Expression of neuropeptides and bone remodeling-related factors during periodontal tissue regeneration in denervated rats.

Increasing evidence indicates that bone remodeling is under the control of factors related to neuronal regulation, but the underlying mechanisms remain largely unknown. The aim of this study is attempted to assess the effect of denervation on neuropeptide expression and bone remodeling-related factors in the periodontal tissue regeneration process. rats underwent transection of the left inferior alveolar nerve (IAN-T) and surgery to produce bilateral periodontal defects; then, alveolar tissue was obtained from the animals of each group at 1, 2, 4, 6 and 8 weeks after the operation. The expression levels of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) were quantified by real-time PCR and Western blot techniques, and immunohistochemical staining was applied to investigate the in situ expression of OPG and RANKL. Osteoclasts were identified by tartrate-resistant acid phosphatase staining. The expression levels of calcitonin gene-related peptide (CGRP) mRNA and substance P (SP) mRNA were also quantified by real-time PCR. Mandibles with only periodontal defects were used as controls. After denervation, the OPG/RANKL ratio was reduced in the IAN-T groups due to decreased OPG mRNA and protein (P < 0.05) and a simultaneous increase in RANKL mRNA and protein expression (P < 0.05). On the other hand, the number of osteoclasts in periodontal defect areas increased, especially at 2 weeks, and at this time point, the expression of RANKL mRNA and protein peaked. The mRNA expression levels of neuropeptides CGRP and SP mRNA were monitored throughout the entire progress and exhibited a trend that was similar to that of the OPG/RANKL ratio, i.e., a downward trend over 1-2 weeks, an increase until 6 weeks, then back to the normal levels at 8 weeks. Innervation influences the OPG/RANKL ratio and neuropeptide expression, both of which govern the periodontal alveolar bone regeneration processes.

Alternative anesthetic technique for maxillary periodontal surgery.

BACKGROUND: Maxillary periodontal surgery typically requires multiple injections and may inadvertently affect facial structures such as the upper lip, lateral aspect of the nose, and lower eyelid. To minimize these sequelae and reduce the number of total injections, a relatively new injection technique has been proposed for maxillary procedures. The anterior middle superior alveolar (AMSA) injection is reported to effectively anesthetize maxillary teeth and associated gingival tissues extending from the buccal root of the first molar mesially to the central incisor with a single injection while avoiding undesirable side effects. The purpose of this article is to provide background information on the AMSA injection and demonstrate its use in a variety of maxillary periodontal surgeries. METHODS: Anesthesia was provided for five separate maxillary periodontal surgeries with unilateral or bilateral AMSA injections. Injections were administered via conventional syringe with a 27-gauge needle. Confirmation of anesthesia was subjectively tested with buccal mucosal sticks and palatal transgingival probing. RESULTS: The AMSA injection provided promising results for a variety of maxillary periodontal surgical procedures. Benefits of the AMSA injection included outstanding palatal hemostatic control, avoidance of undesirable collateral anesthesia, and a reduced number of cumulative injections. Drawbacks of the AMSA injection included occasionally inadequate buccal hemostatic control and short-lived anesthesia of the maxillary central incisors. CONCLUSION: The AMSA injection is a novel anesthetic technique that may prove useful for certain maxillary periodontal surgeries.

Branching patterns and intraosseous course of the mental nerve.

PURPOSE: The purpose of this study was to clarify the branching patterns of the mental nerve (MN) and intraosseous courses of the MN branches, and to determine the clinical relevance of the various courses of the MN branches. MATERIALS AND METHODS: We investigated the topography of the MN by dissecting 31 hemifaces of Korean cadavers. Based on the distribution area of the MN, it was divided into angular (A), medial inferior labial (ILm), lateral inferior labial (ILl), and mental (M) branches. We classified the branching patterns of the 4 branches of the MN into 5 types. RESULTS: Type II, in which the MN divided into 3 branches (A, ILm, and M), with the ILl branch separating from the A branch, was the most common (35.4%). The MN was classified based on the shape of the anterior loop into loop, straight, and vertical patterns, which constituted 61.5%, 23.1%, and 15.4%, respectively. In the mandibular canal, the inferior alveolar nerve completely divided into the MN and the dental nerve, which supplies the teeth. In 17 cases (81%), the nerve bundles constituting the A branch were located at the superior aspect, whereas the nerve bundles of the inferior labial and mental branches were in the middle and inferior aspects within the mandibular canal, respectively, at the mental foramen region. CONCLUSION: These observations can help clinicians to predict the location or extent of paresthesia in the facial region according to the location and extent of nerve damage during dental implant surgery or genioplasty.

Normal development of dental innervation and nerve/tissue interactions in the colony-stimulating factor-1 deficient osteopetrotic mouse.

