Conjugation of bone grafts with NO-delivery dinitrosyl iron complexes promotes synergistic osteogenesis and angiogenesis in rat calvaria bone defects.

Craniofacial/jawbone deformities remain a significant clinical challenge in restoring facial/dental functions and esthetics. Despite the reported therapeutics for clinical bone tissue regeneration, the bioavailability issue of autografts and limited regeneration efficacy of xenografts/synthetic bone substitutes, however, inspire continued efforts towards functional conjugation and improvement of bioactive bone graft materials. Regarding the potential of nitric oxide (NO) in tissue engineering, herein, functional conjugation of NO-delivery dinitrosyl iron complex (DNIC) and osteoconductive bone graft materials was performed to optimize the spatiotemporal control over the delivery of NO and to activate synergistic osteogenesis and angiogenesis in rat calvaria bone defects. Among three types of biomimetic DNICs, [Fe2(µ-SCH2CH2COOH)2(NO)4] (DNIC-COOH) features a steady kinetics for cellular uptake by MC3T3-E1 osteoblast cells followed by intracellular assembly of protein-bound DNICs and release of NO. This steady kinetics for intracellular delivery of NO by DNIC-COOH rationalizes its biocompatibility and wide-spectrum cell proliferation effects on MC3T3-E1 osteoblast cells and human umbilical vein endothelial cells (HUVECs). Moreover, the bridging [SCH2CH2COOH]- thiolate ligands in DNIC-COOH facilitate its chemisorption to deproteinized bovine bone mineral (DBBM) and physisorption onto TCP (ß-tricalcium phosphate), respectively, which provides a mechanism to control the kinetics for the local release of loaded DNIC-COOH. Using rats with calvaria bone defects as an in vivo model, DNIC-DBBM/DNIC-TCP promotes the osteogenic and angiogenic activity ascribed to functional conjugation of osteoconductive bone graft materials and NO-delivery DNIC-COOH. Of importance, the therapeutic efficacy of DNIC-DBBM/DNIC-TCP on enhanced compact bone formation after treatment for 4 and 12 weeks supports the potential for clinical application to regenerative medicine.

A secured internet of robotic things (IoRT) for long-term care services in a smart building.

Long-term care refers to any support, both medical and non-medical, provided to the elderly with a chronic illness or disability due to physical or mental conditions. Since the cost of long-term care insurance is not inexpensive, low-cost devices and sensors can be used to create medical assistance systems to reduce human maintenance costs. The requirement of security and privacy under healthcare information protection is a critical issue for internet of medical things (IoMT) data transmission. In this paper, we designed an IoMT security robot for a long-term care system. The goal of this IoMT security robot is to provide secure transmission of the residents' private information. It is composed of three layers, namely, collection, encryption, and transmission. The function of the IoMT security robot is to first collect data from the patient or the elderly, then provide efficient data encryption, and deliver secured data transmission mechanisms to send the valuable data to the cloud. This IoMT security robot also has a server authentication mechanism, and a support IoT and IoMT devices inspection function. Our evaluation results showed that even when we utilized a low power consumption device like Raspberry Pi, AES algorithm achieved an encrypt and decrypt of 100-100 K bytes under 9 ms, which is a lot better than ECC, which takes about 104 ms. Further, we found that the AES only takes 0.00015 s to decrypt 100 Bytes data, which is way faster than the ECC algorithm, which takes 0.09 s.

Composition Analysis and Feature Selection of the Oral Microbiota Associated with Periodontal Disease.

Periodontitis is an inflammatory disease involving complex interactions between oral microorganisms and the host immune response. Understanding the structure of the microbiota community associated with periodontitis is essential for improving classifications and diagnoses of various types of periodontal diseases and will facilitate clinical decision-making. In this study, we used a 16S rRNA metagenomics approach to investigate and compare the compositions of the microbiota communities from 76 subgingival plagues samples, including 26 from healthy individuals and 50 from patients with periodontitis. Furthermore, we propose a novel feature selection algorithm for selecting features with more information from many variables with a combination of these features and machine learning methods were used to construct prediction models for predicting the health status of patients with periodontal disease. We identified a total of 12 phyla, 124 genera, and 355 species and observed differences between health- and periodontitis-associated bacterial communities at all phylogenetic levels. We discovered that the genera Porphyromonas, Treponema, Tannerella, Filifactor, and Aggregatibacter were more abundant in patients with periodontal disease, whereas Streptococcus, Haemophilus, Capnocytophaga, Gemella, Campylobacter, and Granulicatella were found at higher levels in healthy controls. Using our feature selection algorithm, random forests performed better in terms of predictive power than other methods and consumed the least amount of computational time.

