The Effectiveness and Practicality of a Novel Barrier Membrane for the Open Window in Maxillary Sinus Augmentation with a Lateral Approach, with Risk Indicators for Bone Graft Displacement and Bone Height Decrease: A Prospective Study in Humans.

Maxillary sinus augmentation with a lateral approach (MSA) is a well-established treatment. In this prospective study, we evaluated risk factors for postoperative bone graft displacement and reported the clinical application of long-term resorbable L-lactic acid/-caprolactone (PLA/PCL) as a barrier membrane to cover the open window in the lateral wall in MSA. Twenty-four patients underwent MSA according to the relevant criteria; CT data obtained before and 1 week (1 w) and 5-6 months (5 m) post-MSA, bone height changes, bone height reduction rates at 1 w and 5 m post-MSA, bone graft displacement measurements, and risk factors were examined. All patients showed bone height increments (p < 0.005). However, no difference was observed between 1 w and 5 m post-MSA. Bone graft displacement was observed in eight patients; the reduction rate from 1 w to 5 m post-MSA was 8.38% ± 4.88%. Sex, septa, maxillary sinus floor-palatal bone distance, and maxillary sinus floor-maxillary ostium distance were associated with bone graft displacement (p < 0.05). The height from the maxillary sinus floor to the palatal bone and the sinus angle influenced the augmentation degree (p < 0.05). The PLA/PCL membrane is compared favorably with other membranes and may be useful as a barrier membrane for the MSA open window.

Variations in vertical mucosal thickness at edentulous ridge according to site and gender measured by cone-beam computed tomography.

BACKGROUND: The vertical thickness of the peri-implant mucosa is associated with the amount of post treatment marginal bone loss. However, the variations in mucosal thickness at the different edentulous sites have been sparsely documented. The purpose of the study was to conduct a survey of the frequency distribution of variations in mucosal thickness at the different sites of the edentulous alveolar ridge and to compare them according to gender. Our study included 125 partially edentulous patients having a total of 296 implant sites. Cone-beam computed tomography (CBCT) scans were obtained by placing a diagnostic template with a radiopaque crown indicator on the ridge to determine the mucosal thickness at the crest of the alveolar ridge. RESULTS: The mucosal thickness was 3.0±1.3 mm in the maxilla, which was significantly greater than the mucosal thickness of 2.0±1.0 mm in the mandible (p<0.001). In both the maxilla and the mandible, the mucosa was the thickest in the anterior region, followed by the premolar and molar regions. Sites were further classified into two groups based on whether the mucosal thickness was greater than 2 mm. In the mandible, more than half of the sites showed a mucosal thickness of 2 mm or less. CONCLUSIONS: Although this study was a limited preoperative study, the vertical mucosal thickness at the edentulous ridge differed between the maxillary and mandibular regions. The majority of sites in the mandibular molar region had a mucosal thickness of less than 2 mm. Practitioners might be able to develop an optimal dental implant treatment plan for long-term biologic and esthetic stability by considering these factors.

Redox injectable gel protects osteoblastic function against oxidative stress and suppresses alveolar bone loss in a rat peri-implantitis model.

Dental implant surgery is a routine treatment in clinical dentistry. However, implant surgery is associated with an increased risk of bacterially induced peri-implantitis and the production of reactive oxygen species (ROS), with no established treatment. We recently designed a new redox injectable gel (RIG) containing nitroxide radicals for the treatment of peri-implantitis. Here, we investigated the antioxidative effect of RIG as a preventive therapy for ROS-associated peri-implantitis in a rat model of alveolar bone resorption and in vitro. In each rat, the maxillary first molar tooth was replaced with a screw-type implant, and rats were assigned to one of four groups: an implant alone, an implant with infection, implant with infection and treatment with nRIG (a non-nitroxide radical-containing injectable hydrogel) or RIG. We confirmed the long-term retention of RIG in the peri-implant region and found that RIG significantly protected the alveolar bone volume and decreased lipid peroxidation. In culture, we found that RIG restored osteoblast proliferation and differentiation in the presence of hydrogen peroxide (H2O2)-induced oxidative stress. Moreover, using a malondialdehyde assay of lipid peroxidation, we found that RIG suppressed oxidative stress in H2O2-treated rat osteoblasts. Overall, RIG is anticipated as a prophylactic treatment for peri-implantitis and may help preserve oral function. Statement of Significance 1. Implant surgery is associated with an increased risk of bacterially induced peri-implantitis and the production of reactive oxygen species (ROS). We designed a novel redox injectable gel (RIG) containing nitroxide radicals for the treatment of peri-implantitis. In this study, we investigated the antioxidative effect of RIG as a preventive therapy for ROS-associated peri-implantitis in a rat model and in vitro. 2. We showed that treatment with RIG reduces oxidative damage in a rat peri-implantitis model, protecting against bone resorption and a loss of bone density. We showed that RIG inhibits H2O2-mediated decreases in proliferation, osteoblast differentiation, and mineralization, and also against lipid peroxidation in vitro. Our results indicate that RIG has an antioxidative effect of peri-implantitis.

