Synthesis, crystal structure and theoretical studies of a Schiff base 2-[4-hydroxy benzylidene]-amino naphthalene.

The molecular structure of a new Schiff base, 2-[4-hydroxy benzylidene]-amino naphthalene (HBAN) has been examined by HF and B3LYP/6-311++G(d,p) calculations. The X-ray structure was determined in order to establish the conformation of the molecule. The compound, C17H13NO, crystallizes in the orthorhombic, P212121 space group with the cell dimension, a=6.2867(2), b=10.2108(3), c=19.2950(6) Å, α=ß=γ=90° and z=4. The asymmetric unit contains a molecule of a Schiff base. A strong intermolecular O-H⋯N and a weak C-H⋯O hydrogen bonds stabilized the crystal structure. The vibrational spectra of HBAN have been calculated using density functional theoretical computation and compared with the experimental. The study is extended to the HOMO-LUMO analysis to calculate the energy gap (Δ), Ionization potential (I), Electron Affinity (A), Global Hardness (η), Chemical Potential (µ) and Global Electrophilicity (w). The calculated HOMO and LUMO energy reveals that the charge transfer occurs within the molecule.

Prevalence of oral precancerous and cancerous lesions in elderly Malaysians.

A house to house survey on elderly subjects aged 60 years old and above was undertaken in a large district in Malaysia. A total of 486 subjects in randomly selected Enumeration Blocks were interviewed and examined. The prevalence of oral precancerous lesions was recorded at 3.3%, of which leukoplakia was the most common. When the ethnic distribution of these oral precancerous and cancerous (OPC) lesions was compared, 72% of those inflicted were Indians. Oral cancer was detected in two subjects (0.4%), both of whom were of Indian origin. Among subjects with OPC lesions, 4.2% were smokers, 12.7% were betelquid chewers, 11.8% had indulged in both habits, whilst one subject had not practised any of the oral habits of interest (0.4%). The findings suggest the occurrence of OPC lesions to be related to betelquid chewing.

Patient education and preventive care in Malaysian dental practice.

A questionnaire survey was conducted to examine the attitudes of Malaysian dentists toward patient education and preventive dentistry and the level of preventive care adopted in Malaysian dental practice. An adjusted response rate of 73.1% was obtained. Generally the Malaysian dentists had positive attitudes towards patient education and preventive dentistry including fluoridation. However, a sizable proportion of them considered that preventive measures were no challenge for the dentist. The common preventive measures given to patients were scaling, dental health education, prophylaxis and instruction in correct brushing and flossing in as much as 40 to 50 percent of the queried dentist claimed that these preventive items were provided to most or all of their new patients. In spite of the fact that the majority of the dentists had good knowledge about the application and effects of sealants only about 41 percent of the dentists claimed to have used sealants. More dentists in the private sector reportedly having done so. Also many Malaysian dentists (18.5%) did not use leaded protection for any of their new patients when taking radiographs.

Utilization, knowledge and attitudes concerning sealants among Malaysian dentists: a national survey.

The aim of this postal survey was to assess the utilization, knowledge and attitude concerning sealants among Malaysian dentists. A pretested questionnaire was sent to all dentists (1217) who were on the Dentist Register of Malaysia of 1987. A response rate of 61.1% was obtained. The results indicate that 52.6% of the respondents have used sealants, but of these only 13.6% have used them frequently. The two "knowledge" related questions receiving the most support concerned the suitability of the first permanent molars for sealants and the loss of sealants attributable to problems at the time of application. The two "attitudinal" questions receiving the most support concerned the value of sealants in preventing dental caries and the need for the profession to expand more efforts toward increasing public demand for sealants. Only about 50% of the respondents believed that sealants are cost-effective.

Ethnic variations of sweet preferences in Malaysian children: a pilot study.

Diet and sugar eating habits, in particular sweet preference levels, are gradually nurtured over time by culturally accepted dietary norms. The dietary habits of Malaysia's three main ethnic groups are distinctively different from each other and expectedly, many studies have discovered significant ethnic variations in caries experience. In order to guide further research work into the causes of these variations, this pilot study was designed to establish whether ethnic variations exist in sweet preference levels. This study found that although the difference in sweet preference between boys and girls in this sample was not statistically significant, the ethnic variation was statistically significant. The implications of this study and suggestions for further research in this field are discussed.

