冷光牙齿漂白技术对活髓牙牙髓影响的病理观察

目的 探讨冷光牙齿漂白技术对活髓牙牙髓的影响.方法 选择因正畸需要拔除的40颗活髓牙,对照组(10颗)不做任何处理拔除,其余30颗牙采用冷光漂白后分别即刻拔除(15颗)和漂白7 d后拔除(15颗).40颗牙齿均制作病理切片,镜下观察牙髓组织形态.结果 所有活髓牙漂白前后均未发现有任何临床症状.漂白后即刻拔除组、7 d后拔除组以及对照组在镜下均表现为正常的牙髓组织结构,与对照组相比漂白后即刻拔除组及7 d后拔除组牙髓组织均无明显改变.结论 冷光牙齿漂白技术对活髓牙牙髓无明显不良影响,是一项安全可靠的漂白技术.     

Hydrogen peroxide induces cell proliferation and apoptosis in pulp of rats after dental bleaching in vivo: Effects of the dental bleaching in pulp

ObjectiveThis study provides an in vivo evaluation of the inflammatory response, levels of cell proliferation and apoptosis, and the presence of necrosis after dental bleaching with two concentrations of hydrogen peroxide (H₂O₂).DesignWistar rats were divided into Control (placebo gel), BLUE (20% H₂O₂, 1 × 50 min), and MAXX (35% H₂O₂, 3 × 15 min) groups. At 2 and 30 days, the rats were killed (n = 10). The jaws were processed for histology analysis and PCNA and Caspase-3-cleaved immunohistochemistry, and data were submitted to the Mann-Whitney or ANOVA test (P < 0.05).ResultsAt 2 days, the MAXX group showed necrosis and the BLUE group revealed moderate inflammation on the occlusal third of the crown (P < 0.05). At 30 days, tertiary dentin had formed and there was an absence of inflammation. The level of cell proliferation was higher in the middle third of the BLUE group (P < 0.05), and cervical of MAXX at 2 days (P < 0.05), decreasing at 30 days. The apoptosis was present at 2 days, particularly in the cervical third of the crown in the bleached groups (P < 0.05), with a decrease only at 30 days in the BLUE group (P < 0.05).ConclusionsThe concentration of H₂O₂ influences effects on the pulp tissue, where a higher concentration of H₂O₂ can cause necrosis in the pulp and a prolonged effect within the apoptotic process; lower concentrations of H₂O₂ provide moderate inflammation, cell proliferation and apoptosis with a reduction of these processes over time.     

Analysis of incisor pulp cell populations in Wistar rats of different ages

Pulp cell function and viability is important for maintaining tooth vitality throughout life. However, the effects of ageing on pulpal cell populations and pulp tissue remodelling are still unclear. The aim here was to quantify age-related cell-density changes in the pulp of rat incisor teeth, using histomorphometric analysis and ANOVA. Mandibular (n=35) and maxillary (n=34) incisors were carefully extracted from 20 Wistar rats aged between 1 and 18 months, fixed and processed for light microscopy. Cell counts were performed in mature and immature regions at both labial and lingual aspects of all teeth. Odontoblast and subodontoblast cell densities were reported per mm of pulp-dentine border and core fibroblast density per mm2 pulp tissue. Irrespective of age, odontoblast and subodontoblast densities were lower in the immature than the mature regions of both maxillary and mandibular incisors (P<0.001). However, in both regions odontoblast and subodontoblast densities decreased significantly with increasing age (P<0.0001). The age-related reduction in odontoblasts was significantly greater in mature than immature regions (P<0.02) but not influenced by other variables. In contrast, the age-related reduction in subodontoblasts was significantly different between mandibular and maxillary teeth (P=0.012) but not influenced by site. Unlike odontoblasts and subodontoblasts, core fibroblasts showed small but significant increases with increasing age (P<0.0001). These age-related reductions in the density of odontoblasts and subodontoblasts may partly explain the slower rate of secondary dentine secretion and decreased pulp repair activity associated with ageing.     

Acceptability,efficacy and safety of two treatment protocols for dental fluorosis: A randomized clinical trial

Objectives

This parallel randomized clinical trial evaluated the efficacy of two treatments for removing fluorosis stains.

