Genome-Wide Scan for Parent-of-Origin Effects in a sub-Saharan African Cohort With Nonsyndromic Cleft Lip and/or Cleft Palate (CL/P)

OBJECTIVE

Nonsyndromic cleft lip and/or cleft palate (NSCL/P) have multifactorial etiology where genetic factors, gene-environment interactions, stochastic factors, gene-gene interactions, and parent-of-origin effects (POEs) play cardinal roles. POEs arise when the parental origin of alleles differentially impacts the phenotype of the offspring. The aim of this study was to identify POEs that can increase risk for NSCL/P in humans using a genome-wide dataset.

METHODS

The samples (174 case-parent trios from Ghana, Ethiopia, and Nigeria) included in this study were from the African only genome wide association studies (GWAS) that was published in 2019. Genotyping of individual DNA using over 2 million multiethnic and African ancestry-specific single-nucleotide polymorphisms from the Illumina Multi-Ethnic Genotyping Array v2 15070954 A2 (genome build GRCh37/hg19) was done at the Center for Inherited Diseases Research. After quality control checks, PLINK was employed to carry out POE analysis employing the pooled subphenotypes of NSCL/P.

RESULTS

We observed possible hints of POEs at a cluster of genes at a 1 mega base pair window at the major histocompatibility complex class 1 locus on chromosome 6, as well as at other loci encompassing candidate genes such as ASB18, ANKEF1, AGAP1, GABRD, HHAT, CCT7, DNMT3A, EPHA7, FOXO3, lncRNAs, microRNA, antisense RNAs, ZNRD1, ZFAT, and ZBTB16.

CONCLUSION

Findings from our study suggest that some loci may increase the risk for NSCL/P through POEs. Additional studies are required to confirm these suggestive loci in NSCL/P etiology.

Caries in children with and without orofacial clefting; Systematic Review and Meta-Analysis

This systematic review compared children's primary dentition caries experience for those with cleft lip and/or palate (CL/P) and without. Four databases were searched without date restriction for; cross‐sectional studies comparing caries experience for children with CL/P to those without. Screening, data extraction and risk assessment were carried out independently (in duplicate). Meta‐analyses used a random‐effects model. Twenty studies (21 reports) fitting the inclusion criteria comprised 4647 children in primary dentition from 12 countries. For dmft (n = 3016 children; 15 groups), CL/P mean = 3.2; standard deviation = 2.22 and no CL/P mean dmft = 2.5; sd 1.53. For dmfs (n = 1095 children; 6 groups), CL/P mean = 4; sd = 3.5 and no CL/P mean = 3; sd = 2.8. For % caries experience (n = 1094 children; 7 groups), CL/P mean = 65%; sd = 20.8 and no CL/P mean = 52%; sd = 28.1. Meta‐analysis showed higher caries experience in children with CL/P, standardised mean difference = 0.46; 95% CI = 0.15, 0.77. Studies' risk of bias was high (n = 7), medium (n−10) and low (n = 3). Children with CL/P had higher caries experience compared to those without CLP.

Genome-wide Gene-by-Sex Interaction Studies Identify Novel Nonsyndromic Orofacial Clefts Risk Locus

Risk loci identified through genome-wide association studies have explained about 25% of the phenotypic variations in nonsyndromic orofacial clefts (nsOFCs) on the liability scale. Despite the notable sex differences in the incidences of the different cleft types, investigation of loci for sex-specific effects has been understudied. To explore the sex-specific effects in genetic etiology of nsOFCs, we conducted a genome-wide gene × sex (GxSex) interaction study in a sub-Saharan African orofacial cleft cohort. The sample included 1,019 nonsyndromic orofacial cleft cases (814 cleft lip with or without cleft palate and 205 cleft palate only) and 2,159 controls recruited from 3 sites (Ethiopia, Ghana, and Nigeria). An additive logistic model was used to examine the joint effects of the genotype and GxSex interaction. Furthermore, we examined loci with suggestive significance (P < 1E-5) in the additive model for the effect of the GxSex interaction only. We identified a novel risk locus on chromosome 8p22 with genome-wide significant joint and GxSex interaction effects (rs2720555, p_2df = 1.16E-08, p_GxSex = 1.49E-09, odds ratio [OR] = 0.44, 95% CI = 0.34 to 0.57). For males, the risk of cleft lip with or without cleft palate at this locus decreases with additional copies of the minor allele (p < 0.0001, OR = 0.60, 95% CI = 0.48 to 0.74), but the effect is reversed for females (p = 0.0004, OR = 1.36, 95% CI = 1.15 to 1.60). We replicated the female-specific effect of this locus in an independent cohort (p = 0.037, OR = 1.30, 95% CI = 1.02 to 1.65), but no significant effect was found for the males (p = 0.29, OR = 0.86, 95% CI = 0.65 to 1.14). This locus is in topologically associating domain with craniofacially expressed and enriched genes during embryonic development. Rare coding mutations of some of these genes were identified in nsOFC cohorts through whole exome sequencing analysis. Our study is additional proof that genome-wide GxSex interaction analysis provides an opportunity for novel findings of loci and genes that contribute to the risk of nsOFCs.

Effectiveness of The Wikipedia Collaboration of Dental Schools' Training Programme: a new Paradigm for Teaching and Learning of Evidence-Based Dentistry

BACKGROUND

The Wikipedia Collaboration of Dental Schools (WCODS) is a student-led initiative that aims to publish high quality scientific, evidence-based dental content on the Wikipedia online encyclopaedia by equipping its members to use research, critical appraisal and writing skills to create accurate content. In 2019, the Collaboration launched a standardised training programme developed by Wikimedia-trained committee members, academic dental school staff and the Cochrane Oral Health global community.

OBJECTIVE

To evaluate the effectiveness of this training programme in ensuring WCODS editors follow the processes underpinning Evidence-Based Dentistry (EBD).

METHOD

A cohort of dental students and staff (n=136) from six dental schools in the UK and Malaysia took part in a standardised and structured training programme at the annual WCODS training meeting. Participants' abilities and their perceived levels of confidence in carrying out critical analysis of the literature were measured using pre- and post-training surveys, and competency assessments.

RESULTS

Participants' skills in conducting literature searches, critical appraisal of the findings and creating and editing a Wikipedia page improved after training.

CONCLUSION

The training programme provided participants with the skill set and confidence to apply best practice to create and edit Wikipedia entries. This Collaboration intends to recruit more contributors to improve global oral health literacy using the free online Wikipedia encyclopaedia.

Zygomaticus major muscle bony attachment site: a Thiel-embalmed cadaver study

OBJECTIVE

Thezygomaticus major is a principal muscle of facial expression which is engaged when smiling. The zygomaticus major origin of the zygomatic bone is often discussed relevant to its importance in the field of plastic surgery. In addition, the zygomaticus major attachment site is also significant for forensic craniofacial reconstruction, separating the cheek into frontal and lateral surfaces. However, there are discrepancies amongst published articles regarding the precise origin of the zygomaticus major muscle. The aim of this study is to investigate more distinctive and palpable landmarks as the bony attachment of the zygomaticus major.

