Clinical Evaluation of Short (6 mm) and Longer Implants Placed Side by Side in Posterior Partially Edentulous Area: A 3-Year Observational Study.

Background: Short implants have been proposed as an alternative solution for the rehabilitation of atrophic posterior region. Purpose: To compare the clinical outcomes between 6 mm short implants and conventional implants placed under similar conditions of bone quality and occlusal loading. Materials and Methods: Nine patients received atone 6 mm implant and one standard-length (8 mm length or longer) implants in a total of 10 partially edentulous areas. Implants were left submerged for 3-6 months healing period and the screw-retained splinted prostheses were delivered. When the provisional or final restoration was placed, and at each year after loading, standardized intraoral radiograph was taken for themarginal bone level (MBL) changes around the implants. Subsequently, the patients were recalled for the clinical examination evaluating the implant survival, sulcus bleeding index, suppuration, and the incidence of prosthetic complications at every 6 months after the definitive crown delivery. The observation period was continued to 3 years (mean follow-up was 3.4 ± 0.3 years) after functional loading. Results: Nine patients (10 short implants and 10 standard length implants) were selected in this study. Cumulative survival rates of the short implants and standard-length implants were 100% in both groups, and no biological and prosthetic complication were found in 3 years observation period. Cortical bone thickness of implant insertion sites was 1.39 ± 0.45 mm at short implants and 1.38 ± 0.69 mm at standard-length implants, and trabecular bone computed tomography values of implant insertion sites was 424.1 ± 290.1 at short implants and 410.9 ± 267.9 at standard-length implants. The MBL changes were -0.30 ± 0.71 mm at short implants and -0.19 ± 0.78 mm at standard-length implants at 3 years follow-up visit. No significant difference was found in the average of MBL changes between implant length. Conclusions: Within the limits of this study, it can be concluded that 6 mm short implants in a posterior edentulous region showed excellent results compared with conventional implants.

Gap junctional intercellular communication attenuates osteoclastogenesis induced by activated osteoblasts.

Osteoblasts participate in both bone formation through the synthesis of extracellular matrix and osteoclast differentiation through the expression of osteoclast differentiation factor. Osteoblasts communicate with each other via gap junctions (GJ), which enable small molecules, such as cAMP, to move to adjacent cells. Therefore, we focused on the role of cAMP propagation between osteoblasts via GJ in the osteoclast-supporting activity of osteoblasts. Osteoclast-supporting activity was evaluated by a co-culture system of osteoblasts with bone marrow-derived mononuclear cells. In this system, ablation of Gja1, a gene encoding connexin 43, in osteoblasts promoted osteoclastogenesis induced by prostaglandin E2 (PGE2). A phosphodiesterase 4 inhibitor increased both osteoclastogenesis and the intracellular cAMP concentration ([cAMP]i) in osteoblasts. Individual cell analysis of [cAMP]i in osteoblasts revealed different responses of each osteoblast to PGE2. Moreover, measurement of real-time [cAMP]i demonstrated cAMP movement from cell to cell via GJ. The inhibition of GJ resulted in the upregulation of [cAMP]i in osteoblasts stimulated by PGE2. This study suggested that GJ intercellular communication exerts protective effects against excess osteoclastogenesis via cAMP movement between osteoblasts.

Staged Sinus Floor Elevation Using Novel Low-Crystalline Carbonate Apatite Granules: Prospective Results after 3-Year Functional Loading.

The aim of this study was to evaluate clinical outcomes of staged sinus floor elevation (SFE) using novel low-crystalline carbonate apatite (CO3Ap) granules. Patients who needed SFE for implant placement were recruited into this clinical trial. A staged procedure (lateral window technique using CO3Ap granules, followed by implant placement after 7 ± 2 months) was employed in 13 patients. Bone-height increase and insertion torque values (ITVs) were assessed along with histological evaluation. The survival and success rates of 3-year functioning implants were also evaluated. Mean of bone-height increase after SFE using CO3Ap granules was 7.2 ± 2.5 mm and this increase allowed implant placement in all cases (17 implants). Mean of ITV was 25.1 ± 13.2 Ncm and primary stability was achieved successfully in all cases. Histological analyses revealed mature new bone formation (36.8 ± 17.3%) and residual CO3Ap granules (16.2 ± 10.1%) in the compartment after SFE. The survival and success rates after 3-year functional loading were 100% and no complications were found. These results clearly indicate the clinical usefulness of CO3Ap granules for SFE.

