Formation of Dentinal Bridge on Surface of Regenerated Dental Pulp in Dentin Defects by Controlled Release of Fibroblast Growth Factor–2 From Gelatin Hydrogels

IntroductionPulp regeneration therapy is important to overcome the limitations of conventional therapy to induce reparative dentinogenesis. In the present study, we examined the effects of controlled release of different dosages of fibroblast growth factor–2 (FGF-2) from gelatin hydrogels to regenerate the dentin-pulp complex.MethodsAfter the amputation of dental pulp of rat molars, gelatin hydrogels incorporating various dosages of FGF-2 were individually implanted into dentin defects above the sites of the amputated pulps. Histologic changes as well as the expression of dentin matrix protein–1 (DMP-1) and nestin in the dentin defect area above the amputated pulp were analyzed.ResultsWe found that controlled release of high doses of FGF-2 from gelatin hydrogels induced DMP-1–positive calcified particles in the proliferating pulp, whereas a moderate dose of FGF-2 induced DMP-1–positive dentinal bridge on the surface of the proliferating pulp. These findings indicate that the dosage of released FGF-2 has an influence on the structure of calcified tissue regenerated in dentin defects. In addition, pulp cells near calcified tissues regenerated in dentin defects were nestin-negative, suggesting that the calcified tissues might be osteodentin.ConclusionsOur results showed that the dentin regeneration on amputated pulp, not reparative dentin formation toward amputated pulp, can be regulated by adjusting the dosage of FGF-2 incorporated in biodegradable gelatin hydrogels.     

SOD复合氢氧化钙切髓术的实验研究

将ＳＯＤ（超氧化物歧化酶）复合氢氧化钙用于猴磨牙切髓术，观察其组织学效果。结果表明：术后６个月，可诱导牙本质桥形成，具有典型规则的管样牙本质形成，偶见骨样牙本质。对照组氢氧化钙也可诱导牙本质桥形成，以不规则管样牙本和骨样牙本质为主。结果显示ＳＯＤ与氢氧化钙联合使用在诱导牙本质桥形成方面优于单纯氢氧化钙。     

SOD与SOD复合Ca(OH)_2切髓术的组织学疗效对比

目的：观察超氧化物岐化酶（ＳＯＤ）、ＳＯＤ复合氢氧化钙〔Ｃａ（ＯＨ）２〕（ＣＨ）作为盖髓剂的组织学疗效。方法：将ＳＯＤ、ＳＯＤ复合Ｃａ（ＯＨ）２用于猴磨牙切髓术，观察组织学效果。结果：术后６个月，均可诱导牙本质桥形成，但组织学效果不同，ＳＯＤ组以骨样牙本质为主；ＳＯＤ复合Ｃａ（ＯＨ）２组以典型规则的管样牙本质为主；对照组Ｃａ（ＯＨ）２以不规则管样牙本质和骨样牙本质为主。结论：ＳＯＤ复合Ｃａ（ＯＨ）２在诱导牙本质桥形成的组织学效果方面优于单纯使用ＳＯＤ。     

猴磨牙SOD切髓术的实验研究

本文从抗炎、抗自由基的角度观察了ＳＯＤ在猴牙切髓术后６个月的组织学反应。结果表明：ＳＯＤ与牙髓组织有良好的生物相容性，可诱导牙本质桥形成，以骨样牙本质为主。对照组氢氧化钙也可诱导牙本质桥形成，以管状牙本质为主。本实验显示了临床应用ＳＯＤ保存活髓治疗的可能性。     

