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1.  Tooth Wear Prevalence and Sample Size Determination : A Pilot Study 
Tooth wear is the non-carious loss of tooth tissue, which results from three processes namely attrition, erosion and abrasion. These can occur in isolation or simultaneously. Very mild tooth wear is a physiological effect of aging. This study aims to estimate the prevalence of tooth wear among 16-year old Malay school children and determine a feasible sample size for further study. Fifty-five subjects were examined clinically, followed by the completion of self-administered questionnaires. Questionnaires consisted of socio-demographic and associated variables for tooth wear obtained from the literature. The Smith and Knight tooth wear index was used to chart tooth wear. Other oral findings were recorded using the WHO criteria. A software programme was used to determine pathological tooth wear. About equal ratio of male to female were involved. It was found that 18.2% of subjects have no tooth wear, 63.6% had very mild tooth wear, 10.9% mild tooth wear, 5.5% moderate tooth wear and 1.8 % severe tooth wear. In conclusion 18.2% of subjects were deemed to have pathological tooth wear (mild, moderate & severe). Exploration with all associated variables gave a sample size ranging from 560 – 1715. The final sample size for further study greatly depends on available time and resources.
PMCID: PMC3341919  PMID: 22589636
pilot study; tooth wear; prevalence and sample size determination
2.  Severe tooth wear in Prader-Willi syndrome. A case–control study 
BMC Oral Health  2012;12:12.
Prader-Willi syndrome (PWS) is a rare complex multsystemic genetic disorder characterized by severe neonatal hypotonia, endocrine disturbances, hyperphagia and obesity, mild mental retardation, learning disabilities, facial dysmorphology and oral abnormalities. The purpose of the present study was to explore the prevalence of tooth wear and possible risk factors in individuals with Prader-Willi syndrome.
Forty-nine individuals (6-40 years) with PWS and an age- and sex-matched control group were included. Tooth wear was evaluated from dental casts and intraoral photographs and rated by four examiners using the Visual Erosion Dental Examination (VEDE) scoring system and the individual tooth wear index IA. In accordance with the VEDE scoring system, tooth wear was also evaluated clinically. Whole saliva was collected.
Mean VEDE score was 1.70 ± 1.44 in the PWS group and 0.46 ± 0.36 in the control group (p < 0.001). Median IA was 7.50 (2.60-30.70) in the PWS group and 2.60 (0.90-4.70) among controls (p < 0.001). In the PWS group tooth wear correlated significantly with age (VEDE; r = 0.79, p < 0.001, IA; r = 0.82, p < 0.001) and saliva secretion (VEDE; r = 0.46, p = 0.001, IA; r = 0.43, p = 0.002). Tooth grinding was also associated with tooth wear in the PWS group, as indicated by the mean VEDE 2.67 ± 1.62 in grinders and 1.14 ± 0.97 in non-grinders (p = 0.001) and median IA values 25.70 (5.48-68.55) in grinders and 5.70 (1.60-9.10) in non-grinders (p = 0.003). Multivariate linear regression analysis was performed with tooth wear as the dependent variable and PWS (yes/no), age, tooth grinding and saliva secretion as independent variables. PWS (yes/no), age and tooth grinding retained a significant association with tooth wear, VEDE (p < 0.001) and log IA (p < 0.001). The only factor significantly associated with tooth wear in the control group was age.
Our study provides evidence that tooth wear, in terms of both erosion and attrition, is a severe problem in Prader-Willi syndrome. There is therefore considerable need for prosthodontic rehabilitation in young adults with PWS.
PMCID: PMC3437195  PMID: 22639910
Prader-Willi syndrome; Tooth wear; Tooth grinding; Saliva secretion; Rehabilitation
3.  Tooth wear: prevalence and associated factors in general practice patients 
To estimate the prevalence of tooth wear and to investigate factors associated with tooth wear in patients from general practices in the Northwest United States.
Data on the diagnosis and treatment of oral diseases during the previous year were collected in a survey with a systematic random sample of patients (n = 1530) visiting general dentists from the Northwest Practice-based REsearch Collaborative in Evidence-based DENTistry (PRECEDENT) (n = 80). Prevalence ratios (PRs) of moderate to severe occlusal and incisal tooth wear by patient characteristics were estimated using cluster-adjusted multiple binomial regression for adults (18+ years) and children/adolescents (3–17 years).
For adults, the mean number of teeth with wear facets was 5.4 [95% confidence interval (CI) = 4.6–6.2] and 51% of the adults had four or more teeth with wear. Participants 45–64 and 65+ years old were 1.3 (95% CI = 1.1–1.6) and 1.4 (95% CI = 1.1–1.8) times as likely to have 4+ teeth with moderate to severe wear facets as participants 18–44 years old. Adult males had a 20% (PR = 1.2; 95% CI = 1.1–1.4) higher prevalence of wear than adult females. Adults who were using, or had ever used occlusal splints had higher prevalence of tooth wear compared to those who never used such appliances (PR = 1.3; 95% CI = 1.0–1.5). Adults with any periodontal bone loss also had a 20% higher prevalence of wear than adults without periodontal disease (PR = 1.2; 95% CI = 1.0–1.4). For children/adolescents, the mean number of teeth with moderate to severe wear facets was 1.6 (95% CI = 0.9–2.6) and 31% of the children had one or more teeth with wear facets. The adjusted prevalence ratio of tooth wear (1+ teeth with wear facets) for boys was 1.6 times as high (95% CI = 1.1–2.4) as compared with girls. The prevalence of wear for children 12+ years old was 50% (PR = 0.5; 95% CI = 0.3–0.8) lower than that of children <12 years old. Angle’s class II was associated with higher tooth wear prevalence (PR = 1.8; 95% CI = 1.3–2.6) than class I. Children with posterior or anterior open bite had lower prevalence of wear than their counterparts (PR = 0.6; 95% CI = 0.3–1.0). No associations were observed between tooth wear and orthodontic treatment, missing teeth, and race/ethnicity.
