In Japan, the number of retreatment of endodontically treated teeth is relatively high. This indicates the low success rate of root canal treatment. Here, we will discuss the “decision-making process for retreatment of endodontically-treated teeth” according to Friedmanʼs decision tree (1986) and will discuss the six points of diversion in terms of treatment options. The six points are:(1) restorability, (2) evaluation of the apical surgical periodontium, (3) accessibility of the root canal, mainly in situations where surgical endodontic treatment should be considered, (4) the quality of the radiographic root canal filling, which does not necessarily mean the overall quality of the root canal treatment, (5) the need for a new prosthesis, and (6) consideration of treatment options if there is any: (a) when root canal treatment is not successful, and (b) when root canal treatment is successful but a new prosthesis is needed--with emphases on problems peculiar to Japan. I also discussed five options which are nonsurgical retreatment, surgical retreatment, tooth extraction, follow-up, and referral to a specialist.

Regenerative medicine, which reconstructs tissues using three components, namely––stem cells, scaffolds, and bioactive factors––attempts to revive healthy tissue that has been lost. It is attracting attention as an advanced therapy that will dramatically improve the efficacy of drug therapies that have been ineffective with conventional biopharmaceuticals such as peptides and proteins. Regenerative medicine has been applied clinically, and its effectiveness has led to its inclusion in insurance coverage and its commercialization and has progressed from a “dream treatment” to a “real treatment”, and is advancing as a next-generation medical treatment. In the field of dentistry, bone regeneration is one of the most important issues in dentistry and has obtained good results, as bone loss often occurs due to bone resorption caused by periodontal disease, tumors, trauma, etc. The authors have been conducting clinical applications of regenerative medicine using bone marrow-derived stem cells and dental pulp stem cells, and have obtained favorable results. The indications include alveolar bone regeneration for dental implants, periodontal disease, residual bone defects, and distraction osteogenesis and we have applied bone regeneration to more than 100 patients, including a 13.5-year-long case. The results of this study revealed more rapid bone formation to bone regeneration than expected. This review will touch on the current status of bone regeneration and outline the process of using cell therapy, which is gentle on the body. The development of regenerative medicine in dentistry may lead to social contribution and to a paradigm shift in new treatment methods.

The number of elderly patients aged 65 years or older who visit a dental clinic on a daily basis increased from 21% in 1996 to 45% in 2009. Nowadays, probably half of the patients who visit a dental clinic on a daily basis are aged 65 years or older. Many of the elderly are sick with various diseases, such as lifestyle-related diseases, and the presence of such risk factors may lead to a sudden emergency in the patient's general condition during dental treatment. The probability of sudden change in a patient's general condition during dental treatment and required lifesaving treatment will certainly increase. Currently, 5 to 10 dental treatment related deaths are annually reported. The characteristics of deaths are heart failure and cerebrovascular disease in middle-aged and elderly patients, and choking in young children. Few of these cases are directly related to medication. As such, it is important to learn CPR and AED operation for adults, and CPR and removal of foreign objects from the airway for infants, in order to provide safe and secure dental treatment.

“Adhesion” is a phenomenon in which the surface of adherend and the adhesive material are united by chemical and/or physical force. The mechanisms of adhesion in the oral cavity are explained as resulting mainly from chemical bonds such as van der Waals forces and hydrogen bonds, and mechanical bonds. In order to obtain strong adhesive force, the adhesive materials are desired to have good wettability (i.e., lower contact angle) on the adherend surface and the surface tension at the interface between adherend surface and adhesive is required to be lowered. For the cases of adhesive bridge made of precious alloy, application of primer treatment with a sulfur-containing adhesive monomer to alloy surface is preferable. Besides, Rocatec treatment achieved by a tribochemical reaction to the zirconia surface is believed to be effective surface treatment to the adhesive bridge of zirconia. In addition, the adhesive resin cement, which has high mechanical strength and adhesive strength, is recommended to use in cementing the adhesive bridge.

[Introduction] The human maxillofacial morphology has gradually changed from ancient times to the present, and the greatest change is considered to be progressive reduction of the jaw bone size associated with decreases in masticatory force due to softening of the diet. It is a well-known that bone adapts to mechanical conditions and changes its morphology, but the association between masticatory force, especially dentition and number of teeth, and maxillofacial morphology has not been biomechanically established. In this study, we prepared three models of the maxillofacial skeleton and considered the causal relationship between mastication and morphological change in the jaw bone from the viewpoint of mechanical responses to changes in the dentition and number of teeth with a review of the literature. [Materials and Methods] To clarify mechanical behavior of the maxillofacial skeleton associated with changes in dentition, a normal occlusion model (analysis model 1), bilateral mandibular first molar defect model (analysis model 2), and bilateral first and second molar defect model (analysis model 3) were prepared from CT image data of actual patients, and analysis was performed using finite element analysis software (MECHANICAL FAINDER version 11.0, Research Center of Computational Mechanics, Inc., Tokyo, Japan). [Results] ① In normal occlusion, stress was distributed widely on the front surface of the maxillofacial skeleton, and occlusal force was transmitted to the upper and lower jaw bones and anterior parts of the facial cranium via the teeth. Also, dense convergence of horizontal components was observed near the midpoint between the bilateral orbits, which was in agreement with the anatomical reinforcement structure of the facial cranium. ② With loss of teeth, the burden on the remaining teeth, particularly the most distal molars, increased, stress in the anterior aspect of the maxillofacial skeleton centering around the nasal cavity and midpoint between the bilateral orbits and mandibular condyles increased relative to the areas immediately above the tooth defects, and the burden of the surrounding bone tissues including the temporomandibular joints increased with decreases of support in the molar region.

