Mandibular Size Research Articles

Feeding habits of Plio-Pleistocene large carnivores as revealed by the mandibular geometry

ABSTRACT Extant large members of the order Carnivora show high variability in feeding adaptation. Morphology of their teeth and skull is a primer to predict diet in both extant and extinct species. Here I present a complete geometric morphometric survey of mandible of large (>7 kg) Carnivora in order to make paleoecological predictions for selected Plio-Pleistocene taxa. Mandibular size and shape data support a strong differentiation between families but also convergence due to functional adaptations to hunting prey. Linear discriminant function analyses are performed in order to obtain dietary predictions on fossil taxa with statistical accuracy. There is a high level of discrimination among dietary categories, especially when subsets of predator and non-predator carnivores are analyzed separately. New insights emerge for Plio-Pleistocene fossil taxa whose paleoecology was previously inferred. Mandibular size and shape data are accurate dietary predictors in large carnivores, with size being more relevant to clarify adaptations in killing prey of different size classes.

Ecological Adaptations of Mandibular Form in Fissiped Carnivora

Among mammals, Carnivora presents an ideal group for investigating the complex interplay between functional adaptation and phylogenetic history. Here we explore mandibular form and its relationship to ecology and phylogeny using geometric morphometrics applied to mandibles of extant Carnivora. Both mandibular size and shape discriminate carnivoran ecological adaptations (diet, membership to small or large predatory guilds), but the interplay of morphology with phylogenetic history is profound. In general, families do not overlap in mandible shape; however, Viverridae, Herpestidae, Canidae, and Mustelidae exhibit functional and morphological convergence. Mandibular allometric trajectories are distinct among families and ecological categories. Our findings suggest that variability in mandibular form among Carnivora is primarily influenced by major evolutionary changes occurring at the family level and less, but significantly so, by ecological adaptations. Small generalist feeders (insectivores, omnivores) exhibit stronger convergence in mandibular shape than highly specialized predators; bigger taxa, such as bears, evolved unique morphologies constrained by allometric scaling. Thus, the findings of this study serve to demonstrate how ecological factors mold anatomical structures in similar ways to serve similar functions. As such, carnivoran species can be usefully grouped into functional ‘guilds’ in eco-morphological studies irrespective of their phylogenetic history.

Analysis of Differences in the Cranial Base and Facial Skeleton of Patients with Lambdoid Synostosis and Deformational Plagiocephaly

Earlier investigations suggest that the morphologic features of patients with lambdoid synostosis include ipsilateral occipital flattening, an ipsilateral mastoid prominence, downward cant of the posterior skull base to the affected side, and contralateral hemifacial deficiency. These features are absent in patients with deformational plagiocephaly. The authors hypothesize that significant differences in craniofacial morphology exist between patients with lambdoid synostosis and those with deformational plagiocephaly. Craniometric measurements were performed on patients with unilateral lambdoid synostosis (n = 9) and deformational plagiocephaly (n = 12). Measurements were performed on affected and unaffected sides and included posterior fossa deflection angle, petrous ridge angle, middle cranial fossa and anterior cranial fossa area, temporomandibular joint displacement, and maxillary and mandibular dimensions. Appropriate statistical tests were performed. Statistically significant differences in posterior fossa deflection angle, petrous ridge angle, and middle cranial fossa were found between groups. Lambdoid synostosis patients demonstrated a larger petrous ridge angle (p = 0.0001) and middle cranial fossa (p = 3.37 × 10(-6)) on the unaffected side. Deformational plagiocephaly patients exhibited no discrepancies between sides. The mean posterior fossa deflection angle was 10.55 degrees for the lambdoid synostosis group and 3.59 degrees for the deformational plagiocephaly group (p < 0.0001). All lambdoid synostosis patients had deviation of the posterior cranial fossa toward the affected side. Deformational plagiocephaly patients had variable deflection. All lambdoid synostosis patients demonstrated marked posterior displacement of the contralateral temporomandibular joint. Deformational plagiocephaly patients had either symmetric temporomandibular joint position (75 percent) or slight contralateral posterior displacement (25 percent). Mandibular size was not significantly different between groups. Patients with lambdoid synostosis and deformational plagiocephaly manifest significant differences in cranial base morphology, contributing to the phenotypic differences seen in these two groups of patients.