METHODS

This project is the first zygomaticus major dissection study utilising Thiel embalmed cadavers. Fifty-two facial dissections were investigated in 26 Thiel embalmed bodies, bequeathed to the Centre for Anatomy and Human Identification at The University of Dundee between 2013 and 2015.

RESULTS

This study found that the origin of zygomaticus major muscle was located at the superior margin of the temporal process on the lateral surface of zygomatic bone. Moreover, the zygomaticus major muscle overlapped the anterosuperior border of the masseter muscle. One out of 52 zygomaticus major muscles presented bifurcation.

CONCLUSION

The origin site of zygomaticus major is considered important to increase resemblance in forensic craniofacial reconstruction. Furthermore, since zygomaticus major is a salient muscle involved in facial expression, the potential effects for cosmetic/surgical procedures are also relevant to the medical field and successful surgical outcomes. The current study provided easily palpable landmarks of zygomaticus major origin site which is beneficial for both surgeons and forensic craniofacial reconstruction practitioners.

Estimating the birth prevalence and pregnancy outcomes of congenital malformations worldwide

Congenital anomaly registries have two main surveillance aims: firstly to define baseline epidemiology of important congenital anomalies to facilitate programme, policy and resource planning, and secondly to identify clusters of cases and any other epidemiological changes that could give early warning of environmental or infectious hazards. However, setting up a sustainable registry and surveillance system is resource-intensive requiring national infrastructure for recording all cases and diagnostic facilities to identify those malformations that that are not externally visible. Consequently, not all countries have yet established robust surveillance systems. For these countries, methods are needed to generate estimates of prevalence of these disorders which can act as a starting point for assessing disease burden and service implications. Here, we describe how registry data from high-income settings can be used for generating reference rates that can be used as provisional estimates for countries with little or no observational data on non-syndromic congenital malformations.

Muscle fiber diameter assessment in cleft lip using image processing

OBJECTIVE

To pilot investigation of muscle fiber diameter (MFD) on medial and lateral sides of the cleft in 18 infants with cleft lip with or without cleft palate (CL/P) using image processing.

MATERIAL AND METHODS

Formalin-fixed paraffin-embedded (FFPE) tissue samples from the medial and lateral sides of the cleft were analyzed for MFD using an image-processing program (ImageJ). For within-case comparison, a paired Student's t test was performed. For comparisons between classes, an unpaired t test was used.

RESULTS

Image processing enabled rapid measurement of MFD with majority of fibers showing diameter between 6 and 11 μm. There was no significant difference in mean MFD between the medial and lateral sides, or between CL and CLP. However, we found a significant difference on the medial side (p = .032) between males and females.

CONCLUSION

The image processing on FFPE tissues resulted in easy quantification of MFD with finding of a smaller MFD on the medial side in males suggesting possible differences in orbicularis oris (OO) muscle between the two sexes in CL that warrants replication using larger number of cases. Moreover, this finding can aid subclinical phenotyping and potentially in the restoration of the anatomy and function of the upper lip.

Loss-of-Function GRHL3 Variants Detected in African Patients with Isolated Cleft Palate

In contrast to the progress that has been made toward understanding the genetic etiology of cleft lip with or without cleft palate, relatively little is known about the genetic etiology for cleft palate only (CPO). A common coding variant of grainyhead like transcription factor 3 ( GRHL3) was recently shown to be associated with risk for CPO in Europeans. Mutations in this gene were also reported in families with Van der Woude syndrome. To identify rare mutations in GRHL3 that might explain the missing heritability for CPO, we sequenced GRHL3 in cases of CPO from Africa. We recruited participants from Ghana, Ethiopia, and Nigeria. This cohort included case-parent trios, cases and other family members, as well as controls. We sequenced exons of this gene in DNA from a total of 134 nonsyndromic cases. When possible, we sequenced them in parents to identify de novo mutations. Five novel mutations were identified: 2 missense (c.497C>A; p.Pro166His and c.1229A>G; p.Asp410Gly), 1 splice site (c.1282A>C p.Ser428Arg), 1 frameshift (c.470delC; p.Gly158Alafster55), and 1 nonsense (c.1677C>A; p.Tyr559Ter). These mutations were absent from 270 sequenced controls and from all public exome and whole genome databases, including the 1000 Genomes database (which includes data from Africa). However, 4 of the 5 mutations were present in unaffected mothers, indicating that their penetrance is incomplete. Interestingly, 1 mutation damaged a predicted sumoylation site, and another disrupted a predicted CK1 phosphorylation site. Overexpression assays in zebrafish and reporter assays in vitro indicated that 4 variants were functionally null or hypomorphic, while 1 was dominant negative. This study provides evidence that, as in Caucasian populations, mutations in GRHL3 contribute to the risk of nonsyndromic CPO in the African population.

A survey of undergraduate orthodontic teaching and factors affecting pursuit of postgraduate training

Background Undergraduate orthodontic teaching has been focused on developing an understanding of occlusal development in an effort to equip practitioners to make appropriate referrals for specialist-delivered care. However, there is a growing interest among general dentists in delivering more specialised treatments, including short-term orthodontic alignment. This study aimed to assess the levels of knowledge of occlusal problems among final year undergraduate dental students, as well as their interest in various orthodontics techniques and training.Methods A 36-item electronic questionnaire was sent to all final year undergraduate students in four dental institutes in the UK (Barts and the London, Kings College London, Cardiff and Dundee). The questionnaire explored satisfaction with undergraduate orthodontic teaching; students' perception of knowledge, based on General Dental Council learning outcomes; perceptions of the need for specialist involvement in the management of dental problems; interest in further training in orthodontics; and potential barriers to undertaking specialist training.Results The overall response rate was 66% (239/362). The majority of students (84.1%) were aware of GDC guidance in terms of undergraduate teaching. Students reported a preference for case-based and practical teaching sessions in orthodontics, with less interest in lectures or problem-based learning approaches. A high percentage were interested in further teaching in interceptive orthodontics (60.3%) and fixed appliance therapy (55.7%). Further training including specialist orthodontic training (36.4%), Invisalign (59%) and Six Month Smiles (41%) courses appealed to undergraduates. Levels of student debt, course fees and geographical issues were seen as potential barriers to formal, specialist training pathways.Conclusions Satisfaction with undergraduate orthodontic teaching is high and interest in further training, including specialist training pathways, continues to be high. While short-term orthodontics is not taught at undergraduate level, there appears to be an appetite to undertake alternatives to conventional orthodontics among dental students.