This is a remarkable case, in which an 86-year-old female patient with cirrhotic ascites judged to be in the terminal stage showed no effect of albumin replacement, but improvement of general conditions after recovery of masticatory function. The patient was finally admitted to our hospital (a chronic care hospital) after being hospitalized at two hospitals: first, the patient received treatment of pressure fracture at orthopedic hospital A, then to be treated for suspected heart failure due to decreased appetite and blood pressure, emergencytransferred to acute care hospital B, where CT scan revealed liver cirrhosis, large amount of ascites, and small amount of pleural effusion in both lungs. During admission to orthopedic hospital A, anorexia, chronic diarrhea, hypoproteinemia, pleural effusion, leg edema, and thrombocytopenia were observed. The patient was transferred to Acute Care Hospital B, where he was treated with fluid replacement, albumin, and ascites puncture, but continued to suffer from anorexia. Progression of debility and obsoletism due to decreased diet was expected; however, neither the patient nor her family wanted aggressive treatment or invasive examinations, and she was transferred to a chronic care hospital for continued care. After transfer, the patient complained that she could not eat with her dentures. We remounted and adjusted her dentures with an articulator to improve her masticatory function, and encouraged oral intake in cooperation with multiple professions. As a result, the patient's food intake recovered and stabilized. The patient's general condition stabilized and FIM improved with recovery of food intake, drainage of ascites using diuretics, and improvement of liver function, and he was discharged from the facility after about 10 months. The recovery of masticatory function plays an important role in QOL, and it was strongly suggested that efforts should be made to restore masticatory function even in patients who are judged to be in the terminal stage of life.

Patients with occlusal collapse tend to develop masticatory habits due to the abnormal position and tooth defects, which cause hypertonia and hyperlaxity of the muscles and changes in the mandibular position. Postural changes often occur, resulting in systemic symptoms such as headaches, stiff shoulders, back and knee pain. When performing occlusal reconstruction in such patients, we aim to improve and maintain oral and systemic symptoms by evaluating not only the oral cavity but also postural changes. According to the guidelines of the JapanProsthodontic Society, occlusal abnormalities not only affect the balance of the head and neck musculature, but also greatly affect the balance of the whole body, causing malalignment of the trunk, pain and movement disorders in the shoulders, arms, and backs, etc. On the contrary, various mandibular positions (mandibular rest position, terminal position of habitual jaw closure, muscle position, etc.) are affected by posture (head position), and may change to a certain extent. In addition to the diagnostic examination including intraoral photography, periodontal examination, evaluation of defects, radiographs, temporomandibular joint and dental cast evaluation, postural changes were also evaluated. The mandibular position was evaluated by comparing the Gothic arch tracing at the initial examination and upon fitting of the provisional resotrations. Registration of a madibular position with incorporation of postural analysis and the elimination of the tilt and rotation of the whole body to the greatest extent possible might contribute to the long-term stability of the mandibular position.

Clinical Case: An 82 years old male patient had dementia and cerebral infarction aftereffects. We repaired and adjusted his upper and lower complete dentures. According to the method of Kawahara Remounted Occlusal Adjustment, we evaluated his chewing ability by a food test and his dentures were remounted with a centric bite and adjusted for a simple full balanced occlusion. Result and discussion: He could eat well and a result of food test was improved. Also clinical findings and oriental medical evaluation indicated that his dementia, cerebral infarction after-effects and facial paralysis were decreased with time. Kawahara`s denture adjustment method improved not only the dietary habit but also QOL and dementia. Thus, a close relationship between dementia and occlusion was suggested from this clinical result.

A 48-year-old male patient presented a with a chief complaint of gingival swelling around 7 . He had lost bilateral mandibular canine teeth due to periodontal disease at around age 30, and had continued to lose teeth thereafter, but had low oral health consciousness, poor plaque control, and was a smoker until around age 40. The aforementioned tooth loss triggered a pronounced dental irregularity, and inflammation and a tendency toward deviated mastication began to appear. The patient's continuity of teeth and proper occlusal relationship were lost due to pathological tooth displacement in addition to poor plaque control, and occlusal trauma mainly to the molars was considered to have seemingly induced the occlusal collapse. The patient was diagnosed with generalized severe chronic periodontitis based on bone resorption throughout the jaws. Periodontal surgery was performed after improving the oral environment, starting with lifestyle modification and oral hygiene instruction. The patient was treated with autologous tooth transplantation, regenerative therapy, and localized orthodontic treatment to stabilize the mandibular position, to disperse occlusal forces, and to achieve a good occlusal relationship and together with continued SPT, the good progress has been observed.

The purpose of this article is to report the importance of taking into account the influence of perioral muscles on the wound site base on the cases, in which the bone width and height of the alveolar crest were insufficient for implant placement and bone augmentation was required using a membrane and bone grafting material. [Case 1] A monitored GBR was performed around implant site 1 , but the result was not what was wanted because the wound was not stabilized due to the force of the lips. [Case 2] A case in which the procedure was performed without consideration for the perioral muscles and the expected result was not obtained, but after eliminating the influence of the sternal collar, the treatment proceeded smoothly and the patient was in good condition for a long period of time. It was suggested that eliminating the force of the perioral muscles on the wound site, especially immediately after surgery, can make a difference in the success or failure of the treatment.