可乐丽菲露SE BOND用于直接盖髓术的组织学评价

目的:对可乐丽菲露SEBOND在人体用于直接盖髓术进行组织学评价。方法:选择24名志愿者共45颗健康人第三磨牙,41颗在牙合面制备Ⅰ类洞并在洞底作人工穿髓孔,然后分为2组,实验组以可乐丽菲露SEBOND盖髓,对照组以氢氧化钙盖髓。4颗作为空白对照。所有实验牙齿分别在盖髓后的7、30、90d后拔除并进行组织学检测。结果:实验组和对照组志愿者均未出现术后实验牙齿敏感症状。病理检测显示,在7d和30d的观察期内2组均有轻度到中度的炎性反应,但可乐丽菲露SEBOND组的炎性反应较氢氧化钙组轻,其组织学评价分级上的差别有统计学意义(P<0.05)。在90d的观察期内2组均无明显的炎性反应,而牙本质桥的形成在氢氧化钙组显著多于可乐丽菲露SEBOND组,氢氧化钙组7例标本中有6例标本有牙本质桥的形成,可乐丽菲露SEBOND组7例标本中有3例形成,其差别有统计学意义(P<0.05)。结论:可乐丽菲露SEBOND对牙髓的刺激性较小,但诱导牙本质形成的能力较氢氧化钙弱。     

Immunohistochemical study of small integrin-binding ligand, N-linked glycoproteins in reactionary dentin of rat molars at different ages

Small integrin-binding ligand, N-linked glycoproteins (SIBLING) are believed to play key roles in the process of biomineralization. Reactionary dentin (RD), formed by odontoblasts in response to external stimuli, differs morphologically from primary dentin (PD). To test our hypothesis that the microscopic changes reflect variations in molecular mechanisms involved in formation of the two forms of dentin, and to characterize RD further, we compared the distributions of four SIBLING proteins [bone sialoprotein (BSP), osteopontin (OPN), dentin matrix protein 1 (DMP-1) and dentin sialophosphoprotein (DSPP)] in naturally occurring RD with those in PD. Molars of rats aged 12, 18, 24 and 36 wk were analyzed using immunohistochemistry with antibodies against BSP, OPN, DMP-1, and dentin sialoprotein (a fragment of DSPP). Differences in the distribution of the four SIBLING proteins were evident. Bone sialoprotein, not seen in PD, was consistently observed in RD. Osteopontin, almost absent from PD, was clearly observed in RD. The expression levels of DMP-1 and DSP in RD were lower than in PD. Elevated expression of BSP and OPN, along with a marked decrease of dentin sialoprotein and DMP-1 in RD, suggests a difference in the mechanism of formation of the two forms of dentin.     

Immunohistochemical study of hard tissue formation in the rat pulp cavity after tooth replantation

While mineralized tissue is formed in the pulp cavity after tooth replantation or transplantation, little is known of this hard tissue formation. Therefore, we conducted histological and immunohistochemical evaluations of hard tissue formed in the pulp of rat maxillary molars after tooth replantation. At 5 days after replantation, degenerated odontoblasts were lining the pulp cavity. At 14 days, dentin- or bone-like tissue was present in the pulp cavity. Immunoreactivity for osteopontin (OPN) and bone sialoprotein (BSP) was strong in the bone-like tissue, but weak in the dentin-like tissue. Conversely, dentin sialoprotein (DSP) was localized in the dentin-like tissue, but not in the bone-like tissue. Cells positive for BMP4, Smad4, Runx2, and Osterix were found around the blood vessels of the root apex at 5 days. At 14 days, these cells were also localized around the bone-like tissue. Cells expressing alpha-smooth muscle actin (SMA) were seen around the newly formed bone-like tissue, whereas no such cells were found around the newly formed dentin-like tissue. In an experiment involving the transplantation of a green fluorescent protein (GFP)-transgenic rat tooth into a wild-type rat tooth socket, GFP-positive cells were detected on the surface of the bone-like tissue and over all dentin-like tissue. These results indicate that the original pulp cells had the ability to differentiate into osteoblast-like cells as well as into odontoblast-like cells.     

