THE JOURNAL OF THE ACADEMY OF CLINICAL DENTISTRY

Early implant bone loss after connection of the abutment

Satoshi Sekino

2015 Volume 35 Issue 1-2 Pages 13-19
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.13

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It is known that early crestal bone loss occurs after implant treatment. The success criteria in implant treatments include the marginal bone loss of 1.0-1.5mm in the first year after loading. The possible factors that influence the phenomenon are loading, micro leakage at the implantabutment connection and disconnection, the characteristic of abutment surfaces, platformswitching and thickness of peri-implant mucosa. For the early bone loss is observed without loading and also in one-piece implant system, which does not have implant-abutment interface, influences of the loading and micro-leakage cannot be clearly demonstrated. In the meantime, the platform-switching tends to result in lesser bone loss. The materials which cannot integrate to connective tissue, repeating connection and disconnection of abutment, thickness of mucosa influences the amount of early bone loss. These findings indicate that early bone loss around implants may be chiefly caused by the epithelial down growth after implant penetration into mucosa.

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Study of risk factors of the abutment screw fracture of titanium dental implant

Ayako Ando , Norimasa Nakamura, Hiroko Niimura , Sakae Nagasawa , Ich ...

2015 Volume 35 Issue 1-2 Pages 20-30
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.20

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We investigated a cause of a fractured abutment screw made of a Ti alloy, a physical and environmental factor. We observed the fracture surface of the abutment screw with a scanning electron microscope (SEM) and conducted stress analysis by three dimensional finite element method, and corrosion reaction experiment in a pseudo-oral environment. A pitting corrosion and fatigue destruction were discovered in the fracture surface of the abutment screw and accretion such as S was detected by the surface. A stress concentration was found in the same place as the broken part of abutment screw when stress was vertically loaded to marginal ridge region of implant superstructure in a three-dimensional finite element. In a corrosion test, stress was loaded to Ti alloy (Ti-6Al-4V) boards and dipped in Na₂SO₄ solution and isotonic sodium chloride solution at 37 degrees Celsius, and likewise dipped non-stressed Ti alloy boards in Na₂SO₄ solution. The dipping periods were 1week, 2weeks, 3weeks and 4weeks. Then, SEM images were examined and the element assay was conducted using an energy dispersive x-ray spectroscopy (EDS), but indication of corrosion such as pits was not found in any test pieces. Fatigue destruction stemmed from a pitting corrosion is believed to be the cause of the abutment screw fracture, but cause of pit initiation could not be identified.

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Masticatory muscle activities during mastication in dentition with molar intermediary missing

Tomofumi Sakamoto , Shintaro Minami , Masahiko Kikuchi

2015 Volume 35 Issue 1-2 Pages 31-37
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.31

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The first molars play an important role in grinding food, whereas the frequency of missing first molars is relatively high due to high caries prevalence. Thus, clinical cases with the intermediary missing mandibular first molar are often observed. In this study, masticatory muscle activities from the onset of chewing to the completion of swallowing were evaluated, using splints simulating three different arches, namely, a full lower dental arch and arches with the unilaterally and bilaterally intermediary missing mandibular first molar (s) in order to investigate the impact of intermediary missing molars on the muscle activities. As a result, the total amount of muscle activities and the number of chewing strokes increased as the number of the missing first molars on the splint increased. However, mean muscle activities required for one chewing stroke was almost constant irrespective of the splint type. In conclusion, it was suggested that the intermediary missing first molar caused increase of chewing strokes, and the bilateral first molar missing showed significant impact on the total muscle activities.

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Outline of splint treatment and its effect

—in consideration for occlusal force and myofunctional disorders at different life stages

Naoya Tachibana

2015 Volume 35 Issue 1-2 Pages 38-48
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.38

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Factors relevant to myofunctional disorders include life stages, malocclusion, attrition, tooth loss, intercuspal interference, functional mandibular shift, overbite due to attrition or tooth loss, lifestyle or dietary habit, excessive occlusal force due to nocturnal/awake bruxism, and various combinations of these. During the seven years from 2006 to 2013, 458 patients with toothache, dental hyperesthesia, or suspected myofunctional disorders, e.g., temporomandibular disorders received occlusal examinations using a sheet with special wash designed for a nocturnal bruxism analyzer. After the bite taking, the patients were provided splint treatment (based on the premise that the splint will be worn for a long term). This splint treatment aims to protect oral systems from excessive occlusal force of nocturnal bruxism, maintaining a position close to functional occlusion. 339 patients (74％) continued to use the splint, and among these patients, 83％ confirmed subsidence of chief complaints; 47％ admitted alleviation of other problems.

