Mandibular Variables Research Articles

Les vertèbres cervicales : indicateurs du dynamisme de la croissance mandibulaire ?

A study of mandibular growth maturation was performed on a population of 103 patients during orthodontic treatment (69 girls and 34 boys) from 11 to 16 years, having initially a Class II skeletal discrepancy. The relationship between wrist maturation indices and the cervical vertebrae maturation was studied by Lamparski classification. Significant correlations were found between Björk stages, MP3=, MP3 cap and MP3 U and respectively Lamparski stages as CVS 2, CVS 3-4 and CVS 5-6. This retrospective longitudinal study identified three mandibular variables at three different maturation stages according to Björk classification and to the six stages of Lamparski classification. The relationships between these different maturation stages and a quantitative mandibular response permit to estimate optimal time for our orthodontic therapy. The results indicate a significant increase in mandibular length between CVS 4 and CVS 5, suggesting the persistence of a condylar response to a stimulation therapy after CVS3 or CVS 4 stages (MP3 cap). Mandibular growth seems to continue after MP3 U stage or CVS 5 stage.

Cephalometric craniofacial features in Saudi parents and their offspring

To estimate the correlation and heritability values of craniofacial variables between parents and their offspring. The sample comprised 24 Saudi families; each family consisted of father, mother, son, and daughter. Lateral cephalometric radiographs were taken for each family member. Twenty-eight angular, linear, and proportional cephalometric variables were measured. Interfamilial correlations and heritability (h(2)) values were estimated among father-son, father-daughter, mother-son, and mother-daughter pairings. The most similar angular measurements between parents and offspring were related to mandibular variables, which were as follows: MP-SN degrees , MP-FH degrees , SNB degrees , and SNPog degrees ; facial height dimensions and mandibular body length were among the highest similar linear variables. Lower facial height percentage had greater resemblance to parents with regard to proportional measurements. Both the correlation coefficients and the heritable values of these characteristics were stronger in the father-offspring than the mother-offspring pairings. The daughters' cephalometric craniofacial characteristics were more affected by the parents than were those of the sons. The overall correlation and h(2) mean values for the three types of measurements showed stronger values in the father-offspring than the mother-offspring groups, with the father-daughter pairings more significant than the father-son groups.

Bone mass and trabecular pattern in the mandible as an indicator of skeletal osteopenia: a 10-year follow-up study

The aim of this investigation was to evaluate mandibular trabecular pattern as an indicator of osteopenia and bone mineral density (BMD) changes in relation to mandibular bone changes. Forty females (49 to 80 years old) underwent intraoral radiography and BMD examinations 10 years apart. The trabecular pattern was assessed visually (Lindh's index), bone texture digitally, and bone mass by its grey-level values. With the exception of one subject, all individuals with sparse trabeculation were found to be osteopenic. All mandibular variables were tested for correlations with forearm and hip BMDs. They predicted forearm BMD, but adjusted for body mass index not hip BMD. Age, body mass index, and mandibular variables explained 29% to 64% of BMD variance. BMD changes correlated with body mass index change, bone texture change, and trabeculation change. Mandibular variables identify individuals with low BMD, but they are not discriminating enough for osteoporosis diagnostics. Mandibular bone changes correlated with forearm BMD changes.

Mandible of the giant panda (Ailuropoda melanoleuca) compared with other Chinese carnivores: functional adaptation

The aim of this study was to understand the mandible of the giant panda in morphometric terms to explore differences between the giant panda and other carnivores distributed in China, in terms of functional adaptation. Twelve mandibular variables were studied using bivariate (allometry) and multivariate (principal components analysis, PCA, and discriminant functional analysis, DFA) tools. When deviations were produced from allometric baselines consisting of all the species studied, the giant panda displayed a much more developed mandibular structure than the bear, leopard, and tiger. This may be related to its specific dietary preference for bamboo, which has very strong fibers. Results also indicate that the mandibular structure among carnivores mainly reflects the differences in their dietary preferences and functional adaptation. Three groups were found referring to dispersal profiles expressed by the first two axes of PCA and DFA: (1) the two panda species – the herbivorous carnivores; (2) the black bear – the omnivorous carnivore; and (3) the tiger and leopard – the hypercarnivores. Nevertheless, a significant separation between the two panda species was also found with the profiles displayed by the first and third axes of DFA. In addition to no close evolutionary relationship and phylogenetic development, a noticeable separation between the two panda species found in DFA analysis may be associated with their variation in consuming different parts of the bamboo plant: the giant panda feeds on stems and the red panda feeds on leaves. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 449–456.

