The International Journal of Oral & Maxillofacial Implants, 06/2017

Purpose: The goal of this study was to compare the in vitro bioactivity in simulated body fluid (SBF) of commercially available dental implants. Materials and Methods: Bioactivity, according to ISO 23317, of commercially available dental implants with various surface modifications (BIO-surface, SLA, SLActive, TiUnite, and OsseoSpeed) was tested in SBF for 1 and 3 weeks. Surface characterizations, especially calcium and phosphorus surface content before and after the immersion in SBF, were performed. The effect of surface treatment on bioactivity was studied. Results: Differences between surfaces before immersion in SBF were confirmed by Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), and scanning electron microscope (SEM) analysis. Calcium and phosphorus surface content was increasing within the tested period in the case of two (BIO-surface and SLActive) of the five tested dental implants. Calcium-phosphate precipitation was observed by SEM, XPS, EDX, and x-ray micro‑diffraction (μ-XRD) analysis. Conclusion: Two (BIO-surface from LASAK and SLActive from Straumann) of the five tested dental implants were found to be bioactive, according to ISO 23317. Although it is difficult to unambiguously determine the properties that have influence on the hydroxyapatite precipitation rate, multiple properties that the two surfaces have in common were found. Keywords: dental implant, in vitro bioactivity, ISO 23317, SBF, surface treatment

Purpose: To compare the adhesion and proliferation effect of HGF-1 cells on pure titanium disks when the surfaces are unprocessed (machined surfaces after slicing) or modified with a laser. Materials and Methods: Twenty-eight titanium disks were divided into four groups. Three surface topographies were created using an erbium fiber laser: group 1 (unidirectional application [no crosshatch]), group 2 (crosshatching in two directions), and group 3 (crosshatching in three directions). The samples in group 4 were unprocessed and served as controls. The surface roughness of samples was investigated with scanning electron microscopy (SEM) and measured with a mechanical surface profilometer. HGF-1 cell line was used to analyze the adhesion of fibroblasts on the sample surfaces. The authors used SEM, XTT, and acridine orange tests to determine the adhesion of HGF-1 onto specimen surfaces and the cell morphology after incubation for 72 hours. XTT results and surface roughness values for all specimens were analyzed using the Kruskal-Wallis test. Results: Ra values of group 1 to group 4 (control) were 1.13, 0.26, 0.38, and 0.19, respectively. Crosshatching decreased the surface roughness values compared with unidirectional application (P = .003). Cell morphology observed in SEM showed that the elongation direction of cells resulted in all directions related with additional filopodia extentions within the crosshatch groups. Therefore, the highest cell viability was also detected in the three-directional crosshatch group (group 3) (P = .000) in XTT assay. According to the acridine orange test, higher cell numbers were seen in group 3, similar to the XTT findings (P = .86). Conclusion: Crosshatching significantly increased the cell-covered implant surfaces compared with the unidirectional group. Decreasing the surface Ra values via crosshatching helped spread the fibroblast over the implants in any direction, thus increasing cell proliferation and adhesion. Keywords: electron microscope tomography, lasers, titanium

Purpose: To evaluate the changes in the external-hexagon surface of the titanium (Ti) implant before and after mechanical cycling, when coupled with zirconia (Zr) abutments (A) manufactured by three computer-aided design/ computer-aided manufacturing (CAD/CAM) systems (Neodent Digital, Zirkonzahn, and AmannGirrbach) and the ZrTi abutment manufactured by Neodent. Materials and Methods: Four groups were formed (n = 6): titanium implant with Zr AmannGirrbach abutment (AZrAG), with Zr Zirkonzahn abutment (AZrZ), with Zr Neodent abutment (AZrN), and with Zr abutment with infrastructure in Ti Neodent (AZrTiN). Standardized abutments were made from three identical abutments milled in wax. Images of the surface of each side of the hexagons of the implant were obtained by scanning electron microscopy, before and after mechanical cycling, to evaluate the parameters: (1) scratches in the hexagon face; (2) hexagon superior shoulder kneading; (3) hexagon shoulder wear; (4) alterations on the hexagon base; and (5) scratches on the hexagon top. The abutments were coupled with the implants, and Cr-Co crowns were cemented. The implant/abutment/crown assemblies were submitted to mechanical cycling (400 N, 8.0 Hz) for 1 million cycles. The observed changes were classified as follows: absence (0), mild (1), moderate (2), and severe (3). The results were analyzed using the Mann-Whitney, Kruskal-Wallis, and Dunn tests (P .05). Results: For parameter 1, a significant difference (P = .008) was observed between AZrZ and AZrAG, with more scratches in AZrZ; and between AZrN and AZrTiN (P = .006), with more scratches in AZrN. For parameter 2, a significant difference (P .05) was observed between AZrZ and AZrAG and between AZrZ and AZrN, with greater kneading in AZrZ; among AZrN and AZrTiN, there was no significant difference (P = .103). For parameter 3, a significant difference (P .05) was observed between AZrZ and the other groups of Zr, with more wear in AZrZ; between AZrN and AZrTiN, there was no significant difference (P = .107). For parameter 4, a significant difference (P .05) was observed between AZrZ and AZrN, with more scratches in AZrZ; a significant difference (P = .002) was also observed between AZrN and AZrTiN, with more scratches in AZrN. For parameter 5, a significant difference (P .05) was observed between AZrZ and AZrAG and between AZrZ and AZrN, with the fewest scratches in AZrZ; a significant difference (P = .006) was also observed between AZrN and AZrTiN, with more alterations in AZrN. Considering all the alterations, the AZrZ group showed more surface alteration, 1.74 (0.99); followed by AZrN, 1.43 (0.92); AZrAG, 1.32 (0.96); and AZrTiN, 0.88 (0.94). Conclusion: Among the Neodent abutments, the AZrN group had shown more surface alterations. Among the Zr groups, AZrZ samples had shown the most altered surfaces, suggesting that alterations on the implant/Zr abutment hexagon surfaces are related to the abutment milled hexagon shape. Keywords: CAD/CAM, cyclic loading, esthetic abutment, implant abutment, implant-abutment interface, prosthodontics, titanium, zirconia

