Biomedical subjects

E C M Lo

Publications and source records attributed to E C M Lo.

14 recordsLinked to original sources

PubMed2006

Association between developmental defects of enamel and different concentrations of fluoride in the public water supply.

OBJECTIVES: To compare the prevalence and severity of developmental defects of enamel (DDE) among subjects whose maxillary incisors developed during periods with different concentrations of fluoride in the public water supply. METHODS: Standardized intra-oral photographs of random samples of 12-year-old children were collected in 1983, 1991 and 2001 (n = 1,990) in Hong Kong and assessed for DDE by a trained masked examiner. The fluoride concentrations in the public water supply at the times when the enamel on their maxillary incisors developed were 1.0, 0.7 and 0.5 ppm, respectively. RESULTS: The mouth prevalence of DDE for these children (based on the maxillary incisors) were 92.1, 55.8 and 35.2% in the years 1983, 1991 and 2001, respectively (p < 0.001). Most of these children were affected by diffuse opacities (89.3% in 1983, 48.5% in 1991 and 32.4% in 2001, p < 0.001). Marked differences in the mean number of teeth affected by DDE (p < 0.001) and in the maximum extent of DDE (p <or= 0.002) between 1983, 1991 and 2001 were also observed. CONCLUSIONS: A decrease in the prevalence and severity of DDE among the maxillary incisor teeth of the children corresponded to the reductions in the concentration of fluoride in the water during the time of enamel development.

Cariostatic Agents↗

PubMed2006

A two-year randomized clinical trial of chlorhexidine varnish on dental caries in Chinese preschool children.

The objective of this study was to assess the effect of six-monthly professional applications of chlorhexidine varnish on the prevention of dental caries in primary molars in Chinese preschool children. In a double-blinded, randomized, placebo-controlled clinical trial, 334 children aged 4-5 years were randomly divided into two groups. Children in the test group received six-monthly applications of a 40% chlorhexidine varnish, and the control children received a placebo varnish. Caries status of the children was assessed by two calibrated examiners at baseline and after 24 months, according to criteria recommended by the World Health Organization. The two-year mean caries increments in the test and the control group children were 1.0 and 1.6 decayed, missing, or filled molar surfaces (dmfs-molar), respectively, a 37.3% reduction (t test, p = 0.036). No side-effects were found. It was concluded that six-monthly applications of chlorhexidine varnish were effective in reducing the incidence of dental caries in primary molars.

Administration, Topical↗

PubMed2006

ART and conventional root restorations in elders after 12 months.

Successful use of atraumatic restorative treatment (ART) in children has been reported, but little information is available regarding its use in older adults. The hypothesis of this study was that survival rates of root restorations placed by both ART and the conventional technique were similar. Root-surface caries lesions in 103 institutionalized elders in Hong Kong were treated randomly by either: (1) the conventional approach-caries removed by dental burs, and the cavity filled with light-cured resin-modified glass ionomer; or (2) the ART approach-caries removed by hand instruments, and the cavity filled with chemically cured high-strength glass ionomer. In total, 84 conventional and 78 ART restorations were placed. After 12 months, 63 conventional and 59 ART restorations were reviewed, and the respective 12-month survival rates were 91.7% and 87.0% (p > 0.05). It is concluded that the survival rates of both types of root restorations were high and similar.

Age Factors↗

PubMed2005

The sensitivity and responsiveness of an oral health related quality of life measure to tooth whitening.

OBJECTIVES: To assess the sensitivity and responsiveness of an oral health related quality of life measure to tooth whitening. METHODS: Following screening at a clinic, 87 subjects were given an array of tooth whitening products to use at home and reviewed 8 weeks later. Subjects self-completed the 49-item Oral Health Impact Profile (OHIP) at baseline and follow-up, and rated their satisfaction with the whiteness of their teeth compared to baseline on a global transition scale. RESULTS: In terms of sensitivity, observed changes were apparent in overall OHIP scores (P<0.05) and across several domains, notably functional limitation (P<0.01). However, the magnitude of change (effect size) was generally small except for the functional domain. There was an observed gradient in observed change in OHIP scores and in the magnitude of such changes (effect sizes) in relation to global rating of satisfaction with the outcome, supporting the responsiveness of the measure. CONCLUSION: The OHIP scale is sensitive and responsive to the effects of tooth whitening. Greatest sensitivity and responsiveness was in relation to functional limitations. These findings have implications for the use of oral health related quality of life measures as an outcome measure of interventions aimed at improving dental aesthetics through tooth whitening.

Adolescent↗

PubMed2005

Outcome of root canal treatment using Thermafil and cold lateral condensation filling techniques.

