UV/ozone irradiation manipulates immune response for antibacterial activity and bone regeneration on titanium.

The immunomodulatory antibacterial activity and osteoimmunomodulatory properties of implantable biomaterials significantly influence bone regeneration. Various types of ultraviolet (UV) instrument are currently in use to greatly enhance the antibacterial activity and osteoconductive capability of titanium, it remains unclear how UV treatment modulates immune response. Compared to traditional UV treatment, the combination of low-dose ozone with UV irradiation is considered a new option to give benefits to surface modification and reduce the drawbacks of UV and ozone individually. Herein, the aim of this study was to elucidate the immune-modulatory properties of macrophages on UV/ozone-irradiated titanium that serve as defense against S. aureus and the crosstalk between immune cells and osteoblasts. Three different cell and bacteria co-culture systems were developed in order to investigate the race between host cells and bacteria to occupy the surface. In vitro immunological experiments indicated that UV/ozone irradiation significantly enhanced the phagocytic and bactericidal activity of macrophages against S. aureus. Further, in vitro and in vivo studies evidenced the favorable osteoimmune environment for osteogenic differentiation and bone formation. This research suggests vital therapeutic potential of UV/ozone irradiation for preventing the biomaterial-associated infections and achieving favorable bone formation simultaneously.

Decontamination of Titanium Surface Using Different Methods: An In Vitro Study.

Contamination of implants is inevitable during different steps of production as well as during the clinical use. We devised a new implant cleaning strategy to restore the bioactivities on dental implant surfaces. We evaluated the efficiency of the Finevo cleaning system, and Ultraviolet and Plasma treatments to decontaminate hydrocarbon-contaminated titanium disks. The surfaces of the contaminated titanium disks cleaned using the Finevo cleaning system were similar to those of the uncontaminated titanium disks in scanning electron microscopy and X-ray photoelectron spectroscopy analysis, but no obvious change in the roughness was observed in the scanning probe microscopy analysis. The rat bone marrow mesenchymal stem cells (rBMMSCs) cultured on the treated titanium disks attached to and covered the surfaces of disks cleaned with the Finevo cleaning system. The alkaline phosphatase activity, calcium deposition, and osteogenesis-related gene expression in rBMMSCs on disks cleaned using the Finevo cleaning system were higher compared to those in the ultraviolet and plasma treatments, displaying better cell functionality. Thus, the Finevo cleaning system can enhance the attachment, differentiation, and mineralization of rBMMSCs on treated titanium disk surfaces. This research provides a new strategy for cleaning the surface of contaminated titanium dental implants and for restoration of their biological functions.

Effect of Amelogenin Coating of a Nano-Modified Titanium Surface on Bioactivity.

The interactions between implants and host tissues depend on several factors. In particular, a growing body of evidence has demonstrated that the surface texture of an implant influences the response of the surrounding cells. The purpose of this study is to develop new implant materials aiming at the regeneration of periodontal tissues as well as hard tissues by coating nano-modified titanium with amelogenin, which is one of the main proteins contained in Emdogain®. We confirmed by quartz crystal microbalance evaluation that amelogenin is easy to adsorb onto the nano-modified titanium surface as a coating. Scanning electron microscopy, scanning probe microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy analyses confirmed that amelogenin coated the nano-modified titanium surface following alkali-treatment. In vitro evaluation using rat bone marrow and periodontal ligament cells revealed that the initial adhesion of both cell types and the induction of hard tissue differentiation such as cementum were improved by amelogenin coating. Additionally, the formation of new bone in implanted surrounding tissues was observed in in vivo evaluation using rat femurs. Together, these results suggest that this material may serve as a new implant material with the potential to play a major role in the advancement of clinical dentistry.

Erratum to: Analysis of factors associated with maintenance discontinuation in implant patients.

[This corrects the article DOI: 10.1186/s40064-015-1569-3.].

Analysis of factors associated with maintenance discontinuation in implant patients.

Maintenance following implant treatment is essential to ensure long-term stability. Accordingly, the objective of this study was to investigate the factors leading patients to discontinue maintenance following implant treatment. Among the 729 patients that underwent implantation at the Department of Oral Implantology, Osaka Dental University Hospital from January 2008 to December 2012, 41 patients were excluded from the study. Exclusion criteria comprised patients without a superstructure attachment, those who only underwent maxillary sinus floor augmentation procedures and those who discontinued visiting the hospital prior to superstructure attachment. Treatment was discontinued in 181 patients. The rate of discontinuation was 26.6 %. The odds ratio (OR) in the adjustment model was 1.552 (95 % CI 1.078-2.236) in males when compared with females. When compared with those who were 30-64 years old, the OR was 5.818 (95 % CI 3.017-11.220) in those 29 years old or younger and 1.561 (95 % CI 1.021-2.386) in those 65 years old or older. Moreover, when compared with those with a O'Leary's Plaque Control Record of all teeth and superstructures (PCR) level of 20 % or less following superstructure attachment, the OR was 2.113 (95 % CI 1.471-3.035) in those with a PCR level of 20 % or more following superstructure attachment. It is highly important to decrease maintenance discontinuation, especially in patients aged 29 years old or younger with a PCR level of 20 % or more following superstructure attachment. Moreover, a support system must be developed to enable patients with difficulties visiting the hospital to continue their maintenance program.