Methods

Seventy individuals living in an area endemic for fluorosis, with at least four maxillary anterior teeth presenting fluorosis with a Thylstrup and Fejerskov index from 1 to 7, were randomized into two treatment groups (n = 35): GI – enamel microabrasion or GII – microabrasion associated with at-home bleaching. Microabrasion was performed using 37% phosphoric acid and pumice and, at-home tooth bleaching was performed with 10% carbamide peroxide. Areas of enamel opacities were recorded by digital camera at baseline and 1-month (1 M) after treatment. Two blinded examiners evaluated the reduction in the area (mm²) of opacity using software. Two visual analogue scales were used: one for recording tooth sensitivity and/or gingival irritation ranging from 1 (none) to 5 (severe) and the other to evaluate participant satisfaction with the treatment used ranging from 1 (no improvement) to 7 (exceptional improvement).

Results

1 M after treatment, both groups showed a significant reduction in the area of enamel opacity (p = 0.0001) and there was no difference between groups (p = 0.1). Most of the participants from both treatment groups reported no or mild tooth sensitivity and gingival irritation (p > 0.05). Participants reported that they were happy with the improvement in dental appearance, however, individuals from GII reported that they were happier than those from GI (p = 0.004).

Conclusions

Both treatment protocols were effective in reducing fluoride stains, however, when home bleaching was associated to enamel microabrasion, patients reported a major satisfaction with dental appearance.     

家用过氧化脲凝胶对氟斑牙着色斑漂白作用的临床评价

目的:评价家用过氧化脲凝胶对氟斑牙着色斑漂白的临床效果.方法:将24例氟斑牙患者的108颗着色氟斑牙,根据着色区着色深浅分为轻、中、重度3组.用过氧化脲凝胶进行家庭漂白.在治疗前、治疗结束时及治疗结束1年后,采用CMYK色值表对氟斑牙着色斑进行比色,记录漂白前、后的色阶变化及疗程,计算漂白有效率并评价疗效稳定性;用数字化疼痛评判法记录受试者术中牙的敏感度.采用SPSS13.0软件包对结果进行x2检验.结果:(1)轻度氟斑牙着色斑脱色效果显著,1个疗程内漂白有效率达100%;中、重度氟斑牙着色斑脱色效果稍差,有效率分别为94.29%和86.21%,3组间无统计学差异(P＞0.05).(2)治疗结束1年后复查,3组漂白有效率与治疗结束时比较均无统计学差异(P＞0.05).(3)用药时,部分患者有不同程度的牙酸痛症状,敏感率为56.52%,停止用药2～3h后,敏感症状消失.结论:家用过氧化脲凝胶治疗氟斑牙着色斑效果显著,具有一定的安全性和稳定性.     

Correlation between numbers of cells in human dental pulp and age: Implications for age estimation

ObjectiveThe aim of this study was to investigate correlations between dental pulp cell count of odontoblasts, subodontoblasts and fibroblasts and age, within different age groups. Formulation of regression equations using the dental pulp cell count for predicting age was attempted.DesignEighty-one extracted teeth were grouped into two age groups (6–25 years, 26–80 years). The teeth were demineralized and histological sections were prepared for cell count. Regression equations were generated from regression analysis of cell count and tested for age estimation.ResultsThe number of dental pulp cells were found to increase until around the third decade of life and following this, the odontoblasts and subodontoblasts cell numbers began to decline while the fibroblasts seemed to remain almost stationary. The Pearson correlation test revealed a significant positive correlation between the cell number for all type of cells and age in the 6–25 years group (r = +0.791 for odontoblasts, r = +0.600 for subodontoblasts and r = +0.680 for fibroblasts). In the 26–80 years age group, a significant negative correlation of the odontoblasts (r = −0.777) and subodontoblasts (r = −0.715) with age was observed but for fibroblasts, the correlation value was negligible (r = −0.165). Regression equations generated using odontoblasts and subodontoblasts cell number were applicable for age estimation. The standard error of estimates (SEEs) were around ± 5 years for 6–25 years and ± 8 years for 26–80 years age groups. The mean values of the estimated and chronological ages were not significantly different.ConclusionsA significant correlation between the cell count of odontoblasts and subodontoblasts with age was demonstrated. Regression equations using odontoblasts and subodontoblasts cell number can be used to predict age with some limitations.     

