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PubMed2005

Cytoskeleton and surface structures of cells directly attached to the tooth in the rat junctional epithelium.

OBJECTIVE: It is still an open question whether cells directly attached to the tooth (DAT) cells are migratory or non-migratory cells. The purpose of this study was to examine cytoskeletal and surface structures of DAT cells that might be involved in migration. METHODS: We investigated the distribution of stress fibers composed of actin filaments in DAT cells using phallacidin fluorescent dye methods in a confocal laser scanning microscope. To observe the three-dimensional structure of the DAT cell surface, the osmium maceration scanning electron microscope (SEM) method, which removes various soluble materials between DAT cells and the enamel, was employed. RESULTS: Stress fibers were found in the most apically located DAT cells, and were arranged in parallel to the presumable cervical-line, whereas some of the fibers ran parallel to the tooth axis in the more coronally located DAT cells. The parallel arrangement to the tooth axis of the fibers may be involved with migration for turnover, and the parallel accumulation to the presumable cervical-line may be concerned with the cervical contraction of DAT cells. Osmium maceration SEM images at high magnification revealed the existence of microvilli-like structures on the enamel surfaces (facing to the tooth surface) of DAT cells after removal of the soluble matrices. The thicknesses of the microvilli-like structures on the enamel surfaces and cell processes of intercellular bridges were significantly different. CONCLUSION: DAT cells possess stress fibers arranged in parallel to the tooth axis and to the presumable cervical-line in the cytoplasm, and microvilli-like structures on their enamel surfaces. These results suggest that these structures contribute to DAT cell migration.

Animals↗

PubMed1989

Evidence of acute inflammation in the periodontal ligament subsequent to orthodontic tooth movement in rats.

Experimental orthodontic tooth extrusion can result in red cell diapedesis through the PDL vascular wall. Diapedesis is an early sign of acute inflammation. At the ultrastructural level, red cell migration is demonstrated occurring through the endothelial junction of a postcapillary-sized venule. This phenomenon is considered to be indicative of unphysiological tooth loading.

Animals↗

PubMed2004

Unusual migratory foreign body in the neck.

Reports of ingested foreign bodies penetrating the pharynx and migrating through the neck are rare, and mostly involved fish bones. We describe a 44-year-old man who was involved in a motor vehicle accident and accidentally swallowed his tooth. The swallowed tooth penetrated the pharynx and became lodged adjacent to his right thyroid gland. It was successfully removed via neck exploration and the patient recovered well.

Accidents, Traffic↗

PubMed2002

Human mineralized bone in extraction sites before implant placement: preliminary results.

BACKGROUND: Bone loss after tooth extraction may prevent dental implant placement. Human mineralized bone grafts can be used to restore bone volume and allow for tooth replacement with dental implants. METHODS: The authors grafted 22 sites in 18 patients with human mineralized bone after tooth extraction. They allowed molar sites 16 weeks for graft healing, placed the implants and restored them with a final crown after a four-month integration period. Single-rooted maxillary sites received implants and immediate placement of provisional crowns or underwent a delayed two-stage restoration approach. The authors used radiographs and clinical examinations to evaluate the results. RESULTS: All of the sites were restored successfully with a single-tooth implant restoration. Periapical radiographs indicated that the crestal bone levels were limited to the first thread of the implants or slightly coronal to the first thread of the implant. Clinical evaluation indicated excellent gingival health around the provisional and final restorations, without obvious gingival migration. CONCLUSIONS: The use of human mineralized bone may have significant potential to reconstruct missing bone resulting from tooth extraction and to preserve bone after tooth extraction. In addition, healed bone graft sites seem to be able to support immediate placement of a provisional crown and implant restorations. CLINICAL IMPLICATIONS: Patients who are having teeth extracted may become candidates for implant restorations when the sites are appropriately grafted to preserve and reconstruct bone volume, thus allowing for more options for reconstructing the missing tooth site.

Alveolar Ridge Augmentation↗

PubMed2004

Coronectomy: a technique to protect the inferior alveolar nerve.