Purpose: To analyze, in vitro, the influence of O2 pressure on the adhesion, proliferation, and osteogenic differentiation of human dental pulp stem cells (DPSC) on β-tricalcium phosphate (β-TCP) scaffold. Materials and Methods: DPSC, positive for the molecular markers CD133, Oct4, Nestin, Stro-1, and CD34, and negative for CD45, were isolated from extracted third molars. Experiments were started by seeding 200,000 cells on β-TCP cultured under 3% or 21% O2 pressure. No osteogenic medium was used. Eight different cultures were performed at each time point under each O2 pressure condition. Cell adhesion, proliferation, and differentiation over the biomaterial were evaluated at 7, 13, 18, and 23 days of culture. Cell adhesion was determined by light microscopy, proliferation by DNA quantification, and osteogenic differentiation by alkaline phosphatase (ALP) activity analysis. Results: DPSC adhered to β-TCP with both O2 conditions. Cell proliferation was found from day 7 of culture. Higher values were recorded at 3% O2 in each time point. Statistically significant differences were recorded at 23 days of culture (P = .033). ALP activity was not detectable at 7 days. There was, however, an increase in ALP activity over time in both groups. At 13, 18, and 23 days of culture, higher ALP activity was recorded under 3% O2 pressure. Statistical differences were found at day 23 (P = .014). Conclusion: DPSC display capacity of adhering to β-TCP under 3% or 21% O2 pressure conditions. Cell proliferation on β-TCP phosphate is significantly higher at 3% than at 21% O2 pressure, the most frequently used O2 tension. β-TCP can itself promote osteogenic differentiation of DPSC and is enhanced under 3% O2 compared with 21%. Keywords: bone regeneration, dental pulp stem cells, O2 pressure, tissue engineering, β-tricalcium phosphate

Purpose: To evaluate the relationship between mandibular bone structure parameters measured on preimplant cone beam computed tomography (CBCT) images and primary implant stability. Materials and Methods: Twenty-one hemimandibles were scanned on the 3D Accuitomo 170 CBCT. Next, an implant was placed in each hemimandible, after which insertion torque and implant stability quotient (ISQ) measurements were acquired. The following measurements were performed on the preimplant CBCT scans: bone surface, bone volume, fractal dimension, connectivity, trabecular thickness and spacing, and skeleton analysis. Measurements were performed using various regions of interest in the vicinity of the implant site. In addition, cortical thickness was measured. The correlation between bone structure parameters, insertion torque, and ISQ was calculated. Results: The overall correlation was low to medium (|R| = 0.002-0.723). For the bone around the entire implant site, the highest correlation with ISQ was found for skeleton analysis and trabecular thickness. The highest overall correlation between bone structure and ISQ was found in the coronal region. For insertion torque, no significant correlation was found for the bone around the entire implant; the highest overall correlation was found in the apical region. The highest number of significant correlations between bone structure and primary implant stability were found for trabecular thickness and fractal dimension. Conclusion: While each of the investigated bone structure parameters can have a predictive value in terms of primary implant stability, they should be measured at specific regions surrounding a planned implant site, and can provide complementary information regarding the local bone quality. Keywords: bone quality, computer-assisted image processing, cone beam computed tomography, dental implant, implant stability quotient, insertion torque

Purpose: Titanium-based biomaterials present good biocompatibility, while their osseointegration and antibacterial properties need to be improved. This study aimed to enhance the bone-bonding ability of titaniumbased granules, which are intended to be used as bone graft. Materials and Methods: The titanium granules were anodized in ethylene glycol-based electrolyte and subsequently annealed to be loaded separately with simvastatin. The samples were then inspected with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) for drug loading. The release of simvastatin from titanium granule samples was measured after soaking samples in phosphate-buffered saline (PBS) for 30 days using ultraviolet-visible (UV/Vis) spectroscopy. The alkaline phosphatase (ALP) activity of MG63 osteosarcoma-loaded samples was measured, and microbroth dilution assay was performed to evaluate the antibacterial potential of drug-loaded and nonloaded titanium granule samples for bacterial growth. Results: The results expressed the gradual and constant release of simvastatin within the duration of the examination. ALP of the samples showed improved activity of anodized and annealed granules, while the antibacterial test illustrated no significant improvement in their bactericidal effects. However, the simvastatin-loaded samples showed an improved antibacterial effect compared with nonloaded samples. Conclusion: It is assumed that anodizing, annealing, and subsequent simvastatin loading of titanium granules could be used as surface modification to improve osseointegration and restrain bacterial growth and adhesion. It is fair to believe that the results of this study could be used to treat titanium granules as bone graft substitute materials for dental and orthopedic applications. Keywords: bactericidal effect, bone graft, osseointegration, porous titanium granules, simvastatin