Association Studies and Direct DNA Sequencing Implicate Genetic Susceptibility Loci in the Etiology of Nonsyndromic Orofacial Clefts in Sub-Saharan African Populations

Orofacial clefts (OFCs) are congenital dysmorphologies of the human face and oral cavity, with a global incidence of 1 per 700 live births. These anomalies exhibit a multifactorial pattern of inheritance, with genetic and environmental factors both playing crucial roles. Many loci have been implicated in the etiology of nonsyndromic cleft lip with or without cleft palate (NSCL/P) in populations of Asian and European ancestries, through genome-wide association studies and candidate gene studies. However, few populations of African descent have been studied to date. Here, the authors show evidence of an association of some loci with NSCL/P and nonsyndromic cleft palate only (NSCPO) in cohorts from Africa (Ghana, Ethiopia, and Nigeria). The authors genotyped 48 single-nucleotide polymorphisms that were selected from previous genome-wide association studies and candidate gene studies. These markers were successfully genotyped on 701 NSCL/P and 163 NSCPO cases, 1,070 unaffected relatives, and 1,078 unrelated controls. The authors also directly sequenced 7 genes in 184 nonsyndromic OFC (NSOFC) cases and 96 controls from Ghana. Population-specific associations were observed in the case-control analyses of the subpopulations, with West African subpopulations (Ghana and Nigeria) showing a similar pattern of associations. In meta-analyses of the case-control cohort, PAX7 (rs742071, P = 5.10 × 10(-3)), 8q24 (rs987525, P = 1.22 × 10(-3)), and VAX1 (rs7078160, P = 0.04) were nominally associated with NSCL/P, and MSX1 (rs115200552, P = 0.01), TULP4 (rs651333, P = 0.04), CRISPLD2 (rs4783099, P = 0.02), and NOG1 (rs17760296, P = 0.04) were nominally associated with NSCPO. Moreover, 7 loci exhibited evidence of threshold overtransmission in NSOFC cases through the transmission disequilibrium test and through analyses of the family-based association for disease traits. Through DNA sequencing, the authors also identified 2 novel, rare, potentially pathogenic variants (p.Asn323Asp and p.Lys426IlefsTer6) in ARHGAP29 In conclusion, the authors have shown evidence for the association of many loci with NSCL/P and NSCPO. To the best of this knowledge, this study is the first to demonstrate any of these association signals in any African population.

Intraoral 3D Scanning or Dental Impressions for the Assessment of Dental Arch Relationships in Cleft Care: Which is Superior?

OBJECTIVE

This study was undertaken to evaluate intraoral 3D scans for assessing dental arch relationships and obtain patient/parent perceptions of impressions and intraoral 3D scanning.

MATERIALS & METHODS

Forty-three subjects with nonsyndromic unilateral cleft lip and palate (UCLP) had impressions taken for plaster models. These and the teeth were scanned using the R700 Orthodontic Study Model Scanner and Trios® Digital Impressions Scanner (3Shape A/S, Copenhagen, Denmark) to create indirect and direct digital models. All model formats were scored by three observers on two occasions using the GOSLON and modified Huddart Bodenham (MHB) indices. Participants and parents scored their perceptions of impressions and scanning from 1 (very good) to 5 (very bad). Intra- and interexaminer reliability were tested using GOSLON and MHB data (Cronbach's Alpha >0.9). Bland and Altman plots were created for MHB data, with each model medium (one-sample t tests, P < .05) and questionnaire data (Wilcoxon signed ranks P < .05) tested.

RESULTS

Intra- and interexaminer reliability (>0.9) were good for all formats with the direct digital models having the lowest interexaminer differences. Participants had higher ratings for scanning comfort (84.8%) than impressions (44.2%) (P < .05) and for scanning time (56.6%) than impressions (51.2%) (P > .05). None disliked scanning, but 16.3% disliked impressions. Data for parents and children positively correlated (P < .05).

CONCLUSIONS

Reliability of scoring dental arch relationships using intraoral 3D scans was superior to indirect digital and to plaster models; Subjects with UCLP preferred intra-oral 3D scanning to dental impressions, mirrored by parents/carers; This study supports the replacement of conventional impressions with intra-oral 3D scans in longitudinal evaluations of the outcomes of cleft care.

Global Economic Impact of Dental Diseases

Reporting the economic burden of oral diseases is important to evaluate the societal relevance of preventing and addressing oral diseases. In addition to treatment costs, there are indirect costs to consider, mainly in terms of productivity losses due to absenteeism from work. The purpose of the present study was to estimate the direct and indirect costs of dental diseases worldwide to approximate the global economic impact. Estimation of direct treatment costs was based on a systematic approach. For estimation of indirect costs, an approach suggested by the World Health Organization's Commission on Macroeconomics and Health was employed, which factored in 2010 values of gross domestic product per capita as provided by the International Monetary Fund and oral burden of disease estimates from the 2010 Global Burden of Disease Study. Direct treatment costs due to dental diseases worldwide were estimated at US$298 billion yearly, corresponding to an average of 4.6% of global health expenditure. Indirect costs due to dental diseases worldwide amounted to US$144 billion yearly, corresponding to economic losses within the range of the 10 most frequent global causes of death. Within the limitations of currently available data sources and methodologies, these findings suggest that the global economic impact of dental diseases amounted to US$442 billion in 2010. Improvements in population oral health may imply substantial economic benefits not only in terms of reduced treatment costs but also because of fewer productivity losses in the labor market.

Ectopia or concomitant hypohyperdontia? A case report

This report describes the unusual appearance seen on a panoramic radiograph of an orthodontic patient which the authors argue may represent ectopia or concomitant hypohyperdontia of the mandibular premolar teeth. A literature review describes the frequency of such anomalies in this area from previous studies. The presenting features of the patient and the differential diagnoses are explored. Treatment planning is discussed and treatment carried out in this particular case is detailed. The unusual symmetrical bilateral anomalies in this patient may point to a genetic determinant of tooth germ position and/or movement.

Strong association of variants around FOXE1 and orofacial clefting

Nonsyndromic orofacial clefting (nsOFC) is a common, complex congenital disorder. The most frequent forms are nonsyndromic cleft lip with or without cleft palate (nsCL/P) and nonsyndromic cleft palate only (nsCPO). Although they are generally considered distinct entities, a recent study has implicated a region around the FOXE1 gene in both nsCL/P and nsCPO. To investigate this hypothesis, we analyzed the 2 most strongly associated markers (rs3758249 and rs4460498) in 2 independent samples of differing ethnicities: Central European (949 nsCL/P cases, 155 nsCPO cases, 1163 controls) and Mayan Mesoamerican (156 nsCL/P cases, 10 nsCPO cases, 338 controls). While highly significant associations for both single-nucleotide polymorphisms were obtained in nsCL/P (rs4460498: p Europe = 6.50 × 10(-06), p Mayan = .0151; rs3758249: p Europe = 2.41 × 10(-05), p Mayan = .0299), no association was found in nsCPO (p > .05). Genotyping of rs4460498 in 472 independent European trios revealed significant associations for nsCL/P (p = .016) and nsCPO (p = .043). A meta-analysis of all data revealed a genomewide significant result for nsCL/P (p = 1.31 × 10(-08)), which became more significant when nsCPO cases were added (p nsOFC = 1.56 × 10(-09)). These results strongly support the FOXE1 locus as a risk factor for nsOFC. With the data of the initial study, there is now considerable evidence that this locus is the first conclusive risk factor shared between nsCL/P and nsCPO.