Efficacy of a novel membrane comprising a copolymer of L-lactic acid and glycolic acid in osteoblasts in vitro.

In guided bone regeneration (GBR), a barrier membrane is applied to provide a space for bone regeneration to promote cell adhesion, cell proliferation, and bone regeneration by inducing cell migration to the surface of the bone-deficient site. We prepared a non-woven absorbable membrane for GBR comprised of a copolymer of L-lactic acid and glycolic acid (PLLGA) using the dry spinning method. A thin and dense membrane comprising unsintered hydroxyapatite (uHA) and poly-L-lactic acid (PLLA) was used for comparison. Osteoblast TMS-12 cells were seeded onto the membranes, and cell adhesion and proliferation rates were examined. Calcification levels were quantified by Alizarin Red S staining after cell culture in calcification induction medium. Osteoblastic gene expression was examined by RT-PCR. Cell adhesion and proliferation rates and calcification on PLLGA membranes were significantly higher than those on uHA/PLLA membranes. PLLGA membranes upregulated osteogenic gene expression compared to on uHA/PLLA membranes. Non-woven PLLGA membranes may be useful in GBR for promoting bone formation and maturation.

Factors influencing the sinus membrane thickness in edentulous regions: a cone-beam computed tomography study.

BACKGROUND: During implant treatment in the maxillary molar area, maxillary sinus floor augmentation is often performed to ameliorate the reduced alveolar bone height attributable to bone remodeling and pneumatization-induced expansion of the maxillary sinus. However, this augmentation may cause complications such as misplaced implants, artery damage, and maxillary sinus mucosal perforation; infections like maxillary sinusitis; and postsurgical complications such as bone graft leakage and postoperative nasal hemorrhaging. To reduce the complications during maxillary sinus floor augmentation and postoperative infections, we performed retrospective investigations of various systemic and local factors that influence pre-operative sinus mucosal thickness (SMT) by using cone-beam computed tomography (CBCT). Subjects included patients who underwent maxillary sinus floor augmentation in an edentulous maxillary molar area with a lateral approach. Pre-operative SMT, existing bone mass, and nasal septum deviation were measured using CBCT images. Relationships between SMT and the following influencing factors were investigated: (1) age, (2) sex, (3) systemic disease, (4) smoking, (5) period after tooth extraction, (6) reason for tooth extraction, (7) residual alveolar bone height (RBH), (8) sinus septa, and (9) nasal septum deviation. Correlations were also investigated for age and RBH (p < 0.05). RESULTS: We assessed 35 patients (40 sinuses; 11 male, 24 female). The average patient age was 58.90 ± 9.0 years (males, 57.9 ± 7.7 years; females, 59.9 ± 9.4 years; age range, 41-79 years). The average SMT was 1.09 ± 1.30 mm, incidence of SMT > 2 mm was 25.0%, incidence of SMT < 0.8 mm was 50.0%, and the average RBH was 2.14 ± 1.02 mm. The factors that influenced SMT included sex (p = 0.0078), period after tooth extraction (p = 0.0075), reason for tooth extraction (p = 0.020), sinus septa (p = 0.0076), and nasal septum deviation (p = 0.038). CONCLUSIONS: Factors associated with higher SMT included male sex, interval following tooth extraction < 6 months, periapical lesions, sinus septa, and nasal septum deviation. Factors associated with SMT > 2 mm were sex and reason for tooth extraction, while factors associated with SMT < 0.8 mm were time following tooth extraction and nasal septum deviation. Despite the limitations of this study, these preoperative evaluations may be of utmost importance for safely conducting maxillary sinus floor augmentation.

Genetic and epigenetic regulation of osteopontin by cyclic adenosine 3' 5'-monophosphate in osteoblasts.

