Tooth Development Associated with Mutations in Hereditary Vitamin D-Resistant Rickets.

Hereditary vitamin D-resistant rickets (HVDRR) is a rare genetic disorder caused by mutations at the level of the vitamin D receptor ( VDR) gene. The disease is characterized by refractory hypocalcemia, elevated serum levels of 1,25-dihydroxy-vitamin D, retarded growth, sparse body hair (sometimes alopecia), premature tooth loss, enlarged pulp chambers, thin dentine, and hypoplastic enamel. The aims of this study were 1) to document the dental development of children with HVDRR in association with the mutation type within the VDR and 2) to evaluate the association between dental development and the timing of and response to HVDRR treatment. Genome analysis was performed for 4 affected children (2 y 2 mo to 6 y 8 mo) under treatment with high doses of vitamin D and calcium. Longitudinal records of clinical and radiographic data on their dental development were assessed in relation to genetic profile and response to treatment. Treatment success depended on the position of the mutation within the VDR protein: children with the p.R391S mutation had a favorable outcome but maintained alopecia totalis, while 1 child with the p.H397P mutation and normal hair had no response to very high doses of vitamin D. The primary incisors, formed prenatally and first to emerge, were missing in 3 children and mobile in 1 child; parents reported loss within months posteruption. Posterior teeth were present, having erupted after treatment initiation. Hypoplastic enamel in emerging teeth was associated with late treatment onset. Mutation type in the VDR gene appears to be related to differences in the disease phenotype and response to treatment. Dental development represents an indicator of the disease process, initially protected by maternal blood levels of calcium and later restored by therapeutic supplies that normalize these levels. Knowledge Transfer Statement: Two novel mutations were associated with different HVDRR phenotypes, one of which responded positively to treatment. Early detection of the mutation should help pediatricians forecast treatment protocol and response. The results also highlight the direct relationship between dental development and blood calcium levels, underscoring the importance of early diagnosis and treatment of HVDRR to minimize the loss of primary teeth and reduce structural abnormalities of permanent teeth.

Sex prediction from morphometric palatal rugae measures.

While abundant research has been conducted on palatal rugae (PR), the literature pertaining to the sex dimorphism of the palatal rugae and their use for sex prediction is inconclusive. Moreover, palatal rugae have been classified into categories based on length, shape, direction and unification but accurate rugal morphometric linear and angular measurements have not yet been reported. OBJECTIVE: The aims of this study were to -1- assess the dimensions and bilateral symmetry of the first three palatal rugae in an adult population and -2- explore sex dimorphism and the ability to predict sex from palatal rugae measurements. MATERIALS AND METHODS: The maxillary dental casts of 252 non-growing subjects (119 males, 130 females, mean age 25.6 ± 7.7 years) were scanned using a laser system (Perceptron ScanWorks® V5). Angular and linear transverse and anteroposteior measures of the first three palatal rugae were recorded. Independent samples t-tests and paired samples t-tests were used to test for side related differences and sex dimorphism. Multiple logistic regression was employed to model sex using associated palatal rugae measures. RESULTS: Palatal rugae exhibited lateral asymmetry in the majority of bilateral measures. Males presented with larger values for 9 out of 28 parameters. Four linear rugae measurements and one angular measurement together correctly classified 71.4% of the subjects in their true gender. CONCLUSIONS: Morphometric palatal rugae measurements demonstrated promising usefulness in sex prediction. Recording morphometric linear and angular measures is recommended as an adjunct to the commonly used classification based on the shapes of rugae.

Palatal rugae morphology in an adult mediterranean population.

