Chapter 11 : Histopathological Evaluation of Combined Root Canal Filling: An Animal Study

Since the study of root canal filling combined with gutta-percha points and endodontic cement by Dixon and Rickert, many other studies have made use of radiographic evaluation. However, histopatholgical evaluations are infrequent and often incomplete in terms of findings. In this chapter we report the results of our examination using gutta-percha points and a new endodontic cement called KEZ with powder components: 40% zinc oxide, 20% calcium hydroxide, 20% iodoform, and 20% resin; and liquid components: 90. 5% eugenol, 9% resin and 0.5% setting agent. One hundred dog teeth were perforated using a rotary cutting instrument. The exposed pulp chamber was left opened for 30 days. Rotary reamers were used to perforate the infected root canals at the apical portion. They were cleaned with sodium hypochlorite and saline solution. Fifty canals were filled with combined gutta percha and KEZ. In the other fifty, no root canal filling was used and the teeth were restored with amalgam. Three months later the dogs were sacrificed and specimens for histopathological evaluation were prepared. Resuts were as follows. Root canals filled with a combination of guttapercha and KEZ manifested proper sealing of the apical apex, appropriate radiopacity, and reliable healing of the apical periodontal tissues. In unfilled root canals, no reparative change occurred. Moreover, when root canals were filled, alveolar bone regeneration, closure of the root apex and cicatrization of the periodontal tissue in deep layers occurred. In addition, sealing of the artificially-made apical foramen was observed in some cases. When canals were filled, both inflammatory cell infiltration and suppuration tended to decrease. Alveolar bone resorption and closure of the root apex occurred as a consequence of new cementum or bone deposition.Editor, Toshiyuki KawakamiLanguage Editor, David M Carlsonviii, 232 p. ill. (some col.

Chapter 10 : Histopathological Evaluation of Root Canal Filling Material Pastes: An Animal Study

To improve the paste used for root canal filling, the authors performed a histopathological study on 100 root canals from dogs of more than twelve months of age. The pulps were exposed under general anesthesia with the administration of pentobarbital sodium. The pulp chambers were left opened for one month and then enlargement and cleaning of the root canals were performed. The subjects were divided into three experimental groups: (A) 40 cases of root canals filled with a prepared paste called Vitapex, which contains calcium hydroxide, iodoform, silicone oil, and other substances (B) 30 cases of root canals filled with a paste called Calvital, a mixture of a powder containing calcium hydroxide, iodoform, guanofracin, and sulfathiazole, with a liquid containing propyleneglycol, distilled water and T-cain (C) 30 cases of unfilled root canals Only the pulp chambers were filled with cement bases and amalgam for all cases. After three months, the dogs were sacrificed and specimens were prepared for pathological examination. Radiographic examination was also carried out. The results are as follows. In most of the cases with root canal fillings containing Vitapex and Calvital, regeneration of alveolar bone and apical hard tissue as well as cicatrization of the periodontal membrane and the deep alveolar area were observed. Sealing of the perforated portion of the apex was observed less often. These two pastes proved to be clinically useful, whereas in cases in which no root canal filling was made, reparative process in the tissue of any kind was rarely observed. In many cases of Vitapex fillings and in some cases of Calvital fillings, regeneration of the alveolar bone was irregular and porous. Filling with either of the two pastes decreased the inflammation in the apical area. Three months after the experiment, radiopacity persisted in the group of cases in which Vitapex was used, while this persistence was less notable in cases filled with Calvital.Editor, Toshiyuki KawakamiLanguage Editor, David M Carlsonviii, 232 p. ill. (some col.

Chirality Induction in Bioorganometallic Conjugates

Considerable attention has been given to the research field of bioorganometallic chemistry, which is a hybrid chemistry field between biology and organometallic chemistry. The introduction of biomolecules, which have hydrogen bonding sites and chiral centers, into organometallic compounds is a promising strategy to construct chirality-organized bioorganometallic conjugates. This feature paper sketches an outline of induction of helical chirality into bioorganometallic conjugates by the control of a torsional twist of the organometallic moiety. Topics covered included control of the helical chirality of 1,n′-disubstituted ferrocene moieties in ferrocene-dipeptide conjugates, and the chirality induction of the Au(I)–Au(I) axis in the dinuclear organogold(I)-uracil conjugates

Chapter 4 : Injury and the Recovery Reaction due to the Penetration of Material into the Mandibular Canal

A root canal filling material paste, mainly made of calcium hydroxide and iodoform with the addition of silicone oil, was experimentally introduced into the mandibular canals of dogs. The tissue reactions to the paste were examined by radiography, histopathology, and electron microscopy. The examination results showed that the paste was phagocytosed by macrophages and, in general, was gradually resorbed by the passage of time. The paste was also found to cause heterotopic calcification and/or bone formation within the limited area of original penetration. The histopathological tissue changes of the alveolar nerve tissue were also examined. No injury-related histopathological change was observed as long as the injected paste did not contact alveolar nerve tissue, but tissue damage was observed at sites of direct contact. After removal of degenerated nerved debris by macrophages and Schwann cells, the persisting external membrane or “Schwann tubes” appeared to provide a scaffold for axonal regeneration and Schwann cell proliferation.Editor, Toshiyuki KawakamiLanguage Editor, David M Carlsonviii, 232 p. ill. (some col.