An anthropometric study of relationships between the clival angle and craniofacial measurements in adult human skulls

STATING BACKGROUND: The clival angle, between the ethmoidal plane and the clival plane, measures the cranial base angulation. Relations between cranial base angulation and facial patterns have been discussed and present contradictory evidence. The aim of this study is to determine whether correlations could be found between the clival angle and craniofacial measurements. This study was carried out on a sample of 235 human skulls. Twenty landmarks were marked. The clival angle and 16 other variables were measured and compared using analysis of variance. Statistical analysis showed a relationship between the clival angle and six measurements (P < 0.05). There was a positive correlation between the clival angle and the cranial lengths, the nasomaxillary sagittal measurements and palatal length but the width of the foramen magnum had a negative correlation. No significant relationship was found between the clival angle and the cranial height and widths, the palatal width, the length of the foramen magnum and the mandibular measurements. The trends found in this study with regard to the craniofacial lengths show that the nasomaxillary complex in humans has a stable position lying beneath the anterior cranial base. Transversal, vertical and mandibular variables have a more independent relationship.

Analysis of mandibular variability in humans of different geographic areas

The mandible is the single mobile bone of the skull. It develops from the sixth week of the intrauterine life. The aim of our study is to confirm the variability of different mandibular landmarks in humans of different geographic areas. A number of 100 young persons from different geographic areas (Europe, Middle Orient, Asia and Africa) were selected. We used the classical measurement with the metric band and Baudeloque compass and analysed 50 cephalograms in frontal and lateral views. The focus of our measurements were the opening of the mandibular angle (gonion), ramal length and width, condylar diameters and the gonion-menton distance. In the European specimens, the opening of the mandibular angle is smaller than in the Asians. Africans had a lower value of the mandibular angle than Asians. Significant differences appeared in the gonion-menton distance measurements, as well. In conclusion, there is a positive correlation between the mandibular angle and the menton-gonion distance, respectively.

Herbst/multibracket appliance treatment of Class II division 1 malocclusions in early and late adulthood. A prospective cephalometric study of consecutively treated subjects

A prospective study of 23 consecutive adult Class II division 1 malocclusion subjects (19 female and 4 male) treated with the Herbst/multibracket (MB) appliance is presented. The skeletal, dental, and facial profile changes were evaluated in addition to the mechanism of Class II correction during the Herbst phase and the settling of the occlusion during the MB phase. The mean pre-treatment age of the subjects was 21.9 years (15.7-44.4 years). Lateral head films in habitual occlusion from before treatment (T1) and after the Herbst (T2) and MB (T3) phases were analysed using standard cephalometrics and the sagittal occlusion analysis. For the standard cephalometrics, normal growth standards were utilized as control parameters. All patients were treated successfully to a Class I occlusal relationship with a normal overjet and overbite. The mandibular variables (SNB and SNPg) showed an angular increase (1.22 and 0.93 degrees, respectively) during T2-T1 followed by an angular reduction (0.40 and 0.23 degrees, respectively) during T3-T2. Compared with normal growth standards, all mandibular parameters were affected favourably by Herbst/MB treatment. Both the skeletal and soft tissue profile convexities were significantly reduced. Over the entire observation period (T3-T1), the largest amount of profile convexity reduction was seen for the soft tissue profile excluding the nose (mean 3.14 degrees). Class II correction was achieved by both skeletal and dental changes: overjet correction by 13 per cent skeletal and 87 per cent dental changes, and molar correction by 22 per cent skeletal and 78 per cent dental changes. In conclusion, on a short-term basis, the Herbst/MB appliance combination was found to be a powerful tool for non-surgical, non-extraction, treatment of Class II division I subjects in early and late adulthood.

The effect of growth hormone therapy on mandibular and cranial base development in children treated with total body irradiation.