Tooth wear is a prevalent condition in this population. Among adults, higher prevalences of tooth wear were observed among those who were older, males, had used occlusal splints and had periodontal disease. Among children, higher prevalences were associated with younger age, male gender, class II malocclusion and the absence of open bite. Submitted on behalf of the Northwest PRECEDENT network, with support from NIDCR grants DE016750 and DE016752.
PMCID: PMC3116086  PMID: 20370807
dental practice-based research; malocclusion; Northwest PRECEDENT; tooth attrition
4.  Copper deficit as a potential pathogenic factor of reduced bone mineral density and severe tooth wear 
Osteoporosis International  2013;25(2):447-454.
The study evaluated if men and women with severe tooth wear were at increased risk of general bone loss. Enamel biopsies obtained from 50 subjects aged 47.5 ± 5 years showed decreased copper content, which was associated with reduced spine bone mineral density, suggesting deficits of this trace element contributing to bone demineralization, enamel attrition, and deteriorated quality of mineralized tissues.
The objective of this cross-sectional study was to assess associations between enamel trace minerals and bone mineral density (BMD) in severe tooth wear. We hypothesized that similar factors contributed to both the excessive abrasion of dental enamel and reduced BMD in subjects with tooth wear.
Fifty patients aged 47.5 ± 5 years with severe tooth wear and 20 age-, sex-, and body mass index (BMI)-matched healthy volunteers with normal dental status were studied regarding dietary intakes of trace elements, serum and salivary copper (Cu), zinc (Zn), and calcium (Ca) concentrations, and serum PTH, osteocalcin, and hydroxyvitamin D levels. Tooth wear was determined using clinical examination based on standard protocol according to Smith and Knight. In all subjects, acid biopsies of the maxillary central incisors were carried out to assess mineral composition of the enamel. Atomic absorption spectroscopy with an air/acetylene flame was used to measure Ca and Zn, and graphite furnace atomic absorption spectroscopy was used to analyze Cu content. BMD was examined using dual energy X-ray absorptiometry.
Tooth wear patients had reduced lumbar spine, but not femoral, BMD relative to controls (p < 0.001). No differences were found in enamel Ca concentration and Zn content was slightly higher in tooth wear patients than in controls whereas Cu content was significantly decreased in the patients: 19.59 ± 16.4 vs 36.86 ± 26.1 μg/l (p = 0.01) despite similar levels of Cu in serum and saliva. The differences were independent of serum 25-OH-D, osteocalcin concentrations or PTH either.
Severe tooth wear is associated with reduced spinal BMD. Enamel in adult individuals with severe tooth wear is low in copper content. Therefore, further work is needed to determine whether copper plays a role in bone pathophysiology in these patients.
PMCID: PMC3906556  PMID: 23797848
Bone mineral density; Copper deficit; Dental status; Enamel attrition; Enamel composition; Microelements
5.  Some Socio-Demographic Attributes as Covariates in Tooth Wear Among Males in a Rural Community in Nigeria 
Association between some socio-demographic attributes and tooth wear among adult male population in a rural community of Igbo-ora, Southwestern Nigeria was investigated in this cross-sectional study.
Cross-sectional study among 200 consenting adult males in Igbo-ora was carried out using a 10-item semi-structured questionnaire to obtain data on socio-demographics. Oral examination to establish the presence of tooth wear lesions was carried out by two examiners. Frequencies and percentages of relevant variables were generated. Multivariate analysis was used to test associations between categorical variables at P<0.05.
The mean age of participants was 35.6±11.7 years. One hundred and six (53.0%) subjects had one form of tooth wear lesion. Sixty eight (34.0%) of the subjects had attrition only and 96 (48.0%) had multiple tooth wear lesions. There was an association between age group, marital status, level of education and tooth wear (p<0.05). However, the association between occupation and tooth wear was not statistically significant (p>0.05). After adjusting for marital status, occupation and level of education, the association between age group and tooth wear was still significant. Though marital status was found to be associated with tooth wear, this association was not significant after adjusting for age, occupation and level of education. The association between some of the socio-demographic factors studied and the types of tooth wear was statistically significant (p<0.05).
Age group was the only independent predictor of tooth wear.
PMCID: PMC3511897  PMID: 23209353
Socio-demographic; Rural Community; Tooth Wear; Nigerian
6.  Involvement of a Plasmid-Encoded Type IV Secretion System in the Plant Tissue Watersoaking Phenotype of Burkholderia cenocepacia 
Journal of Bacteriology  2004;186(18):6015-6024.
Burkholderia cenocepacia strain K56-2, a representative of the Burkholderia cepacia complex, is part of the epidemic and clinically problematic ET12 lineage. The strain produced plant tissue watersoaking (ptw) on onion tissue, which is a plant disease-associated trait. Using plasposon mutagenesis, mutants in the ptw phenotype were generated. The translated sequence of a disrupted gene (ptwD4) from a ptw-negative mutant showed homology to VirD4-like proteins. Analysis of the region proximal to the transfer gene homolog identified a gene cluster located on the 92-kb resident plasmid that showed homology to type IV secretion systems. The role of ptwD4, ptwC, ptwB4, and ptwB10 in the expression of ptw activity was determined by conducting site-directed mutagenesis. The ptw phenotype was not expressed by K56-2 derivatives with a disruption in ptwD4, ptwB4, or ptwB10 but was observed in a derivative with a disruption in ptwC. Complementation of ptw-negative K56-2 derivatives in trans resulted in complete restoration of the ptw phenotype. In addition, analysis of culture supernatants revealed that the putative ptw effector(s) was a secreted, heat-stable protein(s) that caused plasmolysis of plant protoplasts. A second chromosomally encoded type IV secretion system with complete homology to the VirB-VirD system was identified in K56-2. Site-directed mutagenesis of key secretory genes in the VirB-VirD system did not affect expression of the ptw phenotype. Our findings indicate that in strain K56-2, the plasmid-encoded Ptw type IV secretion system is responsible for the secretion of a plant cytotoxic protein(s).
