Twenty Years-Passed Case of Demineralized Dentin Matrix Autograft for Sinus Bone Augmentation - A First Case of Dentin Graft in Human.

This report presents a 20-year follow-up of a unique case involving a 46-year-old man who underwent sinus augmentation using autogenous demineralized dentin matrix (DDM) derived from non-functional teeth. Two extracted molars were crashed into granules, and then demineralized, freeze-dried, and stored at -80° for approximately one year. The stocked DDM granules were grafted into the sinus along with platelet-rich plasma, without the use of any membrane. Radiographic evidence at 1 month after the graft demonstrated successful harmonization of the augmented tissues with the atrophic maxilla, as shown by the increase in radiopaque dots. Computed tomography scans taken 5 months post-procedure revealed clear sinuses devoid of inflammation, significant bone formation, and a smooth buccal side outline. Bone biopsies at 5 months were carried out from the implant sites, and three fixtures were placed into the augmented bone. The biopsy tissues confirmed the presence of continuous trabecular bone linked with DDM, with new bone formation observed on it. A comparison of the dental X-ray images taken in 2009 and those captured in 2021 indicated minimal change in the outline of the new bone formed near the fixture-necks through the DDM graft and successful placement of dental implants was achieved. Based on this long-term case study, it is suggested that autogenous DDM graft could serve as a minimally invasive alternative for sinus bone augmentation without invasive bone harvesting and the associated morbidities. Key words:Atrophic maxilla, autograft, bone, dentin, demineralized dentin matrix, sinus augmentation, teeth.

Using the Oral Assessment Guide to Predict the Onset of Pneumonia in Residents of Long-Term Care and Welfare Facilities: A One-Year Prospective Cohort Study.

Appropriate oral health care, depending on oral assessments, reduces the onset of pneumonia. However, the relationship between risk evaluation using an oral assessment tool and pneumonia in residents of long-term care facilities has not been fully elucidated. In the present study, we aim to examine the relationship between the total scores of the Oral Assessment Guide (OAG) and the incidence of pneumonia after a one-year baseline study of residents in long-term care facilities. The settings for sampling include nine long-term care facilities in Hokkaido. At baseline, there were 267 study subjects. A total of 72 individuals dropped out and 11 individuals met the exclusion criteria. Therefore, the subject sample included 184 individuals. Among the subjects included in our analyses, eight individuals developed pneumonia (six males and two females). A multiple logistic regression analysis was performed with the risk factors for developing pneumonia. Evaluations were performed based on the odds ratio (OR) and 95% confidence interval (CI). We observed that the OR for pneumonia onset was 2.29 (CI: 1.27-4.14) after being adjusted for pneumonia risk factors. Therefore, it was suggested that the total scores of the OAG could be used to screen for the risk of pneumonia onset in residents of long-term care and welfare facilities.

Histological Evidences of Autograft of Dentin/Cementum Granules into Unhealed Socket at 5 Months after Tooth Extraction for Implant Placement.

The aim of this clinical case study was to observe biopsy tissues at 5 months after an autograft of a partially demineralized dentin/cementum matrix (pDDM) into a tooth-extracted socket exhibiting healing failure. A 66-year-old female presented with healing failure in the cavity for 2 months after the extraction (#36). Initial X-ray photos showed a clear remainder of lamina dura (#36), a residual root (#37), and a horizontal impaction (#38). The vital tooth (#38) was selected for pDDM. The third molar crushed by electric mill was decalcified in 1.0 L of 2.0% HNO3 for 20 min and rinsed in cold distilled water. The pDDM granules (size: 0.5-2.0 mm) were grafted immediately into the treated socket. X-ray views just after pDDM graft showed radio-opaque granules. At 5 months after pDDM graft, the surface of regenerated bone was harmonized with the mandibular line, and bone-like radio-opacity was found in the graft region. The biopsy tissue (diameter: 3.0 mm) at 5 months after pDDM graft showed that mature bone was interconnected with the remaining pDDM. The novel histological evidence highlighted that newly formed bone was connected directly with both dentin-area and cementum-area matrix of pDDM. We concluded that pDDM contributed to the regeneration of bone in the unhealed socket, and this regeneration prepared the socket for implant placement. Autogenous pDDM could be immediately recycled as an innovative biomaterial for local bone regeneration.

Image diagnosis models for the oral assessment of older people using convolutional neural networks: A retrospective observational study.

