Biomedical subjects

Claire Elcock

Publications and source records attributed to Claire Elcock.

7 recordsLinked to original sources

PubMed2006

The new Enamel Defects Index: testing and expansion.

The Enamel Defects Index (EDI) was created based on three innovative principles: (i) a basic level of the three major categories of defects; (ii) more detailed subcategories of each major category; and (iii) each category scored independently as present [1] or absent [0], simplifying decision making. The aim of this investigation was to further test the index in a number of applications and to expand it to record defect subtype and treatment need. Testing was undertaken by operators with different levels of clinical experience. A computer-assisted learning (CAL) package was developed for operator training and calibration. The index was also used on clinical photographs and high-resolution digital images of exfoliated and extracted teeth. Scoring of photographs revealed substantial intra-operator agreement. Training using the CAL package resulted in significant improvement in index use. Intra-operator reproducibility was good to excellent, and interoperator reproducibility was good for buccal surfaces on digital images. Index expansion allowed information on defect subtype, location, and treatment need to be gathered readily. The EDI has high reproducibility and allows more rapid and accurate data collection from clinical and in vitro studies than the Fédération Dentaire Internationale Developmental Defects of Enamel index.

Amelogenesis Imperfecta↗

PubMed2006

Comparison of methods for measurement of hypoplastic lesions.

Enamel hypoplasia is a quantitative defect of enamel thickness. Methods previously used for its measurement have limitations in clinical studies. The aim of this study was to investigate new methods of measurement using image analysis. Lesions on 8 teeth affected by enamel hypoplasia were quantified from study models and impression surfaces using an image-analysis system. The measurements made included lesion area and tooth surface area; from these the proportion of tooth surface area affected was calculated. For comparison, manual measurement was performed on impression surfaces and study models, using digital callipers. Images were also acquired of lesions on 12 exfoliated teeth, and the lesion area and total tooth area were calculated. For assessment of intra-operator reliability, the +/-repeatability coefficient was calculated. Measurement of the surface of lesions direct from the exfoliated teeth gave the best results overall, followed by direct image analysis of the silicone impression.

Dental Enamel↗

PubMed2005

The patterning of hypodontia in a group of young adults in Sheffield, UK.

OBJECTIVE: Identifying the patterning of congenitally absent teeth will contribute to understanding the aetiology of hypodontia. The aim of this study was to investigate patterns of hypodontia in a group of young adults in Sheffield, UK involving specific tooth types, gender differences and maxilla:mandible and left:right correlations. METHODS: The patients were 198 unrelated Caucasian young adults (86 males and 112 females) with non-syndromic hypodontia. Statistical methods included the multivariate techniques of cluster analysis and principal components analysis and associated display devices of circular dotplots and biplots. Autologistic regression was used to model the relationship of the presence or absence of a particular tooth to the status of other teeth. RESULTS: The results revealed distinct patterns of dependence. Common patterns included either third molars and second premolars missing in all quadrants and/or combinations of these two tooth types and the incisors. The gender of the patient and the severity of hypodontia did not have a significant effect on patterns of tooth type absence. If a tooth was missing, the odds ratios that the same tooth type in the horizontally or vertically opposite quadrant was also missing were some 20 times higher than if the tooth was present. For diagonally opposite quadrants the dependence was much weaker. CONCLUSIONS: These statistical techniques are valuable for increasing understanding of hypodontia and identifying groups of patients for genetic studies.

Adolescent↗

PubMed2005

Fluctuating dental asymmetry of multiple crown variables measured by an image analysis system.