PMCID: PMC515160  PMID: 15342570
7.  Prevalence, severity and etiology of dental wear in patients with eating disorders 
European Journal of Dentistry  2014;8(1):68-73.
The purpose of this study was to evaluate the prevalence, distribution and associated factors of dental wear among patients with eating disorders (EDs).
Materials and Methods:
An epidemiological cross-sectional survey was conducted by trained, calibrated examiners, using the dental wear index. The sample was composed of 30 patients with EDs (experimental group – G1) and 30 control patients without current or previous history of EDs (G2). A questionnaire was used to assess the etiological factors of dental wear. The univariate analyses using the Chi-square (χ2) test were used to compare the tooth wear prevalence between groups according to the surface and tooth (P > 0.05).
The dental wear was similar for both group; however, the G1 presented more moderate wear in molars when compared with G2 (P = 0.048). The majority of EDs patients related have one or more oral habits (n = 26; 86.6%) and only 13.4% (n = 4) affirmed did not have oral habits. The etiological factors of tooth wear related with dental wear were biting objects (P = 0.04) and pain in temporomandibular disorders (P = 0.03).
The highest prevalence of dental wear was observed in the molars teeth. Differences in the extent and pattern of dental wear were found in an individual, emphasized the relevance of clinical parameter.
PMCID: PMC4054035  PMID: 24966749
Anorexic; bulimic; eating disorders; oral health; tooth wear
8.  Oral health and the impact of socio-behavioural factors in a cross sectional survey of 12-year old school children in Laos 
BMC Oral Health  2009;9:29.
In recent decades low-income countries experienced an increasing trend in dental caries among children, particularly recorded in 12-year olds, which is the principal WHO indicator age group for children. This increases the risks of negative affects on children's life. Some data exist on the oral health status of children in low-income countries of Southeast Asia. However, information on how oral health is associated with socio-behavioural factors is almost not available. The aims of this study were to: assess the level of oral health of Lao 12-year-olds in urban and semi-urban settings; study the impact of poor oral health on quality of life; analyse the association between oral health and socio-behavioural factors; investigate the relation between obesity and oral health.
A cross sectional study of 12-year old schoolchildren chosen by multistage random sampling in Vientiane, Lao P.D.R (hereafter Laos). The final study population comprised 621 children. The study consisted of: clinical registration of caries and periodontal status, and scores for dental trauma according to WHO; structured questionnaire; measurement of anthropometric data. Frequency distributions for bi-variate analysis and logistic regression for multivariate analysis were used for assessment of statistical association between variables.
Mean DMFT was 1.8 (SEM = 0.09) while caries prevalence was 56% (CI95 = 52-60). Prevalence of gingival bleeding was 99% (CI95 = 98-100) with 47% (CI95 = 45-49) of present teeth affected. Trauma was observed in 7% (CI95 = 5-9) of the children. High decay was seen in children with dental visits and frequent consumption of sweet drinks. Missed school classes, tooth ache and several impairments of daily life activities were associated with a high dD-component. No associations were found between Body Mass Index (BMI) and oral health or common risk factors. The multivariate analyses revealed high risk for caries for children with low or moderate attitude towards health, a history of dental visits and a preference for drinking sugary drinks during school hours. Low risk was found for children with good or average perception of own oral health. High risk for gingival bleeding was seen in semi-urban children and boys.
Although the caries level is low it causes considerable negative impact on daily life. School based health promotion should be implemented focussing on skills based learning and attitudes towards health.
PMCID: PMC2781791  PMID: 19917089
9.  Tooth wear in aging people: an investigation of the prevalence and the influential factors of incisal/occlusal tooth wear in northwest China 
BMC Oral Health  2014;14:65.
The aim of this study was to estimate the prevalence of tooth wear in the aging population of northwest China and to investigate the factors associated with such tooth wear.
Cross-sectional analytic clinical and questionnaire study was performed in 704 participants who had a mean age of 46.5 ± 0.2 SD and of which 367(52.13%) were males and 337(47.87%) female. These participants were invited when they attended the hospital which located in northwest China for routine oral examination.
In the maxilla of the examined patients, the rate of tooth wear varied from 85.51% for molar group, 89.77% for premolar group, 100.0% for canine group to 87.22% for incisor group. In the mandible, the rates were 86.36%, 88.92%, 100.0% and 91.19% for the four groups respectively. Moreover, both the incisor and canine groups of these patients showed median scores of 3, the premolar group showed a median score of 1, and the molar group had a median score of 2. Additionally, multiple factors were considered to contribute to these patterns of tooth wear, especially the habitual consumption of a hard or sour diet (P < 0.05,odds ratio 1.21, 95% confidence intervals 1.04-1.49).
Tooth wear is a common disease in which the anterior teeth exhibit greater wear than posterior teeth. The data support an association between tooth wear and dietary patterns.
PMCID: PMC4080580  PMID: 24902953
Tooth wear; Attrition; Erosion; Abrasion; Abfraction
10.  Characteristics associated with requested and required accelerometer wear in children 
BMJ Open  2013;3(8):e003402.