三种家用牙齿漂白剂对牙釉质结构及其相关力学性能的影响

目的 研究3种不同质量分数的家用牙齿漂白剂对人牙釉质结构和力学性能的影响,为评价市售家用牙齿漂白剂的安全性提供依据.方法 将60块人牙釉质样本按随机数字化表法随机分至4组:10％过氧化脲组、15％过氧化脲组、20％过氧化脲组和蒸馏水对照组,每组15块.在漂白组样本表面涂布漂白剂并将其置于37℃恒温箱中,漂白8h后去净漂白剂,再将样本保存于蒸馏水中16 h;蒸馏水对照组不做漂白处理.如此循环14 d分别用原子力显微镜、衰减全反射红外测试仪、显微拉曼光谱仪、显微硬度仪检测各组漂白前后釉质表面形貌、化学结构及硬度、断裂韧性等力学特性.结果 3个漂白组的釉质与对照组相比没有出现表面形貌、均方根表面粗糙度(P=0.774)、红外光谱中v2 CO32-∶v1 v3 PO43-(P=0.263)和显微硬度(P=0.829)的明显变化;10％、15％、20％过氧化脲组相对拉曼强度漂白后相对于漂白前的百分比分别为(105.74±11.34)％、(104.46±8.83)％和(99.52±9.32)％,与对照组[(97.62±7.46)％]相比差异均无统计学意义(P=0.062);但3个漂白组荧光背景强度漂白后相对于漂白前的百分比分别为(20.86±7.23)％、(22.14±7.34)％和(21.10±7.59)％,与对照组[(100.78±3.70)％]相比差异均有统计学意义(P＜0.001).同时,3个漂白组与对照组相比断裂韧性漂白后下降值差异亦有统计学意义(P =0.024、P=0.005、P=0.013).结论 在体外环境下,3种质量分数的家用牙齿漂白剂不会影响牙釉质中的无机物和显微硬度,但可能会造成牙釉质断裂韧性下降.     

Immunohistochemical evaluation of endothelial cell adhesion molecules in human dental pulp: effects of tooth preparation and adhesive application

OBJECTIVE: Studies have demonstrated that restorative procedures can initiate pulpal inflammation. Adhesion molecules on endothelial cells mediate the leukocyte-endothelium interaction, which is the fundamental event of inflammation. The aim of this study was to evaluate possible changes in the endothelial cell adhesion molecules (CAMs) of human dental pulp with tooth preparation, and after the application of one-step self-etch adhesive. MATERIALS AND METHODS: Twenty healthy human premolars and third molars scheduled to be extracted for orthodontic reasons were randomly assigned to four experimental groups. Group 1 involved sound intact teeth representing the controls. In group 2, teeth were prepared for full crown and extracted within 2h. Groups 3 and 4 comprised the teeth coated with one-step self-etch adhesive, iBond Gluma inside following the preparation and extracted after 24 and 48h, respectively. Tissue distribution and staining intensity of CAMs including E-selectin, P-selectin, ICAM-1, VCAM-1 and PECAM-1 was investigated in the pulp samples using monoclonal antibodies and the streptavidin-biotin-horse-radish immunoperoxidase procedure. The assessment of immunohistochemical reactions was performed by two independent observers using a semi-quantitative scale. RESULTS: All the CAMs evaluated were expressed by the healthy pulp tissues. Significant alterations in the distribution and staining intensity of CAMs were detected following tooth preparation. One-step self-etch adhesive tested in the present study induced inflammatory reactions in the pulp (P<0.05, Mann-Whitney U-test). CONCLUSION: It seems evident that tooth preparation for full crown and application of one-step self-etch adhesive on prepared teeth had a potential to interfere with the inflammatory response.     

Effectiveness of different carbamide peroxide concentrations used for tooth bleaching: an in vitro study

Objectives

This in vitro study evaluated the effectiveness of three carbamide peroxide concentrations used for tooth bleaching treatments.