PURPOSE: Damage to the inferior alveolar nerve when extracting lower third molars is often caused by the intimate relationship between the nerve and the roots of the teeth. The technique of coronectomy, or intentional root retention, may minimize this problem. PATIENTS AND METHODS: Forty-one patients underwent coronectomy on 50 lower third molars with follow-up of at least 6 months. The technique of coronectomy deliberately protected the lingual nerve as part of the surgical procedure. All roots were left at least 3 mm below the buccal and lingual plates of bone. All patients were radiographed preoperatively, immediately postoperatively, and after 6 months. RESULTS: There were no cases of inferior alveolar nerve-involved damage in this study of 41 patients who underwent 50 coronectomies. There was 1 case of transient lingual nerve involvement, probably from the use of the lingual retractor. One patient required subsequent removal of the roots of both lower third molars because of failure to heal, and 1 patient required subsequent removal of a root because of subsequent migration to the surface. Root migration was noted in approximately 30% of patients over a 6 month period. CONCLUSION: Coronectomy appears to be a viable technique in those cases where removal of the whole tooth might put the inferior alveolar nerve at considerable risk of damage. The technique appears to be associated with a low incidence of complications, but subsequent migration of the roots may be an issue in the long term.

Cranial Nerve Injuries↗

PubMed1989

[Molecular mechanisms of cellular adhesion].

Regeneration of connective tissue structures lost as a result of periodontal disease remains the major goal of periodontal therapy. The ability of cells of the periodontium to adhere to the tooth surface is central to a number of phenomenons. Among these are cellular migration, morphogenesis and wound healing. Several classes of molecules appear to mediate the ability of cells to adhere. These cells utilize a group of receptors called Integrins to anchor themselves to the extra-cellular matrix. The receptors are transmembrane heterodimers which serve as bridges which communicate informations between the extra-cellular matrix and the cytoskeleton.

Cell Adhesion↗

PubMed1989

Postoperative status after partial removal of the mandibular third molar.

The aim of the study was to examine the postoperative status one year after partial removal of the third mandibular molar. Thirty-three third molars were selected because of the proximity of the apices to the mandibular canal and/or complicated root anatomy. At a follow-up examination one year postoperatively, clinical and radiological findings were recorded. A definition based on both clinical and radiological findings for healing and unsatisfactory healing, respectively, is suggested. Twenty-seven root fragments migrated between 1 and 7 mm coronally in the length axis of the tooth. Nine patients had subjective symptoms or objective findings. Three of these patients had dysesthesia. The findings indicated healing around 24 root fragments (73%) and unsatisfactory healing around 9 root fragments (27%). This findings of healing around most of the root fragments indicates that partial removal might be considered as an alternative method in certain cases of complicated root anatomy.

Adult↗

PubMed1989

[Sulcus and coronal junctional epithelium in mild gingivitis. A retrospective study].

Is the presence of mild gingivitis in humans synonymous with early pocket formation? In order to answer this question, buccal gingival biopsies from 5 children, 9 to 12 years of age, were studied by light and electron microscopy. These biopsies included the entire topographically intact gingival sulcus and coronal junctional epithelium. The results indicated that in the presence of supragingival plaque and mild gingival inflammation, the coronal junctional epithelium acquired a loose structure. However, this structural change did not affect the ability of the junctional epithelium to maintain its attachment to the tooth. The loose epithelial structure results in part from the apico-coronal migration of neutrophilic granulocytes through the junctional epithelium and the appearance throughout the junctional epithelium of irregular, cavernous enlargements of the intercellular spaces that are filled with tissue fluid. The degree to which the epithelial structure is altered varies over short stretches of the dentogingival junction. The findings are interpreted in the light of current knowledge in pathophysiology. The above question appears to have a negative answer.

Child↗

PubMedDate not supplied

The use of attachments in combination implant and natural-tooth fixed partial dentures: a technical report.