Osteopontin (OPN) is not only a marker of osteoblasts but it is also related to cancer progression and inflammation. The expression of OPN increases in response to inflammatory cytokines, hormones, and mechanical stress. Among them, cyclic-AMP (cAMP) elevating agents stimulate OPN expression in the presence of 1, 25-OH vitamin D3 (VD3). We aimed to clarify the mechanism by which cAMP enhances OPN expression in osteoblastic cells. The OPN promoter (-2335 to +76, OPNp2335) exerted a cell type specific response to forskolin (FK) and VD3. Sequential deletion analysis of OPNp revealed that the OPNp (-833 to +76) contained essential responsive regions to respond to cAMP signaling. In particular, both Vitamin D response element (VDRE, -758 to -743) and osteoblast-specific cis- acting element 2 (OSE2, -695 to -690) were essential for cAMP-mediated OPNp activity. The expression of vitamin D receptor (VDR), but not runt-related transcription factor 2 (Runx2), a nuclear receptor for OSE2, was induced by the treatment of the cells with FK. Although, VD3-induced OPNp activity was slightly enhanced in VDR-overexpressing osteoblasts, it reached the same level as that of osteoblasts induced by both VD3 and FK in the presence of histone deacetylase (HDAC) inhibitor. Moreover, we identified histone acetylation on the OPN promoter region by FK treatment. These results strongly suggest that OPNp activity is controlled by the cAMP signaling via genetic and epigenetic regulations.

Evaluation of maxillary sinus floor augmentation with the crestal approach and beta-tricalcium phosphate: a cone-beam computed tomography 3- to 9-year follow-up.

BACKGROUND: We performed maxillary sinus floor augmentation using the crestal approach and beta-tricalcium phosphate (ß-TCP) and a long-term evaluation using cone-beam computed tomography (CBCT). METHODS: Twenty-three patients (30 implants) underwent sinus floor augmentation using the osteotome technique. Subjects underwent CBCT imaging before surgery, immediately after surgery, and at follow-up (≥ 3 years after surgery). We measured the changes in height of the augmented sinus floor (SL), the augmented bone above apex of the implant (BH), and the implant length that projected into the sinus (IL). RESULTS: The mean SL decreased from 6.54 ± 1.51 (immediately after surgery) to 3.11 ± 1.35 mm (follow-up). The mean BH decreased from 3.17 ± 0.97 to - 0.25 ± 1.19 mm; the maxillary sinus floor in many implants was near the apex at follow-up. The SL at follow-up showed a strong correlation with the IL (p = 0.0057). CONCLUSIONS: Osteotome sinus floor elevation with beta-tricalcium phosphate was clinically effective. Cone-beam computed tomography analysis revealed that ≥ 3 years after surgery, the maxillary sinus floor was near the apex of the implant.

Application of low-crystalline carbonate apatite granules in 2-stage sinus floor augmentation: a prospective clinical trial and histomorphometric evaluation.

PURPOSE: The purpose of this study was to elucidate the efficacy and safety of carbonate apatite (CO3Ap) granules in 2-stage sinus floor augmentation through the radiographic and histomorphometric assessment of bone biopsy specimens. METHODS: Two-stage sinus floor augmentation was performed on 13 patients with a total of 17 implants. Radiographic assessment using panoramic radiographs was performed immediately after augmentation and was also performed 2 additional times, at 7±2 months and 18±2 months post-augmentation, respectively. Bone biopsy specimens taken from planned implant placement sites underwent micro-computed tomography, after which histological sections were prepared. RESULTS: Postoperative healing of the sinus floor augmentation was uneventful in all cases. The mean preoperative residual bone height was 3.5±1.3 mm, and this was increased to 13.3±1.7 mm by augmentation with the CO3Ap granules. The mean height of the augmented site had decreased to 10.7±1.9 mm by 7±2 months after augmentation; however, implants with lengths in the range of 6.5 to 11.5 mm could still be placed. The mean height of the augmented site had decreased to 9.6±1.4 mm by 18±2 months post-augmentation. No implant failure or complications were observed. Few inflammatory cells or foreign body giant cells were observed in the bone biopsy specimens. Although there were individual differences in the amount of new bone detected, new bone was observed to be in direct contact with the CO3Ap granules in all cases, without an intermediate layer of fibrous tissue. The amounts of bone and residual CO3Ap were 33.8%±15.1% and 15.3%±11.9%, respectively. CONCLUSIONS: In this first demonstration, low-crystalline CO3Ap granules showed excellent biocompatibility, and bone biopsy showed them to be replaced with bone in humans. CO3Ap granules are a useful and safe bone substitute for two-stage sinus floor augmentation.Trial Registration: ICTRP Identifier: JPRN-UMIN000019281.