Sabotaging behaviour and minimal latex of Asclepias curassavica incur no cost for larvae of the southern monarch butterfly Danaus erippus

1. The southern monarch, Danaus erippus, uses mainly Asclepias curassavica as its host in the Neotropics, a plant species bearing articulated anastomosing laticifers. When artificially severed, A. curassavica has been shown to release significantly less latex than other Asclepias species.2. The present study tested the hypothesis that sabotaging behaviour changes during the ontogeny of D. erippus and recorded latex outflow of A. curassavica during sabotaging and feeding. Larvae displayed vein‐cutting behaviour, which was initially observed in the second instar, became more pronounced in the third and fourth instars, and less frequent in the fifth instar. When present, latex outflow was never more than 1 µl at a time during either vein cutting or feeding, regardless of the instar.3. Mandibular and midrib morphometrics revealed that larvae selected thicker midrib sites for severing as instars progressed; however, no correlation between mandibular size and midrib size severed was found within instars.4. Costs of sabotaging behaviour and the effects of A. curassavica latex outflow on D. erippus larvae were also examined. Sabotaging behaviour did not incur growth costs for larvae, and only latex exudation volumes at least 10‐fold greater than those observed due to D. erippus sabotaging or feeding, caused significantly higher larval mortality than controls.5. Since latex outflow is minimal or non‐existent in A. curassavica, sabotaging behaviour in D. erippus is mostly limited by morphological constraints and is probably driven by chemical stimulants rather than latex defence. In turn, latex does not constitute a major defence of A. curassavica against D. erippus.

A comparative study of incisor procumbency and mandibular morphology in vampire bats

The three species of vampire bats (Phyllostomidae: Desmodontinae), Desmodus rotundus, Diaemus youngi, and Diphylla ecaudata, are the only mammals that obtain all nutrition from vertebrate blood (sanguinivory). Because of the unique challenges of this dietary niche, vampire bats possess a suite of behavioral, physiological, and morphological specializations. Morphological specializations include a dentition characterized by small, bladelike, non-occlusive cheek teeth, large canines, and extremely large, procumbent, sickle-shaped upper central incisors. The tips of these incisors rest in cuplike pits in the mandible behind the lower incisors (mandibular pits). Here, we use microCT scanning and high-resolution radiography to describe the morphology of the mandible and anterior dentition in vampire bats, focusing on the relationship between symphyseal fusion, mandibular pit size, incisor size, and procumbency. In Desmodus and Diaemus, highly procumbent upper incisors are associated with relatively small mandibular pits, an unfused mandibular symphysis with substantial bony interdigitations linking the dentaries, and a diastema between the lower central incisors that helps to facilitate the lapping of blood from a wound. In Diphylla, less procumbent upper incisors are associated with relatively large mandibular pits, a completely fused mandibular symphysis, and a continuous lower toothrow lacking a central diastema. We hypothesize that symphyseal morphology and the presence or absence of the diastema are associated with the angle of upper incisor procumbency and mandibular pit development, and that spatial constraints influence the morphology of the symphysis. Finally, this morphological variation suggests that Diphylla utilizes a different feeding strategy as compared to Desmodus and Diaemus, possibly resulting from the functional demands of specialization on avian, rather than mammalian, blood.

Evaluation of mandibular length in subjects with Class I and Class II skeletal patterns using the cervical vertebrae maturation

The aim of this study was to compare the mandibular size in boys and girls with Class I and Class II skeletal patterns, taking into consideration the bone maturation stage, as defined by the cervical vertebrae maturation. One hundred and sixty cephalometric radiographs were obtained from subjects (aged between 7 and 12 years) with Class I or Class II skeletal patterns, according to the ANB angle and WITS appraisal. The Class I sample consisted of 80 subjects (40 boys, 40 girls). The Class II sample also consisted of 80 subjects (40 boys, 40 girls). On a cross-sectional basis, mandibular length (Co-Gn) was compared between groups and genders. The between-stages changes were also evaluated, with the cervical vertebrae analysis used for establishing the bone maturation stages at CS2, CS3, CS4 and CS5. The results were statistically analyzed by the Kruskal-Wallis test. The mandibular length differed between skeletal patterns only at the earlier stages of development. In the Class I pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS4 and CS5, whereas in the Class II pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS3 and CS4. The present results indicate a sexual dimorphism in the mandibular length at almost all stages of bone maturation, in exception of the CS5 stage in Class II.

