Chinese Journal of Dental Research, 04/2019

Objective: To evaluate whether the combination of the pan-histone deacetylase (HDAC) inhibitor, suberanilohydroxamic acid (SAHA), and the cyclooxygenase-2 (COX-2) inhibitor, celecoxib, could produce synergistic anticancer effects in human salivary adenoid cystic cancer (SACC) cells. Methods: SACC cells were treated with the COX-2 inhibitor celecoxib or the pan-HDAC inhibitor SAHA, or a combination of celecoxib and SAHA, for 24 hours. Cell proliferation, apoptosis, migration and invasion were evaluated using the cell counting kit 8 (CCK-8) assay, and the 4',6-diamidino-2-phenylindole staining assay, transwell migration or invasion assays, respectively. The protein expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and protein kinase B or AKT1(PKB/AKT) were evaluated using western blot. Results: The combinational treatment with SAHA and celecoxib synergistically inhibited cell proliferation, migration and invasion, and synergistically induced apoptosis, whereas the treatment with SAHA or celecoxib alone only slightly inhibited cell proliferation, migration and invasion, and slightly induced apoptosis. Meanwhile, the combinational treatment synergistically upregulated the membrane-bound PTEN (activated form) and downregulated phospho-AKT (activated form). Conclusion: The combination of pan-HDAC and COX-2 inhibitors produced synergistic anticancer effects at least partially via activating PTEN and inactivating AKT in the SACC cells. Keywords: HDAC, COX-2, celecoxib, SACC, SAHA

Objective: To evaluate whether the periodontal status was affected in patients with stage IV/grade C periodontitis after orthodontic treatment. Methods: Twenty-four patients with stage IV/grade C periodontitis who received combined periodontal and orthodontic treatment were included in this study. Probing depth (PD), bleeding on probing (BOP) and percentage of relative bone height (RBH%) were measured and calculated. Parameter changes before and after orthodontic treatment, and their differences between teeth adjacent to extraction sites (TAES) and teeth nonadjacent to extraction sites (TNES) were compared. Three-level analysis was performed to test the influential factors of PD and RBH% reduction after orthodontic treatment. Results: No change of PD, BOP% and RBH% was detected after orthodontic treatment. No difference of PD, BOP% and RBH% was detected between TAES and TNES. BOP negative, excessive horizontal overlap, excessive vertical overlap, crowding, PD at T0 (the last periodontal visit before orthodontic treatment) and RBH% at T0 were positively associated with PD reduction after orthodontic treatment. Being female, excessive horizontal overlap, excessive vertical overlap, crowding, PD at T0 and RBH% at T0 were positively associated with a RBH% reduction. Space was negatively associated with a RBH% reduction. Conclusion: Periodontal stability can be obtained for patients with stage IV/grade C periodontitis after orthodontic treatment. Orthodontic treatment with extraction was safe for patients with severe periodontitis, however, attention should be given to TAES. Keywords: periodontitis, orthodontic treatment, stage IV/grade C periodontitis

Objective: To evaluate and quantify the prevalence and morphology of the mandibular incisive canal (MIC) comparatively among healthy, periodontitis and edentulous mandibles using cone-beam computed tomography (CBCT). Methods: CBCT images of 1,070 hemimandibles from 535 consecutive patients, including 448 with healthy dentition, 42 with severe periodontitis mandibles and 45 with edentulous mandibles, were retrospectively analysed. MICs were identified, and linear measurements were performed. Statistical analyses were conducted to investigate differences in the prevalence and morphology of MICs relative to gender, laterality, age group and dental status. Results: The MIC was observed in 92.8% of 1,070 hemimandibles. No significant differences of MIC prevalence were found between left and right sides, or between healthy and periodontitis mandibles. However, males had a higher prevalence of MIC than females, and patients with dentate mandibles had a higher prevalence of MIC than those with edentulous mandibles. For dentate mandibles, MICs started most commonly below the first premolar (51.9%) and ended around the canine (58.5%). The mean diameter of MIC was 2.5 ± 0.5 mm at origin, and 20.6% of MICs began with a diameter of ≥ 3 mm. The mean length of MIC was 13.4 ± 3.3 mm. The mean distances from the MIC to the labial cortex, lingual cortex, alveolar ridge and inferior border of mandible were 3.7 ± 0.9, 5.1 ± 1.6, 19.5 ± 3.8 and 8.9 ± 1.7 mm, respectively. Moreover, significant differences of measurements were found relative to gender, age group, and dental status. Conclusion: Due to the large variations in size and course of MICs, special caution should be exercised in any individual surgery affecting the anterior mandible. Keywords: mandibular incisive canal, dentate mandible, edentulous mandible, cone-beam computed tomography

