A new classification system of trifid mandibular canal derived from Malaysian population.

BACKGROUND: The purpose of this study was to identify and classify the anatomic variation of mandibular canal among Malaysians of three ethnicities. MATERIALS AND METHODS: The courses of the mandibular canal in 202 cone-beam computed tomography scanned images of healthy Malaysians were evaluated, and trifid mandibular canal (TMC) when present, were recorded and studied in detail by categorizing them to a new classification (comprising of 12 types). The diameter and length of canals were also measured, and their shape determined. RESULTS: Trifid mandibular canals were observed in 12 (5.9%) subjects or 16 (4.0%) hemi-mandibles. There were 10 obvious categories out the 12 types of TMCs listed. All TMCs (except one) were observed in patients older than 30 years. The prevalence according to ethnicity was 6 in Malays, 5 in Chinese and 1 in Indian. Four (33.3%) patients had bilateral TMCs, which was not seen in the Indian subject. More than half (56.3%) of the accessory canals were located above the main mandibular canal. Their mean diameter was 1.32 mm and 1.26 mm for the first and second accessory canal, and the corresponding lengths were 20.42 mm and 21.60 mm, respectively. Most (62.5%) canals had irregularly shaped lumen; there were more irregularly shaped canals in the second accessory canal than the first branch. None of the second accessory canal was oval (in shape). CONCLUSIONS: This new classification can be applied for the variations in the branching pattern, length and shape of TMCs for better clinical description.

Distribution of Molar Incisor Hypomineralization in Malaysian Children Attending University Dental Clinic.

OBJECTIVES: Molar-Incisor Hypomineralization (MIH) is a condition of hypomineralized enamel of systemic origin affecting first permanent molars and frequently permanent incisors. It is considered a global problem and data from South-East Asian countries, including Malaysia are lacking. Hence the aim of this study were to investigate the distribution and severity of MIH in a group of children aged 7-12 year olds attending pediatric dental clinic at Faculty of Dentistry, Universiti Teknologi MARA (UiTM), Malaysia. STUDY DESIGN: Hundred and fifty four children age 7-12 year-old with mean age of 9.14 ±1.682 had their first permanent molars and permanent incisors were examined at Faculty of Dentistry, UiTM using European Academy of Paediatric Dentistry 2003 (EAPD) criteria for diagnosis of MIH. Children at least one first permanent molar affected were considered as having MIH. Data were recorded and statistically analysed using descriptive analysis and Chi square test. RESULTS: Twenty six of the total examined children (n=154) had MIH (16.9%). There was no statistical difference between males and females in the prevalence of MIH. However, a statistical significant difference was found by age groups. The first permanent molars were more frequently affected (58%) as compared to permanent incisors. Mandibular molars were to have the highest rate of MIH (15.5%). The right and left sides were equally affected. Mild defects were the most frequent lesion type (96.6%). CONCLUSIONS: This study revealed that MIH is a common condition (16.9%). Molars were more frequently affected than incisors with mild defects were the most common lesion status. Further studies on this defect amongst Malaysian children are worthwhile.

Knowledge, management and perceived barriers to treatment of molar-incisor hypomineralisation in general dental practitioners and dental nurses in Malaysia.

BACKGROUND: Molar-incisor hypomineralisation (MIH) is a global dental problem, yet little is known about the knowledge of the general dental practitioners (GDPs) and dental nurses (DNs) regarding this defect in South East Asia. AIMS: To assess and compare the knowledge of the GDPs and DNs in Malaysia regarding the frequency of occurrence of MIH within their practice, its diagnosis, putative aetiological factors and management. STUDY DESIGN AND METHODS: A questionnaire was distributed to GDPs and DNs during a nationwide dental conference in Melaka, Malaysia and who were asked to answer questions about demographic variables, knowledge, attitudes and practices in the management of MIH. STATISTICS: Descriptive statistics and bivariate analysis were performed. A 5% level of statistical significance was applied for the analyses. RESULTS: A response rate of 58.2% (131/225) was obtained. Most respondents were aware of MIH and encountered it in their practice (GDPs = 82.5%, DNs = 82.4%). The condition was observed by respondents less in primary molars compared to first permanent molars. Full agreement between GDPs and DNs did not exist concerning the aetiological factors and management of MIH. Glass ionomer cements were the most popular material used in treating MIH. Most respondents (GDPs = 93%, DNs = 76.5%) indicated that they had not received sufficient information about MIH and were willing to have clinical training in the diagnosis and therapeutic modalities of MIH. CONCLUSIONS: MIH is identified and encountered by most respondents. Agreement did not exist between GDPs and DNs concerning MIH frequency of occurrence within their practice, its diagnosis, aetiological factors and management.