Purpose: Soft and hard tissue volumes are critical for implant placement and long-term stability. Although the literature has adequately addressed tissue biotypes of Western populations, pertinent information about Asian populations is limited. This study aimed to evaluate the soft and hard tissue profiles of the maxillary anterior teeth of the Taiwanese population using a semi-automatic algorithm. Materials and Methods: Cone beam computed tomography images of 11 adults with well-aligned maxillary anterior teeth were overlaid with those of cast models, based on the tooth crowns manually outlined by two independent observers. Each tooth was digitally trisected mesiodistally and apicocoronally. The thicknesses of the labial gingiva and alveolar bone were measured using a customized software program. Results: No obvious difference between the observers was noted regarding the dimension of tooth crowns. The average thicknesses of the labial gingiva, the labial alveolar bone, and the palatal alveolar bone were 1.76 ± 0.11 mm, 1.02 ± 0.12 mm, and 1.80 ± 0.31 mm, respectively, with no significant differences between teeth. All parameters were thicker in the apical region than in the cervical region, and the alveolar bone was thinner in the midlabial region of incisors than in the interproximal regions. The thinnest areas were the midcervical compartment of the right central incisor (0.53 ± 0.33 mm) for the labial gingiva, the midcervical compartment of the right lateral incisor (0.23 ± 0.10 mm) for the labial alveolar bone, and the mesiocervical compartment of the left central incisor (0.33 ± 0.09 mm) for the palatal alveolar bone. Conclusion: This study presents an objective and comprehensive methodology for evaluating the soft and hard tissue profiles of maxillary anterior teeth and may be of value for presurgical planning for immediate implant placement. The results suggest that profiles of the Taiwanese subjects are similar to profiles of Western populations. Keywords: alveolar process, cone beam computed tomography, dental implants, gingiva

Purpose: In this in vitro study, the purpose was to assess the cytotoxicity profiles of seven commercial dental implant materials by using cell culture methods on an osteoblastic cell line. Materials and Methods: The microstructure of seven commercial dental implants (each given a letter code) was investigated via scanning electron microscopy and energy-dispersive x-ray analysis. Medium extracts were collected on the first and fifth days for each group and tested using MC3T3-E1 cell line. Cytotoxicity was evaluated with Xcelligance System and XTT reagent, and apoptosis was determined by Annexin-V staining. One-way analysis of variance (ANOVA) and Tukey's multiple range tests were used for statistical analyses. In all tests, P was set as .05. Results: ANOVA results disclosed that Ti (P = .001), Na (P = .001), Ca (P = .019), Al (P = .024), and P (P = .020) amounts were significantly different between test materials. Cytotoxicity and apoptosis analyses revealed that implant materials (C) and (E) were the materials with the lowest cell vitality and the highest apoptosis rates among the test materials. Phosphorus was the only element that presented the highest amount in C and E (14.23% and 12.29%, respectively) compared with the other implant materials tested. (F) and (G) had favorable results for all experiments. Conclusion: The results suggest that pure dental implant materials with a lower number of additional elements may possess fewer cytotoxic effects than the other implant materials tested in this study. Keywords: cell culture, cytotoxicity, dental implants, energy-dispersive x-ray analysis, osteoblasts

Purpose: To evaluate insertion torque value (ITV) and marginal bone loss (MBL) of an implant system after a clinically perceived bone quality-adapted drilling. Materials and Methods: This multicenter retrospective study included patients treated with implants, conventionally loaded, in completely healed sites. Operators customized the osteotomy preparation according to radiographic assessment and their perception of bone quality. Drilling sequence, bone quality, and ITV were recorded at the time of surgery. Radiographs were taken at the time of implant placement and permanent restoration. MBL between implant placement and permanent restoration was calculated. The implant was used as the statistical unit. Demographic and implant characteristics were shown by means of descriptive statistics. Outcome values were compared using analysis of variance (ANOVA) and Kruskal-Wallis tests. Multiple regression models were used to test the effect of independent variables on ITV and MBL. Results: One hundred eighty-eight implants placed in 87 patients were included in the analysis. The mean observation period was 144 ± 59 days. The mean ITV was 30.8 ± 15.1 Ncm. ITV differed significantly based on arches (mandible/maxilla) (P = .001), bone quality (P .001), implant diameter (P = .032), and drilling protocol (P = .019). Median MBL was 0.05 mm (0.00; 0.24). A significant difference was found between the mandible and maxilla (P = .008) and between drilling protocols (P = .011). In particular, significantly higher MBL was found in the undersized drilling protocol. Multiple regression analysis showed that ITV was influenced by bone quality and implant diameter. MBL was influenced by bone quality, implant diameter, ITV, and the interaction between bone quality and ITV. It was estimated that MBL was greater with increased bone density and ITV. Conclusion: Excessive ITV in dense bone can cause negative marginal bone responses. A presurgical radiographic assessment and the perception of bone quality are necessary to select an optimal drilling protocol and to minimize surgical trauma. Keywords: dental implant, insertion torque, marginal bone loss, primary stability, surgical protocol

Clinicians very often have seen marginal bone loss around dental implants at the crest level early on after implant placement and uncovering. Early clinical publications had suggested that this bone loss occurred during the first year of loading. Thus, numerous attempts have been made to minimize or eliminate such bone loss. However, the timing and reason for this bone loss are not always apparent. The objective of this study was to review the evidence regarding marginal bone loss around dental implants from the standpoint of biologic consequences to help understand marginal bone changes around dental implants. One hypothesis for the bone loss around these implants was related to the presence of bacteria in the interfaces between the implant and abutment connections. The literature was reviewed regarding the three major types of implant-abutment crestal connections, including butt-joint, platform-switched, and no interface (tissue-level or one-body). This review article revealed that 1.5 to 2.0 mm of bone loss occurred around bone-level, butt-joint connections when the interface was created because the microgap was wide enough for penetration and colonization of bacteria, and that this bone loss was not observed around implants with no interface because they did not have a contaminated interface at the bone crest. Many studies have shown an advantage in the amount of marginal bone resorption for implants with a platform-switched connection, and there appears to be a significantly different biologic reaction. Recent publications indicate that such contaminated implant-abutment connections might have an effect on peri-implantitis and failure over time. Keywords: alveolar bone loss, dental implant-abutment interface, dental implants, inflammation, platform switching, review literature

