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Biomedical subjects

M N Spyropoulos

Publications and source records attributed to M N Spyropoulos.

At least 19 recordsLinked to original sources
PubMed2001

Significance of the soft tissue profile on facial esthetics.

The soft tissue profile has been studied extensively in orthodontics, primarily from lateral cephalometric radiographs, under the assumption that the form of the soft tissue outline largely determines the esthetics of the whole face. The purpose of this study was to assess the relative contribution of the shape of the soft tissue profile outline on the attractiveness of the face, as seen from the profile view. Pretreatment color profile facial photographs of 20 female patients were used. The photographs were scanned, and the soft tissue outlines were digitized. The average outline of the 20 original photographs was then calculated and used as a template for modifying the photographs with computer warping methods. This resulted in 20 warped photographs, all with the same soft tissue outline. Three additional photographs were constructed with 1 face-the composite average of the 20 original photographs-and 3 hairstyles from 3 of the original pictures. The photographs were printed and presented to 10 laypersons and 10 orthodontists for scoring. Scoring was performed on 2 occasions separated by at least 1 week. On the first occasion, the original photographs of 10 of the patients and the warped photographs of the other 10 patients were shown. At the next session, the remaining 10 original and 10 warped photographs were shown. The 3 composite photographs were interspersed with the 20 pictures shown to the judges in each scoring session. Judges were asked to score facial attractiveness on a scale of 0 to 10. The judges were unaware of both the computer modification of the photographs and the purpose of the study. Good agreement was noted between the judges, although the orthodontists tended to be more influenced by the profile outline than did the laypersons. The 3 averaged composite photographs were consistently given the highest scores. The modified photographs were given higher scores than their original counterparts, showing that facial attractiveness is influenced by soft tissue outline form. However, the score improvement was not sufficient to reach the level of the composite images, especially for faces initially judged as being unattractive. This shows that factors other than profile outline shape may be more influential in facial esthetics.

Adolescent↗
PubMed2001

Patterns of body and visceral growth in human prenates with clefts of the lip and palate.

OBJECTIVE: To address the hypothesis that human prenates with birth defects such as clefts of the lip and palate show growth patterns in which body size and visceral growth are aberrant for prenatal age. METHODS: Body size and organ weight measurements were derived from a cross-sectional population sample of 167 legally donated human embryos that were representative of key periods in visceral organogenesis and growth. Measurements included those of overall body size (i.e., length and weight) and weights of major organs. Data were analyzed for two comparative (age-matched) groups consisting of 120 typical-for-age "control" and 47 specimens showing the three typical cleft types. Organ weight data for the entire cleft group and for each of the three cleft subgroups were compared with those of the control group. RESULTS: Cleft specimens showed crown-rump body sizes that were within one standard deviation of the control group. Among the entire cleft sample, each of the organ weight values was generally consistent with the organ weights observed for the age-matched control group. When organ weights for the cleft group differed from the controls, with one exception, some organs showed either increased or decreased organ weights. One remarkable exception was with lung weights, which were reduced for each of the prenates across the three cleft types. Among the three cleft groups, fetuses with cleft lip and palate showed the highest percentage of organ weight discrepancies (i.e., smaller than expected) as compared with the group with cleft palate, which showed the lowest. CONCLUSIONS; Organ weight aberrancies were observable (whether increased or reduced weights), and such aberrancies were not apparent until approximately 24 weeks (fertilization age).

Body Weight↗
PubMed2001

Effects of drugs and systemic factors on orthodontic treatment.

Orthodontic tooth movement and bone remodeling activity are dependent on systemic factors such as nutritional factors, metabolic bone diseases, age, and use of drugs. Therefore, a comprehensive review of the effects of these factors on orthodontic tooth movement is attempted in this article. Systemic hormones such as estrogen, androgen, and calcitonin are associated with an increase in bone mineral content, bone mass, and a decrease in the rate of bone resorption. Consequently, they could delay orthodontic tooth movement. On the contrary, thyroid hormones and corticosteroids might be involved in a more rapid orthodontic tooth movement during orthodontic therapy and have a less stable orthodontic result. Drugs such as bisphosphonates, vitamin D metabolites, and fluorides can probably cause a reduction of tooth movement after the orthodontic force is applied. Nonsteroidal anti-inflammatory drugs have also been shown to reduce bone resorption. Long-term administration of these drugs may therefore delay the necessary bone response to respective tooth-borne pressure and should not be administered for long periods of time to patients undergoing orthodontic tooth movement. Attention has also been focused on the effects of prostaglandins and leukotrienes in orthodontic tooth movement. It seems that they might have future clinical applications that could result in enhanced tooth movement. The use of the above drugs should be considered by every dentist in evaluating the treatment time and in planning treatment when tooth movement is attempted.