Prevalence and comparative analysis of the type IV secretion system in Aggregatibacter actinomycetemcomitan.

BACKGROUD/PURPOSE: Aggregatibacter actinomycetemcomitans has emerged as one of the aetiological agents in periodontal disease. Although Type IV secretion systems (T4SSs) are widely distributed in many bacteria, the genetic features and distribution of T4SSs in A. actinomycetemcomitans remain unclear. In this study, we investigated the prevalence of A. actinomycetemcomitans serotypes and their T4SSs in a Taiwanese population. METHODS: A comparative analysis of 20 A. actinomycetemcomitans genomes and their T4SSs deposited in GenBank was performed. One hundred subjects, including 20 periodontitis and 80 normal subjects, were enrolled and PCR identification of A. actinomycetemcomitans serotypes and T4SS genes were performed. RESULTS: Of 100 subjects, serotypes C (22%) and E (11%) were most common. In addition, T4SSs were distributed in all of the serotypes. The prevalence of T4SSs and their location in plasmids in periodontitis subjects were 1.28-2 fold higher but not significantly different compared to normal subjects. Of 20 A. actinomycetemcomitans genomes, only ten with complete T4SS modules could be detected, which was highly correlated with localized aggressive periodontitis (p < 0.1). Nine of ten T4SS modules were from periodontitis subjects. Phylogenetic analysis of 10 T4SSs in A. actinomycetemcomitans showed that they were clustered into two groups, T4SSAaI and T4SSAaII, with only T4SSAaI appearing in the Taiwanese subjects. CONCLUSION: A. actinomycetemcomitans strains with different serotypes carrying T4SSAaI are widely distributed in a Taiwanese population. This is the first report to show the distribution and detailed comparative genomics of T4SSs in A. actinomycetemcomitans.

Decreased Amount of Supporting Alveolar Bone at Single-Rooted Premolars Is Under Estimated by 2D Examinations.

The purpose of this study was to relate the proportions of bone-supported root length of a 2D view into the amount of a 3D bone-attached root surface area (BA-RSA) by using a dental laser scanner examination. White-light 3D scanning technology was used to probe 36 maxillary and 35 mandibular single-rooted premolars. The bone-supported height (BSH) and BA-RSA at designated levels (95-25%) were compared using statistical t tests. The 100% BSH and BA-RSA of the maxillary/mandibular premolars were 12.6 ± 1.60 mm/13.45 ± 1.47 mm (p < 0.05) and 220.78 ± 35.31 mm2/199.51 ± 26.33 mm2 (p < 0.01), respectively. Approximately 79-80%, 59-60%, and 35-36% premolars 2D BSH remained in comparison to 75%, 50%, and 25% 3D BA-RSA preservation, respectively. However, corresponding to a 75%, 50%, and 25% 2D BSH reserve, premolars retained 67-68%, 39-41%, and 15-17% 3D BA-RSA, respectively. When taking 1.0 mm connective tissue attachment into account, 60% 3D BA-RSA and 50% 2D BSH loss were noted at the 5.1-5.4 mm clinical attachment level. Assigning a periodontal prognosis and determining the severity of periodontitis for premolars with alveolar bone loss based on 3D's or 2D's measurement is inconsistent.

Mechanical response comparison in an implant overdenture retained by ball attachments on conventional regular and mini dental implants: a finite element analysis.