Analytical Electron Microscopic Study of Mineral Deposits in a Case of Calcionsis Universalis

Calcinosis universalis with dermatomyositis occurred in a 58-year-old woman. Tissues removed from the patient\u27s sublingual region were studied mainly by analytical electron microscopic methods. According to an elemental analysis using a wavelength dispersive X-ray spectroscope, most of the mineral deposits contained the elements sodium, phosphorus, calcium, rhenium, and some deposits also contained sulphur and magnesium. The elements sodium, sulphur, chlorine, and calcium were found in the stromal tissues of the material. Energy dispersive X-ray spectroscopy demonstrated that the analysis-peaks of phosphorus and calcium were higher in the mineral deposits than in the stromal tissues. The mineral deposits throughout the specimen were mainly composed of hydroxyapatite, judging from field-limited area electron diffraction and X-ray diffraction examinations

Chapter 12 : Histopathological Examination of a \u27Simultaneously folded\u27 Method with Paste and Combined Root Canal illing Methods in Dog Teeth

To improve the method of root canal filling, the authors performed a histopathological study using a novel system named the ‘simultaneously folded’ root canal filling method. This system calls for applying Vitapex paste near the area of the apical foramen followed by filling the remainder of the root canal by means of either the combination of gutta-percha point and KEZ endodontic cement (dry components: 40% zinc oxide, 20% calcium hydroxide, 20% iodoform and 20% rosin; liquid components: 90.5% eugenol 90.5%, 9.0% rosin and 0.5% setting agent) or Neodyne zinc-oxide eugenol cement. The authors compared the healing effects of this method with those resulting from a combined root canal filling method employing gutta-percha point and Neodyne endodontic cement. The root canals of 119 dog teeth were perforated by means of rotary cutting instruments. Pulp chambers were exposed and allowed to remain open for thirty days. Engine reamers were used to perforate the apical portions. They were cleaned with sodium hypochlorite and saline solutions. Fifty-one of the canals were filled using our ‘simultaneously folded’ technique with Vitapex, gutta-percha point and KEZ endodontic cement. Forty-two canals were filled using the \u27simultaneously folded\u27 technique with Vitapex, gutta-percha point and Neodyne. Twenty-six canals were filled using a combined root canal filling method with gutta-percha point and Neodyne. Three months later, the dogs were sacrificed and specimens were prepared for histopathological observation. Results showed that the ‘simultaneously folded’ root canal filling method resulted in a peculiar healing process featuring a cement barrier without ankylosis. Apparently, this method accelerated the closure of the apical foramen and regeneration of alveolar bone. Consequently, the \u27simultaneous folded\u27 root canal filling method is recommended for clinical application.Editor, Toshiyuki KawakamiLanguage Editor, David M Carlsonviii, 232 p. ill. (some col.

形態計測のためのメタノール・硝酸セルロースによる組織包埋法

Very recently we developed a new embedding medium, "Shiojirin-E", made chiefly of cellulose nitrate (Kawakami et al. 1995)^&;t;1\u272)>. During the course of its development, we noted that cellulose nitrate would be a very suitable embedding medium for morphometric analysis, especially because of its low and constant rate of contraction. But the highviscosity of this medium resulted in a very slow rate of infiltration. Therefore we sought to develop a new, better histological embedding medium for morphometric analysis based on information on the methanol-cellulose nitrate method by Seki (1937)^. After trial and error, we succeeded in our goal : The composition of the medium is as follows : cellulose nitrate 15.0g, methanol 78.6g, and others 6.4g (total of 100.00g). When the specimens are not so big, we can easily get 3-5 micron-thick sections like paraffin sections with complete non-contractibility. We believe that this new methanol-cellulose nitrate medium will be useful especially for histological morphometrical analysis

Light and Electron Microscopic Studies of Microcalcifications Appearing in Monomorphic Adenomas

Microcalcifications appearing in two cases of monomorphic adenomas were studied histopathologically, electron microscopically, and electron-microanalytically. One case was basal cell adenoma that occurred in a 56-year-old man and the other was canalicular adenoma in a 71-year-old woman. The calcified granules were observed both in the lumina formed by the tumor cells and in the stromal tissues. The surroundings of the granules were stained by alcian blue and showed a sulfur peak by EPMA. These facts suggest that the surroundings contain sulfated glycosaminoglycans and that sulfur has a significant role in the mechanisms of pathological calcification as well as physiological calcification

Pathological Examination of Experimentally Induced Periodontal Polyp in Mice

The mechanism in the formation of periodontal polyp has been established in several histological studies but details on cell differentiation and/or proliferation have not been elucidated. In the present study, we established a convenient and possible experimental system using ddY mice. Briefly, pentobarbital sodium (Somnopentyl) was injected into the abdominal cavity of the mouse followed by access cavity preparation on maxillary first molar using low speed ½ round bur (Merufa Inc), exposing the pulp and then allowed to perforate the floor of the pulp chamber. Observation was done over time until 6 months using micro CT (m_CT) image photography. Results with transmission image using m_CT showed theexpansion in the width of the periodontal ligament in the furcation area. The lesion was excised as one mass and examined histopathologically. The granulation tissue was covered with stratified squamous epithelium. The present experimental technique has been confirmed to be effective in analyzing the formation of periodontal polyp induced by mechanical perforation