Influence of rotating-oscillating, sonic and ultrasonic action of power toothbrushes on abrasion of sound and eroded dentine

OBJECTIVE: This in vitro study aimed to evaluate the susceptibility of sound and eroded dentine to brushing abrasion performed by different rotating-oscillating, sonic and ultrasonic toothbrushes. METHODS: Toothbrushing abrasion (20 cycles, each 30 s) was applied to bovine dentine samples (each subgroup n = 10) exhibiting both a demineralized (each cycle: 1% citric acid, pH: 2.3, 60 s; 30 min remineralization in artificial saliva) and a sound surface area. Toothbrushing was performed in an automatic brushing machine with the rotating-oscillating, sonic and ultrasonic toothbrushes either (a) activated, supplemented by 20 strokes/min of the brushing machine, (b) inactivated, supplemented by 20 strokes/min of the brushing machine or (c) inactivated, supplemented by 80 strokes/min of the brushing machine. A manual toothbrush was applied with 20, 80 or 100 linear strokes/min. Specimens of the control group were not brushed after erosion. After each cycle, the samples were stored in artificial saliva for 4 h. After 20 cycles, loss of sound and softened dentine was determined by profilometry. Mann-Whitney-Wilcoxon test and Bonferroni corrections were applied to the data (p < 0.05). RESULTS: For all groups, demineralized dentin areas exhibited significantly higher abrasion values than the respective sound dentine surfaces. However, mean dentine loss of both softened and sound dentine was higher after use of the rotating-oscillating, sonic and ultrasonic brushes with the activated regime [(a) eroded dentine: 9.94-16.45 microm; sound dentine: 3.31-5.47 microm] than after brushing with the inactivated regimes [(b) eroded dentine: 5.10-5.62 microm; sound dentine: 1.16-1.81 microm; (c) eroded dentin: 7.64-8.89 microm; sound dentine: 1.38-1.69 microm]. CONCLUSION: The results indicate that rotating-oscillating, sonic or ultrasonic action of the power toothbrushes leads to an increased loss of demineralized and sound dentine.     

Effect of antisense oligonucleotide against mouse dentine matrix protein 1 on mineralization ability and calcium ions metabolism in odontoblast-like cell line MDPC-23

AIM: To study the mineralization ability and the dynamic changes of intracellular and extracellular concentrations of calcium ions in the odontoblast-like cell line MDPC-23 affected by antisense oligonucleotide (AS-ODN) against mouse dentine matrix protein 1 (DMP1). METHODOLOGY: The expression of DMP1 in MDPC-23 cells was detected by an immunohistochemical method and its blocking outcome by the Western blot method. The alkaline phosphatase (ALP) activity, size and number of mineralized nodules, and the intracellular free ([Ca2+]if), total ([Ca2+]it) and the extracellular ([Ca2+]e) calcium ion concentrations in MDPC-23 cells in the experimental group affected with AS-ODN were compared with those in the control group (paired-samples t-test). RESULTS: Dentine matrix protein 1 was stably expressed in a stable way in MDPC-23 cells; the expression was only just detectable at 12 h and became negative after 24 h affected by AS-ODN. Compared with the control groups, ALP activity of MDPC-23 cells in the AS-ODN group was decreased (P < 0.05), and both the number and size of mineralized nodules were smaller than those in the control group. [Ca2+]if in the AS-ODN group increased and then decreased after 24 h. [Ca2+]it dropped substantially to the lowest point at 24 h (P < 0.01). [Ca2+]e increased before treatment for 24 h and then dropped, however, it was still higher than that of the control group. CONCLUSIONS: Antisense oligonucleotide against DMP1 could decrease mineralization ability and affect the intracellular and extracellular concentrations of calcium ions in MDPC-23 cells. This would indicate that DMP1 regulates the metabolism and transportation of calcium ions in odontoblasts, and thus boosts dentine mineralization.     

Effect of prolonged photo-irradiation time of three self-etch systems on the bonding to root canal dentine

OBJECTIVES: To evaluate the effect of photo-irradiation time to the adhesive on the regional bond strength of a dual-cure resin core material to root canal dentine using photo and dual-cure adhesives with self-etching primer. MATERIALS AND METHODS: Post spaces were prepared in extracted premolars and then the root canal dentine was treated with one of the following bonding procedures: (1) Clearfil SE Bond Primer/Bond (SE), (2) Nano-Bond Primer/Photo-cure adhesive (PNB), (3) Nano-Bond Primer/Dual-cure adhesive (DNB). Photo-irradiation was performed for 10 or 20s from a coronal direction. The post spaces were then filled with a dual-cure composite resin (Build-It FR) and light-cured for 60s. After 24h storage, each specimen was serially sliced into 8, 0.6 x 0.6mm-thick beams for the microTBS test. The bond strength data were divided into coronal and apical regions and analysed using three-way ANOVA and Games-Howell multiple comparison (alpha=0.05). RESULTS: The microTBS of the photo-cure adhesive resin, SE and PNB, significantly decreased (p<0.05) at the apical region when the photo-irradiation time was 10s. However, the bond strength of the SE group was significantly improved at both regions when photo-irradiation time was extended to 20s (p<0.05). There were no differences in microTBS of the photo-cure adhesive resin (PNB) cured for 20s and dual-cure adhesive resin (DNB) (p>0.05). CONCLUSION: Photo-cure adhesive was effective for application on root canal dentine when the photo-irradiation time was sufficient. Extension of photo-irradiation time to the adhesive improved the bond strength depending on the type of adhesive resin.     