Salivary trace elements in relation to dental caries in a group of multi-ethnic schoolchildren in Shah Alam, Malaysia.

AIM: To assess the salivary levels of Copper (Cu), Zinc (Zn), Manganese (Mn) and Iron (Fe) obtained from children of different ethnic backgrounds in Shah Alam, Malaysia and investigate the possible relationships with caries. MATERIALS AND METHODS: One hundred and twenty primary school children were included. They were divided into caries and caries-free groups. Unstimulated whole saliva was collected from each participant using spitting method. The salivary elements were measured using an Atomic Absorption Spectrophotometer. Descriptive statistics, bivariate and Pearson's correlation analysis were performed. RESULTS: Salivary Cu and Zn levels were significantly higher in children with dental caries compared to those caries-free (p < 0.05). Moreover, these elements had a positive correlation with dental caries (Cu: r=0.698, p<0.001; Zn: r=0.181, p<0.05). No significant variations in Mn and Fe were observed between caries and caries-free group (p>0.05). Additionally, there were significant differences in salivary Zn and Fe among different age groups (p<0.05) and highly significant differences in salivary Cu, Mn and Fe among different ethnic groups (p<0.001). However, all elements exhibited no significant differences between males and females. CONCLUSION: The salivary Cu and Zn levels showed significant differences between caries and caries-free groups. The findings also revealed significant variations in the levels of salivary Cu, Mn and Fe among different ethnic groups and salivary Zn and Fe among different age groups.

Assessing the competency of University of Malaya dental graduates: employers' and graduates' perceptions.

A survey was conducted to assess competencies of dental graduates of the Faculty of Dentistry, University of Malaya, as perceived by the graduates and their employers, based on the five-year undergraduate curriculum introduced in 1995. All senior dental officers in the Ministry of Health (MOH), representing employers, and all 164 dental graduates of the years 2000, 2001, and 2002 were sent a self-administered questionnaire covering eight areas of competency. The respondents had to rate these areas on a scale of 1 (very poor) to 4 (very good). The responses for each area were then dichotomized into poor (1 and 2) and good (3 and 4). If less than 60 percent of the respondents rated an area as good, then it was categorized as needing attention; 60-69 percent as satisfactory; and 70 percent and above as excellent. One hundred and six graduates (64.6 percent) and twenty-nine employers (96.7 percent) responded; of the graduates, 73.6 percent were working in the MOH and 22.6 percent in private practice. About 57.1 percent of employers reported that at least five graduates have worked under them. Graduates (85.7 percent) and employers (83.3 percent) agreed that graduates have excellent skills in communication. Although all graduates perceived their competency to be excellent in the four areas (treatment planning; community-based skills; management, administrative skills, and personal management; and professional development skills), employers felt that these are the areas that are of concern and needed attention. In conclusion, whilst generally the graduates' level of competency in almost all areas is acceptable or good, there are areas of concern that need to be addressed to further improve the five-year curriculum at the University of Malaya.

Evaluation of load at fracture of Procera AllCeram copings using different luting cements.

PURPOSE: The current study investigated the effect of different luting agents on the fracture resistance of Procera AllCeram copings. METHODS: Six master dies were duplicated from the prepared maxillary first premolar tooth using nonprecious metal alloy (Wiron 99). Thirty copings (Procera AllCeram) of 0.6-mm thickness were manufactured. Three types of luting media were used: zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and dual-cured composite resin cement (Panavia F). Ten copings were cemented with each type. Two master dies were used for each group, and each of them was used to lute five copings. All groups were cemented according to manufacturer's instructions and received a static load of 5 kg during cementation. After 24 hours of distilled water storage at 37 degrees C, the copings were vertically compressed using a universal testing machine at a crosshead speed of 1 mm/min. RESULTS: ANOVA revealed significant differences in the load at fracture among the three groups (p < 0.001). The fracture strength results showed that the mean fracture strength of zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and resin luting cement (Panavia F) were 1091.9 N, 784.8 N, and 1953.5 N, respectively. CONCLUSION: Different luting agents have an influence on the fracture resistance of Procera AllCeram copings.