Influence of Preoperative Pulp Inflammation in the Outcome of Full Pulpotomy Using a Dog Model

IntroductionThis study aimed to evaluate the impact of preoperative pulp inflammation on the histologic outcome of full pulpotomy performed in mature permanent posterior teeth using 4 different biomaterials.MethodsFive beagle dogs (providing a total of 120 roots) were selected. Dentin exposure was performed in teeth from the second and third quadrants. One week later, full pulpotomy procedures were performed using 4 different bioactive materials (ProRoot MTA [MTA], TotalFill BC Putty [BC], Biodentine [BIO], and an experimental cement [ie, pulp capping material]). The hemostasis time was registered. After 14 weeks, the animals were killed. Pulp-dentin tissues were histologically and radiographically assessed. The significance level was set at .05.ResultsTeeth with previously exposed dentin revealed a statistically significant increase in the time required to achieve hemostasis (P < .001), therefore confirming the pulp inflammation status induced by 1-week exposure of occlusal dentin before performing full pulpotomy. There was no radiographic evidence of root resorption, periapical radiolucency, or lamina dura alterations. No statistically significant differences were observed between normal and inflamed pulp regardless of the evaluated histologic parameters. Moreover, histologic data concerning calcified barrier formation and the pulp tissue response show better results for BIO without statistical differences compared with MTA or BC (P > .05). The pulp capping material presented a lower performance, with statistically significant differences being detected in regard to the remaining 3 tested materials (P < .001).ConclusionsRadiographic and histologic outcomes of full pulpotomy are not jeopardized by short-term preoperative pulp inflammation. Moreover, BIO, MTA, and BC cements present suitable alternatives to be used as pulp capping agents.     

乳牙活髓切断术不同盖髓剂的实验研究

目的:比较不同盖髓剂用于乳磨牙活髓切断的效果.方法:36颗小型猪乳磨牙均分为4组.分别用氢氧化钙,氢氧化钙碘仿,FC,戊二醛制剂做盖髓剂行活髓切断术,以对侧同名牙做对照.术后定期做X光和组织病理学观查.结果:X光片检查结果显示:术后2,4,6个月各实验组根尖、根周未见异常,牙根吸收程度与对照组一致.组织病理学结果表明:术后4,6个月用氢氧化钙(88.8%),氢氧化钙碘仿(100%)及戊二醛(100%)做盖髓剂术后有修复性牙本质形成牙本质桥,根髓正常.FC组无完整牙本质桥形成,根髓可见炎症细胞.结论:氢氧化钙碘仿及戊二醛糊制剂做乳牙活髓切断的盖髓剂较为适合.     

Comparison of iRoot BP Plus and Calcium Hydroxide as Pulpotomy Materials in Permanent Incisors with Complicated Crown Fractures: A Retrospective Study

IntroductionCalcium hydroxide has been used as a traditional pulpotomy agent for a long time but has some disadvantages. iRoot BP Plus (Innovative Bioceramix Inc, Vancouver, Canada) is a newly developed, ready-to-use calcium silicate–based bioactive ceramic with excellent bioactivity and sealing ability. However, whether iRoot BP Plus shows superiority over calcium hydroxide as a pulpotomy material on permanent incisors with complicated crown fractures remains unknown.MethodsThis research included 205 permanent incisors with complicated crown fractures. These teeth were treated with pulpotomy and divided into 2 groups according to the pulpotomy material (105 treated with iRoot BP Plus and 100 with calcium hydroxide). Clinical and radiographic information was collected during the 12- to 24-month follow-up period. The formation of reparative dentin bridges and pulp canal obliteration were analyzed using radiographs in both groups.ResultsThe success rates for recall in the average follow-up period of 17.5 ± 4.4 months (12–24 months) after pulpotomy treatment were significantly different between the 2 groups, with 99% for the iRoot BP Plus group and 93% for the calcium hydroxide group. Reparative dentin bridges were observed in 92.4% of the iRoot BP Plus group and 90% of the calcium hydroxide group, but the difference was not significant. Pulp canal obliteration was observed in 2 teeth (2%) in each group.ConclusionsThe success rates obtained in our study indicate that iRoot BP Plus as a pulpotomy agent can be a suitable alternative to calcium hydroxide to manage complicated crown fractures.     