Prevalence of dental caries and periodontal disease in patients with inflammatory bowel disease: a case-control study

AIM: Previous reports suggest a higher incidence of dental caries in patients with inflammatory bowel disease (IBD) and similarities in the immunopathogenesis of IBD and periodontitis. This study assessed the prevalence of periodontal disease and caries in patients with IBD. METHODS: In the present case-control study, 62 patients seeking treatment of IBD and 59 matched healthy controls of a dental practice were clinically examined. Oral soft-tissue alterations, the decayed, missing and filled tooth surface (DMF-S) index, dentine caries, plaque index (PI), bleeding on probing (BOP), probing pocket depth (PPD) and clinical attachment loss (CAL) were evaluated in each patient and in the controls. RESULTS: Patients with IBD showed a significantly higher number of oral manifestations compared with controls. The DMF-S index showed no significant differences, but there was a significantly higher number of subjects with dentine caries in patients with IBD. The mean PPD in patients with IBD was 2.08 versus 2.23 mm in controls (p=0.014). Compared with controls, patients with IBD had more sites with CAL of at least 4 mm (81% versus 64% in controls, p=0.07) and 5 mm (63% versus 46%, p=0.07), respectively. CONCLUSIONS: The results of this case-control study demonstrate a higher frequency of dentine caries in patients with IBD but the periodontal findings showed no distinct differences between cases and controls.     

改良组织块酶消化法培养人龋损牙髓干细胞的实验研究

目的:比较3种方法培养人龋损牙髓干细胞的成功率和细胞生长状态,以探求人龋损牙髓干细胞的最佳培养方法。方法:取18～22岁成人新鲜正常和龋损离体第三磨牙各25个,采用组织块法、酶消化法、改良组织块酶消化法培养牙髓干细胞。通过倒置显微镜观察组织块的贴壁以及细胞的形态和数量,并记录培养所需时间;有限稀释法纯化牙髓干细胞,流式细胞仪检测正常和龋损牙髓干细胞表面标记物Stro-1、CD 90的表达情况,绘制正常和龋损牙髓干细胞生长曲线。结果:组织块法、酶消化法和改良组织块酶消化法均可以培养出人龋损牙髓干细胞,其中改良组织块酶消化法可以在短时间内获得数量多,状态好,形态多样的细胞。通过有限稀释法获得的龋损牙髓干细胞生长速率高于正常牙髓干细胞(P<0.05)。结论:改良组织块酶消化法是一种较为理想的原代培养人龋损牙髓干细胞的方法。     

奥威尔牙膏抗牙本质过敏的疗效研究

目的:评价家庭日常使用奥威尔牙膏后牙本质过敏症状的改善情况。方法:将60名受试者随机分成2组:实验组使用奥威尔牙膏,对照组使用普通牙膏。两组受试者每天刷牙2次共8周,采用VAS记分评价基线0、2、4周和8周受试者的牙本质敏感程度。结果:实验组基线0周时记分为5.92±1.04,4周和8周后为4.39±1.30、3.98±1.19,可显著减少牙本质过敏症状(P<0.05);与对照组4周和8周后记分5.08±1.17、4.65±1.18相比,有显著性差异(P<0.05)。结论:奥威尔牙膏有抗牙本质过敏的效果。     

Carisolv去龋对龋损内层牙本质粘接修复的影响

目的：评价Carisolv化学机械去龋对龋损内层牙本质与复合树脂之间粘接强度的影响。方法：12个牙合面中龋离体恒磨牙,随机等分为2组,分别用Carisolv化学机械法和牙钻机械法去龋,去龋后用复合树脂充填,低速切片机将牙齿切割成0.9mm×0.9mm×8mm的条形试件,微拉伸测试仪检测粘接强度,扫描电镜观察断裂模式。结果：Carisolv化学机械去龋和牙钻机械去龋后龋损内层牙本质与复合树脂之间的粘接强度分别为：22.98±4.17MPa,20.01±3.97Mpa,差异具有显著性意义（P〈0.05）;试件断裂以混合破坏为主。结论：Carisolv化学机械去龋可增加复合树脂与龋损内层牙本质的粘接强度。     

Ageing-related effects of dye penetration in the apical 5 mm mesiobuccal and mesial roots of molars

This study examined how the tubular permeability in the apical 5 mm of mesial roots was affected by age, direction, distance from root apex, canal shape and canal number. Twenty mesiobuccal/mesial roots of maxillary/mandibular molars from three age groups (<30, 30–60, >60 years) were prepared. Maximal dye penetration in buccal, lingual, mesial and distal directions was measured at 1-mm segment depth and analysed statistically. The <30 years group, when comparing to the >60 years group, had significantly deeper dye penetration in buccal and lingual directions. The permeability in proximal directions was not affected by either age or canal number. In the >60 years group, neither direction, segment depth nor canal number significantly impacted the permeability. However, these parameters significantly impacted samples younger than 60 years. Effective removal of infected root canal dentine would depend on age and its related preferred direction, distance from root apex and canal number.