Effect of eugenol on respiration and division in human pulp, mouse fibroblasts, and liver cells in vitro

Eugenol depressed cell respiration in homogenates of human dental pulp and in mouse fibroblast monolayers. The depression was concentration-dependent, with a threshold at about 10(-4)M and a maximum at 10(-3)M in both preparations. Onset of the depression appeared to be rapid. The effects of variation in both duration and concentration of eugenol exposure on subsequent uptake of 3H-thymidine were examined in mouse fibroblast monolayers and human pulp explants. Fibroblasts survived short-term (up to 12 hr) exposure to 10(-3)M eugenol or less, but died after exposure to 10(-3)M for one day or more. The cells survived exposure to 10(-4)M for ten days, the longest period examined. Human pulp maintained in tissue culture medium showed similar eugenol susceptibility. Analysis of these data, when coupled with those of previous studies on eugenol release from ZOE and diffusion through dentin, gives strong support for the concepts that: the blandness of ZOE when applied to intact dentin is due to eugenol reaching the pulp in sub-toxic concentrations, and the irritant effect of ZOE when applied directly to soft tissue is due to the development of concentrations of eugenol in tissue adjacent to ZOE sufficient to inhibit respiration and thus kill cells.     

In vivo and in vitro effects of zinc oxide-eugenol (ZOE) on biosynthesis of cyclo-oxygenase products in rat dental pulp

To determine the in vivo effects of a zinc oxide-eugenol mixture (ZOE) on the cyclo-oxygenase system in dental pulp, we used radioimmunoassay to measure the levels of prostaglandin E2 (PGE2), 13,14-dihydro-15-keto-PG (DHK-PG), thromboxane B2 (TXB2), and 6-keto-PGF1 alpha in the dental pulp of rats. When the dental pulp was irritated by a hole made in the dentin of the mandibular incisors without use of any coolants, the levels of these cyclo-oxygenase products in the pulp were increased to, respectively, 2.8, 1.7, 10.0, and 2.6 times those in the normal pulp at six hr after treatment. In contrast, these increases in cyclo-oxygenase products disappeared immediately when the artificial cavity in the dentin was filled with ZOE (P/L; 1 g/0.25 mL), but were not altered when the cavity was filled with zinc oxidewater (ZOW, 1 g/1.5 mL). Most of the eugenol portion of ZOE was released into the pulp within two hr after the cavity was filled with ZOE. The maximal eugenol content was 35 pmol per mg of pulp. Furthermore, when the cavity was filled either with ZOE or by the addition of 10 mumol/L eugenol to the pulp homogenate, biosynthesis of 14C-6-keto-PGF1 alpha, PGF2 alpha, and PGE2 from 14C-arachidonic acid in the homogenate was inhibited. These results suggest that eugenol released from ZOE in the cavity prepared in the dentin inhibited the biosynthesis of cyclo-oxygenase products during pulp irritation.     

An analysis of the release and the diffusion through dentin of eugenol from zinc oxide-eugenol mixtures

Tritium-labeled eugenol was released from mixtures of zinc oxide eugenol (ZOE) into aqueous solution at rates which declined exponentially with time, and which were directly proportional to the liquid-powder ratio. The release pattern was consistent with a model of progressive hydrolysis of zinc eugenolate in a limited-thickness ZOE surface layer. Intervening dentin had a profound effect on this pattern of release. In human teeth in vitro containing ZOE as a base or temporary filling, peak eugenol release at the pulpal surface of dentin was of the order of a thousand-fold less than that at the salivary surface. In such teeth, eugenol reached concentrations in excess of 10(-2) M in dentin just beneath ZOE, and 10(-4) M or less adjacent to the pulp space. Both pulpal outflow and dentin concentrations of eugenol remained relatively constant for more than a week, unlike release into aqueous solution. While these data were derived from studies on human teeth in vitro, they give a strong indication of probable events in vivo, and appear to provide a basis for the explanation of the paradox of the therapeutic and toxic actions of ZOE.     