Material and Methods

Sixty bovine dental slabs (6x6x3 mm) were obtained, sequentially polished, submitted to artificial staining (baseline) and randomized into four groups (n=15), according to the bleaching agent concentration: distilled water (control), 10% (CP10), 16% (CP16) or 37% (CP37) carbamide peroxide. CP10 and CP16 were covered with 0.2 mL of the respective bleaching gels, which were applied on enamel surface for 4 h/day during two weeks. Samples of CP37 were covered with 0.2 mL of the bleaching gel for 20 min. The gel was light activated by two 40-s applications spaced by 10-min intervals. The gel was renewed and applied 3 times per clinical session. This cycle was repeated at 3 sessions with 5 days of interval between them. Tooth shade evaluations were done with a digital spectrophotometer at T0 (baseline), T1 (after 1-week of treatment) and T2 (1-week post-bleaching). Tooth shade means were statistically analyzed by Kruskal-Wallis and Friedman''s tests and color parameters were analyzed by two-way ANOVA and Tukey''s test (p<0.05).

Results

At T1 and T2 evaluations, tooth shade was significantly lighter than at baseline for all treatment groups, considering the color parameters ΔL*, Δa*, Δb*, ΔE* (p<0.001) or tooth shade means (p<0.001). CP37 group showed lower shade mean change than CP10 and CP16 at T1 (p<0.01), but this difference was not statistically significant at T2 (p>0.05).

Conclusions

One week after the end of the treatment, all carbamide peroxide concentrations tested produced similar tooth color improvement.     

漂白对人牙釉质与树脂粘接强度的影响

目的 研究漂白对人牙釉质深层与树脂粘接强度的影响,探讨漂白后瓷贴面修复的粘接时机.方法 96个人恒牙试件均分为6个组,第1组不漂白,直接磨除釉质0.6～0.8 mm,第2～6组分别在35%过氧化氢漂白剂冷光辅助漂白后即刻、1、4、7、14 d磨除釉质0.6～0.8 mm,分别用粘接剂A(One-step plus)和B(Single bond)粘接.测量拉伸强度,作为粘接强度.结果 每个时间点两种粘接剂粘接强度的差异无统计学意义(P>0.01).A和B两种粘接剂中,第2、3、4组粘接强度[(17.79±3.53)和(19.41±3.37)MPa、(17.50±4.29)和(19.66±3.48)MPa、(18.39±3.58)和(19.53±3.21)MPa]比第1组[(25.94±4.88)和(28.02±4.36)MPa]降低约30%;第5组粘接强度[(22.46±3.98)和(23.74±5.04)MPa]与第1组的差异无统计学意义(P>0.01);第6组粘接强度[(26.03±4.47)和(27.88±4.78)MPa]与第1组相差不大.结论 漂白后人牙釉质深层与树脂粘接剂的粘接强度明显下降,最好在漂白两周后进行瓷贴面粘接.     

High-efficiency tooth bleaching using non-thermal atmospheric pressure plasma with low concentration of hydrogen peroxide

Light-activated tooth bleaching with a high hydrogen peroxide (HP; H₂O₂) concentration has risks and the actual role of the light source is doubtful. The use of conventional light might result in an increase in the temperature and cause thermal damage to the health of the tooth tissue.

Objective:

This study investigated the efficacy of tooth bleaching using non-thermal atmospheric pressure plasma (NAPP) with 15% carbamide peroxide (CP; CH₆N₂O₃) including 5.4% HP, as compared with conventional light sources.

Material and Methods:

Forty human teeth were randomly divided into four groups: Group I (CP+NAPP), Group II (CP+plasma arc lamp; PAC), Group III (CP+diode laser), and Group IV (CP alone). Color changes (ΔE ) of the tooth and tooth surface temperatures were measured. Data were evaluated by one-way analysis of variance (ANOVA) and post-hoc Tukey''s tests.

Results:

Group I showed the highest bleaching efficacy, with a ΔE value of 1.92-, 2.61 and 2.97-fold greater than those of Groups II, III and IV, respectively (P<0.05). The tooth surface temperature was maintained around 37ºC in Group I, but it reached 43ºC in Groups II and III.

Conclusions:

The NAPP has a greater capability for effective tooth bleaching than conventional light sources with a low concentration of HP without causing thermal damage. Tooth bleaching using NAPP can become a major technique for in-office bleaching in the near future.     