Prevalence of orofacial clefts in Nigeria

Orofacial clefts are the most common malformations of the head and neck. In Africa, orofacial clefts are underascertained, with little or no surveillance system in most parts for clefts and other birth defects. A Nigerian craniofacial anomalies study, NigeriaCRAN, was established in 2006 to support cleft research specifically for epidemiological studies, treatment outcomes, and studies into etiology and prevention. We pooled data from seven of the largest Smile Train treatment centers in the six geopolitical zones in Nigeria. Data from September 2006 to June 2011 were analyzed and clefts compared between sides and genders using the Fisher exact test. A total of 2197 cases were identified during the study period, with an estimated prevalence rate of 0.5 per 1000. Of the total number of orofacial clefts, 54.4% occur in males and 45.6% in females. There was a significant difference (P = .0001) between unilateral left clefts and unilateral right clefts, and there was a significant difference (P = .0001) between bilateral clefts and clefts on either the left or right side. A significant gender difference (P = .03) was also observed for cleft palate, with more females than males. A total of 103 (4.7%) associated anomalies were identified. There were nine syndromic cleft cases, and 10.4% of the total number of individuals with clefts have an affected relative. The significant difference between unilateral clefts and the gender differences in the proportion of cleft palate only are consistent with the literature. The present study emphasizes the need for birth defects registries in developing countries in order to estimate the exact prevalence of birth defects including orofacial clefts.

Global oral health inequalities: challenges in the prevention and management of orofacial clefts and potential solutions

The birth prevalence of orofacial clefts, one of the most common congenital anomalies, is approximately one in 700 live births, but varies with geography, ethnicity, and socio-economic status. There is a variation in infant mortality and access to care both between and within countries, so some clefts remain unrepaired into adulthood. Quality of care also varies, and even among repaired clefts there is residual deformity and morbidity that significantly affects some children. The two major issues in attempts to address these inequalities are (a) etiology/possibilities for prevention and (b) management and quality of care. For prevention, collaborative research efforts are required in developing countries, in line with the WHO approach to implement the recommendations of the 2008 Millennium Development Goals (www.un.org/millenniumgoals). This includes the "common risk factor" approach, which analyzes biological and social determinants of health alongside other chronic health problems such as diabetes and obesity, as outlined in the Marmot Health inequalities review (2008) (www.ucl.ac.uk/gheg/marmotreview). Simultaneously, orofacial cleft research should involve clinical researchers to identify inequalities in access to treatment and identify the best interventions for minimizing mortality and residual deformity. The future research agenda also requires engagement with implementation science to get research findings into practice.

Genetic studies in the Nigerian population implicate an MSX1 mutation in complex oral facial clefting disorders

BACKGROUND

Orofacial clefts are the most common malformations of the head and neck, with a worldwide prevalence of 1 in 700 births. They are commonly divided into CL(P) and CP based on anatomic, genetic, and embryologic findings. A Nigerian craniofacial anomalies study (NigeriaCRAN) was set up in 2006 to investigate the role of gene-environment interaction in the origin of orofacial clefts in Nigeria.

SUBJECTS AND METHODS

DNA isolated from saliva from Nigerian probands was used for genotype association studies and direct sequencing of cleft candidate genes: MSX1 , IRF6 , FOXE1, FGFR1 , FGFR2 , BMP4 , MAFB, ABCA4 , PAX7, and VAX1 , and the chromosome 8q region.

RESULTS

A missense mutation A34G in MSX1 was observed in nine cases and four HapMap controls. No other apparent causative variations were identified. Deviation from Hardy Weinberg equilibrium (HWE) was observed in these cases (p = .00002). A significant difference was noted between the affected side for unilateral CL (p = .03) and bilateral clefts and between clefts on either side (p = .02). A significant gender difference was also observed for CP (p = .008).

CONCLUSIONS

Replication of a mutation previously implicated in other populations suggests a role for the MSX1 A34G variant in the development of CL(P).

Asymmetry of the craniofacial skeleton in the parents of children with a cleft lip, with or without a cleft palate, or an isolated cleft palate

The objective of this study was to evaluate asymmetry of the parental craniofacial skeleton of subjects with a cleft lip, with or without cleft palate [CL(P)], and isolated cleft palate (CP). The postero-anterior (PA) cephalograms of 52 parents of children with CL(P) and 40 parents of children with CP from a sample of 196 children with non-syndromic clefts in the west of Scotland were analysed. A conventional cephalometric asymmetry analysis was used to evaluate size-related right:left asymmetry comprising eight linear distances, nine angular, and three facial area measurements. Right:left ratios of the mean values identified the direction of the asymmetry and two-sample t-tests determined statistical significance. A shape-related asymmetry analysis was also undertaken. The configurations of landmarks were optimally superimposed and scaled using Procrustes algorithms. Euclidean distance matrix analysis (EDMA) was then compared and the shape of the left and the right landmark configurations were statistically tested using a non-parametric bootstrap technique. For the parents of CL(P) children, size-related asymmetry was identified and the area of the craniofacial polygon was statistically significantly larger on the right than on the left side. EDMA detected the presence of shape-related asymmetry (T statistic = 1.304; P = 0.003). For the parents of CP children, although size-related asymmetry was identified, EDMA did not identify shape-related asymmetry (T statistic = 1.281; P = 0.065). Size and shape directional asymmetries are characteristic features of the parental craniofacial skeleton in CL(P). Although directional size asymmetry is present in the parental craniofacial skeleton in CP, shape asymmetry is not a characteristic feature.

Epidemiology of Orofacial clefts in Africa: Methodological challenges in ascertainment

BACKGROUND

To carry out a systematic review of the birth prevalence of cleft lip with or without cleft palate (CLP) and cleft palate (CP) in Africa based on available published data.

METHOD

Using the Cochrane search strategy and the following keywords words "cleft palate", "prevalence", "incidence", "cleft lip" and "Africa" to screen Ovid Medline {1966 to March 2007), Cinahl {1982-March 2007}, Pub Med, Scopus, and Web-Google. All identified published, prospective and retrospective studies on the birth prevalence of CLP and CP in Africa were included. The dates, location, sources, number of births (live births, still births, number of cleft cases, prevalence rates, sex ratio, cleft types, and clefts with associated anomalies were extracted.