Dental innervation occurs concurrently with tooth development, eruption, and root formation and is suggested to interact with developing tissues. The purpose of the present study was to investigate dental innervation in osteopetrotic (op/op) mice, which carry a mutation of colony-stimulating factor-1 (CSF-1) and demonstrate sparse macrophages and osteoclasts, failure of bone resorption, lack of tooth eruption, and poor root formation. Jaw tissues from 21 mice in different age groups (7 days, 18 days, 26 days, 5 weeks, and 3 months) were prepared for immunocytochemistry and light microscopy. Immunocytochemistry with the neuronal marker protein gene product 9.5 (PGP 9.5), macrophage marker F4/80, double-labeling with F4/80 and PGP 9.5, and histochemical analysis using tartarate-resistant acid phosphatase (TRAPase) were carried out in selected sections. Molar and incisor development were arrested in the op/op mouse, and both types of teeth had bony occlusion of the eruptive pathway and failure of root formation. Third molar development in the normal mouse is delayed until after birth; therefore, it encounters different bone barriers and jaw structures than are present when first and second molars and incisors begin to develop after the second embryonic week. All three molars, however, completed crown formation prior to eruption failure. Partial root formation was seen in several homozygous op/op mice, and, in those cases, there was partial development of the periodontal ligament. Innervation of dental tissues that successfully formed was essentially normal in the mutant mice despite phenotypic deficiencies in macrophages and osteoclasts. The periodontal ligament was innervated with PGP 9.5-immunoreactive Ruffini mechanoreceptive endings in those cases in which the ligament formed, and op/op mice had remarkably normal sensory innervation of molar and incisor pulp despite failure of bone resorption, failure of root development, and arrested eruption. This study shows that op/op mice develop normal innervation in dental tissues and that dental nerve development proceeds independently of bone abnormalities and root failure in this animal.

Healing of the root surface-associated periodontium: an immunohistochemical study of orthodontic root resorption in man.

The purpose of the present investigation was to study resorption and regeneration of periodontal tissues incident to orthodontic tooth movement, in particular cells resorbing the root surface and the subsequent regeneration of the periodontal epithelial network and forming reparative cementum. The study was carried out using a select number of immunohistochemical markers on extracted human teeth which had been treated orthodontically. The most striking finding in the resorbing areas was the presence of what appeared to be two populations of KP 1+ mononuclear cells located at a distance of 50-100 microns from the root surface and multinucleated cells in resorption lacunae in close contact with the root surface. KP 1+ has previously not been reported for odontoclasts. The mononuclear KP 1+ cells in the periodontal ligament may represent either precursors to odontoclasts or phagocytic scavenger cells of the macrophage lineage. The subsequent healing of the resorption lacunae was characterized by re-establishment of nervous, vascular and epithelial tissues as evidenced by S-100+ filamentous delicate structures, factor VIII+ vessels and cytokeratin+ clusters of cells, respectively. However, cytokeratin+ single cells in close contact with the unresorbed cementum did not re-appear within the healing period. Although the present results are not quantitative in nature, cementoblasts located in the vicinity of resorption lacunae, especially healing ones, appeared to show an up-regulation of epidermal growth factor (EGF) receptors. It may be suggested the intense positive staining for EGF receptors may be an expression of an auto- or paracrine stimulatory pathway increasing the rate of reparative cementum formation.

Histological characteristics of peri-implant mucosa around Brånemark and single-crystal sapphire implants.

Soft tissues surrounding Brånemark titanium implants and single crystal sapphire implants were studied by conventional light- and transmission electron microscopy and by immunohistochemical markers for cytokeratin, protein S-100, Factor VIII and KP1. Histological sections of biopsies obtained from clinically healthy peri-implant mucosa were separated into a keratinized outer implant epithelium and an inner, non-keratinized epithelium, both immunoreactive towards cytokeratin. The inner implant epithelium terminated in a junctional epithelium, apically not a few cell layers thick. The cells adjacent to the implant showed a condensed cytoplasm, resembling hemidesmosomes. In the underlying connective tissue, rich in fibroblasts and factor VIII immunoreactive blood vessels, the bundles of collagen ran in different directions. S-100 immunoreactive nerve structures were more frequently found beneath the outer than the inner implant epithelium. Inflammatory cell infiltrates, some KP1 positive, were observed in the apical parts of the inner implant epithelium. S-100 positive Langerhans' cells were present mainly within the the outer implant epithelium. For the two implant systems, the techniques disclosed no qualitative structural differences in the adjacent soft tissues.

Periapical neural changes after pulpectomy.

Pulpectomy and pulpal necrosis result in severance of the nerves that supply the pulp as well as loss of their target organ. Inflammatory changes commonly extend into the periapical region to involve those nerves. The neural response to pulpal loss combined with periapical inflammation is a derangement of the periodontal plexus normally located in the center of the periodontal space around the apical third of the root; the result is the formation of a disorganized group of sprouting and branching axons that have some features in common with neuromas. The inflammatory and neural responses continue for at least a year even when pulpectomy is followed by canal debridement and obturation. Then the responses are reduced but not eliminated by steroids. Root canal therapy with techniques that do not leave residual inflammation still results in increased periapical innervation; the increase seems to be an organized addition to the normal periradicular plexus.

Nerve growth factor receptor and neurochemical markers in human oral mucosa: an immunohistochemical study.

BACKGROUND: The innervation of the oral mucosa has so far been studied mainly by histochemical and ultrastructural techniques. Only few studies have investigated the presence of neural proteins and neurotransmitters in human gingival mucosa. OBJECTIVE: The purpose of the present study was to evaluate the presence and distribution of neural structural and transmitter proteins in different areas of normal human oral mucosa. METHOD: Indirect immunofluorescence was employed on specimens taken from different mucosal regions (gingiva, lips, gums, palate). Both structural (low-affinity nerve growth factor receptor, NGFr; protein gene product 9.5, PGP 9.5) and neuropeptide markers (substance P; calcitonin gene-related peptide; vasoactive intestinal peptide, neuropeptide Y) were used. RESULTS: NGFr and PGP 9.5 intensely labelled both nerve fibres and selected epithelial cells, while neuropeptide immunoreactivity was scarcely expressed and exclusively localized in nerve fibres. CONCLUSIONS: Similarly in the distribution pattern and neurochemistry between oral and cutaneous innervation is apparent. Expression of NGFr could be relevant to the trophism of both the oral innervation and epithelium.