Dental pulp capping: effect of Emdogain Gel on experimentally exposed human pulps

AIM: To investigate the effect of Emdogain Gel (Biora AB, Malmo, Sweden), consisting of a enamel matrix derivative (EMD) in a propylene glycol alginate (PGA) vehicle, on experimentally exposed human pulps and to register postoperative symptoms. METHODOLOGY: Nine pairs of contralateral premolars scheduled for extraction on orthodontic indications were included. Following a superficial pulp amputation performed with a small (016) diamond bur, either EMDgel or a mix of calcium hydroxide and sterile saline was placed at random in contact with the pulp wound. The subjects made records of symptoms and were also interviewed about pain/discomfort by a blinded examiner. After 12 weeks the teeth were extracted, prepared and subjected to light microscopic examination in which the inflammation and newly formed hard tissue in the pulp were analysed. Immunohistochemistry was performed using affinity-purified rabbit anti-EMD polyclonal antibodies. RESULTS: Postoperative symptoms were less frequent in the EMDgel-treated than in the calcium hydroxide-treated teeth, especially during the first six weeks. In the EMDgel-treated teeth, new tissue partly filled the space initially occupied by the gel and hard tissue was formed alongside the exposed dentine surfaces and in patches in the adjacent pulp tissue. EMD was detected in the areas where new hard tissue had been formed. The wound area of the EMDgel-treated teeth exhibited inflammation in the majority of the teeth whereas less inflammation was seen in the calcium hydroxide-treated teeth where the hard tissue was formed as a bridge. CONCLUSIONS: In the EMDgel-treated teeth, postoperative symptoms were less frequent and the amount and pattern of hard tissue formation were markedly different than in the teeth treated with calcium hydroxide. However, the operative procedure and the formulation with EMD in a PGA vehicle do not seem to be effective for the formation of a hard tissue barrier.     

Dentinogenic Responses after Direct Pulp Capping of Miniature Swine Teeth with Biodentine

Introduction

The aim of this study was to evaluate pulpal responses after experimental direct pulp capping of mechanically exposed teeth with a new calcium silicate–based dentin replacement material.

Methods

Thirty-four anterior and posterior teeth of 3 miniature swine were used. Class V or I cavities were prepared on the buccal or occlusal surfaces, respectively. Pulpal exposures were further performed using a round carbide bur 0.8 mm in diameter. Exposures were treated with white MTA Angelus (Angelus, Londrina, PR, Brazil) or Biodentine (Septodont, Saint Maur des Fosses, France), and the cavities were further restored with Biodentine. The pulpal tissue responses were histologically assessed at postoperative periods of 3 and 8 weeks. Data were statistically analyzed using the Kruskal Wallis and the Mann-Whitney U tests.

Results

Inflammatory infiltration or pulp tissue necrosis was not found in any of the specimens. All teeth showed mineralized matrix formation in the form of a complete hard tissue bridge composed of osteodentin or osteodentin followed by a discontinuous or continuous reparative dentin zone. A significantly higher thickness of the hard tissue bridge was found in the group of teeth treated with Biodentine at both 3 and 8 weeks. A number of teeth, which were under root development at the onset of the experimental procedures, exhibited ectopic pulp calcification.

Conclusions

The application of both calcium silicate–based materials in direct contact with the mechanically exposed pulp of healthy miniature swine teeth led to pulp repair with complete hard tissue bridge formation. The thickness of hard tissue bridges was significantly higher after pulp capping with Biodentine.     

