Periodontal Fiber Attachment Research Articles

Runx2 heterozygosity alters homeostasis of the periodontal complex.

Haploinsufficiency of Runx2 (Runx2+/- ) causes dental anomalies. However, little is known about the involvement of Runx2 in the maintenance of dentin, cementum, and the periodontal ligament (PDL) during adulthood. This study aimed to observe the effects of Runx2+/- on homeostasis of the periodontal complex. A total of 14 three-month-old Runx2+/- mice and their wild-type littermates were examined using micro-computed tomography, histology, and immunohistochemistry. Phenotypic alterations in the dentin, cementum, and PDL were characterized and quantified. Haploinsufficiency of Runx2 caused cellular changes in the PDL space including reduction of cell proliferation and apoptosis, and irregular attachment of the collagen fibers in the PDL space into the cementum. Absence of continuous thickness of cementum was also observed in Runx2+/- mice. Runx2 is critical for cementum integrity and attachment of periodontal fibers. Because of its importance to cementum homeostasis, Runx2 is essential for homeostasis of periodontal complex.

ORAL PROTOZOA IN A NIGERIA POPULATION

A study aimed at establishing the occurrence of oral protozoa in a Nigeria population was carried out over a 6-month period, January 1998 to June 1998. A total of 203 dental patients attending the dental clinics of the University of Nigeria Teaching Hospital (UNTH), Enugu were involved. Scrapings of plaque were taken from the buccal surfaces of T16 and T36 (near the gingival margins) and placed on individual glass microscope slides. To each was added a drop of saline, which was mixed with the plaque and covered with a coverslip and then examined immediately. Thirty-three (16.30%) of the patients harboured protozoa in their mouths. Of these, 10 (4.9%) had Trichomonas tenax , while the majority 23 (11.3%) had Entamoeba gingivalis . No patient had both species of protozoa in their mouths. The associations of age, sex, teeth cleaning and other dental parameters with prevalence of protozoa were recorded. Our findings suggest that poor oral hygiene, calculus, old age and loss of attachment of periodontal fibers, are factors, which favour the proliferation of Entamoeba gingivalis . African Journal Of Clinical And Experimental Microbiology Jan 2004 Vol.5 No.1 15-19

Cementogenesis reviewed: A comparison between human premolars and rodent molars

Background Cementum continues to be the least-known mineralized tissue. Although recent advances in the field of molecular biology have contributed to an understanding of the involvement of molecular factors in cementum formation during development and regeneration, cementogenesis on a cell biological basis is still poorly understood. Virtually nothing is known about cementoblast origin, differentiation, and the cell dynamics during normal development, repair, and regeneration. This review describes the recent findings of cementogenesis on roots of human premolars and opposes them to those of teeth from other mammals, particularly the rodent molar. Methods Using light and electron microscopy, light microscopic radioautography, and various measurements, a comprehensive insight into the development and repair of cementum during and after root formation and tooth eruption has been achieved for human premolars. Results Cementum is a highly responsive mineralized tissue. This biological activity is necessary for root integrity and for bringing and maintaining the tooth in its proper position. With regard to cementum formation and periodontal fiber attachment, considerable species-particularities exist that are mainly based on differences in growth rates and tooth sizes. Since root development and initial cementogenesis last on the average 5–7 years in human premolars, cementum formation in these teeth is characterized by a long-lasting phase of prefunctional development, which occurs independent of principal periodontal fiber attachment to the root and which may take 5 years or more. The first molar of the rat, however, is in functional occlusion 3 1/2 weeks after the onset of root formation. Since initial cementum formation and periodontal fiber attachment to the root occur almost at the same time in this tooth, the distinction between cells associated with one or the other process is very difficult to achieve, and cementogenesis cannot be described independent of periodontal fiber attachment to the root. Therefore, the determination of cementoblast origin in the rodent molar may be intricate. Conclusions Taking into account these species differences, the current description on the origin and differentiation of cementoblasts is inconsistent and the description of cementogenesis is still incomplete. This review calls into question the currently held concept of cementogenesis and offers a possible alternative. © 1996 Wiley-Liss, Inc.

Periodontal fiber attachment and apical root resorption

Abstract Apical root resorption is frequent after physiological and orthodontic tooth movement. Current resorption concepts emphasize a protective effect due to cell and fiber attachment to surfaces at risk. The present study investigated relationships between fiber attachment to the root surface and susceptibility to root resorption. The material comprised 10 normal mandibular second and third bicuspids with surrounding periodontia from 4 squirrel monkeys. On step‐serial histological sections, defined coronal, middle and apical root surface regions were examined, and attached fiber density and diameter were quantified using computerized digitization methods. For each root surface region, the density and diameter value was used to calculate the fiber occupancy per unit root length. Analysis of variance testing between animal, tooth surface, and defined root surface region showed a significant effect for root surface region only. In the apical region of the root surface, the fiber density was significantly less and the fiber diameter was significantly greater than in the coronal and middle regions. The product of density and diameter showed that attached fiber occupancy was significantly less in the apical region (58%) than in coronal (70%) and middle (74%) regions. It was concluded that differences in attached fiber occupancy may contribute to the greater susceptibility of the root apex to resorption.

In vitro attachment of bacteria to extracts of cementum.

