A laminin-211-derived bioactive peptide promotes the osseointegration of a sandblasted, large-grit, acid-etched titanium implant.

Early implant loading is very important for reducing the duration of missing teeth in human patients. The laminin-derived peptide, DLTIDDSYWYRI motif (Ln2-P3), accelerates bone healing. Therefore, to investigate the hypothesis that Ln2-P3 increases the bone response to sandblasted, large-grit, acid-etched (SLA) titanium implants, the effect of the Ln2-P3 peptide on the osseointegration of SLA titanium implants was evaluated in vitro and in vivo. Human osteoblast-like cells were cultured on untreated, scrambled peptide (SP)-treated, and Ln2-P3-treated SLA titanium discs, and the cellular responses of these cells were evaluated. The Ln2-P3 treatment augmented osteoblast attachment and spreading, alkaline phosphatase activity, and the expression of osteogenic marker genes. Furthermore, the untreated and Ln2-P3-treated SLA titanium implants were inserted into the tibiae of rabbits for 9 and 11 days. Compared with the untreated implants, the Ln2-P3-treated implants showed a significantly higher bone-to-implant contact ratio at Day 9 after implantation and an increased bone area. The Ln2-P3 treatment of the SLA titanium implant surface augmented osteoblastic activity and accelerated peri-implant bone formation at the bone-implant interface. Overall, these results indicated that compared with the SLA titanium surface alone, the Ln2-P3 peptide-treated SLA titanium surface enhances initial osseointegration, thereby facilitating earlier implant loading.

Leukocyte- and platelet-rich fibrin is an effective membrane for lateral ridge augmentation: An in vivo study using a canine model with surgically created defects.

BACKGROUND: Leukocyte- and platelet-rich fibrin (L-PRF) has been suggested to enhance bone healing and the effects of L-PRF need to be evaluated in lateral residual alveolar bone augmentation. This in vivo study aimed to analyze the effects of L-PRF as a membrane on bone regeneration in lateral residual alveolar augmentation. METHODS: Eight mongrel dogs were used; the mandibular premolars were extracted and then three lateral ridge defects were surgically created on each side of the arch. After 4 weeks, guided bone ridge augmentation was performed in each defect with the following treatment groups: N+D (nonresorbable membrane with deproteinized bovine bone mineral [DBBM]), N+B (nonresorbable membrane with ß-tricalcium phosphate [ß-TCP]), R+D (resorbable membrane with DBBM), R+B (resorbable membrane with ß-TCP), and P+D (L-PRF with DBBM), and P+B (L-PRF and ß-TCP). Following 4 weeks of bone healing, the new bone amount for each group was measured by light microscopy (primary outcome) and microcomputed tomography (micro-CT) (secondary outcome). The mean values were compared at the 0.05 significance level. RESULTS: The P+D group showed the most newly formed bone in histology and in micro-CT analyses. L-PRF was more effective in bone regeneration when compared to nonresorbable and resorbable barrier membranes. Additionally, this study indicated DBBM was the more favorable osseous graft material for bone regeneration than ß-TCP when barrier membranes are used. CONCLUSION: From the results of this in vivo study using surgically created defects, L-PRF plays an effective role as a barrier membrane for lateral ridge augmentation. L-PRF may be an excellent barrier membrane in place of other nonresorbable and resorbable membranes.

The Effect of Ultraviolet Photofunctionalization on a Titanium Dental Implant with Machined Surface: An In Vitro and In Vivo Study.