The causes of tooth mortality of permanent teeth in a Malaysian population.

The reasons underlying the need for extraction of 2765 permanent teeth carried out over a 6 month period in the Out-patient Clinic in the Dental Faculty, University of Malaya, was investigated. The present study showed that dental caries (67.4%) is the leading cause for extraction followed by periodontal disease (19.6%). Caries accounted for the highest proportion of extractions up to the age of 50 whereas periodontal disease becomes the major factor beyond this age. The highest frequency of extractions carried out was between the ages of 21-30.

A 5-year longitudinal study of caries development in first permanent molars in children.

The present study analysed the development of caries in 653 first permanent molars annually over a period of 5 years in children who were 7 years-old at baseline. The cumulative caries experience increased from 6.0% at baseline to 35.2% at the end of the study period. There were no appreciable differences in the annual incremental rate of caries experience among males and females. At baseline, the Malays and Indians have the highest and lowest caries experience respectively. At 12 years of age, the Chinese have the highest caries experience whilst the data for the Malays and Indians were comparable. The highest cumulative percentage increase in caries experience for the Malays, Chinese and Indians were between the ages of 7 to 8, 9 to 10 and 8 to 9 respectively while the average annual caries increment were 4.5%, 7.3% and 5.0% respectively.

Reasons for seeking dental care in a Malaysian urban adult population: an analysis by sex and ethnic group.

Different groups of people will view and use modern dental services differently. This is determined by their traditional beliefs and cultural background. The aim of this study is to identify variations in utilization among adults in the three major ethnic groups in Malaysia. Dental records of 500 adults attending the University dental center were randomly selected and analyzed by sex and ethnic group. Results from this pilot study clearly indicate that different ethnic groups tend to use certain types of services more than others. Similarly, there is evidence of variation in the type of dental service preferred between males and females. The implications of these findings for dental health educators, program planners and further research is emphasized in order to promote a more positive pattern of utilization among the various ethnic groups.

Enamel defects in 11-12 year-old subjects in a fluoridated area.

Enamel defects were studied in a group of 11-12 year-old children in a fluoridated area using the DDE index. The mouth prevalence of this condition was 72.5 per cent with a tooth prevalence of 40.4 per cent. Enamel opacities accounted for 96.5 per cent of the total condition of which the diffuse patchy type predominates. The defects on the affected posterior teeth occurred most commonly on both the buccal and lingual/palatal surfaces, with most defects being located in the incisal one-half, gingival one-half and occlusal simultaneously. In the affected incisors, the highest proportion of defects affected the buccal surface only, with the most frequent location being the incisal one-half and gingival one-half simultaneously. In 20.9 per cent of the affected subjects, there was a 100 per cent tooth involvement.

Toothbrushing effectiveness of a group of six-year-old uninstructed schoolchildren.

The main purpose of this study was to evaluate the effectiveness of toothbrushing in 124 six year-old uninstructed schoolchildren. The toothbrushing conditions were made to closely simulate the toothbrushing procedure carried out at home. The amount of plaque before and after toothbrushing was assessed using the Modified Personal Hygiene Performance Index. An overall reduction of 54.0 per cent in plaque score was observed following toothbrushing. This reduction was much more favourable than other reported studies using subjects of similar age group. However most of the plaque that remained following brushing were accumulated in the gingival areas. The highest prebrushing score and the least effective toothbrushing ability was observed among the Malay schoolchildren. The pre and postbrushing scores among the Chinese and Indians were comparable. There was no statistically significant difference in toothbrushing ability between boys and girls at this age. The children brushed their anterior teeth better than their posterior and the facial surfaces better than the lingual. The greatest percentage reduction in plaque score was observed in the occlusal/incisal areas with the gingival areas being the least accessible. The conclusions of this study points to the lack of manual dexterity of children of this age group to effectively brush their teeth and the need for proper parental supervision in assisting them to carry out the toothbrushing procedure.

Accuracy of tooth length measurements from periapical radiographs.

This study was undertaken to investigate and assess two radiographic techniques for measuring tooth length. The result of this study demonstrated the inadequacy of determining tooth lengths using radiographs alone without the introduction of instruments into the canal as close as possible to the root apex. Neither of the techniques proved ideal, however, the Paralleling Extension Tube Technique seemed relatively more accurate and reliable than the Bisecting-Angle Technique.