A randomized double blinded study to assess the efficacy of a laser-guided collimator on dental radiography training.

OBJECTIVES: To assess the effect of a laser-guided collimator in intraoral radiography training. METHODS: A custom-made collimator with four red laser diodes on each corner on the rim of an aluminium alloy cubic housing was fabricated. The laser used low power diodes, which are classified as laser-safe by the United States Food and Drug Administration (FDA). When activated, the effective dimensions of the laser beams were 4 cm x 4.5 cm. Eighteen dental hygiene students were randomized into test and control groups. The Laser group used a rectangular collimator with the laser device, while the Non-laser group used a conventional rectangular collimator. Each group attended nine intraoral radiography training sessions. All radiographs were assessed and were classified into three categories: Excellent, Acceptable and Repeat, by a masked academic staff member. Reasons for repeats were marked. Statistical comparisons between the two groups were made. RESULTS: A total of 2334 radiographs were made. Conecut was more common on bitewings than periapicals. The Laser group produced fewer conecuts than the Non-laser group. The Laser group produced more excellent radiographs with fewer repeats than the Non-laser group, but there was not a significant difference. CONCLUSIONS: The laser-guided collimator helped the students to produce fewer repeats in a shorter period of time. It was an effective training aid.

Prevalence of impacted teeth and associated pathologies--a radiographic study of the Hong Kong Chinese population.

OBJECTIVES: To investigate the prevalence and pattern of impacted teeth and associated pathologies in the Hong Kong Chinese population. SETTING: The Reception and Primary Care Clinic, Prince Philip Dental Hospital, Hong Kong. DESIGN: Retrospective study. SUBJECTS AND METHODS: The records of 7486 patients were examined to determine whether the chief complaints were related to impacted teeth and associated pathologies, which were investigated using panoramic radiographs. RESULTS: A total of 2115 (28.3%) patients presented with at least one impacted tooth. Among the 3853 impacted teeth, mandibular third molars were the most common (82.5%), followed by maxillary third molars (15.6%), and maxillary canines (0.8%). Approximately 8% of mandibular second molars associated with impacted third molars had periodontal bone loss of more than 5 mm on their distal surfaces. Caries were also found on the same surfaces in approximately 7% of the second molars. Approximately 30% of patients with dental impaction had symptoms, and 75% had complaints limited to one side of the mouth. CONCLUSIONS: The prevalence of impacted teeth was high, and there was a predilection for impacted third molars in the mandible. More than 50% of maxillary third molars had erupted, creating potential trauma of the pericoronal tissues of the partially erupted mandibular third molars. Caries and periodontal diseases were commonly seen in relation to the impacted third molars, whereas cystic pathology and root resorption were rarely observed.

Phenotypic diversity of oral C. albicans isolated on single and sequential visits in an HIV-infected Chinese cohort.

HIV-infected individuals maintain multiple oral C. albicans strains over time that are thought to undergo microevolution in terms of both phenotypic and genotypic features. To study this phenomenon, a 12-month prospective study was conducted in a cohort of 16 HIV-infected ethnic Chinese individuals with (A) and without (B) symptoms of oropharyngeal candidiasis to evaluate the phenotype distribution among oral C. albicans isolates during disease progression. Oral rinse samples were obtained and up to five C. albicans colony-forming units were selected per each visit, during the one year period of multiple visits. The isolates were phenotyped using two commercially available biotyping kits, the API 20C system, API ZYM system, and a plate test for resistance to boric acid. A total of 261 C. albicans strains in group A were differentiated into 67 biotypes, while 42 biotypes were seen amongst the 182 isolates from group B. The major biotypes in the two groups were similar and were in decreasing order of prevalence J1R, J1S, J6S, J6R, J2S, K1S, J10R, K1R, and K6R; 48 different biotypes were seen in group A and 24 in group B, with some uniquely represented in each group, leading to a significant association between the prevalence of the biotypes J1S and J2S and symptomatic candidiasis (p<0.05). Taken together this study illustrates the wide phenotypic spectrum of oral C. albicans associated with HIV-infection.

Odontogenic myxomas in the Hong Kong Chinese: clinico-radiological presentation and systematic review.

AIM: The aim of this study was to determine the clinical and radiological presentation on plain films of central odontogenic myxomas (OM) in the Hong Kong Chinese and compare them to other reported series by a systematic review (SR). METHODS: The study had two elements, that of a complete series of all OMs presenting at a major Chinese maxillofacial surgical unit and a SR. The files of the Department of Oral and Maxillofacial Surgery of the University of Hong Kong between 1989 and 2000 were reviewed for OM cases. The relevant literature was identified by electronic databases, review of citation lists and handsearching of key journals. The principal selection criterion was that the study should represent a complete collection of cases. RESULTS: The SR revealed that only a quarter of the reports provided any quantitative radiological details. Just under half of the included reports provided the relative period prevalence of OMs compared to other odontogenic tumours, but these reports almost completely excluded consideration not only of the radiology but also specific clinical details. Furthermore, they did not report of recurrence data, an important feature of the OM. Most of the most recent reports were concerned with relative period prevalence. The relative period prevalence and 'number of OMs per hospital per year' of studies separated by two or more decades in Hong Kong and Nigeria indicate an increase in the number of lesions diagnosed as OMs. The 10 Hong Kong cases were broadly consistent with the predilections for females and the mandible of other reports. The mean age at first presentation in the present report is 36.9, older than the other reports. Most lesions are large, affecting both posterior and anterior quadrants. They appear to be larger than those in many other reports. Two of the OMs are accompanied by histories of recent rapid growth. Tooth displacement and root resorption are more frequently observed in OMs in the present study. Although all OMs in the present study are still being followed up after surgery, none have recurred. CONCLUSION: Although the presentation of larger lesions in the older Chinese could in part be explained by attitudes rooted in traditional medicine in spite of the widespread availability of modern medical care in Hong Kong, there is a history of recent rapid growth in at least two cases. An emphasis by recent reports on the OMs' relative period prevalence of concurrent odontogenic lesions, has omitted recording the radiology and the specific clinical details usually required for diagnosis.,