Aged ; Denture, Complete ; Female ; Follow-Up Studies ; Humans ; Hypercementosis ; therapy ; Mandibular Condyle

Periodontal disease is characterized by inflammation and subsequent loss and/or damage to tooth-supporting tissues such as bone, cementum, and periodontal ligament.Periodontal ligament and cementum are the key tissues in the initial process of regeneration following periodontal disease.Therefore, studies on cementoblasts, which form cementum are emphasized. It is still unclear which cells cementoblast differentiate from.This study was conducted under the hypothesis that PDL fibroblast can differentiate into either cementoblast or osteoblast depending on the conditions of surrounding tissue.Clinically, with excessive traction force of orthodontic appliances or excessive occlusion hypercementosis is observed, and this has been confirmed histologically.Consequently, activation of cementoblast can be expected in rats when mechanical stimuli are given to PDL fibroblast.Therefore, the purpose of this article is to prove that PDL fibroblast differentiates into cementoblast in rats under mechanical stimuli using histologic and molecular methods. In this study, twenty rats were given hard diet.Ten of them were sacrificed after 1 week, and the others were sacrificed after two weeks.Slides were made from tooth specimen, and they were studied under the microscope. In addition, PDL fibroblast and cementum from the extracted teeth were analyzed with Northern blotting. In histologic examination, as time passed, PDL fibroblast migrated to the dentin side, differentiated into cementoblast, and formed new cementum.In Northern blotting, it was found that mRNA expression of cementoblast-specific proteins such as BSP, OC, OPN, and type I collagen were more prominent in rats sacrificed after 2 weeks of hard-diet than rats sacrificed after 1 week. From these findings we can conclude that PDL fibroblast can differentiate into cementoblast under mechanical stimuli.We think that 'Rat Models' used in this study will be beneficial to future studies regarding cementoblast.
Animals ; Blotting, Northern ; Collagen Type I ; Dental Cementum ; Dentin ; Fibroblasts* ; Hypercementosis ; Inflammation ; Ligaments ; Orthodontic Appliances ; Osteoblasts ; Periodontal Diseases ; Rats* ; Regeneration ; RNA, Messenger ; Tooth ; Traction

BACKGROUND: The surgical extraction of the third molar is the most frequently encountered procedure in oral and maxillofacial surgery and is related with a variety of complications. This study examined the efficacy of intentional partial odontectomy (IPO) in the third molars which have no periapical lesions and are located near important anatomical structures such as inferior alveolar nerve. METHODS: Seven patients (four males, three females, 39.1 ± 11.6 years), who received IPO to reduce the risk of inferior alveolar nerve injury (IANI), were followed long-term. The treated teeth were horizontally impacted third molars in the mandibular left (n = 5) or mandibular right (n = 4) areas and were all ankylosed with the surrounding alveolar bone. During the IPO, the bone around the crown was removed to expose the crown, and then the tooth was resected at cement-enamel junction (CEJ). Any secondary trauma to the healthy root was minimized and remained intact after primary suture. RESULTS: The mean follow-up time was 63.2 ± 29.8 months, and all sites showed good bone healing after the crown removal. Also, sensory abnormality was not found in any patients after IPO. In one patient, the bone fragments erupted 4 months after IPO. In other patient, an implant placed on second molar site adjacent to the third molar that received IPO was explanted about 2 years after the patient’s persistent discomfort. CONCLUSIONS: In case where high risk of IANI exists, IPO may be chosen alternatively to surgical extraction to reduce the risk of nerve damage. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s40902-017-0127-z) contains supplementary material, which is available to authorized users.
Compassion Fatigue ; Crowns ; Female ; Follow-Up Studies* ; Humans ; Hypercementosis ; Male ; Mandibular Nerve ; Molar ; Molar, Third ; Surgery, Oral ; Sutures ; Tooth ; Tooth Ankylosis ; Tooth Extraction

The earliest reports of the use of electrical energy to directly stimulate bone healing seem to be in 1853 from England, the techniques involved the introduction of direct current into the non-united fracture site percutaneously via metallic needles, with subsequent healing of the defect. One endpoint of the periodontal therapy is to generate structure lost by periodontal diseases. Several procedural advances may support regeneration of attachment, however, regeneration of alveolar bone does not occur consistently. Therefore, factors which stimulate bone repair are areas for research in periodontal reconstructive therapy. Effects of cytokines or growth factors on bone repair are examples of such areas. Another one is electrical current which occurs in bone naturally, so that such bone may be particularly susceptible to electrical therapy. The purposes of this study were to observe the effects of electrical stimulation on the normal periodontium, to determine whether the electricity is the useful means for periodontal regeneration or not. Forty rats weighted about 100 gram were used and divided into 4 groups, the first group, there was no electrical stimulation with the connection of electrodes only. In the second group, there was stimulated by the 10 mA during 10 minutes per a day, in the third group was stimulated by the 25 mA , and the fourth by the 50 mA. At 3, 5, 10 and 15 days post-appliance , two rats in each group were serially sacrificed. and the maxillae and the mandible processed to paraffin, and the specimens were prepared with Hematoxylin-Eosin stain for the light microscopic evaluation. The results of this study were as follows : 1. There was the distinct reversal line on the lingual alveolar crest, whereas a little changes in the labial alveolar crest to the duration and amount of currents. 2. In 50 mA group, the cells were highly concentrated at the apex of anterior teeth, and was observed the necrotic tissue. In posterior root apex, the hypercementosis was appeared, and newly formed cementum layer has been increased continuously with the time. 3. The periodontal ligament fiber and Sharpey's fiber were arranged in order, and the bone trabeculae were increased as the experiment proceeded by, relatively the bone marrows were decreased. 4. In the pulp tissue, the blood vessels were increased with blood congestion in the experimetal specimens remarkably, and the dentinal tubules were obstructed . 5. The osteoblasts in alveolar bone proper had been showed highly activity, and also observed the formation of bone trabeculea. In the conclusion, it was suggested that the electrical stimulation has influence on the periodontium and the pulp tissue. However, there might be the injurious effects.
Animals ; Blood Vessels ; Bone Marrow ; Cytokines ; Dental Cementum ; Dentin ; Electric Stimulation* ; Electricity ; Electrodes ; England ; Estrogens, Conjugated (USP) ; Hypercementosis ; Intercellular Signaling Peptides and Proteins ; Mandible ; Maxilla ; Needles ; Osteoblasts ; Osteogenesis ; Paraffin ; Periodontal Diseases ; Periodontal Ligament ; Periodontium* ; Rats ; Regeneration ; Tooth