Effect of a Syndromic Diagnosis on Mandibular Size and Sagittal Position in Robin Sequence

Despite its pathogenic heterogeneity, it is often assumed that the small mandible in a neonate with Robin sequence will not grow normally. The purpose of this study was to determine mandibular length and position in patients with nonsyndromic versus syndromic Robin sequence. Lateral cephalograms of 51 children with Robin sequence were analyzed. Group I consisted of nonsyndromic (NS) subjects and group II consisted of subjects with the 4 most common syndromic (S) diagnoses. Cephalometric measurements included sella-nasion-A point (SNA), sella-nasion-B point (SNB), sella-nasion-pogonion (SNPg), articulare-gonion-pogonion (ArGoPg), temporomandibular joint-pogonion (TmPg), articulare-gonion (ArGo), and gonion-pogonion (GoPg). Differences between groups and subgroups were compared using t test. There were 26 NS patients (mean age, 6.8 yrs) and 25 S patients (mean age, 8.7 yrs); mean age was statistically different between groups (P = .04); therefore, cephalometric measurements were compared with age-matched normal values. Syndromes included Stickler (n = 10), bilateral facial microsomia (n = 8), velocardiofacial (n = 4), and Treacher Collins (n = 3). SNA was statistically different from normal in both groups (NS, P = .017; S, P = .007); however, SNB was not different from normal for either group (NS, P = .175; S, P = .537). SNPg (0.007) was significantly greater than normal in NS (P = .007) but not in S (P = .702) patients. SNA, SNB, and SNPg were not significantly different between groups. In both groups, mandibular length was short (P = .00), especially in S patients (P = .049), mandibular body was small (NS, P = .00; S, P = .00), and the gonial angle more obtuse (NS, P = .006; S, P = .000) than normal. Ramus length was significantly shorter than normal only in S patients (P = .019). Mandibular length (TmPg) was smaller than normal in all S subgroups but with wide variability. There were statistically significant differences among S subgroups with respect to mandibular sagittal position (SNB, P = .00; SNPg, P = .00) and mandibular length (TmPg, P = .008). There were no differences in S subgroups with respect to age, SNA, ArGo, GoPg, and ArGoPg. Mandibular morphology and position are variable in Robin sequence, based on the presence and type of associated syndromic diagnosis.

Standardizing interarch tooth-size harmony in a Syrian population.

The Bolton analysis is considered to be a good indicator for evaluating the degree of intermaxillary tooth-size harmony, but the possibility of ethnic variation of these values should be examined. Thus, the aim of this study was to calculate both the anterior and overall ratios of mandibular and maxillary tooth sizes for a Syrian sample of harmonious permanent dentitions and to compare these ratios with the data from the Bolton and the Michigan studies. In plaster models of 55 Syrian patients (11-22 years) with neutral occlusion (Angle Class I), harmonious overjet and overbite, no reduction of mesiodistal tooth width or missing teeth, the mesiodistal widths of each tooth from the incisors to the first permanent molars were measured in both arches. In the statistical data analysis, the anterior and overall ratios were calculated according to Bolton. The results for the anterior ratio (78.99 +/- 2.18) and the overall ratio (92.26 +/- 2.06) showed no statistically significant differences by sex (P > .48). These values and the degree of variation were similar to the original data by Bolton. Both studies differed considerably from the values of the anterior ratio found in the Michigan University study, which also shows a higher degree of variability. Nevertheless, the overall ratios of all three studies were very similar. Therefore, the interarch tooth-size analysis and values for a harmonious dentition developed by Bolton can also be transferred to an Arabian or at least a Syrian population.