BACKGROUND: The use of the palatal rugae in forensic odontology is based on their unique and individual characteristics. Few studies have assessed the palatal rugae in Mediterranean populations and none in the Lebanese population. OBJECTIVE: Assess the shape and other morphological features of the palatal rugae in a Lebanese adult population, and compare them with reported similar features in other populations. MATERIALS AND METHODS: Rugae characteristics were assessed on the maxillary dental casts of 217 non-growing subjects (95 males, 122 females, age 25.5 ± 7.6 years) according to guidelines established by Thomas and Kotze (1983) and Lysell (1955). The overall number of rugae and numbers of primary rugae (> 5mm in length), secondary rugae (3-5mm) and fragmentary rugae (2-3mm) on either side were recorded. Rugae were classified according to shape, direction and presence of unification. Z-tests were used to compare the proportions between right and left sides and between genders. The mean numbers of rugae in each category were compared with independent samples t-tests between males and females; paired samples t-tests were employed to compare mean numbers of rugae in each category between right and left sides. The data were compared with published reports on other Mediterranean cohorts. RESULTS: The average number of rugae was 7.7 per individual, 3.81 on the right and 3.89 on the left. Curved, wavy and straight rugae patterns were equally common (one third each). The spatial direction of most rugae (49.3%) was backward. Circular, non-specific and convergent rugae were rare (< 2% each). Rugae numbers (total, primary, secondary, fragmentary) were symmetrical but shape, direction and the occurrence of convergence were asymmetrical (p < 0.05). None of the examined characteristics showed gender dimorphism. Tabulated comparisons disclosed the equality of rugae patterns as major differences with findings from other Mediterranean studies. CONCLUSIONS: The palatal rugae in the Lebanese population display shape distinct from other reported Mediterranean and non-Caucasian populations. Studies in large samples and primary comparisons with other Mediterranean populations are warranted.

Association among geometric configurations of palatal rugae.

BACKGROUND: The associations between the length and morphological shape-related characteristics of palatal rugae have not been fully explored. OBJECTIVE: We aimed to assess the possible association among various geometric configurations of the palatal rugae in an adult population. MATERIALS AND METHODS: The maxillary dental casts of 217 non-growing subjects (95 males, 122 females, mean age 25.5±7.6 years) were scanned (laser scanning system Perceptron ScanWorks® V5) and digitized for linear measurements. The casts were also surveyed for visual categorization into curved, wavy, straight and other topographical forms, along with spatial direction of the rugae and the presence of unification. The rugae were categorized as primary, secondary, and fragmentary based on their lengths (> 5mm, 2-3mm, < 2mm, respectively). Chi square and one-way ANOVA and post-hoc tests were used to compare the palatal rugae groupings. RESULTS: Primary and backward-directed rugae prevailed in the total sample (84.7% and 49.3%, respectively). Wavy form was dominant among primary lengths, while straight form was associated with the shorter secondary and fragmentary groups (p=0.0042). Absence of unification was the norm (88.8%). CONCLUSIONS: Associations of length and shape characteristics among palatal rugae combine wavy patterns with increased length, and straight forms with shorter folds. These features contribute to the definition of ruga individuality in combination rather than separately.

New insights on age-related association between nasopharyngeal airway clearance and facial morphology.

OBJECTIVES: To evaluate the relation between adenoid hypertrophy and facial morphology across age in a pediatric population. SETTING AND SAMPLE POPULATION: The American University of Beirut Department of Otolaryngology. Two-hundred consecutive children (age 6.00 ± 2.62 years) referred from the Pediatric Otolaryngology unit to the Orthodontic division and requiring a lateral cephalogram for adenoid hypertrophy assessment. METHODS: Cephalometric measurements included relations among cranial base, maxilla and mandible, and airway clearance measured from adenoid to soft palate (AD). The children were classified into two age groups, Group 1: ≤ 6 years (n = 124) and Group 2: ≥ 6.01 years (n = 76), and also stratified in four subgroups (A, B, C, D) based on maxillo-mandibular divergence (palatal to mandibular plane angle, PP-MP): A- PP-MP ≤ 27.5°, n = 34; B- 27.5° < PP-MP ≤ 32°, n = 68; C- 32°

Monitoring growth during orthodontic treatment.

The relationship between somatic growth and orthodontic treatment has been limited to the evaluation of body height and skeletal age relative to craniofacial development. The aim of this study was to evaluate the correlation of anthropometric and biochemical measures of general growth with facial and occlusal changes during the early treatment of Class II Division 1 malocclusion. Findings are reported from 46 children, ages 7.20 to 12.85 years (skeletal ages, 5.75 to 12.75 years), who are enrolled in a prospective clinical trial. Body and knee heights were measured monthly, with a Holtain stadiometer and a Knee Height Measuring Device, respectively. Every three months, serum levels were measured of the hormone dehydroepiandrosterone sulfate (DHEAS), an androgen associated with growth in midchildhood, and osteocalcin, an indicator of bone turnover. Significant correlations existed between knee height and various occlusal measurements, but mandibular length was not significantly correlated with knee height and DHEAS levels. Knee height correlated significantly (P < .05) with DHEAS and osteocalcin only in 46% and 37% of the children, respectively. The results indicate that the evaluated biochemical measures, at the time intervals considered, may not increase the accuracy of growth depiction by physical measures alone (height and skeletal maturation).