Correction of Mass Spectrometric Interferences for Rapid and Precise Isotope Ratio Measurements of Calcium from Biological Samples Using ICP-Mass Spectrometry.

Stable isotope compositions of calcium (Ca) provide useful information concerning metabolic alterations of Ca in human and animal bodies. For the measurements of Ca isotope ratio, great care must be taken for the mass spectrometric interferences on Ca isotopes (42Ca+, 43Ca+, and 44Ca+) from doubly charged strontium (Sr) ions (84Sr2+, 86Sr2+, and 88Sr2+). To obtain reliable stable isotope data of Ca, we developed a new correction technique for the mass spectrometric interferences by mSr2+ ions based on standard addition method. Addition of a small fraction of Sr onto a Ca solution shifts the measured Ca isotope ratios on a three-isotope diagram (i.e., δ44Ca and δ43Ca) along a mixing line defined by both the true Ca isotope ratio and the Sr isotope ratio. Therefore, the true Ca isotope ratio of a sample can be obtained as the crossover point of mass dependent fractionation line and the mixing line. With the present correction technique, precise and accurate isotope ratio measurements can be made on analyte solutions having a CSr/CCa ratio (concentration ratio) of 0.03, which is 6 times higher than the CSr/CCa ratio applicable to the conventional correction technique.

Low-Intensity Pulsed Ultrasound Prevents Development of Bisphosphonate-Related Osteonecrosis of the Jaw-Like Pathophysiology in a Rat Model.

We developed a rat model of bisphosphonate-related osteonecrosis of the jaw (BRONJ) by removing a maxillary molar tooth (M1) from ovariectomized rats after treatment with alendronate. To mimic periodontitis, some of the rats were administered Porphyromonas gingivalis (p. gingivalis) at the M1 site every 2 to 3 d for 2 wk. Rats pretreated with alendronate plus p. gingivalis showed delayed healing of socket epithelia, periosteal reaction of alveolar bone formation and lower bone mineral density in the alveolus above adjacent M2 teeth. These abnormalities were prevented by tooth socket exposure to 20 min/d low-intensity pulsed ultrasound (LIPUS), which restored diminished expression of RANKL, Bcl-2, IL-6, Hsp70, NF-κB and TNF-α messenger ribonucleic acids in remote bone marrow, suggesting LIPUS prevented development of BRONJ-like pathophysiology in rat by inducing systemic responses for regeneration, in addition to accelerating local healing. Non-invasive treatment by LIPUS, as well as low-level laser therapy, may be useful for medication-related osteonecrosis of the jaw patients.

13. Effect of Low-Intensity Pulsed Ultrasound (LIPUS) on Remote Bone Marrow in Rats With Healing Socket.

OBJECTIVE: We reported at the previous annual meeting that LIPUS treatment of the molar tooth sockets of retired breeder rats accelerated alveolar bone healing, and that associated humoral effects were seen with elevated blood flow. Namely, LIPUS induced VEGF/angiogenesis along with elevated baseline blood flow rate, which was further associated with a sudden depression of blood flow rate in the socket immediately after cessation of LIPUS treatment. Prior injection with EP4 PGE2 receptor antagonist, but not EP3 antagonist, abolished this LIPUS-induced depression, and topical application of PGE2 to the socket epithelium mimicked the LIPUS-induced depression. In fact, the serum level of PGE2 increased after LIPUS treatment, and significantly increased in the blood flow rate at remote sites on the foot dorsum and tail after 20 minutes. Therefore, in the current study, we examined the tibia bone marrow, which is likely to respond to circulating PGE2. METHODS: Right maxillary first molars were removed from retired female breeder rats in both the LIPUS and the control groups. LIPUS was applied extrabuccally to the socket every 24 hours for 2 weeks starting one day after extraction. Removed bone samples were fixed with 4% formaldehyde to prepare undecalcified frozen sections using Kawamoto's method for immunohistochemical or histochemical staining. Bone marrow samples dissected from the tibia were treated with RNAlater (Ambion) for later RT-PCR analysis. RESULTS AND DISCUSSION: Chemokine receptor CXCR4-positive bone marrow cells increased in the tibia of the LIPUS-treated rat. Together with ubiquitously expressed CXCL12(SDF-1), it is suggested that PGE2 released from the exposed socket is responsible for the recruitment, proliferation and mobilization of the precursors of bone forming cells. LIPUS is thought to exert humoral effects by recruiting bone marrow cells into the healing socket along with VEGF/angiogenesis induced by PGE2.