Ultraviolet (UV) photofunctionalization has been suggested as an effective method to enhance the osseointegration of titanium surface. In this study, machined surface treated with UV light (M + UV) was compared to sandblasted, large-grit, acid-etched (SLA) surface through in vitro and in vivo studies. Groups of titanium specimens were defined as machined (M), SLA, and M + UV for the disc type, and M + UV and SLA for the implant. The discs and implants were assessed using scanning electron microscopy, confocal laser scanning microscopy, electron spectroscopy for chemical analysis, and the contact angle. Additionally, we evaluated the cell attachment, proliferation assay, and real-time polymerase chain reaction for the MC3T3-E1 cells. In a rabbit tibia model, the implants were examined to evaluate the bone-to-implant contact ratio and the bone area. In the M + UV group, we observed the lower amount of carbon, a 0°-degree contact angle, and enhanced osteogenic cell activities (p < 0.05). The histomorphometric analysis showed that a higher bone-to-implant contact ratio was found in the M + UV implant at 10 days (p < 0.05). In conclusion, the UV photofunctionalization of a Ti dental implant with M surface attained earlier osseointegration than SLA.

Osteogenic Cell Behavior on Titanium Surfaces in Hard Tissue.

It is challenging to remove dental implants once they have been inserted into the bone because it is hard to visualize the actual process of bone formation after implant installation, not to mention the cellular events that occur therein. During bone formation, contact osteogenesis occurs on roughened implant surfaces, while distance osteogenesis occurs on smooth implant surfaces. In the literature, there have been many in vitro model studies of bone formation on simulated dental implants using flattened titanium (Ti) discs; however, the purpose of this study was to identify the in vivo cell responses to the implant surfaces on actual, three-dimensional (3D) dental Ti implants and the surrounding bone in contact with such implants at the electron microscopic level using two different types of implant surfaces. In particular, the different parts of the implant structures were scrutinized. In this study, dental implants were installed in rabbit tibiae. The implants and bone were removed on day 10 and, subsequently, assessed using scanning electron microscopy (SEM), immunofluorescence microscopy (IF), transmission electron microscopy (TEM), focused ion-beam (FIB) system with Cs-corrected TEM (Cs-STEM), and confocal laser scanning microscopy (CLSM)-which were used to determine the implant surface characteristics and to identify the cells according to the different structural parts of the turned and roughened implants. The cell attachment pattern was revealed according to the different structural components of each implant surface and bone. Different cell responses to the implant surfaces and the surrounding bone were attained at an electron microscopic level in an in vivo model. These results shed light on cell behavioral patterns that occur during bone regeneration and could be a guide in the use of electron microscopy for 3D dental implants in an in vivo model.

A Clue to the Existence of Bonding between Bone and Implant Surface: An In Vivo Study.

We evaluated the shear bond strength of bone-implant contact, or osseointegration, in the rabbit tibia model, and compared the strength between grades 2 and 4 of commercially pure titanium (cp-Ti). A total of 13 grades 2 and 4 cp-Ti implants were used, which had an identical cylinder shape and surface topography. Field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and confocal laser microscopy were used for surface analysis. Four grades 2 and 4 cp-Ti implants were inserted into the rabbit tibiae with complete randomization. After six weeks of healing, the experimental animals were sacrificed and the implants were removed en bloc with the surrounding bone. The bone-implant interfaces were three-dimensionally imaged with micro-computed tomography. Using these images, the bone-implant contact area was measured. Counterclockwise rotation force was applied to the implants for the measurement of removal torque values. Shear bond strength was calculated from the measured bone-implant contact and removal torque data. The t-tests were used to compare the outcome measures between the groups, and statistical significance was evaluated at the 0.05 level. Surface analysis showed that grades 2 and 4 cp-Ti implants have similar topographic features. We found no significant difference in the three-dimensional bone-implant contact area between these two implants. However, grade 2 cp-Ti implants had a higher shear bond strength than grade 4 cp-Ti implants (p = 0.032). The surfaces of the grade 2 cp-Ti implants were similar to those of the grade 4 implants in terms of physical characteristics and the quantitative amount of attachment to the bone, whereas the grade 2 surfaces were stronger than the grade 4 surfaces in the bone-surface interaction, indicating osseointegration quality.

Comparison of micro-computed tomography and histomorphometry in the measurement of bone-implant contact ratios.