When implants and natural teeth are combined, forces on the abutments need to be controlled so that neither the teeth nor the implants sustain excessive amounts of force. The technique described addresses reduction of potentially harmful cantilever effects in a fixed prosthesis that is facultatively removable. A nonrigid attachment is used in the implant crown. Telescopic copings are definitively cemented on the natural teeth. Provisionally cemented overcastings incorporate this nonrigid connection between the pontics and the implant crowns. The means of connection employs a semiprecision attachment in which the female connector is placed within the relatively immobile implant crown. The male connector is placed on the pontic seating into the implant crown. This relationship limits cantilever forces exerted on the natural-tooth abutment. The nonrigid connection of the tooth-supported retainer limits cantilever forces and directs occlusal loads axially in a direction along the long axis of the implant. This arrangement is acceptable as compared to the complete tooth-supported arrangement described by Shillingburg; in this situation, the implant will not migrate. Since 1986, this arrangement has been used clinically without attachment migrations, implant failure, or endodontic therapy, with only minor screw-loosening episodes.

Dental Abutments↗

PubMed1990

[Measurement of supra-eruption of the human first upper molar in the absence of an opposing tooth].

The situation and configuration of the occlusal plane can be modified by the process of supra-eruption, which can be split up into: active eruption (the tooth leaves its socket) and periodontal growth. In order to dissociate and better by understand them, supra eruption of the first upper molar was observed in the absence of the first lower molar. Three groups of subjects were selected, the first group, our reference group (n = 50), consisted of subjects with complete healthy dental arches for which we could determine the extent of the gingival margin and the crown height. The second group of subjects (n = 50) differed from the former by the presence of a supra-erupted first upper molar. This allowed us to evaluate the migration of the gingival margin and the crown height increase in terms of the length of time the antagonist tooth was missing. The analysis of these 2 values shows that in the early years after the tooth loss, supra-eruption is due mainly to periodontal growth. It is only later that tooth movement beyond the occlusal plane is due principally to active eruption. The third group was made up of subjects showing pathological conditions of the periodontium. We observed an apical migration of the gingival margin and in increase in crown height, resulting from a periodontal regression (passive eruption) and a rapid active eruption.

Adult↗

PubMed1980

Healing following implantation of periodontitis affected roots into bone tissue.

The aim of the present experiment was to study whether new connective tissue attachment can occur to root surfaces which have been exposed to the oral environment and subsequently implanted into bone tissue. Twelve teeth in three beagle dogs were subjected to progressive periodontal breakdown to half the root length by placing cotton floss ligatures around the neck of the teeth. Following crown resection and root hemisection, the teeth were root filled and the roots thoroughly scaled and planed. Each root was extracted and implanted into bone cavities prepared in edentolous areas of the jaws in such a way that epithelial migration into the wound and bacterial infection were prevented during healing. Root implantation and sacrifice of the animals were scheduled to allow for observation periods of 1, 2 and 3 months. The results demonstrated that new connective tissue attachment did not occur to root surfaces which had been exposed to the oral environment, but healing was characterized by repair phenomena, i.e. mainly root resorption and ankylosis. In those areas of the roots where periodontal ligament tissue was preserved following tooth extraction, a functionally oriented attachment apparatus was reformed. The results indicate that in addition to apical migration of junctional epithelium and regrowth of subgingival plaque, the type of cells which repopulate the wound area may jeopardize new connective tissue attachment.

Animals↗

PubMed2005

Quantitative histological and ultrastructural features of opercula of normally erupting human teeth.