OBJECTIVE: Fluctuating dental asymmetry as an indication of the effect of environmental insults during tooth development requires further investigation. The aim of this study was to assess asymmetry in tooth crown dimension for the increased range of parameters possible with image analysis compared to previous manual measurements. METHODS: Study models of 25 male and 25 female white Caucasian subjects were measured from buccal and occlusal views to determine mesio-distal, bucco-lingual, occluso-gingival and tooth surface area dimensions using image analysis. Method errors were assessed by the repeatability coefficient RC and asymmetry assessed calculating intra-class correlation coefficients between pairs of antimere teeth. RESULTS: The method errors calculated using RC were small. There was a high degree of symmetry with correlation coefficients with a range of 0.67-0.96 for linear measurements and 0.80-0.97 for tooth surface areas. No significant differences were found between the genders or between the upper and lower jaws. Asymmetry tended to follow a pattern in morphogenic tooth fields with the mesial tooth showing greater symmetry than the more distal. There were differences in the degree of symmetry among the variables measured with the mesio-distal dimension showing the greatest symmetry. CONCLUSIONS: This new technique was reliable and readily applicable, providing also a greater range of measurements. While the asymmetry generally followed a similar pattern to earlier manual studies, there were variations in the degree of symmetry between different parameters.

Adolescent↗

PubMed2004

Peripheral mechanisms for the initiation of pain following trigeminal nerve injury.

Injury to a branch of the trigeminal nerve may lead to the development of chronic pain in the affected area. The etiology of this condition is not clear, but there is strong evidence to suggest that spontaneous and mechanically induced neural discharge from the injury site plays a crucial role. In laboratory studies, we have characterized this discharge following injury to the inferior alveolar or lingual nerves and have shown a temporal association with the accumulation of neuropeptides in the damaged axons. Substance P, calcitonin gene-related peptide, and vasoactive intestinal polypeptide were all found to be capable of increasing the discharge when applied systemically, and enkephalin caused a decrease. There were also changes in the expression of specific sodium channels and nitric oxide synthase, both at the injury site and in the trigeminal ganglion. Studies on lingual nerve neuromas taken from patients undergoing nerve repair also revealed accumulation of peptides, as well as inflammatory and structural changes, but the presence of these features did not correlate directly with the reported symptoms. The application of corticosteroids to an experimental injury site decreased the mechanically induced discharge, and the anticonvulsant carbamazepine reduced the spontaneous discharge in some axons. Some of the responses that result from damage to a branch of the trigeminal nerve appear to differ from those that follow damage to other peripheral nerves. These differences will need to be taken into account when developing new therapeutic approaches for the management of injury-induced trigeminal pain.

Action Potentials↗

PubMed2003

Novel missense mutations and a 288-bp exonic insertion in PAX9 in families with autosomal dominant hypodontia.

We describe the molecular analysis of three families with hypodontia involving primarily molar teeth and report two novel mutational mechanisms. Linkage analysis of two large families revealed that the hypodontia was linked to the PAX9 locus. These two families revealed missense mutations consisting of a glutamic acid substitution for lysine and a proline substitution for leucine within the paired domain of PAX9. A pair of identical twins affected with hypodontia in a third family demonstrated a 288-bp insertion within exon 2 that resulted in a putative frameshift mutation and a premature stop codon. The insertion was associated with the loss of 7-bp from exon 2. A block of 256-bp of sequence within the insertion was completely identical to downstream sequence from the second intron of the PAX9 gene. These studies extend the spectrum of mutations in PAX9 associated with hypodontia to include heretofore undescribed categories, including missense mutations.

Amino Acid Sequence↗

PubMed2003

Incisor crown shape and crowding.

The aim of this study was to investigate correlations between the shape of mandibular incisor crowns and crowding. Study models of 50 untreated white subjects (25 men and 25 women) with varying degrees of crowding were studied. The lower incisors were sectioned and imaged at the contact point and midpoint levels, and the mesiodistal width was measured. Crowding was quantified by using both Little's irregularity index and anterior tooth size-arch length discrepancy. The ratio of the 2 mesiodistal widths was correlated with Little's irregularity index and anterior tooth size-arch length discrepancy. In the women, the ratio showed correlations of 0.52 (P =.008) and 0.55 (P =.005) for central and lateral incisors, respectively, with anterior tooth size-arch length discrepancy. No predictors of lower incisor crowding could be established from mandibular incisor crown shape in this study.

Adolescent↗