The dentinogenic effect of mineral trioxide aggregate (MTA) in short-term capping experiments

AIM: The objective of the present experiment was to study the early pulpal cell response and the onset of reparative dentine formation after capping application of MTA in mechanically exposed pulps. METHODOLOGY: Thirty-three teeth from three dogs, 12-18 months of age were mechanically exposed via class V cavities. Light pressure was applied to control haemorrhage. ProRoot MTA (Dentsply Simfra, Paris) was placed at the exposure site and light pressure was applied with a wet cotton pellet. The cavities were restored with amalgam and the pulpal tissue reactions were assessed by light and electron microscopy (transmission and scanning) after healing intervals of 1, 2 or 3 weeks. RESULTS: A homogenous zone of crystalline structures was initially found along the pulp-MTA interface, whilst pulpal cells showing changes in their cytological and functional state were arranged in close proximity to the crystals. Deposition of hard tissue of osteotypic form was found in all teeth in direct contact with the capping material and the associated crystalline structures. Formation of reparative dentine (tubular matrix formation in a polar predentine-like pattern by elongated polarized cells) was consistently related to a firm osteodentinal zone. CONCLUSIONS: The present experiments indicate that MTA is an effective pulp-capping material, able to stimulate reparative dentine formation by the stereotypic defensive mechanism of early pulpal wound healing.     

Is hard tissue formation in the dental pulp after the death of the primary odontoblasts a regenerative or a reparative process?

Objectives

Conceptually, two types of tertiary dentine may be produced in response to caries and environmental irritations: “reactionary dentine” that is secreted by existing primary odontoblasts and “reparative dentine”, formed after the death of the odontoblasts by proliferation and differentiation of progenitor cells into odontoblast-like cells. Because histologic evidence for tubular dentine generated by newly differentiated odontoblast-like cells is lacking in human teeth, the present study examined pulpal cellular changes associated with caries/restorations, in the presence or absence of pulpal exposures.

Methods

Ninety-six extracted human teeth were histologically processed and serial sectioned for light microscopy: 65 contained untreated enamel/dentine caries; 20 were heavily restored and 11 had carious exposures managed by direct pulp-capping.

Results

Sparsely distributed, irregularly arranged dentinal tubules were identified from the tertiary dentine formed in teeth with unexposed medium/deep caries and in restored teeth; those tubules were continuous with the tubules of secondary dentine; in some cases, tubules were absent. The palisade odontoblast layer was reduced to a single layer of flattened cells. In direct pulp-capping of pulp exposures, the defects were repaired by the deposition of an amorphous dystrophic calcified tissue that resembled pulp stones more than dentine, sometimes entrapping pulpal remnants. This atubular hard tissue was lined by fibroblasts and collagen fibrils.

Conclusions

Histological evidence from the present study indicates that reparative dentinogenesis cannot be considered as a regenerative process since the so-formed hard tissue lacks tubular features characteristic of genuine dentine. Rather, this process represents a repair response that produces calcified scar tissues by pulpal fibroblasts.

Clinical significance

Formation of hard tissue in the dental pulp after the death of the primary odontoblasts has often been regarded by clinicians as regeneration of dentine. If the objective of the clinical procedures involved is to induce healing, reduce dentine hypersensitivity, or minimise future bacteria exposure, such procedures may be regarded as clinical success. However, current clinical treatment procedures are not adept at regenerating physiological dentne because the tissues formed in the dental pulp are more likely the result of repair responses via the formation of calcified scar tissues.     

Pulpal responses following direct pulp capping of healthy dog teeth with dentine adhesive systems

OBJECTIVE: The aim of the present study was to evaluate the pulpal responses following direct pulp capping of mechanically exposed teeth with new dentine adhesive systems, in the preclinical model of dog teeth. METHODS: Class V cavities (approximately 2.50 mm wide, 3.00 mm long, 1.5-2.0 mm deep) were prepared on the buccal surface of permanent maxillary and mandibulary molars, two rooted premolars, canines and third incisors. The cavities were assigned to five experimental groups, representing one control group treated with a Ca(OH)2-based material and four experimental groups where the adhesive systems Clearfil SE Bond, Prompt-L-Pop, Etch & Prime 3.0 and Single Bond were tested. The pulpal tissue responses to dentine adhesives were assessed at post-operative periods of 7, 21, 65 days. RESULTS: Variable responses were recorded, which were characterized by moderate to severe inflammatory reactions, progressive extension of tissue necrosis with time and total absence of continuous hard tissue bridge formation after pulp capping with each of the four adhesive systems. Application of a Ca(OH)2-based material was characterized by inflammatory cell infiltration, limited tissue necrosis as well as partial to complete hard tissue bridging. CONCLUSIONS: It seems evident that application of dentine adhesive systems in direct contact with the mechanically exposed pulp of healthy dog teeth cannot lead to acceptable repair of the dentine-pulp complex e.g. wound healing with tertiary dentine bridge formation.     