Objective: To systematically review the prevalence of dental caries from 1980 to 2018 to provide evidence for caries prevention in mainland China. Methods: Four databases were selected with online search tools to offer maximum coverage of the published literature on the provincial or national level of caries prevalence: Medline, EMBASE, China National Knowledge Infrastructure (CNKI, in Chinese) and Wanfang databases (in Chinese). We supplemented the results with relevant publications from the government health sectors, textbooks and web-based databases. Studies published between 1 January 1980 and 26 March 2018 were included. The quality of literature was assessed, and a meta-analysis was conducted using Stata12.0. Results: A total of 82 studies were included in the final analysis. There were 1.49 million samples retrieved from 1980 to 2018, and the overall pooled prevalence of caries was 52.0% (95% CI: 49.4%-54.6%) in mainland China. The overall prevalence of caries increased from 36.4% (95% CI: 31.5%-41.5%) in the 1980s to 51.8% (95% CI: 34.9%-68.7%) in the 1990s, stabilised at 50.7% (95% CI: 43.8%-57.6%) in the 2000s and slightly increased to 53.1% (95% CI: 50.8%-55.5%) in the 2010s. The pooled caries prevalence was 64.8% (95% CI: 61.7%-67.8%), 47.3% (95% CI: 43.1%-51.5%), 42.4% (95% CI: 38.3%-46.5%), 66.7% (95% CI: 50.8%-82.6%) and 82.0% (95% CI: 72.5%-91.4%) for the ages/age groups 5, 12, 15, 35-44 and 65-74, respectively. The average dental caries pooled prevalence in urban areas was 51.4% (95% CI: 48.5%-54.2%), which was lower than 54.6% (95% CI: 47.9%-61.4%) in rural areas. Conclusion: The prevalence of dental caries in mainland China is generally high, and an increasing trend was observed over the past 38 years. The prevalence of dental caries in mainland China varied geographically, and its characteristics differed over time. Regional disparities between eastern/western China and rural/urban areas still exist. Comprehensive local prevalence data on caries are summarised here for the first time, which provide valuable evidence for the oral disease burden in China. Keywords: dental caries, prevalence, systematic review, China

Objective: To compare the peri-implant clinical and radiographic status around bone-level narrow-diameter titanium-zirconium (TiZr) implants and titanium (Ti) implants placed in cigarette-smokers (CS) and never-smokers (NS). Methods: Partially edentulous CS and NS rehabilitated with TiZr and Ti implants were included. Demographic data and information regarding smoking habits were collected. Participants were divided into four groups: group-1, CS with TiZr implants; group-2, NS with TiZr implants; group-3, CS with Ti implants; and group-4, NS with Ti implants. 36, 30, 31 and 33 implants were placed in 24, 23, 24 and 25 male individuals in groups 1, 2, 3 and 4, respectively. Peri-implant plaque index (PI), bleeding on probing (BOP), probing depth (PD) and mesial and distal crestal bone loss (CBL) were measured. All patients were enrolled in biannual routine oral prophylaxis care at least until the fifth year of follow-up and oral hygiene instructions were reinforced at each recall appointment. P 0.05 was considered statistically significant. Results: At the 3- and 5-year follow-ups, there was no statistically significant difference in the peri-implant PI, BOP, PD and CBL between individuals in all groups. In all groups, the implant success and survival rates were 100% and 100%, respectively, at the 5-year follow-up. Conclusion: The TiZr and Ti dental implants can remain clinically and radiographically stable in CS in a manner similar to NS. Routine oral hygiene maintenance plays an essential role in this regard. Keywords: dental implant, crestal bone loss, peri-implant inflammation, cigarette smoking

Objective: To investigate the effect of silver fluoride in preventing the development of artificial caries lesions in root dentine using an artificial mouth system (AMS). Methods: A total of 34 extracted intact human premolars were embedded individually in blocks with one root dentine surface exposed. Among these, 32 were randomly divided into four groups (eight each) and the remaining two tooth blocks were used in the baseline evaluation of the cariogenic biofilm after bacterial inoculation. The interventions (topical application of 2.36 M solutions) were applied after inoculation as follows: group-1, silver fluoride (AgF); group-2, potassium fluoride (KF); group-3, silver nitrate (AgNO3); and group-4, deionised water (control). Subsequently, the tooth blocks were transferred into the AMS to start an artificial caries challenge (5% sucrose was delivered three times per day). After 10 days, the formed biofilm was assessed via colony forming unit (CFU) counts, confocal laser scanning microscopy, and scanning electron microscopy. The artificial dentinal caries lesion was evaluated using micro-computed tomography. Results: After the interventions and the 10-day challenge in the AMS, the median CFUs (AgF AgNO3 KF = control, P 0.001) and the median live-to-dead bacteria ratios (AgF AgNO3 KF = control, P 0.005) of the biofilm differentiated significantly among the groups. Scattered bacterial cells were found in the tooth blocks of the AgF and AgNO3 groups, while a confluent biofilm layer was observed in the tooth blocks of the KF and control groups. The median lesion depth in the AgF group was significantly lower than in the AgNO3 (P = 0.016), KF (P = 0.016) and control (P = 0.009) groups. Conclusion: The combined use of silver and fluoride ions in the AgF solution significantly protected dentine against the development of caries lesions. Keywords: silver fluoride, dental biofilm, artificial mouth system, dentine caries lesion, prevention

Oligodontia is the agenesis of six or more permanent teeth, excluding the third molars. Multidisciplinary dental treatments should be performed sequentially due to the restoration requirements for good oral function, aesthetics and self-confidence of patients. In this study, we report a case using dental implants and full-ceramic prostheses to restore the absent and malformed teeth in a patient with agenesis of 18 permanent teeth and with some primary teeth retained. The dental sequential treatments began when she was 16 years old, and she wore removable partial dentures for 4 years with unsatisfying restoration outcome. When she became an adult, dental implants and full-ceramic prostheses were used to restore the absent and malformed teeth. Finally, the patient was very satisfied with the functional and aesthetic outcomes of the prosthetic treatment. Keywords: occlusal rehabilitation, oligodontia, dental implant, minimally invasive restoration, PAX9 mutations