Immunomodulatory/anti-inflammatory effect of ZOE-based dental materials

Objective

The study assessed the cytotoxicity and immunomodulatory/anti-inflammatory effect of extract from zinc oxide–eugenol (ZOE)-based dental materials during setting using immortalized human dental pulp stem cells (IHDPSCs) and mouse bone marrow monocytes (IMBMMs), and identified the responsible extract component.

Cytotoxic effect of eugenol on the expression of molecular markers related to the osteogenic differentiation of human dental pulp cells

The cytotoxic effect of eugenol on the expression of molecular markers related to the osteogenic differentiation of human dental pulp cells such as collagen synthesis and the expression of two osteogenesis-related genes, alkaline phosphatase (ALP) and bone sialoprotein (BSP), was studied using human dental pulp cells (D824 cells). Cellular growth and survival were decreased by treatment of cells with eugenol in a concentration-dependent manner. The incorporation rate of [³H] proline into the acid-insoluble fraction and the synthesis of type I–V collagens were also reduced by treatment of cells with eugenol in a concentration-dependent fashion. The mRNA expression of ALP was scarcely affected in cells exposed to eugenol, whereas the mRNA and protein expression of BSP was down-regulated depending on the concentrations of eugenol. The results suggest that because collagen synthesis and BSP expression play a critical role in hard tissue formation, eugenol used for endodontic treatment may give rise to cytotoxic effects to the normal function of stem cells reported to exist in human dental pulp tissue and periodontal ligament.     

美松糊剂与氧化锌丁香油糊剂的临床疗效观察

目的：比较美松糊剂和传统的氧化锌丁香油糊剂（ZOE）根充后的效果。方法：选择96位病人双侧均有牙髓病变的牙齿192颗,且两侧病牙为相对应的牙齿或为相对应牙齿的邻牙,采用自身对照的方法,在根管充填时,一侧牙齿用美松糊剂加牙胶尖充填,另一侧用ZOE加牙胶尖充填根管,通过观察根充术后牙齿疼痛情况及持续时间来比较两组的根充效果。结果：美松糊剂组术后轻、中和重度疼痛的牙齿分别为85、10、1颗,而ZOE组分别为34、50、12颗,两组经χ2检验,P〈0.05;术后疼痛时间3、5、7d以内的美松糊剂组牙齿分别为91、5、0颗,而ZOE组分别为37、43、16颗,两组比较,亦为P〈0.05。结论：美松糊剂根充的效果要明显优于ZOE。     

Inhibition of lipoxygenase of rat dental pulp and human platelets by phenolic dental medicaments

The effects of phenolic dental medicaments on lipoxygenase activities of rat dental pulp and human platelets were studied. The major product derived from [14C] arachidonic acid by the homogenate of rat dental pulp was 12-HETE (15-HETE). Eugenol and p-chlorophenol dose-dependently inhibited HETEs formation. The IC50 values of eugenol and p-chlorophenol were 0.62 and 0.34 mM respectively. The concentrations of these compounds that inhibit lipoxygenase were similar to those required to inhibit cyclooxygenase. These compounds also inhibited 12-lipoxygenase of human platelets with a similar range of concentrations. The results show that phenolic dental medicaments inhibit pulpal and platelet lipoxygenase. Thus, inhibition of arachidonic acid metabolism by phenolic dental medicaments via the lipoxygenase pathway may be involved in the analgesic and anti-inflammatory effects of the medicaments in endodontic therapy.     

The in vitro biological evaluation of dental cements using elution and binding by bovine serum albumin (author's transl)]

In order to evaluate in vitro biological properties of dental cements sixteen different cements including zinc oxide eugenol (ZOE), EBA, resin, polycarboxylate, glass ionomer cement and calcium hydroxide base material were tested regarding elution and binding by bovine serum albumin (BSA). The persistency of elution over long time after subsequent transfer to fresh water was calculated at 210 nm absorbance with ultra violet spectrometer. Also the eluates obtained were analyzed by high performance liquid chromatograpy. The continuous leaching of eugenol from ZOE cement was observed. Binding of eluates from cement to BSA was evaluated spectrophotometrically by utilizing the competition with 2-(4' hydroxyphenylazo) benzoic acid (HABA). EBA cement showed the highest binding ability by BSA because of the leaching o-ethoxybenzoic acid from this cement. The relevance of protein and pulp toxicity is discussed.     