AIMS: The purpose of this study was to construct a model for oral assessment using deep learning image recognition technology and to verify its accuracy. BACKGROUND: The effects of oral care on older people are significant, and the Oral Assessment Guide has been used internationally as an effective oral assessment tool in clinical practice. However, additional training, education, development of user manuals and continuous support from a dental hygienist are needed to improve the inter-rater reliability of the Oral Assessment Guide. DESIGN: A retrospective observational study. METHODS: A total of 3,201 oral images of 114 older people aged >65 years were collected from five dental-related facilities. These images were divided into six categories (lips, tongue, saliva, mucosa, gingiva, and teeth or dentures) that were evaluated by images, out of the total eight items that comprise components of the Oral Assessment Guide. Each item was classified into a rating of 1, 2 or 3. A convolutional neural network, which is a deep learning method used for image recognition, was used to construct the image recognition model. The study methods comply with the STROBE checklist. RESULTS: We constructed models with a classification accuracy of 98.8% for lips, 94.3% for tongue, 92.8% for saliva, 78.6% for mucous membranes, 93.0% for gingiva and 93.6% for teeth or dentures. CONCLUSIONS: Highly accurate diagnostic imaging models using convolutional neural networks were constructed for six items of the Oral Assessment Guide and validated. In particular, for the five items of lips, tongue, saliva, gingiva, and teeth or dentures, models with a high accuracy of over 90% were obtained. RELEVANCE TO CLINICAL PRACTICE: The model built in this study has the potential to contribute to obtain reproducibility and reliability of the ratings, to shorten the time for assessment, to collaborate with dental professionals and to be used as an educational tool.

Architecture of connective tissue regenerated by enamel matrix derivative around hydroxyapatite implanted into tooth extraction sockets in the rat maxilla.

We investigated the architecture of periodontal ligament regenerated by an enamel matrix derivative (EMD, Emdogain®) coating on the surface of hydroxyapatite (EMD-HA). Immediately after extraction of the maxillary first molar in rats, HA alone or EMD-HA was implanted into the socket. At 5 days, and 2 and 4 weeks after implantation, the specimens were examined by light and transmission electron microscopy, and immunohistochemistry for periostin and matrix metalloproteinase (MMP)-13. Histological observations revealed a large number of fibroblasts and well-developed blood capillaries in the fibrous connective tissue surrounding EMD-HA at 5 days. Ultrastructural analysis showed a distinct difference in the architecture of the fibrous connective tissue. As compared with the poorly constructed architecture of HA, EMD-HA had an orderly alignment of fibroblasts and bundled collagen fibers, with some fibroblasts in the cytoplasm showing collagen fiber phagocytosis. Periostin immunoreactivity was observed in the fibrous connective tissue around EMD-HA at each time point, but was not seen in HA at 5 days and 2 weeks. MMP-13 immunoreactivity was intensely localized in fibroblasts at 5 days and 2 weeks in EMD-HA. The present results indicate that EMD may greatly contribute to a well-developed architecture accompanied by orderly alignment of fibroblasts and bundled collagen fibers, through accelerated induction of periostin, maintenance of fibrillogenesis, and degradation of collagen fibers by extracellular proteinase and phagocytosis.

Analysis of fracture surface of titanium-porcelain bonding by electron spectroscopy for chemical analysis.

Three commercially available porcelains bonded to titanium were evaluated to determine the weakest zone of the titanium-porcelain bonding structures. Tensile bond tests were performed for these specimens (NO, DU, and VI) and for Ni-Cr alloy-porcelain bonding samples that served as controls. The maximum bond strengths between porcelain and titanium and the Ni-Cr alloy subjected to different metal surface treatments were compared. Sand blasting effectively increased bond strengths in titanium-porcelain bonding materials. No statistically significant differences in the maximum bond strengths were found between the NO sample and a control; however, sample NO exhibited greater maximum bond strength than DU and VI samples. The bond strengths increased with increasing area fractions of porcelain failure on fracture surfaces. The weakest zones were investigated based on the oxygen chemical states determined by electron spectroscopy for chemical analysis, which include bridging oxygen (Si-O-Si), nonbridging oxygen (Si-O(-) M(+)), and titanium oxide (O(2-)) states. We concluded that the titanium oxide layer is the weakest zone of titanium-porcelain bonding structures.

Effect of low intensity pulsed ultrasound stimulation on sinus augmentation in rabbits.