Purpose: Implant overdentures with attachments have been used in clinical practice and the effect of attachments on implant strain has been frequently reported. However, most studies have focused on mandibular overdentures; there are few reports on maxillary overdentures. The purpose of this study was to examine the influence of attachment type on implant strain in maxillary overdentures under various implant configurations. Materials and Methods: A maxillary edentulous model with implants and experimental overdentures were fabricated. Four strain gauges were attached to each implant, positioned in anterior, premolar, and molar areas. Three types of unsplinted attachments-ball, locator, and magnet-were set on the implants under various implant configurations. A vertical occlusal load of 98 N was applied through the mandibular complete denture, and implant strain was compared using the Kruskal-Wallis test. Results: Ball attachments caused the greatest amount of strain, while magnet attachments caused the least amount under all conditions. For all attachments, two anterior implants caused significantly more strain than four implants (P .05). No significant difference was observed between subtypes in four-implant configurations except when using locator attachments. Conclusion: When using unsplinted attachments for maxillary implant overdentures, magnet attachments are recommended to reduce implant stress. Using only two implants, especially two anterior implants, is not recommended regardless of attachment type. Keywords: ball attachment, locator attachment, magnet attachment, maxillary implant overdenture, strain

Purpose: This in vitro study tested the effects of argon atmospheric pressure dielectric barrier discharge (APDBD) on different implant surfaces with regard to physical changes, bacterial decontamination, and osteoblast adhesion. Materials and Methods: Seven hundred twenty disks with three different surface topographies- machined (MAC), titanium plasma-sprayed (TPS), and zirconia-blasted and acid-etched (ZRT)-were tested in this experiment. Bacterial adhesion tests were performed repeatedly on a simplified biofilm of Streptococcus mitis. Bacteria were incubated in the presence of the samples, which were subsequently either left untreated as controls or treated with APDBD for 30, 60, and 120 seconds. Samples were then metalized, prior to the recurring acquisition of images using a scanning electronic microscope (SEM). Protein adsorption, surface wettability, and early biologic response were determined for both treated (120 seconds) and untreated implant surfaces. For depicting the eukaryotic cell behavior, preosteoblastic murine cells were used. Cells were conveniently stained, and nuclei were counted. Cell viability was assessed by a chemiluminescent assay at 1, 2, and 3 days. Results: On all treated samples, values of the contact angle measurements were lower than 10 degrees. The untreated samples showed values of contact angle of 80, 100, and 110 degrees, respectively, for MAC, TPS, and ZRT. The protein adsorption on TPS and ZRT was significantly increased after the plasma of argon treatment. However, no significant effect was noted on the MAC disks. The number and the cell spreading area of adherent osteoblasts significantly increased in all treated surfaces. Nonetheless, argon treatment did not influence the osteoblast proliferation and viability at different time points. Bacteria adhesion was significantly reduced, even after 60 seconds of argon treatment. Conclusion: Preliminary data showed that argon atmospheric pressure dielectric barrier discharge disinfected the implant surface, with potential to promote osteoblast attachment and spreading, suggesting this may be a possible approach to clean a peri-implantitis-contaminated implant surface. Keywords: microbiology, peri-implantitis, plasma of argon

Purpose: To analyze and compare the frequency, type, and location of maxillary sinus septa in patients with a dentate and an edentulous posterior maxilla using cone beam computed tomography (CBCT) imaging. Materials and Methods: The study consisted of 100 maxillary sinuses: 50 from patients with a dentate and 50 from patients with an edentulous posterior maxilla. The aim was to assess the frequency, morphology, and location of maxillary sinus septa in axial, sagittal, and coronal CBCT images. Images were only included in this study provided that patients were older than 30 years of age, at least one maxillary sinus was completely visible in the field of view (FOV), and the sinus membrane exhibited a mucosal thickening of a maximum 4 mm. Differences regarding age, sex, side, septa location, and type of dentition (dentate/ edentulous posterior maxilla) were analyzed. Results: The mean age of the 100 patients (66 women, 34 men) was 58.3 years. A total of 60 sinus septa were found in exactly half of the evaluated sinuses. The major part of the septa was found on the floor of the maxillary sinus (n = 34/56.7%). Of these, the majority was located in the posterior maxilla in the region of the second molars (n = 27/79.4%). The most common orientation of the septa was coronal (63.3%), followed by septa in relation to the infraorbital canal (23.3%). Regarding the status of the dentition in the posterior maxilla in relation to the distribution of sinus septa, septa were present in 26 (52%) dentate and in 24 (48%) edentulous regions. Thus, for a potential influence of the status of the dentition in the posterior maxilla on the frequency of sinus septa, no significant impact was found (P = .69). Conclusion: Sinus septa are frequent anatomical structures, and are found equally often in patients with a dentate and an edentulous posterior maxilla. This is of clinical relevance, as patients with missing teeth in the posterior area of the maxilla are often in need of a sinus floor elevation (SFE) procedure when dental implant placement is intended. As sinus septa are reported to be an important reason for surgical complications during SFE, a three-dimensional radiographic examination using CBCT prior to surgery might be helpful for diagnostic evaluation and treatment planning. Keywords: cone beam computed tomography, dentate posterior maxilla, edentulous posterior maxilla, interobserver reliability, maxillary sinus septa