This study investigates the bone/implant mechanical responses in an implant overdenture retained by ball attachments on two conventional regular dental implants (RDI) and four mini dental implants (MDI) using finite element (FE) analysis. Two FE models of overdentures retained by RDIs and MDIs for a mandibular edentulous patient with validation within 6% variation errors were constructed by integrating CT images and CAD system. Bone grafting resulted in 2 mm thickness at the buccal side constructed for the RDIs-supported model to mimic the bone augmentation condition for the atrophic alveolar ridge. Nonlinear hyperelastic material and frictional contact element were used to simulate characteristic of the ball attachment-retained overdentures. The results showed that a denture supported by MDIs presented higher surrounding bone strains than those supported by RDIs under different load conditions. Maximum bone micro strains were up to 6437/2987 and 13323/5856 for MDIs/RDIs under single centric and lateral contacts, respectively. Corresponding values were 4429/2579 and 9557/5774 under multi- centric and lateral contacts, respectively. Bone micro strains increased 2.06 and 1.96-folds under single contact, 2.16 and 2.24-folds under multiple contacts for MDIs and RDIs when lateral to axial loads were compared. The maximum RDIs and MDIs implant stresses in all simulated cases were found by far lower than their yield strength. Overdentures retained using ball attachments on MDIs in poor edentulous bone structure increase the surrounding bone strain over the critical value, thereby damaging the bone when compared to the RDIs. Eliminating the occlusal single contact and oblique load of an implant-retained overdenture reduces the risk for failure.

Biomechanical comparison of a single short and wide implant with monocortical or bicortical engagement in the atrophic posterior maxilla and a long implant in the augmented sinus.

PURPOSE: The present study investigated the biomechanical interactions of a monocortically or bicortically engaged short and wide implant in the atrophic posterior maxilla and compared them to those of a long implant in the augmented sinus under different loading conditions via a nonlinear finite element (FE) approach. MATERIALS AND METHODS: Nonlinear FE models of a single implant in the posterior maxilla were constructed for the following conditions: (1) A monocortically engaged 5-mm-long, 7-mm-wide implant with an internal tripodgrip abutment connection (SIT-1), (2) a bicortically engaged 6-mm-long, 7-mm-wide implant with internal tripod-grip abutment connection (SIT-2), and (3) a 13-mm-long, 4.5-mm-wide implant with an internal-hexagon abutment connection in an augmented sinus. Simulated loads of 150 N were applied axially at the central fossa, off-axis at the buccal and palatal cusps, and toward the axis at the buccal and palatal cusps. RESULTS: The simulated results showed that loading condition was the main factor influencing the mechanical responses. Oblique occlusal forces increased implant stress and stress/strain values for the surrounding bone. The use of a long implant decreased the implant stress but increased the bone stress/strain values relative to a short and wide implant. The SIT-1 and SIT-2 implants increased the implant stress on average by 2.94 and 2.67 fold, respectively. However, the SIT-2 implant reduced the average stress and strain in bone by 37%, and the SIT-1 implant reduced average stress by 33% and average strain by 32%. CONCLUSIONS: Placement of a short and wide implant in the atrophic posterior maxilla may be a possible alternative for reducing the strain/stress on the surrounding bone. Detrimental off-axis loads should always be minimized to prevent extraordinarily high bone strain and stress.

Biomechanical analysis of the effects of implant diameter and bone quality in short implants placed in the atrophic posterior maxilla.

Short dental implant (SDI) placement has been proposed as an alternative to reduce the surgical risks related to the advanced grafting procedures. The aim of this study was to simulate the biomechanical behaviors and influences of SDI diameters under various conditions of bone quality by using a validated finite element (FE) model for simulation. The CT image and CAD system were combined to construct the FE models with 6 mm length SDIs for 6, 7 and 8 mm diameters under three types of bone qualities, from normal to osteoporotic. The simulated results showed that implant diameter did not influence the von Mises strains of bone under the vertical load. The bone strains increased about 58.58% in the bone of least density under lateral load. Lateral loads induced high bone strain and implant stress than vertical loads. The bone strains of 7 mm- and 8 mm-diameter short implants were not different, and both were about 52% and 66% compared to those of 6 mm-wide short implant under lateral loads. The von Mises stress of the SDIs and their compartments were all less than the yield stress of the material under vertical and lateral loads. SDIs with diameter of 7 mm or above may have better mechanical transmission in the same length at feasible condition. Attaining a proper occlusal scheme design or selective occlusal adjustments to reduce the lateral occlusal force upon the SDIs is recommended.