AIM: To evaluate the outcome of root canal treatment (RCT) using either Thermafil (TF) or lateral condensation (LC) as filling technique, and to compare the time required for the treatment when either filling technique was used. METHODOLOGY: This study involved all patients attending the dental clinic of a university in Hong Kong who required primary, nonsurgical RCT. It was a prospective clinical trial involving 85 teeth in 79 patients aged 15-69 years (mean 48 +/- 12 years), which required root treatment and finally filling with either TF or LC by one of four dentists following a standard treatment protocol. The time used for the entire course of treatment was recorded. The treated teeth were examined both clinically and radiographically 3 years after the treatment by a single examiner who did not know their group assignment. RESULTS: A total of 85 teeth from 79 patients were included in this study and 71 teeth from 64 patients were examined after 3 years. Thirty-four teeth were root filled with LC and 37 with TF. The overall attrition rate was 16% (14/85). There were 22 incisors and canines, 21 premolars and 28 molars for evaluation. Post-treatment disease with clinical symptoms and/or radiographic radiolucency was observed in seven teeth (21%) of the LC group and in seven teeth (19%) in the TF group. There was no statistically significant difference (P > 0.05) for the presence of disease between the two groups. It was found that irrespective of the filling method used, teeth later restored with extracoronal restorations had a lower association with disease than those receiving intracoronal restorations (7% vs. 30%; P = 0.037). RCT took, on average, 20 min less when TF was used for filling compared with LC (98 min vs. 78 min, P = 0.003). CONCLUSIONS: Using TF or LC in the filling of root canals did not result in significant difference in the clinical treatment outcome. TF consumed significantly less time than LC. The type of postendodontic restoration had a significant association with the presence of post-treatment disease.

Adolescent↗

PubMed2005

Bayesian analysis of clustered interval-censored data.

The recording of multiple interval-censored failure times is common in dental research. Modeling multilevel data has been a difficult task. This paper aims to use the Bayesian approach to analyze a set of multilevel clustered interval-censored data from a clinical study to investigate the effectiveness of silver diamine fluoride and sodium fluoride varnish in arresting active dentin caries in Chinese pre-school children. The time to arrest dentin caries on a surface was measured. A three-level random-effects Weibull regression model was used. Analysis was performed with WinBUGS. Results revealed a strong positive correlation (0.596) among the caries lesions' arrest times on different surfaces from the same child. The software WinBUGS made the above complicated estimation simple. In conclusion, the annual application of silver diamine fluoride on caries lesions, and caries removal before the application, were found to shorten the arrest time.

Bayes Theorem↗

PubMed2003

Changes in life quality following third molar surgery--the immediate postoperative period.

OBJECTIVES: This study describes patients' perceptions of changes in oral health related quality of life (OHQOL) in the early postoperative period following third molar surgery. METHODS: One hundred patients were enrolled in a prospective cohort study of the surgical removal of lower third molars under local anaesthetic. Two specific oral health related quality of life measures, OHIP-14 and OHQoLUK, were administered to the study group prior to surgery. Standardized surgical and analgesic protocols were followed. Patients kept a diary of changes in life quality each postoperative day (POD) for 7 days, completing both OHIP-14 and OHQoLUK daily. RESULTS: Both oral health related quality of life measures identified a significant deterioration in quality of life on POD1 (P<0.01) and this remained evident on POD2 (P<0.01), POD3 (P<0.01), POD4 (P<0.01) and POD5 (P<0.05). By POD6 and POD7 there was no significant difference in quality of life compared with preoperative status (P>0.05). Deterioration in life quality over the study period was associated with postoperative clinical findings (P<0.05): swelling and trismus. CONCLUSION: The study concludes that there is a significant deterioration in oral health related quality of life in the immediate postoperative period following third molar surgery; particularly during the first five days. This is associated with postoperative clinical findings. This has implication for patients deciding on third molar surgery and informed consent.

Attitude to Health↗

PubMed2003

Oral colonisation by aerobic and facultatively anaerobic Gram-negative rods and yeast in Tibetans living in Lhasa.