OBJECTIVE: The purpose of this study was to measure the 3-dimensional (3D) bone-to-implant contact (BIC) ratios calculated with an associated software algorithm on 3D micro-computed tomography (µCT) scans and compare them with measurements made with 2-dimensional histomorphometry. STUDY DESIGN: For uncomplicated calculation of the 3D BIC ratios, 16 implants (8 grade 2 titanium and 8 grade 4 titanium) with simple cylindrical geometry were inserted into 8 rabbit tibiae; 2 implants were inserted into each tibia. The experimental animals were sacrificed at 2 weeks after surgery. The implants were surgically removed en bloc with surrounding bone. 3D µCT images were acquired and reconstructed, and histomorphometric procedures were performed. The calculated 3D BIC ratios were compared with the histomorphometrically measured BIC ratios. RESULTS: When the 3D BIC ratios calculated in this study were compared with the BIC ratios measured conventionally by using histologic slides for light microscopy, no significant statistical correlation was found between the 2 ratios (P ≥ .35). CONCLUSIONS: This study indicated that 3D µCT should be used for more accurate BIC assessment to produce an overall 3D picture for the bone-implant interface.

A laminin-derived functional peptide, PPFEGCIWN, promotes bone formation on sandblasted, large-grit, acid-etched titanium implant surfaces.

PURPOSE: This study aimed to investigate the in vitro and in vivo bone-forming potential of a sandblasted, large-grit, acid-etched (SLA) titanium (Ti) surface treated with a laminin-derived functional peptide, PPFEGCIWN (DN3). MATERIALS AND METHODS: Human osteoblast-like MG63 cells were cultured with SLA Ti discs untreated or treated with DN3 or a control scrambled peptide (SP). Cell adhesion, spreading, and viability on the discs were tested. Alkaline phosphatase gene expression and enzyme activity were also evaluated. Four DN3-coated SLA Ti implants and four untreated implants were placed into the tibiae of two rabbits (two implants/tibia). Ten days later, the bone-implant interfaces were subjected to histomorphometry to measure the bone response. The surface properties of the discs and implants were determined using scanning electron, widefield confocal, and confocal laser microscopy and x-ray photoelectron spectroscopy. RESULTS: The peptide-treated and untreated discs and implants were similar in terms of physical surface properties, but the peptide-treated surfaces had significantly higher nitrogen levels (P < .05). The DN3 peptide promoted cell adhesion, spreading, and alkaline phosphatase expression and enzyme activity (P < .05). Histomorphometry of the harvested implants showed rapid bone formation and affinity of the motif. CONCLUSION: This study suggests that treatment with the cell adhesion peptide DN3 promotes bone healing at the SLA Ti surface.

Control Variable Implants Improve Interpretation of Surface Modification and Implant Design Effects on Early Bone Responses: An In Vivo Study.

PURPOSE: This in vivo study used control variable implants to compare early bone responses in fluoride-modified (F-mod) and hydrophilic, sandblasted, large-grit, acid-etched (modSLA) surface implants that differed in implant design. MATERIALS AND METHODS: Four different types of implants (n = 24) were prepared: F-mod surface with Astra Tech implant design; modSLA surface with Straumann implant design; sandblasted, large-grit, acid-etched (SLA) surface with Astra Tech design; and SLA surface with Straumann implant design. Scanning electron microscopy, confocal laser scanning microscopy, and x-ray photoelectron spectroscopy were performed to assess implant surface characteristics. Four implants from each implant type were inserted in the tibiae of four rabbits that were sacrificed 10 days after surgery. Bone-to-implant contact (BIC) and bone area (BA) were measured to evaluate early bone responses. Analysis of variance with Tukey's multiple comparison method was used for the histomorphometric data to find any significant difference. The surface characteristic-related data were analyzed using the Kruskal-Wallis test. The level of significance was .05 in statistical analyses. RESULTS: No significant differences in BIC and BA were found among the modified surfaces (P > .05), whereas significant differences were found in surface topography and surface chemistry. The different designs showed no significant effects on early bone responses when identical surface modifications were applied (P > .05). CONCLUSION: F-mod and modSLA surfaces showed no significant differences in early bone responses. Furthermore, the implant design had no influence on the bone response. This in vivo experimental model will help improve the evaluation of surface modification factors by allowing an independent estimation of one variable (surface modification) against a constant (implant design).