Clinical and radiographic evaluation of vital pulp therapy in open apex teeth with MTA and ZOE

The purpose of this study was to report the success rate of using mineral trioxide aggregate (MTA) and zinc oxide eugenol (ZOE) as vital pulp therapy agents in immature permanent teeth with carious or traumatic pulp exposure. Subjects were children with permanent teeth requiring pulpotomy (apexogenesis) and without systemic diseases. Both ZOE and MTA treatments as pulpotomy agents showed clinical and radiographic success in immature permanent teeth. Although MTA was more successful, it is more expensive, and dentin bridges may develop over canal orifices, complicating future root canal therapy.     

不同清洗方式对ZOE水门汀污染车针清洗效果的研究

目的 针对口腔临床表面粗糙的小器械,使用中黏附氧化锌丁香酚(ZOE)水门汀后难以有效清除的问题进行改进。方法 在TR-13金刚砂车针表面负载ZOE水门汀模拟临床使用后ZOE水门汀污染。以不同清洗方式处理,通过称重残余质量、扫描电镜观察处理后车针表面情况以及短时间内抑菌效果分析各实验组清洗效果。结果 对比清水浸泡组、多酶浸泡组、保湿剂浸泡组、丁香酚浸泡组结果,丁香酚浸泡后ZOE水门汀清除效果显著好于其他实验组。若丁香酚直接超声清洗,效果无差异,但抑菌效果较差。使用丁香酚超声清洗后再经多酶浸泡,抑菌效果明显改善。结论 应用丁香酚超声清洗ZOE水门汀污染器械,配合多酶清洗液浸泡,可有效清除器械表面黏附的ZOE水门汀同时抑制病原菌的增殖。该清洗方式简便易行、效果显著,适于临床推广使用。     

Assessment of coronal microleakage in intermediately restored endodontic access cavities

OBJECTIVE: The purpose of this in vitro study was to evaluate the coronal microleakage in endodontic access cavities restored with Kalzinol (zinc oxide eugenol, De Trey, Dentsply Dental Products of India Ltd) and a zinc oxide eugenol (ZOE) intermediate restorative material at different intervals. STUDY DESIGN: Restored access cavities were immersed in 2% freshly prepared methylene blue dye, and dye penetration was evaluated at 1-, 2-, 4-, and 7-day intervals. RESULTS: ZOE cement displayed dye penetration throughout the complete depth of the restoration, reaching the pulp chamber by the second day, whereas Kalzinol produced leakage reaching the pulp chamber on the fourth day. CONCLUSION: Results indicated that none of the ZOE formulations tested could predictably produce a fluid-tight seal even up to the fourth day. We therefore recommend early replacement of these restorations during and after endodontic treatment to produce a better prognosis.     

The effectiveness of mineral trioxide aggregate, calcium hydroxide and formocresol for pulpotomies in primary teeth

Aim To compare the effectiveness of mineral trioxide aggregate (MTA), calcium hydroxide (CH) and formocresol (FC) as pulp dressing agents in carious primary teeth. Methodology Forty‐five primary mandibular molars with dental caries in 23 children [AUTHOR QUERY: How many children?] between 5 and 9 years old were treated by a conventional pulpotomy technique. The teeth were randomly assigned to the experimental (CH or MTA) or control (FC) groups. After coronal pulp removal and haemostasis, remaining pulp tissue was covered with MTA paste or CH powder in the experimental groups. In the control group, diluted FC was placed with a cotton pellet over the pulp tissue for 5 min and removed; the pulp tissue was then covered with zinc oxide–eugenol (ZOE) paste. All teeth were restored with reinforced ZOE base and resin modified glass–ionomer cement. Clinical and radiographic successes and failures were recorded at 3, 6, 12, 18 and 24 month follow‐up. Results Forty‐three teeth were available for follow‐up. In the FC and MTA groups, 100% of the available teeth were clinically and radiographically successful at all follow‐up appointments; dentine bridge formation could be detected in 29% of the teeth treated with MTA. In the CH group, 64% of the teeth presented clinical and radiographic failures detected throughout the follow‐up period, and internal resorption was a frequent radiographic finding. Conclusions Mineral trioxide aggregate was superior to CH and equally as effective as FC as a pulpotomy dressing in primary mandibular molars. Internal resorption was the most common radiographic finding up to 24 month after pulpotomies performed with CH.     