Dentine-pulp tissue engineering in miniature swine teeth by set calcium silicate containing bioactive molecules

Objective: The present study aims to investigate whether reparative dentinogenesis could be guided at central pulpal sites or at a distance from the amputated pulp of miniature pig teeth, by using set calcium silicate-based carriers containing human recombinant bioactive molecules.DesignPulp exposures were performed in 72 permanent teeth of 4 healthy miniature swine. The teeth were capped with pre-manufactured implants of set calcium silicate-based material containing BMP-7, TGFβ1 or WnT-1, for 3 weeks. Conical-shaped intrapulpal implants were exposed in the central pulp core, while disc-shaped extrapulpal implants were placed at a distance from the amputated pulp. Implants without bioactive molecules were used as controls. Thickness and forms of new matrix mineralized deposition were assessed histologically at post-operative periods of 3 weeks by light microscopy.ResultsIntrapulpal applications: Calcified structures composed of osteodentine were found in contact with the BMP-7 implants. An inhomogeneous calcified tissue matrix was found around the WnT-1 carriers. A two-zone calcified structure composed of osteodentine and a thicker tubular matrix zone was seen at the TGFβ1 carrier-pulp interface. Extrapulpal applications: The space between WnT-1 implants and pulp periphery had been invaded by soft tissue with traces of calcified foci. Thick calcified structures composed of osteodentine were found surrounding pulp exposure sites in response to application of BMP-7. Spindle-shaped cells associated with atubular calcified matrix or elongated polarized cells associated with tubular dentine-like matrix were found along the cut dentinal walls of the TGFβ1 group.ConclusionThe present experiments indicated that set calcium silicate could be used as carrier for biologically active molecules. TGFβ1 was shown to be an effective bioactive molecule in guiding tertiary dentine formation.     

Effects of a new antibacterial adhesive on the repair capacity of the pulp-dentine complex in infected teeth

AIM: To evaluate the effects of a self-etching/priming adhesive system, containing the antibacterial monomer 12-methacryloyloxy-dodecylpyridinium bromide (MDPB), on the repair capacity of the pulp-dentine complex in infected cavities in dog's teeth. METHODOLOGY: Class V cavities with a residual dentine thickness ranging from 0.3-0.8 mm were prepared on the buccal surface of permanent teeth in four dogs. Pulpal exposures were performed in half of the cavities. Millipore filters that had been incubated for 3 h in a 10(5) milky suspension of a-streptococci were placed in the cavities, which were then filled temporarily. After 24 h, the filters were removed and both the exposed and non-exposed cavities were washed with sterile saline and assigned to four groups which were treated with either the experimental antibacterial adhesive system, or Clearfil SE bond, Dycal and Teflon discs. Stereotype connective tissue reactions (inflammatory cell response and/or tissue necrosis) and pulp-specific reparative tissue responses (reduction of odontoblasts and tertiary dentine formation) were assessed at post-operative periods of 4 and 8 weeks. RESULTS: Neither severe inflammation nor tissue necrosis was observed, either in the dentinal cavities or pulpal exposures treated with the self-etch adhesive containing MDPB. Rates of tertiary dentine formation in infected dentinal cavities treated with this system were comparable with those observed after dentine treatment with the Ca(OH)2-based material. Dentinal bridging was not seen in pulpal exposures treated with the experimental adhesive. CONCLUSIONS: The new antibacterial adhesive system maintained pulp vitality and primary odontoblastic function in infected nonexposed and exposed cavities but interfered with reparative dentine formation in infected pulpal exposures.     