OBJECTIVES: The objective of the present study was to evaluate the efficacy of low intensity pulsed ultrasound stimulation (LIPUS) and to determine the optimal frequency for enhancing bone regeneration in sinus augmentation using a rabbit model. MATERIAL AND METHODS: Thirty male rabbits underwent sinus augmentation. Two rectangular nasal bone windows were outlined bilaterally. LIPUS was applied at two different frequencies (1 MHz and 3 MHz) on experimental sites daily for 2, 4 and 8 weeks. Each histological area of the experimental and control sites was divided into upper and lower parts from the parietal region to a depth of 5 mm. Each area of new bone was measured. RESULTS: At 2, 4 and 8 weeks, the experimental sites in the 1 MHz group exhibited significantly more new bone growth than the control sites in both the upper and lower parts. When the upper and lower parts of each area were measured in combination there was a statistical difference between the test and control sites in the 1 MHz group at 2, 4 and 8 weeks; however, there were no statistical differences between the test and control sites in the 3 MHz group. CONCLUSIONS: The results suggest that clinical application of LIPUS for sinus augmentation may promote new bone formation, and that the effect of LIPUS for sinus augmentation at a frequency of 1 MHz was greater than at 3 MHz until 8 weeks after sinus augmentation.

Analysis of bacterial flora associated with peri-implantitis using obligate anaerobic culture technique and 16S rDNA gene sequence.

PURPOSE: To analyze and characterize the predominant bacterial flora associated with peri-implantitis by using culture techniques under obligate anaerobic conditions and 16S rDNA gene sequences. MATERIALS AND METHODS: Subgingival bacterial specimens were taken from 30 patients: control (n = 15), consisting of patients with only healthy implants; and test (n = 15), consisting of patients with peri-implantitis. In both groups, subgingival bacterial specimens were taken from the deepest sites. An anaerobic glove box system was used to cultivate bacterial strains. The bacterial strains were identified by 16S rDNA genebased polymerase chain reaction and comparison of the gene sequences. RESULTS: Peri-implantitis sites had approximately 10-fold higher mean colony forming units (per milliliter) than healthy implant sites. A total of 69 different bacterial species were identified in the peri-implantitis sites and 53 in the healthy implant sites. The predominant bacterial species in the peri-implantitis sites were Eubacterium nodatum, E. brachy, E. saphenum, Filifactor alocis, Slackia exigua, Parascardovia denticolens, Prevotella intermedia, Fusobacterium nucleatum, Porphyromonas gingivalis, Centipeda periodontii, and Parvimonas micra. The predominant bacteria in healthy implant sites apart from Streptococcus were Pseudoramibacter alactolyticus, Veillonella species, Actinomyces israelii, Actinomyces species, Propionibacterium acnes, and Parvimonas micra. CONCLUSION: These results suggest that the environment in the depths of the sulcus showing peri-implantitis is well suited for growth of obligate anaerobic bacteria. The present study demonstrated that the sulcus around oral implants with peri-implantitis harbors high levels of asaccharolytic anaerobic gram-positive rods (AAGPRs) such as E. nodatum, E. brachy, E. saphenum, Filifactor alocis, Slackia exigua, and gram-negative anaerobic rods, suggesting that conventional periodontopathic bacteria are not the only periodontal pathogens active in peri-implantitis, and that AAGPRs may also play an important role.

In vitro corrosion of dental Au-based casting alloys in polyvinylpyrrolidone-iodine solution.

The corrosion and tarnish behaviors of two Au-based casting alloys (ISO type 1 and type 4 Au alloys) and their constituent pure metals, Au, Ag, Cu, Pt, and Pd in a polyvinylpyrrolidone-iodine solution were examined. The two Au alloys actively corroded, and the main anodic reaction for both was dissolution of Au as AuI2(-). The amount of Au released from the ISO type 1 Au alloy was significantly larger than that from the ISO type 4 Au alloy (P<0.05). Visible light spectrophotometry revealed that the type 1 alloy exhibited higher susceptibility to tarnishing than the type 4 alloy. The corrosion forms of the two Au alloys were found to be completely different, i.e., the type 1 alloy exhibited the corrosion attack over the entire exposed surface with a little irregularity whereas the type 4 alloy exhibited typical intergranular corrosion, which was caused by local cells produced by segregation of Pd and Pt.

Effect of the quantity and quality of cortical bone on the failure force of a miniscrew implant.