Bone sialoprotein-induced reparative dentinogenesis in the pulp of rat’s molar

Bone sialoprotein (BSP), an osteogenic protein (OP), mixed with a carrier, was implanted in the pulp of rat first upper molars (OP group). Cavities were prepared with dental burs and pulp perforation was carried out by pressure with the tip of a steel probe. After 8, 14, and 30 days, the rats were killed and the pulps of the OP group were compared with (1) a sham group (S group), (2) a group where the carrier was implanted alone (C group), and (3) capping with calcium hydroxide (Ca group). After 8 days, a few inflammatory cells were seen, mostly located at the pulp surface near the perforation. In the Ca group, a dentin bridge started to form, in contrast to the other groups. After 15 days, globular structures were seen in the pulps of the S and C groups. A reparative osteodentin bridge isolated the pulp from the cavity in the Ca group. Variable reactions were seen in the OP group, with some evidence of cell and matrix alignments or plugs of osteodentin in continuity with an inner layer of reparative dentin. After 30 days, irregular osteodentin formation was observed in the pulps of the S and C groups, with a tendency for globular structures to merge, but with interglobular spaces filled by pulp remnants. In the Ca group, osteodentin was observed in the mesial part of the pulp chamber. In the BSP-implanted group, the osteogenic protein stimulated the formation of a homogeneous dentin-like deposit occupying most of the mesial part of the pulp. Apparently, BSP stimulates the differentiation of cells which secrete an organized extracellular matrix more efficiently than any other capping material used so far. Altogether, the results reported here support that bone sialoprotein displays novel bioactive properties and is capable of stimulating in 1 month’s time the development of a thick reparative dentinal tissue in the pulp, occluding the perforation and filling the mesial third of the pulp chamber. Received: 13 October 1999 / Accepted: 6 December 1999     

硅酸钙生物陶瓷对牙髓细胞体外增殖分化的影响

目的:应用硅酸钙(CaSiO3,CS)生物陶瓷作用于人牙髓细胞(human dental pulp cells,hDPCs),研究其对hDPCs增殖及向成牙本质细胞方向分化的影响。方法:从年轻健康患者(18²0岁)拔除的智齿或前磨牙牙髓组织中获取hDPCs进行培养。将质量浓度为0.2 g/mL的CS浸提液按1/2、1/4、1/8、1/16、1/32、1/64和1/128倍比稀释后作用于hDPCs。MTT实验检测不同质量浓度CS浸提液对hDPCs增殖的影响,进而筛选出最佳浓度。以最佳质量浓度(1/64倍比稀释)CS浸提液培养hDPCs 2、4 d后,Real-Time PCR检测以下hDPCs成牙本质相关基因的表达:牙本质涎磷蛋白(dentin sialophosphoprotein,DSPP)、牙本质基质蛋白-1(dentin matrix protein 1,DMP-1),Ⅰ型胶原(collagen typeⅠ,COL-Ⅰ)、骨钙蛋白(osteocalcin,OCN)、骨桥蛋白(osteopontin,OPN);培养7、14 d后碱性磷酸酶(alkaline phosphatase,ALP)染色及半定量检测ALP活性。结果:最佳质量浓度(1/64倍比稀释)CS浸提液能够促进hDPCs的增殖,对牙髓细胞DSPP、DMP-1、COL-1、OPN等成牙本质相关基因的表达有较为明显的促进作用。ALP染色及半定量分析显示该浓度的CS浸提液能够提高hDPCs分泌ALP的活性。结论:最佳质量浓度(1/64倍比稀释)CS浸提液能够明显促进hDPCs的增殖,提高成牙本质相关基因的表达,进而促进hDPCs向成牙本质细胞方向分化,为后期hDPCs结合CS支架材料进行牙本质再生的研究打下基础。     

Histological and scanning electron microscopy assessment of various vital pulp-therapy materials

Pulp capping and pulpotomy procedures were performed on 15 male mongrel dogs. Three materials were used: calcium hydroxide, acid-etched dentin bonding, and mineral trioxide aggregate. Six of the animals were killed at 50 days and nine were killed at 150 days. Samples from 11 dogs were used for histological evaluation, and the remaining dog samples were used for scanning electron microscopy evaluation. Each slide was graded histologically according to previously published criteria. Scanning electron microscopy analysis was performed, and the weight percentage of elements found in the dentin of a nontreated tooth versus the bridge formed in the exposed specimen was established. By evaluating pulp inflammation in vital pulp-therapy treatments, it was found that mineral trioxide aggregate was not significantly different from the untreated control group, both in pulp-capping procedures at 50 days (p = 0.357) or 150 days (p = 0.198) and pulpotomy procedures at 50 days (p = 0.357) or 150 days (p = 0.198). Moreover, histologically mineral trioxide aggregate was a considerably better material than calcium hydroxide or acid-etched dentin bonding in maintaining the integrity of the pulp.     