Effects of different bleaching methods on shear bond strengths of orthodontic brackets

Objective:To evaluate the effects of different bleaching methods on the shear bond strength (SBS) of orthodontic brackets.Materials and Methods:Forty-five freshly extracted premolars were randomly divided into three groups (n  =  15 per group). In group I, bleaching was performed with the office bleaching method. In group II, bleaching was performed with the home bleaching method. Group III served as the control. Orthodontic brackets were bonded with a light cure composite resin and cured with an LED light. After bonding, the SBS of the brackets were tested with a Universal testing machine.Results:Analysis of variance indicated a significant difference between groups (P < .001). The highest values for SBS were measured in group III (20.99 ± 2.32 MPa). The SBS was significantly lower in groups I and II than in group III (P < .001). The lowest values for SBS were measured in group II (6.42 ± 0.81 MPa). SBS was significantly higher in group I than in group II (P < .001).Conclusions:Both of the bleaching methods significantly affected the SBS of orthodontic brackets on human enamel. Bleaching with the home bleaching method affected SBS more adversely than did bleaching with the office bleaching method.     

过氧化物漂白对牙釉质维氏硬度影响的实验研究

目的 通过观察过氧化物漂白后牙齿的硬度变化,探讨过氧化物浓度、漂白时间对牙釉质维氏硬度的影响,以期为临床提供参考.方法 取新鲜牛牙制成牙釉质平面,按近远中对称分为漂白区和对照区,使用不同质量分数(10％、16％、22％、25％、30％)的过氧化脲、含0.25％氟化钠的过氧化脲(过氧化脲质量分数分别为10％、15％、20％)对漂白区进行漂白处理或使用10％过氧化氢(漂白20 min,1、3、5、16h)和35％过氧化氢(漂白8、30 min,1、2、5h)漂白不同时间,每种处理的样本量均为5.测定牙釉质维氏硬度,计算硬度变化率.使用单因素方差分析进行统计学分析.结果 不同质量分数过氧化脲或不同质量分数含氟化钠过氧化脲漂白后牙釉质维氏硬度与对照区的差异均无统计学意义(P＞0.05).10％过氧化氢漂白处理16 h后牙釉质维氏硬度(248±21)与对照区(299±32)的差异有统计学意义(P＜0.05).牙釉质硬度变化率随过氧化物浓度增加而增大.结论 按使用说明对牙齿进行漂白不会造成牙釉质硬度显著降低.     

The effect of hydrogen peroxide concentration on metal ion release from dental amalgam

OBJECTIVES: The aim of this study was to investigate the effect of hydrogen peroxide (HP) concentration on metal ion release from dental amalgam. METHODS: Dental amalgam discs (n=25) were prepared by packing amalgam into cylindrical plastic moulds (10 mm diameter and 2 mm height). The discs were divided into five equal groups and each group was immersed in 20 ml of either 0%, 1%, 3%, 10% or 30% HP solution for 24 h at 37 degrees C. Samples were taken for metal ion release determination (Hg, Ag, Sn and Cu) using inductively coupled plasma mass spectrometry (ICP-MS). The surface roughness of each disc was measured before and after bleaching. RESULTS: The differences in concentration of metal ions released after treatment with 0% (control) and each of 1%, 3%, 10% and 30% HP were statistically significant (p<0.05). Metal ion release for the elements (Hg, Ag, Sn and Cu) increased with exposure to increasing concentrations of HP. Surface roughness measurements of the samples before and after treatments with HP solutions were not significantly different (p>0.05). CONCLUSIONS: Exposure to HP bleaching agent was associated with increased metal ion released from dental amalgams compared to treatment with a control solution. Ion release was in proportion to the peroxide concentration tested, with the highest concentration associated with the greatest metal ion release for all elements investigated.     