Purpose: Manufacturers have inserted a prosthetic index, an internal hexagon to guide prosthetic components inside Morse taper implants. However, it is still unclear if this mechanism could decrease the mechanical strength of Morse taper implants. The aim of this study was to evaluate the influence of the prosthetic index inside Morse taper implants on fracture resistance compared with nonindexed implants. Materials and Methods: Fifty-seven Morse taper implants, with 11.5-degree angulation of the internal conical portion, were divided into three groups: implants without the prosthetic index and solid Morse taper universal post (group 1), implants with the prosthetic index and solid Morse taper universal post (group 2), and implants and abutments with the prosthetic index (group 3). All groups were modeled for finite element stress analysis (FEA), simulating force application of a perpendicular load to the abutments. Fracture resistance (n = 10) was determined under the same condition. Dynamic loading (n = 9) was also performed. The statistical analysis was performed using one-way analysis of variance (ANOVA), and the Tukey test was applied (α = .05). The metallographic analysis was used to identify the fracture distribution and the microstructure of the titanium alloy. Results: There was no statistically significant difference between the values of all tested groups. According to the FEA, the prosthetic index region was out of stress. The mean fracture resistances and loading test were 353.7 N and 200 N for group 1, 397.3 N and 170 N for group 2, and 372.0 N and 160 N for group 3, respectively. Metallographic analysis showed a macroscopic failure pattern just as demonstrated by FEA. Conclusion: The presence of the prosthetic index on Morse taper implants did not decrease its resistance to fracture for the tested implants. Keywords: biomechanics, dental implants, mechanical stress, prosthetic index

Purpose: To test the antimicrobial properties, surface topography, reaction of surrounding tissue (biocompatibility), and osseointegration of ultrathin implant surfaces containing polysiloxane and nanoscaled silver particles. Materials and Methods: Implants with polysiloxane coating and nanoscaled silver particles (Ag/SiOxCy; HyProtect, Bio-Gate) were compared with implants with polysiloxane coating alone and with noncoated (grit-blasted and acid-etched) implants. A total of 72 implants were inserted into the calvaria of eight domestic pigs (nine implants each, three of each type). After 3 months, histologic sections were evaluated for inflammatory cell infiltration and bone implant contact. Results: Roughness parameters did not differ between all three implant types. The Ag/SiOxCy coating exhibited a good antimicrobial effect in vitro and no sign of inflammatory cell infiltration in vivo. The noncoated implants demonstrated 10.85% and 14.48% more bone contact than the polysiloxane-coated implants (P = .003) and the Ag/SiOxCy‑coated implants (P ≤ .001), respectively. Osseointegration was not significantly different between the Ag/SiOxCy‑coated and polysiloxane-coated implants (P = .72). Conclusion: The osseointegration capability of the Ag/SiOxCy-coated implants was equal to that of the polysiloxane-coated implants but less than that of the grit-blasted and acid-etched implants. Because of the biocompatibility of the polysiloxane coating, further studies should be conducted in load-bearing models and in the oral cavity to investigate the antimicrobial effect of the embedded silver clusters. Keywords: implant coating, implant surface, in vivo model, polysiloxane coating, silver coating

Purpose: Osseointegrated implants have been shown to transmit a certain sensibility termed as osseoperception. The purpose of this study was to determine the perception by implants over a period of 6 months after loading in comparison to the natural dentition. Materials and Methods: Twenty subjects (ages 40 to 50 years) were included in this split-mouth clinical trial. The subjects were divided into two groups (n = 10) as follows: group 1-subjects with recently cemented implant-supported fixed prosthesis opposing natural teeth; group 2-subjects with recently cemented implant-supported fixed prosthesis in both arches. The implant-supported prostheses were considered as the test sites, whereas natural teeth on the contralateral side were considered as the control. Articulating papers of varied thickness were placed interocclusally in the posterior region in a predetermined random order of true and false insertions. The subjects' ability to perceive the presence/absence of the test papers was recorded for every insertion. The evaluation was performed immediately after cementation and at 1 week, 3 months, and 6 months after cementation. The minimum interocclusal thickness detected by the subjects at the test and control sites at different time intervals was used for further analysis. Results: All subjects with implant-supported prostheses perceived a certain thickness of articulating paper. The minimum interocclusal thickness detected by the implant-supported prosthesis decreased postloading; however, the difference was not statistically significant (P > .008). At the end of the follow-up period, the minimum interocclusal thickness detected by the implants in group 1 was similar to the controls, whereas it was significantly higher than the controls in group 2 (P .05). Conclusion: There was progressive improvement in the perception by implant-supported prostheses during the follow-up period, and it was nearing the perception by natural teeth in subjects with implants opposing natural teeth. Keywords: active tactile perception, dental implants, minimum interocclusal thickness

Purpose: To evaluate biologic and prosthetic outcomes of implant-supported mandibular full-arch fixed prostheses treated with the All-on-4 treatment concept after 7 years. Materials and Methods: Patients were selected to receive full-arch fixed immediate prostheses supported by four implants up to 72 hours after surgery. The following biologic aspects were evaluated: Plaque Index (PI) and Bleeding Index (BI), implant stability by resonance frequency, and marginal bone loss (MBL) measured with the aid of periapical radiographs. The prosthetic complications evaluated were related to screw loosening, framework or acrylic teeth fractures, or fractures of implants. The means of implant stability and MBL were subjected to analysis of variance and the Tukey test (P .05). For PI and BI, the Friedmann test was used (P .05). Results: Sixteen patients (12 women and 4 men; mean age: 59.1 years) received 64 implants, and in all patients, two implants were positioned axially at the incisor region and two distally tilted implants at the region of the second premolars or molars. Patients were evaluated immediately after surgery and at 1, 2, and 7 years. Fifteen patients attended the recall after 2 years; one patient could not attend the scheduled follow-up visit and was excluded from the sample. In the 7-year evaluation, the sample size decreased to 12 patients; one could not attend because of a severe disease, and two were deceased. The cumulative implant survival rate was 100%. There was a significant (P .0162) decrease in PI at the 1- and 7-year evaluations (71.87% and 47.92%, respectively), while the BI was the same at 1 and 7 years (43.75%). There was no statistical difference in MBL (P = .12) and implant stability (P = .48) between axial and tilted implants (P = .48). The survival rate of prostheses was 100%. The following technical complications were observed: tooth fracture occurred in one patient (6.25%); loosening of prosthetic screws and abutments were observed in three patients (18.75%); after 5 years, three patients (18.75%) had changed the denture acrylic teeth because of the replacement of the removable total maxillary prostheses with fixed implant prostheses. Conclusion: For the 12 patients who attended the recall after 7 years, implant loss was not found, the implant stability was high, MBL was low, and prosthetic complications were easily solved. Thus, it can be concluded that rehabilitation with implant-supported mandibular full-arch fixed prostheses with four implants has proved to be a treatment with a high survival rate. Keywords: bone loss, dental implant, immediate loading, mandible, tilted implant

