METHODS: Case records of patients who underwent third molar extractions at the Prince Philip Dental Hospital in Hong Kong between 3 July 2012 and 22 June 2017 were evaluated retrospectively. Data extraction was performed for indications, clinical and radiographic findings, antibiotic treatment, postoperative complications, and treatment for postoperative infection. The odds ratio (OR) for postoperative infection was estimated.

RESULTS: In total, 1615 extracted over 5 years from 992 patient records were included in the final analysis. Antibiotics were prescribed postoperatively for 44% of the extractions. The overall infection rate was 2.05%. There was no significant difference in infection rates between the groups which underwent extractions with or without antibiotics (OR = .68; P = .289). We found a significantly higher risk for infections with increasing age (P = .002).

METHODS: Tooth wear status of NPC survivors were clinically assessed using the Exact Tooth Wear Index. A tooth was graded to have severe wear when more than one-third of its buccal/occlusal/lingual surface had dentine loss. At the subject-level, percentages of anterior/posterior/all teeth with severe wear were calculated. Age, number of teeth, flow-rate/buffering capacity/pH of stimulated whole (SWS) and parotid (SPS) saliva's were collected. Correlation and multiple-linear regression tests were performed at the significance level α = 0.05.

RESULT: Sixty-eight participants (mean age of 60.0 ± 8.9), 697 anterior and 686 posterior teeth were examined with a mean of 10-years post-radiotherapy. Severe tooth wear was found in 63 (92.6 percent) participants, 288 anterior and 83 posterior teeth. The mean percentage of anterior/posterior/all teeth with severe wear were 42.3 ± 28.1, 14.5 ± 19.9 and 30.0 ± 21.7. Anterior teeth, particularly the incisal surface of central incisors were most affected. The mean flow-rate of SWS and SPS were 0.1 ± 0.1 ml/min and 0.03 ± 0.07 ml/min respectively. Thirty (44.1 percent) and 48 (70.6 percent) participants were found to have low/no buffering capacity of SWS and SPS respectively. Multiple-regression analyses revealed the SWS flow-rate was associated with the percentage of anterior teeth with severe wear (p=0.03).

CONCLUSION: Anterior tooth wear is a significant dental problem among NPC survivors and was associated with hypo-salivation.

METHODS: Fifty-four dental students enrolled in 2018 were recruited as participants and assigned to two groups. Both groups were given the same lecture and asked to watch the same video in either the enhanced or non-enhanced version. The enhanced video was modified with the contemporaneous subtitle of the presenters' dialogue, text bullet points and summary text pages. The knowledge acquisition from the two types of video was subjected to pre- and post-tests one month after the students watched the video. A questionnaire was used to evaluate the students' perceptions of the learning experience and a performance test on practical skills was performed after six weeks. All the students responded to the test (100%).

METHODS: Oral swab samples were collected from smokers, smokeless tobacco users, and healthy controls (n = 44). Microbial DNA was extracted and the 16S rRNA gene profiled using the Illumina MiSeq platform. Sequencing reads were processed using DADA2, and taxonomical classification was performed using the phylogenetic placement method. Differentially abundant taxa were identified using DESeq2, while functional metagenomes based on KEGG orthology abundance were inferred using LIMMA.