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At least 19 recordsLinked to original sources
PubMed1975

Accelerated reattachment with cementogenesis to dentin, demineralized in situ. I. Optimum range.

This study confirms an original report describing accelerated reattachment with cementogenesis to root dentin, surgically exposed and demineralized in situ. It additionally describes results of 250 experiments on over 1000 teeth in mongrel dogs and cats designed to identify an optimum range of demineralization related to type of agent, pH, and time of application. This optimum range consistently induces flap reattachment with cementogenesis, while demineralization rates above and below this range enhance reattachment relative to undermineralized controls, but do not consistently induce new cementum. Although most controls demonstrated some reattachment with partial cementogenesis, none produced complete repair as did properly demineralized root surfaces and approximately one-third showed spithelial migration to the apical borders of the wound. No demineralized teeth demonstrated this control result. Small species differences in the response to root demineralization and the degree of hypermineralization of roots adjacent to chronic periodontal pockets, may make optimum ranges determined in this animal study slightly low for human pocket reaattachment techniques.

Animals↗
PubMed1976

Accelerated reattachment with cementogenesis to dentin, demineralized in situ. II. Defect repair.

Three surgical experiments, with histologic evaluation, were performed to study induced gingival reattachment to tooth root dentin demineralized in situ during flap surgery in adult mongrel dogs. Experiments demonstrated aspects of: (1) Weekly histochemical and morphological sequences of repair; (2) Repair of chronically inflamed bony defects simulating periodontal pockets; and (3) Six and 12 month repair of reattached surgical defects. Flap reattachment with cementogenesis was induced by in situ root demineralization using citric acid at pH 1.0 applied for 2 minutes. Results demonstrate: (1) The production of anchoring cementum pins extending into dentin tubules widened by demineralization; (2) Reattachment with cementogenesis of inflamed gingiva to roots exposed to chronically-infected surgical defects for 3 months; (3) Success in repairing chronic interproximal one-walled and labial one surface defects by reattachment; (4) Relative failure to repair bifurcation and horizontal bone defects by flap reattachment; and (5) Complete alveolar bone repair over most labial defects by 1 year, with maintenance of a periodontal ligament between induced bone and cementum. These findings, together with previous reports of induced reattachment to demineralized roots, provide further evidence for mechanisms and consistency and suggest that this regenerative phenomenon may be useful in repairing osseous defects in periodontal therapy.

Alveolar Process↗
PubMed1989

[Effect of various implant materials on cementogenesis].

Various implant materials have been used to stimulate the regeneration of supporting bone lost from periodontal disease. In addition, the histologic features of bone regeneration associated with their implantation have been evaluated. Very little, however, seems to be known about the effect of implant materials on cementum formation. The aim of this study was to determine whether implant materials stimulate the cementogenesis on adjacent planed root surfaces. Twelve monkeys with healthy gingivae were used in this experiment. Following mucoperiosteal flap elevation, "windows" were chiseled in the bone to the proximal root dentin surfaces and adjacent root surfaces were planed. Each of the three implant materials [tricalcium phosphate (TCP), decalcified bone matrix (DBM) and hydroxyapatite (HA)] were then placed in the cuspid and incisor root "windows" before the flap was sutured back into the previous position. Windows with no implantation served as a control. Animals were sacrificed 2, 4 and 8 weeks postoperatively. Biopsy specimens including the tooth and surrounding bone were examined by light and electron microscopy. At 2 weeks, all implant particles were surrounded by fibrous tissue. On the other hand, fibrous tissues filled the control defect. On the planed root surfaces after the implantation of TCP and DBM, furthermore, cementoid tissue appeared. At 4 weeks, a considerable amount of new cementum was deposited on the root surfaces except in the implantation of HA. It was especially pronounced after implantation of TCP and DBM which promoted bone regeneration after resorption. These results suggest that resorbable implant materials such as TCP and DBM not only facilitate the formation of new bone, but also of new cementum.

Animals↗
PubMed1990

Expression of attachment proteins during cementogenesis.