Effect of difference in occlusal contact area of mandibular free-end edentulous area implants on periodontal mechanosensitive threshold of adjacent premolars.

Implant treatment is believed to cause minimal invasion of remaining teeth. However, few studies have examined teeth adjacent to an implant region. Therefore, this study investigated the effect of occlusal contact size of implants on the periodontal mechanosensitive threshold of adjacent premolars. A cross-sectional study design was adopted. The Department of Oral Implantology, Osaka Dental University, was the setting where patients underwent implant treatment in the mandibular free-end edentulous area. The study population comprised of 87 patients (109 teeth) who underwent follow-up observation for at least 3 years following implant superstructure placement. As variables, age, sex, duration following superstructure placement, presence or absence of dental pulp, occlusal contact area, and periodontal mechanosensitive threshold were considered. The occlusal contact area was measured using Blue Silicone(®)and Bite Eye BE-I(®). Periodontal mechanosensitive threshold were measured using von Frey hair. As quantitative variables for periodontal mechanosensitive threshold, we divided subjects into two groups: normal (≤5 g) and high (≥5.1 g). For statistical analysis, we compared the two groups for the sensation thresholds using the Chi square test for categorical data and the Mann-Whitney U test for continuous volume data. For variables in which a significant difference was noted, we calculated the odds ratio (95 % confidence interval) and the effective dose. There were 93 teeth in the normal group and 16 teeth in the high group based on periodontal mechanosensitive threshold. Comparison of the two groups indicated no significant differences associated with age, sex, duration following superstructure placement, or presence or absence of dental pulp. A significant difference was noted with regard to occlusal contact area, with several high group subjects belonging to the small contact group (odds ratio: 4.75 [1.42-15.87]; effective dose: 0.29). The results of this study suggest an association between implant occlusal contact area and the periodontal mechanosensitive threshold of adjacent premolars. Smaller occlusal contact application resulted in an increased threshold. It appears that prosthodontic treatment should aim not only to improve occlusal function but also to maintain oromandibular function with regard to the preservation of remaining teeth.

Prognostic factor of mandibular condylar movement exercise for patients with internal derangement of the temporomandibular joint on initial presentation: preliminary report.

PURPOSE: The aim of this study is to examine the factors, which predict the effect of mandibular condylar movement exercise (MCME). MATERIAL AND METHODS: We investigated the efficiency of MCME and the significant difference in average age and the mean duration length of closed lock symptoms prior to the initial consultation in both success cases and failure cases in initial visiting. Seventy-four women aged between 19 and 75 (mean: 41.4) years were included in this study. RESULTS: On the initial visiting day, the success cases were 50 cases (67.6%) and the failures were 24 cases (23.4%). The average age of success cases is 38.0 years, and failure cases are 48.4 years. Duration of the lock in success cases is 35.3 days, and failure cases are 87.6 days. CONCLUSION: These results suggested that lower improvement rates thus correlated with increasing age with exercise. MCME is effective mouth-opening exercise in patients with a history of short duration of locking. In conclusion, age and duration of locking, it must become the important factor predict an effect MCME.

Bioactivity of nanostructure on titanium surface modified by chemical processing at room temperature.

PURPOSE: Recently, there has been considerable interest in finding novel applications and functions for existing dental materials. We found that, at room temperature and atmospheric pressure, titanium oxide spontaneously generates nanostructures very similar to the "nanotubes" created by TiO(2) sputtering. The aim of this study was to evaluate the ability of this surface to affect the cellular osteogenic differentiation response. METHODS: Titanium disks without and with a 'nanosheet' deposited on their surface were used as the control and test groups, respectively. Cell culture experiments were performed with SD rat bone marrow cells, which were seeded into microplate wells and cultured in media designed to induce osteogenic differentiation. We measured alkaline phosphatase (ALP) activity, osteocalcin (OCN) production, calcium deposition and Runx2 gene expression to assess the levels of differentiation. RESULTS: After 14 and 21 days, cellular ALP activity was significantly higher in the test group than in the control group. After 28 days, cells in the test group also showed significantly more calcium deposition and OCN production than those in the control group. There was significantly different expression of Runx2 mRNA in the test group compared to the control group after 3 days of culture. CONCLUSION: In conclusion, these data suggest that titanium implants modified by the application of nanostructures promote osteogenic differentiation, and may improve the biointegration of these implants into the alveolar bone.