Purpose: To assess the success and stability of 6-, 7-, 8-, and 9-mm-long, 6.5-mm-wide-neck tissue-level implants placed at the time of transalveolar sinus augmentation therapy, utilizing a trephine and osteotome approach, which were restored with single crowns. Materials and Methods: In total, 1,344 implants were placed by the author, varying in length from 6 to 9 mm, with parallel-wall 4.8-mm-diameter implant bodies and 6.5-mm-diameter implant necks. The implants were restored with single abutments and crowns by a variety of practitioners. They were followed for 60 to 229 months in function, with a mean time of 121.1 months in function. Implant success was evaluated by the author utilizing a combination of the Albrektsson et al criteria, and buccal and palatal/lingual bone sounding under anesthesia. Results: The overall cumulative success rate was 98.8%. One hundred ninety 6-mm-long implants demonstrated a cumulative success rate of 97.5% at a mean time of 109.2 months in function. Eleven 7-mm-long implants demonstrated a cumulative success rate of 100% at a mean time of 218.5 months in function. One thousand ninety-four 8-mm-long implants demonstrated a cumulative success rate of 98.9% at a mean time of 112.3 months in function. Forty-nine 9-mm-long implants demonstrated a cumulative success rate of 100% at a mean time of 212.1 months in function. Conclusion: Implants of 6 to 9 mm in length, placed at the time of trephine and osteotome transalveolar sinus elevation procedures and restored with abutments and single crowns, demonstrate a high level of long-term clinical success, assuming specific comprehensive treatment criteria are met. Keywords: implant success, osteotomes, shorter implants, sinus augmentation, trephines

Purpose: The need for dental implants is increasing, and supportive periodontal treatment can achieve long-term success and prevent peri-implantitis. Contributing factors to noncompliance with long-term scheduled supportive periodontal treatment remain unclear. To investigate whether demographic and clinical characteristics are associated with noncompliance, the authors analyzed data for patients who had received dental implants. Materials and Methods: The authors recruited patients participating in a supportive periodontal treatment program after receiving permanent prostheses on implants placed from 2005 to 2013. Demographic data and dental treatment histories were collected. Compliance was defined as a record of participation in a standard supportive periodontal treatment program for at least 1 year. The chi-square test, log-rank test, Kaplan-Meier survival curve, and Cox proportional hazards model were used for statistical analysis. Results: The study included 120 patients (259 implants, 60% compliance). The two groups (compliant and noncompliant) differed significantly in frequency distributions for sex (P = .0017), educational level (P = .0325), and histories of substance use (P = .0016), periodontitis (P = .0005), and root planing or flap surgery (P = .0002). The Kaplan-Meier survival curves and log-rank test showed that increases in cumulative continuation rates were significantly associated with male sex (P = .0025); body mass index ≥ 24 kg/m2 (P = .0093); and a history of periodontitis (P .0001), root planing or flap surgery (P .0001), and substance use (P = .0026). Multivariate Cox proportional hazards model for supportive periodontal treatment noncompliance showed significantly higher compliance in patients who had received root planing or flap surgery (hazard ratio = 0.26, 95% confidence interval = 0.12 to 0.53, P = .0002). Conclusion: These results suggest that in patients who received a permanent prosthesis on implant placement, root planing or flap surgery was the crucial factor in determining compliance with supportive periodontal treatment. However, well-designed large-scale studies with a larger sample size are needed to confirm the findings of this study. Keywords: compliance, cumulative continuation rates, implant, supportive periodontal treatment

Purpose: The purpose of this retrospective study was to provide practice-based evidence to determine if the consistency of dental hygiene therapy, despite utilizing instrumentation literature that has proven to cause alterations to implant surfaces, affects peri-implant health or survival. Materials and Methods: The study sample comprised patients with implant-supported full-arch fixed dental prostheses who were distributed into two groups. The consistent hygiene group patients had dental hygiene therapy at a minimum biannually and were exposed to at least three dental hygiene instrument materials. The inconsistent hygiene group patients had dental hygiene therapy at a minimum once every 3 to 10 years and were exposed to at least three dental hygiene instrument materials. Years of survival free of soft tissue pathology and/or implant failure were estimated. Continuous features were summarized with medians, interquartile ranges (IQRs), and ranges; categorical features were summarized with frequency counts and percentages. Results: Among 48 patients in the consistent hygiene group, 11 patients experienced soft tissue pathology or implant failure at a median of 11.3 years; among 99 patients in the inconsistent hygiene group, 17 patients experienced soft tissue pathology or implant failure at a median of 4.8 years. The survival free of soft tissue pathology or implant failure rate at 5 years was 94% for the consistent hygiene group and 91% for the inconsistent hygiene group. The survival free of soft tissue pathology or implant failure rate at 20 years was 70% for the consistent hygiene group and 79% for the inconsistent hygiene group (P = .91). Conclusion: Although no statistical differences were found between the groups, this practice-based evidence suggests more consistent dental hygiene therapy increases the median in years in which soft tissue pathology or implant failure is present. Keywords: dental implants, dental prophylaxis, dental prosthesis implant-supported, dental scaling