The aim of the present investigation was to study craniomandibular development during growth hormone (GH) therapy in nine girls and one boy, aged between 7.3 and 16 years, who exhibited pronounced growth reduction after total body irradiation (TBI) and bone marrow transplantation (BMT). Age- and sex-matched healthy children with normal dentofacial development constituted the control material. The investigation data were based on measurements made on lateral skull radiographs taken at the start and, on average, 6 months after cessation of GH treatment. The control group comprised similar longitudinal cephalographic records. The results showed that GH therapy in patients who exhibited growth retardation after TBI and BMT had only a minor effect on cranial base dimensions, probably due to the fact that the development of this area is completed at a relatively early age. The effect of GH treatment on mandibular growth was very obvious. The dimensional increase of the mandibular variables in the patients was equivalent to, or in some cases even exceeded, that of the controls. In relation to basion, the mandibular condyles were displaced in a backward/upward direction in the patient group. Displacement in the opposite direction was recorded in the controls. It seems likely that the development seen in the patients is a reflection of a normalization of the condyle-fossa relationship made possible by enhanced condylar growth. This change should be advantageous for the function of the craniomandibular complex.

Mandibular variation among Chinese macaques.

In order to clarify the degree to which mandibular variation among Chinese macaques results from functional adaptation and phylogenetic inertia, 13 mandibular variables were analyzed by bivariate and multivariate techniques. The results indicate, not surprisingly, that the main differences in the mandible are associated with size. The study further implies that the variation between species is not closely associated with differences in functional adaptation even though the dietary and related differences are large compared to the situation in other macaques. The great variety in diet and related factors among Chinese macaques may not have yet resulted in a significant variation in the mandible. This may be because their radiation in Asia, though involving considerably greater differences in habitat, climate, and so on, has occurred more recently than for other macaque species in Southeast Asia. Mandibular variation between these species, therefore, is likely to be more closely tied to their immediate prior phylogenetic history. For example, the two stump-tailed macaques are closely similar and are also closely similar to the Assam species. Function in the mandible in these species is quite different. The results, therefore, seem to support the hypothesis that these three macaque species should be placed in a single species-group (sinica) as proposed by Delson [1980], Pan [1998], and Pan et al. [1998].

Analysis of dental casts of 6-8- and 12-year-old Kenyan children

Dental plaster casts of 97 6-8-year-old and 173 12-year-old Maasai, Kikuyu, and Kalenjin children were studied. The Kikuyu are Bantu, while Maasai and Kalenjin are Nilo-Hamitic subjects. The variables measured were palatal depth (PD) and length (PL); maxillary and mandibular anterior arc circumferences (AC1) and (AC2), respectively; posterior arc circumferences (PC1) and (PC2), inter-canine (CC1), and (CC2); inter-molar (MM1) and (MM2) distances, and mandibular length (ML). The data were analysed using SPSS package. The mean values of all the variables were generally higher in the males compared with the females and significant sex differences in the means (P < 0.01) were found in AC1, PC1, PC2, CC1, CC2, MM1, and MM2 in the 12-year-old subjects. The means of all variables, except PL, ML, PC2, and CC2, increased from 6 to 12 years of age and significant differences in the means for age were found in ML, AC1, PC2, PD, MM1, MM2, and CC1. Mean maxillary inter-molar distance increased with age by 0.17-0.34 mm in the three groups. Mean values of mandibular variables were highest in the Kikuyu, while maxillary variables were highest in the Maasai. The Maasai casts showed a marked decrease in CC2, PC2, AC2, and ML compared with the Kikuyu and Kalenjin. Ethnic and sex differences in the dental arches may be masked by anterior tooth positions that are influenced by the dento-alveolar complex and soft tissues. Corresponding mandibular and maxillary variables were strongly correlated and anterior and posterior arc circumferences were correlated with inter-canine and intermolar distances. Details of the norms for dental arch dimensions and changes with age may allow for appropriate assessment of dental occlusion and treatment planning for Kenyan children.

Application of a Fourier series to analysis of the relationship between mandibular form and facial morphology.

The shape of the mandible is used by orthodontists as an aid to orthodontic treatment planning, with different shapes displaying different growth characteristics and being associated with different functional patterns. However, the quantification of shape using conventional linear and angular variables does not always include details of some of the more subtle aspects of form. Fourier analysis enables accurate representation, with few coefficients, of a mandibular outer line from articulare to infradentale. The aim of this study was to investigate, using a cluster analysis, the relationship between variation in mandibular form and overall facial morphology. A cluster analysis of the Fourier amplitudes classified mandibular forms into one of seven groups for both males and females. The cluster analysis showed that the gonial angle and the inclination of lower incisor were associated with facial type according to the mandibular variables. Furthermore, the Fourier descriptions of mandibular form could be related to the observed variation in facial form, each of the clusters based on mandibular form being associated with demonstrable differences in dentofacial morphology.