Sequelae of iatrogenic periodontal destruction associated with elastics and permanent incisors: literature review and report of 3 cases.

The purpose of this paper was to report 3 cases of localized aggressive periodontal bone destruction related to improper use of orthodontic elastic bands to close diastemas in permanent anterior teeth and to compare the results to previous studies. Some common signs and symptoms of this particular destruction were observed with these patients that had been previously reported when the comparisons of these cases were made. The patients usually experienced a painful sensation, and an isolated pyogenic-like granuloma appeared at the interdental area. Radiographs revealed localized periodontal destruction, with tooth extrusion and clinical crown divergence and radiographic root convergence; the two involved teeth moved simultaneously during mobility testing. Surgical intervention and treatment of the cases was described. The prognosis is usually decided by the severity of the condition, and many factors may influence the healing of treated cases.

Evaluation of stress induced by implant type, number of splinted teeth, and variations in periodontal support in tooth-implant-supported fixed partial dentures: a non-linear finite element analysis.

BACKGROUND: This study investigated the biomechanical interactions in tooth-implant-supported fixed partial dentures (FPDs) with variations in periodontal support, implant system, number of splinted teeth, and load type using the non-linear finite element (FE) approach. METHODS: The section contours of the alveolar bone, abutment teeth, and prosthesis were acquired using computed tomography (CT) and micro-CT to construct the FE models with normal periodontal support (NPS) and compromised periodontal support (CPS) containing one- and two-piece implants splinted to the first and second premolars. Realistic interface conditions within the implant system were simulated using frictional contact elements. The main effects for each level of investigated factors in terms of stress values and dissimilar mobility of natural teeth and the implant were computed for all models. RESULTS: Analytic results indicated that the load condition was the predominant factor affecting stress developed in the implant, bone, and prosthesis. Additionally, the oblique occlusal forces increased the stress values relative to that of axial analogs. A splinted system with a two-piece implant increased stress on the bone and decreased stress on the prosthesis compared to that of the one-piece implant. The splinted system with a CPS only slightly increased implant stress on the bone compared to that of the splint system with NPS. Splinting an additional tooth did not significantly impact stress values for the tooth-implant-supported FPD. CONCLUSIONS: A one-piece structure implant may be better than that of a two-piece structure implant in decreasing bone stress when a natural tooth is planned to connect with an implant. The factors of periodontal support and number of splinted teeth only slightly influenced stress in tooth-implant-supported FPDs.

Multi-factorial analysis of variables influencing the bone loss of an implant placed in the maxilla: prediction using FEA and SED bone remodeling algorithm.

The aim of this study was to investigate the interactions of implant position, implant-abutment connection and loading condition influencing bone loss of an implant placed in the maxilla using finite element (FE) analysis and mathematical bone remodeling theory. The maxilla section contours were acquired using CT images to construct FE models containing RS (internal retaining-screw) and the TIS (taper integrated screwed-in) implants placed in SC (along the axis of occlusal force) and RA (along the axis of residual ridge) positions. The adaptive strain energy density (SED) algorithm was combined with FE approach to study the preliminary bone remodeling around implant systems under different load conditions. The simulated results showed that the implant position obviously influenced the bone loss. An implant placed in the RA position resulted in substantially increased bone loss. Implant receiving a lateral load slightly increased bone loss compared with an axial load. The implant type did not significantly influence bone loss. It was found that buccal site suffered the most bone loss around the implant, followed by distal, lingual and mesial sites. The implant position primarily influenced bone loss and it was found most obviously at the buccal site. Implant placed along the axial load direction of a proposed prosthesis could obtain less bone loss around the implant. Attaining proper occlusal adjustments to reduce the lateral occlusal force is recommended in implant-bone-prosthesis system. Abutments of internal engagement with or without taper-fit did not affect the bone loss in the surrounding bone.

Factorial analysis of variables influencing mechanical characteristics of a single tooth implant placed in the maxilla using finite element analysis and the statistics-based Taguchi method.