Some flexural properties of a nylon denture base polymer.

Nylon denture base material could be a useful alternative to poly (methyl methacrylate) (PMMA) in special circumstances such as patient allergy to the monomer. The aim of this study was to evaluate the flexural properties of a nylon denture base material (Lucitone FRS), a conventional compression-moulded heat-polymerized (Meliodent), a compression-moulded microwave-polymerized (Acron MC) and an injection-moulded microwave-polymerized (Lucitone 199) PMMA polymers. The effect of aldehyde-free, oxygen releasing disinfectant solution (Perform) on these properties was also investigated. The flexural modulus and the flexural strength were assessed with a three-point bending test. Specimens were stored in water at a temperature of 37 degrees C for 30 days. For each material, half of the prepared specimens were randomly selected and immersed in the disinfectant 24 h prior to testing. Results were compared statistically at a confidence level of 95%. The result showed that in both the control and disinfected groups, the flexural modulus of nylon was significantly lower than the three PMMA polymers. The flexural strength of nylon was significantly lower than those of Meliodent and Acron MC but was comparable with Lucitone 199. A 24-h immersion in the disinfecting solution increased the rigidity of nylon denture base material.

Stress distribution associated with loaded ceramic onlay restorations with different designs of marginal preparation. An FEA study.

The design of marginal finish of an inlay or onlay could influence the prognosis of the restoration since this area is subjected to various mechanical or chemical actions during function. This study was carried out to determine the tensile stresses which develop at the marginal area when subjected to vertical and horizontal loads. Onlay restorations with three different types of marginal finish, i. e. shoulder, chamfer and bevel, were modelled in three dimensions using the finite element method, and were then subjected to vertical and horizontal load at three different sites. The results show that horizontal forces acting on the restoration generate the highest tensile stresses whilst the vertical forces generate high tensile stresses at the margins of the chamfer and bevel designs.

Strains and tensile stress distribution in loaded disc-shaped ceramic specimens. An FEA study.

Disc-shaped specimens are frequently tested in order to establish an understanding of the properties of ceramic material. In this study three-dimensional finite element stress analysis has been used to investigate the loading characteristics of this shape of specimen and the effect of incorporating scratches and voids into its structure. The results indicated that stress increased as loading was carried out nearer to the centre of the specimen. The presence of cracks did not affect these stresses whereas the presence of a void resulted in a very high stress concentration.

Incidence of pain after biomechanical preparation: a review of 302 cases treated by dental students.

Records of 302 root-filled teeth treated by dental undergraduates were reviewed by four lecturers in the Department of Conservative Dentistry, University of Malaya. Preoperative and operative factors were evaluated for their association with postoperative pain experience of patients during the visit immediately after completion of biomechanical preparation. Eighty four percent of patients did not experience any pain after biomechanical preparation whilst the remaining 16 percent only complained of slight or moderate pain. The incidence of pain after biomechanical preparation is not high even when performed by inexperienced undergraduates. Teeth with a pre-existing painful condition had a higher chances of postoperative of pain. The incidence of postoperative pain was halved when teeth were associated with a sinus tract.

Porosity determination of cast investment by a wax-infiltration technique.

A reproducible method of determining the porosity (pore volume) of cast investment materials is described. This procedure, requiring no highly specialized equipment, involved the infiltration of a test sample with paraffin wax and the weighing of the wax-infiltrated sample in both air and water. Pore-volume wax is then extracted with chloroform and the sample reweighed. The difference in weight is used to calculate the porosity of the investment material. Pore-volume data thus obtained are comparable to those resulting from standard techniques and far more sophisticated (and expensive) instrumentation. The porosities of hand-mixed samples of gypsum-bonded, phosphate-bonded and silica-bonded investments were 53.9 per cent, 36.9 per cent and 31.4 per cent and those of the vacuum-mixed samples were 52.5 per cent, 31.3 per cent and 26.9 per cent, respectively. The results show that gypsum-bonded investments were more porous than phosphate-bonded investments while silica-bonded investments were the least porous. Hand-mixed samples appeared to have greater porosity than vacuum-mixed samples.