RESULTS

Ascertainment of cases was through the hospitals. Overall there were 57 CL/P, 56 CL and 36 CP reported from all the studies. From seven studies combined, 21 males and 20 females had CL, 10 males and 22 females with CP and 26 males and 24 females with CL/P. There were 3 cases with CL/P, 2 with CP and 2 with CL from the three studies that reported clefts with associated anomalies.

CONCLUSION

For an improved ascertainment of cleft cases, there is a need to set up a birth defects surveillance system in the form of a national birth registry. Future studies should then aim to include the entire population in geographically defined regions. Reliable data on incidence is an essential pre-requisite for studies into aetiology and prevention.

Folate and Clefts of the Lip and Palate—A U.K.-Based Case-Control Study: Part I: Dietary and Supplemental Folate

Objectives:

We sought to determine the associations between nonsyndromic cleft lip with or without cleft palate (CL−P) and cleft palate only (CP) and maternal intake of dietary folate and supplemental folic acid, in an area where the prevalence at birth of neural tube defects has been high and flour is not fortified with folic acid.

Methods:

Interviews regarding periconceptional dietary intake and supplement use were completed with the mothers of 112 CL−P cases, 78 CP cases, and 248 unaffected infants. The data were analyzed by logistic regression methods.

Results:

There was no overall association between CL−P and CP and either energy-adjusted total folate intake or supplemental folic acid use, irrespective of dosage.

Conclusion:

Overall, higher intakes of total folate do not appear to prevent oral clefts in this population.

Folate and Clefts of the Lip and Palate—A U.K.-Based Case-Control Study: Part II: Biochemical and Genetic Analysis

Objective:

To investigate associations between nonsyndromic oral clefts and biochemical measures of folate status and the MTHFR C677T variant in the United Kingdom, where there has been no folic acid fortification program.

Method:

Dietary details were obtained from the mothers of 112 cases of cleft lip with or without cleft palate (CL±P), 78 cleft palate only (CP) cases, and 248 unaffected infants. Infant and parental MTHFR C677T genotype was determined. Red blood cell (RBC) and serum folate and homocysteine levels were assessed in 12-month postpartum blood samples from a subset of mothers. The data were analyzed by logistic and log-linear regression methods.

Results:

There was an inverse association between CL±P and maternal MTHFR CT (odds ratio [OR]  =  0.5, 95% confidence interval [CI]  =  0.31–0.95) and TT (OR  =  0.6, 95% CI  =  0.21–1.50) genotypes, with similar risk estimates for CP. There was no clear association with infant MTHFR genotype. Higher levels of maternal postpartum RBC and serum folate were associated with a lower risk for CL±P and an increased risk for CP. Higher levels of serum homocysteine were associated with a slightly increased risk for both CL±P and CP.

Conclusion:

While the inverse relation between the mother's having the MTHFR C677T variant and both CL±P and CP suggests perturbation of maternal folate metabolism is of etiological importance, contrasting relations between maternal postpartum levels of RBC and serum folate by type of cleft are difficult to explain.

Evaluation of a modified Huddart/Bodenham scoring system for assessment of maxillary arch constriction in unilateral cleft lip and palate subjects

The aim of this retrospective study was to describe the use and reliability of a numerical scoring system (modified Huddart/Bodenham) for the measurement of maxillary arch constriction in patients born with unilateral cleft lip and palate (UCLP), and to compare and contrast the new scoring system with the current methods of measuring treatment outcome, the Goslon and 5-year-old indices. Dental study models of 50 patients aged 5 years, and 50 patients aged 10 years, were scored using the 5-year-old and Goslon indices, respectively. Four examiners scored each set of models using the modified Huddart and Bodenham system, and repeated the scoring one month later. The intra- and inter-rater reliability of the numerical scoring system was assessed using the Kappa (kappa) statistic. The scores using the new method were correlated with the 5-year-old and Goslon scores using Spearman's (rho) and Kendall's (tau) rank correlation coefficients. There was a high level of intra-rater reliability for both the 5 (0.87: incisors, 0.91: canines, 0.88: molars) and 10 (0.9: incisors, 0.84: canines, 0.78: premolars/molars) year models. The weighted kappa values measuring inter-rater reliability were above 0.85 and 0.74, respectively, for all examiners. There was a statistically significant correlation between the modified Huddart/Bodenham scores and both the 5-year-old and Goslon scores in all cases (P < 0.001). It is concluded that the modified Huddart/Bodenham system provides an objective and reliable assessment of maxillary arch constriction. It has a high degree of correlation with the recommended standards, but is more versatile and sensitive to inter-arch discrepancies.

Smoking and orofacial clefts: a United Kingdom-based case-control study

OBJECTIVE

To investigate the association between smoking and orofacial clefts in the United Kingdom.

DESIGN

Case-control study in which the mother's exposure to tobacco smoke was assessed by a structured interview.

SETTING

Scotland and the Manchester and Merseyside regions of England.

PARTICIPANTS

One hundred ninety children born with oral cleft between September 1, 1997, and January 31, 2000, and 248 population controls, matched with the cases on sex, date of birth, and region.

MAIN OUTCOME MEASURE

Cleft lip with or without cleft palate and cleft palate.

RESULTS

There was a positive association between maternal smoking during the first trimester of pregnancy and both cleft lip with or without cleft palate (odds ratio 1.9, 95% confidence interval 1.1 to 3.1) and cleft palate (odds ratio 2.3, 95% confidence interval 1.3 to 4.1). There was evidence of a dose-response relationship for both types of cleft. An effect of passive smoking could not be excluded in mothers who did not smoke themselves.

CONCLUSION

The small increased risk for cleft lip with or without cleft palate in the offspring of women who smoke during pregnancy observed in this study is in line with previous evidence. In contrast to some previous studies, an increased risk was also apparent for cleft palate. In these U.K. data, there was evidence of a dose-response effect of maternal smoking for both types of cleft. The data were compatible with a modest effect of maternal passive smoking, but the study lacked statistical power to detect or exclude such an effect with confidence. It may be useful to incorporate information on the effects of maternal smoking on oral clefts into public health campaigns on the consequences of maternal smoking.