Purpose: The aim of this 1-year randomized trial was to evaluate and compare the clinical and radiographic performance of four immediately loaded mini dental implants (MDIs) and two immediately loaded standard-sized tissue-level (STL) implants, placed in the interforaminal region of the mandible and used to retain mandibular overdentures (IODs) in completely edentulous patients. Materials and Methods: A total of 50 completely edentulous patients wearing conventional maxillary dentures and complaining about insufficient retention of their mandibular dentures were divided into two groups; 25 patients received four MDIs and 25 patients received two STL implants. The marginal bone loss (MBL) at the mesial and distal sides of each implant was assessed by means of standardized intraoral radiographs after a period of 1 year. Implant success and survival rates were also calculated. Results: Immediate loading was possible for all patients in the first group. In the second group, an immediate loading protocol could not be applied for 10 patients. These patients were treated with a delayed loading protocol. A mean MBL of 0.42 ± 0.56 mm for the MDIs and 0.54 ± 0.49 mm for the immediately loaded STL implants was recorded at the end of the evaluation period. There was no statistically significant difference between the MDIs and the immediately loaded STL implants. Two MDIs failed, resulting in a survival rate of 98%. The success rate was 91%. For the immediately loaded conventional implants, the survival rate was 100% and the success rate 96.7% after 1 year of function. However, in 10 patients, the immediate loading protocol could not be followed. Conclusion: Considering the limitations of this short-term clinical study, immediate loading of four unsplinted MDIs or two splinted STL implants to retain mandibular overdentures seems to be a feasible treatment option. The marginal bone level changes around the MDIs were well within the clinically acceptable range. Keywords: immediate loading, implant overdentures, marginal bone loss, mini dental implants

Purpose: Recent case reports suggest that amnion-chorion membranes (ACM) and dense polytetrafluoroethylene membranes (dPTFE) can be left exposed during ridge preservation. The aim of this study was to compare the effectiveness of these membranes in ridge preservation, particularly when they are intentionally left exposed. Materials and Methods: A split-mouth, single-blind, randomized trial design was used to compare treatments with the two membranes in 22 nonmolar sites on the same arch. Ridge dimensions were recorded clinically and with cone beam computed tomography prior to and 3 months after ridge preservation. Postoperative discomfort was recorded with Visual Analog Scale (VAS) forms. Mixed‑model analysis of variance was used to test significance. Results: Clinical and radiographic ridge dimensions were not significantly different between the two treatments. ACM sites had significantly more osteoid and higher bone volume density but significantly less graft particles and bone surface density compared with dPTFE. Mineralized bone area and soft tissue area were not significantly different between the two treatments. ACM sites had significantly lower postoperative VAS scores compared with dPTFE. Conclusion: Intentionally exposed ACM is equally effective in ridge preservation compared with dPTFE. Additionally, ACM use may aid in reducing postoperative VAS scores, and potentially result in better quality of bone available for implant placement, as evidenced by improved histomorphometric measures. Keywords: amnion-chorion membrane, cone beam computed tomography, dense PTFE, histomorphometry, microtomography, RCT, ridge preservation

Purpose: To report on the outcome of placement of two bilateral zygomatic implants with an immediately loaded prosthesis. Materials and Methods: A retrospective chart review was conducted of all patients treated with zygomatic implants between August 1, 2011 and June 6, 2016. All patients had at least two zygomatic implants placed bilaterally and immediately loaded with a provisional prosthesis the same day of implant placement. The implants were Nobel Biocare TiUnite or machined surface with lengths of 30 to 52.5 mm. All patients were treated by a team consisting of one surgeon, a restorative dentist or prosthodontist, an anesthesiologist, and a laboratory technician. Implant success was defined as successful integration of the implant; prosthetic success was defined as retention of the prosthesis under normal function. Results: One hundred five zygomatic implants were placed and immediately loaded in 28 patients over a period of 1 to 60 months. Ages ranged from 46 to 81 years, with 26 female and 2 male patients. All the implants were placed by one surgeon. The immediate load on the day of implant placement was completed by either one of 2 prosthodontists or 11 restorative dentists. Implant success was 96% (101/105). All four failed implants were in one patient and were TiUnite surface coated. Conclusion: This study demonstrated that two zygomatic implants bilaterally placed and immediately loaded with a full-arch splinted prosthesis will provide a predictable outcome. Keywords: graftless solution, immediate load, zygoma, zygomatic implants

Purpose: To determine the survival rate of implants placed in different craniofacial locations and factors affecting survival. Materials and Methods: This study retrospectively reviewed a consecutive series of patients treated at the Royal Melbourne Hospital who received craniofacial implants for an array of benign and malignant conditions. Implant survival per site and cumulative survival were determined. Surgical and implant variables were assessed using the Kaplan-Meier and Cox Proportional Hazards Models. Results: Fifty-two patients had 156 implants placed to reconstruct the nose, orbit, and ears. A total of 43 implants failed (overall survival: 72.4%) in the orbital (29/63, failure rate: 46%) and auricular sites (14/70, failure rate: 17%). No implants failed in the nasal site (0/9). Three-, 5-, and 10-year cumulative survival was also determined. Independent risk factors for decreased survival included postoperative radiation therapy (P = .005, RR: 3.2, 95% CI: 1.4 to 7.0), implants placed in the orbit (P = .004, RR: 5.0, 95% CI: 1.6 to 15.2), and implants that were not loaded with a prosthesis (P = .007, RR: 2.7, 95% CI: 1.3 to 5.4). Conclusion: Failure rates varied according to site in this cohort of patients. A number of independent risk factors affecting implant survival in extraoral sites were identified. Keywords: craniofacial, endosseous, extraoral, implant, osseointegrated, survival