To investigate characteristics associated with wearing an accelerometer for the required and requested time among 8-year-old to 10-year-old children.
60 Bristol and North Somerset primary schools taking part in the ‘Active for Life Year 5’ randomised controlled trial (RCT) in 2011.
2048 children, aged 8–10 years, invited to wear an accelerometer for 5 days of recording.
Primary outcome measure
Numbers meeting required wear-time for inclusion in main RCT analysis (≥8 h/day ≥3 days) and numbers meeting requested wear-time (≥8 h/day for all 5 days).
817 (40%) of the children wore the accelerometer for the requested time and 1629 (80%) for the required time. In adjusted multivariable analyses the odds of wearing the accelerometer for the required time were greater in females as compared with males (OR 1.76 (1.42–2.18)), those with higher scores for reporting their mother restricted time on sedentary behaviours (1.26 (1.04–1.52) per increase of 1 on a 1–4 scale) and in children from schools with larger year group sizes (1.01 (1.00–1.02) per additional child). Living in a neighbourhood with higher levels of deprivation (0.49 (0.33–0.72) comparing highest to lowest third of the deprivation score) or reporting higher levels of weekday outdoor play (0.97 (0.94, 1.00) per 30 min more) were associated with reduced odds of meeting required time. Results were essentially the same for requested wear-time. Other characteristics, including child body mass index, were not associated with required or requested wear-time.
Only 40% of children wore the accelerometer for the requested time but 80% fulfilled the required criteria to be included in the main study analyses. Knowing which characteristics are associated with accelerometer wear could help target interventions to increase wear-time.
PMCID: PMC3753482  PMID: 23975106
Epidemiology; Public Health; Sports MEdicine
11.  Association between Periodontal Status, Oral Hygiene Status and Tooth Wear among Adult Male Population in Benin City, Nigeria 
The association between periodontal status, oral hygiene status and severity of tooth wear lesion varies from community to community and also from occupation to occupation.
To determine the association between periodontal status, oral hygiene status and tooth wear among the adult male population in Benin City, Nigeria.
Subjects and Methods:
This study was conducted among 65 male drivers, aged 25-64 years, with a mean age of 48.6 (9.1) years in an organized private motor park in Benin City between November 2011 and January 2012. The data collected through interview and clinical oral examination were age, educational status, driving experience, oral hygiene status, periodontal status and severity of tooth wear.
In this study, 13.8% (9/65) and 1.5% (1/65) of the participants had 4-5 mm and ≥6 mm periodontal pockets, respectively. A total of 15.4% (10/65) of the participants had poor oral hygiene status and 58.5% (38/65) of the participants had tooth wear lesion, with 15.8% (9/65) being severe tooth wear lesions (score 3). Participants with poorer oral hygiene and more severe tooth wear lesions significantly exhibited poorer periodontal status. There also existed a significant association between oral hygiene status and the severity of tooth wear lesion among the participants in this study.
Data from this study revealed a statistically significant association between periodontal status, oral hygiene status and severity of tooth wear lesion among the participants.
PMCID: PMC3728853  PMID: 23919180
Africa; Asia; Male population; Oral hygiene
12.  Control of replication and segregation of R plasmid Rts1. 
Journal of Bacteriology  1976;128(3):693-700.
A mutant plasmid, pTW2, which was derived from the integrated Rst1 genome in the Escherichia coli chromosome, was studied as to its mode of replication at 30 degrees C. When Proteus mirabilis Pm17 harboring pTW2 was grown in broth at 30 degrees C, a considerable number of R- segregants (approximately 40%) were consistently observed. This indicates that pTW2 is unstable even at the permissive temperature for the replication of Rts1. The pTW2+ cells in a culture were heterogeneous with respect to the level of kanamycin resistance, ranging from 500 to 4,000 mug of the drug per ml. The amount of pTW2 deoxyribonucleic acid (DNA) relative to the Pm17 chromosomal DNA was about fivefold as large as that of Rts1 DNA in an exponentially growing culture. In addition, pTW2 in P. mirabilis continued to replicate after the chromosome had ceased to replicate, which was shown in the study of the inhibition of protein synthesis. Contrary to pTW2, the parent plasmid Rts1 is highly stable, and the relative percent Rts1 DNA is maintained at approximately 7% in any cultural conditions at a permissive temperature. These results suggest that copies of pTW2 may not segregate evenly into the host progeny upon cell division and that the replication of pTW2 does not coordinate with that of the chromosome. A remarkable instability of pTW2 as well as an increase in the relative percent pTW2 DNA was also shown when E. coli were used as the host cells. These results suggest the possibility that there is a gene or a gene cluster on the Rst1 genome responsible for the control of both replication and segregation of Rts1.
PMCID: PMC232757  PMID: 791923
13.  A survey of oral health in a Sudanese population 
BMC Oral Health  2012;12:5.
We aimed to assess the oral health status and risk factors for dental caries and periodontal disease among Sudanese adults resident in Khartoum State. To date, this information was not available to health policy planners in Sudan.
A descriptive population-based survey of Sudanese adults aged ≥ 16 years was conducted. After stratified sampling, 1,888 adult patients from public dental hospitals and dental health centres scattered across Khartoum State, including different ethnic groups present in Sudan, were examined in 2009-10. Data were collected using patient interviews and clinical examinations. Dental status was recorded using the DMFT index, community periodontal index (CPI), and a validated tooth wear index.
Caries prevalence was high, with 87.7% of teeth examined having untreated decay. Periodontal disease increased in extent and severity with age. For 25.8% of adults, tooth wear was mild; 8.7% had moderate and 1% severe toothwear. Multivariate analysis revealed that decay was less prevalent in older age groups but more prevalent in southern tribes and frequent problem based attenders; western tribes and people with dry mouths who presented with less than18 sound, untreated natural teeth (SUNT). Older age groups were more likely to present with tooth wear; increasing age and gender were associated with having periodontal pocketing ≥ 4 mm.