Spiral scanning imaging and quantitative calculation of the 3-dimensional screw-shaped bone-implant interface on micro-computed tomography.

PURPOSE: Bone-to-implant contact (BIC) is difficult to measure on micro-computed tomography (CT) because of artifacts that hinder accurate differentiation of the bone and implant. This study presents an advanced algorithm for measuring BIC in micro-CT acquisitions using a spiral scanning technique, with improved differentiation of bone and implant materials. METHODS: Five sandblasted, large-grit, acid-etched implants were used. Three implants were subjected to surface analysis, and 2 were inserted into a New Zealand white rabbit, with each tibia receiving 1 implant. The rabbit was sacrificed after 28 days. The en bloc specimens were subjected to spiral (SkyScan 1275, Bruker) and round (SkyScan 1172, SkyScan 1275) micro-CT scanning to evaluate differences in the images resulting from the different scanning techniques. The partial volume effect (PVE) was optimized as much as possible. BIC was measured with both round and spiral scanning on the SkyScan 1275, and the results were compared. RESULTS: Compared with the round micro-CT scanning, the spiral scanning showed much clearer images. In addition, the PVE was optimized, which allowed accurate BIC measurements to be made. Round scanning on the SkyScan 1275 resulted in higher BIC measurements than spiral scanning on the same machine; however, the higher measurements on round scanning were confirmed to be false, and were found to be the result of artifacts in the void, rather than bone. CONCLUSIONS: The results of this study indicate that spiral scanning can reduce metal artifacts, thereby allowing clear differentiation of bone and implant. Moreover, the PVE, which is a factor that inevitably hinders accurate BIC measurements, was optimized through an advanced algorithm.

Characteristics of contact and distance osteogenesis around modified implant surfaces in rabbit tibiae.

PURPOSE: Contact and distance osteogenesis occur around all endosseous dental implants. However, the mechanisms underlying these processes have not been fully elucidated. We hypothesized that these processes occur independently of each other. To test this, we used titanium (Ti) tubes to physically separate contact and distance osteogenesis, thus allowing contact osteogenesis to be measured in the absence of possible triggers from distance osteogenesis. METHODS: Sandblasted and acid-etched (SLA) and modified SLA (modSLA) implants were used. Both types had been sandblasted with large grit and then etched with acid. The modSLA implants then underwent additional treatment to increase hydrophilicity. The implants were implanted into rabbit tibiae, and half were implanted within Ti tubes. The bone-to-implant contact (BIC) ratio was calculated for each implant. Immunohistochemical analyses of bone morphogenetic protein (BMP)-2 expression and new bone formation (Masson trichrome stain) were performed. RESULTS: The implants outside of Ti tubes were associated with good bone formation along the implant surface. Implantation within a Ti tube significantly reduced the BIC ratio (P<0.001). Compared with the modSLA implants, the SLA implants were associated with significantly higher BIC ratios, regardless of the presence or absence of Ti tubes (P=0.043). In the absence of Ti tubes, the bone adjacent to the implant had areas of new bone formation that expressed BMP-2 at high levels. CONCLUSIONS: This study disproved the null hypothesis and suggested that contact osteogenesis is initiated by signals from the old bone that undergoes distance osteogenesis after drilling. This signal may be BMP-2.

Influence of nanocoated calcium phosphate on two different types of implant surfaces in different bone environment: an animal study.