Vertical ridge augmentation using a porous composite of uncalcined hydroxyapatite and poly-DL-lactide enriched with types 1 and 3 collagen.

BACKGROUND: Previous studies have shown that porous composite blocks containing uncalcined hydroxyapatite (u-HA; 70 wt%) with a scaffold of poly-DL-lactide (PDLLA, 30 wt%) are biodegradable, encourage appropriate bone formation, and are suitable for use as a bone substitute in vertical ridge augmentation. The present study aimed to accelerate osteogenesis in vertical ridge formation by adding types 1 and 3 collagen to the u-HA/PDLLA blocks and assessing the effect. MATERIAL AND METHODS: The bone substitute in the present study comprised porous composite blocks of u-HA (70 wt%) with a PDLLA (27-29 wt%) scaffold and enriched with types 1 and 3 collagen (1.7 ~ 3.4 wt%). The control blocks were composed of u-HA (70 wt%) and PDLLA (30 wt%). The materials were formed into 8-mm diameter, 2-mm high discs and implanted onto the cranial bones of six rabbits. The animals were sacrificed 4 weeks after implantation, and histological and histomorphometrical analyses were performed to quantitatively evaluate newly formed bone. RESULTS: New bone formation occurred with both block types, showing direct contact with the original bone. Mean ± standard deviation bone formation was significantly greater in the experimental blocks (25.6% ± 4.8%) than in the control blocks (17.0% ± 4.7%). CONCLUSIONS: Histological and histomorphometrical observations indicated that new bone was formed with both block types. The u-HA/PDLLA block with types 1 and 3 collagen is a more promising candidate for vertical ridge augmentation than the u-HA/PDLLA alone block.

Maxillary Sinus Floor Augmentation Using Low-Crystalline Carbonate Apatite Granules With Simultaneous Implant Installation: First-in-Human Clinical Trial.

PURPOSE: Carbonate apatite (CO3Ap), an inorganic component of human bone, can be fabricated in chemically pure form from calcium carbonate block via a dissolution-precipitation reaction. A first-in-human clinical trial was conducted in which low-crystalline CO3Ap granules were evaluated for safety and efficacy in sinus floor augmentation and simultaneous implant installation. MATERIALS AND METHODS: Procedures were performed in 8 patients (9 implants) with 2 granule sizes: small (300 to 600 µm) and medium (600 to 1,000 µm). Panoramic radiographic assessment was performed immediately after augmentation, 7 ± 2 months after augmentation, 6 ± 2 months after prosthetic loading, and 12 ± 2 months after prosthetic loading. RESULTS: Postoperative healing was uniformly uneventful, with no abnormal bleeding, pain, or swelling, and all implants achieved successful osseointegration. The mean residual maxillary molar bone height was 5.2 ± 0.8 mm preoperatively and increased to 14.0 ± 1.9 mm after augmentation. Implants 9.0 to 11.5 mm in length were placed. The post-augmentation height decreased to 12.4 ± 1.3 mm at 7 ± 2 months; after prosthetic loading, it decreased to 11.9 ± 0.8 mm at 6 ± 2 months and 11.7 ± 0.6 mm at 12 ± 2 months. No abnormal bone resorption of the augmented areas was observed, and bone height supporting the implants was maintained. The overall implant survival rate was 100%, with no implant failures or complications during the first year. CONCLUSIONS: Low-crystalline CO3Ap granules were useful and safe for sinus floor augmentation and simultaneous implant installation, providing a promising bone substitute for dental implant surgery.