Purpose: To evaluate the effect of titanium (Ti) particles on oral epithelial cell homeostasis and the potential of dental implants to release Ti debris upon insertion. Materials and Methods: Dental implants with varying surface treatments were employed to determine the feasibility of particle release during implant placement as well as the impact of free Ti debris on oral epithelial cells. Ti particles derived from implant surfaces were isolated and cultured in direct contact with normal oral epithelial cells for 48 hours. Further, cells were fixed and processed for immunofluorescence assay to detect the activation of the DNA damage response (DDR) using CHK2 and BRCA1 molecular markers. Positive cells demonstrating DNA damage were quantified and statistically analyzed. Results: Ti particles derived from implants containing phosphate-enriched titanium oxide (PETO), fluoride-modified (FM), and grit-blasted (GB) surface treatments were able to activate CHK2 and trigger the recruitment of BRCA1 in oral epithelial cells. Also, implants with GB surfaces were able to release Ti particles upon implant placement. Conclusion: The results indicate that Ti debris may be detached from the implant surface upon placement. Also, free Ti particles can trigger DDR signaling in oral epithelial cells. These findings suggest that Ti particles/debris released into a surgical wound may contribute to the disruption of epithelial homeostasis, and potentially compromise the oral epithelial barrier. Keywords: dental implants, DNA damage, peri-implantitis, titanium

Osseointegrated craniofacial implants have improved retention and patients' perceptions of implant-retained nasal prostheses; however, the determination of the available bone sites for implant placement post-rhinectomy is difficult. This case report describes the use of cone beam computed tomography scanning and computer-assisted virtual planning in conjunction with digital photographs for rehabilitation of a facial defect with an implant-retained silicon nasal prosthesis. Two implants were planned in the anatomical area with adequate bone volume to achieve favorable cosmetic outcomes and accessibility for hygiene maintenance. The implant-retained nasal prosthesis resulted in a meaningful improvement in the esthetics without the need for plastic surgery. In such cases, the post-rhinectomy reconstruction surgery should be limited to preparation of the surgical defect area for an implant-retained prosthesis. Silicone prostheses are reliable alternatives to surgery and should be considered in selected cases. Keywords: bar attachment, implant retained, maxillofacial prosthesis, nasal prosthesis

Papillon-Lefèvre syndrome (PLS) is a rare autosomal recessive disorder of keratinization associated with palmoplantar keratoderma and severe periodontitis resulting in complete edentulism in late adolescence. The pathognomonic dental features of PLS are pathologic migration, hypermobility, and exfoliation of the teeth without any signs of root resorption. It has been suggested that an effective way to treat PLS patients presenting early in the disease progression is extraction of the erupted primary dentition or hopeless permanent teeth followed by antibiotic coverage with periodontal therapy for the remaining teeth. Unfortunately, studies have shown that this regimen only temporarily delays the progression of periodontal disease and does not prevent further tooth loss and bone destruction in the long term. Post-tooth loss, atrophic ridges make conventional prosthodontic rehabilitation quite challenging, and more recently, implant-supported prostheses have been considered as a viable alternative. In a PLS patient, implant placement is complicated by inadequate bone volume; thus, bone augmentation techniques or the use of short implants is often considered. When large volumes of bone are required, parietal calvarium bone can be used to predictably reconstruct severe defects. A PLS patient aged 21 years presented a chief complaint of ill-fitting conventional complete dentures. The patient had severely atrophic ridges, requiring significant bone augmentation for an implant-supported prosthesis. The present case is the first example of bone augmentation using autogenous calvarium parietal graft followed by endosseous implant placement and prosthetic restoration in a PLS patient. Keywords: bone graft, case report, dental implants, Papillon-Lefèvre syndrome/rehabilitation

Purpose: Evidence on the outcomes of functional loading placed in recombinant human bone morphogenetic protein 2 (rhBMP-2)/acellular collagen sponge (ACS)-induced bone is lacking. The aim of this study was to verify whether guided bone regeneration (GBR) with rhBMP-2/ACS enhances regeneration of missing bone and osseointegration of dental implants subject to functional loading. Materials and Methods: Two bilateral standardized large saddle-type defects (~10 × 10 × 6 mm) were surgically created in each mandible of seven beagle dogs 2 months after tooth extraction. Defects were immediately reconstructed randomly using rhBMP-2 (O-BMP or InFuse) soaked in ACS, deproteinized bovine bone mineral (DBBM) granules, or ACS alone as surgical control and subsequently covered with collagen membrane. Screw-type sand-blasted, acid-etched dental implants were placed 3 months later into the reconstructed defects and into adjacent bone. Osseointegration was allowed to progress for 3 months before functional loading of 3 months until sacrifice. Results: Significantly more bone fill was radiographically observed for GBR with rhBMP-2/ACS (O-BMP: 92.5%, InFuse: 79%) in comparison to the DBBM (52%) and ACS alone groups (56.6%). Osseointegration was achieved and maintained in all experimental defects challenged by prostheses-driven functional load. The bone density ranged from 37.49% in the ACS group to 64.9% in the rhBMP-2/ACS (InFuse) group with no significance. The highest mean percentage of BIC was found in rhBMP-2/ACS (InFuse: 52.98%) with no statistical difference. Crestal bone resorption was observed around implants placed in reconstructed areas without any significant difference. Conclusion: GBR with rhBMP-2/ACS provided the greatest bone fill among the three treatment procedures. GBR with rhBMP-2/ACS showed efficacy for placement, osseointegration, and functional loading of titanium implants in alveolar ridge defects. Keywords: alveolar ridge augmentation, dental implants, functional loading, guided bone regeneration, rhBMP-2