The prevalence of untreated caries and periodontal disease was high in this population. There appear to be some barriers to restorative dental care, with frequent use of dental extractions to treat caries and limited use of restorative dentistry. Implementation of population-based strategies tailored to the circumstances of Sudanese population is important to improve oral health status in Sudan.
PMCID: PMC3311612  PMID: 22364514
14.  A Case Report of Tooth Wear Associated with a Patient's Inappropriate Efforts to Reduce Oral Malodor Caused by Endodontic Lesion 
Here, we report a case of severe tooth wear associated with a patient's inappropriate efforts to reduce oral malodor. A 72-year-old male patient visited our breath clinic complaining of strong breath odor. Former dentists had performed periodontal treatments including scaling and root planing, but his oral malodor did not decrease. His own subsequent breath odor-reducing efforts included daily use of lemons and vinegar to reduce or mask the odor, eating and chewing hard foods to clean his teeth, and extensive tooth brushing with a hard-bristled toothbrush. Oral malodor was detected in our breath clinic by several tests, including an organoleptic test, portable sulphide monitor, and gas chromatography. Although patient's oral hygiene and periodontal condition were not poor on presentation, his teeth showed heavy wear and hypersensitiving with an unfitted restoration on tooth 16. Radiographic examination of the tooth did not reveal endodontic lesion, but when the metal crown was removed, severe pus discharge and strong malodor were observed. When this was treated, his breath odor was improved. After dental treatment and oral hygiene instruction, no further tooth wear was observed; he was not concerned about breath odor thereafter.
PMCID: PMC2836914  PMID: 20339568
15.  Weight, height and eruption times of permanent teeth of children aged 4–15 years in Kampala, Uganda 
BMC Oral Health  2013;13:15.
Tooth eruption is a continuous biological process by which developing teeth emerge through the jaws and the overlying mucosa to enter into the oral cavity. Tooth eruption time and sequence are important factors in dental treatment planning, particularly in orthodontics, but also in forensic dentistry to estimate age of a child. Tooth eruption time is influenced by many factors. In this study we set out to determine the timing of eruption of permanent teeth and assess its association with the height and weight of school children aged 4–15 years in Kampala, Uganda.
This was a cross sectional study comprising of 1041 healthy Ugandan children: boys/girls (520/521) who were consecutively selected from two primary schools in Kampala. The children were clinically assessed for tooth emergency through the oral mucosa as well as measuring their weight and height. The mean and standard deviation of tooth eruption time was estimated for boys and girls. Bivariate analysis was used to assess any significant association between tooth eruption time and demographic variables. Pearson and partial correlation analyses were used to assess any significant association between the tooth eruption time and anthropometric measurements of the children.
Generally, the mean eruption times for girls were lower compared to boys except for three teeth (#25, #32 and #42) which erupted earlier in boys. The average difference in mean eruption times of all teeth between boys and girls was found to be 0.8 (range, 0–1.5) years. In partial correlation analysis, mean tooth eruption times were positively, but not significantly associated with height while controlling for weight except for the mandibular left central incisor (#31). On the other hand, in partial correlation analysis, mean tooth eruption times were positively associated with weight while controlling for height except for tooth #11, #16, #26 and #41. The weight of the child was significantly correlated with mean eruption times in 50% of the teeth.
In the present study, the mean tooth eruption times for girls were lower compared to boys except for three teeth (#25, #32 and #42). The height of the child did not show any significant influence on the tooth eruption times while the influence of weight on tooth eruption times was non-conclusive.
PMCID: PMC3606623  PMID: 23497340
Height; Permanent teeth; Tooth eruption age; Uganda; Weight
16.  Dental caries prevalence, oral health knowledge and practice among indigenous Chepang school children of Nepal 
BMC Oral Health  2013;13:20.
Chepang communities are one of the most deprived ethnic communities in Nepal. According to the National Pathfinder Survey, dental caries is a highly prevalent childhood disease in Nepal. There is no data concerning the prevalence of caries along with knowledge, attitude and oral hygiene practices among Chepang schoolchildren. The objectives of this study were to 1) record the prevalence of dental caries 2) report experience of dental pain 3) evaluate knowledge, attitude and preventive practices on oral health of primary Chepang schoolchildren.
A cross sectional epidemiological study was conducted in 5 government Primary schools of remote Chandibhanjyang Village Development Committee (VDC) in Chitwan district. Ethical approval was taken from the Institutional Review Board within the Research Department of the Institute of Medicine (IOM) Tribhuvan University. Consent was obtained from parents for conducting clinical examination and administrating questionnaire. Permission was taken from the school principal in all schools. Data was collected using a pretested questionnaire on 131 schoolchildren aged 8-16-year- olds attending Grade 3–5. Clinical examination was conducted on 361 school children aged 5–16 –year-olds attending grade 1–5. Criteria set by the World Health Organization (1997) was used for caries diagnosis. The questionnaires, originally constructed in English and translated into Nepali were administered to the schoolchildren by the researchers. SPSS 11software was used for data analysis.