Guided bone regeneration using a hydrophilic membrane made of unsintered hydroxyapatite and poly(L-lactic acid) in a rat bone-defect model.

The effectiveness of a previously developed unsintered hydroxyapatite (uHA) and poly(L-lactic acid) (PLLA) hydrophilic membrane as a resorbable barrier for guided bone regeneration (GBR) was evaluated. Critical-size 8-mm diameter bone defects were surgically generated in the parietal bones of 24 12-week-old male Wistar rats, which were then divided into three groups in which either a uHA/PLLA or a collagen membrane or no membrane (control) was placed onto the bone defect. Following sacrifice of the animals 2 or 4 weeks after surgery, bone defects were examined using microcomputed tomography and histological analysis. Bone mineral density, bone mineral content, and relative bone growth area values 2 or 4 weeks after surgery were highest in the uHA/PLLA group. Four weeks after surgery, the relative bone growth area in the uHA/PLLA group was larger than that in the collagen group. The resorbable uHA/PLLA membrane is thus potentially effective for GBR.

Effective removal of calcified deposits on microstructured titanium fixture surfaces of dental implants with erbium lasers.

BACKGROUND: Recently, the occurrence of peri-implantitis has been increasing. However, a suitable method to debride the contaminated surface of titanium implants has not been established. The aim of this study was to investigate the morphologic changes of the microstructured fixture surface after erbium laser irradiation, and to clarify the effects of the erbium lasers when used to remove calcified deposits from implant fixture surfaces. METHODS: In experiment 1, sandblasted, large grit, acid etched surface implants were treated with Er:YAG laser or Er,Cr:YSGG laser at 30 to 60 mJ/pulse and 20 Hz with water spray. In experiments 2 and 3, the effects of erbium lasers used to remove calcified deposits (artificially prepared deposits on virgin implants and natural calculus on failed implants) were investigated and compared with mechanical debridement using either a titanium curette or cotton pellets. After the various debridement methods, all specimens were analyzed by stereomicroscopy (SM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). RESULTS: Stereomicroscopy and SEM showed that erbium lasers with optimal irradiation parameters did not influence titanium microstructures. Compared with mechanical debridement, erbium lasers were more capable of removing calcified deposits on the microstructured surface without surface alteration using a noncontact sweeping irradiation at 40 mJ/pulse (ED 14.2 J/cm2 /pulse) and 20 Hz with water spray. CONCLUSION: These results indicate that Er:YAG and Er,Cr:YSGG lasers are more advantageous in removing calcified deposits on the microstructured surface of titanium implants without inducing damage, compared to mechanical therapy by cotton pellet or titanium curette.

Histological and Histomorphometrical Determination of the Biogradation of ß-Tricalcium Phosphate Granules in Maxillary Sinus Floor Augmentation: A Prospective Observational Study.

INTRODUCTION: We have recently used highly pure ß-TCP (beta-tricalcium phosphate) as the bone grafting material to avoid highly invasive autogenous bone grafting. We evaluated the osseoconduction potential of highly pure ß-TCP in sinus augmentation surgery treatment. MATERIALS AND METHODS: The study group comprised 13 patients who underwent maxillary sinus floor augmentation with ß-TCP alone. Seven patients underwent sinus augmentation and implant placement simultaneously. Six patients were treated with a staged approach. Six months after surgery, specimens were obtained from 7 patients (for lateral biopsy) and 6 patients (for vertical biopsy). RESULTS: Histological and histomorphometrical analysis showed a mean bone proportion of 30.8% (vertical) and 12.0% (lateral) for new bone formation and good integration of the ß-TCP. New bone formation was lower in the lateral biopsy specimens than in the vertical. CONCLUSION: Highly pure ß-TCP is a safe bone-grafting material with superior osteoconductive properties. Histologic and radiographic examinations indicate that ß-TCP is slowly resorbed, which results in unresorbed graft material remaining even 6 months after the procedure, and that new bone replacement occurs slowly for approximately 1 year.

