Adjacent Alveolar Bone Research Articles

The biocompatibility of hydroxyapatite implanted in the human periodontium.

A TEM study was made of the response to synthetic hydroxyapatite prepared in powder form and implanted for 6 and 12 months respectively in infrabony lesions in 2 adult patients with chronic periodontitis and tooth mobility. Round or oval‐shaped crystal aggregates, ranging in diameter from 1 to 20 μm, were surrounded by connective tissue free of inflammatory cells. The aggregates were made up of loosely‐packed individual synthetic hydroxyapatite crystals, with a mean diameter of 128.12±14.57 nm, separated by an amorphous matrix containing few collagen fibrils. In the 6‐month implants small apatite crystals, of a size similar to those found in adjacent alveolar bone and giving similar diffraction patterns, appeared in the center of the aggregates between the relatively large crystals of synthetic hydroxyapatite. These new apatite crystals filled the amorphous matrix progressively from the center to the periphery of the aggregate. The latter was surrounded either by fibroblasts or by osteoblasts and osteoid tissue. In the 12‐month samples a calcified collagenous bone matrix enveloped the crystal aggregates. Typical osteoclasts, lacking a brush border, were evident around certain aggregates. Some osteoclasts contained large vacuoles filled with synthetic hydroxyapatite crystals.

Idiopathic resorption of teeth A report of three cases

External resorption of teeth is a condition typically associated with etiologic factors within the adjacent alveolar bone, such as chronic periapical or periodontal infections, neoplasms, erupting permanent teeth, orthodontic movement, or trauma to the jaws. When none of these causes are present, resorption of teeth at the cementoenamel junction has been termed “idiopathic resorption of teeth.” Three cases of idiopathic resorption of teeth are reported, the literature on previous cases is reviewed, and hypotheses as to causes and a new theory are postulated regarding the possible mechanism for osteoclastic resorption of teeth.

External root resorption following bleaching of pulpless teeth with oxygen peroxide.

Abstract Eleven teeth in which bleaching with 30% oxygen peroxide was followed by external root resorption are presented. One tooth had no traumatic history, while the others were previously subluxated or luxated in accidental injury. Radiographic appearance of resorptions varied. In 2 teeth the resorptions were only superficial and did not progress during the observation time. In 5 teeth the resorptions were associated with ankylosis. In the remaining 4 teeth the resorption was progressive, bowl‐shaped and associated with radiolucency in the adjacent alveolar bone. It was suggested that damage to the periodontium, caused by oxygen peroxide at the time of treatment, may heal or be followed by ankylosis and, when complicated by bacterial contamination, develop to a progressive root resorption associated with persistent inflammatory changes in periodontal tissues.

A geminated tooth with adjacent cyst

Gemination is a rare phenomenon. No reports of gemination include descriptions of adjacent alveolar bone pathology. This is a clinical report of tooth gemination of a mandibular incisor in a 27-yr-old black female with an adjacent alveolar bone radiolucency. The content of the bone lesion was removed for biopsy and the crown of the lateral incisor was reshaped to remove a rudimentary projection. The histological diagnosis was a cyst of undetermined origin. Endodontic treatment of the incisor was performed 2 yr after initial treatment because of cold sensitivity. A 5-yr follow-up examination revealed that the osseous lesion appeared to be healed radiographically. The tooth is asymptomatic, functional, and has normal bone support and attachment levels. The combination of a cyst adjacent to a geminated tooth is very rare and presented with a very unusual radiographic appearance.

The cytology of the dental follicle and adjacent alveolar bone during tooth eruption in the dog.