Parental craniofacial morphology in orofacial clefting

The parental craniofacial morphology in orofacial clefting (OFC) has been shown to differ from that of the non-cleft population when evaluated using conventional cephalometric analyses comprising a variety of linear, angular, and area measurements. In spite of this, the shape of the parental craniofacial complex is of greater importance in the search for the morphogenes involved in OFC. This retrospective case-control study employed three morphometric techniques [discriminant analysis of the principal components of shape (PCS), Euclidean distance matrix analysis (EDMA), and thin-plate spline analysis (TPS)] to localize the craniofacial skeletal shape differences between (a) the parents of children with OFC and a comparison group, (b) the parents of children with cleft lip and palate [CL(P)] and cleft palate (CP), and (c) the male and female parents of children with OFC. The postero-anterior (PA) cephalograms of 92 parents of children with non-syndromic OFC and 43 comparison group volunteers were scanned and digitized. The configurations of 24 reproducible landmarks were optimally superimposed using Procrustes algorithms to allow shape data to be derived using PCS, EDMA, and TPS. The parental craniofacial shape statistically significantly differed from that of the comparison group using PCS (P < 0.001) and EDMA (P = 0.001). However PCS, EDMA, and TPS differed in their localization of the shape differences, explainable by the different mathematical methods used by the individual techniques. Interestingly, the parental craniofacial shapes in CL(P) and CP were morphologically similar when tested using PCS (P = 0.03) and EDMA (P = 0.027). However, there was no shape-related sexual dimorphism in parental craniofacial morphology in OFC when tested using PCS (P = 0.35) and EDMA (P = 0.525). Thus, the parental craniofacial shape in OFC differs from the non-cleft population, the parental craniofacial shape does not differ between CL(P) and CP and there is no sexual dimorphism in the parental craniofacial morphology in OFC, as viewed on PA cephalograms.

Socioeconomic status and orofacial clefts in Scotland, 1989 to 1998

OBJECTIVE

The purpose of this study was to investigate the association between socioeconomic status and orofacial clefts (OFC) in Scotland.

DESIGN

Study of prevalence at birth over a 10-year period using an area-based measure of material deprivation.

SETTING

Population-based study throughout Scotland.

PARTICIPANTS

Eight hundred thirty-four live births with OFC born between January 1, 1989, and December 31, 1998, ascertained from the nationwide register of the Cleft Service in Scotland, compared with the total 603,825 live births in Scotland in this period.

RESULTS

There was a strong positive relationship whereby the prevalence of OFC at birth increased with increasing deprivation. This trend was statistically significant for cleft lip and/or palate (CL[P]: p =.016) but not for cleft palate (CP; p =.078). For each type of cleft, the relative risk among those resident in the most deprived areas, compared with those resident in the least deprived areas, was 2.33.

CONCLUSIONS

The association between OFC and socioeconomic status is consistent with a report for an earlier period in a smaller part of Scotland. Unlike the earlier study, this pattern appears to be stronger for CL(P) than for CP. These observations do not appear to be an artifact of recording. It is possible that they reflect the association between deprivation and risk factors for OFC, most likely tobacco smoking during pregnancy. Because the relationship between OFC and socioeconomic status appears to have been virtually unstudied in other populations, it would be valuable to investigate this relationship elsewhere and determine whether known risk factors account for the relationship.

Fluoride supplements and changes in tooth decay on the Island of Tristan da Cunha: 1966-1996

BACKGROUND

The island of Tristan Da Cunha is one of the few examples in the world of a remote enclosed community. The inhabitants of the island were transported to England in 1961 as a result of a volcanic eruption and during their time in England they received a detailed dental health examination. They were later examined back on the island in 1966 by Dr John Fisher and in 1982 a school fluoride supplementation programme was introduced.

AIM

The present paper reports the results of the first dental health survey to be carried out on the island since the introduction of a regular school fluoride supplementation programme in 1982.

SUBJECTS AND METHODS

A cohort of 6-19-year-old subjects on the island were examined in 1996 using a similar protocol to that which was used by Fisher in the 1966 examination.

RESULTS

Comparing the 6-12-year-olds who were caries free in 1966 with those caries free in 1996 using the Chi-squared statistic reveals a statistically significant greater number caries free in the more recent cohort (X2 - 6.0, P- 0.014). For the older age group (13-19 years), a similar comparison reveals a highly statistically significant difference(Z2 - 12.26, P 0.005).

CONCLUSIONS

A significant increase in the number of caries free 6-19-year-old children in Tristan Da Cunha between 1966 and 1996 was noted: 1) This is a significant finding in the light of the school fluoride supplementation programme that was introduced on the island in 1982; and 2) Appropriate fluoride supplementation regimes may have conferred a protective effect in a group of children with a cariogenic diet. The paper discusses the significance of this study in the support of fluoridation as a method of reducing the prevalence of dental caries a nd also discusses possibilities for future research on the island of Tristan Da Cunha.

Posteroanterior cephalometric analysis of the parental craniofacial morphology in orofacial clefting

OBJECTIVE

To evaluate the parental craniofacial morphology in orofacial clefting (OFC).

DESIGN

Case-control posteroanterior cephalometric study.

SETTING

The Department of Orthodontics, University of Dundee Dental School, Scotland, United Kingdom.

PARTICIPANTS

Ninety-two parents from a completely ascertained sample of 286 Scottish babies with nonsyndromic OFC and 43 comparison group volunteers from the University of Dundee Dental School.

MAIN OUTCOMES AND MEASURES

A conventional cephalometric analysis was used to measure linear distances and their ratios, angles, and areas. Two-sample Student's t tests and a discriminant analysis were applied to the data, and the clinically important statistically significant variables were identified using an accepted protocol.

RESULTS

Sixty-four linear distances, 10 ratios, 52 angles, and 7 areas statistically significantly differed between the parental and comparison groups (p <.01). Of these, 62 linear distances (22%), 9 ratios (45%), 41 angles (41%), and 6 areas (24%) were clinically important. Asymmetry was a feature of the results. Canonical variates analysis correctly classified 91.3% of the parental group and 90.6% of the comparison group using a series of 36 variables.

CONCLUSIONS

The parental craniofacial morphology in OFC differs significantly from the noncleft population. A larger superolateral face and smaller central midface and, in particular, a clinically significantly smaller maxillary width, in conjunction with skeletal asymmetry, characterize the parents of Scottish children with OFC. These features may be of morphogenetic importance in the etiopathogenesis of OFC in this ethnic group.

Preliminary investigation of a modified Huddart/Bodenham scoring system for assessment of maxillary arch constriction in unilateral cleft lip and palate subjects

The objective of this study was to describe a numerical scoring system for the measurement of maxillary arch constriction in patients born with unilateral cleft lip and palate (UCLP). A modification of the Huddart/Bodenham scoring system was compared and contrasted with the current methods of measuring treatment outcome, the GOSLON and 5-year indices. The GOSLON and 5-year indices are represented by 10 sets of study models grouped into five categories representing the range of possible outcomes in terms of dental arch relationship, with two sets of models in each of the five categories, whilst the modified Huddart/Bodenham method uses the frequency and severity of crossbite of the dental occlusion to evaluate maxillary arch constriction. The latter system was found to be more objective and reliable, and to correlate well with current recommended standards. It was also more versatile and more sensitive to interarch discrepancies. However, further work is required to refine it to reflect the potential for orthodontic treatment to mask interarch discrepancy following surgery.