Glucose Transporter 2 and 4 Are Involved in Glucose Supply during Pulpal Wound Healing after Pulpotomy with Mineral Trioxide Aggregate in Rat Molars

IntroductionPulp capping materials allow healing of injured pulp with a layer of reparative dentin. Glucose is needed to cure the injured area. Glucose is transported by glucose transporter (Glut) 2 and Glut4, which are transmembrane proteins that act as gatekeepers. We hypothesized that the transport of glucose via Glut2/Glut4 might contribute to the production of a dentin bridge during wound healing. Therefore, we explored Glut2 and Glut4 expression during reparative dentinogenesis after mineral trioxide aggregate capping.MethodsThe upper left first molar of 8-week-old Wistar rats underwent pulpotomy with mineral trioxide aggregate. At 1, 3, 5, 7, and 14 days after treatment, localization and colocalization of Glut2, Glut4, nestin (odontoblast marker), and antiendothelial cell antigen 1 (RECA-1; endothelial cell marker) were analyzed with immunohistochemical staining. Messenger RNA expression levels of Slc2a2 (encoding Glut2), Slc2a4 (encoding Glut4), Igf-1r (encoding insulinlike growth factor 1 receptor), and nestin were analyzed in the extracted teeth using real-time polymerase chain reaction.ResultsGlut2 and Glut4 were localized within odontoblasts and endothelial cells in normal control teeth. Three days after pulpotomy, Glut2- and Glut4-positive cells were detected; 7 days after pulpotomy, immunoreactivity for Glut2 and Glut4 was confined to newly differentiated odontoblastlike cells arranged beneath reparative dentin. Messenger RNA expression levels of Slc2a2 and Slc2a4 were significantly up-regulated after pulpotomy.ConclusionsGlut2 and Glut4 regulate glucose transport during wound healing beneath the injured area. This may contribute to the development of new vital pulp therapy for patients with deep caries.     

Human pulpal response to mineral trioxide aggregate (MTA): a histologic study

The purpose of this study was to study the histologic changes in the dental pulp following pulpotomy with Mineral Trioxide Aggregate (MTA) and Calcium hydroxide. Pulpotomies were performed on premolar teeth that were to be extracted for orthodontic reasons. The radicular pulp was capped with either MTA or Calcium hydroxide and restored with IRM. The teeth were extracted at 4 and 8 week intervals, fixed in 10% formalin and then kept in 5% nitric acid for 28 days for demineralization. Longitudinal sections were then prepared and viewed under light microscope. The pulps capped with MTA (at the end of 4 weeks and 8 weeks) showed dentin bridge formation which was more homogenous and continuous with the original dentin when compared to the pulps capped with calcium hydroxide. The pulpal inflammation was also less in the MTA group as compared to the calcium hydroxide group at the end of 4 and 8 weeks.     

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目的比较部分活髓切断术和间接盖髓术两种方法治疗年轻恒前牙外伤冠折近髓的临床疗效,为临床寻求更佳治疗方法。方法对2005—2008年来济宁口腔医院儿童牙病科就诊的24例前牙外伤患者的31颗冠折近髓的患牙,按患者的就诊顺序随机分成部分活髓切断组(16颗)和间接盖髓组(15颗),分别采用部分活髓切断术和间接盖髓术对患牙进行治疗,随诊观察2年。结果部分活髓切断组的成功率为93.7%,间接盖髓组的成功率为80.0%,两组成功率比较差异无统计学意义(P>0.05)。结论采用部分活髓切断术治疗冠折近髓的年轻恒前牙可能较间接盖髓术更有优势。     

Application of High-frequency Radio Waves to Direct Pulp Capping

Introduction

In vital pulp therapy such as direct pulp capping, clinical success rates depend on achieving hemostasis in exposed pulp tissue. For hemostasis of exposed pulp tissue, gentle pressure by cotton pellets moistened with sodium hypochlorite is most commonly used. However, more rapid and reliable methods are necessary. Therefore, we focused on high-frequency radio waves (HRW).