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Considerations for difficulty of orthodontic care based on cephalograms in orthodontic cares for patients in a growth phase

Toshio Yamagishi

2015 Volume 35 Issue 1-2 Pages 49-56
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.49

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In cases of malocclusions in a growth phase, it is necessary to start orthodontic treatment based on the growth prediction, in order to avoid a recurrence and extension of the treatment period. A number of studies using cephalograms have been reported, but precision to enable predictions and ease of operation are the key in clinical context. This article aims to explicate examination on the growth prediction and degree of difficulty of the treatment by overlaying lateral cephalograms of six patients with malocclusion on Sakamoto-based profilograms and observing positions of the condyles and backward and forward positions of the maxillary. As a result, the crossbite cases in a growth phase show better stability when the condylar position is close to the average (according to Sakamoto-based profiograms), but tend to be less stabile when the mandibular condyle was located forward and the maxillary located backward compared to the average. In the aspect of the growth prediction, a technique to link individual morphological characteristics appeared in the cephalogram with a future image is deemed useful.

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The importance of hospital communication

Natumi Onodera

2015 Volume 35 Issue 1-2 Pages 57-62
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.57

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Good team approach improves not only the quality of the clinical treatment, but also the medical safety management at the clinic. Fluid and accurate communication is particularly important. Verbal exchanges naturally make up the major part of day-to-day communication, but verbal communication alone is prone to errors and slipping one’s memory over time, hence the importance of documentation in written format. Written documents help us share and retain information and discussions at the meetings and sometimes make a draft for a manual where/when necessary. The resultant manual may resolve certain disagreements or miscommunication among staff members due to different backgrounds and experiences and in effect decrease critical mistakes. This will certainly be reflected in the quality of clinical care provided at the clinic. This article is to present a variety of meeting methodologies and tips (e.g. reporting, brainstorming, and discussions) and effective usage of IT devices and to explicate a PDCA (Plan-Do-Check-Action) cycle for organic and continuous improvement of communication and teamwork. Through ramification of intra-clinic communication we have come to learn the importance of securing a system and time to share information and day-to-day clinical experience and also the necessity to set an appropriate short-, mid-, and long-term goals for implementation of sound team medical care.

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Case report of comprehensive treatment for generalized chronic periodontitis with posterior bite collapse

Takuji Yoshida

2015 Volume 35 Issue 1-2 Pages 63-72
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.63

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Presented in this report is a case of generalized chronic periodontal patient; the patient’s periodontitis was diagnosed as a result of occlusal trauma and the posterior bite collapse was predicted if left untreated. In order to alleviate inflammation and inflammatory factors and stabilize the occlusion (by provision of adequate anterior guidance and posterior occlusal support), initial periodontal treatment, periodontal regenerative treatment, orthodontic treatment, and implant treatment were performed as part of the comprehensive treatment. As to stabilize the occlusion, properly fabricated provisional restoration was employed before the final restoration was set. Confirming that the symptom of periodontal disease subsided, the treatment was switched to supportive periodontal therapy. The periodontal condition is stable at the 6 year follow-up.

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Patient-oriented prosthetic treatment; a case report of a patient with a few teeth existing teeth and cardiovascular disorders

Akihiro Taniguchi

2015 Volume 35 Issue 1-2 Pages 73-81
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.73

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Presented in this article is a case of a patient with a chief complaint with a“ masticatory problem”. In consideration for the patient’s request for restoration of masticatory function, preservation of natural teeth, and a short treatment period, occlusal reconstruction with implant treatment was selected. Respecting the patient’s demand and systemic condition—the patient is considering a pacemaker surgery—the treatment plan was scrutinized, calculating the risks of the surgical procedure and the treatment period. As a result, selected for the maxilla was the attachment denture and for the mandible implant treatment to replace missing teeth in posterior region, and the surgery was carried out with an anesthetist on duty for the whole-body management. As at 5 years and 6 months post surgery, the condition of peri-implant and natural teeth were stable. Through this case, I have come to rethink about role of implant in occlusal reconstruction in everyday clinical context.

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[title in Japanese]

Koichiro Matsuo

2015 Volume 35 Issue 1-2 Pages 82-87
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.82

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Recognition and emotion of pain

Eiji Kondo

2015 Volume 35 Issue 1-2 Pages 88-93
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.88

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After entering the Central Nervous System (CNS) from the Peripheral Nervous System (PNS), pain information takes on an ascending path (lateral system and medial system) to be relayed at the thalamus and projected to the upper region of the CNS. Although the local ization of functions in the CNS has been described in the works of Broadman and Penfield, central pain modulation and recognition system were unclear until the recent advancement in imaging technology such as the fMRI (functional MRI imaging) which enabled the visual ization of the regions of brain activation in response to pain. In the present study, we focused primarily on the thalamus, cerebral cortex, amygdaloid body, anterior cingulate gyrus, nu cleus accumbens and hippocampus. We were able to locate the region of the brain at which pain is recognized, as well as the region at which emotional response to pain is established.

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[title in Japanese]

Tatsuya Kubo

2015 Volume 35 Issue 1-2 Pages 94-97
Published: April 25, 2015
Released on J-STAGE: June 17, 2016

DOIhttps://doi.org/10.14399/jacd.35.94

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