Asymmetry of the parental craniofacial skeleton in orofacial clefting

OBJECTIVE

To evaluate size-related and shape-related craniofacial skeletal asymmetries in the parents of children with orofacial clefting (OFC).

DESIGN

Retrospective PA cephalometric study.

SETTING

Glasgow/Dundee, Scotland.

SUBJECTS

Ninety-two parental volunteers from a completely ascertained sample of 286 children born with OFC between 1980-1984 in the West of Scotland.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

A conventional cephalometric asymmetry analysis (CCAA) evaluated size-related right:left asymmetry comprising eight linear distance, nine angular, and three mid-facial area measurements. The right and left landmark configurations were uniformly scaled using Procrustes superimposition and Euclidean Distance Matrix Analysis (EDMA) evaluated shape-related right-left asymmetry.

RESULTS

The three linear distances, nine angles and two areas differed between the right and left sides of the craniofacial complex (P <0.05) indicate size asymmetry characterized by a wider left side of the face and a shorter vertical dimension on the right side (directional asymmetry). EDMA detected shape asymmetry [T statistic = 2.671 (P = 0.10)]. Forty per cent of the EDMA ratios were clinically importantly larger or smaller on the left and right sides respectively, involving landmarks anatomically and morphogenetically important in OFC.

CONCLUSION

Size and shape directional asymmetries characterize the parental craniofacial skeleton in OFC. This heritable directional craniofacial skeletal asymmetry could be of relevance in the left-sided predilection of OFC.

The craniofacial morphology of the parents of children with orofacial clefting: a systematic review of cephalometric studies

OBJECTIVE

To systematically review the cephalometric studies investigating the craniofacial morphology of the parents of children with orofacial clefting (OFC).

SEARCH STRATEGY

The search strategy was based on the keywords 'parent', cephalometry', and 'cleft', identifying 17 studies, of which 15 'case/control' studies met the inclusion criteria Statistically significant clinically relevant cephalometric variables from univariate statistical tests and multivariate results were collated and presented unweighted.

RESULTS/CONCLUSIONS

The parental craniofacial complex in OFC is distinctive in comparison to the non-cleft population. However, there is insufficient consistency in study designs and results to accurately characterize the parents of children with OFC. Although the craniofacial morphology of the parents of children with CL(P) differs to the parents of children with CP, there is insufficient information to accurately localize these differences.

The Structured Clinical Operative Test (SCOT) in dental competency assessment

INTRODUCTION

This paper describes a method of assessment of invasive clinical procedures which are currently being devised, and which are perceived to be a method that may be used to complement OSCEs in overall clinical skills assessment.

OBJECTIVE

The objective of the Structured Clinical Operative Tests (SCOT) is to introduce a greater level of objectivity to the assessment of operative clinical skills. Invasive or irreversible clinical operative procedures from a large part of dental undergraduate training and are by their very nature precluded from OSCE scenarios. It is also important to test intraoperative skills, communication skills and contingency management, and performance of these with awareness of the psychosocial context and ethical framework. The paper describes the use of checklists in the monitoring of clinical operative skills in a more authentic clinical situation using the SCOT. FORMATIVE ASSESSMENT: Continuous assessment should a) record achievement of competency in as objective a manner as possible and b) should encourage continuous self-evaluation. In the SCOT the students reflect on their clinical performance and in consultation with their supervisors record their plans to improve their competence in that skill or procedure in the future. This is done immediately on completion of a clinical task while the experience is still fresh in the mind. This encourages deep reflective learning as opposed to superficial factual learning which is characteristic of the more traditional curriculum, and is described as supervisor validated self-assessment.

DISCUSSION

The discussion outlines how SCOTs can be practically implemented and integrated into the undergraduate curriculum and an example of a SCOT is appended to the paper. The scope for using SCOTs in postgraduate assessment such as in VT/GPT is also described.

Scope of the OSCE in the assessment of clinical skills in dentistry

INTRODUCTION

The objective structured clinical examination (OSCE) is now an accepted tool in the assessment of clinical skills in dentistry. There are however no strict or limiting guidelines on the types of scenario that are used in the OSCE examinations and experience and experimentation will inevitably result in the refinement of the OSCE as a tool for assessment.

AIM

The aim of this study was to compare and contrast different types of clinical operative skills scenarios in multi-station OSCE examinations.

METHODOLOGY

Student feedback was obtained immediately after the sitting of an OSCE examination on two different occasions (and two different cohorts of students). The same questionnaire was used to elicit the responses.

RESULTS

The questionnaire feedback was analysed qualitatively with particular regard to student perception of the usefulness and validity of the two different kinds of OSCE scenarios.

CONCLUSIONS

OSCE scenarios which involve phantom heads are perceived to lack clinical authenticity, and are inappropriate for the assessment of certain clinical operative skills. While the OSCE is useful in the examination of diagnostic, interpretation and treatment planning skills, it has apparent limitations in the examination of invasive operative procedures.

An investigation into the use of a structured clinical operative test for the assessment of a clinical skill

AIM

This study was designed to investigate the level of agreement between a group of assessors observing students undertaking a structured clinical operative test.

METHOD

3 assessors agreed a series of criteria to assess the performance of undergraduate students in the recording of a dental impression. Guidelines for assessing whether the students adequately performed in relation to each criteria were also agreed. Following preliminary validation between the assessors, 2 assessors independently scored the performance of each student by reference to the agreed criteria, and the levels of agreement between assessors were compared. The 3 assessors worked in pairs with each other on three groups of students who were in the early stages of their clinical course.

RESULTS

A total of 39 clinical dental students were assessed in the recording of a dental impression. The 3 pairs of assessors had satisfactory levels of agreement in the study with similar judgements being made on 90% or more of the 12 criteria assessed. Some differences existed between the pairs of assessors. Certain criteria were more easily judged than others and this was reflected in the level of agreement seen. For over 90% of the criteria, positive assessments were made by each of the 3 assessors, and although there were minor variations between the pairs of assessors, this may have reflected the ability of the groups of students studied.

CONCLUSION

The study showed that different assessors were generally able to make agreed judgements on performance criteria in a structured clinical operative test. In setting up performance assessment it is necessary to have close collaboration between assessors to make clearly defined criteria so that judgements are not too subjective. Furthermore, for the assessment of more complex clinical skills, great care is needed in assembling criteria that can be used reproducibly, and sufficient preparation time for the assessors is critical.

Oral clefts and vitamin supplementation

OBJECTIVES

The evidence linking low levels of folic acid and orofacial clefting (OFC) is presently equivocal. There is stronger evidence for the role of folic acid supplementation in protection against the occurrence and recurrence of neural tube defects. The present investigation tested the hypotheses that cleft lip, cleft palate, or both are inversely associated with maternal intake of dietary and supplemental vitamins during the periconceptional period and first 4 months of pregnancy in a Brazilian population.