Longitudinal research on the oral environment of elderly wearing fixed or removable prostheses.

PURPOSE: The purpose of this study was to investigate oral environmental risk factors involved in caries incidence in the elderly. We investigated the relationship between the oral environment factors of the elderly with both fixed prostheses and removable prostheses at baseline and at follow-up and examined time-course changes of each oral environmental factor by prosthesis type. MATERIALS AND METHODS: The subject group consisted 11 elderly patients with fixed prostheses and 11 who wore removable prostheses. We examined oral environmental factors by saliva tests. Five oral environmental factors were examined: the stimulated salivary flow rate, buffering capacity, and the counts of mutans streptococci (SM), lactobacilli (LB), and Candida (CA). We compared these factors for subjects with fixed prostheses and those wearing removable prostheses at baseline and at follow-up. Furthermore, 3-year changes in the factors of each oral environment were compared and evaluated. RESULTS: Significant differences were observed between the two groups in the salivary microbial counts of SM and LB at baseline and at follow-up. The LB counts increased in the Denture group during the 3-year period and significant differences were noted. CONCLUSIONS: We found that fixed prostheses are less cariogenic, and removable prostheses cause an increase in the cariogenic bacterial count. Regarding time-course changes by the type of prosthesis, the LB count tended to increase in the subjects with removable prostheses. The risk of caries due to a fixed prosthesis may be lower than that of removable prostheses.

Study on motor learning of sternocleidomastoid muscles during ballistic voluntary opening.

PURPOSE: Neck pain is one of the main symptoms of temporomandibular disorder. Muscle activity of the sternocleidomastoid muscle during occlusion has been clarified in recent years. We reported that when healthy individuals were instructed to chew rapidly, the activity of the sternocleidomastoid muscle responded to activity of the masseter muscle, however, during voluntary jaw opening, activity of the sternocleidomastoid muscle did not respond, but worked actively due to motor programming. The objective of the present study was to investigate the learning effects of repetitive training, that is, changes in activity mode of the neuromuscular system. MATERIALS AND METHODS: The sternocleidomastoid and the anterior belly of digastric muscles in 8 healthy male adults were analyzed. In response to acoustic stimulation, each subject was instructed to open their mouth as quickly and widely as possible a total of 30 times with a break between measurements. EMG-reaction times (RT) of the sternocleidomastoid and anterior belly of digastric muscles were measured, and the length of time from the start of EMG activity of agonist to the start of actual movement was measured. RESULTS: In all subjects, at first measurement, EMGRT of the sternocleidomastoid muscle did not precede that of the anterior belly of digastric muscle. With each measurement, the difference in EMG-RT between the sternocleidomastoid and the anterior belly of digastric muscles decreased, and in 6 of the 8 subjects, EMG-RT of the sternocleidomastoid muscle preceded that of the anterior belly of digastric muscle. CONCLUSION: Repetitive task movement alters the start times of muscular activities, and from the perspective of EMG kinesiology, motor learning effects were confirmed with maximum ballistic voluntary jaw opening.

Relationship of pressure pain thresholds between the masticatory muscles and styloid process. Part 2. Healthy subjects and patients with temporomandibular disorders.

PURPOSE: We previously reported correlations between the pressure pain threshold (PPT) at the styloid process, which represents individual pain sensitivity, and PPTs of the masticatory muscles in healthy subjects, and proposed the 95% confidence interval (95%CI) of the PPT at the styloid process as a reference range. In this study, we evaluated its usefulness as a reference range. METHODS: Serial changes in the PPT relative to the 95%CI were studied in 7 healthy subjects. Next, the determination of abnormal sites in the PPT relative to the 95%CI was studied in 7 patients with temporomandibular disorders (TMD). RESULTS: In the healthy subjects, the PPT remained within the 95%CI at all sites. Since the PPT deviated from the 95%CI at some sites in TMD patients, abnormal sites could be determined. CONCLUSION: The 95%CI of the PPT at the styloid process is useful as a means for the evaluation of muscle symptoms of TMD patients.

[Comparison of shortened dental arches with complete dental arches by clinical examinations].