Previous studies from our laboratories have shown that premolar eruption in dogs depends upon the presence of the dental follicle and is independent of root or crown growth or attachment to the oral epithelium. The present study is an analysis of the cellular composition of the dental follicle and the cellular investment of the adjacent walls of the bony crypt before and during eruption of the third and fourth mandibular permanent premolars in young beagle dogs. Four premolar follicles and their adjacent bony crypts were examined at 2-week intervals over 12 weeks before and during eruption of these teeth. Tissues were removed, fixed, processed, and oriented so that each follicle and the adjacent crypt wall could be reproducibly examined in vertical and horizontal planes. Mononuclear cells with abundant cytoplasm, euchromatic nuclei, and prominent nucleoli were present in juxtavascular location in the coronal part of the dental follicle; and these cells increased in number immediately preceding and during tooth eruption in parallel with an increase in osteoclasts on the adjacent crypt wall. These data are interpreted to mean that the coronal part of the dental follicle may coordinate the alveolar bone resorption required for tooth eruption by attracting and directing to the crypt wall a population of mononuclear cells, which either become osteoclasts and/or direct osteoclastic activity during tooth eruption.

The distribution of plasma cells in naturally occurring periodontitis lesions in rats. A light and electron microscopic study.

Plasma cells are widely distributed in inflamed periodontal tissues, the adjacent periodontal ligament and nearby alveolar bone spaces, of old rats (20 and 27 months) raised on a conventional diet in a normal laboratory environment. Electron microscopy revealed three morphologic types (or perhaps stages) of these cells based on the arrangement and content of the granular endoplasmic reticulum. Close contact between plasma cells and other cell types, such as lymphocytes, macrophages and fibroblasts, were commonly observed. It is suggested that plasma cell infiltration is a widespread and prominent feature of naturally occurring periodontitis in old rats, resembling the condition known to exist in humans, monkeys and dogs. The occurrence of large numbers of apparently fully differentiated plasma cells in otherwise normal alveolar bone marrow is discussed.

Repair in Different Zones of the Periodontium After Tooth Reimplantation

This study was undertaken to clarify the dynamics of tissue repair in the transseptal region and periodontal ligament after tooth reimplantation. Twelve teeth, distributed in four squirrel monkeys, were extracted and reimplanted within 3 minutes. The reimplantation schedule provided three teeth at 1, 3, 7 and 21 days after reimplantation. Tritiated proline was injected 8 hours before animal sacrifice. Histologic characteristics and autoradiographic grain densities were compared in the transseptal and periodontal ligament areas. One day after reimplantation there was a distinct break in the continuity of transseptal and periodontal ligament fibers. Regions bordering the tear, and the entire ligament, were virtually acellular. Cell repopulation was occurring in the transseptal region at 3 days, in contrast to the ligament which was still acellular. At 7 days, cell repopulation appeared complete in the transseptal area, and new fibers were evident bridging the tear. The periodontal ligaments still had acellular areas, lacked fiber continuity, and were repopulating primarily from the adjacent alveolar bone which had enlarged marrow spaces and active osteoclastic resorption. Proline grain density was significantly greater in the transseptal area compared with the periodontal ligament. In 21 day specimens, the transseptal region appeared normal. Although cell repopulation and restoration of fiber continuity had occurred in the periodontal ligament, normal orientation was absent. Grain density in the periodontal ligament was significantly greater than in the transseptal region. The results indicated that healing after tooth reimplantation occurred more rapidly in the transseptal region than within the periodontal ligament. The transseptal healing resembled that reported following incisional wounds, whereas healing in the periodontal ligament was dependent primarily upon repopulation from the adjacent alveolar bone.

Electron microscopic localization of virions in developing teeth of young hamsters infected with minute virus of mice.

Virus particles were detected within the nuclei and cytoplasm of odontogenic cells in the developing teeth of young hamsters infected with a small DNA virus (MVM). Disturbances of normal cytodifferentiation and organogenesis occurred as a result of viral multiplication. Virions were also observed in dense lysosome-like bodies of activated monocytes within the periodontal ligament and adjacent connective tissues. Fibrolytic and osteolytic lesions in the periodontal ligament and adjacent alveolar bone were associated with the inflammatory cell infiltrate.