Caries prevalence for 5–6 –year-old was above the goals recommended by WHO and Federation of Dentistry international (FDI) of less than 50% caries free children. Caries prevalence in 5-6-year-olds was 52% and 12-13-year-olds was 41%. The mean dmft/DMFT score of 5–6 –year-olds and 12 -13-year -olds was 1.59, 0.31 and 0.52, 0.84 respectively. The DMFT scores increased with age and the d/D component constituted almost the entire dmft/DMFT index. About 31% of 8-16-year-olds school children who participated in the survey reported having suffered from oral pain. Further, the need for treatment of decayed teeth was reported at 100%. About 76% children perceived teeth as an important component of general health and 75% reported it was required to eat. A total 93% children never visited a dentist or a health care service. Out of 56% children reporting cleaning their teeth daily, only 24% reported brushing their teeth twice daily. About 86% of the children reported using toothbrush and toothpaste to clean their teeth. Although 61% children reported to have received oral health education, 82% children did not know about fluoride and its benefit on dental health. About 50% children reported bacteria as the main cause of tooth decay and 23% as not brushing teeth for gingivitis. Frequency of sugar exposure was low; 75% of children reported eating sugar rich food once daily.
Caries prevalence of 5–6 –year- old Chepang school children is above the recommended target set by FDI/WHO. The study reported 31% schoolchildren aged 8-16-year old suffered oral pain and decayed component constituted almost the entire dmft/DMFT index. The brushing habit was reportedly low with only 24% of the children brushing twice daily. A nationwide scientifically proven, cost effective school based interventions is needed for prevention and control of caries in schoolchildren in Nepal.
PMCID: PMC3655880  PMID: 23672487
Dental caries; School children; Oral hygiene
17.  Patient and surgery related factors associated with fatigue type polyethylene wear on 49 PCA and DURACON retrievals at autopsy and revision 
Polyethylene wear is an important factor for longevity of total knee arthroplasty. Proven and suspicious factors causing wear can be grouped as material, patient and surgery related. There are more studies correlating design and/or biomaterial factors to in vivo wear than those to patient and surgery related factors. Many retrieval studies just include revision implants and therefore may not be representative. This study is aimed to correlate patient- and surgery- related factors to visual wear score by minimizing design influence and include both autopsy and revision implants. Comparison between the groups was expected to unmask patient and surgery-related factors responsible for wear.
The amount of joint side wear on polyethylene retrievals was measured using a modification of an established visual wear score. Fatigue type wear was defined as summation of the most severe wear modes of delamination, pitting and cracks. Analysis of patient and surgery related variables suspicious to cause wear included prospectively sampled patient activity which was measured by self reported walking capacity. Statistical analysis was done by univariate analysis of variance. Activity level and implantation time were merged to an index of use and correlated to the wear score.
Wear score after comparable implantation time was significantly less in the autopsy group. Even so, fatigue type wear accounted for 84 and 93 % of total wear score on autopsy and revision implants respectively. A highly significant influence on wear score was found in time of implantation (p = 0.002), level of activity (p = 0.025) and inserts belonging to revision group (p = 0.006). No influence was found for the kind of patella replacement (p = 0.483). Body mass index and accuracy of component alignment had no significant influence on visual wear score. Fatigue-type wear in the medial compartment was closely correlated to the index of use in the autopsy (R2 = 0.383) and the revision group (R2 = 0.813).
The present study's finding of substantial fatigue type wear in both autopsy and revision retrievals supports the theory that polyethylene fatigue strength is generally exceeded in this type of prosthesis. Furthermore, this study correlated fatigue-type polyethylene wear to an index of use as calculated by activity over time. Future retrieval studies may use activity over time as an important patient related factor correlated to the visual wear score. When evaluating total knee arthroplasty routine follow up, the surgeon must think of substantial wear present even without major clinical signs.
PMCID: PMC2289815  PMID: 18294372
18.  Rates of, and the factors affecting, cycle helmet use among secondary schoolchildren in East Sussex and Kent 
Injury Prevention  1998;4(2):106-110.
Objectives—To assess the level of cycle helmet wearing among young people in two counties in the South East of England in 1994, and to identify the factors associated with helmet wearing.
Design—Cross sectional survey in a convenience sample.
Setting—Secondary schools in East Sussex and Kent.
Subjects—Students in year 7 (aged 10–12 years) and year 11 (aged 14–16 years).
Main outcome measures—Self reported "always wears a helmet".
Results—Among those who ride a bicycle, 32% of boys and 29% of girls aged 10–12 years, and 14% of boys and 10% of girls aged 14–16, reported that they always wear helmets. The variables that were most consistently associated with helmet wearing (that is significantly associated with helmet wearing in at least five of the six age, sex, and county subgroups) were: "parental encouragement to wear a helmet", "closest friend wears a helmet", "belief that laws that make children wear helmets are good", and "sometimes rides off-road".
Conclusions—The self reported rates of always wearing a cycle helmet in East Sussex and Kent are consistent with overseas findings for populations who had not been exposed to intensive helmet promotion. The evidence suggests that parental encouragement has a favourable effect on rates of cycle helmet use among secondary schoolchildren, which is separate from and additional to peer influences. When designing a helmet promotion programme, therefore, it will have added impact if both parents and children are addressed.
PMCID: PMC1730369  PMID: 9666363
19.  Relationship of Tooth Wear to Chronological Age among Indigenous Amazon Populations 
PLoS ONE  2015;10(1):e0116138.
In indigenous populations, age can be estimated based on family structure and physical examination. However, the accuracy of such methods is questionable. The aim of this cross-sectional study was to evaluate occlusal tooth wear related to estimated age in the remote indigenous populations of the Xingu River, Amazon. Two hundred and twenty three semi-isolated indigenous subjects with permanent dentition from the Arara (n = 117), Xicrin-Kayapó (n = 60) and Assurini (n = 46) villages were examined. The control group consisted of 40 non-indigenous individuals living in an urban area in the Amazon basin (Belem). A modified tooth wear index was applied and then associated with chronological age by linear regression analysis. A strong association was found between tooth wear and chronological age in the indigenous populations (p <0.001). Tooth wear measurements were able to explain 86% of the variation in the ages of the Arara sample, 70% of the Xicrin-Kaiapó sample and 65% of the Assurini sample. In the urban control sample, only 12% of ages could be determined by tooth wear. These findings suggest that tooth wear is a poor estimator of chronological age in the urban population; however, it has a strong association with age for the more remote indigenous populations. Consequently, these findings suggest that a simple tooth wear evaluation method, as described and applied in this study, can be used to provide a straightforward and efficient means to assist in age determination of newly contacted indigenous groups.