Animals↗
PubMed2001

Premolar development in Greek children with cleft lip and palate.

OBJECTIVE: The purpose of this investigation was to study the development of the premolars in a sample of Greek children with cleft lip and palate. METHOD AND MATERIALS: The study material consisted of panoramic radiographs of 34 individuals (22 boys and 12 girls) with cleft lip with or without cleft palate. The boys ranged from 9.0 to 14.0 years of age and the girls ranged from 8.0 to 14.5 years of age. The mean age was 11.3 years. Each panoramic radiograph was matched with a corresponding one of an unaffected individual of the same sex and chronologic age (+/- 3 months). The panoramic radiographs were used to categorize the stages of tooth development according to the 10 stages of mineralization described by Nolla. The assessment was repeated by a second observer. RESULTS: Individuals with clefts exhibited a statistically significant delay of formation and mineralization of the maxillary right and left second premolars and the mandibular right second premolar in comparison to individuals without clefts. In the cleft group, there was no statistically significant difference between boys and girls in premolar development. No asymmetric development of contralateral premolar teeth was observed in individuals with cleft lip and palate. CONCLUSION: Although the exact biologic explanation remains to be found, the formation of premolars is delayed in children with cleft lip and palate.

Adolescent↗
PubMed1997

An appliance designed for experimental mandibular hyperpropulsion in rats.

Many animal experiments dealing with function-form interaction and mandibular condylar growth have utilized hyperpropulsion of the animal's mandible. Numerous hyperpropulsive appliances have been described in the literature. However, there are significant discrepancies between reported results which are most likely due to the use of appliances that do not secure true mandibular hyperpropulsion. The specific rat craniofacial anatomy as well as the masticatory physiology of this animal requires the design of a specific appliance that would meet the species' functional characteristics. The aim of this paper is to describe a new type of appliance that can produce a controlled, stable and reproducible anterior displacement of the mandible in rats. After reviewing and evaluating the appliances used by other researchers, a totally new appliance for experimental mandibular hyperpropulsion in rats is presented. Its advantages are: (i) it produces a secure, measurable and reproducible anterior displacement of the mandible; (ii) it does not permit any retrusive or lateral mandibular movements. Avoidance of this variable can increase reliability of results and minimize involvement of other confusing parameters; and (iii) it allows the animals to be fed sufficiently for a number of hours every day. The appliance consists of an acrylic collar brace fitted to the animal's neck and carrying wire extensions that support rubber bands pulling on a band cemented to the animal's lower incisors. The pulling force depends on the thickness of the applied elastics.

Acrylic Resins↗
PubMed1997

Effects of altered mandibular function on mandibular growth after condylectomy.

The purpose of this study was to investigate the effect of protruded mandibular function on bilaterally condylectomized mandibles of growing rats. Sixty 4-week-old rats were divided into three experimental and two control groups each consisting of 12 animals as follows: (A) bilateral condylectomy was performed and the mandible was left to function normally; (B) the mandible was protracted forward without any condylectomy; (C) after bilateral condylectomy, the mandible was forced to function in a protruded position; (D) the animals were used as controls without any operation or appliance; and (E) a sham operation was performed in the condylar area but no appliance was used. Mandibular protraction was achieved by means of a specific appliance acting via rubber bands pulling the mandible in a straight, forward direction with a force of 25 g for 12 hours/day. The experimental period was 30 days. Lateral and dorsoventral radiographs were taken and vital dyes were administered on days 1 and 30 for all animals. Cephalometric analysis included 10 measurements. Findings resulting from statistical analysis of measurements in the five groups are summarized as follows: (i) between group A and groups D and E, less growth was found in group A; (ii) between group B and groups D and E, more growth was found in group B; (iii) between group A and group B, more growth was found in group B; (iv) between group A and group C, more growth was found in group C; and (v) between group B and group C, more growth was found in group B. These findings support the conclusion that although mandibular propulsion enhances growth even after condylectomy, the condyle seems to be an essential element for normal growth and development.

Analysis of Variance↗
PubMed1997

Effects of experimental unilateral condylectomy followed by altered mandibular function on the maxilla and zygoma.