This study examined the influence of the quantity and quality of cortical bone on the failure force of miniscrew implants. Twenty-six titanium alloy miniscrew implants (AbsoAnchor) 1.4mm in diameter and 5 or 7 mm long were placed in cross-sectioned maxillae (n = 6) and mandibles (n = 20) of human cadavers. Computed tomography imaging was used to estimate the cortical bone thickness and bone mineral density [total bone mineral density (TBMD, values obtained from cortical bone plus trabecular bone); cortical bone mineral density (CBMD, values obtained from only cortical bone)]. Maximum force at failure was measured in a shear test. Nanoindentation tests were performed to measure the hardness and elastic modulus of cortical bone around the miniscrew implants. The mean failure force of miniscrew implants placed in mandibles was significantly greater than that for implants in maxillae, and the bone hardness of mandibles was significantly greater than that of maxillae. The length of miniscrew implants did not influence the mean failure force in monocortical placement in the mandible. Cortical bone thickness, TBMD, CBMD, and bone hardness were significantly related to the mean failure force. CBMD was related to the mechanical properties of cortical bone. In conclusion, the quantity and quality of cortical bone greatly influenced the failure force of miniscrew implants.

In vitro corrosion of dental Ag-based alloys in polyvinylpyrrolidone iodine solution.

The corrosion and tarnish behaviors of three Ag-based alloys (Ag-Pd-Cu-Au alloy, Ag-In alloy, and Ag-Sn-Zn alloy) in polyvinylpyrrolidone iodine (povidone-iodine) solution were examined. The degree of tarnish was evaluated by visible-ray spectrocolorimetry. Corrosion potential measurements and analyses of corrosion products by X-ray diffractometry were carried out to elucidate the corrosion mechanism. The corrosion rate of the three Ag-based alloys in povidone-iodine solution at its practical concentration used as a gargle solution was so fast that the alloys tarnished within 10 seconds of immersion with the formation of AgI. Thermodynamic consideration and the results of surface analysis by X-ray diffractometry revealed that the main anodic and cathodic reactions were Ag + I(-)-->AgI + e- and I2 + 2e(-)-->2I- respectively.

Bone augmentation using rhGDF-5-collagen composite.

The aim of this study was to evaluate the effectiveness of local application of growth differentiation factor-5 (GDF-5)-collagen composite on bone augmentation on the rat calvaria. GDF-5-collagen composite is made from recombinant human GDF-5 (rhGDF-5) and purified bovine type I atelocollagen. The GDF-5 solution was mixed with 0.3% atelocollagen acid solution, and the mixture was lyophilized. The spongy lyophilized material was pressed into the shape of a minidisk to make the GDF-5-collagen composite. The GDF-5-collagen composite contained 1, 10, or 100-microg rhGDF-5. The control collagen composite contained 0-microg rhGDF-5. The GDF-5-collagen composite or control collagen composite was inserted beneath the calvarial periosteum of 4-week-old rats. At 3 weeks after implantation, the implants containing 1-microg rhGDF-5 had mostly induced new bone formation on the cranial side. In the implants containing 10- microg rhGDF-5, bone formation had proceeded to the center of the GDF-5-collagen composite from the periosteal and the cranial sides, and bone marrow was seen focally. The augmented bone showed a connected trabecular structure with abundant vascularization. The implants containing 100-microg rhGDF-5 were nearly entirely replaced by new bone with bone marrow, and the augmented bone was firmly connected with the original bone. Neither cartilage nor bone formation was found in the control collagen composite. Thus, we conclude that the GDF-5-collagen composite may be a superior biomaterial for bone augmentation and this composite could be useful as a local osteoinductive device.

Solcoseryl, a tissue respiration stimulating agent, significantly enhances the effect of capacitively coupled electric field on the promotion of bone formation around dental implants.

In the present study we examined the combined effect of application of a capacitively coupled electric field (CCEF) and the tissue respiration stimulating agent, Solcoseryl, on the promotion of bone formation around dental implants histologically and mechanically. After a dental implant was inserted into each femur of Japanese white rabbits, Solcoseryl (2 ml/kg) was administered intravenously in the ear vein and a CCEF was applied for 4 h per day for 14 days. The degree of bone formation on microscopic observation, bone contact ratio, bone surface area ratio, and the level of removal torque of the implant in the Solcoseryl- and CCEF-treated group were significantly higher than the respective value in the control group, which had not been treated with Solcoseryl nor CCEF. Thus, the combination of CCEF stimulation and Solcoseryl effectively promoted the formation of new bone. It is suggested that the clinical use of a combination of CCEF stimulation and Solcoseryl for dental implants promotes osseointegration.