OBJECTIVE: The purpose of this study was to evaluate the osseointegration of two different types of surfaces, smooth and roughened surface implants nanocoated with calcium phosphate (CAP) around different bone environment. MATERIALS AND METHODS: Five male mongrel dogs were used in this study. The premolars and molars were extracted on both sides of the mandible. Eight weeks after extraction, implants were submerged on both sides of the mandible. On the left, CAP nanocoated roughened surface (RCAP) implants were installed whereas, the CAP nanocoated smooth surface (SCAP) implants were installed on the right side. The control group had no defect, on the other hand, three-wall intrabony defects were surgically created adjacent to the implant in the experimental group. The dogs were sacrificed after 12 weeks. RESULTS: Histological and histomorphometrical analysis were performed with the specimen. The SCAP and RCAP implants showed good osseointegration with no statistical significance in the control group. Histologically, the SCAP group showed little resolution of the defect compared with the RCAP group. In the experimental groups, there was a significant difference in defect fill between SCAP and RCAP. CONCLUSION: Within the limits of our study, it can be concluded that SCAP and RCAP implants show no difference in sufficient bone area whereas, CAP nanocoating on roughened implant surface may enhance osseointegration in deficient bone environment.

Comparison between bioactive fluoride modified and bioinert anodically oxidized implant surfaces in early bone response using rabbit tibia model.

PURPOSE: The aim of this study was to investigate whether bioactive surfaces were more favorable to bone than bioinert surfaces by evaluating bone responses around two commercial dental implants. MATERIALS AND METHODS: Bioactive fluoride-modified implants (Osseospeed) were compared with bioinert oxidized implants (TiUnite). Field emission scanning electron microscopy, energy dispersive spectroscopy, and confocal laser scanning microscopy analyzed the implant surface characteristics. Five New Zealand white rabbits were used to evaluate the bone response. Each rabbit received two implants: a fluoride-modified implant in one tibia and an oxidized implant in the other. Drilling was performed bicortically, and a gap defect was created in the upper cortexonly. Bone-to-implant contact and bone area were measured on the histological specimens 2 weeks after implant insertion. RESULTS: No significant differences were found in surface roughness (P > 0.05). The gap defects were almost filled with new bone within a period of 2 weeks. The histomorphometry revealed no significant differences in bone-to-implant contact and bone area (P > 0.05). CONCLUSIONS: Within the limitation of this study, the bioactive fluoride-modified surface may show no superiority to the bioinert anodized surface in early bone response.

Resolution of surgically created three-wall intrabony defects in implants using three different biomaterials: an in vivo study.

OBJECTIVES: To histomorphometrically analyze bone formation on amorphous calcium phosphate (ACP), micro-macroporous biphasic calcium phosphate (MBCP), and freeze-dried bone allograft (FDBA) in three-wall defects adjacent to structured surface with calcium phosphate nanocoating implants in dogs. MATERIALS AND METHODS: Five male mixed-breed dogs were used in this study. The premolars and molars were extracted on both sides of the mandible. Eight weeks after extraction, four implants were submerged on each side of the mandible. Three-wall intrabony defects (5 × 3 × 3 mm) were surgically created adjacent to the implants before installation. No grafts were placed in the control group. At the experimental sites, each intrabony defect was grafted with either ACP, MBCP, or FDBA. The dogs were sacrificed after 12 weeks, and histological and histomorphometrical analyses of the implant sites were performed. RESULTS: All of the three experimental groups exhibited defect resolution and osseointegration that showed a statistically significant difference compared with the control group in terms of remaining defect depth and bone-to-implant contact (BIC). However, there were no statistical significances among the three experimental groups. MBCP had the highest BIC (63.57 ± 21.57%), followed by ACP and FDBA. The control group showed the least bone area and the greatest remaining defect depth. CONCLUSION: Grafts with the synthetic biomaterials ACP and MBCP showed bone regeneration that was similar to FDBA in surgically created three-wall intrabony defects adjacent to implants. Within the limitations of this study, it can be concluded that ACP and MBCP synthetic biomaterials are as effective as FDBA at osteoconduction.

The effects of newly formed synthetic peptide on bone regeneration in rat calvarial defects.