Tooth eruption across the mucosa in humans has been studied rarely, although there are disturbances of eruption that are attributed specifically to failure of the supraosseous eruptive migration. The aim of this study was to analyze the soft tissues covering normally erupting teeth so as to get an insight into the supraosseous phase of tooth eruption and to provide the basis for comparison with cases of eruption disturbances. Six opercula covering normally erupting permanent molars (primary opercula) and six of succedaneous teeth (secondary opercula) were surgically removed from 10 patients aged 7.5-17.5 years. Specimens were examined light and electron microscopically and analyzed morphometrically. All opercula contained strands and islands of odontogenic epithelium, prominent numbers of high endothelial venules, nerves, and mast cells. Nerves comprised normally structured, 1.5-3.5 microm thick myelinated (Adelta) and thinner unmyelinated (C) fibers. In primary opercula, the proportions of blood vessels and nerves were three- and sevenfold higher than the respective values for the secondary opercula. Furthermore, primary opercula contained multinucleated, fibroblast-like giant cells that were not observed in secondary opercula. As all teeth under investigation were erupting normally, neither the presence of the giant cells nor the atypical proportions of blood vessels and nerves appeared to be decisive in the eruption process. These conspicuous tissue components of opercula seem merely to accompany the eruptive tooth movement.

Adolescent↗

PubMed2006

Dental abscess in a tooth with intact dens evaginatus.

This article reports a case of dental abscess in a mandibular premolar with intact dens evaginatus. Dentists are advised to critically evaluate those teeth with dens evaginatus, both clinically and radiographically, before attempting prophylactic treatments. This is particularly important medicolegally in case the tooth develops symptoms shortly after the prophylactic treatment. Dentists practising in Western countries should also be aware of this dental anomaly because of the increasing global migration of people from Asia.

Asian People↗

PubMed2000

Mechanical stress enhances expression and production of plasminogen activator in aging human periodontal ligament cells.

Plasminogen activator (PA) converts plasminogen to plasmin, and plasmin activates the kinin cascade and latent extracellular matrix metalloproteases. The periodontal ligament serves to anchor the tooth to the alveolus and functions as a cushion between these hard tissues to migrate occlusal force during mastication. We reported previously that repeated mechanical tension force (MTF) as an experimental model of a traumatic occlusion, increased PA activity in human periodontal ligament derived fibroblast (hPLF) cells. In this study, the influence of in vitro cellular aging on MTF-stimulated PA activity in hPLF cells was studied. Aged hPLF cells produced a significantly higher PA activity when compared with those of young hPLF cells in response to MTF in a time- and magnitude-dependent manner. tPA mRNA levels in aged cells were higher than those in young cells, whereas PAI-1 mRNA remained unchanged and uPA mRNA was not detected. Because MTF-stimulated PA activity from hPLF cells was increased by in vitro cellular aging, aging of the periodontal ligament may affect the severity of the inflammation and the degradation of the extracellular matrix of periodontal ligament tissue by producing a large amount of PA in response to excessive force such as a traumatic occlusion.

Bite Force↗

PubMed2005

Facial and oral reconstruction following trauma and failed chin implant: a case report.

Functional and esthetic reconstruction of a patient with microgenia who sustained traumatic injury was successfully accomplished using Brånemark System osseointegrated implants (Nobel Biocare USA, Inc., Yorba Linda, CA) to support a permanent dental prosthesis following mechanical and biologic reconstruction of the anterior mandible and chin. A 25-year-old glycine chin implant previously used for facial esthetic enhancement had eroded the anterior cortical plate and migrated through the medullary bone, compressing the periosteum into the apex of the anterior tooth roots. Further destruction of the lingual cortex with risk of fracture was imminent. After removal of the chin implant, a cancellous bone graft was held in place with a titanium mesh frame. The prosthetic rehabilitation consisted of two phases of mandibular implant placement followed by the construction of a porcelain-fused-to-gold implant-supported fixed prosthesis, restoring the occlusal vertical dimension as well as appropriate lip support. Restoration of function was superior to the pretreatment condition.

Bone Resorption↗

PubMed1979

Long term effect of systemic tetracycline administration on the severity of induced periodontitis in the rat.