PMCID: PMC4300213  PMID: 25602501
20.  Dental caries and associated factors among primary school children in Bahir Dar city: a cross-sectional study 
BMC Research Notes  2014;7(1):949.
Dental caries is the most common chronic infectious disease of childhood caused by the interaction of bacteria, mainly Streptococcus mutans and sugary foods on tooth enamel. This study aimed at determining the prevalence and associated factors of dental caries among primary school children at Bahir Dar city.
A school based cross-sectional study was conducted at Bahir Dar city from October 2013 to January 2014. Systematic random sampling technique was used to select the children. Structured questionnaire was used to interview children and/or parents to collect socio demographic variables. Clinical dental information obtained by experienced dentist using dental caries criteria set by World Health Organization. Binary and multiple logistic regression analysis were computed to investigate factors associated with dental caries.
Of the 147 children, 82 (55.4%) were girls. Majority of the children (67.6%) cleaned their teeth using traditional method (small stick of wood made of a special type of plant). The proportion of children having dental caries was 32 (21.8%). Primary tooth decay accounted for 24 (75%) of dental caries. The proportion of missed teeth was 7 (4.8%). The overall proportion of toothache and dental plaque among school children were 40 (27.2%) and 99 (67.3%), respectively. Grade level of 1–4 (AOR = 3.9, CI = 1.49 -10.4), poor habit of tooth cleaning (AOR = 2.6, CI = 1.08 - 6.2), dental plaque (AOR = 5.3, CI = 1.6 - 17.7) and toothache (AOR = 6.3, CI = 2.4 – 15.4) were significantly associated with dental caries.
Dental caries is a common public health problem in school children associated with poor oral hygiene, dietary and dental visit habits. Therefore, prevention measures such as health education on oral hygiene, dietary habits and importance of dental visit are obligatory for children.
PMCID: PMC4307198  PMID: 25540044
Dental caries; Dental plaque; Children
21.  Relationship between Food Habits and Tooth Erosion Occurrence in Malaysian University Students 
Tooth erosion is a growing dental problem; however, the role of diet in the aetiology of tooth erosion is unclear. A cross-sectional study was conducted to determine the association between tooth erosion occurrence and the consumption of acidic foods and drinks among undergraduate university students.
A total of 150 undergraduate students (33 males and 117 females) aged 19 to 24 years at Universiti Kebangsaan Malaysia participated in this study. The Basic Erosive Wear Examination was used to assess the occurrence of tooth erosion. Information regarding dental hygiene practices, usual dietary habits, and consumption of acidic foods and drinks was obtained through a structured questionnaire.
In all, 68% of subjects had tooth erosion. Subjects who reported having received information about healthy eating were less likely to have tooth erosion (χ2 [1, N = 150] = 7.328, P = 0.007). The frequencies of milk (OR = 0.29, 95% CI = 0.13–0.67) and tea/coffee (adjusted OR = 0.42, 95% CI = 0.19–0.95) consumption were negatively associated with tooth erosion. Dental hygiene practice, the frequency and amount of acidic food and drink intake, and body mass index classification were not significantly associated with the risk of tooth erosion (P > 0.05).
A high prevalence of tooth erosion was observed among this group of students. Preventive measures, such as dietary advice and increased consumption of milk at a younger age, may reduce the occurrence of tooth erosion among this age group.
PMCID: PMC3431744  PMID: 22973138
beverages; cross-sectional study; food habits; public health; tooth erosion; young adult
22.  Impact of removable dentures on oral health-related quality of life among elderly adults in Taiwan 
BMC Oral Health  2015;15:1.
Although the use of removable dentures can improve oral function and esthetics for elderly people, compared to those who do not wear removable dentures, those wearing removable dentures could have worse oral health related-quality of life (OHRQoL). Additional information is required to assess which factors related to denture wearing influence the OHRQoL of elderly individuals. The purpose of this study is to evaluate the association between denture wearing and OHRQoL in a sample of elderly individuals in Taiwan.
The study population included 277 elderly people wearing removable dentures (mean age = 76.0 years). Using face-to-face interviews, we collected data on the participants’ socio-demographic characteristics, dental care service usage (regular dental checkups, treatment during toothache, dental visits in the last year), and factors related to denture wearing (perceived oral pain, perceived loose denture, perceived oral ulcer, perceived halitosis, perceived dry mouth, and perceived total denture satisfaction scores). OHRQoL was measured using the Taiwanese version of the Geriatric Oral Health Assessment Index (GOHAI-T). The location and number of remaining natural teeth and the type of denture were also recorded. Hierarchical multiple regression analysis was performed using GOHAI-T scores as the dependent variable.
All the predictors together accounted for 50% of the variance in GOHAI-T scores. Further, education level, number of natural teeth, denture status, perceived loose denture, perceived oral ulcer, and perceived total denture satisfaction scores had statistically significant influences on OHRQoL. When compared with other variables, factors related to denture wearing, especially perceived total denture satisfaction scores, had the greatest impact on GOHAI-T scores.
Of the factors analyzed in this study, denture satisfaction was the strongest predictor of OHRQoL. This suggests that denture satisfaction is useful for assessing the effect of denture treatment on the OHRQoL of elderly individuals wearing removable dentures.