PURPOSE: Recently, there have been reports in favor of avoiding prosthodontic intervention as Shortened Dental Arch (SDA) in Northern Europe. However, many of these reports were conducted through interviews and questionnaires, and so the evaluation of the results lacked objectivity. Thus, this research analyzed the clinical status of SDA. METHODS: For the selection of subjects, seven patients (average age: 59.3+/-13.2 years old) who had had the free-end missing on both sides of the lower dental arches for over five years were chosen as the SDA group. As the complete dental arch (CDA) group, seven patients (average age: 61.3+/-9.6 years old) who had no clinical defects in their masticatory function, and who had no missing teeth other than the third molar, were selected. Measurement items in this study were occlusal contact areas for the mandible premolar, center of force, occlusion time, and interdentium. The Mann-Whitney U test was used for statistical analysis and the significance level was assumed to be 5%. RESULTS: The results were as follows: 1) The occlusal contact area of the mandible premolar of SDA was significantly large. 2) The center of force of SDA was significantly forward. 3) The occlusion time of SDA had a tendency of prolongation. 4) Interdentium of 3 2 | 2 3, 4 3 | 3 4 and 5 4 | 4 5 of SDA were significantly wide. CONCLUSIONS: There were differences of clinical parameters between SDA and CDA in this study.

[Investigation of meals in health care service facility].

PURPOSE: Oral care and oral treatment are promoted in health care service facilities. However, disorders of eating, mastication and swallowing and care management of meal were get behind. This study investigated them in health care service facilities. METHODS: Doctors who work in facilities were screened for care management of meal using questionnaire. Inpatients were screened for age, meal menu, vertical stop, prosthetic treatment, satisfaction of mastication and difference of meal menu in the home and in the facility. RESULTS: Doctors and care workers have little understanding of mastication. Inpatients were satisfied to be able to eat rice in the home and in the facility. It is of paramount importance to have remaining teeth, to maintain vertical stop and to have prosthetic treatment. CONCLUSIONS: Education on the importance of mastication is needed. The research results show that new action and diagnosis method for deciding menus aiming at mastication of steamed rice need to be developed.

Development of implant movement checker for determining dental implant stability.

Noninvasive and nondestructive mobility assessment of dental implants is very important and useful for dental implantation diagnostic-aids. The development of implant movement (IM) checker based on microcontroller is presented in this paper. Data acquisition system and bender-type piezoelectric probe were used to improve measurement quality to the original tooth mobility (TM) tester. The adoption of a microcontroller and the use of a dental drill-sized measuring probe were sufficient in the reproducibility and reliability of the IM checker. When the implant was subjected to a constant force and amplitude, the acceleration of the model was detected using the measuring probe. The data acquisition system controlled for obtaining the appropriate acceleration signals based on the preload detection during measurement. Dental implant models of Molteno and Rigolac were made at different stiffness and were used to verify the reliability and validity of measurements. The values of measurements obtained by the IM checker were reliable and precise. The maximum error for perpendicular measurements was less than 12% measured by a new operator and decreased to 2% by an experienced operator. The IM checker was applied to monitor the stability of dental implantation, which compared the relative IM score of the new 5[see text] implant with the adjacent old 6 [see text] implant that had been used functionally for 3 years.

Development of dental implant movement (IM) checker for dental implant mobility assessment.

This study aimed at developing a dental implant movement (IM) checker for assessing quantitative dental implant mobility. The design of the instrument was based on the tooth mobility (TM) tester, which was previously developed by our group. The IM checker consists of a newly developed measuring probe which has the size of a typical dental drill so that it would be easy to measure at all regions of dental implants. The probe has a bimorph ceramics transducer for actuating an implant at constant frequency and force amplitude and for detecting acceleration response. A set of strain gauges were attached to the bimorph ceramics for detecting preload during measurement. A new digital data acquisition system was used to eliminate measurement artifacts mainly due to probe handling. The IM checker could discriminate the artificial dental implant models in the range of clinical tooth mobility M0 with variation less than 6%. The measuring time needed by five operators was less than 15 s. Accordingly, the IM checker has sufficient measuring reliability and therefore it could be introduced in dental clinics.

Wear resistance of hybrid composite resin for crown material by the two-body sliding test.

Comparative studies on two-body sliding wear resistance were performed between a hybrid composite resin and conventional light-curing composite veneering materials. This study investigated the wear resistance of hybrid composite resins compared with three composite resin veneering materials for 12%Au-Ag-Pd alloy, the wear resistance of four restorative materials opposed to hybrid composite resin, and the influence of surface characteristics on hybrid composite resins. Hybrid composite resin without heat-curing, which was compared with other composite resin materials exhibited inferior wear resistance, but hybrid composite resin mechanically polished after heat-curing exhibited the most superior wear resistance.