Comparison of two β-tricalcium phosphate composite grafts used for reconstruction of mandibular critical size bone defects

Comparison of two β-tricalcium phosphate composite grafts used for reconstruction of mandibular critical size bone defects

Permanent reduction of mandibular size and bone stiffness induced in post-weaning rats by cyclophosphamide

It has been previously reported that several doses of cyclophosphamide (CPA) reduce body weight gain, diaphyseal torsional strength and longitudinal femoral growth in the growing rat. The present study was thus designed to estimate both the initial and the possible long-term effects of CPA treatment, by analyzing mandibular dimensions and biomechanical performance of the bone in adulthood in rats treated with the drug around weaning. Female Sprague–Dawley rats ( N = 20), 26 d of age, received 100 mg/kg of CPA by the intraperitoneal route during days 0, 7 and 21 of the experimental period. Controls (C) received saline. Groups of rats were sacrificed at day 28 to estimate initial changes induced by the drug and on day 126 in order to determine long-term effects. The dimensions of the excised mandibles were measured directly between anatomical points; the geometry and material biomechanical quality of mandibular bone were assessed using a three-point bending mechanical test in an Instron Universal Testing Machine model 4442. CPA reduced body weight, body length and mandibular size (posterior part of the bone) significantly, when the parameters were measured at day 28. They did not recover with time, which means that catch-up growth did not occur and that the overall growth of the body was permanently affected by the drug. CPA treatment was also associated with a marked depression of the natural increase in the mandibular bone mass (cross-sectional area). The bending cross-sectional moment of inertia of the fracture sections (xCSMI) was also negatively affected by treatment. Significant decreases of both ultimate load and stiffness were also observed. The above structural parameters did not recover enough with time to attain control values at the end of the study. The intrinsic stiffness ( E) of the mandibular bone was not affected by treatment. These findings suggest that CPA treatment during early postnatal life causes permanent changes in mandibular morphology and affects the adaptation of mandibular bone architecture to body growth, thus not allowing complete compensation at the end of the study because of an inadequate distribution of the resistive material through its cross-section rather than a qualitative impairment of cortical bone.

Glenoid Fossa Position in Class II Malocclusion Associated with Mandibular Retrusion

To assess the position of the glenoid fossa in subjects with Class II malocclusion associated with mandibular retrusion and normal mandibular size in the mixed dentition. A sample of 30 subjects (16 male, 14 female), age 9 years +/- 6 months, with skeletal and dental Class II malocclusion associated with mandibular retrusion, normal skeletal vertical relationships, and normal mandibular dimensions, was compared with a matched group of 37 subjects (18 male, 19 female) with skeletal and dental Class I relationships. The comparisons between the Class II group and the control group on the cephalometric measures for the assessment of glenoid fossa position were performed by means of a nonparametric test for independent samples (Mann-Whitney U-test, P < .05). Subjects with Class II malocclusion presented with a significantly more distal position of the glenoid fossa, when compared with the control group as measured by means of three parameters (GF-S on FH, GF-Ptm on FH, and GF-FMN). A posteriorly displaced glenoid fossa is a possible diagnostic feature of Class II malocclusion associated with mandibular retrusion. An effective cephalometric measurement to evaluate glenoid fossa position is the distance from the glenoid fossa to the frontomaxillonasal suture (GF-FMN).

Bacular variation and allometry in the western martenMartes caurina

Many sexually-selected structures are variable and positively allometric relative to body size. For the western martenMartes caurina Merriam, 1890 from Vancouver Island, British Columbia, we investigated variation in the baculum compared with other bones and allometry of bacular to body size. Carcass length did not differ, and humeral and mandibular lengths differed little (< 1 and 2%, respectively), between age groupings < 1 and ≥ 1 yr old. In contrast, bacular length increased by 16%, and thickness by 29% (mid shaft) and 86% (basal) between those groupings, and thickness and mass continued to grow after the second year of life. Controlling for body size, bacular size varied more than humeral or mandibular size (CV for linear variables ∼4–8% for baculum, ∼2% for humerus or mandible). Some positive static allometry of bacular size to body size was found, but correlations between bacular and body size were weak (r=0.3–0.4). So penile size as related to bacular size could be a reliable but imprecise quality indicator during copulation. Weak polygamy (serial promiscuity), complex copulatory mechanisms, and high energetic costs of reproduction, likely select for multiple cues in mate-choice by females, not just penile cues affected by bacular size or shape.