Sample groups of children (n=50) and adults (n=38) were selected from pools of 207 children, (11-13-year olds from two primary schools) and 94 adults (25-44-year olds from four governmental agencies) who were the subjects of an oral health survey among Tibetans living in Lhasa, Tibet Autonomous Region. Mean ages of the study groups of children (38% females) and adults (61% females) were 11.6+/-0.9 and 37.1+/-6.1 years, respectively. All had lived in Tibet since birth. Oral rinse samples were selective cultured to isolate, quantify and speciate aerobic and facultatively anaerobic Gram-negative rods (using the API 20E kit) and yeasts (using API 20C AUX and API ZYM kits). For children, the isolation rates for oral coliform bacteria and yeasts were 84 and 14%, respectively, for adults, the respective rates were 26 and 40%. The corresponding quantities of coliforms/yeasts for children and adults were 0.4+/-1.6 x 10(3)c.f.u./15.8+/-72.3 and 0.2+/-0.6 x 10(3)c.f.u./57.2+/-137.5c.f.u. per millilitre oral rinse, respectively. Aerobic and facultatively anaerobic Gram-negative rods and Stenotrophomonas maltophilia, a free-living saprophytic and ubiquitous bacterial species of wide geographic distribution, were significantly more frequently recovered from the children's oral rinses. The isolation rates of facultatively anaerobic Gram-negative rods in adults and yeasts in both groups were similar to those found in similar cohorts from southern China in earlier studies. Randomly amplified polymeric DNA analysis showed that the S. maltophilia spp. isolated from children were of several different clonal types and were school specific. This study shows that the colonisation rate of facultatively anaerobic Gram-negative rods in adults and yeasts in both groups are similar to those in populations living at lower altitudes, the native young, urban Tibetans appear to exhibit a high oral carriage rate of S. maltophilia spp.

Adolescent↗

PubMed2003

The impact of oral disease among the institutionalized and non-institutionalized elderly in Hong Kong.

The study aimed to describe and compare the psychosocial and functional impact of oral disease on the quality of life of the institutionalized and non-institutionalized elderly in Hong Kong. A total of 268 institutionalized and 318 non-institutionalized elderly aged 60-80 years took part. The 49-statement Oral Health Impact Profile (OHIP) was administered in a structured interview format and sociodemographic information collected prior to a clinical, oral examination. A greater number of the institutionalized were edentulous (19%); they also had more untreated dental disease. The number of elderly reporting negative impacts was generally low. The percentage of institutionalized elderly reporting a negative impact was significantly lower in one of the OHIP subscales (handicap, P < 0.001) and similar in the other six. The main factors affecting the OHIP score were living location, socio-economic status, dental disease and treatment seeking behaviour. In conclusion, the psychosocial and functional impact of oral conditions was low and similar in the institutionalized and non-institutionalized elderly although the pattern of oral disease was different. Life events and socially and culturally derived values appeared to affect the elderly perception of the impact of oral disease.

Aged↗

PubMed2002

Comparison of pulse activation vs conventional light-curing on marginal adaptation of a compomer conditioned using a total-etch or a self-etch technique.

OBJECTIVES: This study investigated the effect of two factors: conditioning methods and light-curing techniques on the marginal adaptation of Dyract AP (Dentsply DeTrey, Germany). The 'pulse activation' curing technique was compared with a conventional light-curing technique for their effectiveness in reducing marginal gaps in restorations that were conditioned with three different protocols. MATERIALS AND METHODS: Cylindrical cavities, 3mm in diameter, were prepared in extracted human molar teeth. They were restored with Dyract AP using Prime&Bond NT (PBNT; Dentsply DeTrey) as the adhesive. Cavities were etched with: Conditioner36/PBNT (group 1), Non-Rinse Conditioner (NRC)/PBNT (group 2), and PBNT only (group 3). Either conventional or the 'pulse activation' technique was used for light-curing of the material. Epoxy resin replicas were obtained from longitudinal sections of the specimens, and the restoration-tooth interfaces were examined using scanning electron microscopy. Marginal qualities along the resin-dentin interfaces were further measured using image analysis and analyzed using nonparametric statistical methods. RESULTS: With the conventional curing technique, enamel margin fractures were frequently observed. Marginal gaps were found along the compomer-dentin interfaces irrespective of the conditioning protocol. A significantly lower percentage of gap-containing margins were found in cavities that were conditioned with 36% phosphoric acid. With the 'pulse activation' technique, no marginal gap was found along compomer-dentin interfaces that were etched with either Conditioner36 or NRC. More than 90% of the total margin length were excellent. No cohesive failure of enamel could be observed along cavosurface margins. SIGNIFICANCE: The 'pulse activation' curing technique significantly improves the marginal integrity of Dyract AP when Conditioner36/Prime&Bond NT and NRC/Prime&Bond NT are used as conditioning/bonding systems. The use of Prime&Bond NT without etching is not recommended, as marginal gaps are present irrespective of the curing techniques employed.

Acid Etching, Dental↗

PubMed2002

Usage and status of cobalt-chromium removable partial dentures 5-6 years after placement.