Influence of Plaque Control on the Healing of Experimentally‐Induced Bone Defects in the Dog.

The aim of this investigation was to induce alveolar bone defects experimentally in dogs and to study the effects of mechanical tooth cleaning on their subsequent development. Thirty premolars from four beagle dogs were used. Bone defects were created by surgically exposing the adjacent alveolar bone and applying steel or silk ligatures around the roots of the chosen teeth. After 8 weeks the ligatures were removed. Dental plaque was allowed to accumulate on 20 premolars whereas daily plaque elimination by toothbrushing was carefully performed on 10 premolars. After 1, 3, and 6 months of plaque accumulation, gingival inflammation, periodontal pocket depth, gingival recession and the radiographically observed degree of bone destruction were registered. Histological examination was performed in conjunction with the registrations made 6 months after removal of the ligatures. The clinical, radiographic and histologic findings all confirm that a regeneration of the experimentally induced destruction of the periodontal tissues had taken place. This reaction was most evident in teeth exposed to mechanical plaque control. The remaining bone defects were consistently accompanied by recession of the gingival margin.

Vascular Responses in the Human Periodontal Ligament and Alveolar Bone Detected by Photoelectric Plethysmography: The Effect of Force Application to the Tooth

A modification of the technique of photoelectric plethysmography has been developed to monitor changes in the microcirculation of the human periodontal ligament and adjacent alveolar bone, whereby detection is made of light reflected from or transmitted through a tissue during alterations in blood volume, flow or distribution. Light is conducted to and from the periodontal tissues via miniature fiberoptics placed within the root canals of endodontically treated teeth, or illuminated through the external surface of the gingiva towards the root. Circulatory activity was monitored both with the teeth at rest and under forces up to 480 gm. Horizontal and axial forces were found to produce a decrease in blood volume in the area of the periodontal tissue under compression. In an area under tension, an initial increase in blood volume was followed by a decrease as the magnitude of force rose above the critical 90 to 180 gm level. The pulse volume, however, was increased during both phases. Analysis of the biphasic and pulse volume changes suggests that autoregulation of blood vessel tone occurs in the periodontal tissues as a result of alteration in extravascular tissue pressure when the root is moved relative to the alveolus. It is proposed that this autoregulatory mechanism may play a role in alveolar bone metabolism by producing alteration in local tissue oxygen tension.

Cellular response to subgingival injection of bacterial products in the rat.

Various bacterial products were injected in the oral mucosa of 74 conventional weanling rats of the Holtzman strain. The site of injection was lingual to the mesial cusp of the first molar of the maxilla or mandible. The bacterial products were whole dead cells, cell walls or cytoplasm obtained from Actinomyces naeslundii. Saline was injected into control animals. The animals were killed at intervals 0 to 48 hours subsequently, and the tissues examined by standard histological methods.In all cases there was an initial polymorphonuclear response at the site of injection which had usually disappeared by 24 hours. In addition, osteoblasts on the adjacent alveolar bone were destroyed and in no case had they reappeared at 48 hours. Osteocytes were also missing after whole dead cell or cytoplasm injections, but not after cell wall injections. The most striking difference between the various reactions was an early appearance of lymphocytes after cell wall injections, which overshadowed the polymorphonuclear response, and which persisted up to 24 hours post injection. The disappearance of osteoblasts and osteocytes after injection of bacterial products from an organism associated with periodontal disease in man may explain in part the bone loss in this condition.

Effects of acrylic restorations on the periodontium of monkeys.

Replanted teeth that had an acrylic restoration in the middle third of their roots were studied from three days to six months after grafting. The study revealed that the acrylic obturator elicited epithelial proliferation, fibrous encapsulation, moderate chronic inflammation, and adjacent alveolar bone loss.

Tooth transplantation by separation and moving of the adjacent alveolar bone

The transplantation of an impacted tooth with its adjacent alveolar bone is a surgical procedure which offers considerable promise and merits further study.