DESIGN

A population-based, case-control study of cleft lip with or without cleft palate (CL(P)) and isolated cleft palate (CP) in a Brazilian population. In structured interviews, case histories were taken from the mothers of a consecutive sample of 450 infants born with nonsyndromic OFC.

RESULTS

Mothers who had children with CL(P) were less likely to have been supplemented during the periconceptional period. The statistical significance of the difference in prevalence of the use of supplements between mothers of patients and of controls was greater for the CL(P) group: p < .05 for CP and p < .001 for CL(P). Multivariate analysis confirmed this finding of a protective effect for both types of orofacial cleft.

CONCLUSIONS

The use of vitamin supplements in the first 4 months of pregnancy was suggestive of a protective effect against the occurrence of CP and CL(P) in this population. The significance of an association between multivitamin supplementation and OFC and the possible role of gene/environment interaction are discussed.

The heritability of malocclusion: part 2. The influence of genetics in malocclusion

The relative influence of genetics and environmental factors in the aetiology of malocclusion has been a matter for discussion, debate and controversy in the orthodontic literature. This paper reviews the literature and summarises the evidence for the influence of genetics in dental anomalies and malocclusion. Among the conclusions are that, while phenotype is inevitably the result of both genetic and environmental factors, there is irrefutable evidence for a significant genetic influence in many dental and occlusal variables. The influence of genetics however varies according to the trait under consideration and in general remains poorly understood. More precise research tools and methods are required to improve knowledge and understanding, which in turn is a prerequisite to the appreciation of the potential for genetic and/or environmental manipulation in orthodontic therapy.

The heritability of malocclusion: Part 1--Genetics, principles and terminology

The relative contribution of genes and the environment to the aetiology of malocclusion has been a matter of controversy throughout the twentieth century. Genetic mechanisms are clearly predominant during embryonic craniofacial morphogenesis, but environment is also thought to influence dentofacial morphology postnatally, particularly during facial growth. Orthodontic and orthopaedic techniques are used in the treatment of malocclusion and other dentofacial deformities, but with limited effectiveness. The key to the determination of the aetiology of malocclusion, and its treatability lies in the ability to differentiate the effect of genes and environment on the craniofacial skeleton in a particular individual. Our ability to do this is limited by our lack of knowledge on the genetic mechanisms that control facial growth and lack of scientific evidence for the influence of environmental factors on human craniofacial morphogenesis.

Teaching dental undergraduates behaviour change skills

This paper describes an active learning-based education tool which enables dental students to learn preventive techniques relevant to patient dental health behaviour. 2 studies were conducted involving 33, 2nd year (study 1) and 9, 3rd year (study 2) undergraduate dental students. In study 1, snacking behaviour and its antecedents were analysed from detailed 3-day diet diaries completed by the students. Study 2 entailed the students changing one aspect of their sugar/diet behaviour using self-management techniques. It is concluded that dental students can successfully (a) identify antecedents to sugar snacking behaviours on several levels, i.e., cognitive, emotional and situational, (b) set goals and use behaviour change techniques to modify these behaviours, and (c) appreciate that this experience is relevant to similar preventive techniques that they will use in clinical practice. Training in the application of these skills to their own maladaptive behaviours provides a strong educational tool based on psycho-educational theories.

Cephalometric features in the parents of children with orofacial clefting

This nonrandomised retrospective case-comparison survey was based on the hypothesis that craniofacial morphometric features can be used to identify individuals at greater risk for having children with a cleft. The theory of aetiological heterogeneity suggests there may be differences according to gender and cleft type. From a completely ascertained sample of 286 children with cleft lip and/or palate born in the West of Scotland between 1 January 1980 and 31 December 1984, a sample of 83 parents of the children with non-syndromic clefts volunteered for lateral cephalometric examination. A comparison group was derived from the archives of Glasgow Dental Hospital. Multivariate statistical analyses were applied to identify which parental craniofacial parameters, if any, determine predisposition to orofacial clefting. Compared to the male comparison group, the fathers of children with CL(P) were shown to have reduced mandibular and symphyseal areas (P < 0.001), reduced maxillary area (P < 0.01) and a shorter palatal length (P < 0.01). The cranial base angle was more acute (P < 0.01) and the cross-sectional area of the cranium on lateral skull radiographs was significantly smaller (P < 0.001). However, the occipital subtenuce was larger in the fathers (P < 0.05). The craniofacial morphology in the mothers of children with CL(P) was characterized by a longer mandible (P = 0.011), an increase in the anterior facial height (P < 0.05) and greater facial length (P < 0.01). Anterior cranial base and the clivus length were also larger in the mothers (P < 0.05). The cranial parameters showed a similar trend to the paternal group with a reduced cranial area (P < 0.01) and an increase in the occipital subtenuce length (P < 0.001). Different cephalometric parameters distinguish fathers from a male comparison group and mothers from their female counterparts. An awareness of these parameters might be of value in the prediction of liability to clefting and may prove to be important in the quest for clues to the pathogenesis of both CP and CL(P).

Prediction of liability to orofacial clefting using genetic and craniofacial data from parents

BACKGROUND

Cleft lip with or without cleft palate (CL(P)) and isolated cleft palate (CP) are separate clinical entities and for both polygenic multifactorial aetiology has been proposed. Parents of children with orofacial clefting have been shown to have distinctive differences in their facial shape when compared to matched controls.

OBJECTIVE

To test the hypothesis that genetic and morphometric factors predispose to orofacial clefting and that these markers differ for CL(P) and CP. Methods-Polymorphisms at the transforming growth factor alpha (TGFalpha) locus in 83 parents of children with nonsyndromic orofacial clefts were analysed, and their craniofacial morphology was assessed using lateral cephalometry.

RESULTS

Parents of children with CL(P) and CP showed an increased frequency of the TGFalpha/TaqI C2 allele (RR=4.10, p=0.009) relative to the comparison group. Also the TGFalpha/BamHI A1 allele was more prevalent in the CP parents. MULTIVARIATE STATISTICAL ANALYSIS: Using stepwise logistic regression analysis the TGFalpha/TaqI C2 polymorphism provides the best model for liability to orofacial clefting. To determine the type of clefting a model involving interaction between the parental TGFalpha/BamHI and TGFalpha/RsaI genotypes showed the best fit. Using genotype only to predict the clefting defect in the children according to parental genotype, 68.3% could be correctly classified. By adding information on craniofacial measurements in the parents, 76% of CP and 94% of CL(P) parents could be correctly classified.

CONCLUSIONS

This study provides a model for prediction of liability to orofacial clefting. These findings suggest that different molecular aberrations at the TGFalpha locus may modify the risk for CP and CL(P).

Defining, conferring and assessing the skills of the dentist

The task facing educators in dentistry is never an easy one. It is an area where as many questions as answers arise. This paper looks at how the skills that a dentist needs can be defined and the best way to confer them.