The aim of this study was to determine the relative contribution of changes (design factors) in implant system, position, bone classification, and loading condition on the biomechanical response of a single-unit implant-supported restoration. Non-linear finite-element analysis was used to simulate the mechanical responses in an implant placed in the maxillary posterior region. The Taguchi method was employed to identify the significance of each design factor in controlling the strain/stress. Increased strain values were noted in the cortical bone with lateral force and an implant with a retaining-screw connection. Cancellous bone strain was affected primarily by bone type and increased with decreasing bone density. Implant stress was influenced mainly by implant type and position. The combined use of finite-element analysis and the Taguchi method facilitated effective evaluation of the mechanical characteristics of a single-unit implant-supported restoration. Implants placed along the axis of loading exhibit improved stress/strain distribution. The reduction of lateral stress through implant placement and selective occlusal adjustment is recommended. An implant with a tapered interference fit connection performed better as a force-transmission mechanism than other configurations.

Finite element analysis of biomechanical interactions of a tooth-implant splinting system for various bone qualities.

BACKGROUND: The splinting of an implant and tooth is a rational alternative in some clinical situations. The complex biomechanical aspects of a tooth-implant system are derived from the dissimilar mobility between the osseointegrated implant and the tooth. The aim of this study was to analyze the biomechanics in a tooth-implant splinting system for various bone qualities with different occlusal forces using non-linear finite element (FE) analysis. METHODS: A 3D FE model containing one Frialit-2 implant splinted to the mandibular second premolar and a simplified bony segment was constructed. Four bone quality categories were established by varying the elastic parameters assigned to the bone volumes. Contact elements (frictional surface) were used to simulate the realistic frictional interface condition within the implant system. The stress distributions in the splinting system were observed for four loading types. RESULTS: The simulated results indicated that the lateral occlusal forces significantly increased the implant system (sigmaI, max), alveolar bone (sigmaAB, max) and prosthesis (sigmaP, max) stress values when compared with the axial occlusal forces. The sigma1, max and sigmaP, max values did not exhibit significant differences between the four bone qualities. Conversely, the sigmaAB, max values increased with reduction in bone quality, in particular for type IV bone quality. The sigmaI, max, sigmaAB, max and sigmaP, max stress values were significantly reduced in centric or lateral contact situations once the occlusal forces on the pontic were decreased. CONCLUSIONS: This study suggests that implants connected to natural teeth should be used with caution in softer bone regions. Utilizing occlusal adjustment to minimize the occlusal loading force on the pontic could reduce the stress/strain values in the splinting system.

Mechanical interactions of an implant/tooth-supported system under different periodontal supports and number of splinted teeth with rigid and non-rigid connections.

OBJECTIVES: This study investigated the mechanical interactions of implant-teeth splinting systems under different periodontal supports and number of splinted teeth with rigid and non-rigid connectors using non-linear finite element (FE) approach. METHODS: Two FE models with normal and compromised periodontal supports containing a Frialit-2 implant splinted to the first and second premolars were constructed. Non-linear contact elements were used to simulate a realistic interface fixation within the implant system and the sliding function of the non-rigid connector. ANOVA was used to test for relative importance of the investigated factors and main effects for each level of the three investigated factors (periodontal supports, teeth splinting and connector designs) in terms of the stress values were performed. RESULTS: The simulated results indicated that the cross-interaction of the periodontal support and the splinting situation was a major factor affecting the stress value in alveolar bone. An additional splinting decreased the stress values of bone significantly for a compromised periodontal support. The individual factor of periodontal support also influenced the stress found in the alveolar bone (28%) and implant (72%), and the stress values increased when the periodontal support was reduced. Using different connectors affected the stresses found in bone (15%), implant (21%) and prosthesis (99%). The stress values of the implant and prosthesis increased, but were decreased in bone when the splinting system used non-rigid connectors. The mobility of natural teeth and the implant system between non-rigid and rigid connections showed only small differences. CONCLUSIONS: A non-rigid connector should be used with caution since it breaks the stress transfer and increases the unfavorable stress values in the implant system and prosthesis. The tooth/implant-supported system with an additional splinting is more efficient in compromised periodontal supports.