A diversity of peri-implant mucosal thickness by site.

OBJECTIVES: The objective of this study was to examine peri-implant mucosal thickness at different sites of peri-implant crevice around 70 implants placed in 35 patients. MATERIAL AND METHODS: The peri-implant mucosal thickness was defined as distance of the peri-implant mucosal margin and the coronal edge of bone/implant contact and measured using the cast models and dental radiography. RESULTS: The overall mean peri-implant mucosal thickness was 3.6 ± 1.4 mm, wherein maxillary anterior implants, maxillary posterior implants and mandibular posterior implants had significantly different dimensions of median thickness of 4.25, 3.75 and 3.0 mm, respectively. Furthermore, the mesial and distal sites of those positioned implants measured unevenness in the thickness especially in the maxillary posterior region with statistical significance. CONCLUSION: The proposed methodology to evaluate peri-implant mucosal thickness measured with a big variation from overall 3.6 mm with a big variation from 1.6 to 7.0 mm in healthy volunteers. And significant difference was found in the depth among the three regions and, statistically, dispersion of individual peri-implant mucosal thickness resulted in lack of consistency. Although dental implants have been well developed, predictable and prevailing prosthetics, onset of peri-implantitis might be inevitable in some cases. Therefore, establishment of a standardized dimensional diagnosis of peri-implant tissues followed by pathologic ascertainment could be taken into account for the prevention or curing of peri-implantitis.

Differences in knowledge related to dental implants between patients with and without a treatment history of dental implants.

OBJECTIVE: This aim of this study was to investigate the differences between patients with and without a treatment history of dental implants by use of a questionnaire survey in order to determine the information that is required for patients undergoing dental implants. MATERIALS AND METHODS: The questionnaires were given to 4512 patients who visited the Tokyo Medical and Dental University Hospital for oral implants between January 2012 and December 2014, and 2972 (66%) valid questionnaires were collected. RESULTS: There were 857 patients with a treatment history of dental implants and 2115 patients without. "Preservation of an adjacent tooth" was the reason that 32% of these patients chose implant therapy, and the patients without treatment history were significantly higher than the patients with one. Significantly, more patients without a treatment history of dental implants selected the after-effects of surgery and pain after surgery as their main concerns for implant therapy compared to those with a treatment history. In the question "Pain after surgery," the patients without treatment history did not know significantly lower than the patients with one. CONCLUSIONS: Patients without a treatment history of dental implants placed more importance on the preservation of healthy teeth. Because patients, in particular those without a treatment history of dental implants, are anxious about surgery, we should provide them with more information on treatment than we already do and explain the risks of treatment to them. To keep the credence between doctors and patients, informed consent and patient education on treatment are six important concerns.

Involvement of CX3CL1 in the Migration of Osteoclast Precursors Across Osteoblast Layer Stimulated by Interleukin-1ß.

The trigger for bone remodeling is bone resorption by osteoclasts. Osteoclast differentiation only occurs on the old bone, which needs to be repaired under physiological conditions. However, uncontrolled bone resorption is often observed in pro-inflammatory bone diseases, such as rheumatoid arthritis. Mature osteoclasts are multinuclear cells that differentiate from monocyte/macrophage lineage cells by cell fusion. Although Osteoclast precursors should migrate across osteoblast layer to reach bone matrix before maturation, the underlying mechanisms have not yet been elucidated in detail. We herein found that osteoclast precursors utilize two routes to migrate across osteoblast layer by confocal- and electro-microscopic observations. The osteoclast supporting activity of osteoblasts inversely correlated with osteoblast density and was positively related to the number of osteoclast precursors under the osteoblast layer. Osteoclast differentiation was induced by IL-1ß, but not by PGE2 in high-density osteoblasts. Osteoblasts and osteoclast precursors expressed CX3CL1 and CX3CR1, respectively, and the expression of CX3CL1 increased in response to interleukin-1ß. An anti-CX3CL1-neutralizing antibody inhibited the migration of osteoclast precursors and osteoclast differentiation. These results strongly suggest the involvement of CX3CL1 in the migration of osteoclast precursors and osteoclastogenesis, and will contribute to the development of new therapies for bone diseases. J. Cell. Physiol. 232: 1739-1745, 2017. © 2016 Wiley Periodicals, Inc.