PMCID: PMC4298049  PMID: 25559722
Elderly; Removable dental prostheses; Oral health-related quality of life; Geriatric oral health assessment index; Denture satisfaction; Dental care service
23.  Evaluation of oral health status and salivary flow rate in obese patients after bariatric surgery 
European Journal of Dentistry  2012;6(2):191-197.
The aim of this study was to identify the prevalence of dental caries, periodontal diseases and tooth wear in bariatric patients, and relate the oral health conditions to saliva flow.
Fifty-two patients who had undergone bariatric surgery (Roux-en-Y gastric bypass) and 50 severely obese patients indicated for bariatric surgery were submitted to clinical examinations with regard to dental caries (DMFT index), periodontal condition (CPI index), dental wear (DWI index – Dental wear index) and saliva flow. The data were statistically analyzed by the Student’s-t, Mann-Whitney, Spearman Correlation and Chi-square (χ2) tests at 5% significance level.
The DMFT index was 16.11±5.19 in the surgical group and 16.06±6.29 in the control group (P>.05). The mean CPI was 3.05±0.84 for the operated group and 2.66±1.25 for the obese patients with no significant difference between them (P>.05). There was statistically significant difference between the groups for the presence of periodontal pockets (P=.021). All the patients presented some degree of tooth wear, however, with no significant difference between the two groups (P=.82). The mean saliva flow values of the surgical group and control group were 0.64±0.46 mL/min and 0.66±0.49 mL/min, respectively. There was no significant difference in saliva flow and all oral conditions analyzed (P>.05).
The prevalence of oral diseases was similar in severely obese patients who were candidates for bariatric surgery and in patients who had been submitted to bariatric surgery. Nevertheless, there was higher prevalence of periodontal pockets in the operated group.
PMCID: PMC3327499  PMID: 22509123
Oral health; tooth erosion; periodontal diseases; dental caries; xerostomia; obesity; bariatric surgery
24.  Effects of the crude extract of Polygala tenuifolia Willd on human sperm in vitro*  
The aim of the present study is to analyze sperm membrane changes and the spermicidal effect in treatment with the crude extract from Polygala tenuifolia Willd (PTW) in vitro. The root of PTW was extracted in distilled water. Normal human spermatozoa were used to assess the spermicidal activity (Sander-Cramer assay) of the extract from the PTW root. The hypo-osmotic swelling (HOS) test and the eosin Y (EY) staining were used to detect the integrity of sperm membrane and vitality. The sperm chromatin dispersion (SCD) test was performed to determine sperm DNA integrity. N-9 was used as a reference standard and semen added to physiological saline was used as the control. Semen samples were donated by 42 healthy fertile men. The crude extract from the root of PTW could immobilize and kill 100% spermatozoa within 20 s in vitro at the concentrations of 20.0 and 10.0 mg/ml; at the concentration of 5.0 mg/ml, spermatozoa were immobilized in (39.5±3.2) s. In the groups of the crude extract from the root of PTW and N-9 solution, the rate of the normal HOS (tails swollen) and the white head (unstained) was 0%, and the rate of the abnormal HOS (tails unswollen) and red head (stained) was 100%. Sperm DNA fragmentation showed no change in exposure to the crude extract from the root of PTW and N-9 solution. The sperm revival test did not show any spermatozoa that recovered their motilities. The rapid spermicidal activity of the crude extract from the root of PTW in vitro may occur by the disruption of the sperm membrane integrity.
PMCID: PMC3109146  PMID: 21634037
Polygala tenuifolia Willd; Crude extract; Spermicidal effect in vitro; Sperm membrane; DNA integrity
25.  Cigarette smoking and tooth loss experience among young adults: a national record linkage study 
BMC Public Health  2007;7:313.
Various factors affect tooth loss in older age including cigarette smoking; however, evidence regarding the association between smoking and tooth loss during young adulthood is limited. The present study examined the association between cigarette smoking and tooth loss experience among adults aged 20–39 years using linked data from two national databases in Japan.
Two databases of the National Nutrition Survey (NNS) and the Survey of Dental Diseases (SDD), which were conducted in 1999, were obtained from the Ministry of Health, Labor and Welfare with permission for analytical use. In the NNS, participants received physical examinations and were interviewed regarding dietary intake and health practices including cigarette smoking, whereas in the SDD, participants were asked about their frequency of daily brushing, and received oral examinations by certified dentists. Among 6,805 records electronically linked via household identification code, 1314 records of individuals aged 20 to 39 years were analyzed. The prevalence of 1+ tooth loss was compared among non-, former, and current smokers. Multiple logistic regression models were constructed including confounders: frequency of tooth brushing, body mass index, alcohol consumption, and intake of vitamins C and E.
Smoking rates differed greatly in men (53.3%) and women (15.5%). The overall prevalence of tooth loss was 31.4% (31.8% men and 31.1% women). Tooth loss occurred more frequently among current smokers (40.6%) than former (23.1%) and non-smokers (27.9%). Current smoking showed a significant association with 1+ tooth loss in men (adjusted OR = 2.21 [1.40–3.50], P = 0.0007) and women (1.70 [1.13–2.55], P = 0.0111). A significant positive exposure-related relationship between cigarette smoking status and tooth loss was observed (P for trend < 0.0001 and 0.0004 in men and women, respectively). Current smoking was also associated with the prevalence of decayed teeth (1.67 [1.28–2.20], P = 0.0002).
An association between cigarette smoking and tooth loss was evident among young adults throughout Japan. Due to limitations of the available variables in the present databases, further studies including caries experience and its confounders should be conducted to examine whether smoking is a true risk of premature tooth loss in young adults.
PMCID: PMC2186324  PMID: 17976246

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