Methods

To evaluate reparative dentin induction by HRW, we used a rat direct pulp capping model and performed hemostasis by using HRW of several strengths, covering the pulp with calcium hydroxide as a direct capping agent. After 14 or 28 days, rats were killed, and reparative dentin and pulp inflammation were investigated histologically.

Results

Radio wave–induced hemostasis required less time when compared with the control group. Reparative dentin with regularly arranged dentinal tubules was observed in the HRW group.

Conclusions

HRW induce hemostasis and produce high-quality reparative dentin and reduced pulpal inflammation.     

大鼠牙乳头细胞复合微孔滤膜形成牙本质样结构的实验研究

目的 观察SD大鼠牙乳头细胞在复合有转化生长因子β1(transforming growth factor-β1,TGF-β1)的微孔滤膜上形成牙本质样结构的能力,为组织工程化具有一定规则形状的牙本质提供实验依据.方法 取传代培养的第二代SD大鼠牙乳头细胞消化、离心,所得细胞团与复合有TGF-β1的微孔滤膜相结合,体外培养6 d或体内移植2周,观察附合物上细胞生长和硬组织形成情况.结果 体外培养观察到靠近微孔滤膜的牙乳头细胞发生极化,呈高柱状沿滤膜排列,并有细胞突起伸人材料的多孔结构中,牙本质涎蛋白(dentin sialoprotein,DSP)与牙本质基质蛋白1(dentin matrix protein-1,DMP-1)表达阳性;体内移植2周移植物可见管状基质沿滤膜表面沉积,扫描电镜可见厚度基本一致的管状牙本质样结构,DSP、DMP-1在高柱状细胞、管状基质和邻近的牙乳头细胞中均有表达.结论 复合有TGF-β1的微孔滤膜能够有效趋化和诱导成牙本质细胞前体细胞在其表面分化,并均匀分泌基质,矿化形成结构规则的牙本质样结构.     

辛伐他汀-胶原蛋白复合海绵用于大鼠磨牙直接盖髓的实验研究

目的 评估辛伐他汀-胶原蛋白复合海绵作为直接盖髓材料的疗效及可行性。方法 120只SD大鼠随机分成3组,即辛伐他汀-胶原蛋白海绵组（SIM组）、胶原蛋白海绵组（CS组）及氢氧化钙组（CH组）,每组40只。在每只大鼠左上颌第一磨牙咬合面开髓,分别用3种材料直接盖髓,玻璃离子充填,并设对侧上颌第一磨牙为正常对照组。在术后第1、3、7、14、28天处死大鼠后拍摄X线片、苏木精-伊红（HE）及Masson’s Thichrome染色,观察牙髓组织生物学反应及牙本质桥形成情况。结果 影像学上,CH组术后第28天见穿髓孔处有高密度阻射影且封闭穿髓孔;术后第14天和第28天,SIM组在穿髓孔处见有高密度阻射影且穿髓孔封闭;而CS组仅在穿髓孔远中见高密度钙化团块影像,但未见钙化组织将穿髓孔封闭。HE及Masson’s Thichrome染色结果显示：不同时间点,3组中观察到不同的炎症反应,CS组炎症程度最重,SIM组与CS组的炎症反应程度在术后第14、28天存在统计学差异（P<0.01）。SIM组的炎症反应程度比CH组轻,在术后第14天二者存在统计学差异（P<0.05）。与另外两组相比,SIM组修复性牙本质形成的速度更快、质量更好,在术后第14天,SIM组与CH组、CS组存在统计学差异（P<0.05）,且在术后第28天,SIM组、CH组与CS组均存在统计学差异（P<0.05）。结论 辛伐他汀-胶原蛋白复合海绵生物相容性好,促进修复性牙本质形成能力较强,作为盖髓材料具有良好的应用前景。