Zirconia-incorporated zinc oxide eugenol has improved mechanical properties and cytocompatibility with human dental pulp stem cells

Objective

Zinc oxide eugenol (ZOE) is widely used as a therapeutic dental restorative material. However, ZOE has poor mechanical properties and high cytotoxicity toward human dental pulp stem cells (hDPSCs) due to the release of Zn ions. In this study, zirconia-incorporated ZOE (ZZrOE) was developed to reduce the cytotoxicity and improve the mechanical properties of ZOE with sustained therapeutic effects on inflamed hDPSCs in terms of inflammatory gene expression levels compared with those of the original material.

Temporary zinc oxide–eugenol cement: eugenol quantity in dentin and bond strength of resin composite

Uptake of eugenol from eugenol‐containing temporary materials may reduce the adhesion of subsequent resin‐based restorations. This study investigated the effect of duration of exposure to zinc oxide–eugenol (ZOE) cement on the quantity of eugenol retained in dentin and on the microtensile bond strength (μTBS) of the resin composite. The ZOE cement (IRM Caps) was applied onto the dentin of human molars (21 per group) for 1, 7, or 28 d. One half of each molar was used to determine the quantity of eugenol (by spectrofluorimetry) and the other half was used for μTBS testing. The ZOE‐exposed dentin was treated with either OptiBond FL using phosphoric acid (H₃PO₄) or with Gluma Classic using ethylenediaminetetraacetic acid (EDTA) conditioning. One group without conditioning (for eugenol quantity) and two groups not exposed to ZOE (for eugenol quantity and μTBS testing) served as controls. The quantity of eugenol ranged between 0.33 and 2.9 nmol mg^?1 of dentin (median values). No effect of the duration of exposure to ZOE was found. Conditioning with H₃PO₄ or EDTA significantly reduced the quantity of eugenol in dentin. Nevertheless, for OptiBond FL, exposure to ZOE significantly decreased the μTBS, regardless of the duration of exposure. For Gluma Classic, the μTBS decreased after exposure to ZOE for 7 and 28 d. OptiBond FL yielded a significantly higher μTBS than did Gluma Classic. Thus, ZOE should be avoided in cavities later to be restored with resin‐based materials.     

Eugenol: liberation from dental materials and effect on human diploid fibroblast cells

The amount of eugenol (4-allyl-2-methoxyphenol) released from four different dental materials immersed in phosphate buffer was measured by gas liquid chromatography. Maximal release of eugenol from zinc oxide-eugenol cement (ZOE) and IRM® was attained within 5 h and corresponded to 5% and 4%, respectively, of the total amount of eugenol in each material. Both the rates and total amounts of eugenol released from Nobetec® and Opotow® were lower than for ZOE and IRM. Eugenol (0.67 mm) applied to growing cultures of human diploid fibroblasts reduced the number of cells recovered to a value which was 4%. of that found for control cultures which grew to form, monolayers. Confluent monolayers of ³H-uridine labeled cell cultures which were incubated for 1 h in the presence of 4 mm eugenol lost approximately 100% of this cytoplasmic label, indicating total cell death.     

Pulpal response to a new light-activated fluoride releasing liner

The purpose of this study was to investigate the degree of pulp irritation of a newly developed light-activated fluoride-releasing adhesive resin liner using canine teeth compared to the amount caused by a negative control, zinc oxide eugenol cement (ZOE), and a positive control, silicate cement (silicate). In the cases of unexposed pulp, this experimental liner showed none, slight or moderate pulpal changes at 3 d postoperatively. At 30 and 90 d, no pulpal response to the experimental liner was detected in almost all cases. These findings were similar to the ZOE and better than the silicate. There was less evidence of pulpal irritation produced by the experimental liner. This material seems to be safe to the pulp under the conditions of this study.     

