Biomedical subjects

Alan H Brook

Publications and source records attributed to Alan H Brook.

8 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

Hypoplastic enamel defects and environmental stress in a homogeneous Romano-British population.

This study investigated hypoplastic enamel defects in a well-defined sample of Romano-Britons from the 3rd to the 5th century AD and compared the findings with a modern British sample investigated by the same authors. All 178 excavated skulls with intact dentitions were examined for hypoplastic defects using the Federation Dentaire International (FDI) Developmental Defects of Enamel Index criteria. Histopathological and microradiographic sections were prepared of 5 teeth. Hypoplastic defects were found in the teeth of 37% of skulls, with 25% having 4 or more teeth affected. The teeth most frequently involved were canines. Of the defects, 75% were horizontal grooves, 12.7% were pitting, and 7.1% were areas of missing enamel. The location of defects was 82% buccal, 16.5% lingual, and 1.2% occlusal. The reproducibility of diagnosis was 84%. Microscopic and microradiographic investigations showed areas of hypomineralization of enamel and wide zones of interglobular dentine related to the hypoplastic grooves. There was higher frequency, different morphology, and greater severity of hypoplastic enamel defects compared with the modern British sample. The defects may be related to repeated environmental stresses between the ages of 2 and 6 yr. Identified environmental stresses in these Romano-Britons, including high lead ingestion, poor nutrition, and recurrent infections, may be important etiological factors for the enamel defects.

Adolescent↗

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↗

PubMed2006

A randomized controlled trial of outreach placement's effect on dental students' clinical confidence.

This randomized controlled trial compared the effects of outreach placement with traditional, exclusively dental school-based clinical experience on students' confidence in providing treatment for patients presenting with common dental problems. Senior dental students (n=49) were allocated at random to existing dental school-based clinics or placement in primary care clinics to work supervised by local dentists. At baseline, students self-rated their global confidence on a five-point scale. These measures were repeated at follow-up, augmented by a transition judgment and a then-test of confidence (asking students to look back and re-rate their pre-placement confidence). Groups were comparable at baseline. Follow-up scores for global confidence were similar between groups. The outreach group scored higher in the transition judgment (mean 3.7, SD 0.9) than the control group (mean 3.1, SD 1.1, P=0.05). In the then-test, on reflection, the outreach group considered their baseline ratings of confidence were overoptimistic (mean then-test scores 3.2, SD 0.9 and baseline 3.7, SD 0.5) while the control group thought theirs were accurate (mean then-test scores 3.8, SD 0.7 and baseline 3.6, SD 0.8, P=0.01). The findings suggest dental outreach training in primary care settings is more effective than dental school training alone in improving students' confidence in tackling clinical situations. The measurement of change in confidence is complicated by shifts in students' internal scales arising from insights gained on outreach.

Attitude of Health Personnel↗

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↗

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↗