated by φ. CLINICAL SIGNIFICANCE: If the distances from reference points of the face to teeth within a harmonious smile exhibited recurring esthetic proportions, knowledge of such ratios would provide an additional tool for the elaboration of esthetic treatment plans. In addition, this knowledge could provide guidance when planning tooth positions and dental proportions by encouraging consideration of the global nature of the oro-facial sphere.

Flexural Properties, Wear Resistance, and Microstructural Analysis of Highly Filled Flowable Resin Composites.

OBJECTIVE: This study aimed to evaluate the flexural properties and two-body wear resistance of nine highly filled flowable resin composites relative to those of viscous and conventional low-filled flowable composites. In addition, scanning electron microscopy (SEM) analysis of the microstructures was performed. METHODS AND MATERIALS: For each resin composite group (n=12), 12 specimen bars (25 mm × 2 mm × 2 mm) were fabricated using a silicon mold for performing flexural strength (FS), flexural modulus (E), flexural toughness (FT), Weibull modulus (m) tests, and SEM microstructural analysis. For each group, ten bars were tested using a three-point flexural test on a universal testing machine, while the other two were embedded in acrylic resin before being observed by SEM for structural analysis. During the two-body wear test with a chewing simulator, 8 specimens (12 groups, n=8) of each resin composite group were manufactured in a specific mold and subjected to 120,000 cycles of wear against a steatite ball, and the depth loss was measured. Three one-way ANOVA tests followed by Tukey's post hoc tests were conducted to compare the flexural and wear properties among the different groups. RESULTS: The majority of highly filled composites tested in this study exhibited similar flexural strengths (between 105.68 MPa and 135.49 MPa) and superior wear resistance to those of viscous composites. The flexural moduli (between 5.12 GPa and 9.62 GPa) of these composites were in between those of the viscous and low-filled composites tested in this study. CONCLUSIONS: The highly filled flowable composites tested in this study exhibited different in vitro properties but were often superior to those of viscous resin composite suggesting their possible use for posterior restorations.

Glucosensing capacity of rainbow trout telencephalon.

To assess the hypothesis of glucosensing systems present in fish telencephalon, we first demonstrated in rainbow trout, by in situ hybridisation, the presence of glucokinase (GK). Then, we assessed the response of glucosensing markers in rainbow trout telencephalon 6 hours after i.c.v. treatment with glucose or 2-deoxyglucose (inducing glucoprivation). We evaluated the response of parameters related to the mechanisms dependent on GK, liver X receptor (LXR), mitochondrial activity, sweet taste receptor and sodium-glucose linked transporter 1 (SGLT-1). We also assessed mRNA abundance of neuropeptides involved in the metabolic control of food intake (agouti-related protein, neuropeptide Y, pro-opiomelanocortin, and cocaine- and amphetamine-related transcript), as well as the abundance and phosphorylation status of proteins possibly involved in linking glucosensing with neuropeptide expression, such as protein kinase B (AkT), AMP-activated protein kinase (AMPK), mechanistic target of rapamycin and cAMP response element-binding protein (CREB). The responses obtained support the presence in the telencephalon of a glucosensing mechanism based on GK and maybe one based on LXR, although they do not support the presence of mechanisms dependent on mitochondrial activity and SGLT-1. The mechanism based on sweet taste receptor responded to glucose but in a converse way to that characterised previously in the hypothalamus. In general, systems responded only to glucose but not to glucoprivation. Neuropeptides did not respond to glucose or glucoprivation. By contrast, the presence of glucose activates Akt and inhibits AMPK, CREB and forkhead box01. This is the first study in any vertebrate species in which the response to glucose of putative glucosensing mechanisms is demonstrated in the telencephalon. Their role might relate to processes other than homeostatic control of food intake, such as the hedonic and reward system.

Analysis of adrenergic regulation of melatonin synthesis in Siberian hamster pineal emphasizes the role of HIOMT.

Seasonal variations of environmental factors are translated into annual fluctuations in synthesis and release of melatonin, which in turn acts as a neuroendocrine messenger for the synchronization of annual functions. So far, most studies performed to understand the regulation of melatonin synthesis have used the non seasonal laboratory rat. It was demonstrated that nocturnal melatonin synthesis depends on alpha- and beta-adrenergic activation of the enzyme arylalkylamine N-acetyltransferase (AA-NAT). In this study, we investigated the mechanisms of melatonin synthesis in the Siberian hamster, a seasonal species with marked photoperiodic variation in melatonin peak duration and amplitude. A beta-adrenergic receptor agonist alone markedly stimulated AA-NAT activity and melatonin synthesis and release. An alpha-adrenergic receptor agonist, while having no effect per se, potentiated the beta-adrenergic stimulation of AA-NAT activity both in vitro and in vivo. Strikingly, the potentiation of AA-NAT activity did not result in a potentiation of melatonin synthesis, suggesting that the rate of melatonin production is limited downstream in the metabolic pathway, most probably at the level of hydroxyindole-O-methyltransferase (HIOMT). HIOMT presented a constitutively high activity that was not acutely (within hours) stimulated by beta-adrenergic agonist, but was rather up-regulated by chronic application of the agonist. This long-term beta-adrenergic regulation may explain the reported large photoperiodic variation of HIOMT activity that drives the photoperiodic variation in melatonin peak.

Measuring quality of life from the point of view of HIV-positive subjects: the HIV-QL31.

Assessment of the quality of life (QoL) of human immunodeficiency virus (HIV)-infected subjects is often based on questionnaires in which the items or questions are not seen to be relevant by patients, nor by the users of the data obtained. It therefore seemed appropriate to return to the issue. The methodological and bibliographical research as well as the consultations we conducted convinced us that the elaboration of a new questionnaire was both necessary and possible. In order to do so, we adopted methodological principles based on the Sickness Impact Profile development methodology. First a bibliographical research was conducted in order to study instruments already used for HIV infection. Then, experts concerned with HIV infection and members of patients' associations were interviewed to assess how opportune the development of a new instrument could be. Following this, a methodology was established for the design and construction of the new instrument. One hundred and eighteen candidate questions were generated from an analysis of the content of 20 patients' interviews, which were subsequently submitted to 102 patients, to obtain finally a set of 31 questions from the interpretation of the results obtained from classic psychometric analysis and also from non-classic methods (item response theory and Rasch model). The concept being measured is the impact of illness being experienced by HIV-infected subjects from their own perspective. The range of health states covered by this questionnaire relates to fairly mild conditions. Rasch analysis of this set of 31 questions (HIV-QL31) shows that it corresponds to one unidimensional construct. A single score can be calculated by simple summation of dichotomous response options. This score is highly reliable (Cronbach's alpha coefficient = 0.93) and is also discriminant regarding the severity of clinical status.