Comparative observations on the tooth root morphology of Gigantopithecus blacki

The extinct great ape Gigantopithecus blacki from the middle Pleistocene of China and Vietnam is known only from dental and mandibular remains, and its dietary specializations remain contentious. Here, for the first time, we describe the root morphology in G. blacki using computed tomography and three-dimensional image processing. We quantify the tooth root lengths and surface areas of the female G. blacki mandible No. 1 from the Liucheng Cave and compare it to a sample of extant great apes and humans, as well as the giant panda ( Ailuropoda melanoleuca) and the American black bear ( Ursus americanus). The results show that, in G. blacki, the pattern of mandibular root numbers—particularly that of the premolars—corresponds with that of Gorilla gorilla, Pan troglodytes, and Pongo pygmaeus. However, G. blacki can be distinguished from the extant hominids by having relatively higher values for postcanine root length and surface area, both absolutely and relative to mandibular size (except for premolar root lengths of humans). The relatively large postcanine root surface areas, which are most similar to A. melanoleuca, suggest that the dentition of G. blacki was adapted to sustaining relatively large occlusal forces needed to fracture mechanically resistant foods such as bamboo.

A novel method to determine larval mandibular wear of the African stalk borer, Eldana saccharina Walker (Lepidoptera: Pyralidae)

The African stalk borer, Eldana saccharina Walker (Lepidoptera: Pyralidae), is the most significant indigenous pest on sugarcane in South Africa (Atkinson 1980; Conlong 2001). Currently, crop management and cultivar resistance in sugarcane remain the most widely accepted control methods for E. saccharina in South Africa (Nuss & Atkinson 1983; Keeping 2006). Following emergence, E. saccharina larvae graze up and down the sugarcane stalk or disperse onto dead leaf sheaths for several days until old enough and, presumably, with sufficiently strong mandibles to bore into the plant (Leslie 1993). As young larvae use their mandibles to chew through the sugarcane stalk, abrasion of the mandibles’ chewing surface is inevitable and could ultimately reduce feeding efficiency. It is recognized that fertilization with silicon (Si) can enhance the resistance of plants to insect attack, including that of sugarcane to E. saccharina (Keeping & Meyer 2002, 2006; Kvedaras et al. 2007). Testing the effects of this treatment highlighted a need to measure the extent of wear on larval mandibles. While there have been studies that have reported wear of chewing mouthparts of insects, they have either failed to describe the method (Djamin & Pathak 1967), used a method which can only be applied to mandibles of the same size (Raupp 1985) or have not accounted for differences in mandibular size between individuals (Kokko et al. 1993). The objective of this study was to develop an accurate and repeatable method to measure the mandibular wear experienced by E. saccharina larvae fed on commercial sugarcane. It is anticipated that the method will be useful in quantifying mandibular wear in other adult and larval chewing insects. A method is described that uses a simple image analysis technique to determine the loss of feature on the chewing edge of the mandible. Ten third instar E. saccharina larvae were randomly sampled from commercial sugarcane cultivars N26 and N11 grown at the South African Sugarcane Research Institute (SASRI), Mount Edgecombe, KwaZulu-Natal. Larvae were placed directly into 70 % alcohol until required. Prior to analysis, the larvae were removed from the alcohol, allowed to air dry for 10 min and their heads removed under a light microscope. The labrum was removed and using a fine tipped dissecting needle, the mandibles were carefully pried apart to avoid chipping and air-dried for 1 h. The heads were mounted with their mandibles in a horizontal position using black, double-sided carbon tape (12 mm × 20 m, Structure Probe Inc., West Chester, U.S.A.), on standard aluminium scanning electron microscopy (SEM) stubs. Debris on the mandibles was removed using a fine dissection needle and a fine camel hair brush. The specimens were gold coated for 3.5 min (approx. 6 nanometres thickness) using a gold sputtercoater (Polaron E5100 coating unit and E5500 film thickness moniter, Polaron Equipment Limited, Watford Hertfordshire, U.K.). Specimens were viewed using a scanning electron microscope (Leo 1450 Scanning Electron Microscope, Cambridge, U.S.A.) and the images captured digitally. Each mandible has two scissorial teeth and a proximal tooth, the mola. The degree of wear of a mandible was quantified using an algorithm to obtain a mean square error (MSE), as follows. The (x,y) coordinates (x = horizontal, y = vertical) of the pixels in the digital image that represent the chewing edge of the mandible, from the distal to the proximal convex protrusion (distal scissorial teeth and mola tooth) (Fig. 1), were subjected to linear regression. As the chewing edge of each mandible is carefully orientated under a microscope in a vertical direction, the deviation in the X-axis is the most relevant measurement, hence the best-fitting straight line is calculated as:

Effects of treatment with a combined maxillary protraction and chincap appliance in skeletal Class III patients with different vertical skeletal morphologies

Several cephalometric studies and case reports have described the effects of treatment with a maxillary protraction appliance (MPA) and chincap appliance. The purpose of this investigation was to identify differences in the response to treatment with a combined MPA and chincap in skeletal Class III patients with different vertical skeletal morphologies: short- (low mandibular plane angle) and long- (high mandibular plane angle) face types. The cephalograms used in this study were of 42 Japanese girls at the beginning of treatment (T0, mean age 10.1 years) and at removal of the appliance (T1, mean age 11.5 years). The subjects were divided into two groups (short and long face) according to the inclination of the mandibular plane at T0. Total anterior face height, upper and lower face height, occlusal plane, and gonial angle were significantly larger in the long-face group at T0. In both groups, significant increases in SNA, maxillary size (A'-Ptm'), and ANB were noted during treatment. Compared with the long-face group, the short-face group showed greater forward displacement and size increment of the maxillary body, while there were no significant differences in changes in mandibular size or position between the two groups. These results indicate that the vertical dimensions of the craniofacial skeleton are important factors in the orthopaedic effects of a MPA and chincap and the prognosis for skeletal Class III patients.

歯・顎顔面用コーンビームＣＴ撮影による咽頭部形態評価に関する検討‐下顎骨形態との関連について‐

A detailed functional and morphological evaluation of the pharynx, especially its relationship with the mandible, is essential for the surgical orthodontic treatment and diagnosis of sleep apnea syndrome. The present study assessed the correlation between pharyngeal and mandibular morphology in 45 adult Japanese women (average age, 27.9 years). Nine measurements in the pharynx, hyoid bone, and epiglottis were analyzed by conebeam computed tomography (CBCT), and six parameters of mandibular morphology were analyzed using lateral cephalograms. A positive correlation was found between pharyngeal space volume and gonial angle, and between pharyngeal vertical length and the mandibular plane. In addition, the results suggested that both antero-posterior position of the hyoid bone and epiglottis width are related to mandibular size. This study suggested that CBCT is a useful tool for three-dimensional evaluation of the pharynx. The results provide clinically valuable information for the diagnosis and treatment of surgical orthodontics, and enhance our understanding of sleep apnea syndrome.

Three‐dimensional sonographic determination of normal fetal mandibular and maxillary size during the second half of pregnancy

To explore the various ways of obtaining fetal maxillary and mandibular size with three-dimensional (3D) ultrasound, with a view to developing a tool for identifying minor anomalies in the lower facial region. Serial 3D sonographic measurements of the fetal jaws were made in 126 normal singleton pregnancies at 18-34 weeks of gestation for determination of degree of maxillary and mandibular protrusion, maxillary and mandibular corpus lengths, mid- and lower facial depths and maxillary and mandibular curvature. In a sub study the reproducibility of the measurements was evaluated. The coefficient of variation in the reproducibility study varied between 7.1 and 10.5%. For all parameters except maxillary and mandibular protrusion, there was a significant gestational age-related increase. Ratios of maxillary/mandibular protrusion, maxillary/mandibular corpus lengths, mid-/lower facial depths and maxillary/mandibular curvature all showed a significant gestational age-related decrease, with the most distinct decrease in the mid-/lower facial depth ratio. 3D sonographic measurement of the fetal maxilla and mandible demonstrated an acceptable intraobserver variability for all measurements. The mid-/lower facial depth ratio appears to be most valuable in determining abnormal mandibular development.