Wound healing process of injured pulp tissues with emdogain gel

This study aimed to investigate the wound healing process of injured pulp tissues with Emdogain gel (EMD). Pulpotomy was performed for the first molars of the mandibles in rats. EMD or Vitapex (VIT)-containing calcium hydroxide was applied to the exposed pulp tissues. The treated teeth were extracted after 7, 14, and 28 days and prepared for histologic examination. In the VIT-treated group, the number of interleukin-1 beta (IL-1 beta)-expressing macrophages initially increased, followed by that of transforming growth factor-beta1 (TGF-beta1)-expressing macrophages. The number of cells expressing bone morphogenetic proteins (BMPs) gradually increased with reparative dentin formation. Meanwhile, in the EMD-treated group, cells expressing IL-1 beta or TGF-beta1 were few. However, the number of BMP-expressing cells, partly macrophages, increased in the early phase, and large amounts of reparative dentin were observed. This study demonstrated that different healing processes existed for EMD and VIT. BMP-expressing macrophages might play important roles in reparative dentin formation.     

The mechanism of pulpal wound healing

The favourable response of exposed pulp tissue against a variety of materials used for pulp capping in experimental conditions, as observed by hard tissue (reparative dentine) formation, demonstrates an intrinsic capacity of pulp tissue for healing. However, in the clinical situation, in which a pulpal exposure is usually accompanied by a long-term external irritation with the subsequent long-term inflammatory response to that irritation, the outcome of pulp capping procedures is not as predictable. While some of the factors related to the defensive reactions and healing after pulp exposure and capping procedures are well understood, the mechanisms and importance of others remain less well-known. Understanding the mechanisms regulating the spread of inflammation and necrosis in pulp tissue, and the factors regulating healing after closure of the wound, would facilitate the development of new and better treatment procedures with more predictable outcomes. In this review, some of the aspects considered to be important in pulpal wound healing are discussed.     

生物陶瓷材料iRoot BP Plus对小型猪修复性牙本质形成影响的实验研究

目的 应用小型猪实验动物模型评价iRoot BP Plus直接盖髓后修复性牙本质桥形成的情况以及牙髓的生物学反应.方法 选取4只18月龄小型猪前磨牙26颗,制备直径为2 mm穿髓孔,随机分3组:氢氧化钙组、MTA组和iRoot BP Plus组,进行直接盖髓.术后8周,组织病理学观察.结果 MTA组和iRoot BP Plus组均可以形成具有天然牙本质小管样结构及极性的成牙本质细胞层的钙桥.与MTA组相比,iRoot BP Plus组形成的钙桥质地较为均匀连续,牙髓组织炎症反应较轻,髓腔未见不规则钙化.氢氧化钙组表现钙桥较为疏松,冠部牙髓组织坏死,根髓可见不同程度的炎症反应,根管壁出现不规则钙化.结论 iRoot BP Plus和MTA盖髓明显优于传统的氢氧化钙.iRoot BP Plus在盖髓术中表现了良好的生物学特性.     

An immunocytochemical study of the morphological reaction of nerves containing calcitonin gene-related peptide to microabscess formation and healing in rat molars

Pulpal inflammation was induced by cutting a class V cavity to within 0.1-0.3 mm of the pulp on the mesial aspect of maxillary and mandibular first molars at the cervical line. The exposed dentine was briefly acid-etched and left open to the mouth until the animals were killed. Histological examination of teeth 4 days after injury showed microabscesses, blood vessel dilation and increased numbers of terminal nerve sprouts around the lesion and in radicular pulp and dentine. Specimens at 7, 11, 21 and 35 days after injury showed progressive healing of the lesions with the formation of reparative dentine and a coincident return to a normal patterns of innervation in the remaining pulp. Thus pulpal nerves are not static structures, but rather are capable of rapid change in response to inflammation. The morphological association of CGRP-immunoreactive nerve fibres with the edges of the healing lesions and with zones of reparative dentine suggests a role for these fibres and for the neuropeptide CGRP in the healing response of pulpal tissue.     

A (3H)-proline autoradiographic study of dentine bridge formation in transplanted mouse molar teeth.

