Bone is continuously destroyed by osteoclasts and reformed by osteoblasts to maintain bone volume and calcium homeostasis throughout the lifespan. Osteoclasts, the multinucleated cells that resorb bone, originate from monocyte/macrophage lineage cells. Osteoblasts are involved in osteoclastogenesis. Various hormones, cytokines and growth factors are involved in osteoclastogenesis, via interaction with osteoblasts. The research of “mechanism of osteoblastmediated osteoclast differentiation” directly links elucidation for bone mineral balance (coupling of bone tissue). In this review, we summarize the coupling mechanism regulated by osteoblastderived osteoclast differentiation factor (RANKL) and osteoprotegerin (OPG) which is a soluble decoy receptor for RANKL.

This paper is to report our clinical analysis on short implants. Method and material: This study focuses on screw type implant system with fixtures 8mm or shorter. The implants are either anodized or HA-coated. The system allows the options of both one-stage and two-stage procedures. Covered in this follow-up study are 104 implants in 75 patients, composed of 22 males and 53 females between 40 and 83 years old, averaging 62.45 years old (male at 65.85 and female at 61.04). Those subjects underwent operations at 4 facilities belonging to Kyoto Institute of Implantology between 1992 and 2011. Result: Of 104 short implants 8 have been lost, with the survival rate of 92.3％. Maxillary implants survived at the rate of 89.6％ with 5 losses out of 48, and mandibular implants 96.4％ with 2 losses out of 56. Those were mostly placed in the posterior regions. Analysis: Given the context of our super-aging society, the role short implants can achieve seems to be significant, considering their advantage in terms of surgical and mechanical stresses effecting on the elderly.

A suction-effective mandibular complete denture, which builds negative pressure on the interior surface by creating an effective seal around the entire border of the denture base with the oral mucosa, is resistant to lifting during mouth opening, and thus provides excellent clinical results in mandibular complete denture fabrication for fully edentulous patients. However, den ture suction cannot be achieved in all cases. A questionnaire survey was conducted to identify and examine potential risk factors for denture suction. Results: The extent of alveolar ridge resorp tion, amount of spongy tissue in the sublingual fold region, retromylohyoid fossa space available for denture base extension, shape of the retromolar pad, tongue retraction, and occlusal stability were identified as risk factors. The success rate of denture suction was significantly decreased when these factors were less favorable. There was no significant difference in the success rate with or without mandibular tori. The overall success rate of mandibular complete denture suc tion was 86.9％. Conclusion: These findings suggest that it is important to pay attention to the 6 risk factors during patient examination and diagnosis in order to achieve a high success rate of mandibular complete denture suction.

Background: Mandibular torus is one of exostosis which often develops lingually at mandibular molar region. It has been recognized as a product of long-continued occlusal force (mechanical stress) for years, because it is observed with clinical features such as attrition that suggests excessive local force. Few reports, however, have been published regarding the developmental mechanisms. With three-dimensional finite element analysis and immunohistochemical test, the developmental mechanisms are reviewed in this report. Methods: CT image data of patients whose mandible and maxillary teeth were thought to be in relatively normal contact, and thus whose occlusions were classified as Angle Class I malocclusion, were modeled using MECHANICAL FINDER version 5.0 (Research Center of Computational Mechanics, Inc., Tokyo) to evaluate mechanical behaviors of the mandibular body from stress distribution of a condition which represented centric occlusion (Case 1) and a condition which represented lateral movement with eccentric load (Case 2) selected from conditions that mimicked movements of masseter muscle. Also, tissues harvested from mandibular tori were immunohistochemically evaluated to examine the relationship between mechanical stress and bony growth. Results: The areas of stress concentration and mandibular tori formation were found to match by finite element analysis. Also, findings of immunostaining suggested involvement of mechanical stress with development of mandibular torus.

An elderly patient came to our clinic accompanied by his wife. The patient did not have any complaint, but his wife complained about his prolonged meal time. The patient has been a complete denture wearer for many years; he had a proud collection of dentures and brought four in addition to the one he was wearing at his second visit. Lack of the patient’s complaint is perhaps due to the fact that he was unaware of or had not accepted his own chewing difficulty. However, the loss of chewing ability became apparent upon a food test; he kept rolling the peanut on his tongue and seemed to have forgotten how to chew. Once balanced occlusion was established via remounting procedure, the patient regained chewing ability and ate a peanut without any assistance or instruction. The recovery of his sentience to chewing or biting brought him back his chewing ability. This case shows the importance of the food test and sharing a consensus on the patient’s chewing ability among the patient, caregiver, and the dentist—for “chewing and eating rehabilitation.”

We first examined by palatogram the speech articulation of a patient with chewing and articulation disorders. We then tried to recover chewing and articulation functions by applying gingivoplasty to the palate and adjusting the palatal surface of the maxillary complete denture. The patient visited our clinic with the main complaint of chewing and pronunciation difficulties due to the ill-fitting complete denture. After adjusting the denture by trailing its edge and applying tissue conditioning to the mucous membrane of the palates, we administered the treatment of upper and lower complete denture prostheses. Using palatogram, we closely examined the contact between the tongue and palate with the wax trial denture and determined the shape of the polished surface and the position of finish lines. The patient was able to articulately pronounce immediately after wearing a new denture thanks to the appropriately set finish lines and provision of S curve to the lingual flange. The resultant metal-based dentures presented high maintainability, stability, and good support . The patient echoed this; with the new well fitting dentures, he was able to speak and chew better.This was farther confirmed by the questionnaires on ingestible food, the score improving from 31.8 at the time of the initial diagnosis to 89.3 immediately after insertion of new dentures. Thus the oral environment was dramatically improved. The result suggests that the palatogram, which records the contact between tongue and palate, is a simple and useful diagnostic tool for evaluating the chewing and articulation functions of a patient with maxillary complete denture.