Smaller mandibular size in infants with a history of an apparent life-threatening event

To examine small mandibular size and preference for a hand-to-chin posture as salient characteristics in infants with a history of an apparent life-threatening event (ALTE). This was a prospective case-control study of term infants, from birth to 6 months of age, admitted post-ALTE and matched 1:2 with healthy control infants (age within 2 weeks and weight within 0.5 kg). Infants with confirmed gastroesophageal reflux and congenital anomalies, including severe micrognathia, were excluded. Infants with a history of an ALTE (n = 25) were matched to 47 healthy controls. Infants with a history of an ALTE had mandibular indices (larger index indicates a smaller mandible) that were 3.8 mm greater on the left side (95% CI: 2.0-5.6, P < .001) and 4.2 mm greater on the right side (95% CI: 2.7-5.6, P < .001) adjusting for length and non-white race. Controlling for matching and length, a 1-mm increase in the average mandibular index increased the odds of an ALTE by 62% (OR = 1.62, 95% CI: 1.22-2.44, P < .001). Smaller mandibular size was associated with ALTE, suggesting airway obstruction as a potential cause of ALTE. The association of this characteristic with ALTE also offers the potential for prospective quantification of ALTE risk.

Comparison of Facial Morphology in Two Populations with Complete Unilateral Cleft Lip and Palate from Two Different Centers

To identify differences in craniofacial morphology of two populations with a history of complete unilateral cleft lip and palate (UCLP) treated under different protocols. Retrospective longitudinal cohort study. Cleft Center of the University of Nijmegen, The Netherlands, and the Cleft Lip and Palate Program, The Hospital for Sick Children, Toronto, Canada. Nineteen patients (16 male, 3 female) from Nijmegen and 19 patients (16 male, 3 female) from Toronto. Each patient was matched for sex and age with a patient from the other group. The mean ages at which lateral cephalometric radiographs were available for the Nijmegen group were 5.5, 9.9, and 18.3 years, while for the Toronto group these were available at mean ages of 5.3, 10.1, and 18.3 years, respectively. Eighteen patients from the Nijmegen group received an alveolar bone graft at a mean age of 9.5 years (range 8.2 to 13.5 years). None of the patients from Toronto received bone grafts. Eighteen cephalometric variables per radiograph were calculated at each time registration, using Dentofacial Planner cephalometric software. Statistical evaluation was performed with repeated-measures analysis of variance. No differences were seen in the maxillary measurements. The patients in the Toronto group had significantly larger mandibles at all three time registrations. The Nijmegen and Toronto protocols resulted in similar maxillary projections in patients with UCLP. Comparison of data from other studies supports the contention that the larger profile convexity of the Nijmegen group is a reflection of a genetically determined smaller mandibular size in the Dutch population.

Intraspecific variability and phylogenetic relationships of the Pleistocene shrewSorex runtonensis (Soricidae)

Intraspecific variability of the Pleistocene speciesSorex runtonensis Hinton, 1911 from different Polish and Russian (Caucasus Mts.) localities and its relationships to Recent red-toothed shrews of similar body size and mandibular morphology,S. caecutiens Laxmann, 1788 andS. tundrensis Merriam, 1990, are explained on the grounds of multivariate statistics. The remains ofS. runtonensis from different localities form a single group and differ fromS. caecutiens. They resembleS. tundrensis by the first canonical root related to a mandibular size and proportions. This may indicate thatS. runtonensis andS. tundrensis are closely related but separated components of the species complextundrensis.