Next-generation biomaterials for dental pulp tissue immunomodulation

ObjectivesThe current standard for treating irreversibly damaged dental pulp is root canal therapy, which involves complete removal and debridement of the pulp space and filling with an inert biomaterial. A regenerative approach to treating diseased dental pulp may allow for complete healing of the native tooth structure and enhance the long-term outcome of once-necrotic teeth. The aim of this paper is, therefore, to highlight the current state of dental pulp tissue engineering and immunomodulatory biomaterials properties, identifying exciting opportunities for their synergy in developing next-generation biomaterials-driven technologies.MethodsAn overview of the inflammatory process focusing on immune responses of the dental pulp, followed by periapical and periodontal tissue inflammation are elaborated. Then, the most recent advances in treating infection-induced inflammatory oral diseases, focusing on biocompatible materials with immunomodulatory properties are discussed. Of note, we highlight some of the most used modifications in biomaterials’ surface, or content/drug incorporation focused on immunomodulation based on an extensive literature search over the last decade.ResultsWe provide the readers with a critical summary of recent advances in immunomodulation related to pulpal, periapical, and periodontal diseases while bringing light to tissue engineering strategies focusing on healing and regenerating multiple tissue types.SignificanceSignificant advances have been made in developing biomaterials that take advantage of the host’s immune system to guide a specific regenerative outcome. Biomaterials that efficiently and predictably modulate cells in the dental pulp complex hold significant clinical promise for improving standards of care compared to endodontic root canal therapy.     

A survey of primary tooth pulp therapy as taught in US dental schools and practiced by diplomates of the American Board Of Pediatric Dentistry

PURPOSE: The purpose of this study was to repeat a 1997 survey of current pulp therapy practice. METHODS: The directors of dental school predoctoral pediatric dentistry programs (N=56) and board certified pediatric dentists (N=1200) were surveyed in 2005. RESULTS: More dental schools (83%) taught indirect pulp therapy (IPT) compared to 1997. Significantly more used glass ionomer for IPT with most dental schools and diplomates not re-entering a tooth after IPT. Over 30% of schools and diplomates do direct pulp cops using glass ionomer. For pulpotomy, diluted formocresol usage decreased in dental schools (54%) while ferric sulfate significantly increased (24%) and full strength remained at 22%. Shorter placement of pulpotomy medication was noted and ZOE alone the preferred base. Pulpectomy was advocated by 85% of 2005 schools and diplomates with ZOE filler use decreasing while iodoform/calcium hydroxide filler use increasing. CONCLUSIONS: More pediatric dentists are using glass ionomer for IPT and direct pulp capping, and there was a trend away from the use of 1:5 diluted formocresol with more using ferric sulfate for pulpotomy. For pulpectomy, most use ZOE but iodoform pastes and calcium hydroxide have increased in usage since 1997 Disagreements continue concerning when to use certain pulp therapies and some directors and diplomates did not follow the AAPD guidelines.     

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。     

Effects of therapeutic and pulp protecting materials on nerve transmission in vitro

Effects of therapeutic and pulp protecting dental materials on nervous tissue were studied in an in vitro model utilizing the isolated left rat phrenic nerve. The nerve was placed in a buffer bath between two suction electrodes, one for electrical stimulation and one for recording. Evoked compound action potentials (cAP) were monitored in an oscilloscope. Fresh mixes of six commonly used pulp-dentin materials were placed in contact with the nerve, and the cAP registered. Formocresol, zinc oxide-eugenol (ZOE), Calasept and Dycal caused a complete depression of the nerve activity within 0.5 to 5 min of contact. The depression appeared irreversible with Formocresol and Calasept, reversible with Dycal, and reversible with ZOE when applied to nerves surrounded by adherent fatty tissue. De Trey Zinc and Durelon caused only a minor depression of the cAP within 30 min of contact.