The effect of protruded mandibular function on the maxilla and zygoma was studied in young unilaterally condylectomized growing rats. Forty-eight-4-week-old rats were divided into two experimental and two control groups as follows: group A, 12 animals unilaterally condylectomized on the right side; the mandible was allowed to function normally; group B, 12 animals unilaterally condylectomized on the right side; the mandible was protracted forwards immediately by means of an appliance; group C, 12 animals sham-operated on the right side; no condylectomy or mandibular protraction; and group d, 12 control animals not subjected to any operation or mandibular protraction. The mandibular protraction was achieved by an appliance consisting of an acrylic collar brace fitted to the animal's neck and supporting rubber bands pulling on an intraoral part cemented on the animal's lower incisors. Twenty-five grams of pulling force and protrusion to a clinically and radiographically testes anterior crossbite was exercised for 12 hours per day. The experimental period was 30 days. Lateral and dorsoventral radiographs were taken on days 1 and 30 following condylectomies and mandibular protraction. Cephalometric analysis was performed for each animal with measurements evaluating the maxilla and zygoma. Statistical analysis and comparison of the findings in the four groups of animals can be summarized as follows: (i) condylectomy and altered mandibular function may produce remote skeletal reactions in other parts of the cranial complex; and (ii) the ipsilateral maxilla is affected by condylectomy of the mandible, but altered mandibular function by protraction compensates for the results of condylectomy.

Animals↗
PubMed1997

Altered mandibular function and prevention of skeletal asymmetries after unilateral condylectomy in rats.

Unilateral condylar injury is known to be a frequent cause of mandibular asymmetry. Whether this is due to the trauma itself or to the disturbed function that follows the injury is a very important question with ramifications for clinical complications related to facial asymmetries. The aim of this study was to test the hypothesis that mandibular function in a protruded position can compensate for the absence of one condyle and prevent potential growth asymmetries. Forty-eight 4-week-old rats were divided into two experimental and two control groups consisting of 12 animals each, as follows: (A) unilateral condylectomy was performed on the right side and the mandible was left to function normally; (B) after unilateral condylectomy on the right side, the mandible was forced to function in a protruded position; (C) a sham operation was performed in the condylar area of the right side but no appliance was used; and (D) 12 animals were used as controls without any operation or appliance. Mandibular protraction was achieved by means of a specific appliance, acting via rubber bands, pulling the mandible in a straight, forward direction with a force of 25 g for 12 hours per day. The experimental period was 30 days. Dorsoventral radiographs were taken and vital dyes were administered at three time intervals, i.e. on days 1, 15 and 30, for all animals. Cephalometric analysis included 14 measurements. Findings resulting from statistical analysis and comparisons of measurements obtained in the four groups can be summarized as follows: (i) when comparing group A with groups C and D, less growth was found in the right mandibular sides in group A; (ii) when comparing group B and groups C and D, less growth was found in the right mandibular sides in group B; (iii) when comparing groups A and B, more growth was found in the right mandibular sides in group B; (iv) when comparing the right and left mandibular sides in group A, less growth was found in the right side; and (v) when comparing the right and left mandibular sides in group B, no significant growth differences were found. These findings support the hypothesis that altered mandibular function in a protruded position can compensate for the effects of unilateral condylectomy and prevent the appearance of skeletal mandibular asymmetries in growing rats.

Alveolar Process↗
PubMed1997

Evaluation of facial features in two groups of cleft lip and palate patients receiving centralized and non-centralized treatment regimes.

The aims of the present study were: (a) to evaluate facial profile and other findings in a group of cleft lip and palate (CLP) patients receiving centralized services as compared with a group of patients who received non-centralized services and who were not submitted to bone grafting procedures; and (b) to evaluate and compare the outcome of early bone grafting procedures that were included in the centralized treatment regime to the outcome of a non-centralized treatment approach that did not include bone grafting procedures. Forty-three lateral cephalometric radiographs of CLP Greek Caucasian children not receiving centralized treatment and 43 lateral cephalometric radiographs of CLP Swedish Caucasian children receiving centralized treatment, strictly matched for age, sex, and type of cleft, were compared as a total and in two subgroups, according to age. Differences were also evaluated in the unilateral (UCLP) and in the bilateral (BCLP) groups separately, as well as in groups discriminated by age, i.e. in the patients born before 1984 (age 11-19 years) and in those born after 1984 (age 4-10 years), as 1984 was the year when early bone grafting was discontinued in the Stockholm area. The findings of this study revealed the following. The overall difference in facial and dental cephalometric findings between CLP children receiving a centralized treatment approach as compared with those treated without centralization was significant. The Swedish group showed a trend towards better cephalometric values throughout all the age groups. When the early age groups were compared, the early bone grafting procedure that was included in the centralized treatment regime did not seem to be a positive factor, in comparison with the absence of bone grafting in the non-centralized treatment regime.