Novel antioxidative nanotherapeutics in a rat periodontitis model: Reactive oxygen species scavenging by redox injectable gel suppresses alveolar bone resorption.

The excessive production of reactive oxygen species (ROS) has been implicated in a variety of disorders, but to date, ROS scavengers have not been widely used for local treatment of inflammation, because they are rapidly eliminated from the inflamed site. We have designed a novel redox injectable gel (RIG) that is formed at 37 °C after disintegration of nano-assembled flower micelles allowing nitroxide radicals to act locally as specific ROS scavengers for the treatment of periodontitis. In the present study, we have confirmed retention of the RIG in the periodontal region, along with its antioxidant-related anti-inflammatory effects, and we have subsequently evaluated the inhibitory effect of the RIG against Porphyromonas gingivalis (P. gingivalis)-induced alveolar bone loss attributed to ROS. Alveolar bone loss was estimated by morphometry, gingival blood flow was measured using laser Doppler flowmetry, and osteoclast differentiation was evaluated by tartrate-resistant acid phosphatase staining. The results show that the RIG can inhibit P. gingivalis-induced bone loss by antioxidant-related anti-inflammatory actions, and this suggests that the RIG is a promising novel therapeutic agent for the treatment of P. gingivalis-induced periodontitis.

Effect of Ultraviolet Irradiation of the Implant Surface on Progression of Periimplantitis--A Pilot Study in Dogs.

OBJECTIVE: The objective of this study was to investigate morphologically the progression of periimplantitis around an ultraviolet (UV)-light-irradiated implant in dogs. MATERIALS AND METHODS: Pure titanium implants (3.3 mm in diameter and 8 mm long) were placed into dog jawbone bilaterally. Implants on one side were irradiated with UV light for 15 minutes using a photodevice immediately before placement (UV group), whereas those on the other side were not irradiated (non-UV group). Osseointegration was confirmed 90 days after implant placement by radiography. Experimental periimplantitis was induced by the application of dental floss over 90 days. Clinical and radiographic examination and micro-computed tomography (micro-CT) were performed after 90 and 180 days, and bone resorption was measured. The bone-implant interface in tissue sections was examined by light microscopy. RESULTS: Bone resorption around the UV-irradiated implant was less pronounced than around the non-UV-irradiated implant in the ligature-induced periimplantitis model. Tissue section images revealed no contact and partial destruction at the bone-implant interface. CONCLUSION: Within the limitations of this preliminary investigation, it is suggested that UV-light-irradiated implants suppress spontaneous progression of periimplantitis.

Micromolar sodium fluoride mediates anti-osteoclastogenesis in Porphyromonas gingivalis-induced alveolar bone loss.

Osteoclasts are bone-specific multinucleated cells generated by the differentiation of monocyte/macrophage lineage precursors. Regulation of osteoclast differentiation is considered an effective therapeutic approach to the treatment of bone-lytic diseases. Periodontitis is an inflammatory disease characterized by extensive bone resorption. In this study, we investigated the effects of sodium fluoride (NaF) on osteoclastogenesis induced by Porphyromonas gingivalis, an important colonizer of the oral cavity that has been implicated in periodontitis. NaF strongly inhibited the P. gingivalis-induced alveolar bone loss. That effect was accompanied by decreased levels of cathepsin K, interleukin (IL)-1ß, matrix metalloproteinase 9 (MMP9), and tartrate-resistant acid phosphatase, which were up-regulated during P. gingivalis-induced osteoclastogenesis. Consistent with the in vivo anti-osteoclastogenic effect, NaF inhibited osteoclast formation caused by the differentiation factor RANKL (receptor activator of nuclear factor κB ligand) and macrophage colony-stimulating factor (M-CSF). The RANKL-stimulated induction of the transcription factor nuclear factor of activated T cells (NFAT) c1 was also abrogated by NaF. Taken together, our data demonstrate that NaF inhibits RANKL-induced osteoclastogenesis by reducing the induction of NFATc1, ultimately leading to the suppressed expression of cathepsin K and MMP9. The in vivo effect of NaF on the inhibition of P. gingivalis-induced osteoclastogenesis strengthens the potential usefulness of NaF for treating periodontal diseases.

Three-dimensional X-ray micro-computed tomography analysis of polymerization shrinkage vectors in flowable composite.