PURPOSE: Significant interest has emerged in the design of cell scaffolds that incorporate peptide sequences that correspond to known signaling domains in extracellular matrix and bone morphogenetic protein. The purpose of this study was to evaluate the bone regenerative effects of the synthetic peptide in a critical-size rat calvarial defect model. METHODS: Eight millimeter diameter standardized, circular, transosseus defects created on the cranium of forty rats were implanted with synthetic peptide, collagen, or both synthetic peptide and collagen. No material was was implanted the control group. The healing of each group was evaluated histologically and histomorphometrically after 2- and 8-week healing intervals. RESULTS: Surgical implantation of the synthetic peptide and collagen resulted in enhanced local bone formation at both 2 and 8 weeks compared to the control group. When the experimental groups were compared to each other, they showed a similar pattern of bone formation. The defect closure and new bone area were significantly different in synthetic peptide and collagen group at 8 weeks. CONCLUSIONS: Concerning the advantages of biomaterials, synthetic peptide can be an effective biomaterial for damaged periodontal regeneration.

Evaluation of mandibular posterior single implants with two different surfaces: a 5-year comparative study.

BACKGROUND: Anatomic and biomechanical limitations can jeopardize successful single implantation in the mandibular posterior area. To overcome the limitations, the design and the surface of the fixtures were modified. This study evaluated the cumulative survival rate (CSR) of mandibular molars replaced with a sand-blasted, large-grit, acid-etched (SLA) single implant or an anodized (ANO) single implant and examined associated factors, such as the surface treatment, position, and length and diameter of the implants. METHODS: One hundred ninety-three single implants restored with an SLA implant and 112 single implants restored with an ANO implant in the mandibular molar area were selected from subjects who had visited the Department of Periodontology, Dental Hospital of Yonsei University, from March 2001 through June 2006. In the SLA group, 123 and 70 implants were placed in the first and second molar area, respectively. In the ANO group, 55 and 57 implants were placed in the first and second molar area, respectively. The 1- to 6-year CSR of the SLA and ANO groups was calculated using the life-table analysis. In addition, associated factors, such as the surface treatment, position, and length and diameter of the implants, were compared and analyzed using the chi(2) test (P <0.05). RESULTS: Two of 193 implants in the SLA group failed, giving a CSR of 98.96%; four of 112 ANO implants failed, giving a CSR of 96.43%. There were no significant differences with regard to the surface treatment, position, and length and diameter of the implants. CONCLUSIONS: Despite the anatomic and biomechanical limitation in the mandibular posterior area, mandibular posterior single implants showed a high CSR during the observation period. Mandibular posterior single implants can be an effective and reliable treatment modality that is not affected by the surface treatment, position, or length and diameter of the implant.

Effects of different depths of gap on healing of surgically created coronal defects around implants in dogs: a pilot study.

BACKGROUND: This study investigated the bone growth pattern in surgically created coronal defects with various depths around implants in dogs. METHODS: Four mongrel dogs were used. All mandibular premolars were extracted under general anesthesia and left to heal for 2 months. After ostectomy, bony defects were prepared in test sites, using a stepped drill with a diameter of 6.3 mm and two depths: 2.5 mm (test sites 1 [T1]) and 5.0 mm (test sites 2 [T2]). In the control sites, the implants were placed after ostectomy without any coronal defects. T1, T2, and control sites were prepared in the right and left sides of the mandible. Six implants, 3.3 mm in diameter and 10 mm in length, were placed in each dog; the implants were submerged completely. Two dogs were sacrificed 8 weeks after surgery, and the other two dogs were sacrificed 12 weeks after surgery. The stability of all implants was measured with a resonance frequency analyzer after placement and after sacrifice. All sites were block-dissected for ground sectioning and histologic examination. RESULTS: After 12 weeks of healing, only T2 were not filled fully with bone. At week 8, the mean bone-to-implant contact (BIC) was 47.7% for control, 43.6% for T1, and 22.2% for T2. At week 12, the control BIC was 56.7% and the 2.5-mm defect had a greater BIC (58.8%). However, in the 5-mm defect, the BIC was 35.1%. At insertion, stability was reduced at sites with a greater defect depth. Similar stability was noted in all specimens after 8 and 12 weeks of healing. CONCLUSION: Bone healing between an implant and marginal bone was compromised at sites with a deeper defect when the width of the bone defect was 1.5 mm.