There is general agreement that during development the extracellular environment plays a critical role in controlling cell differentiation. Data generated from numerous studies support the possibility that cell attachment proteins and their corresponding cell receptors are possible candidates for this role. In particular, our studies are directed at identifying attachment proteins in mature cementum and establishing the function of these proteins during root formation. Fractionation of guanidine HCL/EDTA extracts of cementum revealed the presence of a bone-associated attachment, BSP, as well as fractions containing as of yet undetermined attachment proteins. Immunofluorescent examination of 1st molar tissues during root formation, obtained from 7 day-old mice neonates, for bone-associated attachment proteins indicated that osteopontin is expressed in the area of Hertwig's epithelial root sheath, but not in the region of the dental papillae. However, dental papillae cells, considered to have the capacity to form cementum, attached to osteopontin coated dishes, in vitro. Thus, unique attachment proteins, as well as those previously identified, were found in mature cementum and during root development. Future studies focused on identifying attachment proteins of mature cementum and determining the spatial and temporal localization of these proteins, pre- and post-cementogenesis, will provide important information necessary for establishing the function of these proteins during root development.

Animals↗
PubMed1983

Cementogenesis and soft tissue attachment after citric acid treatment in a human. An electron microscopic study.

The four maxillary incisors and two maxillary premolars of a 25-year-old male patient were used to study epithelial and connective tissue attachment 67 days and 164 days after flap surgery and cutting of an horizontal intradentinal groove near the buccal cervical region. Three teeth were topically conditioned for 3 minutes with citric acid pH = 1. The three other teeth were used as controls. The histologic examination was carried out in double-blind conditions; the examiners did not know which specimens were acid treated until the end of the study. Two of the three cases treated with citric acid showed improved healing conditions, when compared to the controls; a more coronal position of the epithelial attachment in the dentin nick as well as a relatively important gain in connective tissue attachment. Two types of connective tissue attachment were observed. The first consisted of an attachment to dentin, without cementum formation and was characterized by a mineralization of decalcified dentin collagen spliced with collagen, newly secreted by fibroblasts. The second type involved cementum formation. Topical citric acid treatment, however, can not be considered as a completely reliable clinical procedure since in one experimental case the type of attachment observed was not better than that seen in the control.

Adult↗
PubMed1992

The role of osteonectin in human tooth development: an immunohistological study.

We investigated immunohistologically 160 teeth and dental germs in various stages of tooth development taken from human individuals (13th week of pregnancy to the 24th year of life) to study the osteonectin expression in dental hard tissue. In the course of dentinogenesis, the predentin, the odontoblasts, and their cell processes show a positive osteonectin staining reaction. During cementogenesis, osteonectin is synthesized by cement-producing fibroblasts, cementoblasts, and cementocytes. The expression of osteonectin during dentinogenesis and cementogenesis is closely related to the development of the respective calcified tissue. All cells of the inner and outer enamel epithelium, the cells of the stratum reticulare and stratum intermedium, the ameloblasts, and the enamel substance are osteonectin negative, just as dentin and cement are. The results of this study indicate one important physiological role of osteonectin as a protein associated with the formation of collagen containing mineralizing tissues like human bone, as well as human dentin and cement.

Adolescent↗
PubMed1991

Cells from Hertwig's epithelial root sheath do not transcribe amelogenin.

Recent experimental evidence has led to the interpretation that "enamel-like" material is deposited along the forming mouse molar root surface by cells of Hertwig's epithelial root sheath (HERS cells) and that this material is integral to the developmental program for cementogenesis. The experimental strategy described in this study was to examine selected developmental stages of root formation for mouse first and second mandibular molars in order to localize the cellular sites of amelogenin gene transcripts using high resolution in situ hybridization. Amelogenin is the major structural protein of coronal enamel and is highly conserved among mammalian species at the DNA and amino acid sequence level. Within the limits of sensitivity for in situ hybridization and utilizing either cRNAs or oligodeoxynucleotide probes, we were unable to localize amelogenin transcripts within HERS cells from selected developmental stages associated with mouse molar root formation. In contrast, previous studies using antipeptide antibodies have provided immuno-histochemical localization of amelogenin domains in HERS cell-derived products. For these HERS cell-derived proteins to contain both amelogenin epitopes and yet fail to yield nucleic acid hybridization signals suggests that either gene rearrangement and/or alternative processing of messenger RNAs from the structural gene locus operate to produce immunologically related motifs sharing insufficient complementarity at the nucleotide level to permit efficient detection by hybridization. It is postulated that HERS cells synthesize proteins which contain amelogenin domains and that these proteins participate during cementogenesis. However, these enamel-related proteins are neither identical to, nor collinear with coronal canonical amelogenin transcripts.

Ameloblasts↗