The polymerization shrinkage of flowable resin composites was evaluated using air bubbles as traceable markers. Three different surface treatments i.e. an adhesive silane coupling agent, a separating silane coupling agent, and a combination of both, were applied to standard cavities. Before and after polymerization, X-ray micro-computed tomography images were recorded. Their superimposition and comparison allowed position changes of the markers to be visualized as vectors. The movement of the markers in the resin composite was, therefore, quantitatively evaluated from the tomographic images. Adhesion was found to significantly influence shrinkage patterns. The method used here could be employed to visualize shrinkage vectors and shrinkage volume.

Prolonged endochondral bone healing in senescence is shortened by low-intensity pulsed ultrasound in a manner dependent on COX-2.

To test whether mechanical loading produces faster healing in aged mice, fractured femurs of aged 1-year-old mice were subjected to low-intensity pulsed ultrasound (LIPUS), a treatment that is routinely used to help heal fractures in humans. Cyclooxygenase-2 knockout mice (COX-2(-/-)), which lack an immediate early mediator of mechanical stimulation, were also studied by histochemistry, microcomputed tomography and quantitative polymerase chain reaction to determine the role of COX-2. The healing in the aged COX-2(-/-) mice is slow during the endochondral bone remodeling (>30 d), a period generally prolonged in senescence. For aged wild-type mice, LIPUS halved the endochondral phase to about 10 d, whereas that was not the case for aged COX-2(-/-) mice, which showed no apparent shortening of the prolonged endochondral-phase healing time. Injecting prostaglandin E(2) receptor agonists, however, rescued the COX-2(-/-) callus from insensitivity to LIPUS. In conclusion, COX-2 is a limiting factor in the delayed endochondral bone healing and is induced by LIPUS, which normalizes healing rate to the wild-type level.

Image quality of film transparency printer output of digital dental radiographs.

OBJECTIVE: The purpose of this study was to evaluate the physical properties of the film transparency output of a printer and its potential use in dental radiography. STUDY DESIGN: A color printer (Sony UP-D70XR) was used to produce film transparencies of digital radiographs. A physical evaluation for the image quality was conducted including measurements of the image density reproducibility, the dose response function, the root mean square (RMS) granularity and the modulation transfer function (MTF). RESULTS: The characteristic curve of the hard copy image produced a nonlinear, sigmoid response for pixel value or x-ray absorbed dose. The RMS of the scan parallel direction was greater than that of the scan perpendicular direction in low density areas, but it reversed beyond density 1.3. The MTF of the scan perpendicular direction was superior to that of the scan parallel direction. CONCLUSION: It was suggested that further examination of the image qualities of this printer is worthwhile.

Structuring parameters for assessment of bone quality using a morphological filter and star volume analysis: structuring property in the cancellous bone of the human femoral head.

This study examines structuring parameters for the assessment of bone quality based on the relationship of bone strength to the trabecular structure or bone mineral density (BMD). Thirty-nine human cancellous bone blocks sampled from resected Ward's triangle area were investigated. The trabecular bone pattern of each bone block was binarized into its corresponding trabecular skeletal pattern using computed radiography with a morphological filter. Every binarized trabecular skeletal pattern was quantified to find the trabecular skeletal pixel percentage (SkP = volume parameter of trabecular skeletal signal component) and skeletal star volume (Vt = connection parameter of trabecular skeletal structure). After BMD and elasticity for each bone block was measured by dual X-ray absorptiometry and the breaking test, the correlations to SkP and Vt were determined. In addition, an attempt was made to detect changes of the trabecular structure in the Ward's triangle area of the femoral head after patients had received treatment for osteoporosis. This evaluation used the structuring parameters SkP and Vt. The results showed that the larger the BMD value, the greater the elasticity, although some samples with similar BMD values had considerably different elasticities. With increased Vt values the trabecular skeletal pattern that had horizontal skeletal elements orientated perpendicular to the loading direction showed higher elasticity. No correlation between SkP and either elasticity or BMD was observed in either the subset (sequential images of morphological filter) or sumset images (combined with subset images). On the other hand, the correlation coefficient between Vt and elasticity was similar to that between BMD and elasticity for subset image ( n = 6). For sumset images (3-6 and 4-7), the correlation coefficient of Vt was equal or higher than that of BMD and the connectivity of the trabecular skeletal structure was more closely linked to bone strength as compared to BMD. Therefore, it was concluded that because no high correlation could be detected between Vt and BMD, BMD and the connectivity of trabeculae are independently related to bone strength. In addition, this method was used to evaluate patients after treatment for osteoporosis, and noticeable changes were seen in the bone trabecular skeletal structure in the Ward's triangle area of the femoral head. In reference to these clinical images, variations in SkP and Vt were quantitatively assessed. These results suggest that the SkP and Vt obtained using computed radiography, morphological filter, and star volume analysis are useful structuring parameters for the assessment of bone quality.