Adolescent↗
PubMed1994

Changes in cheek pressure following rapid maxillary expansion.

The purpose of the present investigation was to study the effects of rapid maxillary expansion on the pressures exerted by the cheeks on the maxillary arch. The sample consisted of 15 patients (five males, ten females) who received either a Hyrax or Haas type expansion appliance for treatment of a bilateral maxillary constriction of more than 5 mm. The median age of the sample was 12 years. Buccal pressures were measured at the upper first molar on the left and right side, before and after active expansion, and also after an average of 3-4 months of retention with the appliance in place. Buccal pressures on the maxillary first molar averaged approximately 3 g/cm2 before expansion and increased significantly to a value of approximately 9 g/cm2 after expansion. Pressure change was approximately 0.6 g/cm2 for each millimetre of expansion. During the 3-4-month period of stabilization of the appliance, the pressures remained at the post-expansion levels and no adaptation of the soft tissues was observed. These results lead to the conclusion that cheek pressures on the maxillary arch may be implicated in the relapse occurring after rapid expansion, even after the usual 3-month period of stabilization.

Adaptation, Physiological↗
PubMed1992

Hyoid bone position and orientation in Class I and Class III malocclusions.

Various studies have documented a variability of hyoid bone position in relation to changed mandibular position or head posture. The aim of this study was to investigate the hyoid bone position and inclination on the cephalometric radiographs of two groups of patients exhibiting Class I and Class III malocclusions. The radiographs were taken in both centric occlusion and wide-opened mandibular position, and 17 measurements were performed on both tracings. The findings reveal a statistically significant difference in the position and inclination of the hyoid bone in the two groups; Class III patients, especially the boys, show a more anterior position of the hyoid bone and also a reverse inclination. This might have an implication on the function of the suprahyoid and infrahyoid muscles and thus on the direction of mandibular growth.

Adolescent↗
PubMed1990

[Soft tissue configuration in certain syndromes of the head and neck].

In order to examine the relationship existing between soft tissue configuration and the underlying skeletodental framework, patients presenting severe and representative syndromes of the head and neck were studied. Grouping of these patients in three groups according to the similarities of the skeletal pattern and/or the etiology of the syndrome, provided a basis for evaluation, comparison and contradistinction of the configuration of the hard and soft tissues, in a material where genetic predetermination is dominant. By cephalometric analysis, superimposition and plotting of the soft tissues on an abstraction and relative magnification basis, the following conclusions could be formulated: a) There is a specificity in the soft tissue configuration of the face of patients with specific syndromes and, this specificity, seems to be independent of the underlying skeletodental elements in the area of the nose and the upper lip. b) A genetic predetermination of the soft tissue morphology can be deduced because, in patients with specific syndromes, the same characteristics accompany constantly the same chromosomal or gene mutations. c) Further studies along these lines might throw more light on the role of genetics in soft tissue configuration and function.

Acrocephalosyndactylia↗
PubMed1989

[Management of the cleft patient from birth to completion of the deciduous teeth].

Cleft lip and cleft palate are the most common defects of the craniofacial system. The treatment of children with this craniofacial malformation requires a multidisciplinary approach due to the complexity of their problems. Thus, cleft lip and palate teams have developed in many institutions, in order to provide the necessary medical and psychosocial treatment to these children. The treatment of children with cleft lip and cleft palate should begin right after birth and include their families as well. The purpose of the present paper is to present the problems of children with cleft lip and cleft palate from birth until the completion of their primary dentition. In addition, the systematic and comprehensive treatment planned by the various specialists of the team for the solution of the above problems, is presented in detail.

Cleft Lip↗
PubMed1989

[Orthodontic and maxillofacial confrontation of a hemifacial microsomic mandible, comprising electromyographic check].

A rare case of hemifacial microsomia of the mandible whose etiological entity is delineated from the bad posture of the foetus in the womb during the foetal period, is described. In this case, the combination of orthodontic and maxillofacial treatment, gave satisfactory results as regards the aesthetic problem of the person, the occlusal disturbances and the function, of the masseter and the temporalis-muscles. These functions were checked before, during and after the treatment by means of electromyograms, and a more balanced activity of these muscles could be detected after the combined treatment.

Adult↗