A dentine bridge invariably forms across the cervical pulp of transplanted mouse molar isografts. Autoradiographic study demonstrated that bridge formation occurred in two phases. Firstly during post-operative degeneration cellular dentine was formed by non-polar secretion from degenerating cells. Cellular dentine formation was also observed in allografts. Secondly, as isografts recovered, tubular secondary dentine was formed by cuboid pre-odonto-blasts and then by fully differentiated odontoblasts. Similarities were noted between reparative dentinogenesis in transplanted teeth and in teeth in situ. These similarities suggest that reparative dentinogenesis is an identical process irrespective of the stimulus for formation and that the capacity for repair of transplanted teeth resides within the donor tissue. These experiments also demonstrate the remarkable inherent healing capacity of the dental pulp.     

The response of four calcium hydroxides on monkey pulps

Abstract Dentinal bridge formation and pulpal responses of four calcium hydroxide materials, pulp capping medicaments, MFC®, Experimental MFC-12, Dycal® and Pulpdent®, were evaluated in primary and permanent monkey teeth. A total of 60 primary and 60 permanent teeth were used with each material placed in a Class V cavity exposure in Rhesus monkey teeth. The materials were placed on the exposed pulp tissue and were histologically evaluated at 3 days, 5 weeks and 8 weeks. After perfusion the teeth were processed using routine histological procedures. The 3-day pulpal responses in both primary and permanent teeth were moderate, characterized by disruption of the pulpal tissue directly beneath the exposure site and a zone of acute inflammation and hemorrhage in the underlying pulp. The 5-week response showed histological differences between the four medicaments, with Dycal producing the least amount of pulpal irritation with reparative dentin bridges occurring in 50% of the permanent teeth. Experimental MFC-12 stimulated one reparative dentin bridge, while Pulpdent and MFC showed no evidence of bridge formation. Pulpal responses to Dycal were moderate and moderate to severe for the other calcium hydroxide compounds. No reparative dentin bridges were seen in the primary teeth at 5 weeks with any of the materials, and the pulpal responses were of a moderate degree at that time. Eight-week responses were similar to the 5-week responses. Dycal provoked a slight to moderate pulpal response with 50% success at bridging. Experimental MFC-12 initiated pulpal responses in the moderate to severe range with some bridging evident. Pulpdent incited moderate to severe histological responses with three teeth demonstrating bridge formation, and MFC provoked severe pulpal responses with no bridging. Primary teeth showed some bridging for all compounds except those treated with MFC, in which no evidence of bridging occurred, and moderate to severe pulpal responses were present.     

胶原蛋白保存活髓的实验研究

目的　探讨胶原在修复性牙本质形成过程中的作用。方法　用Ⅰ型胶原作盖髓剂为小型猪牙盖髓 ,术后 2、4和 13周取实验牙 ,对其组织病理学改变进行光镜和透射电镜的观察。结果胶原盖髓后 2周 ,有牙本质团块形成 ,电镜下可见在基质中出现多突的成牙本质细胞样细胞。盖髓后4周 ,大部标本可见形成牙本质桥 ,电镜下可见在基质中出现退变的细胞。盖髓后 13周 ,大部标本形成牙本质桥 ,桥表层为骨样牙本质 ,深层为管状牙本质 ,电镜下可见致密的基质 ,内含紊乱的小管。结论　胶原可促进修复性牙本质形成 ,是较好的盖髓材料     

Hard tissue barrier formation in pulpotomized monkey teeth capped with cyanoacrylate or calcium hydroxide for 10 and 60 minutes

Monkey incisor teeth were pulpotomized in groups of 10. After physiological hemostasis, the pulps of group I were covered with isobutyl cyanoacrylate, and those of groups II and III with calcium hydroxide for 10 and 60 minutes, respectively, whereafter this compound was washed away and the wound surfaces covered with Teflon. In group IV, calcium hydroxide was used as a positive control, and Teflon as a negative control in group V. The animals were killed after 12 weeks and the teeth removed in tissue blocks. The material was processed and evaluated histologically with respect to location and continuity of a hard tissue barrier, type of newly formed hard tissue, state of the pulp, and presence of stainable bacteria in the coronal cavity. Seven of nine teeth in group I showed a hard tissue barrier. The corresponding figure for group II was eight out of 10 teeth. All teeth in groups III and IV had a barrier. The incidence of a continuous barrier increased from group I through group IV, as did the incidence of its location below the level of the original wound surface. The condition of the pulp was related to the presence of bacteria and the continuity of the barrier to the presence of inflammation. There was no bridging in group V. The results support the theory that a low-grade irritation is responsible for the formation of a hard tissue barrier in exposed pulps.     