Cementum is a specialized mineralized tissue providing for the attachment of periodontal fibers to the root surface of a tooth. In periodontal disease this connective tissue attachment to the cemental surface is lost. The ability of bacteria to adhere to the root surface, an initial event in the disease process, may be influenced by the organic matrix of cementum. Therefore, an in vitro assay of cell attachment was modified to study bacterial adherence to protein extracts of cementum. Petri dishes coated with the extracts were pre-incubated in culture media and then bacteria were added. Using this assay, Capnocytophaga-like species, a gram negative bacterium implicated in periodontal disease, attached preferentially to dishes coated with cemental extracts when compared with Type I collagen or uncoated dishes. This assay system should prove beneficial for studying the attachment of various microorganisms to protein extracts of both normal and diseased cementum, as well as providing insight into the unique attachment properties of cementum.

Formation of the periodontal attachment in developing rabbit permanent incisors.

Permanent incisors from fetal New Zealand white rabbits aged 25-30 days in utero and from 1-20 days postnatally were processed for light microscopy. Examination of longitudinal and cross-sections revealed that cementum deposition and fiber attachment first occurred at 27 days in utero. A tooth-to-bone course of principal fibers confined to lateral aspects of the teeth was observed in 29-day fetal incisors, whereas lingually the periodontal ligament remained undeveloped as late as 5 days postnatally. In 20-day postnatal incisors, the development of the functional periodontal ligament was complete as evidenced by the fiber arrangement on all aspects of the root-analogue tooth surface. This study shows that 25-26-day fetal rabbit permanent incisors represent the end of the follicular phase, whereas 27-day fetal to 20-day postnatal teeth demonstrate distinct histologic characteristics of initial, incomplete and complete periodontal fiber attachment.

The angular bone defect and its relationship to trauma from occlusion and downgrowth of subgingival plaque

Sixty-four sets of human teeth were collected with the aim of evaluating the role of trauma from occlusion in the etiology of destructive periodontal disease. Before the jaws were taken out, a careful bite analysis was carried out. After fixation of the jaws, impressions were taken and plaster of Paris models were made. Finally, a set of 14 radiographs were taken. On the basis of the "clinical" records postmortem, the study models and the radiographs, the jaws were sectioned. Only mesio-distal sections were included in the present analysis. The total number of interdental spaces examined was 106. The following observations were made: 1. Before any loss of periodontal fiber attachment has taken place, the configuration of the interdental septum is entirely dependent on the location of the cemento-enamel junction (CEJ) of the two neighboring teeth. The alveolar crest does not approach the apical border of the junctional epithelium closer than about 1 mm. Thus, if the CEJ is located at different levels on two neighboring teeth, the marginal termination of the interdental septum will be oblique, forming an acute angle with the "lowest" tooth. 2. Loss of periodontal fiber attachment could invariably be related to the apical growth of subgingival plaque, and downgrowth of plaque was always associated with an inflammatory process which involved lysis of the attachment fibers within a distance varying between 0.2 and 1.8 mm from the apical border of the plaque. Subsequently, the JE proliferated down to cover the denuded root surface. 3. Reduction in height of the alveolar crest could also be related to the downgrowth of plaque. The distance from plaque to bone was never found to be less than 0.5 mm and never more than 2.7 mm. The configuration of the interdental septum always seemed to be determined by the level of the plaque on the two neighboring tooth surfaces. Thus, if the plaque had reached the same level on both sides, the crest of the interdental septum assumed a horizontal outline; if plaque had proliferated down to different levels, the crest of the interdental septum was oblique and an angular defect hereby established. 4. In the present material no evidence was found to indicate that functional (traumatic) forces can act as a co-factor in the causation of angular defects. In fact, such defects were found equally often adjacent to "nontraumatized" as to "traumatized" teeth. 5. Infrabony pockets were invariably associated with downgrowth of subgingival plaque.

Clinical, radiographic, histologic, and electron microscopic observations of plastic tooth implantations in baboons

Twenty-one successful plastic tooth implants composed of polymethylmethacrylate were performed on thirteen baboons; fifteen other implants were lost within 2 to 97 days because of failure of retention. Complete jaw block specimens were removed surgically at specific time intervals of from 2 weeks to 12 months. There was no histologic evidence of epithelial attachment to the plastic implant tooth; instead, there was an apical proliferation of the epithelial attachment, the apical extent of which increased with the age of the tooth implant. Periodontal membrane inflammation was universal. The degree and depth varied with each specimen, but it reached the apex in seventeen of the twenty-one histologic sections. Five cases of severe inflammation with osteomyelitis were observed in four different animals in implant sites varying from 2 weeks to 3 months in duration. No attachment of periodontal fibers to the twenty-one plastic implants could be demonstrated by either light or electron microscopy. The periodontal fibers assumed an arrangement parallel to the vertical axis of the plastic tooth, rather than their normal perpendicular or diagonal alignment. It is believed that the severe toxic reaction of the implant site tissues in the five osteomyelitis cases was most likely caused by liquid monomer leaching out from the plastic material. Plastic tooth implants can often be retained if holes are drilled through the root, thus creating a bony pin type of retention after 3 months. That is not an ideal form of support, however, because deep periodontal pockets still exist, a true fibrous periodontal union of plastic to bone is not achieved, and proliferating epithelium is buried, creating a site for possible later cystic or malignant change. Replacement of lost natural teeth with fabricated synthetic replicas will be perfected and generally utilized in the practice of clinical dentistry as one of the most dramatic and fruitful advancements in dental research. However, the results of this investigation underscore the contention that further research is definitely warranted before polymethylmethacrylate tooth implants are acceptable for generalized use in clinical dentistry.

Periodontal Fiber Attachment to the Plastic Tooth Implant

Periodontal Fiber Attachment to the Plastic Tooth Implant