Effect of bleaching agents on bonding to pulp chamber dentine

AIM: To determine the effect of intracoronal bleaching agents on adhesion of bonding agents to pulp chamber dentine. METHODOLOGY: Forty extracted human maxillary anterior teeth were randomly divided into four groups of 10 teeth each. Bleaching agents were sealed in pulp chambers for 7 days, as in clinical use. Group 1 (control): distilled water, group 2: 35% hydrogen peroxide, group 3: sodium perborate mixed with water, and group 4: sodium perborate mixed with 35% hydrogen peroxide. Teeth were stored in saline at 37 degrees C for 7 days. After the bleaching agent was removed, teeth were leached in water for a further 7 days prior to bonding. The crown was cut vertically from mesial to distal and the labial pulp chamber dentine was prepared for bonding with Clearfil SE-Bond and filled with resin composite (Clearfil AP-X). The bonded specimens were kept moist at 37 degrees C for 24 h. Microtensile bond strengths were determined using a universal testing machine. Additional teeth were prepared using the same bleaching procedures to investigate the scanning electron microscopic appearance of the dentine surface. RESULTS: Mean values (+/-SD) of microtensile bond strength for the experimental groups were: group 1: 5.29 +/- 2.21 MPa, group 2: 5.99 +/- 1.51 MPa, group 3: 9.17 +/- 1.65 MPa and group 4: 3.99 +/- 1.31 MPa. Dentine treated with sodium perborate in water (group 3) had significantly higher mean bond strength when compared with the other three groups (P < 0.05, Tukey's test). Mean bond strength was lowest when dentine was treated with sodium perborate plus hydrogen peroxide (group 4). CONCLUSIONS: In terms of subsequent bond strength during restoration, sodium perborate mixed with distilled water appears to be the best intracoronal bleaching agent.     

3种浓度过氧化脲漂白剂对牙科陶瓷表面粗糙度的影响

目的评估3种浓度过氧化脲漂白剂对牙科陶瓷表面粗糙度的影响。方法 80个瓷块按随机数字表法分成4组。A、B、C组所有瓷块进行为期3周,每天8 h的漂白,A组漂白剂为质量分数10%的过氧化脲,B组为质量分数15%的过氧化脲,C组为质量分数20%的过氧化脲;D组为空白对照组,浸泡于人工唾液里。表面粗糙度仪测量所有样本初始时和漂白1 d、2 d、3 d、1周、2周、3周后的瓷块表面粗糙度,并进行统计学分析。结果 A、B、C、D 4组瓷块的初始表面粗糙度分别为（0.073±0.003）μm、（0.073±0.002）μm、（0.072±0.003）μm、（0.074±0.003）μm,3周后的粗糙度分别为（0.073±0.004）μm、（0.073±0.005）μm、（0.074±0.006）μm、（0.074±0.005）μm。7个时间点,4组组间和组内表面粗糙度差异均无统计学意义（P＆gt;0.05）。结论 3种浓度过氧化脲漂白剂对牙科陶瓷表面无明显不良影响。     

Effects of Notch ligand Delta1 on the proliferation and differentiation of human dental pulp stem cells in vitro

Objective

Notch signalling controls cell fate decisions in adult and embryonic tissues. The Notch ligand Delta1 is known to influence proliferation and differentiation of many kinds of tissue specific stem cells. In the present study, we investigated the role of Delta1 in the regulation of dental pulp stem cells (DPSCs) in vitro.

Methods

DPSCs were isolated from impacted third molars. Expression of human Notch1, 2 and Delta1 in DPSCs were detected by immunochemistry. Delta1 overexpressed DPSCs were constructed by a retroviral method. Delta1 transduced DPSCs proliferation changes were examined by means of colony-forming assay, BrdU incorporation assay and cell cycle analysis. Delta1 transduced DPSCs were cultured in differentiation-inductive medium. The nodule formation and DSPP expression were evaluated.

Results

It was shown that the Notch receptors and Delta1 ligand were expressed throughout the proliferation and differentiation process of cultured dental pulp stem cells. Furthermore, it was found in our study that Delta1 could significantly enhance the proliferation of DPSCs and permit DPSCs differentiating into odontoblast-like cells in differentiation-inductive environments.

Conclusions

Our findings verified that Notch-Delta1 signalling was expressed in human DPSCs in vitro and appeared to play pivotal role in DPSCs proliferation enhancement and differentiation regulation, thereby consistent with the hypothesis that the Notch pathway controls stem cell fate during pulp regeneration.     

Beyond冷光美白治疗着色型氟斑牙的临床效果

目的探讨Beyond冷光美白对着色型氟斑牙的临床效果。方法 20名着色型氟斑牙受试者,用Be-yond冷光美白进行3个疗程的漂白治疗,每个疗程结束后由患者本人和两位未参与治疗的医生对疗效进行评分。结果 3个疗程结束后,受试者评分为(95.43±5.98)分,医生甲评分为(95.61±7.11)分,医生乙评分为(96.12±5.76)分。结论 3个疗程的Beyond冷光美白对着色型氟斑牙疗效满意。