Soft tissue and dentoskeletal profile changes associated with maxillary expansion and protraction headgear treatment

One of the goals of early treatment of Class III malocclusion with maxillary expansion and protraction headgear is to significantly improve the dentofacial profile. The objectives of the present study were to determine (1) the interrelationships of the soft tissue and dentoskeletal profiles after maxillary expansion and protraction headgear treatment and (2) which cephalometric variables could contribute to an accurate prediction of the protraction effect on the soft tissue profile. Lateral cephalometric radiographs of 20 consecutively treated Class III patients (10 males, 10 females) by protraction headgear were included in this study. Their ages at the start of protraction headgear treatment ranged from 6 to 11 years, with an average of 8.1 ± 2.1 years. None of the patients had previous orthodontic treatment. For each patient, the first lateral cephalogram was taken 6 months before the initiation of headgear treatment (T o), and the second radiograph at the start of treatment (T 1). Therefore (T 1 − T o) represented 6 months of growth with no treatment. A third radiograph was taken 6 months after start of treatment (T 2). In this way, (T 2 − T 1) − (T 1 − T o) represented the effect the result of appliance therapy alone and each subject served as his/her own control. A computerized cephalometric analysis was used including variables assessing sagittal and vertical relationships of skeletal and soft tissue profiles, incisal relationships, soft tissue thickness, and lip structure. Data were analyzed by means of paired t tests, Pearson's product-moment coefficient correlation, and multiple regression analyses. The results showed significant improvements in dentofacial profile after 6 months of maxillary protraction. The skeletal and soft tissue facial profiles were straightened and the posture of the lips was improved. The normal incisal relationship (overjet) that was achieved had a significant impact on the soft tissues overlying both upper and lower incisors resulting in better lip competence and posture. Significant correlations were found between changes in the sagittal relationships of skeletal and soft tissue profiles in both the maxilla and the mandible ( p < 0.05). The forward movement of the maxilla was accompanied by a corresponding forward movement of the soft tissue profile at 50% to 79% of the hard tissue. In the mandible, the downward and backward movements of the soft tissues were equivalent to 71% to 81% of the corresponding hard tissues. The lack of high r square values in the multiple regression analyses reflected a low prediction value for the maxillary variables, but moderately high prediction value for the mandibular variables that could be used in preorthopedic treatment planning. This study showed that significant dentoskeletal changes and improvements in dentofacial profile resulted from 6 months of treatment with maxillary expansion and protraction. (A M J O RTHOD D ENTOFAC O RTHOP 1996;109:38-49.)

Effect of adenoidectomy on dentofacial skeleton in naso-respiratory dysfunction children

This study was made to investigate the effect of adenoidectomy on dentofacial skeleton in naso-respiratory dysfunction children. The clinical material compromised the 24 children in a previous study who had naso-respiratory dysfunction and 24 children who were the nasal breathing with normal occlusion. The cephalograms were taken at the initial examination and 1 year later for the control group and experimental group the paired sample statistical analysis was performed. The result were as follows. 1. In cranial base variable, difference between two groups were not statistically significant. 2. In craniofacial variable, experimental group showed brachyfacial pattern but control groups didn't show significant growth pattern. 3. In maxillary variables, experimental group showed flattening the palptal plane. 4. In mandibular variables, experimental group showed the decrease of mandibular plane angle and gonial angle. 5. In facial height variables, experimental group showed horizontal growth rotation.

Reproducibility of rotational panoramic radiography: Mandibular linear dimensions and angles

The reproducibility of nine mandibular variables (linear dimensions and angles) assessed from panoramic radiographs with the Orthopantomograph 5 (Siemens) was investigated. Attention was given to the possible influence of recording the reference number of the head positioner with one or two radiographers. Two separate exposures of three groups of patients were made under different radiographic conditions, each group representing one method. Acceptable reproducibility was observed for the vertical and angular variables, the method variance being mostly within 3% of the total variance. Horizontal variables were clearly more unreliable. No statistically significant differences were observed between the reproducibility of the right and left sides. A negative correlation was found between the angular variables within two groups. For most variables, only small differences among the methods were found. The highest reliability was obtained when the same radiographer recorded the reference number of the head positioner and made both exposures. An accuracy study on five dried skulls showed an image magnification of approximately 18% to 21% for the vertical variables, whereas the gonial angle assessed from a panoramic film was almost identical to that measured on the dried mandible.