The present investigation was undertaken to determine the influence of systemically administered tetracycline on periodontitis in the rat. Thirty Sprague-Dawley rats were arranged into two groups, one group received 21 mg of tetracycline hydrochloride each day for 10 weeks in the drinking water. Periodontitis was induced in the maxillary left segment with a 0.008 inch stainless steel ligature wire and by modifying the normal diet with sucrose. The direct microscopic and histometric measurements obtained were analyzed for statistical significance, which revealed the following: 1. Tetracycline-treated animals demonstrated significantly less resorption of the buccal alveolar bone. There were no statistical differences however, in the amount of alveolar bone resorption palatally or interdentally. 2. Tetracycline-treated animals demonstrated significantly less apical migration of the junctional epithelium on the distal root of the maxillary first molar tooth. 3. Tetracycline-treated animals demonstrated significantly fewer inflammatory cells. In conclusion, long term systemic administration of tetracycline in the rat may be of value in reducing the amount of tissue destruction in experimentally induced periodontitis.

Administration, Oral↗

PubMed2000

Effects of neonatal injury of the inferior alveolar nerve on the development and regeneration of periodontal nerve fibers in the rat incisor.

Our previous study showed that the migration of terminal Schwann cells occurred in the periodontal ligament of the rat lower incisor following transection of the inferior alveolar nerve (IAN) in the adult animals [Y. Atsumi, K. Matsumoto, M. Sakuda, T. Maeda, K. Kurisu, S. Wakisaka, Altered distribution of Schwann cells in the periodontal ligament of the rat incisor following resection of the inferior alveolar nerve: An immunohistochemical study on S-100 proteins, Brain Res. 849 (1999) 187-195]. The aim of the present study was to investigate the effects of neonatal transection of the IAN on the regeneration of axon elements and Schwann cells in the periodontal ligament of the rat lower incisor. Following transection of IAN at post-natal day 5 (PN 5d), when the numbers of both axon elements and the terminal Schwann cells were very small, regenerating nerve fibers appeared between post-injured days 7 (PO 7d) and PO 14d, and increased in number thereafter gradually. Although the terminal morphologies of regenerated Ruffini endings became identical to those of the adult animals by PO 54d, the number of regenerated PGP 9.5-IR nerve fibers did not recover the adult levels even by PO 56d. A small number of Schwann cells migrated into the shear zone, the border between the alveolus-related part (ARP) and the tooth-related part (TRP), but did not enter into the TRP. Following transection of the IAN at PN 14d or PN 28d, when clusters of apparent terminal Schwann cells could be recognized, axon regeneration started around PO 5d. Individual axon terminals of the regenerating Ruffini endings ramified and became identical to those of the adult animals around PO 28d, but the number of regenerated Ruffini endings was smaller than that of the adult animals. Similar to the adult animals, the migration of Schwann cells into the shear zone and TRP occurred, and disappeared prior to the completion of the axonal regeneration. The present results indicate that the migration of the Schwann cells into TRP during the regeneration of the periodontal nerve fibers following nerve injury to the IAN depends on the maturation of the terminal Schwann cells of the periodontal Ruffini endings, not on post-operative time.

Age Factors↗

PubMed2000

Effects of TGFbeta1 on dental pulp cells in cultured human tooth slices.

Transforming growth factor-beta1 (TGF beta1) is a potent modulator of tissue repair in various tissues. To analyze its role during human dental repair, we used thick-sliced teeth cultured as described previously (Magloire et al., 1996). The supply of TGF beta1 to the pulp tissue was accomplished by means of a small tube glued onto the dentin. We show that this device allowed the growth factor to diffuse locally through dentinal tubules and to bind to the cells present in the coronal pulp opposite the TGF beta1-delivery tube. The tube was filled with 20 ng/mL TGF beta1, and slices were cultured for 4 days. Results show a preferential accumulation of cells in the odontoblastic and subodontoblastic layers in the vicinity of the tube. Cell proliferation increased in the subodontoblastic layer and in the underlying pulp, and BrdU-positive cells were abundant around the blood vessels. TGF beta1 induced type I collagen production by the odontoblastic/subodontoblastic/pulp cells in the stimulated zone, as demonstrated by in situ hybridization. These results suggest that TGF beta1 could be directly involved in the regulation of cell proliferation, migration, and extracellular matrix production in the human dental pulp and eventually in the repair process occurring after tooth injury.

Adolescent↗