The aim of this study was to describe the usage of cobalt-chromium (Co-Cr) removable partial dentures (RPDs) by patients 5-6 years after denture insertion and to find out the factors that affected their denture usage. A random sample of patients provided with Co-Cr RPDs from a dental teaching hospital in Hong Kong was selected. Patients were interviewed using a structured questionnaire concerning their assessment and use of the dentures. Those who had been constantly wearing their original RPDs were examined by one calibrated examiner under optimal clinical conditions. The response rate of the patients who could be contacted was 98%. The results from 189 patient interviews showed that usage of the RPDs declined with time and that half of the dentures had been discarded or replaced 5-6 years after insertion. These discarded RPDs had been in use for an average of 19.5 months. The main reason given by the patients for not using the RPDs was general dissatisfaction with the dentures in various combinations of comfort, fit and chewing ability and, less importantly, with food trapping and appearance. No statistically significant association between denture usage and their respective Kennedy classification was found. The status of the Co-Cr RPDs that had been constantly used for 5-6 years was generally good. The majority of these RPDs demonstrated fair to good cleanliness, stability and retention and had no defect of any sort.

Adult↗

PubMed2002

Effectiveness of silver diamine fluoride and sodium fluoride varnish in arresting dentin caries in Chinese pre-school children.

Untreated dental caries in Chinese pre-school children is common. This prospective controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries. Three hundred seventy-five children, aged 3-5 years, with carious upper anterior teeth were divided into five groups. Children in the first and second groups received annual applications of silver diamine fluoride solution (44,800 ppm F). Sodium fluoride varnish (22,600 ppm F) was applied every three months to the lesions of children in the third and fourth groups. For children in the first and third groups, soft carious tissues were removed prior to fluoride application. The fifth group was the control. Three hundred eight children were followed for 30 months. The respective mean numbers of arrested carious tooth surfaces in the five groups were 2.5, 2.8, 1.5, 1.5, and 1.3 (p < 0.001). Silver diamine fluoride was found to be effective in arresting dentin caries in primary anterior teeth in pre-school children.

Analysis of Variance↗

PubMed2002

[The cost-effectiveness of ART and resin sealant on caries prevention].

OBJECTIVE: Pit and fissure sealants have been widely used to caries prevention. More often, ART is used in caries treatment. ART was used to prevent caries in recent years. However,the cost-effectiveness of ART that is used to caries prevention still remains unclear. The aim of the present research was to compare the cost-effectiveness of ART with that of resin sealant in caries prevention for primary school children. METHODS: Two hundred and twelve children aged 7 to 9 years old took part in this research. The molar of every child on one side of the mouth was sealed by light-cure resin sealant(Concise,3M) and by chemically firmed glass ionomer (Ketac-molar, ESPE) on the opposite side. The routine methods were used to seal teeth and the cotton rolls and suction were used to keep dry. The time for manipulation,amount of materials and times for repetition in the program were recorded. The retained rate of sealed material on the teeth was checked month after treatment. RESULTS: The results indicated the time for manipulation,cotton rolls and times for repetition in sealant was respectively 3.54 (min.), 2.52 and 0.04 (times) in sealant and 3.18 (min.),1.13 and 0.03 (times) in ART. The material of ART was more expensive than of resin sealant. Respectively,the costs of glass ionomer and resin sealant were 3.77 and 0.93(Yuan). However, the cost of equipment used in sealant were much more expensive than that used in ART. Furthermore, there was no significantly difference between sealant and ART in the remaining rate. CONCLUSION: The results suggest that ART is more cost-effective than sealant on caries prevention.

English Abstract↗

PubMedDate not supplied

Actinomyces spp. in supragingival plaque of ethnic Chinese preschool children with and without active dental caries.

Very limited molecular epidemiological data are available on the role of Actinomyces spp. in the pathogenesis of caries in the primary dentition. Therefore, we investigated their distribution in supragingival plaque of ethnic Chinese preschool children from Singapore and Hong Kong, either with or without active caries. Plaque samples were taken from intact interproximal enamel areas using dental floss. Bacterial genomic DNA of each sample was extracted and variable regions of 16S ribosomal DNA amplified and labelled with digoxigenin. Oligonucleotide probes specific for Actinomyces bovis, Actinomyces gerencseriae, Actinomyces israelii, Actinomyces meyeri, Actinomyces odontolyticus, catalase-negative Actinomyces naeslundii (genospecies 1 and 2) and catalase-positive Actinomyces naeslundii genospecies 2 (previously Actinomyces viscosus serotype II) were used to detect these species using Southern hybridization with a Minislot and Miniblotter system. A. odontolyticus, A. gerencseriae and A. meyeri were detected with similar frequency in both Singapore and Hong Kong samples or in those with and without active caries. However, the prevalence of A. naeslundii was significantly different in the two locales (p<0.05). A. odontolyticus (88.7%), A. gerencseriae (56.6%) and A. naeslundii (50.9%) were detected in a majority of the samples and the positive hybridization signals of A. gerencseriae in the caries-active group were stronger than from the caries-free group. A. bovis and A. israelii were undetectable in any of the samples. These data imply that A. odontolyticus, A. naeslundii and A. gerencseriae may play an important role in supragingival plaque formation on primary teeth in ethnic Chinese, with others such as A. meyeri contributing.

Actinomyces↗