Histological evaluation of microfilled and conventional composite resins on monkey dental pulps

Summary. The pulpal responses to two micro-filled composite resins and a conventional composite resin were investigated in adult rhesus monkey teeth. All materials were randomly placed in unetched and unlined class V buccal cavity preparations. A total of 90 teeth were used in the study. Each material was evaluated at 3 days, 5 weeks and 8 weeks. Following perfusion, the teeth were prepared using routine histological procedures. The results indicated that the pulpal response to the microfilled and conventional composite resins were similar for all time periods, characterized by an initial slight to moderate response at 3 days, followed at 5 and 8 weeks by a zero to slight response with evidence of reparative dentine formation. Brown and Brenn staining for bacteria indicated positive staining reactions along the cavity wails of all teeth for all materials at each time period.     

碱性成纤维因子用于犬牙盖髓剂的实验研究

目的探讨碱性成纤维因子(bFGF)对犬牙髓损伤修复的影响。方法选取健康英国小猎兔犬牙齿64颗,分为bFGF盖髓组、Dycal盖髓组及ZOE盖髓组。进行直接盖髓术,观察术后14天和28天修复性牙本质形成及牙髓组织学变化。免疫组化检测骨形成蛋白表达情况。结果术后14天:实验组及阳性对照组有纤维性基质形成,无牙本质桥形成;术后28天:实验组及阳性对照组有骨样牙本质桥、管状牙本质形成,阴性对照组无牙本质桥形成。结论bFGF在体内能够有效诱导牙髓细胞分化,形成修复性牙本质。     

牙本质非胶原蛋白诱导牙髓-牙本质复合体反应的动物实验观察

目的：观察提取的猪牙本质非胶原蛋白对修复性牙本质形成的诱导活性。方法：用提取的猪EDTA可溶性牙本质非胶原蛋白作盖髓剂,对Wistar大鼠的健康第一磨牙进行直接盖髓实验,采用氢氧化钙（Dycal）和空白组为对照,通过组织学实验观察牙髓-牙本质复合体的反应。结果：盖髓术后7 d,各组之间软、硬组织反应的差异无统计学意义。术后14 d,NCPs组和Dycal组的修复反应均明显优于空白对照组（P〈0.01）,且NCPs组对牙髓的刺激小于Dycal组（P〈0.05）。结论：NCPs对牙髓刺激性小,可以诱导牙髓细胞分化为成牙本质细胞样细胞,形成修复性牙本质,其诱导活性至少与常规盖髓剂相当。     

光敏黏接剂盖髓后牙髓的组织病理反应

目的观察应用3种光敏黏接剂直接盖髓后,兔牙髓的反应。方法兔前臼齿及臼齿72颗,分为4组,制备Ⅰ类洞机械穿髓,实验组3组(Excite,Prime & Bond NT,XenoⅢ),Dycal为对照,光敏树脂(SureFil)充填。于第7、14、21天每组拔除6颗牙齿,常规脱钙切片,镜下观察充血反应、炎细胞浸润、纤维化程度、牙本质桥形成、修复性牙本质形成、细菌污染等情况。结果所有实验牙齿都有牙本质桥形成,修复性牙本质封闭穿髓孔。同一时期内,兔牙髓对不同盖髓剂的反应无显著性差异。除对照组外,同种黏接剂在不同时期内对牙髓的影响无显著性差异。结论此3种黏接剂对兔牙髓具有良好的生物相容性,并能促进修复性牙本质生成。