Long-term radiographic assessment of maxillary sinus floor augmentation using beta-tricalcium phosphate: analysis by cone-beam computed tomography.

BACKGROUND: The long-term stability of maxillary sinus floor augmentation with ß-TCP remains largely unknown. We report the long-term assessment of volumetric changes in maxillary sinus floor augmentation with ß-TCP by cone-beam computed tomography (CBCT). METHODS: The subjects included 30 patients who underwent maxillary sinus floor augmentation using ß-TCP and 58 implant placement for unilateral maxillary defect, simultaneously. Volumetric changes in ß-TCP and the height of peri-implant bone were analyzed by CBCT. RESULTS: In all patients, the mean volume of the grafted bone decreased from immediately after implant placement to 6 months after implant placement (75.6 % reduction rate); it decreased further at 2.5 years after implant placement (54.9 % reduction rate). The mean of the height from the implant tip to the maxillary sinus floor was 2.00 ± 1.51 mm, 0.73 ± 1.33 mm, and -0.72 ± 1.11 mm immediately, 6 months, and 2.5 years after implant placement, respectively. The implant tip protruded beyond the maxillary sinus floor in approximately 70 % of the implants (41/58 implants) at 2.5 years after surgery. During the observation period, the implant survival rate was 100 %. CONCLUSIONS: The radiographic analysis by CBCT is considerably more advanced than previous radiographic examinations. Although maxillary sinus pneumatization continues to progress ≥1 year after maxillary sinus floor augmentation with ß-TCP, it stabilizes 3 years after surgery.

Histological and micro-computed tomographic observations after maxillary sinus augmentation with porous hydroxyapatite alloplasts: a clinical case series.

BACKGROUND: It is important to visualize the phenomenon which occurs in actual clinical cases to decide the timing of implant placement subsequently after sinus graft. Although several clinical cases of bone augmentation using xenograft have been evaluated, the number of those reports which have described bone remodeling by alloplasty are not sufficient. FINDINGS: In the present report, to investigate bone remodeling histologically after maxillary sinus augmentation with porous hydroxyapatite alloplast, bone cores from the sinus floor of three female nonsmoking patients (aged 64-73 years) were collected 6 months after sinus lift surgery, embedded in methyl methacrylate resin, and prepared by conventional methods. Bone architecture and graft residues were evaluated by micro-computed tomography of the same specimens. Hematoxylin-eosin and Villanueva-Goldner staining revealed mature osteoblasts and multinucleated osteoclasts on the grafted sinus floor and surface of residual hydroxyapatite particles. The particulate interspace was partially filled with osteoid and calcified tissue and showed active vascularization. CONCLUSION: The results suggested that bone regeneration and angiogenesis within and between porous hydroxyapatite particles were sufficiently found after 6 month histologically in the grafted sinus floor.

The Maxillary Sinus Floor Elevation Using a Poly-L-Lactic Acid Device to Create Space Without Bone Graft: Case Series Study of Five Patients.

Maxillary sinus floor elevation using autologous or alloplastic bone grafting is often performed for implant treatment of maxillary molars; however, issues related to the donor site and complications such as infection have been reported. We performed maxillary sinus floor elevation using poly-L-lactic acid (PLLA) as a space-making material in patients with an insufficient bone mass (<3 mm) for simultaneous implantation between the alveolar crest and floor of the maxillary sinus and evaluated the newly formed bone. Conventional antrostomy of the maxillary sinus from the lateral wall was performed, and PLLA was placed on the floor of the maxillary sinus after elevating the sinus membrane. Six months after surgery, the bone mass and density were measured using quantitative computed tomography, and histological evaluation was performed. No complications were recorded. Radiological findings showed a bone-like radiopaque appearance, and histological examination revealed new bone formation in all patients. In cases with insufficient bone mass prior to simultaneous implant placement, this method of maxillary sinus augmentation allows for sufficient bone augmentation without bone grafting.